Impact of non-ideal analyte behavior on the separation of protein aggregates by asymmetric flow field-flow fractionation.

PubMed

Boll, Björn; Josse, Lena; Heubach, Anja; Hochenauer, Sophie; Finkler, Christof; Huwyler, Jörg; Koulov, Atanas V

2018-04-25

Asymmetric flow field-flow fractionation is a valuable tool for the characterization of protein aggregates in biotechnology owing to its broad size range and unique separation principle. However, in practice asymmetric flow field-flow fractionation is non-trivial to use due to the major deviations from theory and the influence on separation by various factors that are not fully understood. Here we report methods to assess the non-ideal effects that influence asymmetric flow field-flow fractionation separation and for the first time identify experimentally the main factors that impact it. Furthermore, we propose new approaches to minimize such non-ideal behavior, showing that by adjusting the mobile phase composition (pH and ionic strength) the resolution of asymmetric flow field-flow fractionation separation can be drastically improved. Additionally, we propose a best practice method for new proteins. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng

An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the firstmore » exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.« less

Mathematical models of continuous flow electrophoresis: Electrophoresis technology

NASA Technical Reports Server (NTRS)

Saville, Dudley A.

1986-01-01

Two aspects of continuous flow electrophoresis were studied: (1) the structure of the flow field in continuous flow devices; and (2) the electrokinetic properties of suspended particles relevant to electrophoretic separations. Mathematical models were developed to describe flow structure and stability, with particular emphasis on effects due to buoyancy. To describe the fractionation of an arbitrary particulate sample by continuous flow electrophoresis, a general mathematical model was constructed. In this model, chamber dimensions, field strength, buffer composition, and other design variables can be altered at will to study their effects on resolution and throughput. All these mathematical models were implemented on a digital computer and the codes are available for general use. Experimental and theoretical work with particulate samples probed how particle mobility is related to buffer composition. It was found that ions on the surface of small particles are mobile, contrary to the widely accepted view. This influences particle mobility and suspension conductivity. A novel technique was used to measure the mobility of particles in concentrated suspensions.

Geologic field-trip guide to Medicine Lake Volcano, northern California, including Lava Beds National Monument

USGS Publications Warehouse

Donnelly-Nolan, Julie M.; Grove, Timothy L.

2017-08-17

Medicine Lake volcano is among the very best places in the United States to see and walk on a variety of well-exposed young lava flows that range in composition from basalt to rhyolite. This field-trip guide to the volcano and to Lava Beds National Monument, which occupies part of the north flank, directs visitors to a wide range of lava flow compositions and volcanic phenomena, many of them well exposed and Holocene in age. The writing of the guide was prompted by a field trip to the California Cascades Arc organized in conjunction with the International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) quadrennial meeting in Portland, Oregon, in August of 2017. This report is one of a group of three guides describing the three major volcanic centers of the southern Cascades Volcanic Arc. The guides describing the Mount Shasta and Lassen Volcanic Center parts of the trip share an introduction, written as an overview to the IAVCEI field trip. However, this guide to Medicine Lake volcano has descriptions of many more stops than are included in the 2017 field trip. The 23 stops described here feature a range of compositions and volcanic phenomena. Many other stops are possible and some have been previously described, but these 23 have been selected to highlight the variety of volcanic phenomena at this rear-arc center, the range of compositions, and for the practical reason that they are readily accessible. Open ground cracks, various vent features, tuffs, lava-tube caves, evidence for glaciation, and lava flows that contain inclusions and show visible evidence of compositional zonation are described and visited along the route.

Inductively coupled plasma-mass spectrometry as an element-specific detector for field-flow fractionation particle separation

USGS Publications Warehouse

Taylor, Howard E.; Garbarino, John R.; Murphy, Deirdre M.; Beckett, Ronald

1992-01-01

An inductively coupled plasma-mass spectrometer was used for the quantitative measurement of trace elements In specific,submicrometer size-fraction particulates, separated by sedimentation field-flow fractionation. Fractions were collected from the eluent of the field-flow fractionation centrifuge and nebulized, with a Babington-type pneumatic nebulizer, into an argon inductively coupled plasma-mass spectrometer. Measured Ion currents were used to quantify the major, minor, and trace element composition of the size-separated colloidal (< 1-microm diameter) particulates. The composition of surface-water suspended matter collected from the Yarra and Darling rivers in Australia is presented to illustrate the usefulness of this tool for characterizing environmental materials. An adsorption experiment was performed using cadmium lon to demonstrate the utility for studying the processes of trace metal-suspended sediment interactions and contaminant transport in natural aquatic systems.

Experiments and numerical simulations of flow field and heat transfer coefficients inside an autoclave model

NASA Astrophysics Data System (ADS)

Ghamlouch, T.; Roux, S.; Bailleul, J.-L.; Lefèvre, N.; Sobotka, V.

2017-10-01

Today's aerospace industrial first priority is the quality improvement of the composite material parts with the reduction of the manufacturing time in order to increase their quality/cost ratio. A fabrication method that could meet these specifications especially for large parts is the autoclave curing process. In fact the autoclave molding ensures the thermal control of the composite parts during the whole curing cycle. However the geometry of the tools as well as their positioning in the autoclave induce non uniform and complex flows around composite parts. This heterogeneity implies non-uniform heat transfers which can directly impact on part quality. One of the main challenges is therefore to describe the flow field inside an autoclave as well as the convective heat transfer from the heated pressurized gas to the composite part and the mold. For this purpose, and given the technical issues associated with instrumentation and measurements in actual autoclaves, an autoclave model was designed and then manufactured based on similarity laws. This tool allows the measurement of the flow field around representative real industrial molds using the PIV technique and the characterization of the heat transfer thanks to thermal instrumentation. The experimental results are then compared with those derived from numerical simulations using a commercial RANS CFD code. This study aims at developing a semi-empirical approach for the prediction of the heat transfer coefficient around the parts and therefore predicts its thermal history during the process with a view of optimization.

Ferromagnetic effects for nanofluid venture through composite permeable stenosed arteries with different nanosize particles

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher; Mustafa, M. T.

2015-07-01

In the present article ferromagnetic field effects for copper nanoparticles for blood flow through composite permeable stenosed arteries is discussed. The copper nanoparticles for the blood flow with water as base fluid with different nanosize particles is not explored upto yet. The equations for the Cu-water nanofluid are developed first time in literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been evaluated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. Effect of various flow parameters on the flow and heat transfer characteristics are utilized.

Two-phase magnetoconvection flow of magnetite (Fe3O4) nanoparticles in a horizontal composite porous annulus

NASA Astrophysics Data System (ADS)

Abbas, Zaheer; Hasnain, Jafar

A numerical study is performed to examine the two-phase magnetoconvection and heat transfer phenomena of Fe3O4 -kerosene nanofluid flow in a horizontal composite porous annulus with an external magnetic field. The annulus is filled with immiscible fluids flowing between two concentric cylinders. The governing equations of the flow problem are obtained using Darcy-Brinkman model. Heat transfer is analyzed in the presence of viscous and Darcian dissipation terms. The shooting method is used as a tool to solve the obtained non-linear ordinary differential equations for the velocity and temperature profiles. The velocity and temperature distributions are analyzed and discussed under the influence of involved flow parameters with the aid of graphs. It is found that both velocity and temperature of fluid are decreased with ferroparticle volume fraction. In addition to that, it is also presented that the existence of magnetic field decreases the benefit of ferrofluids in heat transfer progression.

Three-dimensional investigations of the threading regime in a microfluidic flow-focusing channel

NASA Astrophysics Data System (ADS)

Gowda, Krishne; Brouzet, Christophe; Lefranc, Thibault; Soderberg, L. Daniel; Lundell, Fredrik

2017-11-01

We study the flow dynamics of the threading regime in a microfluidic flow-focusing channel through 3D numerical simulations and experiments. Making strong filaments from cellulose nano-fibrils (CNF) could potentially steer to new high-performance bio-based composites competing with conventional glass fibre composites. CNF filaments can be obtained through hydrodynamic alignment of dispersed CNF by using the concept of flow-focusing. The aligned structure is locked by diffusion of ions resulting in a dispersion-gel transition. Flow-focusing typically refers to a microfluidic channel system where the core fluid is focused by the two sheath fluids, thereby creating an extensional flow at the intersection. In this study, threading regime corresponds to an extensional flow field generated by the water sheath fluid stretching the dispersed CNF core fluid and leading to formation of long threads. The experimental measurements are performed using optical coherence tomography (OCT) and 3D numerical simulations with OpenFOAM. The prime focus is laid on the 3D characteristics of thread formation such as wetting length of core fluid, shape, aspect ratio of the thread and velocity flow-field in the microfluidic channel.

Development of the 1990 Kalapana Flow Field, Kilauea Volcano, Hawaii

USGS Publications Warehouse

Mattox, T.N.; Heliker, C.; Kauahikaua, J.; Hon, K.

1993-01-01

The 1990 Kalapana flow field is a complex patchwork of tube-fed pahoehoe flows erupted from the Kupaianaha vent at a low effusion rate (approximately 3.5 m3/s). These flows accumulated over an 11-month period on the coastal plain of Kilauea Volcano, where the pre-eruption slope angle was less than 2??. the composite field thickened by the addition of new flows to its surface, as well as by inflation of these flows and flows emplaced earlier. Two major flow types were identified during the development of the flow field: large primary flows and smaller breakouts that extruded from inflated primary flows. Primary flows advanced more quickly and covered new land at a much higher rate than breakouts. The cumulative area covered by breakouts exceeded that of primary flows, although breakouts frequently covered areas already buried by recent flows. Lava tubes established within primary flows were longer-lived than those formed within breakouts and were often reoccupied by lava after a brief hiatus in supply; tubes within breakouts were never reoccupied once the supply was interrupted. During intervals of steady supply from the vent, the daily areal coverage by lava in Kalapana was constant, whereas the forward advance of the flows was sporadic. This implies that planimetric area, rather than flow length, provides the best indicator of effusion rate for pahoehoe flow fields that form on lowangle slopes. ?? 1993 Springer-Verlag.

Fluid dynamic aspects of jet noise generation

NASA Technical Reports Server (NTRS)

1974-01-01

The location of the noise sources within jet flows, their relative importance to the overall radiated field, and the mechanisms by which noise generation occurs, are studied by detailed measurements of the level and spectral composition of the radiated sound in the far field. Directional microphones are used to isolate the contribution to the radiated sound of small regions of the flow, and for cross-correlation between the radiated acoustic field and either the velocity fluctuations or the pressure fluctuations in the source field. Acquired data demonstrate the supersonic convection of the acoustic field and the resulting limited upstream influence of the signal source, as well as a possible increase of signal strength as it propagates toward the centerline of the flow.

Extensive young silicic volcanism produces large deep submarine lava flows in the NE Lau Basin

NASA Astrophysics Data System (ADS)

Embley, Robert W.; Rubin, Kenneth H.

2018-04-01

New field observations reveal that extensive (up to 402 km2) aphyric, glassy dacite lavas were erupted at multiple sites in the recent past in the NE Lau basin, located about 200 km southwest of Samoa. This discovery of volumetrically significant and widespread submarine dacite lava flows extends the domain for siliceous effusive volcanism into the deep seafloor. Although several lava flow fields were discovered on the flank of a large silicic seamount, Niuatahi, two of the largest lava fields and several smaller ones ("northern lava flow fields") were found well north of the seamount. The most distal portion of the northernmost of these fields is 60 km north of the center of Niuatahi caldera. We estimate that lava flow lengths from probable eruptive vents to the distal ends of flows range from a few km to more than 10 km. Camera tows on the shallower, near-vent areas show complex lava morphology that includes anastomosing tube-like pillow flows and ropey surfaces, endogenous domes and/or ridges, some with "crease-like" extrusion ridges, and inflated lobes with extrusion structures. A 2 × 1.5 km, 30-m deep depression could be an eruption center for one of the lava flow fields. The Lau lava flow fields appear to have erupted at presumptive high effusion rates and possibly reduced viscosity induced by presumptive high magmatic water content and/or a high eruption temperature, consistent with both erupted composition ( 66% SiO2) and glassy low crystallinity groundmass textures. The large areal extent (236 km2) and relatively small range of compositional variation ( σ = 0.60 for wt% Si02%) within the northern lava flow fields imply the existence of large, eruptible batches of differentiated melt in the upper mantle or lower crust of the NE Lau basin. At this site, the volcanism could be controlled by deep crustal fractures caused by the long-term extension in this rear-arc region. Submarine dacite flows exhibiting similar morphology have been described in ancient sequences from the Archaean through the Miocene and in small batches on present-day seafloor spreading centers. This study shows that extensive siliceous lavas can erupt on the modern seafloor under the right conditions.

Compositions for directed alignment of conjugated polymers

DOEpatents

Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

2016-04-19

Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

Design, fabrication and characterization of an arrayable all-polymer microfluidic valve employing highly magnetic rare-earth composite polymer

NASA Astrophysics Data System (ADS)

Rahbar, Mona; Shannon, Lesley; Gray, Bonnie L.

2016-05-01

We present a new magnetically actuated microfluidic valve that employs a highly magnetic composite polymer (M-CP) containing rare-earth hard-magnetic powder for its actuating element and for its valve seat. The M-CP offers much higher magnetization compared to the soft-magnetic, ferrite-based composite polymers typically used in microfluidic applications. Each valve consists of a permanently magnetized M-CP flap and valve seat mounted on a microfluidic channel system fabricated in poly(dimethylsiloxane) (PDMS). Each valve is actuated under a relatively small external magnetic field of 80 mT provided by a small permanent magnet mounted on a miniature linear actuator. The performance of the valve with different flap thicknesses is characterized. In addition, the effect of the magnetic valve seat on the valve’s performance is also characterized. It is experimentally shown that a valve with a 2.3 mm flap thickness, actuated under an 80 mT magnetic field, is capable of completely blocking liquid flow at a flow rate of 1 ml min-1 for pressures up to 9.65 kPa in microfluidic channels 200 μm wide and 200 μm deep. The valve can also be fabricated into an array for flow switching between multiple microfluidic channels under continuous flow conditions. The performance of arrays of valves for flow routing is demonstrated for flow rates up to 5 ml min-1 with larger microfluidic channels of up to 1 mm wide and 500 μm deep. The design of the valves is compatible with other commonly used polymeric microfluidic components, as well as other components that use the same novel permanently magnetic composite polymer, such as our previously reported cilia-based mixing devices.

Dielectrokinetic chromatography devices

DOEpatents

Chirica, Gabriela S; Fiechtner, Gregory J; Singh, Anup K

2014-12-16

Disclosed herein are methods and devices for dielectrokinetic chromatography. As disclosed, the devices comprise microchannels having at least one perturber which produces a non-uniformity in a field spanning the width of the microchannel. The interaction of the field non-uniformity with a perturber produces a secondary flow which competes with a primary flow. By decreasing the size of the perturber the secondary flow becomes significant for particles/analytes in the nanometer-size range. Depending on the nature of a particle/analyte present in the fluid and its interaction with the primary flow and the secondary flow, the analyte may be retained or redirected. The composition of the primary flow can be varied to affect the magnitude of primary and/or secondary flows on the particles/analytes and thereby separate and concentrate it from other particles/analytes.

Dielectrokinetic chromatography and devices thereof

DOEpatents

Chirica, Gabriela S; Fiechtner, Gregory J; Singh, Anup K

2014-04-22

Disclosed herein are methods and devices for dielectrokinetic chromatography. As disclosed, the devices comprise microchannels having at least one perturber which produces a non-uniformity in a field spanning the width of the microchannel. The interaction of the field non-uniformity with a perturber produces a secondary flow which competes with a primary flow. By decreasing the size of the perturber the secondary flow becomes significant for particles/analytes in the nanometer-size range. Depending on the nature of a particle/analyte present in the fluid and its interaction with the primary flow and the secondary flow, the analyte may be retained or redirected. The composition of the primary flow can be varied to affect the magnitude of primary and/or secondary flows on the particles/analytes and thereby separate and concentrate it from other particles/analytes.

Development of a steady potential solver for use with linearized, unsteady aerodynamic analyses

NASA Technical Reports Server (NTRS)

Hoyniak, Daniel; Verdon, Joseph M.

1991-01-01

A full potential steady flow solver (SFLOW) developed explicitly for use with an inviscid unsteady aerodynamic analysis (LINFLO) is described. The steady solver uses the nonconservative form of the nonlinear potential flow equations together with an implicit, least squares, finite difference approximation to solve for the steady flow field. The difference equations were developed on a composite mesh which consists of a C grid embedded in a rectilinear (H grid) cascade mesh. The composite mesh is capable of resolving blade to blade and far field phenomena on the H grid, while accurately resolving local phenomena on the C grid. The resulting system of algebraic equations is arranged in matrix form using a sparse matrix package and solved by Newton's method. Steady and unsteady results are presented for two cascade configurations: a high speed compressor and a turbine with high exit Mach number.

Compositional and volumetric development of a monogenetic lava flow field: The historical case of Paricutin (Michoacán, Mexico)

NASA Astrophysics Data System (ADS)

Larrea, Patricia; Salinas, Sergio; Widom, Elisabeth; Siebe, Claus; Abbitt, Robbyn J. F.

2017-12-01

Paricutin volcano is the youngest and most studied monogenetic volcano in the Michoacán-Guanajuato volcanic field (Mexico), with an excellent historical record of its nine years (February 1943 to March 1952) of eruptive activity. This eruption offered a unique opportunity to observe the birth of a new volcano and document its entire eruption. Geologists surveyed all of the eruptive phases in progress, providing maps depicting the volcano's sequential growth. We have combined all of those previous results and present a new methodological approach, which utilizes state of the art GIS mapping tools to outline and identify the 23 different eruptive phases as originally defined by Luhr and Simkin (1993). Using these detailed lava flow distribution maps, the volume of each of the flows was estimated with the aid of pre- and post-eruption digital elevation models. Our procedure yielded a total lava flow volume ranging between 1.59 and 1.68 km3 DRE, which is larger than previous estimates based on simpler methods. In addition, compositional data allowed us to estimate magma effusion rates and to determine variations in the relative proportions of the different magma compositions issued during the eruption. These results represent the first comprehensive documentation of the combined chemical, temporal, and volumetric evolution of the Paricutin lava field and provide key constraints for petrological interpretations of the nature of the magmatic plumbing system that fed the eruption.

Production waters associated with the Ferron coalbed methane fields, central Utah: Chemical and isotopic composition and volumes

USGS Publications Warehouse

Rice, C.A.

2003-01-01

This study investigated the composition of water co-produced with coalbed methane (CBM) from the Upper Cretaceous Ferron Sandstone Member of the Mancos Shale in east-central Utah to better understand coalbed methane reservoirs. The Ferron coalbed methane play currently has more than 600 wells producing an average of 240 bbl/day/well water. Water samples collected from 28 wellheads in three fields (Buzzards Bench, Drunkards Wash, and Helper State) of the northeast-southwest trending play were analyzed for chemical and stable isotopic composition.Water produced from coalbed methane wells is a Na-Cl-HCO3 type. Water from the Drunkards Wash field has the lowest total dissolved solids (TDS) (6300 mg/l) increasing in value to the southeast and northeast. In the Helper State field, about 6 miles northeast, water has the highest total dissolved solids (43,000 mg/l), and major ion abundance indicates the possible influence of evaporite dissolution or mixing with a saline brine. In the southern Buzzards Bench field, water has variable total dissolved solids that are not correlated with depth or spatial distance. Significant differences in the relative compositions are present between the three fields implying varying origins of solutes and/or different water-rock interactions along multiple flow paths.Stable isotopic values of water from the Ferron range from +0.9??? to -11.4??? ?? 18O and -32??? to -90??? ?? 2H and plot below the global meteoric water line (GMWL) on a line near, but above values of present-day meteoric water. Isotopic values of Ferron water are consistent with modification of meteoric water along a flow path by mixing with an evolved seawater brine and/or interaction with carbonate minerals. Analysis of isotopic values versus chloride (conservative element) and total dissolved solids concentrations indicates that recharge water in the Buzzards Bench area is distinct from recharge water in Drunkards Wash and is about 3 ??C warmer. These variations in isotopes along with compositional variations imply that the Ferron reservoir is heterogeneous and compartmentalized, and that multiple flow paths may exist. ?? 2003 Published by Elsevier B.V. All rights reserved.

Impact of Carrier Fluid Composition on Recovery of Nanoparticles and Proteins in Flow Field Flow Fractionation

PubMed Central

Schachermeyer, Samantha; Ashby, Jonathan; Kwon, MinJung; Zhong, Wenwan

2012-01-01

Flow field flow fractionation (F4) is an invaluable separation tool for large analytes, including nanoparticles and biomolecule complexes. However, sample loss due to analyte-channel membrane interaction limits extensive usage of F4 at present, which could be strongly affected by the carrier fluid composition. This work studied the impacts of carrier fluid (CF) composition on nanoparticle (NP) recovery in F4, with focus on high ionic strength conditions. Successful analysis of NPs in a biomolecules-friendly environment could expand the applicability of F4 to the developing field of nanobiotechnology. Recovery of the unfunctionalized polystyrene NPs of 199-, 102-, and 45-nm in CFs with various pH (6.2, 7.4 and 8.2), increasing ionic strength (0–0.1 M), and different types of co- and counter-ions, were investigated. Additionally, elution of the 85-nm carboxylate NPs and two proteins, human serum albumin (HSA) and immunoglobulin (IgG), at high ionic strengths (0–0.15 M) was investigated. Our results suggested that; 1) Electrostatic repulsion between the negatively charged NPs and the regenerated cellulose membrane was the main force to avoid particle adsorption on the membrane; 2) Larger particles experienced higher attractive force and thus were influenced more by variation in CF composition; and 3) Buffers containing weak anions or NPs with weak anion as the surface functional groups provided higher tolerance to the increase in ionic strength, owing to more anions being trapped inside the NP porous structure. Protein adsorption onto the membrane was also briefly investigated in salted CFs, using human serum albumin and immunoglobulin. We believe our findings could help to identify the basic carrier fluid composition for higher sample recovery in F4 analysis of nanoparticles in a protein-friendly environment, which will be useful for applying F4 in bioassays and in nanotoxicology studies. PMID:23058938

A record of igneous evolution in Elysium, a major martian volcanic province

PubMed Central

Susko, David; Karunatillake, Suniti; Kodikara, Gayantha; Skok, J. R.; Wray, James; Heldmann, Jennifer; Cousin, Agnes; Judice, Taylor

2017-01-01

A major knowledge gap exists on how eruptive compositions of a single martian volcanic province change over time. Here we seek to fill that gap by assessing the compositional evolution of Elysium, a major martian volcanic province. A unique geochemical signature overlaps with the southeastern flows of this volcano, which provides the context for this study of variability of martian magmatism. The southeastern lava fields of Elysium Planitia show distinct chemistry in the shallow subsurface (down to several decimeters) relative to the rest of the martian mid-to-low latitudes (average crust) and flows in northwest Elysium. By impact crater counting chronology we estimated the age of the southeastern province to be 0.85 ± 0.08 Ga younger than the northwestern fields. This study of the geochemical and temporal differences between the NW and SE Elysium lava fields is the first to demonstrate compositional variation within a single volcanic province on Mars. We interpret the geochemical and temporal differences between the SE and NW lava fields to be consistent with primary magmatic processes, such as mantle heterogeneity or change in depth of melt formation within the martian mantle due to crustal loading. PMID:28233797

Ferromagnetic CNT suspended H2O+Cu nanofluid analysis through composite stenosed arteries with permeable wall

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher

2015-08-01

In the present article magnetic field effects for CNT suspended copper nanoparticles for blood flow through composite stenosed arteries with permeable wall are discussed. The CNT suspended copper nanoparticles for the blood flow with water as base fluid is not explored yet. The equations for the CNT suspended Cu-water nanofluid are developed first time in the literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been evaluated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. Effect of various flow parameters on the flow and heat transfer characteristics is utilized. It is also observed that with the increase in slip parameter blood flows slowly in arteries and trapped bolus increases.

The length of channelized lava flows: Insight from the 1859 eruption of Mauna Loa Volcano, Hawai‘i

NASA Astrophysics Data System (ADS)

Riker, Jenny M.; Cashman, Katharine V.; Kauahikaua, James P.; Montierth, Charlene M.

2009-06-01

The 1859 eruption of Mauna Loa Volcano, Hawai'i, produced paired 'a'ā and pāhoehoe flows of exceptional length (51 km). The 'a'ā flow field is distinguished by a long (> 36 km) and well-defined pāhoehoe-lined channel, indicating that channelized lava remained fluid to great distances from the vent. The 1859 eruption was further unusual in initiating at a radial vent on the volcano's northwest flank, instead of along the well-defined rift zone that has been the source of most historic activity. As such, it presents an opportunity both to examine controls on the emplacement of long lava channels and to assess hazards posed by future flank eruptions of Mauna Loa. Here we combine evidence from historical chronicles with analysis of bulk compositions, glass geothermometry, and microlite textures of samples collected along the 1859 lava flows to constrain eruption and flow emplacement conditions. The bulk compositions of samples from the 'a'ā and pāhoehoe flow fields are bimodally distributed and indicate tapping of two discrete magma bodies during eruption. Samples from the pāhoehoe flow field have bulk compositions similar to those of historically-erupted lavas (< 8 wt.% MgO); lava that fed the 'a'ā channel is more primitive (> 8 wt.% MgO), nearly aphyric, and was erupted at high temperatures (1194-1216 °C). We suggest that the physical properties of proximal channel-fed lava (i.e., high-temperature, low crystallinity, and low bulk viscosity) promoted both rapid flow advance and development of long pāhoehoe-lined channels. Critical for the latter was the large temperature decrease (~ 50 °C) required to reach the point at which plagioclase and pyroxene started to crystallize; the importance of phase constraints are emphasized by our difficulty in replicating patterns of cooling and crystallization recorded by high-temperature field samples using common models of flow emplacement. Placement of the 1859 eruption within the context of historic activity at Mauna Loa suggests that the formation of radial vents and eruptions of high-temperature magma may not only be linked, but may also be a consequence of periods of high magma supply (e.g., 1843-1877). Flank eruptions could therefore warrant special consideration in models and hazard mitigation efforts.

Doppler-shifted fluorescence imaging of velocity fields in supersonic reacting flows

NASA Technical Reports Server (NTRS)

Allen, M. G.; Davis, S. J.; Kessler, W. J.; Sonnenfroh, D. M.

1992-01-01

The application of Doppler-shifted fluorescence imaging of velocity fields in supersonic reacting flows is analyzed. Focussing on fluorescence of the OH molecule in typical H2-air Scramjet flows, the effects of uncharacterized variations in temperature, pressure, and collisional partner composition across the measurement plane are examined. Detailed measurements of the (1,0) band OH lineshape variations in H2-air combustions are used, along with single-pulse and time-averaged measurements of an excimer-pumped dye laser, to predict the performance of a model velocimeter with typical Scramjet flow properties. The analysis demonstrates the need for modification and control of the laser bandshape in order to permit accurate velocity measurements in the presence of multivariant flow properties.

Volcanic stratigraphy and geochemical variations in Miocene-age rocks in western and southeastern Fort Irwin, California

NASA Astrophysics Data System (ADS)

Buesch, D.

2015-12-01

Lava flows and tuffaceous deposits ranging in composition from basalt to rhyolite, including basaltic trachyandesite to trachyte, are exposed in 800 km2 of western Fort Irwin area, California, and form the eastern edge of the Eagle Crags volcanic field (ECVF). The main ECVF has 40Ar/39Ar ages from ~18.7-12.4 Ma (mostly 18.7-18.5 Ma; Sabin et al. 1994), and on Fort Irwin, the ages are from 21.0-15.8 Ma (mostly 18.6-15.8 Ma; Schermer et al. 1996). 68 samples (56 lava flow, 4 dome-collapse breccia, 3 ignimbrite, and 5 fallout tephra) were analyzed for major, minor, and trace elements. Typically, stratigraphic sequences dip <30° (mostly <15°) except near faults, with local buttress unconfomities and no large unconfomities. Compositions are moderate-to-high-K type, and similar to Na2O+K2O from Sabin et al. (1994) but with slightly smaller ranges. The generalized stratigraphic sequence is rhyolite (R), dacite (D), or trachyte (T) that form domes, lava flows (up to 3.5 km long), dome-collapse deposits, or pyroclastic deposits, overlain by andesite (A), trachyandesite (TA), basaltic andesite (BA), basaltic trachyandesite (BT), or basalt (B) lava flows (up to 7 km long), and minor cinder cones. A general upward felsic to mafic compositional sequence occurs throughout the area, but is not continuous as B is locally in a R-D sequence and B is at the base of and interstratified with a BA-A sequence. Also, there are compositional variations at different locations along the edges of the field. In the Goldstone Mesa, Pink Canyon, and Stone Ridge areas (~70 km2), B-BA forms the youngest lava flows, but ~21 km to the north in the Garry Owen area (~25 km2), BTA forms the youngest lava flows. Compared to the Stone Ridge area with a D-A-TA-BA trend, ~6 km west in the Pioneer Plateau area is R-TA-D, ~3 km south in the Pink Canyon area is R-B-BA-A, and ~8 km east at Dacite Dome is D only (all areas have slightly different Na2O+K2O in each rock type). A non-ECVF, 5.6 Ma BA flow in SE Fort Irwin also has distinct compositions. Chemical variations indicate the region had similar general evolution of magma sources, but (1) there were numerous small, isolated chambers that fed flows along the edges of the field, (2) several tuffs are similar to local lavas but some differ and might have distant sources, and (3) basalt flows locally encroached into adjacent areas.

Double-trace flows and the swampland

NASA Astrophysics Data System (ADS)

Giombi, Simone; Perlmutter, Eric

2018-03-01

We explore the idea that large N, non-supersymmetric conformal field theories with a parametrically large gap to higher spin single-trace operators may be obtained as infrared fixed points of relevant double-trace deformations of superconformal field theories. After recalling the AdS interpretation and some potential pathologies of such flows, we introduce a concrete example that appears to avoid them: the ABJM theory at finite k, deformed by \\int O^2, where O is the superconformal primary in the stress-tensor multiplet. We address its relation to recent conjectures based on weak gravity bounds, and discuss the prospects for a wider class of similarly viable flows. Next, we proceed to analyze the spectrum and correlation functions of the putative IR CFT, to leading non-trivial order in 1 /N. This includes analytic computations of the change under double-trace flow of connected four-point functions of ABJM superconformal primaries; and of the IR anomalous dimensions of infinite classes of double-trace composite operators. These would be the first analytic results for anomalous dimensions of finite-spin composite operators in any large N CFT3 with an Einstein gravity dual.

Characterization of the molar mass distribution of macromolecules in beer for different mashing processes using asymmetric flow field-flow fractionation (AF4) coupled with multiple detectors.

PubMed

Choi, Jaeyeong; Zielke, Claudia; Nilsson, Lars; Lee, Seungho

2017-07-01

The macromolecular composition of beer is largely determined by the brewing and the mashing process. It is known that the physico-chemical properties of proteinaceous and polysaccharide molecules are closely related to the mechanism of foam stability. Three types of "American pale ale" style beer were prepared using different mashing protocols. The foam stability of the beers was assessed using the Derek Rudin standard method. Asymmetric flow field-flow fractionation (AF4) in combination with ultraviolet (UV), multiangle light scattering (MALS) and differential refractive index (dRI) detectors was used to separate the macromolecules present in the beers and the molar mass (M) and molar mass distributions (MD) were determined. Macromolecular components were identified by enzymatic treatments with β-glucanase and proteinase K. The MD of β-glucan ranged from 10 6 to 10 8  g/mol. In addition, correlation between the beer's composition and foam stability was investigated (increased concentration of protein and β-glucan was associated with increased foam stability).

Flux flow induced microwave absorption in high temperature superconductor Bi 2-XPb XSr 2Ca N-1Cu NO 4+2N

NASA Astrophysics Data System (ADS)

Owens, F. J.

1990-12-01

Direct measurements of microwave absorption without use of rf H field modulation in granular composites of the 115 K superconductor Bi 2-XPb XSr 2Ca N-1Cu NO 4+2N as a function of magnetic field above 0.1 T reveal a continuing increase of absorption of microwave energy increasing magnetic field. The temperature and magnetic field dependence of the absorption are very different from the low magnetic field (<0.01 T) absorption arising from weak links in the material. The magnetic field and temperature dependence are consistent with the behavior of thermally activated flux flow resistance suggesting the absorption is due to flux creep.

Changes in collection efficiency in nylon net filter media through magnetic alignment of elongated aerosol particles.

PubMed

Lam, Christopher O; Finlay, W H

2009-10-01

Fiber aerosols tend to align parallel to surrounding fluid streamlines in shear flows, making their filtration more difficult. However, previous research indicates that composite particles made from cromoglycic acid fibers coated with small nanoscaled magnetite particles can align with an applied magnetic field. The present research explored the effect of magnetically aligning these fibers to increase their filtration. Nylon net filters were challenged with the aerosol fibers, and efficiency tests were performed with and without a magnetic field applied perpendicular to the flow direction. We investigated the effects of varying face velocities, the amount of magnetite material on the aerosol particles, and magnetic field strengths. Findings from the experiments, matched by supporting single-fiber theories, showed significant efficiency increases at the low face velocity of 1.5 cm s(-1) at all magnetite compositions, with efficiencies more than doubling due to magnetic field alignment in certain cases. At a higher face velocity of 5.12 cm s(-1), filtration efficiencies were less affected by the magnetic field alignment being, at most, 43% higher for magnetite weight compositions up to 30%, while at a face velocity of 10.23 cm s(-1) alignment effects were insignificant. In most cases, efficiencies became independent of magnetic field strength above 50 mT, suggesting full alignment of the fibers. The present data suggest that fiber alignment in a magnetic field may warrant applications in the filtration and detection of fibers, such as asbestos.

Oxygen isotope exchange in rocks and minerals from the Cerro Prieto geothermal system: Indicators of temperature distribution and fluid flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, A.E.; Elders, W.A.

1981-01-01

Oxygen isotopic compositions have been measured in drill cuttings and core samples from more than 40 wells ranging in depth to more than 3.5 km in the Cerro Prieto geothermal field. Profiles of isotopic ratios versus sampling depths provide information on the three-dimensional distribution of temperature and fluid flow. These parameters also indicate variations in the history of hydrothermal processes in different areas of the geothermal field.

Real gas flow fields about three dimensional configurations

NASA Technical Reports Server (NTRS)

Balakrishnan, A.; Lombard, C. K.; Davy, W. C.

1983-01-01

Real gas, inviscid supersonic flow fields over a three-dimensional configuration are determined using a factored implicit algorithm. Air in chemical equilibrium is considered and its local thermodynamic properties are computed by an equilibrium composition method. Numerical solutions are presented for both real and ideal gases at three different Mach numbers and at two different altitudes. Selected results are illustrated by contour plots and are also tabulated for future reference. Results obtained compare well with existing tabulated numerical solutions and hence validate the solution technique.

Nonequilibrium radiation and chemistry models for aerocapture vehicle flowfields, volume 3

NASA Technical Reports Server (NTRS)

Carlson, Leland A.

1991-01-01

The computer programs developed to calculate the shock wave precursor and the method of using them are described. This method calculated the precursor flow field in a nitrogen gas including the effects of emission and absorption of radiation on the energy and composition of gas. The radiative transfer is calculated including the effects of absorption and emission through the line as well as the continuum process in the shock layer and through the continuum processes only in the precursor. The effects of local thermodynamic nonequilibrium in the shock layer and precursor regions are also included in the radiative transfer calculations. Three computer programs utilized by this computational scheme to calculate the precursor flow field solution for a given shock layer flow field are discussed.

Incompressible variable-density turbulence in an external acceleration field

DOE PAGES

Gat, Ilana; Matheou, Georgios; Chung, Daniel; ...

2017-08-24

Dynamics and mixing of a variable-density turbulent flow subject to an externally imposed acceleration field in the zero-Mach-number limit are studied in a series of direct numerical simulations. The flow configuration studied consists of alternating slabs of high- and low-density fluid in a triply periodic domain. Density ratios in the range ofmore » $$1.05\\leqslant R\\equiv \\unicode[STIX]{x1D70C}_{1}/\\unicode[STIX]{x1D70C}_{2}\\leqslant 10$$are investigated. The flow produces temporally evolving shear layers. A perpendicular density–pressure gradient is maintained in the mean as the flow evolves, with multi-scale baroclinic torques generated in the turbulent flow that ensues. For all density ratios studied, the simulations attain Reynolds numbers at the beginning of the fully developed turbulence regime. An empirical relation for the convection velocity predicts the observed entrainment-ratio and dominant mixed-fluid composition statistics. Two mixing-layer temporal evolution regimes are identified: an initial diffusion-dominated regime with a growth rate$${\\sim}t^{1/2}$$followed by a turbulence-dominated regime with a growth rate$${\\sim}t^{3}$$. In the turbulent regime, composition probability density functions within the shear layers exhibit a slightly tilted (‘non-marching’) hump, corresponding to the most probable mole fraction. In conclusion, the shear layers preferentially entrain low-density fluid by volume at all density ratios, which is reflected in the mixed-fluid composition.« less

Incompressible variable-density turbulence in an external acceleration field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gat, Ilana; Matheou, Georgios; Chung, Daniel

Dynamics and mixing of a variable-density turbulent flow subject to an externally imposed acceleration field in the zero-Mach-number limit are studied in a series of direct numerical simulations. The flow configuration studied consists of alternating slabs of high- and low-density fluid in a triply periodic domain. Density ratios in the range ofmore » $$1.05\\leqslant R\\equiv \\unicode[STIX]{x1D70C}_{1}/\\unicode[STIX]{x1D70C}_{2}\\leqslant 10$$are investigated. The flow produces temporally evolving shear layers. A perpendicular density–pressure gradient is maintained in the mean as the flow evolves, with multi-scale baroclinic torques generated in the turbulent flow that ensues. For all density ratios studied, the simulations attain Reynolds numbers at the beginning of the fully developed turbulence regime. An empirical relation for the convection velocity predicts the observed entrainment-ratio and dominant mixed-fluid composition statistics. Two mixing-layer temporal evolution regimes are identified: an initial diffusion-dominated regime with a growth rate$${\\sim}t^{1/2}$$followed by a turbulence-dominated regime with a growth rate$${\\sim}t^{3}$$. In the turbulent regime, composition probability density functions within the shear layers exhibit a slightly tilted (‘non-marching’) hump, corresponding to the most probable mole fraction. In conclusion, the shear layers preferentially entrain low-density fluid by volume at all density ratios, which is reflected in the mixed-fluid composition.« less

Mineral and chemical variations within an ash-flow sheet from Aso caldera, Southwestern Japan

USGS Publications Warehouse

Lipman, P.W.

1967-01-01

Although products of individual volcanic eruptions, especially voluminous ash-flow eruptions, have been considered among the best available samples of natural magmas, detailed petrographic and chemical study indicates that bulk compositions of unaltered Pleistocene ash-flow tuffs from Aso caldera, Japan, deviate significantly from original magmatic compositions. The last major ash-flow sheet from Aso caldera is as much as 150 meters thick and shows a general vertical compositional change from phenocryst-poor rhyodacite upward into phenocryst-rich trachyandesite; this change apparently reflects in inverse order a compositionally zoned magma chamber in which more silicic magma overlay more mafic magma. Details of these magmatic variations were obscured, however, by: (1) mixing of compositionally distinct batches of magma during upwelling in the vent, as indicated by layering and other heterogeneities within single pumice lumps; (2) mixing of particulate fragments-pumice lumps, ash, and phenocrysts-of varied compositions during emplacement, with the result that separate pumice lenses from a single small outcrop may have a compositional range nearly as great as the bulk-rook variation of the entire sheet; (3) density sorting of phenocrysts and ash during eruption and emplacement, resulting in systematic modal variations with distance from the caldera; (4) addition of xenocrysts, resulting in significant contamination and modification of proportions of crystals in the tuffs; and (5) ground-water leaching of glassy fractions during hydration after cooling. Similar complexities characterize ash-flow tuffs under study in southwestern Nevada and in the San Juan Mountains, Colorado, and probably are widespread in other ash-flow fields as well. Caution and careful planning are required in study of the magmatic chemistry and phenocryst mineralogy of these rocks. ?? 1967 Springer-Verlag.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin

2000-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both: mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, compositional variations in metal alloys have been investigated.

Mixing Dynamics Induced by Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Mazuruk, Konstantin; Rose, M. Franklin (Technical Monitor)

2001-01-01

Microstructural and compositional homogeneity in metals and alloys can only be achieved if the initial melt is homogeneous prior to the onset of solidification processing. Naturally induced convection may initially facilitate this requirement but upon the onset of solidification significant compositional variations generally arise leading to undesired segregation. Application of alternating magnetic fields to promote a uniform bulk liquid concentration during solidification processing has been suggested. To investigate such possibilities an initial study of using traveling magnetic fields (TMF) to promote melt homogenization is reported in this work. Theoretically, the effect of TMF-induced convection on mixing phenomena is studied in the laminar regime of flow. Experimentally, with and without applied fields, both 1) mixing dynamics by optically monitoring the spreading of an initially localized dye in transparent fluids and, 2) compositional variations in metal alloys have been investigated.

Composite volcanoes in the south-eastern part of İzmir-Balıkesir Transfer Zone, Western Anatolia, Turkey

NASA Astrophysics Data System (ADS)

Seghedi, Ioan; Helvacı, Cahit; Pécskay, Zoltan

2015-01-01

During the Early-Middle Miocene (Western Anatolia) several volcanic fields occur along a NE-SW-trending shear zone, known as İzmir-Balıkesir Transfer Zone. This is a deformed crustal-scale sinistral strike-slip fault zone crossing the Bornova flysch and extending along the NW-boundary of the Menderes Massif by accommodating the differential deformation between the Cycladic and Menderes core complexes within the Aegean extensional system. Here we discuss the volcanic activity in Yamanlar and Yuntdağı fields that is closely related to the extensional tectonics of the İzmir-Balıkesir Transfer Zone and in the same time with the episodic core complex denudation of the Menderes Massif. This study documents two composite volcanoes (Yamanlar and Yuntdağı), whose present vent area is strongly eroded and cut by a variety of strike-slip and normal fault systems, the transcurrent NW-SE being the dominant one. The erosional remnants of the vent areas, resembling a shallow crater intrusive complex, illustrate the presence of numerous dykes or variably sized neck-like intrusions and lava flows, typically associated with hydrothermal alteration processes (propylitic and argillic). Such vent areas were observed in both the examined volcanic fields, having ~ 6 km in diameter and being much more eroded toward the south, along the NW-SE fault system. Lava flows and lava domes are sometimes associated with proximal block and ash flow deposits. In the cone-building association part, besides lava flows and remnants of lava domes, rare block and ash and pumice-rich pyroclastic flow deposits, as well as a series of debris-flow deposits, have been observed. The rocks display a porphyritic texture and contain various proportions of plagioclase, clinopyroxene, orthopyroxene, amphibole, rare biotite and corroded quartz. The examined rocks fall at the limit between calc-alkaline to alkaline field, and plot predominantly in high-K andesite and dacite fields and one is rhyolite. The trace element distribution suggests fractional crystallization processes and mixing in upper crustal magma chambers and suggests a metasomatized lithospheric mantle/lower crust source. This preliminary volcanological-petrological and geochronological base study allowed documenting the Yamanlar and Yuntdağı as composite volcanoes generated during post-collisional Early-Middle Miocene transtensional tectonic movements.

Systematic measurements of ion-proton differential streaming in the solar wind.

PubMed

Berger, L; Wimmer-Schweingruber, R F; Gloeckler, G

2011-04-15

The small amount of heavy ions in the highly rarefied solar wind are sensitive tracers for plasma-physics processes, which are usually not accessible in the laboratory. We have analyzed differential streaming between heavy ions and protons in the solar wind at 1 AU. 3D velocity vector and magnetic field measurements from the Solar Wind Electron Proton Alpha Monitor and the Magnetometer aboard the Advanced Composition Explorer were used to reconstruct the ion-proton difference vector v(ip) = v(i) - v(p) from the 12 min 1D Solar Wind Ion Composition Spectrometer observations. We find that all 44 analyzed heavy ions flow along the interplanetary magnetic field at velocities which are smaller than, but comparable to, the local Alfvén speed C(A). The flow speeds of 35 of the 44 ion species lie within the range of ±0.15C(A) around 0.55C(A), the flow speed of He(2+).

Geologic map of the central San Juan caldera cluster, southwestern Colorado

USGS Publications Warehouse

Lipman, Peter W.

2006-01-01

The San Juan Mountains are the largest erosional remnant of a composite volcanic field that covered much of the southern Rocky Mountains in middle Tertiary time. The San Juan field consists mainly of intermediate-composition lavas and breccias, erupted about 35-30 Ma from scattered central volcanoes (Conejos Formation) and overlain by voluminous ash-flow sheets erupted from caldera sources. In the central San Juan Mountains, eruption of at least 8,800 km3 of dacitic-rhyolitic magma as nine major ash flow sheets (individually 150-5,000 km3) was accompanied by recurrent caldera subsidence between 28.3 Ma and about 26.5 Ma. Voluminous andesitic-dacitic lavas and breccias erupted from central volcanoes prior to the ash-flow eruptions, and similar lava eruptions continued within and adjacent to the calderas during the period of more silicic explosive volcanism. Exposed calderas vary in size from 10 to 75 km in maximum dimension; the largest calderas are associated with the most voluminous eruptions.

Preferential adsorption of fluorescing fulvic and humic acid components on activated carbon using flow field-flow fractionation analysis.

PubMed

Schmit, Kathryn H; Wells, Martha J M

2002-02-01

Activated carbon treatment of drinking water is used to remove natural organic matter (NOM) precursors that lead to the formation of disinfection byproducts. The innate hydrophobic nature and macromolecular size of NOM render it amenable to sorption by activated carbon. Batch equilibrium and minicolumn breakthrough adsorption studies were performed using granular activated carbon to treat NOM-contaminated water. Ultraviolet (UV) absorption spectroscopy and flow field-flow fractionation analysis using tandem diode-array and fluorescence detectors were used to monitor the activated carbon sorption of NOM. Using these techniques, it was possible to study activated carbon adsorption properties of UV absorbing, fluorescing and nonfluorescing, polyelectrolytic macromolecules fractionated from the total macromolecular and nonmacromolecular composition of NOM. Adsorption isotherms were constructed at pH 6 and pH 9. Data were described by the traditional and modified Freundlich models. Activated carbon capacity and adsorbability were compared among fractionated molecular subsets of fulvic and humic acids. Preferential adsorption (or adsorptive fractionation) of polyelectrolytic, fluorescing fulvic and humic macromolecules on activated carbon was observed. The significance of observing preferential adsorption on activated carbon of fluorescing macromolecular components relative to nonfluorescing components is that this phenomenon changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the composition that existed in the aqueous phase prior to adsorption. Likewise, it changes the composition of dissolved organic matter remaining in equilibrium in the aqueous phase relative to the adsorbed phase. This research increases our understanding of NOM interactions with activated carbon which may lead to improved methods of potable water production.

The gas heterogeneous flows cleaning technology from corona discharge field

NASA Astrophysics Data System (ADS)

Bogdanov, A.; Tokarev, A.; Judanov, V.; Vinogradov, V.

2017-11-01

A nanogold capture and extraction from combustion products of Kara-Keche coal, description the process: a coal preparation to experiments, nanogold introducing in its composition, temperature and time performance of combustion, device and function of experimental apparatus, gas-purification of the gas flow process and receiving combustion products (condensate, coke, ash, rags) is offerred.

Late Holocene lava flow morphotypes of northern Harrat Rahat, Kingdom of Saudi Arabia: Implications for the description of continental lava fields

NASA Astrophysics Data System (ADS)

Murcia, H.; Németh, K.; Moufti, M. R.; Lindsay, J. M.; El-Masry, N.; Cronin, S. J.; Qaddah, A.; Smith, I. E. M.

2014-04-01

A "lava morphotype" refers to the recognizable and distinctive characteristics of the surface morphology of a lava flow after solidification, used in a similar way to a sedimentary facies. This classification method is explored on an example volcanic field in the Kingdom of Saudi Arabia, where copious lava outpourings may represent an important transition between monogenetic and flood basalt fields. Here, young and well-preserved mafic lava fields display a wide range of surface morphologies. We focussed on four post-4500 yrs. BP lava flow fields in northern Harrat Rahat (<10 Ma) and propose a framework for describing systematic changes in morphotypes down-flow. The morphotypes give insight into intrinsic and extrinsic parameters of emplacement, rheology and dominant flow behavior, as well as the occurrence and character of other lava structures. The Harrat Rahat lava flow fields studied extend up to 23 km from the source, and vary between 1-2 m and 12 m in thickness. Areas of the lava flow fields are between ˜32 and ˜61 km2, with individual flow field volumes estimated between ˜0.085 and ˜0.29 km3. They exhibit Shelly-, Slabby-, and Rubbly-pahoehoe, Platy-, Cauliflower-, and Rubbly-a'a, and Blocky morphotypes. Morphotypes reflect the intrinsic parameters of: composition, temperature, crystallinity and volatile-content/vesicularity; along with external influences, such as: emission mechanism, effusion rate, topography and slope control of flow velocity. One morphotype can transition to another in individual flow-units or lobes and they may dominate zones. Not all morphotypes were found in a single lava flow field. Pahoehoe morphotypes are related to the simple mechanical disaggregation of the crust, whereas a'a morphotypes are related to the transitional emergence and subsequent transitional disappearance of clinker. Blocky morphotypes result from fracturing and auto-brecciation. A'a morphotypes (i.e. platy-, cauliflower-, rubbly-a'a) dominate the lava flow field surfaces in northern Harrat Rahat, which suggests that core-dominated flows were predominant during flow movement. Lava structures are well-developed and well-preserved and some may be related to some morphotypes. Down-flow changes exhibit key illustrative and easy recognizable features in the lava flow fields and might provide insights into real-time monitoring of future flows in this region.

Theories of binary fluid mixtures: from phase-separation kinetics to active emulsions

NASA Astrophysics Data System (ADS)

Cates, Michael E.; Tjhung, Elsen

2018-02-01

Binary fluid mixtures are examples of complex fluids whose microstructure and flow are strongly coupled. For pairs of simple fluids, the microstructure consists of droplets or bicontinuous demixed domains and the physics is controlled by the interfaces between these domains. At continuum level, the structure is defined by a composition field whose gradients which are steep near interfaces drive its diffusive current. These gradients also cause thermodynamic stresses which can drive fluid flow. Fluid flow in turn advects the composition field, while thermal noise creates additional random fluxes that allow the system to explore its configuration space and move towards the Boltzmann distribution. This article introduces continuum models of binary fluids, first covering some well-studied areas such as the thermodynamics and kinetics of phase separation, and emulsion stability. We then address cases where one of the fluid components has anisotropic structure at mesoscopic scales creating nematic (or polar) liquid-crystalline order; this can be described through an additional tensor (or vector) order parameter field. We conclude by outlining a thriving area of current research, namely active emulsions, in which one of the binary components consists of living or synthetic material that is continuously converting chemical energy into mechanical work.

Thermal Conductivity Measurement of Molten Cu-Co Alloy Using an Electromagnetic Levitator Superimposed with a Static Magnetic Field

NASA Astrophysics Data System (ADS)

Nakamura, Yuki; Takahashi, Ryuji; Shoji, Eita; Kubo, Masaki; Tsukada, Takao; Uchikoshi, Masahito; Fukuyama, Hiroyuki

2017-12-01

The thermal conductivity of molten Cu-Co alloy with different compositions around the liquidus line temperature was measured by the periodic laser-heating method using an electromagnetic levitator superimposed with a static magnetic field to suppress convection in a levitated droplet sample. During the measurement, a static magnetic field of 10 T was applied to the levitated droplet. To confirm that the strength of the static magnetic field was sufficient to suppress convection in the droplet, numerical simulations were performed for the flow and thermal fields in an electromagnetically levitated droplet under a static magnetic field, and moreover, for the periodic laser-heating method to determine the thermal conductivity. It was found that the thermal conductivity of molten Cu-Co alloy increased gradually with increasing Cu composition up to 80 at. pct, beyond which it increased markedly and reached that of pure Cu. In addition, it was found that the composition dependence of the thermal conductivity can be explainable by the Wiedemann-Franz law.

Gas chemistry and thermometry of the Cerro Prieto, Mexico, geothermal field

USGS Publications Warehouse

Nehring, N.L.; D'Amore, F.

1984-01-01

Gas compositions of Cerro Prieto wells in 1977 reflected strong boiling in the reservoir around wells M-20 and M-25. This boiling zone appeared to be collapsing in 1982 when a number of wells in this area of the field were shut-in. In 1977 and 1982, gas compositions also showed boiling zones corresponding to faults H and L postulated by Halfman et al. (1982). Four gas geothermometers were applied, based on reservoir equilibria and calculated fugacities. The Fisher - Tropsch reaction predicted high temperatures and appeared to re-equilibrate slowly, whereas the H2S reaction predicted low temperatures and appeared to re-equilibrate rapidly. Hydrogen and NH3 reactions were intermediate. Like gas compositions, the geothermometers reflected reservoir processes, such as boiling. Surface gas compositions are related to well compositions, but contain large concentrations of N2 originating from air dissolved in groundwater. The groundwater appears to originate in the east and flow over the production field before mixing with reservoir gases near the surface. ?? 1984.

Pollen-mediated gene flow and seed exchange in small-scale Zambian maize farming, implications for biosafety assessment

NASA Astrophysics Data System (ADS)

Bøhn, Thomas; Aheto, Denis W.; Mwangala, Felix S.; Fischer, Klara; Bones, Inger Louise; Simoloka, Christopher; Mbeule, Ireen; Schmidt, Gunther; Breckling, Broder

2016-10-01

Gene flow in agricultural crops is important for risk assessment of genetically modified (GM) crops, particularly in countries with a large informal agricultural sector of subsistence cultivation. We present a pollen flow model for maize (Zea mays), a major staple crop in Africa. We use spatial properties of fields (size, position) in three small-scale maize farming communities in Zambia and estimate rates of cross-fertilisation between fields sown with different maize varieties (e.g. conventional and transgene). As an additional factor contributing to gene flow, we present data on seed saving and sharing among farmers that live in the same communities. Our results show that: i) maize fields were small and located in immediate vicinity of neighboring fields; ii) a majority of farmers saved and shared seed; iii) modeled rates of pollen-mediated gene flow showed extensive mixing of germplasm between fields and farms and iv) as a result, segregation of GM and non-GM varieties is not likely to be an option in these systems. We conclude that the overall genetic composition of maize, in this and similar agricultural contexts, will be strongly influenced both by self-organised ecological factors (pollen flow), and by socially mediated intervention (seed recycling and sharing).

Pollen-mediated gene flow and seed exchange in small-scale Zambian maize farming, implications for biosafety assessment

PubMed Central

Bøhn, Thomas; Aheto, Denis W.; Mwangala, Felix S.; Fischer, Klara; Bones, Inger Louise; Simoloka, Christopher; Mbeule, Ireen; Schmidt, Gunther; Breckling, Broder

2016-01-01

Gene flow in agricultural crops is important for risk assessment of genetically modified (GM) crops, particularly in countries with a large informal agricultural sector of subsistence cultivation. We present a pollen flow model for maize (Zea mays), a major staple crop in Africa. We use spatial properties of fields (size, position) in three small-scale maize farming communities in Zambia and estimate rates of cross-fertilisation between fields sown with different maize varieties (e.g. conventional and transgene). As an additional factor contributing to gene flow, we present data on seed saving and sharing among farmers that live in the same communities. Our results show that: i) maize fields were small and located in immediate vicinity of neighboring fields; ii) a majority of farmers saved and shared seed; iii) modeled rates of pollen-mediated gene flow showed extensive mixing of germplasm between fields and farms and iv) as a result, segregation of GM and non-GM varieties is not likely to be an option in these systems. We conclude that the overall genetic composition of maize, in this and similar agricultural contexts, will be strongly influenced both by self-organised ecological factors (pollen flow), and by socially mediated intervention (seed recycling and sharing). PMID:27694819

Pollen-mediated gene flow and seed exchange in small-scale Zambian maize farming, implications for biosafety assessment.

PubMed

Bøhn, Thomas; Aheto, Denis W; Mwangala, Felix S; Fischer, Klara; Bones, Inger Louise; Simoloka, Christopher; Mbeule, Ireen; Schmidt, Gunther; Breckling, Broder

2016-10-03

Gene flow in agricultural crops is important for risk assessment of genetically modified (GM) crops, particularly in countries with a large informal agricultural sector of subsistence cultivation. We present a pollen flow model for maize (Zea mays), a major staple crop in Africa. We use spatial properties of fields (size, position) in three small-scale maize farming communities in Zambia and estimate rates of cross-fertilisation between fields sown with different maize varieties (e.g. conventional and transgene). As an additional factor contributing to gene flow, we present data on seed saving and sharing among farmers that live in the same communities. Our results show that: i) maize fields were small and located in immediate vicinity of neighboring fields; ii) a majority of farmers saved and shared seed; iii) modeled rates of pollen-mediated gene flow showed extensive mixing of germplasm between fields and farms and iv) as a result, segregation of GM and non-GM varieties is not likely to be an option in these systems. We conclude that the overall genetic composition of maize, in this and similar agricultural contexts, will be strongly influenced both by self-organised ecological factors (pollen flow), and by socially mediated intervention (seed recycling and sharing).

Spatial and Temporal Analysis of Eruption Locations, Compositions, and Styles in Northern Harrat Rahat, Kingdom of Saudi Arabia

NASA Astrophysics Data System (ADS)

Dietterich, H. R.; Stelten, M. E.; Downs, D. T.; Champion, D. E.

2017-12-01

Harrat Rahat is a predominantly mafic, 20,000 km2 volcanic field in western Saudi Arabia with an elongate volcanic axis extending 310 km north-south. Prior mapping suggests that the youngest eruptions were concentrated in northernmost Harrat Rahat, where our new geologic mapping and geochronology reveal >300 eruptive vents with ages ranging from 1.2 Ma to a historic eruption in 1256 CE. Eruption compositions and styles vary spatially and temporally within the volcanic field, where extensive alkali basaltic lavas dominate, but more evolved compositions erupted episodically as clusters of trachytic domes and small-volume pyroclastic flows. Analysis of vent locations, compositions, and eruption styles shows the evolution of the volcanic field and allows assessment of the spatio-temporal probabilities of vent opening and eruption styles. We link individual vents and fissures to eruptions and their deposits using field relations, petrography, geochemistry, paleomagnetism, and 40Ar/39Ar and 36Cl geochronology. Eruption volumes and deposit extents are derived from geologic mapping and topographic analysis. Spatial density analysis with kernel density estimation captures vent densities of up to 0.2 %/km2 along the north-south running volcanic axis, decaying quickly away to the east but reaching a second, lower high along a secondary axis to the west. Temporal trends show slight younging of mafic eruption ages to the north in the past 300 ka, as well as clustered eruptions of trachytes over the past 150 ka. Vent locations, timing, and composition are integrated through spatial probability weighted by eruption age for each compositional range to produce spatio-temporal models of vent opening probability. These show that the next mafic eruption is most probable within the north end of the main (eastern) volcanic axis, whereas more evolved compositions are most likely to erupt within the trachytic centers further to the south. These vent opening probabilities, combined with corresponding eruption properties, can be used as the basis for lava flow and tephra fall hazard maps.

Hypervelocity atmospheric flight: Real gas flow fields

NASA Technical Reports Server (NTRS)

Howe, John T.

1990-01-01

Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that were reduced to a relatively compact set of equations of a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-averaged behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equation a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. For hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates, chemical nonequilibrium is considered and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

Hypervelocity atmospheric flight: Real gas flow fields

NASA Technical Reports Server (NTRS)

Howe, John T.

1989-01-01

Flight in the atmosphere is examined from the viewpoint of including real gas phenomena in the flow field about a vehicle flying at hypervelocity. That is to say, the flow field is subject not only to compressible phenomena, but is dominated by energetic phenomena. There are several significant features of such a flow field. Spatially, its composition can vary by both chemical and elemental species. The equations which describe the flow field include equations of state and mass, species, elemental, and electric charge continuity; momentum; and energy equations. These are nonlinear, coupled, partial differential equations that have been reduced to a relatively compact set of equations in a self-consistent manner (which allows mass addition at the surface at a rate comparable to the free-stream mass flux). The equations and their inputs allow for transport of these quantities relative to the mass-average behavior of the flow field. Thus transport of mass by chemical, thermal, pressure, and forced diffusion; transport of momentum by viscosity; and transport of energy by conduction, chemical considerations, viscosity, and radiative transfer are included. The last of these complicate the set of equations by making the energy equations a partial integrodifferential equation. Each phenomenon is considered and represented mathematically by one or more developments. The coefficients which pertain are both thermodynamically and chemically dependent. Solutions of the equations are presented and discussed in considerable detail, with emphasis on severe energetic flow fields. Hypervelocity flight in low-density environments where gaseous reactions proceed at finite rates chemical nonequilibrium is considered, and some illustrations are presented. Finally, flight where the flow field may be out of equilibrium, both chemically and thermodynamically, is presented briefly.

Understanding Friction Stir Welding

NASA Technical Reports Server (NTRS)

Nunes, A. C., Jr.

2018-01-01

This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

The effect of inflation on the morphology-derived rheological parameters of lava flows and its implications for interpreting remote sensing data - A case study on the 2014/2015 eruption at Holuhraun, Iceland

NASA Astrophysics Data System (ADS)

Kolzenburg, S.; Jaenicke, J.; Münzer, U.; Dingwell, D. B.

2018-05-01

Morphology-derived lava flow rheology is a frequently used tool in volcanology and planetary science to determine rheological parameters and deduce the composition of lavas on terrestrial planets and their moons. These calculations are usually based on physical equations incorporating 1) lava flow driving forces: gravity, slope and flow-rate and 2) morphological data such as lava flow geometry: flow-width, -height or shape of the flow outline. All available methods assume that no geometrical changes occur after emplacement and that the measured flow geometry reflects the lava's apparent viscosity and/or yield strength during emplacement. It is however well-established from terrestrial examples that lava flows may inflate significantly after the cessation of flow advance. This inflation affects, in turn, the width-to-height ratio upon which the rheological estimates are based and thus must result in uncertainties in the determination of flow rheology, as the flow height is one of the key parameters in the morphology-based deduction of flow properties. Previous studies have recognized this issue but, to date, no assessment of the magnitude of this error has been presented. This is likely due to a lack of digital elevation models (DEMs) at sufficiently high spatial and temporal resolution. The 2014/15 Holuhraun eruption in central Iceland represents one of the best monitored large volume (1.5 km3) lava flow fields (85 km2) to date. An abundance of scientific field and remote sensing data were collected during its emplacement. Moreover, inflation plays a key role in the emplacement dynamics of the late stage of the lava field. Here, we use a time series of high resolution DEMs acquired by the TanDEM-X satellite mission prior, during and after the eruption to evaluate the error associated with the most common methods of deriving lava flow rheology from morphological parameters used in planetary science. We can distinguish two dominant processes as sources of error in the determination of lava flow rheology from morphology 1) wholesale inflation of lava channels and 2) post halting inflation of individual lava toes. These result in a 2.4- to 17 - fold overestimation of apparent viscosity and a 0.7- to 2.4 - fold overestimation of yield strength. When applied in planetary sciences, this overestimation in rheological parameters translates directly to an overestimation of the respective lavas silica content. We conclude that, although qualitatively informative, morphological analysis is insufficient to discern lava rheology and composition. Instead, in-situ analysis together with high resolution remote sensing data is needed to properly constrain the compositions involved in planetary volcanism.

Laboratory and pilot-scale field experiments for application of iron oxide nanoparticle-loaded chitosan composites to phosphate removal from natural water.

PubMed

Kim, Jae-Hyun; Kim, Song-Bae; Lee, Sang-Hyup; Choi, Jae-Woo

2018-03-01

The aim of this study was to apply iron oxide nanoparticle-chitosan (ION-chitosan) composites to phosphate removal from natural water collected from the Seoho Stream in Suwon, Republic of Korea. Laboratory batch experiments showed that phosphate removal by the ION-chitosan composites was not sensitive to pH changes between pH values of 5.0 and 9.0. During six cycles of adsorption-desorption, the composites could be successfully regenerated with 5 mM NaOH solution and reused for phosphate removal. Laboratory fixed-bed column experiments (column height = 10 and 20 cm, inner diameter = 2.5 cm, flow rate = 8.18 and 16.36 mL/min) demonstrated that the composites could be successfully applied for phosphate removal under dynamic flow conditions. A pilot-scale field experiment was performed in a pilot plant, which was mainly composed of chemical reactor/dissolved air flotation and an adsorption tower, built nearby the Seoho Stream. The natural water was pumped from the Seoho Stream into the pilot plant, passed through the chemical reactor/dissolved air flotation process, and then introduced into the adsorption tower (height = 100 cm, inner diameter = 45 cm, flow rate = 7.05 ± 0.18 L/min) for phosphate removal via the composites (composite volume = 80 L, composite weight = 85.74 kg). During monitoring of the adsorption tower (33 days), the influent total phosphorus (T-P) concentration was in the range of 0.020-0.046 mgP/L, whereas the effluent T-P concentration was in the range of 0.010-0.028 mgP/L. The percent removal of T-P in the adsorption tower was 52.3% with a phosphate removal capacity of 0.059 mgP/g.

Biofilm development in a hotspot of mixing between shallow and deep groundwater in a fractured aquifer: field evidence from joint flow, chemical and microbiological measurements

NASA Astrophysics Data System (ADS)

Bochet, O.; Dufresne, A.; Pédrot, M.; Chatton, E.; Labasque, T.; Ben Maamar, S.; Burté, L.; de la Bernardie, J.; Guihéneuf, N.; Lavenant, N.; Petton, C.; Bour, O.; Aquilina, L.; Le Borgne, T.

2015-12-01

Biofilms play a major role in controlling the fluxes and reactivity of chemical species transported in hydro-logical systems. Micro-organisms require both electron donors and electron acceptors for cellular growth, proliferation and maintenance of their metabolic functions. The mechanisms controlling these reactions derive from the interactions occurring at the micro-scale that depend on mineral compositions, the biota of subsurface environment, but also fluid mixing, which determines the local concentrations of nutriments, electron donors and electron acceptors. Hence, mixing zones between oxygen and nutriment rich shallow groundwater and mineralized deep groundwater are often considered as potential hotspots of microbial activity, although relatively few field data document flow distributions, transport properties, chemical gradients and micro-organisms distributions across these mixing interfaces. Here we investigate the origin of a localized biofilm development observed in the fractured granite aquifer at the Ploemeur observatory (H+ network hplus.ore.fr).This biofilm composed of ferro-oxidizing bacteria is observed in an 130m deep artesian well. Borehole video logs show an important colonization of the well by the biofilm in the shallower part (0 to 60m), while it is inexistent in the deeper part (60 to 130m). As flow is localized in a few deep and shallow fractures, we presume that the spatial distribution of biofilm is controlled by mixing between shallow and deep groundwater. To verify this hypothesis we conducted a field campaign with joint characterization of the flow and chemical composition of water flowing from the different fractures, as well as the microbiological composition of the biofilm at different depth, using pyrosequencing techniques. We will discuss in this presentation the results of this interdisciplinary dataset and their implications for the occurrence of hotspots of microbiological activity in the subsurface.

Resonant Mode-hopping Micromixing

PubMed Central

Jang, Ling-Sheng; Chao, Shih-Hui; Holl, Mark R.; Meldrum, Deirdre R.

2009-01-01

A common micromixer design strategy is to generate interleaved flow topologies to enhance diffusion. However, problems with these designs include complicated structures and dead volumes within the flow fields. We present an active micromixer using a resonating piezoceramic/silicon composite diaphragm to generate acoustic streaming flow topologies. Circulation patterns are observed experimentally and correlate to the resonant mode shapes of the diaphragm. The dead volumes in the flow field are eliminated by rapidly switching from one discrete resonant mode to another (i.e., resonant mode-hop). Mixer performance is characterized by mixing buffer with a fluorescence tracer containing fluorescein. Movies of the mixing process are analyzed by converting fluorescent images to two-dimensional fluorescein concentration distributions. The results demonstrate that mode-hopping operation rapidly homogenized chamber contents, circumventing diffusion-isolated zones. PMID:19551159

Mapping and DOWNFLOW simulation of recent lava flow fields at Mount Etna

NASA Astrophysics Data System (ADS)

Tarquini, Simone; Favalli, Massimiliano

2011-07-01

In recent years, progress in geographic information systems (GIS) and remote sensing techniques have allowed the mapping and studying of lava flows in unprecedented detail. A composite GIS technique is introduced to obtain high resolution boundaries of lava flow fields. This technique is mainly based on the processing of LIDAR-derived maps and digital elevation models (DEMs). The probabilistic code DOWNFLOW is then used to simulate eight large flow fields formed at Mount Etna in the last 25 years. Thanks to the collection of 6 DEMs representing Mount Etna at different times from 1986 to 2007, simulated outputs are obtained by running the DOWNFLOW code over pre-emplacement topographies. Simulation outputs are compared with the boundaries of the actual flow fields obtained here or derived from the existing literature. Although the selected fields formed in accordance with different emplacement mechanisms, flowed on different zones of the volcano over different topographies and were fed by different lava supplies of different durations, DOWNFLOW yields results close to the actual flow fields in all the cases considered. This outcome is noteworthy because DOWNFLOW has been applied by adopting a default calibration, without any specific tuning for the new cases considered here. This extensive testing proves that, if the pre-emplacement topography is available, DOWNFLOW yields a realistic simulation of a future lava flow based solely on a knowledge of the vent position. In comparison with deterministic codes, which require accurate knowledge of a large number of input parameters, DOWNFLOW turns out to be simple, fast and undemanding, proving to be ideal for systematic hazard and risk analyses.

Effect of steady and time-harmonic magnetic fields on macrosegragation in alloy solidification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Incropera, F.P.; Prescott, P.J.

Buoyancy-induced convection during the solidification of alloys can contribute significantly to the redistribution of alloy constituents, thereby creating large composition gradients in the final ingot. Termed macrosegregation, the condition diminishes the quality of the casting and, in the extreme, may require that the casting be remelted. The deleterious effects of buoyancy-driven flows may be suppressed through application of an external magnetic field, and in this study the effects of both steady and time-harmonic fields have been considered. For a steady magnetic field, extremely large field strengths would be required to effectively dampen convection patterns that contribute to macrosegregation. However, bymore » reducing spatial variations in temperature and composition, turbulent mixing induced by a time-harmonic field reduces the number and severity of segregates in the final casting.« less

A discontinuous Galerkin method with a bound preserving limiter for the advection of non-diffusive fields in solid Earth geodynamics

NASA Astrophysics Data System (ADS)

He, Ying; Puckett, Elbridge Gerry; Billen, Magali I.

2017-02-01

Mineral composition has a strong effect on the properties of rocks and is an essentially non-diffusive property in the context of large-scale mantle convection. Due to the non-diffusive nature and the origin of compositionally distinct regions in the Earth the boundaries between distinct regions can be nearly discontinuous. While there are different methods for tracking rock composition in numerical simulations of mantle convection, one must consider trade-offs between computational cost, accuracy or ease of implementation when choosing an appropriate method. Existing methods can be computationally expensive, cause over-/undershoots, smear sharp boundaries, or are not easily adapted to tracking multiple compositional fields. Here we present a Discontinuous Galerkin method with a bound preserving limiter (abbreviated as DG-BP) using a second order Runge-Kutta, strong stability-preserving time discretization method for the advection of non-diffusive fields. First, we show that the method is bound-preserving for a point-wise divergence free flow (e.g., a prescribed circular flow in a box). However, using standard adaptive mesh refinement (AMR) there is an over-shoot error (2%) because the cell average is not preserved during mesh coarsening. The effectiveness of the algorithm for convection-dominated flows is demonstrated using the falling box problem. We find that the DG-BP method maintains sharper compositional boundaries (3-5 elements) as compared to an artificial entropy-viscosity method (6-15 elements), although the over-/undershoot errors are similar. When used with AMR the DG-BP method results in fewer degrees of freedom due to smaller regions of mesh refinement in the neighborhood of the discontinuity. However, using Taylor-Hood elements and a uniform mesh there is an over-/undershoot error on the order of 0.0001%, but this error increases to 0.01-0.10% when using AMR. Therefore, for research problems in which a continuous field method is desired the DG-BP method can provide improved tracking of sharp compositional boundaries. For applications in which strict bound-preserving behavior is desired, use of an element that provides a divergence-free condition on the weak formulation (e.g., Raviart-Thomas) and an improved mesh coarsening scheme for the AMR are required.

Microfluidic free-flow zone electrophoresis and isotachophoresis using carbon black nano-composite PDMS sidewall membranes.

PubMed

Fu, Xiaotong; Mavrogiannis, Nicholas; Ibo, Markela; Crivellari, Francesca; Gagnon, Zachary R

2017-01-01

We present a new type of free-flow electrophoresis (FFE) device for performing on-chip microfluidic isotachophoresis and zone electrophoresis. FFE is performed using metal gallium electrodes, which are isolated from a main microfluidic flow channel using thin micron-scale polydimethylsiloxane/carbon black (PDMS/CB) composite membranes integrated directly into the sidewalls of the microfluidic channel. The thin membrane allows for field penetration and effective electrophoresis, but serves to prevent bubble generation at the electrodes from electrolysis. We experimentally demonstrate the ability to use this platform to perform on-chip free-flow electrophoretic separation and isotachophoretic concentration. Due to the small size and simple fabrication procedure, this PDMS/CB platform could be used as a part of an on-chip upstream sample preparation toolkit for portable microfluidic diagnostic applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fabrication and characterization of artificial hair cell sensor based on MWCNT-PDMS composite

NASA Astrophysics Data System (ADS)

Kim, Chi Yeon; Lee, Hyun Sup; Cho, Yo Han; Joh, Cheeyoung; Choi, Pyung; Park, Seong Jin

2011-06-01

The aim of this work is to design and fabricate a flow sensor using an artificial hair cell (AHC) inspired by biological hair cells of fish. The sensor consists of a single cilium structure with high aspect ratio and a mechanoreceptor using force sensitive resistor (FSR). The cilium structure is designed for capturing a drag force with direction due to flow field around the sensor and the mechanoreceptor is designed for sensing the drag force with direction from the cilium structure and converting it into an electric signal. The mechanoreceptor has a symmetric four electrodes to sense the drag force and its direction. To fabricate the single cilium structure with high aspect ratio, we have proposed a new design concept using a separated micro mold system (SMS) fabricated by the LIGA process. For a successful replication of the cilium structure, we used the hot embossing process with the help of a double-sided mold system. We used a composite of multiwall carbon nanotube and polydimethylsiloxane (MWCNT-PDMS). The performance of the mechanoreceptors was measured by a computer-controlled nanoindenter. We carried out several experiments with the sensor in the different flow rate and direction using the experimental test apparatus. To calibrate the sensor and calculate the velocity with direction based the signal from the sensor, we analyzed the coupled phenomena between flow field and the cilium structure to calculate the deflection of the cilium structure and the drag force applying to the cilium structure due to the flow field around sensor.

Mineral complexities as evidence for open-system processes in intermediate magmas of the Mount Baker volcanic field, northern Cascade arc

NASA Astrophysics Data System (ADS)

Escobar-Burciaga, R. D.; DeBari, S. M.

2015-12-01

The petrogenesis of intermediate magmas in arcs is a critical contribution to crustal growth. Andesites are commonly thought of as a hybrid product, the result of two endmember magmas mixing. At the Mount Baker volcanic field (MBVF), northern Cascade arc, andesites are the predominantly erupted lavas since 1 Ma and yet their origin is poorly constrained. Previous studies have suggested that open-system processes play a dominant role. However, the studies rely heavily on bulk rock compositions and overlook complex mineral textures and compositions. To better understand the complex processes at work at MBVF, we focus on establishing mineral and crystal clot populations in three andesitic flow units (55-59% SiO2). Petrographic and geochemical analyses suggest that variable-composition crystal clot and phenocryst populations in a single flow are related. We interpret the crystal clots to represent cumulates entrained in the erupting host magma and that related phenocrysts are disaggregates of crystal clots. The existence of common, multiple phenocryst and crystal clot populations in each flow of different age and SiO2 content provides strong evidence that intermediate magmas of MBVF are more than just the end product of mixing between two magmas. Furthermore, we suggest that most phenocrysts do not represent equilibrium products of their host liquid, evident from wide compositional ranges of ferromagnesian minerals (e.g. augite core Mg# 70-87). In fact, the most primitive phenocryst populations show the least amount of disequilibrium texture but represent assemblages expected to fractionate from basaltic to basaltic-andesitic liquids rather than equilibrium assemblages from their host bulk rock "liquid" composition. As a result, we interpret the variable SiO2 signature of the three andesitic flow units to have been obtained through the incorporation of cumulates/liquids as basaltic to basaltic-andesitic magma ascends.

Ring discharge on the backsurface of a composite skin with ohmic anisotropy in response to frontal high current injection

NASA Astrophysics Data System (ADS)

Lee, T. S.; Robb, J. D.

The ring discharge hazard to a carbon-reinforced-composites fuel tank skin under lightning strike conditions is investigated. A model of anisotropy in electric conductivity is adopted whereby longitudinal conductivity and transverse conductivity are considered separately. It is concluded that the current flow pattern contains a stagnation-dominated near-field region and a geometry-dominated far-field decaying region. While this pattern is unaltered by anisotropy in conductivity, the accompanying nonliner electrical field pattern is greatly distorted. It is noted that conclusions applicable to the ignition hazard which were derived from the model of a uniform scalar conductivity for the skin still remain intact.

Mesozoic ash-flow caldera fragments in southeastern Arizona and their relation to porphyry copper deposits.

USGS Publications Warehouse

Lipman, P.W.; Sawyer, D.A.

1985-01-01

Jurassic and Upper Cretaceous volcanic and associated granitic rocks in SE Arizona are remnants of large composite silicic volcanic fields, characterized by voluminous ash-flow tuffs and associated calderas. Presence of 10-15 large caldera fragments is inferred primarily from 1) ash-flow deposits over 1 km thick, having features of inter-caldera ponding; 2) 'exotic-block' breccia within a tuff matrix, interpreted as caldera-collapse megabreccia; and 3) local granitic intrusion along arcuate structural boundaries of the thick volcanics. Several major porphyry copper deposits are associated with late granitic intrusions within the calderas or along their margins. Such close spatial and temporal association casts doubt on models that associate porphyry copper deposits exclusively with intermediate composition strato-volcanoes. -L.C.H.

Laminar mixing in a small floating zone

NASA Technical Reports Server (NTRS)

Harriott, George M.

1987-01-01

The relationship between the flow and solute fields during steady mass transfer of a dilute component is analyzed for multi-cellular rotating flows in the floating zone process of semiconductor growth. When the recirculating flows are weak in relation to the rate of crystal growth, a closed-form solution clearly shows the link between the convection pattern in the melt and the solute distribution across the surface of the growing solid. In the limit of strong convection, finite element calculations demonstrate the tendency of the composition to become uniform over the majority of the melt. The solute segregation in the product crystal is greatest when the recirculating motion is comparable to the rate of crystal growth, and points to the danger in attempting to grow compositionally uniform materials from a nearly convectionless melt.

Cassini Observations of Saturn's Magnetotail Region: Preliminary Results

NASA Technical Reports Server (NTRS)

Sittler, E. C.; Arridge, C.; Rymer, A.; Coates, A.; Krupp, N.; Blanc, M.; Richardson, J.; Andre, N.; Thomsen, M.; Tokar, R. L.;

Coupled Monte Carlo Probability Density Function/ SPRAY/CFD Code Developed for Modeling Gas-Turbine Combustor Flows

NASA Technical Reports Server (NTRS)

1995-01-01

The success of any solution methodology for studying gas-turbine combustor flows depends a great deal on how well it can model various complex, rate-controlling processes associated with turbulent transport, mixing, chemical kinetics, evaporation and spreading rates of the spray, convective and radiative heat transfer, and other phenomena. These phenomena often strongly interact with each other at disparate time and length scales. In particular, turbulence plays an important role in determining the rates of mass and heat transfer, chemical reactions, and evaporation in many practical combustion devices. Turbulence manifests its influence in a diffusion flame in several forms depending on how turbulence interacts with various flame scales. These forms range from the so-called wrinkled, or stretched, flamelets regime, to the distributed combustion regime. Conventional turbulence closure models have difficulty in treating highly nonlinear reaction rates. A solution procedure based on the joint composition probability density function (PDF) approach holds the promise of modeling various important combustion phenomena relevant to practical combustion devices such as extinction, blowoff limits, and emissions predictions because it can handle the nonlinear chemical reaction rates without any approximation. In this approach, mean and turbulence gas-phase velocity fields are determined from a standard turbulence model; the joint composition field of species and enthalpy are determined from the solution of a modeled PDF transport equation; and a Lagrangian-based dilute spray model is used for the liquid-phase representation with appropriate consideration of the exchanges of mass, momentum, and energy between the two phases. The PDF transport equation is solved by a Monte Carlo method, and existing state-of-the-art numerical representations are used to solve the mean gasphase velocity and turbulence fields together with the liquid-phase equations. The joint composition PDF approach was extended in our previous work to the study of compressible reacting flows. The application of this method to several supersonic diffusion flames associated with scramjet combustor flow fields provided favorable comparisons with the available experimental data. A further extension of this approach to spray flames, three-dimensional computations, and parallel computing was reported in a recent paper. The recently developed PDF/SPRAY/computational fluid dynamics (CFD) module combines the novelty of the joint composition PDF approach with the ability to run on parallel architectures. This algorithm was implemented on the NASA Lewis Research Center's Cray T3D, a massively parallel computer with an aggregate of 64 processor elements. The calculation procedure was applied to predict the flow properties of both open and confined swirl-stabilized spray flames.

Characterization of magnetic nanoparticles using programmed quadrupole magnetic field-flow fractionation

PubMed Central

Williams, P. Stephen; Carpino, Francesca; Zborowski, Maciej

2010-01-01

Quadrupole magnetic field-flow fractionation is a relatively new technique for the separation and characterization of magnetic nanoparticles. Magnetic nanoparticles are often of composite nature having a magnetic component, which may be a very finely divided material, and a polymeric or other material coating that incorporates this magnetic material and stabilizes the particles in suspension. There may be other components such as antibodies on the surface for specific binding to biological cells, or chemotherapeutic drugs for magnetic drug delivery. Magnetic field-flow fractionation (MgFFF) has the potential for determining the distribution of the magnetic material among the particles in a given sample. MgFFF differs from most other forms of field-flow fractionation in that the magnetic field that brings about particle separation induces magnetic dipole moments in the nanoparticles, and these potentially can interact with one another and perturb the separation. This aspect is examined in the present work. Samples of magnetic nanoparticles were analysed under different experimental conditions to determine the sensitivity of the method to variation of conditions. The results are shown to be consistent and insensitive to conditions, although magnetite content appeared to be somewhat higher than expected. PMID:20732895

Mass flow of a volatile organic liquid mixture in soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerstl, Z.; Galin, Ts.; Yaron, B.

1994-05-01

The flow of kerosene, a volatile organic liquid mixture (VOLM), was studied in loam and clay soils and in a medium sand. The kerosene residual capacity and conductivity were determined for all three media at different initial moisture contents and with kerosene of different compositions. The kerosene conductivity of the soil was found to be strongly influenced by the soil texture and initial moisture content as well as by the kerosene composition. The kerosene conductivity of the sand was two orders of magnitude greater than that of the soils and was unaffected by initial moisture contents as high as fieldmore » capacity. The kerosene conductivity of the loam soil was similar in oven dry and air dry soils, but increased significantly in soils at 70% and fun field capacity due to the Yuster effect. In the clay soil the kerosene conductivity of the air dry sod was four times that of the oven dry sod and increased somewhat in the soil at 70% field capacity. No kerosene flow was observed in the oven dry soil at full field capacity. The differences in kerosene conductivity in these soils and the effect of moisture content were attributed to the different pore-sin distributions of the soil& Changes in the composition of the kerosene due to volatilization of the light fractions resulted in increased viscosity of the residual kerosene. This increased viscosity affected the fluid properties of kerosene, which resulted in decreased kerosene conductivity in the sand and the soils. 29 refs., 4 figs., 4 tabs.« less

Numerical simulation on semi-solid die-casting of magnesium matrix composite based on orthogonal experiment

NASA Astrophysics Data System (ADS)

Liu, Huihui; He, Xiongwei; Guo, Peng

2017-04-01

Three factors (pouring temperature, injection speed and mold temperature) were selected to do three levels L9 (33)orthogonal experiment, then simulate processing of semi-solid die-casting of magnesium matrix composite by Flow-3D software. The stress distribution, temperature field and defect distribution of filling process were analyzed to find the optimized processing parameter with the help of orthogonal experiment. The results showed that semi-solid has some advantages of well-proportioned stress and temperature field, less defect concentrated in the surface. The results of simulation were the same as the experimental results.

Field-trip guide to the geologic highlights of Newberry Volcano, Oregon

USGS Publications Warehouse

Jensen, Robert A.; Donnelly-Nolan, Julie M.

2017-08-09

Newberry Volcano and its surrounding lavas cover about 3,000 square kilometers (km2) in central Oregon. This massive, shield-shaped, composite volcano is located in the rear of the Cascades Volcanic Arc, ~60 km east of the Cascade Range crest. The volcano overlaps the northwestern corner of the Basin and Range tectonic province, known locally as the High Lava Plains, and is strongly influenced by the east-west extensional environment. Lava compositions range from basalt to rhyolite. Eruptions began about half a million years ago and built a broad composite edifice that has generated more than one caldera collapse event. At the center of the volcano is the 6- by 8-km caldera, created ~75,000 years ago when a major explosive eruption of compositionally zoned tephra led to caldera collapse, leaving the massive shield shape visible today. The volcano hosts Newberry National Volcanic Monument, which encompasses the caldera and much of the northwest rift zone where mafic eruptions occurred about 7,000 years ago. These young lava flows erupted after the volcano was mantled by the informally named Mazama ash, a blanket of volcanic ash generated by the eruption that created Crater Lake about 7,700 years ago. This field trip guide takes the visitor to a variety of easily accessible geologic sites in Newberry National Volcanic Monument, including the youngest and most spectacular lava flows. The selected sites offer an overview of the geologic story of Newberry Volcano and feature a broad range of lava compositions. Newberry’s most recent eruption took place about 1,300 years ago in the center of the caldera and produced tephra and lava of rhyolitic composition. A significant mafic eruptive event occurred about 7,000 years ago along the northwest rift zone. This event produced lavas ranging in composition from basalt to andesite, which erupted over a distance of 35 km from south of the caldera to Lava Butte where erupted lava flowed west to temporarily block the Deschutes River. Because of Newberry Volcano’s proximity to populated areas, the presence of hot springs within the caldera, and the long and recent history of eruptive activity (including explosive activity), the U.S. Geological Survey installed monitoring equipment on the volcano. A recent geophysical study indicates the presence of magma at 3 to 5 km beneath the caldera.The writing of this guide was prompted by a field trip to Crater Lake and Newberry Volcano organized in conjunction with the August 2017 IAVCEI quadrennial meeting in Portland, Oregon. Both field trip guides are available online. These two volcanoes were grouped in a single field trip because they are two of the few Cascades volcanoes that have generated calderas and significant related tephra deposits.

The effect of rotating magnetic field on the microstructure of in situ TiB2/Cu composites

NASA Astrophysics Data System (ADS)

Zou, C.; Kang, H.; Li, R.; Li, M.; Wang, W.; Chen, Z.; Wang, T.

2016-03-01

Nano ceramic particulate reinforced metal matrix composites are confronted with the problem of particle aggregation emerging in the process of solidification. It sharply deteriorates the mechanical properties of the composites. In order to improve the microstructure and particle distribution, in situ TiB2/Cu composites were prepared using Ti and Cu-B master alloys in a vacuum medium frequency induction furnace equipped with a rotating magnetic field (RMF). The effect of RMF magnetic field intensity employed on the microstructure and particles distribution of the TiB2/Cu composites were investigated. The results show that with the applied RMF, TiB2 particles are homogeneously distributed in the copper matrix, which significantly improves the mechanical properties of TiB2/Cu composites. The mechanism of RMF may be ascribed to the following two aspects. On the one hand, the electromagnetic body force generated by appropriate RMF drives forced convection in the equatorial plane of composite melt during solidification. On the other hand, a secondary flow in the meridional plane is engendered by a radial pressure gradient, thus making a strong agitation in the melt. These two effects result in a homogenous dispersion of TiB2 particles in the copper matrix, and hence excellent properties of TiB2/Cu composites were obtained.

Elemental ratios for characterization of quantum-dots populations in complex mixtures by asymmetrical flow field-flow fractionation on-line coupled to fluorescence and inductively coupled plasma mass spectrometry.

PubMed

Menendez-Miranda, Mario; Fernandez-Arguelles, Maria T; Costa-Fernandez, Jose M; Encinar, Jorge Ruiz; Sanz-Medel, Alfredo

2014-08-11

Separation and identification of nanoparticles of different composition, with similar particle diameter, coexisting in heterogeneous suspensions of polymer-coated CdSe/ZnS quantum dots (QDs) have been thoroughly assessed by asymmetric flow field-flow fractionation (AF4) coupled on-line to fluorescence and inductively coupled plasma mass spectrometry (ICPMS) detectors. Chemical characterization of any previously on-line separated nanosized species was achieved by the measurement of the elemental molar ratios of every element involved in the synthesis of the QDs, using inorganic standards and external calibration by flow injection analysis (FIA). Such elemental molar ratios, strongly limited so far to pure single nanoparticles suspensions, have been achieved with adequate accuracy by coupling for the first time an ICP-QQQ instrument to an AF4 system. This hyphenation turned out to be instrumental to assess the chemical composition of the different populations of nanoparticles coexisting in the relatively complex mixtures, due to its capabilities to detect the hardly detectable elements involved in the synthesis. Interestingly such information, complementary to that obtained by fluorescence, was very valuable to detect and identify unexpected nanosized species, present at significant level, produced during QDs synthesis and hardly detectable by standard approaches. Copyright © 2014. Published by Elsevier B.V.

Prediction for the Flow-induced Gravity Field of Saturn: Implications for Cassini’s Grand Finale

NASA Astrophysics Data System (ADS)

Galanti, Eli; Kaspi, Yohai

2017-07-01

The Cassini measurements of Saturn’s gravity field during its Grand Finale might shed light on a long-standing question regarding the flow on Saturn. While the cloud-level winds are well known, little is known about whether these winds are confined to the outer layers of the planet or penetrate deep into the interior. An additional complexity is added by the uncertainty in the exact rotation period of Saturn, a key factor in determining the cloud-level winds, with an effect on the north-south symmetric part of the winds. Using Saturn’s cloud-level winds we relate the flow to the gravity harmonics. We give a prediction for the odd harmonics {J}3,{J}5,{J}7,{and} {J}9 as a function of the flow depth, identifying three ranges of depths. Since the odd harmonics depend solely on the flow, and are not influenced by Saturn’s shape and static density distribution, any measured value of the odd harmonics by Cassini can be used to uniquely determine the depth of the flow. We also discuss the flow-induced even harmonics {{Δ }}{J}2,{{Δ }}{J}4,\\ldots ,{{Δ }}{J}12 that are affected by Saturn’s rotation period. While the high-degree even harmonics might also be used to determine the flow depth, the lower-degree even harmonics serve as uncertainties for analysis of the planet’s interior structure and composition. Thus, the gravity harmonics measured during the Cassini Grand Finale may be used to get a first-order estimate of the flow structure and to better constrain the planet’s density structure and composition.

Superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles by inelastic collision via ultrasonic field: Role of colloidal stability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sodipo, Bashiru Kayode; Azlan, Abdul Aziz; Innovation

2015-04-24

Superparamagnetic iron oxide nanoparticles (SPION)/Silica composite nanoparticles were prepared by ultrasonically irradiating colloidal suspension of silica and SPION mixture. Both silica and SPION were synthesized independently via co-precipitation and sol-gel method, respectively. Their mixtures were sonicated at different pH between 3 and 5. Electrophoresis measurement and other physicochemical analyses of the products demonstrate that at lower pH SPION was found incorporated into the silica. However, at pH greater than 4, SPION was unstable and unable to withstand the turbulence flow and shock wave from the ultrasonic field. Results suggest that the formation of the SPION/silica composite nanoparticles is strongly relatedmore » to the inelastic collision induced by ultrasonic irradiation. More so, the formation the composite nanoparticles via the ultrasonic field are dependent on the zeta potential and colloidal stability of the particles.« less

Induced charge electroosmosis micropumps using arrays of Janus micropillars.

PubMed

Paustian, Joel S; Pascall, Andrew J; Wilson, Neil M; Squires, Todd M

2014-09-07

We report on a microfluidic AC-driven electrokinetic pump that uses Induced Charge Electro-Osmosis (ICEO) to generate on-chip pressures. ICEO flows occur when a bulk electric field polarizes a metal object to induce double layer formation, then drives electroosmotic flow. A microfabricated array of metal-dielectric Janus micropillars breaks the symmetry of ICEO flow, so that an AC electric field applied across the array drives ICEO flow along the length of the pump. When pumping against an external load, a pressure gradient forms along the pump length. The design was analyzed theoretically with the reciprocal theorem. The analysis reveals a maximum pressure and flow rate that depend on the ICEO slip velocity and micropillar geometry. We then fabricate and test the pump, validating our design concept by demonstrating non-local pressure driven flow using local ICEO slip flows. We varied the voltage, frequency, and electrolyte composition, measuring pump pressures of 15-150 Pa. We use the pump to drive flows through a high-resistance microfluidic channel. We conclude by discussing optimization routes suggested by our theoretical analysis to enhance the pump pressure.

Volcanic eruptions on mid-ocean ridges: New evidence from the superfast spreading East Pacific Rise, 17°-19°S

NASA Astrophysics Data System (ADS)

Sinton, John; Bergmanis, Eric; Rubin, Ken; Batiza, Rodey; Gregg, Tracy K. P.; Grönvold, Karl; Macdonald, Ken C.; White, Scott M.

2002-06-01

Side-scan sonar, submersible observations and sampling of lava flows from the East Pacific Rise, 17°-19°S constrain the character and variability of submarine volcanic eruptions along mid-ocean ridges. Nine separate lava sequences were mapped using relative age and lithological contrasts among recovered samples. Axial lengths activated during eruptive episodes range from ~1 to >18 km; individual flow field areas vary from <1 to >19 km2. Estimated erupted volumes range from <1 to >200 × 106 m3. The largest unit is the chemically uniform Animal Farm lava near 18°37'S. The youngest lava is the Aldo-Kihi flow field, 17°24'-34'S, probably erupted in the early 1990s from a fissure system extending >18 km along axis. Near 18°33'S two distinct lava compositions with uniform sediment cover were recovered from lava that buries older faulted terrain. The boundary in lava composition coincides with a change in depth to the top of an axial magma lens seismic reflector, consistent with magmas from two separate reservoirs being erupted in the same event. Chemical compositions from throughout the area indicate that lavas with identical compositions can be emplaced in separate volcanic eruptions within individual segments. A comparison of our results to global data on submarine mid-ocean ridge eruptions suggests consistent dependencies of erupted volume, activated fissure lengths, and chemical heterogeneity with spreading rate, consistent with expected eruptive characteristics from ridges with contrasting thermal properties and magma reservoir depths.

Age and petrology of the Tertiary As Sarat volcanic field, southwestern Saudi Arabia

USGS Publications Warehouse

du Bray, E.A.; Stoeser, D.B.; McKee, E.H.

1991-01-01

Harrat As Sarat forms the second smallest and southernmost of the basalt fields of western Saudi Arabia and is part of a voluminous Red Sea rift-related continental alkali basalt province. The rocks of the As Sarat were emplaced during the first stage of Red Sea rifting and represent the northernmost extension of the Tertiary Trap Series volcanics that occur mainly in the Yemen Arab Republic and Ethiopia. The field consists of up to 580 m of basalt flows, that are intruded by basaltic plugs, necks, minor dikes, and highly evolved peralkaline trachyte intrusions. K-Ar ages indicate that the As Sarat field formed between 31 and 22 Ma and contains an eruption hiatus of one million years that began about 25 Ma ago. Pre-hiatus flows are primarily hypersthene normative intersertal subalkaline basalt, whereas the majority of post-hiatus flows are nepheline normative alkali basalt and hawaiite with trachytic textures. Normative compositions of the basalts are consistent with their genesis by partial melting at varying depths. Trace element abundances in the basalt indicate that varying degrees of partial melting and fractional crystallization (or crystal accumulation) had major and minor roles, respectively, in development of compositional variation in these rocks. Modeling indicates that the pre-hiatus subalkaline basalts represent 8-10 percent mantle melting at depths of about 70 km and the post-hiatus alkali basalts represent 4-9 percent mantle melting at depths greater than 70 km. ?? 1991.

Directional change during a Miocene R-N geomagnetic polarity reversal recorded by mafic lava flows, Sheep Creek Range, north central Nevada, USA

NASA Astrophysics Data System (ADS)

Bogue, S. W.; Glen, J. M. G.; Jarboe, N. A.

2017-09-01

Recurring transitional field directions during three Miocene geomagnetic reversals provide evidence that lateral inhomogeneity of the lower mantle affects flow in the outer core. We compare new paleomagnetic results from a composite sequence of 15.2 Ma lava flows in north central Nevada (Sheep Creek Range; 40.7°N, 243.2°E), erupted during a polarity reversal, to published data from Steens Mountain (250 km to the northwest in Oregon) and the Newberry Mountains (650 km to the south in California) that document reversals occurring millions of years and many polarity switches earlier. Alternating field demagnetization, followed by thermal demagnetization in half the samples, clearly isolated the primary thermoremanent magnetization of Sheep Creek Range flows. We correlated results from our three sampled sections to produce a composite record that begins with a single virtual geomagnetic pole (VGP) at low latitude in the Atlantic, followed by two VGPs situated near latitude 30°N in NE Africa. After jumping to 83°N (one VGP), the pole moves to equatorial South America (one VGP), back to NE Africa (three VGPs), to high southern latitudes (two VGPs), back to equatorial South America (three VGPs), and finally to high northern latitudes (nine VGPs). The repeated visits of the transitional VGP to positions in South America and near NE Africa, as well as the similar behavior recorded at Steens Mountain and the Newberry Mountains, suggest that lower mantle or core-mantle boundary features localize core flow structures, thereby imparting a discernible regional structure on the transitional geomagnetic field that persists for millions of years.

Saturn's Magnetosphere and Properties of Upstream Flow at Titan: Preliminary Results

NASA Technical Reports Server (NTRS)

Sittler, E. C., Jr.; Hartle, R. E.; Cooper, J. F.; Lipatov, A.; Bertucci, C.; Coates, A. J.; Arridge, C.; Szego, K.; Shappirio, M.; Simipson, D. G.;

High-Latitude Geomagnetic Secular Variation and Paleointensity during 6-0.5 Ma: Paleomagnetic Results from Eastern Iceland

NASA Astrophysics Data System (ADS)

Døssing, A.; Muxworthy, A. R.; Mac Niocaill, C.; Riishuus, M. S.

2014-12-01

Statistical analyses of paleomagnetic data from sequential lava flows allow us to study the geomagnetic field behaviour on kyr to Myr timescales. Previous paleomagnetic studies lack high-latitude, high-quality measurements and the resolution necessary to investigate the persistence of high-latitude geomagnetic field anomalies observed in the recent and historical field records, and replicated in some numerical geodynamo simulations. As part of the Time-Averaged Field Initiative (TAFI) project, lava sequences exposed in Nordurdalur (by Fljótsdalur) and Jökuldalur in eastern Iceland provide an excellent opportunity to improve high-latitude data suitable for investigating the 6-0.5 Ma TAF and paleosecular variation. These adjacent valleys, separated by 40 km, host a composite stratigraphic record of lava flows erupted from the Northern Rift Zone between 0.5 and ~6.5 Ma (one lava flow extruded every ~15-40 kyr). Hiatuses are present locally in the younger sections, at ~0.9 Ma and 2 Ma (spanning 200-400 kyr), that contain frequent hyaloclastites and sediments. In 2013, we collected a total of ~2200 cores (10-18 cores/site; mean = ~13 cores/site) from ~140 separate lava flows (165 in total) along eight stratigraphic profiles in Nordurdalur and Jökuldalur. In addition, hand samples were collected from ~70 sites to deliver new 40Ar/39Ar radiometric age determinations. We present the final results of AF- and thermal demagnetization of ~10 specimens/flow, comprising 165 (~140 distinct) paleomagnetic directions, along with updated composite litho-, chrono- and magnetostratigraphy of the exposed volcanic pile in Nordurdalur and Jökuldalur. We present the dispersion of the Arctic virtual geomagnetic poles over the last 6.5 Ma. In addition, we present a number of new IZZI paleointensity results from Jökuldalur. The geomagnetic results are compared and contrasted with other high-latitude data.

Rejuvenescent Volcanism on San Cristóbal Island, Galápagos: A Late "Plumer"

NASA Astrophysics Data System (ADS)

Mahr, J.; Harpp, K. S.; Kurz, M. D.; Geist, D.; Bercovici, H.; Pimentel, R.; Cleary, Z.; Córdova Aguilar, M. D.

2016-12-01

Nestled between the two volcanoes of San Cristóbal Island in the Galápagos is a series of curiously young basaltic lava flows. These flows are not vegetated and have well-preserved flow tops, indicating that they are a rejuvenescent phase of volcanism. The young lava region covers 70 km2 of the NW coast and consists of five flow fields from 5 to 17 km2. We report new cosmogenic helium exposure ages that indicate emplacement occurred 9 to 15 ka, and that the surrounding area was active since 174 ka; a hiatus in activity may have occurred between 174 and 15 ka. These dates contrast with the fact that San Cristóbal is one of the oldest islands in the archipelago, with several K-Ar ages >2 Ma. Petrographically, the young lavas are mostly olivine-phyric (1-5 mm, average 5% abundance). Plagioclase phenocrysts are small (<1 mm) and rarely exceed 3% in abundance. Some flows range in their crystal cargo over rather short distances (<30 m). Compositional variation of this small set of young flows encompasses the compositional range exhibited by lavas from across the island. Rare earth element patterns are flat to LREE-enriched, even within the same flow field. Incompatible trace element ratios (e.g., La/Sm) indicate a wide range in extents of melting at relatively shallow depths (e.g., low Sm/Yb), comparable to conditions observed at Floreana Island. Compositions are consistent with a source that is a mixture of Galápagos plume and ancient, recycled oceanic crust (FLO source of Harpp and White, 2001). The contribution from the plume source is notable given the island's location in the eastern archipelago, where plume influence is normally lower than in the western islands. The young lavas are primitive compared to the majority of the archipelago and to other lavas on San Cristóbal, having only crystallized olivine and sparse CPX. These observations are consistent with a model in which melts pass through the crust relatively quickly, without extensive fractionation or homogenization prior to eruption. Because late stage lavas in the Galápagos have similar source compositions to the rest of the island, we propose that the mechanism for rejuvenescent volcanism in the Galápagos differs from that proposed for other ocean island systems, such as Hawai'i.

Quantitative characterization of the carbon/carbon composites components based on video of polarized light microscope.

PubMed

Li, Yixian; Qi, Lehua; Song, Yongshan; Chao, Xujiang

2017-06-01

The components of carbon/carbon (C/C) composites have significant influence on the thermal and mechanical properties, so a quantitative characterization of component is necessary to study the microstructure of C/C composites, and further to improve the macroscopic properties of C/C composites. Considering the extinction crosses of the pyrocarbon matrix have significant moving features, the polarized light microscope (PLM) video is used to characterize C/C composites quantitatively because it contains sufficiently dynamic and structure information. Then the optical flow method is introduced to compute the optical flow field between the adjacent frames, and segment the components of C/C composites from PLM image by image processing. Meanwhile the matrix with different textures is re-segmented by the length difference of motion vectors, and then the component fraction of each component and extinction angle of pyrocarbon matrix are calculated directly. Finally, the C/C composites are successfully characterized from three aspects of carbon fiber, pyrocarbon, and pores by a series of image processing operators based on PLM video, and the errors of component fractions are less than 15%. © 2017 Wiley Periodicals, Inc.

The effect of liquid target on a nonthermal plasma jet—imaging, electric fields, visualization of gas flow and optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Kovačević, Vesna V.; Sretenović, Goran B.; Slikboer, Elmar; Guaitella, Olivier; Sobota, Ana; Kuraica, Milorad M.

2018-02-01

The article describes the complex study of the interaction of a helium plasma jet with distilled water and saline. The discharge development, spatial distribution of the excited species, electric field measurement results and the results of the Schlieren imaging are presented. The results of the experiments showed that the plasma-liquid interaction could be prolonged with the proper choice of the gas composition between the jet nozzle and the target. This depends on the gas flow and the target distance. Increased conductivity of the liquid does not affect the discharge properties significantly. An increase of the gas flow enables an extension of the plasma duration on the liquid surface up to 10 µs, but with a moderate electric field strength in the ionization wave. In contrast, there is a significant enhancement of the electric field on the liquid surface, up to 30 kV cm-1 for low flows, but with a shorter time of the overall plasma liquid interaction. Ignition of the plasma jet induces a gas flow modification and may cause turbulences in the gas flow. A significant influence of the plasma jet causing a mixing in the liquid is also recorded and it is found that the plasma jet ignition changes the direction of the liquid circulation.

A Numerical Investigation of the Effect of Thermoelectromagnetic Convection (TEMC) on the Bridgman Growth of Ge(1-x)Si(x)

NASA Technical Reports Server (NTRS)

Yesilyurt, Serhat; Vujisic, Ljubomir; Motakef, Shariar; Szofran, F. R.; Volz, Martin P.

1998-01-01

Thermoelectric currents at the growth interface of GeSi during Bridgman growth are shown to promote convection when a low intensity axial magnetic field is applied. TEMC, typically, is characterized by a meridional flow driven by the rotation of the fluid; meridional convection alters composition of the melt, and shape of the growth interface substantially. TEMC effect is more important in micro-gravity environment than the terrestrial one, and can be used to control convection during the growth of GeSi. In this work, coupled thermo-solutal flow equations (energy, scalar transport, momentum and mass) are solved in tandem with Maxwell's equations to compute the thermo-solutat flow field, electric currents, and the growth-interface shape.

Numerical study on the thermo-chemically driven Geodynamo

NASA Astrophysics Data System (ADS)

Trümper, Tobias; Hansen, Ulrich

2014-05-01

In our numerical study we consider magneto-convection in the Earth's outer core driven by buoyancy induced by heterogeneities both in the thermal and the chemical field. The outer core is thus treated as a self-gravitating, rotating, spherical shell with unstable thermal and chemical gradients across its radius. The thermal gradient is maintained by secular cooling of the core and the release of latent heat at the inner core freezing front. Simultaneously, the concentration of the light constituents of the liquid phase increases at the inner core boundary since only a smaller fraction of the light elements can be incorporated during solidification. Thus, the inner core boundary constitutes a source of compositional buoyancy. The molecular diffusivities of the driving agents differ by some orders of magnitude so that a double-diffusive model is employed in order to study the flow dynamics of this system. We investigate the influence of different thermo-chemical driving scenarios on the structure of the flow and the internal magnetic field. A constant ratio of the diffusivities (Le=10) and a constant Ekman number (Ek=10-4) are adopted. Apart from testing different driving scenarios, the double-diffusive approach also allows to implement distinct boundary conditions on temperature and composition. Isochemical and fixed chemical flux boundary conditions are implemented in order to investigate their respective influence on the flow and magnetic field generation.

Comparison of Plains Volcanism in the Tempe Terra Region of Mars to the Eastern Snake River Plains, Idaho with Implications for Geochemical Constraints

NASA Technical Reports Server (NTRS)

Weren, S. L.; Sakimoto, S. E. H.; Hughes, S. S.; Gregg, T. K. P.

2004-01-01

The Eastern Snake River Plains (ESRP) in Idaho have long been considered a terrestrial analog for the plains volcanism like that evident in Syria Planum and Tempe Terra, Mars. Both the ESRP and Tempe Terra are sediment-blanketed volcanic fields in areas with significant extensional faulting. Similar volcanic features can be observed throughout both study areas using field analysis and DEMs of the ESRP and the Mars Global Surveyor (MGS) data from Mars. These features include flow fields, low shields, shields with steep summits, and fissure eruptions. A few other volcanic features, such as cinder cones, which suggest variable compositions, volatile interactions, and multiple volcanic events can be seen in both areas. The eruptions in both the ESRP and Tempe Terra generally originate from the fissures creating elongate, multi-vent shields as well as isolated or aligned single vent shields. Many of these show evidence of radial flow patterns from summit craters as well as lava tube fed flows. The volcanoes of Tempe Terra display some of the global latitudinal parameter trends of small volcanoes on Mars. Some of these trends may be explained by the variation of volatile content and compositional variation across Mars. However, within Tempe Terra no significant local latitudinal trends can be seen in edifice attributes and not all variations are explained by global trends. This study builds upon previous studies of the Tempe Terra region and the ESRP in order to develop a more detailed representation of features and topographic data. Using these data we attempt to help constrain the composition and eruptive style of the Tempe Terra volcanoes by correlating them with the similar and quantified ESRP variations.

Shear rheology and 1H TD-NMR combined to low-field RheoNMR: Set-up and application to quiescent and flow-induced crystallization of polymers

NASA Astrophysics Data System (ADS)

Räntzsch, Volker; Özen, Mürüvvet Begüm; Ratzsch, Karl-Friedrich; Guthausen, Gisela; Wilhelm, Manfred

2017-05-01

Rheology provides access to the flow properties of soft matter, while 1H TD-NMR is a useful technique for the characterization of molecular dynamics. To achieve greater insight into the interplay of these domains, especially under flow, it is desirable to combine these two methods in one set-up. We present a low-field RheoNMR set-up based on a portable 30 MHz 1H NMR unit that was integrated into a commercial strain-controlled shear rheometer. This unique combination can simultaneously conduct a full rheological characterization (G', G", |η*|, FT-Rheology: I3/1, Q0) while monitoring molecular dynamics in-situ via 1H TD-NMR for temperatures from -15 to +210 °C. Possible applications include the quantitative measurement of the composition in multiphase systems (fats, polymers, etc.) and soft matter during the application of flow, e.g. measurements on the flow-induced crystallization of polymers.

Correlation of ash-flow tuffs.

USGS Publications Warehouse

Hildreth, W.; Mahood, G.

1985-01-01

Discrimination and correlation of ash-flow sheets is important in structurally complex, long-lived volcanic fields where such sheets provide the best keys to the regional stratigraphic framework. Three-dimensional complexities resulting from pulsatory eruptions, sectorial emplacement, mechanical sorting during outflow, thermal and compositional zoning of magmas, the physical zoning of cooling units, and structural and erosional disruption can make such correlation and discrimination difficult. When lithologic, magnetic, petrographic, chemical, and isotopic criteria for correlating ash-flow sheets are critically evaluated, many problems and pitfalls can be identified. Distinctive phenocrysts, pumice clasts, and lithic fragments are among the more reliable criteria, as are high-precision K-Ar ages and thermal remanent magnetization (TRM) directions in unaltered welded tuff. Chemical correlation methods should rely principally upon welded or nonwelded pumice blocks, not upon the ash-flow matrix, which is subject to fractionation, mixing, and contamination during emplacement. Compositional zoning of most large sheets requires that many samples be analyzed before phenocryst, glass or whole-rock chemical trends can be used confidently as correlation criteria.-Authors

PEVC-FMDF for Large Eddy Simulation of Compressible Turbulent Flows

NASA Astrophysics Data System (ADS)

Nouri Gheimassi, Arash; Nik, Mehdi; Givi, Peyman; Livescu, Daniel; Pope, Stephen

2017-11-01

The filtered density function (FDF) closure is extended to a ``self-contained'' format to include the subgrid scale (SGS) statistics of all of the hydro-thermo-chemical variables in turbulent flows. These are the thermodynamic pressure, the specific internal energy, the velocity vector, and the composition field. In this format, the model is comprehensive and facilitates large eddy simulation (LES) of flows at both low and high compressibility levels. A transport equation is developed for the joint ``pressure-energy-velocity-composition filtered mass density function (PEVC-FMDF).'' In this equation, the effect of convection appears in closed form. The coupling of the hydrodynamics and thermochemistry is modeled via a set of stochastic differential equation (SDE) for each of the transport variables. This yields a self-contained SGS closure. For demonstration, LES is conducted of a turbulent shear flow with transport of a passive scalar. The consistency of the PEVC-FMDF formulation is established, and its overall predictive capability is appraised via comparison with direct numerical simulation (DNS) data.

The experimental study of heat transfer around molds inside a model autoclave

NASA Astrophysics Data System (ADS)

Ghamlouch, Taleb; Roux, Stéphane; Lefèvre, Nicolas; Bailleul, Jean-Luc; Sobotka, Vincent

2018-05-01

The temperature distribution within composite parts manufactured inside autoclaves plays a key role in determining the parts quality at the end of the curing cycle. Indeed, heat transfer between the parts and the surroundings inside an autoclave is strongly coupled with the flow field around the molds and can be modeled through the convective heat transfer coefficient (HTC). The aerodynamically unsuitable geometry of the molds generates complex turbulent non-uniform flows around them accompanied with the presence of dead zones. This heterogeneity can imply non-uniform convective heat transfers leading to temperature gradients inside parts that can be prejudicial. Given this fact, the purpose of this study is to perform experimental measurements in order to describe the flow field and the convective heat transfer behavior around representative industrial molds installed inside a home-made model. A key point of our model autoclave is the ease of use of non-intrusive measuring instruments: the Particle Image Velocimetry (PIV) technique and infrared imaging camera for the study of the flow field and the heat transfer coefficient distribution around the molds respectively. The experimental measurements are then compared to computational fluid dynamics (CFD) calculations performed on the computer code ANSYS Fluent 16.0®. This investigation has revealed, as expected, a non-uniform distribution of the convective heat transfer coefficient around the molds and therefore the presence of thermal gradients which can reduce the composite parts quality during an autoclave process. A good agreement has been achieved between the experimental and the numerical results leading then to the validation of the performed numerical simulations.

Thermospheric neutral density estimates from heater-induced ion up-flow at EISCAT

NASA Astrophysics Data System (ADS)

Kosch, Michael; Ogawa, Yasunobu; Yamazaki, Yosuke; Vickers, Hannah; Blagoveshchenskaya, Nataly

We exploit a recently-developed technique to estimate the upper thermospheric neutral density using measurements of ionospheric plasma parameters made by the EISCAT UHF radar during ionospheric modification experiments. Heating the electrons changes the balance between upward plasma pressure gradient and downward gravity, resulting in ion up-flow up to ~200 m/s. This field-aligned flow is retarded by collisions, which is directly related to the neutral density. Whilst the ion up-flow is consistent with the plasma pressure gradient, the estimated thermospheric neutral density depends on the assumed composition, which varies with altitude. Results in the topside ionosphere are presented.

Continious production of exfoliated graphite composite compositions and flow field plates

DOEpatents

Shi, Jinjun; Zhamu, Aruna; Jang, Bor Z.

2010-07-20

A process of continuously producing a more isotropic, electrically conductive composite composition is provided. The process comprises: (a) continuously supplying a compressible mixture comprising exfoliated graphite worms and a binder or matrix material, wherein the binder or matrix material is in an amount of between 3% and 60% by weight based on the total weight of the mixture; (b) continuously compressing the compressible mixture at a pressure within the range of from about 5 psi or 0.035 MPa to about 50,000 psi or 350 MPa in at least a first direction into a cohered graphite composite compact; and (c) continuously compressing the composite compact in a second direction, different from the first direction, to form the composite composition in a sheet or plate form. The process leads to composite plates with exceptionally high thickness-direction electrical conductivity.

Dynamics of Solid-Liquid Composite Beams

NASA Astrophysics Data System (ADS)

Matia, Yoav; Gat, Amir

2017-11-01

Solid-liquid composite structures received considerable attention in recent years in various fields such as smart materials, sensors, actuators and soft-robotics. We examine a beam-like appendage embedded with a set of a fluid-filled bladders, interconnected via elastic slender channels; a common arrangement in the abovementioned fields. Viscous flow within such structures is coupled with the elastic deformation of the solid. Beam deformation both creates, and is induced by, a fluidic pressure gradient and viscous flow which deforms the bladders and thus the surrounding solid. Applying concepts from poroelastic analysis, we obtain a set of three interdependent equations relating the fluidic pressure within the channel to the transverse and longitudinal displacements of the beam. Exact and approximate solutions are presented for various configurations. The results are validated and supplemented by a transient three-dimensional numerical study of the fluid-structure-interaction. The two-way coupled fluid-structure-interaction model allows the analysis and design of soft smart-metamaterials with unique mechanical properties, to applications such as touch-sensing surfaces, energy harvesting and protective gear.

Lead and strontium isotopic evidence for crustal interaction and compositional zonation in the source regions of Pleistocene basaltic and rhyolitic magmas of the Coso volcanic field, California

USGS Publications Warehouse

Bacon, C.R.; Kurasawa, H.; Delevaux, M.H.; Kistler, R.W.; Doe, B.R.

1984-01-01

The isotopic compositions of Pb and Sr in Pleistocene basalt, high-silica rhyolite, and andesitic inclusions in rhyolite of the Coso volcanic field indicate that these rocks were derived from different levels of compositionally zoned magmatic systems. The 2 earliest rhyolites probably were tapped from short-lived silicic reservoirs, in contrast to the other 36 rhyolite domes and lava flows which the isotopic data suggest may have been leaked from the top of a single, long-lived magmatic system. Most Coso basalts show isotopic, geochemical, and mineralogic evidence of interaction with crustal rocks, but one analyzed flow has isotopic ratios that may represent mantle values (87Sr/86Sr=0.7036,206Pb/204Pb=19.05,207Pb/204Pb=15.62,208Pb/204Pb= 38.63). The (initial) isotopic composition of typical rhyolite (87Sr/86Sr=0.7053,206Pb/204Pb=19.29,207Pb/204Pb= 15.68,208Pb/204Pb=39.00) is representative of the middle or upper crust. Andesitic inclusions in the rhyolites are evidently samples of hybrid magmas from the silicic/mafic interface in vertically zoned magma reservoirs. Silicic end-member compositions inferred for these mixed magmas, however, are not those of erupted rhyolite but reflect the zonation within the silicic part of the magma reservoir. The compositional contrast at the interface between mafic and silicic parts of these systems apparently was greater for the earlier, smaller reservoirs. ?? 1984 Springer-Verlag.

High latitude field aligned light ion flows in the topside ionosphere deduced from ion composition and plasma temperatures

NASA Technical Reports Server (NTRS)

Grebowsky, J. M.; Hoegy, W. R.; Chen, T. C.

1993-01-01

Using a comprehensive ionospheric data set comprised of all available ion composition and plasma temperature measurements from satellites, the vertical distributions of ion composition and plasma temperatures are defined from middle latitudes up into the polar cap for summer conditions for altitudes below about 1200 km. These data are sufficient to allow a numerical estimation of the latitudinal variation of the light ion outflows from within the plasmasphere to the polar wind regions. The altitude at which significant light ion outflow begins is found to be lower during solar minimum conditions than during solar maximum. The H(+) outward speeds are of the order of 1 km/s near 1100 km during solar maximum but attain several km/s speeds for solar minimum. He(+) shows a similar altitude development of flow but attains polar cap speeds much less than 1 km/s at altitudes below 1100 km, particularly under solar maximum conditions. Outward flows are also found in the topside F-region for noontime magnetic flux tubes within the plasmasphere.

Rice Field Geochemistry and Hydrology: An Explanation for Why Groundwater Irrigated Fields in Bangladesh are Net Sinks of Arsenic from Groundwater

PubMed Central

Neumann, Rebecca B.; St. Vincent, Allison P.; Roberts, Linda C.; Badruzzaman, A. Borhan M.; Ali, M. Ashraf; Harvey, Charles F.

2011-01-01

Irrigation of rice fields in Bangladesh with arsenic-contaminated groundwater transfers tens of cubic kilometers of water and thousands of tons of arsenic from aquifers to rice fields each year. Here we combine observations of infiltration patterns with measurements of porewater chemical composition from our field site in Munshiganj Bangladesh to characterize the mobility of arsenic in soils beneath rice fields. We find that very little arsenic delivered by irrigation returns to the aquifer, and that recharging water mobilizes little, if any, arsenic from rice field subsoils. Arsenic from irrigation water is deposited on surface soils and sequestered along flow paths that pass through bunds, the raised soil boundaries around fields. Additionally, timing of flow into bunds limits the transport of biologically available organic carbon from rice fields into the subsurface where it could stimulate reduction processes that mobilize arsenic from soils and sediments. Together, these results explain why groundwater irrigated rice fields act as net sinks of arsenic from groundwater. PMID:21332196

Field Measurements of the 1983 Royal Gardens Lava Flows, Kilauea Volcano, and 1984 Mauna Loa Lava Flow, Hawaii

NASA Technical Reports Server (NTRS)

Fink, J.; Zimbelman, J.

1985-01-01

Theoretical models used in the remote determination of lava flow rheology and compositions rely on estimates of such geometric and flow parameters as volume flow rates, levee heights, and channel dimensions, as well as morphologic and structural patterns on the flow surfaces. Quantitative measures of these variables are difficult to obtain, even under optimum conditions. Detailed topographic profiles across several Hawaiian lava flows that were carefully monitored by the U.S. Geological Survey during their emplacement in 1983 were surveyed in order to test various flow emplacement models. Twenty two accurate channel cross sections were constructed by combining these profiles with digitized pre-flow topographic measurements. Levee heights, shear zone widths, and flow depths could then be read directly from the cross sections and input into the models. The profiles were also compared with ones constructed for some Martian lava flows.

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO2 with applications in food and feed.

PubMed

Omar, J; Boix, A; Kerckhove, G; von Holst, C

2016-12-01

Titanium dioxide (TiO 2 ) has various applications in consumer products and is also used as an additive in food and feeding stuffs. For the characterisation of this product, including the determination of nanoparticles, there is a strong need for the availability of corresponding methods of analysis. This paper presents an optimisation process for the characterisation of polydisperse-coated TiO 2 nanoparticles. As a first step, probe ultrasonication was optimised using a central composite design in which the amplitude and time were the selected variables to disperse, i.e., to break up agglomerates and/or aggregates of the material. The results showed that high amplitudes (60%) favoured a better dispersion and time was fixed in mid-values (5 min). In a next step, key factors of asymmetric flow field-flow fraction (AF4), namely cross-flow (CF), detector flow (DF), exponential decay of the cross-flow (CF exp ) and focus time (Ft), were studied through experimental design. Firstly, a full-factorial design was employed to establish the statistically significant factors (p < 0.05). Then, the information obtained from the full-factorial design was utilised by applying a central composite design to obtain the following optimum conditions of the system: CF, 1.6 ml min -1 ; DF, 0.4 ml min -1 ; Ft, 5 min; and CF exp , 0.6. Once the optimum conditions were obtained, the stability of the dispersed sample was measured for 24 h by analysing 10 replicates with AF4 in order to assess the performance of the optimised dispersion protocol. Finally, the recovery of the optimised method, particle shape and particle size distribution were estimated.

Optimisation of asymmetric flow field-flow fractionation for the characterisation of nanoparticles in coated polydisperse TiO2 with applications in food and feed

PubMed Central

Omar, J.; Boix, A.; Kerckhove, G.; von Holst, C.

2016-01-01

ABSTRACT Titanium dioxide (TiO2) has various applications in consumer products and is also used as an additive in food and feeding stuffs. For the characterisation of this product, including the determination of nanoparticles, there is a strong need for the availability of corresponding methods of analysis. This paper presents an optimisation process for the characterisation of polydisperse-coated TiO2 nanoparticles. As a first step, probe ultrasonication was optimised using a central composite design in which the amplitude and time were the selected variables to disperse, i.e., to break up agglomerates and/or aggregates of the material. The results showed that high amplitudes (60%) favoured a better dispersion and time was fixed in mid-values (5 min). In a next step, key factors of asymmetric flow field-flow fraction (AF4), namely cross-flow (CF), detector flow (DF), exponential decay of the cross-flow (CFexp) and focus time (Ft), were studied through experimental design. Firstly, a full-factorial design was employed to establish the statistically significant factors (p < 0.05). Then, the information obtained from the full-factorial design was utilised by applying a central composite design to obtain the following optimum conditions of the system: CF, 1.6 ml min–1; DF, 0.4 ml min–1; Ft, 5 min; and CFexp, 0.6. Once the optimum conditions were obtained, the stability of the dispersed sample was measured for 24 h by analysing 10 replicates with AF4 in order to assess the performance of the optimised dispersion protocol. Finally, the recovery of the optimised method, particle shape and particle size distribution were estimated. PMID:27650879

Core lipid, surface lipid and apolipoprotein composition analysis of lipoprotein particles as a function of particle size in one workflow integrating asymmetric flow field-flow fractionation and liquid chromatography-tandem mass spectrometry

PubMed Central

Jones, Jeffery I.; Gardner, Michael S.; Schieltz, David M.; Parks, Bryan A.; Toth, Christopher A.; Rees, Jon C.; Andrews, Michael L.; Carter, Kayla; Lehtikoski, Antony K.; McWilliams, Lisa G.; Williamson, Yulanda M.; Bierbaum, Kevin P.; Pirkle, James L.; Barr, John R.

2018-01-01

Lipoproteins are complex molecular assemblies that are key participants in the intricate cascade of extracellular lipid metabolism with important consequences in the formation of atherosclerotic lesions and the development of cardiovascular disease. Multiplexed mass spectrometry (MS) techniques have substantially improved the ability to characterize the composition of lipoproteins. However, these advanced MS techniques are limited by traditional pre-analytical fractionation techniques that compromise the structural integrity of lipoprotein particles during separation from serum or plasma. In this work, we applied a highly effective and gentle hydrodynamic size based fractionation technique, asymmetric flow field-flow fractionation (AF4), and integrated it into a comprehensive tandem mass spectrometry based workflow that was used for the measurement of apolipoproteins (apos A-I, A-II, A-IV, B, C-I, C-II, C-III and E), free cholesterol (FC), cholesterol esters (CE), triglycerides (TG), and phospholipids (PL) (phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and lysophosphatidylcholine (LPC)). Hydrodynamic size in each of 40 size fractions separated by AF4 was measured by dynamic light scattering. Measuring all major lipids and apolipoproteins in each size fraction and in the whole serum, using total of 0.1 ml, allowed the volumetric calculation of lipoprotein particle numbers and expression of composition in molar analyte per particle number ratios. Measurements in 110 serum samples showed substantive differences between size fractions of HDL and LDL. Lipoprotein composition within size fractions was expressed in molar ratios of analytes (A-I/A-II, C-II/C-I, C-II/C-III. E/C-III, FC/PL, SM/PL, PE/PL, and PI/PL), showing differences in sample categories with combinations of normal and high levels of Total-C and/or Total-TG. The agreement with previous studies indirectly validates the AF4-LC-MS/MS approach and demonstrates the potential of this workflow for characterization of lipoprotein composition in clinical studies using small volumes of archived frozen samples. PMID:29634782

New numerical approaches for modeling thermochemical convection in a compositionally stratified fluid

NASA Astrophysics Data System (ADS)

Puckett, Elbridge Gerry; Turcotte, Donald L.; He, Ying; Lokavarapu, Harsha; Robey, Jonathan M.; Kellogg, Louise H.

2018-03-01

Geochemical observations of mantle-derived rocks favor a nearly homogeneous upper mantle, the source of mid-ocean ridge basalts (MORB), and heterogeneous lower mantle regions. Plumes that generate ocean island basalts are thought to sample the lower mantle regions and exhibit more heterogeneity than MORB. These regions have been associated with lower mantle structures known as large low shear velocity provinces (LLSVPS) below Africa and the South Pacific. The isolation of these regions is attributed to compositional differences and density stratification that, consequently, have been the subject of computational and laboratory modeling designed to determine the parameter regime in which layering is stable and understanding how layering evolves. Mathematical models of persistent compositional interfaces in the Earth's mantle may be inherently unstable, at least in some regions of the parameter space relevant to the mantle. Computing approximations to solutions of such problems presents severe challenges, even to state-of-the-art numerical methods. Some numerical algorithms for modeling the interface between distinct compositions smear the interface at the boundary between compositions, such as methods that add numerical diffusion or 'artificial viscosity' in order to stabilize the algorithm. We present two new algorithms for maintaining high-resolution and sharp computational boundaries in computations of these types of problems: a discontinuous Galerkin method with a bound preserving limiter and a Volume-of-Fluid interface tracking algorithm. We compare these new methods with two approaches widely used for modeling the advection of two distinct thermally driven compositional fields in mantle convection computations: a high-order accurate finite element advection algorithm with entropy viscosity and a particle method that carries a scalar quantity representing the location of each compositional field. All four algorithms are implemented in the open source finite element code ASPECT, which we use to compute the velocity, pressure, and temperature associated with the underlying flow field. We compare the performance of these four algorithms on three problems, including computing an approximation to the solution of an initially compositionally stratified fluid at Ra =105 with buoyancy numbers B that vary from no stratification at B = 0 to stratified flow at large B .

Direct evidence for two-stage (bimodal) acceleration of ionospheric ions

NASA Astrophysics Data System (ADS)

Klumpar, D. M.; Peterson, W. K.; Shelley, E. G.

1984-12-01

Energetic ion composition spectrometer data gathered on hybrid conical ion distributions by the Dynamics Explorer 1 in the topside ionosphere are reported. The observed ion distributions were field-aligned and upward flowing, with energies up to 5 keV. Increases in ion energy were accompanied by a departure from field-alignment and a cone patterned upward flow, with the apex in the auroral field lines and the cone angle widening upward as the energy increased. Both transverse and parallel accelerations were imparted to the ions, with the transverse heating occurring in a 5000 km extent region centered at 18,000 km altitude. A bi-Maxwellian distribution, a temperature of 1.2 keV and a 260 eV parallel temperature were found at the top of the region.

Composite bipolar plate for electrochemical cells

DOEpatents

Wilson, Mahlon S.; Busick, Deanna N.

2001-01-01

A bipolar separator plate for fuel cells consists of a molded mixture of a vinyl ester resin and graphite powder. The plate serves as a current collector and may contain fluid flow fields for the distribution of reactant gases. The material is inexpensive, electrically conductive, lightweight, strong, corrosion resistant, easily mass produced, and relatively impermeable to hydrogen gas. The addition of certain fiber reinforcements and other additives can improve the properties of the composite material without significantly increasing its overall cost.

Characterization of a protein conjugate using an asymmetrical-flow field-flow fractionation and a size-exclusion chromatography with multi-detection system.

PubMed

Rebolj, Katja; Pahovnik, David; Zagar, Ema

2012-09-04

In this study we present detailed characterization of a protein-PEG conjugate using two separation techniques, that is, asymmetrical-flow field-flow fractionation (AF4) and size-exclusion chromatography (SEC), which were online coupled to a series of successively connected detectors: an ultraviolet, a multiangle light-scattering, a quasi-elastic light-scattering, and a refractive-index detector (UV-MALS(QELS)-RI). Matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used as a complementary characterization technique. The results of AF4 as well as SEC on two columns connected in series, with both separation techniques coupled to a multidetection system, indicate the uniform molar mass and chemical composition of the conjugate, that is, the molar ratio of protein to PEG is 1/1, the presence of minute amounts of residual unreacted protein and the aggregates with the same chemical composition as that of the conjugate. Since the portion of aggregated species is smaller in the acetate buffer solution containing 5% sorbitol than in the acetate buffer solution with 200-mM sodium chloride, the former buffer solution is more suitable for conjugate storage. The separation using only one SEC column results in poorly resolved peaks of the PEGylated protein conjugate and the aggregates, whereas MALDI-TOF MS analysis reveal the presence of the residual protein, but not the aggregates.

Tuff of Bridge Spring: A mid-Miocene ash-flow tuff, northern Colorado River extensional corridor, Nevada and Arizona

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, E.I.; Morikawa, S.A.; Martin, M.W.

1993-04-01

The Tuff of Bridge Spring (TBS) (15.19[+-]0.02 Ma; Gans, 1991) is a compositionally variable dacite to rhyolite ash-flow tuff that crops out over 1800 sq. km in the northern Colorado River extensional corridor. The TBS varies in composition from 59.5 to 74 wt. % SiO[sub 2] and typically contains phenocrysts of sanidine, plagioclase, biotite, clinopyroxene, [+-] sphene, [+-] apatite, [+-] zircon, and [+-] hornblende. The TBS is thickest and displays its greatest compositional range in the center of its area of exposure. The McCullough Range section contains at least three chemically distinct flow units that vary in composition from dacitemore » to rhyolite. The basal and uppermost units are normally zoned and the middle unit is reversely zoned. The complex chemical zonation and zoning reversals in the TBS indicate that it erupted from a magma chamber that was periodically injected by both mafic and felsic magmas. Sections at the edge of the exposure area are thin, contain only one or two chemically definable flow units and have a limited compositional range. To the west at Sheep Mountain, TBS is 2.9 m thick and ranges from 70.2--71.7 wt % SiO[sub 2]. To the east in the White Hills, TBS is 14 m thick and ranges from 59.5--65.3 wt % SiO[sub 2]. This chemical and field data indicate that although the TBS is regionally extensive, individual flow units are not. Isotopic data and chemistry suggest that all sections of the TBS are cogenetic. Comparisons of chemical, geochronological and isotopic data between the TBS and nearby coeval plutons indicate that the Aztec Wash (Eldorado Mts., Nevada) and Mt. Perkins (Black Mountain, Arizona) plutons are possible source for the TBS. Both plutons exhibit ample evidence of magma mixing and commingling, processes that may produce compositional zonation such as that observed in the TBS.« less

High rate fabrication of compression molded components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsen, Marc R.; Negley, Mark A.; Dykstra, William C.

2016-04-19

A method for fabricating a thermoplastic composite component comprises inductively heating a thermoplastic pre-form with a first induction coil by inducing current to flow in susceptor wires disposed throughout the pre-form, inductively heating smart susceptors in a molding tool to a leveling temperature with a second induction coil by applying a high-strength magnetic field having a magnetic flux that passes through surfaces of the smart susceptors, shaping the magnetic flux that passes through surfaces of the smart susceptors to flow substantially parallel to a molding surface of the smart susceptors, placing the heated pre-form between the heated smart susceptors; andmore » applying molding pressure to the pre-form to form the composite component.« less

An artificial elementary eye with optic flow detection and compositional properties.

PubMed

Pericet-Camara, Ramon; Dobrzynski, Michal K; Juston, Raphaël; Viollet, Stéphane; Leitel, Robert; Mallot, Hanspeter A; Floreano, Dario

2015-08-06

We describe a 2 mg artificial elementary eye whose structure and functionality is inspired by compound eye ommatidia. Its optical sensitivity and electronic architecture are sufficient to generate the required signals for the measurement of local optic flow vectors in multiple directions. Multiple elementary eyes can be assembled to create a compound vision system of desired shape and curvature spanning large fields of view. The system configurability is validated with the fabrication of a flexible linear array of artificial elementary eyes capable of extracting optic flow over multiple visual directions. © 2015 The Author(s).

Thermotropic nanostructured gels with complex hierarchical structure and two gelling components for water shut-off and enhance of oil recovery

NASA Astrophysics Data System (ADS)

Altunina, L. K.; Kuvshinov, I. V.; Kuvshinov, V. A.; Kozlov, V. V.; Stasyeva, L. A.

2017-12-01

This work presents the results of laboratory and field tests of thermotropic composition MEGA with two simultaneously acting gelling components, polymer and inorganic. The composition is intended for improving oil recovery and water shut-off at oilfields developed by thermal flooding, and cyclic-steam stimulated oil production wells. The composition forms an in-situ "gel-in-gel" system with improved structural-mechanical properties, using reservoir or carrier fluid heat for gelling. The gel blocks water breakthrough into producing wells and redistribute fluid flows, thus increasing the oil recovery factor.

A Study by Remote Sensing Methods of Volcanism at Craters of the Moon National Park, Idaho

NASA Astrophysics Data System (ADS)

Haberle, C. W.; Hughes, S. S.; Kobs-Nawotniak, S. E.; Lim, D. S. S.; Garry, B.; Sears, D. W. G.; Downs, M.; Busto, J.; Skok, J. R.; Elphic, R. C.; Kobayashi, L.; Heldmann, J. L.; Christensen, P. R.

2014-12-01

Craters of the Moon (COTM) National Park, on the eastern Snake River Plain, and its associated lava fields are currently a focus of the NASA SSERVI FINESSE (Field Investigations to Enable Solar System Science and Exploration) team. COTM was selected for study owing to similarities with volcanic features observed on the Moon, Mars and Vesta. The COTM basaltic lava fields emanate from an 80 km long rift zone where at least eight eruptive episodes, occurring 15,000 to 2,000 BP, have created an expansive volcanic field covering an area of approximately 1,650 km2. This polygenetic volcanic field hosts a diverse collection of basaltic volcanic edifices such as phreatic explosion craters, eruptive fissures, cinder cones, spatter cones, shield volcanoes and expansive lava flows. Engineering challenges and high cost limit the number of robotic and human field investigations of planetary bodies and, due to these constraints, exhaustive remote sensing investigations of planetary surface properties are undertaken prior to field deployment. This creates an unavoidable dependence upon remote sensing, a critical difference between field investigations of planetary bodies and most terrestrial field investigations. Studies of this nature have utility in terrestrial investigations as they can help link spatially encompassing datasets and conserve field resources. We present preliminary results utilizing Earth orbital datasets to determine the efficacy of products derived from remotely sensed data when compared to geologic field observations. Multispectral imaging data (ASTER, AVIRIS, TIMS) collected at a range of spatial and spectral resolutions are paired with high resolution imagery from both orbit and unmanned aircraft systems. This enables the creation of derived products detailing morphology, compositional variation, mineralogy, relative age and vegetation. The surface morphology of flows within COTM differs from flow to flow and observations of these properties can aid in determining the driving mechanisms. The entirety of the COTM volcanic field is the target of this investigation although areas of interest have been selected for more focused investigation to support planned and ongoing field investigations at Highway A'a flow, North Crater cinder cone and King's Bowl phreatic explosion crater and flow.

Pliocene and Pleistocene alkalic flood basalts on the seafloor north of the Hawaiian islands

USGS Publications Warehouse

Clague, D.A.; Holcomb, R.T.; Sinton, J.M.; Detrick, R. S.; Torresan, M.E.

1990-01-01

The North Arch volcanic field is located north of Oahu on the Hawaiian Arch, a 200-m high flexural arch formed by loading of the Hawaiian Islands. These flood basalt flows cover an area of about 25,000 km2; the nearly flat-lying sheet-like flows extend about 100 km both north and south from the axis of the flexural arch. Samples from 26 locations in the volcanic field range in composition from nephelinite to alkalic basalt. Ages estimated from stratigraphy, thickness of sediment on top of the flows, and thickness of palagonite alteration rinds on the recovered lavas, range from about 0.75-0.9 Ma for the youngest lavas to somewhat older than 2.7 Ma for the oldest lavas. Most of the flow field consists of extensive sheetflows of dense basanite and alkalic basalt. Small hills consisting of pillow basalt and hyaloclastite of mainly nephelinite and alkalic basalt occur within the flow field but were not the source vents for the extensive flows. Many of the vent lavas are highly vesicular, apparently because of degassing of CO2. The lavas are geochemically similar to the rejuvenated-stage lavas of the Koloa and Honolulu Volcanics and were generated by partial melting of sources similar to those of the Koloa Volcanics. Prior to eruption, these magmas may have accumulated at or near the base of the lithosphere in a structural trap created by upbowing of the lithosphere. ?? 1990.

Late Pleistocene ages for the most recent volcanism and glacial-pluvial deposits at Big Pine volcanic field, California, USA, from cosmogenic 36Cl dating

USGS Publications Warehouse

Vazquez, Jorge A.; Woolford, Jeff M

2015-01-01

The Big Pine volcanic field is one of several Quaternary volcanic fields that poses a potential volcanic hazard along the tectonically active Owens Valley of east-central California, and whose lavas are interbedded with deposits from Pleistocene glaciations in the Sierra Nevada Range. Previous geochronology indicates an ∼1.2 Ma history of volcanism, but the eruption ages and distribution of volcanic products associated with the most-recent eruptions have been poorly resolved. To delimit the timing and products of the youngest volcanism, we combine field mapping and cosmogenic 36Cl dating of basaltic lava flows in the area where lavas with youthful morphology and well-preserved flow structures are concentrated. Field mapping and petrology reveal approximately 15 vents and 6 principal flow units with variable geochemical composition and mineralogy. Cosmogenic 36Cl exposure ages for lava flow units from the top, middle, and bottom of the volcanic stratigraphy indicate eruptions at ∼17, 27, and 40 ka, revealing several different and previously unrecognized episodes of late Pleistocene volcanism. Olivine to plagioclase-pyroxene phyric basalt erupted from several vents during the most recent episode of volcanism at ∼17 ka, and produced a lava flow field covering ∼35 km2. The late Pleistocene 36Cl exposure ages indicate that moraine and pluvial shoreline deposits that overlie or modify the youngest Big Pine lavas reflect Tioga stage glaciation in the Sierra Nevada and the shore of paleo-Owens Lake during the last glacial cycle.

Metal-dielectric composites for beam splitting and far-field deep sub-wavelength resolution for visible wavelengths.

PubMed

Yan, Changchun; Zhang, Dao Hua; Zhang, Yuan; Li, Dongdong; Fiddy, M A

2010-07-05

We report beam splitting in a metamaterial composed of a silver-alumina composite covered by a layer of chromium containing one slit. By simulating distributions of energy flow in the metamaterial for H-polarized waves, we find that the beam splitting occurs when the width of the slit is shorter than the wavelength, which is conducive to making a beam splitter in sub-wavelength photonic devices. We also find that the metamaterial possesses deep sub-wavelength resolution capabilities in the far field when there are two slits and the central silver layer is at least 36 nm in thickness, which has potential applications in superresolution imaging.

Biological and physical conditions of macroinvertebrates in reference lowland streams

NASA Astrophysics Data System (ADS)

de Brouwer, Jan; Eekhout, Joris; Verdonschot, Piet

2016-04-01

Channelisation measures taken halfway the 20th century have had destructive consequences for the diversity of the ecology in the majority of the lowland streams in countries such as the Netherlands. Currently, stream restoration measures are being implemented in these degraded lowland streams, where design principles are often based on outdated relationships between biological and physical conditions. Little is known about the reference conditions in these streams. Therefore, the aim of this research is to quantify the relationships between biological and physical conditions of macroinvertebrates in reference lowland streams. The research was conducted in four near-natural lowland streams in Central Poland. Field data were obtained during a field campaign in 2011. The following data were obtained in a 50-m reach in each of the four streams: macroinvertebrate sampling, spatial habitat patterns, bathymetry, and flow-velocity. Furthermore, water level, light sensitivity and temperature sensors were installed to obtain the temporal dynamic of these streams. Macroinvertebrates were sampled in 9 different habitat types, i.e. sand, gravel, fine organic matter, stones, branches, leaves, silt, vegetation, and wood. Macroinvertebrates were determined to the highest taxonomic level possible. Data from the bathymetrical surveys were interpolated on a grid and bathymetrical metrics were determined. Flow velocity measurements were related to habitats and flow velocity metrics were determined. Analysis of the data shows that flow conditions vary among the different habitat, with a gradient from hard substrates towards soft substrates. Furthermore, the data show that stream as a unit best explains species composition, but also specific habitat conditions, such as substrate type and flow velocity, correlate with species composition. More specific, the data shows a strong effect of wood on species composition. These findings may have implications for stream restoration design, which mainly focus on large-scale reconstruction of channel planform, whereas this study shows that improvement of stream ecology should focus on the smaller habitat scale.

The influence of tree stands and a noise barrier on near-roadway air quality

EPA Science Inventory

Prediction of air pollution exposure levels of people living near or commuting on roadways is still very problematic due to the highly localized nature of traffic intensity, fleet composition, and extremely complex air flow patterns in urban areas. Both modelling and field studie...

Discovery of meteorites on a blue-ice field near the Frontier Mountains, North Victoria Land, Antarctica

NASA Technical Reports Server (NTRS)

Delisle, G.; Hoefle, H. C.; Thierbach, R.; Schultz, L.

1986-01-01

A high concentration of meteorites were discovered on a blue ice field northeast of the Frontier Mountains. As a result of a systematic search, a total of 42 meteorites were recovered. The current glacial situation has evolved through various stages, which are discussed in relationship to the concentration of meteorites. Ice flow patterns are summarized. The chemical composition and terrestrial ages of the meteorites are discussed.

Direct evidence for magnetic reconnection in the solar wind near 1 AU

NASA Astrophysics Data System (ADS)

Gosling, J. T.; Skoug, R. M.; McComas, D. J.; Smith, C. W.

2005-01-01

We have obtained direct evidence for local magnetic reconnection in the solar wind using solar wind plasma and magnetic field data obtained by the Advanced Composition Explorer (ACE). The prime evidence consists of accelerated ion flow observed within magnetic field reversal regions in the solar wind. Here we report such observations obtained in the interior of an interplanetary coronal mass ejection (ICME) or at the interface between two ICMEs on 23 November 1997 at a time when the magnetic field was stronger than usual. The observed plasma acceleration was consistent with the Walen relationship, which relates changes in flow velocity to density-weighted changes in the magnetic field vector. Pairs of proton beams having comparable densities and counterstreaming relative to one another along the magnetic field at a speed of ˜1.4VA, where VA was the local Alfven speed, were observed near the center of the accelerated flow event. We infer from the observations that quasi-stationary reconnection occurred sunward of the spacecraft and that the accelerated flow occurred within a Petschek-type reconnection exhaust region bounded by Alfven waves and having a cross section width of ˜4 × 105 km as it swept over ACE. The counterstreaming ion beams resulted from solar wind plasma entering the exhaust region from opposite directions along the reconnected magnetic field lines. We have identified a limited number (five) of other accelerated flow events in the ACE data that are remarkably similar to the 23 November 1997 event. All such events identified occurred at thin current sheets associated with moderate to large changes in magnetic field orientation (98°-162°) in plasmas characterized by low proton beta (0.01-0.15) and high Alfven speed (51-204 km/s). They also were all associated with ICMEs.

Trapping and dynamic manipulation of polystyrene beads mimicking circulating tumor cells using targeted magnetic/photoacoustic contrast agents

NASA Astrophysics Data System (ADS)

Wei, Chen-Wei; Xia, Jinjun; Pelivanov, Ivan; Hu, Xiaoge; Gao, Xiaohu; O'Donnell, Matthew

2012-10-01

Results on magnetically trapping and manipulating micro-scale beads circulating in a flow field mimicking metastatic cancer cells in human peripheral vessels are presented. Composite contrast agents combining magneto-sensitive nanospheres and highly optical absorptive gold nanorods were conjugated to micro-scale polystyrene beads. To efficiently trap the targeted objects in a fast stream, a dual magnet system consisting of two flat magnets to magnetize (polarize) the contrast agent and an array of cone magnets producing a sharp gradient field to trap the magnetized contrast agent was designed and constructed. A water-ink solution with an optical absorption coefficient of 10 cm-1 was used to mimic the optical absorption of blood. Magnetomotive photoacoustic imaging helped visualize bead trapping, dynamic manipulation of trapped beads in a flow field, and the subtraction of stationary background signals insensitive to the magnetic field. The results show that trafficking micro-scale objects can be effectively trapped in a stream with a flow rate up to 12 ml/min and the background can be significantly (greater than 15 dB) suppressed. It makes the proposed method very promising for sensitive detection of rare circulating tumor cells within high flow vessels with a highly absorptive optical background.

Microbial community stratification controlled by the subseafloor fluid flow and geothermal gradient at the Iheya North hydrothermal field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331).

PubMed

Yanagawa, Katsunori; Breuker, Anja; Schippers, Axel; Nishizawa, Manabu; Ijiri, Akira; Hirai, Miho; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2014-10-01

The impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of the Chloroflexi and deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group I Thaumarchaeota dominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Microbial Community Stratification Controlled by the Subseafloor Fluid Flow and Geothermal Gradient at the Iheya North Hydrothermal Field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331)

PubMed Central

Breuker, Anja; Schippers, Axel; Nishizawa, Manabu; Ijiri, Akira; Hirai, Miho; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2014-01-01

The impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of the Chloroflexi and deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group I Thaumarchaeota dominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments. PMID:25063666

Stratigraphy, composition and form of the Deccan Basalts, Western Ghats, India

NASA Astrophysics Data System (ADS)

Beane, J. E.; Turner, C. A.; Hooper, P. R.; Subbarao, K. V.; Walsh, J. N.

1986-02-01

In the Western Ghats between latitudes 18° 20' N and 19° 15' N, 7000 km2 of Deccan Basalt have been mapped with the primary objective of establishing a flow stratigraphy as a guide to the volcanic history of the flood basalts. Using over 70 measured vertical sections, major and trace element analyses of nearly 1200 samples, and rare-earth and87Sr/86Sr determinations for over 60 samples, we divide the basalt into three subgroups and ten formations. In this paper we describe the seven principal formations in the area and the most prominent individual flows. The Kalsubai Subgroup is formed by the lower five formations, the Jawhar, Igatpuri, Neral, Thakurvadi, and Bhimashankar formations, from botton to top. In these formations amygdaloidal compound flows predominate and have a typically high MgO content, including picrite basalt (> 10% MgO) and picrite (> 18% MgO) with phenocrysts of olivine and clinopyroxene. These flows are separated by others which contain giant plagioclase phenocrysts and have more evolved chamical compositions. The Lonavala Subgroup overlies the Kalsubai and is composed of two formations, the Khandala and the Bushe. Both are readily recognized in the field and by their chemical compositions. The Wai Subgroup includes the upper three formations, the Poladpur, the Ambenali, and the Mahabaleshwar. The whole subgroup is composed of simple flows with well-developed flow tops, small phenocrysts of plagioclase, pyroxene and olivine, and relatively evolved bulk compositions. Distribution and variation in thickness of the straitigraphic units within the Western Ghats provide a first comprehensive view of the development of the Deccan volcanic edifice. The persistent southerly dip and gentle southerly plunging anticlinal form of the flows, the lensoid shape of many of the formations, and nearly randomly oriented feeder-dike system are together interpreted as evidence of a central volcanic edifice formed as the Indian plate drifted northward over a mantle plume or hot spot.

Characterization of charged polymer self-assemblies by multidetector thermal field-flow fractionation in aqueous mobile phases.

PubMed

Greyling, Guilaume; Pasch, Harald

2018-01-12

Charged block copolymer self-assemblies, such as charged micelles, have attracted much attention as versatile drug delivery systems due to their readily tunable characteristics such as size and surface charge. However, current column-based analytical techniques are not suitable to fractionate and comprehensively characterize charged micelles in terms of size, molar mass, chemical composition and morphology. Multidetector thermal field-flow fractionation (ThFFF) is shown to be a unique characterization platform that can be used to characterize charged micelles in terms of size, molar mass, chemical composition and morphology in aqueous mobile phases with various ionic strengths and pH. This is demonstrated by the characterization of poly(methacrylic acid)-b-poly(methyl methacrylate) self-assemblies in high pH buffers as well as the characterization of cationic poly(2-vinyl pyridine)-b-polystyrene and poly(4-vinyl pyridine)-b-polystyrene self-assemblies in low pH buffers. Moreover, it is shown that ThFFF is capable of separating charged micelles according to the corona composition. These investigations prove convincingly that ThFFF is broadly applicable to the comprehensive characterization of amphiphilic self-assemblies even when aqueous mobile phases are used. Copyright © 2017 Elsevier B.V. All rights reserved.

Eruption rate, area, and length relationships for some Hawaiian lava flows

NASA Technical Reports Server (NTRS)

Pieri, David C.; Baloga, Stephen M.

1986-01-01

The relationships between the morphological parameters of lava flows and the process parameters of lava composition, eruption rate, and eruption temperature were investigated using literature data on Hawaiian lava flows. Two simple models for lava flow heat loss by Stefan-Boltzmann radiation were employed to derive eruption rate versus planimetric area relationship. For the Hawaiian basaltic flows, the eruption rate is highly correlated with the planimetric area. Moreover, this observed correlation is superior to those from other obvious combinations of eruption rate and flow dimensions. The correlations obtained on the basis of the two theoretical models, suggest that the surface of the Hawaiian flows radiates at an effective temperature much less than the inner parts of the flowing lava, which is in agreement with field observations. The data also indicate that the eruption rate versus planimetric area correlations can be markedly degraded when data from different vents, volcanoes, and epochs are combined.

The Puelche volcanic field: Extensive Pleistocene rhyolite lava flows in the Andes of central Chile

USGS Publications Warehouse

Hildreth, W.; Fierstein, J.; Godoy, E.; Drake, Robert E.; Singer, B.

1999-01-01

A remote volcanic field in the rugged headwaters of the Rio Puelche and Rio Invernada (35.8??S) constitutes the largest cluster of Quaternary rhyolite lava flows yet identified in the Andean Southern Volcanic Zone. The Puelche Volcanic Field belongs to an intra-arc belt of silicic magmatic centers that extends, at least, 140 km north-south and lies well east of the volcanic front but nonetheless considerably west of the intraplate extensional fields of basaltic and alkaline centers of pampean Argentina. The authors' mapping has distinguished one shallow intrusive mass of early Pleistocene biotite rhyodacite (70.5% SiO2), 11 eruptive units of mid-Pleistocene high-K biotite-rhyolite lava (71.3-75.6% SiO2), and 4 eruptive units of basaltic andesite (53.95-4.9% SiO2), the conduits of which cut some of the rhyolites. Basal contacts of the rhyolite lava flows (and subjacent pyroclastic precursors) are generally scree covered, but glacial erosion has exposed internal flow structures and lithologic zonation superbly. Thicknesses of individual rhyolite lava flows range from 75 m to 400 m. Feeders for several units are well exposed. Cliff-draping unconformities and intracanyon relationships among the 11 rhyolite units show that the eruptive sequence spanned at least one glacial episode that accentuated the local relief. Lack of ice-contact features suggests, however, that all or most eruptions took place during non-glacial intervals probably between 400 ka and 100 ka. Post-eruptive glacial erosion reduced the rhyolites to several non-contiguous remnants that altogether cover 83 km2 and represent a surviving volume of about 21 km3. Consideration of slopes, lava thicknesses, and paleotopography suggest that the original area and volume were each about three times greater. Phenocryst content of the rhyolites ranges from 1 to 12%, with plagioclase>>biotite>FeTi oxides in all units and amphibole conspicuous in the least silicic. The chemically varied basaltic andesites range from phenocryst-poor to phenocryst-rich, exhibiting large differences in proportions of clinopyroxene, olivine, plagioclase, and xenocrystic quartz. Compositional bimodality of the volcanic field is striking, there being no Quaternary eruptive units having SiO2 contents between 55 and 70%. Major and trace element compositions of the mafic and silicic rocks are nonetheless typical of continental-margin arc suites, not of intracontinental suites. The lack of intermediate eruptive units and the differences between the mafic and rhyolitic lavas in Sr-isotope composition suggest that the rhyolites fractionated from a hybrid parent rather than continuously from basaltic magma. The rhyolites may contain larger contributions of upper-crustal partial melts than do silicic products of the volcanic-front centers 30 km to the west.

Biofilm development in a hotspot of mixing between shallow and deep groundwater in a fractured aquifer: field evidence from joint flow, chemical and microbiological characterization

NASA Astrophysics Data System (ADS)

Bochet, Olivier; Le Borgne, Tanguy; Pédrot, Mathieu; Labasque, Thierry; Lavenant, Nicolas; Petton, Christophe; Dufresne, Alexis; Ben Maamar, Sarah; Chatton, Eliot; De la Bernardie, Jérôme; Aquilina, Luc

2015-04-01

Biofilm development in a hotspot of mixing between shallow and deep groundwater in a fractured aquifer: field evidence from joint flow, chemical and microbiological characterization Olivier Bochet1, Tanguy Le Borgne1, Mathieu Pédrot1, Thierry Labasque1, Nicolas Lavenant1, Christophe Petton1, Alexis Dufresne2,Sarah Ben Maamar1-2, Eliot Chatton1, Jérôme de la Bernardie1, Luc Aquilina1 1: Géosciences Rennes, CNRS UMR 6118, Université de Rennes 1, Campus de Beaulieu bât 14B, Rennes, France 2: Ecobio, CNRS UMR 6553, Université de Rennes 1, Campus de Beaulieu, bât 14, Rennes, France Biofilms play a major role in controlling the fluxes and reactivity of chemical species transported in hydrological systems. Their development can have either positive impacts on groundwater quality (e.g. attenuation of contaminants under natural or stimulated conditions), or possible negative effects on subsurface operations (e.g. bio-clogging of geothermal dipoles or artificial recharge systems). Micro-organisms require both electron donors and electron acceptors for cellular growth, proliferation and maintenance of their metabolic functions. The mechanisms controlling these reactions derive from the interactions occurring at the micro-scale that depend on mineral compositions, the biota of subsurface environment, but also fluid mixing, which determines the local concentrations of nutriments, electron donors and electron acceptors. Hence, mixing zones between oxygen and nutriment rich shallow groundwater and mineralized deep groundwater are often considered as potential hotspots of microbial activity, although relatively few field data document flow distributions, transport properties, chemical gradients and micro-organisms distributions across these mixing interfaces. Here we investigate the origin of a localized biofilm development observed in the fractured granite aquifer at the Ploemeur observatory (H+ network hplus.ore.fr).This biofilm composed of ferro-oxidizing bacteria is observed in an 130m deep artesian well. Borehole video logs show an important colonization of the well by the biofilm in the shallower part (0 to 60m), while it is inexistent in the deeper part (60 to 130m). As flow is localized in a few deep and shallow fractures, we presume that the spatial distribution of biofilm is controlled by mixing between shallow and deep groundwater. To verify this hypothesis we conducted a field campaign with joint characterization of the flow and chemical composition of water flowing from the different fractures, as well as the microbiological composition of the biofilm at different depth, using pyrosequencing techniques. We will discuss in this presentation the results of this interdisciplinary dataset and their implications for the occurrence of hotspots of microbiological activity in the subsurface.

Aeromagnetic and Gravity Maps of the Central Marysvale Volcanic Field, Southwestern Utah

USGS Publications Warehouse

Campbell, David L.; Steven, Thomas A.; Cunningham, Charles G.; Rowley, Peter D.

1999-01-01

Gravity and aeromagnetic features in the Marysvale volcanic field result from the composite effects of many factors, including rock composition, style of magmatic emplacement, type and intensity of rock alteration, and effects of structural evolution. Densities and magnetic properties measured on a suite of rock samples from the Marysvale volcanic field differ in systematic ways. Generally, the measured densities, magnetic susceptibilities, and natural remanent magnetizations all increase with mafic index, but decrease with degree of alteration, and for tuffs, with degree of welding. Koenigsberger Q indices show no such systematic trends. The study area is divided into three geophysical domains. The northern domain is dominated by aeromagnetic lows that probably reflect reversed-polarity volcanic flows. There are no intermediate-sized magnetic highs in the northern domain that might reflect plutons. The northern domain has a decreasing-to-the-south gravity gradient that reflects the Pavant Range homocline. The central domain has gravity lows that reflect altered rocks in calderas and low-density plutons of the Marysvale volcanic field. Its aeromagnetic signatures consist of rounded highs that reflect plutons and birdseye patterns that reflect volcanic flows. In many places the birdseyes are attenuated, indicating that the flows there have been hydrothermally altered. We interpret the central domain to reflect an east-trending locus of plutons in the Marysvale volcanic field. The southern domain has intermediate gravity fields, indicating somewhat denser rocks there than in the central domain, and high-amplitude aeromagnetic birdseyes that reflect unaltered volcanic units. The southern domain contains no magnetic signatures that we interpret to reflect plutons. Basin-and-range tectonism has overprinted additional gravity features on the three domains. A deep gravity low follows the Sevier and Marysvale Valleys, reflecting grabens there. The gravity gradient in the north reflects the southern flank of a structural dome that led to the Pavant Range homocline and whose southern edge lies along the Clear Creek downwarp.

A composite numerical model for assessing subsurface transport of oily wastes and chemical constituents

NASA Astrophysics Data System (ADS)

Panday, S.; Wu, Y. S.; Huyakorn, P. S.; Wade, S. C.; Saleem, Z. A.

1997-02-01

Subsurface fate and transport models are utilized to predict concentrations of chemicals leaching from wastes into downgradient receptor wells. The contaminant concentrations in groundwater provide a measure of the risk to human health and the environment. The level of potential risk is currently used by the U.S. Environmental Protection Agency to determine whether management of the wastes should conform to hazardous waste management standards. It is important that the transport and fate of contaminants is simulated realistically. Most models in common use are inappropriate for simulating the migration of wastes containing significant fractions of nonaqueous-phase liquids (NAPLs). The migration of NAPL and its dissolved constituents may not be reliably predicted using conventional aqueous-phase transport simulations. To overcome this deficiency, an efficient and robust regulatory assessment model incorporating multiphase flow and transport in the unsaturated and saturated zones of the subsurface environment has been developed. The proposed composite model takes into account all of the major transport processes including infiltration and ambient flow of NAPL, entrapment of residual NAPL, adsorption, volatilization, degradation, dissolution of chemical constituents, and transport by advection and hydrodynamic dispersion. Conceptually, the subsurface is treated as a composite unsaturated zone-saturated zone system. The composite simulator consists of three major interconnected computational modules representing the following components of the migration pathway: (1) vertical multiphase flow and transport in the unsaturated zone; (2) areal movement of the free-product lens in the saturated zone with vertical equilibrium; and (3) three-dimensional aqueous-phase transport of dissolved chemicals in ambient groundwater. Such a composite model configuration promotes computational efficiency and robustness (desirable for regulatory assessment applications). Two examples are presented to demonstrate the model verification and a site application. Simulation results obtained using the composite modeling approach are compared with a rigorous numerical solution and field observations of crude oil saturations and plume concentrations of total dissolved organic carbon at a spill site in Minnesota, U.S.A. These comparisons demonstrate the ability of the present model to provide realistic depiction of field-scale situations.

Magnetophoretic manipulation in microsystem using carbonyl iron-polydimethylsiloxane microstructures

PubMed Central

Faivre, Magalie; Gelszinnis, Renaud; Degouttes, Jérôme; Terrier, Nicolas; Rivière, Charlotte; Ferrigno, Rosaria; Deman, Anne-Laure

2014-01-01

This paper reports the use of a recent composite material, noted hereafter i-PDMS, made of carbonyl iron microparticles mixed in a PolyDiMethylSiloxane (PDMS) matrix, for magnetophoretic functions such as capture and separation of magnetic species. We demonstrated that this composite which combine the advantages of both components, can locally generate high gradients of magnetic field when placed between two permanent magnets. After evaluating the magnetic susceptibility of the material as a function of the doping ratio, we investigated the molding resolution offered by i-PDMS to obtain microstructures of various sizes and shapes. Then, we implemented 500 μm i-PDMS microstructures in a microfluidic channel and studied the influence of flow rate on the deviation and trapping of superparamagnetic beads flowing at the neighborhood of the composite material. We characterized the attraction of the magnetic composite by measuring the distance from the i-PDMS microstructure, at which the beads are either deviated or captured. Finally, we demonstrated the interest of i-PDMS to perform magnetophoretic functions in microsystems for biological applications by performing capture of magnetically labeled cells. PMID:25332740

Numerical prediction of flow induced fibers orientation in injection molded polymer composites

NASA Astrophysics Data System (ADS)

Oumer, A. N.; Hamidi, N. M.; Mat Sahat, I.

2015-12-01

Since the filling stage of injection molding process has important effect on the determination of the orientation state of the fibers, accurate analysis of the flow field for the mold filling stage becomes a necessity. The aim of the paper is to characterize the flow induced orientation state of short fibers in injection molding cavities. A dog-bone shaped model is considered for the simulation and experiment. The numerical model for determination of the fibers orientation during mold-filling stage of injection molding process was solved using Computational Fluid Dynamics (CFD) software called MoldFlow. Both the simulation and experimental results showed that two different regions (or three layers of orientation structures) across the thickness of the specimen could be found: a shell region which is near to the mold cavity wall, and a core region at the middle of the cross section. The simulation results support the experimental observations that for thin plates the probability of fiber alignment to the flow direction near the mold cavity walls is high but low at the core region. It is apparent that the results of this study could assist in decisions regarding short fiber reinforced polymer composites.

The Taylor Creek Rhyolite of New Mexico: a rapidly emplaced field of lava domes and flows

USGS Publications Warehouse

Duffield, W.A.; Dalrymple, G.B.

1990-01-01

The Tertiary Taylor Creek Rhyolite of southwest New Mexico comprises at least 20 lava domes and flows. Each of the lavas was erupted from its own vent, and the vents are distributed throughout a 20 km by 50 km area. The volume of the rhyolite and genetically associated pyroclastic deposits is at least 100 km3 (denserock equivalent). The rhyolite contains 15%-35% quartz, sanidine, plagioclase, ??biotite, ??hornblende phenocrysts. Quartz and sanidine account for about 98% of the phenocrysts and are present in roughly equal amounts. With rare exceptions, the groundmass consists of intergrowths of fine-grained silica and alkali feldspar. Whole-rock major-element composition varies little, and the rhyolite is metaluminous to weakly peraluminous; mean SiO2 content is about 77.5??0.3%. Similarly, major-element compositions of the two feldsparphenocryst species also are nearly constant. However, whole-rock concentrations of some trace-elements vary as much as several hundred percent. Initial radiometric age determinations, all K-Ar and fission track, suggest that the rhyolite lava field grew during a period of at least 2 m.y. Subsequent 40Ar/39Ar ages indicate that the period of growth was no more than 100 000 years. The time-space-composition relations thus suggest that the Taylor Creek Rhyolite was erupted from a single magma reservoir whose average width was at least 30 km, comparable in size to several penecontemporaneous nearby calderas. However, this rhyolite apparently is not related to a caldera structure. Possibly, the Taylor Creek Phyolite magma body never became sufficiently volatile rich to produce a large-volume pyroclastic eruption and associated caldera collapse, but instead leaked repeatedly to feed many relatively small domes and flows. The new 40Ar/39Ar ages do not resolve preexisting unknown relative-age relations among the domes and flows of the lava field. Nonetheless, the indicated geologically brief period during which Taylor Creek Rhyolite magma was erupted imposes useful constraints for future evaluation of possible models for petrogenesis and the origin of trace-element characteristics of the system. ?? 1990 Springer-Verlag.

Field and experimental constraints on the rheology of arc basaltic lavas: the January 2014 Eruption of Pacaya (Guatemala)

NASA Astrophysics Data System (ADS)

Soldati, A.; Sehlke, A.; Chigna, G.; Whittington, A.

2016-06-01

We estimated the rheology of an active basaltic lava flow in the field, and compared it with experimental measurements carried out in the laboratory. In the field we mapped, sampled, and recorded videos of the 2014 flow on the southern flank of Pacaya, Guatemala. Velocimetry data extracted from videos allowed us to determine that lava traveled at ˜2.8 m/s on the steep ˜45° slope 50 m from the vent, while 550 m further downflow it was moving at only ˜0.3 m/s on a ˜4° slope. Estimates of effective viscosity based on Jeffreys' equation increased from ˜7600 Pa s near the vent to ˜28,000 Pa s downflow. In the laboratory, we measured the viscosity of a representative lava composition using a concentric cylinder viscometer, at five different temperatures between 1234 and 1199 °C, with crystallinity increasing from 0.1 to 40 vol%. The rheological data were best fit by power law equations, with the flow index decreasing as crystal fraction increased, and no detectable yield strength. Although field-based estimates are based on lava characterized by a lower temperature, higher crystal and bubble fraction, and with a more complex petrographic texture, field estimates and laboratory measurements are mutually consistent and both indicate shear-thinning behavior. The complementary field and laboratory data sets allowed us to isolate the effects of different factors in determining the rheological evolution of the 2014 Pacaya flows. We assess the contributions of cooling, crystallization, and changing ground slope to the 3.7-fold increase in effective viscosity observed in the field over 550 m, and conclude that decreasing slope is the single most important factor over that distance. It follows that the complex relations between slope, flow velocity, and non-Newtonian lava rheology need to be incorporated into models of lava flow emplacement.

The new grasper-integrated single use flexible cystoscope for double J stent removal: evaluation of image quality, flow and flexibility.

PubMed

Talso, M; Emiliani, E; Baghdadi, M; Orosa, A; Servian, P; Barreiro, A; Proietti, S; Traxer, O

2017-08-01

A new single use digital flexible cystoscope (FC) Isiris α from Coloplast ® with an incorporated grasper has been developed to perform double J stent removal. There is a lack of data regarding the comparison of image quality, flexibility and flow between classic cystoscopes and the new Isiris α. Five different FC were used to compare the image quality, the field of view, the loss of flow and the deflection loss. Two standardized grids, three stones of different composition and a ruler's image were filmed in four standardized different scenarios. These videos were shown to thirty subjects that had to evaluate them. Water outflow was measured in ml/sec in all devices with and without the grasper inside, instruments tip deflection was measured using a software. In the subjective analysis of the image quality Isiris α was the second FC best scored. At 3 cm of distance, the field view of Isiris α was the narrowest. Comparing the water flow in the different FCs, we observed a water flow decrease in all cystoscopes when the grasper was loaded in the working channel. Isiris α deflection and flow increase when the grasper is activated. In terms of quality of vision and water flow, the FC Isiris α is comparable to the other digital FC tested. Field of view is narrower. The results displayed a valid alternative to the standard procedure for DJ removal.

Microgravity

NASA Image and Video Library

1995-10-10

This composite image depicts one set of flow patterns simulated in the Geophysical Fluid Flow Cell (GFFC) that flew on two Spacelab missions. Silicone oil served as the atmosphere around a rotating steel hemisphere (dotted circle) and an electrostatic field pulled the oil inward to mimic gravity's effects during the experiments. The GFFC thus produced flow patterns that simulated conditions inside the atmospheres of Jupiter and the Sun and other stars. GFFC flew on Spacelab-3 in 1985 and U.S. Microgravity Laboratory-2 in 1995. The principal investigator was John Hart of the University of Colorado at Boulder. It was managed by NASA's Marshall Space Flight Center. (Credit: NASA/Marshall Space Flight Center)

Sources and drains: Major controls of hydrothermal fluid flow in the Kokanee Range, British Columbia, Canada

NASA Astrophysics Data System (ADS)

Beaudoin, Georges; Therrien, René

1999-10-01

Vein fields are fractured domains of the lithosphere that have been infiltrated by hydrothermal fluids, which deposited minerals in response to changing physico-chemical conditions. Because oxygen is a major component of the infiltrating fluid and the surrounding rock matrix, the oxygen isotope composition of minerals found in veins is used to decipher ancient fluid flow within the lithosphere. We use a numerical model to simulate oxygen isotope transport in the Kokanee Range silver-lead-zinc vein field. The model considers advective, dispersive, and reactive transport in a three-dimensional porous rock matrix intersected by high-permeability planes representing fracture zones. Here we show that it is the geometrical configuration of the sources and of the drains of hydrothermal fluids, combined with the fracture pattern, that exerts the main control on the oxygen isotope distribution. Other factors that affect, to a lesser extent, the values and positions of oxygen isopleths are the fluids and rock-matrix isotopic compositions, the isotopic fractionation, the reaction rate constant, and hydraulic conductivities of the rock matrix and fracture zones.

Rapid, high-temperature, field test method for evaluation of geothermal calcium carbonate scale inhibitors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asperger, R.G.

1986-09-01

A new test method is described that allows the rapid field testing of calcium carbonate scale inhibitors at 500/sup 0/F (260/sup 0/C). The method evolved from use of a full-flow test loop on a well with a mass flow rate of about 1 x 10/sup 6/ lbm/hr (126 kg/s). It is a simple, effective way to evaluate the effectiveness of inhibitors under field conditions. Five commercial formulations were chosen for field evaluation on the basis of nonflowing, laboratory screening tests at 500/sup 0/F (260/sup 0/C). Four of these formulations from different suppliers controlled calcium carbonate scale deposition as measured bymore » the test method. Two of these could dislodge recently deposited scale that had not age-hardened. Performance-profile diagrams, which were measured for these four effective inhibitors, show the concentration interrelationship between brine calcium and inhibitor concentrations at which the formulations will and will not stop scale formation in the test apparatus. With these diagrams, one formulation was chosen for testing on the full-flow brine line. The composition was tested for 6 weeks and showed a dramatic decrease in the scaling occurring at the flow-control valve. This scaling was about to force a shutdown of a major, long-term flow test being done for reservoir economic evaluations. The inhibitor stopped the scaling, and the test was performed without interruption.« less

Compositional variation of lavas from a young volcanic field on the Southern Mid-Atlantic Ridge, 8°48'S

NASA Astrophysics Data System (ADS)

Haase, K.; Brandl, P. A.; Melchert, B.; Hauff, F.; Garbe-Schoenberg, C.; Paulick, H.; Kokfelt, T. F.; Devey, C. W.

2012-12-01

Volcanic eruptions along the mid-oceanic ridge system are the most abundant signs of volcanic activity on Earth but little is known about the timescales and nature of these processes. The main parameter determining eruption frequency as well as magma composition appears to be the spreading rate of the mid-oceanic ridge. However, few observations on the scale of single lava flows exist from the slow-spreading Mid-Atlantic Ridge so far. Here we present geological observations and geochemical data for the youngest volcanic features of the so-called A2 segment (Bruguier et al., 2003, Hoernle et al., 2011) of the slow-spreading (33 mm/yr) southern Mid-Atlantic Ridge at 8°48'S. This segment has a thickened crust of about 9 km indicating increased melt production in the mantle. Side-scan sonar mapping revealed a young volcanic field with high reflectivity that was probably erupted from two volcanic fissures each of about 3 km length. Small-scale sampling of the young lava field at 8°48'S by ROV and wax corer and geochemical analyses of the volcanic glasses reveal three different compositional lava units along this about 11 km long portion of the ridge. Based on the incompatible element compositions of volcanic glasses (e.g. K/Ti, Ce/Yb) we can distinguish two lava units forming the northern and the larger southern part of the lava field covering areas of about 5 and 9 square kilometres, respectively. Basalts surrounding the lava field and from an apparently old pillow mound within the young flows are more depleted in incompatible elements than glasses from the young volcanic field. Radium disequilibria suggest that most lavas from this volcanic field have ages of 3000 to 5000 yrs whereas the older lavas surrounding the lava field are older than 8000 yrs. Faults and a thin sediment cover on many lavas support the ages and indicate that this part of the Mid-Atlantic Ridge is in a tectonic rather than in a magmatic stage. Lavas from the northern and southern ends of the southern lava unit have lower MgO but higher Cl/K than those from the centre of the unit indicating more extensive cooling and assimilation of hydrothermally altered material during ascent, most likely at the tips of the feeder dike. The compositional heterogeneity on a scale of 3 km suggests small magma batches that rise vertically from the mantle to the surface without significant lateral flow and mixing. Thus, the observations on the 8°48'S lava field are in agreement with low frequency eruptions from single ascending magma batches beneath slow-spreading ridges. Bruguier, N.J., Minshull, T.A., Brozena, J.M., 2003. Morphology and tectonics of the Mid-Atlantic Ridge, 7°-12°S. Journal of Geophysical Research, 108: DOI: 10.1029/2001JB001172. Hoernle, K., Hauff, F., Kokfelt, T.F., Haase, K., Garbe-Schönberg, D., and Werner, R., 2011, On- and off-axis chemical heterogeneities along the South Atlantic Mid-Ocean-Ridge (5-11°S): Shallow or deep recycling of ocean crust and/or intraplate volcanism?: Earth and Planetary Science Letters, v. 306, p. 86-97.

Self-contained filtered density function

DOE PAGES

Nouri, Arash G.; Nik, Mehdi B.; Givi, Pope; ...

2017-09-18

The filtered density function (FDF) closure is extended to a “self-contained” format to include the subgrid-scale (SGS) statistics of all of the hydro-thermo-chemical variables in turbulent flows. These are the thermodynamic pressure, the specific internal energy, the velocity vector, and the composition field. In this format, the model is comprehensive and facilitates large-eddy simulation (LES) of flows at both low and high compressibility levels. A transport equation is developed for the joint pressure-energy-velocity-composition filtered mass density function (PEVC-FMDF). In this equation, the effect of convection appears in closed form. The coupling of the hydrodynamics and thermochemistry is modeled via amore » set of stochastic differential equation for each of the transport variables. This yields a self-contained SGS closure. We demonstrated how LES is conducted of a turbulent shear flow with transport of a passive scalar. Finally, the consistency of the PEVC-FMDF formulation is established, and its overall predictive capability is appraised via comparison with direct numerical simulation (DNS) data.« less

Self-contained filtered density function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nouri, Arash G.; Nik, Mehdi B.; Givi, Pope

The filtered density function (FDF) closure is extended to a “self-contained” format to include the subgrid-scale (SGS) statistics of all of the hydro-thermo-chemical variables in turbulent flows. These are the thermodynamic pressure, the specific internal energy, the velocity vector, and the composition field. In this format, the model is comprehensive and facilitates large-eddy simulation (LES) of flows at both low and high compressibility levels. A transport equation is developed for the joint pressure-energy-velocity-composition filtered mass density function (PEVC-FMDF). In this equation, the effect of convection appears in closed form. The coupling of the hydrodynamics and thermochemistry is modeled via amore » set of stochastic differential equation for each of the transport variables. This yields a self-contained SGS closure. We demonstrated how LES is conducted of a turbulent shear flow with transport of a passive scalar. Finally, the consistency of the PEVC-FMDF formulation is established, and its overall predictive capability is appraised via comparison with direct numerical simulation (DNS) data.« less

Self-contained filtered density function

NASA Astrophysics Data System (ADS)

Nouri, A. G.; Nik, M. B.; Givi, P.; Livescu, D.; Pope, S. B.

2017-09-01

The filtered density function (FDF) closure is extended to a "self-contained" format to include the subgrid-scale (SGS) statistics of all of the hydro-thermo-chemical variables in turbulent flows. These are the thermodynamic pressure, the specific internal energy, the velocity vector, and the composition field. In this format, the model is comprehensive and facilitates large-eddy simulation (LES) of flows at both low and high compressibility levels. A transport equation is developed for the joint pressure-energy-velocity-composition filtered mass density function (PEVC-FMDF). In this equation, the effect of convection appears in closed form. The coupling of the hydrodynamics and thermochemistry is modeled via a set of stochastic differential equation for each of the transport variables. This yields a self-contained SGS closure. For demonstration, LES is conducted of a turbulent shear flow with transport of a passive scalar. The consistency of the PEVC-FMDF formulation is established, and its overall predictive capability is appraised via comparison with direct numerical simulation (DNS) data.

AMS analysis and flow source relationship of lava flows and ignimbrites from the eastern Trans-Mexican Volcanic Belt, Mexico

NASA Astrophysics Data System (ADS)

Caballero, C. I.; Alva-Valdivia, L. M.; Morales-Barrera, W.; Rodríguez, S. R.

2013-05-01

The results of an AMS analysis carried on 36 sites from a late Miocene - Holocene volcanic stratigraphic sequence from the eastern Trans-Mexican Volcanic Belt is presented. 22 sites (450 samples) belong to lava flows, mainly of basaltic composition, from different emission centers from the Xalapa Monogenitc Volcanic Field, (Rodríguez et al 2010, González-Mercado, 2005), "Cofre de Perote Vent Cluster" (CPVC), "Naolinco Volcanic Field" (NVF), (Siebert and Carrasco-Núñez, 2002), and the Chiconquiaco-Palma Sola volcanic complex (López-Infanzón, 1991; Ferrari et al., 2005). 14 sites belong to the widely distributed El Castillo rhyolitic ignimbrite dated 2.44 to 2.21 Ma (Morales-Barrera, 2009) which is a non-welded to welded ignimbrite. AMS measurements were performed with a KLY2 Kappabridge and processed with Anisoft software using Jelinek statistics. Sometimes a density distribution analysis was also performed when magnetic fabric showed more dispersed distribution patterns. AMS ellipsoids from basalt sites show mostly prolate shapes, while those from ignimbrites show mostly oblate shapes, which may partly due to magnetic mineralogy and also to flow dynamics. Flow directions were mostly obtained from the imbrication angle of magnetic foliation (evaluated from kmin axis mean as corresponding to its pole) and considering the symmetry of the axes distribution. Flow direction inferences are discussed in relation with flow source when it is clearly evident from geologic field observations, as it is usually the case with basalt lava flows. While in ignimbrites, flow inferences from petrographic and facies distributions are compared with AMS flow inferences, showing agreement between them in some cases but not in others, may be due to local tilting occurring after ignimbrite emplacement.

Development of Supersonic Combustion Experiments for CFD Modeling

NASA Technical Reports Server (NTRS)

Baurle, Robert; Bivolaru, Daniel; Tedder, Sarah; Danehy, Paul M.; Cutler, Andrew D.; Magnotti, Gaetano

2007-01-01

This paper describes the development of an experiment to acquire data for developing and validating computational fluid dynamics (CFD) models for turbulence in supersonic combusting flows. The intent is that the flow field would be simple yet relevant to flows within hypersonic air-breathing engine combustors undergoing testing in vitiated-air ground-testing facilities. Specifically, it describes development of laboratory-scale hardware to produce a supersonic combusting coaxial jet, discusses design calculations, operability and types of flames observed. These flames are studied using the dual-pump coherent anti- Stokes Raman spectroscopy (CARS) - interferometric Rayleigh scattering (IRS) technique. This technique simultaneously and instantaneously measures temperature, composition, and velocity in the flow, from which many of the important turbulence statistics can be found. Some preliminary CARS data are presented.

3D modeling of squeeze flow of unidirectionally thermoplastic composite inserts

NASA Astrophysics Data System (ADS)

Ghnatios, Chady; Abisset-Chavanne, Emmanuelle; Binetruy, Christophe; Chinesta, Francisco; Advani, Suresh

2016-10-01

Thermoplastic composites are attractive because they can be recycled and exhibit superior mechanical properties. The ability of thermoplastic resin to melt and solidify allows for fast and cost-effective manufacturing processes, which is a crucial property for high volume production. Thermoplastic composite parts are usually obtained by stacking several prepreg plies to create a laminate with a particular orientation sequence to meet design requirements. During the consolidation and forming process, the thermoplastic laminate is subjected to complex deformation which can include intraply and/or interply shear, ply reorientation and squeeze flow. In the case of unidirectional prepregs, the ply constitutive equation, when elastic effects are neglected, can be modeled as a transversally isotropic fluid, that must satisfy the fiber inextensibility as well as the fluid incompressibility. The high-fidelity solution of the squeeze flow in laminates composed of unidirectional prepregs was addressed in our former works by making use of an in-plane-out-of-plane separated representation allowing a very detailed resolution of the involved fields throughout the laminate thickness. In the present work prepregs plies are supposed of limited dimensions compared to the in-plane dimension of the part and will be named inserts. Again within the Proper Generalized Decomposition framework high-resolution simulation of the squeeze flow occurring during consolidation is addressed within a fully 3D in-plane-out-of-plane separated representation.

Tropospheric transport differences between models using the same large-scale meteorological fields

NASA Astrophysics Data System (ADS)

Orbe, Clara; Waugh, Darryn W.; Yang, Huang; Lamarque, Jean-Francois; Tilmes, Simone; Kinnison, Douglas E.

2017-01-01

The transport of chemicals is a major uncertainty in the modeling of tropospheric composition. A common approach is to transport gases using the winds from meteorological analyses, either using them directly in a chemical transport model or by constraining the flow in a general circulation model. Here we compare the transport of idealized tracers in several different models that use the same meteorological fields taken from Modern-Era Retrospective analysis for Research and Applications (MERRA). We show that, even though the models use the same meteorological fields, there are substantial differences in their global-scale tropospheric transport related to large differences in parameterized convection between the simulations. Furthermore, we find that the transport differences between simulations constrained with the same-large scale flow are larger than differences between free-running simulations, which have differing large-scale flow but much more similar convective mass fluxes. Our results indicate that more attention needs to be paid to convective parameterizations in order to understand large-scale tropospheric transport in models, particularly in simulations constrained with analyzed winds.

Effects of the Canopy and Flux Tube Anchoring on Evaporation Flow of a Solar Flare

NASA Astrophysics Data System (ADS)

Unverferth, John; Longcope, Dana

2018-06-01

Spectroscopic observations of flare ribbons typically show chromospheric evaporation flows, which are subsonic for their high temperatures. This contrasts with many numerical simulations where evaporation is typically supersonic. These simulations typically assume flow along a flux tube with a uniform cross-sectional area. A simple model of the magnetic canopy, however, includes many regions of low magnetic field strength, where flux tubes achieve local maxima in their cross-sectional area. These are analgous to a chamber in a flow tube. We find that one-third of all field lines in a model have some form of chamber through which evaporation flow must pass. Using a one-dimensional isothermal hydrodynamic code, we simulated supersonic flow through an assortment of chambers and found that a subset of solutions exhibit a stationary standing shock within the chamber. These shocked solutions have slower and denser upflows than a flow through a uniform tube would. We use our solution to construct synthetic spectral lines and find that the shocked solutions show higher emission and lower Doppler shifts. When these synthetic lines are combined into an ensemble representing a single canopy cell, the composite line appears slower, even subsonic, than expected due to the outsized contribution from shocked solutions.

Inducing Propulsion of Colloidal Dimers by Breaking the Symmetry in Electrohydrodynamic Flow.

PubMed

Ma, Fuduo; Yang, Xingfu; Zhao, Hui; Wu, Ning

2015-11-13

We show that dielectric colloidal dimers with broken symmetry in geometry, composition, or interfacial charges can all propel in directions that are perpendicular to the applied ac electric field. The asymmetry in particle properties ultimately results in an unbalanced electrohydrodynamic flow on two sides of the particles. Consistent with scaling laws, the propulsion direction, speed, and orientation of dimers can be conveniently tuned by frequency. The new propulsion mechanism revealed here is important for building colloidal motors and studying collective behavior of active matter.

40Ar/39Ar geochronology and petrogenesis of the Table Mountain Shoshonite, Golden, Colorado, U.S.A.

USGS Publications Warehouse

Millikin, Alexie E. G.; Morgan, Leah; Noblett, Jeffery

2018-01-01

The Upper Cretaceous and Lower Paleogene Table Mountain Shoshonite lava flows and their proposed source, the Ralston Buttes intrusions, provide insight into the volcanic history of the Colorado Front Range. This study affirms the long-held hypothesis linking the extrusive Table Mountain lava flows and their intrusive equivalents at Ralston Buttes through major- and trace- element geochemistry. Systematic 40Ar/39Ar geochronology from all flows and intrusive units refines the eruptive history, improves precision on previously reported ages, and provides tighter constraints on the position of the K-Pg boundary in this location. Four flows are recognized on North and South Table mountains outside of Golden, Colorado. Flow 1 (66.5 ± 0.3 Ma, all ages reported with 2σ uncertainty) is the oldest, most compositionally distinct flow and is separated from younger flows by approximately 35 m of sedimentary deposits of the Denver Formation. Stratigraphically adjacent flows 2 (65.8 ± 0.2 Ma), 3 (65.5 ± 0.3 Ma), and 4 (65.9 ± 0.3 Ma) are compositionally indistinguishable. Lavas (referred to here as unit 5) that form three cone-shaped structures (shown by this study to be volcanic vents of a new unit 5) on top of North Table Mountain are compositionally similar to other units, but yield an age almost 20 m.y. younger (46.94 ± 0.15 Ma). Geochemistry and geochronology suggest that the rim phase of the Ralston plug (65.4 ± 0.2 Ma) is a reasonable source for flows 2, 3, and 4. All units are shoshonites—potassic basalts containing plagioclase, augite, olivine, and magnetite phenocrysts—and plot in the continental-arc field in tectonic discrimination diagrams. A continental-arc setting coupled with Late Cretaceous to early Paleogene ages suggest the high-K magmatism is associated with Laramide tectonism.

Numerical Investigation of Flow in a Centrifugal Compressor

NASA Astrophysics Data System (ADS)

Grishin, Yu. A.; Bakulin, V. N.

2015-09-01

With the use of the domestic software suite of computational hydrodynamics Flow Vision based on application of the method of control volumes, numerical simulation of air composition and delivery by a centrifugal compressor employed for supercharging a piston engine has been carried out. The head-flow characteristics of the compressor, as well as the 3D fields of flow velocity and pressure distributions in the elements of the compressor flow passage, including the interblade channels of the impeller, have been obtained for various regimes. In the regimes of diminished air flow rate, surging phenomena are identified, characterized by a return flow. The application of the technique of numerical experiment will make it possible from here on to carry out design optimization of the compressor flow passage profile and thus to improve its basic characteristics — the degree of pressure increase, compressed air flow rate, and the efficiency — as well as to reduce the costs of the development and production of compressors.

Similarities in basalt and rhyolite lava flow emplacement processes

NASA Astrophysics Data System (ADS)

Magnall, Nathan; James, Mike; Tuffen, Hugh; Vye-Brown, Charlotte

2016-04-01

Here we use field observations of rhyolite and basalt lava flows to show similarities in flow processes that span compositionally diverse lava flows. The eruption, and subsequent emplacement, of rhyolite lava flows is currently poorly understood due to the infrequency with which rhyolite eruptions occur. In contrast, the emplacement of basaltic lava flows are much better understood due to very frequent eruptions at locations such as Mt Etna and Hawaii. The 2011-2012 eruption of Cordón Caulle in Chile enabled the first scientific observations of the emplacement of an extensive rhyolite lava flow. The 30 to 100 m thick flow infilled a topographic depression with a negligible slope angle (0 - 7°). The flow split into two main channels; the southern flow advanced 4 km while the northern flow advanced 3 km before stalling. Once the flow stalled the channels inflated and secondary flows or breakouts formed from the flow front and margins. This cooling rather than volume-limited flow behaviour is common in basaltic lava flows but had never been observed in rhyolite lava flows. We draw on fieldwork conducted at Cordón Caulle and at Mt Etna to compare the emplacement of rhyolite and basaltic flows. The fieldwork identified emplacement features that are present in both lavas, such as inflation, breakouts from the flow font and margins, and squeeze-ups on the flow surfaces. In the case of Cordón Caulle, upon extrusion of a breakout it inflates due to a combination of continued lava supply and vesicle growth. This growth leads to fracturing and breakup of the breakout surface, and in some cases a large central fracture tens of metres deep forms. In contrast, breakouts from basaltic lava flows have a greater range of morphologies depending on the properties of the material in the flows core. In the case of Mt Etna, a range of breakout morphologies are observed including: toothpaste breakouts, flows topped with bladed lava as well as breakouts of pahoehoe or a'a lava. This range in breakout morphologies is in stark contrast to breakouts observed at Cordón Caulle. We also compare the cooled crusts that form on the surface of the flows; in basalts this is of order tens of centimetres thick, in rhyolite flows the crust is of order several metres thick (based on field observations and theoretical values). This surface crust may control the flow advance in the latter phases of the flow evolution, causing stalling of the flow front and subsequent breakout formation. The similarities in flow features between compositional end members hints at a more universal model for lava flow emplacement.

Calculation of Macrosegregation in an Ingot

NASA Technical Reports Server (NTRS)

Poirier, D. R.; Maples, A. L.

1986-01-01

Report describes both two-dimensional theoretical model of macrosegregation (separating into regions of discrete composition) in solidification of binary alloy in chilled rectangular mold and interactive computer program embodying model. Model evolved from previous ones limited to calculating effects of interdendritic fluid flow on final macrosegregation for given input temperature field under assumption of no fluid in bulk melt.

Method of fabricating composite structures

NASA Technical Reports Server (NTRS)

Sigur, W. A. (Inventor)

1990-01-01

A method of fabricating structures formed from composite materials by positioning the structure about a high coefficient of thermal expansion material, wrapping a graphite fiber overwrap about the structure, and thereafter heating the assembly to expand the high coefficient of thermal expansion material to forcibly compress the composite structure against the restraint provided by the graphite overwrap. The high coefficient of thermal expansion material is disposed about a mandrel with a release system therebetween, and with a release system between the material having the high coefficient of thermal expansion and the composite material, and between the graphite fibers and the composite structure. The heating may occur by inducing heat into the assembly by a magnetic field created by coils disposed about the assembly through which alternating current flows. The method permits structures to be formed without the use of an autoclave.

Method of fabricating composite structures

NASA Technical Reports Server (NTRS)

Sigur, Wanda A. (Inventor)

1992-01-01

A method of fabricating structures formed from composite materials by positioning the structure about a high coefficient of thermal expansion material, wrapping a graphite fiber overwrap about the structure, and thereafter heating the assembly to expand the high coefficient of thermal expansion material to forcibly compress the composite structure against the restraint provided by the graphite overwrap. The high coefficient of thermal expansion material is disposed about a mandrel with a release system therebetween, and with a release system between the material having the high coefficient of thermal expansion and the composite material, and between the graphite fibers and the composite structure. The heating may occur by inducing heat into the assembly by a magnetic field created by coils disposed about the assembly through which alternating current flows. The method permits structures to be formed without the use of an autoclave.

New Numerical Approaches To thermal Convection In A Compositionally Stratified Fluid

NASA Astrophysics Data System (ADS)

Puckett, E. G.; Turcotte, D. L.; Kellogg, L. H.; Lokavarapu, H. V.; He, Y.; Robey, J.

2016-12-01

Seismic imaging of the mantle has revealed large and small scale heterogeneities in the lower mantle; specifically structures known as large low shear velocity provinces (LLSVP) below Africa and the South Pacific. Most interpretations propose that the heterogeneities are compositional in nature, differing from the overlying mantle, an interpretation that would be consistent with chemical geodynamic models. The LLSVP's are thought to be very old, meaning they have persisted thoughout much of Earth's history. Numerical modeling of persistent compositional interfaces present challenges to even state-of-the-art numerical methodology. It is extremely difficult to maintain sharp composition boundaries which migrate and distort with time dependent fingering without compositional diffusion and / or artificial diffusion. The compositional boundary must persist indefinitely. In this work we present computations of an initial compositionally stratified fluid that is subject to a thermal gradient ΔT = T1 - T0 across the height D of a rectangular domain over a range of buoyancy numbers B and Rayleigh numbers Ra. In these computations we compare three numerical approaches to modeling the movement of two distinct, thermally driven, compositional fields; namely, a high-order Finte Element Method (FEM) that employs artifical viscosity to preserve the maximum and minimum values of the compositional field, a Discontinous Galerkin (DG) method with a Bound Preserving (BP) limiter, and a Volume-of-Fluid (VOF) interface tracking algorithm. Our computations demonstrate that the FEM approach has far too much numerical diffusion to yield meaningful results, the DGBP method yields much better resuts but with small amounts of each compositional field being (numerically) entrained within the other compositional field, while the VOF method maintains a sharp interface between the two compositions throughout the computation. In the figure we show a comparison of between the three methods for a computation made with B = 1.111 and Ra = 10,000 after the flow has reached 'steady state'. (R) the images computed with the standard FEM method (with artifical viscosity), (C) the images computed with the DGBP method (with no artifical viscosity or diffusion due to discretization errors) and (L) the images computed with the VOF algorithm.

Stratigraphy and compositional evolution of Cinder Cone, a composite monogenetic cone in Lassen Volcanic National Park, California

NASA Astrophysics Data System (ADS)

Clynne, M. A.

2011-12-01

Cinder Cone, in Lassen Volcanic National Park, has received considerable attention in the literature since its description by Harkness (1875) and Diller (1891) and has provoked considerable controversy concerning its age and eruptive history (e.g. Finch and Anderson, 1930; Finch, 1937). Geologic mapping of the composite cinder cone, an extensive tephra blanket, and 5 lava flows determined the eruptive sequence stratigraphy (Clynne and Muffler, 2010), and tree-ring chronology dated the eruption as 1666 C.E. (Sheppard et al., 2008). Tephra, divided into 3 units by Heiken (1978), accounts for 20% of the 0.36 km3 total volume of the eruption. The lava field consists of 5 block lava flows: Old Bench (OB), Painted Dunes (PD) 1 and 2, and Fantastic Lava Beds (FL) 1 and 2. Magnesian olivine containing inclusions of chromian spinel is the most abundant phenocryst, followed by plagioclase and sparse augite. Xenocrystic quartz is ubiquitous. Three types of inclusions are present: 1) sparse, mostly melted, inclusions of granitic rocks derived from Sierran basement, 2) abundant single crystals of quartz derived from granitic rocks and multicrystalline inclusions of metamorphic quartz from veins, and 3) rare magmatic enclaves of olivine basalt with quenched textures. The tephra and OB, PD, and FL lithologies are olivine basaltic andesite to andesite with subtle differences. Analyses of tephra from a measured section document the compositional evolution of Cinder Cone eruption. Unit 1 tephra contains 55.5% SiO2, 7.9% MgO, and 1.25% K2O. Initial unit 2 tephra contains 54.8% SiO2, 8.2% MgO, and 1.2% K2O. Unit 2 tephra becomes increasing more mafic up section to 53.8% SiO2, 9.0% MgO, and 1.0% K2O and then rapidly more felsic to 56.3% SiO2, 8.0% MgO, and 1.3% K2O. Initial unit 3 tephra contains 58.0% SiO2, 7.5% MgO, and 1.6% K2O but becomes more mafic to 55.0% SiO2, 7.5% MgO, and 1.2% K2O up section. The OB flow and the early PD 1 flow are equivalent in composition to the early unit 2 tephra, and the subsequent late PD 1 flow and PD 2 flows mimic late unit 2 tephra. FL 1 and 2 flows are compositionally equivalent to early and late unit 3 tephra, respectively. A mostly destroyed remnant cinder cone has unit 2 tephra composition, and Cinder Cone has unit 3 composition. The complex compositional variation at Cinder Cone, superficially a monogenetic volcano, is ascribed to the combined effects of fractional crystallization and assimilation and concurrent recharge of the system by a new mafic magma. Variation of the early magmas can be modeled by fractional crystallization and assimilation of granitic xenoliths. The reversal of compositional variation near the unit 2-3 boundary and subsequent decrease in SiO2 can be modeled by mixing with a new mafic magma having the composition of the quenched basaltic enclaves. Details of the mineral compositions are consistent with the stratigraphy and bulk compositional evolution.

Effect of corona discharge on the gas composition of the sample flow in a Gas Particle Partitioner.

PubMed

Asbach, Christof; Kuhlbusch, Thomas A J; Fissan, Heinz

2005-09-01

A Gas Particle Partitioner (GPP) that allows highly efficient separation of gas and particles with no effect on the thermodynamic conditions and substantially no change of the gas composition has been developed. The GPP is a coaxial arrangement with inner and outer electrodes and utilizes a corona discharge to electrically charge the particles and a strong electric field to remove them from the sample flow. Several measures were taken to avoid an influence of the corona discharge on the gas composition. The GPP can be applied for various applications. This paper focuses on the use of the GPP as a pre-filter for gas analyzers, where zero pressure drop and a minimization of the influence of the corona discharge on the gas composition are the main objective. Due to its design, the GPP introduces no changes to the thermodynamic conditions. However, corona discharge is known to produce significant amounts of ozone and oxides of nitrogen. The effect of the corona on the gas composition of the sample flow was determined under various conditions. The gas concentrations strongly depended on several aspects, such as material and diameter of the corona wire and polarity of the corona voltage. Due to the measures taken to minimize an effect on the gas composition, the concentrations of these gases could effectively be reduced. Along with the maximum gas-particle separation efficiency of near 100%, the additional O3 concentration was 42 ppbV and the additional NO2 concentration 15 ppbV. If an efficiency of 95% is acceptable, the added concentrations can be as low as 2.5 ppbV (O3) and 0.5 ppbV (NO2), respectively.

Disturbance of the inclined inserting-type sand fence to wind-sand flow fields and its sand control characteristics

NASA Astrophysics Data System (ADS)

Cheng, Jian-jun; Lei, Jia-qiang; Li, Sheng-yu; Wang, Hai-feng

2016-06-01

The inclined inserting-type sand fence is a novel sand retaining wall adopted along the Lanxin High-Speed Railway II in Xinjiang for controlling and blocking sand movement. To verify the effectiveness of the new fence structure for sand prevention, a wind tunnel test was used for flow field test simulation of the sand fence. The results indicate that the inclined inserting-type sand fence was able to deflect the flow of the sand and was able to easily form an upward slant acceleration zone on the leeward side of the sand fence. As shown by the percentage change in sand collection rates on the windward side and the leeward side of the sand fence, the sand flux per unit area at 4 m height in the slant upward direction increased on the leeward side of the inclined inserting-type sand fence. By comparing the flow fields, this site is an acceleration zone, which also reaffirms the correspondence of wind-sand flow fields with the spatial distribution characteristic of the wind-carried sand motion. The field sand collection data indicates that under the effects of the inclined inserting-type sand fence, the sandy air currents passing in front and behind the sand fence not only changed in quality, but the grain composition and particle size also significantly changed, suggesting that the inclined inserting-type sand fence has a sorting and filtering effect on the sandy air currents that passed through. The fence retained coarse particulates on the windward side and fine particulates within the shade of the wind on the leeward side.

Effect of Target Composition and Sputtering Deposition Parameters on the Functional Properties of Nitrogenized Ag-Permalloy Flexible Thin Films Deposited on Polymer Substrates

PubMed Central

Wang, Qun; Jin, Xin

2018-01-01

We report the first results of functional properties of nitrogenized silver-permalloy thin films deposited on polyethylene terephthalic ester {PETE (C10H8O4)n} flexible substrates by magnetron sputtering. These new soft magnetic thin films have magnetization that is comparable to pure Ni81Fe19 permalloy films. Two target compositions (Ni76Fe19Ag5 and Ni72Fe18Ag10) were used to study the effect of compositional variation and sputtering parameters, including nitrogen flow rate on the phase evolution and surface properties. Aggregate flow rate and total pressure of Ar+N2 mixture was 60 sccm and 0.55 Pa, respectively. The distance between target and the substrate was kept at 100 mm, while using sputtering power from 100–130 W. Average film deposition rate was confirmed at around 2.05 nm/min for argon atmosphere and was reduced to 1.8 nm/min in reactive nitrogen atmosphere. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, vibrating sample magnetometer, and contact angle measurements were used to characterize the functional properties. Nano sized character of films was confirmed by XRD and SEM. It is found that the grain size was reduced by the formation of nitride phase, which in turns enhanced the magnetization and lowers the coercivity. Magnetic field coupling efficiency limit was determined from 1.6–2 GHz frequency limit. The results of comparable magnetic performance, lowest magnetic loss, and highest surface free energy, confirming that 15 sccm nitrogen flow rate at 115 W is optimal for producing Ag-doped permalloy flexible thin films having excellent magnetic field coupling efficiency. PMID:29562603

New insights into insect's silent flight. Part II: sound source and noise control

NASA Astrophysics Data System (ADS)

Xue, Qian; Geng, Biao; Zheng, Xudong; Liu, Geng; Dong, Haibo

2016-11-01

The flapping flight of aerial animals has excellent aerodynamic performance but meanwhile generates low noise. In this study, the unsteady flow and acoustic characteristics of the flapping wing are numerically investigated for three-dimensional (3D) models of Tibicen linnei cicada at free forward flight conditions. Single cicada wing is modelled as a membrane with prescribed motion reconstructed by Wan et al. (2015). The flow field and acoustic field around the flapping wing are solved with immersed-boundary-method based incompressible flow solver and linearized-perturbed-compressible-equations based acoustic solver. The 3D simulation allows examination of both directivity and frequency composition of the produced sound in a full space. The mechanism of sound generation of flapping wing is analyzed through correlations between acoustic signals and flow features. Along with a flexible wing model, a rigid wing model is also simulated. The results from these two cases will be compared to investigate the effects of wing flexibility on sound generation. This study is supported by NSF CBET-1313217 and AFOSR FA9550-12-1-0071.

Colloidal Mechanisms of Gold Nanoparticle Loss in Asymmetric Flow Field-Flow Fractionation.

PubMed

Jochem, Aljosha-Rakim; Ankah, Genesis Ngwa; Meyer, Lars-Arne; Elsenberg, Stephan; Johann, Christoph; Kraus, Tobias

2016-10-07

Flow field-flow fractionation is a powerful method for the analysis of nanoparticle size distributions, but its widespread use has been hampered by large analyte losses, especially of metal nanoparticles. Here, we report on the colloidal mechanisms underlying the losses. We systematically studied gold nanoparticles (AuNPs) during asymmetrical flow field-flow fractionation (AF4) by systematic variation of the particle properties and the eluent composition. Recoveries of AuNPs (core diameter 12 nm) stabilized by citrate or polyethylene glycol (PEG) at different ionic strengths were determined. We used online UV-vis detection and off-line elementary analysis to follow particle losses during full analysis runs, runs without cross-flow, and runs with parts of the instrument bypassed. The combination allowed us to calculate relative and absolute analyte losses at different stages of the analytic protocol. We found different loss mechanisms depending on the ligand. Citrate-stabilized particles degraded during analysis and suffered large losses (up to 74%). PEG-stabilized particles had smaller relative losses at moderate ionic strengths (1-20%) that depended on PEG length. Long PEGs at higher ionic strengths (≥5 mM) caused particle loss due to bridging adsorption at the membrane. Bulk agglomeration was not a relevant loss mechanism at low ionic strengths ≤5 mM for any of the studied particles. An unexpectedly large fraction of particles was lost at tubing and other internal surfaces. We propose that the colloidal mechanisms observed here are relevant loss mechanisms in many particle analysis protocols and discuss strategies to avoid them.

Size fractionation and size characterization of nanoemulsions of lipid droplets and large unilamellar lipid vesicles by asymmetric-flow field-flow fractionation/multi-angle light scattering and dynamic light scattering.

PubMed

Vezočnik, Valerija; Rebolj, Katja; Sitar, Simona; Ota, Katja; Tušek-Žnidarič, Magda; Štrus, Jasna; Sepčić, Kristina; Pahovnik, David; Maček, Peter; Žagar, Ema

2015-10-30

Asymmetric-flow field-flow fractionation technique coupled to a multi-angle light-scattering detector (AF4-MALS) was used together with dynamic light-scattering (DLS) in batch mode and transmission electron microscopy (TEM) to study the size characteristics of the trioleoylglycerol lipid droplets covered by a monolayer of sphingomyelin and cholesterol, in water phase. These lipid droplet nanoemulsions (LD) were formed by ultrasonication. In parallel, the size characteristics of large unilamellar lipid vesicles (LUV) prepared by extrusion and composed of sphingomyelin and cholesterol were determined. LD and LUV were prepared at two different molar ratios (1/1, 4/1) of sphingomyelin and cholesterol. In AF4-MALS, various cross-flow conditions and mobile phase compositions were tested to optimize the separation of LD or LUV particles. The particle radii, R, as well as the root-mean-square radii, Rrms, of LD and LUV were determined by AF4-MALS, whereas the hydrodynamic radii, Rh, were obtained by DLS. TEM visualization revealed round shape particles of LD and LUV. Copyright © 2015 Elsevier B.V. All rights reserved.

Confocal microscopy of fluid inclusions reveals fluid-pressure histories of sediments and an unexpected origin of gas condensate

NASA Astrophysics Data System (ADS)

Aplin, Andrew C.; Larter, Steve R.; Bigge, M. Ashley; MacLeod, Gordon; Swarbrick, Richard E.; Grunberger, Daniel

2000-11-01

We present two examples of how fluid inclusion data can be used to determine geologic pressure histories and to quantify the compositional evolution of petroleum in oil reservoirs. Volumetric liquid: vapor ratios generated with a confocal laser scanning microscope are used along with pressure-vapor-temperature (P-V-T) modeling software to estimate the composition, P-T phase envelope, and isochore of single petroleum inclusions in the North Sea's Judy and Alwyn fields. In both cases, the gas condensates currently in the reservoirs formed by the emplacement of gas into preexisting oil accumulations. Pressure histories of individual units in each field are also revealed, providing the kind of data needed to determine the permeability and fluid flow histories of sedimentary basins.

Field-trip guide to Columbia River flood basalts, associated rhyolites, and diverse post-plume volcanism in eastern Oregon

USGS Publications Warehouse

Ferns, Mark L.; Streck, Martin J.; McClaughry, Jason D.

2017-08-09

The Miocene Columbia River Basalt Group (CRBG) is the youngest and best preserved continental flood basalt province on Earth, linked in space and time with a compositionally diverse succession of volcanic rocks that partially record the apparent emergence and passage of the Yellowstone plume head through eastern Oregon during the late Cenozoic. This compositionally diverse suite of volcanic rocks are considered part of the La Grande-Owyhee eruptive axis (LOEA), an approximately 300-kilometer-long (185 mile), north-northwest-trending, middle Miocene to Pliocene volcanic belt located along the eastern margin of the Columbia River flood basalt province. Volcanic rocks erupted from and preserved within the LOEA form an important regional stratigraphic link between the (1) flood basalt-dominated Columbia Plateau on the north, (2) bimodal basalt-rhyolite vent complexes of the Owyhee Plateau on the south, (3) bimodal basalt-rhyolite and time-transgressive rhyolitic volcanic fields of the Snake River Plain-Yellowstone Plateau, and (4) the High Lava Plains of central Oregon.This field-trip guide describes a 4-day geologic excursion that will explore the stratigraphic and geochemical relationships among mafic rocks of the Columbia River Basalt Group and coeval and compositionally diverse volcanic rocks associated with the early “Yellowstone track” and High Lava Plains in eastern Oregon. Beginning in Portland, the Day 1 log traverses the Columbia River gorge eastward to Baker City, focusing on prominent outcrops that reveal a distal succession of laterally extensive, large-volume tholeiitic flood lavas of the Grande Ronde, Wanapum, and Saddle Mountains Basalt formations of the CRBG. These “great flows” are typical of the well-studied flood basalt-dominated Columbia Plateau, where interbedded silicic and calc-alkaline lavas are conspicuously absent. The latter part of Day 1 will highlight exposures of middle to late Miocene silicic ash-flow tuffs, rhyolite domes, and calc-alkaline lava flows overlying the CRBG across the northern and central parts of the LOEA. The Day 2 field route migrates to southern parts of the LOEA, where rocks of the CRBG are associated in space and time with lesser known and more complex silicic volcanic stratigraphy associated with middle Miocene, large-volume, bimodal basalt-rhyolite vent complexes. Key stops will provide a broad overview of the structure and stratigraphy of the middle Miocene Mahogany Mountain caldera and middle to late Miocene calc-alkaline lavas of the Owyhee basalt. Stops on Day 3 will progress westward from the eastern margin of the LOEA, examining a transition linking the Columbia River Basalt-Yellowstone province with a northwestward-younging magmatic trend of silicic volcanism that underlies the High Lava Plains of eastern Oregon. Initial field stops on Day 3 will examine key outcrops demonstrating the intercalated nature of middle Miocene tholeiitic CRBG flood basalts, prominent ash-flow tuffs, and “Snake River-type” large-volume rhyolite lava flows exposed along the Malheur River. Subsequent stops on Day 3 will focus upon the volcanic stratigraphy northeast of the town of Burns, which includes regional middle to late Miocene ash-flow tuffs, and lava flows assigned to the Strawberry Volcanics. The return route to Portland on Day 4 traverses across the western axis of the Blue Mountains, highlighting exposures of the widespread, middle Miocene Dinner Creek Tuff and aspects of Picture Gorge Basalt flows and northwest-trending feeder dikes situated in the central part of the CRBG province.

Strontium isotopic signatures of oil-field waters: Applications for reservoir characterization

USGS Publications Warehouse

Barnaby, R.J.; Oetting, G.C.; Gao, G.

2004-01-01

The 87Sr/86Sr compositions of formation waters that were collected from 71 wells producing from a Pennsylvanian carbonate reservoir in New Mexico display a well-defined distribution, with radiogenic waters (up to 0.710129) at the updip western part of the reservoir, grading downdip to less radiogenic waters (as low as 0.708903 to the east. Salinity (2800-50,000 mg/L) displays a parallel trend; saline waters to the west pass downdip to brackish waters. Elemental and isotopic data indicate that the waters originated as meteoric precipitation and acquired their salinity and radiogenic 87Sr through dissolution of Upper Permian evaporites. These meteoric-derived waters descended, perhaps along deeply penetrating faults, driven by gravity and density, to depths of more than 7000 ft (2100 m). The 87 Sr/86Sr and salinity trends record influx of these waters along the western field margin and downdip flow across the field, consistent with the strong water drive, potentiometric gradient, and tilted gas-oil-water contacts. The formation water 87Sr/86Sr composition can be useful to evaluate subsurface flow and reservoir behavior, especially in immature fields with scarce pressure and production data. In mature reservoirs, Sr Sr isotopes can be used to differentiate original formation water from injected water for waterflood surveillance. Strontium isotopes thus provide a valuable tool for both static and dynamic reservoir characterization in conjunction with conventional studies using seismic, log, core, engineering, and production data. Copyright ??2004. The American Association of Petroleum Geologist. All rights reserved.

Asymmetric flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry for the quantification of quantum dots bioconjugation efficiency.

PubMed

Menéndez-Miranda, Mario; Encinar, Jorge Ruiz; Costa-Fernández, José M; Sanz-Medel, Alfredo

2015-11-27

Hyphenation of asymmetric flow field-flow fractionation (AF4) to an on-line elemental detection (inductively coupled plasma-mass spectrometry, ICP-MS) is proposed as a powerful diagnostic tool for quantum dots bioconjugation studies. In particular, conjugation effectiveness between a "model" monoclonal IgG antibody (Ab) and CdSe/ZnS core-shell Quantum Dots (QDs), surface-coated with an amphiphilic polymer, has been monitored here by such hybrid AF4-ICP-MS technique. Experimental conditions have been optimized searching for a proper separation between the sought bioconjugates from the eventual free reagents excesses employed during the bioconjugation (QDs and antibodies). Composition and pH of the carrier have been found to be critical parameters to ensure an efficient separation while ensuring high species recovery from the AF4 channel. An ICP-MS equipped with a triple quadropole was selected as elemental detector to enable sensitive and reliable simultaneous quantification of the elemental constituents, including sulfur, of the nanoparticulated species and the antibody. The hyphenated technique used provided nanoparticle size-based separation, elemental detection, and composition analysis capabilities that turned out to be instrumental in order to investigate in depth the Ab-QDs bioconjugation process. Moreover, the analytical strategy here proposed allowed us not only to clearly identify the bioconjugation reaction products but also to quantify nanoparticle:antibodies bioconjugation efficiency. This is a key issue in future development of analytical and bioanalytical photoluminescent QDs applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Including spatial data in nutrient balance modelling on dairy farms

NASA Astrophysics Data System (ADS)

van Leeuwen, Maricke; van Middelaar, Corina; Stoof, Cathelijne; Oenema, Jouke; Stoorvogel, Jetse; de Boer, Imke

2017-04-01

The Annual Nutrient Cycle Assessment (ANCA) calculates the nitrogen (N) and phosphorus (P) balance at a dairy farm, while taking into account the subsequent nutrient cycles of the herd, manure, soil and crop components. Since January 2016, Dutch dairy farmers are required to use ANCA in order to increase understanding of nutrient flows and to minimize nutrient losses to the environment. A nutrient balance calculates the difference between nutrient inputs and outputs. Nutrients enter the farm via purchased feed, fertilizers, deposition and fixation by legumes (nitrogen), and leave the farm via milk, livestock, manure, and roughages. A positive balance indicates to which extent N and/or P are lost to the environment via gaseous emissions (N), leaching, run-off and accumulation in soil. A negative balance indicates that N and/or P are depleted from soil. ANCA was designed to calculate average nutrient flows on farm level (for the herd, manure, soil and crop components). ANCA was not designed to perform calculations of nutrient flows at the field level, as it uses averaged nutrient inputs and outputs across all fields, and it does not include field specific soil characteristics. Land management decisions, however, such as the level of N and P application, are typically taken at the field level given the specific crop and soil characteristics. Therefore the information that ANCA provides is likely not sufficient to support farmers' decisions on land management to minimize nutrient losses to the environment. This is particularly a problem when land management and soils vary between fields. For an accurate estimate of nutrient flows in a given farming system that can be used to optimize land management, the spatial scale of nutrient inputs and outputs (and thus the effect of land management and soil variation) could be essential. Our aim was to determine the effect of the spatial scale of nutrient inputs and outputs on modelled nutrient flows and nutrient use efficiencies at Dutch dairy farms. We selected two dairy farms located on cover sands in the Netherlands. One farm was located on relatively homogeneous soil type, and one on many different soil types within the sandy soils. A full year of data of N and P inputs and outputs on farm and field level were provided by the farmers, including field level yields, yield composition, manure composition, degree of grazing and degree of mowing. Soil heterogeneity was defined as the number of soil units within the farm corrected for surface area, and quantified from the Dutch 1:50.000 soil map. N and P balances at farm and field level were determined, as well as differences in nutrient use efficiency, leaching, and N emission. We will present the effect of the spatial scale on nutrient balance analysis and discuss to which degree any differences are caused by within-farm land management and soil variation. This study highlights to which extent within-farm land management and soil variation should be taken into account when modelling nutrient flows and nutrient use efficiencies at farm level, to contribute to field-based decision making for improved land management.

Transient Conditions at the Ice/bed Interface Under a Palaeo-ice Stream Derived from Numerical Simulation of Groundwater Flow and Sedimentological Observations in a Drumlin Field, NW Poland

NASA Astrophysics Data System (ADS)

Hermanowski, P.; Piotrowski, J. A.

2017-12-01

Evacuation of glacial meltwater through the substratum is an important agent modulating the ice/bed interface processes. The amount of meltwater production, subglacial water pressure, flow patterns and fluxes all affect the strength of basal coupling and thus impact the ice-sheet dynamics. Despite much research into the subglacial processes of past ice sheets which controlled sediment transport and the formation of specific landforms, our understanding of the ice/bed interface remains fragmentary. In this study we numerically simulated, using finite difference and finite element codes, groundwater flow pattern and fluxes during an ice advance in the Stargard Drumlin Field, NW Poland to examine the potential influence of groundwater drainage on the landforming processes. The results are combined with sedimentological observations of the internal composition of the drumlins to validate the outcome of the numerical model. Our numerical experiments of groundwater flow suggest a highly time-dependent response of the subglacial hydrogeological system to the advancing ice margin. This is manifested as diversified areas of downward- and upward-oriented groundwater flows whereby the drumlin field area experienced primarily groundwater discharge towards the ice sole. The investigated drumlins are composed of (i) mainly massive till with thin stringers of meltwater sand, and (ii) sorted sediments carrying ductile deformations. The model results and sedimentological observations suggest a high subglacial pore-water pressure in the drumlin field area, which contributed to sediment deformation intervening with areas of basal decoupling and enhanced basal sliding.

Shear and shearless Lagrangian structures in compound channels

NASA Astrophysics Data System (ADS)

Enrile, F.; Besio, G.; Stocchino, A.

2018-03-01

Transport processes in a physical model of a natural stream with a composite cross-section (compound channel) are investigated by means of a Lagrangian analysis based on nonlinear dynamical system theory. Two-dimensional free surface Eulerian experimental velocity fields of a uniform flow in a compound channel form the basis for the identification of the so-called Lagrangian Coherent Structures. Lagrangian structures are recognized as the key features that govern particle trajectories. We seek for two particular class of Lagrangian structures: Shear and shearless structures. The former are generated whenever the shear dominates the flow whereas the latter behave as jet-cores. These two type of structures are detected as ridges and trenches of the Finite-Time Lyapunov Exponents fields, respectively. Besides, shearlines computed applying the geodesic theory of transport barriers mark Shear Lagrangian Coherent Structures. So far, the detection of these structures in real experimental flows has not been deeply investigated. Indeed, the present results obtained in a wide range of the controlling parameters clearly show a different behaviour depending on the shallowness of the flow. Shear and Shearless Lagrangian Structures detected from laboratory experiments clearly appear as the flow develops in shallow conditions. The presence of these Lagrangian Structures tends to fade in deep flow conditions.

Comparative analysis between Payen and Daedalia Planum lava fields

NASA Astrophysics Data System (ADS)

Giacomini, Lorenza; Massironi, Matteo; Pasquarè, Giorgio; Carli, Cristian; Martellato, Elena; Frigeri, Alessandro; Cremonese, Gabriele; Bistacchi, Andrea; Federico, Costanzo

The Payen volcanic complex is a large Quaternary fissural structure belonging to the back-arc extensional area of the Andes in the Mendoza Province (Argentina). From the eastern portion of this volcanic structure huge pahoehoe lava flows were emitted, extending more than 180 km from the feeding vents. These huge flows propagated over the nearly flat surface of the Pampean foreland (ca 0.3° slope). The very low viscosity of the olivine basalt lavas, coupled with the inflation process are the most probable explanation for their considerable length. In an inflation process a thin viscoelastic crust, produced at an early stage, is later inflated by the underlying fluid core, which remains hot and fluid thanks to the thermal-shield effect of the crust. The inflation shows some typical morphological fingerprints like tumuli, lava lobes, lava rises and lava ridges. In order to compare the morphology of the Argentinean Payen flows with lava flows on Mars, MOLA, THEMIS, MOC, MRO/HIRISE, and MEX/OMEGA data have been analysed, providing a multi-scale characterisation of Martian flows. Mars Global Surveyor/MOLA data were used to investigate the topographic environment over which flows propagated on Mars in order to detect very low angle slopes where possibly inflation processes could have developed. Then Mars Odyssey/THEMIS and Mars Global Surveyor's MOC data were used to detect Martian lava flows with inflation "fingerprints", whereas OMEGA data were used to obtain some inferences about their composition. Finally the MRO/HIRISE images recently acquired, can provide further details and constraints on surface morphologies and lava fronts. All these data were used to analyze Daedalia Planum lava field, at about 300 km southwest of Arsia Mons, and clear morphological similarities with the longest flows of the Payen lava fields were found. These striking morphological analogies suggest that inflation process is quite common also for the Daedalia field. This is also supported by simple calculation of effusion rates for not inflated lava flows foreseeing for the Daedalia Planum long lava flows improbable huge rates. Consequently lower effusion rates coupled with very efficient spreading process are more likely. Nonetheless the comparison of typology vs frequency and dimension of inflation related features of Payen and Daedalia Planum field suggest that even the effusion rates responsible of inflated flows on Mars are by far higher than the one on the Earth.

Effects of Traveling Magnetic Field on Dynamics of Solidification

NASA Technical Reports Server (NTRS)

2003-01-01

The Lorentz body force induced in electrically conducting fluids can be utilized for a number of materials processing technologies. An application of strong static magnetic fields can be beneficial for damping convection present during solidification. On the other hand, alternating magnetic fields can be used to reduce as well as to enhance convection. However, only special types of time dependent magnetic fields can induce a non-zero time averaged Lorentz force needed for convection control. One example is the rotating magnetic field. This field configuration induces a swirling flow in circular containers. Another example of a magnetic field configuration is the traveling magnetic field (TMF). It utilizes axisymmetric magnetostatic waves. This type of field induces an axial recirculating flow that can be advantageous for controlling axial mass transport, such as during solidification in long cylindrical tubes. Incidentally, this is the common geometry for crystal growth research. The Lorentz force induced by TMF can potentially counter-balance the buoyancy force, diminishing natural convection, or even setting up the flow in reverse direction. Crystal growth process in presence of TMF can be then significantly modified. Such properties as the growth rate, interface shape and macro segregation can be affected and optimized. Melt homogenization is the other potential application of TMF. It is a necessary step prior to solidification. TMF can be attractive for this purpose, as it induces a basic flow along the axis of the ampoule. TMF can be a practical alloy mixing method especially suited for solidification research in space. In the theoretical part of this work, calculations of the induced Lorentz force in the whole frequency range have been completed. The basic flow characteristics for the finite cylinder geometry are completed and first results on stability analysis for higher Reynolds numbers are obtained. A theoretical model for TMF mixing is also developed. In the experimental part, measurements of flow induced by TMF in a column of mercury (Hg) are presented. Also, an alloy mixing of Bi-Sn of the eutectic composition is demonstrated. A traveling magnetic field of 4mT at 3kHz applied for 120 minutes is found to be sufficient to homogenize an alloy enclosed in a 1cm diameter and 12 cm long tube.

Age discrimination among eruptives of Menengai Caldera, Kenya, using vegetation parameters from satellite imagery

NASA Technical Reports Server (NTRS)

Blodget, Herbert W.; Heirtzler, James R.

1993-01-01

Results are presented of an investigation to determine the degree to which digitally processed Landsat TM imagery can be used to discriminate among vegetated lava flows of different ages in the Menengai Caldera, Kenya. A selective series of five images, consisting of a color-coded Landsat 5 classification and four color composites, are compared with geologic maps. The most recent of more than 70 postcaldera flows within the caldera are trachytes, which are variably covered by shrubs and subsidiary grasses. Soil development evolves as a function of time, and as such supports a changing plant community. Progressively older flows exhibit the increasing dominance of grasses over bushes. The Landsat images correlated well with geologic maps, but the two mapped age classes could be further subdivided on the basis of different vegetation communities. It is concluded that field maps can be modified, and in some cases corrected by use of such imagery, and that digitally enhanced Landsat imagery can be a useful aid to field mapping in similar terrains.

Free flux flow: a probe into the field dependence of vortex core size in clean single crystals

NASA Astrophysics Data System (ADS)

Gapud, A. A.; Gafarov, O.; Moraes, S.; Thompson, J. R.; Christen, D. K.; Reyes, A. P.

2012-02-01

The free-flux-flow (FFF) phase has been attained successfully in a number of clean, weak-pinning, low-anisotropy, low-Tc, single-crystal samples as a unique probe into type II superconductivity that is independent of composition. The ``clean'' quality of the samples have been confirmed by reversible magnetization, high residual resistivity ratio, and low critical current densities Jc with a re-entrant ``peak'' effect in Jc(H) just below the critical field Hc2. The necessity of high current densities presented technical challenges that had been successfully addressed, and FFF is confirmed by a field-dependent ohmic state that is also well below the normal state. In these studies, the FFF resistivity ρf(H) has been measured in order to observe the field-dependent core size of the quantized magnetic flux vortices as modeled recently by Kogan and Zelezhina (KZ) who predicted a specific deviation from Bardeen-Stephen flux flow, dependent on normalized temperature and scattering parameter λ. The compounds studied are: V3Si, LuNi2B2C, and NbSe2, and results have shown consistency with the KZ model. Other applications of this method could also be used to probe normal-state properties, especially for the new iron arsenides, as will be discussed.

Study of magnetized accretion flow with variable Γ equation of state

NASA Astrophysics Data System (ADS)

Singh, Kuldeep; Chattopadhyay, Indranil

2018-05-01

We present here the solutions of magnetized accretion flow on to a compact object with hard surface such as neutron stars. The magnetic field of the central star is assumed dipolar and the magnetic axis is assumed to be aligned with the rotation axis of the star. We have used an equation of state for the accreting fluid in which the adiabatic index is dependent on temperature and composition of the flow. We have also included cooling processes like bremsstrahlung and cyclotron processes in the accretion flow. We found all possible accretion solutions. All accretion solutions terminate with a shock very near to the star surface and the height of this primary shock does not vary much with either the spin period or the Bernoulli parameter of the flow, although the strength of the shock may vary with the period. For moderately rotating central star, there is possible formation of multiple sonic points in the flow and therefore, a second shock far away from the star surface may also form. However, the second shock is much weaker than the primary one near the surface. We found that if rotation period is below a certain value (P*), then multiple critical points or multiple shocks are not possible and P* depends upon the composition of the flow. We also found that cooling effect dominates after the shock and that the cyclotron and the bremsstrahlung cooling processes should be considered to obtain a consistent accretion solution.

Local Discontinuous Galerkin (LDG) Method for Advection of Active Compositional Fields with Discontinuous Boundaries: Demonstration and Comparison with Other Methods in the Mantle Convection Code ASPECT

NASA Astrophysics Data System (ADS)

He, Y.; Billen, M. I.; Puckett, E. G.

2015-12-01

Flow in the Earth's mantle is driven by thermo-chemical convection in which the properties and geochemical signatures of rocks vary depending on their origin and composition. For example, tectonic plates are composed of compositionally-distinct layers of crust, residual lithosphere and fertile mantle, while in the lower-most mantle there are large compositionally distinct "piles" with thinner lenses of different material. Therefore, tracking of active or passive fields with distinct compositional, geochemical or rheologic properties is important for incorporating physical realism into mantle convection simulations, and for investigating the long term mixing properties of the mantle. The difficulty in numerically advecting fields arises because they are non-diffusive and have sharp boundaries, and therefore require different methods than usually used for temperature. Previous methods for tracking fields include the marker-chain, tracer particle, and field-correction (e.g., the Lenardic Filter) methods: each of these has different advantages or disadvantages, trading off computational speed with accuracy in tracking feature boundaries. Here we present a method for modeling active fields in mantle dynamics simulations using a new solver implemented in the deal.II package that underlies the ASPECT software. The new solver for the advection-diffusion equation uses a Local Discontinuous Galerkin (LDG) algorithm, which combines features of both finite element and finite volume methods, and is particularly suitable for problems with a dominant first-order term and discontinuities. Furthermore, we have applied a post-processing technique to insure that the solution satisfies a global maximum/minimum. One potential drawback for the LDG method is that the total number of degrees of freedom is larger than the finite element method. To demonstrate the capabilities of this new method we present results for two benchmarks used previously: a falling cube with distinct buoyancy and viscosity, and a Rayleigh-Taylor instability of a compositionally buoyant layer. To evaluate the trade-offs in computational speed and solution accuracy we present results for these same benchmarks using the two field tracking methods available in ASPECT: active tracer particles and the entropy viscosity method.

Organic matter composition of soil macropore surfaces under different agricultural management practices

NASA Astrophysics Data System (ADS)

Glæsner, Nadia; Leue, Marin; Magid, Jacob; Gerke, Horst H.

2016-04-01

Understanding the heterogeneous nature of soil, i.e. properties and processes occurring specifically at local scales is essential for best managing our soil resources for agricultural production. Examination of intact soil structures in order to obtain an increased understanding of how soil systems operate from small to large scale represents a large gap within soil science research. Dissolved chemicals, nutrients and particles are transported through the disturbed plow layer of agricultural soil, where after flow through the lower soil layers occur by preferential flow via macropores. Rapid movement of water through macropores limit the contact between the preferentially moving water and the surrounding soil matrix, therefore contact and exchange of solutes in the water is largely restricted to the surface area of the macropores. Organomineral complex coated surfaces control sorption and exchange properties of solutes, as well as availability of essential nutrients to plant roots and to the preferentially flowing water. DRIFT (Diffuse Reflectance infrared Fourier Transform) Mapping has been developed to examine composition of organic matter coated macropores. In this study macropore surfaces structures will be determined for organic matter composition using DRIFT from a long-term field experiment on waste application to agricultural soil (CRUCIAL, close to Copenhagen, Denmark). Parcels with 5 treatments; accelerated household waste, accelerated sewage sludge, accelerated cattle manure, NPK and unfertilized, will be examined in order to study whether agricultural management have an impact on the organic matter composition of intact structures.

Phreatic explosions during basaltic fissure eruptions: Kings Bowl lava field, Snake River Plain, USA

NASA Astrophysics Data System (ADS)

Hughes, Scott S.; Kobs Nawotniak, Shannon E.; Sears, Derek W. G.; Borg, Christian; Garry, William Brent; Christiansen, Eric H.; Haberle, Christopher W.; Lim, Darlene S. S.; Heldmann, Jennifer L.

2018-02-01

Physical and compositional measurements are made at the 7 km-long ( 2200 years B.P.) Kings Bowl basaltic fissure system and surrounding lava field in order to further understand the interaction of fissure-fed lavas with phreatic explosive events. These assessments are intended to elucidate the cause and potential for hazards associated with phreatic phases that occur during basaltic fissure eruptions. In the present paper we focus on a general understanding of the geological history of the site. We utilize geospatial analysis of lava surfaces, lithologic and geochemical signatures of lava flows and explosively ejected blocks, and surveys via ground observation and remote sensing. Lithologic and geochemical signatures readily distinguish between Kings Bowl and underlying pre-Kings Bowl lava flows, both of which comprise phreatic ejecta from the Kings Bowl fissure. These basalt types, as well as neighboring lava flows from the contemporaneous Wapi lava field and the older Inferno Chasm vent and outflow channel, fall compositionally within the framework of eastern Snake River Plain olivine tholeiites. Total volume of lava in the Kings Bowl field is estimated to be 0.0125 km3, compared to a previous estimate of 0.005 km3. The main (central) lava lake lost a total of 0.0018 km3 of magma by either drain-back into the fissure system or breakout flows from breached levees. Phreatic explosions along the Kings Bowl fissure system occurred after magma supply was cut off, leading to fissure evacuation, and were triggered by magma withdrawal. The fissure system produced multiple phreatic explosions and the main pit is accompanied by others that occur as subordinate pits and linear blast corridors along the fissure. The drop in magma supply and the concomitant influx of groundwater were necessary processes that led to the formation of Kings Bowl and other pits along the fissure. A conceptual model is presented that has relevance to the broader range of low-volume, monogenetic basaltic fissure eruptions on Earth, the Moon and other planetary bodies.

The Effect of Debris-Flow Composition on Runout Distance

NASA Astrophysics Data System (ADS)

Haas, T. D.; Braat, L.; Leuven, J.; Lokhorst, I.; Kleinhans, M. G.

2014-12-01

Estimating runout distance is of major importance for the assessment and mitigation of debris-flow hazards. Debris-flow runout distance depends on debris-flow composition and topography, but state-of-the-art runout prediction methods are mainly based on topographical parameters and debris-flow volume, while composition is generally neglected or incorporated in empirical constants. Here we experimentally investigated the effect of debris-flow composition and topography on runout distance. We created the first small-scale experimental debris flows with self-formed levees, distinct lobes and morphology and texture accurately resembling natural debris flows. In general, debris-flow composition had a larger effect on runout distance than topography. Enhancing channel slope and width, outflow plain slope, debris-flow size and water fraction leads to an increase in runout distance. However, runout distance shows an optimum relation with coarse-material and clay fraction. An increase in coarse-material fraction leads to larger runout distances by increased grain collisional forces and more effective levee formation, but too much coarse debris causes a large accumulation of coarse debris at the flow front, enhancing friction and decreasing runout. An increase in clay fraction initially enlarges the volume and viscosity of the interstitial fluid, liquefying the flow and enhancing runout, while a further increase leads to very viscous flows with high yield strength, reducing runout. These results highlight the importance and further need of research on the relation between debris-flow composition and runout distance. Our experiments further provide valuable insight on the effects of debris-flow composition on depositional mechanisms and deposit morphology.

The effect of debris-flow composition on runout distance

NASA Astrophysics Data System (ADS)

de Haas, Tjalling; Braat, Lisanne; Leuven, Jasper; Lokhorst, Ivar; Kleinhans, Maarten

2015-04-01

Estimating runout distance is of major importance for the assessment and mitigation of debris-flow hazards. Debris-flow runout distance depends on debris-flow composition and topography, but state-of-the-art runout prediction methods are mainly based on topographical parameters and debris-flow volume, while composition is generally neglected or incorporated in empirical constants. Here we experimentally investigated the effect of debris-flow composition and topography on runout distance. We created the first small-scale experimental debris flows with self-formed levees, distinct lobes and morphology and texture accurately resembling natural debris flows. In general, the effect of debris-flow composition on runout distance was larger than the effect of topography. Enhancing channel slope and width, outflow plain slope, debris-flow size and water fraction leads to an increase in runout distance. However, runout distance shows an optimum relation with coarse-material and clay fraction. An increase in coarse-material fraction leads to larger runout distances by increased grain collisional forces and more effective levee formation, but too much coarse debris causes a large accumulation of coarse debris at the flow front, enhancing friction and decreasing runout. An increase in clay fraction initially enlarges the volume and viscosity of the interstitial fluid, liquefying the flow and enhancing runout, while a further increase leads to very viscous flows with high yield strength, reducing runout. These results highlight the importance and further need of research on the relation between debris-flow composition and runout distance. Our experiments further provide valuable insight on the effects of debris-flow composition on depositional mechanisms and deposit morphology.

Imaging flow cytometry for phytoplankton analysis.

PubMed

Dashkova, Veronika; Malashenkov, Dmitry; Poulton, Nicole; Vorobjev, Ivan; Barteneva, Natasha S

2017-01-01

This review highlights the concepts and instrumentation of imaging flow cytometry technology and in particular its use for phytoplankton analysis. Imaging flow cytometry, a hybrid technology combining speed and statistical capabilities of flow cytometry with imaging features of microscopy, is rapidly advancing as a cell imaging platform that overcomes many of the limitations of current techniques and contributed significantly to the advancement of phytoplankton analysis in recent years. This review presents the various instrumentation relevant to the field and currently used for assessment of complex phytoplankton communities' composition and abundance, size structure determination, biovolume estimation, detection of harmful algal bloom species, evaluation of viability and metabolic activity and other applications. Also we present our data on viability and metabolic assessment of Aphanizomenon sp. cyanobacteria using Imagestream X Mark II imaging cytometer. Herein, we highlight the immense potential of imaging flow cytometry for microalgal research, but also discuss limitations and future developments. Copyright © 2016 Elsevier Inc. All rights reserved.

A field guide to Newberry Volcano, Oregon

USGS Publications Warehouse

Jenson, Robert A.; Donnelly-Nolan, Julie M.; McKay, Daniele

2009-01-01

Newberry Volcano is located in central Oregon at the intersection of the Cascade Range and the High Lava Plains. Its lavas range in age from ca. 0.5 Ma to late Holocene. Erupted products range in composition from basalt through rhyolite and cover ~3000 km2. The most recent caldera-forming eruption occurred ~80,000 years ago. This trip will highlight a revised understanding of the volcano's history based on new detailed geologic work. Stops will also focus on evidence for ice and flooding on the volcano, as well as new studies of Holocene mafic eruptions. Newberry is one of the most accessible U.S. volcanoes, and this trip will visit a range of lava types and compositions including tholeiitic and calc-alkaline basalt flows, cinder cones, and rhyolitic domes and tuffs. Stops will include early distal basalts as well as the youngest intracaldera obsidian flow.

Fabrication and flow characterization of vertically aligned carbon-nanotube/polymer membranes

NASA Astrophysics Data System (ADS)

Castellano, Richard; Meshot, Eric; Fornasiero, Francesco; Shan, Jerry

2017-11-01

Membranes with well-controlled nanopores are of interest for applications as diverse as chemical separations, water purification, and ``green'' power generation. In particular, membranes incorporating carbon nanotubes (CNTs) as through-pores have been shown to pass fluids at rates orders-of-magnitude faster than predicted by continuum theory. However, cost-effective and scalable solutions for fabricating such membranes are still an area of research. We describe a solution-based fabrication technique for creating polymer composite membranes from bulk nanotubes using electric-field alignment and electrophoretic concentration. We then focus on flow characterization of membranes with single-wall nanotube (SWNT) pores. We demonstrate membrane quality by size-exclusion testing and showing that the flowrate of different gasses scales as the square root of molecular weight. The gas flowrates and moisture-vapor-transmission rates are compared with theoretical predictions and with composite membranes -fabricated from CVD-grown SWNT arrays. Funded by DTRA Grant BA12PHM123.

Diverse Eruptions at Approximately 2,200 Years B.P. on the Great Rift, Idaho: Inferences for Magma Dynamics Along Volcanic Rift Zones

NASA Technical Reports Server (NTRS)

Hughes, S. S.; Nawotniak, S. E. Kobs; Borg, C.; Mallonee, H. C.; Purcell, S.; Neish, C.; Garry, W. B.; Haberle, C. W.; Lim, D. S. S.; Heldmann, J. L.

2016-01-01

Compositionally and morphologically diverse lava flows erupted on the Great Rift of Idaho approximately 2.2 ka (kilo-annum, 1000 years ago) during a volcanic "flare-up" of activity following an approximately 2 ky (kiloyear, 1000 years) hiatus in eruptions. Volcanism at Craters of the Moon (COTM), Wapi and Kings Bowl lava fields around this time included primitive and evolved compositions, separated over 75 kilometers along the approximately 85 kilometers-long rift, with striking variability in lava flow emplacement mechanisms and surface morphologies. Although the temporal associations may be coincidental, the system provides a planetary analog to better understand magma dynamics along rift systems, including that associated with lunar floor-fractured craters. This study aims to help bridge the knowledge gap between ancient rift volcanism evident on the Moon and other terrestrial planets, and active rift volcanism, e.g., at Hawai'i and Iceland.

The drive for Aircraft Energy Efficiency

NASA Technical Reports Server (NTRS)

James, R. L., Jr.; Maddalon, D. V.

1984-01-01

NASA's Aircraft Energy Efficiency (ACEE) program, which began in 1976, has mounted a development effort in four major transport aircraft technology fields: laminar flow systems, advanced aerodynamics, flight controls, and composite structures. ACEE has explored two basic methods for achieving drag-reducing boundary layer laminarization: the use of suction through the wing structure (via slots or perforations) to remove boundary layer turbulence, and the encouragement of natural laminar flow maintenance through refined design practices. Wind tunnel tests have been conducted for wide bodied aircraft equipped with high aspect ratio supercritical wings and winglets. Maneuver load control and pitch-active stability augmentation control systems reduce fuel consumption by reducing the drag associated with high aircraft stability margins. Composite structures yield lighter airframes that in turn call for smaller wing and empennage areas, reducing induced drag for a given payload. In combination, all four areas of development are expected to yield a fuel consumption reduction of 40 percent.

Production of microscale particles from fish bone by gas flow assisted laser ablation

NASA Astrophysics Data System (ADS)

Boutinguiza, M.; Lusquiños, F.; Comesaña, R.; Riveiro, A.; Quintero, F.; Pou, J.

2007-12-01

Recycled wastes from fish and seafood can constitute a source of precursor material for different applications in the biomedical field such as bone fillers or precursor material for bioceramic coatings to improve the osteointegration of metallic implants. In this work, fish bones have been used directly as target in a laser ablation system. A pulsed Nd:YAG laser was used to ablate the fish bone material and a transverse air flow was used to extract the ablated material out of the interaction zone. The particles collected at a filter were in the micro and nanoscale range. The morphology as well as the composition of the obtained particles were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). The results reveal that the composition of the analyzed particles is similar to that of the inorganic part of the fish bone.

Scaling Relations for Viscous and Gravitational Flow Instabilities in Multiphase Multicomponent Compressible Flow

NASA Astrophysics Data System (ADS)

Moortgat, J.; Amooie, M. A.; Soltanian, M. R.

2016-12-01

Problems in hydrogeology and hydrocarbon reservoirs generally involve the transport of solutes in a single solvent phase (e.g., contaminants or dissolved injection gas), or the flow of multiple phases that may or may not exchange mass (e.g., brine, NAPL, oil, gas). Often, flow is viscously and gravitationally unstable due to mobility and density contrasts within a phase or between phases. Such instabilities have been studied in detail for single-phase incompressible fluids and for two-phase immiscible flow, but to a lesser extent for multiphase multicomponent compressible flow. The latter is the subject of this presentation. Robust phase stability analyses and phase split calculations, based on equations of state, determine the mass exchange between phases and the resulting phase behavior, i.e., phase densities, viscosities, and volumes. Higher-order finite element methods and fine grids are used to capture the small-scale onset of flow instabilities. A full matrix of composition dependent coefficients is considered for each Fickian diffusive phase flux. Formation heterogeneity can have a profound impact and is represented by realistic geostatistical models. Qualitatively, fingering in multiphase compositional flow is different from single-phase problems because 1) phase mobilities depend on rock wettability through relative permeabilities, and 2) the initial density and viscosity ratios between phases may change due to species transfer. To quantify mixing rates in different flow regimes and for varying degrees of miscibility and medium heterogeneities, we define the spatial variance, scalar dissipation rate, dilution index, skewness, and kurtosis of the molar density of introduced species. Molar densities, unlike compositions, include compressibility effects. The temporal evolution of these measures shows that, while transport at the small-scale (cm) is described by the classical advection-diffusion-dispersion relations, scaling at the macro-scale (> 10 m) shows transitions between advective, diffusive, ballistic, sub-diffusive, and non-Fickian diffusive behavior. These scaling relations can be used to improve the predictive powers of field-scale reservoir simulations that cannot resolve the complexities of unstable flow and transport at cm-m scales.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammond, Glenn Edward; Yang, Xiaofan; Song, Xuehang

The groundwater-surface water interaction zone (GSIZ) plays an important role in riverine and watershed ecosystems as the exchange of waters of variable composition and temperature (hydrologic exchange flows) stimulate microbial activity and associated biogeochemical reactions. Variable temporal and spatial scales of hydrologic exchange flows, heterogeneity of the subsurface environment, and complexity of biogeochemical reaction networks in the GSIZ present challenges to incorporation of fundamental process representations and model parameterization across a range of spatial scales (e.g. from pore-scale to field scale). This paper presents a novel hybrid multiscale simulation approach that couples hydrologic-biogeochemical (HBGC) processes between two distinct length scalesmore » of interest.« less

Automated storm water sampling on small watersheds

USGS Publications Warehouse

Harmel, R.D.; King, K.W.; Slade, R.M.

2003-01-01

Few guidelines are currently available to assist in designing appropriate automated storm water sampling strategies for small watersheds. Therefore, guidance is needed to develop strategies that achieve an appropriate balance between accurate characterization of storm water quality and loads and limitations of budget, equipment, and personnel. In this article, we explore the important sampling strategy components (minimum flow threshold, sampling interval, and discrete versus composite sampling) and project-specific considerations (sampling goal, sampling and analysis resources, and watershed characteristics) based on personal experiences and pertinent field and analytical studies. These components and considerations are important in achieving the balance between sampling goals and limitations because they determine how and when samples are taken and the potential sampling error. Several general recommendations are made, including: setting low minimum flow thresholds, using flow-interval or variable time-interval sampling, and using composite sampling to limit the number of samples collected. Guidelines are presented to aid in selection of an appropriate sampling strategy based on user's project-specific considerations. Our experiences suggest these recommendations should allow implementation of a successful sampling strategy for most small watershed sampling projects with common sampling goals.

Transport of pollution to a remote coastal site during gap flow from California's interior: impacts on aerosol composition, clouds, and radiative balance

NASA Astrophysics Data System (ADS)

Martin, Andrew C.; Cornwell, Gavin C.; Atwood, Samuel A.; Moore, Kathryn A.; Rothfuss, Nicholas E.; Taylor, Hans; DeMott, Paul J.; Kreidenweis, Sonia M.; Petters, Markus D.; Prather, Kimberly A.

2017-01-01

During the CalWater 2015 field campaign, ground-level observations of aerosol size, concentration, chemical composition, and cloud activity were made at Bodega Bay, CA, on the remote California coast. A strong anthropogenic influence on air quality, aerosol physicochemical properties, and cloud activity was observed at Bodega Bay during periods with special weather conditions, known as Petaluma Gap flow, in which air from California's interior is transported to the coast. This study applies a diverse set of chemical, cloud microphysical, and meteorological measurements to the Petaluma Gap flow phenomenon for the first time. It is demonstrated that the sudden and often dramatic change in aerosol properties is strongly related to regional meteorology and anthropogenically influenced chemical processes in California's Central Valley. In addition, it is demonstrated that the change in air mass properties from those typical of a remote marine environment to properties of a continental regime has the potential to impact atmospheric radiative balance and cloud formation in ways that must be accounted for in regional climate simulations.

Downhole measurements and fluid chemistry of a castle rock steam well, the Geysers, Lake County, California

USGS Publications Warehouse

Truesdell, A.H.; Nathenson, M.; Frye, G.A.

1981-01-01

Wellbore and reservoir processes in a steam well in the Castle Rock field of The Geysers have been studied by means of down-hole pressure and temperature measurements and analyses of ejected water and steam produced under bleed and full flow. Down-hole measurements show that below a vapor zone there is liquid water in the well in pressure equilibrium with reservoir steam at a depth of 2290 m. The progressive decreases, from 1973 to 1977, of pressure and temperature in the vapor zone indicate that wellbore heat loss is high enough to condense a large fraction of the steam inflow. The chemical composition of water ejected from the well is consistent with an origin from wellbore condensation of steam. Calculations using the differences in gas and isotopic compositions between bleed and full-flow steam show that about half of the full-flow steam originated as liquid water in the reservoir and that about 30% of the steam entering the well under bleed was condensed in the wellbore and drained downward. Heat loss calculations are also consistent with this amount of condensation. ?? 1981.

UV-driven microvalve based on a micro-nano TiO₂/SiO₂ composite surface for microscale flow control.

PubMed

Guo, Ting; Meng, Tao; Li, Wei; Qin, Jilong; Tong, Zhiping; Zhang, Qing; Li, Xueru

2014-03-28

This paper presents a novel ultraviolet (UV)-driven microvalve based on the concept of inserting a trimethyl chlorosilane (CTMS) modified TiO₂/SiO₂ composite patch of switchable wettability in a microfluidic system. A unique micro-nano hierarchical structure was designed and used to enhance the overall wetting contrast with the aim of improving the wetting-based valve performances. Field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and chemical composition of the surface. UV-driven wettability conversion on the patched microchannel was investigated using water column relative height tests, and the results confirmed the significant improvement of the hierarchical structure with the surface hydrophobic/hydrophilic conversion, which produced enhancements of 276% and 95% of the water-repellent and water-sucking pressures, respectively, compared with those of the single-scale TiO₂ nanopatterned structure. Accordingly, a good reversible and repeated on-off performance was identified by the valve tests, highlighting the potential application of the novel microvalve in the efficient control of microscale flow.

UV-driven microvalve based on a micro-nano TiO2/SiO2 composite surface for microscale flow control

NASA Astrophysics Data System (ADS)

Guo, Ting; Meng, Tao; Li, Wei; Qin, Jilong; Tong, Zhiping; Zhang, Qing; Li, Xueru

2014-03-01

This paper presents a novel ultraviolet (UV)-driven microvalve based on the concept of inserting a trimethyl chlorosilane (CTMS) modified TiO2/SiO2 composite patch of switchable wettability in a microfluidic system. A unique micro-nano hierarchical structure was designed and used to enhance the overall wetting contrast with the aim of improving the wetting-based valve performances. Field-emission scanning electron microscopy (FE-SEM) and x-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and chemical composition of the surface. UV-driven wettability conversion on the patched microchannel was investigated using water column relative height tests, and the results confirmed the significant improvement of the hierarchical structure with the surface hydrophobic/hydrophilic conversion, which produced enhancements of 276% and 95% of the water-repellent and water-sucking pressures, respectively, compared with those of the single-scale TiO2 nanopatterned structure. Accordingly, a good reversible and repeated on-off performance was identified by the valve tests, highlighting the potential application of the novel microvalve in the efficient control of microscale flow.

Planar Rayleigh scattering and laser-induced fluorescence for visualization of a hot, Mach 2 annular air jet

NASA Technical Reports Server (NTRS)

Balla, R. Jeffrey

1994-01-01

Planar Rayleigh scattering (PRS) and planar laser-induced fluorescence (PLIF) were used to investigate the vitiated air component of a coaxial hydrogen/vitiated air nonpremixed turbulent jet flame that is ejected at a Mach number of 2. All experiments were performed with a xenon chloride tunable excimer laser. Planar information for both techniques was obtained using laser sheets 6 cm high, 5 cm wide, and 300 micron thick. In this flow field, the effective Rayleigh cross section of the components in the vitiated air was assumed to be independent of composition. Therefore, the PRS technique produced signals which were proportional to total density. When the flow field was assumed to be at a known and uniform pressure, the PRS signal data for the vitiated air could be converted to temperature information. Also, PLIF images were generated by probing the OH molecule. These images contain striation patterns attributed to small localized instantaneous temperature nonuniformities. The results from the PLIF and PRS techniques were used to show that this flow field contains a nongaseous component, most likely liquid water that can be reduced by increasing the settling chamber wall temperature.

One-step analysis of DNA/chitosan complexes by field-flow fractionation reveals particle size and free chitosan content.

PubMed

Ma, Pei Lian; Buschmann, Michael D; Winnik, Françoise M

2010-03-08

The composition of samples obtained upon complexation of DNA with chitosan was analyzed by asymmetrical flow field flow fractionation (AF4) with online UV-visible, multiangle light scattering (MALS), and dynamic light scattering (DLS) detectors. A chitosan labeled with rhodamine B to facilitate UV-vis detection of the polycation was complexed with DNA under conditions commonly used for transfection (chitosan glucosamine to DNA phosphate molar ratio of 5). AF4 analysis revealed that 73% of the chitosan-rhodamine remained free in the dispersion and that the DNA/chitosan complexes had a broad size distribution ranging from 20 to 160 nm in hydrodynamic radius. The accuracy of the data was assessed by comparison with data from batch-mode DLS and scanning electron microscopy. The AF4 combined with DLS allowed the characterization of small particles that were not detected by conventional batch-mode DLS. The AF4 analysis will prove to be an important tool in the field of gene therapy because it readily provides, in a single measurement, three important physicochemical parameters of the complexes: the amount of unbound polycation, the hydrodynamic size of the complexes, and their size distribution.

High-Latitude Paleomagnetic and Ar-Ar Study of 0 - 6 MA Lavas from Eastern Iceland: Contribution to the Time-Averaged Field Initiative

NASA Astrophysics Data System (ADS)

Døssing, A.; Muxworthy, A. R.; Mac Niocaill, C.; Riishuus, M. S.

2013-12-01

Statistical analyses of paleomagnetic data from sequential lava flows allow us to study the geomagnetic field behavior on kyr to Myr timescales. Previous paleomagnetic studies have lacked high-latitude, high-quality measurements and resolution necessary to investigate the persistence of high-latitude geomagnetic field anomalies observed in the recent and historical field records, and replicated in some numerical geodynamo simulations. As part of the Time-Averaged Field Initiative (TAFI) project, the lava sequences found in Nordurdalur (by Fljótsdalur) and Jökuldalur in eastern Iceland provide an excellent opportunity to improve high-latitude data suitable for investigating the 0-5 Ma TAF and paleosecular variation. These adjacent valleys, separated by 40 km, are known to comprise a fairly continuous record of lava flows erupted from the Northern Rift Zone between 0.5 and 5-7 Ma. During a five weeks field campaign in summer 2013, we collected a total of ~1900 cores (10-16 cores/site; mean = ~13 cores/site) from ~140 separate lava flows (165 in total) along eight stratigraphic profiles in Nordurdalur and Jökuldalur. In addition, hand samples were collected from ~70 sites to deliver ~40 new 40Ar/39Ar radiometric age measurements. We present a preliminary composite magnetostratigraphic interpretation of the exposed volcanic pile in Nordurdalur and Jökuldalur. The new data will be compared and contrasted with previously published paleomagnetic and geochronological results. In addition, determinations of the anisotropy of the magnetic susceptibility of individual lava flows is sought to deliver fossil lava flow directions. The aim of the study is ultimately to present a high-quality study of paleomagnetic directions and intensities from Iceland spanning the past 6-7 Myr. The new Fjlotsdalur and Jökuldalur data will be combined with previously published paleomagnetic results.

3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant L. Hawkes; James E. O'Brien; Greg Tao

2011-11-01

A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified formore » this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, operating potential, steam-electrode gas composition, oxygen-electrode gas composition, current density and hydrogen production over a range of stack operating conditions. Single-cell and five-cell results will be presented. Flow distribution through both models is discussed. Flow enters from the bottom, distributes through the inlet plenum, flows across the cells, gathers in the outlet plenum and flows downward making an upside-down ''U'' shaped flow pattern. Flow and concentration variations exist downstream of the inlet holes. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, oxygen-electrode and steam-electrode current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicate the effects of heat transfer, reaction cooling/heating, and change in local gas composition. Results are discussed for using this design in the electrolysis mode. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.« less

Effect of processing on Polymer/Composite structure and properties

NASA Technical Reports Server (NTRS)

1982-01-01

Advances in the vitality and economic health of the field of polymer forecasting are discussed. A consistent and rational point of view which considers processing as a participant in the underlying triad of relationships which comprise materials science and engineering is outlined. This triad includes processing as it influences material structure, and ultimately properties. Methods in processing structure properties, polymer science and engineering, polymer chemistry and synthesis, structure and modification and optimization through processing, and methods of melt flow modeling in processing structure property relations of polymer were developed. Mechanical properties of composites are considered, and biomedical materials research to include polymer processing effects are studied. An analysis of the design technology of advances graphite/epoxy composites is also reported.

Probing Dynamic Processes in Explosives and Propellants - Science Issues

NASA Astrophysics Data System (ADS)

Moore, David

2017-06-01

Recent experiments on advanced light sources have started to unravel some of the micromechanical behavior of single crystal energetic materials, including void collapse under shock loading and inter-granular failure. These examples just scratch the surface of many extant explosives science issues, which could be elucidated with advanced XFEL-type resources. These include such diverse questions as: How do powders actually compact and what are the spatially and temporally resolved temperature and flow fields generated (especially two-phase flows)? Are there polymorphic effects (if so, how are they spatially distributed)? What are the strain fields during compaction? What happens near surfaces, especially for composite explosives? How is mechanics coupled to chemistry? What are hot spots really? I will provide some history behind these and other questions and point towards how future experiments might be designed to provide some answers.

DISCRIMINATION OF ALTERED BASALTIC ROCKS IN THE SOUTHWESTERN UNITED STATES BY ANALYSIS OF LANDSAT THEMATIC MAPPER DATA.

USGS Publications Warehouse

Davis, Philip A.; Berlin, Graydon L.; Chavez, Pat S.

1987-01-01

Landsat Thematic Mapper image data were analyzed to determine their ability to discriminate red cone basalts from gray flow basalts and sedimentary country rocks for three volcanic fields in the southwestern United States. Analyses of all of the possible three-band combinations of the six nonthermal bands indicate that the combination of bands 1, 4, and 5 best discriminates among these materials. The color-composite image of these three bands unambiguously discriminates 89 percent of the mapped red volcanic cones in the three volcanic fields. Mineralogic and chemical analyses of collected samples indicate that discrimination is facilitated by the presence of hematite as a major mineral phase in the red cone basalts (hematite is only a minor mineral phase in the gray flow basalts and red sedimentary rocks).

The debris-flow rheology myth

USGS Publications Warehouse

Iverson, R.M.; ,

2003-01-01

Models that employ a fixed rheology cannot yield accurate interpretations or predictions of debris-flow motion, because the evolving behavior of debris flows is too complex to be represented by any rheological equation that uniquely relates stress and strain rate. Field observations and experimental data indicate that debris behavior can vary from nearly rigid to highly fluid as a consequence of temporal and spatial variations in pore-fluid pressure and mixture agitation. Moreover, behavior can vary if debris composition changes as a result of grain-size segregation and gain or loss of solid and fluid constituents in transit. An alternative to fixed-rheology models is provided by a Coulomb mixture theory model, which can represent variable interactions of solid and fluid constituents in heterogeneous debris-flow surges with high-friction, coarse-grained heads and low-friction, liquefied tails. ?? 2003 Millpress.

Plasma Methods of Obtainment of Multifunctional Composite Materials, Dispersion-Hardened by Nanoparticles

NASA Astrophysics Data System (ADS)

Sizonenko, O. N.; Grigoryev, E. G.; Pristash, N. S.; Zaichenko, A. D.; Torpakov, A. S.; Lypian, Ye. V.; Tregub, V. A.; Zholnin, A. G.; Yudin, A. V.; Kovalenko, A. A.

2017-09-01

High voltage electric discharge (HVED) in disperse system "hydrocarbon liquid - powder" due to impact of plasma discharge channel, electromagnetic fields, shock waves mechanical impact, hydro flows and volume microcavitation leads to synthesis of nanocarbon, metal powders dispersion and synthesis of micro- (from 10-6 to 10-7 m) and nanosized (from 10-7 to 10-9 m) composite powders of hardening phases. Spark plasma sintering (SPS) of powder mixtures allows targeted control of grain growth rate and thus allows obtainment of multifunctional composite materials dispersion hardened by nanoparticles. Processes of HVED synthesis of micro- and nanosized powders of new compositions from elemental metal powders and their mixtures with the subsequent application of high-speed SPS of obtained powders create conditions for increase of strength (by 10-20 %), hardness and wear-resistance (by 30-60 %) of obtained materials.

Dynamics and viscosity of `a'a and pahoehoe lava flows of the 2012-2013 eruption of Tolbachik volcano, Kamchatka (Russia)

NASA Astrophysics Data System (ADS)

Belousov, Alexander; Belousova, Marina

2018-01-01

The 2012-2013 flank eruption of Tolbachik volcano (Kamchatka) lasted 9 months and produced 0.54 km3 of basaltic trachyandesite lava, thus becoming one of the most voluminous historical lava effusions of basic composition in subduction-related environments globally. From March to July 2013, the volcano monotonously erupted lava of constant composition (SiO2 = 52 wt%) with a nearly stable effusion rate of 18 m3/s. Despite the uniform eruptive and emplacement conditions, the dominant style of lava propagation throughout that time gradually changed from `a'a to pahoehoe. We report results of instrumental field measurements of the `a'a and pahoehoe flow dynamics (documented with time-lapse cameras) as well as the lava viscosity determined by flow rate and shear stress (using penetrometer) methods. Maximal propagation velocities of the `a'a fronts ranged from 2 to 25 mm/s, and those of the pahoehoe from 0.5 to 6 mm/s. The flow front velocities of both lava types experienced short-period fluctuations that were caused by complex flow mechanics of the advancing flow lobes. Minimal viscosities of lava of the `a'a lobes ranged from 1.3 × 105 to 3.3 × 107 Pa s (flow rate method), and those of the pahoehoe from to 5 × 103 to 5 × 104 Pa s (shear stress method). Our data include the first ever measured profiles of viscosity through the entire thickness of actively advancing pahoehoe lava lobes. We have found that both the `a'a and pahoehoe flows were fed by identical parental lava, which then developed contrasting rheological properties, owing to differences in the process of lava transport over the ground surface. The observed transition from the dominant `a'a to the dominant pahoehoe propagation styles occurred due to gradual elongation and branching of the lava tube system throughout the course of the eruption. Such evolution became possible because the growing lava field, composed of semisolidified flows, provided an environment for shallow subsurface intrusions and internal migrations of lava that, with time, developed into branches of the lava tube system. Based on our data, we propose phenomenological models of the `a'a and pahoehoe flow mechanics.

A theoretical study of the global F region for June solstice, solar maximum, and low magnetic activity

NASA Technical Reports Server (NTRS)

Sojka, J. J.; Schunk, R. W.

1985-01-01

A time-dependent, three-dimensional, multi-ion model of the ionospheric F region at 120-800 km altitude is presented. Account is taken of field-aligned diffusion, cross-field electrodynamic drifts in equatorial and high latitude regions, interhemispheric flow, thermospheric winds, polar wind escape, energy-dependent chemical reactions and neutral composition changes. Attention is also given to the effects of ion production by solar EUV radiation and auroral precipitation, thermal conduction, diffusion-thermal heat flow, local heating and cooling processes, offsets between the geomagnetic and geographic poles, and bending of field lines near the magnetic equator. The model incorporates all phenomena described by previous models and can be applied to tracing magnetic storm and substorm disturbances from high to low latitudes on a global scale. Sample results are provided for ionospheric features during a June solstice, the solar maximum and in a period of low geomagnetic activity. The model will eventually be used to study coupled ionosphere-thermosphere activity.

Fred's Flow (Canada) and Murphy Well (Australia): thick komatiitic lava flows with contrasting compositions, emplacement mechanisms and water contents

NASA Astrophysics Data System (ADS)

Siégel, Coralie; Arndt, Nicholas; Barnes, Stephen; Henriot, Anne-Laure; Haenecour, Pierre; Debaille, Vinciane; Mattielli, Nadine

2014-12-01

Two Archaean komatiitic flows, Fred's Flow in Canada and the Murphy Well Flow in Australia, have similar thicknesses (120 and 160 m) but very different compositions and internal structures. Their contrasting differentiation profiles are keys to determine the cooling and crystallization mechanisms that operated during the eruption of Archaean ultramafic lavas. Fred's Flow is the type example of a thick komatiitic basalt flow. It is strongly differentiated and consists of a succession of layers with contrasting textures and compositions. The layering is readily explained by the accumulation of olivine and pyroxene in a lower cumulate layer and by evolution of the liquid composition during downward growth of spinifex-textured rocks within the upper crust. The magmas that erupted to form Fred's Flow had variable compositions, ranging from 12 to 20 wt% MgO, and phenocryst contents from 0 to 20 vol%. The flow was emplaced by two pulses. A first ~20-m-thick pulse was followed by another more voluminous but less magnesian pulse that inflated the flow to its present 120 m thickness. Following the second pulse, the flow crystallized in a closed system and differentiated into cumulates containing 30-38 wt% MgO and a residual gabbroic layer with only 6 wt% MgO. The Murphy Well Flow, in contrast, has a remarkably uniform composition throughout. It comprises a 20-m-thick upper layer of fine-grained dendritic olivine and 2-5 vol% amygdales, a 110-120 m intermediate layer of olivine porphyry and a 20-30 m basal layer of olivine orthocumulate. Throughout the flow, MgO contents vary little, from only 30 to 33 wt%, except for the slightly more magnesian basal layer (38-40 wt%). The uniform composition of the flow and dendritic olivine habits in the upper 20 m point to rapid cooling of a highly magnesian liquid with a composition like that of the bulk of the flow. Under equilibrium conditions, this liquid should have crystallized olivine with the composition Fo94.9, but the most magnesian composition measured by electron microprobe in samples from the flow is Fo92.9. To explain these features, we propose that the parental liquid contained around 32 wt% MgO and 3 wt% H2O. This liquid degassed during the eruption, creating a supercooled liquid that solidified quickly and crystallized olivine with non-equilibrium textures and compositions.

Behaviour of tetraalkylammonium ions in high-field asymmetric waveform ion mobility spectrometry.

PubMed

Aksenov, Alexander A; Kapron, James T

2010-05-30

High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an ion-filtering technique recently adapted for use with liquid chromatography/mass spectrometry (LC/MS) to remove interferences during analysis of complex matrices. This is the first systematic study of a series of singly charged tetraalkylammonium ions by FAIMS-MS. The compensation voltage (CV) is the DC offset of the waveform which permits the ion to emerge from FAIMS and it was determined for each member of the series under various conditions. The electrospray ionization conditions explored included spray voltage, vaporizer temperature, and sheath and auxiliary gas pressure. The FAIMS conditions explored included carrier gas flow rate, electrode temperature and composition of the carrier gas. Optimum desolvation was achieved using sufficient carrier gas (flow rate > or = 2 L/min) to ensure stable response. Low-mass ions (m/z 100-200) are more susceptible to changes in electrode temperature and gas composition than high mass ions (m/z 200-700). As a result of this study, ions are reliably analyzed using standard FAIMS conditions (dispersion voltage -5000 V, carrier gas flow rate 3 L/min, 50% helium/50%nitrogen, inner electrode temperature 70 degrees C and outer electrode temperature 90 degrees C). Variation of FAIMS conditions may be of great use for the separation of very low mass tetraalkylammonium (TAA) ions from other TAA ions. The FAIMS conditions do not appear to have a major effect on higher mass ions. Copyright 2010 John Wiley & Sons, Ltd.

Physico-mechanical and thermal characteristics of commercially available and newly developed dental flowable composites

NASA Astrophysics Data System (ADS)

Kamalak, Hakan; Canbay, C. Aksu; Yiğit, Oktay; Altin, Serdar

2018-03-01

In this study, we investigated the structural stability, thermal conductivity, thermal analysis, materials' homogeneity of newly developed flowable composites. 6 different dental flowable composite resins; Grandio Flow (GF), Charisma Flow (CF), Tetric N Flow (TNF), Clearfil Majesty Flow (CMF),3M Filtek Ultimate Flow (3MFU), Voco Amaris Flow (VFA) were used. Restorations were made in standard teflon molds and the materials were light-cured for 20s in a 6 mm × 2 mm teflon mould. After polymerization, samples were kept in distilled water at 37 °C/24 h .It was found that the composites have multiphase component such as metallic dopant and organic binder. The XRD investigation showed that there was a broad halo in the pattern which indicates the organic section in the composites. The FTIR results indicate the bond structure of the composites. The temperature dependence of the thermal conductivity of the composites were found below to 5 mW/K value depending on the type of the composites, which are low enough for dental application. The micro-hardness of the samples was analyzed and the result was compared.

Effect of flow rate on environmental variables and phytoplankton dynamics: results from field enclosures

NASA Astrophysics Data System (ADS)

Zhang, Haiping; Chen, Ruihong; Li, Feipeng; Chen, Ling

2015-03-01

To investigate the effects of flow rate on phytoplankton dynamics and related environment variables, a set of enclosure experiments with different flow rates were conducted in an artificial lake. We monitored nutrients, temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll- a and phytoplankton levels. The lower biomass in all flowing enclosures showed that flow rate significantly inhibited the growth of phytoplankton. A critical flow rate occurred near 0.06 m/s, which was the lowest relative inhibitory rate. Changes in flow conditions affected algal competition for light, resulting in a dramatic shift in phytoplankton composition, from blue-green algae in still waters to green algae in flowing conditions. These findings indicate that critical flow rate can be useful in developing methods to reduce algal bloom occurrence. However, flow rate significantly enhanced the inter-relationships among environmental variables, in particular by inducing higher water turbidity and vegetative reproduction of periphyton ( Spirogyra). These changes were accompanied by a decrease in underwater light intensity, which consequently inhibited the photosynthetic intensity of phytoplankton. These results warn that a universal critical flow rate might not exist, because the effect of flow rate on phytoplankton is interlinked with many other environmental variables.

Effects of debris flow composition on runout, depositional mechanisms, and deposit morphology in laboratory experiments

NASA Astrophysics Data System (ADS)

Haas, Tjalling; Braat, Lisanne; Leuven, Jasper R. F. W.; Lokhorst, Ivar R.; Kleinhans, Maarten G.

2015-09-01

Predicting debris flow runout is of major importance for hazard mitigation. Apart from topography and volume, runout distance and area depends on debris flow composition and rheology, but how is poorly understood. We experimentally investigated effects of composition on debris flow runout, depositional mechanisms, and deposit geometry. The small-scale experimental debris flows were largely similar to natural debris flows in terms of flow behavior, deposit morphology, grain size sorting, channel width-depth ratio, and runout. Deposit geometry (lobe thickness and width) in our experimental debris flows is largely determined by composition, while the effects of initial conditions of topography (i.e., outflow plain slope and channel slope and width) and volume are negligible. We find a clear optimum in the relations of runout with coarse-material fraction and clay fraction. Increasing coarse-material concentration leads to larger runout. However, excess coarse material results in a large accumulation of coarse debris at the flow front and enhances diffusivity, increasing frontal friction and decreasing runout. Increasing clay content initially enhances runout, but too much clay leads to very viscous flows, reducing runout. Runout increases with channel slope and width, outflow plain slope, debris flow volume, and water fraction. These results imply that debris flow runout depends at least as much on composition as on topography. This study improves understanding of the effects of debris flow composition on runout and may aid future debris flow hazard assessments.

Investigating the Structures of Turbulence in a Multi-Stream, Rectangular, Supersonic Jet

NASA Astrophysics Data System (ADS)

Magstadt, Andrew S.

Supersonic flight has become a standard for military aircraft, and is being seriously reconsidered for commercial applications. Engine technologies, enabling increased mission capabilities and vehicle performance, have evolved nozzles into complex geometries with intricate flow features. These engineering solutions have advanced at a faster rate than the understanding of the flow physics, however. The full consequences of the flow are thus not known, and using predictive tools becomes exceedingly difficult. Additionally, the increasing velocities associated with supersonic flight exacerbate the preexisting jet noise problem, which has troubled the engineering community for nearly 65 years. Even in the simplest flows, the full consequences of turbulence, e.g. noise production, are not fully understood. For composite flows, the fluid mechanics and acoustic properties have been studied even less sufficiently. Before considering the aeroacoustic problem, the development, structure, and evolution of the turbulent flow-field must be considered. This has prompted an investigation into the compressible flow of a complex nozzle. Experimental evidence is sought to explain the stochastic processes of the turbulent flow issuing from a complex geometry. Before considering the more complicated configuration, an experimental campaign of an axisymmetric jet is conducted. The results from this study are presented, and guide research of the primary flow under investigation. The design of a nozzle representative of future engine technologies is then discussed. Characteristics of this multi-stream rectangular supersonic nozzle are studied via time-resolved schlieren imaging, stereo PIV measurements, dynamic pressure transducers, and far-field acoustics. Experiments are carried out in the anechoic chamber at Syracuse University, and focus primarily on the flow-field. An extensive data set is generated, which reveals a detailed view of a very complex flow. Shear, shock waves, unequal entrainment, compressibility, and geometric features of the nozzle heavily influence the development of this jet plume. In the far-field, the acoustic radiation is found to be highly directional. Noise spectra contain high-frequency tonal signatures, and relations to the turbulent structures are made in an effort to explain the physics responsible for such acoustic generation. Analysis of the flow is made possible by the carefully planned experiments. By acquiring a large number of simultaneous data points, the stochastic processes are studied through statistical approaches. First- and second-order moments are used to describe the steady-state behavior of the flow. The wide array of sensors used in the tests allows for cross-moments to be computed, which provide evidence linking different phenomena. Proper orthogonal decomposition (POD) is used to separate flow-field quantities into temporal and spatial pieces, which are then further utilized in conjunction with other sensors. Through these methods, a high-frequency instability is discovered in the near-field of the jet, which pervades the flow-field and propagates ubiquitously throughout the acoustic domain. Additionally, the complex shock structure is found to play a vital role in redistributing disturbances throughout the flow. Finally, several POD modes in the side shear layer of the jet are found to be correlated with acoustic production.

A porous flow model for the geometrical form of volcanoes - Critical comments

NASA Technical Reports Server (NTRS)

Wadge, G.; Francis, P.

1982-01-01

A critical evaluation is presented of the assumptions on which the mathematical model for the geometrical form of a volcano arising from the flow of magma in a porous medium of Lacey et al. (1981) is based. The lack of evidence for an equipotential surface or its equivalent in volcanoes prior to eruption is pointed out, and the preference of volcanic eruptions for low ground is attributed to the local stress field produced by topographic loading rather than a rising magma table. Other difficulties with the model involve the neglect of the surface flow of lava under gravity away from the vent, and the use of the Dupuit approximation for unconfined flow and the assumption of essentially horizontal magma flow. Comparisons of model predictions with the shapes of actual volcanoes reveal the model not to fit lava shield volcanoes, for which the cone represents the solidification of small lava flows, and to provide a poor fit to composite central volcanoes.

Magmatic inclusions in rhyolites, contaminated basalts, and compositional zonation beneath the Coso volcanic field, California

USGS Publications Warehouse

Bacon, C.R.; Metz, J.

1984-01-01

Basaltic lava flows and high-silica rhyolite domes form the Pleistocene part of the Coso volcanic field in southeastern California. The distribution of vents maps the areal zonation inferred for the upper parts of the Coso magmatic system. Subalkalic basalts (<50% SiO2) were erupted well away from the rhyolite field at any given time. Compositional variation among these basalts can be ascribed to crystal fractionation. Erupted volumes of these basalts decrease with increasing differentiation. Mafic lavas containing up to 58% SiO2, erupted adjacent to the rhyolite field, formed by mixing of basaltic and silicic magma. Basaltic magma interacted with crustal rocks to form other SiO2-rich mafic lavas erupted near the Sierra Nevada fault zone. Several rhyolite domes in the Coso volcanic field contain sparse andesitic inclusions (55-61% SiO2). Pillow-like forms, intricate commingling and local diffusive mixing of andesite and rhyolite at contacts, concentric vesicle distribution, and crystal morphologies indicative of undercooling show that inclusions were incorporated in their rhyolitic hosts as blobs of magma. Inclusions were probably dispersed throughout small volumes of rhyolitic magma by convective (mechanical) mixing. Inclusion magma was formed by mixing (hybridization) at the interface between basaltic and rhyolitic magmas that coexisted in vertically zoned igneous systems. Relict phenocrysts and the bulk compositions of inclusions suggest that silicic endmembers were less differentiated than erupted high-silica rhyolite. Changes in inferred endmembers of magma mixtures with time suggest that the steepness of chemical gradients near the silicic/mafic interface in the zoned reservoir may have decreased as the system matured, although a high-silica rhyolitic cap persisted. The Coso example is an extreme case of large thermal and compositional contrast between inclusion and host magmas; lesser differences between intermediate composition magmas and inclusions lead to undercooling phenomena that suggest smaller ??T. Vertical compositional zonation in magma chambers has been documented through study of products of voluminous pyroclastic eruptions. Magmatic inclusions in volcanic rocks provide evidence for compositional zonation and mixing processes in igneous systems when only lava is erupted. ?? 1984 Springer-Verlag.

Analysis of Two-Phase Flow in Damper Seals for Cryogenic Turbopumps

NASA Technical Reports Server (NTRS)

Arauz, Grigory L.; SanAndres, Luis

1996-01-01

Cryogenic damper seals operating close to the liquid-vapor region (near the critical point or slightly su-cooled) are likely to present two-phase flow conditions. Under single phase flow conditions the mechanical energy conveyed to the fluid increases its temperature and causes a phase change when the fluid temperature reaches the saturation value. A bulk-flow analysis for the prediction of the dynamic force response of damper seals operating under two-phase conditions is presented as: all-liquid, liquid-vapor, and all-vapor, i.e. a 'continuous vaporization' model. The two phase region is considered as a homogeneous saturated mixture in thermodynamic equilibrium. Th flow in each region is described by continuity, momentum and energy transport equations. The interdependency of fluid temperatures and pressure in the two-phase region (saturated mixture) does not allow the use of an energy equation in terms of fluid temperature. Instead, the energy transport is expressed in terms of fluid enthalpy. Temperature in the single phase regions, or mixture composition in the two phase region are determined based on the fluid enthalpy. The flow is also regarded as adiabatic since the large axial velocities typical of the seal application determine small levels of heat conduction to the walls as compared to the heat carried by fluid advection. Static and dynamic force characteristics for the seal are obtained from a perturbation analysis of the governing equations. The solution expressed in terms of zeroth and first order fields provide the static (leakage, torque, velocity, pressure, temperature, and mixture composition fields) and dynamic (rotordynamic force coefficients) seal parameters. Theoretical predictions show good agreement with experimental leakage pressure profiles, available from a Nitrogen at cryogenic temperatures. Force coefficient predictions for two phase flow conditions show significant fluid compressibility effects, particularly for mixtures with low mass content of vapor. Under these conditions, an increase on direct stiffness and reduction of whirl frequency ratio are shown to occur. Prediction of such important effects will motivate experimental studies as well as a more judicious selection of the operating conditions for seals used in cryogenic turbomachinery.

Prediction of Tensile Behavior of UHSFRC Considering the Flow Field in the Placing Dominated by Shear Flow.

PubMed

Moon, Joon-Shik; Kang, Su-Tae

2018-01-26

Considering the case of fabricating a UHSFRC (ultra-high strength fiber-reinforced concrete) beam with the method of one end placing and self-flowing to the other end, it was intended to simulate the variation of the fiber orientation distribution according to the flow distance and the variation of the resultant tensile behaviors. Then the validity of the simulation approach was shown by comparing the simulated results with experimental ones. A three-point bending test with a notched beam was adopted for the experiment and a finite element analysis was performed to obtain the simulated results for the bending test considering the flow-dependent tensile behavior of the UHSFRC. From the simulation for the fiber orientation distribution according to the flow distance, it could be found that the major change in the fiber orientation distribution took place within a short flow distance and most of the fibers became nearly aligned to the flow direction. After some flow distance, there was a not-so-remarkable variation in the fiber orientation distribution that could influence the tensile behavior of the composite. For this flow region, the consistent flexural test results, regardless of flow distance, demonstrate the reliability of the simulation.

Fred's Flow (Canada) and Murphy Well (Australia): thick komatiitic lava flows with contrasting compositions, emplacement mechanisms and water contents

NASA Astrophysics Data System (ADS)

Siégel, C.; Arndt, N. T.; Henriot, A.-L.; Barnes, S. J.

2012-04-01

Two Archaean komatiitic flows, Fred's Flow in Canada and the Murphy Well flow in Australia, have similar thicknesses (120 m and 160 m) but very different compositions and internal structures. Fred's Flow is the type example of a thick komatiitic basaltic flow. It is strongly differentiated and consists of a succession of layers with contrasting textures and compositions. The layering is readily explained by the accumulation of olivine and pyroxene in a lower cumulate layer and by evolution of the liquid composition during downward growth of spinifex-textured rocks within the upper crust. A parental liquid was constrained to contain ca. 18 wt% MgO and ca. 5 to 35%vol phenocrysts and it differentiated into cumulates containing 45 wt% MgO and a residual gabbroic layer with only 6 wt% MgO. The Murphy Well flow, in contrast, has a remarkably uniform composition throughout. It comprises two layers, a 20-m-thick upper layer composed of fine-grained dendritic olivine and 2-10% amygdales, a 120-m-thick lower layer of olivine porphyry, and a lowermost 20 m of olivine orthocumulate. Throughout the flow, MgO contents vary little, from only 30 to 34 wt%, except for the slightly more magnesian basal layer (35-40 wt%). The uniform composition and dendritic olivine habits suggest rapid cooling of a highly magnesian liquid with a composition like that of the bulk of the flow. Under equilibrium conditions this liquid should have crystallized olivine with the composition Fo95.5 but the most magnesian composition measured by electron microprobe in samples from the flow is Fo93. To explain these features, we propose that the original liquid was hydrous and contained around 32% MgO. It degassed during eruption creating a supercooled liquid that solidified quickly and crystallized olivine with non-equilibrium compositions. To account for the 60-70vol% olivine throughout the flow requires a combination of degassing and cooling by the evacuation of heat in the escaping fluid.

Petrologic evolution of divergent peralkaline magmas from the Silent Canyon caldera complex, southwestern Nevada volcanic field

USGS Publications Warehouse

Sawyer, D.A.; Sargent, K.A.

1989-01-01

The Silent Canyon volcanic center consists of a buried Miocene peralkaline caldera complex and outlying peralkaline lava domes. Two widespread ash flow sheets, the Tub Spring and overlying Grouse Canyon members of the Miocene Belted Range Tuff, were erupted from the caldera complex and have volumes of 60-100 km3 and 200 km3, respectively. Eruption of the ash flows was preceded by widespread extrusion of precaldera comendite domes and was followed by extrusion of postcollapse peralkaline lavas and tuffs within and outside the caldera complex. Lava flows and tuffs were also deposited between the two major ash flow sheets. Rocks of the Silent Canyon center vary significantly in silica content and peralkalinity. Weakly peralkaline silicic comendites (PI 1.0-1.1) are the most abundant precaldera lavas. Postcollapse lavas range from trachyte to silicic comendite; some have anomalous light rare earth element (LREE) enrichments. Silent Canyon rocks follow a common petrologic evolution from trachyte to low-silica comendite; above 73% SiO2, compositions of the moderately peralkaline comendites diverge from those of the weakly peralkaline silicic comendites. The development of divergent peralkaline magmas, toward both pantelleritic and weakly peralkaline compositions, is unusual in a single volcanic center. -from Authors

Visible-Light Upconversion Carbon Quantum Dots Decorated TiO2 for the Photodegradation of Flowing Gaseous Acetaldehyde

NASA Astrophysics Data System (ADS)

Hu, Yidan; Xie, Xiaofeng; Wang, Xiao; Wang, Yan; Zeng, Yi; Pui, David Y. H.; Sun, Jing

2018-05-01

Carbon-modified photocatalyst has attracted extensive attentions in the field of gaseous pollutant removal, mainly due to the improved adsorption properties and electronic transport of carbon matrix, such as carbon nanotubes, graphene, and fullerene, etc. In this work, carbon quantum dots (CQDs) were employed to enhance the photocatalytic performance of TiO2-based composites for flowing gaseous acetaldehyde removal. Besides the aforementioned advantages of carbon materials, the unique up-converted photoluminescence property of CQDs is capable of extending the optical absorption to visible-light range. Moreover, the electron spin resonance (ESR) results firstly verified a stable existence of Ti3+ defect in the CQDs/TiO2 composite, which is possibly induced by the electron migration from CQDs to TiO2. And the formed Ti3+ donor energy level in the band gap could further help with the visible-light harvesting. During the photodegradation experiments, with two-hour continuous flowing gaseous acetaldehyde injection (500 ppm, 20 sccm), the CQDs/TiO2 composite remained 99% removal efficiency under fluorescent lamp irradiation (λ > 380 nm). The optimized CQDs content was obtained as 3 wt%, and the underlying mechanism was further analyzed by temperature programmed desorption (TPD) methods. This work will push forward the air purification researches by providing new insights of CQDs sensitized photocatalyst.

Noninvasive characterization of a flowing multiphase fluid using ultrasonic interferometry

DOEpatents

Sinha, Dipen N.

2003-11-11

An apparatus for noninvasively monitoring the flow and/or the composition of a flowing liquid using ultrasound is described. The position of the resonance peaks for a fluid excited by a swept-frequency ultrasonic signal have been found to change frequency both in response to a change in composition and in response to a change in the flow velocity thereof. Additionally, the distance between successive resonance peaks does not change as a function of flow, but rather in response to a change in composition. Thus, a measurement of both parameters (resonance position and resonance spacing), once calibrated, permits the simultaneous determination of flow rate and composition using the apparatus and method of the present invention.

Non-Invasive Characterization Of A Flowing Multi-Phase Fluid Using Ultrasonic Interferometry

DOEpatents

Sinha, Dipen N.

2005-11-01

An apparatus for noninvasively monitoring the flow and/or the composition of a flowing liquid using ultrasound is described. The position of the resonance peaks for a fluid excited by a swept-frequency ultrasonic signal have been found to change frequency both in response to a change in composition and in response to a change in the flow velocity thereof. Additionally, the distance between successive resonance peaks does not change as a function of flow, but rather in response to a change in composition. Thus, a measurement of both parameters (resonance position and resonance spacing), once calibrated, permits the simultaneous determination of flow rate and composition using the apparatus and method of the present invention.

Noninvasive Characterization Of A Flowing Multiphase Fluid Using Ultrasonic Interferometry

DOEpatents

Sinha, Dipen N.

2005-05-10

An apparatus for noninvasively monitoring the flow and/or the composition of a flowing liquid using ultrasound is described. The position of the resonance peaks for a fluid excited by a swept-frequency ultrasonic signal have been found to change frequency both in response to a change in composition and in response to a change in the flow velocity thereof. Additionally, the distance between successive resonance peaks does not change as a function of flow, but rather in response to a change in composition. Thus, a measurement of both parameters (resonance position and resonance spacing), once calibrated, permits the simultaneous determination of flow rate and composition using the apparatus and method of the present invention.

Noninvasive characterization of a flowing multiphase fluid using ultrasonic interferometry

DOEpatents

Sinha, Dipen N [Los Alamos, NM

2007-06-12

An apparatus for noninvasively monitoring the flow and/or the composition of a flowing liquid using ultrasound is described. The position of the resonance peaks for a fluid excited by a swept-frequency ultrasonic signal have been found to change frequency both in response to a change in composition and in response to a change in the flow velocity thereof. Additionally, the distance between successive resonance peaks does not change as a function of flow, but rather in response to a change in composition. Thus, a measurement of both parameters (resonance position and resonance spacing), once calibrated, permits the simultaneous determination of flow rate and composition using the apparatus and method of the present invention.

Aerothermo-Structural Analysis of Low Cost Composite Nozzle/Inlet Components

NASA Technical Reports Server (NTRS)

Shivakumar, Kuwigai; Challa, Preeli; Sree, Dave; Reddy, D.

1999-01-01

This research is a cooperative effort among the Turbomachinery and Propulsion Division of NASA Glenn, CCMR of NC A&T State University, and the Tuskegee University. The NC A&T is the lead center and Tuskegee University is the participating institution. Objectives of the research were to develop an integrated aerodynamic, thermal and structural analysis code for design of aircraft engine components, such as, nozzles and inlets made of textile composites; conduct design studies on typical inlets for hypersonic transportation vehicles and setup standards test examples and finally manufacture a scaled down composite inlet. These objectives are accomplished through the following seven tasks: (1) identify the relevant public domain codes for all three types of analysis; (2) evaluate the codes for the accuracy of results and computational efficiency; (3) develop aero-thermal and thermal structural mapping algorithms; (4) integrate all the codes into one single code; (5) write a graphical user interface to improve the user friendliness of the code; (6) conduct test studies for rocket based combined-cycle engine inlet; and finally (7) fabricate a demonstration inlet model using textile preform composites. Tasks one, two and six are being pursued. Selected and evaluated NPARC for flow field analysis, CSTEM for in-depth thermal analysis of inlets and nozzles and FRAC3D for stress analysis. These codes have been independently verified for accuracy and performance. In addition, graphical user interface based on micromechanics analysis for laminated as well as textile composites was developed. Demonstration of this code will be made at the conference. A rocket based combined cycle engine was selected for test studies. Flow field analysis of various inlet geometries were studied. Integration of codes is being continued. The codes developed are being applied to a candidate example of trailblazer engine proposed for space transportation. A successful development of the code will provide a simpler, faster and user-friendly tool for conducting design studies of aircraft and spacecraft engines, applicable in high speed civil transport and space missions.

Understanding of changes in river flow using recently collected field and observational data from Russian Arctic

NASA Astrophysics Data System (ADS)

Shiklomanov, A. I.; Tokarev, I. V.; Davydov, S. P.; Davydova, A.; Streletskiy, D. A.

2017-12-01

There is substantial evidence supporting increasing river runoff in the Eurasian pan-Arctic, but the causes of these changes are not well understood. To determine the contributions of various water sources to river runoff generation in small streams and large rivers located in the continuous permafrost zone, an extensive field campaign was carried out near the town of Cherskii, Russia. Measurements of hydrometeorological characteristics, as well as stable isotope composition and hydrochemistry of precipitation, river flow and ground ice, were obtained during the 2013-2016 period. When combined with older data (2005-2009), the isotopic composition of atmospheric precipitation showed a general trend towards heavier winter precipitation, attributed mainly to observed increases in winter air temperature. Samples of water and ground ice from several boreholes showed that isotopic compositions of water from the active layer, transient layer and permafrost are significantly different. Thus, stable isotopes can be used to assess contributions of different soil layers to stream flow generation. Increases in streamflow of small test watersheds were observed during dry periods in August-September. These increases were associated with considerable stable isotope depletion in streamflow samples, which is likely caused by thawing of the transient- and possibly upper permafrost layers. The absence of correlation between water and air temperature during these periods (R2 = 0.22 in August-September and R2 = 0.8 in June-July) also suggests an increasing contribution of thawing ground ice to the streamflow. To quantitatively assess the contribution of various water sources to the river runoff of Kolyma River, we used stable isotope data along with a physically based hydrological model developed at the University of New Hampshire. Preliminary results suggest that thawing permafrost increased August-September discharge in Kolyma near Cherskii by 8% in 2013, 11% in 2014 and 4% in 2015, even though none of these years was extremely warm or wet. We estimate that 5cm of permafrost thaw (with 30% ice content) over the entire Kolyma basin can contribute about 10 km3/year (or 10%) to annual discharge and significantly change the water regime during low-flow periods (fall-winter).

Laser-absorption sensing of gas composition of products from coal gasification

NASA Astrophysics Data System (ADS)

Jeffries, Jay B.; Sur, Ritobrata; Sun, Kai; Hanson, Ronald K.

2014-06-01

A prototype in-situ laser-absorption sensor for the real-time composition measurement (CO, CH4, H2O and CO2) of synthesis gas products of coal gasification (called here syngas) was designed, tested in the laboratory, and demonstrated during field-measurement campaigns in a pilot-scale entrained flow gasifier at the University of Utah and in an engineering-scale, fluidized-bed transport gasifier at the National Carbon Capture Center (NCCC). The prototype design and operation were improved by the lessons learned from each field test. Laser-absorption measurements are problematic in syngas flows because efficient gasifiers operate at elevated pressures (10-50 atm) where absorption transitions are collision broadened and absorption transitions that are isolated at 1 atm become blended into complex features, and because syngas product streams can contain significant particulate, producing significant non-absorption scattering losses of the transmission of laser light. Thus, the prototype sensor used a new wavelength-scanned, wavelength-modulation spectroscopy strategy with 2f-detection and 1f-normalization (WMS-2f/1f) that can provide sensitive absorption measurements of species with spectra blended by collision broadening even in the presence of large non-absorption laser transmission losses (e.g., particulate scattering, beam steering, etc.). The design of the sensor for detection of CO, CH4, H2O and CO2 was optimized for the specific application of syngas monitoring at the output of large-scale gasifiers. Sensor strategies, results and lessons learned from these field measurement campaigns are discussed.

Preliminary aerodynamic design considerations for advanced laminar flow aircraft configurations

NASA Technical Reports Server (NTRS)

Johnson, Joseph L., Jr.; Yip, Long P.; Jordan, Frank L., Jr.

1986-01-01

Modern composite manufacturing methods have provided the opportunity for smooth surfaces that can sustain large regions of natural laminar flow (NLF) boundary layer behavior and have stimulated interest in developing advanced NLF airfoils and improved aircraft designs. Some of the preliminary results obtained in exploratory research investigations on advanced aircraft configurations at the NASA Langley Research Center are discussed. Results of the initial studies have shown that the aerodynamic effects of configuration variables such as canard/wing arrangements, airfoils, and pusher-type and tractor-type propeller installations can be particularly significant at high angles of attack. Flow field interactions between aircraft components were shown to produce undesirable aerodynamic effects on a wing behind a heavily loaded canard, and the use of properly designed wing leading-edge modifications, such as a leading-edge droop, offset the undesirable aerodynamic effects by delaying wing stall and providing increased stall/spin resistance with minimum degradation of laminar flow behavior.

Bacterial growth, flow, and mixing shape human gut microbiota density and composition.

PubMed

Arnoldini, Markus; Cremer, Jonas; Hwa, Terence

2018-03-13

The human gut microbiota is highly dynamic, and host physiology and diet exert major influences on its composition. In our recent study, we integrated new quantitative measurements on bacterial growth physiology with a reanalysis of published data on human physiology to build a comprehensive modeling framework. This can generate predictions of how changes in different host factors influence microbiota composition. For instance, hydrodynamic forces in the colon, along with colonic water absorption that manifests as transit time, exert a major impact on microbiota density and composition. This can be mechanistically explained by their effect on colonic pH which directly affects microbiota competition for food. In this addendum, we describe the underlying analysis in more detail. In particular, we discuss the mixing dynamics of luminal content by wall contractions and its implications for bacterial growth and density, as well as the broader implications of our insights for the field of gut microbiota research.

Preparation of composite micro/nano structure on the silicon surface by reactive ion etching: Enhanced anti-reflective and hydrophobic properties

NASA Astrophysics Data System (ADS)

Zeng, Yu; Fan, Xiaoli; Chen, Jiajia; He, Siyu; Yi, Zao; Ye, Xin; Yi, Yougen

2018-05-01

A silicon substrate with micro-pyramid structure (black silicon) is prepared by wet chemical etching and then subjected to reactive ion etching (RIE) in the mixed gas condition of SF6, CHF3 and He. We systematically study the impacts of flow rates of SF6, CHF3 and He, the etching pressure and the etching time on the surface morphology and reflectivity through various characterizations. Meanwhile, we explore and obtain the optimal combination of parameters for the preparation of composite structure that match the RIE process based on the basis of micro-pyramid silicon substrate. The composite sample prepared under the optimum parameters exhibits excellent anti-reflective performance, hydrophobic, self-cleaning and anti-corrosive properties. Based on the above characteristics, the composite micro/nano structure can be applied to solar cells, photodetectors, LEDs, outdoor devices and other important fields.

An experimental study of reactive turbulent mixing

NASA Technical Reports Server (NTRS)

Cooper, L. P.; Marek, C. J.; Strehlow, R. A.

1977-01-01

An experimental study of two coaxial gas streams, which react very rapidly, was performed to investigate the mixing characteristics of turbulent flow fields. The center stream consisted of a CO-N2 mixture and the outer annular stream consisted of air vitiated by H2 combustion. The streams were at equal velocity (50 m/sec) and temperature (1280 K). Turbulence measurements were obtained using hot film anemometry. A sampling probe was used to obtain time averaged gas compositions. Six different turbulence generators were placed in the annular passage to alter the flow field mixing characteristics. The turbulence generators affected the bulk mixing of the streams and the extent of CO conversion to different degrees. The effects can be related to the average eddy size (integral scale) and the bulk mixing. Higher extents of conversion of CO to CO2 were found be increasing the bulk mixing and decreasing the average eddy size.

Achieving swift equilibration of a Brownian particle using flow-fields

NASA Astrophysics Data System (ADS)

Patra, Ayoti; Jarzynski, Christopher

Can a system be driven to a targeted equilibrium state on a timescale that is much shorter than its natural equilibration time? In a recent experiment, the swift equilibration of an overdamped Brownian particle was achieved by use of an appropriately designed, time-dependent optical trap potential. Motivated by these results, we develop a general theoretical approach for guiding an ensemble of Brownian particles to track the instantaneous equilibrium distribution of a desired potential U (q , t) . In our approach, we use flow-fields associated with the parametric evolution of the targeted equilibrium state to construct an auxiliary potential U (q , t) , such that dynamics under the composite potential U (t) + U (t) achieves the desired evolution. Our results establish a close connection between the swift equilibration of Brownian particles, quantum shortcuts to adiabaticity, and the dissipationless driving of a classical, Hamiltonian system.

Entanglement entropy and entanglement spectrum of Bi_1-xSb_x (111) bilayers.

PubMed

Brzezińska, Marta; Bieniek, Maciej; Woźniak, Tomasz; Potasz, Paweł; Wójs, Arkadiusz

2018-02-14

We study topological properties of Bi$_{1-x}$Sb$_{x}$ bilayers in the (111) plane using entanglement measures. Electronic structures are investigated within multi-orbital tight-binding model and structural stability is confirmed through first-principles calculations. Topologically non-trivial nature of bismuth bilayer is proved by the presence of spectral flow in the entanglement spectrum. We consider topological phase transitions driven by a composition change x, an applied external electric field in Bi bilayer and strain in Sb bilayer. Composition- and strain-induced phase transitions reveal a finite discontinuity in the entanglement entropy. This quantity remains a continuous function of the electric field strength, but shows a finite discontinuity in the first derivative. We relate the difference in behavior of the entanglement entropy to the breaking of inversion symmetry in the last case. © 2018 IOP Publishing Ltd.

Entanglement entropy and entanglement spectrum of Bi1-x Sb x (1 1 1) bilayers.

PubMed

Brzezińska, Marta; Bieniek, Maciej; Woźniak, Tomasz; Potasz, Paweł; Wójs, Arkadiusz

2018-02-28

We study topological properties of Bi 1-x Sb x bilayers in the (1 1 1) plane using entanglement measures. Electronic structures are investigated within multi-orbital tight-binding model and structural stability is confirmed through first-principles calculations. The topologically non-trivial nature of the bismuth bilayer is proved by the presence of spectral flow in the entanglement spectrum. We consider topological phase transitions driven by a composition change x, an applied external electric field in Bi bilayers and strain in Sb bilayers. Composition- and strain-induced phase transitions reveal a finite discontinuity in the entanglement entropy. This quantity remains a continuous function of the electric field strength, but shows a finite discontinuity in the first derivative. We relate the difference in behavior of the entanglement entropy to the breaking of inversion symmetry in the last case.

Entanglement entropy and entanglement spectrum of Bi1-x Sb x (1 1 1) bilayers

NASA Astrophysics Data System (ADS)

Brzezińska, Marta; Bieniek, Maciej; Woźniak, Tomasz; Potasz, Paweł; Wójs, Arkadiusz

2018-03-01

We study topological properties of Bi1-x Sb x bilayers in the (1 1 1) plane using entanglement measures. Electronic structures are investigated within multi-orbital tight-binding model and structural stability is confirmed through first-principles calculations. The topologically non-trivial nature of the bismuth bilayer is proved by the presence of spectral flow in the entanglement spectrum. We consider topological phase transitions driven by a composition change x, an applied external electric field in Bi bilayers and strain in Sb bilayers. Composition- and strain-induced phase transitions reveal a finite discontinuity in the entanglement entropy. This quantity remains a continuous function of the electric field strength, but shows a finite discontinuity in the first derivative. We relate the difference in behavior of the entanglement entropy to the breaking of inversion symmetry in the last case.

Asymmetrical flow field flow fractionation methods to characterize submicron particles: application to carbon-based aggregates and nanoplastics.

PubMed

Gigault, Julien; El Hadri, Hind; Reynaud, Stéphanie; Deniau, Elise; Grassl, Bruno

2017-11-01

In the last 10 years, asymmetrical flow field flow fractionation (AF4) has been one of the most promising approaches to characterize colloidal particles. Nevertheless, despite its potentialities, it is still considered a complex technique to set up, and the theory is difficult to apply for the characterization of complex samples containing submicron particles and nanoparticles. In the present work, we developed and propose a simple analytical strategy to rapidly determine the presence of several submicron populations in an unknown sample with one programmed AF4 method. To illustrate this method, we analyzed polystyrene particles and fullerene aggregates of size covering the whole colloidal size distribution. A global and fast AF4 method (method O) allowed us to screen the presence of particles with size ranging from 1 to 800 nm. By examination of the fractionating power F d , as proposed in the literature, convenient fractionation resolution was obtained for size ranging from 10 to 400 nm. The global F d values, as well as the steric inversion diameter, for the whole colloidal size distribution correspond to the predicted values obtained by model studies. On the basis of this method and without the channel components or mobile phase composition being changed, four isocratic subfraction methods were performed to achieve further high-resolution separation as a function of different size classes: 10-100 nm, 100-200 nm, 200-450 nm, and 450-800 nm in diameter. Finally, all the methods developed were applied in characterization of nanoplastics, which has received great attention in recent years. Graphical Absract Characterization of the nanoplastics by asymmetrical flow field flow fractionation within the colloidal size range.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, T.

1998-06-16

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell. 5 figs.

Electromagnetic valve for controlling the flow of molten, magnetic material

DOEpatents

Richter, Tomas

1998-01-01

An electromagnetic valve for controlling the flow of molten, magnetic material is provided, which comprises an induction coil for generating a magnetic field in response to an applied alternating electrical current, a housing, and a refractory composite nozzle. The nozzle is comprised of an inner sleeve composed of an erosion resistant refractory material (e.g., a zirconia ceramic) through which molten, magnetic metal flows, a refractory outer shell, and an intermediate compressible refractory material, e.g., unset, high alumina, thermosetting mortar. The compressible refractory material is sandwiched between the inner sleeve and outer shell, and absorbs differential expansion stresses that develop within the nozzle due to extreme thermal gradients. The sandwiched layer of compressible refractory material prevents destructive cracks from developing in the refractory outer shell.

Marine tephrochronology of the Mt. Edgecumbe volcanic field, southeast Alaska, USA

USGS Publications Warehouse

Addison, Jason A.; Beget, James E.; Ager, Thomas A.; Finney, Bruce P.

2010-01-01

The Mt. Edgecumbe Volcanic Field (MEVF), located on Kruzof Island near Sitka Sound in southeast Alaska, experienced a large multiple-stage eruption during the last glacial maximum (LGM)-Holocene transition that generated a regionally extensive series of compositionally similar rhyolite tephra horizons and a single well-dated dacite (MEd) tephra. Marine sediment cores collected from adjacent basins to the MEVF contain both tephra-fall and pyroclastic flow deposits that consist primarily of rhyolitic tephra and a minor dacitic tephra unit. The recovered dacite tephra correlates with the MEd tephra, whereas many of the rhyolitic tephras correlate with published MEVF rhyolites. Correlations were based on age constraints and major oxide compositions of glass shards. In addition to LGM-Holocene macroscopic tephra units, four marine cryptotephras were also identified. Three of these units appear to be derived from mid-Holocene MEVF activity, while the youngest cryptotephra corresponds well with the White River Ash eruption at not, vert, similar 1147 cal yr BP. Furthermore, the sedimentology of the Sitka Sound marine core EW0408-40JC and high-resolution SWATH bathymetry both suggest that extensive pyroclastic flow deposits associated with the activity that generated the MEd tephra underlie Sitka Sound, and that any future MEVF activity may pose significant risk to local population centers.

Fractionation of Poly(butyl methacrylate) by Molecular Topology Using Multidetector Thermal Field-Flow Fractionation.

PubMed

Greyling, Guilaume; Pasch, Harald

2015-12-01

Thermal field-flow fractionation (ThFFF) is an interesting alternative to column-based fractionation being able to address different molecular parameters including size and composition. Until today it has not been shown to be able to fractionate polymers of similar molar masses and chemical compositions by molecular topology. The present study demonstrates that poly(butyl methacrylates) with identical molar masses can be fractionated by ThFFF according to the topology of the butyl group. The influence of the solvent polarity on the thermal diffusion behavior of these polymers is presented and it is shown to have a significant influence on the fractionation of poly(n-butyl methacrylate) and poly(t-butyl methacrylate). Fractionation improves with increasing solvent polarity and solvent polarity may have a greater influence on fractionation than solvent viscosity. It is found that the thermal diffusion coefficient, D(T), as well as the hydrodynamic diameter, D(h), exhibit increasing trends with increasing solvent polarity. The solvent quality has a significant influence on the fractionation. It is found that cyclohexane, being a theta solvent for poly(t-butyl methacrylate) but not for poly(n-butyl methacrylate), significantly improves the fractionation of the samples by decreasing the diffusion rate of the former but not the latter. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of debris-flow composition on runout and erosion

NASA Astrophysics Data System (ADS)

Haas, T. D.; Kleinhans, M. G.

2016-12-01

Predicting debris-flow runout is of major importance for hazard mitigation. Apart from topography and volume, runout depends on debris-flow composition (i.e., particle-size distribution and water content), but how is poorly understood. Moreover, debris flows can grow greatly in size by entrainment of bed material, enhancing their volume and thereby runout and hazardous impact. Debris-flow erosion rates also depend on debris-flow composition, but the relation between the two is largely unexplored. Composition thus strongly affects the dynamics of debris flows. We experimentally investigate the effects of composition on debris-flow runout and erosion. We find a clear optimum in the relations of runout with coarse-material fraction and clay fraction. Increasing coarse material concentration leads to larger runout. However, excess coarse material results in a large accumulation of coarse debris at the flow front and enhances diffusivity, increasing frontal friction and decreasing runout. Increasing clay content initially enhances runout, but too much clay leads to very viscous flows, reducing runout. We further find that debris-flow runout depends at least as much on composition as on topography. In general, erosion depth increases with basal shear stress in our experiments, while there is no correlation with grain collisional stress. There are substantial differences in the scour caused by different types of debris flows. Mean and maximum erosion depths generally become larger with increasing water fraction and grain size and decrease with increasing clay content. However, the erodibility of the very coarse-grained experimental debris flows is unrelated to basal shear stress. This relates to the relatively large influence of grain-collisional stress to the total bed stress in these flows (30-50%). The relative effect of grain-collisional stress is low in the other experimental debris flows (<5%) causing erosion to be largely controlled by basal shear stress. These results show that the erosive behaviour of debris flows may change from basal-shear stress dominated to grain-collisional stress dominated in increasingly coarse-grained debris flows. In short, this study improves our understanding of the effects of debris-flow composition on runout and erosion.

High Dynamic Velocity Range Particle Image Velocimetry Using Multiple Pulse Separation Imaging

PubMed Central

Persoons, Tim; O’Donovan, Tadhg S.

2011-01-01

The dynamic velocity range of particle image velocimetry (PIV) is determined by the maximum and minimum resolvable particle displacement. Various techniques have extended the dynamic range, however flows with a wide velocity range (e.g., impinging jets) still challenge PIV algorithms. A new technique is presented to increase the dynamic velocity range by over an order of magnitude. The multiple pulse separation (MPS) technique (i) records series of double-frame exposures with different pulse separations, (ii) processes the fields using conventional multi-grid algorithms, and (iii) yields a composite velocity field with a locally optimized pulse separation. A robust criterion determines the local optimum pulse separation, accounting for correlation strength and measurement uncertainty. Validation experiments are performed in an impinging jet flow, using laser-Doppler velocimetry as reference measurement. The precision of mean flow and turbulence quantities is significantly improved compared to conventional PIV, due to the increase in dynamic range. In a wide range of applications, MPS PIV is a robust approach to increase the dynamic velocity range without restricting the vector evaluation methods. PMID:22346564

Bioimpedance measurements of human body composition: critical analysis and outlook.

PubMed

Matthie, James R

2008-03-01

Bioimpedance spectroscopy represents one of the largest emerging medical device technologies. The method is generally known as impedance spectroscopy and is an inexpensive, yet extremely powerful, analytical technique for studying the electrical properties of materials. Much of what we know about biological cells and tissues comes from use of this technique in vitro. Due to the high impedance of the cell membrane, current flow through the cell is frequency dependent and this allows the fluid volume inside versus outside the body's cells to be determined. The fluid outside the cells is primarily related to fluid volume status while the intracellular fluid also relates to the body's cellular mass. Technical advances have removed much of the method's basic complexities. The first commercial bioimpedance spectroscopy device for in vivo human body composition studies was introduced in 1990. Major strides have been made and the method is now poised to enter mainstream clinical medicine but the field is only in its infancy. This paper attempts to fully describe the current use of impedance in the body composition field.

Field electron emission from diamond and related films synthesized by plasma enhanced chemical vapor deposition

NASA Astrophysics Data System (ADS)

Lu, Xianfeng

The focus of this thesis is the study of the field electron emission (FEE) of diamond and related films synthesized by plasma enhanced chemical vapor deposition. The diamond and related films with different morphologies and compositions were prepared in a microwave plasma-enhanced chemical vapor deposition (CVD) reactor and a hot filament CVD reactor. Various analytical techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy were employed to characterize the surface morphology and chemical composition. The influence of surface morphology on the field electron emission property of diamond films was studied. The emission current of well-oriented microcrystalline diamond films is relatively small compared to that of randomly oriented microcrystalline diamond films. Meanwhile, the nanocrystalline diamond film has demonstrated a larger emission current than microcrystalline diamond films. The nanocone structure significantly improves the electron emission current of diamond films due to its strong field enhancement effect. The sp2 phase concentration also has significant influence on the field electron emission property of diamond films. For the diamond films synthesized by gas mixture of hydrogen and methane, their field electron emission properties were enhanced with the increase of methane concentration. The field electron emission enhancement was attributed to the increase of sp2 phase concentration, which increases the electrical conductivity of diamond films. For the diamond films synthesized through graphite etching, the growth rate and nucleation density of diamond films increase significantly with decreasing hydrogen flow rate. The field electron emission properties of the diamond films were also enhanced with the decrease of hydrogen flow rate. The field electron emission enhancement can be also attributed to the increase of the sp 2 phase concentration. In addition, the deviation of the experimental Fowler-Nordheim (F-N) plot from a straight line was observed for graphitic nanocone films. The deviation can be mainly attributed to the nonuniform field enhancement factor of the graphitic nanocones. In low macroscopic electric field regions, electrons are emitted mainly from nanocone or nanocones with the largest field enhancement factor, which corresponds to the smallest slope magnitude. With the increase of electric field, nanocones with small field enhancement factors also contribute to the emission current, which results in a reduced average field enhancement factor and therefore a large slope magnitude.

Table Mountain Shoshonite Porphyry Lava Flows and Their Vents, Golden, Colorado

USGS Publications Warehouse

Drewes, Harald

2008-01-01

During early Paleocene time shoshonite porphyry lava was extruded from several plugs about 5 km north of Golden, Colo., to form lava flows intercalated in the upper part of the Denver Formation. These flows now form the caps of North and South Table Mountains. Detailed field and petrographic studies provide insights into magma development, linkage between vents and flows, and the history of the lava flows. The magma was derived from a deep (mantle) source, was somewhat turbulent on its way up, paused on its way up in a shallow granite-hosted chamber, and near the surface followed the steep Golden fault and the thick, weak, steeply dipping Upper Cretaceous Pierre Shale. At the surface the lava flowed out of several plug and dike vents in a nonexplosive manner, four times during a span of about 1 m.y. Potassium-rich material acquired in the shallow chamber produced distinctive textures and mineral associations in the igneous rocks. Lava flows 1 (the lowest) and 2 are channel deposits derived from the southeastern group of intrusions, and flow 1 (a composite, multiple-tongued flow) lies about 50 m below the capping flows. Provisionally, the unit termed flow 1 is considered to include older, felty-textured flows that are distinguished from a blocky-textured unit, flow 1a. Flow 2, newly recognized in this study, lies immediately beneath the capping flows. Lava flows 3 and 4, more voluminous than the earlier ones, were derived from a plug vent 1?2 km farther north-northwest and flowed south-southeast across a broad alluvial plain. This plug is a composite body; the rim phase fed flow 3, and the core phase was the source of flow 4. During the time between the effusion of the four flows, the composition of the shoshonite porphyry magma changed subtly; the later flows contain more alkali, as shown by higher proportions of sanidine. On North Table Mountain, lava flows 3 and 4 form an elongate tumulus above a stream channel that carried water at the time of their eruption. On South Table Mountain, lava flow 3 forms a low, broad dome that forced flow 4 into channels now restricted to the west and northeast flanks of that mesa. Mesa-capping lava flows 3 and 4 are broken by many small normal faults and are warped into open synclines, probably in response to local stresses associated with the settling of piedmont deposits into the Denver Basin. Mid-Tertiary deposits are inferred to have covered the upper part of the Denver Formation and its lavas; these deposits could thus have been instrumental in changing the stream flow direction to the east before the onset of Neogene uplift and consequent canyon cutting across the flows. Other younger deposits may also have covered the area, to be linked to this consequent canyon cutting.

Challenges in the determination of the interstellar flow longitude from the pickup ion cutoff

NASA Astrophysics Data System (ADS)

Taut, A.; Berger, L.; Möbius, E.; Drews, C.; Heidrich-Meisner, V.; Keilbach, D.; Lee, M. A.; Wimmer-Schweingruber, R. F.

2018-03-01

Context. The interstellar flow longitude corresponds to the Sun's direction of movement relative to the local interstellar medium. Thus, it constitutes a fundamental parameter for our understanding of the heliosphere and, in particular, its interaction with its surroundings, which is currently investigated by the Interstellar Boundary EXplorer (IBEX). One possibility to derive this parameter is based on pickup ions (PUIs) that are former neutral ions that have been ionized in the inner heliosphere. The neutrals enter the heliosphere as an interstellar wind from the direction of the Sun's movement against the partially ionized interstellar medium. PUIs carry information about the spatial variation of their neutral parent population (density and flow vector field) in their velocity distribution function. From the symmetry of the longitudinal flow velocity distribution, the interstellar flow longitude can be derived. Aim. The aim of this paper is to identify and eliminate systematic errors that are connected to this approach of measuring the interstellar flow longitude; we want to minimize any systematic influences on the result of this analysis and give a reasonable estimate for the uncertainty. Methods: We use He+ data measured by the PLAsma and SupraThermal Ion Composition (PLASTIC) sensor on the Solar TErrestrial RElations Observatory Ahead (STEREO A) spacecraft. We analyze a recent approach, identify sources of systematic errors, and propose solutions to eliminate them. Furthermore, a method is introduced to estimate the error associated with this approach. Additionally, we investigate how the selection of interplanetary magnetic field angles, which is closely connected to the pickup ion velocity distribution function, affects the result for the interstellar flow longitude. Results: We find that the revised analysis used to address part of the expected systematic effects obtains significantly different results than presented in the previous study. In particular, the derived uncertainties are considerably larger. Furthermore, an unexpected systematic trend of the resulting interstellar flow longitude with the selection of interplanetary magnetic field orientation is uncovered.

Size determination and quantification of engineered cerium oxide nanoparticles by flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry.

PubMed

Sánchez-García, L; Bolea, E; Laborda, F; Cubel, C; Ferrer, P; Gianolio, D; da Silva, I; Castillo, J R

2016-03-18

Facing the lack of studies on characterization and quantification of cerium oxide nanoparticles (CeO2 NPs), whose consumption and release is greatly increasing, this work proposes a method for their sizing and quantification by Flow Field-flow Fractionation (FFFF) coupled to Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Two modalities of FFFF (Asymmetric Flow- and Hollow Fiber-Flow Field Flow Fractionation, AF4 and HF5, respectively) are compared, and their advantages and limitations discussed. Experimental conditions (carrier composition, pH, ionic strength, crossflow and carrier flow rates) are studied in detail in terms of NP separation, recovery, and repeatability. Size characterization of CeO2 NPs was addressed by different approaches. In the absence of feasible size standards of CeO2 NPs, suspensions of Ag, Au, and SiO2 NPs of known size were investigated. Ag and Au NPs failed to show a comparable behavior to that of the CeO2 NPs, whereas the use of SiO2 NPs provided size estimations in agreement to those predicted by the theory. The latter approach was thus used for characterizing the size of CeO2 NPs in a commercial suspension. Results were in adequate concordance with those achieved by transmission electron microscopy, X-ray diffraction and dynamic light scattering. The quantification of CeO2 NPs in the commercial suspension by AF4-ICP-MS required the use of a CeO2 NPs standards, since the use of ionic cerium resulted in low recoveries (99 ± 9% vs. 73 ± 7%, respectively). A limit of detection of 0.9 μg L(-1) CeO2 corresponding to a number concentration of 1.8 × 1012 L(-1) for NPs of 5 nm was achieved for an injection volume of 100 μL. Copyright © 2016 Elsevier B.V. All rights reserved.

Major and trace element modeling of mid-ocean ridge mantle melting from the garnet to the plagioclase stability fields: Generating local and global compositional variability

NASA Astrophysics Data System (ADS)

Brown, S. M.; Behn, M. D.; Grove, T. L.

2017-12-01

We present results of a combined petrologic - geochemical (major and trace element) - geodynamical forward model for mantle melting and subsequent melt modification. The model advances Behn & Grove (2015), and is calibrated using experimental petrology. Our model allows for melting in the plagioclase, spinel, and garnet fields with a flexible retained melt fraction (from pure batch to pure fractional), tracks residual mantle composition, and includes melting with water, variable melt productivity, and mantle mode calculations. This approach is valuable for understanding oceanic crustal accretion, which involves mantle melting and melt modification by migration and aggregation. These igneous processes result in mid-ocean ridge basalts that vary in composition at the local (segment) and global scale. The important variables are geophysical and geochemical and include mantle composition, potential temperature, mantle flow, and spreading rate. Accordingly, our model allows us to systematically quantify the importance of each of these external variables. In addition to discriminating melt generation effects, we are able to discriminate the effects of different melt modification processes (inefficient pooling, melt-rock reaction, and fractional crystallization) in generating both local, segment-scale and global-scale compositional variability. We quantify the influence of a specific igneous process on the generation of oceanic crust as a function of variations in the external variables. We also find that it is unlikely that garnet lherzolite melting produces a signature in either major or trace element compositions formed from aggregated melts, because when melting does occur in the garnet field at high mantle temperature, it contributes a relatively small, uniform fraction (< 10%) of the pooled melt compositions at all spreading rates. Additionally, while increasing water content and/or temperature promote garnet melting, they also increase melt extent, pushing the pooled composition to lower Sm/Yb and higher Lu/Hf.

Effect of pyrrolidone-pyroglutamic acid composition on blood flow in rat middle cerebral artery.

PubMed

Semkina, G A; Matsievskii, D D; Mirzoyan, N R

2006-01-01

We compared the effects of a pyrrolidone-pyroglutamic acid composition and nimodipine on blood circulation in the middle cerebral artery in rats. The composition produced a strong effect on blood supply to the brain, stimulated blood flow in the middle cerebral artery (by 60 +/- 9%) and decreased blood pressure (by 25.0 +/- 2.7%). The cerebrovascular effects of this composition differed from those of nimodipine. Nimodipine not only increased middle cerebral artery blood flow, but also decreased cerebral blood flow in the early period after treatment.

Sensitivity analysis of the Gupta and Park chemical models on the heat flux by DSMC and CFD codes

NASA Astrophysics Data System (ADS)

Morsa, Luigi; Festa, Giandomenico; Zuppardi, Gennaro

2012-11-01

The present study is the logical continuation of a former paper by the first author in which the influence of the chemical models by Gupta and by Park on the computation of heat flux on the Orion and EXPERT capsules was evaluated. Tests were carried out by the direct simulation Monte Carlo code DS2V and by the computational fluiddynamic (CFD) code H3NS. DS2V implements the Gupta model, while H3NS implements the Park model. In order to compare the effects of the chemical models, the Park model was implemented also in DS2V. The results showed that DS2V and H3NS compute a different composition both in the flow field and on the surface, even using the same chemical model (Park). Furthermore DS2V computes, by the two chemical models, different compositions in the flow field but the same composition on the surface, therefore the same heat flux. In the present study, in order to evaluate the influence of these chemical models also in a CFD code, the Gupta and the Park models have been implemented in FLUENT. Tests by DS2V and by FLUENT, have been carried out for the EXPERT capsule at the altitude of 70 km and with velocity of 5000 m/s. The capsule experiences a hypersonic, continuum low density regime. Due to the energy level of the flow, the vibration equation, lacking in the original version of FLUENT, has been implemented. The results of the heat flux computation verify that FLUENT is quite sensitive to the Gupta and to the Park chemical models. In fact, at the stagnation point, the percentage difference between the models is about 13%. On the opposite the DS2V results by the two models are practically equivalent.

Volcanic Chemostratigraphy on the Outcrop Using Field-Portable X-Ray Fluorescence: An Example from the Basaltic Flows of Hewitt's Cove, MA.

NASA Astrophysics Data System (ADS)

Wall, A. M.; Brabander, D. J.

2005-05-01

The area of Hewitt's Cove, Hingham, Massachusetts structurally represents the southern extent of the Boston Basin, and as such, provides the opportunity to identify and recognize basin-wide events. While the stratigraphy of the Boston Basin has been developed since the advent of U-Pb geochronology and formal stratigraphic facies descriptions (Socci and Smith, 2001), the stratigraphy of the Hewitt's Cove area has not been thoroughly addressed since the work of William O. Crosby in 1894 (Billings, 1976, Bailey and Bland, 2001). Hewitt's Cove consists of an andesitic basaltic flow, approximately 150 m thick, overlain by siltstone and conglomeratic sequences. Field-Portable X-Ray Fluorescence (FP-XRF) was used on fresh and weathered surfaces on the outcrop and in hand samples, and these analyses were compared with conventional laboratory XRF analyses. The in situ field-based analyses produced a reproducible chemostratigraphy that is consistent with subsequent laboratory-based analyses. These data suggest that the series of andesitic basalt flows at Hewitt's Cove are the result of compositionally different magmatic pulses. Additional analyses must be completed to determine the extent of these pulses and the extent of variation in this area before further conclusions can be made. This study particularly demonstrates the utility of using FP-XRF in igneous geologic applications.

The Seepage Simulation of Single Hole and Composite Gas Drainage Based on LB Method

NASA Astrophysics Data System (ADS)

Chen, Yanhao; Zhong, Qiu; Gong, Zhenzhao

2018-01-01

Gas drainage is the most effective method to prevent and solve coal mine gas power disasters. It is very important to study the seepage flow law of gas in fissure coal gas. The LB method is a simplified computational model based on micro-scale, especially for the study of seepage problem. Based on fracture seepage mathematical model on the basis of single coal gas drainage, using the LB method during coal gas drainage of gas flow numerical simulation, this paper maps the single-hole drainage gas, symmetric slot and asymmetric slot, the different width of the slot combined drainage area gas flow under working condition of gas cloud of gas pressure, flow path diagram and flow velocity vector diagram, and analyses the influence on gas seepage field under various working conditions, and also discusses effective drainage method of the center hole slot on both sides, and preliminary exploration that is related to the combination of gas drainage has been carried on as well.

Effects of composition of grains of debris flow on its impact force

NASA Astrophysics Data System (ADS)

Tang, jinbo; Hu, Kaiheng; Cui, Peng

2017-04-01

Debris flows compose of solid material with broad size distribution from fine sand to boulders. Impact force imposed by debris flows is a very important issue for protection engineering design and strongly influenced by their grain composition. However, this issue has not been studied in depth and the effects of grain composition not been considered in the calculation of the impact force. In this present study, the small-scale flume experiments with five kinds of compositions of grains for debris flow were carried out to study the effect of the composition of grains of debris flow on its impact force. The results show that the impact force of debris flow increases with the grain size, the hydrodynamic pressure of debris flow is calibrated based on the normalization parameter dmax/d50, in which dmax is the maximum size and d50 is the median size. Furthermore, a log-logistic statistic distribution could be used to describe the distribution of magnitude of impact force of debris flow, where the mean and the variance of the present distribution increase with grain size. This distribution proposed in the present study could be used to the reliability analysis of structures impacted by debris flow.

Lunar Exploration Manned and Unmanned

NASA Astrophysics Data System (ADS)

Spudis, P. D.; Asmar, S. W.; Bussey, D. B. J.; Duxbury, N.; Friesen, L. J.; Gillis, J. J.; Hawke, B. R.; Heiken, G.; Lawrence, D.; Manifold, J.; Slade, M. A.; Smith, A.; Taylor, G. J.; Yingst, R. A.

2002-08-01

The past decade has seen two global reconnaissance missions to the Moon, Clementine and Lunar Prospector, which have mapped the surface in multiple wavelengths, determined the Moon's topography and gravity fields, and discovered the presence of water ice in the permanently dark regions near the poles. Although we have learned much about the Moon, many key aspects of its history and evolution remain obscure. The three highest priority questions in lunar science are: 1) the Moon's global composition, particularly the abundance of aluminum and magnesium; 2) the extent, composition, and physical state of polar deposits, including the extent, purity, and thickness of ice, the elemental, isotopic, and molecular composition of polar volatiles, the environment of the polar regions; and 3) the cratering chronology of the Moon and the implications of a possibly unique history, such as a cataclysm, for our understanding of other Solar System objects. Answering and addressing these questions require a series of new missions, including an orbiter (carrying XRF, imaging radar, and other instruments), the deployment of surface network stations equipped with seismometers and heat flow probes, selected robotic sample return missions from geologically simple areas (e.g., youngest lava flow or crater melt sheet), and complex geological field work, conducted by human explorers. Because the Moon is a touchstone for the history and evolution of other rocky bodies in the solar system, we believe that these questions are of very high scientific priority and that lunar missions should receive much more serious attention and detailed study than they have in the past by the NASA Office of Space Science.

Groundwater vulnerability to climate variability: modelling experience and field observations in the lower Magra Valley (Liguria, Italy)

NASA Astrophysics Data System (ADS)

Menichini, Matia; Doveri, Marco; El Mansoury, Bouabid; El Mezouary, Lhoussaine; Lelli, Matteo; Raco, Brunella; Scozzari, Andrea; Soldovieri, Francesco

2016-04-01

The aquifer of the Lower Magra Valley (SE Liguria, Italy) extends in a flat plain, where two main rivers (Magra and Vara) flow. These rivers are characterized by a wide variation of water level and water chemical composition (TDS, Cl and SO4) due to the combination of rainfall regime and the presence of thermal springs in the inner part of the catchment area. Groundwater flow is apparently controlled by stream water infiltration, which affects both water levels and water quality. In particular, the wide range of variation of some particular chemical species in the stream water influences the groundwater chemistry on a seasonal basis. In the area of interest, there is an important well-field, which supplies most of the drinking water to the nearby city of La Spezia. In this context, the groundwater system is exposed to a high degree of vulnerability, both in terms of quality and quantity. This study is aimed to develop a predictive flow and transport model in order to assess the vulnerability s.l. of the Magra Valley aquifer system and to evaluate its behaviour in awaited climate scenarios. A flow and transport model was developed by using MODFLOW and MT3DMS codes, and it's been calibrated in both steady state and transient conditions. The model confirmed the importance of the Magra river in the water balance and chemical composition of the extracted groundwater. In addition, a data-driven modelling approach was applied in order to determine boundary conditions (e.g. rivers and constant head or general head boundaries) of the physical model under hypothetic future climate scenarios. For this purpose, fully synthetic datasets have been generated as a training set of the data-driven scheme, with input variables inspired by selected climate models and input/output relationships estimated by past observations. An experimental run of the flow-transport model for 30 years ahead was performed, based on such hypothetic scenarios. This approach highlighted how the groundwater flow of the studied aquifer is highly vulnerable and sensitive to climate conditions.

Volcanoes Behave as Composite Materials: Implications for Modeling Magma Chambers, Dikes, and Surface Deformation

NASA Astrophysics Data System (ADS)

Leiss, B.; Gudmundsson, A.; Philipp, S. L.

2005-12-01

By definition, composite volcanoes are composed of numerous alternating material units or layers such as lavas, sediments, and pyroclastics. Commonly, these layers have widely different mechanical properties. In particular, some lava flows and welded pyroclastic flows may be stiff (with a high Young's modulus), whereas others, such as non-welded pyroclastic units and sediments, may be soft (with a low Young's modulus). As a consequence, even if the loading (tectonic stress, magmatic pressure, or displacement) is uniform, the stresses within the composite volcano will vary widely. In this sense, the behavior of composite volcanoes is similar to that of general composite materials. The deformation of the surface of a volcano during an unrest period results from stresses generated by processes and parameters such as fluid pressure in a geothermal field or a magma chamber, a regional tectonic event, and a dike injection. Here we present new numerical models on mechanics of magma chambers and dikes, and the associated surface deformation of composite volcanoes. The models show that the surface deformation during magma-chamber inflation and deflation depends much on the chamber geometry, the loading conditions, and the mechanical properties of the rock units that constitute the volcano. The models also indicate that the surface deformation induced by a propagating dike depends much on the mechanical properties of the layers between the dike tip and the surface. In particular, the numerical results show that soft layers and weak contacts between layers may suppress the dike-induced tensile stresses and the associated surface deformation. Many dikes may therefore become injected and arrested at shallow depths in a volcano while giving rise to little or no surface deformation. Traditional analytical surface-deformation models such as a point source (Mogi model) for a magma-chamber pressure change and a dislocation for a dike normally assume the volcano to behave as a homogeneous, isotropic half space. The present numerical results, combined with field studies, indicate that such analytical models may yield results that have little similarity with the actual structure being modeled.

Cation exchange in a temporally fluctuating thin freshwater lens on top of saline groundwater

NASA Astrophysics Data System (ADS)

Eeman, S.; De Louw, P. G. B.; Van der Zee, S. E. A. T. M.

2017-01-01

In coastal-zone fields with a high groundwater level and sufficient rainfall, freshwater lenses are formed on top of saline or brackish groundwater. The fresh and the saline water meet at shallow depth, where a transition zone is found. This study investigates the mixing zone that is characterized by this salinity change, as well as by cation exchange processes, and which is forced by seepage and by rainfall which varies as a function of time. The processes are first investigated for a one-dimensional (1D) stream tube perpendicular to the interface concerning salt and major cation composition changes. The complex sequence of changes is explained with basic cation exchange theory. It is also possible to show that the sequence of changes is maintained when a two-dimensional field is considered where the upward saline seepage flows to drains. This illustrates that for cation exchange, the horizontal component (dominant for flow of water) has a small impact on the chemical changes in the vertical direction. The flow's horizontal orientation, parallel to the interface, leads to changes in concentration that are insignificant compared with those that are found perpendicular to the interface, and are accounted for in the 1D flow tube. Near the drains, differences with the 1D considerations are visible, especially in the longer term, exceeding 100 years. The simulations are compared with field data from the Netherlands which reveal similar patterns.

Free-living bacterial communities associated with tubeworm (Ridgeia piscesae) aggregations in contrasting diffuse flow hydrothermal vent habitats at the Main Endeavour Field, Juan de Fuca Ridge

PubMed Central

Forget, Nathalie L; Kim Juniper, S

2013-01-01

We systematically studied free-living bacterial diversity within aggregations of the vestimentiferan tubeworm Ridgeia piscesae sampled from two contrasting flow regimes (High Flow and Low Flow) in the Endeavour Hydrothermal Vents Marine Protected Area (MPA) on the Juan de Fuca Ridge (Northeast Pacific). Eight samples of particulate detritus were recovered from paired tubeworm grabs from four vent sites. Most sequences (454 tag and Sanger methods) were affiliated to the Epsilonproteobacteria, and the sulfur-oxidizing genus Sulfurovum was dominant in all samples. Gammaproteobacteria were also detected, mainly in Low Flow sequence libraries, and were affiliated with known methanotrophs and decomposers. The cooccurrence of sulfur reducers from the Deltaproteobacteria and the Epsilonproteobacteria suggests internal sulfur cycling within these habitats. Other phyla detected included Bacteroidetes, Actinobacteria, Chloroflexi, Firmicutes, Planctomycetes, Verrucomicrobia, and Deinococcus–Thermus. Statistically significant relationships between sequence library composition and habitat type suggest a predictable pattern for High Flow and Low Flow environments. Most sequences significantly more represented in High Flow libraries were related to sulfur and hydrogen oxidizers, while mainly heterotrophic groups were more represented in Low Flow libraries. Differences in temperature, available energy for metabolism, and stability between High Flow and Low Flow habitats potentially explain their distinct bacterial communities. PMID:23401293

Experimental constraints on the rheology and mechanical properties of lava erupted in the Holuhraun area during the 2014 rifting event at Bárðarbunga, Iceland

NASA Astrophysics Data System (ADS)

Lavallee, Yan; Kendrick, Jackie; Wall, Richard; von Aulock, Felix; Kennedy, Ben; Sigmundsson, Freysteinn

2015-04-01

A fissure eruption began at Holuhraun on 16 August 2014, following magma drainage from the Bárðarbunga volcanic system (Iceland). Extrusion initiated as fire fountaining along a segment of the fracture and rapidly localised to a series of small, aligned cones containing a lava lake that over spilled at both ends, feeding a large lava field. The lava composition and flow behaviour put some constraints on its rheology and mechanical properties. The lava erupted is a nearly aphyric basalt containing approximately 2-3% plagioclase with traces of olivine and pyroxene in a quenched groundmass composed of glass and 20-25% microlites. The transition from fire fountaining to lava flow leads to lava with variable vesicularities; pyroclasts expelled during fire fountaining reach up to 80% vesicles whilst the lava contain up to 45% vesicles. Textures in the lava vary from a'a to slabby pahoehoe, and flow thicknesses from several meters to few centimetres. Tension gashes, crease structures and shear zones in the upper lava carapace reveal the importance of both compressive and tensional stresses. In addition, occasional frictional marks at the base of the lava flow as well as bulldozing of sediments along the flow hint at the importance of frictional properties of the rocks during lava flow. Flow properties, textures and failure modes are strongly dependent on the material properties as well as the local conditions of stress and temperature. Here we expand our field observation with preliminary high-temperature experimental data on the rheological and mechanical properties of the erupted lava. Dilatometric measurements are used to constrain the thermal expansion coefficient of the lava important to constrain the dynamics of cooling of the flow. Micropenetration is further employed to determine the viscosity of the melt at super-liquidus temperature, which is compared to the temperature-dependence of viscosity as constrained by geochemistry. Lastly, uniaxial compression and tension tests are presented to constrain the mechanical properties (strength and Young's modulus) of the rocks, forming the cooler carapace of the flow. This high-temperature experimental dataset will be integrated to field observations to constrain lava flow emplacement.

Reconstruction of lava fields based on 3D and conventional images. Arenal volcano, Costa Rica.

NASA Astrophysics Data System (ADS)

Horvath, S.; Duarte, E.; Fernandez, E.

2007-05-01

Conventional air photographs, multi-spectral images and a map scale 1:10 000 were used to upgrade Arenal volcano's lava field. Arenal volcano located in NW Costa Rica has been active for 39 years. Fifty two days after the initial explosive events that opened three craters on the west flank, lava flows were erupted from crater A (1050 m) in September, 1968 and continued flowing until November, 1973. These lavas were the most voluminous of the eruption and the effusion rate of lava was relatively high in this period. In April, 1974 lava flows were erupted from crater C (1460 m) and continue to present time. Younger lava flows extended over uncovered ground to the south and southwest in the 1980s and early 1990s and onto the northern slopes in the 1990s and 2000s. Lava flows are becoming shorter and narrower with time. Therefore, the centre of mass of the whole lava flow-field has migrated closer to the vent. Above crater C a cone has been growing steadily, reaching a height of 1670 m, 36 m higher than the prehistoric Arenal cone by 2004. After 39 years of continuous emission of lava flows, the profile of Arenal volcano consists of a duplet of cones whose summits are separated by less than 500 meters. Most of the build up around the new cone comes from varied lava flows. For near 30 years volcano monitoring staff (from OVSICORI-UNA) has recorded field observations of regular and extraordinary events, in paper. Several drafts maps have been used for teaching, academic presentations and for graphic explanations to specific audiences and to the general public. An upgraded version was needed. The purpose of this work is to present the most recent lava flows giving a visual presentation of them by computer methods. Combined SIG techniques (Arc View 3.3) and ERDAS produced a base map in which layers containing the recorded lava flows from the recent 16 years, were depicted. Each lava flow has its own characteristics: direction, year of origin, width, length, surface texture, chemical composition, type of lava, velocity, etc. With all this information and photographs; real, visual and topographic images of the position and characters of the 1990s and 2000s lava flows, were obtained . An illustrative poster will be presented along with this abstract to show the construction process of such tool. Moreover, 3D animations will be present in the mentioned poster.

Geomagnetic field intensity determination from Pleistocene trachytic lava flows in Jeju Geopark

NASA Astrophysics Data System (ADS)

Jeong, Doohee; Yu, Yongjae; Liu, Qingsong; Jiang, Zhaoxia; Koh, Gi Won; Koh, Dong-Chan

2014-03-01

A composite of 28 trachytic lava flows were recovered from the Jeju Geopark Drilling Project (JGDP) in Jeju Geopark, one of the new seven wonders of Nature declared by UNESCO in 2011. Each trachytic lava flow has a tendency to increase in magnetic grain size from the rapidly cooled brecciated margin and vesicle streaked zone downward into the massive crystalline flow interiors. The brecciated margin and vesicle streaked zone of individual trachytic lava flow contains exclusively fine-grained magnetite as inclusions in plagioclase. High-fidelity paleointensity determinations were obtained from 26 (out of 224 examined) samples from JGDP cores. Temporal variation of virtual axial dipole moments (VADMs) calculated from the absolute paleointensity estimates follows the trend of sint-800 data for the interval from ˜80 to ˜360 ka. High VADM from flow 21 possibly represents real intensity peak, as previously recognized high VADM in Japan at ˜336 ka, in Trans-Mexican volcanism ˜339, and in Hawaii ˜340-350 ka. Perhaps such a strong magnetic intensity near ˜325-350 ka might be smoothed out in relative paleointensity records.

Interactions between solidification and compositional convection in mushy layers

NASA Technical Reports Server (NTRS)

Worster, M. Grae

1994-01-01

Mushy layers are ubiquitous during the solidification of alloys. They are regions of mixed phase wherein solid crystals are bathed in the melt from which they grew. The matrix of crystals forms a porous medium through which the melt can flow, driven either by external forces or by its own buoyancy in a gravitational field. Buoyancy-driven convection of the melt depends both on temperature gradients, which are necessary for solidification, and on compositional gradients, which are generated as certain components of the alloy are preferentially incorporated in the solid phase and the remaining components are expelled into the melt. In fully liquid regions, the combined action of temperature and concentration on the density of the liquid can cause various forms of double-diffusive convection. However, in the interior of mushy regions the temperature and concentration are thermodynamically coupled so only single-diffusive convection can occur. Typically, the effect of composition on the buoyancy of the melt is much greater than the effect of temperature, and thus convection in mushy layers in driven primarily by the computational gradients within them. The rising interstitial liquid is relatively dilute, having come from colder regions of the mushy layer, where the liquidus concentration is lower, and can dissolve the crystal matrix through which it flows. This is the fundamental process by which chimneys are formed. It is a nonlinear process that requires the convective velocities to be sufficiently large, so fully fledged chimneys (narrow channels) might be avoided by means that weaken the flow. Better still would be to prevent convection altogether, since even weak convection will cause lateral, compositional inhomogeneities in castings. This report outlines three studies that examine the onset of convection within mushy layers.

The Pioneer Ultramafic Complex of the Barberton Greenstone Belt, South Africa

NASA Astrophysics Data System (ADS)

Cooper, M. R.; Byerly, G. R.; Lowe, D. R.; Thompson, M. E.

2005-12-01

The 3.55-3.22 Ga Barberton Greenstone Belt is an approximately 100km x 30km northeast trending, isoclinally folded, volcanic and sedimentary succession surrounded by intrusive granitic rocks. It is perhaps Earth's best preserved mid-Archean supracrustal sequence and also among the most magnesian, making it an ideal location for studying compositionally distinct rocks of the Archean, such as komatiites. The Pioneer Ultramafic Complex has been interpreted as a komatiitic intrusion but we argue that it is a sequence of layered komatiitic flows and interbedded tuffs correlative with other komatiitic extrusive units of the 3.29 Ga Weltevreden Formation, the uppermost formation of the Onverwacht Group. The Pioneer Ultramafic Complex contains at least 900m of section in the study area, including at least 5 flow sets, with individual flows up to 100 m thick, sections of tuff up to 100m thick and additional thinner tuff units. The base of the sequence is in fault contact with the Sawmill Ultramafic Complex, which is similar to and perhaps correlative with the Pioneer. The top of the sequence is bounded by the Moodies Fault and slightly younger sedimentary rocks of the Fig Tree and Moodies Groups. Typical flows of the Pioneer have highly serpentinized olivine-rich cumulate bases, fresh olivine bearing peridotitic lithologies in central portions, and increasing pyroxene content, pyroxene size, and elongation of grains toward the flow tops. Three of the five flows are capped with random and/or oriented spinifex layers. The tuffs within this and other layered ultramafic complexes of the Barberton Greenstone Belt are mostly fine grained, slaty serpentinites that were previously interpreted as bedding horizontal zones of shearing. However, rare preservation of angular and vesicular lapilli, and more commonly cross-stratification in finer grained layers, provide strong evidence that these layers represent tuffs. High chromium and other trace element contents suggest they are komatiitic tuffs likely co-magmatic with the interbedded komatiitic lava flows. Compositions of fresh olivines range between 91 to 93 percent forsterite, indicating a komatiitic melt composition. In addition to olivine phenocrysts, fresh chromite, orthopyroxene, pigeonite, and augite are all present as smaller intercumulus crystals or microphenocrysts. The pyroxenes have Mg numbers up to 89 and Al/Ti ratios approximately 10-15. The latter are consistent with the Al/Ti ratios of 20-30 found within the komatiites and tuffs analyzed thus far. These ratios indicate the flows belong to the aluminium undepleted group of komatiites. The rock and mineral chemistry of these flows allow us to determine melt compositions and explore correlations and relationships with other komatiitic flows and layered ultramafic complexes of the Barberton Greenstone Belt. Field studies of these flows help characterize an Archean igneous complex believed to represent shallow marine deposition of komatiitic tuffs and coeval emplacement of thick vertically differentiated komatiitic flows.

Solidification of II-VI Compounds in a Rotating Magnetic Field

NASA Technical Reports Server (NTRS)

Gillies, D. C.; Volz, M. P.; Mazuruk, K.; Motakef, S.; Dudley, M.; Matyi, R.

1999-01-01

This project is aimed at using a rotating magnetic field (RMF) to control fluid flow and transport during directional solidification of elemental and compound melts. Microgravity experiments have demonstrated that small amounts of residual acceleration of less than a micro-g can initiate and prolong fluid flow, particularly when there is a static component of the field perpendicular to the liquid solid interface. Thus a true diffusion boundary layer is not formed, and it becomes difficult to verify theories of solidification or to achieve diffusion controlled solidification. The RMF superimposes a stirring effect on an electrically conducting liquid, and with appropriate field strengths and frequencies, controlled transport of material through a liquid column can be obtained. As diffusion conditions are precluded and complete mixing conditions prevail, the technique is appropriate for traveling solvent zone or float zone growth methods in which the overall composition of the liquid can be maintained throughout the growth experiment. Crystals grown by RMF techniques in microgravity in previous, unrelated missions have shown exceptional properties. The objective of the project is two-fold, namely (1) using numerical modeling to simulate the behavior of a solvent zone with applied thermal boundary conditions and demonstrate the effects of decreasing gravity levels, or an increasing applied RMF, or both, and (2) to grow elements and II-VI compounds from traveling solvent zones both with and without applied RMFs, and to determine objectively how well the modeling predicts solidification parameters. Numerical modeling has demonstrated that, in the growth of CdTe from a tellurium solution, a rotating magnetic field can advantageously modify the shape of the liquid solid interface such that the interface is convex as seen from the liquid. Under such circumstances, the defect structure is reduced as any defects which are formed tend to grow out and not propagate. The flow of liquid, however, is complex due to the competing flow induced by the rotating magnetic field and the buoyancy driven convection. When the acceleration forces are reduced to one thousandth of gravity, the flow pattern is much simplified and well controlled material transport through the solvent zone can be readily achieved. Triple axis diffractometry and x-ray synchrotron topography have demonstrated that there is no significant improvement in crystal quality for HgCdTe grown on earth from a tellurium solution when a rotating magnetic field is applied. However, modeling shows that the flow in microgravity with a rotating magnetic field would produce a superior product.

Blunt-Body Aerothermodynamic Database from High-Enthalpy CO2 Testing in an Expansion Tunnel

NASA Technical Reports Server (NTRS)

Hollis, Brian R.; Prabhu, Dinesh K.; Maclean, Matthew; Dufrene, Aaron

2016-01-01

An extensive database of heating, pressure, and flow field measurements on a 70-deg sphere-cone blunt body geometry in high-enthalpy, CO2 flow has been generated through testing in an expansion tunnel. This database is intended to support development and validation of computational tools and methods to be employed in the design of future Mars missions. The test was conducted in an expansion tunnel in order to avoid uncertainties in the definition of free stream conditions noted in previous studies performed in reflected shock tunnels. Data were obtained across a wide range of test velocity/density conditions that produced various physical phenomena of interest, including laminar and transitional/turbulent boundary layers, non-reacting to completely dissociated post-shock gas composition and shock-layer radiation. Flow field computations were performed at the test conditions and comparisons were made with the experimental data. Based on these comparisons, it is recommended that computational uncertainties on surface heating and pressure, for laminar, reacting-gas environments can be reduced to +/-10% and +/-5%, respectively. However, for flows with turbulence and shock-layer radiation, there were not sufficient validation-quality data obtained in this study to make any conclusions with respect to uncertainties, which highlights the need for further research in these areas.

Halophilic viruses with varying biochemical and biophysical properties are amenable to purification with asymmetrical flow field-flow fractionation.

PubMed

Eskelin, Katri; Lampi, Mirka; Meier, Florian; Moldenhauer, Evelin; Bamford, Dennis H; Oksanen, Hanna M

2017-11-01

Viruses come in various shapes and sizes, and a number of viruses originate from extremities, e.g. high salinity or elevated temperature. One challenge for studying extreme viruses is to find efficient purification conditions where viruses maintain their infectivity. Asymmetrical flow field-flow fractionation (AF4) is a gentle native chromatography-like technique for size-based separation. It does not have solid stationary phase and the mobile phase composition is readily adjustable according to the sample needs. Due to the high separation power of specimens up to 50 µm, AF4 is suitable for virus purification. Here, we applied AF4 for extremophilic viruses representing four morphotypes: lemon-shaped, tailed and tailless icosahedral, as well as pleomorphic enveloped. AF4 was applied to input samples of different purity: crude supernatants of infected cultures, polyethylene glycol-precipitated viruses and viruses purified by ultracentrifugation. All four virus morphotypes were successfully purified by AF4. AF4 purification of culture supernatants or polyethylene glycol-precipitated viruses yielded high recoveries, and the purities were comparable to those obtained by the multistep ultracentrifugation purification methods. In addition, we also demonstrate that AF4 is a rapid monitoring tool for virus production in slowly growing host cells living in extreme conditions.

Ground-Water Flow in the Vicinity of the Ho-Chunk Nation Communities of Indian Mission and Sand Pillow, Jackson County, Wisconsin

USGS Publications Warehouse

Dunning, Charles P.; Mueller, Gregory D.; Juckem, Paul F.

2008-01-01

An analytic element ground-water-flow model was constructed to help understand the ground-water-flow system in the vicinity of the Ho-Chunk Nation communities of Indian Mission and Sand Pillow in Jackson County, Wisconsin. Data from interpretive reports, well-drillers' construction reports, and an exploratory augering program in 2003 indicate that sand and gravel of varying thickness (0-150 feet[ft]) and porous sandstone make up a composite aquifer that overlies Precambrian crystalline rock. The geometric mean values for horizontal hydraulic conductivity were estimated from specific-capacity data to be 61.3 feet per day (ft/d) for sand and gravel, 6.6 ft/d for sandstone, and 12.0 ft/d for the composite aquifer. A ground-water flow model was constructed, the near field of which encompassed the Levis and Morrison Creeks Watershed. The flow model was coupled to the parameter-estimation program UCODE to obtain a best fit between simulated and measured values of ground-water levels and estimated Q50 flow duration (base flow). Calibration of the model with UCODE provided a ground-water recharge rate of 9 inches per year and a horizontal hydraulic conductivity of 13 ft/d for the composite aquifer. Using these calibrated parameter values, simulated heads from the model were on average within 5 ft of the measured water levels. In addition, these parameter values provided an acceptable base-flow calibration for Hay, Dickey, and Levis Creeks; the calibration was particularly close for Levis Creek, which was the most frequently measured stream in the study area. The calibrated model was used to simulate ground-water levels and to determine the direction of ground-water flow in the vicinity of Indian Mission and Sand Pillow communities. Backward particle tracking was conducted for Sand Pillow production wells under two pumping simulations to determine their 20-year contributing areas. In the first simulation, new production wells 6, 7, and 8 were each pumped at 50 gallons per minute (gal/min). In the second simulation, new production wells 6, 7, and 8 and existing production well 5 were each pumped at 50 gal/min. The second simulation demonstrated interference between the existing production well 5 and the new production wells when all were pumping at 50 gal/min.

Groundwater flow associated with coalbed gas production, Ferron Sandstone, east-central Utah

USGS Publications Warehouse

Anna, L.O.

2003-01-01

The flow and distribution of water associated with coalbed gas production in the Ferron Sandstone was characterized utilizing a discrete fracture network model and a porous media model. A discrete fracture network model calculated fluid flux through volumes of various scales to determine scale effects, directional bulk permeability, and connectivity. The mean directional permeabilities varied by less than a factor of 6, with the northwest-southeast direction (face cleat direction) as the most conductive. Northwest southeast directed hydrofracture simulations increased permeability in all directions except the northeast-southwest, although the permeability increase was not more than a factor of 3. Cluster analysis showed that the simulated cleat network was very well connected at all simulated scales. For thick coals, the entire cleat network formed one compartment, whereas thin coals formed several compartments. Convex hulls of the compartments confirmed that the directional bulk permeability was nearly isotropic. Volumetric calculations of the Ferron coal indicated that all the water produced to date can be accounted for from the coal cleat porosity system and does not depend on contributions of water from contiguous units.Flow paths, determined from porous media modeling from recharge to discharge, indicate that the three coalbed gas (CBG) fields assessed in this study could have different groundwater chemical compositions as confirmed by geochemical data. Simulated water production from 185 wells from 1993 to 1998 showed that in 1998 the maximum head drawdown from the Drunkards Wash field was more than 365 m, and the cone of depression extended to within a short distance of the Ferron outcrop. Maximum drawdown in the Helper field was 120 m, and the maximum drawdown in the Buzzards Bench field was just over 60 m. The cone of depression for the Helper field was half the size of the Drunkards Wash field, and the cone of depression for the Buzzards Bench field was limited to just outside the field unit. Water budget calculations from the simulation indicate that none of the stream flows are affected by coalbed gas associated water production. ?? 2003 Elsevier B.V. All rights reserved.

Application of supercritical antisolvent method in drug encapsulation: a review

PubMed Central

Kalani, Mahshid; Yunus, Robiah

2011-01-01

The review focuses on the application of supercritical fluids as antisolvents in the pharmaceutical field and demonstrates the supercritical antisolvent method in the use of drug encapsulation. The main factors for choosing the solvent and biodegradable polymer to produce fine particles to ensure effective drug delivery are emphasized and the effect of polymer structure on drug encapsulation is illustrated. The review also demonstrates the drug release mechanism and polymeric controlled release system, and discusses the effects of the various conditions in the process, such as pressure, temperature, concentration, chemical compositions (organic solvents, drug, and biodegradable polymer), nozzle geometry, CO2 flow rate, and the liquid phase flow rate on particle size and its distribution. PMID:21796245

Control of unsteady separated flow associated with the dynamic stall of airfoils

NASA Technical Reports Server (NTRS)

Wilder, M. C.

1995-01-01

An effort to understand and control the unsteady separated flow associated with the dynamic stall of airfoils was funded for three years through the NASA cooperative agreement program. As part of this effort a substantial data base was compiled detailing the effects various parameters have on the development of the dynamic stall flow field. Parameters studied include Mach number, pitch rate, and pitch history, as well as Reynolds number (through two different model chord lengths) and the condition of the boundary layer at the leading edge of the airfoil (through application of surface roughness). It was found for free stream Mach numbers as low as 0.4 that a region of supersonic flow forms on the leading edge of the suction surface of the airfoil at moderate angles of attack. The shocks which form in this supersonic region induce boundary-layer separation and advance the dynamic stall process. Under such conditions a supercritical airfoil profile is called for to produce a flow field having a weaker leading-edge pressure gradient and no leading-edge shocks. An airfoil having an adaptive-geometry, or dynamically deformable leading edge (DDLE), is under development as a unique active flow-control device. The DDLE, formed of carbon-fiber composite and fiberglass, can be flexed between a NACA 0012 profile and a supercritical profile in a controllable fashion while the airfoil is executing an angle-of-attack pitch-up maneuver. The dynamic stall data were recorded using point diffraction interferometry (PDI), a noninvasive measurement technique. A new high-speed cinematography system was developed for recording interferometric images. The system is capable of phase-locking with the pitching airfoil motion for real-time documentation of the development of the dynamic stall flow field. Computer-aided image analysis algorithms were developed for fast and accurate reduction of the images, improving interpretation of the results.

Crystallization, flow and thermal histories of lunar and terrestrial compositions

NASA Technical Reports Server (NTRS)

Uhlmann, D. R.

1979-01-01

Contents: a kinetic treatment of glass formation; effects of nucleating heterogeneities on glass formation; glass formation under continuous cooling conditions; crystallization statistics; kinetics of crystal nucleation; diffusion controlled crystal growth; crystallization of lunar compositions; crystallization between solidus and liquidus; crystallization on reheating a glass; temperature distributions during crystallization; crystallization of anorthite and anorthite-albite compositions; effect of oxidation state on viscosity; diffusive creep and viscous flow; high temperature flow behavior of glass-forming liquids, a free volume interpretation; viscous flow behavior of lunar compositions; thermal history of orange soil material; breccias formation by viscous sintering; viscous sintering; thermal histories of breccias; solute partitioning and thermal history of lunar rocks; heat flow in impact melts; and thermal histories of olivines.

Tracking Hydrothermal Fluid Pathways from Surface Alteration Mineralogy: The Case of Licancura Geothermal Field, Northern Chile

NASA Astrophysics Data System (ADS)

Camus, E.; Elizalde, J. D.; Morata, D.; Wechsler, C.

2017-12-01

In geothermal systems alteration minerals are evidence of hot fluid flow, being present even in absence of other surface manifestations. Because these minerals result from the interaction between geothermal fluids and surrounding host rocks, they will provide information about features of thermal fluids as temperature, composition and pH, allowing tracking their changes and evolution. In this work, we study the Licancura Geothermal field located in the Andean Cordillera in Northern Chile. The combination of Principal Components Analysis on ASTER-L1T imagery and X Ray Diffraction (XRD) allow us to interpret fluid conditions and the areas where fluid flow took place. Results from red, green, blue color composite imagery show the presence of three types of secondary paragenesis. The first one corresponds to hematite and goethite, mainly at the east of the area, in the zone of eroded Pliocene volcanic edifices. The second one, mainly at the center of the area, highlighting propylitic alteration, includes minerals such as chlorite, illite, calcite, zeolites, and epidote. The third paragenesis, spatially related to the intersection between faults, represents advanced argillic alteration, includes minerals as alunite, kaolinite, and jarosite. XRD analysis support results from remote sensing techniques. These results suggest an acid pH hydrothermal fluid reaching temperatures at surface up to 80-100°C, which used faults as a conduit, originating advanced argillic minerals. The same fluid was, probably, responsible for propylitic paragenesis. However, iron oxides paragenesis identified in the area of eroded volcanoes probably corresponds to other processes associated with weathering rather than geothermal activity. In this work, we propose the applicability of remote sensing techniques as a first level exploration tool useful for high-altitude geothermal fields. Detailed clay mineral studies (XRD and SEM) would allow us to a better characterization of the geothermal fluid flow and the defining fluid pathways in the Licancura geothermal field. This work is a contribution to the FONDAP-CONICYT 15090013 Project. E.C. thanks CONICYT for her Ph.D. grant.

Similarities and Differences in the Distributions of Hydrothermal Venting and the Formation of Seafloor Massive Sulfide Deposits at the Tui Malila and Mariner Vent Fields, Valu Fa Ridge

NASA Astrophysics Data System (ADS)

Tivey, M. K.; Evans, G. N.; Ferrini, V. L.; Spierer, H.

2016-12-01

High-resolution bathymetric mapping and recovery and study of samples from precisely known locations relative to local tectonic and volcanic features provide insight into the formation of seafloor massive sulfide deposits. Additional insight comes from repeat mapping efforts in 2005 and 2016 that provide details of relations and changes that may have occurred over time. Located 21 km apart on the Valu Fa Ridge, the Tui Malila and Mariner vent fields exhibit contrasting vent fluid chemistry, mineral deposit composition, deposit morphology, and seafloor morphology. At the Tui Malila vent field, near-neutral pH fluids with low metal contents vent from Zn- and Ba-rich, but Cu-poor deposits. The highest temperature fluids are found near the intersection of two faults and between volcanic domes. In contrast, acidic, metal-rich hydrothermal fluids at the Mariner vent field vent from Cu-rich, Zn-poor deposits. No discernable faults are present. At both the Tui Malila and Mariner vent fields, intermediate temperature fluids were sampled emanating from barite-rich deposits. At the Tui Malila vent field, intermediate fluids vent from flange-dominated edifices that are located on brecciated lava flow that overlays one of the two faults. Intermediate fluids at the Mariner vent field vent from squat terrace-like edifices located peripheral (10-15 m) to high-temperature chimney edifices, and seafloor morphology is dominated by brecciated lava flows. Thermodynamic models of mixing between high-temperature hydrothermal fluids and seawater that consider subsurface deposition of sulfide minerals and iron oxyhydroxide were used to reproduce the chemistry of intermediate fluids. This study suggests that the porous, brecciated lavas characteristic of these two vent fields provide sites for subsurface mixing and contribute to mineral deposition, with the faults at the Tui Malila vent field providing a pathway for subsurface fluid flow.

Formation of Heliospheric Arcs of Slow Solar Wind

NASA Technical Reports Server (NTRS)

Higginson, A. K.; Antiochos, S. K.; Devore, C. R.; Wyper, P. F.; Zurbuchen, T. H.

2017-01-01

A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun's atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.

Formation of Heliospheric Arcs of Slow Solar Wind

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higginson, A. K.; Zurbuchen, T. H.; Antiochos, S. K.

A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun’s atmosphere is divided into magnetically open regions, known as coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchangemore » reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole with a geometry that includes a narrow corridor flanked by closed field and is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.« less

Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and making same

DOEpatents

Syn, C.K.; Lesuer, D.R.

1995-07-04

A laminated metal composite of low flow stress layers and high flow stress layers is described which is formed using flow constraining elements, preferably in the shape of rings, individually placed around each of the low flow stress layers while pressure is applied to the stack to bond the layers of the composite together, to thereby restrain the flow of the low flow stress layers from the stack during the bonding. The laminated metal composite of the invention is made by the steps of forming a stack of alternate layers of low flow stress layers and high flow stress layers with each layer of low flow stress material surrounded by an individual flow constraining element, such as a ring, and then applying pressure to the top and bottom surfaces of the resulting stack to bond the dissimilar layers together, for example, by compression rolling the stack. In a preferred embodiment, the individual flow constraining elements surrounding the layers of low flow stress material are formed of a material which may either be the same material as the material comprising the high flow stress layers, or have similar flow stress characteristics to the material comprising the high flow stress layers. Additional sacrificial layers may be added to the top and bottom of the stack to avoid damage to the stack during the bonding step; and these additional layers may then be removed after the bonding step. 5 figs.

Laminated metal composite formed from low flow stress layers and high flow stress layers using flow constraining elements and making same

DOEpatents

Syn, Chol K.; Lesuer, Donald R.

1995-01-01

A laminated metal composite of low flow stress layers and high flow stress layers is described which is formed using flow constraining elements, preferably in the shape of rings, individually placed around each of the low flow stress layers while pressure is applied to the stack to bond the layers of the composite together, to thereby restrain the flow of the low flow stress layers from the stack during the bonding. The laminated metal composite of the invention is made by the steps of forming a stack of alternate layers of low flow stress layers and high flow stress layers with each layer of low flow stress material surrounded by an individual flow constraining element, such as a ring, and then applying pressure to the top and bottom surfaces of the resulting stack to bond the dissimilar layers together, for example, by compression rolling the stack. In a preferred embodiment, the individual flow constraining elements surrounding the layers of low flow stress material are formed of a material which may either be the same material as the material comprising the high flow stress layers, or have similar flow stress characteristics to the material comprising the high flow stress layers. Additional sacrificial layers may be added to the top and bottom of the stack to avoid damage to the stack during the bonding step; and these additional layers may then be removed after the bonding step.

In vitro drug release behavior from a novel thermosensitive composite hydrogel based on Pluronic f127 and poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) copolymer

PubMed Central

Gong, Chang Yang; Shi, Shuai; Dong, Peng Wei; Zheng, Xiu Ling; Fu, Shao Zhi; Guo, Gang; Yang, Jing Liang; Wei, Yu Quan; Qian, Zhi Yong

2009-01-01

Background Most conventional methods for delivering chemotherapeutic agents fail to achieve therapeutic concentrations of drugs, despite reaching toxic systemic levels. Novel controlled drug delivery systems are designed to deliver drugs at predetermined rates for predefined periods at the target organ and overcome the shortcomings of conventional drug formulations therefore could diminish the side effects and improve the life quality of the patients. Thus, a suitable controlled drug delivery system is extremely important for chemotherapy. Results A novel biodegradable thermosensitive composite hydrogel, based on poly(ethylene glycol)-poly(ε-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE) and Pluronic F127 copolymer, was successfully prepared in this work, which underwent thermosensitive sol-gel-sol transition. And it was flowing sol at ambient temperature but became non-flowing gel at body temperature. By varying the composition, sol-gel-sol transition and in vitro drug release behavior of the composite hydrogel could be adjusted. Cytotoxicity of the composite hydrogel was conducted by cell viability assay using human HEK293 cells. The 293 cell viability of composite hydrogel copolymers were yet higher than 71.4%, even when the input copolymers were 500 μg per well. Vitamin B12 (VB12), honokiol (HK), and bovine serum albumin (BSA) were used as model drugs to investigate the in vitro release behavior of hydrophilic small molecular drug, hydrophobic small molecular drug, and protein drug from the composite hydrogel respectively. All the above-mentioned drugs in this work could be released slowly from composite hydrogel in an extended period. Chemical composition of composite hydrogel, initial drug loading, and hydrogel concentration substantially affected the drug release behavior. The higher Pluronic F127 content, lower initial drug loading amount, or lower hydrogel concentration resulted in higher cumulative release rate. Conclusion The results showed that composite hydrogel prepared in this paper were biocompatible with low cell cytotoxicity, and the drugs in this work could be released slowly from composite hydrogel in an extended period, which suggested that the composite hydrogel might have great potential applications in biomedical fields. PMID:19210779

Simplified behaviors from increased heterogeneity: I. 2-D uranium transport experiments at the decimeter scale.

PubMed

Miller, Andrew W; Rodriguez, Derrick R; Honeyman, Bruce D

2013-05-01

Intermediate scale tank studies were conducted to examine the effects of physical heterogeneity of aquifer material on uranium desorption and subsequent transport in order to bridge the scaling gap between bench and field scale systems. Uranium contaminated sediment from a former uranium mill field site was packed into two 2-D tanks with internal dimensions of 2.44×1.22×0.076 m (tank 1) and 2.44×0.61×0.076 m (tank 2). Tank 1 was packed in a physically homogenous manner, and tank 2 was packed with long lenses of high and low conductivities resulting in different flow fields within the tanks. Chemical gradients within the flow domain were altered by temporal changes in influent water chemistry. The uranium source was desorption from the sediment. Despite the physical differences in the flow fields, there were minimal differences in global uranium leaching behavior between the two tanks. The dominant uranium species in both tanks over time and space was Ca2UO2(CO3)3(0). However, the uranium/alkalinity relationships varied as a function of time in tank 1 and were independent of time in tank 2. After planned stop-flow events, small, short-lived rebounds were observed in tank 1 while no rebound of uranium concentrations was observed in tank 2. Despite appearing to be in local equilibrium with respect to uranium desorption, a previously derived surface complexation model was insufficient to describe uranium partitioning within the flow domain. This is the first in a pair of papers; the companion paper presents an intermediate scale 3-D tank experiment and inter-tank comparisons. For these systems, physical heterogeneity at or above the decimeter scale does not affect global scale uranium desorption and transport. Instead, uranium fluxes are controlled by chemistry dependent desorption patterns induced by changing the influent ionic composition. Published by Elsevier B.V.

Simplified behaviors from increased heterogeneity: I. 2-D uranium transport experiments at the decimeter scale

NASA Astrophysics Data System (ADS)

Miller, Andrew W.; Rodriguez, Derrick R.; Honeyman, Bruce D.

2013-05-01

Intermediate scale tank studies were conducted to examine the effects of physical heterogeneity of aquifer material on uranium desorption and subsequent transport in order to bridge the scaling gap between bench and field scale systems. Uranium contaminated sediment from a former uranium mill field site was packed into two 2-D tanks with internal dimensions of 2.44 × 1.22 × 0.076 m (tank 1) and 2.44 × 0.61 × 0.076 m (tank 2). Tank 1 was packed in a physically homogenous manner, and tank 2 was packed with long lenses of high and low conductivities resulting in different flow fields within the tanks. Chemical gradients within the flow domain were altered by temporal changes in influent water chemistry. The uranium source was desorption from the sediment. Despite the physical differences in the flow fields, there were minimal differences in global uranium leaching behavior between the two tanks. The dominant uranium species in both tanks over time and space was Ca2UO2(CO3)30. However, the uranium/alkalinity relationships varied as a function of time in tank 1 and were independent of time in tank 2. After planned stop-flow events, small, short-lived rebounds were observed in tank 1 while no rebound of uranium concentrations was observed in tank 2. Despite appearing to be in local equilibrium with respect to uranium desorption, a previously derived surface complexation model was insufficient to describe uranium partitioning within the flow domain. This is the first in a pair of papers; the companion paper presents an intermediate scale 3-D tank experiment and inter-tank comparisons. For these systems, physical heterogeneity at or above the decimeter scale does not affect global scale uranium desorption and transport. Instead, uranium fluxes are controlled by chemistry dependent desorption patterns induced by changing the influent ionic composition.

Numerical and experimental investigation of plasma plume deflection with MHD flow control

NASA Astrophysics Data System (ADS)

Kai, ZHAO; Feng, LI; Baigang, SUN; Hongyu, YANG; Tao, ZHOU; Ruizhi, SUN

2018-04-01

This paper presents a composite magneto hydrodynamics (MHD) method to control the low-temperature micro-ionized plasma flow generated by injecting alkali salt into the combustion gas to realize the thrust vector of an aeroengine. The principle of plasma flow with MHD control is analyzed. The feasibility of plasma jet deflection is investigated using numerical simulation with MHD control by loading the User-Defined Function model. A test rig with plasma flow controlled by MHD is established. An alkali salt compound with a low ionization energy is injected into combustion gas to obtain the low-temperature plasma flow. Finally, plasma plume deflection is obtained in different working conditions. The results demonstrate that plasma plume deflection with MHD control can be realized via numerical simulation. A low-temperature plasma flow can be obtained by injecting an alkali metal salt compound with low ionization energy into a combustion gas at 1800–2500 K. The vector angle of plasma plume deflection increases with the increase of gas temperature and the magnetic field intensity. It is feasible to realize the aim of the thrust vector of aeroengine by using MHD to control plasma flow deflection.

Reconstruction of the dynamics of the 1800-1801 Hualalai eruption: Implications for planetary lava flows

NASA Technical Reports Server (NTRS)

Baloga, Stephen; Spudis, Paul

1993-01-01

The 1800-1801 eruption of alkalic basalt from the Hualalai volcano, Hawaii provides a unique opportunity for investigating the dynamics of lava flow emplacement with eruption rates and compositions comparable to those that have been suggested for planetary eruptions. Field observations suggest new considerations must be used to reconstruct the emplacement of these lava flows. These observations are: (1) the flow traversed the 15 km from the vent to the sea so rapidly that no significant crust formed and an observation of the eruption reported that the flow reach the sea from the vent in approximately 1 hour; (2) the drainage of beds of xenolith nodules indicates a highly fluid, low viscosity lava; (3) overspills and other morphologic evidence for a very low viscosity host fluid; (4) no significant longitudinal increase in flow thickness that might be associated with an increase in the rheological properties of the lava; and (5) the relatively large size of channels associated with the flow, up to 80 meters across and several km long. Models for many geologic mass movements and fast moving fluids with various loadings and suspensions are discussed.

Composite-Grid Techniques and Adaptive Mesh Refinement in Computational Fluid Dynamics

DTIC Science & Technology

1990-01-01

years of hard work. During that period an estimated 410 gallons of strong coffee has flowed under the bridge. It has been with the support of this...thank Peter James Coffee Company for the continuous supply of Vienna Roast . I should also thank my advisor, Joel Ferziger, for getting me started on my...variation confined to some rather narrow zones in the field. These zones (boundary layers, shocks, etc.) cause problems during numerical solution of

Magmatism, ash-flow tuffs, and calderas of the ignimbrite flareup in the western Nevada volcanic field, Great Basin, USA

USGS Publications Warehouse

Christopher D. Henry,; John, David A.

2013-01-01

The western Nevada volcanic field is the western third of a belt of calderas through Nevada and western Utah. Twenty-three calderas and their caldera-forming tuffs are reasonably well identified in the western Nevada volcanic field, and the presence of at least another 14 areally extensive, apparently voluminous ash-flow tuffs whose sources are unknown suggests a similar number of undiscovered calderas. Eruption and caldera collapse occurred between at least 34.4 and 23.3 Ma and clustered into five ∼0.5–2.7-Ma-long episodes separated by quiescent periods of ∼1.4 Ma. One eruption and caldera collapse occurred at 19.5 Ma. Intermediate to silicic lavas or shallow intrusions commonly preceded caldera-forming eruptions by 1–6 Ma in any specific area. Caldera-related as well as other magmatism migrated from northeast Nevada to the southwest through time, probably resulting from rollback of the formerly shallow-dipping Farallon slab. Calderas are restricted to the area northeast of what was to become the Walker Lane, although intermediate and effusive magmatism continued to migrate to the southwest across the future Walker Lane.Most ash-flow tuffs in the western Nevada volcanic field are rhyolites, with approximately equal numbers of sparsely porphyritic (≤15% phenocrysts) and abundantly porphyritic (∼20–50% phenocrysts) tuffs. Both sparsely and abundantly porphyritic rhyolites commonly show compositional or petrographic evidence of zoning to trachydacites or dacites. At least four tuffs have volumes greater than 1000 km3, with one possibly as much as ∼3000 km3. However, the volumes of most tuffs are difficult to estimate, because many tuffs primarily filled their source calderas and/or flowed and were deposited in paleovalleys, and thus are irregularly distributed.Channelization and westward flow of most tuffs in paleovalleys allowed them to travel great distances, many as much as ∼250 km (original distance) to what is now the western foothills of the Sierra Nevada, which was not a barrier to westward flow of ash flows at that time. At least three tuffs flowed eastward across a north-south paleodivide through central Nevada. That tuffs could flow significant distances apparently uphill raises questions about the absolute elevation of the region and the elevation, relief, and location of the paleodivide.Calderas are equant to slightly elongate, at least 12 km in diameter, and as much as 35 km in longest dimension. Exceptional exposure of two caldera complexes that resulted from extensional faulting and tilting show that calderas subsided as much as 5 km as large piston-like blocks; caldera walls were vertical to steeply inward dipping to depths ≥4–5 km, and topographic walls formed by slumping of wall rock into the caldera were only slightly outboard (≤1 km) of structural margins.Most calderas show abundant post-collapse magmatism expressed as resurgent intrusions, ring-fracture intrusions, or intracaldera lavas that are closely related temporally (∼0–0.5 Ma younger) to caldera formation. Granitoid intrusions, which were emplaced at paleodepths ranging from <1 to ∼7 km, are compositionally similar to both intracaldera ash-flow tuffs and post-caldera lavas. Therefore in the western Nevada volcanic field, erupted caldera-forming tuffs commonly were the upper parts of large magma chambers that retained considerable volumes of magma after tuff eruption.Several calderas in the western Nevada volcanic field hosted large hydrothermal systems and underwent extensive hydrothermal alteration. Different types of hydrothermal systems (neutral-pH alkali-chloride and acid or low-pH magmatic-hydrothermal) may reflect proximity to (depth of) large resurgent intrusions. With the exception of the giant Round Mountain epithermal gold deposit, few known caldera-related hydrothermal systems are strongly mineralized. Major middle Cenozoic precious and base metal mineral deposits in and along the margins of the western Nevada volcanic field are mostly related to intrusive rocks that preceded caldera-forming eruptions.

AWSCS-A System to Evaluate Different Approaches for the Automatic Composition and Execution of Web Services Flows

PubMed Central

Tardiole Kuehne, Bruno; Estrella, Julio Cezar; Nunes, Luiz Henrique; Martins de Oliveira, Edvard; Hideo Nakamura, Luis; Gomes Ferreira, Carlos Henrique; Carlucci Santana, Regina Helena; Reiff-Marganiec, Stephan; Santana, Marcos José

2015-01-01

This paper proposes a system named AWSCS (Automatic Web Service Composition System) to evaluate different approaches for automatic composition of Web services, based on QoS parameters that are measured at execution time. The AWSCS is a system to implement different approaches for automatic composition of Web services and also to execute the resulting flows from these approaches. Aiming at demonstrating the results of this paper, a scenario was developed, where empirical flows were built to demonstrate the operation of AWSCS, since algorithms for automatic composition are not readily available to test. The results allow us to study the behaviour of running composite Web services, when flows with the same functionality but different problem-solving strategies were compared. Furthermore, we observed that the influence of the load applied on the running system as the type of load submitted to the system is an important factor to define which approach for the Web service composition can achieve the best performance in production. PMID:26068216

AWSCS-A System to Evaluate Different Approaches for the Automatic Composition and Execution of Web Services Flows.

PubMed

Tardiole Kuehne, Bruno; Estrella, Julio Cezar; Nunes, Luiz Henrique; Martins de Oliveira, Edvard; Hideo Nakamura, Luis; Gomes Ferreira, Carlos Henrique; Carlucci Santana, Regina Helena; Reiff-Marganiec, Stephan; Santana, Marcos José

2015-01-01

This paper proposes a system named AWSCS (Automatic Web Service Composition System) to evaluate different approaches for automatic composition of Web services, based on QoS parameters that are measured at execution time. The AWSCS is a system to implement different approaches for automatic composition of Web services and also to execute the resulting flows from these approaches. Aiming at demonstrating the results of this paper, a scenario was developed, where empirical flows were built to demonstrate the operation of AWSCS, since algorithms for automatic composition are not readily available to test. The results allow us to study the behaviour of running composite Web services, when flows with the same functionality but different problem-solving strategies were compared. Furthermore, we observed that the influence of the load applied on the running system as the type of load submitted to the system is an important factor to define which approach for the Web service composition can achieve the best performance in production.

Mapping Intraplate Volcanic Fields: A Case Study from Harrat Rahat, Saudi Arabia

NASA Astrophysics Data System (ADS)

Downs, D. T.; Stelten, M. E.; Champion, D. E.; Dietterich, H. R.

2017-12-01

Continental intraplate mafic volcanoes are typically small-volume (<1 km3), but are one of the most prevalent volcanic landforms on Earth, particularly in the >200 volcanic fields proposed to be active worldwide during the Holocene. Their small individual eruption volumes make any hazards low, however their high prevalence offsets this by raising the risk to populations and infrastructure. The western Arabian Plate hosts at least 15 continental, intra-plate volcanic fields that stretch >3,000 km south to north from Yemen to Turkey. In total, these volcanic fields comprise one of the largest alkali basalt volcanic provinces on Earth, covering an area of 180,000 km2. With a total volume of 20,000 km3, Harrat Rahat in western Saudi Arabia is one of the largest of these volcanic fields. Our study focused on mapping the northern third of the Harrat Rahat volcanic field using a multidisciplinary approach. We have discriminated >200 individual eruptive units, mainly basaltic lava flows throughout Harrat Rahat that are distinguished through a combination of field observations, petrography, geochemistry, paleomagnetism, and 40Ar/39Ar radiometric and 36Cl cosmogenic surface-exposure dating. We have compiled these results into a high-resolution geologic map, which provides new information about the timing, compositions, and eruptive processes of Quaternary volcanism in Harrat Rahat. For example, prior mapping and geochronology undertaken during the 1980s suggested that the majority of mafic and silicic volcanics erupted during the Miocene and Pliocene, whereas several of the youngest-appearing lava flows were interpreted to be Neolithic ( 7,000 to 4,500 years BP) to post-Neolithic. New mapping and age-constrained stratigraphic relations indicate that all exposed volcanic units within the northern third of Harrat Rahat erupted during the Pleistocene, with the exception of a single Holocene eruption in 1256 AD. This new multidisciplinary mapping is critical for understanding the overall spatial, temporal, and compositional evolution of Harrat Rahat, timescales of magmatic processes in the mantle and crust, and understanding hazards and risks associated with the varied styles of volcanism in the region.

User's guide for the computer code COLTS for calculating the coupled laminar and turbulent flow over a Jovian entry probe

NASA Technical Reports Server (NTRS)

Kumar, A.; Graeves, R. A.

1980-01-01

A user's guide for a computer code 'COLTS' (Coupled Laminar and Turbulent Solutions) is provided which calculates the laminar and turbulent hypersonic flows with radiation and coupled ablation injection past a Jovian entry probe. Time-dependent viscous-shock-layer equations are used to describe the flow field. These equations are solved by an explicit, two-step, time-asymptotic finite-difference method. Eddy viscosity in the turbulent flow is approximated by a two-layer model. In all, 19 chemical species are used to describe the injection of carbon-phenolic ablator in the hydrogen-helium gas mixture. The equilibrium composition of the mixture is determined by a free-energy minimization technique. A detailed frequency dependence of the absorption coefficient for various species is considered to obtain the radiative flux. The code is written for a CDC-CYBER-203 computer and is capable of providing solutions for ablated probe shapes also.

Template-free synthesis of multifunctional carbonaceous microcone forests

NASA Astrophysics Data System (ADS)

Wang, Qiang; Yang, Lei; Dai, Bing; Bai, Jie; Yang, Zhenhuai; Guo, Shuai; He, Yurong; Han, Jiecai; Zhu, Jiaqi

2018-01-01

Forests of vertically aligned carbonaceous microcones are fabricated directly on a nickel mesh by microwave-plasma-assisted chemical vapor deposition. The microstructure is formed through a simple one-step process involving self-assembly. The fabricated composite exhibits superhydrophobicity and superoleophilicity as well as low density, owing to which it floats on water and can be used for the in-situ separation of oil from water at the oil/water interface. Furthermore, the composite exhibits pH responsivity, and its water permeability can be varied simply by altering the pH of the aqueous solution. In addition, the composite is suitable for use as an electrode material for supercapacitors owing to its large geometric surface area, porous structure, and superior electrical properties, which allow for fast ion and electron transportation. Thus, this composite consisting of forests of vertically aligned carbonaceous microcones on a nickel mesh is expected to find use in a wide range of fields and applications, including in environmental cleanup, flow switches, and energy storage devices.

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer

PubMed Central

Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Javadi Pordsari, Alireza; Mehrali, Mohammad; Alengaram, U. Johnson; Jumaat, Mohd Zamin

2016-01-01

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content. PMID:26807825

A Comprehensive Study of the Polypropylene Fiber Reinforced Fly Ash Based Geopolymer.

PubMed

Ranjbar, Navid; Mehrali, Mehdi; Behnia, Arash; Javadi Pordsari, Alireza; Mehrali, Mohammad; Alengaram, U Johnson; Jumaat, Mohd Zamin

2016-01-01

As a cementitious material, geopolymers show a high quasi-brittle behavior and a relatively low fracture energy. To overcome such a weakness, incorporation of fibers to a brittle matrix is a well-known technique to enhance the flexural properties. This study comprehensively evaluates the short and long term impacts of different volume percentages of polypropylene fiber (PPF) reinforcement on fly ash based geopolymer composites. Different characteristics of the composite were compared at fresh state by flow measurement and hardened state by variation of shrinkage over time to assess the response of composites under flexural and compressive load conditions. The fiber-matrix interface, fiber surface and toughening mechanisms were assessed using field emission scan electron microscopy (FESEM) and atomic force microscopy (AFM). The results show that incorporation of PPF up to 3 wt % into the geopolymer paste reduces the shrinkage and enhances the energy absorption of the composites. While, it might reduce the ultimate flexural and compressive strength of the material depending on fiber content.

HDPE/HA composites obtained in solution: Effect of the gamma radiation

NASA Astrophysics Data System (ADS)

Carmen, Albano; Arquímedes, Karam; Rosestela, Perera; Gema, González; Nohemy, Domínguez; Jeanette, González; Yanixia, Sánchez

2006-06-01

Radiation is employed to sterilize composite materials used in the biomedical field. Due to the changes induced by radiation onto polymeric materials, it is important to study variations in their melt flow index (MFI), as well as in their mechanical and thermal properties. In this work, those previous parameters were determined in composites obtained via solution of a high-density polyethylene (HDPE) in decalin, with different amounts of hydroxyapatite (HA), varying from 10 to 30 parts per hundred, after being exposed to gamma radiation at absorbed doses between 25 and 100 kGy. After the irradiation, the MFI of HDPE dissolved in decalin and precipitated afterwards and without filler increased from 6 to 24 g/10 min at the highest absorbed doses. This behavior was also observed in composites with 10 pph of HA, being the increase less pronounced, specifically in the range between 50 and 100 kGy. Composites with 20 and 30 pph of HA showed a maximum MFI value at 50 kGy, which decreased at higher doses. This implies that the filler begin to exert an influence because it does not melt at the test temperature and consequently, it does not flow. It was observed that Young's modulus increased with HA addition due to rigidity of the ceramic filler. Radiation did not significantly affect this tensile property. On the other hand, the tensile strength did not show significant variations at the different doses but the filler content did affect this property improving it. Finally, elongation at break showed a drastic decrease with filler addition. When the thermal behavior was studied it was noticed that crystallization and melting temperatures remained unchanged. Instead, crystallinity degree slightly increased in the composites, and a little decrease was obtained when they were irradiated.

Recent volcanism in the Siqueiros transform fault: Picritic basalts and implications for MORB magma genesis

USGS Publications Warehouse

Perfit, M.R.; Fornari, D.J.; Ridley, W.I.; Kirk, P.D.; Casey, J.; Kastens, K.A.; Reynolds, J.R.; Edwards, M.; Desonie, D.; Shuster, R.; Paradis, S.

1996-01-01

Small constructional volcanic landforms and very fresh-looking lava flows are present along one of the inferred active strike-slip faults that connect two small spreading centers (A and B) in the western portion of the Siqueiros transform domain. The most primitive lavas (picritic and olivine-phyric basalts), exclusively recovered from the young-looking flows within the A-B strike-slip fault, contain millimeter-sized olivine phenocrysts (up to 20 modal%) that have a limited compositional range (Fo91.5-Fo89.5) and complexly zoned Cr-Al spinels. High-MgO (9.5-10.6 wt%) glasses sampled from the young lava flows contain 1-7% olivine phenocrysts (Fo90.5-Fo89) that could have formed by equilibrium crystallization from basaltic melts with Mg# values between 71 and 74. These high MgO (and high Al2O3) glasses may be near-primary melts from incompatible-element depleted oceanic mantle and little modified by crustal mixing and/or fractionation processes. Phase chemistry and major element systematics indicate that the picritic basalts are not primary liquids and formed by the accumulation of olivine and minor spinel from high-MgO melts (10% < MgO < 14%). Compared to typical N-MORB from the East Pacific Rise, the Siqueiros lavas are more primitive and depleted in incompatible elements. Phase equilibria calculations and comparisons with experimental data and trace element modeling support this hypothesis. They indicate such primary mid-ocean ridge basalt magmas formed by 10-18% accumulative decompression melting in the spinel peridotite field (but small amounts of melting in the garnet peridotite field are not precluded). The compositional variations of the primitive magmas may result from the accumulation of different small batch melt fractions from a polybaric melting column.

Bathyphotometer bioluminescence potential measurements: A framework for characterizing flow agitators and predicting flow-stimulated bioluminescence intensity

NASA Astrophysics Data System (ADS)

Latz, Michael I.; Rohr, Jim

2013-07-01

Bathyphotometer measurements of bioluminescence are used as a proxy for the abundance of luminescent organisms for studying population dynamics; the interaction of luminescent organisms with physical, chemical, and biological oceanographic processes; and spatial complexity especially in coastal areas. However, the usefulness of bioluminescence measurements has been limited by the inability to compare results from different bathyphotometer designs, or even the same bathyphotometer operating at different volume flow rates. The primary objective of this study was to compare measurements of stimulated bioluminescence of four species of cultured dinoflagellates, the most common source of bioluminescence in coastal waters, using two different bathyphotometer flow agitators as a function of bathyphotometer volume flow rate and dinoflagellate concentration. For both the NOSC and BIOLITE flow agitators and each species of dinoflagellate tested, there was a critical volume flow rate, above which average bioluminescence intensity, designated as bathyphotometer bioluminescence potential (BBP), remained relatively constant and scaled directly with dinoflagellate cell concentration. At supra-critical volume flow rates, the ratio of BIOLITE to NOSC BBP was nearly constant for the same species studied, but varied between species. The spatial pattern and residence time of flash trajectories within the NOSC flow agitator indicated the presence of dominant secondary recirculating flows, where most of the bioluminescence was detected. A secondary objective (appearing in the Appendix) was to study the feasibility of using NOSC BBP to scale flow-stimulated bioluminescence intensity across similar flow fields, where the contributing composition of luminescent species remained the same. Fully developed turbulent pipe flow was chosen because it is hydrodynamically well characterized. Average bioluminescence intensity in a 2.54-cm i.d. pipe was highly correlated with wall shear stress and BBP. This correlation, when further scaled by pipe diameter, effectively predicted bioluminescence intensity in fully developed turbulent flow in a 0.83-cm i.d. pipe. Determining similar correlations between other bathyphotometer flow agitators and flow fields will allow bioluminescence potential measurements to become a more powerful tool for the oceanographic community.

Morphology, stratigraphy, and surface roughness properties of Venusian lava flow fields

NASA Astrophysics Data System (ADS)

Byrnes, Jeffrey M.; Crown, David A.

2002-10-01

Morphologic characteristics, flow stratigraphy, and radar backscatter properties of five lava flow fields on Venus (Turgmam Fluctus, Zipaltonal Fluctus, Tuli Mons/Uilata Fluctus, Var Mons, and Mylitta Fluctus) were examined to understand flow field emplacement mechanisms and relationships to other surface processes. These analyses indicate that the flow fields studied developed through emplacement of numerous, thin flow units, presumably over extended periods of time. Although the Venusian fields display flow morphologies similar to those observed within terrestrial flow fields, the Venusian flow units are significantly larger and have a larger range of radar backscatter coefficients. Both simple and compound flow emplacement appear to have occurred within the flow fields. A potential correlation between flow rheology and radar brightness is suggested by differences in planform morphology, apparent flow thickness, and apparent sensitivity to topography between bright and dark flows. Distributary flow morphologies may result from tube-fed flows, and postemplacement modification by processes such as flow inflation and crustal foundering is consistent with discrete zones of increased radar brightness within individual flow lobes. Mapping of these flow fields does not indicate any simple evolutionary trend in eruptive/resurfacing style within the flow fields, or any consistent temporal sequence relative to other tectonic and volcanic features.

Influence of microstructure and chemical composition of sputter deposited TiO2 thin films on in vitro bioactivity.

PubMed

Lilja, Mirjam; Genvad, Axel; Astrand, Maria; Strømme, Maria; Enqvist, Håkan

2011-12-01

Functionalisation of biomedical implants via surface modifications for tailored tissue response is a growing field of research. Crystalline TiO(2) has been proven to be a bone bioactive, non-resorbable material. In contact with body fluids a hydroxyapaptite (HA) layer forms on its surface facilitating the bone contact. Thus, the path of improving biomedical implants via deposition of crystalline TiO(2) on the surface is interesting to follow. In this study we have evaluated the influence of microstructure and chemical composition of sputter deposited titanium oxide thin films on the in vitro bioactivity. We find that both substrate bias, topography and the flow ratio of the gases used during sputtering affect the HA layer formed on the films after immersion in simulated body fluid at 37°C. A random distribution of anatase and rutile crystals, formed at negative substrate bias and low Ar to O(2) gas flow ratios, are shown to favor the growth of flat HA crystal structures whereas higher flow ratios and positive substrate bias induced growth of more spherical HA structures. These findings should provide valuable information when optimizing the bioactivity of titanium oxide coatings as well as for tailoring process parameters for sputtered-based production of bioactive titanium oxide implant surfaces.

Precipitation and Hydrology Experiment Counter-Flow Spectrometer and Impactor Field Campaign Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poellot, Michael

The U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility Aerial Facility (ARM AAF) counter-flow spectrometer and impactor (CSI) probe was flown on the University of North Dakota Cessna Citation research aircraft during the Integrated Precipitation and Hydrology Experiment (IPHEX). The field campaign took place during May and June of 2014 over North Carolina and its coastal waters as part of a National Aeronautics and Space Administration (NASA) Global Precipitation Measurement validation campaign. The CSI was added to the Citation instrument suite to support the involvement of Jay Mace through the NASA Advanced Composition Explorer (ACE) satellitemore » program and flights of the NASA ER-2 aircraft, which is a civilian version of the Air Force’s U2-S reconnaissance platform. The ACE program funded extra ER-2 flights to focus on clouds that are weakly precipitating, which are also of interest to the Atmospheric System Research program sponsored by DOE.« less

Genetics and Genomics of Coronary Artery Disease.

PubMed

Pjanic, Milos; Miller, Clint L; Wirka, Robert; Kim, Juyong B; DiRenzo, Daniel M; Quertermous, Thomas

2016-10-01

Coronary artery disease (or coronary heart disease), is the leading cause of mortality in many of the developing as well as the developed countries of the world. Cholesterol-enriched plaques in the heart's blood vessels combined with inflammation lead to the lesion expansion, narrowing of blood vessels, reduced blood flow, and may subsequently cause lesion rupture and a heart attack. Even though several environmental risk factors have been established, such as high LDL-cholesterol, diabetes, and high blood pressure, the underlying genetic composition may substantially modify the disease risk; hence, genome composition and gene-environment interactions may be critical for disease progression. Ongoing scientific efforts have seen substantial advancements related to the fields of genetics and genomics, with the major breakthroughs yet to come. As genomics is the most rapidly advancing field in the life sciences, it is important to present a comprehensive overview of current efforts. Here, we present a summary of various genetic and genomics assays and approaches applied to coronary artery disease research.

Influence of convection on microstructure

NASA Technical Reports Server (NTRS)

Wilcox, William R.; Caram, Rubens; Mohanty, A. P.; Seth, Jayshree

1990-01-01

In eutectic growth, as the solid phases grow they reject atoms to the liquid. This results in a variation of melt composition along the solid/liquid interface. In the past, mass transfer in eutectic solidification, in the absence of convection, was considered to be governed only by the diffusion induced by compositional gradients. However, mass transfer can also be generated by a temperature gradient. This is called thermotransport, thermomigration, thermal diffusion or the Soret effect. A theoretical model of the influence of the Soret effect on the growth of eutectic alloys is presented. A differential equation describing the compositional field near the interface during unidirectional solidification of a binary eutectic alloy was formulated by including the contributions of both compositional and thermal gradients in the liquid. A steady-state solution of the differential equation was obtained by applying appropriate boundary conditions and accounting for heat flow in the melt. Following that, the average interfacial composition was converted to a variation of undercooling at the interface, and consequently to microstructural parameters. The results obtained show that thermotransport can, under certain circumstances, be a parameter of paramount importance.

Dynamics and internal structure of an Alaskan debris-covered glacier from repeat airborne photogrammetry and surface geophysics

NASA Astrophysics Data System (ADS)

Holt, John; Levy, Joseph; Petersen, Eric; Larsen, Chris; Fahnestock, Mark

2016-04-01

Debris-covered glaciers and rock glaciers encompass a range of compositions and activity, and can be useful paleoclimate indicators. They also respond differently to ongoing climate change than glaciers without a protective cover. Their flow dynamics are not well understood, and their unique surface morphologies, including lobate fronts and arcuate ridges, likely result from viscous flow influenced by a combination of composition, structure, and climatic factors. However, basic connections between flow kinematics and surface morphology have not yet been established, limiting our ability to understand these features. In order to begin to address this problem we have undertaken airborne and surface studies of multiple debris-covered glaciers in Alaska and the western U.S. Sourdough Rock Glacier in the St. Elias Mountains, Alaska, is completely debris-covered and exhibits numerous transverse compressional ridges. Its trunk also exhibits highly regular bumps and swales with a wavelength of ~175 m and amplitudes up to 12 m. In the middle trunk, lineations (boulder trains and furrows) bend around a point roughly 200m from the eastern edge. We acquired five high-resolution airborne surveys of Sourdough Rock Glacier between late 2013 and late 2015 using lidar and photogrammetry to assess annual and seasonal change at the sub-meter level. Differencing the DTMs provides vertical change while feature tracking in orthophotos provide horizontal velocities that indicate meters of annual motion. The flow field is highly correlated with surface features; in particular, compressional ridges in the lower lobe. Stranded, formerly active lobes are also apparent. Surface geophysical studies were undertaken to constrain internal structure and composition using a combination of ground-penetrating radar (GPR) at 50 and 100 MHz in six transects, and time-domain electromagnetic (TDEM) measurements at 47 locations, primarily in an along-flow transect and two cross-flow transects. We infer from the GPR and TDEM data that Sourdough Rock Glacier is 40-50 m thick and consists of a core of relatively pure glacier ice preserved under a 2.5-3 m thick debris mantle. In conclusion, Sourdough is actively flowing, with surface velocities that correlate with surface slope and thickness. A bedrock restriction is inferred from bending flow lines, low surface velocities, and localized thinning of the ice. This comprehensive suite of observations provides the potential to model ice flow and to ultimately link details of the surface morphology to accumulation and rheology through flow kinematics and internal structure.

Recurrent eruption and subsidence at the Platoro caldera complex, southeastern San Juan volcanic field, Colorado: New tales from old tuffs

USGS Publications Warehouse

Lipman, P.W.; Dungan, M.A.; Brown, L.L.; Deino, A.

1996-01-01

Reinterpretation of a voluminous regional ash-flow sheet (Masonic Park Tuff) as two separate tuff sheets of similar phenocryst-rich dacite erupted from separate source calderas has important implications for evolution of the multicyclic Platoro caldera complex and for caldera-forming processes generally. Masonic Park Tuff in central parts of the San Juan field, including the type area, was erupted from a concealed source at 28.6 Ma, but widespread tuff previously mapped as Masonic Park Tuff in the southeastern San Juan Mountains is the product of the youngest large-volume eruption of the Platoro caldera complex at 28.4 Ma. This large unit, newly named the "Chiquito Peak Tuff," is the last-erupted tuff of the Treasure Mountain Group, which consists of at least 20 separate ash-flow sheets of dacite to low-silica rhyolite erupted from the Platoro complex during a 1 m.y. interval (29.5-28.4 Ma). Two Treasure Mountain tuff sheets have volumes in excess of 1000 km3 each, and five more have volumes of 50-150 km3. The total volume of ash-flow tuff exceeds 2500 km3, and caldera-related lavas of dominantly andesitic composition make up 250-500 km3 more. A much greater volume of intermediate-composition magma must have solidified in subcaldera magma chambers. Most preserved features of the Platoro complex - including postcollapse asymmetrical trap-door resurgent uplift of the ponded intracaldera tuff and concurrent infilling by andesitic lava flows - postdate eruption of the Chiquito Peak Tuff. The numerous large-volume pre-Chiquito Peak ash-flow tuffs document multiple eruptions accompanied by recurrent subsidence; early-formed caldera walls nearly coincide with margins of the later Chiquito Peak collapse. Repeated syneruptive collapse at the Platoro complex requires cumulative subsidence of at least 10 km. The rapid regeneration of silicic magmas requires the sustained presence of an andesitic subcaldera magma reservoir, or its rapid replenishment, during the 1 m.y. life span of the Platoro complex. Either case implies large-scale stoping and assimilative recycling of the Tertiary section, including intracaldera tuffs.

Influence of ionization on the Gupta and on the Park chemical models

NASA Astrophysics Data System (ADS)

Morsa, Luigi; Zuppardi, Gennaro

2014-12-01

This study is an extension of former works by the present authors, in which the influence of the chemical models by Gupta and by Park was evaluated on thermo-fluid-dynamic parameters in the flow field, including transport coefficients, related characteristic numbers and heat flux on two current capsules (EXPERT and Orion) during the high altitude re-entry path. The results verified that the models, even computing different air compositions in the flow field, compute only slight different compositions on the capsule surface, therefore the difference in the heat flux is not very relevant. In the above mentioned studies, ionization was neglected because the velocities of the capsules (about 5000 m/s for EXPERT and about 7600 m/s for Orion) were not high enough to activate meaningful ionization. The aim of the present work is to evaluate the incidence of ionization, linked to the chemical models by Gupta and by Park, on both heat flux and thermo fluid-dynamic parameters. The present computer tests were carried out by a direct simulation Monte Carlo code (DS2V) in the velocity interval 7600-12000 m/s, considering only the Orion capsule at an altitude of 85 km. The results verified what already found namely when ionization is not considered, the chemical models compute only a slight different gas composition in the core of the shock wave and practically the same composition on the surface therefore the same heat flux. On the opposite, the results verified that when ionization is considered, the chemical models compute different compositions in the whole shock layer and on the surface therefore different heat flux. The analysis of the results relies on a qualitative and a quantitative evaluation of the effects of ionization on both chemical models. The main result of the study is that when ionization is taken into account, the Park model is more reactive than the Gupta model; consequently, the heat flux computed by Park is lower than the one computed by Gupta; using the Gupta model, in the design of a thermal protection system, is recommended.

Application of asymmetric flow field-flow fractionation (AsFlFFF) coupled to inductively coupled plasma mass spectrometry (ICPMS) to the quantitative characterization of natural colloids and synthetic nanoparticles.

PubMed

Bouby, M; Geckeis, H; Geyer, F W

2008-12-01

A straightforward quantification method is presented for the application of asymmetric flow field-flow fractionation (AsFlFFF) combined with inductively coupled plasma mass spectrometry (ICPMS) to the characterization of colloid-borne metal ions and nanoparticles. Reproducibility of the size calibration and recovery of elements are examined. Channel flow fluctuations are observed notably after initiation of the fractionation procedure. Their impact on quantification is considered by using (103)Rh as internal reference. Intensity ratios measured for various elements and Rh are calculated for each data point. These ratios turned out to be independent of the metal concentration and total sample solution flow introduced into the nebulizer within a range of 0.4-1.2 mL min(-1). The method is applied to study the interaction of Eu, U(VI) and Th with a mixture of humic acid and clay colloids and to the characterization of synthetic nanoparticles, namely CdSe/ZnS-MAA (mercaptoacetic acid) core/shell-coated quantum dots (QDs). Information is given not only on inorganic element composition but also on the effective hydrodynamic size under relevant conditions. Detection limits (DLs) are estimated for Ca, Al, Fe, the lanthanide Ce and the natural actinides Th and U in colloid-containing groundwater. For standard crossflow nebulizer, estimated values are 7 x 10(3), 20, 3 x 10(2), 0.1, 0.1 and 7 x 10(-2) microg L(-1), respectively. DLs for Zn and Cd in QD characterization are 28 and 11 microg L(-1), respectively.

Product differentiation during continuous-flow thermal gradient PCR.

PubMed

Crews, Niel; Wittwer, Carl; Palais, Robert; Gale, Bruce

2008-06-01

A continuous-flow PCR microfluidic device was developed in which the target DNA product can be detected and identified during its amplification. This in situ characterization potentially eliminates the requirement for further post-PCR analysis. Multiple small targets have been amplified from human genomic DNA, having sizes of 108, 122, and 134 bp. With a DNA dye in the PCR mixture, the amplification and unique melting behavior of each sample is observed from a single fluorescent image. The melting behavior of the amplifying DNA, which depends on its molecular composition, occurs spatially in the thermal gradient PCR device, and can be observed with an optical resolution of 0.1 degrees C pixel(-1). Since many PCR cycles are within the field of view of the CCD camera, melting analysis can be performed at any cycle that contains a significant quantity of amplicon, thereby eliminating the cycle-selection challenges typically associated with continuous-flow PCR microfluidics.

Modeling of the reactant conversion rate in a turbulent shear flow

NASA Technical Reports Server (NTRS)

Frankel, S. H.; Madnia, C. K.; Givi, P.

1992-01-01

Results are presented of direct numerical simulations (DNS) of spatially developing shear flows under the influence of infinitely fast chemical reactions of the type A + B yields Products. The simulation results are used to construct the compositional structure of the scalar field in a statistical manner. The results of this statistical analysis indicate that the use of a Beta density for the probability density function (PDF) of an appropriate Shvab-Zeldovich mixture fraction provides a very good estimate of the limiting bounds of the reactant conversion rate within the shear layer. This provides a strong justification for the implementation of this density in practical modeling of non-homogeneous turbulent reacting flows. However, the validity of the model cannot be generalized for predictions of higher order statistical quantities. A closed form analytical expression is presented for predicting the maximum rate of reactant conversion in non-homogeneous reacting turbulence.

Effect of river flow fluctuations on riparian vegetation dynamics: Processes and models

NASA Astrophysics Data System (ADS)

Vesipa, Riccardo; Camporeale, Carlo; Ridolfi, Luca

2017-12-01

Several decades of field observations, laboratory experiments and mathematical modelings have demonstrated that the riparian environment is a disturbance-driven ecosystem, and that the main source of disturbance is river flow fluctuations. The focus of the present work has been on the key role that flow fluctuations play in determining the abundance, zonation and species composition of patches of riparian vegetation. To this aim, the scientific literature on the subject, over the last 20 years, has been reviewed. First, the most relevant ecological, morphological and chemical mechanisms induced by river flow fluctuations are described from a process-based perspective. The role of flow variability is discussed for the processes that affect the recruitment of vegetation, the vegetation during its adult life, and the morphological and nutrient dynamics occurring in the riparian habitat. Particular emphasis has been given to studies that were aimed at quantifying the effect of these processes on vegetation, and at linking them to the statistical characteristics of the river hydrology. Second, the advances made, from a modeling point of view, have been considered and discussed. The main models that have been developed to describe the dynamics of riparian vegetation have been presented. Different modeling approaches have been compared, and the corresponding advantages and drawbacks have been pointed out. Finally, attention has been paid to identifying the processes considered by the models, and these processes have been compared with those that have actually been observed or measured in field/laboratory studies.

Linear models for sound from supersonic reacting mixing layers

NASA Astrophysics Data System (ADS)

Chary, P. Shivakanth; Samanta, Arnab

2016-12-01

We perform a linearized reduced-order modeling of the aeroacoustic sound sources in supersonic reacting mixing layers to explore their sensitivities to some of the flow parameters in radiating sound. Specifically, we investigate the role of outer modes as the effective flow compressibility is raised, when some of these are expected to dominate over the traditional Kelvin-Helmholtz (K-H) -type central mode. Although the outer modes are known to be of lesser importance in the near-field mixing, how these radiate to the far-field is uncertain, on which we focus. On keeping the flow compressibility fixed, the outer modes are realized via biasing the respective mean densities of the fast (oxidizer) or slow (fuel) side. Here the mean flows are laminar solutions of two-dimensional compressible boundary layers with an imposed composite (turbulent) spreading rate, which we show to significantly alter the growth of instability waves by saturating them earlier, similar to in nonlinear calculations, achieved here via solving the linear parabolized stability equations. As the flow parameters are varied, instability of the slow modes is shown to be more sensitive to heat release, potentially exceeding equivalent central modes, as these modes yield relatively compact sound sources with lesser spreading of the mixing layer, when compared to the corresponding fast modes. In contrast, the radiated sound seems to be relatively unaffected when the mixture equivalence ratio is varied, except for a lean mixture which is shown to yield a pronounced effect on the slow mode radiation by reducing its modal growth.

Research on the reasonable pile spacing of micro pile composite soil nailing

NASA Astrophysics Data System (ADS)

Liu, Jun yan; Liu, Yan; Song, Xiang hua

2017-08-01

Through the numerical simulation software FLAC3D, study on the synergetic effect of micro pile composite soil nailing will be studied. By adjusting the micro pile spacing and analysing the displacement field and stress field of soil, we can find that supporting effect of the soil nail hasn’t work yet when the micro pile spacing is 2D. The soil arching between piles has been formed in the pile spacing 4D ∼ 6D. The composite effect of micro pile and soil nailing will be the best and the soil arch behind piles will be firstly formed in 6D, the horizontal saddle soil arch will be formed between the nails. The nail head coincidence pressure area and micro pile pressure area are overlapping to maintain stability in the soil between piles. When the micro pile spacing is 9D, the arch behind piles will be failure, the soil flows around, but the saddle arch between the nails into circular arch, the supporting effect of the soil nailing is enhanced. When the micro pile spacing is 12D, the arch of the nails becomes smaller, sliding surface appears primitively. Based on the conclusions above, it is suggested that the micro pile spacing between 2D ∼ 6D is suitable for the micro pile and soil nailing composite support. The conclusion can provide theoretical basis for the design and construction of micro pile composite soil nailing.

Composition Pulse Time-Of-Flight Mass Flow Sensor

DOEpatents

Mosier, Bruce P.; Crocker, Robert W.; Harnett, Cindy K. l

2004-01-13

A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 .mu.L/min) and at pressures at least as great as 10,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined

Electric Field Effects in Self-Propagating High-Temperature Synthesis under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Unuvar, C.; Frederick, D. M.; Shaw, B. D.; Munir, Z. A.

2003-01-01

Self-propagating high-temperature synthesis (SHS) has been used to form many materials. SHS generally involves mixing reactants together (e.g., metal powders) and igniting the mixture such that a combustion (deflagration) wave passes though the mixture. The imposition of an electric field (AC or DC) across SHS reactants has been shown to have a marked effect on the dynamics of wave propagation and on the nature, composition, and homogeneity of the product . The use of an electric field with SHS has been termed "field-assisted SHS". Combustion wave velocities and temperatures are directly affected by the field, which is typically perpendicular to the average wave velocity. The degree of activation by the field (e.g., combustion rate) is related to the current density distribution within the sample, and is therefore related to the temperature-dependent spatial distribution of the effective electrical conductivity of reactants and products. Furthermore, the field can influence other important SHS-related phenomena including capillary flow, mass-transport in porous media, and Marangoni flows. These phenomena are influenced by gravity in conventional SHS processes (i.e., without electric fields). As a result the influence of the field on SHS under reduced gravity is expected to be different than under normal gravity. It is also known that heat loss rates from samples, which can depend significantly on gravity, can influence final products in SHS. This research program is focused on studying field-assisted SHS under reduced gravity conditions. The broad objective of this research program is to understand the role of an electric field in SHS reactions under conditions where gravity-related effects are suppressed. The research will allow increased understanding of fundamental aspects of field-assisted SHS processes as well as synthesis of materials that cannot be formed in normal gravity.

Geochronology and Composition of the 2005-06 Volcanic Eruptions of the East Pacific Rise, 9deg 46'-56'N

NASA Astrophysics Data System (ADS)

Rubin, K. H.; Perfit, M. R.; Fornari, D. J.; Soule, S. A.; Tolstoy, M.; Waldhauser, F.

2006-12-01

Following the discovery of a likely eruption during an ocean bottom seismometer (OBS) recovery cruise (4/06, R/V Knorr), two rapid response cruises (5/06, R/V New Horizon and 6/06 R/V Atlantis) confirmed the new eruptions and observed and sampled newly emplaced sea floor to understand eruption conditions and impacts on hydrothermalism and ecology at the East Pacific Rise (EPR) Ridge2000 ISS near 9° 50'N. We report results of an ongoing effort to obtain high resolution 210Po-210Pb radiometric dates and compositions of young lava sampled on those expeditions, to understand when the eruptive activity occurred, its variation in space and time, and the nature of the magma reservoir(s) involved. The 210Po-210Pb method can produce monthly resolution ages from time series measurements of 210Po activity in volcanic glass after initially being degassed during eruption (Rubin et al., Nature, 1994). All analyses are being conducted on samples distributed throughout the flow field, which extends at least 18 km along the ridge axis from 9° 46'N to 9° 56'N, and includes a significant area of lava extrusion from an off-axis fissure ridge located ~~600m east of the ridge axis in the northern portion of the study area. Final 210Po ages must await the completion of multiple repeat analyses on each sample over ca 1 year, but important age constraints can be estimated by comparing measured (210Po/238U) activity ratio in the lavas with the known (limited) range in (210Pb/238U) in other young, but pre-2005 lava in the area. 210Po ranges by more than a factor of two among 10 samples undergoing analysis, which is greater than can be explained by small chemical variations between the lavas. This implies either that the samples are vastly different in U-series nuclide composition or differ in age by up to two 210Po half-lives (T1/2 = 138.4 days ~4 mos.). Preliminary microprobe, ICP-MS and TIMS-ID analyses indicate that the new lavas are slightly more differentiated than 1991-2 flows from this area, with even more differentiated lavas generally occurring at the southern and northern extremes of the flow field. Parental magma compositions are similar for both eruptions. Therefore, we favor the interpretation that most of the (210Po/238U) variations are age related. Preliminary age estimates have 8 of 10 samples erupting in late summer through autumn 2005, 1 sample erupting in Jan-Feb 2006, and one sample indistinguishable from 1991-92 lava. Such dates are generally consistent with the OBS data, although the microseismicity has its largest pulse in Jan 2006 on the instruments examined thus far and lesser pulses in Oct and Nov 2005. Together with visual observations of subtle sediment cover variations and "young-on-young" flow contacts within the flow field, the data indicate an extended eruption duration (8 ± 4 mos.), similar to the 1991-2 eruption in this area (Haymon et al., EPSL, 1993; Rubin et al., Nature, 1994). (*) additional authors: the Knorr, New Horizon - NH06, and Atlantis - AT15-6 Science parties

Use of a ground-water flow model to delineate contributing areas to the Puchack Well Field, Pennsauken township and vicinity, Camden county, New Jersey

USGS Publications Warehouse

Pope, Daryll A.; Watt, Martha K.

2005-01-01

The New Jersey Department of Environmental Protection (NJDEP) Well Head Protection Program, developed in response to the 1986 Federal Safe Drinking Water Act Amendments, requires delineation of Well Head Protection Areas (WHPA's), commonly called contributing areas, for all public and non-community water-supply wells in New Jersey. Typically, WHPA's for public community water-supply wells in New Jersey are delineated using a two-dimensional ground-water flow model incorporating the regional hydraulic gradient; however, NJDEP guidelines allow for the use of a three-dimensional flow model to delineate contributing areas to wells in complex hydrogeologic settings. The Puchack well field in Pennsauken Township, Camden County, N.J., is an area of strong hydraulic connection between the Lower aquifer of the Potomac-Raritan-Magothy aquifer system and the Delaware River. Interactions among and within the public-supply well fields in the area are complex. To delineate the contributing area to the Puchack well field, the U.S. Geological Survey, in cooperation with the NJDEP, developed an 11-layer ground-water flow model of the Potomac-Raritan-Magothy aquifer system in the Pennsauken Township area to simulate flow in the vicinity of the well field. The model incorporates the interaction between the aquifer system and the Delaware River, and includes boundary flows from an existing regional model of the Camden area. Recharge used in the model ranged from 4.5 to 14 inches per year, and horizontal hydraulic conductivity ranged from 50 to 250 feet per day. Values of vertical hydraulic conductivity ranging from 0.001 to 0.5 feet per day were assigned to zones created on the basis of variations in hydrogeologic conditions observed in geophysical logs from wells. A steady-state simulation was used to calibrate the model to synoptic water-level data collected in March 1998. Near the Puchack well field, simulated heads generally were within 1 foot of the measured heads in both the Middle and Lower aquifers. Simulated water-level differences across the confining units at most of the nested wells were within ? 0.5 feet of the differences calculated from measured water levels. The existing flow model was modified to meet NJDEP guidelines for delineating contributing areas in complex hydrogeologic settings. These modifications included rediscretizing the model grid to a finer grid and preparing the water-use data set for use in the rediscretized model. The contributing area to the Puchack well field was delineated by means of particle tracking. An uncertainty analysis was conducted in which 36 model-input parameters were both increased and decreased until the resulting change in simulated heads exceeded the model-calibration criterion of ? 5 feet at any model cell. Porosity most affected the size and shape of the contributing area. The distribution of withdrawals at the Morris/Delair well field and variations in recharge affected both the size and shape of contributing area to the Puchack well field and the source of water to the Puchack wells. The results of the uncertainty analysis were combined to determine the 'aggregate' contributing area to the Puchack well field--a composite of areas on the land surface that contributed flow to the Puchack well field in less than 12 years in any uncertainty simulation. The shape of the aggregate contributing area was most similar to that associated with a reduction in porosity, which indirectly affected the size and shape of the contributing areas by changing travel time.

Determination of the diffusivity, dispersion, skewness and kurtosis in heterogeneous porous flow. Part I: Analytical solutions with the extended method of moments.

NASA Astrophysics Data System (ADS)

Ginzburg, Irina; Vikhansky, Alexander

2018-05-01

The extended method of moments (EMM) is elaborated in recursive algorithmic form for the prediction of the effective diffusivity, the Taylor dispersion dyadic and the associated longitudinal high-order coefficients in mean-concentration profiles and residence-time distributions. The method applies in any streamwise-periodic stationary d-dimensional velocity field resolved in the piecewise continuous heterogeneous porosity field. It is demonstrated that EMM reduces to the method of moments and the volume-averaging formulation in microscopic velocity field and homogeneous soil, respectively. The EMM simultaneously constructs two systems of moments, the spatial and the temporal, without resorting to solving of the high-order upscaled PDE. At the same time, the EMM is supported with the reconstruction of distribution from its moments, allowing to visualize the deviation from the classical ADE solution. The EMM can be handled by any linear advection-diffusion solver with explicit mass-source and diffusive-flux jump condition on the solid boundary and permeable interface. The prediction of the first four moments is decisive in the optimization of the dispersion, asymmetry, peakedness and heavy-tails of the solute distributions, through an adequate design of the composite materials, wetlands, chemical devices or oil recovery. The symbolic solutions for dispersion, skewness and kurtosis are constructed in basic configurations: diffusion process and Darcy flow through two porous blocks in "series", straight and radial Poiseuille flow, porous flow governed by the Stokes-Brinkman-Darcy channel equation and a fracture surrounded by penetrable diffusive matrix or embedded in porous flow. We examine the moments dependency upon porosity contrast, aspect ratio, Péclet and Darcy numbers, but also for their response on the effective Brinkman viscosity applied in flow modeling. Two numerical Lattice Boltzmann algorithms, a direct solver of the microscopic ADE in heterogeneous structure and a novel scheme for EMM numerical formulation, are called for validation of the constructed analytical predictions.

Predicting membrane flux decline from complex mixtures using flow-field flow fractionation measurements and semi-empirical theory.

PubMed

Pellegrino, J; Wright, S; Ranvill, J; Amy, G

2005-01-01

Flow-Field Flow Fractionation (FI-FFF) is an idealization of the cross flow membrane filtration process in that, (1) the filtration flux and crossflow velocity are constant from beginning to end of the device, (2) the process is a relatively well-defined laminar-flow hydrodynamic condition, and (3) the solutes are introduced as a pulse-input that spreads due to interactions with each other and the membrane in the dilute-solution limit. We have investigated the potential for relating FI-FFF measurements to membrane fouling. An advection-dispersion transport model was used to provide 'ideal' (defined as spherical, non-interacting solutes) solute residence time distributions (RTDs) for comparison with 'real' RTDs obtained experimentally at different cross-field velocities and solution ionic strength. An RTD moment analysis based on a particle diameter probability density function was used to extract "effective" characteristic properties, rather than uniquely defined characteristics, of the standard solute mixture. A semi-empirical unsteady-state, flux decline model was developed that uses solute property parameters. Three modes of flux decline are included: (1) concentration polarization, (2) cake buildup, and (3) adsorption on/in pores, We have used this model to test the hypothesis-that an analysis of a residence time distribution using FI-FFF can describe 'effective' solute properties or indices that can be related to membrane flux decline in crossflow membrane filtration. Constant flux filtration studies included the changes of transport hydrodynamics (solvent flux to solute back diffusion (J/k) ratios), solution ionic strength, and feed water composition for filtration using a regenerated cellulose ultrafiltration membrane. Tests of the modeling hypothesis were compared with experimental results from the filtration measurements using several correction parameters based on the mean and variance of the solute RTDs. The corrections used to modify the boundary layer mass transfer coefficient and the specific resistance of cake or adsorption layers demonstrated that RTD analysis is potentially useful technique to describe colloid properties but requires improvements.

Top-down and bottom-up lipidomic analysis of rabbit lipoproteins under different metabolic conditions using flow field-flow fractionation, nanoflow liquid chromatography and mass spectrometry.

PubMed

Byeon, Seul Kee; Kim, Jin Yong; Lee, Ju Yong; Chung, Bong Chul; Seo, Hong Seog; Moon, Myeong Hee

2015-07-31

This study demonstrated the performances of top-down and bottom-up approaches in lipidomic analysis of lipoproteins from rabbits raised under different metabolic conditions: healthy controls, carrageenan-induced inflammation, dehydration, high cholesterol (HC) diet, and highest cholesterol diet with inflammation (HCI). In the bottom-up approach, the high density lipoproteins (HDL) and the low density lipoproteins (LDL) were size-sorted and collected on a semi-preparative scale using a multiplexed hollow fiber flow field-flow fractionation (MxHF5), followed by nanoflow liquid chromatography-ESI-MS/MS (nLC-ESI-MS/MS) analysis of the lipids extracted from each lipoprotein fraction. In the top-down method, size-fractionated lipoproteins were directly infused to MS for quantitative analysis of targeted lipids using chip-type asymmetrical flow field-flow fractionation-electrospray ionization-tandem mass spectrometry (cAF4-ESI-MS/MS) in selected reaction monitoring (SRM) mode. The comprehensive bottom-up analysis yielded 122 and 104 lipids from HDL and LDL, respectively. Rabbits within the HC and HCI groups had lipid patterns that contrasted most substantially from those of controls, suggesting that HC diet significantly alters the lipid composition of lipoproteins. Among the identified lipids, 20 lipid species that exhibited large differences (>10-fold) were selected as targets for the top-down quantitative analysis in order to compare the results with those from the bottom-up method. Statistical comparison of the results from the two methods revealed that the results were not significantly different for most of the selected species, except for those species with only small differences in concentration between groups. The current study demonstrated that top-down lipid analysis using cAF4-ESI-MS/MS is a powerful high-speed analytical platform for targeted lipidomic analysis that does not require the extraction of lipids from blood samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Controls on Lava Flow Morphology and Propagation: Using Laboratory Analogue Experiments

NASA Astrophysics Data System (ADS)

Peters, S.; Clarke, A. B.

2017-12-01

The morphology of lava flows is controlled by eruption rate, composition, cooling rate, and topography [Fink and Griffiths, 1990; Gregg and Fink, 2000, 2006]. Lava flows are used to understand how volcanoes, volcanic fields, and igneous provinces formed and evolved [Gregg and Fink., 1996; Sheth, 2006]. This is particularly important for other planets where compositional data is limited and historical context is nonexistent. Numerical modeling of lava flows remains challenging, but has been aided by laboratory analog experiments [Gregg and Keszrthelyi, 2004; Soule and Cashman, 2004]. Experiments using polyethylene glycol (PEG) 600 wax have been performed to understand lava flow emplacement [Fink and Griffiths, 1990, 1992; Gregg and Fink, 2000]. These experiments established psi (hereafter denoted by Ψ), a dimensionless parameter that relates crust formation and advection timescales of a viscous gravity current. Four primary flow morphologies corresponding to discreet Ψ ranges were observed. Gregg and Fink [2000] also investigated flows on slopes and found that steeper slopes increase the effective effusion rate producing predicted morphologies at lower Ψ values. Additional work is needed to constrain the Ψ parameter space, evaluate the predictive capability of Ψ, and determine if the preserved flow morphology can be used to indicate the initial flow conditions. We performed 514 experiments to address the following controls on lava flow morphology: slope (n = 282), unsteadiness/pulsations (n = 58), slope & unsteadiness/pulsations (n = 174), distal processes, and emplacement vs. post-emplacement morphologies. Our slope experiments reveal a similar trend to Gregg and Fink [2000] with the caveat that very high and very low local & source eruption rates can reduce the apparent predictive capability of Ψ. Predicted Ψ morphologies were often produced halfway through the eruption. Our pulse experiments are expected to produce morphologies unique to each eruption rate and promote tube formation and compound flows. Post-emplacement morphologies are modified by a variety of factors (e.g. solidification, deflation), which may not preserve the initial morphology produced during an eruption. Relating this morphology to the eruption conditions is pertinent to understanding the evolution of planetary surfaces.

Eruption Recurrence Rates and Compositional Variability of Discrete Lava Flows on the S-EPR from 238U-230Th-226Ra- 210Pb-232Th

NASA Astrophysics Data System (ADS)

Rubin, K. H.; Smith, M. C.; Sinton, J. M.; Sacks, L. F.; Bergmanis, E.

2001-12-01

Quantification of the absolute ages and geochemistry of individual seafloor lava flows provides important constraints on the magmatic processes responsible for building the oceanic crust. Here we present new 238U-230Th-226Ra-210Pb radioactive disequilibrium age constraints (decadal to millennial time scale) for 3 mid-ocean ridge lava flows at 17° 26'S on the East Pacific Rise (EPR): Aldo-Kihi, Rehu-Marka, and a neighboring unnamed flow. Our continuing study using high-resolution surveys and manned-submersible sampling (NAUDUR, 1993, and STOWA, 1991, expeditions) has previously shown that Aldo-Kihi is compositionally variable, is probably one of the youngest axial lavas in the 17° -19° S region, and was most likely erupted from a series of fissures extending >18 km along the ridge axis (Sinton et al., JGR, in revision). Rehu Marka has a more trace element enriched and evolved composition. The strongest age constraints in our U-series data set are from the 210Pb-226Ra (half-life = 22.3 yrs) and 226Ra-230Th (half life = 1600 yrs) systems. 210Pb-226Ra disequilibrium (as 5-7% Pb deficits) is common in lavas from our S-EPR study area and slightly lower than disequilibria we have measured in lavas erupted in 1991 and 1992 at 9° 50'N EPR. Although we are still developing our understanding of how this disequilibrium arises in MORB (e.g., how the radioactive "clock" is set for this isotope pair) a number of features of our preliminary data support the idea that these lavas are very young and that geologically observed contact relationships in the field separate the products of chronologically distinguishable eruptions. Also, the extent of 226Ra-210Pb disequilibrium in 3 Aldo-Kihi samples compared to that observed at 9° 50'N indicates that the Aldo-Kihi lava probably erupted within the last 10-20 yrs, and the higher but still <1 (210Pb/226Ra) activity ratio in a lava sampled near to but outside the boundaries of Aldo-Kihi indicates it is slightly older, but probably only by a decade or so. Although the older lava's major element composition is very similar to Aldo-Kihi, it has distinct U-Th-Ra chemistry, indicating it is from a different parental magma. Finally, the compositionally very distinct Rehu Marka flow just to the north has no 226Ra-210Pb disequilibrium, indicating it is likely older than the maximum resolvable age with this method (100-120 years). An age estimate (about 750 yrs) of the latter can be made from its 226Ra excess. Together, these preliminary age constraints provide insight into eruption recurrence rates and the processes that allow for preservation of compositional variability within proximally located (in space and time) lava flows along this magmatically robust segment of the EPR.

A composition joint PDF method for the modeling of spray flames

NASA Technical Reports Server (NTRS)

Raju, M. S.

1995-01-01

This viewgraph presentation discusses an extension of the probability density function (PDF) method to the modeling of spray flames to evaluate the limitations and capabilities of this method in the modeling of gas-turbine combustor flows. The comparisons show that the general features of the flowfield are correctly predicted by the present solution procedure. The present solution appears to provide a better representation of the temperature field, particularly, in the reverse-velocity zone. The overpredictions in the centerline velocity could be attributed to the following reasons: (1) the use of k-epsilon turbulence model is known to be less precise in highly swirling flows and (2) the swirl number used here is reported to be estimated rather than measured.

Osmotic contribution to the flow-driven tube formation of copper-phosphate and copper-silicate chemical gardens.

PubMed

Rauscher, Evelin; Schuszter, Gábor; Bohner, Bíborka; Tóth, Ágota; Horváth, Dezső

2018-02-21

We have produced hollow copper-containing precipitate tubes using a flow-injection technique, and characterized their linear and volume growth. It is shown that the ratio of the volume increase rate to that of pumping is constant independent of the chemical composition. It is also found that osmosis significantly contributes to the tube growth, since the inward flux of chemical species dominates during the precipitate pattern formation. The asymmetric hydrodynamic field coupled with the inherent concentration and pH gradients results in different particle morphology on the two sides of the precipitate membrane. While the tubes have a smooth outer surface, the inner walls are covered with nanoflowers for copper phosphate and with nanoballs for copper silicate.

Ionospheres of the terrestrial planets

NASA Astrophysics Data System (ADS)

Schunk, R. W.; Nagy, A. F.

1980-11-01

The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth, and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionospheres, the relevant observations, and the most recent model calculations. The theory section includes a discussion of ambipolar diffusion in a partially ionized plasma, diffusion in a fully ionized plasma, supersonic plasma flow, photochemistry, and heating and cooling processes. The sections on observations and model calculations cover the neutral atmosphere composition, the ion composition, the electron density, and the electron, ion, and neutral temperatures.

Noise reduction of a composite cylinder subjected to random acoustic excitation

NASA Technical Reports Server (NTRS)

Grosveld, Ferdinand W.; Beyer, T.

1989-01-01

Interior and exterior noise measurements were conducted on a stiffened composite floor-equipped cylinder, with and without an interior trim installed. Noise reduction was obtained for the case of random acoustic excitation in a diffuse field; the frequency range of interest was 100-800-Hz one-third octave bands. The measured data were compared with noise reduction predictions from the Propeller Aircraft Interior Noise (PAIN) program and from a statistical energy analysis. Structural model parameters were not predicted well by the PAIN program for the given input parameters; this resulted in incorrect noise reduction predictions for the lower one-third octave bands where the power flow into the interior of the cylinder was predicted on a mode-per-mode basis.

Preparation and characterization of chitosan/Aloe Vera composite nanofibers generated by electrostatic spinning

NASA Astrophysics Data System (ADS)

Ibrahim, Illani; Sekak, Khairunnadim Ahmad; Hasbullah, Norazurean

2015-08-01

Researches on the fabrication of nanostructured based membrane have attracted great attention amongst scientists due to their wide potential applications on medical application. In this work, Chitosan and Aloe Vera sol-gel solution were electrospun using 20 kV DC supply at room temperature. Morphological structure and functional group of nanofibers were characterized using field emission scanning electron microscopy (FESEM) and Fourier-transform infrared spectroscopy (FT-IR) respectively. The optimum parameter obtained at 90% concentration of acetic acid, 0.3 ml/h of solution flow rate and 10 cm distance of nozzle to collector. The fiber diameters were analyzed using the ImageJ software. Average diameters of the Chitosan/Aloe Vera composite nanofibers is 183nm in ranges of 140-260nm.

Novel Methods of Determining Urinary Calculi Composition: Petrographic Thin Sectioning of Calculi and Nanoscale Flow Cytometry Urinalysis

PubMed Central

Gavin, Carson T; Ali, Sohrab N; Tailly, Thomas; Olvera-Posada, Daniel; Alenezi, Husain; Power, Nicholas E; Hou, Jinqiang; St. Amant, Andre H; Luyt, Leonard G; Wood, Stephen; Wu, Charles; Razvi, Hassan; Leong, Hon S

2016-01-01

Accurate determination of urinary stone composition has significant bearing on understanding pathophysiology, choosing treatment modalities and preventing recurrence. A need exists for improved methods to determine stone composition. Urine of 31 patients with known renal calculi was examined with nanoscale flow cytometry and the calculi collected during surgery subsequently underwent petrographic thin sectioning with polarized and fluorescent microscopy. Fluorescently labeled bisphosphonate probes (Alendronate-fluorescein/Alendronate-Cy5) were developed for nanoscale flow cytometry to enumerate nanocrystals that bound the fluorescent probes. Petrographic sections of stones were also imaged by fluorescent and polarized light microscopy with composition analysis correlated to alendronate +ve nanocrystal counts in corresponding urine samples. Urine samples from patients with Ca2+ and Mg2+ based calculi exhibited the highest alendronate +ve nanocrystal counts, ranging from 100–1000 nm in diameter. This novel urine based assay was in agreement with composition determined by petrographic thin sections with Alendronate probes. In some cases, high alendronate +ve nanocrystal counts indicated a Ca2+ or Mg2+ composition, as confirmed by petrographic analysis, overturning initial spectrophotometric diagnosis of stone composition. The combination of nanoscale flow cytometry and petrographic thin sections offer an alternative means for determining stone composition. Nanoscale flow cytometry of alendronate +ve nanocrystals alone may provide a high-throughput means of evaluating stone burden. PMID:26771074

Experimental Study of Soil Organic Matter Loss From Cultivated Field Plots In The Venezuelan Andes.

NASA Astrophysics Data System (ADS)

Bellanger, B.; Huon, S.; Velasquez, F.; Vallès, V.; Girardin A, C.; Mariotti, A. B.

The question of discriminating sources of organic matter in suspended particles of stream flows can be addressed by using total organic carbon (TOC) concentration and stable isotope (13C, 15N) measurements when constant fluxes of organic matter supply can be assumed. However, little is known on the dynamics of organic matter release during soil erosion and on the temporal stability of its isotopic signature. In this study, we have monitored soil organic carbon loss and water runoff using natural rainfall events on three experimental field plots with different vegetation cover (bare soil, maize and coffee fields), set up on natural slopes of a tropical mountainous watershed in NW Venezuela (09°13'32'' ­ 09°10'00''N, 70°13'49'' ­ 70°18'34''W). Runoff and soil loss are markedly superior for the bare field plot than for the coffee field plot: by a factor 15 ­ 36, respectively, for the five-month experiment, and by a factor 30 ­ 120, respectively, during a single rainfall event experiment. Since runoff and soil organic matter loss are closely linked during most of the flow (at the time scales of this study), TOC concentration in suspended matter is constant. Furthermore, stable isotope compositions reflect those of top-soil organic matter from which they originate.

Logarithmic violation of scaling in strongly anisotropic turbulent transfer of a passive vector field

NASA Astrophysics Data System (ADS)

Antonov, N. V.; Gulitskiy, N. M.

2015-01-01

Inertial-range asymptotic behavior of a vector (e.g., magnetic) field, passively advected by a strongly anisotropic turbulent flow, is studied by means of the field-theoretic renormalization group and the operator product expansion. The advecting velocity field is Gaussian, not correlated in time, with the pair correlation function of the form ∝δ (t -t') /k⊥d -1 +ξ , where k⊥=|k⊥| and k⊥ is the component of the wave vector, perpendicular to the distinguished direction ("direction of the flow")—the d -dimensional generalization of the ensemble introduced by Avellaneda and Majda [Commun. Math. Phys. 131, 381 (1990), 10.1007/BF02161420]. The stochastic advection-diffusion equation for the transverse (divergence-free) vector field includes, as special cases, the kinematic dynamo model for magnetohydrodynamic turbulence and the linearized Navier-Stokes equation. In contrast to the well-known isotropic Kraichnan's model, where various correlation functions exhibit anomalous scaling behavior with infinite sets of anomalous exponents, here the dependence on the integral turbulence scale L has a logarithmic behavior: Instead of powerlike corrections to ordinary scaling, determined by naive (canonical) dimensions, the anomalies manifest themselves as polynomials of logarithms of L . The key point is that the matrices of scaling dimensions of the relevant families of composite operators appear nilpotent and cannot be diagonalized. The detailed proof of this fact is given for the correlation functions of arbitrary order.

Morphologic and thermophysical characteristics of lava flows southwest of Arsia Mons, Mars

NASA Astrophysics Data System (ADS)

Crown, David A.; Ramsey, Michael S.

2017-08-01

The morphologic and thermophysical characteristics of part of the extensive lava flow fields southwest of Arsia Mons (22.5-27.5°S, 120-130°W) have been examined using a combination of orbital VNIR and TIR datasets. THEMIS images provide context for the regional geology and record diurnal temperature variability that is diverse and unusual for flow surfaces in such close proximity. CTX images were used to distinguish dominant flow types and assess local age relationships between individual lava flows. CTX and HiRISE images provide detailed information on flow surface textures and document aeolian effects as they reveal fine-grained deposits in many low-lying areas of the flow surfaces as well as small patches of transverse aeolian ridges. Although this region is generally dust-covered and has a lower overall thermal inertia, the THEMIS data indicate subtle spectral variations within the population of lava flows studied. These variations could be due to compositional differences among the flows or related to mixing of flow and aeolian materials. Specific results regarding flow morphology include: a) Two main lava flow types (bright, rugged and dark, smooth as observed in CTX images) dominate the southwest Arsia Mons/NE Daedalia Planum region; b) the bright, rugged flows have knobby, ridged, and/or platy surface textures, commonly have medial channel/levee systems, and may have broad distal lobes; c) the dark, smooth flows extend from distributary systems that consist of combinations of lava channels, lava tubes, and/or sinuous ridges and plateaus; and d) steep-sided, terraced margins, digitate breakout lobes, and smooth-surfaced plateaus along lava channel/tube systems are interpreted as signatures of flow inflation within the dark, smooth flow type. These flows exhibit smoother upper surfaces, are thinner, and have more numerous, smaller lobes, which, along with their the channel-/tube-fed nature, indicate a lower viscosity lava than for the bright, rugged flows. Flow patterns and local interfingering and overlapping relationships are delineated in CTX images and allow reconstruction of the complex flow field surfaces. Darker channel-/tube-fed flows are generally younger than adjacent thicker, bright, rugged flows; however, the diversity and complexity of temporal relationships observed, along with the thermophysical variability, suggests that lava sources with different eruptive styles and magnitudes and/or lavas that experienced different local emplacement conditions were active contemporaneously.

Thermal conductivity of aerogel blanket insulation under cryogenic-vacuum conditions in different gas environments

NASA Astrophysics Data System (ADS)

E Fesmire, J.; Ancipink, J. B.; Swanger, A. M.; White, S.; Yarbrough, D.

2017-12-01

Thermal conductivity of low-density materials in thermal insulation systems varies dramatically with the environment: cold vacuum pressure, residual gas composition, and boundary temperatures. Using a reference material of aerogel composite blanket (reinforcement fibers surrounded by silica aerogel), an experimental basis for the physical heat transmission model of aerogel composites and other low-density, porous materials is suggested. Cryogenic-vacuum testing between the boundary temperatures of 78 K and 293 K is performed using a one meter cylindrical, absolute heat flow calorimeter with an aerogel blanket specimen exposed to different gas environments of nitrogen, helium, argon, or CO2. Cold vacuum pressures include the full range from 1×10-5 torr to 760 torr. The soft vacuum region, from about 0.1 torr to 10 torr, is complex and difficult to model because all modes of heat transfer - solid conduction, radiation, gas conduction, and convection - are significant contributors to the total heat flow. Therefore, the soft vacuum tests are emphasized for both heat transfer analysis and practical thermal data. Results for the aerogel composite blanket are analyzed and compared to data for its component materials. With the new thermal conductivity data, future applications of aerogel-based insulation systems are also surveyed. These include Mars exploration and surface systems in the 5 torr CO2 environment, field joints for vacuum-jacketed cryogenic piping systems, common bulkhead panels for cryogenic tanks on space launch vehicles, and liquid hydrogen cryofuel systems with helium purged conduits or enclosures.

Is formation segregation melts in basaltic lava flows a viable analogue to melt generation in basaltic systems?

NASA Astrophysics Data System (ADS)

Thordarson, Thorvaldur; Sigmarsson, Olgeir; Hartley, Margaret E.; Miller, Jay

2010-05-01

Pahoehoe sheet lobes commonly exhibit a three-fold structural division into upper crust, core and lower crust, where the core corresponds to the liquid portion of an active lobe sealed by crust. Segregations are common in pahoehoe lavas and are confined to the core of individual lobes. Field relations and volume considerations indicate that segregation is initiated by generation of volatile-rich melt at or near the lower crust to core boundary via in-situ crystallization. Once buoyant, the segregated melt rises through the core during last stages of flow emplacement and accumulates at the base of the upper crust. The segregated melt is preserved as vesicular and aphyric, material within well-defined vesicle cylinders and horizontal vesicle sheets that make up 1-4% of the total lobe volume. We have undertaken a detailed sampling and chemical analysis of segregations and their host lava from three pahoehoe flow fields; two in Iceland and one in the Columbia River Basalt Group (CRBG). The Icelandic examples are: the olivine-tholeiite Thjorsa lava (24 cubic km) of the Bardarbunga-Veidivotn volcanic system and mildly alkalic Surtsey lavas (1.2 cubic km) of the Vestmannaeyjar volcanic system. The CRBG example is the tholeiitic ‘high-MgO group' Levering lava (>100? cubic km) of the N2 Grande Ronde Basalt. The thicknesses of the sampled lobes ranges from 2.3 to 14 m and each lobe feature well developed network of segregation structures [1,2,3]. Our whole-rock analyses show that the segregated melt is significantly more evolved than the host lava, with enrichment factors of 1.25 (Thjorsa) to 2.25 (Surtsey) for incompatible trace elements (Ba, Zr). Calculations indicate that the segregation melt was formed by 20 to 50% closed-system fractional crystallization of plagioclase (plus minor pyroxene and/or olivine). A more striking feature is the whole-rock composition of the segregations. In the olivine-tholeiite Thjorsa lava the segregations exhibit quartz tholeiite composition that is identical to the magma compositions produced by the nearby Grimsvotn and Kverkfjoll volcanic systems during the Holocene. The Surtsey segregations have whole-rock composition remarkably similar to the FeTi basalts from adjacent Katla volcanic system, whereas the segregations of the Levering flow are identical to the ‘low-MgO group' basalts of the CRBG. Is this a coincidence or does volatile induced liquid transfer, as inferred for the formation of the segregations, play an important role in magma differentiation in basaltic systems? [1]Thordarson & Self The Roza Member, Columbia River Basalt Group. J Geophys Res - Solid Earth [2] Sigmarsson, et al, 2009. Segregations in Surtsey lavas (Iceland). In Studies in Volcanology: The Legacy of George Walker. Special Publication of IAVCEI No 3. [3] Hartley & Thordarson, 2009, Melt segregations in a Columbia River Basalt lava flow. Lithos

Controlled synthesis of germanium nanoparticles by nonthermal plasmas

NASA Astrophysics Data System (ADS)

Ahadi, Amir Mohammad; Hunter, Katharine I.; Kramer, Nicolaas J.; Strunskus, Thomas; Kersten, Holger; Faupel, Franz; Kortshagen, Uwe R.

2016-02-01

The size, composition, and crystallinity of plasma produced nanoparticles are crucial factors for their physical and chemical properties. Here, we investigate the role of the process gas composition, particularly the hydrogen (H2) flow rate, on germanium (Ge) nanoparticles synthesized from a chlorinated precursor by nonthermal plasma. We demonstrate that the gas composition can significantly change the nanoparticle size and also adjust the surface chemistry by altering the dominant reaction mechanisms. A red shift of the Ge-Clx infrared absorptions with increasing H2 flow indicates a weakening of the Ge-Clx bonds at high H2 content. Furthermore, by changing the gas composition, the nanoparticles microstructure can be controlled from mostly amorphous at high hydrogen flow to diamond cubic crystalline at low hydrogen flow.

Investigation of local environments in Nafion-SiO(2) composite membranes used in vanadium redox flow batteries.

PubMed

Vijayakumar, M; Schwenzer, Birgit; Kim, Soowhan; Yang, Zhenguo; Thevuthasan, S; Liu, Jun; Graff, Gordon L; Hu, Jianzhi

2012-04-01

Proton conducting polymer composite membranes are of technological interest in many energy devices such as fuel cells and redox flow batteries. In particular, polymer composite membranes, such as SiO(2) incorporated Nafion membranes, are recently reported as highly promising for the use in redox flow batteries. However, there is conflicting reports regarding the performance of this type of Nafion-SiO(2) composite membrane in the redox flow cell. This paper presents results of the analysis of the Nafion-SiO(2) composite membrane used in a vanadium redox flow battery by nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier Transform Infra Red (FTIR) spectroscopy, and ultraviolet-visible spectroscopy. The XPS study reveals the chemical identity and environment of vanadium cations accumulated at the surface. On the other hand, the (19)F and (29)Si NMR measurement explores the nature of the interaction between the silica particles, Nafion side chains and diffused vanadium cations. The (29)Si NMR shows that the silica particles interact via hydrogen bonds with the sulfonic groups of Nafion and the diffused vanadium cations. Based on these spectroscopic studies, the chemical environment of the silica particles inside the Nafion membrane and their interaction with diffusing vanadium cations during flow cell operations are discussed. This study discusses the origin of performance degradation of the Nafion-SiO(2) composite membrane materials in vanadium redox flow batteries. Copyright © 2011 Elsevier Inc. All rights reserved.

Investigation of Local Environments in Nafion-SiO2 Composite Membranes used in Vanadium Redox Flow Batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayakumar, M.; Schwenzer, Birgit; Kim, Soowhan

2012-04-01

The proton conducting polymer composite membranes are of technological interest in many energy devices such as fuel cells and redox flow batteries. In particular, the polymer composite membranes such as SiO2 incorporated Nafion membranes are recently reported as highly promising for the redox flow batteries. However, there is conflicting reports regarding the performance of this Nafion-SiO2 composite membrane in the redox flow cell. This paper presents results of the analysis of the Nafion-SiO2 composite membrane used in a vanadium redox flow battery by nuclear magnetic resonance (NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier Transformed Infra Red (FTIR) spectroscopy, and ultravioletmore » visible spectroscopy. The XPS study reveals the chemical identity and environment of vanadium cations accumulated at the surface. On the other hand, the 19F and 29Si NMR measurement explores the nature of the interaction between the silica particles, Nafion side chains and diffused vanadium cations. The 29Si NMR shows that the silica particles interaction via hydrogen bonds to the sulfonic groups of Nafion and diffused vanadium cations. Based on these spectroscopic studies, the chemical environment of the silica particles inside the Nafion membrane and their interaction with diffusing vanadium cations during flow cell operations are discussed. This study discusses the origin of performance degradation of the Nafion-SiO2 composite membrane materials in vanadium redox flow batteries.« less

On the propagation of hydromagnetic waves in a plasma of thermal and suprathermal components

NASA Astrophysics Data System (ADS)

Kumar, Nagendra; Sikka, Himanshu

2007-12-01

The propagation of MHD waves is studied when two ideal fluids, thermal and suprathermal gases, coupled by magnetic field are moving with the steady flow velocity. The fluids move independently in a direction perpendicular to the magnetic field but gets coupled along the field. Due to the presence of flow in suprathermal and thermal fluids there appears forward and backward waves. All the forward and backward modes propagate in such a way that their rate of change of phase speed with the thermal Mach number is same. It is also found that besides the usual hydromagnetic modes there appears a suprathermal mode which propagates with faster speed. Surface waves are also examined on an interface formed with composite plasma (suprathermal and thermal gases) on one side and the other is a non-magnetized plasma. In this case, the modes obtained are two or three depending on whether the sound velocity in thermal gas is equal to or greater than the sound velocity in suprathermal gas. The results lead to the conclusion that the interaction of thermal and suprathermal components may lead to the occurrence of an additional mode called suprathermal mode whose phase velocity is higher than all the other modes.

A novel composite conductive microfiltration membrane and its anti-fouling performance with an external electric field in membrane bioreactors

PubMed Central

Huang, Jian; Wang, Zhiwei; Zhang, Junyao; Zhang, Xingran; Ma, Jinxing; Wu, Zhichao

2015-01-01

Membrane fouling remains an obstacle to wide-spread applications of membrane bioreactors (MBRs) for wastewater treatment and reclamation. Herein, we report a simple method to prepare a composite conductive microfiltration (MF) membrane by introducing a stainless steel mesh into a polymeric MF membrane and to effectively control its fouling by applying an external electric field. Linear sweep voltammetry and electrochemical impedance spectroscopy analyses showed that this conductive membrane had very good electrochemical properties. Batch tests demonstrated its anti-fouling ability in filtration of bovine serum albumin, sodium alginate, humic acid and silicon dioxide particles as model foulants. The fouling rate in continuous-flow MBRs treating wastewater was also decreased by about 50% for this conductive membrane with 2 V/cm electric field compared to the control test during long-term operation. The enhanced electrostatic repulsive force between foulants and membrane, in-situ cleaning by H2O2 generated from oxygen reduction, and decreased production of soluble microbial products and extracellular polymeric substances contributed to fouling mitigation in this MBR. The results of this study shed light on the control strategy of membrane fouling for achieving a sustainable operation of MBRs. PMID:25784160

Extensive lava flow fields on Venus: Preliminary investigation of source elevation and regional slope variations

NASA Technical Reports Server (NTRS)

Magee-Roberts, K.; Head, James W., III; Lancaster, M. G.

1992-01-01

Large-volume lava flow fields have been identified on Venus, the most areally extensive of which are known as fluctus and have been subdivided into six morphologic types. Sheetlike flow fields (Type 1) lack the numerous, closely spaced, discrete lava flow lobes that characterize digitate flow fields. Transitional flow fields (Type 2) are similar to sheetlike flow fields but contain one or more broad flow lobes. Digitate flow fields are divided further into divergent (Types 3-5) and subparallel (Type 6) classes on the basis of variations in the amount of downstream flow divergence. As a result of our previous analysis of the detailed morphology, stratigraphy, and tectonic associations of Mylitta Fluctus, we have formulated a number of questions to apply to all large flow fields on Venus. In particular, we would like to address the following: (1) eruption conditions and style of flow emplacement (effusion rate, eruption duration), (2) the nature of magma storage zones (presence of neutral buoyancy zones, deep or shallow crustal magma chambers), (3) the origin of melt and possible link to mantle plumes, and (4) the importance of large flow fields in plains evolution. To answer these questions we have begun to examine variations in flow field dimension and morphology; the distribution of large flow fields in terms of elevation above the mean planetary radius; links to regional tectonic or volcanic structures (e.g., associations with large shield edifices, coronae, or rift zones); statigraphic relationships between large flow fields, volcanic plains, shields, and coronae; and various models of flow emplacement in order to estimate eruption parameters. In this particular study, we have examined the proximal elevations and topographic slopes of 16 of the most distinctive flow fields that represent each of the 6 morphologic types.

Upper Mammoth Polarity Transition Recorded in the Pu'u Kualakauila volcanic sequence, Wai'anae Volcano, Oahu, Hawaii USA: Paleomagnetic and 40Ar/39Ar Evidence

NASA Astrophysics Data System (ADS)

Lau, J. K.; Herrero-Bervera, E.; Jicha, B.; Valet, J.

2013-12-01

New paleomagnetic measurements, coupled with Argon-Argon (40Ar/39Ar) radioisotopic dating, are revolutionizing our understanding of the geodynamo by providing detailed terrestrial lava records of the short-term behavior of the paleomagnetic field. As part of an investigation of the Wai'anae Volcano, Oahu, and the short-term behavior of the geomagnetic field, we have sampled a long volcanic section located on the volcano's collapsed flank at a locality known as Pu'u Kaulakauila. Prior paleomagnetic investigations of the Kamaile'unu Volcanic Series (i.e. Herrero-Bervera and Valet, 2005) revealed transitional directions. The silicic composition of lava flows, easy access, and close geographical proximity to K-Ar dated flows made this newly studied 214-m thick sequence of flows an excellent candidate for detailed paleomagnetic analysis. At least eight samples, collected from each of 45 successive flow sites, were stepwise demagnetized by both alternating field (5 mT to 100 mT) and thermal (from 28 °C to 575-650 °C) methods. Mean directions were obtained by principal component analysis. All samples yielded a strong and stable ChRM trending towards the origin of vector demagnetization diagrams based on seven or more demagnetization steps, with thermal and AF results differing insignificantly. Low-field susceptibility vs. temperature (k-T) analysis conducted on individual lava flows indicated approximately half with reversible curves. Curie point determinations from these analyses revealed a temperature close to or equal to 580 °C, indicative of almost pure magnetite ranging from single domain (SD) to pseudosingle domain (PSD) grain sizes for most of the flows. The mean directions of magnetization of the entire section sampled indicate a reversed polarity, with ˜10 m of the section characterized by excursional directions (5 lava flows). Thellier-Coe and microwave paleointensities determinations of these flows indicate a substantial decrease of the absolute paleointensity before and during the transition and a progressive increase of it during the recovery phase of the transition. The corresponding VGPs are located on the western part of Australia. 40Ar/39Ar incremental heating experiments on groundmass from transitional flow sites at different stratigraphic levels yields a weighted mean age of 3.233×0.088 Ma, which, combined with the overall reversed polarity and two older polarity reversals, strongly suggests that the transitional lavas correspond to the Upper Mammoth polarity transition.

Rheology of composite solid propellants during motor casting

NASA Technical Reports Server (NTRS)

Rogers, C. J.; Smith, P. L.; Klager, K.

1978-01-01

In a study conducted to evaluate flow parameters of uncured solid composite propellants during motor casting, two motors (1.8M-lb grain wt) were cast with a PBAN propellant exhibiting good flow characteristics in a 260-in. dia solid rocket motor. Attention is given to the effects of propellant compositional and processing variables on apparent viscosity as they pertain to rheological behavior and grain defect formation during casting. It is noted that optimized flow behavior is impaired with solid propellant loading. Non-Newtonian pseudoplastic flow is observed, which is dependent upon applied shear stress and the age of the uncured propellant.

Monitoring riparian-vegetation composition and cover along the Colorado River downstream of Glen Canyon Dam, Arizona

USGS Publications Warehouse

Palmquist, Emily C.; Ralston, Barbara E.; Sarr, Daniel A.; Johnson, Taylor C.

2018-06-05

Vegetation in the riparian zone (the area immediately adjacent to streams, such as stream banks) along the Colorado River downstream of Glen Canyon Dam, Arizona, supports many ecosystem and societal functions. In both Glen Canyon and Grand Canyon, this ecosystem has changed over time in response to flow alterations, invasive species, and recreational use. Riparian-vegetation cover and composition are likely to continue to change as these pressures persist and new ones emerge. Because this system is a valuable resource that is known to change in response to flow regime and other disturbances, a long-term monitoring protocol has been designed with three primary objectives:Annually measure and summarize the status (composition and cover) of native and non-native vascular-plant species within the riparian zone of the Colorado River between Glen Canyon Dam and Lake Mead.At 5-year intervals, assess change in vegetation composition and cover in the riparian zone, as related to geomorphic setting and dam operations, particularly flow regime.Collect data in a manner that can be used by multiple stakeholders, particularly the basinwide monitoring program overseen by the National Park Service’s Northern Colorado Plateau Network Inventory and Monitoring program.A protocol for the long-term monitoring of riparian vegetation is described in detail and standard operating procedures are included herein for all tasks. Visual estimates of foliar and ground covers are collected in conjunction with environmental measurements to assess correlations of foliar cover with abiotic and flow variables. Sample quadrats are stratified by frequency of inundation, geomorphic feature, and by river segment to account for differences in vegetation type. Photographs of sites are also taken to illustrate qualitative characteristics of the site at the time of sampling. Procedures for field preparation, generating random samples, data collection, data management, collecting and managing unknown species collections, and reporting are also described. Although this protocol is intended to be consistent over the long-term, procedures for minor and major revisions to the protocol are also outlined.

Using high-resolution satellite radar to measure lava flow morphology, rheology, effusion rate and subsidence at El Reventador Volcano, Ecuador.

NASA Astrophysics Data System (ADS)

Biggs, J.; Arnold, D. W. D.; Mothes, P. A.; Anderson, K. R.; Albino, F.; Wadge, G.; Vallejo Vargas, S.; Ebmeier, S. K.

2017-12-01

There are relatively few studies of active lava flows of an andesitic rather than basaltic composition. The flow field at El Reventador volcano, Ecuador is a good example, but observations are hampered by persistent cloud cover. We use high resolution satellite radar from Radarsat-2 and TanDEM-X to map the dimensions of 43 lava flows extruded between 9 Feb 2012 and 24 Aug 2016. Flow height is measured using the width of radar shadow cast by steep sided features, or the difference in radar phase between two sensors separated in space. The cumulative volume of erupted material was 44.8M m3 dense rock equivalent with an average rate of 0.31 ± 0.02 m3s-1, similar to the long term average. The flows were mostly emplaced over durations shorter than the satellite repeat interval of 24 days and ranged in length from 0.3 to 1.7 km. We use the dimensions of the levees to estimate the flow yield strengths and compare measurements of diversions around barriers with observations from laboratory experiments. The rate of effusion, flow length and flow volume all decrease with time, and simple physics-based models can be equally well fit by a closed reservoir depressurising during the eruption with no magma recharge, or an open reservoir with a time-constant magma recharge rate of up to 0.35 ± 0.01 m3s-1. We propose that the conduit acts as magma capacitor and individual flows are volume-limited. Emplaced flows are subsiding at rates proportional to lava thickness that decay with time following a square-root relationship. Radar observations, such as those presented here, could be used to map and measure properties of evolving lava flow fields at other remote or difficult to monitor volcanoes. Physics-based models can be run into the future, but a sudden increase in flow length in 2017 seen by Sentinel illustrates that changes in magma supply can cause rapid changes in behavior, which remain challenging to forecast.

Creativity and Flow in Musical Composition: An Empirical Investigation

ERIC Educational Resources Information Center

MacDonald, Raymond; Byrne, Charles; Carlton, Lana

2006-01-01

Although an extensive literature exists on creativity and music, there is a lack of published research investigating possible links between musical creativity and Csikszentmihalyi's concept of flow or optimal experience. This article examines a group composition task to study the relationships between creativity, flow and the quality of the…

Generation of a composite grid for turbine flows and consideration of a numerical scheme

NASA Technical Reports Server (NTRS)

Choo, Y.; Yoon, S.; Reno, C.

1986-01-01

A composite grid was generated for flows in turbines. It consisted of the C-grid (or O-grid) in the immediate vicinity of the blade and the H-grid in the middle of the blade passage between the C-grids and in the upstream region. This new composite grid provides better smoothness, resolution, and orthogonality than any single grid for a typical turbine blade with a large camber and rounded leading and trailing edges. The C-H (or O-H) composite grid has an unusual grid point that is connected to more than four neighboring nodes in two dimensions (more than six neighboring nodes in three dimensions). A finite-volume lower-upper (LU) implicit scheme to be used on this grid poses no problem and requires no special treatment because each interior cell of this composite grid has only four neighboring cells in two dimensions (six cells in three dimensions). The LU implicit scheme was demonstrated to be efficient and robust for external flows in a broad flow regime and can be easily applied to internal flows and extended from two to three dimensions.

Method of producing exfoliated graphite composite compositions for fuel cell flow field plates

DOEpatents

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z

2014-04-08

A method of producing an electrically conductive composite composition, which is particularly useful for fuel cell bipolar plate applications. The method comprises: (a) providing a supply of expandable graphite powder; (b) providing a supply of a non-expandable powder component comprising a binder or matrix material; (c) blending the expandable graphite with the non-expandable powder component to form a powder mixture wherein the non-expandable powder component is in the amount of between 3% and 60% by weight based on the total weight of the powder mixture; (d) exposing the powder mixture to a temperature sufficient for exfoliating the expandable graphite to obtain a compressible mixture comprising expanded graphite worms and the non-expandable component; (e) compressing the compressible mixture at a pressure within the range of from about 5 psi to about 50,000 psi in predetermined directions into predetermined forms of cohered graphite composite compact; and (f) treating the so-formed cohered graphite composite to activate the binder or matrix material thereby promoting adhesion within the compact to produce the desired composite composition. Preferably, the non-expandable powder component further comprises an isotropy-promoting agent such as non-expandable graphite particles. Further preferably, step (e) comprises compressing the mixture in at least two directions. The method leads to composite plates with exceptionally high thickness-direction electrical conductivity.

A Composite Medium Approximation for Moisture Tension-Dependent Anisotropy in Unsaturated Layered Sediments

NASA Astrophysics Data System (ADS)

Pruess, K.

2001-12-01

Sedimentary formations often have a layered structure in which hydrogeologic properties have substantially larger correlation length in the bedding plane than perpendicular to it. Laboratory and field experiments and observations have shown that even small-scale layering, down to millimeter-size laminations, can substantially alter and impede the downward migration of infiltrating liquids, while enhancing lateral flow. The fundamental mechanism is that of a capillary barrier: at increasingly negative moisture tension (capillary suction pressure), coarse-grained layers with large pores desaturate more quickly than finer-grained media. This strongly reduces the hydraulic conductivity of the coarser (higher saturated hydraulic conductivity) layers, which then act as barriers to downward flow, forcing water to accumulate and spread near the bottom of the overlying finer-grained material. We present a "composite medium approximation" (COMA) for anisotropic flow behavior on a typical grid block scale (0.1 - 1 m or larger) in finite-difference models. On this scale the medium is conceptualized as consisting of homogeneous horizontal layers with uniform thickness, and capillary equilibrium is assumed to prevail locally. Directionally-dependent relative permeabilities are obtained by considering horizontal flow to proceed via "conductors in parallel," while vertical flow involves "resistors in series." The model is formulated for the general case of N layers, and implementation of a simplified two-layer (fine-coarse) approximation in the multiphase flow simulator TOUGH2 is described. The accuracy of COMA is evaluated by comparing numerical simulations of plume migration in 1-D and 2-D unsaturated flow with results of fine-grid simulations in which all layers are discretized explicitly. Applications to water seepage and solute transport at the Hanford site are also described. This work was supported by the U.S. Department of Energy under Contract No. DE-AC03-76SF00098 through Memorandum Purchase Order 248861-A-B2 between Pacific Northwest National Laboratory and Lawrence Berkeley National Laboratory.

A novel method to detect unlabeled inorganic nanoparticles and submicron particles in tissue by sedimentation field-flow fractionation

PubMed Central

Deering, Cassandra E; Tadjiki, Soheyl; Assemi, Shoeleh; Miller, Jan D; Yost, Garold S; Veranth, John M

2008-01-01

A novel methodology to detect unlabeled inorganic nanoparticles was experimentally demonstrated using a mixture of nano-sized (70 nm) and submicron (250 nm) silicon dioxide particles added to mammalian tissue. The size and concentration of environmentally relevant inorganic particles in a tissue sample can be determined by a procedure consisting of matrix digestion, particle recovery by centrifugation, size separation by sedimentation field-flow fractionation (SdFFF), and detection by light scattering. Background Laboratory nanoparticles that have been labeled by fluorescence, radioactivity, or rare elements have provided important information regarding nanoparticle uptake and translocation, but most nanomaterials that are commercially produced for industrial and consumer applications do not contain a specific label. Methods Both nitric acid digestion and enzyme digestion were tested with liver and lung tissue as well as with cultured cells. Tissue processing with a mixture of protease enzymes is preferred because it is applicable to a wide range of particle compositions. Samples were visualized via fluorescence microscopy and transmission electron microscopy to validate the SdFFF results. We describe in detail the tissue preparation procedures and discuss method sensitivity compared to reported levels of nanoparticles in vivo. Conclusion Tissue digestion and SdFFF complement existing techniques by precisely identifying unlabeled metal oxide nanoparticles and unambiguously distinguishing nanoparticles (diameter<100 nm) from both soluble compounds and from larger particles of the same nominal elemental composition. This is an exciting capability that can facilitate epidemiological and toxicological research on natural and manufactured nanomaterials. PMID:19055780

Sedimentation field-flow fractionation for characterization of citric acid-modified Hβ zeolite particles: Effect of particle dispersion and carrier composition.

PubMed

Dou, Haiyang; Bai, Guoyi; Ding, Liang; Li, Yueqiu; Lee, Seungho

2015-11-27

In this study, sedimentation field-flow fractionation (SdFFF) was, for the first time, applied for determination of size distribution of Hβ zeolite particles modified by citric acid (CA-Hβ). Effects of the particle dispersion and the carrier liquid composition (type of dispersing reagent (surfactant) and salt added in the carrier liquid, ionic strength, and pH) on SdFFF elution behavior of CA-Hβ zeolite particles were systematically investigated. Also the SdFFF separation efficiency of the particles was discussed in terms of the forces such as van der Waals, hydrophobic, and induced-dipole interactions. Results reveal that the type of salt and pH of the carrier liquid significantly affect the SdFFF separation efficiency of the zeolite particles. It was found that addition of a salt (NaN3) into the carrier liquid affects the characteristic of the SdFFF channel surface. It was found that the use of an acidic medium (pH 3.2) leads to a particle-channel interaction, while the use of a basic medium (pH 10.6) promotes an inter-particle hydrophobic interaction. Result from SdFFF was compared with those from scanning electron microscopy (SEM) and dynamic light scattering (DLS). It seems that, once the experimental conditions are optimized, SdFFF becomes a valuable tool for size characterization of the zeolite particles. Copyright © 2015 Elsevier B.V. All rights reserved.

The Quaternary and Pliocene Yellowstone Plateau volcanic field of Wyoming, Idaho, and Montana

USGS Publications Warehouse

Christiansen, Robert L.

2001-01-01

This region of Yellowstone National Park has been the active focus of one of the Earth's largest magmatic systems for more than 2 million years. The resulting volcanism has been characterized by the eruption of voluminous rhyolites and subordinate basalts but virtually no lavas of intermediate composition. The magmatic system at depth remains active and drives the massive hydrothermal circulation for which the park is widely known. Studies of the volcanic field using geologic mapping and petrology have defined three major cycles of rhyolitic volcanism, each climaxed by the eruption of a rhyolitic ash-flow sheet having a volume of hundreds of thousands of cubic kilometers. The field also has been analyzed in terms of its magmatic and tectonic evolution, including its regional relation to the Snake River plain and to basin-range tectonic extension.

Cutting through the smoke: the diversity of microorganisms in deep-sea hydrothermal plumes.

PubMed

Djurhuus, Anni; Mikalsen, Svein-Ole; Giebel, Helge-Ansgar; Rogers, Alex D

2017-04-01

There are still notable gaps regarding the detailed distribution of microorganisms between and within insular habitats such as deep-sea hydrothermal vents. This study investigates the community composition of black smoker vent microorganisms in the Southern Hemisphere, and changes thereof along a spatial and chemical gradient ranging from the vent plume to surrounding waters. We sampled two hydrothermal vent fields, one at the South West Indian Ridge (SWIR), the other at the East Scotia Ridge (ESR). Samples were collected across vent fields at varying vertical distances from the origin of the plumes. The microbial data were sequenced on an Illumina MiSeq platform for the 16SrRNA gene. A substantial amount of vent-specific putative chemosynthetic microorganisms were found, particularly in samples from focused hydrothermal venting. Common vent-specific organisms from both vent fields were the genera Arcobacter , Caminibacter and Sulfurimonas from the Epsilonproteobacteria and the SUP05 group from the Gammaproteobacteria. There were no major differences in microbial composition between SWIR and ESR for focused plume samples. However, within the ESR the diffuse flow and focused samples differed significantly in microbial community composition and relative abundance. For Epsilonproteobacteria, we found evidence of niche-specificity to hydrothermal vent environments. This taxon decreased in abundance by three orders of magnitude from the vent orifice to background water. Epsilonproteobacteria distribution followed a distance-decay relationship as vent-effluents mixed with the surrounding seawater. This study demonstrates strong habitat affinity of vent microorganisms on a metre scale with distinct environmental selection.

Optimization and evaluation of asymmetric flow field-flow fractionation of silver nanoparticles.

PubMed

Loeschner, Katrin; Navratilova, Jana; Legros, Samuel; Wagner, Stephan; Grombe, Ringo; Snell, James; von der Kammer, Frank; Larsen, Erik H

2013-01-11

Asymmetric flow field-flow fractionation (AF(4)) in combination with on-line optical detection and mass spectrometry is one of the most promising methods for separation and quantification of nanoparticles (NPs) in complex matrices including food. However, to obtain meaningful results regarding especially the NP size distribution a number of parameters influencing the separation need to be optimized. This paper describes the development of a separation method for polyvinylpyrrolidone-stabilized silver nanoparticles (AgNPs) in aqueous suspension. Carrier liquid composition, membrane material, cross flow rate and spacer height were shown to have a significant influence on the recoveries and retention times of the nanoparticles. Focus time and focus flow rate were optimized with regard to minimum elution of AgNPs in the void volume. The developed method was successfully tested for injected masses of AgNPs from 0.2 to 5.0 μg. The on-line combination of AF(4) with detection methods including ICP-MS, light absorbance and light scattering was helpful because each detector provided different types of information about the eluting NP fraction. Differences in the time-resolved appearance of the signals obtained by the three detection methods were explained based on the physical origin of the signal. Two different approaches for conversion of retention times of AgNPs to their corresponding sizes and size distributions were tested and compared, namely size calibration with polystyrene nanoparticles (PSNPs) and calculations of size based on AF(4) theory. Fraction collection followed by transmission electron microscopy was performed to confirm the obtained size distributions and to obtain further information regarding the AgNP shape. Characteristics of the absorbance spectra were used to confirm the presence of non-spherical AgNP. Copyright © 2012 Elsevier B.V. All rights reserved.

Composition pulse time-of-flight mass flow sensor

DOEpatents

Harnett, Cindy K [Livermore, CA; Crocker, Robert W [Fremont, CA; Mosier, Bruce P [San Francisco, CA; Caton, Pamela F [Berkeley, CA; Stamps, James F [Livermore, CA

2007-06-05

A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 .mu.L/min) and at pressures at least as great as 2,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined. A pair of spaced apart electrodes can be used to produce the electrochemical pulse. In those instances where it is desired to measure a wide range of fluid flow rates a three electrode configuration in which the electrodes are spaced at unequal distances has been found to be desirable.

Quantum dot agglomerates in biological media and their characterization by asymmetrical flow field-flow fractionation.

PubMed

Moquin, Alexandre; Neibert, Kevin D; Maysinger, Dusica; Winnik, Françoise M

2015-01-01

The molecular composition of the biological environment of nanoparticles influences their physical properties and changes their pristine physicochemical identity. In order to understand, or predict, the interactions of cells with specific nanoparticles, it is critical to know their size, shape, and agglomeration state not only in their nascent state but also in biological media. Here, we use asymmetrical flow field-flow fractionation (AF4) with on-line multiangle light scattering (MALS), dynamic light scattering (DLS) and UV-Visible absorption detections to determine the relative concentration of isolated nanoparticles and agglomerates in the case of three types of semi-conductor quantum dots (QDs) dispersed in Dulbecco's Modified Eagle Media (DMEM) containing 10% of fetal bovine serum (DMEM-FBS). AF4 analysis also yielded the size and size distribution of the agglomerates as a function of the time of QDs incubation in DMEM-FBS. The preferred modes of internalization of the QDs are assessed for three cell-types, N9 microglia, human hepatocellular carcinoma cells (HepG2) and human embryonic kidney cells (Hek293), by confocal fluorescence imaging of live cells, quantitative determination of the intracellular QD concentration, and flow cytometry. There is an excellent correlation between the agglomeration status of the three types of QDs in DMEM-FBS determined by AF4 analysis and their preferred mode of uptake by the three cell lines, which suggests that AF4 yields an accurate description of the nanoparticles as they encounter cells and advocates its use as a means to characterize particles under evaluation. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of wing flexibility on sound generation of flapping wings.

PubMed

Geng, Biao; Xue, Qian; Zheng, Xudong; Liu, Geng; Ren, Yan; Dong, Haibo

2017-12-13

In this study, the unsteady flow and acoustic characteristics of a three-dimensional (3D) flapping wing model of a Tibicen linnei cicada in forward-flight are numerically investigated. A single cicada wing is modelled as a membrane with a prescribed motion reconstructed from high-speed videos of a live insect. The numerical solution takes a hydrodynamic/acoustic splitting approach: the flow field is solved with an incompressible Navier-Stokes flow solver based on an immersed boundary method, and the acoustic field is solved with linearized perturbed compressible equations. The 3D simulation allows for the examination of both the directivity and frequency compositions of the flapping wing sound in a full space. Along with the flexible wing model, a rigid wing model that is extracted from real motion is also simulated to investigate the effects of wing flexibility. The simulation results show that the flapping sound is directional; the dominant frequency varies around the wing. The first and second frequency harmonics show different radiation patterns in the rigid and flexible wing cases, which are demonstrated to be highly associated with wing kinematics and loadings. Furthermore, the rotation and deformation in the flexible wing is found to help lower the sound strength in all directions.

Heat flow, morphology, pore fluids and hydrothermal circulation in a typical Mid-Atlantic Ridge flank near Oceanographer Fracture Zone

NASA Astrophysics Data System (ADS)

Le Gal, V.; Lucazeau, F.; Cannat, M.; Poort, J.; Monnin, C.; Battani, A.; Fontaine, F.; Goutorbe, B.; Rolandone, F.; Poitou, C.; Blanc-Valleron, M.-M.; Piedade, A.; Hipólito, A.

2018-01-01

Hydrothermal circulation affects heat and mass transfers in the oceanic lithosphere, not only at the ridge axis but also on their flanks, where the magnitude of this process has been related to sediment blanket and seamounts density. This was documented in several areas of the Pacific Ocean by heat flow measurements and pore water analysis. However, as the morphology of Atlantic and Indian ridge flanks is generally rougher than in the Pacific, these regions of slow and ultra-slow accretion may be affected by hydrothermal processes of different regimes. We carried out a survey of two regions on the eastern and western flanks of the Mid-Atlantic Ridge between Oceanographer and Hayes fracture zones. Two hundred and eight new heat flow measurements were obtained along six seismic profiles, on 5 to 14 Ma old seafloor. Thirty sediment cores (from which porewaters have been extracted) have been collected with a Kullenberg corer equipped with thermistors thus allowing simultaneous heat flow measurement. Most heat flow values are lower than those predicted by purely conductive cooling models, with some local variations and exceptions: heat flow values on the eastern flank of the study area are more variable than on the western flank, where they tend to increase westward as the sedimentary cover in the basins becomes thicker and more continuous. Heat flow is also higher, on average, on the northern sides of both the western and eastern field regions and includes values close to conductive predictions near the Oceanographer Fracture Zone. All the sediment porewaters have a chemical composition similar to that of bottom seawater (no anomaly linked to fluid circulation has been detected). Heat flow values and pore fluid compositions are consistent with fluid circulation in volcanic rocks below the sediment. The short distances between seamounts and short fluid pathways explain that fluids flowing in the basaltic aquifer below the sediment have remained cool and unaltered. Finally, relief at small-scale is calculated using variogram of bathymetry and compared for different regions affected by hydrothermal circulation.

A Submarine Perspective on Hawaiian Volcanoes

NASA Astrophysics Data System (ADS)

Clague, D. A.; Moore, J. G.

2011-12-01

Postwar improvements in navigation, sonar-based mapping, and submarine photography enabled the development of bathymetric maps, which revealed submarine morphologic features that could be dredged or explored and sampled with a new generation of manned and unmanned submersibles. The maps revealed debris fields from giant landslides, the great extent of rift zones radiating from volcanic centers, and two previously unknown submarine volcanoes named Mahukona and Loihi, the youngest Hawaiian volcano. About 70 major landslides cover half the flanks of the Hawaiian Ridge out to Midway Island. Some of the landslides attain lengths of 200 km and have volumes exceeding 5,000 km3. More recent higher resolution bathymetry and sidescan data reveal that many submarine eruptions construct circular, flat-topped, monogenetic cones; that large fields of young strongly alkalic lava flows, such as the North Arch and South Arch lava fields, erupt on the seafloor within several hundred km of the islands; and that alkalic lavas erupt during the shield stage on Kilauea and Mauna Loa. The North Arch flow field covers about 24,000 km2, has an estimated volume between about 1000 and 1250 km3, has flows as long as 108 km, and erupted from over 100 vents. The source and melting mechanisms for their production is still debated. The maps also displayed stair-step terraces, mostly constructed of drowned coral reefs, which form during early rapid subsidence of the volcanoes during periods of oscillating sea level. The combination of scuba and underwater photography facilitated the first motion pictures of the mechanism of formation of pillow lava in shallow water offshore Kilauea. The age progression known from the main islands was extended westward along the Hawaiian Ridge past Midway Island, around a bend in the chain and northward along the Emperor Seamounts. Radiometric dating of dredged samples from these submarine volcanoes show that the magma source that built the chain has been active for over 80 Ma and established the remarkable linearity of the age-progression along the chain. Glass rinds on submarine lava quenched at depth contain initial magmatic volatiles and yield data on the juvenile water, sulfur, CO2, and rare gas contents of basaltic magmas, and continue to reveal nuances of the volatile contents of lava. Rock sampling at Loihi Seamount led to the discovery of the pre-shield alkalic phase of Hawaiian volcanism, which mirrors the well-known post-shield alkalic phase. Lava compositions from the Hawaiian Ridge and Emperor Seamounts have clear affinities to present-day Hawaiian lavas, but subtle source differences as well. The progression from small to large and back to small degrees of melting at individual volcanoes and the compositional changes along the chain constrain the melting processes and source compositions of Hawaiian volcanism. Coupling the age of lavas with that of submerged coral reefs has provided data on the growth and subsidence of volcanic centers. This information has meshed nicely with the age, composition, and morphology of lavas from the 3.2-km-deep Hawaiian Scientific Drill Hole. Submarine studies have taught us much about the workings of Hawaiian Volcanoes, and in the process have stimulated new work and concepts on marine volcanism worldwide.

Improved 3-D turbomachinery CFD algorithm

NASA Technical Reports Server (NTRS)

Janus, J. Mark; Whitfield, David L.

1988-01-01

The building blocks of a computer algorithm developed for the time-accurate flow analysis of rotating machines are described. The flow model is a finite volume method utilizing a high resolution approximate Riemann solver for interface flux definitions. This block LU implicit numerical scheme possesses apparent unconditional stability. Multi-block composite gridding is used to orderly partition the field into a specified arrangement. Block interfaces, including dynamic interfaces, are treated such as to mimic interior block communication. Special attention is given to the reduction of in-core memory requirements by placing the burden on secondary storage media. Broad applicability is implied, although the results presented are restricted to that of an even blade count configuration. Several other configurations are presently under investigation, the results of which will appear in subsequent publications.

Viscous and gravitational fingering in multiphase compositional and compressible flow

NASA Astrophysics Data System (ADS)

Moortgat, Joachim

2016-03-01

Viscous and gravitational fingering refer to flow instabilities in porous media that are triggered by adverse mobility or density ratios, respectively. These instabilities have been studied extensively in the past for (1) single-phase flow (e.g., contaminant transport in groundwater, first-contact-miscible displacement of oil by gas in hydrocarbon production), and (2) multi-phase immiscible and incompressible flow (e.g., water-alternating-gas (WAG) injection in oil reservoirs). Fingering in multiphase compositional and compressible flow has received much less attention, perhaps due to its high computational complexity. However, many important subsurface processes involve multiple phases that exchange species. Examples are carbon sequestration in saline aquifers and enhanced oil recovery (EOR) by gas or WAG injection below the minimum miscibility pressure. In multiphase flow, relative permeabilities affect the mobility contrast for a given viscosity ratio. Phase behavior can also change local fluid properties, which can either enhance or mitigate viscous and gravitational instabilities. This work presents a detailed study of fingering behavior in compositional multiphase flow in two and three dimensions and considers the effects of (1) Fickian diffusion, (2) mechanical dispersion, (3) flow rates, (4) domain size and geometry, (5) formation heterogeneities, (6) gravity, and (7) relative permeabilities. Results show that fingering in compositional multiphase flow is profoundly different from miscible conditions and upscaling techniques used for the latter case are unlikely to be generalizable to the former.

Miocene magmatism in the Bodie Hills volcanic field, California and Nevada: A long-lived eruptive center in the southern segment of the ancestral Cascades arc

USGS Publications Warehouse

John, David A.; du Bray, Edward A.; Blakely, Richard J.; Fleck, Robert J.; Vikre, Peter; Box, Stephen E.; Moring, Barry C.

2012-01-01

The Middle to Late Miocene Bodie Hills volcanic field is a >700 km2, long-lived (∼9 Ma) but episodic eruptive center in the southern segment of the ancestral Cascades arc north of Mono Lake (California, U.S.). It consists of ∼20 major eruptive units, including 4 trachyandesite stratovolcanoes emplaced along the margins of the field, and numerous, more centrally located silicic trachyandesite to rhyolite flow dome complexes. Bodie Hills volcanism was episodic with two peak periods of eruptive activity: an early period ca. 14.7–12.9 Ma that mostly formed trachyandesite stratovolcanoes and a later period between ca. 9.2 and 8.0 Ma dominated by large trachyandesite-dacite dome fields. A final period of small silicic dome emplacement occurred ca. 6 Ma. Aeromagnetic and gravity data suggest that many of the Miocene volcanoes have shallow plutonic roots that extend to depths ≥1–2 km below the surface, and much of the Bodie Hills may be underlain by low-density plutons presumably related to Miocene volcanism.Compositions of Bodie Hills volcanic rocks vary from ∼50 to 78 wt% SiO2, although rocks with <55 wt% SiO2 are rare. They form a high-K calc-alkaline series with pronounced negative Ti-P-Nb-Ta anomalies and high Ba/Nb, Ba/Ta, and La/Nb typical of subduction-related continental margin arcs. Most Bodie Hills rocks are porphyritic, commonly containing 15–35 vol% phenocrysts of plagioclase, pyroxene, and hornblende ± biotite. The oldest eruptive units have the most mafic compositions, but volcanic rocks oscillated between mafic and intermediate to felsic compositions through time. Following a 2 Ma hiatus in volcanism, postsubduction rocks of the ca. 3.6–0.1 Ma, bimodal, high-K Aurora volcanic field erupted unconformably onto rocks of the Miocene Bodie Hills volcanic field.At the latitude of the Bodie Hills, subduction of the Farallon plate is inferred to have ended ca. 10 Ma, evolving to a transform plate margin. However, volcanism in the region continued until 8 Ma without an apparent change in rock composition or style of eruption. Equidimensional, polygenetic volcanoes and the absence of dike swarms suggest a low differential horizontal stress regime throughout the lifespan of the Bodie Hills volcanic field. However, kinematic data for veins and faults in mining districts suggest a change in the stress field from transtensional to extensional approximately coincident with the inferred cessation of subduction.Numerous hydrothermal systems were operative in the Bodie Hills during the Miocene. Several large systems caused alteration of volcaniclastic rocks in areas as large as 30 km2, but these altered rocks are mostly devoid of economic mineral concentrations. More structurally focused hydrothermal systems formed large epithermal Au-Ag vein deposits in the Bodie and Aurora mining districts. Economically important hydrothermal systems are temporally related to intermediate to silicic composition domes.Rock types, major and trace element compositions, petrographic characteristics, and volcanic features of the Bodie Hills volcanic field are similar to those of other large Miocene volcanic fields in the southern segment of the ancestral Cascade arc. Relative to other parts of the ancestral arc, especially north of Lake Tahoe in northeastern California, the scarcity of mafic rocks, relatively K-rich calc-alkaline compositions, and abundance of composite dome fields in the Bodie Hills may reflect thicker crust beneath the southern ancestral arc segment. Thicker crust may have inhibited direct ascent and eruption of mafic, mantle-derived magma, instead stalling its ascent in the lower or middle crust, thereby promoting differentiation to silicic compositions and development of porphyritic textures characteristic of the southern ancestral arc segment.

Materials science research in microgravity

NASA Technical Reports Server (NTRS)

Perepezko, John H.

1992-01-01

There are several important attributes of an extended duration microgravity environment that offer a new dimension in the control of the microstructure, processing, and properties of materials. First, when gravitational effects are minimized, buoyancy driven convection flows are also minimized. The flows due to density differences, brought about either by composition or temperature gradients will then be reduced or eliminated to permit a more precise control of the temperature and the composition of a melt which is critical in achieving high quality crystal growth of electronic materials or alloy structures. Secondly, body force effects such as sedimentation, hydrostatic pressure, and deformation are similarly reduced. These effects may interfere with attempts to produce uniformly dispersed or aligned second phases during melt solidification. Thirdly, operating in a microgravity environment will facilitate the containerless processing of melts to eliminate the limitations of containment for reactive melts. The noncontacting forces such as those developed from electromagnet, electrostatic, or acoustic fields can be used to position samples. With this mode of operation, contamination can be minimized to enable the study of reactive melts and to eliminate extraneous crystal nucleation so that novel crystalline structures and new glass compositions may be produced. In order to take advantage of the microgravity environment for materials research, it has become clear that reliable processing models based on a sound ground based experimental experience and an established thermophysical property data base are essential.

Depth of cure of bulk-fill flowable composite resins.

PubMed

Pedalino, Inaam; Hartup, Grant R; Vandewalle, Kraig S

2015-01-01

In recent years, manufacturers have introduced flowable composite resins that reportedly can be placed in increments of 4 mm or greater. The purpose of this study was to evaluate the depth of cure of bulk-fill flowable composite resins (SureFil SDR Flow, Grandio Flow, and Venus Bulk Fill) and a conventional flowable composite resin (Revolution Formula 2). Depth of cure was measured in terms of bottom-maximum Knoop hardness number (KHN) ratios and the International Organization for Standardization (ISO) 4049 scrape technique. Shades A2 and A3 of SureFil SDR Flow, Grandio Flow, and Revolution Formula 2 were tested. Venus Bulk Fill was tested in its only available shade (universal). Specimens in thicknesses of 2, 3, 4, 5, and 6 mm were polymerized for 20 or 40 seconds, and a hardness tester was used to determine the hardness ratios for each shade at each thickness. For the scraping technique, after specimens were exposed to the curing light, unpolymerized composite resin was removed with a plastic instrument, the polymerized composite was measured, and the length was divided by 2 per ISO guidelines. According to the KHN ratios and the scrape test, Venus Bulk Fill predictably exceeded the manufacturer's claim of a 4-mm depth of cure at both 20 and 40 seconds of curing time. The overall results for depth of cure showed that Venus Bulk Fill ≥ SureFil SDR Flow ≥ Grandio Flow ≥ Revolution Formula 2.

Magnetic roller gas gate employing transonic sweep gas flow to isolate regions of differing gaseous composition or pressure

DOEpatents

Doehler, Joachim

1994-12-20

Disclosed herein is an improved gas gate for interconnecting regions of differing gaseous composition and/or pressure. The gas gate includes a narrow, elongated passageway through which substrate material is adapted to move between said regions and inlet means for introducing a flow of non-contaminating sweep gas into a central portion of said passageway. The gas gate is characterized in that the height of the passageway and the flow rate of the sweep gas therethrough provides for transonic flow of the sweep gas between the inlet means and at least one of the two interconnected regions, thereby effectively isolating one region, characterized by one composition and pressure, from another region, having a differing composition and/or pressure, by decreasing the mean-free-path length between collisions of diffusing species within the transonic flow region. The gas gate preferably includes a manifold at the juncture point where the gas inlet means and the passageway interconnect.

Physical criteria for distinguishing sandy tsunami and storm deposits using modern examples

USGS Publications Warehouse

Morton, Robert A.; Gelfenbaum, Guy; Jaffe, Bruce E.

2007-01-01

Modern subaerial sand beds deposited by major tsunamis and hurricanes were compared at trench, transect, and sub-regional spatial scales to evaluate which attributes are most useful for distinguishing the two types of deposits. Physical criteria that may be diagnostic include: sediment composition, textures and grading, types and organization of stratification, thickness, geometry, and landscape conformity. Published reports of Pacific Ocean tsunami impacts and our field observations suggest that sandy tsunami deposits are generally 30 cm thick, generally extend The distinctions between tsunami and storm deposits are related to differences in the hydrodynamics and sediment-sorting processes during transport. Tsunami deposition results from a few high-velocity, long-period waves that entrain sediment from the shoreface, beach, and landward erosion zone. Tsunamis can have flow depths greater than 10 m, transport sediment primarily in suspension, and distribute the load over a broad region where sediment falls out of suspension when flow decelerates. In contrast, storm inundation generally is gradual and prolonged, consisting of many waves that erode beaches and dunes with no significant overland return flow until after the main flooding. Storm flow depths are commonly

Drilling confirms hot-spot origins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1978-02-01

Eleven holes were drilled at 4 sites in the Emperor Seamount chain in order to test the hot-spot hypothesis of the origin of the Hawaiian and Emperor chains and several important corollaries. Basalt was penetrated at 3 sites, and the paleontological ages of the lowest sediments above basalt are consistent with a linear geochron connecting the ages of Meiji Seamount to the north, and Koko and Yuryaku seamounts to the south. The chemical composition of the upper 4 basalt flow units cored at Ojin Seamount indicates that they are typical Hawaiites. A sample of tholeiite was recovered from the bottommore » of the hole. The lava flows from Ojin, Nintoku, and Suiko have natural remanent magnetization that is relatively stable to alternating field demagnetization, as expected of oceanic-island basalts. Many of the basalts at all 3 sites have highly vesicular and oxidized flow tops and bottoms. Observations indicate that the flows were erupted subaerially, and that Ojin, Nintoku, and Suiko volcanoes once stood well above sea level. In a general way, the hot-spot origin of the Emperor Seamount chain was confirmed. (JGB)« less

New Insights on Subsurface Imaging of Carbon Nanotubes in Polymer Composites via Scanning Electron Microscopy

NASA Technical Reports Server (NTRS)

Zhao, Minhua; Ming, Bin; Kim, Jae-Woo; Gibbons, Luke J.; Gu, Xiaohong; Nguyen, Tinh; Park, Cheol; Lillehei, Peter T.; Villarrubia, J. S.; Vladar, Andras E.;

The effect of hydrodynamic conditions on the phenotype of Pseudomonas fluorescens biofilms.

PubMed

Simões, Manuel; Pereira, Maria O; Sillankorva, Sanna; Azeredo, Joana; Vieira, Maria J

2007-01-01

This study investigated the phenotypic characteristics of monoculture P. fluorescens biofilms grown under turbulent and laminar flow, using flow cells reactors with stainless steel substrata. The cellular physiology and the overall biofilm activity, structure and composition were characterized, and compared, within hydrodynamically distinct conditions. The results indicate that turbulent flow-generated biofilm cells were significantly less extensive, with decreased metabolic activity and a lower protein and polysaccharides composition per cell than those from laminar flow-generated biofilms. The effect of flow regime did not cause significantly different outer membrane protein expression. From the analysis of biofilm activity, structure and composition, turbulent flow-generated biofilms were metabolically more active, had twice more mass per cm(2), and higher cellular density and protein content (mainly cellular) than laminar flow-generated biofilms. Conversely, laminar flow-generated biofilms presented higher total and matrix polysaccharide contents. Direct visualisation and scanning electron microscopy analysis showed that these different flows generate structurally different biofilms, corroborating the quantitative results. The combination of applied methods provided useful information regarding a broad spectrum of biofilm parameters, which can contribute to control and model biofilm processes.

The Effect of Particle Composition on Hygroscopicity and Droplet Formation at CARES

NASA Astrophysics Data System (ADS)

Cziczo, D. J.; Pekour, M. S.; Hiranuma, N.; Nelson, D.

2010-12-01

During the June, 2010 Carbonaceous Aerosol and Radiative Effects Study (CARES) a custom made humidity controlled nephelometer, hereafter termed a ‘humidograph’, was deployed with a commercial cloud condensation nucleus counter (CCNC) and the particle analysis by laser mass spectrometry (PALMS) instrument. Other ancillary measurements, such as particle size distributions, were made continuously during the month. The CARES field study took place in the Sacramento, CA area. Early June was characterized by cool, wet weather with predominantly northerly flow and very low particle loading. Very little biomass burning took place and the aerosol was largely sulfate neutralized by ammonia. Later in the month a more typical flow pattern from the Sacramento urban area toward the foothills developed. During this period more biomass burning occurred and organics from anthropogenic and urban sources were present on particles. The aforementioned instruments were located in the town of Cool, CA in the Sierra foothills, approximately 50 kilometers north east of cool. This site was chosen as being on the typical summertime daily flow some hours downstream of the Sacramento urban plume. Using these instruments we were able to correlate water uptake and droplet formation with particle composition. The early period of CARES was characterized by a clear deliquescence of the aerosol at ~80% relative humidity which correlated with an ammonium neutralized sulfate aerosol composition. Few CCN were present although these activated at low supersaturations and represented a large fraction of the total aerosol over ~70 nanometers in diameter. Later in the month deliquescence was not clearly indicated for a more organic-rich and biomass burning influenced aerosol. More CCN were present although activation generally required much higher saturations.

Numerical modeling of the transitional boundary layer over a flat plate

NASA Astrophysics Data System (ADS)

Ivanov, Dimitry; Chorny, Andrei

2015-11-01

Our example is connected with fundamental research on understanding how an initially laminar boundary layer becomes turbulent. We have chosen the flow over a flat plate as a prototype for boundary-layer flows around bodies. Special attention was paid to the near-wall region in order to capture all levels of the boundary layer. In this study, the numerical software package OpenFOAM has been used in order to solve the flow field. The results were used in a comparative study with data obtained from Large Eddy Simulation (LES). The composite SGS-wall model is presently incorporated into a computer code suitable for the LES of developing flat-plate boundary layers. Presently this model is extended to the LES of the zero-pressure gradient, flat-plate turbulent boundary layer. In current study the time discretization is based on a second order Crank-Nicolson/Adams-Bashforth method. LES solver using Smagorinsky and the one-equation LES turbulence models. The transition models significantly improve the prediction of the onset location compared to the fully turbulent models.LES methods appear to be the most promising new tool for the design and analysis of flow devices including transition regions of the turbulent flow.

Three-dimensional flow visualization and vorticity dynamics in revolving wings

NASA Astrophysics Data System (ADS)

Cheng, Bo; Sane, Sanjay P.; Barbera, Giovanni; Troolin, Daniel R.; Strand, Tyson; Deng, Xinyan

2013-01-01

We investigated the three-dimensional vorticity dynamics of the flows generated by revolving wings using a volumetric 3-component velocimetry system. The three-dimensional velocity and vorticity fields were represented with respect to the base axes of rotating Cartesian reference frames, and the second invariant of the velocity gradient was evaluated and used as a criterion to identify two core vortex structures. The first structure was a composite of leading, trailing, and tip-edge vortices attached to the wing edges, whereas the second structure was a strong tip vortex tilted from leading-edge vortices and shed into the wake together with the vorticity generated at the tip edge. Using the fundamental vorticity equation, we evaluated the convection, stretching, and tilting of vorticity in the rotating wing frame to understand the generation and evolution of vorticity. Based on these data, we propose that the vorticity generated at the leading edge is carried away by strong tangential flow into the wake and travels downwards with the induced downwash. The convection by spanwise flow is comparatively negligible. The three-dimensional flow in the wake also exhibits considerable vortex tilting and stretching. Together these data underscore the complex and interconnected vortical structures and dynamics generated by revolving wings.

Effects of antibacterial nanostructured composite films on vascular stents: hemodynamic behaviors, microstructural characteristics, and biomechanical properties.

PubMed

Cheng, Han-Yi; Hsiao, Wen-Tien; Lin, Li-Hsiang; Hsu, Ya-Ju; Sinrang, Andi Wardihan; Ou, Keng-Liang

2015-01-01

The purpose of this research was to investigate stresses resulting from different thicknesses and compositions of hydrogenated Cu-incorporated diamond-like carbon (a-C:H/Cu) films at the interface between vascular stent and the artery using three-dimensional reversed finite element models (FEMs). Blood flow velocity variation in vessels with plaques was examined by angiography, and the a-C:H/Cu films were characterized by transmission electron microscopy to analyze surface morphology. FEMs were constructed using a computer-aided reverse design system, and the effects of antibacterial nanostructured composite films in the stress field were investigated. The maximum stress in the vascular stent occurred at the intersections of net-like structures. Data analysis indicated that the stress decreased by 15% in vascular stents with antibacterial nanostructured composite films compared to the control group, and the stress decreased with increasing film thickness. The present results confirmed that antibacterial nanostructured composite films improve the biomechanical properties of vascular stents and release abnormal stress to prevent restenosis. The results of the present study offer the clinical benefit of inducing superior biomechanical behavior in vascular stents. © 2014 Wiley Periodicals, Inc.

Capillary Flow of Liquid Metals in Brazing

NASA Astrophysics Data System (ADS)

Dehsara, Mohammad

Capillary flow is driven or controlled by capillary forces, exerted at the triple line where the fluid phases meet the solid boundary. Phase field (PF) models naturally accommodate diffusive triple line motion with variable contact angle, thus allowing for the no-slip boundary condition without the stress singularities. Moreover, they are uniquely suited for modeling of topological discontinuities which often arise during capillary flows. In this study, we consider diffusive triple line motion within two PF models: the compositionally compressible (CC) and the incompressible (IC) models. We derive the IC model as a systematic approximation to the CC model, based on a suitable choice of continuum velocity field. The CC model, applied to the fluids of dissimilar mass densities, exhibits a computational instability at the triple line. The IC model perfectly represents the analytic equilibria. We develop the parameter identification procedure and show that the triple line kinetics can be well represented by the IC model's diffusive boundary condition. The IC model is first tested by benchmarking the phase-field and experimental kinetics of water, and silicone oil spreading over the glass plates in which two systems do not interact with the substrate. Then, two high-temperature physical settings involving spreading of the molten Al-Si alloy: one over a rough wetting substrate, the other over a non-wetting substrate are modeled in a T-joint structure which is a typical geometric configuration for many brazing and soldering applications. Surface roughness directly influences the spreading of the molten metal by causing break-ups of the liquid film and trapping the liquid away from the joint. In the early stages of capillary flow over non-wetting surface, the melting and flow are concurrent, so that the kinetics of wetting is strongly affected by the variations in effective viscosity of the partially molten metal. We define adequate time-dependent functions for the variations of Al-Si alloy viscosity and triple line mobility to describe the wetting kinetics.

Controls on the distribution and isotopic composition of helium in deep ground-water flows

USGS Publications Warehouse

Zhao, X.; Fritzel, T.L.B.; Quinodoz, H.A.M.; Bethke, C.M.; Torgersen, T.

1998-01-01

The distribution and isotopic composition of helium in sedimentary basins can be used to interpret the ages of very old ground waters. The piston-flow model commonly used in such interpretation, how ever, does not account for several important factors and as such works well only in very simple flow regimes. In this study of helium transport in a hypothetical sedimentary basin, we develop a numerical model that accounts for the magnitude and distribution of the basal helium flux, hydrodynamic dispersion, and complexities in flow regimes such as subregional flow cells. The modeling shows that these factors exert strong controls on the helium distribution and isotopic composition. The simulations may provide a basis for more accurate interpretations of observed helium concentrations and isotopic ratios in sedimentary basins.

Documenting Chemical Assimilation in a Basaltic Lava Flow

NASA Technical Reports Server (NTRS)

Young, K. E.; Bleacher, J. E.; Needham, D. H.; Evans, C.; Whelley, P. L.; Scheidt, S.; Williams, D.; Rogers, A. D.; Glotch, T.

2017-01-01

Lava channels are features seen throughout the inner Solar System, including on Earth, the Moon, and Mars. Flow emplacement is therefore a crucial process in the shaping of planetary surfaces. Many studies have investigated the dynamics of lava flow emplacement, both on Earth and on the Moon [1,2,3] but none have focused on how the compositional and structural characteristics of the substrate over which a flow was emplaced influenced its final flow morphology. Within the length of one flow, it is common for flows to change in morphology, a quality linked to lava rheology (a function of multiple factors including viscosity, temperature, composition, etc.). The relationship between rheology and temperature has been well-studied [4,5,6] but less is understood about the relationship between a pre-flow terrain's chemistry and how the interaction between this flow and the new flow might affect lava rheology and therefore emplacement dynamics. Lava erosion. Through visual observations of active terrestrial flows, lava erosion has been well-documented [i.e. 7,8,9,10]. Lava erosion is the process by which flow composition is altered as the active lava melts and assimilates the pre-flow terrain over which it moves. Though this process has been observed, there is only one instance of where it was been geochemically documented.

Spatial Distribution of Cyanobacteria in Modern Stromatolites

NASA Technical Reports Server (NTRS)

Prufert-Bebout, Lee; Dacles-Mariani, Jennifer; Herbert, Alice; DeVincenzi, Donald (Technical Monitor)

2001-01-01

Living stromatolites consist of complex microbial communities with distinct distribution patterns for different microbial groups. The cyanobacterial populations of Highborne Cay Bahamas exemplify this phenomenon. Field observations reveal distinct distribution patterns for several of these cyanobacterial species. To date 10 different cyanobacterial cultures, including both filamentous and endolithic species, have been isolated from these stromatolites. We will present data on the growth and motility characteristics as well as on the nutritional requirements of these isolates. These data will then be correlated with the field observed distributions for these species. Lastly laboratory simulations of stromatolites grown under various conditions of irradiance, flow and cyanobacterial community composition will be presented. These experiments allow us to evaluate our predictions regarding controls on cyanobacterial distribution.

Geology and geologic history of the Moscow-Pullman basin, Idaho and Washington, from late Grande Ronde to late Saddle Mountains time

USGS Publications Warehouse

Bush, John H; Garwood, Dean L; Dunlap, Pamela

2016-01-01

The Moscow-Pullman basin, located on the eastern margin of the Columbia River flood basalt province, consists of a subsurface mosaic of interlayered Miocene sediments and lava flows of the Imnaha, Grande Ronde, Wanapum, and Saddle Mountains Basalts of the Columbia River Basalt Group. This sequence is ~1800 ft (550 m) thick in the east around Moscow, Idaho, and exceeds 2300 ft (700 m) in the west at Pullman, Washington. Most flows entered from the west into a topographic low, partially surrounded by steep mountainous terrain. These flows caused a rapid rise in base level and deposition of immature sediments. This field guide focuses on the upper Grande Ronde Basalt, Wanapum Basalt, and sediments of the Latah Formation.Late Grande Ronde flows terminated midway into the basin to begin the formation of a topographic high that now separates a thick sediment wedge of the Vantage Member to the east of the high from a thin layer to the west. Disrupted by lava flows, streams were pushed from a west-flowing direction to a north-northwest orientation and drained the basin through a gap between steptoes toward Palouse, Washington. Emplacement of the Roza flow of the Wanapum Basalt against the western side of the topographic high was instrumental in this process, plugging west-flowing drainages and increasing deposition of Vantage sediments east of the high. The overlying basalt of Lolo covered both the Roza flow and Vantage sediments, blocking all drainages, and was in turn covered by sediments interlayered with local Saddle Mountains Basalt flows. Reestablishment of west-flowing drainages has been slow.The uppermost Grande Ronde, the Vantage, and the Wanapum contain what is known as the upper aquifer. The water supply is controlled, in part, by thickness, composition, and distribution of the Vantage sediments. A buried channel of the Vantage likely connects the upper aquifer to Palouse, Washington, outside the basin. This field guide locates outcrops; relates them to stratigraphic well data; outlines paleogeographic basin evolution from late Grande Ronde to the present time; and notes structures, basin margin differences, and features that influence upper aquifer water supply.

Accumulation of electric currents driving jetting events in the solar atmosphere

NASA Astrophysics Data System (ADS)

Vargas Domínguez, S.; Guo, Y.; Demoulin, P.; Schmieder, B.; Ding, M.; Liu, Y.

2013-12-01

The solar atmosphere is populated with a wide variety of structures and phenomena at different spatial and temporal scales. Explosive phenomena are of particular interest due to their contribution to the atmosphere's energy budget and their implications, e.g. coronal heating. Recent instrumental developments have provided important observations and therefore new insights for tracking the dynamic evolution of the solar atmosphere. Jets of plasma are frequently observed in the solar corona and are thought to be a consequence of magnetic reconnection, however, the physics involved is not fully understood. Unprecedented observations (EUV and vector magnetic fields) are used to study solar jetting events, from which we derive the magnetic flux evolution, the photospheric velocity field, and the vertical electric current evolution. The evolution of magnetic parasitic polarities displaying diverging flows are detected to trigger recurrent jets in a solar regionon 17 September 2010. The interaction drive the build up of electric currents. Observed diverging flows are proposed to build continuously such currents. Magnetic reconnection is proposed to occur periodically, in the current layer created between the emerging bipole and the large scale active region field. SDO/AIA EUV composite images. Upper: SDO/AIA 171 Å image overlaid by the line-of-sight magnetic field observed at the same time as that of the 171 Å image. Lower: Map of photospheric transverse velocities derived from LCT analysis with the HMI magnetograms.

Nonlinear effective permittivity of field grading composite dielectrics

NASA Astrophysics Data System (ADS)

Yang, Xiao; Zhao, Xiaolei; Li, Qi; Hu, Jun; He, Jinliang

2018-02-01

Field grading composite dielectrics with good nonlinear electrical properties can function as smart materials for electrical field control in a high-voltage apparatus. Besides the well-documented nonlinear conducting behavior, the field-dependent effective permittivity of field grading composites were also reported; however, in-depth research on the mechanism and influencing factors of this nonlinear permittivity are absent. This paper theoretically discusses the origin of the nonlinear effective permittivity, and the mechanism is illustrated through the waveform analysis of the nonlinear response of ZnO microvaristor/silicone rubber composites under a pure AC field. The field-dependent effective permittivity and loss property of the ZnO composites are measured by a dielectric spectrometer in both DC and AC fields under different frequencies. Through comparison of measurement results and theoretical models, the influence of the filler concentration, frequency, and time domain characteristics of the applied field on the nonlinear permittivity of the field grading composites are well explained. This paper provides insight into the nonlinear permittivity of field grading composites, and will be helpful for further tuning the performance of field grading composites.

The rheology and composition of cryovolcanic flows on icy satellites

NASA Technical Reports Server (NTRS)

Kargel, Jeffrey S.

1993-01-01

The rheologic properties of terrestrial lavas have been related to morphologic features of their flows, such as levees, banked surfaces, multilobate structures, and compressible folds. These features also have been used to determine rheologies and constrain the compositions of extraterrestrial flows. However, with rare exceptions, such features are not resolvable in Voyager images of the satellites of outer planets. Often only flow length and edge thickness of cryovolcanic flows can be measured reasonably accurately from Voyager images. The semiempirical lava-flow model presented here is a renewed effort to extract useful information from such measurements.

On the relation between photospheric flow fields and the magnetic field distribution on the solar surface

NASA Technical Reports Server (NTRS)

Simon, George W.; Title, A. M.; Topka, K. P.; Tarbell, T. D.; Shine, R. A.

1988-01-01

Using the technique of local correlation tracking on a 28 minute time sequence of white-light images of solar granulation, the horizontal flow field on the solar surface is measured. The time series was obtained by the Solar Optical Universal Polarimeter (SOUP) on Spacelab 2 (Space Shuttle flight 51-F) and is free from atmospheric blurring and distortion. The SOUP flow fields have been compared with carefully aligned magnetograms taken over a nine hour period at the Big Bear Solar Observatory before, during, and after the SOUP images. The flow field and the magnetic field agree in considerable detail: vectors which define the flow of the white-light intensity pattern (granulation) point toward magnetic field regions, magnetic fields surround flow cells, and magnetic features move along the flow arrows. The projected locations of free particles ('corks') in the measured flow field congregate at the same locations where the magnetic field is observed.

External intermittency prediction using AMR solutions of RANS turbulence and transported PDF models

NASA Astrophysics Data System (ADS)

Olivieri, D. A.; Fairweather, M.; Falle, S. A. E. G.

2011-12-01

External intermittency in turbulent round jets is predicted using a Reynolds-averaged Navier-Stokes modelling approach coupled to solutions of the transported probability density function (pdf) equation for scalar variables. Solutions to the descriptive equations are obtained using a finite-volume method, combined with an adaptive mesh refinement algorithm, applied in both physical and compositional space. This method contrasts with conventional approaches to solving the transported pdf equation which generally employ Monte Carlo techniques. Intermittency-modified eddy viscosity and second-moment turbulence closures are used to accommodate the effects of intermittency on the flow field, with the influence of intermittency also included, through modifications to the mixing model, in the transported pdf equation. Predictions of the overall model are compared with experimental data on the velocity and scalar fields in a round jet, as well as against measurements of intermittency profiles and scalar pdfs in a number of flows, with good agreement obtained. For the cases considered, predictions based on the second-moment turbulence closure are clearly superior, although both turbulence models give realistic predictions of the bimodal scalar pdfs observed experimentally.

Movements of water, solutes, and stable isotopes in the unsaturated zones of two sand plains in the upper Midwest

USGS Publications Warehouse

Komor, Stephen C.; Emerson, Douglas G.

1994-01-01

Four month-long field experiments investigated movements of water and solutes through unsaturated sand plains near Princeton, Minnesota, and Oakes, North Dakota. Atrazine and bromide were applied to bare soils and soils planted with corn. The field plots were irrigated according to local farming practices. At the end of each experiment, unsaturated soils were analyzed for atrazine and bromide concentrations and oxygen and hydrogen isotope compositions of soil water. Most soil water was affected by evaporation but groundwater beneath the plots had no evaporative isotopic signature. Therefore most recharge consisted of water that was unaffected by evaporation. Sources of such water may have included snowmelt, prolonged or high-intensity rainfalls that were not interrupted by periods of drying, and water that moved through preferential flow paths. Preferential flow also was suggested by the detection of atrazine, deethylatrazine, and bromide in groundwater shortly after each application of irrigation water at Princeton and by isolated concentrations of atrazine and bromide in soil well below the main masses of chemicals at Oakes.

Effects of plume afterburning on infrared spectroscopy

NASA Astrophysics Data System (ADS)

Zhu, Xijuan; Xu, Ying; Ma, Jing; Duan, Ran; Wu, Jie

2017-10-01

Contains H2, CO and unburned components of high-temperature plume of rocket engine, then injected into the atmosphere, continue to carry out the oxidation reaction in the plume near field region with the volume in the plume of oxygen in the air, two times burning. The afterburning is an important cause of infrared radiation intensification of propellant plume, which increases the temperature of the flame and changes the components of the gas, thus enhancing the infrared radiation intensity of the flame. [1]. Two the combustion numerical using chemical reaction mechanism involving HO2 intermediate reaction, the study confirmed that HO2 is a key intermediate, plays a decisive role to trigger early response, on afterburning temperature and flow concentration distribution effect. A finite rate chemical reaction model is used to describe the two burning phenomenon in high temperature plume[2]. In this paper, a numerical simulation of the flame flow field and radiative transfer is carried out for the afterburning phenomenon. The effects of afterburning on the composition, temperature and infrared radiation of the plume are obtained by comparison.

Several examples where turbulence models fail in inlet flow field analysis

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.

1993-01-01

Computational uncertainties in turbulence modeling for three dimensional inlet flow fields include flows approaching separation, strength of secondary flow field, three dimensional flow predictions of vortex liftoff, and influence of vortex-boundary layer interactions; computational uncertainties in vortex generator modeling include representation of generator vorticity field and the relationship between generator and vorticity field. The objectives of the inlet flow field studies presented in this document are to advance the understanding, prediction, and control of intake distortion and to study the basic interactions that influence this design problem.

Modeled hydrologic metrics show links between hydrology and the functional composition of stream assemblages.

PubMed

Patrick, Christopher J; Yuan, Lester L

2017-07-01

Flow alteration is widespread in streams, but current understanding of the effects of differences in flow characteristics on stream biological communities is incomplete. We tested hypotheses about the effect of variation in hydrology on stream communities by using generalized additive models to relate watershed information to the values of different flow metrics at gauged sites. Flow models accounted for 54-80% of the spatial variation in flow metric values among gauged sites. We then used these models to predict flow metrics in 842 ungauged stream sites in the mid-Atlantic United States that were sampled for fish, macroinvertebrates, and environmental covariates. Fish and macroinvertebrate assemblages were characterized in terms of a suite of metrics that quantified aspects of community composition, diversity, and functional traits that were expected to be associated with differences in flow characteristics. We related modeled flow metrics to biological metrics in a series of stressor-response models. Our analyses identified both drying and base flow instability as explaining 30-50% of the observed variability in fish and invertebrate community composition. Variations in community composition were related to variations in the prevalence of dispersal traits in invertebrates and trophic guilds in fish. The results demonstrate that we can use statistical models to predict hydrologic conditions at bioassessment sites, which, in turn, we can use to estimate relationships between flow conditions and biological characteristics. This analysis provides an approach to quantify the effects of spatial variation in flow metrics using readily available biomonitoring data. © 2017 by the Ecological Society of America.

Numerical and experimental studies on pulsatile flow in aneurysms arising laterally from a curved parent vessel at various angles.

PubMed

Liou, Tong-Miin; Li, Yi-Chen; Juan, Wei-Cheng

2007-01-01

Both numerical and experimental studies have been performed to characterize the fluid flow inside the lateral aneurysms arising from the curved parent vessels at various angles gamma. The implicit solver was based on the time-dependent Navier-Stokes equations of incompressible laminar flow. Solutions were generated by a cell-center finite-volume method that used second order upwind and second order center flux difference splitting for the convection and diffusion term, respectively. The second order Crank-Nicolson method was used in the time integration term while the SIMPLEC algorithm was adopted to handle the pressure-velocity coupling. Complementarily, the particle tracking velocimetry (PTV) was used to measure the velocity fields. The conditions selected were to simulate an internal carotid artery with a diameter of 5 mm by similarity rules. The values of gamma explored were 0 degrees, 45 degrees, 90 degrees, and 135 degrees. Pulsatile flow with Wormersley number 3.9 and Reynolds numbers varying from 350 to 850 was considered. The computed results are firstly verified by the PTV measured ones. Discussion of the results is in terms of pulsatile main and secondary velocity vector fields, inflow rates into the aneurysm, and the distributions of wall shear stress and static pressure. It is found that among the angles examined gamma=45( composite function) is the riskiest angle from a fluid dynamics point of view and the aneurysmal dome is at risk.

Modeling two-phase flow in three-dimensional complex flow-fields of proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Kim, Jinyong; Luo, Gang; Wang, Chao-Yang

2017-10-01

3D fine-mesh flow-fields recently developed by Toyota Mirai improved water management and mass transport in proton exchange membrane (PEM) fuel cell stacks, suggesting their potential value for robust and high-power PEM fuel cell stack performance. In such complex flow-fields, Forchheimer's inertial effect is dominant at high current density. In this work, a two-phase flow model of 3D complex flow-fields of PEMFCs is developed by accounting for Forchheimer's inertial effect, for the first time, to elucidate the underlying mechanism of liquid water behavior and mass transport inside 3D complex flow-fields and their adjacent gas diffusion layers (GDL). It is found that Forchheimer's inertial effect enhances liquid water removal from flow-fields and adds additional flow resistance around baffles, which improves interfacial liquid water and mass transport. As a result, substantial improvements in high current density cell performance and operational stability are expected in PEMFCs with 3D complex flow-fields, compared to PEMFCs with conventional flow-fields. Higher current density operation required to further reduce PEMFC stack cost per kW in the future will necessitate optimizing complex flow-field designs using the present model, in order to efficiently remove a large amount of product water and hence minimize the mass transport voltage loss.

Review of progress in understanding the fluid geochemistry of the Cerro Prieto Geothermal System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Truesdell, A.H.; Nehring, N.L.; Thompson, J.M.

1982-08-10

Fluid geochemistry has played a major role in the authors present understanding of the Cerro Prieto geothermal system. Fluid chemical and isotopic compositions have been used to indicate the origin of water, salts, and gases, original subsurface temperature and fluid flow, fluid-production mechanims, and production-induced aquifer boiling and cold-water entry. The extensive geochemical data and interpretation for Cerro Prieto published from 1964 to 1981 are reviewed and discussed. Fluid geochemistry must continue to play an important role in the further development of the Cerro Prieto field.

Multi-Scale Behavioral Modeling and Analysis Promoting a Fundamental Understanding of Agent-Based System Design and Operation

DTIC Science & Technology

2007-03-01

Chains," Mathematics of Control, Signals, and Systems, vol. 3(1), pp. 1-29, 1990. [4] A . Arnold, J . A . Carrillo, and I. Gamba, "Low and High Field...Aronson, C. L. A ., and J . L. Vázquez, "Interfaces with a corner point in one- dimensional porous medium flow," Comm. Pure Appl. Math, vol. 38(4), pp. 375...K. Levin, "Damage analysis of fiber composites," Computer Methods in Applied Mechanics and Engineering. [10] K. S. Barber, A . Goel, T. J . Graser, T

The effect of flow reduction on microphytobenthos development in an alpine river stretch using novel fluorescence techniques

NASA Astrophysics Data System (ADS)

Ganglbauer, A.; Bondar-Kunze, E.; Hein, T.; Zeiringer, B.

2009-04-01

Many European river systems are affected by flow alterations leading to significant differences of the pristine discharge regime at different temporal scales. Flow regulation measures and water abstraction are changing the extent and frequency of water level changes. In concert with river bed regulation this could affect the hydromorphological situation of river systems and key ecosystem functions. Microphytobenthos is a major component in the physical, chemical and biochemical processes, which occur in river systems and the associated riparian zones. They are significant primary producers in rivers, because of their high turnover rate, rapid colonization along the aquatic-terrestrial boundary, transform nutrients and support via their biomass the food webs in the river and adjacent ecosystems. The developed structure and composition of microphytobenthos is controlled by the hydromorphological conditions and thus, indicates environmental changes. The guiding question for the presented research was to what extent changes in the variability of flow affect microphytobenthos development in a river stretch and to what extent the structure and composition of microphytobenthos changed at the micro scale. To investigate these effects under natural conditions we compared a residual flow section impacted by a hydropower plant with one unaffected section of the River Ybbs, a tributary to the Danube River. The river stretch investigated was a 33 km long stretch between the villages Göstling and Opponitz in Lower Austria. The River Ybbs is draining a catchment of 1,300 km2 and has a mean discharge of 20 m3 s-1.The main benthic algal group are diatoms, which are typical for low order rivers in the Alpine area, characterized by low temperatures throughout the year. We expected that flow velocity explain the extent of microphytobenthos development at the river stretch scale and especially low flow conditions affect the structure and composition of algal biomass at the micro scale. The measurements included field surveys and two experimental settings. During May 2008 we conducted an in-situ experiment with artificial substrata to investigate the effect of flow velocity changes. We exposed glass slides in baskets along two transects in the River Ybbs at two sampling sites and eight different positions. After a period of about four weeks with weekly recurrent measurements including flow velocity, water depth, chlorophyll a content and electron transport rate (ETR) we started our experiment. Glass slides were taken from each position and were exposed in a flow reduced impounded area in the river Ybbs near Göstling. There low flow velocity was used to test the effect on microphytobenthos development. The next ten days daily measurements of flow velocity, water depth, chlorophyll-a content and electron transport rate (ETR) with the pulse amplitude modulated fluorescence method and microscopic analysis were undertaken. Based on these daily measurements under almost stable environmental conditions we could ascertain a shift in the benthic algae community. To assess the distribution along a river stretch we measured 70 sampling points at each sampling side. To characterize the biomass and activity of the microphytobenthos we used Pulse Amplitude Modulated Fluorescence (PAM-Fluorescence). Using this technique allow to measure the biomass (Chlorophyll a) and the ETR (electron transport rate) simultaneously without destroying the structure. With this technique it is possible to The PAM technique measure directly the fluorescence of chlorophyll a in the photosystem two. The quantum yield you get is the probability that a photon can be used photochemically. The quantum yield offers the possibility to illustrate the fitness of algae. Based on these measurements short term responses can be measured and combined with the results of field surveys. These analytical results were used for a habitat modelling approach to describe the microphytobenthos development at 2 scales. First results of the research will be presented.

A random distribution reacting mixing layer model

NASA Technical Reports Server (NTRS)

Jones, Richard A.; Marek, C. John; Myrabo, Leik N.; Nagamatsu, Henry T.

1994-01-01

A methodology for simulation of molecular mixing, and the resulting velocity and temperature fields has been developed. The ideas are applied to the flow conditions present in the NASA Lewis Research Center Planar Reacting Shear Layer (PRSL) facility, and results compared to experimental data. A gaussian transverse turbulent velocity distribution is used in conjunction with a linearly increasing time scale to describe the mixing of different regions of the flow. Equilibrium reaction calculations are then performed on the mix to arrive at a new species composition and temperature. Velocities are determined through summation of momentum contributions. The analysis indicates a combustion efficiency of the order of 80 percent for the reacting mixing layer, and a turbulent Schmidt number of 2/3. The success of the model is attributed to the simulation of large-scale transport of fluid. The favorable comparison shows that a relatively quick and simple PC calculation is capable of simulating the basic flow structure in the reacting and nonreacting shear layer present in the facility given basic assumptions about turbulence properties.

Cellular Binding of Anionic Nanoparticles is Inhibited by Serum Proteins Independent of Nanoparticle Composition.

PubMed

Fleischer, Candace C; Kumar, Umesh; Payne, Christine K

2013-09-01

Nanoparticles used in biological applications encounter a complex mixture of extracellular proteins. Adsorption of these proteins on the nanoparticle surface results in the formation of a "protein corona," which can dominate the interaction of the nanoparticle with the cellular environment. The goal of this research was to determine how nanoparticle composition and surface modification affect the cellular binding of protein-nanoparticle complexes. We examined the cellular binding of a collection of commonly used anionic nanoparticles: quantum dots, colloidal gold nanoparticles, and low-density lipoprotein particles, in the presence and absence of extracellular proteins. These experiments have the advantage of comparing different nanoparticles under identical conditions. Using a combination of fluorescence and dark field microscopy, flow cytometry, and spectroscopy, we find that cellular binding of these anionic nanoparticles is inhibited by serum proteins independent of nanoparticle composition or surface modification. We expect these results will aid in the design of nanoparticles for in vivo applications.

Architecture and emplacement of flood basalt flow fields: case studies from the Columbia River Basalt Group, NW USA

NASA Astrophysics Data System (ADS)

Vye-Brown, C.; Self, S.; Barry, T. L.

2013-03-01

The physical features and morphologies of collections of lava bodies emplaced during single eruptions (known as flow fields) can be used to understand flood basalt emplacement mechanisms. Characteristics and internal features of lava lobes and whole flow field morphologies result from the forward propagation, radial spread, and cooling of individual lobes and are used as a tool to understand the architecture of extensive flood basalt lavas. The features of three flood basalt flow fields from the Columbia River Basalt Group are presented, including the Palouse Falls flow field, a small (8,890 km2, ˜190 km3) unit by common flood basalt proportions, and visualized in three dimensions. The architecture of the Palouse Falls flow field is compared to the complex Ginkgo and more extensive Sand Hollow flow fields to investigate the degree to which simple emplacement models represent the style, as well as the spatial and temporal developments, of flow fields. Evidence from each flow field supports emplacement by inflation as the predominant mechanism producing thick lobes. Inflation enables existing lobes to transmit lava to form new lobes, thus extending the advance and spread of lava flow fields. Minimum emplacement timescales calculated for each flow field are 19.3 years for Palouse Falls, 8.3 years for Ginkgo, and 16.9 years for Sand Hollow. Simple flow fields can be traced from vent to distal areas and an emplacement sequence visualized, but those with multiple-layered lobes present a degree of complexity that make lava pathways and emplacement sequences more difficult to identify.

The morphology and evolution of the Stromboli 2002-2003 lava flow field--An example of a basaltic flow field emplaced on a steep slope

USGS Publications Warehouse

Lodato, Luigi; Harris, A.; Spampinato, L.; Calvari, Sonia; Dehn, J.; Patrick, M.

2007-01-01

The use of a hand-held thermal camera during the 2002–2003 Stromboli effusive eruption proved essential in tracking the development of flow field structures and in measuring related eruption parameters, such as the number of active vents and flow lengths. The steep underlying slope on which the flow field was emplaced resulted in a characteristic flow field morphology. This comprised a proximal shield, where flow stacking and inflation caused piling up of lava on the relatively flat ground of the vent zone, that fed a medial–distal lava flow field. This zone was characterized by the formation of lava tubes and tumuli forming a complex network of tumuli and flows linked by tubes. Most of the flow field was emplaced on extremely steep slopes and this had two effects. It caused flows to slide, as well as flow, and flow fronts to fail frequently, persistent flow front crumbling resulted in the production of an extensive debris field. Channel-fed flows were also characterized by development of excavated debris levees in this zone (Calvari et al. 2005). Collapse of lava flow fronts and inflation of the upper proximal lava shield made volume calculation very difficult. Comparison of the final field volume with that expecta by integrating the lava effusion rates through time suggests a loss of ~70% erupted lava by flow front crumbling and accumulation as debris flows below sea level. Derived relationships between effusion rate, flow length, and number of active vents showed systematic and correlated variations with time where spreading of volume between numerous flows caused an otherwise good correlation between effusion rate, flow length to break down. Observations collected during this eruption are useful in helping to understand lava flow processes on steep slopes, as well as in interpreting old lava–debris sequences found in other steep-sided volcanoes subject to effusive activity.

Dislocation dynamics and crystal plasticity in the phase-field crystal model

NASA Astrophysics Data System (ADS)

Skaugen, Audun; Angheluta, Luiza; Viñals, Jorge

2018-02-01

A phase-field model of a crystalline material is introduced to develop the necessary theoretical framework to study plastic flow due to dislocation motion. We first obtain the elastic stress from the phase-field crystal free energy under weak distortion and show that it obeys the stress-strain relation of linear elasticity. We focus next on dislocations in a two-dimensional hexagonal lattice. They are composite topological defects in the weakly nonlinear amplitude equation expansion of the phase field, with topological charges given by the standard Burgers vector. This allows us to introduce a formal relation between the dislocation velocity and the evolution of the slowly varying amplitudes of the phase field. Standard dissipative dynamics of the phase-field crystal model is shown to determine the velocity of the dislocations. When the amplitude expansion is valid and under additional simplifications, we find that the dislocation velocity is determined by the Peach-Koehler force. As an application, we compute the defect velocity for a dislocation dipole in two setups, pure glide and pure climb, and compare it with the analytical predictions.

Length-scales of Slab-induced Asthenospheric Deformation from Geodynamic Modeling, Mantle Deformation Fabric, and Synthetic Shear Wave Splitting

NASA Astrophysics Data System (ADS)

Jadamec, M. A.; MacDougall, J.; Fischer, K. M.

2017-12-01

The viscosity structure of the Earth's interior is critically important, because it places a first order constraint on plate motion and mantle flow rates. Geodynamic models using a composite viscosity based on experimentally derived flow laws for olivine aggregates show that lateral viscosity variations emerge in the upper mantle due to the subduction dynamics. However, the length-scale of this transition is still not well understood. Two-dimensional numerical models of subduction are presented that investigate the effect of initial slab dip, maximum yield stress (slab strength), and viscosity formulation (Newtonian versus composite) on the emergent lateral viscosity variations in the upper-mantle and magnitude of slab-driven mantle flow velocity. Significant viscosity reductions occur in regions of large flow velocity gradients due to the weakening effect of the dislocation creep deformation mechanism. The dynamic reductions in asthenospheric viscosity (less than 1018 Pa s) occur within approximately 500 km from driving force of the slab, with peak flow velocities occurring in models with a lower yield stress (weaker slab) and higher stress exponent. This leads to a sharper definition of the rheological base of the lithosphere and implies lateral variability in tractions along the base of the lithosphere. As the dislocation creep mechanism also leads to mantle deformation fabric, we then examine the spatial variation in the LPO development in the asthenosphere and calculate synthetic shear wave splitting. The models show that olivine LPO fabric in the asthenosphere generally increases in alignment strength with increased proximity to the slab, but can be transient and spatially variable on small length scales. The vertical flow fields surrounding the slab tip can produce shear-wave splitting variations with back-azimuth that deviate from the predictions of uniform trench-normal anisotropy, a result that bears on the interpretation of complexity in shear-wave splitting observed in real subduction zones.

Groundwater Recharge and Flow Processes in Taihang Mountains, a Semi-humid Region, North China

NASA Astrophysics Data System (ADS)

Sakakibara, Koichi; Tsujimura, Maki; Song, Xianfang; Zhang, Jie

2015-04-01

Groundwater flow/recharge variations in time and space are crucial for effective water management especially in semi-arid and semi-humid regions. In order to reveal comprehensive groundwater flow/recharge processes in a catchment with a large topographical relief and seasonal hydrological variations, intensive field surveys were undertaken at 4 times in different seasons (June 2011, August 2012, November 2012, February 2014) in the Wangkuai watershed, Taihang mountains, which is a main groundwater recharge area of the North China Plain. The groundwater, spring, stream water and reservoir water were taken, and inorganic solute constituents and stable isotopes of oxygen-18 and deuterium were determined on all water samples. Also, the stream flow rate and the depth of groundwater table were observed. The stable isotopic compositions and inorganic solute constituents in the groundwater are depleted and shown similar values as those of the surface water at the mountain-plain transitional area. Additionally, the groundwater in the vicinity of the Wangkuai Reservoir presents clearly higher stable isotopic compositions and lower d-excess than those of the stream water, indicating the groundwater around the reservoir is affected by evaporation same as the Wangkuai Reservoir itself. Hence, the surface water in the mountain-plain transitional area and Wangkuai Reservoir are principal groundwater recharge sources. An inversion analysis and simple mixing model were applied in the Wangkuai watershed using stable isotopes of oxygen-18 and deuterium to construct a groundwater flow model. The model shows that multi-originated groundwater flows from upstream to downstream along topography with certain mixing. In addition, the groundwater recharge occurs dominantly at the altitude from 421 m to 953 m, and the groundwater recharge rate by the Wangkuai Reservoir is estimated to be 2.4 % of the total groundwater recharge in the Wangkuai watershed. Therefore, the stream water and reservoir water in the mountain-plain transitional area plays an important role of groundwater recharge in semi-arid and semi-humid regions.

A combined morphometric, sedimentary, GIS and modelling analysis of flooding and debris flow hazard on a composite alluvial fan, Caveside, Tasmania

NASA Astrophysics Data System (ADS)

Kain, Claire L.; Rigby, Edward H.; Mazengarb, Colin

2018-02-01

Two episodes of intense flooding and sediment movement occurred in the Westmorland Stream alluvial system near Caveside, Australia in January 2011 and June 2016. The events were investigated in order to better understand the drivers and functioning of this composite alluvial system on a larger scale, so as to provide awareness of the potential hazard from future flood and debris flow events. A novel combination of methods was employed, including field surveys, catchment morphometry, GIS mapping from LiDAR and aerial imagery, and hydraulic modelling using RiverFlow-2D software. Both events were initiated by extreme rainfall events (< 1% Annual Exceedance Probability for durations exceeding 6 h) and resulted in flooding and sediment deposition across the alluvial fan. The impacts of the 2011 and 2016 events on the farmland appeared similar; however, there were differences in sediment source and transport processes that have implications for understanding recurrence probabilities. A debris flow was a key driver in the 2011 event, by eroding the stream channel in the forested watershed and delivering a large volume of sediment downstream to the alluvial fan. In contrast, modelled flooding velocities suggest the impacts of the 2016 event were the result of an extended period of extreme stream flooding and consequent erosion of alluvium directly above the current fan apex. The morphometry of the catchment is better aligned with values from fluvially dominated fans found elsewhere, which suggests that flooding represents a more frequent future risk than debris flows. These findings have wider implications for the estimation of debris flow and flood hazard on alluvial fans in Tasmania and elsewhere, as well as further demonstrating the capacity of combined hydraulic modelling and geomorphologic investigation as a predictive tool to inform hazard management practices in environments affected by flooding and sediment movement.

Flow Fields of the 3.5 Ga Komati Formation, South Africa: Geochemical, Stratigraphic, and Temporal relationships between Massive, Vesicular, and Spinifex flows

NASA Astrophysics Data System (ADS)

Dann, J. C.

2007-12-01

A challenge of Archean volcanology is to reconstruct submarine flow fields by mapping and analyzing vertically dipping sequences of lavas. Some flow fields are bound by sediments and/or seafloor alteration that mark clear gaps in volcanism. Flow fields in the Lower Komati Fm are defined by alternating layers of komatiite (26% MgO) and komatiitic basalt (15% MgO). Five komatiite flow fields (100-200m thick) repeat the same stratigraphic zoning of spinifex overlying massive komatiite, and each flow field has a distinct Al2O3/CaO, a ratio unaffected by olivine fractionation, consistent with the contention that each komatiite flow field represents a distinct batch of mantle melting. Although massive and spinifex komatiite form distinct stratigraphic units on a map scale, detailed outcrop mapping reveals that the change in flow type represents a transition within a single flow field. In one type of transition, thin massive flows alternate with spinifex flow lobes of a compound flow unit. In another, a vesicular flow along the boundary links the underlying massive komatiite and overlying spinifex flows in time. The vesicular flow has alternating spinifex and vesicular layers that form a distinctive crust above a thick massive interior. Locally, this crust is tilted, intruded by massive komatiite from the interior, and overlain by a thick breccia including a spinifex flow broken into blocks and rotated like dominoes by the tilting. These outcrop relations indicate that spinifex flow lobes were starting to flow over the vesicular flow before it had undergone differential inflation, a temporal link between the lower massive and upper spinifex komatiites consistent with their belonging to the same flow field. The transition in flow type may reflect 1) an overlap of proximal and distal facies of komatiite flows as eruption rates waned and/or 2) thermal maturation prior to eruption. Early, cooler, crystal-rich, massive lava, flowing out as thick sheet flows, was replaced by hotter, crystal-poor, less degassed lava, flowing out as spinifex flows.

Thermo-mechanically coupled subduction with a free surface using ASPECT

NASA Astrophysics Data System (ADS)

Fraters, Menno; Glerum, Anne; Thieulot, Cedric; Spakman, Wim

2014-05-01

ASPECT (Kronbichler et al., 2012), short for Advanced Solver for Problems in Earth's ConvecTion, is a new Finite Element code which was originally designed for thermally driven (mantle) convection and is built on state of the art numerical methods (adaptive mesh refinement, linear and nonlinear solver, stabilization of transport dominated processes and a high scalability on multiple processors). Here we present an application of ASPECT to modeling of fully thermo-mechanically coupled subduction. Our subduction model contains three different compositions: a crustal composition on top of both the subducting slab and the overriding plate, a mantle composition and a sticky air composition, which allows for simulating a free surface for modeling topography build-up. We implemented a visco-plastic rheology using frictional plasticity and a composite viscosity defined by diffusion and dislocation creep. The lithospheric mantle has the same composition as the mantle but has a higher viscosity because of a lower temperature. The temperature field is implemented in ASPECT as follows: a linear temperature gradient for the lithosphere and an adiabatic geotherm for the sublithospheric mantle. Initial slab temperature is defined using the analytical solution of McKenzie (1970). The plates can be pushed from the sides of the model, and it is possible to define an additional independent mantle in/out flow through the boundaries. We will show a preliminary set of models, highlighting the codes capabilities, such as the Adaptive Mesh Refinement, topography development and the influence of mantle flow on the subduction evolution. Kronbichler, M., Heister, T., and Bangerth, W. (2012), High accuracy mantle convection simulation through modern numerical methods, Geophysical Journal International,191, 12-29, doi:10.1111/j.1365-246X.2012.05609. McKenzie, D.P. (1970), Temperature and potential temperature beneath island arcs, Teconophysics, 10, 357-366, doi:10.1016/0040-1951(70)90115-0.

Composite time-lapse computed tomography and micro finite element simulations: A new imaging approach for characterizing cement flows and mechanical benefits of vertebroplasty.

PubMed

Stadelmann, Vincent A; Zderic, Ivan; Baur, Annick; Unholz, Cynthia; Eberli, Ursula; Gueorguiev, Boyko

2016-02-01

Vertebroplasty has been shown to reinforce weak vertebral bodies and reduce fracture risks, yet cement leakage is a major problem that can cause severe complications. Since cement flow is nearly impossible to control during surgery, small volumes of cement are injected, but then mechanical benefits might be limited. A better understanding of cement flows within bone structure is required to further optimize vertebroplasty and bone augmentation in general. We developed a novel imaging method, composite time-lapse CT, to characterize cement flow during injection. In brief, composite-resolution time-lapse CT exploits the qualities of microCT and clinical CT. The method consists in overlaying low-resolution time-lapse CT scans acquired during injection onto pre-operative high-resolution microCT scans, generating composite-resolution time-lapse CT series of cement flow within bone. In this in vitro study, composite-resolution time-lapse CT was applied to eight intact and five artificially fractured cadaveric vertebrae during vertebroplasty. The time-lapse scans were acquired at one-milliliter cement injection steps until a total of 10 ml cement was injected. The composite-resolution series were then converted into micro finite element models to compute strains distribution under virtual axial loading. Relocation of strain energy density within bone structure was observed throughout the progression of the procedure. Interestingly, the normalized effect of cement injection on the overall stiffness of the vertebrae was similar between intact and fractured specimens, although at different orders of magnitude. In conclusion, composite time-lapse CT can picture cement flows during bone augmentation. The composite images can also be easily converted into finite element models to compute virtual strain distributions under loading at every step of an injection, providing deeper understanding on the biomechanics of vertebroplasty. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Fissure sealant materials: Wear resistance of flowable composite resins.

PubMed

Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

2016-01-01

Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm(2) and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm(2)of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics.

Fissure sealant materials: Wear resistance of flowable composite resins

PubMed Central

Asefi, Sohrab; Eskandarion, Solmaz; Hamidiaval, Shadi

2016-01-01

Background. Wear resistance of pit and fissure sealant materials can influence their retention. Wear characteristics of sealant materials may determine scheduling of check-up visits. The aim of this study was to compare wear resistance of two flowable composite resins with that of posterior composite resin materials. Methods. Thirty-five disk-shaped specimens were prepared in 5 groups, including two flowable composite resins (Estelite Flow Quick and Estelite Flow Quick High Flow), Filtek P90 and Filtek P60 and Tetric N-Ceram. The disk-shaped samples were prepared in 25-mm diameter by packing them into a two-piece aluminum mold and then light-cured. All the specimens were polished for 1minute using 600-grit sand paper. The samples were stored in distilled water at room temperature for 1 week and then worn by two-body abrasion test using "pin-on-disk" method (with distilled water under a 15-Nload at 0.05 m/s, for a distance of 100 meter with Steatite ceramic balls antagonists). A Profilometer was used for evaluating the surface wear. Data were analyzed with the one-way ANOVA. Results. Estelite Flow Quick exhibited 2708.9 ± 578.1 μm2 and Estelite Flow Quick High Flow exhibited 3206 ± 2445.1 μm2of wear but there were no significant differences between the groups. They demonstrated similar wear properties. Conclusion. Estelite flowable composite resins have wear resistance similar to nano- and micro-filled and micro-hybrid composite resins. Therefore, they can be recommended as pit and fissure sealant materials in the posterior region with appropriate mechanical characteristics. PMID:27651887

The study of multiphase flow control during odor reproduction

NASA Astrophysics Data System (ADS)

Luo, Dehan; Yu, Hao; Fan, Danjun; He, Meiqiu

2014-04-01

Odor reproduction, is the use of the chemical composition of the basic components of odor recipe, according to a certain proportion, to control the flow of the various components, which make them sufficiently blended to achieve reproduction. In this paper, reproducing method is to find the corresponding liquid flavor, and then based on chemical flavor recipes, using flowmeters to control the chemical composition of the liquid flavor ratio. In the proportional control, the liquid chemical composition is very likely to be volatile, so that the proportional control is multiphase flow control. Measurement of the flow control will directly affect the odor reproducible results. Using electronic nose to obtain reproducible odor data, and then use pattern recognition algorithm to determine reproducible results. The experimental results can be achieved on the process of odor components multiphase flow proportional control parameter adjustment.

Effects of mold geometry on fiber orientation of powder injection molded metal matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Faiz, E-mail: faizahmad@petronas.com.my; Aslam, Muhammad, E-mail: klaira73@gmail.com; Altaf, Khurram, E-mail: khurram.altaf@petronas.com.my

2015-07-22

Fiber orientations in metal matrix composites have significant effect on improving tensile properties. Control of fiber orientations in metal injection molded metal composites is a difficult task. In this study, two mold cavities of dimensions 6x6x90 mm and 10x20x180 mm were used for comparison of fiber orientation in injection molded metal composites test parts. In both mold cavities, convergent and divergent flows were developed by modifying the sprue dimensions. Scanning electron microscope (SEM) was used to examine the fiber orientations within the test samples. The results showed highly aligned fiber in injection molded test bars developed from the convergent melt flow. Randommore » orientation of fibers was noted in the composites test bars produced from divergent melt flow.« less

Dissociation transition of a composite lattice of magnetic vortices in the flux-flow regime of two-band superconductors.

PubMed

Lin, Shi-Zeng; Bulaevskii, Lev N

2013-02-22

In multiband superconductors, each superconducting condensate supports vortices with fractional quantum flux. In the ground state, vortices in different bands are spatially bounded together to form a composite vortex, carrying one quantum flux Φ(0). Here we predict dissociation of the composite vortices lattice in the flux flow state due to the disparity of the vortex viscosity and flux of the vortex in different bands. For a small driving current, composite vortices start to deform, but the constituting vortices in different bands move with the same velocity. For a large current, composite vortices dissociate and vortices in different bands move with different velocities. The dissociation transition shows up as an increase of flux flow resistivity. In the dissociated phase, Shapiro steps are developed when an ac current is superimposed with a dc current.

Particle size reduction in debris flows: Laboratory experiments compared with field data from Inyo Creek, California

NASA Astrophysics Data System (ADS)

Arabnia, O.; Sklar, L. S.; Mclaughlin, M. K.

2014-12-01

Rock particles in debris flows are reduced in size through abrasion and fracture. Wear of coarse sediments results in production of finer particles, which alter the bulk material rheology and influence flow dynamics and runout distance. Particle wear also affects the size distribution of coarse particles, transforming the initial sediment size distribution produced on hillslopes into that delivered to the fluvial channel network. A better understanding of the controls on particle wear in debris flows would aid in the inferring flow conditions from debris flow deposits, in estimating the initial size of sediments entrained in the flow, and in modeling debris flow dynamics and mapping hazards. The rate of particle size reduction with distance traveled should depend on the intensity of particle interactions with other particles and the flow boundary, and on rock resistance to wear. We seek a geomorphic transport law to predict rate of particle wear with debris flow travel distance as a function of particle size distribution, flow depth, channel slope, fluid composition and rock strength. Here we use four rotating drums to create laboratory debris flows across a range of scales. Drum diameters range from 0.2 to 4.0 m, with the largest drum able to accommodate up to 2 Mg of material, including boulders. Each drum has vanes along the boundary to prevent sliding. Initial experiments use angular clasts of durable granodiorite; later experiments will use less resistant rock types. Shear rate is varied by changing drum rotational velocity. We begin experiments with well-sorted coarse particle size distributions, which are allowed to evolve through particle wear. The fluid is initially clear water, which rapidly acquires fine-grained wear products. After each travel increment all coarse particles (mass > 0.4 g) are weighed individually. We quantify particle wear rates using statistics of size and mass distributions, and by fitting various comminution functions to the data. Laboratory data are compared with longitudinal evolution of grain size and angularity of particles deposited by debris flows along Inyo Creek, Sierra Nevada, California. Preliminary results suggest wear rates can be scaled across drum sizes and to field conditions using non-dimensional metrics of flow dynamics including Savage, Bagnold, and Froude numbers.

Origin of leucite-rich and sanidine-rich flow layers in the Leucite Hills Volcanic Field, Wyoming

NASA Astrophysics Data System (ADS)

Gunter, W. D.; Hoinkes, Georg; Ogden, Palmer; Pajari, G. E.

1990-09-01

Two types of orendite (sanidine-phlogopite lamproite) and wyomingite (leucite-phlogopite lamproite) intraflow layering are present in the ultrapotassic Leucite Hills Volcanic Field, Wyoming. In large-scale layering, wyomingites are confined to the base of the flow, while in centimeter-scale layering, orendite and wyomingite alternate throughout the flow. The mineralogy of the orendites and wyomingites are the same; only the relative amount of each mineral vary substantially. The chemical compositions of adjacent layers of wyomingite and orendite are almost identical except for water. The centimeter-scale flow layering probably represents fossil streamlines of the lava and therefore defines the path of circulation of the viscous melt. Toward the front of the flow, the layers are commonly folded. Structures present which are indicative that the flows may have possessed a yield strength are limb shears, boudinage, and slumping. Phlogopite phenocrysts are poorly aligned in the orendite layers, while they are often in subparallel alignment in the wyomingite layers; and they are used as a measure of shearing intensity during emplacement of the flow. Vesicle volumes are concentrated in the orendite layers. In the large-scale layering, a discontinuous base rubble zone of autobreccia is overlain by a thin platy zone followed by a massive zone which composes more than the upper 75% of the flow. Consequently, we feel that the origin of the layering may be related to shearing. Two extremes in the geometry of shearing are proposed: closely spaced, thin, densely sheared layers separated by discrete intervals throughout a lava flow as in the centimeter-scale layering and classical plug flow where all the shearing is confined to the base as in the large-scale layering. A mechanism is proposed which causes thixotropic behavior and localizes shearing: the driving force is the breakdown of molecular water to form T-OH bonds which establishes a chemical potential gradient for water in the melt. The higher activity of water in the nonsheared regions allows sandine to crystallize, whereas the lower activity of water in the areas of active shearing causes leucite to crystallize.

On the Relation between Photospheric Flow Fields and the Magnetic Field Distribution on the Solar Surface

DTIC Science & Technology

1988-04-15

granules typically last 10-15 minutes. measure- the divergence of the flow field, and (d) the SOUP flow field muerts must be made in a time short...the magnetograms and ary. If so, the random-walk diffusion of magnetic field dii- AV . I, I68 PHOTOSPIIERIC FLOW FIELDS ON SOLAR SURFACE 967 0011 cussd

Design, fabrication and testing of an air-breathing micro direct methanol fuel cell with compound anode flow field

NASA Astrophysics Data System (ADS)

Wang, Luwen; Zhang, Yufeng; Zhao, Youran; An, Zijiang; Zhou, Zhiping; Liu, Xiaowei

2011-10-01

An air-breathing micro direct methanol fuel cell (μDMFC) with a compound anode flow field structure (composed of the parallel flow field and the perforated flow field) is designed, fabricated and tested. To better analyze the effect of the compound anode flow field on the mass transfer of methanol, the compound flow field with different open ratios (ratio of exposure area to total area) and thicknesses of current collectors is modeled and simulated. Micro process technologies are employed to fabricate the end plates and current collectors. The performances of the μDMFC with a compound anode flow field are measured under various operating parameters. Both the modeled and the experimental results show that, comparing the conventional parallel flow field, the compound one can enhance the mass transfer resistance of methanol from the flow field to the anode diffusion layer. The results also indicate that the μDMFC with an anode open ratio of 40% and a thickness of 300 µm has the optimal performance under the 7 M methanol which is three to four times higher than conventional flow fields. Finally, a 2 h stability test of the μDMFC is performed with a methanol concentration of 7 M and a flow velocity of 0.1 ml min-1. The results indicate that the μDMFC can work steadily with high methanol concentration.

Fuel cell stack with passive air supply

DOEpatents

Ren, Xiaoming; Gottesfeld, Shimshon

2006-01-17

A fuel cell stack has a plurality of polymer electrolyte fuel cells (PEFCs) where each PEFC includes a rectangular membrane electrode assembly (MEA) having a fuel flow field along a first axis and an air flow field along a second axis perpendicular to the first axis, where the fuel flow field is long relative to the air flow field. A cathode air flow field in each PEFC has air flow channels for air flow parallel to the second axis and that directly open to atmospheric air for air diffusion within the channels into contact with the MEA.

The Anatomy of the Blue Dragon: Changes in Lava Flow Morphology and Physical Properties Observed in an Open Channel Lava Flow as a Planetary Analogue

NASA Astrophysics Data System (ADS)

Sehlke, A.; Kobs-Nawotniak, S. E.; Hughes, S. S.; Sears, D. W. G.; Downs, M.; Whittington, A. G.; Lim, D. S. S.; Heldmann, J. L.

2017-12-01

Lava terrains on other planets and moons exhibit morphologies similar to those found on Earth, such as smooth pāhoehoe transitioning to rough `a`ā terrains based on the viscosity - strain rate relationship of the lava. Therefore, the morphology of lava flows is governed by eruptive conditions such as effusion rate, underlying slope, and the fundamental thermo-physical properties of the lava, including temperature (T), composition (X), viscosity (η), fraction of crystals (φc) and vesicles (φb), as well as bulk density (ρ). These textural and rheological changes were previously studied for Hawaiian lava, where the lava flow started as channelized pāhoehoe and transitioned into `a`ā, demonstrating a systematic trend in T, X, η, φc, φb, and ρ. NASA's FINESSE focuses on Science and Exploration through analogue research. One of the field sites is Craters of the Moon, Idaho. We present field work done at a 3.0 km long lava flow belonging to the Blue Dragon lavas erupted from a chain of spatter cones, which then coalesced into channelized flows. We acquired UAV imagery along the entire length of the flow, and generated a high resolution DTM of 5 cm/pixel, from which we derived height profiles and surface roughness values. Field work included mapping the change in surface morphology and sample collection every 150 meters. In the laboratory, we measured φc, φb, and ρ for all collected samples. Viscosity measurements were carried out by concentric cylinder viscometry at subliquidus temperatures between 1310ºC to 1160ºC to study the rheology of the lava, enabling us to relate changes in flow behavior to T and φc. Our results are consistent with observations made for Hawaiian lava, including increasing bulk density downflow, and porosity changing from connected to isolated pore space. Crystallinity increases downflow, and the transition from pāhoehoe to `a`ā occurs between 1230ºC to 1150ºC, which is prompted by nucleation and growth of plagioclase microcrystals, strongly increasing the viscosity of the lava several orders of magnitude. The results of this study allows us to correlate T, X, η, φc, φb, and ρ to the lava flow morphology expressed as surface roughness, which can then be used as a tool to infer these physical properties of the rocks for open channel lava flows on other airless bodies, such as the Moon and Mercury, based on DTMs.

Martian Polar Caps: Folding, Faulting, Flowing Glaciers of Multiple Interbedded Ices

NASA Astrophysics Data System (ADS)

Kargel, J. S.

2001-12-01

The Martian south polar cap (permanent CO2 cap and polar layered deposits), exhibit abundant, varied, and widespread deformational phenomena. Folding and boudinage are very common. Strike-slip or normal faults are rarer. Common in the vicinity of major troughs and scarps are signs of convergent flow tectonics manifested as wrinkle-ridge-like surface folds, thrust faults, and viscous forebulges with thin-skinned extensional crevasses and wrinkle-ridge folds. Such flow convergence is predicted by theory. Boudinage and folding at the 300-m wavelength scale, indicating rheologically contrasting materials, is widely exposed at deep levels along erosional scarps. Independent morphologic evidence indicates south polar materials of contrasting volatility. Hence, the south polar cap appears to be a multiphase structure of interbedded ices. The north polar cap locally also exhibits flow indicators, though they are neither as common nor as varied as in the south. The large-scale quasi-spiral structure of the polar caps could be a manifestation of large-scale boudinage. According to this scenario, deep-level boudinage continuously originates under the glacial divide (the polar cap summit). Rod-like boudin structures are oriented transverse to flow and migrate outward with the large-scale flow field. Troughs develop over areas between major boudins. A dynamic competition, and possibly a rough balance, develops between the local flow field in the vicinity of a trough (which tends to close the trough by lateral closure and upwelling flow) and sublimation erosion (which tends to widen and deepen them). Over time, the troughs flow to the margins of the polar cap where they, along with other polar structures, are destroyed by sublimation. Major ice types contributing to rheological and volatility layering may include, in order of highest to lowest mechanical strength, CO2 clathrate hydrate, water ice containing inert/insoluble dust, pure water ice, water ice containing traces of liquid-soluble salts, water ice containing traces of solid-soluble acids, CO2 ice. This is also nearly the same sequence of highest to lowest melting/dissociation points, but it is different than the sequence of volatility. This geologic-structural interpretation and specific chemical models are amenable to testing by computational means and point the way toward future needed observations, including complete high-resolution imaging of the polar caps, measurement of flow fields (possibly by laser interferometry), mapping of subsurface structures (by radar and/or seismic methods), and determination of composition (by penetrators, drillers, or borers). New lab data are needed on the physical properties of candidate ices.

Geometric and compositional factors on critical current density in YBa2Cu3O7‑δ films containing nanorods

NASA Astrophysics Data System (ADS)

Horide, Tomoya; Nagao, Sho; Izutsu, Ryosuke; Ishimaru, Manabu; Kita, Ryusuke; Matsumoto, Kaname

2018-06-01

Critical current density (J c) was investigated in YBa2Cu3O7‑δ films containing nanorods prepared with various nanorod materials, with variation of nanorod content, substrate temperature, and oxidization condition. Three types of compositional situation were realized: films containing strain induced oxygen vacancies; fully oxidized films containing cation compositional deviation; and oxygen deficient films. Normalized J c‑B behavior was determined via the matching field, which is a geometric factor, regardless of the compositional details. A J c‑critical temperature (T c) relation depending on distribution and fraction of compositional deviation (cation compositional deviation and strain induced oxygen vacancies) was found: the J c values decreased with decreasing T c due to the effect of T c on nanorod pinning strength in the fully oxidized films; J c decreased with decreasing oxygen pressure in the film cooling process after film deposition in spite of T c remaining almost the same, due to reduction of the effective area for current flow in the oxygen deficient films. Thus, a J c landscape based on geometric and compositional factors was obtained. The study highlights the importance of the J c‑T c analysis in the understanding of J c in YBa2Cu3O7‑δ films containing nanorods.

Measurements of non-reacting and reacting flow fields of a liquid swirl flame burner

NASA Astrophysics Data System (ADS)

Chong, Cheng Tung; Hochgreb, Simone

2015-03-01

The understanding of the liquid fuel spray and flow field characteristics inside a combustor is crucial for designing a fuel efficient and low emission device. Characterisation of the flow field of a model gas turbine liquid swirl burner is performed by using a 2-D particle imaging velocimetry(PIV) system. The flow field pattern of an axial flow burner with a fixed swirl intensity is compared under confined and unconfined conditions, i.e., with and without the combustor wall. The effect of temperature on the main swirling air flow is investigated under open and non-reacting conditions. The result shows that axial and radial velocities increase as a result of decreased flow density and increased flow volume. The flow field of the main swirling flow with liquid fuel spray injection is compared to non-spray swirling flow. Introduction of liquid fuel spray changes the swirl air flow field at the burner outlet, where the radial velocity components increase for both open and confined environment. Under reacting condition, the enclosure generates a corner recirculation zone that intensifies the strength of radial velocity. The reverse flow and corner recirculation zone assists in stabilizing the flame by preheating the reactants. The flow field data can be used as validation target for swirl combustion modelling.

Fluid flow and assessment of the leakage potential in the Snohvit reservoir and overburden in the Barents Sea

NASA Astrophysics Data System (ADS)

Tasianas, A.

2012-12-01

Department of Geology, University of Tromsø, Dramsveien 201, 9037 Tromsø, Norway Abstract ____________________________________________________________________________ The Snøhvit reservoir and overburden have been an important location for testing Carbon Capture and Storage (CCS) techniques. Fluid flow in the region is caused mainly by repeated glacial cycles and differential geographic uplift, which caused tilting and spilling of various structural traps in the area. Geological modeling, undertaken as part of the ECO2 project activities, has allowed to model the local stratigraphy and any potential fluid flow pathways in order to determine how effective CCS would be in the area. 3D seismic data related to cube ST0306 from the Hammerfest Sedimentary Basin (HFB), covering the Snohvit and Albatross fields, were used to better understand the pathways and mechanisms related to fluid flow in the area and thus propose also potential leakage scenarios. The inclusion of geological features such as gas chimneys, faults, wells, pockmarks at the seabed and vertical fluid flow structures underlying the pockmarks in the models has also allowed to accurately simulate fluid flow through realistic geological models. Leaking of CO2 from the Tubåen Formation (Fm) can partially migrate upwards to the Hekkingen Fm or less deep formations via the faults. If leaking reaches the tertiary faults, CO2 can migrate through the Top kvitting Fm and maybe continue via pipe structures, faults or the clinoforms of the Torsk Fm and accumulate under the Upper Regional Unconformity (URU). The presence of pockmarks at the seabed could indicate further leakage between the URU and the seabed via vertical fluid flow structures underlying the pockmarks. Depending on the leakage mode, models of different types of domain size and grid resolution were created and populated with properties such as porosity (SPhi), vertical permeability (kv), horizontal permeability (Kh), anisotropy ratio (AnIso), Total Oganic Carbon, [Cl],[CaCO3], [CH4] and various alkalinities. A temperature vs depth profile (Trock) and a lithology model were also associated with it. Modelling results indicate that the most likely sites for leakage, when the crust is subject to erosion-related compressive stresses, would be the faults. The possible presence of any gas hydrates above the BSR could act as a seal for the free gas accumulating below the BSR. This reason as well as the fact that we don't expect any major stress changes in the region in the next few Million years signifies that the faults should remain sealing and thus prevent any CO2 leakage. Preliminary simulation results indicate highest saturation values of CO2 near the base of the overburden with no signs of any CO2 reaching the seabed, thus reducing to a minimum the threat of any contamination to the seawater and marine wildlife. Both Composition 2 and 3 gas hydrates are stable, providing a supplementary sealing effect that prevents any potential leaking fluid reaching the seabed. The study area is however lying outside the Composition 1 pure methane gas hydrate stability field. Any fluid with such composition leaking from the reservoir will thus not form gas hydrates. Keywords : geological modeling, CO2, fluid flow, leakage mechanisms, gas hydrate

Inlet flow field investigation. Part 1: Transonic flow field survey

NASA Technical Reports Server (NTRS)

Yetter, J. A.; Salemann, V.; Sussman, M. B.

1984-01-01

A wind tunnel investigation was conducted to determine the local inlet flow field characteristics of an advanced tactical supersonic cruise airplane. A data base for the development and validation of analytical codes directed at the analysis of inlet flow fields for advanced supersonic airplanes was established. Testing was conducted at the NASA-Langley 16-foot Transonic Tunnel at freestream Mach numbers of 0.6 to 1.20 and angles of attack from 0.0 to 10.0 degrees. Inlet flow field surveys were made at locations representative of wing (upper and lower surface) and forebody mounted inlet concepts. Results are presented in the form of local inlet flow field angle of attack, sideflow angle, and Mach number contours. Wing surface pressure distributions supplement the flow field data.

On the role of particle cracking in flow and fracture of metal matrix composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brockenbrough, J.R.; Zok, F.W.

1995-01-01

The flow response of particle-reinforced metal matrix composites is studied using finite element methods. Unit cells containing either intact or cracked particles in a power law hardening matrix are used to determine the corresponding asymptotic flow strengths. The effects of the hardening exponent and the elastic mismatch between the particles and the matrix on the flow response are examined. For comparison, the flow response of power law hardening solids containing penny-shaped cracks is also evaluated. The latter results are found to be in reasonable agreement with those corresponding to composites that contain low volume fractions of cracked particles. The asymptoticmore » results are used to develop a one-dimensional constitutive law for composites which undergo progressive damage during tensile straining. This law is used to evaluate the strain at the onset of plastic instability. It is proposed that the instability strain be used as a measure of tensile ductility when the particle content is low and the particles are uniformly distributed through the matrix.« less

An LES-PBE-PDF approach for modeling particle formation in turbulent reacting flows

NASA Astrophysics Data System (ADS)

Sewerin, Fabian; Rigopoulos, Stelios

2017-10-01

Many chemical and environmental processes involve the formation of a polydispersed particulate phase in a turbulent carrier flow. Frequently, the immersed particles are characterized by an intrinsic property such as the particle size, and the distribution of this property across a sample population is taken as an indicator for the quality of the particulate product or its environmental impact. In the present article, we propose a comprehensive model and an efficient numerical solution scheme for predicting the evolution of the property distribution associated with a polydispersed particulate phase forming in a turbulent reacting flow. Here, the particulate phase is described in terms of the particle number density whose evolution in both physical and particle property space is governed by the population balance equation (PBE). Based on the concept of large eddy simulation (LES), we augment the existing LES-transported probability density function (PDF) approach for fluid phase scalars by the particle number density and obtain a modeled evolution equation for the filtered PDF associated with the instantaneous fluid composition and particle property distribution. This LES-PBE-PDF approach allows us to predict the LES-filtered fluid composition and particle property distribution at each spatial location and point in time without any restriction on the chemical or particle formation kinetics. In view of a numerical solution, we apply the method of Eulerian stochastic fields, invoking an explicit adaptive grid technique in order to discretize the stochastic field equation for the number density in particle property space. In this way, sharp moving features of the particle property distribution can be accurately resolved at a significantly reduced computational cost. As a test case, we consider the condensation of an aerosol in a developed turbulent mixing layer. Our investigation not only demonstrates the predictive capabilities of the LES-PBE-PDF model but also indicates the computational efficiency of the numerical solution scheme.

Formation and evolution of a metasomatized lithospheric root at the motionless Antarctic plate: the case of East Island, Crozet Archipelago (Indian Ocean)

NASA Astrophysics Data System (ADS)

Meyzen, Christine; Marzoli, Andrea; Bellieni, Giuliano; Levresse, Gilles

2016-04-01

Sitting atop the nearly stagnant Antarctic plate (ca. 6.46 mm/yr), the Crozet archipelago midway between Madagascar and Antarctica constitutes a region of unusually shallow (1543-1756 m below sea level) and thickened oceanic crust (10-16.5 km), high geoid height, and deep low-velocity zone, which may reflect the surface expression of a mantle plume. Here, we present new major and trace element data for Quaternary sub-aerial alkali basalts from East Island, the easterly and oldest island (ca. 9 Ma) of the Crozet archipelago. Crystallization at uppermost mantle depth and phenocryst accumulation have strongly affected their parental magma compositions. Their trace element patterns show a large negative K anomaly relative to Ta-La, moderate depletions in Rb and Ba with respect to Th-U, and heavy rare earth element (HREE) depletions relative to light REE. These characteristics allow limits to be placed upon the composition and mineralogy of their mantle source. The average trace element spectrum of East Island basalts can be matched by melting of about 2 % of a garnet-phlogopite-bearing peridotite source. The stability field of phlogopite restricts melting depth to lithospheric levels. The modelled source composition requires a multistage evolution, where the mantle has been depleted by melt extraction before having been metasomatized by alkali-rich plume melts. The depleted mantle component may be sourced by residual mantle plume remnants stagnated at the melting locus due to a weak lateral flow velocity inside the melting regime, whose accumulation progressively edifies a depleted lithospheric root above the plume core. Low-degree alkali-rich melts are likely derived from the plume source. Such a mantle source evolution may be general to both terrestrial and extraterrestrial environments where the lateral component velocity of the mantle flow field is extremely slow.

Redox flow batteries with serpentine flow fields: Distributions of electrolyte flow reactant penetration into the porous carbon electrodes and effects on performance

NASA Astrophysics Data System (ADS)

Ke, Xinyou; Prahl, Joseph M.; Alexander, J. Iwan D.; Savinell, Robert F.

2018-04-01

Redox flow batteries with flow field designs have been demonstrated to boost their capacities to deliver high current density and power density in medium and large-scale energy storage applications. Nevertheless, the fundamental mechanisms involved with improved current density in flow batteries with serpentine flow field designs have been not fully understood. Here we report a three-dimensional model of a serpentine flow field over a porous carbon electrode to examine the distributions of pressure driven electrolyte flow penetrations into the porous carbon electrodes. We also estimate the maximum current densities associated with stoichiometric availability of electrolyte reactant flow penetrations through the porous carbon electrodes. The results predict reasonably well observed experimental data without using any adjustable parameters. This fundamental work on electrolyte flow distributions of limiting reactant availability will contribute to a better understanding of limits on electrochemical performance in flow batteries with serpentine flow field designs and should be helpful to optimizing flow batteries.

The effect of different beverages on the color and translucency of flowable composites.

PubMed

Karadas, Muhammet

2016-11-01

This study examined the changes in color and translucency of flowable composites after immersion in different beverages. Thirty composite samples were prepared from four flowable composites (G-aenial Universal Flo, Filtek Ultimate, Esthelite Flow Quick, and Clearfil Majesty ES Flow) and a microhybrid composite (Filtek Z-250) and stored in distilled water at 37°C for 24 h. The samples were randomly divided into seven groups and then immersed in different beverages (Red Bull, coffee, black tea, Pepsi Cola, orange juice, and distilled water) for 7 days. The CIE L*a*b* values of each sample were measured against white and black backgrounds using a spectrophotometer before and after immersion. Data were analyzed using two-way analysis of variance and Tukey's post-hoc test (p < 0.05). The color changes were significantly different among the composite materials after immersion in beverages (p < 0.05). Filtek Ultimate and Esthelite Flow Quick exhibited less discoloration than did G-aenial Universal Flo and Clearfil Majesty ES Flow. No significant difference was found between Filtek Z-250 and either Filtek Ultimate or Esthelite Flow Quick (p > 0.05). Among the beverages, black tea and coffee caused the highest discoloration of all the materials. Immersion in coffee and black tea resulted in the highest negative changes in the translucency of the materials. The degree of discoloration for the composite resins depended on the material used and drinking beverage. SCANNING 38:701-709, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Lava flow field emplacement studies of Manua Ulu (Kilauea Volcano, Hawai'i, United States) and Venus, using field and remote sensing analyses

NASA Astrophysics Data System (ADS)

Byrnes, Jeffrey Myer

2002-04-01

This work examines lava emplacement processes by characterizing surface units using field and remote sensing analyses in order to understand the development of lava flow fields. Specific study areas are the 1969--1974 Mauna Ulu compound flow field, (Kilauea Volcano, Hawai'i, USA), and five lava flow fields on Venus: Turgmam Fluctus, Zipaltonal Fluctus, the Tuli Mons/Uilata Fluctus flow complex, the Var Mons flow field, and Mylitta Fluctus. Lava surface units have been examined in the field and with visible-, thermal-, and radar-wavelength remote sensing datasets for Mauna Ulu, and with radar data for the Venusian study areas. For the Mauna Ulu flow field, visible characteristics are related to color, glass abundance, and dm- to m-scale surface irregularities, which reflect the lava flow regime, cooling, and modification due to processes such as coalescence and inflation. Thermal characteristics are primarily affected by the abundance of glass and small-scale roughness elements (such as vesicles), and reflect the history of cooling, vesiculation and degassing, and crystallization of the lava. Radar characteristics are primarily affected by unit topography and fracturing, which are related to flow inflation, remobilization, and collapse, and reflect the local supply of lava during and after unit emplacement. Mauna Ulu surface units are correlated with pre-eruption topography, lack a simple relationship to the main feeder lava tubes, and are distributed with respect to their position within compound flow lobes and with distance from the vent. The Venusian lava flow fields appear to have developed through emplacement of numerous, thin, simple and compound flows, presumably over extended periods of time, and show a wider range of radar roughness than is observed at Mauna Ulu. A potential correlation is suggested between flow rheology and surface roughness. Distributary flow morphologies may result from tube-fed flows, and flow inflation is consistent with observed surface characteristics. Furthermore, the significance of inflation at Mauna Ulu and comparison of radar characteristics indicates that inflation may, in fact, be more prevalent on Venus than at Mauna Ulu. Although the Venusian flow fields display morphologies similar to those observed within terrestrial flow fields, the Venusian flow units are significantly larger.

Numerical Investigation of Near-Field Plasma Flows in Magnetic Nozzles

NASA Technical Reports Server (NTRS)

Sankaran, Kamesh; Polzin, Kurt A.

2009-01-01

The development and application of a multidimensional numerical simulation code for investigating near-field plasma processes in magnetic nozzles are presented. The code calculates the time-dependent evolution of all three spatial components of both the magnetic field and velocity in a plasma flow, and includes physical models of relevant transport phenomena. It has been applied to an investigation of the behavior of plasma flows found in high-power thrusters, employing a realistic magnetic nozzle configuration. Simulation of a channel-flow case where the flow was super-Alfvenic has demonstrated that such a flow produces adequate back-emf to significantly alter the shape of the total magnetic field, preventing the flow from curving back to the magnetic field coil in the near-field region. Results from this simulation can be insightful in predicting far-field behavior and can be used as a set of self-consistent boundary conditions for far-field simulations. Future investigations will focus on cases where the inlet flow is sub-Alfvenic and where the flow is allowed to freely expand in the radial direction once it is downstream of the coil.

Groundwater Conditions and Studies in the Albany Area of Dougherty County, Georgia, 2008

USGS Publications Warehouse

Gordon, Debbie W.

2009-01-01

The U.S. Geological Survey has been working cooperatively with the Albany Water, Gas, and Light Commission to monitor groundwater quality and availability since 1977. This report presents an overview of groundwater conditions and studies in the Albany area of Dougherty County, Georgia, during 2008. Historical data also are presented for comparison with 2008 data. Ongoing monitoring activities include continuous water-level recording in 24 wells and periodic water-level measurements in 5 wells. During 2008, water levels in 10 of the continuous-recording wells were below normal, corresponding to lower than average rainfall. Groundwater samples collected from 25 wells in the Upper Floridan aquifer indicate that nitrate levels during 2008 were similar to values from 2007, with a maximum of 12.5 milligrams per liter at one well. Water samples collected from the Flint River and wells at the Albany well field were analyzed and plotted on a trilinear diagram to show the percent composition of selected major cations and anions. Groundwater constituents (major cations and anions) of the Upper Floridan aquifer at the Albany well field remain distinctly different from those in the water of the Flint River. To improve the understanding of the groundwater-flow system and nitrate movement in the Upper Floridan aquifer, the U.S. Geological Survey is developing a groundwater-flow model in the Albany area of southwestern Georgia. The model is being calibrated to simulate periods of dry (October 1999) hydrologic conditions. Preliminary results of particle tracking indicate that water flows to the well field from the northwest.

Influence of composition of functional additives and deformation modes on flow behavior of polymer composite materials

NASA Astrophysics Data System (ADS)

Onoprienko, N. N.; Rahimbaev, Sh M.

2018-03-01

The paper presents the results of the influence of composition of functional water-soluble polymers and viscosity of domestic and foreign one-percent water solution polymer on flow parameters of cement and polymer test. It also gives the results of rheogoniometry of Eunice Granit tile adhesive used for large-size plates from natural stone and ceramic granite.

Cutting through the smoke: the diversity of microorganisms in deep-sea hydrothermal plumes

PubMed Central

Mikalsen, Svein-Ole; Giebel, Helge-Ansgar; Rogers, Alex D.

2017-01-01

There are still notable gaps regarding the detailed distribution of microorganisms between and within insular habitats such as deep-sea hydrothermal vents. This study investigates the community composition of black smoker vent microorganisms in the Southern Hemisphere, and changes thereof along a spatial and chemical gradient ranging from the vent plume to surrounding waters. We sampled two hydrothermal vent fields, one at the South West Indian Ridge (SWIR), the other at the East Scotia Ridge (ESR). Samples were collected across vent fields at varying vertical distances from the origin of the plumes. The microbial data were sequenced on an Illumina MiSeq platform for the 16SrRNA gene. A substantial amount of vent-specific putative chemosynthetic microorganisms were found, particularly in samples from focused hydrothermal venting. Common vent-specific organisms from both vent fields were the genera Arcobacter, Caminibacter and Sulfurimonas from the Epsilonproteobacteria and the SUP05 group from the Gammaproteobacteria. There were no major differences in microbial composition between SWIR and ESR for focused plume samples. However, within the ESR the diffuse flow and focused samples differed significantly in microbial community composition and relative abundance. For Epsilonproteobacteria, we found evidence of niche-specificity to hydrothermal vent environments. This taxon decreased in abundance by three orders of magnitude from the vent orifice to background water. Epsilonproteobacteria distribution followed a distance–decay relationship as vent-effluents mixed with the surrounding seawater. This study demonstrates strong habitat affinity of vent microorganisms on a metre scale with distinct environmental selection. PMID:28484604

Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics.

PubMed

Cebral, J R; Mut, F; Chung, B J; Spelle, L; Moret, J; van Nijnatten, F; Ruijters, D

2017-06-01

Hemodynamics is thought to be an important factor for aneurysm progression and rupture. Our aim was to evaluate whether flow fields reconstructed from dynamic angiography data can be used to realistically represent the main flow structures in intracranial aneurysms. DSA-based flow reconstructions, obtained during interventional treatment, were compared qualitatively with flow fields obtained from patient-specific computational fluid dynamics models and quantitatively with projections of the computational fluid dynamics fields (by computing a directional similarity of the vector fields) in 15 cerebral aneurysms. The average similarity between the DSA and the projected computational fluid dynamics flow fields was 78% in the parent artery, while it was only 30% in the aneurysm region. Qualitatively, both the DSA and projected computational fluid dynamics flow fields captured the location of the inflow jet, the main vortex structure, the intrasaccular flow split, and the main rotation direction in approximately 60% of the cases. Several factors affect the reconstruction of 2D flow fields from dynamic angiography sequences. The most important factors are the 3-dimensionality of the intrasaccular flow patterns and inflow jets, the alignment of the main vortex structure with the line of sight, the overlapping of surrounding vessels, and possibly frame rate undersampling. Flow visualization with DSA from >1 projection is required for understanding of the 3D intrasaccular flow patterns. Although these DSA-based flow quantification techniques do not capture swirling or secondary flows in the parent artery, they still provide a good representation of the mean axial flow and the corresponding flow rate. © 2017 by American Journal of Neuroradiology.

A robust and fast method of sampling and analysis of delta13C of dissolved inorganic carbon in ground waters.

PubMed

Spötl, Christoph

2005-09-01

The stable carbon isotopic composition of dissolved inorganic carbon (delta13C(DIC)) is traditionally determined using either direct precipitation or gas evolution methods in conjunction with offline gas preparation and measurement in a dual-inlet isotope ratio mass spectrometer. A gas evolution method based on continuous-flow technology is described here, which is easy to use and robust. Water samples (100-1500 microl depending on the carbonate alkalinity) are injected into He-filled autosampler vials in the field and analysed on an automated continuous-flow gas preparation system interfaced to an isotope ratio mass spectrometer. Sample analysis time including online preparation is 10 min and overall precision is 0.1 per thousand. This method is thus fast and can easily be automated for handling large sample batches.

Optimizing gas transfer to improve growth rate of Haematococcus pluvialis in a raceway pond with chute and oscillating baffles.

PubMed

Yang, Zongbo; Cheng, Jun; Li, Ke; Zhou, Junhu; Cen, Kefa

2016-08-01

Up-down chute and oscillating (UCO) baffles were used to generate vortex and oscillating flow field to improve growth rate of Haematococcus pluvialis in a raceway pond. Effects of gas flow rate, solution velocity, and solution depth on solution mass transfer coefficient and mixing time were evaluated using online pH and dissolved oxygen probes. Mass transfer coefficient increased by 1.3 times and mixing time decreased by 33% when UCO baffles were used in the H. pluvialis solution, resulting in an 18% increase in biomass yield with 2% CO2. The H. pluvialis biomass yield further increased to 1.5g/L, and astaxanthin composition accumulated to 29.7mg/L under relatively higher light intensity and salinity. Copyright © 2016 Elsevier Ltd. All rights reserved.

Numerical studies of the polymer melt flow in the extruder screw channel and the forming tool

NASA Astrophysics Data System (ADS)

Ershov, S. V.; Trufanova, N. M.

2017-06-01

To date, polymer compositions based on polyethylene or PVC is widely used as insulating materials. These materials processing conjugate with a number of problems during selection of the rational extrusion regimes. To minimize the time and cost when determining the technological regime uses mathematical modeling techniques. The paper discusses heat and mass transfer processes in the extruder screw channel, output adapter and the cable head. During the study were determined coefficients for three rheological models based on obtained viscosity vs. shear rate experimental data. Also a comparative analysis of this viscosimetric laws application possibility for studying polymer melt flow during its processing on the extrusion equipment was held. As a result of numerical study the temperature, viscosity and shear rate fields in the extruder screw channel and forming tool were obtained.

Surface configuration as an explanation for lithology-related cross-polarized radar image anomalies

NASA Technical Reports Server (NTRS)

Mccauley, J. R.

1973-01-01

One problem that has persisted since the development of multipolarized radar is the cause or causes of differential depolarization which is expressed as tonal reversals between like- and cross-polarized images of certain outcrops. Rocks producing anomalously low returns on the cross-polarized image could be classed into three general types: (1) certain geologically recent lava flows (late Pleistocene and Holocene), (2) some tertiary volcanics and (3) certain massive sandstones. Differential depolarization has been produced by volcanic rocks of various compositions including rhyolite, rhyodacite, dacite, andesite, and basalt. This has led to the conclusion that differential depolarization is not directly caused by any compositional factor. However, the study of aerial photos and subsequent field observation have led to the conclusion that the weathering and other surface characteristics of the outcrops are responsible for their appearance on multipolarized imagery.

Hydrodynamic flows of non-Fermi liquids: Magnetotransport and bilayer drag

NASA Astrophysics Data System (ADS)

Patel, Aavishkar A.; Davison, Richard A.; Levchenko, Alex

2017-11-01

We consider a hydrodynamic description of transport for generic two-dimensional electron systems that lack Galilean invariance and do not fall into the category of Fermi liquids. We study magnetoresistance and show that it is governed only by the electronic viscosity provided that the wavelength of the underlying disorder potential is large compared to the microscopic equilibration length. We also derive the Coulomb drag transresistance for double-layer non-Fermi-liquid systems in the hydrodynamic regime. As an example, we consider frictional drag between two quantum Hall states with half-filled lowest Landau levels, each described by a Fermi surface of composite fermions coupled to a U (1 ) gauge field. We contrast our results to prior calculations of drag of Chern-Simons composite particles and place our findings in the context of available experimental data.

Remedial investigation sampling and analysis plan for J-Field, Aberdeen Proving Ground, Maryland. Volume 1: Field Sampling Plan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benioff, P.; Biang, R.; Dolak, D.

1995-03-01

The Environmental Management Division (EMD) of Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation and feasibility study (RI/FS) of the J-Field area at APG pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. J-Field is within the Edgewood Area of APG in Harford County, Maryland (Figure 1. 1). Since World War II activities in the Edgewood Area have included the development, manufacture, testing, and destruction of chemical agents and munitions. These materials were destroyed at J-Field by open burning and open detonation (OB/OD). Considerable archival information about J-Field exists as a result of effortsmore » by APG staff to characterize the hazards associated with the site. Contamination of J-Field was first detected during an environmental survey of the Edgewood Area conducted in 1977 and 1978 by the US Army Toxic and Hazardous Materials Agency (USATHAMA) (predecessor to the US Army Environmental Center [AEC]). As part of a subsequent USATHAMA -environmental survey, 11 wells were installed and sampled at J-Field. Contamination at J-Field was also detected during a munitions disposal survey conducted by Princeton Aqua Science in 1983. The Princeton Aqua Science investigation involved the installation and sampling of nine wells and the collection and analysis of surficial and deep composite soil samples. In 1986, a Resource Conservation and Recovery Act (RCRA) permit (MD3-21-002-1355) requiring a basewide RCRA Facility Assessment (RFA) and a hydrogeologic assessment of J-Field was issued by the US Environmental Protection Agency (EPA). In 1987, the US Geological Survey (USGS) began a two-phased hydrogeologic assessment in data were collected to model, groundwater flow at J-Field. Soil gas investigations were conducted, several well clusters were installed, a groundwater flow model was developed, and groundwater and surface water monitoring programs were established that continue today.« less

Electric-field-induced flow-aligning state in a nematic liquid crystal.

PubMed

Fatriansyah, Jaka Fajar; Orihara, Hiroshi

2015-04-01

The response of shear stress to a weak ac electric field as a probe is measured in a nematic liquid crystal under shear flow and dc electric fields. Two states with different responses are clearly observed when the dc electric field is changed at a constant shear rate: the flow aligning and non-flow aligning states. The director lies in the shear plane in the flow aligning state and out of the plane in the non-flow aligning state. Through application of dc electric field, the non-flow aligning state can be changed to the flow aligning state. In the transition from the flow aligning state to the non-flow aligning state, it is found that the response increases and the relaxation time becomes longer. Here, the experimental results in the flow aligning state are discussed on the basis of the Ericksen-Leslie theory.

Effect of flow field on the performance of an all-vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Kumar, S.; Jayanti, S.

2016-03-01

A comparative study of the electrochemical energy conversion performance of a single-cell all-vanadium redox flow battery (VRFB) fitted with three flow fields has been carried out experimentally. The charge-discharge, polarization curve, Coulombic, voltage and round-trip efficiencies of a 100 cm2 active area VRFB fitted with serpentine, interdigitated and conventional flow fields have been obtained under nearly identical experimental conditions. The effect of electrolyte circulation rate has also been investigated for each flow field. Stable performance has been obtained for each flow field for at least 40 charge/discharge cycles. Ex-situ measurements of pressure drop have been carried out using water over a range of Reynolds numbers. Together, the results show that the cell fitted with the serpentine flow field gives the highest energy efficiency, primarily due to high voltaic efficiency and also the lowest pressure drop. The electrolyte flow rate is seen to have considerable effect on the performance; a high round-trip energy efficiency of about 80% has been obtained at the highest flow rate with the serpentine flow field. The data offer interesting insights into the effect of electrolyte circulation on the performance of VRFB.

Dependence of Laminar Flow Fluctuation on Indium Composition in In0.07GaAs/GaAs Quantum Wells for 940-nm Infrared Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Kim, Dae-Kwang; Lee, Hyung-Joo; An, Won-Chan; Kim, Hong-Gun; Kwac, Lee-Ku

2018-05-01

The effect of laminar flow fluctuation on the indium composition of In0.07GaAs quantum wells was investigated in order to obtain a higher output power from infrared lighting-emitting diodes (IR-LEDs) having a 940-nm wavelength. By controlling the injection pressure, we obtained various laminar flow conditions. Through subsequent photoluminescence (PL) and X-ray diffraction (XRD) measurements, a noticeable improvement in the optical and the crystalline characteristics of the In0.07GaAs quantum wells was observed at an optimum laminar flow. This result could be attributed to a reduction of non-crystallization in InGaAs quantum wells that had their indium composition improved via the optimized laminar flow. Overall, a significantly improved output power (11.2 mW) was obtained from a 940-nm IR-LED chip fabricated at an optimum laminar flow of 500 sccm, and a remarkable increase of approximately 250% was displayed compared to a conventional chip (3.9 mW) fabricated at a laminar flow of 100 sccm.

Autoclave processing for composite material fabrication. 1: An analysis of resin flows and fiber compactions for thin laminate

NASA Technical Reports Server (NTRS)

Hou, T. H.

1985-01-01

High quality long fiber reinforced composites, such as those used in aerospace and industrial applications, are commonly processed in autoclaves. An adequate resin flow model for the entire system (laminate/bleeder/breather), which provides a description of the time-dependent laminate consolidation process, is useful in predicting the loss of resin, heat transfer characteristics, fiber volume fraction and part dimension, etc., under a specified set of processing conditions. This could be accomplished by properly analyzing the flow patterns and pressure profiles inside the laminate during processing. A newly formulated resin flow model for composite prepreg lamination process is reported. This model considers viscous resin flows in both directions perpendicular and parallel to the composite plane. In the horizontal direction, a squeezing flow between two nonporous parallel plates is analyzed, while in the vertical direction, a poiseuille type pressure flow through porous media is assumed. Proper force and mass balances have been made and solved for the whole system. The effects of fiber-fiber interactions during lamination are included as well. The unique features of this analysis are: (1) the pressure gradient inside the laminate is assumed to be generated from squeezing action between two adjacent approaching fiber layers, and (2) the behavior of fiber bundles is simulated by a Finitely Extendable Nonlinear Elastic (FENE) spring.

Hydrodynamic implications of textural trends in sand deposits of the 2004 tsunami in Sri Lanka

USGS Publications Warehouse

Morton, R.A.; Goff, J.R.; Nichol, S.L.

2008-01-01

Field observations and sediment samples at a coastal-plain setting in southeastern Sri Lanka were used to document the erosional and depositional impacts of the 2004 Indian Ocean tsunami and to interpret the hydrodynamic processes that produced an extensive sand-sheet deposit. Tsunami deposit thicknesses ranged from 6 to 22??cm with thickness being controlled partly by antecedent topography. The deposit was composed of coarse to medium sand organized into plane-parallel laminae and a few laminasets. Vertical textural trends showed an overall but non-systematic upward fining and upward thinning of depositional units with an upward increase in heavy-mineral laminations at some locations. Repeated patterns in the vertical textural trends (upward fining, upward coarsening, uniform) were used to subdivide and correlate the deposit into five hydro-textural stratigraphic units. The depositional units were linked to hydrodynamic processes and upcurrent conditions, such as rates of sediment supply and composition of the sediment sources. Vertical changes in grain-size distributions recorded the depositional phases associated with flow acceleration, initial unsteady pulsating flow, relatively stable and uniform flow, flow deceleration, slack water, and return flow or flow redirection. Study results suggest that vertical textural trends from multiple cross-shore sections can be used to interpret complex tsunami flow histories, but at the location examined, interpretation of the lateral textural trends did not provide a basis for identifying the correct sediment transport pathways because flow near the landward boundary was multidirectional.

Feral rice from introgression of weedy rice genes into transgenic herbicide-resistant hybrid-rice progeny.

PubMed

Zhang, Jingxu; Kang, Ye; Valverde, Bernal E; Dai, Weimin; Song, Xiaoling; Qiang, Sheng

2018-06-05

Pollen-mediated herbicide-resistance transgene flow occurs bidirectionally between transgenic cultivated rice and weedy rice. The potential risk of weedy traits introgressing into hybrid rice is underestimated and poorly understood. Two of each glufosinate-resistant transgenic rice varieties and hybrid rice (F1) and their succeeding generations (F2-F4) were planted for three years in weedy-rice-free field plots adjacent to experimental weedy-rice fields. Weedy-rice-like (feral) plants, both glufosinate-resistant and with red-pericarp seed, were initially found only among the F3 generations of the two glufosinate-resistant transgenic hybrid rice. The composite fitness (an index based on eight productivity and weediness traits) of the feral progeny was significantly higher than that of glufosinate-resistant transgenic hybrid rice (the original female parent of feral progeny) under common monoculture garden conditions. Hybrid rice progeny segregated into individuals of variable height and extended flowering. Hybrid rice F2 generations had higher outcrossing rates by pollen reception (0.96%-1.65%) than their progenitors (0.07%-0.98%). Herbicide-resistant weedy rice can rapidly arise by pollen-mediated gene flow from weedy to transgenic hybrid rice. Their segregating pollen-receptive progeny pose greater agro-ecological risk than transgenic varieties. The safety assessment and management regulations for transgenic hybrid rice should take into account the risk of bidirectional gene flow.

Hierarchy of facies of pyroclastic flow deposits generated by Laacher See type eruptions

NASA Astrophysics Data System (ADS)

Freundt, A.; Schmincke, H.-U.

1985-04-01

The upper Quaternary pyroclastic flow deposits of Laacher See volcano show compositional and structural facies variations on four different scales: (1) eruptive units of pyroclastic flows, composed of many flow units; (2) depositional cycles of as many as five flow units; flow units containing (3) regional intraflow-unit facies; and (4) local intraflow-unit subfacies. These facies can be explained by successively overlapping processes beginning in the magma column and ending with final deposition. The pyroclastic flow deposits thus reflect major aspects of the eruptive history of Laacher See volcano: (a) drastic changes in eruptive mechanism due to increasing access of water to the magma chamber and (b) change in chemical composition and crystal and gas content as evacuation of a compositionally zoned magma column progressed. The four scales of facies result from four successive sets of processes: (1) differentiation in the magma column and external factors governing the mechanism of eruption; (2) temporal variations of factors inducing eruption column collapse; (3) physical conditions in the eruption column and the way in which its collapse proceeds; and (4) interplay of flow-inherent and morphology-induced transport mechanics.

Bacterial community dynamics in surface flow constructed wetlands for the treatment of swine waste.

PubMed

Ibekwe, A M; Ma, J; Murinda, Shelton; Reddy, G B

2016-02-15

Constructed wetlands are generally used for the removal of waste from contaminated water. In the swine production system, wastes are traditionally flushed into an anaerobic lagoon which is then sprayed on agricultural fields. However, continuous spraying of lagoon wastewater on fields can lead to high N and P accumulations in soil or lead to runoff which may contaminate surface or ground water with pathogens and nutrients. In this study, continuous marsh constructed wetland was used for the removal of contaminants from swine waste. Using pyrosequencing, we assessed bacterial composition within the wetland using principal coordinate analysis (PCoA) which showed that bacterial composition from manure influent and lagoon water were significantly different (P=0.001) from the storage pond to the final effluent. Canonical correspondence analysis (CCA) showed that different bacterial populations were significantly impacted by ammonium--NH4 (P=0.035), phosphate--PO4(3-) (P=0.010), chemical oxygen demand--COD (P=0.0165), total solids--TS (P=0.030), and dissolved solids--DS (P=0.030) removal, with 54% of the removal rate explained by NH4+PO4(3-) according to a partial CCA. Our results showed that different bacterial groups were responsible for the composition of different wetland nutrients and decomposition process. This may be the major reason why most wetlands are very efficient in waste decomposition. Published by Elsevier B.V.

High-Latitude Neutral Density Structures Investigated by Utilizing Multi-Instrument Satellite Data and NRLMSISE-00 Simulations

NASA Astrophysics Data System (ADS)

Horvath, Ildiko; Lovell, Brian C.

2018-02-01

This study investigates various types of neutral density features developed in the cusp region during magnetically active and quiet times. Multi-instrument Challenging Minisatellite Payload data provide neutral density, electron temperature, neutral wind speed, and small-scale field-aligned current (SS-FAC) values. Gravity Recovery and Climate Experiment neutral density data are also employed. During active times, cusp densities or density spikes appeared with their underlying flow channels (FCs) and enhanced SS-FACs implying upwelling, fueled by Joule heating, within/above FCs. Both the moderate nightside cusp enhancements under disturbed conditions and the minor dayside cusp enhancements under quiet conditions developed without any underlying FC and enhanced SS-FACs implying the role of particle precipitation in their development. Observations demonstrate the relations of FCs, density spikes, and upwelling-related divergent flows and their connections to the underlying (1) dayside magnetopause reconnection depositing magnetospheric energy into the high-latitude region and (2) Joule heating-driven disturbance dynamo effects. Results provide observational evidence that the moderate nightside cusp enhancements and the minor dayside cusp enhancements detected developed due to direct heating by weak particle precipitation. Chemical compositions related to the dayside density spike and low cusp densities are modeled by Naval Research Laboratory Mass Spectrometer Incoherent Scatter Radar Extended 2000. Modeled composition outputs for the dayside density spike's plasma environment depict some characteristic upwelling signatures. Oppositely, in the case of low dayside cusp densities, composition outputs show opposite characteristics due to the absence of upwelling.

The Plastic Flow Field in the Vicinity of the Pin-Tool During Friction Stir Welding

NASA Technical Reports Server (NTRS)

Bernstein, E. L.; Nunes, A. C., Jr.

2000-01-01

The plastic flow field in the vicinity of the pin-tool during Friction Stir Welding (FSW) needs to be understood if a theoretical understanding of the process is to be attained. The structure of welds does not exhibit the flow field itself, but consists in a residue of displacements left by the plastic flow field. The residue requires analysis to extract from it the instantaneous flow field around the pin-tool. A simplified merry-go-round model makes sense of some tracer experiments reported in the literature. A quantitative comparison is made of the displacements of copper wire markers with displacements computed from a hypothetical plastic flow field. The hypothetical plastic flow field consists in a circular rotation field about a translating pin tool with angular velocity varying with radius from the pin centerline. A sharply localized rotational field comprising slip on a surface around the tool agreed better with observations than a distributed slip field occupying a substantial volume around the tool. Both the tracer and the wire displacements support the "rotating plug" model, originally invoked or thermal reasons, of the FSW process.

Thermal Analysis of Filler Reinforced Polymeric Composites

NASA Astrophysics Data System (ADS)

Ghadge, Mahesh Devidas

Improving heat dissipating property of composite materials is becoming increasingly important in domains ranging from the automotive industry, electronic devices to aeronautical industry. Effective heat dissipation is required especially in aircraft and racing tires to guarantee high performance and good service life [1]. The present study is focused on improving the thermal conductivity of Emulsion-styrene butadiene rubber (ESBR) which is a cheap alternative to other rubber composites. The disadvantages of ESBR are low thermal conductivity and high heat generation. Adding fillers with high thermal conductivity to ESBR is proposed as a technique for improving the thermal conductivity of ESBR. The purpose of the research is to predict the thermal conductivity of ESBR when filled with fillers of much higher thermal conductivity and also to find out to what extent the filler properties affect the heat transfer capabilities of the composite matrix. The influence of different filler shapes i.e. spherical, cylindrical and platelets on the overall thermal capability of composite matrix is studied, the finite element modelings are conducted using Abaqus. Three-dimensional and two-dimensional models are created in Abaqus to simulate the microstructure of the composite matrix filled with fillers. Results indicate that the overall thermal conductivity increases with increasing filler loading i.e. for a filler volume fraction of 0.27, the conductivity increased by around 50%. Filler shapes, orientation angle, and aspect ratio of the fillers significantly influences the thermal conductivity. Conductivity increases with increasing aspect ratio (length/diameter) of the cylindrical fillers since longer conductive chains are able to form at the same volume percentage as compared to spherical fillers. The composite matrix reaches maximum thermal conductivity when the cylindrical fillers are oriented in the direction of heat flow. The heat conductivity predicted by FEM for ESBR is compared with that predicted by mean field theories. At low volume fractions the FEM and mean field theory results are matching. However, at high volume fractions, the results obtained by the two methods are not in agreement. This is due to the fact that mean field theory do not consider the particle interactions happening at higher volume fractions. The present analysis can be used to tailor the thermal properties of ESBR for required thermal conductivity for a wide range of applications such as racing tires, electronic gadgets or aeronautical components. In addition, the proposed FEM models can be used to design and optimize the properties of new composite materials providing more insight into the thermal conductivity of composite polymers and aid in understanding heat transfer mechanism of reinforced polymers.

Preparation research of Nano-SiC/Ni-P composite coating under a compound field

NASA Astrophysics Data System (ADS)

Zhou, H. Z.; Wang, W. H.; Gu, Y. Q.; Liu, R.; Zhao, M. L.

2016-07-01

In this paper, the preparation process of Ni-P-SiC composite coatings on 45 steel surfaces with the assistance of magnetic and ultrasound fields was researched. The influence of external field on the surface morphology and performance of the composite layer is also discussed. Experimental results showed that when prepared under magnetic and ultrasonic fields, composite layers are significantly more dense and uniform than coatings made without external fields. Nano-SiC particles, dispersed uniformly in the layer, significantly improve the hardness of the composite layer, and the composite layer under the external field had the highest hardness at 680 HV The external fields can also accelerate deposition and increase the thickness of the layer. Compared to layers processed without the assistance of external fields, the thickness of the layers increased by nearly ten µm.

Work plan for focused feasibility study of the toxic burning pits area at J-Field, Aberdeen Proving Ground, Maryland

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biang, C.; Benioff, P.; Martino, L.

1995-03-01

The Environmental Management Division (EMD) of Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation and feasibility study (RI/FS) of the J-Field area at APG pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act, as amended (CERCIA). J-Field is within the Edgewood Area of APG in Harford County, Maryland. Since World War II, activities in the Edgewood Area have included the development, manufacture, testing, and destruction of chemical agents and munitions. These materials were destroyed at J-Field by open burning and open detonation (OB/OD). Considerable archival information about J-Field exists as a result of efforts by APG staffmore » to characterize the hazards associated with the site. Contamination of J-Field was first detected during an environmental survey of the Edgewood Area conducted in 1977 and 1978 by the US Army Toxic and Hazardous Materials Agency (USATHAMA)(predecessor to the US Army Environmental Center). As part of a subsequent USATHAMA environmental survey, 11 wells were installed and sampled at J-Field. Contamination at J-Field was also detected during a munitions disposal survey conducted by Princeton Aqua Science in 1983. The Princeton Aqua Science investigation involved the installation and sampling of nine wells and the collection and analysis of surficial and deep composite soil samples. In 1986, a Resource Conservation and Recovery Act (RCRA) permit (MD3-21-0021355) requiring a basewide RCRA Facility Assessment (RFA) and a hydrogeologic assessment of J-Field was issued by the US Environmental Protection Agency (EPA). In 1987, the US Geological Survey (USGS) began a two-phased hydrogeologic assessment in which data were collected to model groundwater flow at J-Field. Soil gas investigations were conducted, several well clusters were installed, a groundwater flow model was developed, and groundwater and surface water monitoring programs were established that continue today-« less

Refining the Subseafloor Circulation Model of the Middle Valley Hydrothermal System Using Fluid Geochemistry

NASA Astrophysics Data System (ADS)

Inderbitzen, K. E.; Wheat, C. G.; Baker, P. A.; Fisher, A. T.

2014-12-01

Currently, fluid circulation patterns and the evolution of rock/fluid compositions as circulation occurs in subseafloor hydrothermal systems are poorly constrained. Sedimented spreading centers provide a unique opportunity to study subsurface flow because sediment acts as an insulating blanket that traps heat from the cooling magma body and limits: (a) potential flow paths for seawater to recharge the aquifer in permeable upper basaltic basement and (b) points of altered fluid egress. This also allows for a range of thermal and geochemical gradients to exist near the sediment-water interface. Models of fluid circulation patterns in this type of hydrologic setting have been generated (eg. Stein and Fisher, 2001); however fluid chemistry datasets have not previously been used to test the model's viability. We address this issue by integrating the existing circulation model with fluid compositional data collected from sediment pore waters and high temperature hydrothermal vents located in Middle Valley on the Juan de Fuca Ridge. Middle Valley hosts a variety of hydrologic regimes: including areas of fluid recharge (Site 855), active venting (Site 858/1036; Dead Dog vent field), recent venting (Site 856/1035; Bent Hill Massive Sulfide deposit) and a section of heavily sedimented basement located between recharge and discharge sites (Site 857). We will present new results based on thermal and geochemical data from the area of active venting (Sites 858 and 1036), that was collected during Ocean Drilling Program Legs 139 and 169 and a subsequent heat flow/gravity coring effort. These results illuminate fine scale controls on secondary recharge and fluid flow within the sediment section at Site 858/1036. The current status of high temperature vents in this area (based on observations made in July, 2014) will also be outlined.

A Perspective on Diagenetic Geometries and Patterns of Iron Oxide Cement and Coloration: Understanding Challenges and Complexities

NASA Astrophysics Data System (ADS)

Chan, M. A.; Wang, Y.

2015-12-01

Diagenetic records of fluid flow are underutilized proxies of water and environmental conditions in sedimentary rocks on Earth as well as Mars. The terrestrial iron-oxide records can be highly varied from faint wisps of coloration, to heavily cemented masses and layers. Other than vein cements, concretionary forms are some of the most prominent, yet enigmatic records. Concretions can have various mineral cement compositions with sizes that can span three orders of magnitude from mm, to cm, and m scales, in remarkably consistent, common spheroidal forms. Concretion geometries and banding may indicate directions and timings of fluid flow and precipitation, but deciphering the origins can be difficult with limited analytical tools. Definite complexities are the possibilities of: 1) overprinted events in an open system; 2) the role of organics in the nucleation and precipitation of authigenic minerals; and 3) multiple fluids, pathways, or processes that may produce similar-looking end products. In near-surface environments, likely any water since the Proterozoic has contained microbial life, and thus it seems highly probable that microbes play a significant role in the precipitation of diagenetic minerals due to the interactions of the biosphere and geosphere. However, recognition of ancient biosignatures that may have poor preservation potential remains a challenge. Iron oxides are particularly common, valuable indicators of near-surface iron cycling and are recognizable because the visual coloration. Our recent studies in Jurassic sandstones indicate preserved records of fingering at the interface of two immiscible fluids. The integration of geochemical self-organization models and field data provides new insights to understanding diagenetic fluid compositions, their relative densities, and flow direction flux and movement. These studies can have valuable implications and applications for understanding past fluid flow history, and reservoir characterization for CO2, hydrocarbon, and water.

Time Resolved Digital PIV Measurements of Flow Field Cyclic Variation in an Optical IC Engine

NASA Astrophysics Data System (ADS)

Jarvis, S.; Justham, T.; Clarke, A.; Garner, C. P.; Hargrave, G. K.; Halliwell, N. A.

2006-07-01

Time resolved digital particle image velocimetry (DPIV) experimental data is presented for the in-cylinder flow field development of a motored four stroke spark ignition (SI) optical internal combustion (IC) engine. A high speed DPIV system was employed to quantify the velocity field development during the intake and compression stroke at an engine speed of 1500 rpm. The results map the spatial and temporal development of the in-cylinder flow field structure allowing comparison between traditional ensemble average and cycle average flow field structures. Conclusions are drawn with respect to engine flow field cyclic variations.

Constraining the Rheologic Properties of Channelized Basaltic Flows on Earth and Mars

NASA Astrophysics Data System (ADS)

Ramsey, M. S.; Harris, A. J. L.; Crown, D. A.

2015-12-01

Basaltic volcanism is ubiquitous on the terrestrial planets and is the most common form of extrusive activity on Earth, with over half of the world's volcanoes consisting largely of basalt. Recently, new eruptions (or new phases of ongoing eruptions) have occurred at Tolbachik in Russia (2012-2013); Bardarbunga in Iceland (2014); Etna in Italy (2014); and Kilauea in Hawaii (2014-2015) emphasizing both the hazard potential and volumetric production of basaltic activity. Furthermore, new high-resolution data of flows on Arsia Mons volcano (Mars) show very similar features. Therefore, this style of effusive volcanism and especially its surface manifestation (lava flows) warrants continued study both from a fundamental science as well as a hazard mitigation point of view. Monitoring flow propagation direction and velocity are critical in these situations and a number of models have evolved over time focused on heat loss and down-flow topography to predict flow advance. In addition to topography, the dominant (internal) factors controlling flow propagation are the discharge rate combined with cooling and increasing viscosity. However, all these models rely on accurate temperature measurements derived from the cooling glassy surface using infrared (IR) non-contact instruments. New laboratory and field-based studies are attempting to characterize the cooling, formation, and dynamics of basaltic surfaces using IR data. Preliminary results are focused on resolving inconsistencies in the derived flow temperature, composition, texture and silicate structure, which can all impact the surface-leaving heat flux. Improved accuracy in these retrievals increases our ability to constrain and model flow surface and interior temperatures. The impact of this improved accuracy has now been assessed using flow model simulations of active terrestrial and well-preserved Martian flows, Results are improving our understanding of the initial eruption conditions of these channelized basaltic lava flows on both planets.

Probe measures gas and liquid mass flux in high mass flow ratio two-phase flows

NASA Technical Reports Server (NTRS)

Burick, R. J.

1972-01-01

Deceleration probe constructed of two concentric tubes with separator inlet operates successfully in flow fields where ratio of droplet flow rate to gas flow rate ranges from 1.0 to 20, and eliminates problems of local flow field disturbances and flooding. Probe is effective tool for characterization of liquid droplet/gas spray fields.

Different elution modes and field programming in gravitational field-flow fractionation. III. Field programming by flow-rate gradient generated by a programmable pump.

PubMed

Plocková, J; Chmelík, J

2001-05-25

Gravitational field-flow fractionation (GFFF) utilizes the Earth's gravitational field as an external force that causes the settlement of particles towards the channel accumulation wall. Hydrodynamic lift forces oppose this action by elevating particles away from the channel accumulation wall. These two counteracting forces enable modulation of the resulting force field acting on particles in GFFF. In this work, force-field programming based on modulating the magnitude of hydrodynamic lift forces was implemented via changes of flow-rate, which was accomplished by a programmable pump. Several flow-rate gradients (step gradients, linear gradients, parabolic, and combined gradients) were tested and evaluated as tools for optimization of the separation of a silica gel particle mixture. The influence of increasing amount of sample injected on the peak resolution under flow-rate gradient conditions was also investigated. This is the first time that flow-rate gradients have been implemented for programming of the resulting force field acting on particles in GFFF.

Flowable composites for bonding orthodontic retainers.

PubMed

Tabrizi, Sama; Salemis, Elio; Usumez, Serdar

2010-01-01

To test the null hypothesis that there are no statistically significant differences between flowables and an orthodontic adhesive tested in terms of shear bond strength (SBS) and pullout resistance. To test the SBS of Light Bond, FlowTain, Filtek Supreme, and Tetric Flow were applied to the enamel surfaces of 15 teeth. Using matrices for application, each composite material was cured for 40 seconds and subjected to SBS testing. To test pullout resistance, 15 samples were prepared for each composite in which a wire was embedded; then the composite was cured for 40 seconds. Later, the ends of the wire were drawn up and tensile stress was applied until the resin failed. Findings were analyzed using an ANOVA and a Tukey HSD test. The SBS values for Light Bond, FlowTain, Filtek Supreme, and Tetric Flow were 19.0 +/- 10.9, 14.7 +/- 9.3, 22.4 +/- 16.3, and 16.8 +/- 11.8 MPa, respectively, and mean pullout values were 42.2 +/- 13.0, 24.0 +/- 6.9, 26.3 +/- 9.4, and 33.8 +/- 18.0 N, respectively. No statistically significant differences were found among the groups in terms of SBS (P > .05). On the other hand, Light Bond yielded significantly higher pullout values compared with the flowables Filtek Supreme and Flow-Tain (P < .01). However, there were no significant differences among the pullout values of flowables, nor between Light Bond and Tetric Flow (P > .05). The hypothesis is rejected. Light Bond yielded significantly higher pullout values compared with the flowables Filtek Supreme and FlowTain. However, flowable composites provided satisfactory SBS and wire pullout values, comparable to a standard orthodontic resin, and therefore can be used as an alternative for direct bonding of lingual retainers.

The role of hydrodynamics in shaping the composition and architecture of epilithic biofilms in fluvial ecosystems.

PubMed

Risse-Buhl, Ute; Anlanger, Christine; Kalla, Katalin; Neu, Thomas R; Noss, Christian; Lorke, Andreas; Weitere, Markus

2017-12-15

Previous laboratory and on-site experiments have highlighted the importance of hydrodynamics in shaping biofilm composition and architecture. In how far responses to hydrodynamics can be found in natural flows under the complex interplay of environmental factors is still unknown. In this study we investigated the effect of near streambed turbulence in terms of turbulent kinetic energy (TKE) on the composition and architecture of biofilms matured in two mountainous streams differing in dissolved nutrient concentrations. Over both streams, TKE significantly explained 7% and 8% of the variability in biofilm composition and architecture, respectively. However, effects were more pronounced in the nutrient richer stream, where TKE significantly explained 12% and 3% of the variability in biofilm composition and architecture, respectively. While at lower nutrient concentrations seasonally varying factors such as stoichiometry of dissolved nutrients (N/P ratio) and light were more important and explained 41% and 6% of the variability in biofilm composition and architecture, respectively. Specific biofilm features such as elongated ripples and streamers, which were observed in response to the uniform and unidirectional flow in experimental settings, were not observed. Microbial biovolume and surface area covered by the biofilm canopy increased with TKE, while biofilm thickness and porosity where not affected or decreased. These findings indicate that under natural flows where near bed flow velocities and turbulence intensities fluctuate with time and space, biofilms became more compact. They spread uniformly on the mineral surface as a film of densely packed coccoid cells appearing like cobblestone pavement. The compact growth of biofilms seemed to be advantageous for resisting hydrodynamic shear forces in order to avoid displacement. Thus, near streambed turbulence can be considered as important factor shaping the composition and architecture of biofilms grown under natural flows. Copyright © 2017 Elsevier Ltd. All rights reserved.

Kevlar reinforced neoprene composites

NASA Technical Reports Server (NTRS)

Penn, B. G.; Daniels, J. G.; White, W. T.; Thompson, L. M.; Clemons, L. M.

1985-01-01

Kevlar/neoprene composites were prepared by two techniques. One method involved the fabrication of a composite from a rubber prepreg prepared by coating Kevlar with viscous neoprene solution and then allowing the solvent to evaporate (solution impregnation technique). The second method involved heating a stack of Kevlar/neoprene sheets at a temperature sufficient to cause polymer flow (melt flow technique). There was no significant difference in the breaking strength and percent elongation for samples obtained by the two methods; however the shear strength obtained for samples fabricated by the solution impregnation technique (275 psi) was significantly higher than that found for the melt flow fabricated samples (110 psi).

Surface roughness of flowable resin composites eroded by acidic and alcoholic drinks

PubMed Central

Poggio, Claudio; Dagna, Alberto; Chiesa, Marco; Colombo, Marco; Scribante, Andrea

2012-01-01

Aim: The aim of this study is to evaluate the surface roughness of four flowable resin composites following exposure to acidic and alcoholic drinks. Materials and Methods: SureFil SDR flow, TetricEvoFlow, Esthet-X Flow and Amaris Flow HT samples were immersed in artificial saliva, Coca Cola and Chivas Regal Whisky. Each specimen was examined using a Leica DCM 3D microscope: Arithmetical mean height of the surface profiles was measured (Sa). Results: Kruskal-Wallis test showed significant differences among various groups (P<0,001). Mann Whitney test was applied and control groups showed significantly lower Sa values than other groups (P=0,008). Coca Cola groups showed highest Sa values (P<0,021). No significant differences (P=0,14) in surface texture were found among the specimens of the different materials. No significant differences were found among TetricEvoFlow, Esthet-X Flow and Amaris Flow under control conditions nor after Coca Cola application. Under control condition and after Coca Cola application SureFil SDR flow showed significantly higher Sa values. Moreover, after whisky application Amaris Flow showed significantly lower Sa values then the other three groups that showed no significant differences among them. Conclusions: Acidic and alcoholic drinks eroded the surface roughness of all evaluated flowable resin composites. PMID:22557811

A Mechanism for Stratifying Lava Flows

NASA Astrophysics Data System (ADS)

Rice, A.

2005-12-01

Relict lava flows (e.g., komatiites) are often reported to be zoned in the vertical, each zone separated by a sharp contact. Such stratifications in igneous flows, both intrusive and extrusive, can be treated as analogues of suspended loads of sediments in rivers and streams, and hence amenable to quantitative treatment derived for the hydraulic environment as long as dynamic similitude is assured. Situations typically encountered in the hydraulic environment are streams carrying a bed load at the bottom of the stream, the bed load separated by a sharp horizon from a sediment load carried above it. This sediment load may be topped by others of decreasing density as one moves to the surface of the flow, with perhaps the uppermost layer clear of any suspended matter. Rules exist for estimating the thickness D of these loads: one of them is given by D ~ 4.4V3/rgcvs where V is the shear velocity or average velocity of the flow, r = (ρs - ρl)/ρl where ρs is the density of the suspended solid matter, ρl the density of the fluid, g the acceleration of gravity, c the concentration of the particulate content and vs the settling velocity. The settling velocity is secured through Stoke's Law and the velocity of the flow is given by V = R2/3S1/2/n where R is the hydraulic radius, S the gradient along which the fluid flows and n is the Manning Coefficient. In the igneous case, the bed load would be composed of primocrysts, i.e., of the first crystals to come out of solution as the flow cools along its run. This would leave the upper portions of the flow more evolved except perhaps for a quenched crust riding atop the flow. As the viscosity of the flow is dependent not only on temperature but on composition and crystal content, the mean velocity of each layer will be different from the layer above and below it. This requires shear at the interface of adjoining stratifications, which brings into play another mechanism: dispersive pressure (the Bagnold effect). Dispersive pressure will drive primocrysts into boundary layers such as that attending the bottom of the flow and at those separating stratifications. For instance, if the primocrysts were spinals, then a Cr high might be expected at the interfaces separating stratifications. Since the melt throughout is evolving as it moves down stream, compositional variations along strike (as well is in the vertical) might be expected. Application of the above notions falls within the confines of field observation.

Biofilm Formation on Reverse Osmosis Membranes Is Initiated and Dominated by Sphingomonas spp.▿ †

PubMed Central

Bereschenko, L. A.; Stams, A. J. M.; Euverink, G. J. W.; van Loosdrecht, M. C. M.

2010-01-01

The initial formation and spatiotemporal development of microbial biofilm layers on surfaces of new and clean reverse osmosis (RO) membranes and feed-side spacers were monitored in situ using flow cells placed in parallel with the RO system of a full-scale water treatment plant. The feed water of the RO system had been treated by the sequential application of coagulation, flocculation, sand filtration, ultrafiltration, and cartridge filtration processes. The design of the flow cells permitted the production of permeate under cross-flow conditions similar to those in spiral-wound RO membrane elements of the full-scale system. Membrane autopsies were done after 4, 8, 16, and 32 days of flow-cell operation. A combination of molecular (fluorescence in situ hybridization [FISH], denaturing gradient gel electrophoresis [DGGE], and cloning) and microscopic (field emission scanning electron, epifluorescence, and confocal laser scanning microscopy) techniques was applied to analyze the abundance, composition, architecture, and three-dimensional structure of biofilm communities. The results of the study point out the unique role of Sphingomonas spp. in the initial formation and subsequent maturation of biofilms on the RO membrane and feed-side spacer surfaces. PMID:20190090

Summary of the geology of the northern part of the Sierra Cuchillo, Socorroand Sierra Counties, southwestern New Mexico

USGS Publications Warehouse

Maldonado, Florian; Edited by Lucas, Spencer G.; McLemore, Virginia T.; Lueth, Virgil W.; Spielmann, Justin A.; Krainer, Karl

2012-01-01

The northern part of the Sierra Cuchillo is located within the northeastern part of the Mogollon-Datil volcanic field west of the Rio Grande rift in the Basin and Range Province, approximately 50 km northwest of Truth or Consequences in south-central New Mexico. The Sierra Cuchillo is a north-south, elongated horst block composed of Tertiary volcanic and intrusive rocks, sparse outcrops of Lower Permian and Upper Cretaceous rocks, and sediments of the Tertiary-Quaternary Santa Fe Group. The horst is composed mainly of a basal volcanic rock sequence of andesite-latite lava flows and mud-flow breccias with a 40Ar/39Ar isotopic age of about 38 Ma. The sequence is locally intruded by numerous dikes and plugs that range in composition from basaltic andesite through rhyolite and granite. The andesite-latite sequence is overlain by ash-flow tuffs and a complex of rhyolitic lava flows and domes. Some of these units are locally derived and some are outflow sheets derived from calderas in the San Mateo Mountains, northeast of the study area. These locally derived units and outflow sheets range in age from 28 to 24 Ma.

Application of Various NDT Methods for the Evaluation of Building Steel Structures for Reuse

PubMed Central

Fujita, Masanori; Masuda, Tomoya

2014-01-01

The reuse system proposed by the authors is an overall business system for realizing a cyclic reuse flow through the processes of design, fabrication, construction, maintenance, demolition and storage. The reuse system is one of the methods to reduce the environmental burden in the field of building steel structures. These buildings are assumed to be demolished within approximately 30 years or more for physical, architectural, economic and social reasons in Japan. In this paper, focusing on building steel structures used for plants, warehouses and offices without fire protection, the performance of steel structural members for reuse is evaluated by a non-destructive test. First, performance evaluation procedures for a non-destructive test, such as mechanical properties, chemical compositions, dimension and degradation, are shown. Tensile strengths are estimated using Vickers hardness measured by a portable ultrasonic hardness tester, and chemical compositions are measured by a portable optical emission spectrometer. The weldability of steel structural members is estimated by carbon equivalent and weld crack sensitivity composition using chemical compositions. Finally, the material grade of structural members of the building steel structure for reuse is estimated based on the proposed procedures. PMID:28788237

Application of Various NDT Methods for the Evaluation of Building Steel Structures for Reuse.

PubMed

Fujita, Masanori; Masuda, Tomoya

2014-10-22

The reuse system proposed by the authors is an overall business system for realizing a cyclic reuse flow through the processes of design, fabrication, construction, maintenance, demolition and storage. The reuse system is one of the methods to reduce the environmental burden in the field of building steel structures. These buildings are assumed to be demolished within approximately 30 years or more for physical, architectural, economic and social reasons in Japan. In this paper, focusing on building steel structures used for plants, warehouses and offices without fire protection, the performance of steel structural members for reuse is evaluated by a non-destructive test. First, performance evaluation procedures for a non-destructive test, such as mechanical properties, chemical compositions, dimension and degradation, are shown. Tensile strengths are estimated using Vickers hardness measured by a portable ultrasonic hardness tester, and chemical compositions are measured by a portable optical emission spectrometer. The weldability of steel structural members is estimated by carbon equivalent and weld crack sensitivity composition using chemical compositions. Finally, the material grade of structural members of the building steel structure for reuse is estimated based on the proposed procedures.

Measurement of Microscopic Growth Rates in Float-Zone Silicon Crystals

NASA Technical Reports Server (NTRS)

Dold, P.; Schweizer, M.; Benz, K. W.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Time dependent convective flows during crystal growth of doped semiconductors lead to fluctuations of the composition, so called dopant striations. In general, it is difficult to decide which is the main mechanism for the generation of these striations, it might be either the fluctuation of the concentration field in the melt and the extent of the solute boundary layer ahead of the solid-liquid interface or a variation of the growth velocity. Direct access to the concentration field is rather complicated to achieve, especially considering the high process temperature and the chemical activity of liquid silicon. The contribution of growth rate fluctuations to the formation of compositional fluctuations can be determined by measuring microscopic growth rates. The classical method of current pulses requires electrical feed-throughs and good electrical contacts, both are critical issues for the growth of high purity silicon crystals. Using a radiation based heating system, the heating power can be modulated very fast and effectively. We added to the normal heater power a sinusoidal off-set in the frequency range of 1 to 10 Hz, generating a narrow spaced weak rippling in the grown crystals which are superposed to the dopant striations caused by natural and by thermocapillary convection. The pulling speed was varied between 1 and 4mm/min. The microscope images of etched crystals slices have been analyzed by peak-search algorithms (measuring the spacing between each artificially induced marker) and by FFT. Performing growth experiments under a time-dependent flow regime, fluctuations of the microscopic growth velocity of Delta(v)/v(sub average) up to 50% have been measured. Damping the time-dependent convection by the use of an axial, static magnetic field of 500mT, the microscopic growth rate became constant within the resolution limit of this method. The results will be discussed using analytical methods for the calculation of microscopic growth velocity and by comparing them with measurements of temperature fluctuations in the melt during growth experiments itself.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, B.; Martino, L.

The White Phosphorus Burning Pits (WPP) Area of Concern (AOC) is a site of about 5.5 acres (2.2 ha) located in the J-Field Study Area, in the Edgewood Area of Aberdeen Proving Ground (APG), Maryland (Figure 1.1). Considerable information about the WPP exists as a result of efforts to characterize the hazards associated with J-Field. Contamination in the J-Field Study Area was first detected during an environmental survey of the APG Edgewood Area conducted in 1977 and 1978 (Nemeth et al. 1983) by the U.S. Army Toxic and Hazardous Materials Agency (USATHAMA; predecessor to the U.S. Army Environmental Center). Asmore » part of a subsequent USATHAMA environmental survey, 11 wells were installed and sampled at J-Field (three of them at the WPP) (Nemeth 1989). Contamination was also detected in 1983 during a munitions disposal survey conducted by Princeton Aqua Science (1984). The Princeton Aqua Science investigation involved installing and sampling nine wells (four at the WPP) and collecting and analyzing surficial and deep composite soil samples (including samples from the WPP area). In 1986, the U.S. Environmental Protection Agency (EPA) issued a Resource Conservation and Recovery Act (RCRA) Permit (MD3-21-002-1355) requiring a post-wide RCRA Facility Assessment (RFA) and a hydrogeologic assessment of J-Field. In 1987, the U.S. Geological Survey (USGS) began a two-phase hydrogeologic assessment in which data were collected to model groundwater flow at J-Field. Soil-gas investigations were conducted, several well clusters were installed (four at the WPP), a groundwater flow model was developed, and groundwater and surface water monitoring programs were established that continue today. The results of the USGS study were published by Hughes (1993).« less

Pyroclastic deposits of the Mount Edgecumbe volcanic field, southeast Alaska: eruptions of a stratified magma chamber

USGS Publications Warehouse

Riehle, J.R.; Champion, D.E.; Brew, D.A.; Lanphere, M.A.

1992-01-01

The Mount Edgecumbe volcanic field in southeastern Alaska consists of 5-6 km3 (DRE) of postglacial pyroclasts that overlie Pleistocene lavas. All eleven pyroclast vents align with the long axis of the field, implying that the pyroclast magma conduits followed a crustal fissure. Most of these vents had previously erupted lavas that are compositionally similar to the pyroclasts, so a persistent magma system (chamber) had likely evolved by the onset of the pyroclastic eruptions. The pyroclastic sequence was deposited in about a millennium and is remarkable for a wide range of upward-increasing silica contents (51-72% SiO2), which is consistent with rise of coexisting magmas at different rates governed by their viscosity. Basaltic and andesitic lava flows have erupted throughout the lifetime of the field. Rhyolite erupted late; we infer that it formed early but was hindered from rising by its high viscosity. Most of the magmas-and all siliceous ones-erupted from vents on the central fissure. Basalt has not erupted from the center of the field during at least the latter part of its lifetime. Thus the field may illustrate basalt underplating: heat and mass flux are concentrated at the center of a stratified magma chamber in which a cap of siliceous melt blocks the rise of basalt. Major-element, strontium isotope, and mineral compositions of unaltered pyroclasts are broadly similar to those of older lavas of similar SiO2 content. Slightly fewer phenocrysts, inherited grains, and trace amphibole in pyroclastic magmas may be due simply to faster rise and less undercooling and degassing before eruption relative to the lavas. Dacite occurs only in the youngest deposits; the magma formed by mixing of andesitic and rhyolitic magmas erupted shortly before by the dacitic vents. ?? 1992.

Dielectric response in Bloch’s hydrodynamic model of an electron-ion plasma

NASA Astrophysics Data System (ADS)

Ishikawa, K.; Felderhof, B. U.

The linear response of an electron-ion plasma to an applied oscillating electric field is studied within the framework of Bloch’s classical hydrodynamic model. The ions are assumed to be fixed in space and distributed according to a known probability distribution. The linearized equations of motion for electron density and flow velocity are studied with the aid of a multiple scattering analysis and cluster expansion. This allows systematic reduction of the many-ion problem to a composition of few-ion problems, and shows how the longitudinal dielectric response function can in principle be calculated.

Graphics and Flow Visualization of Computer Generated Flow Fields

NASA Technical Reports Server (NTRS)

Kathong, M.; Tiwari, S. N.

1987-01-01

Flow field variables are visualized using color representations described on surfaces that are interpolated from computational grids and transformed to digital images. Techniques for displaying two and three dimensional flow field solutions are addressed. The transformations and the use of an interactive graphics program for CFD flow field solutions, called PLOT3D, which runs on the color graphics IRIS workstation are described. An overview of the IRIS workstation is also described.

Effects of thyroxine and dexamethasone on rat submandibular glands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sagulin, G.B.; Roomans, G.M.

1989-08-01

Glucocorticoids and thyroxine are known to have a marked effect on the flow rate and protein composition of rat parotid saliva in hormonally intact animals. In the present study, the effects of a one-week treatment of male rats with dexamethasone and thyroxine were studied by electron microscopy and x-ray micro-analysis, and by measurement of the flow rate and determination of the chemical composition of pilocarpine-induced submandibular saliva. Thyroxine had the most extensive effects on the submandibular gland. The acinar cells were enlarged and filled with mucus; the cellular calcium concentration was significantly increased. The flow rate of the submandibular salivamore » was significantly reduced compared with that in saline-injected control animals. Thyroxine caused an increase in the concentrations of protein, total calcium, and potassium in the saliva. Dexamethasone had no significant effects on gland ultrastructure or on the elemental composition of the acinar cells; flow rate was not affected, but the concentrations of protein, calcium, and potassium were significantly increased. The effects of dexamethasone and thyroxine on the flow rate and protein composition of pilocarpine-induced rat submandibular saliva differ from those reported earlier for rat parotid saliva after simultaneous stimulation with pilocarpine and isoproterenol.« less

Visualizing vector field topology in fluid flows

NASA Technical Reports Server (NTRS)

Helman, James L.; Hesselink, Lambertus

1991-01-01

Methods of automating the analysis and display of vector field topology in general and flow topology in particular are discussed. Two-dimensional vector field topology is reviewed as the basis for the examination of topology in three-dimensional separated flows. The use of tangent surfaces and clipping in visualizing vector field topology in fluid flows is addressed.

A Tale of Two Flows

NASA Image and Video Library

2016-01-27

This image was taken in one of the regions on Mars well-known for its viscous flow features (VFF), which are massive flowing deposits believed to be composed of a mixture of ice and dust similar to glaciers on Earth. In this particular region, an impact event occurred creating ejecta deposits that also appear to flow (probably because of their similarly ice-rich composition), and interact with the flows from the VFF. Looking closer, we can see that the VFF deposits (on the right) appear to be rougher in appearance than those of the impact ejecta. We will need to study this image in more detail to understand how these flows have interacted with each other and what they can tell us about their composition and their flowing behavior properties. http://photojournal.jpl.nasa.gov/catalog/PIA20370

The Physical and Petrologic Evolution of a Multi-vent Volcanic Field Associated With Yellowstone-Newberry Volcanism

NASA Astrophysics Data System (ADS)

Brueseke, M. E.; Hart, W. K.

2004-12-01

The Santa Rosa-Calico volcanic field (SC) of northern Nevada is perhaps the most chemically and physically diverse of all volcanic fields associated with mid-Miocene northwestern USA volcanism. SC volcanism occurred from 16.5 to 14 Ma and was characterized by the eruption of a complete compositional spectrum from basalt through high-Si rhyolite. Locally derived tholeiitic lava flows and shallow intrusive bodies are chemically and isotopically identical to the Steens Basalt (87/86Sri=<0.7040), the Oregon Plateau-wide mid-Miocene flood basalt. Andesite-dacite lava flows are exposed as at least four geographically and chemically distinct packages representing products of multiple, discrete magmatic systems. The most voluminous of these is calc-alkaline and characterized by abundant granitoid and mafic xenoliths/xenocrysts and radiogenic Sr isotopic ratios. Subalkaline silicic lava flows, domes, and shallow intrusive bodies define three diffuse north-south trending zones. Textural, chemical, and isotopic variability within the silicic units is linked to their spatial and temporal distribution, again necessitating the existence of multiple magmatic systems. The youngest locally derived silicic units are ash flows exposed in the central portion of the SC that erupted in actively forming sedimentary basins at ˜15.4 Ma. Underlying the 400-1500m thick package of SC volcanic rocks are temporally ( ˜103 and ˜85 Ma), chemically, and isotopically (87/86Sr at 16 Ma= 0.7045 to 0.7058 and 0.7061 to >0.7070) heterogeneous granitoid plutons and a package of ˜20-23 Ma calc-alkaline, arc-related intermediate lava flows. The observed disequilibrium textures, xenoliths, and chemical/isotopic diversity suggests that upwelling Steens magma interacted with local crust, siliceous crustal melts, and the mafic plutonic roots of early Miocene arc volcanism in multiple magmatic systems characterized by heterogeneous open system processes. The formation of these systems is tectonically controlled as evidenced by magma eruption/ascent along active zones of lithospheric extension. Thus, the observed physical and chemical diversity in this volcanic field is attributed to a combination of factors; tectonic setting, availability of upwelling mafic magma(s), nature of pre-Miocene crustal addition and lithospheric modification, and the resulting array of magma sources and petrogenetic processes.

Sources and export of particle-borne organic matter during a monsoon flood in a catchment of northern Laos

NASA Astrophysics Data System (ADS)

Gourdin, E.; Huon, S.; Evrard, O.; Ribolzi, O.; Bariac, T.; Sengtaheuanghoung, O.; Ayrault, S.

2014-06-01

Tropical rivers of Southeast Asia are characterized by high specific carbon yields and supplies to the ocean. The origin and dynamics of particulate organic matter were studied in the Houay Xon River catchment located in northern Laos during the first erosive flood of the rainy season in May 2012. The partly cultivated catchment is equipped with three successive gauging stations draining areas ranging between 0.2 and 11.6 km2 on the main stem of the permanent stream, and two additional stations draining 0.6 ha hillslopes. In addition, the sequential monitoring of rainwater, overland flow and suspended organic matter compositions was realized at 1 m2 plot scale during a single storm. The composition of particulate organic matter (total organic carbon, total nitrogen, δ13C and δ15N) was determined for suspended sediment, soil surface and subsurface samples collected in the catchment (n = 57, 65 and 11 respectively). Hydrograph separation of event water was conducted using water electric conductivity and δ18O data measured for rainfall, overland flow and river water base flow (n = 9, 30 and 57, respectively). The composition of particulate organic matter indicates that upstream suspended sediments were mainly derived from cultivated soils labelled by their C3 vegetation cover (upland rice, fallow vegetation and teak plantations) but that collapsed riverbanks, characterized by C4 vegetation occurrence (Napier grass), significantly contributed to sediment yields during water level rise and at the downstream station. The highest runoff coefficient (11.7%), sediment specific yield (433 kg ha-1), total organic carbon specific yield (8.3 kg C ha-1) and overland flow contribution (78-100%) were found for the reforested areas covered by teak plantations. Total organic carbon specific yields were up to 2.6-fold higher (at downstream station) than the annual ones calculated 10 years earlier, before the expansion of teak plantations in the catchment. They may be attributed both to the sampling period at the onset of the rainy season (following field clearing by slash and burn) and to the impact of land use change during the past decade.

Aquatic chemistry of flood events

NASA Astrophysics Data System (ADS)

Klavins, Maris; Rodinov, Valery

2015-04-01

During flood events a major discharge of water and dissolved substances happens. However flood waters very much differs from water composition during low-water events. Aquatic chemistry of flood waters also is of importance at the calculation of loadings as well as they might have major impact on water quality in receiving water bodies (lakes, coastal waters and seas). Further flood regime of rivers is subjected to changes due to climate change and growing impact of human activities. The aim of this study is to analyse water chemical composition changes during flood events in respect to low water periods, character of high-water events and characteristics of the corresponding basin. Within this study, the concentrations of major dissolved substances in the major rivers of Latvia have been studied using monitoring data as well as field studies during high water/ low water events. As territories of studies flows of substances in river basins/subbasins with different land-use character and different anthropogenic impacts has been studied to calculate export values depending on the land-use character. Impact of relations between dissolved substances and relations in respect to budgets has been calculated. The dynamics of DOC, nutrient and major dissolved substance flows depending on landuse pattern and soil properties in Latvia has been described, including emissions by industrial and agricultural production. In these changes evidently climate change signals can be identified. The water chemistry of a large number of rivers during flood events has been determined and the possible impact of water chemical composition on DOC and nutrient flows has been evaluated. Long-term changes (1977-2013) of concentrations of dissolved substances do not follow linear trends but rather show oscillating patterns, indicating impact of natural factors, e.g. changing hydrological and climatic conditions. There is a positive correlation between content of inert dissolved substances and water discharge. This study did not reveal a clear correlation between the concentrations of dissolved substances and land-use types within the river basin. Conclusions in respect to calculation needed for loading calculations has been done. Acknowledgement: support from a Latvia Science Council grant "Stability of climate system and its impacts on water quality limiting biogeochemical flows in Latvia"

Influence of precipitating light elements on stable stratification below the core/mantle boundary

NASA Astrophysics Data System (ADS)

O'Rourke, J. G.; Stevenson, D. J.

2017-12-01

Stable stratification below the core/mantle boundary is often invoked to explain anomalously low seismic velocities in this region. Diffusion of light elements like oxygen or, more slowly, silicon could create a stabilizing chemical gradient in the outermost core. Heat flow less than that conducted along the adiabatic gradient may also produce thermal stratification. However, reconciling either origin with the apparent longevity (>3.45 billion years) of Earth's magnetic field remains difficult. Sub-isentropic heat flow would not drive a dynamo by thermal convection before the nucleation of the inner core, which likely occurred less than one billion years ago and did not instantly change the heat flow. Moreover, an oxygen-enriched layer below the core/mantle boundary—the source of thermal buoyancy—could establish double-diffusive convection where motion in the bulk fluid is suppressed below a slowly advancing interface. Here we present new models that explain both stable stratification and a long-lived dynamo by considering ongoing precipitation of magnesium oxide and/or silicon dioxide from the core. Lithophile elements may partition into iron alloys under extreme pressure and temperature during Earth's formation, especially after giant impacts. Modest core/mantle heat flow then drives compositional convection—regardless of thermal conductivity—since their solubility is strongly temperature-dependent. Our models begin with bulk abundances for the mantle and core determined by the redox conditions during accretion. We then track equilibration between the core and a primordial basal magma ocean followed by downward diffusion of light elements. Precipitation begins at a depth that is most sensitive to temperature and oxygen abundance and then creates feedbacks with the radial thermal and chemical profiles. Successful models feature a stable layer with low seismic velocity (which mandates multi-component evolution since a single light element typically increases seismic velocity) growing to its present-day size while allowing enough precipitation to drive compositional convection below. Crucially, this modeling offers unique constrains on Earth's accretion and the light element composition of the core compared to degenerate estimates derived from bulk density and seismic measurements.

Groundwater, springs, and stream flow generation in an alpine meadow of a tropical glacierized catchment

NASA Astrophysics Data System (ADS)

Gordon, R.; Lautz, L. K.; McKenzie, J. M.; Mark, B. G.; Chavez, D.

2013-12-01

Melting tropical glaciers supply approximately half of dry season stream discharge in glacierized valleys of the Cordillera Blanca, Peru. The remainder of streamflow originates as groundwater stored in alpine meadows, moraines and talus slopes. A better understanding of the dynamics of alpine groundwater, including sources and contributions to streamflow, is important for making accurate estimates of glacial inputs to the hydrologic budget, and for our ability to make predictions about future water resources as glaciers retreat. Our field study, conducted during the dry season in the Llanganuco valley, focused on a 0.5-km2 alpine meadow complex at 4400 m elevation, which includes talus slopes, terminal moraines, and a debris fan. Two glacial lakes and springs throughout the complex feed a network of stream channels that flow across the meadow (~2 km total length). We combined tracer measurements of stream and spring discharge and groundwater-surface water exchange with synoptic sampling of water isotopic and geochemical composition, in order to characterize and quantify contributions to streamflow from different geomorphic features. Surface water inputs to the stream channels totaled 58 l/s, while the stream gained an additional 57 l/s from groundwater inputs. Water chemistry is primarily controlled by flowpath type (surface/subsurface) and length, as well as bedrock lithology, while stable water isotopic composition appears to be controlled by water source (glacial lake, meadow or deep groundwater). Stream water chemistry is most similar to meadow groundwater springs, but isotopic composition suggests that the majority of stream water, which issues from springs at the meadow/fan interface, is from the same glacial source as the up-gradient lake. Groundwater sampled from piezometers in confined meadow aquifers is unique in both chemistry and isotopic composition, but does not contribute a large percentage of stream water exiting this small meadow, as quantified by discharge measurements and isotopic mixing. However, we expect that as streams flow down through extensive meadows and wetlands in many Cordillera Blanca valleys, meadow groundwater is a more significant contributor to streamflow. Results from this small, high meadow in Llanganuco will be compared to a larger and lower-elevation meadow system in the Quilcayhuanca valley.

Lithic breccia and ignimbrite erupted during the collapse of Crater Lake Caldera, Oregon

USGS Publications Warehouse

Druitt, T.H.; Bacon, C.R.

1986-01-01

The climactic eruption of Mount Mazama (6845 y.B.P.) vented a total of ???50 km3 of compositionally zoned rhyodacitic to basaltic magma from: (a) a single vent as a Plinian pumice fall deposit and the overlying Wineglass Welded Tuff, and (b) ring vents as ignimbrite and coignimbrite lithic breccia accompanying the collapse of Crater Lake caldera. New field and grain-size data for the ring-vent products are presented in this report. The coarse-grained, poorly bedded, clast-supported lithic breccia extends as far as 18 km from the caldera center. Like the associated ignimbrite, the breccia is compositionally zoned both radially and vertically, and silicic, mixed, and mafic types can be recognized, based on the proportion of rhyodacitic pumice. Matrix fractions in silicic breccias are depleted of fines and are lithic- and crystal-enriched relative to silicic ignimbrite due to vigorous gas sorting during emplacement. Ignimbrite occurs as a proximal veneer deposit overlying the breccia, a medial (??? 8 to ??? 25 km from the caldera center), compositionally zoned valley fill as much as > 110 m thick, and an unzoned distal ({slanted equal to or greater-than} 20 km) facies which extends as far as 55 km from the caldera. Breccia within ??? 9 km of the caldera center is interpreted as a coignimbrite lag breccia formed within the deflation zone of the collapsing ring-vent eruption columns. Expanded pyroclastic flows of the deflation zone were probably vertically graded in both size and concentration of blocks, as recently postulated for some turbidity currents. An inflection in the rate of falloff of lithic-clast size within the lithic breccia at ??? 9 km may mark the outer edge of the deflation zone or may be an artifact of incomplete exposure. The onset of ring-vent activity at Mt. Mazama was accompanied by a marked increase in eruptive discharge. Pyroclastic flows were emplaced as a semicontinuous stream, as few ignimbrite flow-unit boundaries are evident. As eruption from the ring vents progressed, flow-runout distance and the extent of breccia deposition decreased due to (a) greater internal flow friction, and (b) decreasing eruption column heights. Effect (b) probably resulted from a progressive decrease in magmatic gas content and discharge rate. Waning discharge may have been promoted by the tapping of more viscous, crystal-rich magma, collapse of conduit walls, and declining caldera collapse rate. ?? 1986.

Higher-order compositional modeling of three-phase flow in 3D fractured porous media based on cross-flow equilibrium

NASA Astrophysics Data System (ADS)

Moortgat, Joachim; Firoozabadi, Abbas

2013-10-01

Numerical simulation of multiphase compositional flow in fractured porous media, when all the species can transfer between the phases, is a real challenge. Despite the broad applications in hydrocarbon reservoir engineering and hydrology, a compositional numerical simulator for three-phase flow in fractured media has not appeared in the literature, to the best of our knowledge. In this work, we present a three-phase fully compositional simulator for fractured media, based on higher-order finite element methods. To achieve computational efficiency, we invoke the cross-flow equilibrium (CFE) concept between discrete fractures and a small neighborhood in the matrix blocks. We adopt the mixed hybrid finite element (MHFE) method to approximate convective Darcy fluxes and the pressure equation. This approach is the most natural choice for flow in fractured media. The mass balance equations are discretized by the discontinuous Galerkin (DG) method, which is perhaps the most efficient approach to capture physical discontinuities in phase properties at the matrix-fracture interfaces and at phase boundaries. In this work, we account for gravity and Fickian diffusion. The modeling of capillary effects is discussed in a separate paper. We present the mathematical framework, using the implicit-pressure-explicit-composition (IMPEC) scheme, which facilitates rigorous thermodynamic stability analyses and the computation of phase behavior effects to account for transfer of species between the phases. A deceptively simple CFL condition is implemented to improve numerical stability and accuracy. We provide six numerical examples at both small and larger scales and in two and three dimensions, to demonstrate powerful features of the formulation.

Low-angle dunes in the Changjiang (Yangtze) Estuary: Flow and sediment dynamics under tidal influence

NASA Astrophysics Data System (ADS)

Hu, Hao; Wei, Taoyuan; Yang, Zhongyong; Hackney, Christopher R.; Parsons, Daniel R.

2018-05-01

It has long been highlighted that important feedbacks exist between river bed morphology, sediment transport and the turbulent flow field and that these feedbacks change in response to forcing mechanisms. However, our current understanding of bedform dynamics is largely based on studies of steady flow environments and cohesionless bed conditions. Few investigations have been made under rapidly changing flows. Here, we examine flow and sediment dynamics over low-angle dunes in unsteady flows in the Changjiang (Yangtze) Estuary, China. Topography, flow and sediment data were collected over a reach ca 1.8 km long through a semi-diurnal tidal cycle in a moderate tide of flood season. The results show that: (1) roughness length derived from the upper flow changes little with the flow reversing and displays the same value on both the ebb and flood tide. Moreover, the variability of individual bedform features plays an important role in roughness length variation. (2) Shear stress over the crest of low-angle dunes roughly represents the total spatially averaged stress over dunes in this study area, which has significant implications for advancing numerical models. (3) Changes in morphology, flow and sediment dynamics over dunes through time reveal how low-angle dunes evolve within a tidal cycle. (4) The clockwise hysteresis loops between flow dynamics and bedform features (height and aspect ratio) are also observed. The combination of suspended sediment transport and bedload transport on dune transformation and migration attributes to the clockwise hysteresis. The specific sediment composition of the riverbed, in some extent, affects the mechanism of sediment transport related to the exchange between suspended sediment and riverbed, but further investigation is needed to figure out the mechanism behind this for extended series of tides, such as spring/neap tide and tides in flooding and dry season.

Salinization Sources Along the Lower Jordan River Under Draught Conditions

NASA Astrophysics Data System (ADS)

Holtzman, R.; Shavit, U.; Segal, M.; Vengosh, A.; Farber, E.; Gavrieli, I.

2003-12-01

The Lower Jordan River, once a flowing freshwater river, is suffering from an ongoing reduction of discharge and water quality. The river flows between the Sea of Galilee and the Dead Sea, an aerial distance of about 105 Km. The severe reduction is caused by an excessive exploitation of its sources and diversion of sewage and agricultural drainage into the river. The extreme low flows and low water quality threaten the natural existence of the river and its potential use for agriculture. In spite of its importance, little research has been done in the river. The objectives of the study were to measure the discharge and water composition along the river and to evaluate the main sources that control its flow and chemical characteristics. The hypothesis of the study was that interaction with subsurface flows significantly affects the river flow and chemical composition. The research is based on a detailed field study, which included flow rate measurements in the river and its tributaries, water sampling and analysis and mass balance calculations of water and solutes. A portable Acoustic Doppler Velocimeter (ADV) was used to measure velocities and bathymetry at different locations across the river sections. Due to accessibility constraints, a floating traverse construction, which enables the ADV's deployment from one bank of the river, was developed. It was found that flow rate ranges between 500-1,100 L/s in northern (upstream) sections and 300-1,650 L/s in the south. This low discharge represents a significant reduction from historical values and is lower than recent published estimations. This research represents base flows only, as the measurements were done during a period of two consecutive draught years. Calculated mass balance of water flows in the northern sections shows that the subsurface source contributes to the river around 200-670 L/s (30-80% of the river flow). Calculations of solute balance show that the subsurface flows add 20-50% of the mass of solutes (e.g. Sulfate) that flows in the river. The assumption of a hydraulic gradient that points at inflows from subsurface flows is encouraged by high water levels measured in nearby piezometers. Possible natural subsurface sources include shallow groundwater or rising of water from deep formations. The existence of adjacent thermal wells strengthens the reasonability of such water rise. Possible anthropogenic sources include return flows and effluents. The results are consistent and agree with the geochemical and isotopic analyses. It is concluded that the impact of the subsurface component on the Jordan River is significant and must be taken into consideration, for future water management schemes and implementation of the Peace Treaty between Israel and Jordan.

Geochronology and geochemistry of lavas from the 1996 North Gorda Ridge eruption

NASA Astrophysics Data System (ADS)

Rubin, K. H.; Smith, M. C.; Perfit, M. R.; Christie, D. M.; Sacks, L. F.

1998-12-01

Radiometric dating of three North Gorda Ridge lavas by the 210Po- 210Pb method confirms that an eruption occurred during a period of increased seismic activity along the ridge during late February/early March 1996. These lavas were collected following detection of enhanced T-phase seismicity and subsequent ocean bottom photographs documented the existence of a large pillow mound of fresh-appearing lavas. 210Po- 210Pb dating of these lavas indicates that an eruption coinciding with this seismicity did occur (within analytical error) and that followup efforts to sample the recent lava flows were successful. Compositions of the three confirmed young lavas and eleven other samples of this contiguous "new flow" sequence are distinct from older lavas from this area but are variable at a level outside analytical uncertainty. These intraflow variations can not easily be related to a single, common parent magma. Compositional variability within the new flow is compared to that of other recently documented individual flow sequences, and this comparison reveals a strong positive correlation of compositional variance with flow volumes spanning a range of >2 orders of magnitude. The geochemical heterogeneity in the North Gorda new flow probably reflects incomplete mixing of magmas generated from a heterogeneous mantle source or from slightly different melting conditions of a single source. The compositional variability, range in sample ages (up to 6 weeks) and range in active seismicity (4 weeks) imply that this relatively large flow was erupted over an interval of several weeks.

GASFLOW: A Computational Fluid Dynamics Code for Gases, Aerosols, and Combustion, Volume 3: Assessment Manual

DOE Office of Scientific and Technical Information (OSTI.GOV)

Müller, C.; Hughes, E. D.; Niederauer, G. F.

1998-10-01

Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best- estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the wallsmore » and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume III contains some of the assessments performed by LANL and FzK« less

Electroosmotic Flow Driven by DC and AC Electric Fields in Curved Microchannels

NASA Astrophysics Data System (ADS)

Chen, Jia-Kun; Luo, Win-Jet; Yang, Ruey-Jen

2006-10-01

The purpose of this study is to investigate electroosmotic flows driven by externally applied DC and AC electric fields in curved microchannels. For the DC electric driving field, the velocity distribution and secondary flow patterns are investigated in microchannels with various curvature ratios. We use the Dean number to describe the curvature effect of the flow field in DC electric field. The result implies that the effect of curvatures and the strength of the secondary flows become get stronger when the curvature ratio of C/A (where C is the radius of curvature of the microchannel and A is the half-height of rectangular curved tube.) is smaller. For the AC electric field, the velocity distribution and secondary flow patterns are investigated for driving frequencies in the range of 2.0 kHz (\\mathit{Wo}=0.71) to 11 kHz (\\mathit{Wo}=1.66). The numerical results reveal that the velocity at the center of the microchannel becomes lower at higher frequencies of the AC electric field and the strength of the secondary flow decreases. When the applied frequency exceeds 3.0 kHz (\\mathit{Wo}=0.87), vortices are no longer observed at the corners of the microchannel. Therefore, it can be concluded that the secondary flow induced at higher AC electric field frequencies has virtually no effect on the axial flow field in the microchannel.

Numerical and experimental study on vorticity measurement in liquid metal using local Lorentz force velocimetry

NASA Astrophysics Data System (ADS)

Hernández, Daniel; Marangoni, Rafael; Schleichert, Jan; Karcher, Christian; Fröhlich, Thomas; Wondrak, Thomas

2018-03-01

Local Lorentz force velocimetry (local LFV) is a contactless velocity measurement technique for liquid metals. Due to the relative movement between an electrically conductive fluid and a static applied magnetic field, eddy currents and a flow-braking Lorentz force are generated inside the metal melt. This force is proportional to the flow rate or to the local velocity, depending on the volume subset of the flow spanned by the magnetic field. By using small-size magnets, a localized magnetic field distribution is achieved allowing a local velocity assessment in the region adjacent to the wall. In the present study, we describe a numerical model of our experiments at a continuous caster model where the working fluid is GaInSn in eutectic composition. Our main goal is to demonstrate that this electromagnetic technique can be applied to measure vorticity distributions, i.e. to resolve velocity gradients as well. Our results show that by using a cross-shaped magnet system, the magnitude of the torque perpendicular to the surface of the mold significantly increases improving its measurement in a liquid metal flow. According to our numerical model, this torque correlates with the vorticity of the velocity in this direction. Before validating our numerical predictions, an electromagnetic dry calibration of the measurement system composed of a multicomponent force and torque sensor and a cross-shaped magnet was done using a rotating disk made of aluminum. The sensor is able to measure simultaneously all three components of force and torque, respectively. This calibration step cannot be avoided and it is used for an accurate definition of the center of the magnet with respect to the sensor’s coordinate system for torque measurements. Finally, we present the results of the experiments at the mini-LIMMCAST facility showing a good agreement with the numerical model.

Thermal and petrologic constraints on the lower crustal melt accumulation in the Salton Sea Geothermal Field

NASA Astrophysics Data System (ADS)

Karakas, O.; Dufek, J.; Mangan, M.; Wright, H. M. N.

2014-12-01

Heat transfer in active volcanic areas is governed by complex coupling between tectonic and magmatic processes. These two processes provide unique imprints on the petrologic and thermal evolution of magma by controlling the geometry, depth, longevity, composition, and fraction of melt in the crust. The active volcanism, tectonic extension, and significantly high surface heat flow in Salton Sea Geothermal Field, CA, provides information about the dynamic heat transfer processes in its crust. The volcanism in the area is associated with tectonic extension over the last 500 ka, followed by subsidence and sedimentation at the surface level and dike emplacement in the lower crust. Although significant progress has been made describing the tectonic evolution and petrology of the erupted products of the Salton Buttes, their coupled control on the crustal heat transfer and feedback on the melt evolution remain unclear. To address these concepts, we develop a two-dimensional finite volume model and investigate the compositional and thermal evolution of the melt and crust in the Salton Sea Geothermal Field through a one-way coupled thermal model that accounts for tectonic extension, lower crustal magma emplacement, sedimentation, and subsidence. Through our simulations, we give quantitative estimates to the thermal and compositional evolution and longevity of the lower crustal melt source in the crustal section. We further compare the model results with petrologic constraints. Our thermal balance equations show that crustal melting is limited and the melt is dominated by mantle-derived material. Similarly, petrologic work on δ18O isotope ratios suggests fractional crystallization of basalt with minor crustal assimilation. In addition, we suggest scenarios for the melt fraction, composition, enthalpy release, geometry and depth of magma reservoirs, their temporal evolution, and the timescales of magmatic storage and evolution processes. These parameters provide the source conditions for the dynamics of surface volcanism and the presence of a geothermal system, which modify the thermal and mechanical structure of the crust.

Present mantle flow in North China Craton constrained by seismic anisotropy and numerical modelling

NASA Astrophysics Data System (ADS)

Qu, W.; Guo, Z.; Zhang, H.; Chen, Y. J.

2017-12-01

North China Carton (NCC) has undergone complicated geodynamic processes during the Cenozoic, including the westward subduction of the Pacific plate to its east and the collision of the India-Eurasia plates to its southwest. Shear wave splitting measurements in NCC reveal distinct seismic anisotropy patterns at different tectonic blocks, that is, the predominantly NW-SE trending alignment of fast directions in the western NCC and eastern NCC, weak anisotropy within the Ordos block, and N-S fast polarization beneath the Trans-North China Orogen (TNCO). To better understand the origin of seismic anisotropy from SKS splitting in NCC, we obtain a high-resolution dynamic model that absorbs multi-geophysical observations and state-of-the-art numerical methods. We calculate the mantle flow using a most updated version of software ASPECT (Kronbichler et al., 2012) with high-resolution temperature and density structures from a recent 3-D thermal-chemical model by Guo et al. (2016). The thermal-chemical model is obtained by multi-observable probabilistic inversion using high-quality surface wave measurements, potential fields, topography, and surface heat flow (Guo et al., 2016). The viscosity is then estimated by combining the dislocation creep, diffusion creep, and plasticity, which is depended on temperature, pressure, and chemical composition. Then we calculate the seismic anisotropy from the shear deformation of mantle flow by DREX, and predict the fast direction and delay time of SKS splitting. We find that when complex boundary conditions are applied, including the far field effects of the deep subduction of Pacific plate and eastward escaping of Tibetan Plateau, our model can successfully predict the observed shear wave splitting patterns. Our model indicates that seismic anisotropy revealed by SKS is primarily resulting from the LPO of olivine due to the shear deformation from asthenospheric flow. We suggest that two branches of mantle flow may contribute to the observed anisotropy, that are, the westward escaping flow origins from NE Tibet Plateau and/or Mongolia, and the mantle upwelling from the bottom of upper mantle. The proposed mantle flow may also feed the intraplate volcanoes in the TNCO and intensify the erosion to the cratonic keel of Ordos.

Field-testing competing runoff source and hydrochemical conceptualisations

NASA Astrophysics Data System (ADS)

Western, A. W.; Saffarpour, S.; Adams, R.; Costelloe, J. F.; McDonnell, J.

2014-12-01

There are competing conceptualisations of heterogeneity in catchment systems. It is often convenient to divide catchments into zones, for example the soil profile, groundwater aquifers (saturated zone), riparian zones, etc. We also often divide flow sources into distinct categories such as surface runoff, interflow and baseflow, implying a few distinct stores of water. In tracer hydrology we typically assume water from such zones has distinct and invariant chemistry that is used to infer the runoff source mixture through conservative mixing model techniques such as End-Member Mixing Analysis (EMMA). An alternative conceptualisation is that catchments consist of a large number of stores with varying residence times. In this case individual stores contribute a variable proportion of flow and may have a temporally varying composition due to processes such as evapo-concentration. Hence they have a variable influence on the hydrochemistry of runoff. In this presentation, examples from two field studies in southern Australia will be presented that examine the relationships between hydrologic and hydrochemical conceptualisations and the relative variation within and between different hydrologic zones. The implications for water quality behaviour will be examined and the additional behavioural complexities associated with interactions between runoff pathways for non-conservative chemical species will be discussed.

The use of magnetic fields in vertical Bridgman/Gradient Freeze-type crystal growth

NASA Astrophysics Data System (ADS)

Pätzold, Olf; Niemietz, Kathrin; Lantzsch, Ronny; Galindo, Vladimir; Grants, Ilmars; Bellmann, Martin; Gerbeth, Gunter

2013-03-01

This paper outlines advanced vertical Bridgman/Gradient Freeze techniques with flow control using magnetic fields developed for the growth of semiconductor crystals. Low-temperature flow modelling, as well as laboratory-scaled crystal growth under the influence of rotating, travelling, and static magnetic fields are presented. Experimental and numerical flow modelling demonstrate the potential of the magnetic fields to establish a well-defined flow for tailoring heat and mass transfer in the melt during growth. The results of the growth experiments are discussed with a focus on the influence of a rotating field on the segregation of dopants, the influence of a travelling field on the temperature field and thermal stresses, and the potential of rotating and static fields for a stabilization of the melt flow.

Accelerated ions from pulsed-power-driven fast plasma flow in perpendicular magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takezaki, Taichi, E-mail: ttakezaki@stn.nagaokaut.ac.jp; Takahashi, Kazumasa; Sasaki, Toru, E-mail: sasakit@vos.nagaokaut.ac.jp

2016-06-15

To understand the interaction between fast plasma flow and perpendicular magnetic field, we have investigated the behavior of a one-dimensional fast plasma flow in a perpendicular magnetic field by a laboratory-scale experiment using a pulsed-power discharge. The velocity of the plasma flow generated by a tapered cone plasma focus device is about 30 km/s, and the magnetic Reynolds number is estimated to be 8.8. After flow through the perpendicular magnetic field, the accelerated ions are measured by an ion collector. To clarify the behavior of the accelerated ions and the electromagnetic fields, numerical simulations based on an electromagnetic hybrid particle-in-cell methodmore » have been carried out. The results show that the behavior of the accelerated ions corresponds qualitatively to the experimental results. Faster ions in the plasma flow are accelerated by the induced electromagnetic fields modulated with the plasma flow.« less

Natural gas flow through critical nozzles

NASA Technical Reports Server (NTRS)

Johnson, R. C.

1969-01-01

Empirical method for calculating both the mass flow rate and upstream volume flow rate through critical flow nozzles is determined. Method requires knowledge of the composition of natural gas, and of the upstream pressure and temperature.

Steam distillation extraction of ginger essential oil: Study of the effect of steam flow rate and time process

NASA Astrophysics Data System (ADS)

Fitriady, Muhammad Arifuddin; Sulaswatty, Anny; Agustian, Egi; Salahuddin, Aditama, Deska Prayoga Fauzi

2017-01-01

In Indonesia ginger was usually used as a seasoning for dishes, an ingredient for beverage and a source of herbal medicines. Beside raw usage, ginger can be processed to obtain the essential oil which has many advantages such as proven to be an active antimicrobial and having an antioxidant ability. There are a lot of methods to extract essential oil from ginger, one of which is steam distillation. The aim of the current study was to investigate the effect of variation of time process and steam flow rate in the yield on ginger essential oil steam distillation extraction process. It was found that the best operation condition was 0.35 ml/s as the steam flow rate which yields 2.43% oil. The optimum time process was predicted at 7.5 hours. The composition of the oil was varied depend on the flow rate and every flow rate has its own major component contained in the oil. Curcumene composition in the oil was increased as increased steam flow rate applied, but the composition of camphene was decreased along with the increasing steam flow rate.

1200 and 1300 K slow plastic compression properties of Ni-50Al composites

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.; Kumar, K. S.; Mannan, S. K.

1991-01-01

XD synthesis, powder blending, and hot pressing techniques have been utilized to produce NiAl composites containing 4, 7.5, 15, and 25 vol pct alumina whiskers and hybrid composite materials with 15 vol pct Al2O3 + 10 or 20 vol pct, nominally 1 micron TiB2 particles. The resistance to slow plastic flow was determined at 1200 and 1300 K via compression testing in air under constant velocity conditions. The stress-strain behavior of the intermetallic composites depended on the fraction of second phases where the 4 and 7.5 percent Al2O3 materials flowed at a nominally constant stress after about 2 percent deformation, while all the other composites exhibited diffuse yielding followed by strain softening. The flow stress-strain rate properties increased with volume fraction of Al2O3 whiskers except for the 4 and 7.5 percent materials, which had similar strengths. The hybrid composite NiAl + 15Al2O3 + 10TiB2 was substantially stronger than the materials simply containing alumina. Deformation in these composites can be described by the Kelly and Street model of creep in perfectly bonded, rigid, discontinuous fiber materials.