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1

An investigation of the establishment of a recirculation zone by swirling flows within a conical duct  

Microsoft Academic Search

This paper reports an investigation carried out on the recirculation zones established in conical chambers with radial vaned inlet swirlers. The boundaries of the recirculation zones established in various conical chambers of different cone angles are presented for different inlet swirl numbers and an optimum cone angle which gives a reasonably short length of the recirculation zone with maximum pressure

P. Rama Mohan; C. M. Vara Prasad

1983-01-01

2

Annular impinging jet with recirculation zone expanded by acoustic excitation  

Microsoft Academic Search

Flow visualization and mass transfer (naphthalene sublimation) experiments were performed on acoustically excited annular air jet with diameter ratio Di\\/Do=0.95. Two different regimes of the time-mean flow field were found, differing in the size of the central recirculation zone, with either the single stagnation point or the stagnation circle. The switching between the two regimes is accomplished by acoustic excitation,

Zden k Trávní ek; Václav Tes

3

Recirculation zone dynamics of a transversely excited swirl flow and flame  

NASA Astrophysics Data System (ADS)

This work investigates the response of the vortex breakdown region of a swirling, annular jet to transverse acoustic excitation for both non-reacting and reacting flows. This swirling flow field consists of a central vortex breakdown region, two shear layers, and an annular fluid jet. The vortex breakdown bubble, a region of highly turbulent recirculating flow in the center of the flowfield, is the result of a global instability of the swirling jet. Additionally, the two shear layers originating from the inner and outer edge of the annular nozzle are convectively unstable and rollup due to the Kelvin-Helmholtz instability. Unlike the convectively unstable shear layers that respond in a monotonic manner to acoustic forcing, the recirculation zone exhibits a range of response characteristics, ranging from minimal response to exhibiting abrupt bifurcations at large forcing amplitudes. In this study, the response of the time-average and fluctuating recirculation zone is measured as a function of forcing frequency, amplitude, and symmetry. The time-average flow field is shown to exhibit both monotonically varying and abrupt bifurcation features as acoustic forcing amplitude is increased. The unsteady motion in the recirculation zone is dominated by the low frequency precession of the vortex breakdown bubble. In the unforced flow, the azimuthal m = -2 and m = -1 modes (i.e., disturbances rotating in the same direction as the swirl flow) dominate the velocity disturbance field. These modes correspond to large scale deformation of the jet column and two small-scale precessing vortical structures in the recirculation zone, respectively. The presence of high amplitude acoustic forcing changes the relative amplitude of these two modes, as well as the character of the self-excited motion. For the reacting flow problem, we argue that the direct effect of these recirculation zone fluctuations on the flame response to flow forcing is not significant. Rather, flame wrinkling in response to flow forcing is dominated by shear layer disturbances. Recirculation zone dynamics primarily influence the time-average flame features (such as spreading angle). These influences on the flame response are indirect, as they control the transfer function relating shear layer fluctuations and the resulting flame response.

O'Connor, Jacqueline; Lieuwen, Tim

2012-07-01

4

Prediction of central recirculation zone size for a complete burner-quarl-furnace system  

Microsoft Academic Search

In the swirl flow burning process of fuels, the central recirculation zone plays an important role in flame stabilization by providing a hot flow of recirculated combustion products, which reduce both the length of flame and the stabilized flame distance from the burner mouth. In this paper, a new modified swirl number, S exp xx, related to the characteristic size

Eugen-Dan B. Cristea

1987-01-01

5

Flow Field Features of the Induced Recirculation Zone using Planar Jet Injection.  

NASA Astrophysics Data System (ADS)

The objective of the present work is to study the recirculation bubble induced by injecting a planar jet in to a channel flow. The work is motivated by the desire to provide a flame stabilization environment for ramjet engines without the use of a sudden expansion or bluff-body which incurs drag penalties. A planar jet issuing into a cross flow is used to create a recirculation zone reminiscent of the flow field created downstream of a rearward-facing step configuration which is used in a current ramjet/scramjet systems. The effect of confinement at high momentum flux ratios leads to a saturation of the control of the recirculation bubble size and strength. Comparison to a rearward-facing step flow shows the current method produces higher turbulence levels and larger integral length scales. It is clear that the flow field produced with fluidic injection has potential for flame anchoring and enhancing combustion rates.

Ahmed, Kareem; Forliti, David; Moody, Jack

2006-11-01

6

Vortex formation and recirculation zones in left anterior descending artery stenoses: computational fluid dynamics analysis  

NASA Astrophysics Data System (ADS)

Flow patterns may affect the potential of thrombus formation following plaque rupture. Computational fluid dynamics (CFD) were employed to assess hemodynamic conditions, and particularly flow recirculation and vortex formation in reconstructed arterial models associated with ST-elevation myocardial infraction (STEMI) or stable coronary stenosis (SCS) in the left anterior descending coronary artery (LAD). Results indicate that in the arterial models associated with STEMI, a 50% diameter stenosis immediately before or after a bifurcation creates a recirculation zone and vortex formation at the orifice of the bifurcation branch, for most of the cardiac cycle, thus allowing the creation of stagnating flow. These flow patterns are not seen in the SCS model with an identical stenosis. Post-stenotic recirculation in the presence of a 90% stenosis was evident at both the STEMI and SCS models. The presence of 90% diameter stenosis resulted in flow reduction in the LAD of 51.5% and 35.9% in the STEMI models and 37.6% in the SCS model, for a 10 mmHg pressure drop. CFD simulations in a reconstructed model of stenotic LAD segments indicate that specific anatomic characteristics create zones of vortices and flow recirculation that promote thrombus formation and potentially myocardial infarction.

Katritsis, D. G.; Theodorakakos, A.; Pantos, I.; Andriotis, A.; Efstathopoulos, E. P.; Siontis, G.; Karcanias, N.; Redwood, S.; Gavaises, M.

2010-03-01

7

Mixer assembly for a gas turbine engine having a pilot mixer with a corner flame stabilizing recirculation zone  

NASA Technical Reports Server (NTRS)

A mixer assembly for a gas turbine engine is provided, including a main mixer, and a pilot mixer having an annular housing in which a corner is formed between an aft portion of the housing and a bulkhead wall in which a corner recirculation zone is located to stabilize and anchor the flame of the pilot mixer. The pilot mixer can further include features to cool the annular housing, including in the area of the corner recirculation zone.

Dai, Zhongtao (Inventor); Cohen, Jeffrey M. (Inventor); Fotache, Catalin G. (Inventor)

2012-01-01

8

Prediction of central recirculation zone size for a complete burner-quarl-furnace system  

SciTech Connect

In the swirl flow burning process of fuels, the central recirculation zone plays an important role in flame stabilization by providing a hot flow of recirculated combustion products, which reduce both the length of flame and the stabilized flame distance from the burner mouth. In this paper, a new modified swirl number, S exp xx, related to the characteristic size of the burner quarl, is introduced to correlate the isothermal and burning flows. Using a well-known two-dimensional computational model, the isothermal flow pattern in a complete burner-quarl-furnace system is computed. On this basis, the theoretical swirl number S exp xx is calculated and used as a correlation parameter for predicting the central recirculation zone size in burning flow conditions. Experimental tests for both nonreacting and reacting flows on the same complete burner-quarl-furnace system, for comparing the theoretical and experimental swirl number s exp xx, have been conducted, and the validity of this new correlation parameter has been proved. 11 references.

Cristea, E.B.

1987-03-01

9

Central recirculation zone analysis in an unconfined tangential swirl burner with varying degrees of premixing  

NASA Astrophysics Data System (ADS)

Swirl-stabilised combustion is one of the most widely used techniques for flame stabilisation, uses ranging from gas turbine combustors to pulverised coal-fired power stations. In gas turbines, lean premixed systems are of especial importance, giving the ability to produce low NOx systems coupled with wide stability limits. The common element is the swirl burner, which depends on the generation of an aerodynamically formed central recirculation zone (CRZ) and which serves to recycle heat and active chemical species to the root of the flame as well as providing low-velocity regions where the flame speed can match the local flow velocity. Enhanced mixing in and around the CRZ is another beneficial feature. The structure of the CRZ and hence that of the associated flames, stabilisation and mixing processes have shown to be extremely complex, three-dimensional and time dependent. The characteristics of the CRZ depend very strongly on the level of swirl (swirl number), burner configuration, type of flow expansion, Reynolds number (i.e. flowrate) and equivalence ratio. Although numerical methods have had some success when compared to experimental results, the models still have difficulties at medium to high swirl levels, with complex geometries and varied equivalence ratios. This study thus focuses on experimental results obtained to characterise the CRZ formed under varied combustion conditions with different geometries and some variation of swirl number in a generic swirl burner. CRZ behaviour has similarities to the equivalent isothermal state, but is strongly dependent on equivalence ratio, with interesting effects occurring with a high-velocity fuel injector. Partial premixing and combustion cause more substantive changes to the CRZ than pure diffusive combustion.

Valera-Medina, A.; Syred, N.; Kay, P.; Griffiths, A.

2011-06-01

10

Exhaust recirculation  

Microsoft Academic Search

An exhaust gas recirculation system for the reduction of nitrogen oxide emissions from internal combustion engine exhaust is described that is uncomplicated by moving parts, thus avoiding problems associated with prior-art recirculation systems. The system also results in preheating and improved mixing of the fuel-air mixture in the inlet header. A recycling duct receives the exhaust gases at a restricted

Waitzmann

1974-01-01

11

Exhaust recirculation  

Microsoft Academic Search

An exhaust gas recirculation system for the reduction of nitrogen oxides in automobile exhaust is described that provides for the reduction of recirculation during engine idling without the prior-art complexities of moving parts. The system also achieves preheating and improved mixing and carburetion of the fuel-air mixture in the inlet header. Exhaust gases are recycled by means of a swirl

Sarto

1974-01-01

12

Recirculating rotary gas compressor  

DOEpatents

A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.

Weinbrecht, John F. (601 Oakwood Loop, NE., Albuquerque, NM 87123)

1992-01-01

13

Recirculating rotary gas compressor  

DOEpatents

A positive displacement, recirculating Roots-type rotary gas compressor is described which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits which return compressed discharge gas to the compressor housing, where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor. 12 figs.

Weinbrecht, J.F.

1992-02-25

14

Wind Effect, Recirculation and Thermal Flow Field of a Direct Air-cooled Condenser for a Large Power Plant  

NASA Astrophysics Data System (ADS)

The thermal effect experiments were carried out of a direct air-cooled system in the low speed wind tunnel. The influence of effect factors on recirculation is also discussion, after that the relationship between the thermal flow field structure and recirculation ratio under the cooling tower is analyzed. At last, the engineering measures to reduce or avoid recirculation are proposed. For certain conditions the experimental measurement shows close agreement with numerical values.

Zhao, W. L.; Liu, P. Q.; Duan, H. S.; Zhu, J. Y.

2011-09-01

15

Wind tunnel simulation of exhaust recirculation in an air-cooling system at a large power plant  

Microsoft Academic Search

The recirculation of hot exhaust air and its dependence on wind direction was investigated as a cause of reduced efficiency in an air-cooled condenser (ACC). A method of simulating exhaust air recirculation at an ACC platform using a wind tunnel is presented, and applied to a proposed ACC addition at an existing power plant. It was found that wind speed

Zhifu Gu; Xuerei Chen; William Lubitz; Yan Li; Wenlin Luo

2007-01-01

16

Lattice design for the LHEC recirculating LINAC  

Microsoft Academic Search

In this paper, we present a lattice design for the Large Hadron Electron Collider (LHeC) recirculating linac. The recirculating linac consists of one roughly 3-km long linac hosting superconducting RF (SRF) accelerating cavities, two arcs and one transfer line for the recirculation. In two passes through a pulsed SRF linac the electron beam can get a maximum energy of 140

Y P Sun; C Adolphsen; A Lund Eide; F Zimmermann

2010-01-01

17

Wind tunnel investigation on the retention of air pollutants in three-dimensional recirculation zones in urban areas  

NASA Astrophysics Data System (ADS)

The article discusses an experimental investigation of turbulent dispersion processes in a typical three-dimensional urban geometry, in reduced scale, in neutrally stable conditions. Wind tunnel experiments were carried out for characterizing the flow and the dispersion of a pollutant around a scaled model (1:400) of a group of eight 10-floor buildings surrounding a square. The situation corresponded to the dispersion of fine inertialess particles released from a line source positioned upstream of the urban geometry. After the sudden interruption of the source generation, the particles persisted in the recirculation cavity between the buildings, with the concentration decaying exponentially with time. This is in accordance with previous works on the dispersion process around bluff bodies of different shapes [e.g., Humphries and Vincent, 1976. An experimental investigation of the detention of airborne smoke in the wake bubble behind a disk. Journal of Fluid Mechanics 73, 453-464; Vincent, 1977. Model experiments on the nature of air pollution transport near buildings. Atmospheric Environment 11, 765-774; Fackrell, 1984. Parameters characterizing dispersion in the near wake of buildings. Journal of Wind Engineering and Industrial Aerodynamics 16, 97-118]. The main parameter in the investigation was the characteristic time constant for the concentration decay. The measurements of the variation in the concentration of the fine particles were performed by means of a photo-detection technique based on the attenuation of light. The velocity fields were evaluated with the particle image velocimetry (PIV) technique. The dimensionless residence time H for the particles ( H= ?U/ L, where ? is the time constant for the concentration decay, U the free-stream velocity, and L is a characteristic dimension for the urban geometry, as defined by Humphries and Vincent [1976. An experimental investigation of the detention of airborne smoke in the wake bubble behind a disk. Journal of Fluid Mechanics 73, 453-464] was determined for various locations in the scaled model, in the range of Reynolds numbers ( Re) between 8000 and 64,000. H was found to be 6.5±1.0.

Gomes, Marcos Sebastião de Paula; Isnard, André Augusto; Pinto, José Maurício do Carmo

18

Gas turbine combustor stabilization by heat recirculation  

NASA Technical Reports Server (NTRS)

The feasibility of heat recirculation for stabilization of lean mixtures and emission reduction has been studied in detail for a typical aircraft gas turbine combustor. Thermodynamic calculations have indicated temperature and heat recirculation rates for operation of the combustor over a range of combustion zone equivalence ratios and for varying modes of desired engine operation. Calculations indicate the feasibility of stabilizing the combustion zone at equivalence ratios as low as 0.2 with achievable heat recirculation rates. Detailed chemical kinetic calculations suggest that combustor heat release is maintained with reaction completion substantially before the NO forming reactions, even though CO is rapidly oxidized in this same region.

Ganji, A.; Short, J.; Branch, M. C.; Oppenheim, A. K.

1975-01-01

19

Percutaneous re-circulating isolated limb perfusion of gentamicin in a large animal model: targeted delivery of gentamicin to limb  

PubMed Central

Objective: We have developed a percutaneous recirculation system (V-Vascular, V-V) to enable delivery of high levels of antibiotic to the limb in an isolated and targeted manner for the treatment of limb infection. Background: Chronic and acute limb infections are relatively commonplace in a variety of wound types. Infection can become refractory to existing treatment strategies and can cause complications associated with wound healing, lead to amputation and even death. Methods: Gentamicin was delivered to the ovine hind limb (4 mg/kg) using the V-V system, a ‘closed’ recirculatory catheter system that draws blood from the venous system and returns it to the artery via an oxygenator, or via intra-venous (IV) infusion. Samples of muscle, bone and synovial fluid of the limb were collected at 30 and 60 min post administration of gentamicin. Results: There was a significantly greater concentration of gentamicin observed in the bone and skeletal muscle of limbs receiving the antibiotic via V-V at 30 min post administration compared to IV delivery, (bone V-V 0.05 ± 0.04, I.V 0.004 ± 0.001 mg/L p<0.05; muscle V-V 0.005 ± 0.001, I.V 0.002 ± 0.0005 mg/L p<0.05) and bone and synovial fluid at 60 min post administration (bone V-V 0.06 ± 0.02, I.V 0.005 ± 0.001 mg/L p<0.05; synovial fluid V-V 34.58 ± 14.9, I.V 3.03 ± 0.59 mg/L p<0.05). Conclusions: These results suggest that the use of percutaneous recirculation is a safe and effective method for delivering a greater concentration of antibiotic to the limb without systemic implications.

Byrne, Melissa J; Idrizi, Rejhan; Power, John M; Kaye, David M

2013-01-01

20

Design and fabrication of Fresnel zone plates with large numbers of zones  

SciTech Connect

The advent of high-brightness x-ray sources in the 10{endash}40 keV region opens new possibilities of experiments with microbeams. Techniques to form these focused beams may be based on glancing mirrors, phase elements, or diffractive optics, in particular Fresnel zone plates (FZPs). Because of the long focal length and large acceptance, FZPs designed to work in the hard x-ray region tend to have quite large diameters and large numbers of zones. For instance, the zone plate described in this article has a 1860 {mu}m diam, a focal length of f=3 m (for 8 keV), and 1860 zones. On a standard pattern generator, circular shapes are always approximated as simpler structures. The tolerance requirement for shape and positions of zones depends on the number of zones, and it is necessary to guarantee that the circular structures are approximated to the required degree of accuracy while keeping the size of the data structure to a reasonable size for processing by the exposure system. For instance, if polygons are used to approximate circular zones, a formula for the minimum acceptable number of polygon sides can be derived. An x-ray mask for a Fresnel phase zone plate (FPZP) with 1860 zones was designed directly in Cambridge source pattern data format and fabricated using the Leica Cambridge e-beam tool installed in the CXrL. The zone plates presented in this article were designed for hard x rays, and multilevel x-ray lithography was employed as a fabrication technique to form absorber thickness sufficient to provide the necessary phase shift. Minimum gold features of 0.25 {mu}m with thicknesses of 1.6 and 3 {mu}m, were formed to be used with 8 and 20 keV photons, respectively. Finally, in order to estimate the quality of the zone plates during fabrication, a scanning electron microscope based moir{acute e} method was used. {copyright} {ital 1997 American Vacuum Society.}

Chen, Z.; Vladimirsky, Y.; Brown, M.; Leonard, Q.; Vladimirsky, O.; Moore, F.; Cerrina, F. [Center For X-ray Lithography, 3731 Schneider Drive, Stoughton, Wisconsin 53589-3097 (United States)] [Center For X-ray Lithography, 3731 Schneider Drive, Stoughton, Wisconsin 53589-3097 (United States); Lai, B.; Yun, W.; Gluskin, E. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

1997-11-01

21

Recirculating flow and sedimentation in the Colorado River in Grand Canyon, Arizona  

Microsoft Academic Search

Debris fans debouching into the bottom of Grand Canyon create rapids and flow separation in the Colorado River. The patterns of flow and the behavior of recirculation zones formed by flow separation are consistent throughout the Canyon's length. Zones of recirculating flow occur along the margin of channel expansions. Recirculation zones are comprised of one primary eddy; secondary eddies and

John C. Schmidt

1990-01-01

22

Design and fabrication of Fresnel zone plates with large numbers of zones  

Microsoft Academic Search

The advent of high-brightness x-ray sources in the 10â40 keV region opens new possibilities of experiments with microbeams. Techniques to form these focused beams may be based on glancing mirrors, phase elements, or diffractive optics, in particular Fresnel zone plates (FZPs). Because of the long focal length and large acceptance, FZPs designed to work in the hard x-ray region tend

Z. Chen; Y. Vladimirsky; M. Brown; Q. Leonard; O. Vladimirsky; F. Moore; F. Cerrina; B. Lai; W. Yun; E. Gluskin

1997-01-01

23

Validation for a recirculation model.  

PubMed

Recent Clean Air Act regulations designed to reduce volatile organic compound (VOC) emissions have placed new restrictions on painting operations. Treating large volumes of air which contain dilute quantities of VOCs can be expensive. Recirculating some fraction of the air allows an operator to comply with environmental regulations at reduced cost. However, there is a potential impact on employee safety because indoor pollutants will inevitably increase when air is recirculated. A computer model was developed, written in Microsoft Excel 97, to predict compliance costs and indoor air concentration changes with respect to changes in the level of recirculation for a given facility. The model predicts indoor air concentrations based on product usage and mass balance equations. This article validates the recirculation model using data collected from a C-130 aircraft painting facility at Hill Air Force Base, Utah. Air sampling data and air control cost quotes from vendors were collected for the Hill AFB painting facility and compared to the model's predictions. The model's predictions for strontium chromate and isocyanate air concentrations were generally between the maximum and minimum air sampling points with a tendency to predict near the maximum sampling points. The model's capital cost predictions for a thermal VOC control device ranged from a 14 percent underestimate to a 50 percent overestimate of the average cost quotes. A sensitivity analysis of the variables is also included. The model is demonstrated to be a good evaluation tool in understanding the impact of recirculation. PMID:11318387

LaPuma, P T

2001-04-01

24

Temporal variation of large intraplate earthquakes in coupled subduction zones  

NASA Astrophysics Data System (ADS)

The focal mechanisms of intraplate earthquakes within subducting lithosphere are frequently used to infer large-scale stress regimes induced by slab-pull, bending or unbending, and lateral segmentation and undulations of the slab. Numerous studies have further postulated that the intraplate activity is influenced by transitory regional stress regimes such as those associated with interplate thrust events. Temporal variations of the latter type may potentially play an important role in assessing regions of uncertain seismic potential, and possibly even in earthquake forecasting. A systematic analysis of 1130 focal mechanisms for intraplate earthquakes with mb ? 5.0 in the depth range 0-300 km is conducted for nine circum-Pacific subduction zones, all of which are known to have large interplate thrust events. The spatial and temporal relationships of the earthquakes within the subducting slab to the large thrust events in each region are appraised. The earthquake catalog assembled contains all published focal mechanisms, and is probably complete for mb ? 6.5 for the years 1963-1986. For many of the localized regions considered in detail the catalog is complete to lower thresholds of mb ? 6.0 or mb ? 5.5. This analysis provides compelling evidence for a temporal link between large interplate thrust activity and intraplate seismicity. For the seismically coupled regions considered here, outer rise compressional events have occurred prior to several large thrust events or are associated with seismic gaps, while outer rise tensional events generally only follow interplate ruptures. In the intermediate depth range, large down-dip tensional events generally precede interplate thrusts, and are often concentrated at the down-dip edge of the coupled zone. A transition to down-dip compressional stress or diminished tensional activity at intermediate depth is observed after several large thrust events (e.g., 1960 Chile, 1974 Peru, 1957 Aleutian, 1971 New Britain). These examples support the notion that the intraplate stress environment responds viscoelastically to the temporally varying interplate stress regime. Assuming that this concept is correct, the seismic potential of several seismic gaps is considered on the basis of both outer rise and intermediate depth earthquake activity.

Lay, Thorne; Astiz, Luciana; Kanamori, Hiroo; Christensen, Douglas H.

1989-04-01

25

Confined turbulent swirling recirculating flow predictions. Ph.D. Thesis. Final Report  

NASA Technical Reports Server (NTRS)

The capability and the accuracy of the STARPIC computer code in predicting confined turbulent swirling recirculating flows is presented. Inlet flow boundary conditions were demonstrated to be extremely important in simulating a flowfield via numerical calculations. The degree of swirl strength and expansion ratio have strong effects on the characteristics of swirling flow. In a nonswirling flow, a large corner recirculation zone exists in the flowfield with an expansion ratio greater than one. However, as the degree of inlet swirl increases, the size of this zone decreases and a central recirculation zone appears near the inlet. Generally, the size of the central zone increased with swirl strength and expansion ratio. Neither the standard k-epsilon turbulence mode nor its previous extensions show effective capability for predicting confined turbulent swirling recirculating flows. However, either reduced optimum values of three parameters in the mode or the empirical C sub mu formulation obtained via careful analysis of available turbulence measurements, can provide more acceptable accuracy in the prediction of these swirling flows.

Abujelala, M. T.; Lilley, D. G.

1985-01-01

26

Lattice Design for the LHEC Recirculating Linac  

SciTech Connect

In this paper, we present a lattice design for the Large Hadron Electron Collider (LHeC) recirculating linac. The recirculating linac consists of one roughly 3-km long linac hosting superconducting RF (SRF) accelerating cavities, two arcs and one transfer line for the recirculation. In two passes through a pulsed SRF linac the electron beam can get a maximum energy of 140 GeV. Alternatively, in the Energy Recovery Linac (ERL) option the beam passes through a CW linac four times (two passes for acceleration and two for deceleration) for a maximum energy of 60 GeV.

Sun, Yipeng; /CERN; Eide, Anders; /CERN; Zimmermann, Frank; /CERN; Adolphsen, Chris; /SLAC

2011-05-20

27

Cooling Along Hyporheic Pathlines in a Large River Riparian Zone  

NASA Astrophysics Data System (ADS)

Floodplains can contribute to hyporheic cooling and moderation of temperature for rivers, but extent and magnitude are dependent on ground water hydrology. Here we illustrate the controls and dynamics of hyporheic cooling in the ground water of a large river floodplain. We used field data and numerical flow modeling in a region where cooling may influence the formation of coldwater refugia, a valuable ecosystem service for the preservation of salmon habitat. Hyporheic flow and ground water temperature were extensively monitored and characterized along a floodplain section of the Willamette River, Oregon, USA. Numerical flow modeling was done for the strongly contrasting dry and wet season flow patterns. During the warm dry season of our study, we observed significant temperature reduction with distance along most of the pathlines. Examination of particle tracking results indicate that in our site's floodplain areas, hyporheic flow during the wet season often has a locally downward component due to recharge from infiltration of rainfall, although dry season ground water flow also often moves deeper along the longer pathlines. In the dry season, pathlines trend to horizontal. Overall, the observed dry season temperature profiles obeyed the analytical solution to a one-dimensional steady-state governing equation for heat transfer in porous media, with differing thermal Péclet numbers. In one gravel bar, a mean pathline length of about 600 m reduced temperature 18 to 11 degrees Celsius. This cooling occurred over a residence time of 3-4 years before re-emergence, and incorporates the water table fluctuation, and wet season recharge from infiltration of rainfall that produces a locally downward trend of the hyporheic water prior to moving upward and discharging to cutoffs and alcoves. In some of the islands, wet season ground water underwent sufficient mounding to halt or reverse dry season river water that had entered the hyporheic zone. In our floodplain site water table fluctuations, wet season infiltration, and river stage appeared to control patterns of hypoheic cooling. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.

Faulkner, B. R.; Forshay, K. J.; Brooks, J.; Adeuya, R. K.; Cline, S. P.

2012-12-01

28

Development of a Turbulence-Resolving, Three-dimensional, Free Water Surface Numerical Model for Recirculation Eddies in Grand Canyon  

NASA Astrophysics Data System (ADS)

In the Colorado River in Grand Canyon, sand bars, which are built in recirculation areas downstream of channel expansions are valuable resources, particularly as natural habitat for endangered native fish and recreation sites for recreation. Since the closure of Glen Canyon Dam in 1963, there has been a reduction in the size of recirculation eddy bars. Simulated floods in the Colorado after tributary flood sediment input from the Paria River are being investigated as a method of rebuilding recirculation eddy beaches. Time-averaged, two-dimensional (and quasi- three-dimensional) numerical models have been employed to predict deposition during these beach/habit-building test flows. However, behind channel expansion areas, flows are strongly three-dimensional and the cross-channel flow is driven primarily by upwelling boils along the eddy fence that are neither stationary in time or space. Furthermore, these strong vertical motions along the eddy fence preclude use of the hydrostatic assumption. In this study, a non-hydrostatic three-dimensional numerical model is presented in order to calculate flow velocity in channels having rapid channel expansions. This model employs the Large Eddy Simulation (LES) turbulence modeling technique. LES uses spatial filtering to separate flows into gird scale and sub-gird scale rather than time averaging, thus it directly calculates large-scale turbulent motions. Also, this model employs a moving grid system and the Body Fitted Coordinate (BFC) system. These grid and coordinate systems allow the model to calculate time-dependent free water surface levels induced by large-scale turbulent motions. The model_fs calculation results are compared to existing experimental results of an open channel flow expansion in a laboratory flume. The comparison shows that the model succeeds to reproduce several key features of the flow, such as the temporally- and vertically-averaged horizontal recirculation eddy structure, and the time-averaged cross-stream vertical flow structure, which has inward flow (into the recirculation zone) at the surface and outward flow near the bed. The calculated water surface level also seems adequate. Its maximum is at the upstream side of the channel expansion and 3% higher than that of the minimum at the downstream end of the recirculation zone. Calculation results show that horizontal eddies are intermittently produced along the separation line between the recirculation zone and the main channel, and those produced eddies move into the recirculation zone while expanding their size.

Akahori, R.; Schmeeckle, M. W.

2005-12-01

29

33 CFR 165.839 - Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest...165.839 Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest...are established around all large cruise ships transiting between the Southwest Pass...

2013-07-01

30

Stress evolution following the 1811–1812 large earthquakes in the New Madrid Seismic Zone  

Microsoft Academic Search

Following a series of large (Mw = 7.0–7.5) earthquakes in the New Madrid Seismic Zone (NMSZ) in the central US during 1811 and 1812, more than a dozen moderate-size (M > 5) earthquakes occurred in this region, but mostly outside of the NMSZ fault zone. We have simulated the evolution of Coulomb stress and strain energy in the NMSZ and

Qingsong Li; Mian Liu; Eric Sandvol

2005-01-01

31

Stress evolution following the 1811-1812 large earthquakes in the New Madrid Seismic Zone  

Microsoft Academic Search

Following a series of large (Mw = 7.0-7.5) earthquakes in the New Madrid Seismic Zone (NMSZ) in the central US during 1811 and 1812, more than a dozen moderate-size (M > 5) earthquakes occurred in this region, but mostly outside of the NMSZ fault zone. We have simulated the evolution of Coulomb stress and strain energy in the NMSZ and

Qingsong Li; Mian Liu; Eric Sandvol

2005-01-01

32

Cooling Along Hyporheic Pathlines in a Large River Riparian Zone  

EPA Science Inventory

Floodplains can contribute to hyporheic cooling and moderation of temperature for rivers, but extent and magnitude are dependent on ground water hydrology. Here we illustrate the controls and dynamics of hyporheic cooling in the ground water of a large river floodplain with field...

33

Airlift recirculation well test results -- Southern sector  

SciTech Connect

Chlorinated solvents used in the A and M-Areas at the Savannah River Site (SRS) from 1952--1982 have contaminated the groundwater under the site. A plume of groundwater contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) in the Lost Lake aquifer is moving generally southward with the natural flow of groundwater. To comply with the requirements of the current SCDHEC Part B Permit, a series of wells is being installed to contain and treat the plume. Airlift Recirculation Wells (ARW) are a new and innovative technology with potential for more cost effective implementation than conventional pump and treat systems. Two Airlift Recirculation Wells have been installed and tested to quantify performance parameters needed to locate a line of these wells along the leading edge of the contaminant plume. The wells proved to be very sensitive to proper development, but after this requirement was met, performance was very good. The Zone of Capture has been estimated to be within a radius of 130--160 ft. around the wells. Thus a line of wells spaced at 250 ft. intervals could intercept the contaminant plume. At SSR-012, TCE was stripped from the groundwater at approximately 1.2 lb./day. The longer term effect of the recirculation wells upon the plume and the degree of recirculation within the aquifer itself will require additional data over a longer time period for an accurate review. Data collection is ongoing.

White, R.M.; Hiergesell, R.A.

1997-08-01

34

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Portland, OR Captain of...  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Security and Safety Zone Regulations, Large...Guard District § 165.1318 Security and Safety Zone Regulations, Large Passenger...impractical for the purpose of port security, safety or environmental...

2010-07-01

35

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Portland, OR Captain of...  

Code of Federal Regulations, 2010 CFR

... 2009-07-01 false Security and Safety Zone Regulations, Large...Guard District § 165.1318 Security and Safety Zone Regulations, Large Passenger...impractical for the purpose of port security, safety or environmental...

2009-07-01

36

Solar Sail Fresnel Zone Plate Lens for a Large Space Based Telescope.  

National Technical Information Service (NTIS)

A Fresnel zone plat lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by...

J. T. Early

2003-01-01

37

Quiet zone within a seismic gap near western Nicaragua: Possible location of a future large earthquake  

USGS Publications Warehouse

A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone. Copyright ?? 1981 AAAS.

Harlow, D. H.; White, R. A.; Cifuentes, I. L.; Aburto, Q. , A.

1981-01-01

38

Exhaust gas recirculation system  

SciTech Connect

An engine exhaust gas recirculation (EGR) system is provided in which a sonic flow EGR valve is moved to open positions to establish a different constant rate of flow at each open position of the EGR valve in response to air pressure acting on a servo means secured to the valve, the air pressure force being controlled by changes in a control vacuum opposing the air pressure force and modified by an air bleed device as a function of changes in engine exhaust gas backpressure levels, to provide an EGR valve movement that varies essentially in proportion to changes in engine air flow.

Rachedi, S.H.

1983-08-30

39

A proposal for Zoning Crossover of Hybrid Genetic Algorithms for large-scale traveling salesman problems  

Microsoft Academic Search

This paper proposes a novel crossover operator for solving large-scale traveling salesman problems (TSPs) by using a Hybrid Genetic Algorithm (HGA) with Lin-Kernighan heuristic for local search and we tentatively name Zoning Crossover (Z-Cross). The outline of Z-Cross is firstly to set a zone in the travelling area according to some rules, secondly to cut edges connecting cities between inside

Masafumi Kuroda; Kunihito Yamamori; Masaharu Munetomo; Moritoshi Yasunaga; Ikuo Yoshihara

2010-01-01

40

High ratio recirculating gas compressor  

SciTech Connect

A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.

Weinbrecht, John F. (601 Oakwood Pl., NE., Albuquerque, NM 87123)

1989-01-01

41

Exhaust gas recirculator  

SciTech Connect

An exhaust gas recirculator for an internal combustion engine having an exhaust pipe, an intake manifold and a carburetor throttle valve. The exhaust gas recirculator comprises an egr passage which makes the exhaust pipe communicate with the intake manifold, an egr controlling valve and an egr valve respectively arranged in the upper and lower portions of the egr passage. The egr valve operates in association with the carburetor throttle valve for metering the flow of egr gas. The egr controlling valve is separated by a diaphragm into an egr gas chamber communicating with the egr passage between the egr controlling valve and the egr valve and a negative pressure chamber communicating with the intake manifold. The negative pressure chamber contains a compression spring, and the diaphragm is connected with a valve member through a rod upon which is disposed a stopper to serve as a different seal in place of the valve member to close off the exhaust gas passage, which valve member and stopper are constructed to be opened and closed by pressure difference between the egr gas chamber and the negative pressure chamber and by elastic force of the compression spring. The egr controlling valve functions to control the pressure difference around the egr valve to be constant.

Suda, K.

1983-01-04

42

Large-scale laboratory measurements of sheet flow sediment transport in the swash zone  

NASA Astrophysics Data System (ADS)

Existing sediment transport models show poor predictive quality when applied to the swash zone, indicating that the underlying processes of swash zone sediment transport are not yet fully understood. The recognition that more detailed measurements are needed to improve understanding of swash-zone processes has led to several recent innovations in swash-zone measurement techniques. One of these innovative measurement techniques, the Conductivity Concentration Profiler (CCP), was developed to address the issue of near-bed (sheet flow) sediment transport, which is believed to be an important part of the overall swash-zone sediment transport. Measurements of sheet flow processes in the swash zone from the Barrier Dynamics Experiment (Bardex-II) are presented. The aim of this study was to investigate the dynamics of a coastal barrier system and develop an increased understanding of cross-shore sediment transport processes in the nearshore zone of sandy beaches. A 70-m long, near-prototype scale sandy barrier was constructed in a large wave flume facility and equipped with over 200 sensors to measure hydrodynamics and sediment processes ranging from the shoaling-wave zone to the back barrier. CCP sensors were deployed at three locations in the swash zone as part of the ';swash and berm dynamics' work package. Onshore-directed pressure gradients, observed during the initial stages of uprush, enhanced sediment mobilization. The combination of near-bed sediment mobilization due to pressure gradients (known as plug flow) and shear stress (sheet flow) is examined. Sediment load in the sheet flow layer is also compared to suspended load and total load measured using an array of optical backscatter sensors. The sheet flow layer thickness is compared to hydrodynamic forcing such as bed shear stress and the effect of groundwater exchange.

Lanckriet, T. M.; Puleo, J. A.; Foster, D. L.

2013-12-01

43

Recirculating fluidized bed combustion system for a steam generator  

SciTech Connect

The invention comprises a steam generator fluidized bed which recirculates through a major portion of the normal gas to fluid heat transfer circuits. Solid bed material is separated, collected and recirculated. Bed temperatures are limited by regulation of density of bed inert material to inhibit the radiant aspects of combustion. Gas recirculation is used to supplement air flow to achieve higher than entrainment bed gas velocity in the fuel ignition and reaction zone. Fuel ignition and reaction are controlled by limiting the amount of atmospheric air flow to the circulating fuel rich bed mixture to regulate extent of propagation of the ignition and reaction zone into the initial portion of the circulating bed loop, starting from the point of highest gas pressure.

Strohmeyer, C. Jr.

1984-04-17

44

Nuclear reactor coolant recirculation  

SciTech Connect

A system is described for forcing a liquid water coolant to recirculate through an unshrouded nuclear core in a pressure vessel. The core includes an array of spaced fuel assemblies supported between a lower core support member and an upper core support member. Each of the fuel assemblies is fitted with a tubular flow channel for containing water coolant flowing therethrough; an annular lower support ring attached to the pressure vessel and connected to the lower core support member for support thereof. The lower core support member, the lower support ring and the lower part of the pressure vessel form a lower plenum wherein the coolant can be pressurized. An upper support ring is attached to the pressure vessel and connected to the upper core support member. A space in the pressure vessel above the upper core support member forms an upper plenum for containing water coolant. Coolant pressurizers within the pressure vessel each have a coolant inlet and a coolant outlet and vertically oriented elongated coolant conducts conduits positioned in radially spaced relation between the core and the inner wall of the pressure vessel and extends from the upper plenum to the lower plenum. Each is connected to the coolant inlet of a respective one of the coolant pressurizers and each penetrates the upper support ring for conducting coolant from the upper plenum to the coolant inlet. The coolant outlet of each coolant pressurizer is in fluid communication with the lower plenum for pressurizing the coolant therein. Primary coolant passages are through the lower support member for admitting a pressurized coolant from the lower plenum into the fuel assemblies; and coolant outlet means at the upper end of the core are for discharging liquid coolant from the core to the upper plenum whereby the coolant is recirculated from the lower plenum, through the core to the upper plenum and back to the lower plenum.

Hobson, R.R.

1987-09-29

45

The Impact of Laptop-Free Zones on Student Performance and Attitudes in Large Lectures  

ERIC Educational Resources Information Center

The goal of this study was to determine if laptop use in lecture negatively impacts learning outcomes of surrounding students taking notes on paper. Two sections of a large introductory biology course (greater than 400 students/section) were zoned into a laptop-permitted and a laptop-free area. Two sections in which laptop users could sit anywhere…

Aguilar-Roca, Nancy M.; Williams, Adrienne E.; O'Dowd, Diane K.

2012-01-01

46

Adaptation to heat and water shortage in large, arid-zone mammals.  

PubMed

Although laboratory studies of large mammals have revealed valuable information on thermoregulation, such studies cannot predict accurately how animals respond in their natural habitats. Through insights obtained on thermoregulatory behavior, body temperature variability, and selective brain cooling in free-living mammals, we show here how we can better understand the physiological capacity of large mammals to cope with hotter and drier arid-zone habitats likely with climate change. PMID:24789980

Fuller, Andrea; Hetem, Robyn S; Maloney, Shane K; Mitchell, Duncan

2014-05-01

47

Seismic gaps and source zones of recent large earthquakes in coastal Peru  

USGS Publications Warehouse

The earthquakes of central coastal Peru occur principally in two distinct zones of shallow earthquake activity that are inland of and parallel to the axis of the Peru Trench. The interface-thrust (IT) zone includes the great thrust-fault earthquakes of 17 October 1966 and 3 October 1974. The coastal-plate interior (CPI) zone includes the great earthquake of 31 May 1970, and is located about 50 km inland of and 30 km deeper than the interface thrust zone. The occurrence of a large earthquake in one zone may not relieve elastic strain in the adjoining zone, thus complicating the application of the seismic gap concept to central coastal Peru. However, recognition of two seismic zones may facilitate detection of seismicity precursory to a large earthquake in a given zone; removal of probable CPI-zone earthquakes from plots of seismicity prior to the 1974 main shock dramatically emphasizes the high seismic activity near the rupture zone of that earthquake in the five years preceding the main shock. Other conclusions on the seismicity of coastal Peru that affect the application of the seismic gap concept to this region are: (1) Aftershocks of the great earthquakes of 1966, 1970, and 1974 occurred in spatially separated clusters. Some clusters may represent distinct small source regions triggered by the main shock rather than delimiting the total extent of main-shock rupture. The uncertainty in the interpretation of aftershock clusters results in corresponding uncertainties in estimates of stress drop and estimates of the dimensions of the seismic gap that has been filled by a major earthquake. (2) Aftershocks of the great thrust-fault earthquakes of 1966 and 1974 generally did not extend seaward as far as the Peru Trench. (3) None of the three great earthquakes produced significant teleseismic activity in the following month in the source regions of the other two earthquakes. The earthquake hypocenters that form the basis of this study were relocated using station adjustments computed by the method of joint hypocenter determination. ?? 1979 Birkha??user Verlag.

Dewey, J. W.; Spence, W.

1979-01-01

48

Combustion-gas recirculation system  

DOEpatents

A combustion-gas recirculation system has a mixing chamber with a mixing-chamber inlet and a mixing-chamber outlet. The combustion-gas recirculation system may further include a duct connected to the mixing-chamber inlet. Additionally, the combustion-gas recirculation system may include an open inlet channel with a solid outer wall. The open inlet channel may extend into the mixing chamber such that an end of the open inlet channel is disposed between the mixing-chamber inlet and the mixing-chamber outlet. Furthermore, air within the open inlet channel may be at a pressure near or below atmospheric pressure.

Baldwin, Darryl Dean (Lacon, IL) [Lacon, IL

2007-10-09

49

Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project.  

PubMed

Determining the seismic fracture energy during an earthquake and understanding the associated creation and development of a fault zone requires a combination of both seismological and geological field data. The actual thickness of the zone that slips during the rupture of a large earthquake is not known and is a key seismological parameter in understanding energy dissipation, rupture processes and seismic efficiency. The 1999 magnitude-7.7 earthquake in Chi-Chi, Taiwan, produced large slip (8 to 10 metres) at or near the surface, which is accessible to borehole drilling and provides a rare opportunity to sample a fault that had large slip in a recent earthquake. Here we present the retrieved cores from the Taiwan Chelungpu-fault Drilling Project and identify the main slip zone associated with the Chi-Chi earthquake. The surface fracture energy estimated from grain sizes in the gouge zone of the fault sample was directly compared to the seismic fracture energy determined from near-field seismic data. From the comparison, the contribution of gouge surface energy to the earthquake breakdown work is quantified to be 6 per cent. PMID:17122854

Ma, Kuo-Fong; Tanaka, Hidemi; Song, Sheng-Rong; Wang, Chien-Ying; Hung, Jih-Hao; Tsai, Yi-Ben; Mori, Jim; Song, Yen-Fang; Yeh, Eh-Chao; Soh, Wonn; Sone, Hiroki; Kuo, Li-Wei; Wu, Hung-Yu

2006-11-23

50

Stress evolution following the 1811-1812 large earthquakes in the New Madrid Seismic Zone  

NASA Astrophysics Data System (ADS)

Following a series of large (Mw = 7.0-7.5) earthquakes in the New Madrid Seismic Zone (NMSZ) in the central US during 1811 and 1812, more than a dozen moderate-size (M > 5) earthquakes occurred in this region, but mostly outside of the NMSZ fault zone. We have simulated the evolution of Coulomb stress and strain energy in the NMSZ and surrounding regions following the large 1811-1812 events in a three-dimensional viscoelastic finite element model. The results show that much of the stress and strain energy released by the large 1811-1812 events has migrated to southern Illinois and eastern Arkansas, consistent with the seismicity distribution. This inherited strain energy in these areas is capable of producing damaging (M = 6-7) earthquakes today.

Li, Qingsong; Liu, Mian; Sandvol, Eric

2005-06-01

51

Megacities and large urban agglomerations in the coastal zone: interactions between atmosphere, land, and marine ecosystems.  

PubMed

Megacities are not only important drivers for socio-economic development but also sources of environmental challenges. Many megacities and large urban agglomerations are located in the coastal zone where land, atmosphere, and ocean meet, posing multiple environmental challenges which we consider here. The atmospheric flow around megacities is complicated by urban heat island effects and topographic flows and sea breezes and influences air pollution and human health. The outflow of polluted air over the ocean perturbs biogeochemical processes. Contaminant inputs can damage downstream coastal zone ecosystem function and resources including fisheries, induce harmful algal blooms and feedback to the atmosphere via marine emissions. The scale of influence of megacities in the coastal zone is hundreds to thousands of kilometers in the atmosphere and tens to hundreds of kilometers in the ocean. We list research needs to further our understanding of coastal megacities with the ultimate aim to improve their environmental management. PMID:23076973

von Glasow, Roland; Jickells, Tim D; Baklanov, Alexander; Carmichael, Gregory R; Church, Tom M; Gallardo, Laura; Hughes, Claire; Kanakidou, Maria; Liss, Peter S; Mee, Laurence; Raine, Robin; Ramachandran, Purvaja; Ramesh, R; Sundseth, Kyrre; Tsunogai, Urumu; Uematsu, Mitsuo; Zhu, Tong

2013-02-01

52

Analysis of the dopant segregation effects at the floating zone growth of large silicon crystals  

NASA Astrophysics Data System (ADS)

A computer simulation is carried out to study the dopant concentration fields in the molten zone and in the growing crystal for the floating zone (FZ) growth of large (> 100mm) Si crystals with the needle-eye technique and with feed/crystal rotation. The mathematical model developed in the previous work is used to calculate the shape of the molten zone and the velocity field in the melt. The influence of melt convection on the dopant concentration field is considered. The significance of the rotation scheme of the feed rod and crystal on the dopant distribution is investigated. The calculated dopant concentration directly at the growth interface is used to determine the normalized lateral resistivity distribution in the single crystal. The calculated resistivity distributions are compared with lateral spreading resistivity measurements in the single crystal.

Mühlbauer, A.; Muiznieks, A.; Virbulis, J.

1997-10-01

53

DHW Recirculation System Control Strategies.  

National Technical Information Service (NTIS)

This study was the third step in a series of research projects that examined domestic hot water (DHW) issues in multi family buildings. The research analyzed the effects of varying control strategies of DHW recirculation systems in multi family buildings....

1999-01-01

54

Hydroxyl time series and recirculation in turbulent nonpremixed swirling flames  

SciTech Connect

Time-series measurements of OH, as related to accompanying flow structures, are reported using picosecond time-resolved laser-induced fluorescence (PITLIF) and particle-imaging velocimetry (PIV) for turbulent, swirling, nonpremixed methane-air flames. The [OH] data portray a primary reaction zone surrounding the internal recirculation zone, with residual OH in the recirculation zone approaching chemical equilibrium. Modeling of the OH electronic quenching environment, when compared to fluorescence lifetime measurements, offers additional evidence that the reaction zone burns as a partially premixed flame. A time-series analysis affirms the presence of thin flamelet-like regions based on the relation between swirl-induced turbulence and fluctuations of [OH] in the reaction and recirculation zones. The OH integral time-scales are found to correspond qualitatively to local mean velocities. Furthermore, quantitative dependencies can be established with respect to axial position, Reynolds number, and global equivalence ratio. Given these relationships, the OH time-scales, and thus the primary reaction zone, appear to be dominated by convection-driven fluctuations. Surprisingly, the OH time-scales for these nominally swirling flames demonstrate significant similarities to previous PITLIF results in nonpremixed jet flames. (author)

Guttenfelder, Walter A.; Laurendeau, Normand M.; Ji, Jun; King, Galen B.; Gore, Jay P. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-1288 (United States); Renfro, Michael W. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269-3139 (United States)

2006-10-15

55

Large Bi2212 single crystal growth by the floating-zone technique  

Microsoft Academic Search

Effects of growth velocity on the crystal-growth behavior of Bi2Sr2Ca1Cu2Ox (Bi-2212) have been studied by the floating-zone technique. The results show that a necessary condition for obtaining large single crystals along the c-axis is that the solid–liquid interface of a growing rod maintains a stable planar growth front. The planar liquid–solid growth interface tends to break down into a cellular

J. S. Wen; Z. J. Xu; G. Y. Xu; M. Hücker; J. M. Tranquada; G. D. Gu

2008-01-01

56

Large Bi2212 single crystal growth by the floating-zone technique  

Microsoft Academic Search

Effects of the growth velocity on the crystal growth behavior of Bi_2Sr_2Ca_1Cu_2O_x (Bi-2212) have been studied by floating zone technique. The results show that a necessary condition for obtaining large single crystals along the c-axis is that the solid-liquid interface of a growing rod maintains a stable planar growth front. The planar liquid-solid growth interface tends to break down into

J. S. Wen; Z. J. Xu; G. Y. Xu; M. Hücker; J. M. Tranquada; G. D. Gu

2008-01-01

57

77 FR 65816 - Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

Federal Register 2010, 2011, 2012, 2013

...1625-AA00 Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest Pass...moving safety zone around large cruise ships as they transit the Lower Mississippi River between the Port of New Orleans Cruise Ship Terminal, mile marker 96.0, and...

2012-10-31

58

77 FR 29254 - Safety Zones, Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

Federal Register 2010, 2011, 2012, 2013

...1625-AA00 Safety Zones, Large Cruise Ships; Lower Mississippi River, Southwest Pass...moving safety zone around large cruise ships as they transit the Lower Mississippi River between the Port of New Orleans Cruise Ship Terminal, mile marker 96.0 and the...

2012-05-17

59

Nitrate distribution and isotopic composition in vadose-zone sediments underlying large dairy operations  

NASA Astrophysics Data System (ADS)

Understanding the transport and cycling of nitrate in the vadose zone is essential to 1) linking agronomic models of nitrate flux out of the root zone to groundwater models of nitrate loading at the water table, 2) quantifying the impact of vadose-zone biogeochemical processes on nitrate isotopic composition for the purpose of source attribution, and 3) constraining transport time scales through the vadose zone in order to assess the impact of changes in agricultural nutrient management on underlying groundwater quality. In this study, we have investigated the isotopic composition of water-leachable nitrate extracted from sediment cores underlying three dairy operations in the southern San Joaquin Valley of California. One of the dairy operations is new (less than ten years old) and is sited on former range land; the other two operations are older (with one having been continuously operated for over a century). All use dairy wastewater for irrigation, and have vadose zones of 25-60 meters thickness developed in sedimentary sequences dominated by alluvial fan deposits. Sediment core samples from a UC-Davis monitor well drilling program were extracted with an equal amount of ultrapure water, and analyzed for nitrate isotopic composition using the denitrifying bacteria method at LLNL. The range in nitrate isotopic composition (?15N,air = 4.8 to 26.6 permil, ?18O,VSMOW = -0.3 to 16.2 permil) is large, comparable to isotopic compositions observed in dairy wastewater-impacted groundwaters (Singleton et al., 2007, ES&T 41:759-765), and varies from site to site. The range is the largest on the oldest operation (?15N = 5.2 to 26.6), and most tightly clustered on the youngest operation (?15N = 4.8 to 7.8). Leachable nitrate-?18O correlates with nitrate-?15N along a characteristic denitrification trend for individual cores. Leachable nitrate-?15N is not simply correlated with leachable nitrate concentration (which is generally high in shallow sediments and decreases with depth). In one core, the most enriched isotopic compositions are associated with the highest leachate nitrate concentrations. Observed nitrate isotopic compositions are consistent with nitrification of ammonium and mineralized organic N compounds from manure-rich wastewater, followed at some locations by denitrification. Sediment core patterns indicate that these processes can occur in the deep vadose zone. Profiles of leachable nitrate concentration and isotopic composition also differ significantly with respect to the duration of overlying dairy operations on a decadal timescale.

Esser, B. K.; Singleton, M. J.; Moran, J. E.; Roberts, S. K.; Barton, C. G.; Watanabe, N.; Harter, T.

2009-12-01

60

Detailed Structure of the Large Thrust Slice Zone in the Nankai Trough off Muroto  

NASA Astrophysics Data System (ADS)

A 3D seismic reflection data set were collected in the Nankai trough off cape Muroto in 1999. Pre-stack time migration has been perfomed on the 3D data. We will present on the detailed structure of the large thrust slice zone revealed from the 3D seismic reflection volume. The Large Thrust Slize Zone (LTSZ) with ˜25km length is located ˜40km landward from the deformation front, where the water depth shallows to 3000m from 4000m. The LTSZ is characterized by the imbricate structure which is also recognized in the frontal thrust zone, and thrust faults developed in the accretionary prism, which suggests that old accretionary prism in the LTSZ has been uplifted by the underplating and thrust faulting. Several faults can be traced in the LTSZ. These faults cut the well stratified imbricate thrust packages. Imbricate package beneath the upper slope area is thicker than that beneath the lower slope area. Strong flat reflectors were imaged beneath the base of the slope. These reflectors are terminated by a low angle fault landward. This setting of flat reflectors and a low angle fault is similar with that at the deformation front off Kumano area. The low angle fault might be a remnant decollement. The flat reflectors are clearly imaged in the southwest half of the 3D box, but not clear in the northeastern part. Low angle landward dipping reflectors (LA-LDRs) are imaged at the depth of 6.5-6.7s beneath the upper slope of whole 3D box. The LA-LDRs accompany with sigmoidal reflection events, which may represent a duplex structure. Some of the thrust faults take off from the landward end of LA-LDRs.

Nakamura, Y.; Bangs, N. L.; Gulick, S. P.; Moore, G. F.; Kuramoto, S.; Shipley, T. H.; Taira, A.

2003-12-01

61

Solar Sail - Fresnel Zone Plate Lens for a Large Space Based Telescope  

SciTech Connect

A Fresnel zone plate lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by missions to the asteroids, Pluto, Kuiper belt or the tort cloud and could also enable meaningful interstellar fly-by missions for laser propelled sails. This type of lens may also have some potential for laser communications and as a solar concentrator. The techniques for fabrication of meter size and larger Fresnel phase plate optics are under development at LLNL, and we are extending this technology to amplitude zone plates made from sail materials. Corrector optics to greatly extend the bandwidth of these Fresnel optics will be demonstrated in the future. This novel telescope concept will require new understanding of the fabrication, deployment and control of gossamer space structures. It will also require new materials technology for fabricating these optics and understanding their long term stability in a space environment.

Early, J T

2002-02-13

62

Recirculating induction accelerators for heavy ion fusion  

SciTech Connect

We have recently completed a two-year study of recirculating induction heavy-ion accelerators (recirculators) as low-cost drivers for inertial-fusion-energy power plants. We present here a summary of that study and other recent work on recirculators.

Barnard, J.J.; Deadrick, F. [Lawrence Livermore National Lab., CA (United States); Bangerter, R.O. [Lawrence Berkeley Lab., CA (United States)] [and others

1993-06-21

63

Ozonation followed by ultraviolet irradiation provides effective bacteria inactivation in a freshwater recirculating system  

Microsoft Academic Search

Recirculating aquaculture systems may require an internal disinfection process to control population growth of pathogens and heterotrophic bacteria. Ozonation and ultraviolet (UV) irradiation are two technologies that have been used to treat relatively large aquaculture flows, including flows within freshwater systems that recirculate water. The objective of the present study was to evaluate the effectiveness of ozone application alone or

Mark J. Sharrer; Steven T. Summerfelt

2007-01-01

64

Vertical stress transfer after large subduction zone earthquakes: 2007 Tocopilla /North Chile case study  

NASA Astrophysics Data System (ADS)

Large interplate subduction zone earthquakes occur on fault planes within the seismogenic interface which, in the case of Northern Chile, usually start to break at the down dip end of the coupled interface, propagating towards the trench. Although the rupture is a horizontally oriented process, some vertical connectivity between the interface and the upper crust should be expected. We study two clusters of aftershock seismicity from the Mw 7.7, 2007, Tocopilla earthquake in Northern Chile Both clusters seem to align along vertical profiles in the upper crust above the main shock rupture plane. The first cluster has a rather dissipative character at the up-dip limit of the rupture plane in the off-shore area around the Peninsula of Mejillones. It developed in the early stage of the aftershock sequence. The second cluster lies above the pronounced aftershock sequence of a secondary large Mw 6.9 slab-push event on 16th of December 2007. This type of compressional event can occur after large thrust earthquakes. A comparison of the epicentral distribution of the crustal events belonging to the aftershock sequence suggests a possible relation to the Cerro Fortuna Fault in the Coastal Cordillera which is a subsidiary fault strand of the major Atacama Fault Zone. We compute the Coulomb stress change on the respective faults of both clusters analyzed to see where slip is promoted or inhibited due to the slip on the subduction interface. We then combine these results with the spatial and temporal aftershock distribution, focal mechanism solutions, b-value mappings and geological evidences to understand the process behind the ascending seismicity clusters and their relation to the main shock of the major Tocopilla event.

Eggert, S.; Sobiesiak, M.; Victor, P.

2011-12-01

65

Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil.  

PubMed

Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecém) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. PMID:22306311

Buruaem, Lucas M; Hortellani, Marcos A; Sarkis, Jorge E; Costa-Lotufo, Leticia V; Abessa, Denis M S

2012-03-01

66

Preliminary Study on Emittance Growth in the LHEC Recirculating Linac  

SciTech Connect

In this paper, we estimate the emittance growth in the LHeC recirculating Linac, the lattice design of which is presented in another paper of IPAC10 proceedings. The possible sources for emittance growth included here are: energy spread from RF acceleration in the SRF (superconducting RF) linac together with large chromatic effects from the lattice, and synchrotron radiation (SR) fluctuations in the recirculating arcs. 6-D multi-particle tracking is launched to calculate the emittance from the statistical point of view. The simulation results are also compared with a theoretical estimation.

Sun, Yi-Peng; Adolphsen, Chris; /SLAC; Zimmermann, Frank; /CERN

2011-05-20

67

Large-scale modeling of reactive solute transport in fracture zones of granitic bedrocks  

NASA Astrophysics Data System (ADS)

Final disposal of high-level radioactive waste in deep repositories located in fractured granite formations is being considered by several countries. The assessment of the safety of such repositories requires using numerical models of groundwater flow, solute transport and chemical processes. These models are being developed from data and knowledge gained from in situ experiments such as the Redox Zone Experiment carried out at the underground laboratory of Äspö in Sweden. This experiment aimed at evaluating the effects of the construction of the access tunnel on the hydrogeological and hydrochemical conditions of a fracture zone intersected by the tunnel. Most chemical species showed dilution trends except for bicarbonate and sulphate which unexpectedly increased with time. Molinero and Samper [Molinero, J. and Samper, J. Groundwater flow and solute transport in fracture zones: an improved model for a large-scale field experiment at Äspö (Sweden). J. Hydraul. Res., 42, Extra Issue, 157-172] presented a two-dimensional water flow and solute transport finite element model which reproduced measured drawdowns and dilution curves of conservative species. Here we extend their model by using a reactive transport which accounts for aqueous complexation, acid-base, redox processes, dissolution-precipitation of calcite, quartz, hematite and pyrite, and cation exchange between Na + and Ca 2+. The model provides field-scale estimates of cation exchange capacity of the fracture zone and redox potential of groundwater recharge. It serves also to identify the mineral phases controlling the solubility of iron. In addition, the model is useful to test the relevance of several geochemical processes. Model results rule out calcite dissolution as the process causing the increase in bicarbonate concentration and reject the following possible sources of sulphate: (1) pyrite dissolution, (2) leaching of alkaline sulphate-rich waters from a nearby rock landfill and (3) dissolution of iron monosulphides contained in Baltic seafloor sediments. Based on these results, microbially mediated processes are postulated as the most likely hypothesis to explain the measured increase of dissolved bicarbonates and sulphates after tunnel construction.

Molinero, Jorge; Samper, Javier

2006-01-01

68

DOGBONE GEOMETRY FOR RECIRCULATING ACCELERATORS.  

SciTech Connect

Most scenarios for accelerating muons require recirculating acceleration. A racetrack shape for the accelerator requires particles with lower energy in early passes to traverse almost the same length of arc as particles with the highest energy. This extra arc length may lead to excess decays and excess cost. Changing the geometry to a dogbone shape, where there is a single linac and the beam turns completely around at the end of the linac, returning to the same end of the linac from which it exited, addresses this problem. In this design, the arc lengths can be proportional to the particle's momentum. This paper proposes an approximate cost model for a recirculating accelerator, attempts to make cost-optimized designs for both racetrack and dogbone geometries, and demonstrates that the dogbone geometry does appear to be more cost effective.

BERG,J.S.; JOHNSTONE,C.; SUMMERS,D.

2001-06-18

69

Toroidal transducer with two large focal zones for increasing the coagulated volume  

NASA Astrophysics Data System (ADS)

Toroidal HIFU transducers have been shown to generate large conical ablations (7 cm3 in 40 seconds). The focal zone is composed of a first ring-shaped focal zone and an overlap of ultrasound beams behind this first focus. A HIFU device has been developed on this principle to treat liver metastases during an open procedure. Although these large lesions contribute to reduce treatment time, it is still needed to juxtapose 4 to 9 single HIFU lesions to treat liver metastasis (2 cm in diameter) with safety margins. In this work, a different toroidal geometry was used. With this transducer, the overlap area is located between the probe and the focal ring. The objective was to use this transducer with electronic focusing in order to create a spherical shape lesion with sufficient volume for the destruction of a metastasis of 2 cm in diameter without any mechanical displacement. The operating frequency of the toroidal transducer was 2.5 MHz. The radius of curvature was 70 mm with a diameter of 67 mm. The focal ring had a radius of 15 mm. The overlap zone extent between 35 to 55 mm from the emitting surface. An ultrasound-imaging probe (working at 7.5 MHz) was placed in a central circular opening of 26 mm in the HIFU transducer and was aligned with the focal plane. The transducer was divided into 32 rings of 78 mm2. Using a 32 channels amplifier with a phase resolution of 1.4 degrees, it was possible to change the diameter (0 to 15 mm) and depth (45 to 85 mm) of the focus circle to maximize dimensions of the lesion. Tests were conducted in vitro, in bovine liver samples. This toroidal geometry and the use of electronic beam steering allow the creation of roughly spherical lesions (diameter of 47 mm, depth of 35 mm). This treatment was obtained in 6 minutes and 10 seconds without any mechanical displacement of the transducer. The lesions obtained were homogeneous and no untreated area was observed. In conclusion, these results indicate that the treatment of a liver metastasis up to 2 cm in diameter is conceivable with safety margins. An in vivo validation on porcine model is under progress.

Vincenot, J.; Melodelima, D.; Kocot, A.; Chavrier, F.; Chapelon, J. Y.

2012-11-01

70

Large-Scale Structures in the Zone of Avoidance: The Galactic Anticenter Region  

NASA Technical Reports Server (NTRS)

We have selected a sample of 876 galaxy candidates from the IRAS Point Source Catalog in the region of 2(exp h) < alpha < 10(exp h) and 0 deg < delta < 36 deg, which crosses the Galactic anticenter part of the Zone of Avoidance (ZOA) and includes most of the highly obscured Orion-Taurus complex region. We have identified galaxies among the candidate sources by attempting to detect the 21 cm H I line of those sources which were not known to be galaxies at the beginning of the survey. In this manner, we constructed a galaxy sample which is largely free from Galactic reddening. Of the 272 observed candidates, 89 were detected in the H I line up to a heliocentric velocity of v(sub h) approximately 16,000 km/s. The resulting galaxy sample of 717 galaxies is fairly complete (within about 10%) and uniform (within about 4%) in the part of the survey area 10 deg away from the Galactic plane and for velocities up to at least 9000 km/s. This provides, for the first time, a largely unbiased view on the large-scale structures in much of the survey area. Our main results are the following: (1) Several large voids are identified. In particular, a void between alpha approximately equals 3(sup h) and 4(sup h), up to v(sub h) approximately 6000 km/s, separates the Pisces-Perseus supercluster at alpha < 3(sup h) from structures at alpha > 4(sup h); and a "nearby void" occupies most of our survey area and reaches out to a redshift of nearly 3000 km/s. (2) We found no nearby galaxy concentration that could significantly contribute to the "Local Velocity Anomoly" (LVA), but a general excess of galaxies around v(sub h) approximately 5000 km/s in the survey area. (3) The contrast between the "Great Wall" at v(sub h) approximately 8500 km/s and the void in front of it appears to gradually diffuse out after it enters the Zone of Avoidance from the northern Galactic hemisphere. (4) Our data combined with other galaxy surveys in or near the Galactic anticenter part of the ZOA suggest that the main ridge of the Pisces-Perseus supercluster does not extend to Abell 569, a cluster in the northern Galactic hemisphere, and that the simple gravitational model consisting of the Local Void of Tully & Fisher, our nearby void, and Puppis and Fornax-Eridanus clusters would predict a LVA whose direction is probably too far away from that derived from observations.

Lu, Nanyao Y.; Freudling, Wolfram

1995-01-01

71

Large mid-Holocene and late Pleistocene earthquakes on the Oquirrh fault zone, Utah  

NASA Astrophysics Data System (ADS)

The Oquirrh fault zone is a range-front normal fault that bounds the east side of Tooele Valley and it has long been recognized as a potential source for large earthquakes that pose a significant hazard to population centers along the Wasatch Front in central Utah. Scarps of the Oquirrh fault zone offset the Provo shoreline of Lake Bonneville and previous studies of scarp morphology suggested that the most recent surface-faulting earthquake occurred between 9000 and 13,500 years ago. Based on a potential rupture length of 12 to 21 km from previous mapping, moment magnitude ( Mw) estimates for this event range from 6.3 to 6.6 In contrast, our results from detailed mapping and trench excavations at two sites indicate that the most-recent event actually occurred between 4300 and 6900 yr B.P. (4800 and 7900 cal B.P.) and net vertical displacements were 2.2 to 2.7 m, much larger than expected considering estimated rupture lengths for this event. Empirical relations between magnitude and displacement yield Mw 7.0 to 7.2. A few, short discontinuous fault scarps as far south as Stockton, Utah have been identified in a recent mapping investigation and our results suggest that they may be part of the Oquirrh fault zone, increasing the total fault length to 32 km. These results emphasize the importance of integrating stratigraphic and geomorphic information in fault investigations for earthquake hazard evaluations. At both the Big Canyon and Pole Canyon sites, trenches exposed faulted Lake Bonneville sediments and thick wedges of fault-scarp derived colluvium associated with the most-recent event. Bulk sediment samples from a faulted debris-flow deposit at the Big Canyon site yield radiocarbon ages of 7650 ± 90 yr B.P. and 6840 ± 100 yr B.P. (all lab errors are ±1 ?). A bulk sediment sample from unfaulted fluvial deposits that bury the fault scarp yield a radiocarbon age estimate of 4340 ± 60 yr B.P. Stratigraphic evidence for a pre-Bonneville lake cycle penultimate earthquake was exposed at the Pole Canyon site, and although displacement is not well constrained, the penultimate event colluvial wedge is comparable in size to the most-recent event wedges. Charcoal from a marsh deposit, which overlies the penultimate event colluvium and was deposited during the Bonneville lake cycle transgression, yields an AMS radiocarbon age of 20,370 ± 120 yr B.P. Multiple charcoal fragments from fluvial deposits faulted during the penultimate event yield an AMS radiocarbon age of 26,200 ± 200 yr B.P. Indirect stratigraphic evidence for an antepenultimate event was also exposed at Pole Canyon. Charcoal from fluvial sediments overlying the eroded free-face for this event yields an AMS age of 33,950 ± 1160 yr B.P., providing a minimum limiting age on the antepenultimate event. Ages for the past two events on the Oquirrh fault zone yield a recurrence interval of 13,300 to 22,100 radiocarbon years and estimated slip rates of 0.1 to 0.2 mm/yr. Temporal clustering of earthquakes on the nearby Wasatch fault zone in the late Holocene does not appear to have influenced activity on the Oquirrh fault zone. However, consistent with findings on the Wasatch fault zone and with some other Quaternary faults within the Bonneville basin, we found evidence for higher rates of activity during interpluvial periods than during the Bonneville lake cycle. If a causal relation between rates of strain release along faults and changes in loads imposed by the lake does exist, it may have implications for fault dips and mechanics. However, our data are only complete for one deep-lake cycle (the past 32,000 radiocarbon years), and whether this pattern persisted during the previous Cutler Dam and Little Valley deep-lake cycles is unknown.

Olig, Susan S.; Lund, William R.; Black, Bill D.

1994-08-01

72

Recirculation in multiple wave conversions  

SciTech Connect

A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.

Kaufman, A. N.; Brizard, A.J.; Kaufman, A.N.; Tracy, E.R.

2008-07-30

73

Large two-dimensional laboratory experiment with biodegradation of a PCE source zone  

Microsoft Academic Search

To investigate the effects of bioremediation on DNAPL source zones, we carried out an experiment in a two-dimensional tank filled with sand. A microbial assemblage originating from a contaminated field site was used for inoculation without enrichment. Injection of 250 ml PCE into the tank yielded a residual zone of PCE with a pool at the bottom. After this injection,

M. Langevoort; S. Hassanizadeh; P. Kleingeld; T. Heimovaara; T. Leijnse

2008-01-01

74

A Study of NO{sub x} Reduction by Fuel Injection Recirculation  

SciTech Connect

Flue-gas recirculation (FGR) is a well-known method used to control oxides of nitrogen (NO{sub X}) in industrial burner applications. Recent small- and large-scale experiments in natural-gas fired boilers have shown that introducing the recirculated flue gases with the fuel results in a much greater reduction in NO{sub X}, per unit mass of gas recirculated, in comparison to introducing the flue gases with the combustion air. That fuel injection recirculation (FIR) is more effective than windbox FGR is quite remarkable. At present, however, there is no definitive understanding of why FIR is more effective than conventional FGR. The objective of the present investigation is to ascertain whether or not chemical and/or molecular transport effects alone can explain the differences in NO{sub X} reduction observed between FIR and FGR by studying laminar diffusion flames. The purpose of studying laminar flames is to isolate chemical effects from the effects of turbulent mixing and heat transfer, which are inherent in practical boilers. Numerical simulations of H{sub 2}-air and CH{sub 4}-air counterflow diffusion flames using full kinetics were performed and NO{sub X} emission indices calculated for various conditions. Studies were conducted in which a N{sub 2} diluent was added either on the fuel- or air-side of the flame for conditions of either fixed initial velocities or fixed fuel mass flux. Results from these simulation studies indicate that a major factor in diluent effectiveness is the differential effect on flame zone residence times associated with fuel-side verses air-side dilution. Simulations in which flow velocities were fixed as diluent was added either to the air or fuel stream showed lower NO{sub X} emissions for air-side dilution; however, if instead, fuel mass fluxes were fixed as diluent was added, which results in an increase in the velocity of the streams, fuel-side dilution was more effective. These results were independent of whether H{sub 2} or Ch{sub 4} was used as the fuel.

Feese, J.J.; Turns, S.R.

1996-08-01

75

Turbocharged engine exhaust gas recirculation system  

Microsoft Academic Search

Improved exhaust gas recirculation systems for turbocharged gas engines that include an exhaust pipe, a turbocharger connected thereto, and a carburetor connected with a source of gas for the engine. The recirculation system includes an air conduit extending from the turbocharger compressor discharge to a venturi, an exhaust gas conduit that extends from a connection with the exhaust pipe between

Stachowicz

1984-01-01

76

Isotopic variation of fishes in freshwater and estuarine zones of a large subtropical coastal lagoon  

NASA Astrophysics Data System (ADS)

We used stable C and N isotope ratios of tissues from 29 fish species from a large subtropical lagoon in southern Brazil to examine spatial variability in isotopic composition and vertical trophic structure across freshwater and estuarine habitats. Nitrogen isotope ratios indicated a smooth gradation in trophic positions among species, with most fishes occupying the secondary and tertiary consumer level. Fish assemblages showed a significant shift in their carbon isotopic signatures between freshwater and estuarine sites. Depleted carbon signatures (from -24.7‰ to -17.8‰) were found in freshwater, whereas more enriched signatures (from -19.1‰ to -12.3‰) were obtained within the estuarine zone downstream. Based on our survey of the C 3 and C 4 plants and isotopic values for phytoplankton and benthic microalgae reported for ecosystems elsewhere, we hypothesized that the observed ?13C differences in the fish assemblage between freshwater and estuarine sites is due to a shift from assimilating organic matter ultimately derived from C 3 freshwater marsh vegetation and phytoplankton at the freshwater site ( ?13C ranging from -25‰ to -19‰), to C 4 salt-marsh (e.g. Spartina) and widgeon grass ( Ruppia maritima), benthic microalgae and marine phytoplankton at the estuarine sites (from -18‰ to -12‰). Our results suggested that fish assemblages are generally supported by autochthonous primary production. Freshwater fishes that likely were displaced downstream into the estuary during periods of high freshwater discharge had depleted ?13C values that were characteristic of the upper lagoon. These results suggest that spatial foodweb subsidies can occur within the lagoon.

Garcia, A. M.; Hoeinghaus, D. J.; Vieira, J. P.; Winemiller, K. O.

2007-07-01

77

Clinical, pathological and genetic features of primary mediastinal large B-cell lymphomas and mediastinal gray zone lymphomas in children  

PubMed Central

Background Primary mediastinal large B-cell lymphoma is a rare lymphoma accounting for no more than 3% of all B-cell lymphomas in children and adolescents. However, patients in this young age group with this lymphoma have the shortest event-free survival of patients with any B-cell lymphoma under current standard chemotherapy protocols. Lymphomas with features intermediate between primary mediastinal large B-cell lymphoma and classical Hodgkin’s lymphoma (mediastinal gray zone lymphomas) have been acknowledged in the latest World Health Organization classification. Recent studies suggest that mediastinal gray zone lymphomas have an aggressive clinical course whereas patients, at least adult ones, with primary mediastinal large B-cell lymphoma might respond very well to chemotherapy in combination with anti-CD20 antibody. Design and Methods We aimed to evaluate whether biological differences or so far unrecognized admixed mediastinal gray zone lymphomas might explain the relatively poor outcome of pediatric patients with apparent primary mediastinal large B-cell lymphoma. We, therefore, performed a retrospective histopathological, immunohistochemical and interphase cytogenetic analysis of 52 pediatric lymphomas. Results The childhood primary mediastinal large B-cell lymphomas (n=44) showed a similar pattern of histology, immunophenotype and gains at 9p (59%) and 2p (41%) as adult cases, as determined from published data. We identified only four so far unrecognized cases of mediastinal gray zone lymphoma among 52 lymphomas registered in previous trials. Conclusions Mediastinal gray zone lymphoma is very rare in children and adolescents. It does, therefore, seem unlikely that these lymphomas account for the unsatisfactory clinical results with current therapy protocols in pediatric patients. These data have major implications for the design of future treatment protocols for mediastinal lymphomas in children and adolescents.

Oschlies, Ilske; Burkhardt, Birgit; Salaverria, Itziar; Rosenwald, Andreas; d'Amore, Emanuele S.G.; Szczepanowski, Monika; Koch, Karoline; Hansmann, Martin L.; Stein, Harald; Moller, Peter; Reiter, Alfred; Zimmermann, Martin; Rosolen, Angelo; Siebert, Reiner; Jaffe, Elaine S.; Klapper, Wolfram

2011-01-01

78

Large-scale changes of the temperature frontal zones and regional features in heat transfer patterns based on SST data  

NASA Astrophysics Data System (ADS)

The intensity of heat transfer by currents influences on the location of energetically active zones in the ocean In such zones the hydrological parameter gradients increase which reveals the structure of frontal zones SST data isn t enough to determine the location of such zones In our work we calculate according to AVHRR MCSST data the temperature gradients in the ocean that show the large-scale changes of the temperature frontal zones TFZ for the 1982 -- 1986 average monthly and 1990 -- 2001 average weekly periods To study how the temperature frontal zones are connected with the regional heat patterns we use the data concerned with the space-time variability of SST gradients for separate Pacific regions In our case the focus is placed on the investigation of the connection between the formation of the El Ni v n o-Southern Oscillation South-East Pacific and the variability of the heat transfer near the shores of North-West Pacific For the investigation of the main factors influencing on the heat redistribution in the ocean and of the reasons for the large-scale changes in the TFZ structure we use a two-dimensional horizontal numerical model of heat transfer The model takes into consideration the current speed turbulent diffusion and solar radiation Besides the results were obtained concerning heat transformation in several regions of North and South Atlantic which had been caused by the large-scale changes in the TFZ structure The research results and model experiments allow to identify the time scale of the temperature field

Kartushinsky, A.; Shishkin, A.

79

Large two-dimensional laboratory experiment with biodegradation of a PCE source zone  

NASA Astrophysics Data System (ADS)

To investigate the effects of bioremediation on DNAPL source zones, we carried out an experiment in a two-dimensional tank filled with sand. A microbial assemblage originating from a contaminated field site was used for inoculation without enrichment. Injection of 250 ml PCE into the tank yielded a residual zone of PCE with a pool at the bottom. After this injection, the tank was continuously flushed with anaerobic water containing sufficient electron donor and various nutrients. Chlorinated ethenes analysis, microbial groups counting, and the visual observation of the colored PCE show that PCE was degraded in the source zone. Bio-enhanced dissolution occurred as cDCE concentrations were measured four times the solubility limit of PCE and because the PCE solubility limit in the source zone increased. Degradation of cDCE to VC and ethene occurred when PCE concentrations were low (<0.1 mM). After one year of experiment, approximately 135 ml of chlorinated ethenes were removed from the tank. PCE left in the tank was 90 ml and was only present in the pool. keywords: 2D tank experiment, PCE-DNAPL, reductive dechlorination, source zone, bio-enhanced dissolution, mobilization.

Langevoort, M.; Hassanizadeh, S.; Kleingeld, P.; Heimovaara, T.; Leijnse, T.

2008-12-01

80

Large-scale metal zoning in a late-Precambrian skarn-type mineralization, Wadi Kid, SE Sinai, Egypt  

NASA Astrophysics Data System (ADS)

A Precambrian skarn-type mineralization is recently discovered in the Wadi Kid area in southeast Sinai, Egypt. Two sulfide ore types define large scale metal zoning; Cu-Zn-Co in calc-silicate rocks and Zn-Pb-As-Ag in metapelites. The sulfides and host rocks underwent amphibolite facies metamorphism (2.1-4.2 kbar and 500-620 °C). Dating by the chemical Th-U-total Pb isochrone method yields an Th-Pb isochrone age of 660 ± 25 Ma for metamorphic monazite from metapelites. Overall structural and textural relationships of silicate and sulfide minerals favor syn-tectonic formation during granitoids emplacement in a continental margin setting. Large-scale metal zoning reflects variable distances from the causative pluton(s). The Wadi Kid area is highly prospective for Cu, Zn, Pb and Ag mineralization.

Helmy, H. M.; Shalaby, I. M.; Abdel Rahman, H. B.

2014-02-01

81

Large-Scale Physical Models of Thermal Remediation of DNAPL Source Zones in Aquitards.  

National Technical Information Service (NTIS)

In-Situ Thermal Remediation (ISTR) technologies are receiving increasing attention for remediation of dense non-aqueous phase liquid (DNAPL) source zones in soil and groundwater (GW), and are the subject of a number of related current projects funded by t...

R. S. Baker U. Hiester

2009-01-01

82

Application of X-ray mask fabrication technologies to high resolution, large diameter Ta Fresnel zone plates  

Microsoft Academic Search

High-resolution and large diameter condenser Fresnel zone plates were fabricated in a 0.35-?m-thick Ta layer on an SiN membrane. A newly developed conversion algorithm was applied where sub-field length and position are randamized in order to supress the evolution of small figures at pattern divided parts such as subfield boundaries in the conventional conversion algorithm. A single layer resist system

A. Ozawa; T. Tamamura; T. Ishii; H. Yoshihara; T. Kagoshima

1997-01-01

83

Recirculating cross-correlation detector  

DOEpatents

A digital cross-correlation detector is provided in which two time-varying signals are correlated by repetitively comparing data samples stored in digital form to detect correlation between the two signals. The signals are sampled at a selected rate converted to digital form, and stored in separate locations in separate memories. When the memories are filled, the data samples from each memory are first fed word-by-word through a multiplier and summing circuit and each result is compared to the last in a peak memory circuit and if larger than the last is retained in the peak memory. Then the address line to leading signal memory is offset by one byte to affect one sample period delay of a known amount in that memory and the data in the two memories are then multiplied word-by-word once again and summed. If a new result is larger than a former sum, it is saved in the peak memory together with the time delay. The recirculating process continues with the address of the one memory being offset one additional byte each cycle until the address is shifted through the length of the memory. The correlation between the two signals is indicated by the peak signal stored in the peak memory together with the delay time at which the peak occurred. The circuit is faster and considerably less expensive than comparable accuracy correlation detectors.

Andrews, W.H. Jr.; Roberts, M.J.

1985-01-18

84

High Power Picosecond Laser Pulse Recirculation.  

National Technical Information Service (NTIS)

We designed and constructed a nonlinear crystal-based short pulse recirculation cavity that traps the second harmonic of an incident high power laser. This scheme aims to increase the efficiency of Compton-scattering based light sources.

C. Brown D. Gibson F. Hartemann I. Jovanovic M. Y. Shverdin S. Anderson

2007-01-01

85

Combined heat transfer in floating zone growth of large silicon crystals with radiation on diffuse and specular surfaces  

NASA Astrophysics Data System (ADS)

Numerical analyses are conducted to investigate the combined heat transfer in floating zone growth of large Si crystals with needle-eye technique. The radiation element method, REM2, is employed to determine the radiative heat exchange, in which the view factors associated with the components in the float zone furnace and both the diffuse and specular reflection components are incorporated. The boundary element method and the finite difference method are adopted to calculate the electromagnetic field and the heat conduction, respectively. The effect of surface radiative characteristics of Si melt and crystal, i.e., diffuse and/or specular, is discussed in detail. It is found that the consideration of specular surfaces increases the Joulean heat and the radiative heat flux. The temperature fields are obtained for the cases of diffuse and specular, and the difference between the two different cases is obvious in the crystal and molten zone areas. The molten zone is enlarged when the specular surface is accounted for. The interface shape is examined and found to be in good agreement with the experiment.

Guo, Zhixiong; Maruyama, Shigenao; Togawa, Shinji

1998-01-01

86

Large-scale hydraulic structure of a seismogenic fault at 10 km depth (Gole Larghe Fault Zone, Italian Southern Alps)  

NASA Astrophysics Data System (ADS)

The definition of hydraulic properties of fault zones is a major issue in structural geology, seismology, and in several applications (hydrocarbons, hydrogeology, CO2 sequestration, etc.). The permeability of fault rocks can be measured in laboratory experiments, but its upscaling to large-scale structures is not straightforward. For instance, typical permeability of fine-grained fault rock samples is in the 10-18-10-20 m2 range, but, according to seismological estimates, the large-scale permeability of active fault zones can be as high as 10-10 m2. Solving this issue is difficult because in-situ measurements of large-scale permeability have been carried out just at relatively shallow depths - mainly in oil wells and exceptionally in active tectonic settings (e.g. SAFOD at 3 km), whilst deeper experiments have been performed only in the stable continental crust (e.g. KTB at 9 km). In this study, we apply discrete fracture-network (DFN) modelling techniques developed for shallow aquifers (mainly in nuclear waste storage projects like Yucca Mountain) and in the oil industry, in order to model the hydraulic structure of the Gole Larghe Fault Zone (GLFZ, Italian Southern Alps). This fault, now exposed in world-class glacier-polished outcrops, has been exhumed from ca. 8 km, where it was characterized by a well-documented seismic activity, but also by hydrous fluid flow evidenced by alteration halos and precipitation of hydrothermal minerals in veins and along cataclasites. The GLFZ does not show a classical seal structure that in other fault zones corresponds to a core zone characterized by fine-grained fault rocks. However, permeability is heterogeneous and the permeability tensor is strongly anisotropic due to fracture preferential orientation. We will show with numerical experiments that this hydraulic structure results in a channelized fluid flow (which is consistent with the observed hydrothermal alteration pattern). This results in a counterintuitive situation where a permeable fault zone act as a barrier to fluid flow.

Bistacchi, Andrea; Di Toro, Giulio; Smith, Steve; Mittempergher, Silvia; Garofalo, Paolo

2014-05-01

87

Weak Compliance Undermines the Success of No-Take Zones in a Large Government-Controlled Marine Protected Area  

PubMed Central

The effectiveness of marine protected areas depends largely on whether people comply with the rules. We quantified temporal changes in benthic composition, reef fish biomass, and fishing effort among marine park zones (including no-take areas) to assess levels of compliance following the 2005 rezoning of the government-controlled Karimunjawa National Park (KNP), Indonesia. Four years after the rezoning awareness of fishing regulations was high amongst local fishers, ranging from 79.5±7.9 (SE) % for spatial restrictions to 97.7±1.2% for bans on the use of poisons. Despite this high awareness and strong compliance with gear restrictions, compliance with spatial restrictions was weak. In the four years following the rezoning reef fish biomass declined across all zones within KNP, with >50% reduction within the no-take Core and Protection Zones. These declines were primarily driven by decreases in the biomass of groups targeted by local fishers; planktivores, herbivores, piscivores, and invertivores. These declines in fish biomass were not driven by changes in habitat quality; coral cover increased in all zones, possibly as a result of a shift in fishing gears from those which can damage reefs (i.e., nets) to those which cause little direct damage (i.e., handlines and spears). Direct observations of fishing activities in 2009 revealed there was limited variation in fishing effort between zones in which fishing was allowed or prohibited. The apparent willingness of the KNP communities to comply with gear restrictions, but not spatial restrictions is difficult to explain and highlights the complexities of the social and economic dynamics that influence the ecological success of marine protected areas. Clearly the increased and high awareness of fishery restrictions following the rezoning is a positive step. The challenge now is to understand and foster the conditions that may facilitate compliance with spatial restrictions within KNP and marine parks worldwide.

Campbell, Stuart J.; Hoey, Andrew S.; Maynard, Jeffrey; Kartawijaya, Tasrif; Cinner, Joshua; Graham, Nicholas A. J.; Baird, Andrew H.

2012-01-01

88

Longitudinal dynamics in high frequency ffag recirculating accelerators  

NASA Astrophysics Data System (ADS)

A recirculating accelerator accelerates the beam by passing through accelerating cavities multiple times. An FFAG recirculating accelerator uses a single arc to connect the linacs together, as opposed to multiple arcs for the different energies. For most scenarios using high-frequency RF, it is impractical to change the phase of the RF on each pass, at least for lower energy accelerators. Ideally, therefore, the WAG arc will be isochronous, so that the particles come back to the same phase (on-crest) on each linac pass. However, it is not possible to make the FFAG arcs isochronous (compared to the RF period) over a large energy range. This paper demonstrates that one can nonetheless make an WAG recirculating accelerator work. Given the arc's path length as a function of energy and the number of turns to accelerate for, one can find the minimum voltage (and corresponding initial conditions) required to accelerate a reference particle to the desired energy. I also briefly examine how the longitudinal acceptance varies with the number of turns that one accelerates.

Berg, S.

2002-04-01

89

A model for large-scale plastic yield of the Gorda deformation zone  

SciTech Connect

A solution satisfying both continuity and force balance for an elastoplastic Gorda plate in planar coordinates is presented. Continuity on a plane is used to approximate continuity on a spherical surface due to the small area under consideration. The zone of plastic yield vs the seismicity does not change much with fault strength along the Mendocino. Due to the nature of the deformation, the direction of maximum shear stress near the Mendocino triple junction is between 40 and 50 deg to the Mendocino transform in both cases, but curves sharply in the neighborhood of the transform if the fault is strong. It is concluded that the strength of the Mendocino relative to the lithosphere varied over time. Five million years ago a change in pole position increased convergence of the Blanco fracture zone and Mendocino transform, exponentially increasing brittle shear stresses across the fault. Between 2.47 Ma and 1.8 Ma the convergence stabilized, and the resistance to sliding along the transform decayed back to residual levels. The relative slip along the fault during this time was about 1 km. As a result of this history, previous models either for flexural-slip or for right-lateral shear will fit the deformation at different times. 35 refs.

Denlinger, R.P. (Hawaii Volcano Observatory, Hawaii Volcanoes National Park (United States))

1992-10-01

90

An explanation of large-scale coal and gas outbursts in underground coal mines: the effect of low-permeability zones on abnormally abundant gas  

NASA Astrophysics Data System (ADS)

Large-scale coal and gas outbursts post a risk of fatal disasters in underground mines. Large-scale outbursts (outburst of coal and rock greater than 500 t) in recent years in China indicate that there is abundant gas in areas of outbursts containing large amounts of potential energy. The adequate sealing properties of the roof and floor of a coal seam are required for local abundant gas around the site of an outburst, but an annular low-permeability zone in a coal seam, which prevents the loss by gas migration through the coal seam itself, is also required. The distribution of coal gas with this annular zone of low permeability is described, and it is proposed that the annular zone of low permeability creates conditions for confining the coal gas. The effect of this low-permeability zone on the gas distribution is analyzed after allowing for simplifications in the model. The results show that the permeability and length of the low-permeability zone have a great impact on the gas distribution. A steep gradient of gas pressure in the low-permeability zone and the high gas pressure in the abundant zone of gas can promote coal mass failure and coal wall deformation, thereby accelerating the coal and gas outburst. The high pressure gas in abundant zone of gas will lead to a large-scale outburst if an outburst occurs.

An, F. H.; Cheng, Y. P.

2013-09-01

91

Large-scale high-resolution seismic study in the western end of the Nankai seismogenic zone  

NASA Astrophysics Data System (ADS)

In the Nankai Trough subduction seismogenic zone, M8-class great earthquake area can be divided into three segments; they are source regions of the Nankai, Tonankai and presumed Tokai earthquakes. The Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. Possibility of a megathrust earthquake along the Nankai Trough from Tokai to the Hyuga-nada, east off the Kyushu Island, Japan, is recently pointed out. To understand rupture synchronization and segmentation of the Nankai megathrust earthquake, it is important to know the deep seismic image and activity in the Hyuga-nada, the western end of the Nankai seismogenic zone. To obtain the deep structure related to the rupture synchronization and segmentation in this region, the large-scale high-resolution wide-angle seismic study was conducted in Dec. 2008. In this study, 160 ocean bottom seismographs are deployed with a spacing of 5km along four seismic profiles, 830km in a total length. A tuned airgun system (7800 cu. in.) was shot every 200m along these profiles (Fig. 1). This research is part of ‘Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes’ funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. The subducting plate interface beneath coseismic slip zone of the 1968 event (Mw7.5) is the top of the oceanic crust contacting with the old accreted sediments. The young accretionary sediments (Vp<5km/s) above the subducting Philippine Sea plate reaches a maximum thickness of ~10km, and is widely distributed landward. In the northwestern half of the slip zone of the 1968 event, the young Accretionary sediments become thin abruptly. Figure 1: Location map of seismic survey

Nakanishi, A.; Kodaira, S.; Fujie, G.; Obana, K.; Takizawa, K.; Kashiwase, K.; Kaneda, Y.

2009-12-01

92

Deformations Associated With Large Interplate Earthquakes Along the Sumatra-Andaman Subduction Zone  

NASA Astrophysics Data System (ADS)

Since the occurrence of the 2004 Sumatra-Andaman earthquake (Mw9.2), the Sumatra-Andaman Subduction zone has attracted geophysicists' attention. We have been carrying on CGPS observation in Thailand and Myanmar to detect postseismic deformation following this gigantic event. Since CGPS on land is not enough to clarify the detailed image of postseismic deformation, we also make InSAR analyses in Andaman and Phuket Islands. On September 12, 2007, another Mw8.4 event occurred SW off Sumatra. We report deformations observed with GPS and SAR including co- and postseismic deformation following this event. We have analyzed CGPS data up to the end of 2007 and detected postseismic displacements all over the Indochina peninsula. Phuket, which suffered from about 26cm coseismic displacement, has shifted by 26cm southwestward till July, 2007. Postseismic transient is clearly recognized and already exceeds coseismic movements at remote sites such as Bangkok and Chiang Mai in Thailand. We processed ALOS/PALSAR data in Andaman and Phuket islands. No remarkable deformation is found in Andaman and Phuket Islands, since the operation period of ALOS/PALSAR is not long enough and the wavelength of postseismic deformation may be much longer than the swath. We try to synthesize the postseismic displacement using a 3-D viscoelastic FEM model. Its results imply that viscoelastic relaxation in mantle with a typical mantle viscosity may play an important role for the observed postseismic transients except during the first six month. An extremely low viscosity is not required beneath the Andaman Sea, though this back arc is now actively opening. Coseismic motion following the 2007 Sumatra event is detected north of Benkgulu on the coast of southern Sumatra with InSAR. The largest LOS displacement of about 35cm is observed 100km NW of Bengkulu. Coseismic westward displacements of 3.5cm from the 2007 Sumatra event are also observed at Singapore, whose epicentral distance is about 700km, with CGPS. The observed fringe can be simulated by a plane fault model gently dipping northeastward with a 10m slip. On the other hand, the maximum of postseismic LOS displacement is shifted about 50km south from the coseismic maximum and significant fringes are more localized than the coseismic ones. The shift and localization of fringe are difficult to understand with an afterslip on deeper extension of coseismic fault plane. There is a slight disturbance in fringes along the Sumatran fault in the coseismic image, although it might be a topographic error. We will continue monitoring crustal deformations in the Sumatra-Andaman subduction zone with GPS and InSAR in order to reveal stress transfer.

Hashimoto, M.; Fukushima, Y.; Katagi, T.; Hashizume, M.; Satomura, M.; Wu, P.; Kato, T.

2008-12-01

93

In situ treatment of VOCs by recirculation technologies  

SciTech Connect

Confronted with contaminated land from the world wars and the postwar industrialization period, German researchers and practicing professionals have worked to develop processes for effective environmental restoration. This presentation documents efforts by Oak Ridge National Laboratory (ORNL) researchers to (1) identify collaborators and German technologies exhibiting near-term potential for clean-up of volatile organic contaminated soil and groundwater at Department of Energy sites, (2) critically assess performance, and (3) inform interested agencies. The project was limited to identification and preliminary evaluation and included engineering computations, groundwater flow modeling, and treatment process modeling. Two processes were identified: (1) the vacuum vaporizer well/groundwater recirculation well and (2) the porous pipe/horizontal well (PP/HW). Both technologies induce a recirculation flow field in the aquifer and enable simultaneous down hole treatment of the aquifer and vadose zone. University of Karlsruhe researchers have demonstrated the UVB/GZB technology in shallow aquifers with moderately high saturated thickness and hydraulic conductivities. The PP/HW technology offers potential for VOC treatment in sites with thin aquifers or heterogeneities. This paper describes identified German technologies and includes critical evaluations of well performance, associated treatment processes, operating variables, and aquifer-well interactions.

Webb, O.F.; Siegrist, R.L.; Ally, M.R.; Sanford, W.E. [Oak Ridge National Lab., TN (United States); Kearl, P.M.; Zutman, J.L. [Oak Ridge National Lab., Grand Junction, CO (United States). Environmental Science Div.

1994-06-01

94

Numerical study of transient behaviour of molten zone during industrial FZ process for large silicon crystal growth  

NASA Astrophysics Data System (ADS)

The fully transient axisymmetric model has been developed for calculation of phase boundaries in large (up to 200 mm diameter) industrial floating zone (FZ) silicon single crystal growth with the needle-eye technique. The transient model is implemented in a specialized computer program. The model and program are based on a previously developed model and program for steady-state FZ process calculations. This transient approach allows studying of such substantially time-dependent process phases as the growth of the starting and ending cones of the crystal rod, which are particularly important for growth of large crystals in practice. Numerous calculations are carried out and the results for reducing crystal diameter during growth process are presented.

Rudevi?s, A.; Muižnieks, A.; Ratnieks, G.; Mühlbauer, A.; Wetzel, Th.

2004-05-01

95

Mittigating the effects of large subduction-zone earthquakes in Western Sumatra  

NASA Astrophysics Data System (ADS)

No giant earthquakes have struck the outer-arc islands of western Sumatra since the sequence of 1797, 1833 and 1861. Paleoseismic studies of coral microatolls reveal that failure of the subduction interface occurs in clusters of such earthquakes about every 230 years. Thus, the next such sequence may well be no more than a few decades away. In the meantime, GPS measurements and paleogeodetic observations show that the islands continue to submerge, dragged down by the downgoing oceanic slab, in preparation for the next failures of the subduction interface. Uplift of the islands and seafloor one to two meters during large events leads to large tsunamis and substantial changes in the coastal environments of the islands, including the seaward retreat of fringing reef, beach and mangrove environments. Having spent a decade characterizing the seismic history of western coastal Sumatra, we are now beginning to work with the inhabitants of the islands and the mainland coast to mitigate the associated hazards. Thus far, we have begun to creat and distribute posters and brochures aimed at educating the islanders about their natural tectonic environment and guiding them in preparing for future large earthquakes and tsunamis. We are also installing a continuous GPS network, in order to monitor ongoing strain accumulation and possible transients.

Sieh, K.; Stebbins, C.; Natawidjaja, D. H.; Suwargadi, B. W.

2004-12-01

96

Large multicellular filamentous bacteria under the oxygen minimum zone of the eastern South Pacific: a forgotten biosphere  

NASA Astrophysics Data System (ADS)

In the soft reduced sediments of the continental shelf, below the oxygen minimum zone (OMZ) of the eastern South Pacific (ESP), peculiar microbial communities have been disclosed which include a variety of large prokaryotes, protists and small metazoans. Dominant among the prokaryotes are large multi-cellular filamentous bacteria which, according to their size range, are roughly divided into megabacteria and macrobacteria. The former group is made up of a few species of Gamma Proteobacteria of the genera Thioploca and Beggiatoa and the second group includes a diversity of phenotypes. Protists include ciliates, flagellates, and foraminifers and the metazoans are mostly nematodes and small polychaetes. A significant similarity has been found in the exploitation of the area/volume relationship among these large bacteria and their fossil analog forms as described from pre-Cambrian rocks. For the same reason, the latter have mostly been referred to as algae or cyanobacteria in the literature. The presence of these seemingly ancient bacteria in the sediments of the oxygen minimum zones of the ESP, one of the most productive but also ecologically most inefficient marine ecosystems of the world, suggests that such setting must have prevailed throughout the geological history of the planet allowing for their survival and further that it might be considered an analog of Proterozoic ocean conditions. These non-cyanobacterial communities offer an alternative hypothesis to students of the evolution of life on Earth and may be of special interest to astrobiologists looking for life or traces of life in terrestrial or extraterrestrial environments since these do not necessarily imply a photosynthesis-based metabolism.

Gallardo, Victor Ariel; Espinoza, Carola

2007-10-01

97

ELECTROPHORESIS GEL BUFFER RECIRCULATOR FOR UNDER 20 DOLLARS  

EPA Science Inventory

Procedures requiring extended periods of electrophoresis frequently require recirculation of the get buffer in order to reduce gel artifacts. ere we describe a recirculation device which can be built inexpensively and will fit many different model get boxes....

98

40 CFR 1065.127 - Exhaust gas recirculation.  

Code of Federal Regulations, 2013 CFR

...Exhaust gas recirculation. Use the exhaust gas recirculation (EGR) system installed with the engine or one that represents a typical in-use configuration. This includes any applicable EGR cooling...

2013-07-01

99

Recirculating cooling water solute depletion models  

Microsoft Academic Search

Chromates have been used for years to inhibit copper corrosion in the plant Recirculating Cooling Water (RCW) system. However, chromates have become an environmental problem in recent years both in the chromate removal plant (X-616) operation and from cooling tower drift. In response to this concern, PORTS is replacing chromates with Betz Dianodic II, a combination of phosphates, BZT, and

1990-01-01

100

Recirculating natural convection solar energy collector  

Microsoft Academic Search

Recirculating natural convection solar energy collectors are disclosed. In one species of the invention, the collector comprises an insulated housing, a cover of glass or other suitable transparent material, a transparent plate of glass or other suitable material mounted inside said housing and spaced apart from the cover, a heat absorber mounted inside the housing and spaced apart from the

Soleau; B. S. Jr

1979-01-01

101

Spiral line recirculating induction accelerator (SLIA)  

NASA Astrophysics Data System (ADS)

The basic physical principles and issues relating to the design of the spiral line recirculating induction accelerator are examined with reference to the current experimental and theoretical programs. The discussion covers the major technical issues, accelerating cell design for SLIA, magnet design options for transition into and out of the accelerating section, and beam transport experiments.

Bailey, Vernon; Putnam, Sidney; Tiefenback, Michael; Nishimoto, Hart; Mondelli, Alfred

1989-07-01

102

Late Pleistocene and Holocene paleoseismology of an intraplate seismic zone in a large alluvial valley, the New Madrid seismic zone, Central USA  

Microsoft Academic Search

The New Madrid seismic zone (NMSZ) is an intraplate right-lateral strike-slip and thrust fault system contained mostly within the Mississippi Alluvial Valley. The most recent earthquake sequence in the zone occurred in 1811–1812 and had estimated moment magnitudes of 7–8 (e.g., [Johnston, A.C., 1996. Seismic moment assessment of stable continental earthquakes, Part 3: 1811–1812 New Madrid, 1886 Charleston, and 1755

Margaret J. Guccione

2005-01-01

103

Late Pleistocene and Holocene paleoseismology of an intraplate seismic zone in a large alluvial valley, the New Madrid seismic zone, Central USA  

Microsoft Academic Search

The New Madrid seismic zone (NMSZ) is an intraplate right-lateral strike-slip and thrust fault system contained mostly within the Mississippi Alluvial Valley. The most recent earthquake sequence in the zone occurred in 1811 1812 and had estimated moment magnitudes of 7 8 (e.g., [Johnston, A.C., 1996. Seismic moment assessment of stable continental earthquakes, Part 3: 1811 1812 New Madrid, 1886

Margaret J. Guccione

2005-01-01

104

Primary zone dynamics in a gas turbine combustor  

NASA Technical Reports Server (NTRS)

Fluid mechanical investigations simulating the flow in the primary zone of a gas turbine combustor are presented using three generic test rigs: (1) rotating pipe yielding a swirling jet of air; (2) primary zone model with a single swirler and various primary jet configurations, operated with air; and (3) two rectangular models of a (stretched-out) annular combustor with five swirlers in the backwall and with various primary jet configurations, one operated with air and the other with water. Concentration measurements are obtained using laser sheet imaging techniques and velocity measurements using a laser Doppler velocimeter. The results show recirculation zones, intense mixing, instabilities of the interacting jets and the presence of large random vortical motions. The flowfields are shown to exhibit bimodal behavior, have asymmetries despite symmetrical geometry and inlet conditions and display strong jet/swirler and swirler/swirler interactions.

Sullivan, J. P.; Barron, D.; Seal, M.; Morgan, D.; Murthy, S. N. B.

1989-01-01

105

River food web response to large-scale riparian zone manipulations.  

PubMed

Conservation programs often focus on select species, leading to management plans based on the autecology of the focal species, but multiple ecosystem components can be affected both by the environmental factors impacting, and the management targeting, focal species. These broader effects can have indirect impacts on target species through the web of interactions within ecosystems. For example, human activity can strongly alter riparian vegetation, potentially impacting both economically-important salmonids and their associated river food web. In an Olympic Peninsula river, Washington state, USA, replicated large-scale riparian vegetation manipulations implemented with the long-term (>40 yr) goal of improving salmon habitat did not affect water temperature, nutrient limitation or habitat characteristics, but reduced canopy cover, causing reduced energy input via leaf litter, increased incident solar radiation (UV and PAR) and increased algal production compared to controls. In response, benthic algae, most insect taxa, and juvenile salmonids increased in manipulated areas. Stable isotope analysis revealed a predominant contribution of algal-derived energy to salmonid diets in manipulated reaches. The experiment demonstrates that riparian management targeting salmonids strongly affects river food webs via changes in the energy base, illustrates how species-based management strategies can have unanticipated indirect effects on the target species via the associated food web, and supports ecosystem-based management approaches for restoring depleted salmonid stocks. PMID:23284786

Wootton, J Timothy

2012-01-01

106

Is the New Madrid Seismic Zone at risk for a large earthquake?  

NSDL National Science Digital Library

Students do background reading on the possible origins of intraplate seismicity and also read Nuttli's 1973 paper on the 1811-1812 New Madrid sequence. They construct frequency magnitude diagrams using data they acquire themselves from the openly archived University of Memphis catalog, Southern California Earthquake Center catalog, and USGS global catalog. They use these diagrams to estimate a recurrence interval for large magnitude earthquakes at the NMSZ. They then split into teams to read papers detailing campaign GPS surveys, paleoseismic measurements, and heat flow measurements. Each team is responsible for summarizing their set of papers for the other students. The culminating assignment is to update Gomberg and Schweig's 2002 USGS pamphlet "Earthquake hazard in the heart of the homeland" using scientific results that postdate the original pamphlet (including their own analysis). We also end with a "teaching and learning discussion" in which the students, who are usually high school teachers themselves, trade ideas about how they could repurpose parts of the lesson for use in their own classrooms. This activity gives students practice in data analysis and reading scientific papers, it shows them a few resources where they can find openly available data, and it gives them a chance to participate in the practice of science. Teaching Tips Adaptations that allow this activity to be successful in an online environment This lesson was constructed specifically for an online course and didn't exist beforehand. I think it could work in a face-to-face course, too. Elements of this activity that are most effective Students,especially ones who are not as literate with software plotting / analysis programs, find the problem set somewhat difficult because the datasets are large and I am asking them to collect the data themselves, then use it to make a second-order plot and analyze that, instead of just plotting "A" vs. "B" and analyzing it. That being said, I know that students are excited to be able to produce a plot themselves that exactly mimics one they can find in a published paper, and furthermore they are happy to find resources such as the USGS earthquake catalog that contain available real-time data. The part where they have to compare and contrast the strengths and weaknesses of each technique used to study the NMSZ (seismology, paleoseismology, GPS, etc) is important because they get a real sense of how different approaches are important to resolve a scientific debate. I know they are learning something when they get frustrated because there isn't an easy answer! Recommendations for other faculty adapting this activity to their own course: -Be prepared to help students get through the technical aspects of some of the scientific papers, especially if they are not used to reading scientific papers. When I pick the papers for them to read, I purposely pick ones that aren't too long (Science, Nature, GRL, etc) and I try to pick ones that came with a press release, "news and views" or similar, and then I tell the students to read the press release first and then the paper. -Be prepared to give students hints about counting and sorting data to make the frequency-magnitude diagrams because you'd rather lead them towards how to make the plots and then let them get on with the analysis as opposed to letting them get so frustrated with their lack of technical skills that they aren't interested in the science anymore. This exercise should be about seismology; it shouldn't be an excel tutorial! I have a little set of screen capture movie how-to hints under a hidden url, and when I can tell that a student is really suffering I reveal them.

Richardson, Eliza

107

Laser Doppler anemometer measurements of local fluid recirculation in model rod bundle assemblies. [PWR; BWR; LMFBR  

SciTech Connect

Experimental studies have been performed at Pacific Northwest Laboratories to investigate the thermal-hydraulic characteristics of model rod-bundle assemblies subjected to conditions representative of certain postulated accident or emergency shutdown scenarios. Studies related to both light water and liquid metal cooled nuclear reactors have been conducted. The bulk of the experimental data gathered during these studies has been laser Doppler anemometer (LDA) measurements of fluid velocity distributions within rod bundle assemblies. The objectives of the various tests were to extend the useful data base for evaluating thermal-hydraulic computer codes used for safety related reactor analysis. Of particular interest has been the ability of the LDA to detect and quantify areas of local fluid recirculation, such as have been found immediately downstream of simulated fuel ballooning blockages and in zones of large differential buoyancy forces for heated rod bundles operated with severe radial power skews. The non-intrusive nature of the LDA technique is considered important for such measurements of induced countercurrent flow.

Bates, J.M.; Creer, J.M.

1982-05-01

108

Recirculation Bubbles Measured at the Black Rock Forest Site in New York  

NASA Astrophysics Data System (ADS)

In conditions of low or moderate wind speed, large eddy structures - or recirculation bubbles - may form in the atmosphere over complex terrain. Recirculating air can have a significant influence on the exchange of moisture, energy and trace gases between the atmosphere and biosphere. Recirculation bubbles were predicted by an analytical model (Wang and Yi, 2012), and a numerical model (Xu and Yi, 2012). We conducted an experiment using two nearby towers in Black Rock Forest, New York, confirming the predicted phenomenon. Sensors were installed at five different levels on a tower at the top of a forested hill, and at five different levels at the middle of the eastern slope of the same hill. Each tower contained sensors both above and within the canopy measuring wind speed and direction, temperature, carbon dioxide, water vapor, relative humidity, net radiation, ground heat flux and other key parameters. Sensors collected data from 20 April to 9 June, 2013. The energy flux balances at the tops of the hilltop and midslope towers were approximately 75% and 85% of closure, respectively. The formation of recirculation bubbles was observed to be dependent on wind speed and direction, terrain features, temperature gradients and prevailing synoptic conditions. Carbon dioxide, water vapor and temperature profiles show that net ecosystem exchange is influenced by the presence or absence of recirculation. This research was supported by NSF Grants ATM-0930015 and PSC-CUNY ENHC-44-83.

Kutter, E.; Yi, C.; Hendrey, G. R.; Liu, H.; Eaton, T. T.; Ni-Meister, W.

2013-12-01

109

Explorer deformation zone: Evidence of a large shear zone and reorganization of the Pacific Juan de Fuca North American triple junction  

NASA Astrophysics Data System (ADS)

Recently collected multibeam bathymetry and hydroacoustic earthquake data are used to investigate the recent tectonics of the Explorer Juan de Fuca Ridge systems, the boundaries between the Pacific and northern Juan de Fuca plates. The bathymetric and seismic evidence presented is consistent with a zone of shear extending well south of the Sovanco Fracture Zone to include the Heck and Heckle seamounts, and potentially as far south as the Springfield Seamounts and Cobb offset along the Juan de Fuca Ridge. This indicates that the triple junction between the Pacific Juan de Fuca North American plates may be reorganizing southward to establish at the Cobb offset.

Dziak, Robert P.

2006-03-01

110

Large eddy simulation of soot evolution in an aircraft combustor  

NASA Astrophysics Data System (ADS)

An integrated kinetics-based Large Eddy Simulation (LES) approach for soot evolution in turbulent reacting flows is applied to the simulation of a Pratt & Whitney aircraft gas turbine combustor, and the results are analyzed to provide insights into the complex interactions of the hydrodynamics, mixing, chemistry, and soot. The integrated approach includes detailed models for soot, combustion, and the unresolved interactions between soot, chemistry, and turbulence. The soot model is based on the Hybrid Method of Moments and detailed descriptions of soot aggregates and the various physical and chemical processes governing their evolution. The detailed kinetics of jet fuel oxidation and soot precursor formation is described with the Radiation Flamelet/Progress Variable model, which has been modified to account for the removal of soot precursors from the gas-phase. The unclosed filtered quantities in the soot and combustion models, such as source terms, are closed with a novel presumed subfilter PDF approach that accounts for the high subfilter spatial intermittency of soot. For the combustor simulation, the integrated approach is combined with a Lagrangian parcel method for the liquid spray and state-of-the-art unstructured LES technology for complex geometries. Two overall fuel-to-air ratios are simulated to evaluate the ability of the model to make not only absolute predictions but also quantitative predictions of trends. The Pratt & Whitney combustor is a Rich-Quench-Lean combustor in which combustion first occurs in a fuel-rich primary zone characterized by a large recirculation zone. Dilution air is then added downstream of the recirculation zone, and combustion continues in a fuel-lean secondary zone. The simulations show that large quantities of soot are formed in the fuel-rich recirculation zone, and, furthermore, the overall fuel-to-air ratio dictates both the dominant soot growth process and the location of maximum soot volume fraction. At the higher fuel-to-air ratio, the maximum soot volume fraction is found inside the recirculation zone; at the lower fuel-to-air ratio, turbulent fluctuations in the mixture fraction promote the oxidation of soot inside the recirculation zone and suppress the accumulation of a large soot volume fraction. Downstream, soot exits the combustor in intermittent fuel-rich pockets that are not mixed during the injection of dilution air and subsequent secondary fuel-lean combustion. At the higher fuel-to-air ratio, the frequency of these fuel-rich pockets is increased, leading to higher soot emissions from the combustor. Quantitatively, the soot emissions from the combustor are overpredicted by about 50%, which is a substantial improvement over previous works utilizing RANS to predict such emissions. In addition, the ratio between the two fuel-to-air ratios predicted by LES compares very favorably with the experimental measurements. Furthermore, soot growth is dominated by an acetylene-based pathway rather than an aromatic-based pathway, which is usually the dominant mechanism in nonpremixed flames. This finding is the result of the interactions between the hydrodynamics, mixing, chemistry, and soot in the recirculation zone and the resulting residence times of soot at various mixture fractions (compositions), which are not the same in this complex recirculating flow as in nonpremixed jet flames.

Mueller, Michael E.; Pitsch, Heinz

2013-11-01

111

Re-circulating linac vacuum system  

SciTech Connect

The vacuum system for a proposed 2.5 GeV, 10{Mu}A recirculating linac synchrotron light source [1] is readily achievable with conventional vacuum hardware and established fabrication processes. Some of the difficult technical challenges associated with synchrotron light source storage rings are sidestepped by the relatively low beam current and short beam lifetime requirements of a re-circulating linac. This minimal lifetime requirement leads directly to relatively high limits on the background gas pressure through much of the facility. The 10{Mu}A average beam current produces very little synchrotron radiation induced gas desorption and thus the need for an ante-chamber in the vacuum chamber is eliminated. In the arc bend magnets, and the insertion devices, the vacuum chamber dimensions can be selected to balance the coherent synchrotron radiation and resistive wall wakefield effects, while maintaining the modest limits on the gas pressure and minimal outgassing.

Wells, Russell P.; Corlett, John N.; Zholents, Alexander A.

2003-05-09

112

Preoperational test report, recirculation condenser cooling systems  

SciTech Connect

This represents a preoperational test report for Recirculation Condenser Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The four system provide condenser cooling water for vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102. Each system consists of a valved piping loop, a pair of redundant recirculation pumps, a closed-loop evaporative cooling tower, and supporting instrumentation; equipment is located outside the farm on concrete slabs. Piping is routed to the each ventilation condenser inside the farm via below-grade concrete trenches. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-04

113

Multiple trophic levels fueled by recirculation in the Columbia River plume  

Microsoft Academic Search

Large rivers represent gateways for the transport of terrigenous and anthropogenic material to the coastal ocean. Here we document a ?700 km2 recirculation or bulge associated with the Columbia River plume that retains recently discharged river water sufficiently to create a regional bioreactor. Fueled by a fluvial nitrate source, this feature stimulated growth across three trophic levels and may buffer

Raphael M. Kudela; Alexander R. Horner-Devine; Neil S. Banas; Barbara M. Hickey; Tawnya D. Peterson; Ryan M. McCabe; Evelyn J. Lessard; Elizabeth Frame; Kenneth W. Bruland; David A. Jay; Jay O. Peterson; William T. Peterson; P. Michael Kosro; Sherry L. Palacios; Maeve C. Lohan; Edward P. Dever

2010-01-01

114

Breathing of a coral cay: Tracing tidally driven seawater recirculation in permeable coral reef sediments  

Microsoft Academic Search

Coral reefs are characterized by high gross productivity in spite of low nutrient concentrations. This apparent paradox may be partially reconciled if seawater recirculation in permeable sediments over large (meters) and long (hours to days) scales is an important source of recycled nitrogen and phosphorus to coral reefs. In this paper we use radon (222Rn, a natural tracer) to quantify

Isaac R. Santos; Dirk Erler; Douglas Tait; Bradley D. Eyre

2010-01-01

115

Recirculation as a possible microbial control strategy in the production of marine larvae  

Microsoft Academic Search

Marine hatcheries represent high value, low waste systems for larvae that are sensitive to general infections by opportunistic bacteria. In intensive cultivation several procedures destabilise the microbial community of the rearing water and favour growth of potentially harmful microbes. Recirculation aquaculture systems (RASs) have properties that may contribute to microbial stabilisation, including long water retention time and a large surface

Kari J. K. Attramadal; Ingrid Salvesen; Renyu Xue; Gunvor Øie; Trond R. Størseth; Olav Vadstein; Yngvar Olsen

116

Numerical computations of swirling recirculating flow  

NASA Technical Reports Server (NTRS)

Swirling, recirculating, nonreacting flows were computed using a 2D elliptic program consisting of three tasks. The computations in Task 1 and 2 were made using an independent analysis for the two coaxial swirling flows. The Task 2 computations were made using the measured profiles of the mixing region. In Task 3, a modified 2D elliptic program was employed to include the effects of interaction between the inner and outer streams.

Srinivasan, R.; Mongia, H. C.

1980-01-01

117

Exhaust gas recirculation system for diesel engine  

SciTech Connect

An exhaust gas recirculation control system calculates a target EGR ratio value based upon engine operating parameters and maintains the EGR ratio at the target EGR ratio value. Each time the vehicle travels a predetermined distance, the control system calculates an actual EGR ratio value and corrects the target EGR ratio value to reduce a deviation between the target and actual EGR ratio values to zero.

Masaki, K.; Yasuhara, S.

1984-02-28

118

High Power Picosecond Laser Pulse Recirculation  

SciTech Connect

We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

2010-04-12

119

Development of large-field high-resolution hard x-ray imaging microscopy and microtomography with Fresnel zone plate objective  

NASA Astrophysics Data System (ADS)

A hard x-ray imaging microscope system of high spatial resolution and large field of view (FOV) has been developed at the beamline 37 XU of SPring-8. By utilizing the 30 m-long experimental station, large magnification can be attained with a large diameter Fresnel zone plate (FZP) objective. Some configurations of microscope systems were tested. In a typical condition, a magnification of 133 and a FOV of 123 ?m are attained using a FZP with a diameter of 310 ?m and an outermost zone width of 100 nm, and the spatial resolution evaluated by observing resolution test chart is 160 nm in full pitch of periodic object with an exposure time of 1 s. When a FZP with an outermost zone width of 50 nm is used, a spatial resolution better than 100 nm is achieved. Phase-contrast imaging by Zernike's method was also tested, and three dimensional measurement by computer tomography (CT) method was also carried out.

Suzuki, Yoshio; Takeuchi, Akihisa; Terada, Yasuko; Uesugi, Kentaro; Tamura, Shigeharu

2013-09-01

120

Estimation of Recurrence Interval of Large Earthquakes on the Central Longmen Shan Fault Zone Based on Seismic Moment Accumulation/Release Model  

PubMed Central

Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard. The 2008 Wenchuan earthquake (Mw 7.9) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault (YBF) and the Guanxian-Jiangyou fault (GJF). However, there is a considerable discrepancy among recurrence intervals of large earthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results. Post-seismic trenches showed that the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake, suggesting a characteristic earthquake model. In this paper, we use the published seismogenic model of the 2008 earthquake based on Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic moment accumulation/release model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone. Our results show that the seismogenic zone accommodates a moment rate of (2.7?±?0.3)?×?1017?N?m/yr, and a recurrence interval of 3900?±?400?yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake. This study provides a preferred interval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region.

Zhang, Shimin

2013-01-01

121

Variations of mesoscale and large-scale sea ice morphology in the 1984 Marginal Ice Zone Experiment as observed by microwave remote sensing  

NASA Technical Reports Server (NTRS)

The data acquired during the summer 1984 Marginal Ice Zone Experiment in the Fram Strait-Greenland Sea marginal ice zone, using airborne active and passive microwave sensors and the Nimbus 7 SMMR, were analyzed to compile a sequential description of the mesoscale and large-scale ice morphology variations during the period of June 6 - July 16, 1984. Throughout the experiment, the long ice edge between northwest Svalbard and central Greenland meandered; eddies were repeatedly formed, moved, and disappeared but the ice edge remained within a 100-km-wide zone. The ice pack behind this alternately diffuse and compact edge underwent rapid and pronounced variations in ice concentration over a 200-km-wide zone. The high-resolution ice concentration distributions obtained in the aircraft images agree well with the low-resolution distributions of SMMR images.

Campbell, W. J.; Josberger, E. G.; Gloersen, P.; Johannessen, O. M.; Guest, P. S.

1987-01-01

122

Bathymetry-Density Interaction as a Driver for Seawater Recirculation in Submarine Groundwater Discharge  

NASA Astrophysics Data System (ADS)

A new mechanism for shallow saltwater recirculation as a component of submarine groundwater discharge (SGD) in coastal areas is proposed and evaluated. The proposed process occurs as a result of the interaction between bedform topography and buoyancy forces without requiring transient forcing (e.g., tides or waves) or currents over the bedform. Under hydrostatic seawater, the equivalent freshwater head is greatest on the seabed surface at the troughs of the bedform and lowest at the crest. In this mechanism, the inverted salinity (and density) profile in the presence of both a bedform on the seafloor and upward flow of fresher groundwater from depth induces a downward flow of saline porewater under the troughs and upward flow under the adjacent crest of the bedform. The magnitude and occurrence of the mechanism were evaluated and tested using the SEAWAT model. The results indicate that this mechanism could drive seawater recirculation and contribute 20 to 30 percent of local SGD under a range of realistic conditions. Bedform shape, hydraulic conductivity, hydraulic head and salinity at depth in the porous media, aquifer thickness, effective porosity, and hydrodynamic dispersion are among the factors that control the occurrence and magnitude of the recirculation of seawater, though the upward flux of fresher water is a dominant control. The hydraulic head at depth generally decreases with distance offshore as the head dissipates with the upward flow and discharge of the deeper fresher groundwater. Thus, one might anticipate the occurrence of a banded pattern—approximately parallel to the shoreline—of saltwater recirculation due to topographic-density interaction. Close to shore, the underlying head might be so large as to preclude saltwater recirculation, and far offshore fresher groundwater at depth may be absent or the head might be so small as to preclude upwards flow of deeper groundwater, thereby also eliminating the saltwater recirculation due to topographic-density interaction.

Konikow, L. F.; Akhavan, M.; Sawyer, A. H.; Michael, H. A.; Langevin, C. D.

2012-12-01

123

Impact of nitrate-enhanced leachate recirculation on gaseous releases from a landfill bioreactor cell.  

PubMed

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N(2)O emissions. During several weeks, we monitored gas concentrations in the landfill gas collection system as well as surface gas releases with a series of seven static chambers. These devices were directly connected to a gas chromatograph coupled to a flame ionisation detector and an electron capture detector (GC-FID/ECD) placed directly on the field. Measurements were performed before, during and after recirculation of raw leachate and nitrate-enhanced leachate. Raw leachate recirculation did not have a significant effect on the biogas concentrations (CO(2), CH(4) and N(2)O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N(2)O concentrations in the gas collected from the recirculation trench (100-fold increase from 0.2 ppm to 23 ppm). In the common gas collection system however, this N(2)O increase was no more detectable because of dilution by gas coming from other cells or ambient air intrusion. Surface releases through the temporary cover were characterized by a large spatial and temporal variability. One automated chamber gave limited standard errors over each experimental period for N(2)O releases: 8.1 +/- 0.16 mg m(-2) d(-1) (n = 384), 4.2 +/- 0.14 mg m(-2) d(-1) (n = 132) and 1.9 +/- 0.10 mg m(-2) d(-1) (n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N(2)O gaseous surface releases and recirculation events were evidenced. Estimated N(2)O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection. PMID:19297142

Tallec, G; Bureau, C; Peu, P; Benoist, J C; Lemunier, M; Budka, A; Presse, D; Bouchez, T

2009-07-01

124

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

Code of Federal Regulations, 2011 CFR

...Protection, Captain of the Port Columbia River Zone 165.1318 Section 165.1318...Protection, Captain of the Port Columbia River Zone (a) Notice of enforcement or suspension...notice by the Captain of the Port Columbia River. Captain of the Port Columbia...

2011-07-01

125

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

Code of Federal Regulations, 2012 CFR

...Protection, Captain of the Port Columbia River Zone 165.1318 Section 165.1318...Protection, Captain of the Port Columbia River Zone (a) Notice of enforcement or suspension...notice by the Captain of the Port Columbia River. Captain of the Port Columbia...

2012-07-01

126

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

Code of Federal Regulations, 2013 CFR

...Protection, Captain of the Port Columbia River Zone. 165.1318 Section 165.1318...Protection, Captain of the Port Columbia River Zone. (a) Notice of enforcement or...notice by the Captain of the Port Columbia River. Captain of the Port Columbia...

2013-07-01

127

Exhaust gas recirculation system for an internal combustion engine  

DOEpatents

An exhaust gas recirculation system for an internal combustion engine comprises an exhaust driven turbocharger having a low pressure turbine outlet in fluid communication with an exhaust gas conduit. The turbocharger also includes a low pressure compressor intake and a high pressure compressor outlet in communication with an intake air conduit. An exhaust gas recirculation conduit fluidly communicates with the exhaust gas conduit to divert a portion of exhaust gas to a low pressure exhaust gas recirculation branch extending between the exhaust gas recirculation conduit and an engine intake system for delivery of exhaust gas thereto. A high pressure exhaust gas recirculation branch extends between the exhaust gas recirculation conduit and the compressor intake and delivers exhaust gas to the compressor for mixing with a compressed intake charge for delivery to the intake system.

Wu, Ko-Jen

2013-05-21

128

Late Pleistocene and Holocene paleoseismology of an intraplate seismic zone in a large alluvial valley, the New Madrid seismic zone, Central USA  

NASA Astrophysics Data System (ADS)

The New Madrid seismic zone (NMSZ) is an intraplate right-lateral strike-slip and thrust fault system contained mostly within the Mississippi Alluvial Valley. The most recent earthquake sequence in the zone occurred in 1811 1812 and had estimated moment magnitudes of 7 8 (e.g., [Johnston, A.C., 1996. Seismic moment assessment of stable continental earthquakes, Part 3: 1811 1812 New Madrid, 1886 Charleston, and 1755 Lisbon. Geophysical Journal International 126, 314 344; Johnston, A.C., Schweig III, E.S, 1996. The enigma of the New Madrid earthquakes of 1811 1812. Annual Reviews of Earth and Planetary Sciences 24, 339 384; Hough, S.E., Armbruster, J.G., Seeber, L., Hough, J.F., 2000. On the modified Mercalli intensities and magnitudes of the New Madrid earthquakes. Journal of Geophysical Research 105 (B10), 23,839 23,864; Tuttle, M.P., 2001. The use of liquefaction features in paleoseismology: Lessons learned in the New Madrid seismic zone, central United States. Journal of Seismology 5, 361 380]). Four earlier prehistoric earthquakes or earthquake sequences have been dated A.D. 1450 ± 150, 900 ± 100, 300 ± 200, and 2350 B.C. ± 200 years using paleoliquefaction features, particularly those associated with native American artifacts, and in some cases surface deformation ([Craven, J. A. 1995. Paleoseismology study in the New Madrid seismic zone using geological and archeological features to constrain ages of liquefaction deposits. M.S thesis, University of Memphis, Memphis, TN, U.S.A.; Tuttle, M.P., Lafferty III, R.H., Guccione, M.J., Schweig III, E.S., Lopinot, N., Cande, R., Dyer-Williams, K., Haynes, M., 1996. Use of archaeology to date liquefaction features and seismic events in the New Madrid seismic zone, central United States. Geoarchaeology 11, 451 480; Guccione, M.J., Mueller, K., Champion, J., Shepherd, S., Odhiambo, B., 2002b. Stream response to repeated co-seismic folding, Tiptonville dome, western Tennessee. Geomorphology 43(2002), 313 349; Tuttle, M.P., Schweig, E.S., Sims, J.D., Lafferty, R.H., Wolf, L.W., Haynes, M.L., 2002. The earthquake potential of the New Madrid seismic zone, Bulletin of the Seismological Society of America, v 92, n. 6, p. 2080 2089; Tuttle, M.P., Schweig III, E.S., Campbell, J., Thomas, P.M., Sims, J.D., Lafferty III, R.H., 2005. Evidence for New Madrid earthquakes in A.D. 300 and 2350 B.C. Seismological Research Letters 76, 489 501]). The two most recent prehistoric and the 2350 B.C. events were probably also earthquake sequences with approximately the same magnitude as the historic sequence. Surface deformation (faulting and folding) in an alluvial setting provides many examples of stream response to gradient changes that can also be used to date past earthquake events. Stream responses include changes in channel morphology, deviations in the channel path from the regional gradient, changes in the direction of flow, anomalous longitudinal profiles, and aggradation or incision of the channel ([Merritts, D., Hesterberg, T, 1994. Stream networks and long-term surface uplift in the New Madrid seismic zone. Science 265, 1081 1084.; Guccione, M.J., Mueller, K., Champion, J., Shepherd, S., Odhiambo, B., 2002b. Stream response to repeated co-seismic folding, Tiptonville dome, western Tennessee. Geomorphology 43 (2002), 313 349]). Uplift or depression of the floodplain affects the frequency of flooding and thus the thickness and style of vertical accretion or drowning of a meander scar to form a lake. Vegetation may experience trauma, mortality, and in some cases growth enhancement due to ground failure during the earthquake and hydrologic changes after the earthquake ([VanArdale, R.B., Stahle, D.W., Cleaveland, M.K., Guccione, M.J., 1998. Earthquake signals in tree-ring data from the New Madrid seismic zone and implications for paleoseismicity. Geology 26, 515 518]). Identification and dating these physical and biologic responses allows source areas to be identified and seismic events to be dated. Seven fault segments are recognized by microseismicity and geomorphology. Surface faulting

Guccione, Margaret J.

2005-10-01

129

Molecular adsorbent and re-circulating system.  

PubMed

The molecular adsorbent recirculating system (MARS) is a non-biological artificial liver support system. Used for almost a decade, there are only two randomized controlled trials on the efficacy of MARS till date. A number of uncontrolled studies have documented a marked improvement in the biochemical parameters of patients after MARS. Although MARS seems to be an effective and promising tool in the management of liver failure, its cost needs to be reduced to enable it use in a member of indications. PMID:15471317

Batra, Yogesh; Dutta, Amit Kumar; Dutta, Amitabh; Acharya, Subrat Kumar

2004-01-01

130

Fast response exhaust gas recirculation (EGR) system  

SciTech Connect

This patent describes an exhaust gas recirculation (EGR) control for an automotive type internal combustion engine. It comprises: a gas induction passage connected to the engine intake manifold at one end, an EGR passage connected at one end to exhaust gases from the engine combustion chamber, the other end of the induction passage being bifurcated to form ambient air and EGR branch passages, means connecting the ambient air branch passage to ambient air, means connecting the EGR branch passage to the other end of the EGR passage whereby ambient air and EGR gases combine to form a gas charge inducted into the engine.

Wade, W.R.

1990-05-15

131

In-tank recirculating arsenic treatment system  

DOEpatents

A low-cost, water treatment system and method for reducing arsenic contamination in small community water storage tanks. Arsenic is removed by using a submersible pump, sitting at the bottom of the tank, which continuously recirculates (at a low flow rate) arsenic-contaminated water through an attached and enclosed filter bed containing arsenic-sorbing media. The pump and treatment column can be either placed inside the tank (In-Tank) by manually-lowering through an access hole, or attached to the outside of the tank (Out-of-Tank), for easy replacement of the sorption media.

Brady, Patrick V. (Albuquerque, NM); Dwyer, Brian P. (Albuquerque, NM); Krumhansl, James L. (Albuquerque, NM); Chwirka, Joseph D. (Tijeras, NM)

2009-04-07

132

Geomechanical effects on CO{sub 2} leakage through fault zones during large-scale underground injection  

SciTech Connect

The importance of geomechanics—including the potential for faults to reactivate during large scale geologic carbon sequestration operations—has recently become more widely recognized. However, notwithstanding the potential for triggering notable (felt) seismic events, the potential for buoyancy-driven CO{sub 2} to reach potable groundwater and the ground surface is actually more important from public safety and storage-efficiency perspectives. In this context, this work extends the previous studies on the geomechanical modeling of fault responses during underground carbon dioxide injection, focusing on the short-term integrity of the sealing caprock, and hence on the potential for leakage of either brine or CO{sub 2} to reach the shallow groundwater aquifers during active injection. We consider stress/strain-dependent permeability and study the leakage through the fault zone as its permeability changes during a reactivation, also causing seismicity. We analyze several scenarios related to the volume of CO{sub 2} injected (and hence as a function of the overpressure), involving both minor and major faults, and analyze the profile risks of leakage for different stress/strain-permeability coupling functions. We conclude that whereas it is very difficult to predict how much fault permeability could change upon reactivation, this process can have a significant impact on the leakage rate. Moreover, our analysis shows that induced seismicity associated with fault reactivation may not necessarily open up a new flow path for leakage. Results show a poor correlation between magnitude and amount of fluid leakage, meaning that a single event is generally not enough to substantially change the permeability along the entire fault length. Consequently, even if some changes in permeability occur, this does not mean that the CO{sub 2} will migrate up along the entire fault, breaking through the caprock to enter the overlying aquifer.

Rinaldi, A.P.; Rutqvist, J.; Cappa, F.

2013-09-01

133

Maintenance of the intertropical convergence zones and the large-scale tropical circulation on a water-covered earth  

SciTech Connect

How the surface boundary heating (sea surface temperature) and cumulus adjustment process affect the location, structure, energetics, and dynamics of the intertropical convergence zones (ITCZs) is investigated. A series of experiments is performed with a general circulation model where the lower boundary is specified to be water at a fixed sea surface temperature (SST), an aqua planet. All experiments are run using equinoctal insolation with no longitudinal variation in SST. Two different convective parameterization schemes (Kuo and moist convective adjustment) and several different zonally symmetric SST distributions are used in these experiments. The location of the ITCZ is found to be sensitive to the convective parameterization scheme and the SST distribution. The model with the moist convective adjustment scheme produces an ITCZ over the tropical SST maximum, even under conditions where the SST gradient is weak. By contrast, the model with the Kuo convective parameterization is not as sensitive to SST distribution: the model with the Kuo scheme yields two ITCZs straddling the equator at approximately 7[degrees]latitude for a wide variety of SST distributions, including when the warmest water is located on the equator. The location of the ITCZ affects the structure and strength of both the time-mean Hadley cells and the subtropical jets. Furthermore, the equatorial wave spectrum is strongly influenced by the type of cumulus parameterization scheme used. The [open quotes]convective characteristics[close quotes] for each parameterization scheme are presented in detail to elucidate the influence of the large-scale environment on convection. 52 refs., 15 figs., 2 tabs.

Hess, P.G.; Rasch, P.J. (National Center for Atmospheric Research, Boulder, CO (United States)); Battisti, D.S. (Univ. of Washington, Seattle (United States))

1993-03-01

134

A large-scale experiment on mass transfer of trichloroethylene from the unsaturated zone of a sandy aquifer to its interfaces  

NASA Astrophysics Data System (ADS)

A large-scale experiment was conducted to investigate the transport of trichloroethylene (TCE) vapors in the unsaturated zone and to determine the mass transfer to the groundwater and the atmosphere. The experiment involved injection of 5 l of TCE in the unsaturated zone under controlled conditions, with multidepth sampling of gas and water through the unsaturated zone and across the capillary zone into underlying groundwater. The mass transfer of TCE vapors from the vadose zone to the atmosphere was quantified using a vertical flux chamber. A special soil water sampler was used to monitor transport across the capillary fringe. Experimental data indicated that TCE in the unsaturated zone was mainly transported to the atmosphere and this exchange reduced significantly the potential for groundwater pollution. The maximum measured TCE flux to the atmosphere was about 3 g/m 2/day. Observed and calculated fluxes based on vertical TCE vapor concentration gradients and Fick's law were in good agreement. This confirms that TCE vapor transport under the experimental conditions was governed essentially by molecular diffusion. TCE vapors also caused a lower, but significant contamination of the underlying groundwater by dispersion across the capillary fringe with a corresponding maximum flux of about 0.1 g/m 2/day. This mass transfer to groundwater is partly uncertain due to an inadvertent entry of some nonaqueous phase liquid (NAPL) from the source area into the saturated zone. Application of an analytical solution to estimate the TCE flux from the unsaturated zone to the groundwater indicated that this phenomenon is not only influenced by molecular diffusion but also by vertical dispersion. The mass balance indicates that, under the given experimental conditions (e.g. proximity of the source emplacement relative to the soil surface, relatively high permeable porous medium), nearly 95% of the initial TCE mass was transferred to the atmosphere.

Jellali, Salah; Benremita, Hocine; Muntzer, Paul; Razakarisoa, Olivier; Schäfer, Gerhard

2003-01-01

135

A large-scale experiment on mass transfer of trichloroethylene from the unsaturated zone of a sandy aquifer to its interfaces.  

PubMed

A large-scale experiment was conducted to investigate the transport of trichloroethylene (TCE) vapors in the unsaturated zone and to determine the mass transfer to the groundwater and the atmosphere. The experiment involved injection of 5 1 of TCE in the unsaturated zone under controlled conditions, with multidepth sampling of gas and water through the unsaturated zone and across the capillary zone into underlying groundwater. The mass transfer of TCE vapors from the vadose zone to the atmosphere was quantified using a vertical flux chamber. A special soil water sampler was used to monitor transport across the capillary fringe. Experimental data indicated that TCE in the unsaturated zone was mainly transported to the atmosphere and this exchange reduced significantly the potential for groundwater pollution. The maximum measured TCE flux to the atmosphere was about 3 g/m(2)/day. Observed and calculated fluxes based on vertical TCE vapor concentration gradients and Fick's law were in good agreement. This confirms that TCE vapor transport under the experimental conditions was governed essentially by molecular diffusion. TCE vapors also caused a lower, but significant contamination of the underlying groundwater by dispersion across the capillary fringe with a corresponding maximum flux of about 0.1 g/m(2)/day. This mass transfer to groundwater is partly uncertain due to an inadvertent entry of some nonaqueous phase liquid (NAPL) from the source area into the saturated zone. Application of an analytical solution to estimate the TCE flux from the unsaturated zone to the groundwater indicated that this phenomenon is not only influenced by molecular diffusion but also by vertical dispersion. The mass balance indicates that, under the given experimental conditions (e.g. proximity of the source emplacement relative to the soil surface, relatively high permeable porous medium), nearly 95% of the initial TCE mass was transferred to the atmosphere. PMID:12498573

Jellali, Salah; Benremita, Hocine; Muntzer, Paul; Razakarisoa, Olivier; Schäfer, Gerhard

2003-01-01

136

Regional extent of the large coseismic slip zone of the 2011 Mw 9.0 Tohoku-Oki Earthquake delineated by on-fault aftershocks  

NASA Astrophysics Data System (ADS)

In order to image the rupture process of the 2011 Tohoku-Oki earthquake, many fault source models have recently been developed following this giant earthquake by inverting for slip on the fault plane, based on a variety of collected data, strong ground motion, geodetic, and tsunami recordings. Most of these studies suggest that the area of largest coseismic slip (~30-80 m) was located near the mainshock hypocenter, extending eastward to a location near the Japan Trench axis. However, the estimated outer edges of the large-slip zone are substantially different between these models, due to the currently limited spatial resolution of slip along the fault. Consequently, there are insufficient constraints as to how far the large-slip zone extended along the plate interface during the mainshock rupture. Here we delineate the outer edge of this large-slip zone in detail, by applying a spatial correlation between on-fault aftershocks and slip to the Tohoku aftershock sequence. We focus on the sharp density contrast observed for interplate, repeating, and down-dip compressional earthquakes induced by the Tohoku-Oki mainshock. The seismicity rate of interplate earthquakes changed significantly after the mainshock, probably as a result of stress perturbations by the large-slip, and here we use this information as qualitative constraints in constructing our model. The model that we present for the large-slip zone incorporates the main features of previously proposed fault source models, and also the observed fine-scale heterogeneities of fault slip associated with this event. It is important to highlight that the outer edge of this large-slip zone shows a remarkably complex shape. In particular, it is narrow and elongate southward along the ~35 km iso-depth contour of the plate boundary offshore of Fukushima and Ibaraki. This southward elongate slip zone corresponds to down-dip regions that appear to have produced higher relative levels of short-period seismic radiation. We explore whether the coseismic geodetic data could be fit with a fault source model in which slip is confined to the large-slip zone delineated by on-fault aftershocks, described above. We impose zero slip outside the large-slip zone assuming a nonplanar fault plane along the plate boundary. The slip model has a moment magnitude of 9.0. In addition to the largest coseismic slip area off Miyagi, an isolated high slip region is imaged off Ibaraki. Repeating earthquakes that occur along the plate boundary are likely an indication of post-seismic transient afterslip, which could be described in terms of a brittle creep rheology. Because most of the repeating earthquakes coincided closely with the dense concentrations of on-fault aftershocks, it is likely that the stress increase generated by abrupt slip termination of the Tohoku-Oki mainshock triggered the post-seismic transient afterslip event on the outside of the large-slip zone. Beneath the Kanto district, the distribution of interplate earthquakes including repeating earthquakes dissipates across the northern reaches of a contact zone where two oceanic plates are subducting. Because the post-seismic slip has occurred beneath the Kanto, it is important to monitor the seismicity using a dense seismic array operated by the Special project for reducing vulnerability for urban mega earthquake disasters.

Kato, A.; Igarashi, T.; Fukuda, J.

2012-12-01

137

Recirculating linac free-electron laser driver  

NASA Astrophysics Data System (ADS)

This paper describes the design of a recirculating linac as a driver for the suite of seeded free-electron lasers (FELs) proposed in the UK New Light Source (NLS) project. The choice of superconducting technology for NLS is required in order to deliver bunches at high repetition rates up to 1 MHz. This raises the question of whether a shorter linac in recirculating mode can deliver the beam quality required for seeded FELs. To design such a facility, careful layout choices and optimizations must be made to ensure emittance growth is minimized. Effects leading to emittance dilution include chromatic transport terms, incoherent and coherent synchrotron radiation. The design outlined here is based on a modular philosophy to separate beam injection and extraction from a three stage compression scheme. The design uses many novel design concepts and optimizations to deliver the necessary high peak currents while preserving beam quality for seeded FELs. Start-to-end simulations including the FELs show that the necessary pulse coherence and output power can be provided from the beam thus generated.

Williams, Peter H.; Angal-Kalinin, Deepa; Dunning, David J.; Jones, James K.; Thompson, Neil R.

2011-05-01

138

High speed exhaust gas recirculation valve  

SciTech Connect

In order to minimize pollutants such as Nox, internal combustion engines typically include an exhaust gas recirculation (EGR) valve that can be used to redirect a portion of exhaust gases to an intake conduit, such as an intake manifold, so that the redirected exhaust gases will be recycled. It is desirable to have an EGR valve with fast-acting capabilities, and it is also desirable to have the EGR valve take up as little space as possible. An exhaust gas recirculation valve is provided that includes an exhaust passage tube, a valve element pivotally mounted within the exhaust passage tube, a linear actuator; and a gear train. The gear train includes a rack gear operatively connected to the linear actuator, and at least one rotatable gear meshing with the rack gear and operatively connected to the valve element to cause rotation of the valve element upon actuation of the linear actuator. The apparatus provides a highly compact package having a high-speed valve actuation capability.

Fensom, Rod (Peterborough, GB); Kidder, David J. (Peterborough, GB)

2005-01-18

139

Incremental growth of a large volume, chemically zoned magma body: a study of the tephra sequence beneath the Rainier Mesa ash flow sheet of the Timber Mountain Tuff  

NASA Astrophysics Data System (ADS)

The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2 — one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55 66% SiO2) and a high silica (>66% SiO2) trend. Ninety per cent of the Rainier Mesa sheet occurs in the high silica trend. Immediately beneath the Rainier Mesa sheet is a thick tephra sequence. The chemical variation of this sequence is nearly equivalent to the high silica portion of the Rainier Mesa ash-flow sheet (about 66 78% SiO2). Throughout the tephra sequence numerous small ash-flow layers occur, and each ash-flow layer is chemically zoned from more evolved at the base to less evolved at the top. This is consistent with having been erupted from a zoned magma body. The lowest silica tephra units are at the base of the sequence and the highest silica units are at the top — that is, the large-scale chemical trend of the entire sequence is opposite to that of the individual ash-flow layers. These ash-flow layers are of very small volume. The tephra sequence provides a unique record of the incremental development of the zoned, high silica portion of the Rainier Mesa magma body.

Huysken, Kristin T.; Vogel, Thomas A.; Layer, Paul W.

1994-11-01

140

Performance model of a recirculating stack nickel hydrogen cell  

NASA Astrophysics Data System (ADS)

A theoretical model of the nickel hydrogen battery cell has been utilized to describe the chemical and physical changes during charge and overcharge in a recirculating stack nickel hydrogen cell. In particular, the movement of gas and electrolyte have been examined as a function of the amount of electrolyte put into the cell stack during cell activation, and as a function of flooding in regions of the gas screen in this cell design. Additionally, a two-dimensional variation on this model has been utilized to describe the effects of non-uniform loading in the nickel-electrode on the movement of gas and electrolyte within the recirculating stack nickel hydrogen cell. The type of nonuniform loading that has been examined here is that associated with higher than average loading near the surface of the sintered nickel electrode, a condition present to some degree in many nickel electrodes made by electrochemical impregnation methods. The effects of high surface loading were examined primarily under conditions of overcharge, since the movement of gas and electrolyte in the overcharging condition was typically where the greatest effects of non-uniform loading were found. The results indicate that significant changes in the capillary forces between cell components occur as the percentage of free volume in the stack filled by electrolyte becomes very high. These changes create large gradients in gas-filled space and oxygen concentrations near the boundary between the separator and the hydrogen electrode when the electrolyte fill is much greater than about 95 percent of the stack free volume. At lower electrolyte fill levels, these gaseous and electrolyte gradients become less extreme, and shift through the separator towards the nickel electrode. Similarly, flooding of areas in the gas screen cause higher concentrations of oxygen gas to approach the platinum/hydrogen electrode that is opposite the back side of the nickel electrode. These results illustrate the need for appropriate pore size distributions, and the maintenance of both convective electrolyte and gas flow paths through the stack, if the recirculating stack nickel hydrogen cell design is to work properly.

Zimmerman, Albert H.

1994-02-01

141

Performance model of a recirculating stack nickel hydrogen cell  

NASA Technical Reports Server (NTRS)

A theoretical model of the nickel hydrogen battery cell has been utilized to describe the chemical and physical changes during charge and overcharge in a recirculating stack nickel hydrogen cell. In particular, the movement of gas and electrolyte have been examined as a function of the amount of electrolyte put into the cell stack during cell activation, and as a function of flooding in regions of the gas screen in this cell design. Additionally, a two-dimensional variation on this model has been utilized to describe the effects of non-uniform loading in the nickel-electrode on the movement of gas and electrolyte within the recirculating stack nickel hydrogen cell. The type of nonuniform loading that has been examined here is that associated with higher than average loading near the surface of the sintered nickel electrode, a condition present to some degree in many nickel electrodes made by electrochemical impregnation methods. The effects of high surface loading were examined primarily under conditions of overcharge, since the movement of gas and electrolyte in the overcharging condition was typically where the greatest effects of non-uniform loading were found. The results indicate that significant changes in the capillary forces between cell components occur as the percentage of free volume in the stack filled by electrolyte becomes very high. These changes create large gradients in gas-filled space and oxygen concentrations near the boundary between the separator and the hydrogen electrode when the electrolyte fill is much greater than about 95 percent of the stack free volume. At lower electrolyte fill levels, these gaseous and electrolyte gradients become less extreme, and shift through the separator towards the nickel electrode. Similarly, flooding of areas in the gas screen cause higher concentrations of oxygen gas to approach the platinum/hydrogen electrode that is opposite the back side of the nickel electrode. These results illustrate the need for appropriate pore size distributions, and the maintenance of both convective electrolyte and gas flow paths through the stack, if the recirculating stack nickel hydrogen cell design is to work properly.

Zimmerman, Albert H.

1994-01-01

142

Impact of the construction of a large dam on riparian vegetation cover at different elevation zones as observed from remotely sensed data  

NASA Astrophysics Data System (ADS)

The impact of the construction of a large dam on riparian vegetation cover can be multifold. How the riparian vegetation cover changes at different elevation zones in response to the construction of a large dam and the subsequent impound of reservoir water is still an open question. In this study, we used satellite remote sensing data integrated with geographic information system (GIS) to monitor vegetation cover change at different riparian elevation zones on a large spatial scale, taking the Three Gorges Dam in China as an example. Due to the large scale of this newly formed reservoir, it is expected to impact the riparian vegetation canopy both directly and indirectly. We chose to monitor vegetation cover changes along the 100 km riparian stretch of river directly upstream of the Three Gorges Dam site, over the construction period of eleven years (2000-2010), using MODIS vegetation indices products, digital elevation model (DEM) data from ASTER, and the time series water level data of the Three Gorges reservoir as the data sources. Results show that non-vegetated area increased in the inundated zone (below 175 m), as expected; area of densely vegetated land cover increased within the elevation zone of 175-775 m and no change in vegetation cover was observed above 775 m in elevation. Regression analysis between the vegetation index data and the reservoir water level shows that increasing water levels have had a negative impact on vegetation cover below 175 m, a positive impact on vegetation cover is limited to the region between 175 and 775 m, and no significant impact was observed above 775 m. MODIS EVI product is less sensitive in mapping non-vegetated land cover change, but more sensitive in mapping vegetated land cover change, caused by the reservoir water level variation; both products are similar in effectively tracking a trend between land cover change in each elevation zone with time or with reservoir water level.

Kellogg, Christopher H.; Zhou, Xiaobing

2014-10-01

143

Effects of Fluctuating River flow on Groundwater/Surface Water Mixing in the Hyporheic Zone of a Regulated, Large Cobble Bed River  

SciTech Connect

Physicochemical relationships in the boundary zone between groundwater and surface water (i.e., the hyporheic zone) are controlled by surface water hydrology and the hydrogeologic properties of the riverbed. We studied how sediment permeability and river discharge altered the vertical hydraulic gradient (VHG) and water quality of the hyporheic zone within the Hanford Reach of the Columbia River. The Columbia River at Hanford is a large, cobble-bed river where water level fluctuates up to 2 m daily because of hydropower generation. Concomitant with recording river stage, continuous readings were made of water temperature, specific conductance, dissolved oxygen, and water level of the hyporheic zone. The water level data were used to calculate VHG between the river and hyporheic zone. Sediment permeability was estimated using slug tests conducted in piezometers installed into the river bed. The response of water quality measurements and VHG to surface water fluctuations varied widely among study sites, ranging from no apparent response to co-variance with river discharge. At some sites, a hysteretic relationship between river discharge and VHG was indicated by a time lag in the response of VHG to changes in river stage. The magnitude, rate of change, and hysteresis of the VHG response varied the most at the least permeable location (hydraulic conductivity (K) = 2.9 x 10-4 cms-1), and the least at the most permeable location (K=8.0 x 10-3 cms-1). Our study provides empirical evidence that sediment properties and river discharge both control the water quality of the hyporheic zone. Regulated rivers, like the Columbia River at Hanford, that undergo large, frequent discharge fluctuations represent an ideal environment to study hydrogeologic processes over relatively short time scales (i.e., days to weeks) that would require much longer periods of time to evaluate (i.e., months to years) in un-regulated systems.

Arntzen, Evan V.; Geist, David R.; Dresel, P. Evan

2006-10-31

144

Exogenous processes study in the coastal zone of the large reservoirs in the archaeological monuments placement (Volga-Kama region)  

NASA Astrophysics Data System (ADS)

The problem of conservation of archaeological heritage is highly relevant for the Republic of Tatarstan (RT), because in its territory identified, studied and registered around 4,300 archaeological sites. Most of archaeological sites from the Mesolithic to the late Middle Ages, now situated in the coastal zone of reservoirs where archaeological objects destroying because of intensive abrasion processes. The Volga and Kama rivers region attracted people for millennia. This territory of the Russian Plain is abounding in archaeological sites of various ages. During the Upper Paleolithic study region was quite convenient for living activity of the first inhabitants because of its situation out of the glacier limits. The sites on the banks are deposited within deluvial sediments of the Late Valday glaciation which have been accumulated on the slope of the Volga and Kama valleys, placing the third terrace and the segmentations of the second terrace over the flood-plain and now completely or fragmentary destroyed by reservoir waters. The analysis of remote sensing (1958-2013) and field survey (2011-2013) data performed. Georeferencing and alignment of the historical maps with remote sensing data makes possible to reveal mistakes in old site plans and re-create the shape of the destroyed archaeological objects, as well to get the exact size of the monument and its correct orientation. Results showed also that the studying sites caused a great rate of destruction of coastline. Cultural heritage sites monitoring, with information about the chronology, cultural layer value, settlement specifics, etc., taking into account the methods used in landscape ecology and field archaeological survey, allows to evaluate damage and the intensity of archaeological sites destruction through the dangerous exogenous processes estimation. Exogenous processes data and archaeological GIS integration will form unified system of archaeological rescue works, will provide analysis of large amount data in a short time, to update and enter new data, etc. This approach will help to determine the most problematic areas, in their funding valuation and archaeological excavations planning and broaden knowledge about the past of the peoples living in study region.

Gaynullin, Iskander; Usmanov, Bulat

2014-05-01

145

Diseases encountered in rainbow trout cultured in recirculating systems  

Microsoft Academic Search

Recirculating systems create unique environments for fish culture which may provide favorable conditions for disease occurrence or the reproduction of opportunistic microorganisms. Stressful conditions in recirculating systems, such as poor water quality or high stocking densities in the culture tanks, may contribute to disease outbreaks. Non-infectious problems, including high levels of ammonia, nitrites, carbon dioxide, suspended solids, or ozone residual

Alicia C. Noble; Steven T. Summerfelt

1996-01-01

146

Internal combustion engine having exhaust gas recirculation system  

Microsoft Academic Search

An internal combustion engine has an exhaust gas recirculation system including a recirculation valve for controlling the amount of exhaust gas returned to the intake system. The position or opening of the valve is controlled to a desired position in accordance with a memory in a memory device storing desired valve positions under various combinations of the engine load and

K. Iida; K. Okazaki; Y. Yada

1983-01-01

147

Steam generator recirculating system for a pressurized water nuclear reactor  

Microsoft Academic Search

This patent describes a steam generator recirculating system for the recirculation of secondary coolant, for use with the nuclear steam supply system of a pressurized water nuclear reactor plant having at least two steam generators, main feedwater lines to each steam generator and a blowdown system for each steam generator. The system comprises: a discharge line for receipt of a

R. A. Loose; J. S. Schlonski; C. C. Steinkuhler

1987-01-01

148

Silica scale technology and water conservation. [Recirculating evaporative cooling  

Microsoft Academic Search

Conservation of water at the Los Alamos Scientific Laboratory (LASL) has been accomplished by recirculating evaporative cooling waters. Because of high silica concentration (80 mg\\/l) in Los Alamos groundwater, the concentration of recirculating water must be carefully controlled to prevent scaling. The most troublesome scale at Los Alamos has been identified as colloidal silica bound in a crystalline matrix of

W. S. Midkiff; H. P. Foyt

1976-01-01

149

Plume Generation Zones at the margins of Large Low Shear Velocity Provinces on the core mantle boundary  

NASA Astrophysics Data System (ADS)

Large Igneous Province (LIP) eruption sites of the past 300 My lie vertically above 1% slow shear wave velocity ( Vs) contours bounding the African and Pacific Large Low Shear Velocity Provinces (LLSVPs) at the core-mantle boundary (CMB), or in the cases of the Siberian and Columbia River LIPs, bounding one or other of two smaller, Low Shear Velocity Provinces (LSVPs). Steep gradients in Vs at the CMB coincide with those 1% slow contours. The sites of 24 active hotspot volcanoes project down to the same narrowly defined borders of the LLSVPs at the CMB. Plumes that have generated LIPs and major hotspot volcanoes have risen only from the immediate neighbourhoods of the 1% slow Vs contours at the CMB which thus define Plume Generation Zones (PGZs). PGZs projected vertically upward approximately match the + 10 m elevation contour of the geoid showing that the LLSVPs are a dominant control on the positively elevated geoid. Minima in the frequency distribution of shear wave velocities in the lowermost mantle near Vs = - 1% indicate that regions with more negative velocities, forming ˜ 2% of total mantle mass, are likely to be of material compositionally different from the rest of the mantle. Because all LIP eruption sites with ages younger than 300 Ma lie above the borders of LLSVPs or LSVPs at the CMB, PGZ footprints are inferred to have remained in the same places for the past 300 My. Because no plumes have risen from the interior of the LLSVPs and because no lithospheric slabs have penetrated those bodies the volumes of the LLSVPs are inferred to have also remained unchanged for the past 300 My. Because the LLSVPs are the dominant control on the positively elevated areas of the geoid those too must have remained as they now are since 300 Ma. The LLSVPs are not rising buoyant objects but stable features of the deep mantle. LIPs have been erupted throughout the past 2.5 Gy indicating that PGZs comparable to those of the past 0.3 Gy and LLSVPs (of which PGZs mark the margins at the CMB) have also existed for at least that long. LLSVPs could thus form the isolated reservoir invoked by some to explain the distinctive isotopic compositions of terrestrial rocks. PGZs lie at places where the boundaries of: (i) The outer core, (ii) one of the LLSVPs or LSVPs, and (iii) the seismically faster part of the deep mantle meet. Horizontal temperature gradients across the steeply inclined margins to the LLSVPs, the interiors of which are hotter than the surrounding mantle, at the CMB are key controls for the generation of plumes. Near the CMB the association of the high temperature of the outer core with an inclined thermal boundary layer at the margins of LLSVPs facilitates the generation of mantle plumes in the PGZs.

Burke, Kevin; Steinberger, Bernhard; Torsvik, Trond H.; Smethurst, Mark A.

2008-01-01

150

Recirculating Molten Metal Supply System And Method  

DOEpatents

The melter furnace includes a heating chamber (16), a pump chamber (18), a degassing chamber (20), and a filter chamber (22). The pump chamber (18) is located adjacent the heating chamber (16) and houses a molten metal pump (30). The degassing chamber (20) is located adjacent and in fluid communication with the pump chamber (18), and houses a degassing mechanism (36). The filter chamber (22) is located adjacent and in fluid communication with the degassing chamber (20). The filter chamber (22) includes a molten metal filter (38). The melter furnace (12) is used to supply molten metal to an externally located holder furnace (14), which then recirculates molten metal back to the melter furnace (12).

Kinosz, Michael J. (Apollo, PA); Meyer, Thomas N. (Murrysville, PA)

2003-07-01

151

Osteopontin Prevents Monocyte Recirculation and Apoptosis  

PubMed Central

Cells of the monocyte/macrophage lineage have been shown to be the principal targets for productive HIV-1 replication within the central nervous system. In addition, HIV-1-associated dementia (HAD) has been shown to correlate with macrophage abundance in the brain. While increased entry of monocytes into the brain is thought to initiate this process, mechanisms that prevent macrophage egress from the brain and means that prevent macrophage death may also contribute to cell accumulation. We hypothesized that osteopontin (OPN) was involved in the accumulation of macrophages in the brain in neuroAIDS. Utilizing in vitro model systems, we have demonstrated role of OPN in two distinct aspects of macrophage accumulation: prevention from recirculation, and protection from apoptosis. In these unique mechanisms, osteopontin would aid in macrophage survival and accumulation in the brain, the pathological substrate of HAD.

Burdo, Tricia H.; Wood, Malcolm R.; Fox, Howard S.

2008-01-01

152

Recirculating Linac Accelerators For Future Muon Facilities  

SciTech Connect

Neutrino Factories (NF) and Muon Colliders (MC) require rapid acceleration of shortlived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness. We discuss the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both m+ and m- species. The design will include the optics for the multi-pass linac and droplet-shaped return arcs.

Yves Roblin, Alex Bogacz, Vasiliy Morozov, Kevin Beard

2012-04-01

153

Nutrient Management in Recirculating Hydroponic Culture  

NASA Technical Reports Server (NTRS)

There is an increasing need to recirculate and reuse nutrient solutions in order to reduce environmental and economic costs. However, one of the weakest points in hydroponics is the lack of information on managing the nutrient solution. Many growers and research scientists dump out nutrient solutions and refill at weekly intervals. Other authors have recommended measuring the concentrations of individual nutrients in solution as a key to nutrient control and maintenance. Dumping and replacing solution is unnecessary. Monitoring ions in solution is not always necessary; in fact the rapid depletion of some nutrients often causes people to add toxic amounts of nutrients to the solution. Monitoring ions in solution is interesting, but it is not the key to effective maintenance.

Bugbee, Bruce

2004-01-01

154

Maintenance of the intertropical convergence zones and the large-scale tropical circulation on a water-covered earth  

Microsoft Academic Search

How the surface boundary heating (sea surface temperature) and cumulus adjustment process affect the location, structure, energetics, and dynamics of the intertropical convergence zones (ITCZs) is investigated. A series of experiments is performed with a general circulation model where the lower boundary is specified to be water at a fixed sea surface temperature (SST), an aqua planet. All experiments are

Peter G. Hess; P. J. Rasch; D. S. Battisti

1993-01-01

155

Growth and Culture of Larval and Juvenile Tautogs in a Closed Recirculating-Seawater System  

Microsoft Academic Search

Field-captured and laboratory-held adult tautogs Tautoga onitis were allowed to spawn naturally under laboratory conditions. Embryos were cultured to hatching and raised successfully through the larval stage to 490-d-old posthatch juveniles. A large (8,500-L), closed, recirculating-seawater system, designed with a biological filter containing air diffusers that passed a strong air?water mixture through a high-surface-area substrate, was used to culture the

Dean M. Perry; Renee Mercaldo-Allen; Stacy Burgh

2001-01-01

156

Recirculating industrial air: The impact on air compliance and workers` safety case study -- Hill Air Force Base C-130 painting operations. Final report, September 1996--July 1998  

SciTech Connect

Recent Clean Air Act regulations require industries, including aircraft painting facilities, to capture volatile organic compound (VOC) emissions. Because aircraft painting contaminates large airflows with traces of VOCs, conventional air control systems would be prohibitively expensive to apply. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. A computer model is presented that will calculate air control costs and chemical concentrations at selected recirculation levels. Air concentrations are compared to occupational exposure limits (OELs) to analyze worker safety. The model has a chemical database containing over 1300 chemicals. A case study has been performed on a C-130 aircraft painting facility at Hill Air Force Base, Utah. The model predicts strontium chromate concentrations during application of primer paints will reach 1000 times the OEL, and that the concentration will increase by only 1 or 2% at 90% recirculation. Exposures to strontium chromate and other particulate contaminants are affected only slightly by recirculation because airborne solids are removed efficiently when the air is filtered prior to recirculation. The respiratory protection required for the strontium chromate adequately protects workers from increased concentrations of volatile chemicals, which are caused by recirculation. The model demonstrates that recirculating 75% of the air at the Hill AFB facility has a negligible impact on safety and could save $2.7 million on the initial expenses of a VOC control system.

LaPuma, P.T.

1998-07-20

157

Large tectonic rotations since the Early Miocene in a convergent plate-boundary zone, South Island, New Zealand  

NASA Astrophysics Data System (ADS)

A palaeomagnetic study in part of the New Zealand plate-boundary zone provides new constraints on the temporal and spatial distribution of Neogene and Quaternary tectonic rotations. Thermal demagnetization of samples from Cretaceous basaltic dykes, Palaeocene-Oligocene micritic limestone, and Miocene and Pliocene siltstones in the Marlborough region, South Island, have defined stable, high-temperature magnetic components, which are interpreted as the primary magnetization. Declination anomalies, after tectonic corrections, are interpreted as rigid body rotations about a vertical axis of sample sites relative to the Pacific plate. All palaeomagnetic data from Marlborough cluster into three main groups. A 60-100° clockwise rotation affected Palaeocene to Middle Miocene sedimentary sequences across Marlborough between ˜ 18 Ma and ˜ 8 Ma, coeval with a phase of low-angle thrusting. The absence of this rotation in a Late Cretaceous dyke swarm defines the present western limit of the early rotating zone. A regional ˜ 20° clockwise rotation occurred in the last 4 Ma during the development of the Marlborough Fault System in a zone of dextral transpression, although locally clockwise rotations ? 40° may have occurred near some of the major dextral strike-slip faults. However, a negligible rotation is observed in the same period in the region to the southeast of the major Kekerengu dextral strike-slip fault, which appears to have acted as a hinge zone, accommodating relative rotation by dextral strike-slip on an arcuate fault, bending, and internal deformation. The observed tectonic rotations record the overall clockwise rotation of the trend of the southern end of the Hikurangi margin from W to NW in the Early Miocene to ˜ NE today, determined independently from the long-term relative plate motion data for the Pacific and Australian plates.

Vickery, Sara; Lamb, Simon

1995-11-01

158

The Dongbo and Purang ultramafic massifs in the Yarlung Zangbo suture zone of Tibet: Prospects for large chromite deposits  

NASA Astrophysics Data System (ADS)

Many ultramafic massifs occur along the Neo-Tethyan Yarlung Zangbo suture zone between the Indian and Eurasian plates, and the Dongbo and Purang ultramafic massifs in the western part of the zone are two of the largest. Both of them consist mainly of high-Mg harzburgite (with low pyroxene contents) and dunite with minor lherzolite. Mineral compositions of olivine, orthopyroxene, clinopyroxene, and chromite, as well as whole-rock petrochemistry indicate that these are typical Alpine-type mantle peridotites. Chromium spinels in the lherzolite have Cr#s (=100 x Cr/(Cr+Al)) of 20-30, showing an affinity with abyssal peridotites, whereas those in the harzburgites have Cr#s ranging from 20 to 75, implying later melt-rock reaction. Based on the mineralogy and geochemistry of the rocks, the Dongbo and Purang massifs are interpreted as fragments of MORB lithosphere that were modified in a later SSZ setting. Many massive chromite ores and zones of disseminated mineralization are present in the two massifs, and chromite ores have Cr#s 70-80, similar to those of the hosting dunite. The petrological features and metallogenic environment of the Dongbo and Purang massifs are very similar to those of the Luobusa peridotite massif, which hosts the largest chromite deposit in China. Thus, we propose that the Purang and Dongbo massifs are two potential locations for significant chromite deposits.

Xiong, F.; Yang, J.; Li, Y.; Liu, Z.; Liu, F.; Xu, X.

2012-12-01

159

Origin and emplacement of the andesite of Burroughs Mountain, a zoned, large-volume lava flow at Mount Rainier, Washington, USA  

NASA Astrophysics Data System (ADS)

Burroughs Mountain, situated at the northeast foot of Mount Rainier, WA, exposes a large-volume (3.4 km 3) andesitic lava flow, up to 350 m thick and extending 11 km in length. Two sampling traverses from flow base to eroded top, over vertical sections of 245 and 300 m, show that the flow consists of a felsic lower unit (100 m thick) overlain sharply by a more mafic upper unit. The mafic upper unit is chemically zoned, becoming slightly more evolved upward; the lower unit is heterogeneous and unzoned. The lower unit is also more phenocryst-rich and locally contains inclusions of quenched basaltic andesite magma that are absent from the upper unit. Widespread, vuggy, gabbronorite-to-diorite inclusions may be fragments of shallow cumulates, exhumed from the Mount Rainier magmatic system. Chemically heterogeneous block-and-ash-flow deposits that conformably underlie the lava flow were the earliest products of the eruptive episode. The felsic-mafic-felsic progression in lava composition resulted from partial evacuation of a vertically-zoned magma reservoir, in which either (1) average depth of withdrawal increased, then decreased, during eruption, perhaps due to variations in effusion rate, or (2) magmatic recharge stimulated ascent of a plume that brought less evolved magma to shallow levels at an intermediate stage of the eruption. Pre-eruptive zonation resulted from combined crystallization-differentiation and intrusion(s) of less evolved magma into the partly crystallized resident magma body. The zoned lava flow at Burroughs Mountain shows that, at times, Mount Rainier's magmatic system has developed relatively large, shallow reservoirs that, despite complex recharge events, were capable of developing a felsic-upward compositional zonation similar to that inferred from large ash-flow sheets and other zoned lava flows.

Stockstill, Karen R.; Vogel, Thomas A.; Sisson, Thomas W.

2003-01-01

160

33 CFR 165.1317 - Security and Safety Zone; Large Passenger Vessel Protection, Puget Sound and adjacent waters...  

Code of Federal Regulations, 2013 CFR

...Large Passenger Vessel Protection, Puget Sound and adjacent waters, Washington. 165...Large Passenger Vessel Protection, Puget Sound and adjacent waters, Washington. ...notice by the Captain of the Port Puget Sound. Captain of the Port Puget Sound...

2013-07-01

161

Design study of a gas turbine combustor with heat recirculation  

NASA Technical Reports Server (NTRS)

A means of avoiding stoichiometric combustion, reducing emissions, and yet providing stable burning for lean mixtures is based on the use of heat recirculation rather than flow recirculation. This paper is concerned with the calculations of the design parameters of a gas turbine combustor with heat exchanger to produce the desired preheat temperature. The combustor inlet temperature, maximum temperature, equivalence ratio and recirculated heat are determined by thermodynamic analysis. The heat transfer analysis then provides the dimensions of the system to produce the predetermined boundary conditions. It is indicated that practical combustor design may be feasible for reactant mixtures as low as equivalence ratio 0.2.

Ganji, A.; Branch, M. C.; Oppenheim, A. K.

1976-01-01

162

Recirculating industrial air: The impact on air compliance and workers. Safety case study: Hill Air Force Base C-130 painting operations  

SciTech Connect

The 1990 Clean Air Act Amendment resulted in new environmental regulations called the National Emission Standards for Hazardous Air Pollutants (NESHAPs). Industries such as painting facilities may have to treat large volumes of air, which drives the cost of an air control system. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. A guided computer model written in Microsoft Excel 97% is developed to analyze worker safety and compliance costs with a focus on recirculation. The model has a chemical database containing over 1300 chemicals and requires inputs such as tasks performed, hazardous products used, and chemical make-up of the products. The model will predict indoor air concentrations in relation to occupational exposure limits (OELs). A case study is performed on a C-130 aircraft painting facility at Hill AFB, UT. The Aerospace NESHAP requires air pollution reductions in aircraft painting operations. The model predicts strontium chromate concentrations found in primer paints will reach 1000 times the OEL. Strontium chromate and other solid particulates are nearly unaffected by recirculation because the air is filtered prior to recirculation. The next highest chemical, hexamethylene diisocyanate (HDI), increases from 2.6 to 10.5 times the OEL at 0% and 75% recirculation, respectively. Due to the level of respiratory protection required for the strontium chromate, workers are well protected from the modest increases in concentrations caused by recirculating 75%. The initial cost of a VOC control system with no recirculation is $4.5 million and $1.8 million at 75% recirculation. To decide the best operating conditions for a facility, all options such as product substitution, operational changes or recirculation should be explored. The model is an excellent tool to evaluate these options.

LaPuma, P.T.

1998-06-29

163

Large enhancements in low latitude total electron content during 15 May 2005 geomagnetic storm in Indian zone  

NASA Astrophysics Data System (ADS)

Results pertaining to the response of the equatorial and low latitude ionosphere to a major geomagnetic storm that occurred on 15 May 2005 are presented. These results are also the first from the Indian zone in terms of (i) GPS derived total electron content (TEC) variations following the storm (ii) Local low latitude electrodynamics response to penetration of high latitude convection electric field (iii) effect of storm induced traveling atmospheric disturbances (TAD's) on GPS-TEC in equatorial ionization anomaly (EIA) zone. Data set comprising of ionospheric TEC obtained from GPS measurements, ionograms from an EIA zone station, New Delhi (Geog. Lat. 28.42° N, Geog. Long. 77.21° E), ground based magnetometers in equatorial and low latitude stations and solar wind data obtained from Advanced Composition Explorer (ACE) has been used in the present study. GPS receivers located at Udaipur (Geog. Lat. 24.73° N, Geog. Long. 73.73° E) and Hyderabad (Geog. Lat. 17.33° N, Geog. Long. 78.47° E) have been used for wider spatial coverage in the Indian zone. Storm induced features in vertical TEC (VTEC) have been obtained comparing them with the mean VTEC of quiet days. Variations in solar wind parameters, as obtained from ACE and in the SYM-H index, indicate that the storm commenced on 15 May 2005 at 02:39 UT. The main phase of the storm commenced at 06:00 UT on 15 May with a sudden southward turning of the Z-component of interplanetary magnetic field (IMF-Bz) and subsequent decrease in SYM-H index. The dawn-to-dusk convection electric field of high latitude origin penetrated to low and equatorial latitudes simultaneously as corroborated by the magnetometer data from the Indian zone. Subsequent northward turning of the IMF-Bz, and the penetration of the dusk-to-dawn electric field over the dip equator is also discernible. Response of the low latitude ionosphere to this storm may be characterized in terms of (i) enhanced background level of VTEC as compared to the mean VTEC, (ii) peaks in VTEC and foF2 within two hours of prompt penetration of electric field and (iii) wave-like modulations in VTEC and sudden enhancement in hmF2 within 4-5 h in to the storm. These features have been explained in terms of the modified fountain effect, local low latitude electrodynamic response to penetration electric field and the TIDs, respectively. The study reveals a strong positive ionospheric storm in the Indian zone on 15 May 2005. Consequences of such major ionospheric storms on the systems that use satellite based navigation solutions in low latitude, are also discussed.

Dashora, N.; Sharma, S.; Dabas, R. S.; Alex, S.; Pandey, R.

2009-05-01

164

Chemical evolution of a large mafic intrusion in the lower crust, Ivrea-Verbano Zone, northern Italy  

NASA Astrophysics Data System (ADS)

The Ivrea-Verbano and adjacent Strona-Ceneri zones have been described collectively as a section through the continental crust. While resident in the lower crust, amphibolite- to granulite-facies paragneiss of the Ivrea-Verbano Zone was intruded by huge volumes of mafic to intermediate plutonic rocks grouped as the Mafic Complex. Growth of the Mafic Complex involved hypersolidus deformation in an extensional environment. Isotopic and trace element variations close to the axis of this structure indicate crystallization from mantle-derived melts that were extensively contaminated by crustal material. Previous investigations determined that the contaminant was fingerprinted by Sr-87/Sr-86 is greater than 0.71, (delta) O-18 = 10-12.5%, and a positive Eu anomaly. In the present study, the contaminant is also shown to have been enriched in Ba with respect to Rb and K. Charnockites associated with paragneiss septa in the lower part of the Mafic Complex have the appropriate chemistry to be samples of the contaminating material. These chemical features can be explained by melting of granulite-facies paragneiss, which had previously been depleted in K and Rb by an earlier melting event. The Ba enrichment in the core of the Mafic Complex can be modeled by a replenishment-tapping-fractional-crystallization (RTF) process operating within a small magma chamber is repeatedly replenished by mantle melts and contaminated by Ba-rich charnockite. Very high Ba/K in the lower part of the complex are tentatively attributed to chemical exchange between the cumulate framework and infiltrating anatectic melts from underlying paragneiss septa. In contrast to the Mafic Complex, the chemistry of coeval granites in the adjacent Strona-Ceneri zone reflect a component derived from crustal rocks that had not been significantly depleted by a previous melting event. Significantly, the incompatible trace element abundances in the Mafic Complex and Strona-Ceneri granites are similar to model compositions for the lower and upper crust, respectively.

Sinigoi, Silvano; Quick, James E.; Clemens-Knott, Diane; Mayer, Adriano; Demarchi, Gabbriella; Mazzucchelli, Maurizio; Negrini, Luisa; Rivalenti, Giorgio

1994-11-01

165

Nappe-Bounding Shear Zones Initiated On Syn-Tectonic, Pegmatite-Filled Extensional Shear Fractures During Deep-Crustal Nappe Flow In A Large Hot Orogen  

NASA Astrophysics Data System (ADS)

The Central Gneiss Belt (CGB) of the Proterozoic western Grenville Province is an extensive exposure of the mid-crustal levels (upper amphibolite facies, lesser granulites) of a large hot orogen. Numerical models give a credible prediction of structure and metamorphism accompanying CGB deep-crustal nappe flow and define a temporal framework based on four developmental phases: thickening, heating, nappe-flow and post convergence extensional spreading. These phases are diachronous in direction of orogen propagation and imply a spatial framework: externides (close to orogen-craton boundary) containing moderately inclined thickening and/or extensional structures, and internides containing thickening structures overprinted by sub-horizontal nappe flow structures, which may be locally overprinted by those due to extensional spreading. Although on average of granitoid composition, CGB nappes differ in rheology, varying from fertile and weak (unmetamorphosed before Grenville, meltable) to infertile and strong (metamorphosed at high grade before Grenville, unmeltable) or mixed fertile-infertile protoliths. Deformation style varies from diffuse in fertile nappes, weakened by pervasive melting, to localised in shear zones on boundaries or interiors of infertile nappes. Specifically, in terms of deformation phase and location within the orogen, shear zones occur as: thickening structures of externides, early thickening- and later overprinting nappe-flow structures of infertile internide nappes, and extension-related shear zones in externides and internides. Many of the nappe-flow shear zones of the internides are associated with pegmatites. One example has been recognized of a preserved progression from small-scale fracture arrays to regional shear zone. The sequence is present on a km-scale and initiates in the interior of a nappe of layered granulite with arrays of pegmatite filled extensional-shear fractures (mm to cm width) displaying amphibolized margins. The fracture arrays develop into systems of pegmatite cored amphibolite facies shear zones (cm to dm width) lying within metre-scale corridors of variably retrogressed unsheared layered granulite. The sequence culminates with transposition of the layered protolith within the kilometre-scale amphibolite facies shear zone that forms the base of the granulite nappe. The pegmatitic hydrous magma clearly plays a role in initial crack formation, progressive retrogression and weakening of the granulite but its source remains obscure.

Culshaw, Nicholas; Gerbi, Christopher; Marsh, Jeffrey; Regan, Peter

2014-05-01

166

Ozonated seawater induces genotoxicity and hematological alterations in turbot ( Scophthalmus maximus) — Implications for management of recirculation aquaculture systems  

Microsoft Academic Search

Ozonation has proven useful in recirculating aquaculture systems promoting the stabilization of water quality and disease control. Nevertheless, its cytogenetic and physiological effects on fish are still largely unknown. Hence, this research investigated the effects of ozone exposure in juvenile turbot (Scophthalmus maximus) by assessing its genotoxic potential (erythrocytic nuclear abnormalities — ENA — assay) and alterations on hematological parameters

J. Silva; A. Laranjeira; R. Serradeiro; M. A. Santos; M. Pacheco

2011-01-01

167

Large-eddy-simulation of buoyancy-driven fire propagation behind a pyrolysis zone along a vertical wall  

Microsoft Academic Search

Large-eddy-simulation (LES) is performed to investigate the transport characteristics and structure of large-scale, turbulent fires on vertical surfaces under natural convection conditions. The combustion process in buoyancy-driven wall fire plumes is assumed to be diffusion controlled, permitting a mixture-fraction-based modeling approach. The three-dimensional, time-dependent Navier–Stokes equations and mixture fraction are solved with sufficient temporal and spatial resolution. The large-scale eddies

H. Y. Wang; M. Coutin; J. M. Most

2002-01-01

168

Nitric Oxide Formation in Combustion Processes with Strong Recirculation.  

National Technical Information Service (NTIS)

The principal objective of the combustion experiments was to obtain information on the nitric oxide formation process in a continuous flow combustion system in which the flame is stabilized by recirculation. Specifically, the factors affecting nitric oxid...

C. T. Bowman L. S. Cohen M. N. Director

1973-01-01

169

Future of recirculating systems in the US aquaculture industry  

SciTech Connect

Recirculating systems consist of a culture unit, a recirculating pump, and a treatment block which facilitate extended re-use of water in the rearing of aquatic animals. As water re-use is extended from a few hours to months or even years, the complexity of the treatment block increases. Classified as either `open` with greater than 10 percent water replacement per day or `closed` with less than 10 percent daily replacement, most recirculating systems include aerators, clarifiers, and biofilters as key core elements. The aquaculture industry is increasingly facing a variety of socio-economic issues which will dramatically influence its future development. These problems range from increased competition for water rights through price depression and foreign imports to predation by protected migratory birds. As water-use, environmental, and conservation conflicts grow, the cost differences between the flow-through and closed production technologies will narrow, increasing the industry`s use of recirculating systems.

Malone, R.F.

1994-08-01

170

Recirculating Peritoneal Dialysis with a Subcutaneous Peritoneal Catheter.  

National Technical Information Service (NTIS)

Ten end stage renal disease patients, 9 of whom were diabetic, were treated with peritoneal dialysis via a subcutaneous peritoneal catheter. Three dialysis formats were used: Intermittent peritoneal dialysis (IPD), recirculating peritoneal dialysis (RPD),...

R. L. Stephen S. C. Jacobsen C. Kablitz W. J. Kolff

1977-01-01

171

Recirculating Peritoneal Dialysis with a Subcutaneous Peritoneal Catheter.  

National Technical Information Service (NTIS)

Nine patients with end stage renal disease have been treated with peritoneal dialysis utilizing a subcutaneous peritoneal catheter as the access route and recirculation (RPD) as the dialysis format, over a period extending from one to eleven months. Seven...

R. L. Stephen S. C. Jacobsen W. J. Kolff E. Atkin-Thor

1976-01-01

172

Transport and error sensitivity in a heavy-ion recirculator  

SciTech Connect

An envelope code has been developed to facilitate the design of a recirculating accelerator for a heavy-ion fusion reactor. A novel feature of the model is the treatment of the beam charge density as a Lagrangian fluid in the axial direction. Transport results for a preliminary recirculator design are presented, and sensitivity of the transport to errors in the magnet strength is discussed. 4 refs., 4 figs.

Sharp, W.M.; Barnard, J.J.; Yu, S.S.

1991-05-01

173

Momentum and heat transfer in a complex recirculating flow  

Microsoft Academic Search

Three-dimensional and turbulent recirculating flows in enclosed spaces occur in many engineering situations. Accurate measurements of momentum- and heat-transfer characteristics are needed for direct engineering-design applications and for developments of numerical-simulation codes of these flows. A facility to generate recirculating flows driven by buoyancy and\\/or shear forces in a rectangular cavity was constructed to model such flows. Also, a visualization

Rhee

1987-01-01

174

Heat recirculating cooler for fluid stream pollutant removal  

DOEpatents

A process by which heat is removed from a reactant fluid to reach the operating temperature of a known pollutant removal method and said heat is recirculated to raise the temperature of the product fluid. The process can be utilized whenever an intermediate step reaction requires a lower reaction temperature than the prior and next steps. The benefits of a heat-recirculating cooler include the ability to use known pollutant removal methods and increased thermal efficiency of the system.

Richards, George A. (Morgantown, WV); Berry, David A. (Morgantown, WV)

2008-10-28

175

Pulsed power requirements for the Sandia recirculating electron beam linac  

Microsoft Academic Search

Compact, high gradient, linear induction accelerators may be achieved by recirculating the electron beam in phase with a repeating accelerating voltage. A two-cavity recirculating accelerator has been designed and operated in a single-pass mode. The prototype accelerator uses a 2.5-MV, 20-kA, 25-ns duration injector and an accelerating cavity that will produce a total accelerating voltage of 5.3 MV for four

W. K. Tucker; S. L. Shope; D. E. Hasti

1987-01-01

176

Large Eddy Simulations of forced ignition of a non-premixed bluff-body methane flame with Conditional Moment Closure  

SciTech Connect

Large Eddy Simulations (LES) of forced ignition of a bluff-body stabilised non-premixed methane flame using the Conditional Moment Closure (CMC) turbulent combustion model have been performed. The aim is to investigate the feasibility of the use of CMC/LES for ignition problems and to examine which, if any, of the characteristics already observed in related experiments could be predicted. A three-dimensional formulation of the CMC equation was used with simple and detailed chemical mechanisms, and sparks with different parameters (location, size) were used. It was found that the correct pattern of flame expansion and overall flame appearance were predicted with reasonable accuracy with both mechanisms, but the detailed mechanism resulted in expansion rates closer to the experiment. Moreover, the distribution of OH was predicted qualitatively accurately, with patches of high and low concentration in the recirculation zone during the ignition transient, consistent with experimental data. The location of the spark relative to the recirculation zone was found to determine the pattern of the flame propagation and the total time for the flame stabilisation. The size was also an important parameter, since it was found that the flame extinguishes when the spark is very small, in agreement with expectations from experiment. The stabilisation mechanism of the flame was dominated by the convection and sub-grid scale diffusion of hot combustion products from the recirculation zone to the cold gases that enter the burner, as revealed by analysis of the CMC equation. (author)

Triantafyllidis, A.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Eggels, R.L.G.M. [Rolls Royce Deutschland, Blankenfelde-Mahlow (Germany)

2009-12-15

177

Impact of nitrate-enhanced leachate recirculation on gaseous releases from a landfill bioreactor cell  

SciTech Connect

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N{sub 2}O emissions. During several weeks, we monitored gas concentrations in the landfill gas collection system as well as surface gas releases with a series of seven static chambers. These devices were directly connected to a gas chromatograph coupled to a flame ionisation detector and an electron capture detector (GC-FID/ECD) placed directly on the field. Measurements were performed before, during and after recirculation of raw leachate and nitrate-enhanced leachate. Raw leachate recirculation did not have a significant effect on the biogas concentrations (CO{sub 2}, CH{sub 4} and N{sub 2}O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N{sub 2}O concentrations in the gas collected from the recirculation trench (100-fold increase from 0.2 ppm to 23 ppm). In the common gas collection system however, this N{sub 2}O increase was no more detectable because of dilution by gas coming from other cells or ambient air intrusion. Surface releases through the temporary cover were characterized by a large spatial and temporal variability. One automated chamber gave limited standard errors over each experimental period for N{sub 2}O releases: 8.1 {+-} 0.16 mg m{sup -2} d{sup -1} (n = 384), 4.2 {+-} 0.14 mg m{sup -2} d{sup -1} (n = 132) and 1.9 {+-} 0.10 mg m{sup -2} d{sup -1} (n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N{sub 2}O gaseous surface releases and recirculation events were evidenced. Estimated N{sub 2}O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection.

Tallec, G.; Bureau, C. [Cemagref, UR HBAN, Parc de Tourvoie, BP44, F-92163 Antony (France); Peu, P.; Benoist, J.C. [Cemagref, UR GERE, 17 Avenue de Cucille, CS 64427, F-35044 Rennes (France); Lemunier, M. [Suez-Environnement, CIRADE, 38 Av. Jean Jaures, 78440 Gargenville (France); Budka, A.; Presse, D. [SITA France, 132 Rue des 3 Fontanot, 92000 Nanterre Cedex (France); Bouchez, T. [Cemagref, UR HBAN, Parc de Tourvoie, BP44, F-92163 Antony (France)], E-mail: theodore.bouchez@cemagref.fr

2009-07-15

178

Antral recirculation in the stomach during gastric mixing.  

PubMed

We investigate flow in the stomach during gastric mixing using a numerical simulation with an anatomically realistic geometry and free-surface flow modeling. Because of momentum differences between greater and lesser curvatures during peristaltic contractions, time-averaged recirculation is generated in the antrum, with retropulsive flow away from the pylorus and compensation flow along the greater curvature toward the pylorus. Gastric content in the distal stomach is continuously transported to the distal antrum by the forward flow of antral recirculation, and it is then mixed by the backward retropulsive flow. Hence, the content inside the antral recirculation is well mixed independently of initial location, whereas the content outside the recirculation is poorly mixed. Free-surface modeling enables us to analyze the effects of posture on gastric mixing. In the upright, prone, and right lateral positions, most of the antrum is filled with content, and the content is well mixed by antral recirculation. In contrast, in the supine and left lateral positions, most of the content is located outside antral recirculation, which results in poor mixing. The curved, twisted shape of the stomach substantially supports gastric mixing in fluid mechanical terms. PMID:23275619

Imai, Yohsuke; Kobayashi, Ikuma; Ishida, Shunichi; Ishikawa, Takuji; Buist, Martin; Yamaguchi, Takami

2013-03-01

179

Interface shape, heat transfer and fluid flow in the floating zone growth of large silicon crystals with the needle-eye technique  

NASA Astrophysics Data System (ADS)

A computer simulation is carried out to study the interface shape, heat transfer and fluid flow in the floating zone (FZ) growth of large (> 100 mm) Si crystals with the needle-eye technique and with feed/crystal rotation. Natural convection, thermocapillary convection, electromagnetic (EM) forces and rotation in the melt are considered. The unknown shape of the molten zone is calculated as a coupled thermal-electromagnetic-hydrodynamic problem and compared with that observed during experiments. The effects of the growth rate and the process stage on the shape of the interface are demonstrated. It was observed that natural convection and rotation dominate over thermocapillary and EM convection, at least for conditions corresponding to the industrial FZ Si production with the needle-eye technique. It is shown that under these conditions the rotation destabilizes the flow and only unsteady flows exist in the molten zone. The calculated distributions of the oscillation amplitude of the tangential velocity at the growing interface correspond to the radial resistivity distributions measured in the single crystal by the photo-scanning method.

Mühlbauer, Alfred; Muiznieks, Andris; Virbulis, Janis; Lüdge, Anke; Riemann, Helge

1995-05-01

180

The skin, a novel niche for recirculating B cells1  

PubMed Central

B cells infiltrate the skin in many chronic inflammatory diseases caused by autoimmunity or infection. Despite potential contribution to disease, skin-associated B cells remain poorly characterized. Using an ovine model of granulomatous skin inflammation, we demonstrate that B cells increase in the skin and skin-draining afferent lymph during inflammation. Surprisingly, skin B cells are a heterogeneous population that is distinct from lymph node B cells, with more large lymphocytes as well as B-1-like B cells that co-express high levels IgM and CD11b. Skin B cells have increased MHCII, CD1, and CD80/86 expression compared with lymph node B cells, suggesting that they are well-suited for T cell activation at the site of inflammation. Furthermore, we show that skin accumulation of B cells and antibody-secreting cells during inflammation increases local antibody titers, which could augment host defense and autoimmunity. While skin B cells express typical skin homing receptors such as E-selectin ligand and alpha-4 and beta-1 integrins, they are unresponsive to ligands for chemokine receptors associated with T cell homing into skin. Instead, skin B cells migrate toward the cutaneously expressed CCR6 ligand CCL20. Our data support a model in which B cells use CCR6-CCL20 to recirculate through the skin, fulfilling a novel role in skin immunity and inflammation.

Geherin, Skye A.; Fintushel, Sarah R.; Lee, Michael H.; Wilson, R. Paul; Patel, Reema T.; Alt, Carsten; Young, Alan J.; Hay, John B.; Debes, Gudrun F.

2012-01-01

181

Removal of acidic pharmaceuticals within a nitrifying recirculating biofilter.  

PubMed

The fate of pharmaceutically active compounds (PhACs) in wastewater treatment systems is an area of increasing concern. Little research has been done to understand this issue in rural or decentralized communities. The objective of this research was to examine the ability of a bench scale nitrifying recirculating biofilter (RBF) to remove four acidic PhACs: gemfibrozil, naproxen, ibuprofen and diclofenac from secondary treated municipal wastewater at concentrations of 20 and 200?g/L. The average removals in this study were between 92 and 99% for ibuprofen, 89 and 99% for naproxen, 62 and 92% for gemfibrozil and 40 and 76% for diclofenac, which is consistent with literature. Ibuprofen and naproxen were largely removed through biological transformation; whereas gemfibrozil and diclofenac showed more variable removal, likely due to both biological transformation and sorption processes. PhAC removal in the RBFs was repeatable between trials, robust and responsive to system upsets, and the presence of PhACs as a single compound versus mixtures had no impact on PhAC removal efficiency. In summary, this study indicates that RBFs as a nitrifying stage of a multi-stage filtration process could be a viable technology for removal of some acidic pharmaceuticals in small onsite wastewater treatment facilities. PMID:24727009

Krkošek, W H; Payne, S J; Gagnon, G A

2014-05-30

182

Experimental investigation of aerodynamics, combustion, and emissions characteristics within the primary zone of a gas turbine combustor  

NASA Astrophysics Data System (ADS)

The present work investigates pollutant emissions production, mainly nitric oxides and carbon monoxide, within the primary zone of a highly swirling combustion and methods with which to reduce their formation. A baseline study was executed at different equivalence ratios and different inlet air temperatures. The study was then extended to investigate the effects of utilizing transverse air jets on pollutant emission characteristics at different jet locations, jet mass ratio, and overall equivalence ratio as well as to investigate the jets' overall interactions with the recirculation zone. A Fourier Transform Infrared (FTIR) spectrometer was employed to measure emissions concentrations generated during combustion of Jet-A fuel in a swirl-cup assembly. Laser Doppler Velocimetry (LDV) was employed to investigate the mean flow aerodynamics within the combustor. Particle Image Velocimetry (PIV) was utilized to capture the instantaneous aerodynamic behavior of the non-reacting primary zone. Results illustrate that NOx production is a function of both the recirculation zone and the flame length. At low overall equivalence ratios, the recirculation zone is found to be the main producer of NOx. At near stoichiometric conditions, the post recirculation zone appears to be responsible for the majority of NOx produced. Results reveal the possibility of injecting air into the recirculation zone without altering flame stability to improve emission characteristics. Depending on the jet location and strength, nitric oxides as well as carbon monoxide can be reduced simultaneously. Placing the primary air jet just downstream of the fuel rich recirculation zone can lead to a significant reduction in both nitric oxides and carbon monoxide. In the case of fuel lean recirculation zone, reduction of nitric oxides can occur by placing the jets below the location of maximum radius of the recirculation zone.

Elkady, Ahmed M.

183

Constraints on strain rates during large-scale mid-crustal shearing: An example from the basal Vaddas shear zone, northern Caledonides  

NASA Astrophysics Data System (ADS)

The Caledonian orogen in Scandinavia is characterized by large-scale crustal nappe stacks which were emplaced east-/southeast-wards onto the Baltica shield. Whereas original thrust relationships are generally obscured by syn- to post-collisional extensional deformation in the southern and central Scandinavian Caledonides, several large-scale thrust systems are well-preserved in the northern Scandinavian Caledonides in Troms and Finnmark. One example is the mid-crustal Vaddas shear zone, which emplaced the Vaddas nappe on top of the Kalak nappe complex. In this contribution we present a structural, petrological and geochronological analysis of the rocks under- and overlying the Vaddas shear zone in northern Troms, in order to estimate the strain rate associated with thrusting along this major shear zone. The Vaddas nappe above the investigated shear zone consists mainly of Upper Ordovician to Silurian metasediments, which were deposited in a marine environment and which were intruded by voluminous gabbroic intrusions, before they were sheared off from their substratum and transported on top of the Kalak nappe complex during the Caledonian orogeny. PT conditions from one of these gabbroic bodies indicate that the body intruded the metasediments at ~9 kbar (Getsinger et al., subm to G3), which corresponds to a depth of ~34 km. U-Pb SIMS dating of zircons from this gabbro indicate that intrusion occurred at 439±2 Ma. The Vaddas nappe is separated from the Kalak nappe by an at least ~150 m thick, amphibolite-facies shear zone with a subhorizontal fabric and top-to-the-SE shear sense. It has developed within the lowest part of the Vaddas nappe as well as the upper part of the Kalak nappe complex and PT calculations indicate that final shearing occurred at ~450° C and ~6 kbar (depth of ~23 km). U-Pb TIMS dating of titanites, which grow parallel to the shear fabric in the Kalak nappe complex, gives 206Pb/238U ages ranging from 442±1 to 429±1 Ma, indicating that shearing probably commenced right after intrusion of the Vaddas gabbros and continued over a period of ~10 m.y. Assuming an original dip of the Vaddas shear zone of 30° , the horizontal displacement would be ~23 km as the most conservative assumption (i.e. for a highest thrust angle) for the depth difference of 11 km between intrusion of the gabbro and late shear deformation. Given the thickness of the shear zone of 150 m and the time for the shearing of ~10 m.y., a strain rate of ~5*10-13 s-1 can be estimated. As suggested, this is a conservative estimate, so that strain rates may well have been faster. These strain rates appear to be similar to those of Alpine nappes, so that it is suggested that Caledonian nappe stacking has probably taken place at the same rates or even faster than Alpine ones. Given the fact that the transport distances in the Caledonides are far greater than in the Alps, this would suggest that the Caledonian orogeny has taken place over a longer period of time than in the Alps.

Gasser, Deta; Stünitz, Holger; Nasipuri, Pritam; Menegon, Luca

2013-04-01

184

Large slip rate detected at the seismogenic zone of the 2008 M W 7.9 Wenchuan earthquake  

Microsoft Academic Search

Repeating microearthquakes were identified along the edge of the rupture area of the 2008 M\\u000a W7.9 Wenchuan earthquake. Slip rates at depths derived from seismic moments and recurrence intervals are found to be systematically\\u000a larger than those observed at surface. This large deep slip rate may explain the odds about the occurrence of this unanticipated\\u000a event. Our observations here suggested

Qifu Chen; Le Li; Fenglin Niu; Jinrong Su

2011-01-01

185

Phosphorus dynamics at multiple time scales in the pelagic zone of a large shallow lake in Florida, USA  

Microsoft Academic Search

Phosphorus (P) dynamics in large shallow lakes are greatly influenced by physical processes such as wind-driven sediment resuspension,\\u000a at times scales from hours to years. Results from long-term (30 year) research on Lake Okeechobee, Florida (area 1,730 km2, mean depth 2.7 m) illustrate key features of these P dynamics. Variations in wind velocity result in changes in water column\\u000a transparency,

Karl E. Havens; Kang-Ren Jin; Nenad Iricanin; R. Thomas James

2007-01-01

186

Phosphorus dynamics at multiple time scales in the pelagic zone of a large shallow lake in Florida, USA  

Microsoft Academic Search

Phosphorus (P) dynamics in large shallow lakes are greatly influenced by physical processes such as wind-driven sediment resuspension,\\u000a at times scales from hours to years. Results from long-term (30 year) research on Lake Okeechobee, Florida (area 1,730 km2, mean depth 2.7 m) illustrate key features of these P dynamics. Variations in wind velocity result in changes in water column\\u000a transparency,

Karl E. Havens; Kang-Ren Jin; Nenad Iricanin; R. Thomas James

187

Visualisation of isothermal large coherent structures in a swirl burner  

SciTech Connect

Lean premixed combustion using swirl flame stabilisation is widespread amongst gas turbine manufacturers. The use of swirl mixing and flame stabilisation is also prevalent in many other non-premixed systems. Problems that emerge include loss of stabilisation as a function of combustor geometry and thermo-acoustic instabilities. Coherent structures and their relationship with combustion processes have been a concern for decades due to their complex nature. This paper thus adopts an experimental approach to characterise large coherent structures in swirl burners under isothermal conditions so as to reveal the effects of swirl in a number of geometries and cold flow patterns that are relevant in combustion. Aided by techniques such as Hot Wire Anemometry, High Speed Photography and Particle Image Velocimetry, the recognition of several structures was achieved in a 100 kW swirl burner model. Several varied, interacting, structures developed in the field as a consequence of the configurations used. New structures never observed before were identified, the results not only showing the existence of very well defined large structures, but also their dependency on geometrical and flow parameters. The PVC is confirmed to be a semi-helical structure, contrary to previous simulations performed on the system. The appearance of secondary recirculation zones and suppression of the vortical core as a consequence of geometrical constrictions are presented as a mechanism of flow control. The asymmetry of the Central Recirculation Zone in cold flows is observed in all the experiments, with its elongation dependent on Re and swirl number used. (author)

Valera-Medina, A.; Syred, N.; Griffiths, A. [School of Engineering, Cardiff University, Queen's Building, The Parade, Cardiff, Wales CF24 3AA (United Kingdom)

2009-09-15

188

Holocene paleoseismicity, temporal clustering, and probabilities of future large (M > 7) earthquakes on the Wasatch fault zone, Utah  

NASA Astrophysics Data System (ADS)

The chronology of M > 7 paleoearthquakes on the central five segments of the Wasatch fault zone (WFZ) is one of the best dated in the world and contains 16 earthquakes in the past 5600 years with an average repeat time of 350 years. Repeat times for individual segments vary by a factor of 2, and range from about 1200 to 2600 years. Four of the central five segments ruptured between ˜620 ± 30 and 1230 ± 60 calendar years B.P. The remaining segment (Brigham City segment) has not ruptured in the past 2120 ± 100 years. Comparison of the WFZ space-time diagram of paleoearthquakes with synthetic paleoseismic histories indicates that the observed temporal clusters and gaps have about an equal probability (depending on model assumptions) of reflecting random coincidence as opposed to intersegment contagion. Regional seismicity suggests that for exposure times of 50 and 100 years, the probability for an earthquake of M > 7 anywhere within the Wasatch Front region, based on a Poisson model, is 0.16 and 0.30, respectively. A fault-specific WFZ model predicts 50 and 100 year probabilities for an M > 7 earthquake on the WFZ itself, based on a Poisson model, as 0.13 and 0.25, respectively. In contrast, segment-specific earthquake probabilities that assume quasi-periodic recurrence behavior on the Weber, Provo, and Nephi segments are less (0.01-0.07 in 100 years) than the regional or fault-specific estimates (0.25-0.30 in 100 years), due to the short elapsed times compared to average recurrence intervals on those segments. The Brigham City and Salt Lake City segments, however, have time-dependent probabilities that approach or exceed the regional and fault specific probabilities. For the Salt Lake City segment, these elevated probabilities are due to the elapsed time being approximately equal to the average late Holocene recurrence time. For the Brigham City segment, the elapsed time is significantly longer than the segment-specific late Holocene recurrence time.

McCalpin, J. P.; Nishenko, S. P.

1996-03-01

189

Holocene paleoseismicity, temporal clustering, and probabilities of future large (M > 7) earthquakes on the Wasatch fault zone, Utah  

USGS Publications Warehouse

The chronology of M>7 paleoearthquakes on the central five segments of the Wasatch fault zone (WFZ) is one of the best dated in the world and contains 16 earthquakes in the past 5600 years with an average repeat time of 350 years. Repeat times for individual segments vary by a factor of 2, and range from about 1200 to 2600 years. Four of the central five segments ruptured between ??? 620??30 and 1230??60 calendar years B.P. The remaining segment (Brigham City segment) has not ruptured in the past 2120??100 years. Comparison of the WFZ space-time diagram of paleoearthquakes with synthetic paleoseismic histories indicates that the observed temporal clusters and gaps have about an equal probability (depending on model assumptions) of reflecting random coincidence as opposed to intersegment contagion. Regional seismicity suggests that for exposure times of 50 and 100 years, the probability for an earthquake of M>7 anywhere within the Wasatch Front region, based on a Poisson model, is 0.16 and 0.30, respectively. A fault-specific WFZ model predicts 50 and 100 year probabilities for a M>7 earthquake on the WFZ itself, based on a Poisson model, as 0.13 and 0.25, respectively. In contrast, segment-specific earthquake probabilities that assume quasi-periodic recurrence behavior on the Weber, Provo, and Nephi segments are less (0.01-0.07 in 100 years) than the regional or fault-specific estimates (0.25-0.30 in 100 years), due to the short elapsed times compared to average recurrence intervals on those segments. The Brigham City and Salt Lake City segments, however, have time-dependent probabilities that approach or exceed the regional and fault specific probabilities. For the Salt Lake City segment, these elevated probabilities are due to the elapsed time being approximately equal to the average late Holocene recurrence time. For the Brigham City segment, the elapsed time is significantly longer than the segment-specific late Holocene recurrence time.

McCalpin, J. P.; Nishenko, S. P.

1996-01-01

190

Hydrothermal carbonization: process water characterization and effects of water recirculation.  

PubMed

Poplar wood chips were treated hydrothermally and the increase of process efficiency by water recirculation was examined. About 15% of the carbon in the biomass was dissolved in the liquid phase when biomass was treated in de-ionized water at 220 °C for 4 h. The dissolved organic matter contained oxygen and was partly aerobically biodegradable. About 30-50% of the total organic carbon originated from organic acids. A polar and aromatic fraction was extracted and a major portion of the organic load was of higher molecular weight. By process water recirculation organic acids in the liquid phase concentrated and catalyzed dehydration reactions. As a consequence, functional groups in hydrothermally synthesized coal declined and dewaterability was enhanced. Recirculated reactive substances polymerized and formed additional solid substance. As a result, carbon and energetic yields of the produced coal rose to 84% and 82%, respectively. PMID:23792664

Stemann, Jan; Putschew, Anke; Ziegler, Felix

2013-09-01

191

Acceleration schedules for a recirculating heavy-ion accelerator  

SciTech Connect

Recent advances in solid-state switches have made it feasible to design programmable, high-repetition-rate pulsers for induction accelerators. These switches could lower the cost of recirculating induction accelerators, such as the ''small recirculator'' at Lawrence Livermore National Laboratory (LLNL), by substantially reducing the number of induction modules. Numerical work is reported here to determine what effects the use of fewer pulsers at higher voltage would have on the beam quality of the LLNL small recirculator. Lattices with different numbers of pulsers are examined using the fluid/envelope code CIRCE, and several schedules for acceleration and compression are compared for each configuration. For selected schedules, the phase-space dynamics is also studied using the particle-in-cell code WARP3d.

Sharp, W.M.; Grote, D.P.

2002-05-01

192

High Power Picosecond Laser Pulse Recirculation for Compton Scattering  

NASA Astrophysics Data System (ADS)

Gamma-ray generation by Compton back-scattering laser photons off a relativistic electron beam suffers from a small Thomson cross-section. Recirculating unused laser photons can increase the average gamma-ray flux. Traditional approaches to laser recirculation rely on either resonant coupling of a low-energy pulse train to a cavity or active pulse switching using a pockels cell. Our alternative, passive approach does not require interferometeric alignment accuracy and is compatible with ultrashort, high peak power pulses. Pulse injection is achieved by a thin frequency converter inside the cavity in the path of the incident beam. The cavity consists of dichroic mirrors that transmit the incident but reflect the frequency-converted light. Initial modeling and experiments predict better than 20 times increase in the average brightness of Compton back-scattering sources with our pulse recirculation method.

Shverdin, M.; Anderson, S.; Brown, C.; Betts, S.; Gibson, D.; Hernandez, J.; Johnson, M.; Jovanovic, I.; McNabb, D.; Messerly, M.; Pruet, J.; Tremaine, A.; Hartemann, F.; Siders, C.; Barty, C. P. J.

2007-11-01

193

Conditions of melt generation beneath the Taupo Volcanic Zone: The influence of heterogeneous mantle inputs on large-volume silicic systems  

NASA Astrophysics Data System (ADS)

Many silicic igneous provinces exhibit compositional variability defined by oscillation between 'dry' and 'wet' rhyolites. The origins of this variability are often uncertain due to the poor constraints on the composition of the mantle-derived inputs to the lower crustal hybridization zones. The Taupo Volcanic Zone (TVZ) in New Zealand, the most productive of modern silicic igneous provinces, exhibits variability of rhyolite compositions, but small-volume coeval basaltic eruptions also occur making it an ideal location to study the mantle contributions to these distinctive types of rhyolite. Here we present major and trace element data for 43 mafic lavas from 12 magmatic centers from the central TVZ. We have utilized the geochemical modeling program Arc Basalt Simulator to constrain conditions of melt generation beneath the central TVZ. We show that the distinct increase in the concentration of large-ion lithophile elements (LILE) in basalts in the northern portion of the central TVZ may be explained by increased contributions of fluid from subducted sediments and altered oceanic crust to the melting region of these basalts. Our observation of a spatial and temporal relationship between basalt and rhyolite compositional end-members is consistent with a mantle control/origin for the spectrum of rhyolite types from wet to dry that have been erupted over the modern TVZ history.

Rooney, T. O.; Deering, C. D.

2013-12-01

194

Envelope model of a heavy-ion recirculator  

SciTech Connect

A simple transport code has been developed to model the beam in a heavy-ion recirculating accelerator. The novel feature of the model is the treatment of the beam charge density as a Lagrangian fluid in the axial direction. In addition, the envelope and centroid equations include terms that account for the transverse self-force, image forces, and bend fields in the paraxial limit. The use of compressible'' beam slices makes the code suitable for designing the acceleration and compression schedules. The code has been used primarily to design the lattice of the LLNL recirculator, and preliminary magnet configurations for that machine are presented here. 3 refs., 2 figs.

Sharp, W.M.; Barnard, J.J.; Yu, S.S.

1990-12-01

195

Acceleration schedules for a recirculating heavy-ion accelerator  

SciTech Connect

The recent development of miniature inductive adders has made it feasible to design programmable, high-repetition-rate pulsers with a substantially higher voltage than is possible using a conventional field-effect transistor architecture. Prototype pulsers using the new technology are being developed as part of a series of experiments at LLNL to test the concept of a recirculating induction accelerator. Preliminary numerical work is reported here to determine what effects the higher-voltage pulsers would have on the beam quality of the LLNL small recirculator.

Grote, D P; Sharp, W

1999-06-01

196

Simulating Large-Scale Earthquake Dynamic Rupture Scenarios On Natural Fault Zones Using the ADER-DG Method  

NASA Astrophysics Data System (ADS)

In this presentation we will demonstrate the benefits of using modern numerical methods to support physic-based ground motion modeling and research. For this purpose, we utilize SeisSol an arbitrary high-order derivative Discontinuous Galerkin (ADER-DG) scheme to solve the spontaneous rupture problem with high-order accuracy in space and time using three-dimensional unstructured tetrahedral meshes. We recently verified the method in various advanced test cases of the 'SCEC/USGS Dynamic Earthquake Rupture Code Verification Exercise' benchmark suite, including branching and dipping fault systems, heterogeneous background stresses, bi-material faults and rate-and-state friction constitutive formulations. Now, we study the dynamic rupture process using 3D meshes of fault systems constructed from geological and geophysical constraints, such as high-resolution topography, 3D velocity models and fault geometries. Our starting point is a large scale earthquake dynamic rupture scenario based on the 1994 Northridge blind thrust event in Southern California. Starting from this well documented and extensively studied event, we intend to understand the ground-motion, including the relevant high frequency content, generated from complex fault systems and its variation arising from various physical constraints. For example, our results imply that the Northridge fault geometry favors a pulse-like rupture behavior.

Gabriel, Alice; Pelties, Christian

2014-05-01

197

Beam-turning magnet design and test for the Recirculating Linear Accelerator  

SciTech Connect

We have designed and tested a system for applying a ramped vertical magnetic field for turning the electron beam in the IFR Recirculating Linear Accelerator. The field is highly uniform over two Gaussian beam radii, and can be adjusted for a large radial gradient for increased energy bandwidth. The system includes shielding of the current-carrying rods to protect the pulser from REB induced fields and to reduce the effect of REB images on the beam transport to negligible levels. The system has been tested on the IBEX accelerator with > 95% peak current transport and > 90% charge transport through a 90{degree} turn. 2 refs., 6 figs.

Crow, J.T. (Sandia National Labs., Albuquerque, NM (United States)); Platt, R.C. (Science Applications International Corp., San Diego, CA (United States))

1991-01-01

198

Groundwater Discharge Into the Coastal Zone - Who Has the Gauge?  

NASA Astrophysics Data System (ADS)

The direct discharge of groundwater and recirculated seawater into the coastal zone has received increased attention in the last few years as it is now recognized that this process represents an important pathway for transport of nutrients and other dissolved materials. Assessing these material fluxes is difficult, as there is no simple means to gauge the water flux. Methods can be broadly grouped into three approaches: (1) modeling and water balance calculations; (2) direct measurement devices; and (3) geochemical tracers. As groundwater inputs tend to be very patchy, the integration of natural tracers by mixing in the coastal water column is an advantage for larger-scale studies. We have obtained estimates of land-sea groundwater fluxes by measurements of naturally-occurring radium isotopes and radon-222 in the coastal zone. Radium is largely bound to particles in the freshwater environment while it is released to solution in the presence of salt. Thus radium concentrations increase markedly as fresh groundwater and salty pore fluids mix. Radon, continuously released from the solid phases of aquifers, is typically more than 2 orders of magnitude higher in groundwaters than surface waters. Radon is also relatively easy to measure making it a good tracer for high-resolution studies. Comparison between these geochemically-based methods and those tied to hydrogeological modeling or direct measurements is hampered by gross differences in scale, both in time and in space. In spite of these problems, recent intercomparison experiments have shown that there is reasonably good agreement between methods that assess the total water flux (groundwater + recirculated seawater) while evaluating just the fresh groundwater component is more difficult.

Burnett, B.; Moore, W.

2001-05-01

199

Effects of Fluctuating River flow on Groundwater\\/Surface Water Mixing in the Hyporheic Zone of a Regulated, Large Cobble Bed River  

Microsoft Academic Search

Physicochemical relationships in the boundary zone between groundwater and surface water (i.e., the hyporheic zone) are controlled by surface water hydrology and the hydrogeologic properties of the riverbed. We studied how sediment permeability and river discharge altered the vertical hydraulic gradient (VHG) and water quality of the hyporheic zone within the Hanford Reach of the Columbia River. The Columbia River

Evan V. Arntzen; David R. Geist; P. Evan Dresel

2006-01-01

200

Microparticles in recirculating aquaculture systems: microscopic examination of particles  

Microsoft Academic Search

In order to determine the composition, shape and structure of micro-particles in a cold water recirculating plant raising juvenile Atlantic salmon to the smolt stage, samples of suspended solids, collected on classification meshes, and samples of particles in the culture water were examined microscopically. Concurrent gravimetric tests were attempted which method proved unusable due to clogging of the meshes by

R. N. Patterson; K. C. Watts

2003-01-01

201

Use of low temperature blowers for recirculation of hot gases  

DOEpatents

An apparatus is described for maintaining motors at low operating temperatures during recirculation of hot gases in fuel cell operations and chemical processes such as fluidized bed coal gasification. The apparatus includes a means for separating the hot process gas from the motor using a secondary lower temperature gas, thereby minimizing the temperature increase of the motor and associated accessories.

Maru, H.C.; Forooque, M.

1982-08-19

202

33 CFR 159.127 - Safety coliform count: Recirculating devices.  

Code of Federal Regulations, 2013 CFR

...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with § 159.123(b) and tested in accordance with...

2013-07-01

203

Confined Turbulent Swirling Recirculating Flow Predictions. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Turbulent swirling flow, the STARPIC computer code, turbulence modeling of turbulent flows, the k-xi turbulence model and extensions, turbulence parameters deduction from swirling confined flow measurements, extension of the k-xi to confined swirling recirculating flows, and general predictions for confined turbulent swirling flow are discussed.

Abujelala, M. T.

1984-01-01

204

The benefits of flue gas recirculation in waste incineration.  

PubMed

Flue gas recirculation in the incinerator combustion chamber is an operative technique that offers substantial benefits in managing waste incineration. The advantages that can be obtained are both economic and environmental and are determined by the low flow rate of fumes actually emitted if compared to the flue gas released when recirculation is not conducted. Simulations of two incineration processes, with and without flue gas recirculation, have been carried out by using a commercial flowsheeting simulator. The results of the simulations demonstrate that, from an economic point of view, the proposed technique permits a greater level of energy recovery (up to +3%) and, at the same time, lower investment costs as far as the equipment and machinery constituting the air pollution control section of the plant are concerned. At equal treatment system efficiencies, the environmental benefits stem from the decrease in the emission of atmospheric pollutants. Throughout the paper reference is made to the EC legislation in the field of environmental protection, thus ensuring the general validity in the EU of the foundations laid and conclusions drawn henceforth. A numerical example concerning mercury emission quantifies the reported considerations and illustrates that flue gas recirculation reduces emission of this pollutant by 50%. PMID:16516458

Liuzzo, Giuseppe; Verdone, Nicola; Bravi, Marco

2007-01-01

205

Energy stability in recirculating, energy-recovering linacs.  

National Technical Information Service (NTIS)

Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M(sub 5...

L. Merminga J. J. Bisognano J. R. Delayen

1996-01-01

206

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

In an internal combustion engine having an intake passage provided therein with a throttle valve for controlling intake flow of air or an air-fuel mixture passing therethrough toward engine cylinders and an exhaust passage, an exhaust gas recirculation system comprises first means for conducting a portion of the exhaust gases from the exhaust passage into the intake passage downstream of

Higashi

1984-01-01

207

Towards Non-thrombogenic Performance of Blood Recirculating Devices  

PubMed Central

Implantable blood recirculating devices have provided life saving solutions to patients with severe cardiovascular diseases. However, common problems of hemolysis and thromboembolism remain an impediment to these devices. In this article, we present a brief review of the work by several groups in the field that has led to the development of new methodologies that may facilitate achieving the daunting goal of optimizing the thrombogenic performance of blood recirculating devices. The aim is to describe work which pertains to the interaction between flow-induced stresses and the blood constituents, and that supports the hypothesis that thromboembolism in prosthetic blood recirculating devices is initiated and maintained primarily by the non-physiological flow patterns and stresses that activate and enhance the aggregation of blood platelets, increasing the risk of thromboembolism and cardioembolic stroke. Such work includes state-of-the-art numerical and experimental tools used to elucidate flow-induced mechanisms leading to thromboembolism in prosthetic devices. Following the review, the paper describes several efforts conducted by some of the groups active in the field, and points to several directions that should be pursued in the future in order to achieve the goal for blood recirculating prosthetic devices becoming more effective as destination therapy in the future.

Bluestein, D.; Chandran, K. B.; Manning, K. B.

2010-01-01

208

Using exhaust gas recirculation in internal combustion engines: a review  

Microsoft Academic Search

The aim of this work is to review the potential of exhaust gas recirculation (EGR) to reduce the exhaust emissions, particularly NOX emissions, and to delimit the application range of this technique. A detailed analysis of previous and current results of EGR effects on the emissions and performance of Diesel engines, spark ignition engines and duel fuel engines is introduced.

G. H. Abd-Alla

2002-01-01

209

An Inexpensive Recirculating Aquaculture System with Multiple Use Capabilities.  

ERIC Educational Resources Information Center

Describes the construction of an inexpensive recirculating aquaculture system that can hold up to 46 pounds of fish, invertebrates, and mussels for classroom use. The system is versatile, requires little maintenance, and can be used for both teaching and research purposes. (WRM)

Scurlock, Gerald Don, Jr.; Cook, S. Bradford; Scurlock, Carrie Ann

1999-01-01

210

The fault width formation of impending large earthquakes: Its observation near the base of the crustal seismogenic zone by the time series analysis of seismicity.  

NASA Astrophysics Data System (ADS)

Dividing Japan into meshes of about 5°, we collect earthquakes (EQ's) for each mesh-area from a focus catalog of Japan with a regionally dependent magnitude window of M >= 3-3.5. The time history of each mesh-collection is a string of EQ events, which draw a trajectory in a physical space. The space coordinates are the EQ epicenter, focal depth (DEP), inter-EQ time interval (INT), and magnitude (MAG). Thus, each coordinate component of the trajectory is the time series of the corresponding EQ source parameter where time is the chronological event index. Taking a moving-average of the series over 15-25 events, we find only two different triple phase couplings of the averaged DEP, INT, and MAG fluctuations precursory to every large EQ (M >= about 6) throughout Japan [Takeda, 2003; Takeda and Takeo, 2004]. Each triple phase coupling begins the MAG with medium MAG of about 4.1 at either small (shallow) DEP and large INT or large (deep) DEP and small INT, then change it to small MAG of about 3.8 at either deep DEP and small INT or shallow DEP and large INT. The transition of the EQ state creates a large linear DEP variation (W) on its series, which becomes comparable to the fault width of large EQ's except for only a very few cases. Thus, the precursory variation W appears to load the corresponding stress into the local region to prepare for an impending large EQ whose fault width becomes W. With the assumption of the fault length (L in km) being L = 2W, we can successfully forecast the M of the impending large EQ by an empirical relation given by Utsu [2002], log L = 0.5M - 1.8 for 6 =< M =< 8.5, [Takeda and Takeo, 2007]. Each triple phase coupling can draw its own physical picture of the seismogenic process in the earth lithosphere consisting of the brittle (B), brittle ductile transition (B-D) and ductile (D) layers. The B-D layer is at the base of the crustal seismogenic zone. The plate driving force of about 3x1012 Nm-1 creates steady state creep in the D part. According to Aki [2004], Zoback and Zoback [2002] gave a new perspective on the role of D part during the EQ loading process as follows. If the creep deformation rate is high, the stress in the B part builds up and the region becomes tectonically active by the coupling of three layers. Thus, the EQ's of various sizes in magnitude (M) occur in the B part. Aki [2004] and Jin and Aki [2005] have proposed a local version of the B and D coupling as "B-D interaction hypothesis" by a time series analysis (completely different from ours) of the decay rate of coda waves and the local selective seismicity. It is extremely intriguing that the hypothesis is in perfect harmony with physical models of the seismogenic zone inferred from the triple phase couplings.

Takeda, F.; Takeo, M.

2008-12-01

211

Ground Motion Simulation for a Large Active Fault System using Empirical Green's Function Method and the Strong Motion Prediction Recipe - a Case Study of the Noubi Fault Zone -  

NASA Astrophysics Data System (ADS)

The 1995 Hyogo-ken Nambu Earthquake (1995) near Kobe, Japan, spurred research on strong motion prediction. To mitigate damage caused by large earthquakes, a highly precise method of predicting future strong motion waveforms is required. In this study, we applied empirical Green's function method to forward modeling in order to simulate strong ground motion in the Noubi Fault zone and examine issues related to strong motion prediction for large faults. Source models for the scenario earthquakes were constructed using the recipe of strong motion prediction (Irikura and Miyake, 2001; Irikura et al., 2003). To calculate the asperity area ratio of a large fault zone, the results of a scaling model, a scaling model with 22% asperity by area, and a cascade model were compared, and several rupture points and segmentation parameters were examined for certain cases. A small earthquake (Mw: 4.6) that occurred in northern Fukui Prefecture in 2004 were examined as empirical Green's function, and the source spectrum of this small event was found to agree with the omega-square scaling law. The Nukumi, Neodani, and Umehara segments of the 1891 Noubi Earthquake were targeted in the present study. The positions of the asperity area and rupture starting points were based on the horizontal displacement distributions reported by Matsuda (1974) and the fault branching pattern and rupture direction model proposed by Nakata and Goto (1998). Asymmetry in the damage maps for the Noubi Earthquake was then examined. We compared the maximum horizontal velocities for each case that had a different rupture starting point. In the case, rupture started at the center of the Nukumi Fault, while in another case, rupture started on the southeastern edge of the Umehara Fault; the scaling model showed an approximately 2.1-fold difference between these cases at observation point FKI005 of K-Net. This difference is considered to relate to the directivity effect associated with the direction of rupture propagation. Moreover, it was clarified that the horizontal velocities by assuming the cascade model was underestimated more than one standard deviation of empirical relation by Si and Midorikawa (1999). The scaling and cascade models showed an approximately 6.4-fold difference for the case, in which the rupture started along the southeastern edge of the Umehara Fault at observation point GIF020. This difference is significantly large in comparison with the effect of different rupture starting points, and shows that it is important to base scenario earthquake assumptions on active fault datasets before establishing the source characterization model. The distribution map of seismic intensity for the 1891 Noubi Earthquake also suggests that the synthetic waveforms in the southeastern Noubi Fault zone may be underestimated. Our results indicate that outer fault parameters (e.g., earthquake moment) related to the construction of scenario earthquakes influence strong motion prediction, rather than inner fault parameters such as the rupture starting point. Based on these methods, we will predict strong motion for approximately 140 to 150 km of the Itoigawa-Shizuoka Tectonic Line.

Kuriyama, M.; Kumamoto, T.; Fujita, M.

2005-12-01

212

Deterministic simulation and assessment of air-recirculation performance of unidirectional-flow cleanrooms that incorporate age of air concept  

Microsoft Academic Search

The airflow characteristics of a unidirectional cleanroom are largely determined by the airflow in the supply air plenum, the return air plenum and the return air shaft. A deterministic computational fluid dynamic model that incorporates fan-performance characteristics was applied to investigate and compare the air-recirculation performance of the two general designs of unidirectional-flow cleanrooms. Typical flow-resistance models of the various

S. C Hu; Y. K Chuah

2003-01-01

213

Deterministic simulation and assessment of air-recirculation performance of unidirectional$ow cleanrooms that incorporate age of air concept  

Microsoft Academic Search

The air$ow characteristics of a unidirectional cleanroom are largely determined by the air$ow in the supply air plenum, the return air plenum and the return air shaft. A deterministic computational $uid dynamic model that incorporates fan-performance characteristics was applied to investigate and compare the air-recirculation performance of the two general designs of unidirectional-$ow cleanrooms. Typical $ow-resistance models of the various

S. C. Hu; Y. K. Chuah

2003-01-01

214

Groundwater Discharge Into the Coastal Zone - Who Has the Gauge?  

Microsoft Academic Search

The direct discharge of groundwater and recirculated seawater into the coastal zone has received increased attention in the last few years as it is now recognized that this process represents an important pathway for transport of nutrients and other dissolved materials. Assessing these material fluxes is difficult, as there is no simple means to gauge the water flux. Methods can

B. Burnett; W. Moore

2001-01-01

215

Zoning Study.  

National Technical Information Service (NTIS)

The study analyzes existing zoned properties in the Shreveport Standard Metropolitan Statistical Area to determine if current development justifies the amount of such zoning. It reviews administrative procedures and policies used in carrying out zoning ch...

1968-01-01

216

Quantifying turbulent wall shear stress in a stenosed pipe using large eddy simulation.  

PubMed

Large eddy simulation was applied for flow of Re=2000 in a stenosed pipe in order to undertake a thorough investigation of the wall shear stress (WSS) in turbulent flow. A decomposition of the WSS into time averaged and fluctuating components is proposed. It was concluded that a scale resolving technique is required to completely describe the WSS pattern in a subject specific vessel model, since the poststenotic region was dominated by large axial and circumferential fluctuations. Three poststenotic regions of different WSS characteristics were identified. The recirculation zone was subject to a time averaged WSS in the retrograde direction and large fluctuations. After reattachment there was an antegrade shear and smaller fluctuations than in the recirculation zone. At the reattachment the fluctuations were the largest, but no direction dominated over time. Due to symmetry the circumferential time average was always zero. Thus, in a blood vessel, the axial fluctuations would affect endothelial cells in a stretched state, whereas the circumferential fluctuations would act in a relaxed direction. PMID:20887027

Gårdhagen, Roland; Lantz, Jonas; Carlsson, Fredrik; Karlsson, Matts

2010-06-01

217

Large loop excision of the transformation zone (LLETZ) as an alternative to both local ablative and cone biopsy treatment: a series of 1000 patients.  

PubMed

One thousand patients, referred to the Oxford Colposcopy Clinic, were treated with either large loop excision of the transformation zone (LLETZ, 891 cases) or LLETZ cone (109 cases). Forty-five LLETZ cones were performed empirically, 64 under microcolposcopic guidance. Over 98% of patients were managed as outpatients under local anaesthesia, and 87% of new patients treated with LLETZ had treatment at their first visit. Ninety percent of patients had at least cervical intraepithelial neoplasia grade one (CIN I) and 73% had CIN II or worse. Seventeen cases of invasive or possibly invasive disease were detected, 6 of them unsuspected. The overall rate of complete excision of CIN or worse was 72%. Follow-up was cytologic with or without colposcopy depending on lesion severity. Ninety-one percent of 967 treated patients were free of dyskaryosis at a mean follow-up of 23 months, with complete excision of CIN or worse at LLETZ a significant predictive factor. No cases of invasive carcinoma have developed following treatment. Major morbidity was uncommon, with 3.8% severe hemorrhage. Stenosis was noted in 3.8% cases, mostly after LLETZ cone. One patient (0.1%) has reduced fertility possibly attributable to LLETZ. Questionnaire assessment revealed a very high degree of acceptability of the treatment to patients. LLETZ and LLETZ cone have proved highly acceptable and effective outpatient diagnostic and treatment alternatives to both local ablation and cone biopsy in the Oxford Colposcopy Clinic. PMID:10146250

Hallam, N F; West, J; Harper, C; Edwards, A; Hope, S; Merriman, H; Pandher, K S; Pinches, P; Slade, R; Marsh, G

1993-01-01

218

Paleoseismology of the Nephi Segment of the Wasatch Fault Zone, Juab County, Utah - Preliminary Results From Two Large Exploratory Trenches at Willow Creek  

USGS Publications Warehouse

In 2004, we identified a small parcel of U.S. Forest Service land at the mouth of Willow Creek (about 5 km west of Mona, Utah) that was suitable for trenching. At the Willow Creek site, which is near the middle of the southern strand of the Nephi segment, the WFZ has vertically displaced alluvial-fan deposits >6-7 m, forming large, steep, multiple-event scarps. In May 2005, we dug two 4- to 5-m-deep backhoe trenches at the Willow Creek site, identified three colluvial wedges in each trench, and collected samples of charcoal and A-horizon organic material for AMS (acceleration mass spectrometry) radiocarbon dating, and sampled fine-grained eolian and colluvial sediment for luminescence dating. The trenches yielded a stratigraphic assemblage composed of moderately coarse-grained fluvial and debris-flow deposits and discrete colluvial wedges associated with three faulting events (P1, P2, and P3). About one-half of the net vertical displacement is accommodated by monoclinal tilting of fan deposits on the hanging-wall block, possibly related to massive ductile landslide deposits that are present beneath the Willow Creek fan. The timing of the three surface-faulting events is bracketed by radiocarbon dates and results in a much different fault chronology and higher slip rates than previously considered for this segment of the Wasatch fault zone.

Machette, Michael N.; Crone, Anthony J; Personius, Stephen F.; Mahan, Shannon A.; Dart, Richard L.; Lidke, David J.; Olig, Susan S.

2007-01-01

219

Large-scale separation of antipsychotic alkaloids from Rauwolfia tetraphylla L. by pH-zone-refining fast centrifugal partition chromatography.  

PubMed

pH-zone-refining centrifugal partition chromatography was successively applied in the large-scale separation of close R(f) antipsychotic indole alkaloids directly from CHCl(3) fraction of Rauwolfia tetraphylla leaves. Two experiments with increasing mass from 500 mg to 3 g of crude alkaloid extracts (1C) of R. tetraphylla were carried out in normal-displacement mode using a two-phase solvent system composed of methyl tert-butyl ether/ACN/water (4:1:5, v/v/v) where HCl (12 mM) was added to the lower aqueous stationary phase as a retainer and triethylamine (5 mM) to the organic mobile phase as an eluter. The two centrifugal partition chromatography separations afforded a total of 162.6 mg of 10-methoxytetrahydroalstonine (1) and 296.5 mg of isoreserpiline (2) in 97% and 95.5% purity, respectively, along with a 400.9 mg mixture of ?-yohimbine and reserpiline (3 and 4). Further, this mixture was resolved over medium pressure LC using TLC grade silica gel H (average particle size 10 ?m), which afforded 160.4 mg of ?-yohimbine (3) and 150.2 mg of reserpiline (4) in >95% purities. The purity of the isolated antipsychotic alkaloids was analyzed by high-performance LC and their structures were characterized on the basis of their 1D, 2D NMR and electrospray ionization-mass spectroscopic data. PMID:23335460

Maurya, Anupam; Gupta, Shikha; Srivastava, Santosh K

2013-01-01

220

Holocene behavior of the Brigham City segment: implications for forecasting the next large-magnitude earthquake on the Wasatch fault zone, Utah  

USGS Publications Warehouse

The Brigham City segment (BCS), the northernmost Holocene?active segment of the Wasatch fault zone (WFZ), is considered a likely location for the next big earthquake in northern Utah. We refine the timing of the last four surface?rupturing (~Mw 7) earthquakes at several sites near Brigham City (BE1, 2430±250; BE2, 3490±180; BE3, 4510±530; and BE4, 5610±650 cal yr B.P.) and calculate mean recurrence intervals (1060–1500??yr) that are greatly exceeded by the elapsed time (~2500??yr) since the most recent surface?rupturing earthquake (MRE). An additional rupture observed at the Pearsons Canyon site (PC1, 1240±50 cal yr B.P.) near the southern segment boundary is probably spillover rupture from a large earthquake on the adjacent Weber segment. Our seismic moment calculations show that the PC1 rupture reduced accumulated moment on the BCS about 22%, a value that may have been enough to postpone the next large earthquake. However, our calculations suggest that the segment currently has accumulated more than twice the moment accumulated in the three previous earthquake cycles, so we suspect that additional interactions with the adjacent Weber segment contributed to the long elapse time since the MRE on the BCS. Our moment calculations indicate that the next earthquake is not only overdue, but could be larger than the previous four earthquakes. Displacement data show higher rates of latest Quaternary slip (~1.3??mm/yr) along the southern two?thirds of the segment. The northern third likely has experienced fewer or smaller ruptures, which suggests to us that most earthquakes initiate at the southern segment boundary.

Personius, Stephen F.; DuRoss, Christopher B.; Crone, Anthony J.

2012-01-01

221

Multiple-scale turbulence closure modeling of confined recirculating flows  

NASA Technical Reports Server (NTRS)

A multiple-scale turbulence closure scheme is developed for the numerical predictions of confined recirculating flows. This model is based on the multiple-time-scale concepts of Hanjalic et al. (1980) and takes into account the non-equilibrium spectra energy transfer mechanism. Problems concerning new formulation of energy transfer rate equations and subsequent model coefficient redefinition and energy spectrum partition are discussed. Comparisons are made with several experiments of internal recirculating flows for the purpose of model validation. Numerical results using the present model show significant improvement of predictive capability over that obtained with the single-scale k-epsilon model and show promising potential for complex turbulent flow predictions.

Chen, C. P.

1985-01-01

222

Investigation of Leachate Recirculation Effects in Istanbul Odayeri Sanitary Landfill  

Microsoft Academic Search

Each day approximately 10,000 t of municipal solid wastes (MSW) are being produced in Metropolitan Municipality Area of Istanbul. These wastes are disposed at convenient sanitary landfills. MSWs on the European side are being disposed at Odayeri Sanitary Landfill and this study is carried out at this landfill. Approximately 1.5 ha of landfill area is selected as test area for leachate recirculation

Bestamin Ozkaya; Ahmet Demir; Adem Basturk; M. Sinan Bilgili

2004-01-01

223

Monitoring carbon steel corrosion rates in refinery recirculating water  

Microsoft Academic Search

The development of measuring devices and corrosion probes for the determination of metal corrosion rates are discussed. The UISK-2 unit has been used to evaluate the efficiency of a corrosion inhibitor, sodium silicate, used for the corrosion protection of carbon steel. Satisfactory corrosion protection of carbon steel is given by the addition of 100 mg\\/liter of SiOâ to the recirculating

Yu. G. Kotlov; V. V. Burlov; S. G. Polyakov; B. M. Teslya; A. A. Yurutkin

1985-01-01

224

Cyclone reactor with internal separation and axial recirculation  

DOEpatents

A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture is described. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combustor chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture may be tangentially withdrawn from the outlet end and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture. 10 figs.

Becker, F.E.; Smolensky, L.A.

1988-07-19

225

Cyclone reactor with internal separation and axial recirculation  

DOEpatents

A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combuston chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture of flue gas and ash may be tangentially withdrawn from the outlet end of the combustor chamber and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture.

Becker, Frederick E. (Reading, MA); Smolensky, Leo A. (Concord, MA)

1989-01-01

226

A Recirculating Linac-Based Facility for Ultrafast X-Ray Science  

SciTech Connect

We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac [1,2], in particular the incorporation of EUV and soft x-ray production. The project has been named LUX--Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization of 10's fs, optimized for the study of ultra-fast dynamics. The photon range covers the EUV to hard x-ray spectrum by use of seeded harmonic generation in undulators, and a specialized technique for ultra-short pulse photon production in the 1-10 keV range. High brightness rf photocathodes produce electron bunches which are optimized either for coherent emission in free electron lasers, or to provide a large x/y emittance ration and small vertical emittance which allows for manipulation to produce short-pulse hard x-rays. An injector linac accelerates the beam to 120 MeV, and is followed by f our passes through a 600-720 MeV recirculating linac. We outline the major technical components of the proposed facility.

J. N. Corlett; W. A. Barletta; S. DeSantis; L. Doolittle; W. M. Fawley; M.A. Green; P. Heimann; S. Leone; S. Lidia; D. Li; A. Ratti; K. Robinson; R. Schoenlein; J. Staples; W. Wan; R. Wells; A.Wolski; A. Zholents; F. Parmigiani; M. Placidi; W. Pirkl; R. A. Rimmer; S. Wang

2003-05-01

227

A field-scale test of in situ chemical oxidation through recirculation  

SciTech Connect

In situ chemical oxidation is a developing class of remediation technologies in which organic contaminants are degraded in place by powerful oxidants. Successful implementation of this technology requires an effective means for dispersing the oxidant to contaminated regions in the subsurface. An oxidant delivery technique has been developed wherein the treatment solution is made by adding an oxidant to extracted groundwater. The oxidant-laden groundwater is then injected and recirculated into a contaminated aquifer through multiple horizontal and/or vertical wells. This technique, referred to as in situ chemical oxidation through recirculation (ISCOR), can be applied to saturated and hydraulically conductive formations and used with relatively stable oxidants such as potassium permanganate (KMnO{sub 4}). A field-scale test of ISCOR was conducted at a site (Portsmouth Gaseous Diffusion Plant) where groundwater in a 5-ft thick silty gravel aquifer is contaminated with trichloroethylene (TCE) at levels that indicate the presence of residual dense non-aqueous phase liquids (DNAPLs). The field test was implemented using a pair of parallel horizontal wells with 200-ft screened sections. For approximately one month, groundwater was extracted from one horizontal well, dosed with crystalline KMnO{sub 4}, and re-injected into the other horizontal well 90 ft away. Post-treatment characterization showed that ISCOR was effective at removing TCE in the saturated region. Lateral and vertical heterogeneities within the treatment zone impacted the uniform delivery of the oxidant solution. However, TCE was not detected in groundwater samples collected from monitoring wells and soil samples from borings in locations where the oxidant had permeated.

West, O.R.; Cline, S.R.; Holden, W.L.; Gardner, F.G.; Schlosser, B.M. [Oak Ridge National Lab., TN (United States); Siegrist, R.L. [Colorado School of Mines, Golden, CO (United States); Houk, T.C. [Bechtel-Jacobs, Piketon, OH (United States). Portsmouth Gaseous Diffusion Plant

1998-09-01

228

Superconcentration of photospheric sources of the large-scale open solar magnetic field in the main zone of active longitudes, differential rotation blocking, and origination of the four-sector structure. 1. The field and solar activity dynamics  

Microsoft Academic Search

The phenomena of superconcentration of the large-scale field photospheric sources in the main zone of active longitudes, blocking of regular differential rotation by these sources, and origination of the four-sector structure of the solar magnetic field during the decline phase of cycle 23 have been considered in more detail and taking into account the polar correction. It has been indicated

K. G. Ivanov

2009-01-01

229

Demonstration of a Highly Efficient Solid Oxide Fuel Cell Power System Using Adiabatic Steam Reforming and Anode Gas Recirculation  

SciTech Connect

Solid oxide fuel cells (SOFC) are currently being developed for a wide variety of applications because of their high efficiency at multiple power levels. Applications for SOFCs encompass a large range of power levels including 1-2 kW residential combined heat and power applications, 100-250 kW sized systems for distributed generation and grid extension, and MW-scale power plants utilizing coal. This paper reports on the development of a highly efficient, small-scale SOFC power system operating on methane. The system uses adiabatic steam reforming of methane and anode gas recirculation to achieve high net electrical efficiency. The anode exit gas is recirculated and all of the heat and water required for the endothermic reforming reaction are provided by the anode gas emerging from the SOFC stack. Although the single-pass fuel utilization is only about 55%, because of the anode gas recirculation the overall fuel utilization is up to 93%. The demonstrated system achieved gross power output of 1650 to 2150 watts with a maximum net LHV efficiency of 56.7% at 1720 watts. Overall system efficiency could be further improved to over 60% with use of properly sized blowers.

Powell, Michael R.; Meinhardt, Kerry D.; Sprenkle, Vincent L.; Chick, Lawrence A.; Mcvay, Gary L.

2012-05-01

230

Characteristics of velocity pulsations in a turbulent recirculated melt flow  

NASA Astrophysics Data System (ADS)

For the modern industrial applications it is necessary to develop and investigate metallic and oxide materials of high purity or predicted composition. Such materials can be produced by the induction melting method, especially in inductor and cold crucible furnaces. Measurements taken in experimental furnaces show that the velocity pulsations dominate for the heat and mass exchange in the melt, especially in a zone between typical upper and lower eddies. Understanding of the pulsation mechanism and development of models to estimate the exchange characteristics are very important for the development and optimisation of industrial furnaces. The authors present experimental results and propose a simple 3D large eddy simulation (LES) model of the induction furnace that can be adapted to qualitative analysis of experimental data. Tables 2, Figs 13, Refs 7.

Kirpo, M.; Jakovics, A.; Baake, E.

2005-06-01

231

Method and apparatus for affecting a recirculation zone in a cross flow  

DOEpatents

Disclosed is a cross flow apparatus including a surface and at least one outlet located at the surface. The cross flow apparatus further includes at least one guide at the surface configured to direct an intersecting flow flowing across the surface and increase a velocity of a cross flow being expelled from the at least one outlet downstream from the at least one outlet.

Bathina, Mahesh (Andhra Pradesh, IN); Singh, Ramanand (Uttar Pradesh, IN)

2012-07-17

232

Central recirculation zone analysis in an unconfined tangential swirl burner with varying degrees of premixing  

Microsoft Academic Search

Swirl-stabilised combustion is one of the most widely used techniques for flame stabilisation, uses ranging from gas turbine\\u000a combustors to pulverised coal-fired power stations. In gas turbines, lean premixed systems are of especial importance, giving\\u000a the ability to produce low NOx systems coupled with wide stability limits. The common element is the swirl burner, which depends\\u000a on the generation of

A. Valera-Medina; N. Syred; P. Kay; A. Griffiths

2011-01-01

233

Mechanisms of solute transport and dispersion in open channels with surface storage zones  

NASA Astrophysics Data System (ADS)

Lateral cavities in rivers and open channels are distinctive morphodynamic features that work as transient storage zones, which play a significant role on the dispersion and transport of contaminants in the stream. The dynamics of large-scale coherent structures in these turbulent flows constitute the controlling mechanisms of mass-exchange and residence times in the cavity. In this work we study the recirculating flow in lateral rectangular cavities with aspect ratios 1.0 and 3.0. We focus on the complex dynamics of the flow in the cavities and the differences as function of the geometry represented by the aspect ratio. By using time-resolved Particle Image Velocimetry (PIV) and numerical simulations with hybrid turbulence models (URANS/LES), we provide new insights on the mechanisms of dispersion and transport of contaminants for each aspect ratio, analyzing the statistics of mass exchange and residence times for these two configurations.

Escauriaza, C. R.; Soto, K.; Gonzalez, C.; Wei, C.; Mignot, E.; Riviere, N.

2013-12-01

234

Inactivation of bacteria using ultraviolet irradiation in a recirculating salmonid culture system  

Microsoft Academic Search

The objective of this research was to determine the ultraviolet (UV) irradiation dosages required to inactivate bacteria in a commercial-scale recirculating salmonid culture system. Research was conducted in the commercial-scale recirculating system used for Arctic char growout at the Conservation Fund Freshwater Institute (Shepherdstown, West Virginia). This recirculating system uses a UV channel unit to treat 100% of the 4750L\\/min

Mark J. Sharrer; Steven T. Summerfelt; Graham L. Bullock; Lauren E. Gleason; Jessica Taeuber

2005-01-01

235

Recirculation-aeration: Bibliography for aquaculture. Bibliographies and literature of agriculture (Final)  

SciTech Connect

The bibliography includes literature citations through 1992 related to water recirculation and aeration in aquaculture. The focus is on filtration, aeration, and circulation techniques in various aquaculture situations.

Perschbacher, P.W.; Powell, R.V.; Freeman, D.W.; Lorio, W.J.; Hanfman, D.T.

1993-08-01

236

Mesoscale eddies in the South Atlantic Bight and the Gulf Stream Recirculation region: Vertical structure  

NASA Astrophysics Data System (ADS)

level anomalies from altimeters are combined with decade-long potential temperature and salinity profiles from Argo floats to investigate the vertical structure of mesoscale eddies in the South Atlantic Bight (SAB) and the Gulf Stream Recirculation region. Eddy detection and eddy tracking algorithms are applied to the satellite observations, and hydrography profiles from floats that surfaced inside eddies are used to construct three-dimensional composites of cyclones and anticyclones. Eddies are characterized by large temperature and salinity anomalies at 500-1000 m depth and near the surface, and by small anomalies at 200-400 m below the surface at the depth of the North Atlantic Subtropical Mode Water. Anomalies associated with anticyclones are generally larger and found deeper in the water column compared to those due to the presence of cyclones. Geostrophic velocities around eddies generally exceed their translation speed in the top 1000 m of the water column. As such, these eddies can trap water in their interior as they propagate westward. Combining the volume of water inside eddies above their trapping depths with the number of eddies that propagate into the SAB each year, it is estimated that cyclones and anticyclones transport 3.5 ± 0.9 Sv and 4.1 ± 1.7 Sv onshore toward the Gulf Stream, respectively. The total volume transport of 7.6 ± 2.2 Sv represents an important fraction of previous estimates of the onshore transport in the Gulf Stream Recirculation gyre. Since eddies are characterized by large temperature and salinity anomalies, they also contribute significantly to the onshore transport of heat and salt.

Castelao, Renato M.

2014-03-01

237

Self-Recirculating Casing Treatment Concept for Enhanced Compressor Performance  

NASA Technical Reports Server (NTRS)

A state-of-the-art CFD code (APNASA) was employed in a computationally based investigation of the impact of casing bleed and injection on the stability and performance of a moderate speed fan rotor wherein the stalling mass flow is controlled by tip flow field breakdown. The investigation was guided by observed trends in endwall flow characteristics (e.g., increasing endwall aerodynamic blockage) as stall is approached and based on the hypothesis that application of bleed or injection can mitigate these trends. The "best" bleed and injection configurations were then combined to yield a self-recirculating casing treatment concept. The results of this investigation yielded: 1) identification of the fluid mechanisms which precipitate stall of tip critical blade rows, and 2) an approach to recirculated casing treatment which results in increased compressor stall range with minimal or no loss in efficiency. Subsequent application of this approach to a high speed transonic rotor successfully yielded significant improvements in stall range with no loss in compressor efficiency.

Hathaway, Michael D.

2002-01-01

238

Continuous hydroponic wheat production using a recirculating system  

NASA Technical Reports Server (NTRS)

Continuous crop production, where plants of various ages are growing simultaneously in a single recirculating nutrient solution, is a possible alternative to batch production in a Controlled Ecological Life Support System. A study was conducted at John F. Kennedy Space Center where 8 trays (0.24 sq m per tray) of Triticum aestivum L. Yecora Rojo were grown simultaneously in a growth chamber at 23 C, 65 percent relative humidity, 1000 ppm CO2, continuous light, with a continuous flow, thin film nutrient delivery system. The same modified Hoagland nutrient solution was recirculated through the plant trays from an 80 L reservoir throughout the study. It was maintained by periodic addition of water and nutrients based on chemical analyses of the solution. The study was conducted for 216 days, during which 24 trays of wheat were consecutively planted (one every 9 days), 16 of which were grown to maturity and harvested. The remaining 8 trays were harvested on day 216. Grain yields averaged 520 g m(exp -2), and had an average edible biomass of 32 percent. Consecutive yields were unaffected by nutrient solution age. It was concluded that continual wheat production will work in this system over an extended period of time. Certain micronutrient deficiencies and toxicities posed problems and must be addressed in future continuous production systems.

Mackowiak, C. L.; Owens, L. P.; Hinkle, C. R.; Prince, R. P.

1989-01-01

239

High-energy Picosecond Laser Pulse Recirculation for Compton Scattering  

SciTech Connect

Frequency upconversion of laser-generated photons by inverse Compton scattering for applications such as nuclear spectroscopy and gamma-gamma collider concepts on the future ILC would benefit from an increase of average source brightness. The primary obstacle to higher average brightness is the relatively small Thomson scattering cross section. It has been proposed that this limitation can be partially overcome by use of laser pulse recirculation. The traditional approach to laser recirculation entails resonant coupling of low-energy pulse train to a cavity through a partially reflective mirror. Here we present an alternative, passive approach that is akin to 'burst-mode' operation and does not require interferometric alignment accuracy. Injection of a short and energetic laser pulse is achieved by placing a thin frequency converter, such as a nonlinear optical crystal, into the cavity in the path of the incident laser pulse. This method leads to the increase of x-ray/gamma-ray energy proportional to the increase in photon energy in frequency conversion. Furthermore, frequency tunability can be achieved by utilizing parametric amplifier in place of the frequency converter.

Jovanovic, I; Anderson, S G; Betts, S M; Brown, C; Gibson, D J; Hartemann, F V; Hernandez, J E; Johnson, M; McNabb, D P; Messerly, M; Pruet, J; Shverdin, M Y; Siders, C W; Tremaine, A M; Barty, C J

2007-06-12

240

Vortical Structures in Wall-Bounded Turbulent Flow with Recirculation  

NASA Astrophysics Data System (ADS)

Hairpin or horse-shoe vortices are a widely-accepted feature of the wall-bounded flows. These vortical structures have mostly been studied in canonical flows. Relatively few studies have been conducted on the characteristics of the vortical structures in wall-bounded flows with adverse pressure gradient and still fewer on the detached flows with recirculation. In the present contribution, vortices have been educed using a DNS database of incompressible flow over a 2-dimensional surface bump in a converging-diverging channel at a Reynolds number Re? of 617, based on the friction velocity at inlet. Vortices have been educed from the instantaneous velocity field in streamwise/wall-normal and spanwise/wall-normal planes using the signed swirling strength criterion. Vortex validation is done through a fit of the vortex velocity field to the Oseen vortex model. The effects of a strong adverse pressure gradient and flow reciruclation on the population density and sizes of the streamwise and spanwise-oriented vortices have been studied. It has been found that a strong adverse pressure gradient and flow recirculation leads to the generation of a new near-wall peak of small spanwise prograde vortex population. Furthermore, this peak of vortex density has been found to coincide and hence relate to the outward movement of the peak of streamwise rms velocity fluctuations typical of adverse pressure gradient wall-bounded turbulent flows.

Imran Shah, Syed

2011-12-01

241

Effect of irradiation on nonlinear optical recirculation cavity performance  

NASA Astrophysics Data System (ADS)

In applications such as the production of hydrogen ions for accelerators in spallation neutron sources, charge stripping of hydrogen ions using high-power lasers represents an attractive technical approach. The use of laser-ion interaction in conjunction with a laser recirculation cavity holds promise for improved efficiency, but the high-radiation environment raises concerns about the longevity of the key components of such a system, especially the nonlinear crystal used for frequency conversion. We present the results of an in-reactor irradiation experiment in which a sample beta-barium borate crystal has been irradiated with fast neutrons and gamma-rays, accompanied with the Monte Carlo analysis of the irradiation dose and its comparison with typical conditions at the Spallation Neutron Source at Oak Ridge National Laboratory. The results suggest that our design of the laser recirculation cavity exhibits a radiation hardness consistent with maintaining enhancement factors of the order of 10 over >10 years, but a more detailed experimental study is needed to investigate the radiation hardness of cavity designs exhibiting greater enhancement factors.

Saitta, M.; Tikhoplav, R.; Jovanovic, I.

2012-02-01

242

Importance of entero-salivary recirculation in paracetamol pharmacokinetics.  

PubMed

The contribution of an entero-salivary recirculation (salivary secretion-swallowed-reabsorption of drug from the gastrointestinal tract) to the values of the pharmacokinetic parameters of paracetamol was studied in a two-way crossover design. Five healthy volunteers took a tablet of Paracetamol (500 mg) in two occasions separated by a washout period. The difference between the two treatments consisted of saliva that was allowed or not to be swallowed during the 4 h of study. No statistically significant differences were found in the values of the pharmacokinetic parameters between treatments. The half-life time calculated from salivary levels was similar to the values previously reported by other authors. The percent of the oral dose excreted in saliva during 4 h of study was very low (0.1%). Secondary peaks appeared in 8 of 10 profiles. The lack of influence of salivary secretion on the pharmacokinetic parameters of Paracetamol and the low percent secreted in this fluid suggests that entero-salivary recirculation is a possible physiological phenomenon undergoing after oral administration, but it is not one of the principal phenomenon that defines the pharmacokinetic of the drug. We confirm that working with salivary samples in pharmacokinetic studies of paracetamol is a useful tool. PMID:12214325

Schaiquevich, Paula; Niselman, Ada; Rubio, Modesto

2002-09-01

243

Passive mode control in the recirculating planar magnetron  

SciTech Connect

Preliminary experiments of the recirculating planar magnetron microwave source have demonstrated that the device oscillates but is susceptible to intense mode competition due, in part, to poor coupling of RF fields between the two planar oscillators. A novel method of improving the cross-oscillator coupling has been simulated in the periodically slotted mode control cathode (MCC). The MCC, as opposed to a solid conductor, is designed to electromagnetically couple both planar oscillators by allowing for the propagation of RF fields and electrons through resonantly tuned gaps in the cathode. Using the MCC, a 12-cavity anode block with a simulated 1 GHz and 0.26 c phase velocity (where c is the speed of light) was able to achieve in-phase oscillations between the two sides of the device in as little as 30 ns. An analytic study of the modified resonant structure predicts the MCC's ability to direct the RF fields to provide tunable mode separation in the recirculating planar magnetron. The self-consistent solution is presented for both the degenerate even (in phase) and odd (180 Degree-Sign out of phase) modes that exist due to the twofold symmetry of the planar magnetrons.

Franzi, Matthew; Gilgenbach, Ronald; Lau, Y. Y.; Greening, Geoff; Zhang, Peng [Plasma, Pulsed Power, and Microwave Laboratory, Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Hoff, Brad [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States)

2013-03-15

244

Interactive method for computation of viscous flow with recirculation  

NASA Technical Reports Server (NTRS)

An interactive method is proposed for the solution of two-dimensional, laminar flow fields with identifiable regions of recirculation, such as the shear-layer-driven cavity flow. The method treats the flow field as composed of two regions, with an appropriate mathematical model adopted for each region. The shear layer is computed by the compressible boundary layer equations, and the slowly recirculating flow by the incompressible Navier-Stokes equations. The flow field is solved iteratively by matching the local solutions in the two regions. For this purpose a new matching method utilizing an overlap between the two computational regions is developed, and shown to be most satisfactory. Matching of the two velocity components, as well as the change in velocity with respect to depth is amply accomplished using the present approach, and the stagnation points corresponding to separation and reattachment of the dividing streamline are computed as part of the interactive solution. The interactive method is applied to the test problem of a shear layer driven cavity. The computational results are used to show the validity and applicability of the present approach.

Brandeis, J.; Rom, J.

1981-01-01

245

A preliminary paleomagnetic pole for mid-Cretaceous rocks from Tobago: further evidence for large clockwise rotations in the Caribbean-South American plate boundary zone  

NASA Astrophysics Data System (ADS)

The island of Tobago occupies the eastern end of the central (igneous) belt of the Caribbean-South American plate boundary zone. Volcaniclastic sediment of the Albian (˜ 100 Ma) Tobago Volcanic Group and dikes of similar age within it were sampled in two homoclinal sections with different attitudes. The mean of virtual geomagnetic poles for 12 sites (25.4°N, 24.1°E, A95 = 4.2°) is well defined, pre-tilting and apparently reliable, yet is far removed from a similar age reference pole for South America. Five other paleomagnetic studies of Cretaceous rocks from widely separated localities farther west in the plate boundary zone yield pole positions that are remarkably similar to the Tobago pole. Poles obtained from the Guajira Peninsula of Colombia, the islands of Aruba and Bonaire, and the Caribbean Mountains of Venezuela are among those that agree with the Tobago result. The paleolatitudes for study areas within the plate boundary zone are consistent with an origin on or near South America, yet the poles throughout the zone are rotated roughly 90°. Dextral relative motion between the Caribbean and South American plates was probably responsible for the rotation.

Burmester, Russell F.; Beck, Myrl E.; Speed, Robert C.; Snoke, Arthur W.

1996-03-01

246

Numerical Model of Turbulence, Sediment Transport, and Sediment Cover in a Large Canyon-Bound River  

NASA Astrophysics Data System (ADS)

The Colorado River in Grand Canyon is confined by bedrock and coarse-grained sediments. Finer grain sizes are supply limited, and sandbars primarily occur in lateral separation eddies downstream of coarse-grained tributary debris fans. These sandbars are important resources for native fish, recreational boaters, and as a source of aeolian transport preventing the erosion of archaeological resources by gully extension. Relatively accurate prediction of deposition and, especially, erosion of these sandbar beaches has proven difficult using two- and three-dimensional, time-averaged morphodynamic models. We present a parallelized, three-dimensional, turbulence-resolving model using the Detached-Eddy Simulation (DES) technique. DES is a hybrid large eddy simulation (LES) and Reynolds-averaged Navier Stokes (RANS). RANS is applied to the near-bed grid cells, where grid resolution is not sufficient to fully resolve wall turbulence. LES is applied further from the bed and banks. We utilize the Spalart-Allmaras one equation turbulence closure with a rough wall extension. The model resolves large-scale turbulence using DES and simultaneously integrates the suspended sediment advection-diffusion equation. The Smith and McLean suspended sediment boundary condition is used to calculate the upward and downward settling of sediment fluxes in the grid cells attached to the bed. The model calculates the entrainment of five grain sizes at every time step using a mixing layer model. Where the mixing layer depth becomes zero, the net entrainment is zero or negative. As such, the model is able to predict the exposure and burial of bedrock and coarse-grained surfaces by fine-grained sediments. A separate program was written to automatically construct the computational domain between the water surface and a triangulated surface of a digital elevation model of the given river reach. Model results compare favorably with ADCP measurements of flow taken on the Colorado River in Grand Canyon during the High Flow Experiment (HFE) of 2008. The model accurately reproduces the size and position of the major recirculation currents, and the error in velocity magnitude was found to be less than 17% or 0.22 m/s absolute error. The mean deviation of the direction of velocity with respect to the measured velocity was found to be 20 degrees. Large-scale turbulence structures with vorticity predominantly in the vertical direction are produced at the shear layer between the main channel and the separation zone. However, these structures rapidly become three-dimensional with no preferred orientation of vorticity. Surprisingly, cross-stream velocities, into the main recirculation zone just upstream of the point of reattachment and out of the main recirculation region just downstream of the point of separation, are highest near the bed. Lateral separation eddies are more efficient at storing and exporting sediment than previously modeled. The input of sediment to the eddy recirculation zone occurs near the reattachment zone and is relatively continuous in time. While, the export of sediment to the main channel by the return current occurs in pulses. Pulsation of the strength of the return current becomes a key factor to determine the rates of erosion and deposition in the main recirculation zone.

Alvarez, L. V.; Schmeeckle, M. W.

2013-12-01

247

Superconcentration of photospheric sources of the large-scale open solar magnetic field in the main zone of active longitudes, differential rotation blocking, and origination of the four-sector structure. 1. The field and solar activity dynamics  

Microsoft Academic Search

The phenomena of superconcentration of the large-scale field photospheric sources in the main zone of active longitudes, blocking\\u000a of regular differential rotation by these sources, and origination of the four-sector structure of the solar magnetic field\\u000a during the decline phase of cycle 23 have been considered in more detail and taking into account the polar correction. It\\u000a has been indicated

K. G. Ivanov

2009-01-01

248

Influence of temperature- and depth-dependent viscosity structures on postseismic deformation predictions for the large 1946 Nankai subduction zone earthquake  

NASA Astrophysics Data System (ADS)

To investigate the influence of spatial change of viscosity on postseismic deformation associated with the interplate 1946 Nankai earthquake (M 8.0) at the Nankai Trough, southwest Japan, we newly constructed a realistic viscoelastic structure model, taking into account temperature- and depth-dependent viscosity of materials. For this purpose, we first compiled leveling and triangulation data during postseismic periods and clarified characteristics of the amount and spatial patterns of postseismic vertical displacement and principal strain fields. Then, we calculated the spatial distributions of viscosity from temperature and flow fields, which were obtained from 2D subduction models. By incorporating the obtained viscosity structure into 3D viscoelastic finite element models, we constructed a temperature- and depth-dependent viscosity structure model (MODEL P2). Based on MODEL P2, we constructed a viscoelastic structure model, taking into account Poisson's ratio for the oceanic plate and low-velocity regions and the existence of low-viscosity materials beneath the Shikoku and Chugoku districts (MODEL P3), which were revealed from seismic tomography. We also constructed a conventional layered viscoelastic structure model (MODEL L1) and plate subduction model (MODEL P1) with constant viscosity for each region and evaluated the effects of different viscoelastic structures on postseismic surface deformations, using the coseismic slip distribution obtained by inversion analyses of geodetic data. We also compared the calculated surface deformations with the observed postseismic crustal deformations in and around Shikoku. The results show that postseismic surface deformation fields for the newly constructed MODEL P2 are rather different from those for MODELs L1 and P1. Landward horizontal displacements for MODEL P2 are smaller than those for MODELs L1 and P1, seaward horizontal displacements are negligible, and vertical displacement is characterized by small subsidence over Shikoku. The postseismic horizontal principal strain field for MODEL P2 is characterized by contractions in the N-S to NW-SE directions at amounts smaller than those for MODELs L1 and P1. Postseismic surface deformations for MODEL P3 are almost the same as those for MODEL P2. The observed postseismic vertical displacement and horizontal principal strain fields could not be explained by the viscoelastic response for the realistic viscoelastic structure models P2 and P3. This indicates that the effects of elastic and viscoelastic responses due to interplate coupling on the plate interface, after-slip at the extension of the coseismic slipped region, and poroelasticity should be taken into account to precisely estimate postseismic surface deformation. This also suggests that, in order to evaluate postseismic crustal deformations derived from a large interplate subduction zone earthquake, it is essential to use realistic temperature- and depth-dependent viscoelastic structure models.

Katagi, Takeshi; Yoshioka, Shoichi; Hashimoto, Manabu

2008-06-01

249

Sensor for directly determining the exhaust gas recirculation rate—EGR sensor  

Microsoft Academic Search

Exhaust gas recirculation (EGR) is an effective means to reduce NOx emissions of internal combustion engines without increasing fuel consumption. Up to now, only complex procedures to determine the exhaust gas recirculation rate are available. Here, a novel sensor device is suggested that measures directly at one position and with only one single sensor device the concentration of a tracer

Ralf Moos; Burkhard Reetmeyer; Armin Hürland; Carsten Plog

2006-01-01

250

A Review Article: Access Recirculation Among End Stage Renal Disease Patients Undergoing Maintenance Hemodialysis  

PubMed Central

Background The presence of arterio-venous (A-V) fistula recirculation among hemodialysis (HD) patients markedly decrease adequacy of dialysis. Objectives The present article summarize some of observations about clinical significance, causes, the most common techniques for measurement, and main source of pitfall in calculation of access recirculation. Materials and Methods A variety of literature sources such as PubMed, Current Content, Scopus, Embase, and Iranmedex; with key words such as inadequate dialysis and arterio-venous fistula access recirculation were used to collect current data. Manuscripts published in English language as full-text articles or as abstract form were included in our review study. Results Any access recirculation among HD patients should be considered abnormal and if it presents prompt investigation should be performed for its causes. There are two most common techniques for accurate assessment of access recirculation: Urea (or chemical) and nonurea-based method by ultrasound dilution technique. The most common causes of access recirculation are the presence of high-grade venous stenosis, inadequate arterial blood flow rate, close proximity, or misdirection of arterial and venous needles placement by HD staff especially in new vascular accesses due to a lack of familiarity with the access anatomy. Conclusions The presence of access recirculation among HD patients can lead to significant inadequate dialysis thereby resulting in reducing the survival of these patients. Therefore, periodic assessment of access recirculation should be performed in HD wards.

Zeraati, Abbasali; Beladi Mousavi, Seyed Seifollah; Beladi Mousavi, Marzieh

2013-01-01

251

Further studies on beam breakup growth reduction by cavity cross-couplings in recirculating accelerators: Effects of long pulse length and multiturn recirculation  

NASA Astrophysics Data System (ADS)

Cavity cross-coupling was recently found to reduce beam breakup (BBU) growth in a recirculating accelerator known as the Spiral LIne Induction Accelerator (SLIA). Here, we extend the analyses in two respects: long beam pulse lengths and a SLIA upgrade geometry which accelerates a 10 kA, 35 ns beam to 25 MeV via a 70-cavity, 7-turn recirculation. We found that when the beam pulse length tau exceeds the beam's transit time tau' between cross-coupled cavities, BBU growth may be worsened as a result of the cross-couplings among cavities. This situation is not unlike other long pulse recirculating accelerators when beam recirculation leads to beam breakup of a regenerative type. Thus, the advantage of BBU reduction by cavity cross-coupling is restricted primarily to beams with tau is less than tau', a condition envisioned for all SLIA geometries. For the 70-gap, 7-turn SLIA upgrade, we found that cavity cross-coupling may reduce BBU growth up to factors of a thousand when the quality factor Q of the deflecting modes are relatively high (like 100). In these high Q cases, the amount of growth reduction depends on the arrangement and sequence of beam recirculation. For Q less than or = 20, BBU growth reduction by factors of hundreds is observed, but this reduction is insensitive to the sequence of beam recirculation. The above conclusions were based on simple models of cavity coupling that have been used in conventional microwave literature.

Colombant, D.; Lau, Y. Y.

1991-09-01

252

[Pilot scale research on impacts of leachate recirculation on its ultimate treatment].  

PubMed

Two pilot scale simulated columns, with and without leachate recirculation, were erected to study impacts of leachate recirculation of traditional anaerobic bioreactor landfill on leachate ultimate treatment methods. The results indicate that recirculation can remove organic pollutants visibly, but it isn't effective to inbiodegradable components, nitrogen (N) and phosphorus (P) pollutants. After recircualted for 44 weeks, test column has a BODs removal ratio of 98.5%. BOD5/COD value of outflow is only 0.07. BOD5/TN and BOD5/TP are 0.13 and 11 respectively, which are much lower than the adequate value for anaerobic microorganisms. It's difficult to treat this kind of leachate by traditional biological methods. When a bioreactor landfill is being designed, leachate characteristics after recirculated should be well considered and adequate leachate treatment, landfill and recirculation schemes should be chosen to take full advantage of waste stack decontamination effects. PMID:16921969

Deng, Zhou; Jiang, Jian-guo; Huang, Zhong-lin; Feng, Xiang-ming; Zhou, Sheng-yong; Yang, Guo-dong

2006-06-01

253

Physics design and scaling of recirculating induction accelerators: from benchtop prototypes to drivers  

SciTech Connect

Recirculating induction accelerators (recirculators) have been investigated as possible drivers for inertial fusion energy production because of their potential cost advantage over linear induction accelerators. Point designs were obtained and many of the critical physics and technology issues that would need to be addressed were detailed. A collaboration involving Lawrence Livermore National Laboratory and Lawrence Berkeley National Laboratory researchers is now developing a small prototype recirculator in order to demonstrate an understanding of nearly all of the critical beam dynamics issues that have been raised. We review the design equations for recirculators and demonstrate how, by keeping crucial dimensionless quantities constant, a small prototype recirculator was designed which will simulate the essential beam physics of a driver. We further show how important physical quantities such as the sensitivity to errors of optical elements (in both field strength and placement), insertion/extraction, vacuum requirements, and emittance growth, scale from small-prototype to driver-size accelerator.

Barnard, J.J.; Cable, M.D.; Callahan, D.A.

1996-02-06

254

Haldane's rule revisited: do hybrid females have a shorter lifespan? Survival of hybrids in a recent contact zone between two large gull species.  

PubMed

Haldane's rule predicts that particularly high fitness reduction should affect the heterogametic sex of interspecific hybrids. Despite the fact that hybridization is widespread in birds, survival of hybrid individuals is rarely addressed in studies of avian hybrid zones, possibly because of methodological constraints. Here, having applied capture-mark-recapture models to an extensive, 19-year-long data set on individually marked birds, we estimate annual survival rates of hybrid individuals in the hybrid zone between herring (Larus argentatus) and Caspian (Larus cachinnans) gulls. In both parental species, males have a slightly higher survival rate than females (model-weighted mean ± SE: herring gull males 0.88 ± 0.01, females 0.87 ± 0.01, Caspian gull males 0.88 ± 0.01, females 0.87 ± 0.01). Hybrid males do not survive for a shorter time than nonhybrid ones (0.88 ± 0.01), whereas hybrid females have the lowest survival rate among all groups of individuals (0.83 ± 0.03). This translates to a shorter adult (reproductive) lifespan (on average by 1.7-1.8 years, i.e. ca 25%) compared with nonhybrid females. We conclude that, in line with Haldane's rule, the lower survival rate of female hybrids may contribute to selection against hybrids in this hybrid zone. PMID:24820228

Neubauer, G; Nowicki, P; Zagalska-Neubauer, M

2014-06-01

255

Dynamics of microorganism populations in recirculating nutrient solutions  

NASA Technical Reports Server (NTRS)

This overview covers the basic microbial ecology of recirculating hydroponic solutions. Examples from NASA and Soviet CELSS tests and the commercial hydroponic industry will be used. The sources of microorganisms in nutrient solutions include air, water, seeds, plant containers and plumbing, biological vectors, and personnel. Microbial fates include growth, death, and emigration. Important microbial habitats within nutrient delivery systems are root surfaces, hardware surfaces (biofilms), and solution suspension. Numbers of bacteria on root surfaces usually exceed those from the other habitats by several orders of magnitude. Gram negative bacteria dominate the microflora with fungal counts usually much lower. Trends typically show a decrease in counts with increasing time unless stressed plants increase root exudates. Important microbial activities include carbon mineralization and nitrogen transformations. Important detrimental interactions include competition with plants, and human and plant pathogenesis.

Strayer, R. F.

1994-01-01

256

Dynamics of microorganism populations in recirculating nutrient solutions  

NASA Technical Reports Server (NTRS)

This overview covers the basic microbial ecology of recirculating hydroponic solutions. Examples from NASA and Soviet Controlled Ecological Life Support Systems (CELSS) tests and the commercial hydroponic industry will be used. The sources of microorganisms in nutrient solutions include air, water, seeds, plant containers and plumbing, biological vectors, and personnel. Microbial fates include growth, death, and emigration. Important microbial habitats within nutrient delivery systems are root surfaces, hardware surfaces (biofilms), and solution suspension. Numbers of bacteria on root surfaces usually exceed those from the other habitats by several orders of magnitude. Gram negative bacteria dominate the microflora with fungal counts usually much lower. Trends typically show a decrease in counts with increasing time unless stressed plants increase root exudates. Important microbial activities include carbon mineralization and nitrogen transformations. Important detrimental interactions include competition with plants, and human and plant pathogenesis.

Strayer, R. F.

1994-01-01

257

Timing of large earthquakes since A.D. 800 on the Mission Creek strand of the San Andreas fault zone at Thousand Palms Oasis, near Palm Springs, California  

USGS Publications Warehouse

Paleoseismic investigations across the Mission Creek strand of the San Andreas fault at Thousand Palms Oasis indicate that four and probably five surface-rupturing earthquakes occurred during the past 1200 years. Calendar age estimates for these earthquakes are based on a chronological model that incorporates radio-carbon dates from 18 in situ burn layers and stratigraphic ordering constraints. These five earthquakes occurred in about A.D. 825 (770-890) (mean, 95% range), A.D. 982 (840-1150), A.D. 1231 (1170-1290), A.D. 1502 (1450-1555), and after a date in the range of A.D. 1520-1680. The most recent surface-rupturing earthquake at Thousand Palms is likely the same as the A.D. 1676 ?? 35 event at Indio reported by Sieh and Williams (1990). Each of the past five earthquakes recorded on the San Andreas fault in the Coachella Valley strongly overlaps in time with an event at the Wrightwood paleoseismic site, about 120 km northwest of Thousand Palms Oasis. Correlation of events between these two sites suggests that at least the southernmost 200 km of the San Andreas fault zone may have ruptured in each earthquake. The average repeat time for surface-rupturing earthquakes on the San Andreas fault in the Coachella Valley is 215 ?? 25 years, whereas the elapsed time since the most recent event is 326 ?? 35 years. This suggests the southernmost San Andreas fault zone likely is very near failure. The Thousand Palms Oasis site is underlain by a series of six channels cut and filled since about A.D. 800 that cross the fault at high angles. A channel margin about 900 years old is offset right laterally 2.0 ?? 0.5 m, indicating a slip rate of 4 ?? 2 mm/yr. This slip rate is low relative to geodetic and other geologic slip rate estimates (26 ?? 2 mm/yr and about 23-35 mm/yr, respectively) on the southernmost San Andreas fault zone, possibly because (1) the site is located in a small step-over in the fault trace and so the rate is not be representative of the Mission Creek fault, (2) slip is partitioned northward from the San Andreas fault and into the eastern California shear zone, and/or (3) slip is partitioned onto the Banning strand of the San Andreas fault zone.

Fumal, T. E.; Rymer, M. J.; Seitz, G. G.

2002-01-01

258

Evaluation of recirculating sand filter in a cold climate.  

PubMed

Approximately 30% of Minnesota's residents rely on onsite technologies for their wastewater treatment. There is a growing need for 'alternative' technologies to aid in treatment for difficult sites and sensitive environmental areas. Recirculating sand filters (RSFs) have been used since the 1970s for small communities with flows > 20,000 L per day, but use for small flow application (< 5,000 L/d) has been growing due to its small land use requirement. A research site was developed in southern Minnesota in 1995 to test alternative technologies, including two RSFs. In addition, in 1998, two RSFs were added to existing residential soil treatment systems that were having problems because of inadequate separation and fill soil conditions. All RSFs in this study used 0.6 metres of coarse sand for treatment, were loaded at approximately 204 L per day per square metre (5 gallons per square foot per day) and a recirculation rate of 5:1. All RSFs have effectively reduced Biochemical Oxygen Demand (BOD5), Total Suspended Solids (TSS), Fecal Coliform (FC) and Nutrients (nitrogen and phosphorus). These systems are able to achieve secondary effluent treatment levels for BOD5 and TSS. The median FC reduction was 90% with a value of 5.7 E4 cfu/100 mL, indicating additional treatment is necessary to protect health and the environment. The RSFs consistently removed 25% or more total phosphorus (TP) and 40% or more total nitrogen (TN). The RSFs did not show significantly decreased performance during the winter months. Two of the RSFs receiving rather high strength domestic waste were able to reduce a greater percentage of total nitrogen, indicated that the addition of carbon from the high strength waste is a benefit resulting in greater TN removal. PMID:16104430

Christopherson, S H; Anderson, J L; Gustafson, D M

2005-01-01

259

Mean properties of mesoscale eddies in the Kuroshio recirculation region  

NASA Astrophysics Data System (ADS)

Using a 19-year altimetric dataset, the mean properties and spatiotemporal variations of eddies in the Kuroshio recirculation region are examined. A total of 2 001 cyclonic tracks and 1 847 anticyclonic tracks were identified using a geometry-based eddy detection method. The mean radius was 57 km for cyclonic eddies and was 61 km for anticyclonic eddies, respectively, and the mean lifetime was about 10 weeks for both type eddies. There were asymmetric spatial distributions for eddy generation and eddy termination, which were domain-dependent. Mean eddy generation rates were 2.0 per week for cyclonic eddies and were 1.9 per week for anticyclonic eddies. Both type eddies tended to deform during their lifetime and had different propagation characteristics, which mainly propagated westward and southwestward with velocities 4.0-9.9 cm/s, in the Kuroshio recirculation region. Further discussion illustrates that the eddy westward speed maybe influenced by the combined effect of vertical shear of horizontal currents and nonlinearity of eddy. To better understand the evolution of eddy tracks, a total of 134 long-lived tracks (lifetime ?20 weeks) were examined. Comparison between short-span eddies (lifetime ?4 weeks and <20 weeks) and long-lived eddies is also conducted and the result shows that the short-span and long-lived eddies have similar time evolution. Finally, eddy seasonal variations and interannual changes are discussed. Correlation analysis shows that eddy activity is sensitive to the wind stress curl and meridional gradient of sea surface temperature on interannual timescales. Besides, the strength and orientation of background flows also have impacts on the eddy genesis.

Ma, Libin; Wang, Qiang

2014-05-01

260

Oral bioavailability and enterohepatic recirculation of otilonium bromide in rats.  

PubMed

This study was conducted to examine the oral bioavailability and the possibility of enterohepatic recirculation of otilonium bromide in rats. A sensitive LC/MS/MS assay (LLOQ 0.5 ng/mL) was developed for the determination of otilonium and applied to i.v. and oral administration studies in bile duct cannulated (BDC) and non-BDC rats. After i.v. injection to BDC rats (1 mg/ kg as otilonium), average t(1/2), CL, Vz and AUC were 7.9 +/- 1.9 h, 8.7 +/- 3.1 mL/min/kg, 5.7 +/- 1.4 L/kg and 2,088 +/- 676 ng h/mL, respectively, and these values were comparable to those found in non-BDC rats. The percentages of i.v. dose excreted unchanged in bile and urine in BDC rats were 11.6 +/- 3.0 and 3.1 +/- 0.7%, respectively. Upon oral administration to non-BDC rats (20 mg/kg as otilonium), t(1/2), Cmax, Tmax and AUC were 6.4 +/- 1.3 h, 182.8 +/- 44.6 ng/mL, 1.9 +/- 1.6 h and 579 +/- 113 ng h/mL, respectively. The absolute oral bioavailability was low (1.1%), while the drug was preferentially distributed to gastrointestinal tissues. A secondary peak was observed in the serum concentration-time profiles in non-BDC rats following both i.v. and oral administration, indicating that otilonium bromide was subject to enterohepatic recirculation. PMID:18277617

Shin, Beom Soo; Kim, Jung Jun; Kim, John; Hu, Sul Ki; Kim, Hyoung Jun; Hong, Seok Hyun; Kim, Han Kyung; Lee, Hye Suk; Yoo, Sun Dong

2008-01-01

261

Displacement of large-scale open solar magnetic fields from the zone of active longitudes and the heliospheric storm of November 3-10, 2004: 1. The field dynamics and solar activity  

NASA Astrophysics Data System (ADS)

The dynamics of the large-scale open field and solar activity at the second stage of the MHD process, including the origination and disappearance of the four-sector structure during the decline phase of cycle 23 (the stage when the blocking field is displaced from the main zone of active longitudes), has been considered. Extremely fast changes in the scales of one of new sectors (from an extremely small sector (“singularity”) to a usual sector that originated after the uniform expansion (“explosion”) of singularity with a “kick” into the zone of active longitudes, westward motion of the MHD disturbance front in the direction of solar rotation, and formation of an active quasi-rigidly corotating sector boundary responsible for the heliospheric storm of November 2004) have been detected in the field dynamics. It has been indicated that a very powerful group of sunspots AR 10656 (which disappeared after the explosion) with an area of up to 1540 ppmh (part per million hemisphere), a considerable deficit of the external energy release, and zero geoeffectiveness in spite of the closeness to the Earth helioprojection existed within singularity. It has been assumed that the energy escaped from this group with effort owing to the interaction between coronal ejections and narrow sector walls (singularity), and a considerable part of the energy was released in the outer layers of the convective zone, as a result of which singularity exploded and this explosion was accompanied by the above effects in the large-scale field and solar activity.

Ivanov, K. G.

2010-06-01

262

A five-year study of coastal recirculation and its effect on air pollutants over the East Mediterranean region  

Microsoft Academic Search

Many studies have shown that air pollutants concentrations in coastal cities may be gravely affected by coastal recirculation. In this study an attempt is made to examine the properties of coastal recirculation over a long period (5 yrs) at multiple sites along the East Mediterranean Sea (EMS). For this purpose, a single station quantitative measure of horizontal recirculation is used

Ilan Levy; Uri Dayan; Yitzhak Mahrer

2008-01-01

263

A hybrid 2-zone\\/WAVE engine combustion model for simulating combustion instabilities during dilute operation  

Microsoft Academic Search

Internal combustion engines are operated under conditions of high exhaust gas recirculation (EGR) to reduce NO x emissions and promote enhanced combustion modes such as HCCI. However, high EGR under certain conditions also promotes nonlinear feedback between cycles, leading to the development of combustion instabilities and cyclic variability. We employ a two-zone phenomenological combustion model to simulate the onset of

Kevin Dean Edwards; Robert M Wagner; Veerathu K Chakravarthy; C Stuart Daw; Johney Boyd Green Jr

2006-01-01

264

Quantitative investigations of the Missouri gravity low: A possible expression of a large, Late Precambrian batholith intersecting the New Madrid seismic zone  

USGS Publications Warehouse

Analysis of gravity and magnetic anomaly data helps characterize the geometry and physical properties of the source of the Missouri gravity low, an important cratonic feature of substantial width (about 125 km) and length (> 600 km). Filtered anomaly maps show that this prominent feature extends NW from the Reelfoot rift to the Midcontinent Rift System. Geologic reasoning and the simultaneous inversion of the gravity and magnetic data lead to an interpretation that the gravity anomaly reflects an upper crustal, 11-km-thick batholith with either near vertical or outward dipping boundaries. Considering the modeled characteristics of the batholith, structural fabric of Missouri, and relations of the batholith with plutons and regions of alteration, a tectonic model for the formation of the batholith is proposed. The model includes a mantle plume that heated the crust during Late Precambrian and melted portions of lower and middle crust, from which the low-density granitic rocks forming the batholith were partly derived. The batholith, called the Missouri batholith, may be currently related to the release of seismic energy in the New Madrid seismic zone (earthquake concentrations occur at the intersection of the Missouri batholith and the New Madrid seismic zone). Three qualitative mechanical models are suggested to explain this relationship with seismicity. Copyright 1996 by the American Geophysical Union.

Hildenbrand, T. G.; Griscom, A.; Van Schmus, W. R.; Stuart, W. D.

1996-01-01

265

Factors responsible for increased percent recirculation in arterio-venous fistula among the haemodialysis patients.  

PubMed

Recirculation is an important issue in haemodialysis (HD) patients as increased percent recirculation causes decreased dialysis delivery of the patients. The purpose of the study was to determine the amount and factors of recirculation in those patients. The study was a cross sectional one carried in the Department of Nephrology, Dhaka Medical College and Hospital during October 2010 to September 2011. A total of 118 end stage renal disease patients with arterio-venous fistula who were on HD for more than 3 months were purposively selected. The degree of recirculation was measured with urea based two needle technique method. For each patient distances between arterial and venous and distances of needles from fistula and its directions were recorded. Echocardiography and A-V fistula Colour Doppler Ultrasound were also performed. The mean A-V fistula recirculation was 8.1 +/- 5.5% with a range 0-66%. The most common factors were close proximity and improper arterial and venous needles placement. No difference was observed between diabetic and non diabetic also between hypertensive and normotensive. A-V fistula recirculation is common occurrence in HD patients and the most common factors of recirculation are misplacement and close proximity of needles therefore emphasis should be given on education and training of HD staffs. PMID:23923409

Mahbub, T; Chowdhury, M N U; Jahan, F; Islam, M N; Khan, F M; Sikder, N H; Rahman, M

2013-04-01

266

Lycos Zone  

NSDL National Science Digital Library

In the tradition of Yahooligans (reviewed in the March 22, 1996 Scout Report) and other so-called "green spaces," Lycos has created a new online safe haven for young users which is fairly self-contained, with the exception of the advertisements. (In response to criticisms regarding aggressive marketing to children at similar sites, Lycos claims that the ads are clearly marked and will not collect any personal information.) The site is composed of four sections: the Fun and Games Zone, the Homework Zone, the New and Cool Zone, and an area for parents and teachers. The first two sections are fairly deep, with numerous resources and activities aimed at various age levels. Some links in the Homework Zone lead users outside the site, but they are first presented with a gateway page informing them that they are leaving and offering advice on not divulging personal information.

267

Effects of effluent recirculation in vertical-flow constructed wetland on treatment efficiency of livestock wastewater.  

PubMed

Enhancing the treatment efficiency of livestock wastewater by effluent recirculation is investigated in a pilot-scale vertical-flow constructed wetland. The wetland system is composed of downflow and upflow stages, on which narrow-leaf Phragmites communis and common reed Phragmites typhia are planted, respectively; each stage has a dimension of 4 m(2) (2 m x 2 m). Wastewater from the facultative pond is fed into the system intermittently at a flow rate of 0.4 m(3)/d. Recirculation rates of 0, 25%, 50%0, 100% and 150% are adopted to evaluate the effect of the recirculation rate on pollutants removal. This shows that with effluent recirculation the average removal efficiencies of NH4-N, BOD5 and SS obviously increase to 61.7%, 81.3%, and 77.1%, respectively, in comparison with the values of 35.6%o, 50.2%, and 49.3% without effluent recirculation. But the improvement of TP removal is slight, only from 42.3% to 48.9%. The variations of NH4-N, DO and oxidation-reduction potential (ORP) of inflow and outflow reveal that the adoption of effluent recirculation is beneficial to the formation of oxide environment in wetland. The exponential relationships with excellent correlation coefficients (R(2) > 0.93) are found between the removal rates of NH4-N and BOD5 and the recirculation rates. With recirculation the pH value of the outflow decreases as the alkalinity is consumed by the gradually enhanced nitrification process. When recirculation rate is kept constant at 100%, the ambient temperature appears to affect NH4-N removal, but does not have significant influence on BOD5 removal. PMID:17302314

Lian-sheng, He; Hong-liang, Liu; Bei-dou, Xi; Ying-bo, Zhu

2006-01-01

268

Coastal and synoptic recirculation affecting air pollutants dispersion: A numerical study  

NASA Astrophysics Data System (ADS)

This study examines the spatial distribution of potential recirculation over the East Mediterranean Sea, and the combined effect of synoptic and meso-scale recirculations on plume dispersion in the region. For this purpose, three case studies are performed by the RAMS-HYPACT modeling system, each for a different synoptic scale flow pattern. Both a quantitative measure of the recirculation potential at each grid cell and particle dispersion are calculated. Although the recirculation index is an Eulerian quantity for the wind field and plume dispersion is a manifestation of the Lagrangian behavior of the wind, good correlation is found between the two. Several locations are identified as having high recirculation potential, including southern Cyprus, the coasts of Israel and Lebanon, the eastern slopes of the Judean Mountains and the Haifa Bay in particular. In the latter location, high recirculation potential could be explained by strong interaction between the land-sea surfaces, curvature of the bay and proximity of the Carmel ridge. It is shown that the synoptic and meso-scale recirculations may, under certain conditions, act together and at the same time in determining particle distribution. Under weak synoptic scale flows, particles are recirculated over the entire East Mediterranean Sea basin, returning onshore after a period of 2-3 days to join freshly emitted particles. At the same time, near-shore land-sea breeze effects cause particles to recirculate on smaller time scales of less then one day, sometimes passing as much as three times over the same airshed. A single elevated emission source is shown to have the potential to impair air quality at a coastal strip as long as 100-200 km upon returning onshore.

Levy, Ilan; Mahrer, Yizhak; Dayan, Uri

269

Numerical investigation of the influence of EM-fields on fluid motion and resistivity distribution during floating-zone growth of large silicon single crystals  

NASA Astrophysics Data System (ADS)

The floating-zone-process with needle-eye inductor is a complex process with many coupled parameters that have nonlinear influence on the process stability and resistivity distribution in the silicon single crystal. To fulfill the requirements of semiconductor industry for tighter specification of resistivity distribution, additional means like magnetic fields can be used to reach a more homogeneous resistivity distribution without disturbing process stability. The current paper analyses the influence of static and alternating fields on the fluid motion and macroscopic and microscopic resistivity profile by means of numerical calculations. It is found that with a lower frequency of the HF-inductor current and with an additional AC-field the radial resistivity profile can be made more homogeneous. Rotating magnetic fields give only a slightly more homogeneous resistivity profile. DC-fields do not change the radial resistivity distribution qualitatively, but suppress all flow oscillations and therefore axial microscopic resistivity variations.

Raming, G.; Muižnieks, A.; Mühlbauer, A.

2001-08-01

270

Large-aperture fast multilevel Fresnel zone lenses in glass and ultrathin polymer films for visible and near-infrared imaging applications.  

PubMed

The ability to fabricate 4-level diffractive structures with 1 µm critical dimensions has been demonstrated for the creation of fast (?f/3.1 at 633 nm) Fresnel zone lenses (FZLs) with >60% diffraction efficiency into the -1 focusing order and nearly complete suppression of 0 and +1 orders. This is done using tooling capable of producing optics with 800 mm apertures. A 4-level grating fabricated in glass at 300 mm aperture is shown to have <15??nm rms holographic phase error. Glass FZLs have also been used as mandrels for casting zero-thermal-expansion, 20 µm thick polymer films created with the 4-level structure as a route to mass replication of efficient diffractive membranes for ultralight segmented space-based telescope applications. PMID:24787399

Britten, Jerald A; Dixit, Shamusundar N; DeBruyckere, Michael; Steadfast, Daniel; Hackett, James; Farmer, Brandon; Poe, Garrett; Patrick, Brian; Atcheson, Paul D; Domber, Jeanette L; Seltzer, Aaron

2014-04-10

271

Evidence for baroclinic instability in the Gulf Stream recirculation  

NASA Astrophysics Data System (ADS)

Long term current measurements from Polymode Array 2 are analyzed using the technique of empirical orthogonal functions applied in the frequency domain. The region of especially good instrument coverage and clearest decomposition into empirical modes is also in the Gulf Stream recirculation (? 36°N 55°W). On theoretical grounds, this is expected to be an area actively unstable to baroclinic disturbances ( GILL, GREEN and SIMMONS, 1974). Both the horizontal and vertical structure of motions with periods ranging from 10 to 120 days are studied. Spectra reveal that kinetic energy is peaked at 30 day periods with a weaker peak at 12 days. The most energetic empirical mode accounts for about 50% of the measured energy although somewhat less than this at higher subinertial frequencies. Consistent with the theoretical calculations of Gill, Green and Simmons it is found that the zonal phase propagation is nearly independent of frequency and averages about 12 cm s -1 toward the west. The 30 and 12 day energy peaks correspond to wavenumbers (wavelengths) of -0.18 km -1 (350 km) and -.033 km -1 (190 km) respectively. These are almost identical to the predicted scales for secondary and primary growth rate maxima for baroclinically unstable disturbances to a zonal current which is horizontally uniform but whose strength decreases exponentially with depth. Energy in these motions increases toward the west at a rate which is statistically indistinguishable from zero but also from the predicted rate. The vertical structure of these motions is also qualitatively similar to the theoretical modes. Phase for velocity decreases with depth, whereas temperature phase increases leading to energy release concentrated in the thermocline near the steering level which is projected to be somewhere above the shallowest observational level (600 m). The 30 day wave is much less depth dependent in amplitude than the 12 day wave and is responsible for the intense deep eddy field observed in this area by SCHMITZ (1977, 1978, 1980). At this point in the recirculation the instability process is still active and the resulting motions have not yet reached a finite amplitude state.

Hogg, Nelson G.

272

Modeling slow slip events, non-volcanic tremor and large earthquakes in the Guerrero subduction zone (Mexico) with space-variable frictional weakening and creep  

NASA Astrophysics Data System (ADS)

We explore with numerical simulations the range of conditions leading to key observed features of NVT in relation to SSE and earthquakes along the Guerrero segment of the Mexican subduction zone. The Guerrero segment is known to produce some of the largest slow slip events (SSE) recorded so far with equivalent magnitude up to 7.5 Mw. These SSE, with apparent durations of about 4 years, are accompanied by strong activity of Non Volcanic Tremor (NVT) in central Guerrero. Recently, NVT triggered by the 8.8 Mw Maule earthquake were also been reported in that region. The geometry of the Guerrero subduction zone remains sub-horizontal between 150 km to 250 km from the coast, making it easy to model with a simple flat frictional interface. We use a model with a planar interface governed by space-varying static/kinetic friction and dislocation creep in elastic solid. The model is tailored through the employed dimensions, distribution of rheological properties and boundary conditions to the Guerrero segment, with particular attention to conditions of the past 15 years for which observations are available. A section of the fault with zero weakening during frictional slip fails in a mode corresponding to a "critical depinning transition" that produces many observed features of NVT. When a high creep patch representing a section sustaining SSE is added, strong interactions between NVT and SSE are observed as in the natural fault system. We also examine triggering of NVT by larger remote earthquakes, implemented by adding periodic triggering oscillations to the regular tectonic loading. In addition to modeling observations of NVT and SSE made in Guerrero during the past 15 years, the simulations allow us to distinguish aspects of the observed behavior that are robust over long time intervals from aspects that change during intervals longer than the observational period.

Zigone, D.; Ben-Zion, Y.; Campillo, M.

2012-12-01

273

Equipment review: The molecular adsorbents recirculating system (MARS®)  

PubMed Central

The molecular adsorbents recirculating system (MARS®) is a form of artificial liver support that has the potential to remove substantial quantities of albumin-bound toxins that have been postulated to contribute to the pathogenesis of liver cell damage, haemodynamic instability and multi-organ failure in patients with acute liver failure (ALF) and acute-on-chronic liver failure (AoCLF). These toxins include fatty acids, bile acids, tryptophan, bilirubin, aromatic amino acids and nitric oxide. Data from controlled clinical trials are limited so far. One of two studies performed on small numbers of patients with AoCLF suggest a survival benefit, but no controlled data are available in the ALF setting. Our preliminary experience with MARS therapy, instituted late in the clinical course of five patients with severely impaired liver function, including three with AoCLF precipitated by sepsis and two with liver dysfunction due to sepsis in the absence of pre-existing chronic liver disease, indicates some clinical efficacy. However, the overall survival rate (1 of 5; 20%) remained poor. More data obtained from larger cohorts of patients enrolled in randomised controlled studies will be required in both the AoCLF and ALF settings to identify categories of liver failure patients who might benefit most from MARS treatment, to ascertain the most appropriate timing of intervention and to determine the overall impact on outcome, including cost-effectiveness.

Boyle, Martin; Kurtovic, Jelica; Bihari, David; Riordan, Stephen; Steiner, Christian

2004-01-01

274

Recirculating 1-K-Pot for Pulse-Tube Cryostats  

NASA Technical Reports Server (NTRS)

A paper describes a 1-K-pot that works with a commercial pulse tube cooler for astrophysics instrumentation testbeds that require temperatures <1.7 K. Pumped liquid helium-4 cryostats were commonly used to achieve this temperature. However, liquid helium-4 cryostats are being replaced with cryostats using pulse tube coolers. The closed-cycle 1K-pot system for the pulse tube cooler requires a heat exchanger on the pulse tube, a flow restriction, pump-out line, and pump system that recirculates helium-4. The heat exchanger precools and liquefies helium- 4 gas at the 2.5 to 3.5 K pulse tube cold head. This closed-cycle 1-K-pot system was designed to work with commercially available laboratory pulse tube coolers. It was built using common laboratory equipment such as stainless steel tubing and a mechanical pump. The system is self-contained and requires only common wall power to operate. The lift of 15 mW at 1.1 K and base temperature of 0.97 K are provided continuously. The system can be scaled to higher heat lifts of .30 to 50 mW if desired. Ground-based telescopes could use this innovation to improve the efficiency of existing cryo

Paine, Christopher T.; Naylor, Bret J.; Prouve, Thomas

2013-01-01

275

Design of a computerized, temperature-controlled, recirculating aquaria system  

USGS Publications Warehouse

We built a recirculating aquaria system with computerized temperature control to maintain static temperatures, increase temperatures 1 ??C/day, and maintain diel temperature fluctuations up to 10 ??C. A LabVIEW program compared the temperature recorded by thermocouples in fish tanks to a desired set temperature and then calculated the amount of hot or cold water to add to tanks to reach or maintain the desired temperature. Intellifaucet?? three-way mixing valves controlled temperature of the input water and ensured that all fish tanks had the same turnover rate. The system was analyzed over a period of 50 days and was fully functional for 96% of that time. Six different temperature treatments were run simultaneously in 18, 72 L fish tanks and temperatures stayed within 0.5 ??C of set temperature. We used the system to determine the upper temperature tolerance of fishes, but it could be used in aquaculture, ecological studies, or other aquatic work where temperature control is required. ?? 2005 Elsevier B.V. All rights reserved.

Widmer, A. M.; Carveth, C. J.; Keffler, J. W.; Bonar, S. A.

2006-01-01

276

In situ treatment of VOCs by recirculation technologies  

SciTech Connect

The project described herein was conducted by Oak Ridge National Laboratory (ORNL) to identify processes and technologies developed in Germany that appeared to have near-term potential for enhancing the cleanup of volatile organic compound (VOC) contaminated soil and groundwater at DOE sites. Members of the ORNL research team identified and evaluated selected German technologies developed at or in association with the University of Karlsruhe (UoK) for in situ treatment of VOC contaminated soils and groundwater. Project activities included contacts with researchers within three departments of the UoK (i.e., Applied Geology, Hydromechanics, and Soil and Foundation Engineering) during fall 1991 and subsequent visits to UoK and private industry collaborators during February 1992. Subsequent analyses consisted of engineering computations, groundwater flow modeling, and treatment process modeling. As a result of these project efforts, two processes were identified as having near-term potential for DOE: (1) the vacuum vaporizer well/groundwater recirculation well and (2) the porous pipe/horizontal well. This document was prepared to summarize the methods and results of the assessment activities completed during the initial year of the project. The project is still ongoing, so not all facets of the effort are completely described in this document. Recommendations for laboratory and field experiments are provided.

Siegrist, R.L.; Webb, O.F.; Ally, M.R.; Sanford, W.E. [Oak Ridge National Lab., TN (US); Kearl, P.M.; Zutman, J.L. [Oak Ridge National Lab., Grand Junction, CO (US)

1993-06-01

277

Further studies on beam breakup growth reduction by cavity cross-couplings in recirculating accelerators: effects of long pulse length and multiturn recirculation  

NASA Astrophysics Data System (ADS)

Cavity cross-coupling was recently found to reduce beam breakup (BBU) growth in a recirculating accelerator known as the Spiral Line Induction Accelerator (SLIA). Here, we extend the analyses in two respects: long beam pulse lengths and a SLIA upgrade geometry which accelerates a 10 kA, 35 ns beam to 25 MeV via a 70 cavity, 7 turn recirculation. We found that when the beam pulse length ? exceeds the beam's transit time ?' between cross-coupled cavities. BBU growth may be worsened as a result of the cross-couplings among cavities. This situation is not unlike other long pulse recirculating accelerators where beam recirculation leads to beam breakup of a regenative type. Thus, the advantage of BBU reduction by cavity cross-coupling is restricted primarily to beams with ?recirculation. For Q?20, BBU growth reduction by factors of hundreds is observed, but this reduction is insensitive to the sequence of beam recirculation. The above conclusions were based on simple models of cavity coupling that have been used in conventional microwave literature. Not addressed is the detail design consideration that leads to the desired degree of cavity coupling.

Colombant, D.; Lau, Y. Y.

1992-01-01

278

Concept for powering the dipole magnet in a recirculating induction accelerator for heavy ion fusion.  

National Technical Information Service (NTIS)

In a Recirculating Heavy Ion Fusion Induction Accelerator the largest energy consumption occurs in the bending magnetic fields. Because these fields are pulsed, they cannot be generated by superconducting magnets. The bending magnets will consist of iron ...

L. Reginato M. Newton S. Yu

1990-01-01

279

Leachate Recirculation at the Nanticoke Sanitary Landfill Using a Bioreactor Trench.  

National Technical Information Service (NTIS)

A one-year landfill leachate recirculation demonstration project was conducted in a 20-acre cell at the Broome County, NY, Nanticoke Landfill using a retrofit bioreactor trench design concept to introduce landfill leachate to the surrounding refuse mass. ...

J. J. Pagano R. J. Scrudato G. M. Sumner

1998-01-01

280

High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays  

SciTech Connect

Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

Jovanovic, I; Shverdin, M; Gibson, D; Brown, C

2007-04-17

281

Cascadia Subduction Zone  

USGS Publications Warehouse

The geometry and recurrence times of large earthquakes associated with the Cascadia Subduction Zone (CSZ) were discussed and debated at a March 28-29, 2006 Pacific Northwest workshop for the USGS National Seismic Hazard Maps. The CSZ is modeled from Cape Mendocino in California to Vancouver Island in British Columbia. We include the same geometry and weighting scheme as was used in the 2002 model (Frankel and others, 2002) based on thermal constraints (Fig. 1; Fluck and others, 1997 and a reexamination by Wang et al., 2003, Fig. 11, eastern edge of intermediate shading). This scheme includes four possibilities for the lower (eastern) limit of seismic rupture: the base of elastic zone (weight 0.1), the base of transition zone (weight 0.2), the midpoint of the transition zone (weight 0.2), and a model with a long north-south segment at 123.8? W in the southern and central portions of the CSZ, with a dogleg to the northwest in the northern portion of the zone (weight 0.5). The latter model was derived from the approximate average longitude of the contour of the 30 km depth of the CSZ as modeled by Fluck et al. (1997). A global study of the maximum depth of thrust earthquakes on subduction zones by Tichelaar and Ruff (1993) indicated maximum depths of about 40 km for most of the subduction zones studied, although the Mexican subduction zone had a maximum depth of about 25 km (R. LaForge, pers. comm., 2006). The recent inversion of GPS data by McCaffrey et al. (2007) shows a significant amount of coupling (a coupling factor of 0.2-0.3) as far east as 123.8? West in some portions of the CSZ. Both of these lines of evidence lend support to the model with a north-south segment at 123.8? W.

Frankel, Arthur D.; Petersen, Mark D.

2008-01-01

282

Picosecond Pulse Recirculation for High Average Brightness Thomson Scattering-based Gamma-ray Sources  

SciTech Connect

Pulse recirculation has been successfully demonstrated with the interaction laser system of LLNL's Thomson-Radiated Extreme X-ray (T-REX) source. The recirculation increased twenty-eight times the intensity of the light coming out of the laser system, demonstrating the capability of increasing the gamma-ray flux emitted by T-REX. The technical approach demonstrated could conceivably increase the average gamma-ray flux output by up to a hundred times.

Semenov, V

2009-05-28

283

KE basin recirculation/skimmer/IX systems restart acceptance test report  

SciTech Connect

The 105 KE Basin Recirculation System and Skimmer Loop have been upgraded to provide the flexibility to run the Ion Exchange Modules on either system to support spent fuel removal for the Spent Nuclear Fuel Project. This Acceptance Test Report Provides the documentation of the leak Testing for the construction work associated with the IXM inlet and outlet piping, places the cartridge filters back in service and provides the functional testing of the IXM`s on the recirculation and skimmer systems.

Derosa, D.C.

1996-03-27

284

Investigation over the recirculation influence on the combustion of micro organic dust particles  

Microsoft Academic Search

This paper investigates the role of recirculation and non-unity Lewis number on the combustion of organic dust particles.\\u000a Since recirculation effect is more noticeable in micro-combustors, it is necessary to propose a modeling approach of this\\u000a phenomenon to better simulate the performance of micro-combustors. In this research, in order to model the combustion of organic\\u000a dust particles, it is assumed

M. Bidabadi; A. Fanaee; A. Rahbari

2010-01-01

285

Large Pore Ion and Metabolite-Permeable Channel Regulation of Postnatal Ventricular Zone Neural Stem and Progenitor Cells: Interplay between Aquaporins, Connexins, and Pannexins?  

PubMed Central

The birth of new neurons from unspecialized neural stem and progenitor cells surrounding the lateral ventricles occurs throughout postnatal life. This process, termed neurogenesis, is complex and multistepped, encompassing several types of cellular behaviours, such as proliferation, differentiation, and migration. These behaviours are influenced by numerous factors present in the unique, permissive microenvironment. A major cellular mechanism for sensing the plethora of environmental cues directing this process is the presence of different channel forming proteins spanning the plasma membrane. So-called large pore membrane channels, which are selective for the passage of specific types of small molecules and ions, are emerging as an important subgroup of channel proteins. Here, we focus on the roles of three such large pore channels, aquaporin 4, connexin 43, and pannexin 1. We highlight both their independent functions as well as the accumulating evidence for crosstalk between them.

Wicki-Stordeur, Leigh E.; Swayne, Leigh Anne

2012-01-01

286

Stress fields during the evolution of large-scale strike-slip systems and tectonic slivers, Atacama Fault Zone, northern Chile  

Microsoft Academic Search

Tectonic evolution of crustal slivers generated during oblique subduction involves a series of translations and rotations. Slivers are defined by large-scale strike-slip faults, whereas internal blocks are by the faulting pattern related to the fault system. Translations and rotations are then likely to accommodate the internal deformation caused by external forces. The Atacama Fault System (AFS), a crustal-scale strike-slip fault

E. E. Veloso; R. Gomila

2009-01-01

287

Ionospheric effects near the magnetic equator and the anomaly crest of the Indian longitude zone during a large number of intense geomagnetic storms  

NASA Astrophysics Data System (ADS)

Ionospheric effects of a large number (51) of severe geomagnetic storms are studied using total electron content (TEC) and VHF/UHF scintillation data from Calcutta, situated near the northern crest of equatorial ionization anomaly and equatorial spread-F (ESF) data from Kodaikanal. The susceptibility of the equatorial ionosphere to develop storm time plasma density irregularities responsible for ESF and scintillation is found to be largely modulated by the local times of occurrences of main and recovery phases as seen in the Dst index. While inhibition of premidnight scintillation for lower TEC values compared to the quiet day averages is omnipresent, occurrence of scintillation for enhancements of TEC is largely dependent on initiation time and amplitude of the said deviations. An overall reduction in threshold values of h?F for observing storm induced ESF and scintillation compared to reported quiet time values is noted. The results are discussed in terms of storm time variabilities in electric fields, neutral wind system and composition changes.

Hajra, R.; Chakraborty, S. K.; Dasgupta, A.

2010-11-01

288

Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary Formations  

SciTech Connect

There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. Terralog USA, in collaboration with the University of California, Irvine (UCI), are currently investigating advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. This two-year research project, funded by the US Department of Energy, includes combined efforts for: 1) Resource characterization; 2) Small and large scale laboratory investigations; 3) Numerical simulation at both the laboratory and field scale; and 4) Engineering feasibility studies and economic evaluations. The research project is currently in its early stages. This paper summarizes our technical approach and preliminary findings related to potential resources, small-scale laboratory simulation, and supporting numerical simulation efforts.

Mike Bruno; Russell L. Detwiler; Kang Lao; Vahid Serajian; Jean Elkhoury; Julia Diessl; Nicky White

2012-09-30

289

Ornithinimicrobium tianjinense sp. nov., isolated from a recirculating aquaculture system.  

PubMed

A Gram-positive, strictly aerobic and heterotrophic, non-spore-forming actinobacterium (strain B2(T)) isolated from a recirculating aquaculture system was studied for its taxonomic position. Strain B2(T) formed a rudimentary substrate-mycelium that fragmented into short rod-shaped to coccoid cells (0.5 µm×0.5-2.2 µm or 0.5-1.0 µm in diameter). Colonies were yellow, smooth, circular and 1.5-2.0 mm in diameter after incubation on TSA for 3 days at 30 °C. Strain B2(T) grew at 20-40 °C (optimal, 30 °C) and pH 5.5-9.5 (optimal, 6.5-7.0) and in the presence of 0-9% (w/v) NaCl (optimal, 1%). The predominant menaquinone of strain B2(T) was MK-8(H4). The cell-wall peptidoglycan of strain B2(T) contained the amino acids ornithine, glutamic acid, alanine, glycine and aspartic acid. The major polar lipids were phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were iso-C15?:?0, iso-C16?:?0 and summed feature 9. Its DNA G+C content was 68.3 mol% (Tm). Analysis of 16S rRNA gene sequences indicated that strain B2(T) was related phylogenetically to members of the genus Ornithinimicrobium with highest similarity (96.6?%) to Ornithinimicrobium kibberense DSM 17687(T), followed by Ornithinimicrobium humiphilum DSM 12362(T) (96.3?%), Ornithinimicrobium pekingense LW6(T) (96.2%) and Ornithinimicrobium murale 01-Gi-040(T) (94.8%). On basis of phenotypic, chemotaxonomic and phylogenetic data, it was concluded that strain B2(T) represents a novel species of the genus Ornithinimicrobium, for which the name Ornithinimicrobium tianjinense sp. nov. is proposed. The type strain is B2(T) (?=CGMCC 1.12160(T)?=JCM 18464(T)). PMID:23907216

Liu, Liang-Zi; Liu, Ying; Chen, Zhu; Liu, Hong-Can; Zhou, Yu-Guang; Liu, Zhi-Pei

2013-12-01

290

Closed recirculating system for shrimp-mollusk polyculture  

NASA Astrophysics Data System (ADS)

This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle, water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation. Constricted tagelus, Sinonovacula constricta, was selected as the cultured mollusk, and Pacific white shrimp, Litopenaeus vannamei, as the cultured shrimp. The main managing measures during the production cycle were: setting and using the aerators; introducting the probiotic products timely into the shrimp ponds; adopting a “pen-closing” method for controlling shrimp viral epidemics; setting the flow diversion barriers in the mollusk pond to keep the circulating water flowing through the pond along a sine-like curve and serve as substrate for biofilm; no direct feeding was necessary for the cultured mollusk until the co-cultured shrimp was harvested; natural foods in the water from the shrimp ponds was used for their foods. Two sets of the system were used in the experiment in 2002 and satisfactory results were achieved. The average yield of the shrimp was 11 943.5 kg/hm2, and that of the mollusk was 16 965 kg/hm2. After converting the mollusk yield into shrimp yield at their market price ratio, the food coefficient of the entire system averaged at as low as 0.81. The water quality in the ponds was maintained at a desirable level and no viral epidemics were discovered during the production cycle.

Wu, Xiongfei; Zhao, Zhidong; Li, Deshang; Chang, Kangmei; Tong, Zhuanshang; Si, Liegang; Xu, Kaichong; Ge, Bailin

2005-12-01

291

Photobacterium aquae sp. nov., isolated from a recirculating mariculture system.  

PubMed

A Gram-staining-negative, heterotrophic, facultatively anaerobic bacterium, designated AE6(T), was isolated from a grouper (Epinephelus malabaricas) culture tank in a recirculating mariculture system located in Tianjin, China. Strain AE6(T) was able to grow at 15-40 °C (optimum, 30-35 °C), at pH 5.5-10.0 (optimum, pH 7.0-7.5) and in the presence of 0.5-7% (w/v) NaCl (optimum, 2-3%). It contained Q-8 as the predominant respiratory quinone, phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) as the major polar lipids and C(16 : 1)?7c/C(16 : 1)?6c (40.4%), C(18 : 1)?7c (15.5%) and C(16 : 0) (13.5%) as the predominant cellular fatty acids. The genomic DNA G+C content was 47.1 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain AE6(T) belonged to the genus Photobacterium (94.2-96.8% of 16S rRNA gene sequence similarity) and formed a distinct phylogenetic lineage within the genus and exhibited the highest sequence similarity to Photobacterium aphoticum CECT 7614(T) (96.8%). Multilocus sequence analysis (MLSA) using four loci (gyrB, rpoA, pyrH and recA) also revealed that strain AE6(T) was phylogenetically related to the genus Photobacterium. Based on the phylogenetic, chemotaxonomic and phenotypic evidence, strain AE6(T) is considered to represent a novel species of the genus Photobacterium, for which the name Photobacterium aquae sp. nov. is proposed. The type strain is AE6(T) (?=?CGMCC 1.12159(T)?=?JCM 18480(T)). PMID:24096359

Liu, Ying; Liu, Liang-Zi; Song, Lei; Zhou, Yu-Guang; Qi, Fang-Jun; Liu, Zhi-Pei

2014-02-01

292

Constructed wetlands as recirculation filters in large-scale shrimp aquaculture  

Microsoft Academic Search

Effluent waters from shrimp aquaculture, which can contain elevated levels of phosphorus, ammonia, nitrate, and organics, must be managed properly if shrimp aquaculture is to achieve sustainability. Constructed wetlands are ecologically beneficial, low cost treatment alternatives proven capable of reducing suspended solids, biochemical oxygen demand (BOD), nitrogen, phosphorus and heavy metals from wastewater of many sources. The goal of this

David Rogers Tilley; Harish Badrinarayanan; Ronald Rosati; Jiho Son

2002-01-01

293

Further Studies on Beam Breakup Growth Reduction by Cavity Cross-Couplings in Recirculating Accelerators: Effects of Long Pulse Length and Multiturn Recirculation.  

National Technical Information Service (NTIS)

Cavity cross-coupling was recently found to reduce beam breakup (BBU) growth in a recirculating accelerator known as the Spiral LIne Induction Accelerator (SLIA). Here, we extend the analyses in two respects: long beam pulse lengths and a SLIA upgrade geo...

D. Colombant Y. Y. Lau

1991-01-01

294

Design and Simulation of a Recirculating Bed Reactor for Coal Hydrogasification. Final Report, Part I. Recirculating Bed Hydrogasifier Conceptual Design and Simulation Results.  

National Technical Information Service (NTIS)

Part I of this report presents a conceptual design of a recirculating bed hydrogasifier. The reactor is designed to operate at 1800 exp 0 F and 44 atm on hydrogen, and it would convert 63% of coal carbon. A mechanical design is presented which utilizes U-...

T. W. Bierl L. J. Bajdos A. E. McIver

1980-01-01

295

Large eddy simulation of blowout of a bluff-body stabilized flame in a duct  

NASA Astrophysics Data System (ADS)

The blowout of a flame that is anchored within a duct by a flat plate is examined by means of large-eddy simulations (LESs) to study the vortex/chemical/acoustical interactions which produce transient effects. The suitability of the model is demonstrated by performing the LES with a finite-volume CFD code that had been used to model subgrid turbulence. Isothermal and reacting flows are investigated with calculations for progressively lowered equivalence ratios (ERs). Isothermal flow vortices are found to shed from the plate's corners at a fixed frequency, and reacting flows related to a one-step combustion model become steady behind the flameholder when the ER is near unity. The heat associated with reacting flows decreases and vortex shedding begins to be generated as the ER is reduced. The blowout of the flame is caused by vortical gas motion at the end of the recirculation zone.

Leonard, Andy D.; Smith, Clifford E.; van Erp, Chris

1991-06-01

296

Kink zone localization, structurally-controlled instability, and large-scale rock slope failure at the Mt. Gorsa porphyry quarry (Trentino, Italy)  

NASA Astrophysics Data System (ADS)

Rock slope failure is controlled by rock mass strength and anisotropy, and by slope-scale persistent fractures with different spacing, eventually resulting in complex mechanisms as large-scale flexural toppling, block toppling, and kink band slumping. Despite these mechanisms have been studied, their interplay in large rock slope failure is often difficult to ascertain in complex geological settings. We studied the 250 m high porphyry quarry slopes of Mt. Gorsa (Trentino, Italy). Two slopes facing to N and E are carved in Permian rhyolithic ignimbrites, providing spectacular exposures of the inherited geological structure. Despite the strong intact rock, rock mass has a complex structure due to the occurrence of thermal cooling joints, persistent tectonic fractures, and joint sets. Evidence of ongoing displacement of the northern quarry face in 2003 motivated geotechnical and geophysical site investigation, and the initiation of displacement monitoring activities. GB-InSAR measurements using a LiSALab system captured large-scale slope dilation involving 400.000 m3. Further GB-InSAR measurements have been carried out since 2010. In order to understand the mechanisms governing large-scale deformation and failure of the northern slope, we carried out a comprehensive field and modelling study exploiting terrestrial photo mapping, field structural analysis and discontinuity surveys at different locations. On the northern face, 190 Geological Strength Index (GSI) surveys along benches, DEM structural analysis (COLTOP3D), and analysis of GB-InSAR data were carried out, and relationships among rock mass quality, 2003 landslide extent, and measured displacements established. Data show that slope instability is locally constrained by close and persistent cooling joints steeply dipping to the south (K1), persistent fault surfaces moderately dipping to the NNW (K2), and joint sets steeply dipping to NE and WNW (K3 and K4). NNW-dipping, top-to-N kink bands up to 2m wide also occur at depth and are exposed on the eastern slope. Close to the northern quarry face, structurally-controlled instabilities (sliding, flexural toppling, block toppling) occur inside individual kinematic domains ranging from tens to thousands cubic meters, leading to significant rock mass degradation (GSI < 35-40) and to disintegrated and weathered rock masses in areas undergoing largest displacements. We investigated the links between local structurally-controlled failure and large-scale rock slope failure using different Finite-Element modelling approaches implemented in the softwares Phase2 v.8 (Rocscience Inc.) and ELFEN (Rockfield Inc.). Performed modelling tasks include: continuum models (Phase, ELFEN), continuum-based jointed rock models (Phase), and hybrid continuum-discrete models (ELFEN). A continuum-based SSR (Shear Strength reduction) back-analysis of the 2003 instability, calibrated on landslide geometry and GB-InSAR displacements, shows that reduced rock mass properties (GSI < 35-40) observed where local-scale structurally-controlled instability occurs, were a pre-requisite for the 2003 global slope instability. Jointed rock and hybrid models suggest that slope excavation results in shear strain localisation along inherited fault surfaces and newly-formed kink bands at different depths. At depths less than some tens of meters, these interact with K1 resulting in step-path failure surfaces, sliding and toppling. Globally, these processes result in dilation and rock mass damage, which in turn promote the required conditions for global slope failure.

Agliardi, F.; Crosta, G. B.; Meloni, F.; Valle, C.; Rivolta, C.; Leva, D.

2012-04-01

297

Exhaust gas recirculation control method and apparatus for internal combustion engine  

SciTech Connect

An exhaust gas recirculation control method is described for operating an exhaust gas recirculation control device including a needle valve provided in an exhaust gas recirculation passage for setting an effective diameter of the passage, a position sensor for providing a signal representing a position of the needle valve, and a negative pressure motor for positioning the needle valve. The method comprises: setting a target value for the needle valve according to predetermined operating conditions of the internal combustion engine; measuring a positional deviation between the target value and an actual position of the needle valve as represented by the signal provided by the position sensor; and driving the negative pressure motor with only a single drive pulse having a time width corresponding to the measured positional deviation. An exhaust gas recirculation control apparatus is described for operating an exhaust gas recirculation control device. The apparatus comprises: means for setting a target value for the needle valve according to predetermined operating conditions of the internal combustion engine; and means for measuring a positional deviation between the target value and an actual position of the needle valve as represented by the signal provided by the position sensor.

Tsutsumi, K.

1987-02-10

298

Diversity and Phylogenetic Affiliations of Morphologically Conspicuous Large Filamentous Bacteria Occurring in the Pelagic Zones of a Broad Spectrum of Freshwater Habitats  

PubMed Central

Filamentous bacteria with a conspicuous morphology were found in the majority of the bacterioplankton samples from a variety of freshwater habitats that were studied. These heterotrophic filaments typically account for <1 to 11% of the total number of bacteria. The biovolume of this morphotype can exceed 40% of the biovolume for all bacteria. Surprisingly, we found hardly any data on these morphologically conspicuous filaments in the literature. Mixed cultures containing these filamentous bacteria were established by cultivation and isolation experiments with samples from different freshwater lakes. Nearly full-length 16S rRNA gene sequences were obtained from several mixed cultures and environmental samples from habitats in Europe, Africa, China, Australia, and New Zealand. Phylogenetic analysis of the sequences showed that three groups form a single monophyletic cluster, the SOL cluster, in the family Saprospiraceae. We developed a set of six nested probes for fluorescence in situ hybridization. Of the six probes, one probe was specific for Haliscomenobacter hydrossis, three probes were specific for the three subclusters (each probe was specific for one subcluster), one probe was specific for the entire SOL cluster, and another probe targeted almost the entire Saprospiraceae family. Specific hybridization of environmental samples and enrichments showed that the members of the three subclusters exhibited the same filamentous morphology. So far, using the subcluster-specific probes, we have not been able to detect any bacteria with a differing morphology. We conclude that the SOL cluster bacteria are an integral part of bacterioplankton in many freshwater habitats. They potentially account for a large fraction of the total bacterial biomass but have been underrepresented in molecular diversity studies so far.

Schauer, Michael; Hahn, Martin W.

2005-01-01

299

Resolving the Effects of Aperture and Volume Restriction of the Flow by Semi-Porous Barriers Using Large-Eddy Simulations  

NASA Astrophysics Data System (ADS)

The Regional Atmospheric Modelling System (RAMS)-based Forest Large-Eddy Simulation (RAFLES) model is used to simulate the effects of large rectangular prism-shaped semi-porous barriers of varying densities under neutrally buoyant conditions. RAFLES model resolves flows inside and above forested canopies and other semi-porous barriers, and it accounts for barrier-induced drag on the flow and surface flux exchange between the barrier and the air. Unlike most other models, RAFLES model also accounts for the barrier-induced volume and aperture restriction via a modified version of the cut-cell coordinate system. We explicitly tested the effects of the numerical representation of volume restriction, independent of the effects of the drag, by comparing drag-only simulations (where we prescribed neither volume nor aperture restrictions to the flow), restriction-only simulations (where we prescribed no drag), and control simulations where both drag and volume plus aperture restrictions were included. Previous modelling and empirical work have revealed the development of important areas of increased uplift upwind of forward-facing steps, and recirculation zones downwind of backward-facing steps. Our simulations show that representation of the effects of the volume and aperture restriction due to the presence of semi-porous barriers leads to differences in the strengths and locations of increased-updraft and recirculation zones, and the length and strength of impact and adjustment zones when compared to simulation solutions with a drag-only representation. These are mostly driven by differences to the momentum budget of the streamwise wind velocity by resolved turbulence and pressure gradient fields around the front and back edges of the barrier. We propose that volume plus aperture restriction is an important component of the flow system in semi-porous environments such as forests and cities and should be considered by large-eddy simulation (LES).

Chatziefstratiou, Efthalia K.; Velissariou, Vasilia; Bohrer, Gil

2014-04-01

300

Stress fields during the evolution of large-scale strike-slip systems and tectonic slivers, Atacama Fault Zone, northern Chile  

NASA Astrophysics Data System (ADS)

Tectonic evolution of crustal slivers generated during oblique subduction involves a series of translations and rotations. Slivers are defined by large-scale strike-slip faults, whereas internal blocks are by the faulting pattern related to the fault system. Translations and rotations are then likely to accommodate the internal deformation caused by external forces. The Atacama Fault System (AFS), a crustal-scale strike-slip fault in northern Chile, can be divided into three concave, oceanward segments, that show sinestral (Mesozoic) and normal (Cenozoic) displacements. Clockwise rotations of ca. 50° have been suggested for the AFS, mostly for the northernmost segment. The Paposo segment defines a sliver of 160 km long and 25 km wide. In the northern part, it exhibits intense internal faulting, duplexes, single- and multiple-core faults. To determine the stress field responsible for the development and evolution of the sliver, we measured 162 brittle fault planes on which we determined the sense and direction of maximum shear. Fault planes show a main NW-SE trend and subvertical dip-angles (Fig. 1). Brittle kinematic indicators indicate subhorizontal (sinestral) and subvertical (normal) movements. Fault-slip data was processed with the multiple inverse method. Input parameters were k=5 (grouping), e=9 (enhance) and d=1 (dispersion). Calculations show that ?1 axes are distributed on a NW-SE trending great-circle whereas ?3 axes are clustered near the horizontal in NE and SW orientations. Stress ratios average 0.55±0.20. In the horizontal, ?1 axes cover an arc of about 30° and ?3 axes cover about 60° (Fig. 1), suggesting a strike-slip stress field. On the contrary, the subvertical cluster of ?1 axes suggests a normal stress field. These analyses indicate that the Paposo Sliver developed during a period of NW-SE compression and NE-SW tension. The wide distribution of the tensile axes may denote rotation of the internal blocks to accommodate the deformation or an unsteady orientation of the main axis. However, previously proposed clockwise rotations within the Paposo sliver are few and scarce. We hypothesize that future detailed paleomagnetic work can unravel the block rotation pattern and the style of internal accommodation within the sliver.

Veloso, E. E.; Gomila, R.

2009-12-01

301

Recurrent amoebic gill infestation in rainbow trout cultured in a semiclosed water recirculation system  

USGS Publications Warehouse

Five lots of commercially purchased juvenile rainbow trout Oncorhynchus mykiss (17-44 g) stocked in a continuous-production water recirculation system became infested with gilt amoebae. The amoebae were introduced into the recirculation system, as evidenced by their presence on gills of fish held in quarantine tanks. Based on their morphology, as seen in histological sections and by electron microscopy, the amoebae appeared to be more closely related to the family Cochliopodiidae than to other taxa of free living amoebae. Attempts to culture the amoebae in different media, at different temperatures of incubation, and in fish cell culture were not successful. Initial treatment of the recirculation system with formalin at 167 parts per million (ppm) for 1 h eliminated amoebae from the gills. Subsequent treatments of the entire system with formalin at 50-167 ppm reduced the intensity of further infestations.

Noble, A. C.; Herman, R. L.; Noga, E. J.; Bullock, G. L.

1997-01-01

302

Zoning Ordinance, Brandon, Mississippi.  

National Technical Information Service (NTIS)

The Zoning Ordinance divides the City of Brandon, State of Mississippi into zoning districts. The Zoning Ordinance contains, in addition to the Zoning districts, regulations regarding non-conforming uses and structures along with signs and outdoor commerc...

1972-01-01

303

Methane emissions from MSW landfill with sandy soil covers under leachate recirculation and subsurface irrigation  

NASA Astrophysics Data System (ADS)

CH 4 emissions and leachate disposal are recognized as the two major concerns in municipal solid waste (MSW) landfills. Recently, leachate recirculation was attempted to accelerate land-filled waste biodegradation and thus enhanced landfill gas generation. Leachate irrigation was also conducted for volume reduction effectively. Nevertheless, the impacts of leachate recirculation and irrigation on landfill CH 4 emissions have not been previously reported. A field investigation of landfill CH 4 emissions was conducted on selected sandy soil cover with leachate recirculation and subsurface irrigation based on whole year around measurement. The average CH 4 fluxes were 311±903, 207±516, and 565±1460 CH 4 m -2 h -1 from site A without leachate recirculation and subsurface irrigation, lift B2 with leachate subsurface irrigation, and lift B1 with both leachate recirculation and subsurface irrigation, respectively. Both gas recovery and cover soil oxidation minimized CH 4 emissions efficiently, while the later might be more pronounced when the location was more than 5 m away from gas recovery well. After covered by additional clay soil layer, CH 4 fluxes dropped by approximately 35 times in the following three seasons compared to the previous three seasons in lift B2. The diurnal peaks of CH 4 fluxes occurred mostly followed with air or soil temperature in the daytimes. The measured CH 4 fluxes were much lower than those of documented data from the landfills, indicating that the influences of leachate recirculation and subsurface irrigation on landfill CH 4 emissions might be minimized with the help of a well-designed sandy soil cover. Landfill cover composed of two soil layers (clay soil underneath and sandy soil above) is suggested as a low-cost and effective alternative to minimize CH 4 emissions.

Zhang, Houhu; He, Pinjing; Shao, Liming

304

Effect of recirculation on organic matter removal in a hybrid constructed wetland system.  

PubMed

This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, average removal efficiencies for TSCW were 91 +/- 4% for COD, 83 +/- 10% for BOD and 96 +/- 3% for suspended solids with average effluent concentrations of 9 +/- 5 mg/L COD, 6 +/- 3 mg/L BOD and 1 mg/L for suspended solids. Comparing non-recirculation and recirculation periods, the lowest effluent concentrations were obtained with a 100% recirculation ratio. The effluent concentrations met the Turkish regulations for discharge limits of COD, BOD and TSS in each case. The study showed that a hybrid constructed wetland system with recirculation is a very effective method of obtaining very low effluent organic matter and suspended solids concentrations downstream of anaerobic pretreatment of domestic wastewaters in small communities. PMID:21977661

Ayaz, S C; Findik, N; Akça, L; Erdo?an, N; Kinaci, C

2011-01-01

305

Large eddy simulation of the unsteady flow-field in an idealized human mouth-throat configuration.  

PubMed

The present study concerns the simulation and analysis of the flow field in the upper human respiratory system in order to gain an improved understanding of the complex flow field with respect to the process affecting drug delivery for medical treatment of the human air system. For this purpose, large eddy simulation (LES) is chosen because of its powerful performance in the transitional range of laminar and turbulent flow fields. The average gas velocity in a constricted tube is compared with experimental data (Ahmed and Giddens, 1983) and numerical data from Reynolds-averaged Navier-Stokes (RANS) equations coupled with low Reynolds number (LRN) ?-? model (Zhang and Kleinstreuer, 2003) and LRN shear-stress transport ?-? model (Jayaraju et al., 2007), for model validation. The present study emphasizes on the instantaneous flow field, where the simulations capture different scales of secondary vortices in different flow zones including recirculation zones, the laryngeal jet zone, the mixing zone, and the wall shear layer. It is observed that the laryngeal jet tail breaks up, and the unsteady motion of laryngeal jet is coupled with the unsteady distribution of secondary vortices in the jet boundary. The present results show that it is essential to study the unsteady flow field since it strongly affects the particle flow in the human upper respiratory system associated with drug delivery for medical treatment. PMID:21937045

Cui, X G; Gutheil, E

2011-11-10

306

Cleaning and recirculation of perfluorohexane (C 6F 14) in the STAR-RICH detector  

NASA Astrophysics Data System (ADS)

A RICH detector with a CsI photo-cathode and liquid perfluorohexane radiator has been installed in the STAR experiment at RHIC. The liquid is continuously cleaned and distributed to a quartz containment vessel within the detector by a closed recirculation system. A VUV spectrometer is connected to the system which monitors the optical transparency of the liquid. This measurement provides one of the pieces of information necessary to model the number of Cherenkov photons which reach the pad plane. A description of the liquid recirculation system and the cleaning procedure for the liquid as well as the spectrometer is presented along with results of their performance.

Andres, Y.; Braem, A.; Cozza, D.; Davenport, M.; De Cataldo, G.; Dell Olio, L.; DiBari, D.; DiMauro, A.; Dunlop, J. C.; Finch, E.; Fraissard, D.; Franco, A.; Gans, J.; Ghidini, B.; Harris, J. W.; Horsley, M.; Kunde, G. J.; Lasiuk, B.; Lesenechal, Y.; Majka, R. D.; Martinengo, P.; Morsch, A.; Nappi, E.; Paic, G.; Piuz, F.; Posa, F.; Raynaud, J.; Salur, S.; Sandweiss, J.; Santiard, J. C.; Satinover, J.; Schyns, E.; Smirnov, N.; Van Beelen, J.; Williams, T. D.; Xu, Z.; STAR-RICH Collaboration

307

Performance of the prototype gas recirculation system with built-in RGA for INO RPC system  

NASA Astrophysics Data System (ADS)

An open loop gas recovery and recirculation system has been developed for the INO RPC system. The gas mixture coming from RPC exhaust is first desiccated by passing through molecular sieve (3 Å+4 Å). Subsequent scrubbing over basic active alumina removes toxic and acidic contaminants. The Isobutane and Freon are then separated by diffusion and liquefied by fractional condensation by cooling up to -26C. A Residual Gas Analyser (RGA) is being used in the loop to study the performance of the recirculation system. The results of the RGA analysis will be discussed.

Bhuyan, M.; Datar, V. M.; Joshi, A.; Kalmani, S. D.; Mondal, N. K.; Rahman, M. A.; Satyanarayana, B.; Verma, P.

2012-01-01

308

Water recirculation and good management: potential methods to avoid disease outbreaks with Flavobacterium psychrophilum.  

PubMed

Flavobacterium psychrophilum infections cause high mortality among rainbow trout, Oncorhynchus mykiss, fry in Danish fish farms and hatcheries. Hatcheries based entirely on bore-hole water recirculation systems have been suggested as a possibility for eliminating F. psychrophilum or at least keeping the amount of this bacterium low. The occurrence of the bacterium in a bore-hole water recirculation system was compared with a combined bore-hole water and stream water flow-through system in a hatchery where outbreaks of rainbow trout fry syndrome caused by F. psychrophilum often occurred. Broodfish, unfertilized and fertilized eggs, eyed eggs and fry, as well as water samples from the tanks/troughs with broodfish/fry, were examined. Suspect yellow bacterial colonies were either confirmed or rejected as F. psychrophilum by growth characteristics and by PCR. As both virulent and less virulent F. psychrophilum isolates are known, isolates were characterized. The isolates were ribotyped and grouped according to ribotyping patterns. Representatives of the groups were serotyped. Fry isolates were very homogeneous whereas isolates from broodfish were heterogeneous, whether the isolates originated from external surfaces of the fish (mucus from skin and gills, haemorrhages and ulcers) or internal organs. Flavobacterium psychrophilum was isolated from broodfish in both water systems; 56% of investigated broodfish from the borehole/flowthrough system and 36% from the recirculation facility harboured the bacterium. In the recirculation system, the bacterium was isolated from fish (ulcers, milt, liver, abdominal cavity) kept in the system for 11 months. Flavobacterium psychrophilum was found in milt and ovarian fluid as well as on the surface of fertilized eggs, but not inside the eggs. Fry also harboured F. psychrophilum, but in the water recirculation system the bacterium was first isolated from the fry after they had been graded. Flavobacterium psychrophilum was found regularly in other parts of the hatchery (outside the recirculation facility), including at the time of grading, suggesting that the occurrence of F. psychrophilum in the fry recirculation facility was due to contamination from the borehole/flow-through hatchery. It is suggested that the combination of bore-hole water recirculation systems and good management procedures (including egg disinfection) is a possible method for hatcheries to avoid disease outbreaks due to F. psychrophilum. PMID:19238756

Madsen, L; Dalsgaard, I

2008-11-01

309

Design and simulation of a recirculating bed reactor for coal hydrogasification. Final report, Part I. Recirculating bed hydrogasifier conceptual design and simulation results  

Microsoft Academic Search

Part I of this report presents a conceptual design of a recirculating bed hydrogasifier. The reactor is designed to operate at 1800°F and 44 atm on hydrogen, and it would convert 63% of coal carbon. A mechanical design is presented which utilizes U-bend crossovers, a unique mechanism for controlling loop pressure balance and a dense-phase coal injector for direct addition

T. W. Bierl; L. J. Bajdos; A. E. McIver

1980-01-01

310

Four-Nozzle Benchmark Wind Tunnel Model USA Code Solutions for Simulation of Multiple Rocket Base Flow Recirculation at 145,000 Feet Altitude  

NASA Technical Reports Server (NTRS)

Multiple rocket exhaust plume interactions at high altitudes can produce base flow recirculation with attendant alteration of the base pressure coefficient and increased base heating. A search for a good wind tunnel benchmark problem to check grid clustering technique and turbulence modeling turned up the experiment done at AEDC in 1961 by Goethert and Matz on a 4.25-in. diameter domed missile base model with four rocket nozzles. This wind tunnel model with varied external bleed air flow for the base flow wake produced measured p/p(sub ref) at the center of the base as high as 3.3 due to plume flow recirculation back onto the base. At that time in 1961, relatively inexpensive experimentation with air at gamma = 1.4 and nozzle A(sub e)/A of 10.6 and theta(sub n) = 7.55 deg with P(sub c) = 155 psia simulated a LO2/LH2 rocket exhaust plume with gamma = 1.20, A(sub e)/A of 78 and P(sub c) about 1,000 psia. An array of base pressure taps on the aft dome gave a clear measurement of the plume recirculation effects at p(infinity) = 4.76 psfa corresponding to 145,000 ft altitude. Our CFD computations of the flow field with direct comparison of computed-versus-measured base pressure distribution (across the dome) provide detailed information on velocities and particle traces as well eddy viscosity in the base and nozzle region. The solution was obtained using a six-zone mesh with 284,000 grid points for one quadrant taking advantage of symmetry. Results are compared using a zero-equation algebraic and a one-equation pointwise R(sub t) turbulence model (work in progress). Good agreement with the experimental pressure data was obtained with both; and this benchmark showed the importance of: (1) proper grid clustering and (2) proper choice of turbulence modeling for rocket plume problems/recirculation at high altitude.

Dougherty, N. S.; Johnson, S. L.

1993-01-01

311

High rate algal pond treatment for water reuse in a marine fish recirculation system: Water purification and fish health  

Microsoft Academic Search

Regardless of the degree of closure of a recirculation system, effluents are produced and replacement water is needed, which limits the possibility of locating a seawater production system away from the shoreline. At the Palavas Ifremer station, in the south of France, a High Rate Algal Pond (HRAP) was operated during several years to treat the effluent from a recirculating

E. Metaxa; G. Deviller; P. Pagand; C. Alliaume; C. Casellas; J. P. Blancheton

2006-01-01

312

Development and design of a fluidized bed/upflow sand filter configuration for use in recirculating aquaculture systems  

SciTech Connect

A fluidized bed/upflow sand filter configuration, was developed and designed for utilization in recirculating aquaculture system, specifically the soft-shell crab and soft-shell crawfish industries. These filters were selected and designed because of their ability to withstand clogging and still maintain high levels of water quality for aquaculture production. The effectiveness of sand grain size was used to evaluate fluidized bed filter performance with filter loadings ranging from 16 to 1285 pounds of crawfish per cubic foot of filter sand. A coarse sand grain size was recommended as a filter media because of it's ability to shear excessive biofilm growth from the and, thus prohibiting clogging from occurring within the filter bed. The fluidized bed/upflow sand filter combination was evaluated in terms of nitrification and oxygen consumption when used with a recirculating crab shedding system. The filter combination's carrying capacity (700 crabs per cubic foot of sand media) exceeded that observed with the submerged rock filter by more than 20 times and was largely explained by the filter's solids removal ability which significantly reduced the filter's oxygen loading rate (OLR). Nitrification rates with the filter combination were extremely high as total ammonia and nitrite levels remained below 1.0 mg-N/l. Verification of a volumetric loading criteria (150 pounds per cubic foot) for this filter combination was further established with performance data obtained from a commercial soft-shell crawfish facility. Water quality monitoring results indicated that the filters maintained total ammonia and nitrite levels below 1.0 mg-N/l under typical operating conditions. Shock loading, pH control, and over-feeding, rather than filter capacity, dominated water quality fluctuations, thereby indicating that the loading criteria was sufficient for commercial operation.

Burden, D.G.

1988-01-01

313

SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES  

SciTech Connect

The research program conducted at the West Virginia University Engine and Emissions Research Laboratory (EERL) is working towards the verification and optimization of an approach to remove nitric oxides from the exhaust gas of lean burn natural gas engines. This project was sponsored by the US Department of Energy, National Energy Technology Laboratory (NETL) under contract number: DE-FC26-02NT41608. Selective NOx Recirculation (SNR) involves three main steps. First, NOx is adsorbed from the exhaust stream, followed by periodic desorption from the aftertreatment medium. Finally the desorbed NOx is passed back into the intake air stream and fed into the engine, where a percentage of the NOx is decomposed. This reporting period focuses on the NOx decomposition capability in the combustion process. Although researchers have demonstrated NOx reduction with SNR in other contexts, the proposed program is needed to further understand the process as it applies to lean burn natural gas engines. SNR is in support of the Department of Energy goal of enabling future use of environmentally acceptable reciprocating natural gas engines through NOx reduction under 0.1 g/bhp-hr. The study of decomposition of oxides of nitrogen (NOx) during combustion in the cylinder was conducted on a 1993 Cummins L10G 240 hp lean burn natural gas engine. The engine was operated at different air/fuel ratios, and at a speed of 800 rpm to mimic a larger bore engine. A full scale dilution tunnel and analyzers capable of measuring NOx, CO{sub 2}, CO, HC concentrations were used to characterize the exhaust gas. Commercially available nitric oxide (NO) was used to mimic the NOx stream from the desorption process through a mass flow controller and an injection nozzle. The same quantity of NOx was injected into the intake and exhaust line of the engine for 20 seconds at various steady state engine operating points. NOx decomposition rates were obtained by averaging the peak values at each set point minus the baseline and finding the ratio between the injected NO amounts. It was observed that the air/fuel ratio, injected NO quantity and engine operating points affected the NOx decomposition rates of the natural gas engine. A highest NOx decomposition rate of 27% was measured from this engine. A separate exploratory tests conducted with a gasoline engine with a low air/fuel ratio yielded results that suggested, that high NOx decomposition rates may be possible if a normally lean burn engine were operated at conditions closer to stoichiometric, with high exhaust gas recirculation (EGR) for a brief period of time during the NOx decomposition phase and with a wider range of air/fuel ratios. Chemical kinetic model predictions using CHEMKIN were performed to relate the experimental data with the established rate and equilibrium models. NOx decomposition rates from 35% to 42% were estimated using the CHEMKIN software. This provided insight on how to maximize NOx decomposition rates for a large bore engine. In the future, the modeling will be used to examine the effect of higher NO{sub 2}/NO ratios that are associated with lower speed and larger bore lean burn operation.

Nigel Clark; Gregory Thompson; Richard Atkinson; Chamila Tissera; Matt Swartz; Emre Tatli; Ramprabhu Vellaisamy

2005-01-01

314

Nutrient removal from aquaculture wastewater by vegetable production in aquaponics recirculation system  

Microsoft Academic Search

Nutrient removal is essential for aquaculture wastewater treatment to protect receiving water from eutrophication and for potential reuse of the treated water. The integration of aquaculture with agriculture appears to be an excellent way of saving water, disposing aquaculture wastewater and providing fertilizer to the agricultural crop. The study was conducted to evaluate aquaponics recirculation system (ARS) performance in removing

A. Enduta; A. Jusoh; N. Ali; W. B. Wan Nik

2011-01-01

315

A study on the optimal hydraulic loading rate and plant ratios in recirculation aquaponic system  

Microsoft Academic Search

The growths of the African catfish (Clarias gariepinus) and water spinach (Ipomoea aquatica) were evaluated in recirculation aquaponic system (RAS). Fish production performance, plant growth and nutrient removal were measured and their dependence on hydraulic loading rate (HLR) was assessed. Fish production did not differ significantly between hydraulic loading rates. In contrast to the fish production, the water spinach yield

Azizah Endut; A. Jusoh; N. Ali; W. B. Wan Nik; A. Hassan

2010-01-01

316

Integration of direct contact membrane distillation and recirculating cooling water system for pure water production  

Microsoft Academic Search

A novel cleaner production technology (CPT) using waste heat for pure water production was established by integration of direct contact membrane distillation (DCMD) and traditional recirculating cooling water (RCW) process. The effect of temperature difference and flow rate of fluid between the hot and cold sides in a membrane module on the membrane flux was investigated. The results of the

Jun Wang; Bin Fan; Zhaokun Luan; Dan Qu; Xianjia Peng; Deyin Hou

2008-01-01

317

Culture of Six Species of Bivalves in a Recirculating Seawater System.  

National Technical Information Service (NTIS)

The report presents the results of four experiments conducted in which six species of bivalve molluscs were reared for periods ranging from ten weeks to over two years in a recirculating seawater system. Shellfish were fed defined algal diets and had no a...

C. E. Epifanio C. M. Logan C. Turk

1975-01-01

318

Design and Evaluation of Recirculating Water Systems for Maintenance and Propagation of Freshwater Mussels  

Microsoft Academic Search

A complete system for culturing, rearing, and holding juvenile and adult freshwater mussels (Unionidae) was designed and evaluated for use at hatcheries and research facilities. The system includes air delivery, water conditioning and delivery, algal culturing and automated algal feed delivery, and air-driven water-recirculating units. These systems are appropriate for holding and conditioning adult mussels for spawning, as well as

William F. Henley; Lora L. Zimmerman; Richard J. Neves; Mark R. Kidd

2001-01-01

319

Experimental and numerical visualization of the recirculation flow inside a gas flow-focused liquid meniscus  

Microsoft Academic Search

The liquid cone-jet mode, which can be produced upon stimulation by gas flow-focusing among other procedures, is explored by both numerical simulation and experimental visualization. The results for low viscosity liquids show that, like in previous computational simulations, a recirculation cell inside the meniscus appears when the injected liquid flow rate is reduced below a certain limit. The size of

M. Torregrosa; C. Ferrera; A. Ganan-Calvo; M. A. Herrada; M. Marchand

2010-01-01

320

Albumin dialysis and Molecular Adsorbents Recirculating System (MARS) for acute Wilson's disease  

Microsoft Academic Search

Wilson's disease presenting as acute liver failure (ALF) is potentially fatal, and liver transplantation (LTx) is the only option. We report two patients with Wilson's disease and ALF treated with the Molecular Adsorbents Recirculating System (MARS). Both patients fulfilled criteria for poor prognosis. Because LTx was not available immediately in either case, MARS was used as a bridge to LTx.

Sambit Sen; Marie Felldin; Christian Steiner; Bo Larsson; Godfrey T. Gillett; Michael Olausson; Roger Williams; Rajiv Jalan

2002-01-01

321

Microbial corrosion of galvanized steel in a simulated recirculating cooling tower system  

Microsoft Academic Search

In this study, mixed species biofilm formation including sulphate reducing bacteria (SRB) on the galvanized steel surfaces and also microbiologically influenced corrosion (MIC) of galvanized steel were observed in a model recirculating cooling water system during 10months. A biofilm which had a heterogeneous structure formed on galvanized steel coupons. The results suggested that galvanized steel was corroded by microorganisms as

Esra Ilhan-Sungur; Ay??n Çotuk

2010-01-01

322

Physiologically-based pharmacokinetic model for trichloroethylene considering enterohepatic recirculation of major metabolites  

SciTech Connect

Trichloroacetic acid (TCA) is a major metabolite of trichloroethylene (TRI) thought to contribute to its hepatocarcinogenic effects in mice. Recent studies have shown that peak blood concentrations of TCA in rats do not occur until approximately 12 hours following an oral dose of TRI. However, blood concentrations of TRI reach a maximum within an hour and are nondetectable after 2 hours. The results of a study which examined the enterohepatic recirculation (EHC) of the principle TRI metabolites was used to develop a physiologically-based pharmacokinetic model for TRI, which includes enterohepatic recirculation of its metabolites. The model quantitatively predicts the uptake, distribution and elimination of TRI, trichloroethanol, trichloroethanol-glucuronide, and TCA and includes production of metabolites through the enterohepatic recirculation pathway. Physiologic parameters used in the model were obtained from the literature. Parameters for TRI metabolism were taken from Fisher et al. Other kinetic parameters were found in the literature or estimated from experimental data. The model was calibrated to data from experiments of an earlier study where TRI was orally administered. Verification of the model was conducted using data on the enterohepatic recirculation of TCEOH and TCA, choral hydrate data (infusion doses) from Merdink, and TRI data from Templin and Larson and Bull.

Stenner, R.D.; Bull, R.J. [Pacific Northwest National Lab., Richland, WA (United States)

1998-06-01

323

Concept for powering the dipole magnet in a recirculating induction accelerator for heavy ion fusion  

Microsoft Academic Search

In a Recirculating Heavy Ion Fusion Induction Accelerator the largest energy consumption occurs in the bending magnetic fields. Because these fields are pulsed, they cannot be generated by superconducting magnets. The bending magnets will consist of iron core dipoles with multiturn copper conductors. The energy stored in the magnetic field is many tens of megajoules and over 90% of this

L. Reginato; M. Newton; S. Yu

1990-01-01

324

A nucleonic oil debris monitor for detecting metal in recirculating lubricating systems  

Microsoft Academic Search

Metallic debris sensors have been developed for recirculating oil lubrication systems. The in-line monitors apply the principle of X-ray fluorescence. The nucleonic oil debris monitors (ODM's) have been designed and fabricated for use with test cell operations involving aircraft transmissions and gear boxes. ODM's were tested to evaluate their sensitivity, accuracy, and response to lubricant temperature over the range of

R. W. Harman

1974-01-01

325

Leachate recirculation: moisture content assessment by means of a geophysical technique  

Microsoft Academic Search

Bioreactor technology is a waste treatment concept consisting in speeding up the biodegradation of landfilled waste by optimizing its moisture content through leachate recirculation. The measurement of variations in waste moisture content is critical in the design and control of bioreactors. Conventional methods such as direct physical sampling of waste reach their limits due to the interference with the waste

Roger Guérin; Marie Laure Munoz; Christophe Aran; Claire Laperrelle; Mustapha Hidra; Eric Drouart; Solenne Grellier

2004-01-01

326

Continuous fermentation of undetoxified dilute acid lignocellulose hydrolysate by Saccharomyces cerevisiae ATCC 96581 using cell recirculation.  

PubMed

Saccharomyces cerevisiae ATCC 96581 was cultivated in a chemostat reactor with undetoxified dilute acid softwood hydrolysate as the only carbon and energy source. The effects of nutrient addition, dilution rate, cell recirculation, and microaerobicity were investigated. Fermentation of unsupplemented dilute acid lignocellulose hydrolysate at D = 0.10 h(-1) in an anaerobic continuous reactor led to washout. Addition of ammonium sulfate or yeast extract was insufficient for obtaining steady state. In contrast, dilute acid lignocellulose hydrolysate supplemented with complete mineral medium, except for the carbon and energy source, was fermentable under anaerobic steady-state conditions at dilution rates up to 0.14 h(-1). Under these conditions, washout occurred at D = 0.15 h(-1). This was preceded by a drop in fermentative capacity and a very high specific ethanol production rate. Growth at all different dilution rates tested resulted in residual sugar in the chemostat. Cell recirculation (90%), achieved by cross-flow filtration, increased the sugar conversion rate from 92% to 99% at D = 0.10 h(-1). Nutrient addition clearly improved the long-term ethanol productivity in the recirculation cultures. Application of microaerobic conditions on the nutrient-supplemented recirculation cultures resulted in a higher production of biomass, a higher cellular protein content, and improved fermentative capacity, which further improves the robustness of fermentation of undetoxified lignocellulose hydrolysate. PMID:16080688

Brandberg, Tomas; Sanandaji, Nima; Gustafsson, Lena; Franzén, Carl Johan

2005-01-01

327

Experimental Bleaching of a Reef-Building Coral Using a Simplified Recirculating Laboratory Exposure System  

EPA Science Inventory

Determining stressor-response relationships in reef building corals is a critical need for researchers because of global declines in coral reef ecosystems. A simplified recirculating coral exposure system for laboratory testing of a diversity of species and morphologies of reef b...

328

Farming the Artificial Sea: Growth of Clams in a Recirculating Seawater System.  

National Technical Information Service (NTIS)

Eight groups of hatchery-reared clams were cultured for 22 weeks from setting in a recirculating seawater system. Each of the eight groups was fed a different diet. An extrapolated growth rate for the fastest growing group would yield animals with a shell...

M. Hartman C. E. Epifanio G. Pruder R. na

1975-01-01

329

Comparison of theory and experiment for dispersion-managed solitons in a recirculating fiber loop  

Microsoft Academic Search

We have developed a model that accurately predicts the dynamics of the signal pulses and the growth of amplified spontaneous emission noise in a dispersion-managed soliton pulse train propagating in a recirculating fiber-loop experiment. Theoretically predicted dependencies of the amplitude and phase margins for the marks and the amplitude margin for the spaces as a function of distance are in

R.-M. Mu; V. S. Grigoryan; Curtis R. Menyuk; G. M. Carter; J. M. Jacob

2000-01-01

330

Numerical Recirculating Flow Calculation Using a Body-Fitted Coordinate System  

Microsoft Academic Search

A finite-difference algorithm for recirculating flow problem! in a body-fitted coordinate system is presented. A fully staggered grid system is adopted for the velocity components and the scalar variables. The strong conservation law form of the governing equations is written in the general curvilinear coordinates. The SIMPLE calculation procedure originally developed in Cartesian coordinates is extended to the present curvilinear

W. Shyy; S. S. Tong; S. M. Correa

1985-01-01

331

Dynamic Instabilities in Spark-Ignited Combustion Engines with High Exhaust Gas Recirculation.  

National Technical Information Service (NTIS)

We propose a cycle-resolved dynamic model for combustion instabilities in spark-ignition engines operating with high levels of exhaust gas recirculation (EGR). We account for the complex combustion response to cycle-to-cycle feedback by utilizing a global...

C. E. A. Finney C. S. Dawov

2013-01-01

332

The effects of exhaust gas recirculation on diesel combustion and emissions  

Microsoft Academic Search

An investigation was conducted with the aim of identifying and quantifying the effects of exhaust gas recirculation (EGR) on diesel engine combustion and exhaust emissions. Five effects of EGR were identified and investigated experimentally: the reduction in oxygen supply to the engine, participation in the combustion process of carbon dioxide and water vapour present in the EGR, increase in the

N Ladommatos; S Abdelhalim; H Zhao

2000-01-01

333

Reduction of Beam Breakup Growth by Cavity Cross-Couplings in Recirculating Accelerators.  

National Technical Information Service (NTIS)

It is shown that cross-coupling among cavities may reduce beam breakup (BBU) growth in a recirculating accelerator. The main reason for this growth reduction appears to be the sharing of the deflecting mode energy among coupled cavities. The result is bas...

D. Chernin D. Colombant Y. Y. Lau

1990-01-01

334

Fulminant hepatic failure following marijuana drug abuse: Molecular adsorbent recirculation system therapy  

PubMed Central

Marijuana is used for psychoactive and recreational purpose. We report a case of fulminant hepatic failure following marijuana drug abuse who recovered following artificial support systems for acute liver failure. There is no published literature of management of marijuana intoxication with molecular adsorbent recirculation system (MARS). MARS is effective and safe in patients with fulminant hepatic failure following marijuana intoxication.

Swarnalatha, G.; Pai, S.; Ram, R.; Dakshinamurty, K. V.

2013-01-01

335

A Tracer Method for Evaluating Recirculation of Pollutant Releases in Buildings  

Microsoft Academic Search

A method is introduced for evaluating recirculation in a building ventilation system from pollutant emissions in or near the building. Tracer was released at a known rate at the point of pollutant emission. Using measured tracer concentrations, the tracer release rate, and an estimate of the pollutant release rate, pollutant concentrations were estimated at the locations in the building where

James P. Rydock; Ove Hermansen

2002-01-01

336

Monte Carlo simulation of energization of Jovian trapped electrons by recirculation  

SciTech Connect

The recirculation model for particle acceleration in the Jovian magnetosphere is studied by means of Monte Carlo simulation. The recirculation model combines the conventional radial and pitch angle diffusion processes with the essentially energy-conserving latitudinal diffusion in low altitudes and the pitch angle scattering in the plasma disc. This process has been proposed to explain the pitch angle and spectral characteristics of MeV electrons observed by Pioneer spacecraft in the Jovian magnetosphere. The simulation confirms that the dumbbell type anisotropy and the high-energy tail of the energy spectrum can be produced from the recirculation process if the rate of the low-altitude cross-L diffusion is comparable to that of the conventional radial diffusion. The required low-altitude diffusion rate corresponds to roughly 10{sup {minus}2} times the Bohm diffusion rate for 1-MeV electrons, and altitudes is responsible for this high diffusion rate. The dumbbell type anisotropy observed also for MeV range electrons in the Earth's and Saturnian magnetospheres could also be the consequence of the recirculation process.

Fujimoto, M.; Nishida, A. (Inst. of Space and Astronautical Science, Sagamihara (Japan))

1990-04-01

337

Suction-recirculation device for stabilizing particle flows within a solar powered solid particle receiver  

DOEpatents

A suction-recirculation device for stabilizing the flow of a curtain of blackened heat absorption particles falling inside of a solar receiver with an open aperture. The curtain of particles absorbs the concentrated heat from a solar mirror array reflected up to the receiver on a solar power tower. External winds entering the receiver at an oblique angle can destabilize the particle curtain and eject particles. A fan and ductwork is located behind the back wall of the receiver and sucks air out through an array of small holes in the back wall. Any entrained particles are separated out by a conventional cyclone device. Then, the air is recirculated back to the top of the receiver by injecting the recycled air through an array of small holes in the receiver's ceiling and upper aperture front wall. Since internal air is recirculated, heat losses are minimized and high receiver efficiency is maintained. Suction-recirculation velocities in the range of 1-5 m/s are sufficient to stabilize the particle curtain against external wind speeds in excess of 10 m/s.

Kolb, Gregory J. (Albuquerque, NM)

2012-02-07

338

Effect of coagulation pretreatment on membrane distillation process for desalination of recirculating cooling water  

Microsoft Academic Search

The objective of this work was to study the performance of coagulation pretreatment and the effect of coagulation pretreatment on membrane distillation (MD) process for desalination of recirculating cooling water (RCW). In this study, RCW was desalinated by MD process after pretreated by coagulation, precision filtration, acidification and degassing. Pre-coagulation of RCW with poly-aluminum chloride (PACl) coagulant improves the elimination

Jun Wang; Dan Qu; Muer Tie; Haijing Ren; Xianjia Peng; Zhaokun Luan

2008-01-01

339

Growth and survival of juvenile cobia, Rachycentron canadum, at different salinities in a recirculating aquaculture system  

Microsoft Academic Search

Cobia (Rachycentron canadum) is an emerging aquaculture candidate for both offshore cage culture and land-based systems such as recirculating aquaculture systems. The ability to grow cobia at salinities other than oceanic (?34 ppt) could present culturists with additional production opportunities with this species. Culture at low salinities could also reduce the incidence of disease and simplify water management. In two

Matthew J. Resley; Kenneth A. Webb; G. Joan Holt

2006-01-01

340

Growth and survival of larval and juvenile cobia Rachycentron canadum in a recirculating raceway system  

Microsoft Academic Search

Cobia Rachycentron canadum is a fast-growing, pelagic marine species that has recently attracted aquaculturists in both the research and commercial sectors. The typical method of grow-out for this species is in outdoor systems where production is limited to locations and seasons conducive for adequate growth and survival. Expanding the culture of cobia to indoor recirculating aquaculture systems (RAS) would allow

Cynthia K. Faulk; Jeffrey B. Kaiser; G. Joan Holt

2007-01-01

341

Growth of juvenile cobia, Rachycentron canadum, at three different densities in a recirculating aquaculture system  

Microsoft Academic Search

Cobia (Rachycentron canadum) is an excellent aquaculture candidate and culture of this species continues to develop worldwide. Current culture practices generally include larviculture and production of early juveniles on land with final growout occurring in ocean cages. Data indicate that production and\\/or growout of juveniles in land based recirculating systems may be hampered by growth depression in fish held at

Kenneth A. Webb; Glenn M. Hitzfelder; Cynthia K. Faulk; G. Joan Holt

2007-01-01

342

The use of ozone in a high density recirculation system for rotifers  

Microsoft Academic Search

The use of ozone in the effluent treatment of a closed recirculation system for rotifers resulted in a significant improvement of rotifer production and water quality. Compared to a control treatment, the rotifer culture exposed to ozone did not only support a higher rotifer biomass (16000 vs. 8000 rotifers ml?1), it also allowed a prolongation of the culture period for

G Suantika; P Dhert; G Rombaut; J Vandenberghe; T De Wolf; P Sorgeloos

2001-01-01

343

Development concepts of primary coolant recirculating pumps for nuclear power plants  

Microsoft Academic Search

From pump conference; Karlsruhe, Germany (2 Oct 1973). The layout and ; design of primary coolant recirculating pumps is closely connected with the ; development of the various types of reactors. Reactor safety aspects have an ; influence on the design of reactors as well as on the design features of pressure ; retaining pump components. The rapid increase in

Gaffal

1973-01-01

344

Development concepts of primary coolant recirculating pumps for nuclear power plants  

Microsoft Academic Search

From pump conference; Karlsruhe, Germany (2 Oct 1973). The layout and ; design of primary coolant recirculating pumps is closely connected with the ; development of the various types of reactors. Reactor safety aspects have an ; influence on the conception of reactors as well as on the design features of ; pressure retaining pump components. The rapid increase in

Gaffal

1973-01-01

345

Performance of two-stage vegetable waste anaerobic digestion depending on varying recirculation rates.  

PubMed

Vegetable waste, which characterized by high moisture content, was evaluated as a substrate for biogas production. The effects of recirculation rate (RR) on the performance of two-stage anaerobic digestion were investigated. The system was operated at an organic loading rate of 1.7 g VS/L/d with varying RRs (0, 0.6, 1, and 1.4). Results demonstrated that volumetric biogas production rates in acidogenic reactor increased from approximately 0.2 7 L/L/d to 0.97 L/L/d, when pH is increased from approximately 5.1 to 6.7. These indicate that recirculation of alkaline effluent from the methanogenic reactor helps create a favorable condition for biogas production in the acidogenic reactor. The decrease in chemical oxygen demand (COD) concentrations from approximately 21,000 mg/L to 6800 mg/L was also observed in the acidogenic reactor. This condition may be attributed to dilution under recirculation. The dynamics between hydrolysis and methanogenesis under recirculation indicated that mass transfer capacity between two-stage reactors improved. PMID:24759642

Zuo, Zhuang; Wu, Shubiao; Zhang, Wanqin; Dong, Renjie

2014-06-01

346

Temperate Oceans : Light Zones  

NSDL National Science Digital Library

This reference provides an overview of the three zones into which the ocean can be divided based on the amount of light recieved: the sunlit (or euphotic) zone, the twilight (or disphotic) zone, and the midnight (or aphotic) zone. The descriptions are accompanied by diagrams and a brief listing of the organisms that live in each zone.

2007-12-12

347

Twin Convergence Zones  

NASA Technical Reports Server (NTRS)

NASA's QuikSCAT satellite has confirmed a 30-year old largely unproven theory that there are two areas near the equator where the winds converge year after year and drive ocean circulation south of the equator. By analyzing winds, QuikSCAT has found a year-round southern and northern Intertropical Convergence Zone. This find is important to climate modelers and weather forecasters because it provides more detail on how the oceans and atmosphere interact near the equator. The Intertropical Convergence Zone (ITCZ) is the region that circles the Earth near the equator, where the trade winds of both the Northern and Southern Hemispheres come together. North of the equator, strong sun and warm water of the equator heats the air in the ITCZ, drawing air in from north and south and causing the air to rise. As the air rises it cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms. Satellite data, however, has confirmed that there is an ITCZ north of the equator and a parallel ITCZ south of the equator. Variation in the location of the ITCZ is important to people around the world because it affects the north-south atmospheric circulation, which redistributes energy. It drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes. Longer term changes in the ITCZ can result in severe droughts or flooding in nearby areas. 'The double ITCZ is usually only identified in the Pacific and Atlantic Oceans on a limited and seasonal basis,' said Timothy Liu, of NASA's Jet Propulsion Laboratory and California Institute of Technology, Pasadena, Calif., and lead researcher on the project. In the eastern Pacific Ocean, the southern ITCZ is usually seen springtime. In the western Atlantic Ocean, the southern ITCZ was recently clearly identified only in the summertime. However, QuikSCAT's wind data has seen the southern ITCZ in all seasons across the entire Atlantic Ocean and the eastern Pacific. 'QuikSCAT's wind data confirms there is a double ITCZ, and that they exist all year long,' Liu said. This is a major find for the science community, as the existence, location, and seasonality of the double ITCZ had remained controversial since 1969. full text: Satellite Sees Double Zones of Converging Tropical Winds around The World For more about convergence zones, read: The Intertropical Convergence Zone and Convergence Zones: Where the Action Is Image courtesy Liu and Xie, NASA JPL

2002-01-01

348

Simultaneous water desalination and electricity generation in a microbial desalination cell with electrolyte recirculation for pH control.  

PubMed

A recirculation microbial desalination cell (rMDC) was designed and operated to allow recirculation of solutions between the anode and cathode chambers. This recirculation avoided pH imbalances that could inhibit bacterial metabolism. The maximum power density was 931±29mW/m(2) with a 50mM phosphate buffer solution (PBS) and 776±30mW/m(2) with 25mM PBS. These power densities were higher than those obtained without recirculation of 698±10mW/m(2) (50mM PBS) and 508±11mW/m(2) (25mM PBS). The salt solution (20g/L NaCl) was reduced in salinity by 34±1% (50mM) and 37±2% (25mM) with recirculation (rMDC), and by 39±1% (50mM) and 25±3% (25mM) without recirculation (MDC). These results show that electrolyte recirculation using an rMDC is an effective method to increase power and achieve efficient desalination by eliminating pH imbalances. PMID:22200556

Qu, Youpeng; Feng, Yujie; Wang, Xin; Liu, Jia; Lv, Jiangwei; He, Weihua; Logan, Bruce E

2012-02-01

349

Spontaneous interannual to decadal scale variations in the Kuroshio and its recirculation in a high-resolution North Pacific Model  

NASA Astrophysics Data System (ADS)

Interannual to decadal scale variations of the Kuroshio and its recirculation are investigated using an eddy-permitting North Pacific numerical model. The model is a z-coordinate free-surface OGCM (one version of MRI.COM; MRI Community Ocean Model). Horizontal resolution is 1/6o in the latitudinal and 1/4o in the longitudinal direction, with 44 vertical levels. The model domain is the Pacific north of 15oS. Integration is carried out for 150 years, including the initial restoring body forcing of temperature and salinity to the observed state for the first six years. Data from the last 50 years of integration are used for analysis. The model is forced by climatological wind stresses, and the temperature and salinity are restored to climatology at the surface, at the southern boundary, and in the Okhotsk and Bering Seas. Without interannual change in the forcing, it is found that there are variations of about three-year period in mass transports of the Kuroshio through the Tokara Strait and the Ryukyu Current, flowing northeastward east of the Ryukyu Islands. The Tokara transport lags that of the Ryukyu Current for about 9 months. The Tokara transport is also found to be in opposite phase with the extent of the recirculation gyre, which is defined here as an area encircled by some closed contour of the barotropic stream function. During the analysis period, the Kuroshio south of Japan takes the large meander path, the strait path, or unstable paths. The path variation is rather irregular in comparison with the mass transport described above. The stable large meander path that persists for longer than a couple of years appears four times within the fifty-year period. Thus, the periods between the transitions from the strait path ( or unstable paths ) to the large meander path are about twelve years on average, which is longer than the time scale of the mass transport variation, and the path variation looks uncorrelated to the mass transport.

Ishikawa, I.; Ishizaki, H.

2004-12-01

350

The middle intertidal zone  

NSDL National Science Digital Library

The middle intertidal zone is submerged during high tide and only exposed during low tides. This zone has the most moderate conditions of the zones and has many algae, sea anemones, mollusks, and crustaceans.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-04

351

The middle intertidal zone  

NSDL National Science Digital Library

The middle intertidal zone is submerged during high tide and only exposed during low tides. This zone has the most moderate conditions of the zones and has many algae, sea anemones, mollusks, and crustaceans.

Katie Hale (CSUF;Biological Sciences)

2007-06-08

352

The upper intertidal zone  

NSDL National Science Digital Library

The upper intertidal zone is exposed most of the time and will become submerged only during high tide. This zone is least abundant of the intertidal zones but contains some mollusks, barnacles, and other animals adapted to avoid drying out.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-04

353

The upper intertidal zone  

NSDL National Science Digital Library

The upper intertidal zone is exposed most of the time and will become submerged only during high tide. This zone is least abundant of the intertidal zones but contains some mollusks, barnacles, and other animals adapted to avoid drying out.

Katie Hale (CSUF;Biological Sciences)

2007-06-08

354

Heat transport dynamics at a sandy intertidal zone  

NASA Astrophysics Data System (ADS)

Intertidal zones are spatially complex and temporally dynamic environments. Coastal groundwater discharge, including submarine groundwater discharge, may provide stabilizing conditions for intertidal zone permeable sediments. In this study, we integrated detailed time series temperature observations, porewater pressure measurements, and two-dimensional electrical resistivity tomography profiles to understand the coupled hydraulic-thermal regime of a tropical sandy intertidal zone in a fringing coral reef lagoon (Rarotonga, Cook Islands). We found three heating patterns across the 15 m study transect over tidal and diel periods: (1) a highly variable thermal regime dominated by swash infiltration and changes in saturation state in the upper foreshore with net heat import into the sediment, (2) a groundwater-supported underground stable, cool region just seaward of the intertidal slope break also importing heat into the subsurface, and (3) a zone of seawater recirculation that sustained consistently warm subsurface temperatures that exported heat across the sediment-water interface. Simple calculations suggested thermal conduction as the main heat transport mechanism for the shallow intertidal sediment, but deeper and/or multidimensional groundwater flow was required to explain temperature patterns beyond 20 cm depth. Temperature differences between the distinct hydrodynamic zones of the foreshore site resulted in significant thermal gradients that persisted beyond tidal and diel periods. The thermal buffering of intertidal zones by coastal groundwater systems, both at surface seeps and in the shallow subsurface, can be responsible for thermal refugia for some coastal organisms and hotspots for biogeochemical reactions.

Befus, Kevin M.; Cardenas, M. Bayani; Erler, Dirk V.; Santos, Isaac R.; Eyre, Bradley D.

2013-06-01

355

Root Apex Transition Zone As Oscillatory Zone  

PubMed Central

Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen, and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command center. In accordance with the early proposal of Charles and Francis Darwin, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone.

Baluska, Frantisek; Mancuso, Stefano

2013-01-01

356

Diffuse large B-cell lymphoma of the uterus suspected of having transformed from a marginal zone B-cell lymphoma harboring trisomy 18: a case report and review of the literature  

PubMed Central

The patient was a 72-year-old female with the chief complaint of abdominal fullness. A giant primary myoma of the uterine cervix was suspected, and total hysterectomy was performed. Based on a postoperative histopathological examination of the tumor a diagnosis of diffuse large B-cell lymphoma (DLBCL) was made in the uterus and a mass in the greater omentum was diagnosed as a marginal zone B-cell lymphoma (MZBCL). No flow-cytometry studies or chromosome or gene examinations were performed on a fresh specimen. The results of an examination of a paraffin block histopathology specimen by fluorescence in-situ hybridization (FISH) showed no mucosa associated lymphoid tissue lymphoma translocation gene 1 (MALT1) (18q21.1), B-cell lymphoma 2 (BCL2) (18q21.3), or BCL6 (3q27) split signals in either the uterus or the greater omentum, however, trisomy 18 was detected in approximately 50%-70% of the tumor cells in both the uterus and the greater omentum. Trisomy 18 was present in around 15-33% of the DLBCL cells and MZBCL cells. These findings suggested a strong possibility that the tumor cells in the uterus and greater omentum were the same clone and that transformation from MZBCL to DLBCL had occurred. Since DLBCLs that result from a transformation usually have a worse outcome than de novo DLBCLs, even when a DLBCL seems to have originated in the uterus the surrounding tissue should always be examined, and caution should be exercised in regard to transformation from a low-grade B-cell lymphoma to a DLBCL.

Sugimoto, Kei-Ji; Imai, Hidenori; Shimada, Asami; Wakabayashi, Mutsumi; Sekiguchi, Yasunobu; Nakamura, Noriko; Sawada, Tomohiro; Izumi, Hiroshi; Ota, Yasunori; Komatsu, Norio; Noguchi, Masaaki

2013-01-01

357

Design and simulation of a recirculating bed reactor for coal hydrogasification. Final report, Part I. Recirculating bed hydrogasifier conceptual design and simulation results  

SciTech Connect

Part I of this report presents a conceptual design of a recirculating bed hydrogasifier. The reactor is designed to operate at 1800/sup 0/F and 44 atm on hydrogen, and it would convert 63% of coal carbon. A mechanical design is presented which utilizes U-bend crossovers, a unique mechanism for controlling loop pressure balance and a dense-phase coal injector for direct addition of agglomerating coals. Part II documents the software developed to perform a non-linear simulation of a recirculating bed reactor for coal hydrogasification. The software takes the form of a flowsheet simulator of limited, yet general applicability. The information herein serves as both a user's manual and a programmer's reference manual. Included are descriptions of how to use the software, how it works, and source listings of the code developed in DECsystem-20 FORTRAN V. Documentation on the use of the simulator for its intended purpose is contained in Part I. Part III presents a linear programming analysis of hydrogasification strategies. It attempts to establish the operating conditions of the hydrogasifier by placing it in the context of the complete process. The most surprising result was that a processing strategy which was allowed to produce a char product was no more efficient a means of producing methane than was a process which converted all of the coal.

Bierl, T.W.; Bajdos, L.J.; McIver, A.E.

1980-03-01

358

Possible interactions between recirculated landfill leachate and the stabilized organic fraction of municipal solid waste.  

PubMed

The stabilized organic fraction of municipal solid waste (SOFMSW) is a product of the mechanical/biological treatment (MBT) of mixed municipal solid waste (MMSW). SOFMSW is considered a 'grey' compost and the presence of pollutants (particularly heavy metals) and residual glass and plastic normally prevents agricultural use, making landfills the typical final destination for SOFMSW. Recirculation of leachate in landfills can be a cost-effective management option, but the long-term sustainability of such a practice must be verified. Column tests were carried out to examine the effect of SOFMSW on leachate recirculation. The results indicate that organic matter may be biologically degraded and metals (copper and zinc) are effectively entrapped through a combination of physical (adsorption), biological (bacterial sulfate reduction), and chemical (precipitation of metal sulfides) processes, while other chemicals (i.e. ammonia nitrogen and chloride) are essentially unaffected by filtration through SOFMSW. PMID:22351654

Calabrò, Paolo S; Mancini, Giuseppe

2012-05-01

359

A tracer method for evaluating recirculation of pollutant releases in buildings.  

PubMed

A method is introduced for evaluating recirculation in a building ventilation system from pollutant emissions in or near the building. Tracer was released at a known rate at the point of pollutant emission. Using measured tracer concentrations, the tracer release rate, and an estimate of the pollutant release rate, pollutant concentrations were estimated at the locations in the building where the tracer was measured. The method can be used to test whether a ventilation system is adequate for maintaining an acceptable work environment before work with a hazardous substance begins. In a case study presented to illustrate the technique, initial attempts to correct a problem of recirculation of sulfuric acid from a fume hood in a chemistry laboratory were shown to be inadequate, prompting the ventilation contractor to make further repairs before work with sulfuric acid could be resumed. PMID:11975662

Rydock, James P; Hermansen, Ove

2002-01-01

360

Diagnosing system for an exhaust gas recirculation system of an automotive engine  

SciTech Connect

This patent describes a diagnosing system for an exhaust gas recirculation system having an EGR passage communicating an exhaust pipe of an engine with an intake passage of the engine, an EGR valve provided in the EGR passage, control means for opening the EGR valve in accordance with enigne operating conditions comprising: first means for detecting flow rate of recirculated gas in the EGR passage and for producing an actual EGR rate signal dependent on the flow rate; second means for producing a desired EGR rate signal including an allowable range in accordance with engine operating conditions; and third means responsive to the actual EGR rate signal and the desired EGR rate signal for producing a trouble signal as an alarm signal when the actual EGR rate signal is out of the allowable range.

Tamura, I.

1988-02-09

361

LUX - A recirculating linac-based ultrafast X-ray source  

SciTech Connect

We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV range, and is followed by four passes through a 700 MeV recirculating linac. Ultrafast hard x-ray pulses are obtained by a combination of electron bunch manipulation, transverse temporal correlation of the electrons, and x-ray pulse compression. EUV and soft x-ray pulses as short as 10 fs are generated in a harmonic-cascade free electron laser scheme.

Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.R.; Lidia, S.; Li, D.; Parmigiani, F.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Zholents, A.

2003-08-01

362

Thermal-hydraulic tests of a recirculation cooling installation for the Rostov nuclear power station  

NASA Astrophysics Data System (ADS)

Results obtained from thermal-hydraulic tests of the recirculation cooling installation used as part of the air cooling system under the containments of the Rostov nuclear power station Units 3 and 4 are presented. The operating modes of the installation during normal operation (air cooling on the surface of finned tubes), under the conditions of anticipated operational occurrences (air cooling and steam condensation from a steam-air mixture), and during an accident (condensation of pure steam) are considered. Agreement is obtained between the results of tests and calculations carried out according to the recommendations given in the relevant regulatory documents. A procedure of carrying out thermal calculation for the case of steam condensation from a steam-air mixture on the surface of fins is proposed. The possibility of efficient use of the recirculation cooling installation in the system for reducing emergency pressure under the containment of a nuclear power station is demonstrated.

Balunov, B. F.; Balashov, V. A.; Il'in, V. A.; Krayushnikov, V. V.; Lychakov, V. D.; Meshalkin, V. V.; Ustinov, A. N.; Shcheglov, A. A.

2013-09-01

363

Organic compounds in re-circulated leachates of aerobic biological treated municipal solid waste  

Microsoft Academic Search

Biodegradation of organic matter is required to reduce the potential of municipal solid waste for producing gaseous emissions and leaching contaminants. Therefore, we studied leachates of an aerobic-treated waste from municipal solids and a sewage sludge mixture that were re-circulated to decrease the concentration of biodegradable organic matter in laboratory-scale reactors. After 12 months, the total organic C and biological and

Matthias Franke; Gerald Jandl; Peter Leinweber

2006-01-01

364

Recirculating loop for experimental evaluation of EDFA saturated regime effects on optical communication systems  

Microsoft Academic Search

We demonstrate an optical-fiber recirculating loop for experimental simulation of long-haul optical communication systems using cascaded erbium-doped fiber amplifiers (EDFA's) operating in the gain saturation regime. The loop contains sections of dispersion shifted fibers (DSF's), standard fiber, and a set of in-line devices, such as tuning filters, optical amplifiers, polarization controllers, and a variable attenuator. The main results presented here

Claudio Mazzali; Hugo L. Fragnito

1998-01-01

365

RECIRCULATING - REDUCING AND ALKALINITY PRODUCING SYSTEM (RERAPS) FOR THE TREATMENT OF ACIDIC COAL PILE RUNOFF 1  

Microsoft Academic Search

The treatment of acidic coal pile runoff (CPR) using an alternative constructed wetland design was evaluated. This alternative design, which provided improved wetland performance, was based on the partial re-circulation of treated water into a detention basin located immediately upstream from a Reducing and Alkalinity Producing System (RAPS). This modification created a semi-passive RAPS-based system we refer to as a

William E. Garrett; Alfred A. Bartolucci; Robert R. Pitt; Michael E. Vermace

2002-01-01

366

Selective NOx Recirculation for Stationary Lean-Burn Natural Gas Engines  

Microsoft Academic Search

Nitric oxide (NO) and nitrogen dioxide (NO2) generated by internal combustion (IC) engines are implicated in adverse environmental and health effects. Even though lean-burn natural gas engines have traditionally emitted lower oxides of nitrogen (NOx) emissions compared to their diesel counterparts, natural gas engines are being further challenged to reduce NOx emissions to 0.1 g\\/bhp-hr. The Selective NOx Recirculation (SNR)

Nigel N. Clark

2006-01-01

367

Identification of channelling and recirculation parameters of agitated pulp stock chests  

Microsoft Academic Search

This paper describes a mechanism for identifying the dynamics of non-ideal mixing processes. The object is to study two of the non-ideal behaviours of agitated pulp stock chests: recirculation and channelling. An initial continuous-time model, which contains physically relevant parameters, is transformed into its discrete-time counterpart. This transformation introduces some challenging identification problems, as the discrete-time parameters become a non-linear

Leonardo C. Kammer; Farhad Ein-Mozaffari; Guy A. Dumont; Chad P. J. Bennington

2005-01-01

368

Performance degradation due to polarization effects in a dispersion-managed-soliton recirculating loop system  

Microsoft Academic Search

We investigate the performance degradation in dispersion-managed soliton systems caused by polarization-dependent loss and polarization-mode dispersion using a 600-km recirculating loop. We show that in an ultralong-haul transmission system, polarization effects can easily induce a variation in the bit-error rate (BER) greater than two orders of magnitude. In addition, polarization scattering caused by soliton collisions in wavelength-division-multiplexing systems makes the

Chongjin Xie; Andrew R. Grant; Linn F. Mollenauer; Xiang Liu

2004-01-01

369

A recirculating linac-based facility for ultrafast x-ray science  

Microsoft Academic Search

We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac, in particular the incorporation of EUV and soft x-ray production. The project has been named LUX - Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization

J. N. Corlett; W. A. Barletta; S. DeSantis; L. Doolittle; W. M. Fawley; M. A. Green; P. Heimann; S. Leone; S. Lidia; D. Li; A. Ratti; K. Robinson; R. Schoenlein; J. Staples; W. Wan; R. Wells; A. Wolski; A. Zholents; F. Parmigiani; M. Placidi; W. Pirkl; R. A. Rimmer; S. Wang

2003-01-01

370

Recirculating accelerator driver for a high-power free-electron laser: a design overview  

Microsoft Academic Search

Jefferson Lab is building a free-electron laser (FEL) to produce continuous-wave (cw), kW-level light at 3-6 ?m wavelength. A superconducting linac will drive the laser, generating a 5 mA average current, 42 MeV energy electron beam. A transport lattice will recirculate the beam back to the linac for deceleration and conversion of about 75% of its power into rf power.

Courtlandt L. Bohn

1997-01-01

371

Molecular absorbent recirculating system for the treatment of acute liver failure in surgical patients  

Microsoft Academic Search

The Molecular Adsorbent Recirculating System (MARS) represents an attractive artificial liver support system for the treatment\\u000a of liver insufficiency. However, neither indications for MARS treatment (i.e., after extended liver resection) nor criteria\\u000a for discontinuation of therapy have been evaluated. Therefore, we analyzed the clinical data of all our surgical patients\\u000a who received MARS treatment for acute liver failure (n =

Daniel Inderbitzin; Beat Muggli; Annette Ringger; Guido Beldi; Markus Gass; Beat Gloor; Dominik Uehlinger; Bruno Regli; Jürg Reichen; Daniel Candinas

2005-01-01

372

Inhibition of seedling growth of crop species by recirculating root exudates of Bidens pilosa L  

Microsoft Academic Search

The allelopathic effects of root exudates ofBidens pilosa L. on seedling growth ofLactuca sativa L.,Phaseolus vulgaris L.,Zea mays L., andSorghum bicolor (L.) Moench were studied using a root exudate recirculating system that allows continuous exposure of crop plants to allelopathic chemicals. This system maintains an undisturbed rhizosphere and eliminates competition and physical contact between the donor and acceptor plants. Comparison

Gordon A. Stevens; Chung-Shih Tang

1985-01-01

373

High gradient magnetic beneficiation of dry pulverized coal via upwardly directed recirculating fluidization  

DOEpatents

This invention relates to an improved device and method for the high gradient magnetic beneficiation of dry pulverized coal, for the purpose of removing sulfur and ash from the coal whereby the product is a dry environmentally acceptable, low-sulfur fuel. The process involves upwardly directed recirculating air fluidization of selectively sized powdered coal in a separator having sections of increasing diameters in the direction of air flow, with magnetic field and flow rates chosen for optimum separations depending upon particulate size.

Eissenberg, David M. (Oak Ridge, TN); Liu, Yin-An (Opelika, AL)

1980-01-01

374

Zoning, equity, and public health.  

PubMed Central

Zoning, the most prevalent land use planning tool in the United States, has substantial implications for equity and public health. Zoning determines where various categories of land use may go, thereby influencing the location of resulting environmental and health impacts. Industrially zoned areas permit noxious land uses and typically carry higher environmental burdens than other areas. Using New York City as a case study, the author shows that industrial zones have large residential populations within them or nearby. Noxious uses tend to be concentrated in poor and minority industrial neighborhoods because more affluent industrial areas and those with lower minority populations are rezoned for other uses, and industrial zones in poorer neighborhoods are expanded. Zoning policies, therefore, can have adverse impacts on public health and equity. The location of noxious uses and the pollution they generate have ramifications for global public health and equity; these uses have been concentrated in the world's poorer places as well as in poorer places within more affluent countries. Planners, policymakers, and public health professionals must collaborate on a worldwide basis to address these equity, health, and land use planning problems.

Maantay, J

2001-01-01

375

Computations of longitudinal electron dynamics in the recirculating CW RF accelerator-recuperator for the high average power FEL.  

National Technical Information Service (NTIS)

The use of optimal longitudinal phase-energy motions conditions for bunched electrons in a recirculating RF accelerator gives the possibility to increase the final electron peak current and, correspondingly, the FEL gain. 2 refs. (Atomindex citation 25:05...

A. S. Sokolov N. A. Vinokurov

1993-01-01

376

Final Environmental Assessment: Recirculation of Recaptured Water Year 2013-2017 San Joaquin River Restoration Program Flows.  

National Technical Information Service (NTIS)

Pursuant to the National Environmental Policy Act, the Department of the Interior, Bureau of Reclamation (Reclamation) is preparing this Final Environmental Assessment for the Recirculation of Recaptured Water Year 2013-2017 (Final WY 2013-2017 Recirculat...

2013-01-01

377

CO(2) Capture for PC Boilers using Flue-Gas Recirculation: Evaluation of CO(2) Recovery, Transport, and Utilization.  

National Technical Information Service (NTIS)

The U.S. Department of Energy (DOE) is investigating retrofitting boilers with flue gas recirculation as a strategy for CO(2) recovery from conventional pulverized coal (PC) plants because of the current motivation to reduce greenhouse gas emissions. Howe...

R. D. Doctor J. C. Molburg N. F. Brockmeier M. Mendelsohn

2002-01-01

378

Discovery of Deformation Band Damage Zones on Mars  

NASA Astrophysics Data System (ADS)

High-resolution structural mapping within the layered deposits in west Candor Chasma provide the first detailed documentation of fault-related damage zones on Mars. These damage zones are interpreted to be largely composed of deformation bands.

Okubo, C. H.

2012-03-01

379

Performance of anaerobic hybrid reactors for the treatment of complex phenolic wastewaters with biogas recirculation.  

PubMed

This study investigates the application of a novel anaerobic hybrid reactor (AHR) configuration, incorporating support media for biomass immobilisation and biogas recirculation for improved mixing towards the anaerobic treatment of complex phenolic wastewater. Synthetic coal wastewater with an average phenolics and COD concentration of 752 and 2240 mg L(-1) was used as substrate. Biogas recirculation was employed at four different rates of 11.25, 16.87, 25.30 and 37.95 L d(-1) for 100 days. Phenolics and COD removal improved with increase in biogas recirculation. After 120 days of continuous operation, the results revealed that a high amount (14.0 g VSS) of biomass was able to attach itself to the support medium. The investigated AHR configuration achieved phenolics and COD removal efficiencies of 95% and 92% respectively at a hydraulic retention time (HRT) of 0.33 d. The corresponding average methane production obtained in this study was 0.02 mol methane g(-1) COD. PMID:23232220

Ramakrishnan, Anushuya; Surampalli, Rao Y

2013-02-01

380

Upwelling-triggered near-geostrophic recirculation in an equatorward facing embayment  

NASA Astrophysics Data System (ADS)

Underway current velocity profiles were combined with hydrographic profiles at the entrance to Tongoy Bay, an equatorward facing bay in north-central Chile, with the objective of determining its exchange hydrodynamics. To the west, Tongoy Bay is bounded by Lengua de Vaca Point, a ˜6 km-long northward protruding peninsula. Observations were obtained during three surveys (April 2005, December 2005, May 2009) along cross-bay transects for at least one full day. During the surveys, winds were upwelling-favorable and displayed diurnal variations. Non-tidal (tidally averaged) flows showed a consistent clockwise or southern hemisphere cyclonic, recirculation during the three surveys. This recirculation was likely part of a cyclonic gyre (10-20 km in diameter), not entirely resolved by the surveys, and formed by flow separation off Lengua de Vaca Point. Estimates of the baroclinic pressure gradient, combined with analytical solutions of density-driven and wind-driven flows, indicated that the recirculation in Tongoy Bay was nearly in geostrophic balance. An ageostrophic contribution to the dynamics was related to frictional effects derived from local upwelling-favorable winds. A linear superposition of the analytically derived density-driven and wind-driven exchange resulted in a flow pattern that resembled the observed net exchange flows at the bay mouth.

Moraga-Opazo, Julio; Valle-Levinson, Arnoldo; Ramos, Marcel; Pizarro-Koch, Matías

2011-12-01

381

Microfluidic device capable of medium recirculation for non-adherent cell culture.  

PubMed

We present a microfluidic device designed for maintenance and culture of non-adherent mammalian cells, which enables both recirculation and refreshing of medium, as well as easy harvesting of cells from the device. We demonstrate fabrication of a novel microfluidic device utilizing Braille perfusion for peristaltic fluid flow to enable switching between recirculation and refresh flow modes. Utilizing fluid flow simulations and the human promyelocytic leukemia cell line, HL-60, non-adherent cells, we demonstrate the utility of this RECIR-REFRESH device. With computer simulations, we profiled fluid flow and concentration gradients of autocrine factors and found that the geometry of the cell culture well plays a key role in cell entrapping and retaining autocrine and soluble factors. We subjected HL-60 cells, in the device, to a treatment regimen of 1.25% dimethylsulfoxide, every other day, to provoke differentiation and measured subsequent expression of CD11b on day 2 and day 4 and tumor necrosis factor-alpha (TNF-?) on day 4. Our findings display perfusion sensitive CD11b expression, but not TNF-? build-up, by day 4 of culture, with a 1:1 ratio of recirculation to refresh flow yielding the greatest increase in CD11b levels. RECIR-REFRESH facilitates programmable levels of cell differentiation in a HL-60 non-adherent cell population and can be expanded to other types of non-adherent cells such as hematopoietic stem cells. PMID:24753733

Dixon, Angela R; Rajan, Shrinidhi; Kuo, Chuan-Hsien; Bersano, Tom; Wold, Rachel; Futai, Nobuyuki; Takayama, Shuichi; Mehta, Geeta

2014-01-01

382

Bacterial community structure in cooling water and biofilm in an industrial recirculating cooling water system.  

PubMed

Microbial fouling is a serious problem in open recirculating cooling water systems. The bacterial communities that cause it have not been fully understood. In this study, we analyzed the community structure of free-living bacteria and particle-attached bacteria in cooling water, and bacteria in biofilm collected from the wall of the water reservoir in an industrial recirculating cooling water system by construction of a 16S rRNA gene clone library. Based on amplified ribosomal DNA restriction analysis, clones of all three libraries were clustered into 45 operational taxonomic units (OTUs). Thirteen OTUs displaying 91-96% sequence similarity to a type strain might be novel bacterial species. Noted differences in community structure were observed among the three libraries. The relative species richness of the free-living bacteria in cooling water was much lower than that of particle-attached bacteria and bacteria in biofilm. The majority of the free-living bacterial community (99.0%) was Betaproteobacteria. The predominant bacteria in the particle-attached bacterial community were Alphaproteobacteria (20.5%), Betaproteobacteria (27.8%) and Planctomycetes (42.0%), while those in the biofilm bacterial community were Alphaproteobacteria (47.9%), Betaproteobacteria (11.7%), Acidobacteria (13.1%) and Gemmatimonadetes (11.3%). To control microbial fouling in industrial recirculating cooling water systems, additional physiological and ecological studies of these species will be essential. PMID:23985528

Wang, Jinmei; Liu, Min; Xiao, Huijie; Wu, Wei; Xie, Meijuan; Sun, Mengjia; Zhu, Chenglin; Li, Pengfu

2013-01-01

383

Computations of longitudinal electron dynamics in the recirculating cw RF accelerator-recuperator for the high average power FEL  

NASA Astrophysics Data System (ADS)

The use of optimal longitudinal phase-energy motion conditions for bunched electrons in a recirculating RF accelerator gives the possibility to increase the final electron peak current and, correspondingly, the FEL gain. The computer code RECFEL, developed for simulations of the longitudinal compression of electron bunches with high average current, essentially loading the cw RF cavities of the recirculator-recuperator, is briefly described and illustrated by some computational results.

Sokolov, A. S.; Vinokurov, N. A.

1994-03-01

384

Generation of Flat Optical Frequency Comb based on Mach-Zehnder Modulator and Recirculating Frequency Shifter Loop  

NASA Astrophysics Data System (ADS)

We propose a novel scheme to generate optical frequency comb by using Mach-Zehnder modulator and recirculating frequency shifter loop based on IQ modulator driven by radio frequency clock signals. A system of 4 flat and stable comb lines generation based on Mach-Zehnder modulator is set as the seed light source of the recirculating loop. Through theorical analysis and simulation it is shown that the proposed theoretical model is proved in good agreement with simulation results.

Wu, Shibao; Li, Yulong; Fei, Yue; Hu, Faze

2014-06-01

385

Vadose zone microbiology  

SciTech Connect

The vadose zone is defined as the portion of the terrestrial subsurface that extends from the land surface downward to the water table. As such, it comprises the surface soil (the rooting zone), the underlying subsoil, and the capillary fringe that directly overlies the water table. The unsaturated zone between the rooting zone and the capillary fringe is termed the "intermediate zone" (Chapelle, 1993). The vadose zone has also been defined as the unsaturated zone, since the sediment pores and/or rock fractures are generally not completely water filled, but instead contain both water and air. The latter characteristic results in the term "zone of aeration" to describe the vadose zone. The terms "vadose zone," "unsaturated zone", and "zone of aeration" are nearly synonymous, except that the vadose zone may contain regions of perched water that are actually saturated. The term "subsoil" has also been used for studies of shallow areas of the subsurface immediately below the rooting zone. This review focuses almost exclusively on the unsaturated region beneath the soil layer since there is already an extensive body of literature on surface soil microbial communities and process, e.g., Paul and Clark (1989), Metting (1993), Richter and Markowitz, (1995), and Sylvia et al. (1998); whereas the deeper strata of the unsaturated zone have only recently come under scrutiny for their microbiological properties.

Kieft, Thomas L.; Brockman, Fred J.

2001-01-17

386

Duration of a large Mafic intrusion and heat transfer in the lower crust: A SHRIMP U-Pb zircon Study in the Ivrea-Verbano Zone (Western Alps, Italy)  

USGS Publications Warehouse

The Ivrea-Verbano Zone in the western Italian Alps contains one of the world's classic examples of ponding of mantle-derived, mafic magma in the deep crust. Within it, a voluminous, composite mafic pluton, the Mafic Complex, intruded lower-crustal, high-grade paragneiss of the Kinzigite Formation during Permian-Carboniferous time, and is now exposed in cross-section as a result of Alpine uplift. The age of the intrusion is still debated because the results of geochronological studies in the last three decades on different rock types and with various dating techniques range from 250 to about 300 Ma. Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon age determinations on 12 samples from several locations within the Mafic Complex were performed to better constrain the age of the igneous event. The results indicate a long history of magma emplacement and cooling, which reconciles the spread in previously published ages. The main intrusive phase took place at 288 ?? 4 Ma, causing a perturbation of the deep-crustal geotherm, which relaxed to the Sm-Nd closure temperature in garnet-free mafic rocks after about 15-20 Myr of sub-solidus cooling at c. 270 Ma. These results suggest that large, deep crustal plutons, such as those identified geophysically at depths of 10-20 km within extended continental crust (e.g. Yellowstone, Rio Grande Rift, Basin and Range) may have formed rapidly but induced a prolonged thermal perturbation. In addition, the data indicate that a significant thermal event affected the country rock of the Mafic Complex at about 310 Ma. The occurrence of an upper amphibolite- to granulite-facies thermal event in the Kinzigite Formation prior to the main intrusive phase of the Mafic Complex has been postulated by several workers, and is corroborated by other geochronological investigations. However, it remains uncertain whether this event (1) was part of a prolonged perturbation of the deep-crustal geotherm, which started long before the onset of intrusion of the Mafic Complex, or (2) corresponded to the intrusion of the first sills of the Mafic Complex, or (3) was related to an earlier, independent thermal pulse. ?? The Author 2007. Published by Oxford University Press. All rights reserved.

Peressini, G.; Quick, J. E.; Sinigoi, S.; Hofmann, A. W.; Fanning, M.

2007-01-01

387

Large Eddy Simulations of Volume Restriction Effects on Canopy-Induced Increased-Uplift Regions  

NASA Astrophysics Data System (ADS)

ABSTRACT Previous modeling and empirical work have shown the development of important areas of increased uplift past forward-facing steps, and recirculation zones past backward-facing steps. Forests edges represent a special kind of step - a semi-porous one. Current models of the effects of forest edges on the flow represent the forest with a prescribed drag term and does not account for the effects of the solid volume in the forest that restrict the airflow. The RAMS-based Forest Large Eddy Simulation (RAFLES) resolves flows inside and above forested canopies. RAFLES is spatially explicit, and uses the finite volume method to solve a descretized set of Navier-Stokes equations. It accounts for vegetation drag effects on the flow and on the flux exchange between the canopy and the canopy air, proportional to the local leaf density. For a better representation of the vegetation structure in the numerical grid within the canopy sub-domain, the model uses a modified version of the cut cell coordinate system. The hard volume of vegetation elements, in forests, or buildings, in urban environments, within each numerical grid cell is represented via a sub-grid-scale process that shrinks the open apertures between grid cells and reduces the open cell volume. We used RAFLES to simulate the effects of a canopy of varying foliage and stem densities on flow over virtual qube-shaped barriers under neutrally buoyant conditions. We explicitly tested the effects of the numerical representation of volume restriction, independent of the effects of the leaf drag by comparing drag-only simulations, where we prescribed no volume or aperture restriction to the flow, restriction-only simulations, where we prescribed no drag, and control simulations, where both drag and volume plus aperture restriction were included. Our simulations show that representation of the effects of the volume and aperture restriction due to obstacles to flow is important (figure 1) and leads to differences in the strengths and locations of increased-updraft and recirculation zones. Particularly, introduction of volume restriction shifted the location of the uplift zone and anchored it to the downwind edge of the barrier. In addition. We propose that volume restriction due to the presence of the stems and branches is an important improvement to LES that should be considered. Figure 1: Horizontal and vertical wind components (arrows) illustrated across a vertical cross section through the simulation domain. The colors illustrate the variation of the vertical wind component. The canopy location is marked by a thick continuous line. A. Drag-only simulation (Drag = 0.04?, Volume blockage = 0%), B. Control simulation (Drag = 0.04?, Volume blockage = 40%).

Chatziefstratiou, E.; Bohrer, G.; Velissariou, V.

2012-12-01

388

High-rate algal pond treatment for water reuse in an integrated marine fish recirculating system: effect on water quality and sea bass growth  

Microsoft Academic Search

A high-rate algae pond (HRAP) was tested as a second loop of water treatment in a recirculating fish rearing system to reduce water requirements and nutrient discharge levels. Three duplicated groups of sea bass (mean initial body weight 35±11 g) were reared under different system conditions (flow-through system, recirculating system and recirculating system with HRAP) for 1 year. Fish survival

Geneviève Deviller; Catherine Aliaume; Miguel Angel Franco Nava; Claude Casellas; Jean Paul Blancheton

2004-01-01

389

Kane Fracture Zone.  

National Technical Information Service (NTIS)

The Kane Fracture Zone probably is better covered by geophysical survey data, acquired both by design and incidentally, than any other fracture zone in the North Atlantic Ocean. We have used this data to map the basement morphology of the fracture zone an...

B. E. Tucholke H. Schouten

1988-01-01

390

Polygonal Fresnel zone plates  

Microsoft Academic Search

The performance of Fresnel zone plates having a polygonal boundary between zones has been studied. The contribution of the complex amplitude of each zone is calculated analytically and numerically solved. The case of a continuous phase plate is considered as the limit case in performance for each polygonal shape. This performance is compared with respect to the circular case. Also

Javier Alda; Francisco Javier González

2009-01-01

391

Speed Zoning and Control.  

National Technical Information Service (NTIS)

Field studies have been conducted at a limited number of Texas Sites to investigate and evaluate speed zoning procedures (1) at speed zones in rapidly developing urban fringe areas, (2) at transition section speed zones on highway approaches to cities or ...

C. L. Dudek G. L. Ullman

1987-01-01

392

Figure This: Time Zones  

NSDL National Science Digital Library

This is an activity featuring a time zone map useful when teaching an interdisciplinary social studies and math unit focusing on geography and the time zones. It underscores the role of the earth's rotation in everyday life, and the need to understand the relationships between earth rotation, day and night, and time zones around the world.

2004-01-01

393

Involvement of Sialic Acid on Endothelial Cells in Organ-Specific Lymphocyte Recirculation  

NASA Astrophysics Data System (ADS)

Mouse lymphocytes incubated on cryostat-cut sections of lymphoid organs (lymph nodes and Peyer's patches) specifically adhere to the endothelium of high endothelial venules (HEV), the specialized blood vessels to which recirculating lymphocytes attach as they migrate from the blood into the parenchyma of the lymphoid organs. Treatment of sections with sialidase eliminated the binding of lymphocytes to peripheral lymph node HEV, had no effect on binding to Peyer's patch HEV, and had an intermediate effect on mesenteric lymph node HEV. These results suggest that sialic acid on endothelial cells may be an organ-specific recognition determinant for lymphocyte attachment.

Rosen, Steven D.; Singer, Mark S.; Yednock, Ted A.; Stoolman, Lloyd M.

1985-05-01

394

Degradation of oleic acid in anaerobic filters: the effect of inoculum acclimatization and biomass recirculation.  

PubMed

The degradation of oleic acid in anaerobic filters was studied and the effect of an acclimated inoculum and biomass recirculation was evaluated. Three anaerobic filters (R1, R2, and R3) were operated in parallel. The anaerobic filters R1 and R2 were inoculated with nonacclimated biomass, whereas the anaerobic filter R3 was inoculated with acclimated biomass. In the anaerobic filters R2 and R3, biomass settling and recirculation were applied. The use of an acclimated inoculum and biomass recirculation (R3) was beneficial in terms of removal efficiency, which was 4 to 8% higher than in the anaerobic filters R1 and R2 when oleate was the sole carbon source fed to the reactors at an applied organic load of 12.5 kg of chemical oxygen demand (COD)/m3 x d, even with an oleate to calcium and magnesium ion molar concentration ratio of 6.8. Biomass recirculation significantly reduced the biomass washout and the toxic effect on the acetogenic and methanogenic populations. The use of an acclimated inoculum was beneficial in terms of methane yield, which was 50% greater than that observed for the reactors inoculated with nonacclimated inoculum for the highest applied organic loading rate (12.5 kg COD/m3 x d). At the end of the operation, the biomass was encapsulated by a whitish matter, which was well detected by microscopic examination. When this sludge was incubated in batch vials at 37 degrees C where no substrate was added, methane production from the adsorbed organic matter was evidenced, attaining a maximum value (at standard temperature and pressure) of 39.7 mL/g volatile solids x d for the biomass taken from R1. With stirring (150 r/min), the methane production rate was 13.8 times higher than under static conditions. When oleate was added to this sludge, methane production was delayed, suggesting that adsorbed matter can be an intermediate of oleate degradation such as stearic, palmitic, myristic, or other saturated acids. PMID:11765998

Pereira, A; Mota, M; Alves, M

2001-01-01

395

Characterization of Fault Zones  

NASA Astrophysics Data System (ADS)

- There are currently three major competing views on the essential geometrical, mechanical, and mathematical nature of faults. The standard view is that faults are (possibly segmented and heterogeneous) Euclidean zones in a continuum solid. The continuum-Euclidean view is supported by seismic, gravity, and electromagnetic imaging studies; by successful modeling of observed seismic radiation, geodetic data, and changes in seismicity patterns; by detailed field studies of earthquake rupture zones and exhumed faults; and by recent high resolution hypocenter distributions along several faults. The second view focuses on granular aspects of fault structures and deformation fields. The granular view is supported by observations of rock particles in fault zone gouge; by studies of block rotations and the mosaic structure of the lithosphere (which includes the overall geometry of plate tectonics); by concentration of deformation signals along block boundaries; by correlation of seismicity patterns on scales several times larger than those compatible with a continuum framework; and by strongly heterogeneous wave propagation effects on the earth's surface. The third view is that faults are fractal objects with rough surfaces and branching geometry. The fractal view is supported by some statistical analysis of regional hypocenter locations; by long-range correlation of various measurements in geophysical boreholes; by the fact that observed power-law statistics of earthquakes are compatible with an underlying scale-invariant geometrical structure; by geometrical analysis of fault traces at the earth's surface; and by measurements of joint and fault surfaces topography.There are several overlaps between expected phenomenology in continuum-Euclidean, granular, and fractal frameworks of crustal deformation. As examples, highly heterogeneous seismic wavefields can be generated by granular media, by fractal structures, and by ground motion amplification around and scattering from an ensemble of Euclidean fault zones. A hierarchical granular structure may have fractal geometry. Power-law statistics of earthquakes can be generated by slip on one or more heterogeneous planar faults, by a fractal collection of faults, and by deformation of granular material. Each of the three frameworks can produce complex spatio-temporal patterns of earthquakes and faults. At present the existing data cannot distinguish unequivocally between the three different views on the nature of fault zones or determine their scale of relevance. However, in each observational category, the highest resolution results associated with mature large-displacement faults are compatible with the standard continuum-Euclidean framework. This can be explained by a positive feedback mechanism associated with strain weakening rheology and localization, which attracts the long-term evolution of faults toward progressive regularization and Euclidean geometry. A negative feedback mechanism associated with strain hardening during initial deformation phases and around persisting geometrical irregularities and conjugate sets of faults generates new fractures and granularity at different scales. We conclude that long-term deformation in the crust, including many aspects of the observed spatio-temporal complexity of earthquakes and faults, may be explained to first order within the continuum-Euclidean framework.

Ben-Zion, Y.; Sammis, C. G.

396

Adenovirus Vector-Induced CD8+ T Effector Memory Cell Differentiation and Recirculation, But Not Proliferation, Are Important for Protective Immunity Against Experimental Trypanosoma cruzi Infection  

PubMed Central

Abstract Heterologous prime-boost vaccination using plasmid DNA followed by replication-defective adenovirus vector generates a large number of specific CD8+ T effector memory (TEM) cells that provide long-term immunity against a variety of pathogens. In the present study, we initially characterized the frequency, phenotype, and function of these T cells in vaccinated mice that were subjected to infectious challenge with the human protozoan parasite Trypanosoma cruzi. We observed that the frequency of the specific CD8+ T cells in the spleens of the vaccinated mice increased after challenge. Specific TEM cells differentiated into cells with a KLRG1High CD27Low CD43Low CD183LowT-betHigh EomesLow phenotype and capable to produce simultaneously the antiparasitic mediators IFN? and TNF. Using the gzmBCreERT2/ROSA26EYFP transgenic mouse line, in which the cells that express Granzyme B after immunization, are indelibly labeled with enhanced yellow fluorescent protein, we confirmed that CD8+ T cells present after challenge were indeed TEM cells that had been induced by vaccination. Subsequently, we observed that the in vivo increase in the frequency of the specific CD8+ T cells was not because of an anamnestic immune response. Most importantly, after challenge, the increase in the frequency of specific cells and the protective immunity they mediate were insensitive to treatment with the cytostatic toxic agent hydroxyurea. We have previously described that the administration of the drug FTY720, which reduces lymphocyte recirculation, severely impairs protective immunity, and our evidence supports the model that when large amounts of antigen-experienced CD8+ TEM cells are present after heterologous prime-boost vaccination, differentiation, and recirculation, rather than proliferation, are key for the resultant protective immunity.

Vasconcelos, Jose Ronnie; Dominguez, Mariana R.; Neves, Ramon L.; Ersching, Jonatan; Araujo, Adriano; Santos, Luara I.; Virgilio, Fernando S.; Machado, Alexandre V.; Bruna-Romero, Oscar; Gazzinelli, Ricardo T.

2014-01-01

397

Adenovirus vector-induced CD8? T effector memory cell differentiation and recirculation, but not proliferation, are important for protective immunity against experimental Trypanosoma cruzi Infection.  

PubMed

Heterologous prime-boost vaccination using plasmid DNA followed by replication-defective adenovirus vector generates a large number of specific CD8? T effector memory (TEM) cells that provide long-term immunity against a variety of pathogens. In the present study, we initially characterized the frequency, phenotype, and function of these T cells in vaccinated mice that were subjected to infectious challenge with the human protozoan parasite Trypanosoma cruzi. We observed that the frequency of the specific CD8? T cells in the spleens of the vaccinated mice increased after challenge. Specific TEM cells differentiated into cells with a KLRG1(High) CD27(Low) CD43(Low) CD183(Low)T-bet(High) Eomes(Low) phenotype and capable to produce simultaneously the antiparasitic mediators IFN? and TNF. Using the gzmBCreERT2/ROSA26EYFP transgenic mouse line, in which the cells that express Granzyme B after immunization, are indelibly labeled with enhanced yellow fluorescent protein, we confirmed that CD8? T cells present after challenge were indeed TEM cells that had been induced by vaccination. Subsequently, we observed that the in vivo increase in the frequency of the specific CD8? T cells was not because of an anamnestic immune response. Most importantly, after challenge, the increase in the frequency of specific cells and the protective immunity they mediate were insensitive to treatment with the cytostatic toxic agent hydroxyurea. We have previously described that the administration of the drug FTY720, which reduces lymphocyte recirculation, severely impairs protective immunity, and our evidence supports the model that when large amounts of antigen-experienced CD8? TEM cells are present after heterologous prime-boost vaccination, differentiation, and recirculation, rather than proliferation, are key for the resultant protective immunity. PMID:24568548

Vasconcelos, José Ronnie; Dominguez, Mariana R; Neves, Ramon L; Ersching, Jonatan; Araújo, Adriano; Santos, Luara I; Virgilio, Fernando S; Machado, Alexandre V; Bruna-Romero, Oscar; Gazzinelli, Ricardo T; Rodrigues, Mauricio M

2014-04-01

398

Investigation of sludge re-circulating clarifiers design and optimization through numerical simulation.  

PubMed

In steam thermal power plants (TPP) with open re-circulating wet cooling towers, elimination of water hardness and suspended solids (SS) is performed in clarifiers. Most of these clarifiers are of high efficiency sludge re-circulating type (SRC) with capacity between 500-1,500 m3/hr. Improper design and/or mal-operation of clarifiers in TPPs results in working conditions below design capacity or production of soft water with improper quality (hardness and S.S.). This causes accumulation of deposits in heat exchangers, condenser tubes, cooling and service water pipes and boiler tubes as well as increasing the ionic load of water at the demineralizing system inlet. It also increases the amount of chemical consumptions and produces more liquid and solid waste. In this regard, a software program for optimal design and simulation of SRCs has been developed. Then design parameters of existing SRCs in four TPPs in Iran were used as inputs to developed software program and resulting technical specifications were compared with existing ones. In some cases improper design was the main cause of poor outlet water quality. In order to achieve proper efficiency, further investigations were made to obtain control parameters as well as design parameters for both mal-designed and/or mal-operated SRCs. PMID:14753549

Davari, S; Lichayee, M J

2003-01-01

399

Tritium Superpermeability: Experimental Investigation and Simulation of Tritium Recirculation in 'Prometheus' Setup  

SciTech Connect

The superpermeability phenomenon was suggested to use in fusion machines to separate the fuel mixture from helium ashes, to arrange in-vessel fuel recirculation contours and effective evacuation of fuel mixture out of machine exhaust. To develop this technology and to simulate tritium recirculation in RFNC-VNIIEF at the 'Prometheus' setup the experiments on superpermeation of hydrogen isotopes through metal membrane were realized.The results of experiments on superpermeation of hydrogen isotopes through cylindrical niobium membrane are presented. As the experiment has shown, membrane pumping rate is inversely proportional to square root of isotope mass and amount to 2.5 l/cm{sup 2}s for protium, 1.8 l/cm{sup 2}s for deuterium and 1.5 l/cm{sup 2}s for tritium. The possibility of effective pumping, separation of hydrogen isotopes from helium and residual gas, compression and recuperation of hydrogen isotopes by means of superpermeable membrane was demonstrated. It follows from results that the separation of D/T from He with employment of the techniques of superpermeable membranes might reduce the total amount of tritium in fuel cycle and substantially enhance the resource of cryogenic pumps evacuating helium.

Musyaev, R.K. [Russian Federal Nuclear Center-All-Russian Research Institute of Experimental Physics (Russian Federation); Lebedev, B.S. [Russian Federal Nuclear Center-All-Russian Research Institute of Experimental Physics (Russian Federation); Grishechkin, S.K. [Russian Federal Nuclear Center-All-Russian Research Institute of Experimental Physics (Russian Federation); Yukhimchuk, A.A. [Russian Federal Nuclear Center-All-Russian Research Institute of Experimental Physics (Russian Federation); Busnyuk, A.A [St.-Peterburg State University of Telecommunications (Russian Federation); Notkin, M.E. [St.-Peterburg State University of Telecommunications (Russian Federation); Samartsev, A.A. [St.-Peterburg State University of Telecommunications (Russian Federation); Livshits, A.I. [St.-Peterburg State University of Telecommunications (Russian Federation)

2005-07-15

400

Leachate recirculation: moisture content assessment by means of a geophysical technique.  

PubMed

Bioreactor technology is a waste treatment concept consisting in speeding up the biodegradation of landfilled waste by optimizing its moisture content through leachate recirculation. The measurement of variations in waste moisture content is critical in the design and control of bioreactors. Conventional methods such as direct physical sampling of waste reach their limits due to the interference with the waste matrix. This paper reviews geophysical measurements such as electrical direct current and electromagnetic slingram methods for measuring the electrical conductivity. Electrical conductivity is a property, which is linked to both moisture and temperature and can provide useful indications on the biodegradation environment in the waste mass. The study reviews three site experiments: a first experimentation shows the advantages (correlation between conductive anomaly and water seepage) but also the limits of geophysical interpretation; the two other sites allow the leachate recirculation to be tracked by studying the relative resistivity variation versus time from electrical 2D imaging. Even if some improvements are necessary to consider geophysical measurements as a real bioreactor monitoring tool, results are promising and could lead to the use of electrical 2D imaging in bioreactor designing. PMID:15381230

Guérin, Roger; Munoz, Marie Laure; Aran, Christophe; Laperrelle, Claire; Hidra, Mustapha; Drouart, Eric; Grellier, Solenne

2004-01-01

401

LUX - A Recirculating Linac-based Ultrafast X-ray Source  

SciTech Connect

We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV range, and is followed by four passes through a 700 MeV recirculating linac. Ultrafast hard x-ray pulses are obtained by a combination of electron bunch manipulation, transverse temporal correlation of the electrons, and x-ray pulse compression. EUV and soft x-ray pulses as short as 10 fs are generated in a harmonic-cascade free electron laser scheme. We describe the facility major systems and performance.

Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.R.; Lidia, S.; Li, D.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Zholents, A. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Parmigiani, F. [Laboratorio TASC-INFM (Italy)

2004-05-12

402

Effects of Exhaust Gas Recirculation on SI Engines at Wide Open Throttle  

NASA Astrophysics Data System (ADS)

Exhaust gas recirculation, a charge dilution technique, has proven to be an effective method of reducing NOx emissions and fuel consumption of spark ignition engines. Wide open throttle operation also increases overall engine efficiency by reducing the pumping losses caused by throttling. In this study, the emissions and fuel economy benefits of exhaust gas recirculation (EGR) at wide open throttle conditions were quantified using a 2.4L port-injected engine. Engine performance and emissions data were recorded as the percentage of EGR in the intake charge was increased from zero to just above thirty percent (the EGR limit). This EGR percentage, in-cylinder pressure measurements, and the temperatures and pressures of the intake and exhaust were all recorded to ensure stable operating conditions. These tests were performed with a stoichiometric air-fuel ratio at a constant speed of 2000 rpm at wide open throttle. The variation of brake specific fuel consumption and emissions (in particular NOx) with increasing EGR percentages was analyzed.

Bronson, Sydney; Puzinauskas, Paulius

2011-11-01

403

Numerical Investigation of Turbulent Shallow Recirculating Flows by a Quasi-Three k-MODEL  

NASA Astrophysics Data System (ADS)

A quasi-three-dimensional multilayer k- model has been developed to simulate turbulent recirculating flows behind a sudden expansion in shallow waters. The model accounts for the vertical variation in the flow quantities and eliminates the problem of closure for the effective stresses resulting from the depth integration of the non-linear convective accelerations found in the widely used depth- integrated models. The governing equations are split into three parts in the finite difference solution: advection, dispersion and propagation. The advection part is solved using the four-node minimax-characteristics method. The dispersion and propagation parts are treated by the central difference method, the former being solved explicitly and the latter implicitly using the Gauss-Seidel iteration method. The relative effect of bed-generated turbulence and transverse shear-generated turbulence on the recirculating flow has been studied in detail. In comparison with the results computed by the depth-integrated k- model, the results computed by the present model are found to be closer to the reported data.

Li, C. W.; Yu, T. S.

1996-09-01

404

H2-CO2 Recirculation and pH Control for Growth of Methanogens in Mass Culture  

PubMed Central

We modified a fermentor (10-liter liquid volume) for the growth of anaerobic, H2-CO2-catabolizing bacteria. Gas in the fermentor (ca. 10% CO2, 50% H2, 40% CH4) was recirculated by a diaphragm pump. During growth, the gas composition was maintained by the addition of a mixture of 80% H2 and 20% CO2, and this addition was controlled by a pH auxostat. During gas addition, gas was discharged from the recirculating gas stream and was collected by the displacement of an acidified salt solution.

Boone, David R.; Mathrani, Indra M.; Mah, Robert A.

1987-01-01

405

Performance of large fan-filter units for cleanroom applications  

Microsoft Academic Search

Fan-filter units (FFUs) are widely used in clean space to re-circulate and remove particles out of the airflows directed to cleanrooms or minienvironments. Energy and aerodynamic performance of FFUs may largely influence both energy efficiency and effectiveness in contamination control in the cleanroom design, qualifications, and operation. This article presents laboratory-measured performance of seven relatively new and large FFUs, with

Tengfang Xu; Chao-Ho Lan; Ming-Shan Jeng

2007-01-01

406

Rapid Shear Zones - Unspecific Microstructures  

NASA Astrophysics Data System (ADS)

The record of episodic deformation at 500-550°C and 0.7+/-0.2 GPa was identified in eclogite- amphibolites on Rugsundoya island in the Western Gneiss Region of Norway, in the footwall of the low angle Nordfjord Sogn Detachment Zone (Birtel and Stöckhert 2008). An event of fracture formation was followed by inhomogeneous ductile deformation, during which the fractures developed into open cavities sealed by quartz. The structural relations indicate contemporaneous formation of veins and shear zones, also demonstrated by the fact that the quartz veins do nowhere transect the shear zones and the shear zones do nowhere transect the quartz veins. The deformation is ascribed to brittle failure driven by stress redistribution during a large earthquake, followed by an episode of inhomogeneous ductile deformation during postseismic stress relaxation. The peculiar record is thus interpreted to represent a single seismic cycle and to obey the respective time scales, with quasi-instantaneous loading and subsequent stress relaxation over time spans on the order of 102 to 103 years. If this is true, the shear zones linking the open cavities (now quartz veins) must have formed by markedly non-steady state deformation starting at high stress and very high strain rate. Here we examine the microfabrics of the shear zones. The amphibolite facies shear zones are made up of a fine-grained amphibole and plagioclase matrix, with a typical grain size of 0.1 mm for both phases. Millimetre-sized porphyroclasts of amphibole are widespread. The matrix microstructure is characterized by smooth grain and interphase boundaries. The amphiboles reveal a marked shape preferred orientation (SPO) combined with a crystallographic preferred orientation (CPO). In contrast to amphibole, plagioclase shows no CPO. The chemical composition of amphibole and plagioclase within the shear zones corresponds to that in the undeformed host rock, with only slight inhomogeneity and rather unsystematic zoning patterns in both porphyroclasts and matrix amphiboles. The microfabrics of the shear zones are found to be unspecific in terms of deformation mechanisms. The combined CPO and SPO is very common for amphiboles. It does not necessarily indicate deformation by dislocation creep, but can be the product of various processes from anisotropic growth to cataclastic flow (e.g. Brodie and Rutter 1985, Nyman et al. 1992). The unsystematic chemical zoning pattern and the tendency towards a low-energy grain shape indicates that the synkinematic microstructures became erased during annealing at amphibolite facies conditions. The term "blastomylonite" is therefore probably appropriate to characterize the fine-grained amphibolite within the shear zones. We conclude that rapid non-steady state ductile deformation, presumably by a variety of deformation mechanisms sequentially activated at decaying stress, leaves no specific record at the given temperatures of 500-550°C. The synkinematic microfabrics, including those developed at an early stage at exceptionally high strain rate, become obliterated by annealing at such temperatures. References Birtel, S. and Stöckhert, B (2008) Tectonophysics 457: 53-63. Brodie, K. H. and Rutter, E.H. (1985) in Kinetics, Textures, and Deformation. A. B. Thompson and D. C. Rubie. (eds) New York, Springer. 4: 138-179. Nyman, M. W., Law, R. D. and Smelik, E.A. (1992) Geology 20: 455-458.

Birtel, S.; Stoeckhert, B.

2008-12-01

407

Kane Fracture Zone  

Microsoft Academic Search

The Kane Fracture Zone probably is better covered by geophysical survey data, acquired both by design and incidentally, than\\u000a any other fracture zone in the North Atlantic Ocean. We have used this data to map the basement morphology of the fracture\\u000a zone and the adjacent crust for nearly 5700 km, from near Cape Hatteras to the middle of the Mesozoic

Brian E. Tucholke; Hans Schouten

1988-01-01

408

Zone plate interferometer  

NASA Technical Reports Server (NTRS)

A developed form of the Fresner zone-plate interferometer is described. Three basic configurations are distinguished, associated with the real and virtual first order foci of a zone plate. Related versions and higher order variants are also educed. Compensated phase zone plates used in this application are found to produce uniform amplitude wavefronts. The properties of the interferometer in this form are discussed and an example given of its high-quality performance.

Smartt, R. N.

1974-01-01

409

The performance and impact of a bubble-wash bead filter in a recirculating green water larval culture system for delta smelt ( Hypomesus transpacificus)  

Microsoft Academic Search

Delta smelt are cultured at the UC Davis Fish Conservation and Culture Lab (FCCL) for research purposes. The culture systems used are based on recirculation technology to ensure optimum water quality for the fish at each life stage. Larval culture takes place in recirculation systems with green water to which a Nannochloropsis algal concentrate is added to maintain a turbidity

Tien-Chieh Hung; Raul H. Piedrahita

2011-01-01

410