The Unevenly Distributed Nearest Brown Dwarfs

NASA Astrophysics Data System (ADS)

Bihain, Gabriel; Scholz, Ralf-Dieter

2016-08-01

To address the questions of how many brown dwarfs there are in the Milky Way, how do these objects relate to star formation, and whether the brown dwarf formation rate was different in the past, the star-to-brown dwarf number ratio can be considered. While main sequence stars are well known components of the solar neighborhood, lower mass, substellar objects increasingly add to the census of the nearest objects. The sky projection of the known objects at <6.5 pc shows that stars present a uniform distribution and brown dwarfs a non-uniform distribution, with about four times more brown dwarfs behind than ahead of the Sun relative to the direction of rotation of the Galaxy. Assuming that substellar objects distribute uniformly, their observed configuration has a probability of 0.1 %. The helio- and geocentricity of the configuration suggests that it probably results from an observational bias, which if compensated for by future discoveries, would bring the star-to-brown dwarf ratio in agreement with the average ratio found in star forming regions.

Combination of nano-material enrichment and dead-end filtration for uniform and rapid sample preparation in matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Wu, Zengnan; Khan, Mashooq; Mao, Sifeng; Lin, Ling; Lin, Jin-Ming

2018-05-01

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a fast analysis tool for the detection of a wide range of analytes. However, heterogeneous distribution of matrix/analyte cocrystal, variation in signal intensity and poor experimental reproducibility at different locations of the same spot means difficulty in quantitative analysis. In this work, carbon nanotubes (CNTs) were employed as adsorbent for analyte cum matrix on a conductive porous membrane as a novel mass target plate. The sample pretreatment step was achieved by enrichment and dead-end filtration and dried by a solid-liquid separation. This approach enables the homogeneous distribution of analyte in the matrix, good shot-to-shot reproducibility in signals and quantitative detection of peptide and protein at different concentrations with correlation coefficient (R 2 ) of 0.9920 and 0.9909, respectively. The simple preparation of sample in a short time, uniform distribution of analyte, easy quantitative detection, and high reproducibility makes this technique useful and may diversify the application of MALDI-MS for quantitative detection of a variety of proteins. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of visual cues of object density on perception and anticipatory control of dexterous manipulation.

PubMed

Crajé, Céline; Santello, Marco; Gordon, Andrew M

2013-01-01

Anticipatory force planning during grasping is based on visual cues about the object's physical properties and sensorimotor memories of previous actions with grasped objects. Vision can be used to estimate object mass based on the object size to identify and recall sensorimotor memories of previously manipulated objects. It is not known whether subjects can use density cues to identify the object's center of mass (CM) and create compensatory moments in an anticipatory fashion during initial object lifts to prevent tilt. We asked subjects (n = 8) to estimate CM location of visually symmetric objects of uniform densities (plastic or brass, symmetric CM) and non-uniform densities (mixture of plastic and brass, asymmetric CM). We then asked whether subjects can use density cues to scale fingertip forces when lifting the visually symmetric objects of uniform and non-uniform densities. Subjects were able to accurately estimate an object's center of mass based on visual density cues. When the mass distribution was uniform, subjects could scale their fingertip forces in an anticipatory fashion based on the estimation. However, despite their ability to explicitly estimate CM location when object density was non-uniform, subjects were unable to scale their fingertip forces to create a compensatory moment and prevent tilt on initial lifts. Hefting object parts in the hand before the experiment did not affect this ability. This suggests a dichotomy between the ability to accurately identify the object's CM location for objects with non-uniform density cues and the ability to utilize this information to correctly scale their fingertip forces. These results are discussed in the context of possible neural mechanisms underlying sensorimotor integration linking visual cues and anticipatory control of grasping.

Solid state thermal rectifier

DOEpatents

None

2016-07-05

Thermal rectifiers using linear nanostructures as core thermal conductors have been fabricated. A high mass density material is added preferentially to one end of the nanostructures to produce an axially non-uniform mass distribution. The resulting nanoscale system conducts heat asymmetrically with greatest heat flow in the direction of decreasing mass density. Thermal rectification has been demonstrated for linear nanostructures that are electrical insulators, such as boron nitride nanotubes, and for nanostructures that are conductive, such as carbon nanotubes.

Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey

NASA Astrophysics Data System (ADS)

Kobulnicky, Henry A.; Kiminki, Daniel C.; Lundquist, Michael J.; Burke, Jamison; Chapman, James; Keller, Erica; Lester, Kathryn; Rolen, Emily K.; Topel, Eric; Bhattacharjee, Anirban; Smullen, Rachel A.; Vargas Álvarez, Carlos A.; Runnoe, Jessie C.; Dale, Daniel A.; Brotherton, Michael M.

2014-08-01

We analyze orbital solutions for 48 massive multiple-star systems in the Cygnus OB2 association, 23 of which are newly presented here, to find that the observed distribution of orbital periods is approximately uniform in log P for P < 45 days, but it is not scale-free. Inflections in the cumulative distribution near 6 days, 14 days, and 45 days suggest key physical scales of sime0.2, sime0.4, and sime1 A.U. where yet-to-be-identified phenomena create distinct features. No single power law provides a statistically compelling prescription, but if features are ignored, a power law with exponent β ~= -0.22 provides a crude approximation over P = 1.4-2000 days, as does a piece-wise linear function with a break near 45 days. The cumulative period distribution flattens at P > 45 days, even after correction for completeness, indicating either a lower binary fraction or a shift toward low-mass companions. A high degree of similarity (91% likelihood) between the Cyg OB2 period distribution and that of other surveys suggests that the binary properties at P <~ 25 days are determined by local physics of disk/clump fragmentation and are relatively insensitive to environmental and evolutionary factors. Fully 30% of the unbiased parent sample is a binary with period P < 45 days. Completeness corrections imply a binary fraction near 55% for P < 5000 days. The observed distribution of mass ratios 0.2 < q < 1 is consistent with uniform, while the observed distribution of eccentricities 0.1 < e < 0.6 is consistent with uniform plus an excess of e ~= 0 systems. We identify six stars, all supergiants, that exhibit aperiodic velocity variations of ~30 km s-1 attributed to atmospheric fluctuations.

Rates of Charged Clocks in an Electric Field.

NASA Astrophysics Data System (ADS)

Ozer, Murat

2008-04-01

The gravitational arguments leading to time dilation, redshift, and spacetime curvature are adapted to electric fields. The energy levels of two identical positively charged atoms at different potentials in a static electric field are shown to undergo blueshift. Secondly, the period of a charged simple pendulum (clock) in the electric field of a metallic sphere is shown to vary with the electric potential. The spacetime diagram for the world lines of two photons emitted and absorbed by two pendulums at different potentials at different times and the world lines of the pendulums, as in Schild's argument, is shown to be not a parallelogram in Minkowski spacetime, concluding that spacetime must be curved. A Pound-Rebka-Snider experiment in an electric field is proposed to confirm that photons undergo a frequency shift in an electric field and hence the spacetime manifold is curved. Next, Torretti's gravitational argument that spacetime around a mass distribution concentrated at a point is curved is extended to electric charge distributions to conclude that the nonuniform electric fields of such charge distributions too curve spacetime. Finally, the local equivalence of a uniform electric field times the charge to mass ratio to a uniform acceleration is shown through spacetime transformations and the electrical redshift is obtained in a uniformly accelerated frame by using this principle. These arguments lead to the conclusion that special relativistic electromagnetism is an approximation to a general relativistic multi-metric theory.

Resistivity analysis of epitaxially grown, doped semiconductors using energy dependent secondary ion mass spectroscopy

NASA Astrophysics Data System (ADS)

Burnham, Shawn D.; Thomas, Edward W.; Doolittle, W. Alan

2006-12-01

A characterization technique is discussed that allows quantitative optimization of doping in epitaxially grown semiconductors. This technique uses relative changes in the host atom secondary ion (HASI) energy distribution from secondary ion mass spectroscopy (SIMS) to indicate relative changes in conductivity of the material. Since SIMS is a destructive process due to sputtering through a film, a depth profile of the energy distribution of sputtered HASIs in a matrix will contain information on the conductivity of the layers of the film as a function of depth. This process is demonstrated with Mg-doped GaN, with the Mg flux slowly increased through the film. Three distinct regions of conductivity were observed: one with Mg concentration high enough to cause compensation and thus high resistivity, a second with moderate Mg concentration and low resistivity, and a third with little to no Mg doping, causing high resistivity due to the lack of free carriers. During SIMS analysis of the first region, the energy distributions of sputtered Ga HASIs were fairly uniform and unchanging for a Mg flux above the saturation, or compensation, limit. For the second region, the Ga HASI energy distributions shifted and went through a region of inconsistent energy distributions for Mg flux slightly below the critical flux for saturation, or compensation. Finally, for the third region, the Ga HASI energy distributions then settled back into another fairly unchanging, uniform pattern. These three distinct regions were analyzed further through growth of Mg-doped step profiles and bulk growth of material at representative Mg fluxes. The materials grown at the two unchanging, uniform regions of the energy distributions yielded highly resistive material due to too high of Mg concentration and low to no Mg concentration, respectively. However, material grown in the transient energy distribution region with Mg concentration between that of the two highly resistive regions yielded low resistivity (0.59Ωcm) and highly p-type (1.2×1018cm-3 holes) Mg-doped GaN.

Analysis of flow field characteristics in IC equipment chamber based on orthogonal design

NASA Astrophysics Data System (ADS)

Liu, W. F.; Yang, Y. Y.; Wang, C. N.

2017-01-01

This paper aims to study the influence of the configuration of processing chamber as a part of IC equipment on flow field characteristics. Four parameters, including chamber height, chamber diameter, inlet mass flow rate and outlet area, are arranged using orthogonally design method to study their influence on flow distribution in the processing chamber with the commercial software-Fluent. The velocity, pressure and temperature distribution above the holder were analysed respectively. The velocity difference value of the gas flow above the holder is defined as the evaluation criteria to evaluate the uniformity of the gas flow. The quantitative relationship between key parameters and the uniformity of gas flow was found through analysis of experimental results. According to our study, the chamber height is the most significant factor, and then follows the outlet area, chamber diameter and inlet mass flow rate. This research can provide insights into the study and design of configuration of etcher, plasma enhanced chemical vapor deposition (PECVD) equipment, and other systems with similar configuration and processing condition.

Influence of Soret-Dufour and thermophoresis on hydromagnetic mixed convection heat and mass transfer over an inclined flat plate with non-uniform heat source/sink and chemical reaction

NASA Astrophysics Data System (ADS)

Pal, Dulal; Mondal, Hiranmoy

2018-03-01

The paper is devoted to the study of thermophoresis and Soret-Dufour effects on magnetohydrodynamic mixed convective heat and mass transfer over an inclined flat plate with non-uniform heat source/sink. Governing non-linear coupled ordinary differential equations are solved numerically using Runge-Kutta Fehlberg technique with shooting scheme. The effects of various physical parameters on the velocity, temperature, and concentration profiles are depicted graphically. The values of skin-friction coefficient, Nusselt number and Sherwood number are presented in a tabular form. It is found that increase in thermophoretic and chemical reaction parameters retard the velocity and concentration distributions in the boundary layer.

Evaluation of the degree of mixing of combinations of dry syrup, powder, and fine granule products in consideration of particle size distribution using near infrared spectrometry.

PubMed

Yamamoto, Yoshihisa; Suzuki, Toyofumi; Matsumoto, Mika; Ohtani, Michiteru; Hayano, Shuichi; Fukami, Toshiro; Tomono, Kazuo

2012-01-01

We used near infrared (NIR) spectroscopy to evaluate the degree of mixing of blended dry syrup (DS) products whose particle sizes are not specified in the Revised 16th Edition of the Japanese Pharmacopoeia, and also evaluated the degree of mixing when powder products or fine granule products were added to DS products. The data obtained were used to investigate the relationship between the particle size distributions of the products studied and the degree of mixing. We found that the particle size distribution characteristics of the 15 DS products studied can be broadly classified into 5 types. Combinations of frequently prescribed products were selected to represent 4 of the 5 particle size distribution types and were blended with a mortar and pestle. The coefficient of variation (CV) decreased as the percent mass of Asverin® Dry Syrup 2% (Asverin-DS) increased in blends of Periactin® Powder 1% (Periactin) and Asverin-DS, indicating an improved degree of mixing (uniformity). In contrast, in blends of Periactin and Mucodyne® DS 33.3%, mixing a combination at a 1:1 mass ratio 40 times resulted in a CV of 20%. Other mixing frequencies and mass ratios resulted in a CV by 50% to 70%, indicating a very poor degree of mixing (poor uniformity). These results suggest that when combining different DSs, or a DS with a powder or fine granule product, the blending obtained with a mortar and pestle improves as the particle size distributions of the components approach each other and as the ranges of the distributions narrow.

Effects of temperature segregation on the volumetric and mechanistic properties of asphalt mixtures : research project capsule.

DOT National Transportation Integrated Search

2015-02-01

Material segregation in asphalt mixtures is a non-uniform distribution of coarse : and fine aggregates through its masses, i.e., concentration of coarse materials : in some area and fine materials in others. During construction, the coarse and : fine...

Precise mass determination of single cell with cantilever-based microbiosensor system.

PubMed

Łabędź, Bogdan; Wańczyk, Aleksandra; Rajfur, Zenon

2017-01-01

Having determined the mass of a single cell of brewer yeast Saccharomyces cerevisiae by means of a microcantilever-based biosensor Cantisens CSR-801 (Concentris, Basel, Switzerland), it was found that its dry mass is 47,65 ± 1,05 pg. Found to be crucial in this mass determination was the cell position along the length of the cantilever. Moreover, calculations including cells positions on the cantilever provide a threefold better degree of accuracy than those which assume uniform mass distribution. We have also examined the influence of storage time on the single cell mass. Our results show that after 6 months there is an increase in the average mass of a single yeast cell.

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

Shi, J.; Xue, X.

A comprehensive 3D CFD model is developed for a bi-electrode supported cell (BSC) SOFC. The model includes complicated transport phenomena of mass/heat transfer, charge (electron and ion) migration, and electrochemical reaction. The uniqueness of the modeling study is that functionally graded porous electrode property is taken into account, including not only linear but nonlinear porosity distributions. Extensive numerical analysis is performed to elucidate the effects of both porous microstructure distributions and operating condition on cell performance. Results indicate that cell performance is strongly dependent on both operating conditions and porous microstructure distributions of electrodes. Using the proposed fuel/gas feeding design,more » the uniform hydrogen distribution within porous anode is achieved; the oxygen distribution within the cathode is dependent on porous microstructure distributions as well as pressure loss conditions. Simulation results show that fairly uniform temperature distribution can be obtained with the proposed fuel/gas feeding design. The modeling results can be employed to guide experimental design of BSC test and provide pre-experimental analysis, as a result, to circumvent high cost associated with try-and-error experimental design and setup.« less

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

Trianti, Nuri, E-mail: nuri.trianti@gmail.com; Nurjanah,; Su’ud, Zaki

Thermalhydraulic of reactor core is the thermal study on fluids within the core reactor, i.e. analysis of the thermal energy transfer process produced by fission reaction from fuel to the reactor coolant. This study include of coolant temperature and reactor power density distribution. The purposes of this analysis in the design of nuclear power plant are to calculate the coolant temperature distribution and the chimney height so natural circulation could be occurred. This study was used boiling water reactor (BWR) with cylinder type reactor core. Several reactor core properties such as linear power density, mass flow rate, coolant density andmore » inlet temperature has been took into account to obtain distribution of coolant density, flow rate and pressure drop. The results of calculation are as follows. Thermal hydraulic calculations provide the uniform pressure drop of 1.1 bar for each channels. The optimum mass flow rate to obtain the uniform pressure drop is 217g/s. Furthermore, from the calculation it could be known that outlet temperature is 288°C which is the saturated fluid’s temperature within the system. The optimum chimney height for natural circulation within the system is 14.88 m.« less

A quasi-molecular dynamics simulation study on the effect of particles collisions in pulsed-laser desorption

NASA Astrophysics Data System (ADS)

Xinyu-Tan; Duanming-Zhang; Shengqin-Feng; Li, Zhi-hua; Li, Guan; Li, Li; Dan, Liu

2006-05-01

The dynamics characteristic and effect of atoms and particulates ejected from the surface generated by nanosecond pulsed-laser ablation are very important. In this work, based on the consideration of the inelasticity and non-uniformity of the plasma particles thermally desorbed from a plane surface into vacuum induced by nanosecond laser ablation, the one-dimensional particles flow is studied on the basis of a quasi-molecular dynamics (QMD) simulation. It is assumed that atoms and particulates ejected from the surface of a target have a Maxwell velocity distribution corresponding to the surface temperature. Particles collisions in the ablation plume. The particles mass is continuous and satisfies fractal theory distribution. Meanwhile, the particles are inelastic. Our results show that inelasticity and non-uniformity strongly affect the dynamics behavior of the particles flow. Along with the decrease of restitution coefficient e and increase of fractional dimension D, velocity distributions of plasma particles system all deviate from the initial Gaussian distribution. The increasing of dissipation energy ΔE leads to density distribution clusterized and closed up to the center mass. Predictions of the particles action based on the proposed fractal and inelasticity model are found to be in agreement with the experimental observation. This verifies the validity of the present model for the dynamics behavior of pulsed-laser-induced particles flow.

How Spherical Is a Cube (Gravitationally)?

NASA Astrophysics Data System (ADS)

Sanny, Jeff; Smith, David

2015-02-01

An important concept that is presented in the discussion of Newton's law of universal gravitation is that the gravitational effect external to a spherically symmetric mass distribution is the same as if all of the mass of the distribution were concentrated at the center.1,2 By integrating over ring elements of a spherical shell, we show that the gravitational force on a point mass outside the shell is the same as that of a particle with the same mass as the shell at its center. This derivation works for objects with spherical symmetry while depending on the fact that the gravitational force between two point masses varies inversely as the square of their separation.3 If these conditions are not met, then the problem becomes more difficult. In this paper, we remove the condition of spherical symmetry and examine the gravitational force between two uniform cubes.

Parametric excitation of tire-wheel assemblies by a stiffness non-uniformity

NASA Astrophysics Data System (ADS)

Stutts, D. S.; Krousgrill, C. M.; Soedel, W.

1995-01-01

A simple model of the effect of a concentrated radial stiffness non-uniformity in a passenger car tire is presented. The model treats the tread band of the tire as a rigid ring supported on a viscoelastic foundation. The distributed radial stiffness is lumped into equivalent horizontal (fore-and-aft) and vertical stiffnesses. The concentrated radial stiffness non-uniformity is modeled by treating the tread band as fixed, and the stiffness non-uniformity as rotating around it at the nominal angular velocity of the wheel. Due to loading, the center of mass of the tread band ring model is displaced upward with respect to the wheel spindle and, therefore, the rotating stiffness non-uniformity is alternately compressed and stretched through one complete rotation. This stretching and compressing of the stiffness non-uniformity results in force transmission to the wheel spindle at twice the nominal angular velocity in frequency, and therefore, would excite a given resonance at one-half the nominal angular wheel velocity that a mass unbalance would. The forcing produced by the stiffness non-uniformity is parametric in nature, thus creating the possibility of parametric resonance. The basic theory of the parametric resonance is explained, and a parameter study using derived lumped parameters based on a typical passenger car tire is performed. This study revealed that parametric resonance in passenger car tires, although possible, is unlikely at normal highway speeds as predicted by this model unless the tire is partially deflated.

Manifold to uniformly distribute a solid-liquid slurry

DOEpatents

Kern, Kenneth C.

1983-01-01

This invention features a manifold that divides a stream of coal particles and liquid into several smaller streams maintaining equal or nearly equal mass compositions. The manifold consists of a horizontal, variable area header having sharp-edged, right-angled take-offs which are oriented on the bottom of the header.

Design, development and manufacture of a breadboard radio frequency mass gauging system

NASA Technical Reports Server (NTRS)

1975-01-01

The feasibility of the RF gauging mode, counting technique was demonstrated for gauging liquid hydrogen and liquid oxygen under all attitude conditions. With LH2, it was also demonstrated under dynamic fluid conditions, in which the fluid assumes ever changing positions within the tank, that the RF gauging technique on the average provides a very good indication of mass. It is significant that the distribution of the mode count data at each fill level during dynamic LH2 and LOX orientation testing does approach a statistical normal distribution. Multiple space-diversity probes provide better coupling to the resonant modes than utilization of a single probe element. The variable sweep rate generator technique provides a more uniform mode versus time distribution for processing.

Modeling and optimization of an enhanced battery thermal management system in electric vehicles

NASA Astrophysics Data System (ADS)

Li, Mao; Liu, Yuanzhi; Wang, Xiaobang; Zhang, Jie

2018-06-01

This paper models and optimizes an air-based battery thermal management system (BTMS) in a battery module with 36 battery lithium-ion cells. A design of experiments is performed to study the effects of three key parameters (i.e., mass flow rate of cooling air, heat flux from the battery cell to the cooling air, and passage spacing size) on the battery thermal performance. Three metrics are used to evaluate the BTMS thermal performance, including (i) the maximum temperature in the battery module, (ii) the temperature uniformity in the battery module, and (iii) the pressure drop. It is found that (i) increasing the total mass flow rate may result in a more non-uniform distribution of the passage mass flow rate among passages, and (ii) a large passage spacing size may worsen the temperature uniformity on the battery walls. Optimization is also performed to optimize the passage spacing size. Results show that the maximum temperature difference of the cooling air in passages is reduced from 23.9 to 2.1 K by 91.2%, and the maximum temperature difference among the battery cells is reduced from 25.7 to 6.4 K by 75.1%.

Operational performance of a low cost, air mass 2 solar simulator

NASA Technical Reports Server (NTRS)

Yass, K.; Curtis, H. B.

1975-01-01

Modifications and improvements on a low cost air mass 2 solar simulator are discussed. The performance characteristics of total irradiance, uniformity of irradiance, spectral distribution, and beam subtense angle are presented. The simulator consists of an array of tungsten halogen lamps hexagonally spaced in a plane. A corresponding array of plastic Fresnel lenses shapes the output beam such that the simulator irradiates a 1.2 m by 1.2 m area with uniform collimated irradiance. Details are given concerning individual lamp output measurements and placement of the lamps. Originally, only the direct component of solar irradiance was simulated. Since the diffuse component may affect the performance of some collectors, the capability to simulate it is being added. An approach to this diffuse addition is discussed.

Time-Fractional Advection-Dispersion Equation (tFADE) to Quantify Aqueous Phase Contaminant Elution from a Trichloroethene (TCE) NAPL Source Zone in Sand Columns

NASA Astrophysics Data System (ADS)

Tick, G. R.; Wei, S.; Sun, H.; Zhang, Y.

2016-12-01

Pore-scale heterogeneity, NAPL distribution, and sorption/desorption processes can significantly affect aqueous phase elution and mass flux in porous media systems. The application of a scale-independent fractional derivative model (tFADE) was used to simulate elution curves for a series of columns (5 cm, 7 cm, 15 cm, 25 cm, and 80 cm) homogeneously packed with 20/30-mesh sand and distributed with uniform saturations (7-24%) of NAPL phase trichloroethene (TCE). An additional set of columns (7 cm and 25 cm) were packed with a heterogeneous distribution of quartz sand upon which TCE was emplaced by imbibing the immiscible liquid, under stable displacement conditions, to simulate a spill-type process. The tFADE model was able to better represent experimental elution behavior for systems that exhibited extensive long-term concentration tailing requiring much less parameters compared to typical multi-rate mass transfer models (MRMT). However, the tFADE model was not able to effectively simulate the entire elution curve for such systems with short concentration tailing periods since it assumes a power-law distribution for the dissolution rate for TCE. Such limitations may be solved using the tempered fractional derivative model, which can capture the single-rate mass transfer process and therefore the short elution concentration tailing behavior. Numerical solution for the tempered fractional-derivative model in bounded domains however remains a challenge and therefore requires further study. However, the tFADE model shows excellent promise for understanding impacts on concentration elution behavior for systems in which physical heterogeneity, non-uniform NAPL distribution, and pronounced sorption-desorption effects dominate or are present.

Quantitative 3-D Elemental Mapping by LA-ICP-MS of a Basaltic Clast from the Hanford 300 Area, Washington, USA

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

Sheng, Peng; Hu, Qinhong; Ewing, Robert P.

2012-03-01

Laser ablation with inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure elemental concentrations at the 100 {micro}m scale in a 3-dimensional manner in a basalt sample collected from the Hanford 300 Area in south-central Washington State. A modified calibration method was developed to quantify the LA-ICP-MS signal response using a constant-sum mass fraction of eight major elements; the method produced reasonable concentration measurements for both major and trace elements when compared to a standard basalt sample with known concentrations. 3-dimensional maps (stacked 2-D contour layers, each measuring 2100 {micro}m x 2100 {micro}m) show relatively uniform concentration with depth formore » intrinsic elements such as Si, Na, and Sr. However, U and Cu accumulation were observed near the rock surface, consistent with the site's release history of these pollutants. U and Cu show substantial heterogeneity in their concentration distributions in horizontal slices, while the intrinsic elements are essentially uniformly distributed. From measured U concentrations of this work and reported mass fractions, cobbles and gravels were estimated to contain from 0.6% to 7.5% of the contaminant U, implicating the coarse fraction as a long-term release source.« less

Evaluation of the Community Multiscale Air Quality (CMAQ) ...

EPA Pesticide Factsheets

This work evaluates particle size-composition distributions simulated by the Community Multiscale Air Quality (CMAQ) model using Micro-Orifice Uniform Deposit Impactor (MOUDI) measurements at 18 sites across North America. Size-resolved measurements of particulate SO4+, with the model ranging from an underestimation to overestimation of both the peak diameter and peak particle concentration across the sites. Computing PM2.5 from the modeled size distribution parameters rather than by summing the masses in the Aitken and a

The particle size distribution, density, and specific surface area of welding fumes from SMAW and GMAW mild and stainless steel consumables.

PubMed

Hewett, P

1995-02-01

Particle size distributions were measured for fumes from mild steel (MS) and stainless steel (SS); shielded metal arc welding (SMAW) and gas metal arc welding (GMAW) consumables. Up to six samples of each type of fume were collected in a test chamber using a micro-orifice uniform deposit (cascade) impactor. Bulk samples were collected for bulk fume density and specific surface area analysis. Additional impactor samples were collected using polycarbonate substrates and analyzed for elemental content. The parameters of the underlying mass distributions were estimated using a nonlinear least squares analysis method that fits a smooth curve to the mass fraction distribution histograms of all samples for each type of fume. The mass distributions for all four consumables were unimodal and well described by a lognormal distribution; with the exception of the GMAW-MS and GMAW-SS comparison, they were statistically different. The estimated mass distribution geometric means for the SMAW-MS and SMAW-SS consumables were 0.59 and 0.46 micron aerodynamic equivalent diameter (AED), respectively, and 0.25 micron AED for both the GMAW-MS and GMAW-SS consumables. The bulk fume densities and specific surface areas were similar for the SMAW-MS and SMAW-SS consumables and for the GMAW-MS and GMAW-SS consumables, but differed between SMAW and GMAW. The distribution of metals was similar to the mass distributions. Particle size distributions and physical properties of the fumes were considerably different when categorized by welding method. Within each welding method there was little difference between MS and SS fumes.

Analytical solution for heat transfer in three-dimensional porous media including variable fluid properties

NASA Technical Reports Server (NTRS)

Siegel, R.; Goldstein, M. E.

1972-01-01

An analytical solution is obtained for flow and heat transfer in a three-dimensional porous medium. Coolant from a reservoir at constant pressure and temperature enters one portion of the boundary of the medium and exits through another portion of the boundary which is at a specified uniform temperature and uniform pressure. The variation with temperature of coolant density and viscosity are both taken into account. A general solution is found that provides the temperature distribution in the medium and the mass and heat fluxes along the portion of the surface through which the coolant is exiting.

Quantitative 3-D elemental mapping by LA-ICP-MS of a basaltic clast from the Hanford 300 Area, Washington, USA.

PubMed

Peng, Sheng; Hu, Qinhong; Ewing, Robert P; Liu, Chongxuan; Zachara, John M

2012-02-21

Laser ablation with inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure elemental concentrations at the 100-μm scale in a 3-dimensional manner within a basaltic clast sample collected from the Hanford 300 Area in south-central Washington State, United States. A calibration method was developed to quantify the LA-ICP-MS signal response using a constant-sum mass fraction of eight major elements; the method produced reasonable concentration measurements for both major and trace elements when compared to a standard basalt sample with known concentrations. 3-Dimensional maps (stacked 2-D contour layers, each representing 2100 μm × 2100 μm) show relatively uniform concentration with depth for intrinsic elements such as Si, Na, and Sr. However, U and Cu accumulation were observed near the sample surface, consistent with the site's release history of these contaminants. U and Cu show substantial heterogeneity in their concentration distributions within horizontal slices, while the intrinsic elements are essentially uniformly distributed. From these measured U concentrations and published grain size distributions, gravel and cobbles were estimated to contain about 1% of the contaminant U, implicating the coarse fraction as a long-term release source.

A fabrication strategy for nanosized zero valent iron (nZVI)-polymeric anion exchanger composites with tunable structure for nitrate reduction.

PubMed

Jiang, Zhenmao; Zhang, Shujuan; Pan, Bingcai; Wang, Wenfeng; Wang, Xiaoshu; Lv, Lu; Zhang, Weiming; Zhang, Quanxing

2012-09-30

To reveal how the distribution of nanoscale zero-valent iron (nZVI) affect their reduction efficiency of its polymer-based composites and to further develop a simple strategy to tune the structure of the composites, we prepared four nZVI-polymerstyrene anion exchanger composites with similar nZVI loadings (13.5-14.4 Fe % in mass) but different distributions just through varying the concentration of NaBH(4) (0.9, 1.8, 3.6, and 7.2% in mass) solution during reduction of nZVI precursor (FeCl(4)(-) anions). As observed by SEM-EDX images, increasing the NaBH(4) concentration resulted in a more uniform nZVI distribution within the polymer, and thereto higher NH(4)(+)N production, faster reaction rate and more gaseous products during its reduction of nitrate and nitrite. nZVI distribution of the composites was suggested to greatly depend upon two processes, the hydrolyzation of anionic FeCl(4)(-) into cationic Fe(3+) and the reduction of both Fe(III) species by NaBH(4). Higher NaBH(4) concentration favored its faster diffusion into the inside polymer and in situ reduction of Fe(III) species into nZVI, causing a more uniform nZVI distribution. The results reported herein suggest that adjusting the NaBH(4) concentration was a simple and effective method to control the nZVI distribution in the supporting polymers, and indirectly tune the reactivity of the resultant nZVI hybrids. Copyright © 2012 Elsevier B.V. All rights reserved.

Relativistic equation of state at subnuclear densities in the Thomas-Fermi approximation

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

Zhang, Z. W.; Shen, H., E-mail: shennankai@gmail.com

We study the non-uniform nuclear matter using the self-consistent Thomas-Fermi approximation with a relativistic mean-field model. The non-uniform matter is assumed to be composed of a lattice of heavy nuclei surrounded by dripped nucleons. At each temperature T, proton fraction Y{sub p} , and baryon mass density ρ {sub B}, we determine the thermodynamically favored state by minimizing the free energy with respect to the radius of the Wigner-Seitz cell, while the nucleon distribution in the cell can be determined self-consistently in the Thomas-Fermi approximation. A detailed comparison is made between the present results and previous calculations in the Thomas-Fermimore » approximation with a parameterized nucleon distribution that has been adopted in the widely used Shen equation of state.« less

Scaling, clustering and avalanches for steel beads in an external magnetic field

NASA Astrophysics Data System (ADS)

Marquinez, Alyse; Thvedt, Ingrid; Lehman, S. Y.; Jacobs, D. T.

2011-03-01

We investigated avalanches using uniform 3mm steel spheres (``beads'') dropped onto a conical bead pile within a uniform magnetic field. The bead pile is built by pouring beads onto a circular base where the bottom layer of beads had been glued randomly. Beads are then individually dropped from a fixed height after which the pile is massed. This process is repeated for thousands of bead drops. By measuring the number of avalanches of a given size that occurred during the experiment, the resulting avalanche size distribution was compared to a power law description as predicted by self-organized criticality. As the magnetic field intensity increased, the beads clustered to give a larger angle of repose and we measured the change in the avalanche size distribution. The moments of the distribution give a sensitive test of mean-field theory as the universality class for these bead piles. We acknowledge support from Research Corporation and NSF-REU grant DMR 0649112.

Effects of inlet distortion on gas turbine combustion chamber exit temperature profiles

NASA Astrophysics Data System (ADS)

Maqsood, Omar Shahzada

Damage to a nozzle guide vane or blade, caused by non-uniform temperature distributions at the combustion chamber exit, is deleterious to turbine performance and can lead to expensive and time consuming overhaul and repair. A test rig was designed and constructed for the Allison 250-C20B combustion chamber to investigate the effects of inlet air distortion on the combustion chamber's exit temperature fields. The rig made use of the engine's diffuser tubes, combustion case, combustion liner, and first stage nozzle guide vane shield. Rig operating conditions simulated engine cruise conditions, matching the quasi-non-dimensional Mach number, equivalence ratio and Sauter mean diameter. The combustion chamber was tested with an even distribution of inlet air and a 4% difference in airflow at either side. An even distribution of inlet air to the combustion chamber did not create a uniform temperature profile and varying the inlet distribution of air exacerbated the profile's non-uniformity. The design of the combustion liner promoted the formation of an oval-shaped toroidal vortex inside the chamber, creating localized hot and cool sections separated by 90° that appeared in the exhaust. Uneven inlet air distributions skewed the oval vortex, increasing the temperature of the hot section nearest the side with the most mass flow rate and decreasing the temperature of the hot section on the opposite side. Keywords: Allison 250, Combustion, Dual-Entry, Exit Temperature Profile, Gas Turbine, Pattern Factor, Reverse Flow.

Uniform Media Effects and Uniform Audience Responses.

ERIC Educational Resources Information Center

Perry, David K.

The idea that mass communication effects may decrease diversity among people or societies exposed to it arises constantly. However, discussions of mass media effects do not highlight differences between mass communications that "affect" people uniformly and messages that members of audiences "respond to" in similar ways. A…

Ensemble Forecasting of Coronal Mass Ejections Using the WSA-ENLIL with CONED Model

NASA Technical Reports Server (NTRS)

Emmons, D.; Acebal, A.; Pulkkinen, A.; Taktakishvili, A.; MacNeice, P.; Odstricil, D.

2013-01-01

The combination of the Wang-Sheeley-Arge (WSA) coronal model, ENLIL heliospherical model version 2.7, and CONED Model version 1.3 (WSA-ENLIL with CONED Model) was employed to form ensemble forecasts for 15 halo coronal mass ejections (halo CMEs). The input parameter distributions were formed from 100 sets of CME cone parameters derived from the CONED Model. The CONED Model used image processing along with the bootstrap approach to automatically calculate cone parameter distributions from SOHO/LASCO imagery based on techniques described by Pulkkinen et al. (2010). The input parameter distributions were used as input to WSA-ENLIL to calculate the temporal evolution of the CMEs, which were analyzed to determine the propagation times to the L1 Lagrangian point and the maximum Kp indices due to the impact of the CMEs on the Earth's magnetosphere. The Newell et al. (2007) Kp index formula was employed to calculate the maximum Kp indices based on the predicted solar wind parameters near Earth assuming two magnetic field orientations: a completely southward magnetic field and a uniformly distributed clock-angle in the Newell et al. (2007) Kp index formula. The forecasts for 5 of the 15 events had accuracy such that the actual propagation time was within the ensemble average plus or minus one standard deviation. Using the completely southward magnetic field assumption, 10 of the 15 events contained the actual maximum Kp index within the range of the ensemble forecast, compared to 9 of the 15 events when using a uniformly distributed clock angle.

Vibroacoustic Model Validation for a Curved Honeycomb Composite Panel

NASA Technical Reports Server (NTRS)

Buehrle, Ralph D.; Robinson, Jay H.; Grosveld, Ferdinand W.

2001-01-01

Finite element and boundary element models are developed to investigate the vibroacoustic response of a curved honeycomb composite sidewall panel. Results from vibroacoustic tests conducted in the NASA Langley Structural Acoustic Loads and Transmission facility are used to validate the numerical predictions. The sidewall panel is constructed from a flexible honeycomb core sandwiched between carbon fiber reinforced composite laminate face sheets. This type of construction is being used in the development of an all-composite aircraft fuselage. In contrast to conventional rib-stiffened aircraft fuselage structures, the composite panel has nominally uniform thickness resulting in a uniform distribution of mass and stiffness. Due to differences in the mass and stiffness distribution, the noise transmission mechanisms for the composite panel are expected to be substantially different from those of a conventional rib-stiffened structure. The development of accurate vibroacoustic models will aide in the understanding of the dominant noise transmission mechanisms and enable optimization studies to be performed that will determine the most beneficial noise control treatments. Finite element and boundary element models of the sidewall panel are described. Vibroacoustic response predictions are presented for forced vibration input and the results are compared with experimental data.

Determining irrigation distribution uniformity and efficiency for nurseries

Treesearch

R. Thomas Fernandez

2010-01-01

A simple method for testing the distribution uniformity of overhead irrigation systems is described. The procedure is described step-by-step along with an example. Other uses of distribution uniformity testing are presented, as well as common situations that affect distribution uniformity and how to alleviate them.

The dynamics of spin stabilized spacecraft with movable appendages, part 1

NASA Technical Reports Server (NTRS)

Bainum, P. M.; Sellappan, R.

1975-01-01

The motion and stability of spin stabilized spacecraft with movable external appendages are treated both analytically and numerically. The two basic types of appendages considered are: (1) a telescoping type of varying length and (2) a hinged type of fixed length whose orientation with respect to the main part of the spacecraft can vary. Two classes of telescoping appendages are considered: (a) where an end mass is mounted at the end of an (assumed) massless boom; and (b) where the appendage is assumed to consist of a uniformly distributed homogeneous mass throughout its length. For the telescoping system Eulerian equations of motion are developed. During all deployment sequences it is assumed that the transverse component of angular momentum is much smaller than the component along the major spin axis. Closed form analytical solutions for the time response of the transverse components of angular velocities are obtained when the spacecraft hub has a nearly spherical mass distribution.

Investigation of thickness uniformity of thin metal films by using α-particle energy loss method and successive scanning measurements

NASA Astrophysics Data System (ADS)

Li, Gang; Xu, Jiayun; Bai, Lixin

2017-03-01

The metal films are widely used in the Inertial Confinement Fusion (ICF) experiments to obtain the radiation opacity, and the accuracy of the measuring results mainly depends on the accuracy of the film thickness and thickness uniformity. The traditional used measuring methods all have various disadvantages, the optical method and stylus method cannot provide mass thickness which reflects the internal density distribution of the films, and the weighing method cannot provide the uniformity of the thickness distribution. This paper describes a new method which combines the α-particle energy loss (AEL) method and the successive scanning measurements to obtain the film thickness and thickness uniformity. The measuring system was partly installed in the vacuum chamber, and the relationship of chamber pressure and energy loss caused by the residual air in the vacuum chamber was studied for the source-to-detector distance ranging from 1 to 5 cm. The results show that the chamber pressure should be less than 10 Pa for the present measuring system. In the process of measurement, the energy spectrum of α-particles transmitted through each different measuring point were obtained, and then recorded automatically by a self-developed multi-channel analysis software. At the same time, the central channel numbers of the spectrum (CH) were also saved in a text form document. In order to realize the automation of data processing and represent the thickness uniformity visually in a graphic 3D plot, a software package was developed to convert the CH values into film thickness and thickness uniformity. The results obtained in this paper make the film thickness uniformity measurements more accurate and efficient in the ICF experiments.

Apparent negative mass in QCM sensors due to punctual rigid loading

NASA Astrophysics Data System (ADS)

Castro, P.; Resa, P.; Elvira, L.

2012-12-01

Quartz Crystal Microbalances (QCM) are highly sensitive piezoelectric sensors able to detect very small loads attached to them. These devices are widely employed in many applications including process control and industrial and environmental monitoring. Mass loading is usually related to frequency shift by the well-known Sauerbrey's equation, valid for thin rigid homogeneous films. However, a significant deviation from this equation can occur when the mass is not uniformly distributed over the surface. Whereas the effects of a thin film on a QCM have been thoroughly studied, there are relatively few results on punctual loads, even though particles are usually deposited randomly and non-uniformly on the resonator surface. In this work, we have studied the effect of punctual rigid loading on the resonant frequency shift of a QCM sensor, both experimentally and using finite element method (FEM). The FEM numerical analysis was done using COMSOL software, 3D modeling a linear elastic piezoelectric solid and introducing the properties of an AT-cut quartz crystal. It is shown that a punctual rigid mass deposition on the surface of a QCM sensor can lead to positive shifts of resonance frequency, contrary to Sauerbrey's equation.

Reproducible direct exposure environmental testing of metal-based magnetic media

NASA Technical Reports Server (NTRS)

Sides, Paul J.

1994-01-01

A flow geometry and flow rate for mixed flowing gas testing is proposed. Use of an impinging jet of humid polluted air can provide a uniform and reproducible exposure of coupons of metal-based magnetic media. Numerical analysis of the fluid flow and mass transfer in such as system has shown that samples confined within a distance equal to the nozzle radius on the surface of impingement are uniformly accessible to pollutants in the impinging gas phase. The critical factor is the nozzle height above the surface of impingement. In particular, the uniformity of exposure is less than plus/minus 2% for a volumetric flow rate of 1600 cm(exp 3)/minute total flow with the following specifications: For a one inch nozzle, the height of the nozzle opening above the stage should be 0.177 inches; for a 2 inch nozzle - 0.390 inches. Not only is the distribution uniform, but one can calculate the maximum delivery rate of pollutants to the samples for comparison with the observed deterioration.

Research of the rotation effect upon the hydrodynamics and heat and mass transport in a chemical reactor

NASA Astrophysics Data System (ADS)

Gicheva, Natalia I.

2017-11-01

The subject of this research is a chemical reactor for producing tungsten. A physical and mathematical model of fluid motion and heat and mass transfer in a vortex chamber of the chemical reactor under forced and free convection has been described and simulated using two methods. The numerical simulation was carried out in «vortex - stream functions and «velocity - pressure» variables. The velocity field, the mass and the temperature distributions in the reactor were obtained. The influence of a rotation effect upon the hydrodynamics and heat and mass transport was showed. The rotation is important for more uniform distribution of temperature and matter in the vortex chamber. Parametric studies on effects of the Reynolds, Prandtl and Rossbi criteria on the flow characteristics were also performed. Reliability of the calculations was verified by comparing the results obtained by the methods mentioned above. Also, the created model was applied for numerically solving of the classical test problem of the velocity distribution in an annular channel and that of a rotating infinite disk in a stationary liquid. The study findings showed a good agreement with the exact solutions.

Linear Instability Analysis of non-uniform Bubbly Mixing layer with Two-Fluid model

NASA Astrophysics Data System (ADS)

Sharma, Subash; Chetty, Krishna; Lopez de Bertodano, Martin

We examine the inviscid instability of a non-uniform adiabatic bubbly shear layer with a Two-Fluid model. The Two-Fluid model is made well-posed with the closure relations for interfacial forces. First, a characteristic analysis is carried out to study the well posedness of the model over range of void fraction with interfacial forces for virtual mass, interfacial drag, interfacial pressure. A dispersion analysis then allow us to obtain growth rate and wavelength. Then, the well-posed two-fluid model is solved using CFD to validate the results obtained with the linear stability analysis. The effect of the void fraction and the distribution profile on stability is analyzed.

Accumulation rate and mixing of shelf sediments in the Monterey Bay National Marine Sanctuary

USGS Publications Warehouse

Lewis, R.C.; Coale, K.H.; Edwards, B.D.; Marot, M.; Douglas, J.N.; Burton, E.J.

2002-01-01

The distribution of excess 210Pb in 31 sediment cores was used to determine modern (last 100 yr) mass accumulation rates and the depth of sediment mixing on the continental shelf between Pacifica and Monterey, California, USA. Apparent mass accumulation rates average 0.27 g cm-2 yr-1 and range from 0.42 g cm-2 yr-1 to 0.12 g cm-2 yr-1. Accumulation rates were highest at mid-shelf water depths (60-100 m) adjacent to major rivers and near the head of the Ascension submarine canyon. Cores from water depths of less than 65 m had low, uniform 210Pb activity profiles and sandy textures. The uppermost 5-13 cm of 15 cores had uniform 210Pb activity profiles above a region of steadily decreasing 210Pb activity. This phenomenon was attributed to sediment mixing. The thickness of this upper layer of uniform 210Pb activity decreased southward from 13 cm, west of Pacifica, to less than 5 cm, near Monterey Canyon. This southward decrease may be attributed to shallower bioturbation in the southern study area. Integrated excess 210Pb activities were generally higher where sedimentation rates were high. They were also higher with increasing distance from major rivers. Thus, sedimentation rate alone does not explain the distribution of integrated excess 210Pb in this study area. Excess 210Pb in the seafloor is controlled by other factors such as sediment texture, the atmospheric deposition rate of 210Pb, and the residence time of sediment particles in the water column. ?? 2002 Elsevier Science B.V. All rights reserved.

Microtomographic studies of subdivision of modified-release tablets.

PubMed

Wilczyński, Sławomir; Koprowski, Robert; Duda, Piotr; Banyś, Anna; Błońska-Fajfrowska, Barbara

2016-09-25

The uniformity of dosage units within a certain batch is ensured when each unit contains the active pharmaceutical ingredient (API) within a narrow range around the label claim. For tablets containing a score-line authorised for dose reductions, the European Pharmacopoeia (Ph. Eur.) considers that the uniformity of the tablet parts may be based on weight measurements regardless of the tablet type (immediate or modified release). This is because it is up to the regulatory authorities first to assess whether the tablet may contain a score-line for such use. X-ray microtomography was applied to assess the symmetry of 36 modified release tablets, containing 300mg of theophylline. The sum of the volume and surface area of the pellets in the subdivided tablets were compared. Simulations were carried out to identify the optimal amount of pellets in the tablet mass. The maximum difference in the API content between two subdivided halves was 165.18mg vs 133.83mg. If the amount of pellets in the tablet mass would drop below 13% on the basis of the pellet surface area, then the Ph. Eur. requirements would be exceeded. The amount of pellets in the tablet halves resulting in the greatest variability in API content was 38%. The results of this study indicate that the pellets were not distributed uniformly in the tablet mass. Thus, the uniformity of the dose in both halves of a tablet containing pellets cannot be based on the weight measurements i.e. it is necessary to develop further standards for tablet subdivision. Microtomographic methods are a very interesting alternative to expensive and time-consuming pharmacokinetic studies. Copyright © 2016 Elsevier B.V. All rights reserved.

Plane hydroelastic beam vibrations due to uniformly moving one axle vehicle

NASA Astrophysics Data System (ADS)

Fleischer, D.; Park, S.-K.

2004-06-01

The hydroelastic vibrations of a beam with rectangular cross-section is analyzed under the effect of an uniformly moving single axle vehicle using modal analysis and two-dimensional potential flow theory of the fluid neglecting the effect of surface waves aside the beam. For the special case of homogeneous beam resting on the surface of a water filled prismatic basin, the normal modes are determined considering surface waves in beam direction under the condition of compensating the volume of the enclosed fluid. The way to determine the vertical acceleration of the single axle vehicle is shown, which governs the response of the system. As analysis results the course of wheel load, the surface waves along the beam and the flow velocity distribution of the fluid is demonstrated for a continuous floating bridge under the passage of a rolling mass moving with uniform speed.

Behavior of dusty real gas on adiabatic propagation of cylindrical imploding strong shock waves

NASA Astrophysics Data System (ADS)

Gangwar, P. K.

2018-05-01

In this paper, CCW method has been used to study the behavior of dusty real gas on adiabatic propagation of cylindrical imploding strong shock waves. The strength of overtaking waves is estimated under the assumption that both C+ and C- disturbances propagate in non-uniform region of same density distribution. It is assumed that the dusty gas is the mixture of a real gas and a large number of small spherical solid particles of uniform size. The solid particles are uniformly distributed in the medium. Maintaining equilibrium flow conditions, the expressions for shock strength has been derived both for freely propagation as well as under the effect of overtaking disturbances. The variation of all flow variables with propagation distance, mass concentration of solid particles in the mixture and the ratio of solid particles to the initial density of gas have been computed and discussed through graphs. It is found that the presence of dust particles in the gases medium has significant effects on the variation of flow variables and the shock is strengthened under the influence of overtaking disturbances. The results accomplished here been compared with those for ideal gas.

Uncertainty estimates of a GRACE inversion modelling technique over Greenland using a simulation

NASA Astrophysics Data System (ADS)

Bonin, Jennifer; Chambers, Don

2013-07-01

The low spatial resolution of GRACE causes leakage, where signals in one location spread out into nearby regions. Because of this leakage, using simple techniques such as basin averages may result in an incorrect estimate of the true mass change in a region. A fairly simple least squares inversion technique can be used to more specifically localize mass changes into a pre-determined set of basins of uniform internal mass distribution. However, the accuracy of these higher resolution basin mass amplitudes has not been determined, nor is it known how the distribution of the chosen basins affects the results. We use a simple `truth' model over Greenland as an example case, to estimate the uncertainties of this inversion method and expose those design parameters which may result in an incorrect high-resolution mass distribution. We determine that an appropriate level of smoothing (300-400 km) and process noise (0.30 cm2 of water) gets the best results. The trends of the Greenland internal basins and Iceland can be reasonably estimated with this method, with average systematic errors of 3.5 cm yr-1 per basin. The largest mass losses found from GRACE RL04 occur in the coastal northwest (-19.9 and -33.0 cm yr-1) and southeast (-24.2 and -27.9 cm yr-1), with small mass gains (+1.4 to +7.7 cm yr-1) found across the northern interior. Acceleration of mass change is measurable at the 95 per cent confidence level in four northwestern basins, but not elsewhere in Greenland. Due to an insufficiently detailed distribution of basins across internal Canada, the trend estimates of Baffin and Ellesmere Islands are expected to be incorrect due to systematic errors caused by the inversion technique.

The panchromatic Hubble Andromeda Treasury. V. Ages and masses of the year 1 stellar clusters

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

Fouesneau, Morgan; Johnson, L. Clifton; Weisz, Daniel R.

We present ages and masses for 601 star clusters in M31 from the analysis of the six filter integrated light measurements from near-ultraviolet to near-infrared wavelengths, made as part of the Panchromatic Hubble Andromeda Treasury (PHAT). We derive the ages and masses using a probabilistic technique, which accounts for the effects of stochastic sampling of the stellar initial mass function. Tests on synthetic data show that this method, in conjunction with the exquisite sensitivity of the PHAT observations and their broad wavelength baseline, provides robust age and mass recovery for clusters ranging from ∼10{sup 2} to 2 × 10{sup 6}more » M {sub ☉}. We find that the cluster age distribution is consistent with being uniform over the past 100 Myr, which suggests a weak effect of cluster disruption within M31. The age distribution of older (>100 Myr) clusters falls toward old ages, consistent with a power-law decline of index –1, likely from a combination of fading and disruption of the clusters. We find that the mass distribution of the whole sample can be well described by a single power law with a spectral index of –1.9 ± 0.1 over the range of 10{sup 3}-3 × 10{sup 5} M {sub ☉}. However, if we subdivide the sample by galactocentric radius, we find that the age distributions remain unchanged. However, the mass spectral index varies significantly, showing best-fit values between –2.2 and –1.8, with the shallower slope in the highest star formation intensity regions. We explore the robustness of our study to potential systematics and conclude that the cluster mass function may vary with respect to environment.« less

Effect of high negative incidence on the performance of a centrifugal compressor stage with conventional vaned diffusers

NASA Astrophysics Data System (ADS)

Jaatinen, Ahti; Grönman, Aki; Turunen-Saaresti, Teemu; Backman, Jari

2011-06-01

Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotational speeds, and flow angles before and after the diffuser are measured at the design rotational speed and with three mass flow rates. The results are compared to corresponding results of the original vaneless diffuser design. Attention is paid to the performance at lower mass flows than the design mass flow. The results show that it is possible to improve the performance at mass flows lower than the design mass flow with a vaned diffuser designed with high negative incidence. However, with the vaned diffusers, the compressor still stalls at higher mass flow rates than with the vaneless one. The flow angle distributions after the diffuser are more uniform with the vaned diffusers.

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

Le, Hai P.; Cambier, Jean -Luc

Here, we present a numerical model and a set of conservative algorithms for Non-Maxwellian plasma kinetics with inelastic collisions. These algorithms self-consistently solve for the time evolution of an isotropic electron energy distribution function interacting with an atomic state distribution function of an arbitrary number of levels through collisional excitation, deexcitation, as well as ionization and recombination. Electron-electron collisions, responsible for thermalization of the electron distribution, are also included in the model. The proposed algorithms guarantee mass/charge and energy conservation in a single step, and is applied to the case of non-uniform gridding of the energy axis in the phasemore » space of the electron distribution function. Numerical test cases are shown to demonstrate the accuracy of the method and its conservation properties.« less

Maskless deposition technique for the physical vapor deposition of thin film and multilayer coatings with subnanometer precision and accuracy

DOEpatents

Vernon, Stephen P.; Ceglio, Natale M.

2000-01-01

The invention is a method for the production of axially symmetric, graded and ungraded thickness thin film and multilayer coatings that avoids the use of apertures or masks to tailor the deposition profile. A motional averaging scheme permits the deposition of uniform thickness coatings independent of the substrate radius. Coating uniformity results from an exact cancellation of substrate radius dependent terms, which occurs when the substrate moves at constant velocity. If the substrate is allowed to accelerate over the source, arbitrary coating profiles can be generated through appropriate selection and control of the substrate center of mass equation of motion. The radial symmetry of the coating profile is an artifact produced by orbiting the substrate about its center of mass; other distributions are obtained by selecting another rotation axis. Consequently there is a direct mapping between the coating thickness and substrate equation of motion which can be used to tailor the coating profile without the use of masks and apertures.

Development of a methodology to evaluate material accountability in pyroprocess

NASA Astrophysics Data System (ADS)

Woo, Seungmin

This study investigates the effect of the non-uniform nuclide composition in spent fuel on material accountancy in the pyroprocess. High-fidelity depletion simulations are performed using the Monte Carlo code SERPENT in order to determine nuclide composition as a function of axial and radial position within fuel rods and assemblies, and burnup. For improved accuracy, the simulations use short burnups step (25 days or less), Xe-equilibrium treatment (to avoid oscillations over burnup steps), axial moderator temperature distribution, and 30 axial meshes. Analytical solutions of the simplified depletion equations are built to understand the axial non-uniformity of nuclide composition in spent fuel. The cosine shape of axial neutron flux distribution dominates the axial non-uniformity of the nuclide composition. Combined cross sections and time also generate axial non-uniformity, as the exponential term in the analytical solution consists of the neutron flux, cross section and time. The axial concentration distribution for a nuclide having the small cross section gets steeper than that for another nuclide having the great cross section because the axial flux is weighted by the cross section in the exponential term in the analytical solution. Similarly, the non-uniformity becomes flatter as increasing burnup, because the time term in the exponential increases. Based on the developed numerical recipes and decoupling of the results between the axial distributions and the predetermined representative radial distributions by matching the axial height, the axial and radial composition distributions for representative spent nuclear fuel assemblies, the Type-0, -1, and -2 assemblies after 1, 2, and 3 depletion cycles, is obtained. These data are appropriately modified to depict processing for materials in the head-end process of pyroprocess that is chopping, voloxidation and granulation. The expectation and standard deviation of the Pu-to-244Cm-ratio by the single granule sampling calculated by the central limit theorem and the Geary-Hinkley transformation. Then, the uncertainty propagation through the key-pyroprocess is conducted to analyze the Material Unaccounted For (MUF), which is a random variable defined as a receipt minus a shipment of a process, in the system. The random variable, LOPu, is defined for evaluating the non-detection probability at each Key Measurement Point (KMP) as the original Pu mass minus the Pu mass after a missing scenario. A number of assemblies for the LOPu to be 8 kg is considered in this calculation. The probability of detection for the 8 kg LOPu is evaluated with respect the size of granule and powder using the event tree analysis and the hypothesis testing method. We can observe there are possible cases showing the probability of detection for the 8 kg LOPu less than 95%. In order to enhance the detection rate, a new Material Balance Area (MBA) model is defined for the key-pyroprocess. The probabilities of detection for all spent fuel types based on the new MBA model are greater than 99%. Furthermore, it is observed that the probability of detection significantly increases by increasing granule sample sizes to evaluate the Pu-to-244Cm-ratio before the key-pyroprocess. Based on these observations, even though the Pu material accountability in pyroprocess is affected by the non-uniformity of nuclide composition when the Pu-to-244Cm-ratio method is being applied, that is surmounted by decreasing the uncertainty of measured ratio by increasing sample sizes and modifying the MBAs and KMPs. (Abstract shortened by ProQuest.).

Modelling of convective processes during the Bridgman growth of poly-silicon

NASA Astrophysics Data System (ADS)

Popov, V. N.

2009-09-01

An original 3D model was used to numerically examine convective heat-and-mass transfer processes in the melt during the growth of polycrystalline silicon in vertical Bridgman configuration. The flow in the liquid was modelled using the Navier — Stokes equations in the Boussinesq approximation. The distribution of dissolved impurities was determined by solving the convective diffusion equation. The effects due to non-uniform heating of the lateral wall of the vessel and due to the shape of the crystallization front on the structure of melt flows and on the distribution of dissolved impurities in the liquid are examined.

The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies

NASA Astrophysics Data System (ADS)

Kirby, Evan N.; Cohen, Judith G.; Guhathakurta, Puragra; Cheng, Lucy; Bullock, James S.; Gallazzi, Anna

2013-12-01

We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z_* \\propto M_*^{0.30+/- 0.02}. The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M * = 1012 M ⊙. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

Free vibration of fully functionally graded carbon nanotube reinforced graphite/epoxy laminates

NASA Astrophysics Data System (ADS)

Kuo, Shih-Yao

2018-03-01

This study provides the first-known vibration analysis of fully functionally graded carbon nanotube reinforced hybrid composite (FFG-CNTRHC) laminates. CNTs are non-uniformly distributed to reinforce the graphite/epoxy laminates. Some CNT distribution functions in the plane and thickness directions are proposed to more efficiently increase the stiffening effect. The rule of mixtures is modified by considering the non-homogeneous material properties of FFG-CNTRHC laminates. The formulation of the location dependent stiffness matrix and mass matrix is derived. The effects of CNT volume fraction and distribution on the natural frequencies of FFG-CNTRHC laminates are discussed. The results reveal that the FFG layout may significantly increase the natural frequencies of FFG-CNTRHC laminate.

Results on angular distributions of thermal dileptons in nuclear collisions

NASA Astrophysics Data System (ADS)

Usai, Gianluca; NA60 Collaboration

2009-11-01

The NA60 experiment at the CERN SPS has studied dimuon production in 158 AGeV In-In collisions. The strong pair excess above the known sources found in the mass region 0.2

First Results on Angular Distributions of Thermal Dileptons in Nuclear Collisions

NASA Astrophysics Data System (ADS)

Arnaldi, R.; Banicz, K.; Castor, J.; Chaurand, B.; Cicalò, C.; Colla, A.; Cortese, P.; Damjanovic, S.; David, A.; de Falco, A.; Devaux, A.; Ducroux, L.; En'Yo, H.; Fargeix, J.; Ferretti, A.; Floris, M.; Förster, A.; Force, P.; Guettet, N.; Guichard, A.; Gulkanian, H.; Heuser, J. M.; Keil, M.; Kluberg, L.; Lourenço, C.; Lozano, J.; Manso, F.; Martins, P.; Masoni, A.; Neves, A.; Ohnishi, H.; Oppedisano, C.; Parracho, P.; Pillot, P.; Poghosyan, T.; Puddu, G.; Radermacher, E.; Ramalhete, P.; Rosinsky, P.; Scomparin, E.; Seixas, J.; Serci, S.; Shahoyan, R.; Sonderegger, P.; Specht, H. J.; Tieulent, R.; Usai, G.; Veenhof, R.; Wöhri, H. K.

2009-06-01

The NA60 experiment at the CERN Super Proton Synchrotron has studied dimuon production in 158AGeV In-In collisions. The strong excess of pairs above the known sources found in the complete mass region 0.2

Off-normal deposition of PTFE thin films during 157-nm irradiation

NASA Astrophysics Data System (ADS)

George, Sharon R.; Langford, Stephen C.; Dickinson, J. Thomas

2010-03-01

Polytetrafluoroethylene (PTFE) is valued for its chemical stability, low surface energy, and insulating properties. The ablation of PTFE by F2 excimer lasers (157 nm photons) involves photochemical scission of C-C bonds along the polymer chain. Depending on the fluence, the fragment masses can range from 50 to 2000 amu. Gaussian beam profiles allow for the production of spatially non-uniform distributions of fragment masses, with the lighter fragments concentrated in the center of the laser spot. The resulting trajectories for the light fragments can be strongly forward directed, while the heavy fragments are directed more to the side, well away from the surface normal. We present experimental evidence for these angular distributions, and numerically simulate this behavior with a simple, two-component hydrodynamic model. Under the conditions of our work, most of the ablated mass appears as heavier fragments and can be collected on substrates mounted to the sides or above and below the laser spot. This geometry may have advantages in some applications of pulsed laser deposition.

Preliminary weight and costs of sandwich panels to distribute concentrated loads

NASA Technical Reports Server (NTRS)

Belleman, G.; Mccarty, J. E.

1976-01-01

Minimum mass honeycomb sandwich panels were sized for transmitting a concentrated load to a uniform reaction through various distances. The form skin gages were fully stressed with a finite element computer code. The panel general stability was evaluated with a buckling computer code labeled STAGS-B. Two skin materials were considered; aluminum and graphite-epoxy. The core was constant thickness aluminum honeycomb. Various panel sizes and load levels were considered. The computer generated data were generalized to allow preliminary least mass panel designs for a wide range of panel sizes and load intensities. An assessment of panel fabrication cost was also conducted. Various comparisons between panel mass, panel size, panel loading, and panel cost are presented in both tabular and graphical form.

The mass distribution of clumps within infrared dark clouds. A Large APEX Bolometer Camera study

NASA Astrophysics Data System (ADS)

Gómez, L.; Wyrowski, F.; Schuller, F.; Menten, K. M.; Ballesteros-Paredes, J.

2014-01-01

Aims: We present an analysis of the dust continuum emission at 870 μm in order to investigate the mass distribution of clumps within infrared dark clouds (IRDCs). Methods: We map six IRDCs with the Large APEX BOlometer CAmera (LABOCA) at APEX, reaching an rms noise level of σrms = 28-44 mJy beam-1. The dust continuum emission coming from these IRDCs was decomposed by using two automated algorithms, Gaussclumps and Clumpfind. Moreover, we carried out single-pointing observations of the N2H+ (3-2) line toward selected positions to obtain kinematic information. Results: The mapped IRDCs are located in the range of kinematic distances of 2.7-3.2 kpc. We identify 510 and 352 sources with Gaussclumps and Clumpfind, respectively, and estimate masses and other physical properties assuming a uniform dust temperature. The mass ranges are 6-2692 M⊙ (Gaussclumps) and 7-4254 M⊙ (Clumpfind), and the ranges in effective radius are ~0.10-0.74 pc (Gaussclumps) and 0.16-0.99 pc (Clumpfind). The mass distribution, independent of the decomposition method used, is fitted by a power law, dN/dM ∝ Mα, with an index (α) of -1.60 ± 0.06, consistent with the CO mass distribution and other high-mass star-forming regions. Based on data acquired with the Atacama Pathfinder Experiment (APEX). APEX is a collaboration between the Max-Planck-Institut für Radioastronomie, the European Southern Observatory, and the Onsala Space Observatory.Full Tables 3 and 4 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/561/A148

Impact of uniform electrode current distribution on ETF. [Engineering Test Facility MHD generator

NASA Technical Reports Server (NTRS)

Bents, D. J.

1982-01-01

A basic reason for the complexity and sheer volume of electrode consolidation hardware in the MHD ETF Powertrain system is the channel electrode current distribution, which is non-uniform. If the channel design is altered to provide uniform electrode current distribution, the amount of hardware required decreases considerably, but at the possible expense of degraded channel performance. This paper explains the design impacts on the ETF electrode consolidation network associated with uniform channel electrode current distribution, and presents the alternate consolidation designs which occur. They are compared to the baseline (non-uniform current) design with respect to performance, and hardware requirements. A rational basis is presented for comparing the requirements for the different designs and the savings that result from uniform current distribution. Performance and cost impacts upon the combined cycle plant are discussed.

Dynamics of volcanic ash remobilisation by wind through the Patagonian steppe after the eruption of Cordón Caulle, 2011

PubMed Central

Panebianco, Juan E.; Mendez, Mariano J.; Buschiazzo, Daniel E.; Bran, Donaldo; Gaitán, Juan J.

2017-01-01

Wind erosion of freshly-deposited volcanic ash causes persistent storms, strongly affecting ecosystems and human activity. Wind erosion of the volcanic ash was measured up to 17 months after the ash deposition, at 7 sites located within the ash-deposition area. The mass flux was measured up to 1.5 m above ground level. Mass transport rates were over 125 times the soil wind-erosion rates observed before the ash deposition, reaching up to 6.3 kg m−1 day−1. Total mass transport of ash during the 17 months ranged between 113.6 and 969.9 kg m−1 depending on topographic location and wind exposure. The vertical distribution of the mass flux at sites with higher vegetation cover was generally inverted as compared to sites with lower vegetation cover. This situation lasted 7 months and then a shift towards a more uniform vertical distribution was observed, in coincidence with the beginning of the decline of the mass transport rates. Decay rates differed between sites. Despite changes over time, an inverse linear correlation between the mass transports and the mass-flux gradients was found. Both the mass-flux gradients and the average mass-transport rates were not linked with shear-stress partition parameters, but with the ratio: ash-fall thickness to total vegetation cover. PMID:28349929

Dynamics of volcanic ash remobilisation by wind through the Patagonian steppe after the eruption of Cordón Caulle, 2011.

PubMed

Panebianco, Juan E; Mendez, Mariano J; Buschiazzo, Daniel E; Bran, Donaldo; Gaitán, Juan J

2017-03-28

Wind erosion of freshly-deposited volcanic ash causes persistent storms, strongly affecting ecosystems and human activity. Wind erosion of the volcanic ash was measured up to 17 months after the ash deposition, at 7 sites located within the ash-deposition area. The mass flux was measured up to 1.5 m above ground level. Mass transport rates were over 125 times the soil wind-erosion rates observed before the ash deposition, reaching up to 6.3 kg m -1 day -1 . Total mass transport of ash during the 17 months ranged between 113.6 and 969.9 kg m -1 depending on topographic location and wind exposure. The vertical distribution of the mass flux at sites with higher vegetation cover was generally inverted as compared to sites with lower vegetation cover. This situation lasted 7 months and then a shift towards a more uniform vertical distribution was observed, in coincidence with the beginning of the decline of the mass transport rates. Decay rates differed between sites. Despite changes over time, an inverse linear correlation between the mass transports and the mass-flux gradients was found. Both the mass-flux gradients and the average mass-transport rates were not linked with shear-stress partition parameters, but with the ratio: ash-fall thickness to total vegetation cover.

In-plane vibration of FG micro/nano-mass sensor based on nonlocal theory under various thermal loading via differential transformation method

NASA Astrophysics Data System (ADS)

Rahmani, O.; Mohammadi Niaei, A.; Hosseini, S. A. H.; Shojaei, M.

2017-01-01

In the present study, free vibration model of a cantilever functionally graded (FG) nanobeam with an attached mass at tip and under various thermal loading and two types of material distribution is introduced. The vibration performance is considered using nonlocal Euler-Bernoulli beam theory. Two types of thermal loading, namely, uniform and nonlinear temperature rises through the thickness direction are considered. Thermo-mechanical properties of FG nano mass sensor are supposed to vary smoothly and continuously throughout the thickness based on power-law and Mori Tanaka distributions of material properties. Eringen non-local elasticity theory is exploited to describe the size dependency of FG nanobeam. The governing equations of the system with both axial and transverse displacements are derived based on Hamilton's principle and solved utilizing the differential transformation method (DTM) to find the non-dimensional natural frequencies. The results have good agreements with those discussing in the literature. After validation of the present model, the effect of various parameters such as mass and position of the attached nano particle, FG power-law exponent, thermal load type, material distribution type and nonlocal parameter on the frequency of nano sensor are studied. It is shown that the present model produces results of high accuracy, and it can be used as a benchmark in future studies of the free vibration of FG Nano-Mass Sensors.

1RXS J180834.7+101041 is a new cataclysmic variable with non-uniform disc

NASA Astrophysics Data System (ADS)

Yakin, D. G.; Suleimanov, V. F.; Shimansky, V. V.; Borisov, N. V.; Bikmaev, I. F.; Sakhibullin, N. A.

2010-11-01

Results of photometric and spectroscopic investigations of the recently discovered disc cataclysmic variable star 1RXS J180834.7+101041 are presented. Emission spectra of the system show broad double peaked hydrogen and helium emission lines. Doppler maps for the hydrogen lines demonstrate strongly non-uniform emissivity distribution in the disc, similar to that found in IP Peg. It means that the system is a new cataclysmic variable with a spiral density wave in the disc. Masses of the components (MWD = 0.8+/-0.22 Msolar and MRD = 0.14+/-0.02 Msolar), and the orbit inclination (i = 78°+/- 1.°5) were estimated using the various well-known relations for cataclysmic variables.

A Probabilistic Mass Estimation Algorithm for a Novel 7- Channel Capacitive Sample Verification Sensor

NASA Technical Reports Server (NTRS)

Wolf, Michael

2012-01-01

A document describes an algorithm created to estimate the mass placed on a sample verification sensor (SVS) designed for lunar or planetary robotic sample return missions. A novel SVS measures the capacitance between a rigid bottom plate and an elastic top membrane in seven locations. As additional sample material (soil and/or small rocks) is placed on the top membrane, the deformation of the membrane increases the capacitance. The mass estimation algorithm addresses both the calibration of each SVS channel, and also addresses how to combine the capacitances read from each of the seven channels into a single mass estimate. The probabilistic approach combines the channels according to the variance observed during the training phase, and provides not only the mass estimate, but also a value for the certainty of the estimate. SVS capacitance data is collected for known masses under a wide variety of possible loading scenarios, though in all cases, the distribution of sample within the canister is expected to be approximately uniform. A capacitance-vs-mass curve is fitted to this data, and is subsequently used to determine the mass estimate for the single channel s capacitance reading during the measurement phase. This results in seven different mass estimates, one for each SVS channel. Moreover, the variance of the calibration data is used to place a Gaussian probability distribution function (pdf) around this mass estimate. To blend these seven estimates, the seven pdfs are combined into a single Gaussian distribution function, providing the final mean and variance of the estimate. This blending technique essentially takes the final estimate as an average of the estimates of the seven channels, weighted by the inverse of the channel s variance.

Numerical analysis on performance and contaminated failures of the miniature split Stirling cryocooler

NASA Astrophysics Data System (ADS)

He, Ya-Ling; Zhang, Dong-Wei; Yang, Wei-Wei; Gao, Fan

2014-01-01

A mathematical model based on thermodynamic theory of variable mass is developed for the split Stirling refrigerator, in which, the whole machine is considered by one-dimensional approach while the processes in the regenerator are simulated by two-dimensional approach. First, the influence of the ideal frost layer distributions on the flow and heat transfer in the regenerator and the performance of the Stirling cryocooler are simulated. Then, the distribution of the contaminated water vapor and its coagulated and deposited process is qualitatively analyzed. Finally, the lifetime of the refrigerator is evaluated based on the calculated data. The results show that when the refrigerator is operated at uniform distribution of the water vapor partial pressure in the regenerator, the cooling capacity is reduced over 10% at about 631 h, and the power consumption of compressor is increased over 20% at about 1168 h. However, for the linear distribution of water vapor partial pressure, the refrigerator can work properly because the frost never reaches the criterion of failure. Also, it is found that when the Stirling cryocooler restarts after a shutdown, the cooling capacity is reduced by 10% once the frost mass is over 7.05 mg, and there is no cooling capacity once the frost mass reaches 41.2 mg.

Global survey of star clusters in the Milky Way. VI. Age distribution and cluster formation history

NASA Astrophysics Data System (ADS)

Piskunov, A. E.; Just, A.; Kharchenko, N. V.; Berczik, P.; Scholz, R.-D.; Reffert, S.; Yen, S. X.

2018-06-01

Context. The all-sky Milky Way Star Clusters (MWSC) survey provides uniform and precise ages, along with other relevant parameters, for a wide variety of clusters in the extended solar neighbourhood. Aims: In this study we aim to construct the cluster age distribution, investigate its spatial variations, and discuss constraints on cluster formation scenarios of the Galactic disk during the last 5 Gyrs. Methods: Due to the spatial extent of the MWSC, we have considered spatial variations of the age distribution along galactocentric radius RG, and along Z-axis. For the analysis of the age distribution we used 2242 clusters, which all lie within roughly 2.5 kpc of the Sun. To connect the observed age distribution to the cluster formation history we built an analytical model based on simple assumptions on the cluster initial mass function and on the cluster mass-lifetime relation, fit it to the observations, and determined the parameters of the cluster formation law. Results: Comparison with the literature shows that earlier results strongly underestimated the number of evolved clusters with ages t ≳ 100 Myr. Recent studies based on all-sky catalogues agree better with our data, but still lack the oldest clusters with ages t ≳ 1 Gyr. We do not observe a strong variation in the age distribution along RG, though we find an enhanced fraction of older clusters (t > 1 Gyr) in the inner disk. In contrast, the distribution strongly varies along Z. The high altitude distribution practically does not contain clusters with t < 1 Gyr. With simple assumptions on the cluster formation history, the cluster initial mass function and the cluster lifetime we can reproduce the observations. The cluster formation rate and the cluster lifetime are strongly degenerate, which does not allow us to disentangle different formation scenarios. In all cases the cluster formation rate is strongly declining with time, and the cluster initial mass function is very shallow at the high mass end.

Adaptive histogram equalization in digital radiography of destructive skeletal lesions.

PubMed

Braunstein, E M; Capek, P; Buckwalter, K; Bland, P; Meyer, C R

1988-03-01

Adaptive histogram equalization, an image-processing technique that distributes pixel values of an image uniformly throughout the gray scale, was applied to 28 plain radiographs of bone lesions, after they had been digitized. The non-equalized and equalized digital images were compared by two skeletal radiologists with respect to lesion margins, internal matrix, soft-tissue mass, cortical breakthrough, and periosteal reaction. Receiver operating characteristic (ROC) curves were constructed on the basis of the responses. Equalized images were superior to nonequalized images in determination of cortical breakthrough and presence or absence of periosteal reaction. ROC analysis showed no significant difference in determination of margins, matrix, or soft-tissue masses.

Conservative algorithms for non-Maxwellian plasma kinetics

DOE PAGES

Le, Hai P.; Cambier, Jean -Luc

2017-12-08

Here, we present a numerical model and a set of conservative algorithms for Non-Maxwellian plasma kinetics with inelastic collisions. These algorithms self-consistently solve for the time evolution of an isotropic electron energy distribution function interacting with an atomic state distribution function of an arbitrary number of levels through collisional excitation, deexcitation, as well as ionization and recombination. Electron-electron collisions, responsible for thermalization of the electron distribution, are also included in the model. The proposed algorithms guarantee mass/charge and energy conservation in a single step, and is applied to the case of non-uniform gridding of the energy axis in the phasemore » space of the electron distribution function. Numerical test cases are shown to demonstrate the accuracy of the method and its conservation properties.« less

The idea of uniform change: is it time to revisit a central tenet of Rose's "Strategy of Preventive Medicine"?

PubMed

Razak, Fahad; Davey Smith, George; Subramanian, S V

2016-12-01

A mean-centric view of populations, whereby a change in the mean of a health variable at the population level is assumed to result in uniform change across the distribution, is a core component of Geoffrey Rose's concept of the "population strategy" to disease prevention. This idea also has a critical role in Rose's observation that individuals who are considered abnormal or sick (the rightward tail of the distribution) and those who are considered normal (the center) are very closely related, and that true preventive medicine must focus on shifting the normal or average. In this Perspective, we revisit these core tenets of Rose's concept of preventive medicine after providing an overview of the key concepts that he developed. We examine whether these assumptions apply to population changes in body mass index (BMI) and show that there is considerable evidence of a widening of the BMI distribution in populations over time. We argue that, with respect to BMI, the idea of using statistical measures of a population solely on the basis of means and the assumption that populations are coherent entities that change uniformly over time may not fully capture the true nature of changes in the population. These issues have important implications for how we assess and interpret the health of populations over time with implications for the balance between universal and targeted strategies aimed at improving health. © 2016 American Society for Nutrition.

Urban mass transportation industry uniform system of accounts and records and reporting system. Volume II. Uniform system of accounts and records.

DOT National Transportation Integrated Search

1977-01-10

The purpose of the report is to present and document the detailed features of the uniform system of accounts and records and reporting system required by Section 15 of the Urban Mass Transportation Act of 1964, as amended. Volume 2 contains the defin...

Groundwater contamination downstream of a contaminant penetration site. II. Horizontal penetration of the contaminant plume

USGS Publications Warehouse

Rubin, H.; Buddemeier, R.W.

2002-01-01

Part I of this study (Rubin, H.; Buddemeier, R.W. Groundwater Contamination Downstream of a Contaminant Penetration Site Part 1: Extension-Expansion of the Contaminant Plume. J. of Environmental Science and Health Part A (in press).) addressed cases, in which a comparatively thin contaminated region represented by boundary layers (BLs) developed within the freshwater aquifer close to contaminant penetration site. However, at some distance downstream from the penetration site, the top of the contaminant plume reaches the top or bottom of the aquifer. This is the location of the "attachment point," which comprises the entrance cross section of the domain evaluated by the present part of the study. It is shown that downstream from the entrance cross section, a set of two BLs develop in the aquifer, termed inner and outer BLs. It is assumed that the evaluated domain, in which the contaminant distribution gradually becomes uniform, can be divided into two sections, designated: (a) the restructuring section, and (b) the establishment section. In the restructuring section, the vertical concentration gradient leads to expansion of the inner BL at the expense of the outer BL, and there is almost no transfer of contaminant mass between the two layers. In the establishment section, each of the BLs occupies half of the aquifer thickness, and the vertical concentration gradient leads to transfer of contaminant mass from the inner to the outer BL. By use of BL approximations, changes of salinity distribution in the aquifer are calculated and evaluated. The establishment section ends at the uniformity point, downstream from which the contaminant concentration profile is practically uniform. The length of the restructuring section, as well as that of the establishment section, is approximately proportional to the aquifer thickness squared, and is inversely proportional to the transverse dispersivity. The study provides a convenient set of definitions and terminology that are helpful in visualizing the gradual development of uniform contaminant concentration distribution in an aquifer subject to contaminant plume penetration. The method developed in this study can be applied to a variety of problems associated with groundwater quality, such as initial evaluation of field data, design of field data collection, the identification of appropriate boundary conditions for numerical models, selection of appropriate numerical modeling approaches, interpretation and evaluation of field monitoring results, etc.

Airborne pollutant characteristics in an urban, industrial and agricultural complex metroplex with high emission loading and ammonia concentration.

PubMed

Tsai, Jiun-Horng; Chang, Li-Peng; Chiang, Hung-Lung

2014-10-01

The size distribution of particulate mass and water-soluble ionic constituents and their gaseous precursors was investigated in a subtropical area, southern Taiwan. Field sampling and chemical analysis of particulate matter (PM) were conducted using a Micro Orifice Uniform Deposition Impactor (MOUDI) and a Nano-MOUDI, and gaseous pollutants were determined by a denuder-filter pack system. PM size mass distribution, mass concentration and ionic species concentration were measured during the day and at night in the winter and summer. Average PM concentrations in the winter were as high as 132 ± 42 μg/m(3), and PM mass concentrations in the summer were as low as 38 ± 19 μg/m(3). Generally, PM concentration was 111 ± 60 μg/m(3) at night, which was 20% higher than that in the daytime. The size-segregated mass distribution of PM mass concentration was over 85% in the 0.1-3.2 μm range. Ammonium, nitrate, and sulfate were the dominant water-soluble ionic species in PM, contributing 34%-48% of PM mass. High ammonia (12.9-49 μg/m(3)) and SO2 (2.6-27 μg/m(3)) were observed in the gas precursors. The molar ratio [Formula: see text] was 3.18 ± 1.20 at PM1.0, which indicated that the PM was rich in ammonium. Therefore, the excess ammonium could neutralize nitrate to form ammonium nitrate, after the more stable ammonium sulfate and ammonium bisulfate formation. Copyright © 2014 Elsevier B.V. All rights reserved.

Cavitation effects in ultrasonic cleaning baths

NASA Technical Reports Server (NTRS)

Glasscock, Barbara H.

1995-01-01

In this project, the effect of cavitation from aqueous ultrasonic cleaning on the surfaces of metal and non-metal sample coupons was studied. After twenty cleaning cycles, the mass loss from the aluminum coupons averaged 0.22 mg/sq cm surface area and 0.014 mg/sq cm for both stainless steel and titanium. The aluminum coupons showed visual evidence of minor cavitation erosion in regions of previously existing surface irregularities. The non-metal samples showed some periods of mass gain. These effects are believed to have minor impact on hardware being cleaned, but should be evaluated in the context of specific hardware requirements. Also the ultrasonic activity in the large cleaning baths was found to be unevenly distributed as measured by damage to sheets of aluminum foil. It is therefore recommended that items being cleaned in an ultrasonic bath be moved or conveyed during the cleaning to more evenly distribute the cavitation action provide more uniform cleaning.

Predicting ambient aerosol thermal-optical reflectance measurements from infrared spectra: elemental carbon

NASA Astrophysics Data System (ADS)

Dillner, A. M.; Takahama, S.

2015-10-01

Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as thermal-optical reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier transform infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive and nondestructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FT-IR spectra are divided into calibration and test sets. Two calibrations are developed: one developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a uniform distribution of Low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the Low EC calibration to Low EC samples and the Uniform EC calibration to all other samples is used to produce predictions for Low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), no bias (0.00 μg m-3, a concentration value based on the nominal IMPROVE sample volume of 32.8 m3), low error (0.03 μg m-3) and reasonable normalized error (21 %). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. Only the normalized error is higher for the FT-IR EC measurements than for collocated TOR. FT-IR spectra are also divided into calibration and test sets by the ratios OC/EC and ammonium/EC to determine the impact of OC and ammonium on EC prediction. We conclude that FT-IR analysis with partial least squares regression is a robust method for accurately predicting TOR EC in IMPROVE network samples, providing complementary information to TOR OC predictions (Dillner and Takahama, 2015) and the organic functional group composition and organic matter estimated previously from the same set of sample spectra (Ruthenburg et al., 2014).

Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: elemental carbon

NASA Astrophysics Data System (ADS)

Dillner, A. M.; Takahama, S.

2015-06-01

Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as Thermal-Optical Reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier Transform Infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure tested and developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FTIR spectra are divided into calibration and test sets. Two calibrations are developed, one which is developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a~uniform distribution of low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the low EC calibration to low EC samples and the Uniform EC calibration to all other samples is used to produces predictions for low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of variation (R2; 0.96), no bias (0.00 μg m-3, concentration value based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.03 μg m-3) and reasonable normalized error (21 %). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. Only the normalized error is higher for the FT-IR EC measurements than for collocated TOR. FT-IR spectra are also divided into calibration and test sets by the ratios OC/EC and ammonium/EC to determine the impact of OC and ammonium on EC prediction. We conclude that FT-IR analysis with partial least squares regression is a robust method for accurately predicting TOR EC in IMPROVE network samples; providing complementary information to TOR OC predictions (Dillner and Takahama, 2015) and the organic functional group composition and organic matter (OM) estimated previously from the same set of sample spectra (Ruthenburg et al., 2014).

Separation in 5 Msun Binaries

NASA Astrophysics Data System (ADS)

Evans, Nancy R.; Bond, H. E.; Schaefer, G.; Mason, B. D.; Karovska, M.; Tingle, E.

2013-01-01

Cepheids (5 Msun stars) provide an excellent sample for determining the binary properties of fairly massive stars. International Ultraviolet Explorer (IUE) observations of Cepheids brighter than 8th magnitude resulted in a list of ALL companions more massive than 2.0 Msun uniformly sensitive to all separations. Hubble Space Telescope Wide Field Camera 3 (WFC3) has resolved three of these binaries (Eta Aql, S Nor, and V659 Cen). Combining these separations with orbital data in the literature, we derive an unbiased distribution of binary separations for a sample of 18 Cepheids, and also a distribution of mass ratios. The distribution of orbital periods shows that the 5 Msun binaries prefer shorter periods than 1 Msun stars, reflecting differences in star formation processes.

First Results on Angular Distributions of Thermal Dileptons in Nuclear Collisions

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

Arnaldi, R.; Colla, A.; Cortese, P.

The NA60 experiment at the CERN Super Proton Synchrotron has studied dimuon production in 158A GeV In-In collisions. The strong excess of pairs above the known sources found in the complete mass region 0.2

Impact of uniform electrode current distribution on ETF

NASA Technical Reports Server (NTRS)

Bents, D. J.

1982-01-01

The design impacts on the ETF electrode consolidation network associated with uniform channel electrode current distribution are examined and the alternate consolidation design which occur are presented compared to the baseline (non-uniform current) design with respect to performance, and hardware requirements. A rational basis is given for comparing the requirements for the different designs and the savings that result from uniform current distribution. Performance and cost impacts upon the combined cycle plant are discussed.

The Mass Evolution of Protostellar Disks and Envelopes in the Perseus Molecular Cloud

NASA Astrophysics Data System (ADS)

Andersen, Bridget; Stephens, Ian; Dunham, Michael; Pokhrel, Riwaj; Jørgensen, Jes; Frimann, Søren

2018-01-01

In the standard picture for low-mass star formation, a dense molecular cloud undergoes gravitational collapse to form a protostellar system consisting of a new central star, a circumstellar disk, and a surrounding envelope of remaining material. The mass distribution of the system evolves as matter accretes from the large-scale envelope through the disk and onto the protostar. While this general picture is supported by simulations and indirect observational measurements, the specific timescales related to disk growth and envelope dissipation remain poorly constrained. We present a rigorous test of a method introduced by Jørgensen et al. (2009) to obtain observational mass measurements of disks and envelopes around embedded protostars from unresolved (resolution of ~1000 AU) observations. Using data from the recent Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey, we derive disk and envelope mass estimates for 59 protostellar systems in the Perseus molecular cloud. We compare our results to independent disk mass measurements from the VLA Nascent Disk and Multiplicity (VANDAM) survey and find a strong linear correlation. Then, leveraging the size and uniformity of our sample, we find no significant trend in protostellar mass distribution as a function of age, as approximated from bolometric temperatures. These results may indicate that the disk mass of a protostar is set near the onset of the Class 0 protostellar stage and remains roughly constant throughout the Class I protostellar stage.

Energy distributions of an ion in a radio-frequency trap immersed in a buffer gas under the influence of additional external forces

NASA Astrophysics Data System (ADS)

Rouse, I.; Willitsch, S.

2018-04-01

An ion held in a radio-frequency trap interacting with a uniform buffer gas of neutral atoms develops a steady-state energy distribution characterized by a power-law tail at high energies instead of the exponential decay characteristic of thermal equilibrium. We have previously shown that the Tsallis statistics frequently used as an empirical model for this distribution is a good approximation when the ion is heated due to a combination of micromotion interruption and exchange of kinetic energy with the buffer gas [Rouse and Willitsch, Phys. Rev. Lett. 118, 143401 (2017), 10.1103/PhysRevLett.118.143401]. Here, we extend our treatment to include the heating due to additional motion of the ion caused by external forces, including the "excess micromotion" induced by uniform electric fields and rf phase offsets. We show that this also leads to a Tsallis distribution with a potentially different power-law exponent from that observed in the absence of this additional forced motion, with the difference increasing as the ratio of the mass of the neutral atoms to that of the ion decreases. Our results indicate that unless the excess micromotion is minimized to a very high degree, then even a system with very light neutrals and a heavy ion does not exhibit a thermal distribution.

Uniform Mass Distribution Properties and Body Size Appropriate for the 50 Percentile Male Aircrewmember during 1980-1990.

DTIC Science & Technology

1981-03-27

a(ireument that differences in recorded data for this size- was . .;mall amongj the various users. An Anthropometry Task group and a Mas...meeting, Dr. K. W. Kennedy of the Anthropometry Tauk group provided a status report on the Air Force proqram to develop appropriate anthropometric and...seating considerations and requirements for the handicapped and elderly . Included in this reference are dimensions for link systems and simple drafting

[Welding arc temperature field measurements based on Boltzmann spectrometry].

PubMed

Si, Hong; Hua, Xue-Ming; Zhang, Wang; Li, Fang; Xiao, Xiao

2012-09-01

Arc plasma, as non-uniform plasma, has complicated energy and mass transport processes in its internal, so plasma temperature measurement is of great significance. Compared with absolute spectral line intensity method and standard temperature method, Boltzmann plot measuring is more accurate and convenient. Based on the Boltzmann theory, the present paper calculates the temperature distribution of the plasma and analyzes the principle of lines selection by real time scanning the space of the TIG are measurements.

Geography of end-Cretaceous marine bivalve extinctions

NASA Technical Reports Server (NTRS)

Raup, David M.; Jablonski, David

1993-01-01

Analysis of the end-Cretaceous mass extinction, based on 3514 occurrences of 340 genera of marine bivalves (Mollusca), suggests that extinction intensities were uniformly global; no latitudinal gradients or other geographic patterns are detected. Elevated extinction intensities in some tropical areas are entirely a result of the distribution of one extinct group of highly specialized bivalves, the rudists. When rudists are omitted, intensities at those localities are statistically indistinguishable from those of both the rudist-free tropics and extratropical localities.

Flight evidence of spacecraft surface contamination rate enhancement by spacecraft charging obtained with a quartz crystal microbalance

NASA Technical Reports Server (NTRS)

Clark, D. M.; Hall, D. F.

1980-01-01

The significance of the fraction of the mass outgassed by a negatively charged space vehicle which is ionized within the vehicle plasma sheath and electrostatically reattracted to the space vehicle was determined. The ML-12 retarding potential analyzer/temperature controlled quartz crystal microbalances (RPA/TQCMs) distinguishes between charged and neutral molecules and investigates contamination mass transport mechanism. Two long term, quick look flight data sets indicate that on the average a significant fraction of mass arriving at one RPA/TQCM is ionized. It is assumed that vehicle frame charging during these periods was approximately uniformly distributed in degree and frequency. It is shown that electrostatic reattraction of ionized molecules is an important contamination mechanism at and near geosynchronous altitudes.

Laminar mixing in a small floating zone

NASA Technical Reports Server (NTRS)

Harriott, George M.

1987-01-01

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

Treatment of internal sources in the finite-volume ELLAM

USGS Publications Warehouse

Healy, R.W.; ,; ,; ,; ,; ,

2000-01-01

The finite-volume Eulerian-Lagrangian localized adjoint method (FVELLAM) is a mass-conservative approach for solving the advection-dispersion equation. The method has been shown to be accurate and efficient for solving advection-dominated problems of solute transport in ground water in 1, 2, and 3 dimensions. Previous implementations of FVELLAM have had difficulty in representing internal sources because the standard assumption of lowest order Raviart-Thomas velocity field does not hold for source cells. Therefore, tracking of particles within source cells is problematic. A new approach has been developed to account for internal sources in FVELLAM. It is assumed that the source is uniformly distributed across a grid cell and that instantaneous mixing takes place within the cell, such that concentration is uniform across the cell at any time. Sub-time steps are used in the time-integration scheme to track mass outflow from the edges of the source cell. This avoids the need for tracking within the source cell. We describe the new method and compare results for a test problem with a wide range of cell Peclet numbers.

Size and composition distribution of fine particulate matter emitted from wood burning, meat charbroiling, and cigarettes

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

Kleeman, M.J.; Schauer, J.J.; Cass, G.R.

A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from air pollution sources. Measurements are made using a laser optical particle counter (OPC), a differential mobility analyzer/condensation nucleus counter (DMA/CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include wood smoke (pine, oak, eucalyptus), meat charbroiling, and cigarettes. The particle mass distributions from all wood smoke sources have a single mode that peaks at approximately 0.1--0.2 {micro}m particle diameter. The smoke from meat charbroiling shows a major peak in the particle mass distribution atmore » 0.1--0.2 {micro}m particle diameter, with some material present at larger particle sizes. Particle mass distributions from cigarettes peak between 0.3 and 0.4 {micro}m particle diameter. Chemical composition analysis reveals that particles emitted from the sources tested here are largely composed of organic compounds. Noticeable concentrations of elemental carbon are found in the particles emitted from wood burning. The size distributions of the trace species emissions from these sources also are presented, including data for Na, K, Ti, Fe, Br, Ru, Cl, Al, Zn, Ba, Sr, V, Mn, Sb, La, Ce, as well as sulfate, nitrate, and ammonium ion when present in statistically significant amounts. These data are intended for use with air quality models that seek to predict the size distribution of the chemical composition of atmospheric fine particles.« less

High spatial resolution mass spectrometry imaging reveals the genetically programmed, developmental modification of the distribution of thylakoid membrane lipids among individual cells of maize leaf

DOE PAGES

Duenas, Maria Emilia; Klein, Adam T.; Alexander, Liza E.; ...

2016-11-17

Metabolism in plants is compartmentalized among different tissues, cells and subcellular organelles. Mass spectrometry imaging (MSI) with matrix-assisted laser desorption ionization (MALDI) has recently advanced to allow for the visualization of metabolites at single-cell resolution. Here we applied 5- and 10 μm high spatial resolution MALDI-MSI to the asymmetric Kranz anatomy of Zea mays (maize) leaves to study the differential localization of two major anionic lipids in thylakoid membranes, sulfoquinovosyldiacylglycerols (SQDG) and phosphatidylglycerols (PG). The quantification and localization of SQDG and PG molecular species, among mesophyll (M) and bundle sheath (BS) cells, are compared across the leaf developmental gradient frommore » four maize genotypes (the inbreds B73 and Mo17, and the reciprocal hybrids B73 × Mo17 and Mo17 × B73). SQDG species are uniformly distributed in both photosynthetic cell types, regardless of leaf development or genotype; however, PG shows photosynthetic cell-specific differential localization depending on the genotype and the fatty acyl chain constituent. Overall, 16:1-containing PGs primarily contribute to the thylakoid membranes of M cells, whereas BS chloroplasts are mostly composed of 16:0-containing PGs. Furthermore, PG 32:0 shows genotype-specific differences in cellular distribution, with preferential localization in BS cells for B73, but more uniform distribution between BS and M cells in Mo17. Maternal inheritance is exhibited within the hybrids, such that the localization of PG 32:0 in B73 × Mo17 is similar to the distribution in the B73 parental inbred, whereas that of Mo17 × B73 resembles the Mo17 parent. As a result, this study demonstrates the power of MALDI-MSI to reveal unprecedented insights on metabolic outcomes in multicellular organisms at single-cell resolution.« less

The Mass Outflow Rate of the Milky Way

NASA Astrophysics Data System (ADS)

Fox, Andrew

2017-08-01

The balance between gaseous inflow and outflow regulates star formation in spiral galaxies. This paradigm can be tested in the Milky Way, but whereas the star formation rate and inflow rate have both been measured, the outflow rate has not. We propose an archival COS program to determine the Galactic outflow rate in cool gas ( 10^4 K) by surveying UV absorption line high-velocity clouds (HVCs). This project will make use of the newly updated Hubble Spectroscopic Legacy Archive, which contains a uniformly reduced sample of 233 COS G130M spectra of background AGN. The outflow rate will be determined by (1) searching for redshifted HVCs; (2) modeling the clouds with photoionization simulations to determine their masses and physical properties; (3) combining the cloud masses with their velocities and distances. We will measure how the outflow is distributed spatially across the sky, calculate its mass loading factor, and compare the line profiles to synthetic spectra extracted from new hydrodynamic simulations. The distribution of HVC velocities will inform us what fraction of the outflowing clouds will escape the halo and what fraction will circulate back to the disk, to better understand how and where gas enters and exits the Milky Way.

Size mass distribution of water-soluble ionic species and gas conversion to sulfate and nitrate in particulate matter in southern Taiwan.

PubMed

Tsai, Jiun-Horng; Chang, Li-Peng; Chiang, Hung-Lung

2013-07-01

A Micro-Orifice Uniform Deposition Impactor (MOUDI) and a Nano-MOUDI were employed to determine the size-segregated mass distributions of ambient particulate matter (PM) and water-soluble ionic species for particulate constituents. In addition, gas precursors, including HCl, HONO, HNO3, SO2, and NH3 gases, were analyzed by an annular denuder system. PM size mass distribution, mass concentration, and ionic species concentration were measured during the day and at night during episode and non-episode periods in winter and summer. Average total suspended particle (TSP) concentrations during episode days in winter were as high as 153 ± 33 μg/m(3), and PM mass concentrations in summer were as low as one-third of that in winter. Generally, PM concentration at night was higher than that in the daytime in southern Taiwan during the sampling periods. In winter during the episode periods, the size-segregated mass distribution of PM mass concentration was mostly in the 0.32-3.2-μm range, and the PM concentration increased significantly in the range of 0.32-3.2 μm at night. Ammonium, nitrate, and sulfate were the dominant water-soluble ionic species in PM, contributing 34-48% of TSP mass. High concentrations of ammonia (12.9-49 μg/m(3)) and SO2 (2.6-27 μg/m(3)) were observed in the gas precursors. The conversion ratio was high in the PM size range of 0.18-3.2 μm both during the day and at night in winter, and the conversion ratio of episode days was 20% higher than that of non-episode days. The conversion factor was high for both nitrogen and sulfur species at nighttime, especially on episode days.

The late behavior of supernova 1987A. I - The light curve. II - Gamma-ray transparency of the ejecta

NASA Technical Reports Server (NTRS)

Arnett, W. David; Fu, Albert

1989-01-01

Observations of the late (t = 20-1500 days) bolometric light curve and the gamma-lines and X-rays from supernova 1987A are compared to theoretical models. It is found that 0.073 + or - 0.015 solar masses of freshly synthesized Ni-56 must be present to fit the bolometric light curve. The results place limits on the luminosity and presumed period of the newly formed pulsar/neutron star. In the second half of the paper, the problem of computing the luminosities in gamma-ray lines and in X-rays from supernova 1987A is addressed. High-energy observations suggest the development of large-scale clumping and bubbling of radioactive material in the ejecta. A model is proposed with a hydrogen envelope mass of about 7 solar masses, homologous scale expansion velocities of about 3000 km/s, and an approximately uniform mass distribution.

Measurement of spatial and temporal variation in volatile hazardous air pollutants in Tacoma, Washington, using a mobile membrane introduction mass spectrometry (MIMS) system.

PubMed

Davey, Nicholas G; Fitzpatrick, Cole T E; Etzkorn, Jacob M; Martinsen, Morten; Crampton, Robert S; Onstad, Gretchen D; Larson, Timothy V; Yost, Michael G; Krogh, Erik T; Gilroy, Michael; Himes, Kathy H; Saganić, Erik T; Simpson, Christopher D; Gill, Christopher G

2014-09-19

The objective of this study was to use membrane introduction mass spectrometry (MIMS), implemented on a mobile platform, in order to provide real-time, fine-scale, temporally and spatially resolved measurements of several hazardous air pollutants. This work is important because there is now substantial evidence that fine-scale spatial and temporal variations of air pollutant concentrations are important determinants of exposure to air pollution and adverse health outcomes. The study took place in Tacoma, WA during periods of impaired air quality in the winter and summer of 2008 and 2009. Levels of fine particles were higher in winter compared to summer, and were spatially uniform across the study area. Concentrations of vapor phase pollutants measured by membrane introduction mass spectrometry (MIMS), notably benzene and toluene, had relatively uniform spatial distributions at night, but exhibited substantial spatial variation during the day-daytime levels were up to 3-fold higher at traffic-impacted locations compared to a reference site. Although no direct side-by-side comparison was made between the MIMS system and traditional fixed site monitors, the MIMS system typically reported higher concentrations of specific VOCs, particularly benzene, ethylbenzene and naphthalene, compared to annual average concentrations obtained from SUMA canisters and gas chromatographic analysis at the fixed sites.

Neutron-Star Radius from a Population of Binary Neutron Star Mergers.

PubMed

Bose, Sukanta; Chakravarti, Kabir; Rezzolla, Luciano; Sathyaprakash, B S; Takami, Kentaro

2018-01-19

We show how gravitational-wave observations with advanced detectors of tens to several tens of neutron-star binaries can measure the neutron-star radius with an accuracy of several to a few percent, for mass and spatial distributions that are realistic, and with none of the sources located within 100 Mpc. We achieve such an accuracy by combining measurements of the total mass from the inspiral phase with those of the compactness from the postmerger oscillation frequencies. For estimating the measurement errors of these frequencies, we utilize analytical fits to postmerger numerical relativity waveforms in the time domain, obtained here for the first time, for four nuclear-physics equations of state and a couple of values for the mass. We further exploit quasiuniversal relations to derive errors in compactness from those frequencies. Measuring the average radius to well within 10% is possible for a sample of 100 binaries distributed uniformly in volume between 100 and 300 Mpc, so long as the equation of state is not too soft or the binaries are not too heavy. We also give error estimates for the Einstein Telescope.

Approximation of a radial diffusion model with a multiple-rate model for hetero-disperse particle mixtures

PubMed Central

Ju, Daeyoung; Young, Thomas M.; Ginn, Timothy R.

2012-01-01

An innovative method is proposed for approximation of the set of radial diffusion equations governing mass exchange between aqueous bulk phase and intra-particle phase for a hetero-disperse mixture of particles such as occur in suspension in surface water, in riverine/estuarine sediment beds, in soils and in aquifer materials. For this purpose the temporal variation of concentration at several uniformly distributed points within a normalized representative particle with spherical, cylindrical or planar shape is fitted with a 2-domain linear reversible mass exchange model. The approximation method is then superposed in order to generalize the model to a hetero-disperse mixture of particles. The method can reduce the computational effort needed in solving the intra-particle mass exchange of a hetero-disperse mixture of particles significantly and also the error due to the approximation is shown to be relatively small. The method is applied to describe desorption batch experiment of 1,2-Dichlorobenzene from four different soils with known particle size distributions and it could produce good agreement with experimental data. PMID:18304692

Rapid learning of visual ensembles.

PubMed

Chetverikov, Andrey; Campana, Gianluca; Kristjánsson, Árni

2017-02-01

We recently demonstrated that observers are capable of encoding not only summary statistics, such as mean and variance of stimulus ensembles, but also the shape of the ensembles. Here, for the first time, we show the learning dynamics of this process, investigate the possible priors for the distribution shape, and demonstrate that observers are able to learn more complex distributions, such as bimodal ones. We used speeding and slowing of response times between trials (intertrial priming) in visual search for an oddly oriented line to assess internal models of distractor distributions. Experiment 1 demonstrates that two repetitions are sufficient for enabling learning of the shape of uniform distractor distributions. In Experiment 2, we compared Gaussian and uniform distractor distributions, finding that following only two repetitions Gaussian distributions are represented differently than uniform ones. Experiment 3 further showed that when distractor distributions are bimodal (with a 30° distance between two uniform intervals), observers initially treat them as uniform, and only with further repetitions do they begin to treat the distributions as bimodal. In sum, observers do not have strong initial priors for distribution shapes and quickly learn simple ones but have the ability to adjust their representations to more complex feature distributions as information accumulates with further repetitions of the same distractor distribution.

Uniform irradiation of irregularly shaped cavities for photodynamic therapy.

PubMed

Rem, A I; van Gemert, M J; van der Meulen, F W; Gijsbers, G H; Beek, J F

1997-03-01

It is difficult to achieve a uniform light distribution in irregularly shaped cavities. We have conducted a study on the use of hollow 'integrating' moulds for more uniform light delivery of photodynamic therapy in irregularly shaped cavities such as the oral cavity. Simple geometries such as a cubical box, a sphere, a cylinder and a 'bottle-neck' geometry have been investigated experimentally and the results have been compared with computed light distributions obtained using the 'radiosity method'. A high reflection coefficient of the mould and the best uniform direct irradiance possible on the inside of the mould were found to be important determinants for achieving a uniform light distribution.

Toward a Galactic Distribution of Planets. I. Methodology and Planet Sensitivities of the 2015 High-cadence Spitzer Microlens Sample

NASA Astrophysics Data System (ADS)

Zhu, Wei; Udalski, A.; Calchi Novati, S.; Chung, S.-J.; Jung, Y. K.; Ryu, Y.-H.; Shin, I.-G.; Gould, A.; Lee, C.-U.; Albrow, M. D.; Yee, J. C.; Han, C.; Hwang, K.-H.; Cha, S.-M.; Kim, D.-J.; Kim, H.-W.; Kim, S.-L.; Kim, Y.-H.; Lee, Y.; Park, B.-G.; Pogge, R. W.; KMTNet Collaboration; Poleski, R.; Mróz, P.; Pietrukowicz, P.; Skowron, J.; Szymański, M. K.; KozLowski, S.; Ulaczyk, K.; Pawlak, M.; OGLE Collaboration; Beichman, C.; Bryden, G.; Carey, S.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Shvartzvald, Y.; Wibking, B.; Spitzer Team

2017-11-01

We analyze an ensemble of microlensing events from the 2015 Spitzer microlensing campaign, all of which were densely monitored by ground-based high-cadence survey teams. The simultaneous observations from Spitzer and the ground yield measurements of the microlensing parallax vector {{\\boldsymbol{π }}}{{E}}, from which compact constraints on the microlens properties are derived, including ≲25% uncertainties on the lens mass and distance. With the current sample, we demonstrate that the majority of microlenses are indeed in the mass range of M dwarfs. The planet sensitivities of all 41 events in the sample are calculated, from which we provide constraints on the planet distribution function. In particular, assuming a planet distribution function that is uniform in {log}q, where q is the planet-to-star mass ratio, we find a 95% upper limit on the fraction of stars that host typical microlensing planets of 49%, which is consistent with previous studies. Based on this planet-free sample, we develop the methodology to statistically study the Galactic distribution of planets using microlensing parallax measurements. Under the assumption that the planet distributions are the same in the bulge as in the disk, we predict that ∼1/3 of all planet detections from the microlensing campaigns with Spitzer should be in the bulge. This prediction will be tested with a much larger sample, and deviations from it can be used to constrain the abundance of planets in the bulge relative to the disk.

Characteristic of nanoparticles generated from different nano-powders by using different dispersion methods

NASA Astrophysics Data System (ADS)

Tsai, Chuen-Jinn; Lin, Guan-Yu; Liu, Chun-Nan; He, Chi-En; Chen, Chun-Wan

2012-03-01

A standard rotating drum with a modified sampling train (RD), a vortex shaker (VS), and a SSPD (small-scale powder disperser) were used to investigate the emission characteristics of nano-powders, including nano-titanium dioxide (nano-TiO2, primary diameter: 21 nm), nano-zinc oxide (nano-ZnO, primary diameter: 30-50 nm), and nano-silicon dioxide (nano-SiO2, primary diameter: 10-30 nm). A TSI SMPS (scanning mobility particle sizer), a TSI APS (aerodynamic particle sizer), and a MSP MOUDI (micro-orifice uniform deposit impactor) were used to measure the number and mass distributions of generated particles. Significant differences in specific number and mass concentration or distributions were found among different methods and nano-powders with the most specific number and mass concentration and the smallest particles being generated by the most energetic SSPD, followed by VS and RD. Near uni-modal number or mass distributions were observed for the SSPD while bi-modal number or mass distributions existed for nano-powders except nano-SiO2 which also exhibited bimodal mass distributions. The 30-min average results showed that the mass median aerodynamic diameter (MMAD) and number median diameter (NMD) of the SSPD ranged 1.1-2.1 μm and 166-261 nm, respectively, for all three nano-powders, which were smaller than those of the VS (MMAD: 3.3-6.0 μm and NMD: 156-462 nm), and the RD (MMAD: 5.2-11.2 μm and NMD: 198-479 nm). For nano-particles (electric mobility diameter < 100 nm), specific mass concentrations were nearly negligible for all three nano-powders and test methods. Specific number concentrations of nano-particles were low for the RD tester but were elevated when more energetic VS and SSPD testers were used. The quantitative size and concentration data obtained in this study is useful to elucidate the field emission and personal exposure data in the future provided that particle loss in the generation system is carefully assessed.

Vibration suppression of planar truss structures utilizing uniform damping control

NASA Technical Reports Server (NTRS)

Andersen, G. C.; Silverberg, L. M.

1986-01-01

A variety of methods has been devised for vibrational control of a structure using both passive and active controls. Presented in this paper is a relatively new method for vibration suppression, uniform damping control. This method consists of implementing a control law which tends to dampen each vibrational mode of the structure at the same desirable exponential rate. The unique aspects of this method are that the control law is not explicitly dependent on the structural stiffness, the control forces are directly proportional to the distribution of the structural mass, and the control law is natural and decentralized. The control law was applied to a flexible planar truss structure and the various aspects of implementation of the control law examined are: actuator/sensor number, placement, and the impact of the actuator/sensor number and placement on the necessary control 'power' requirements such as peak power loads, total power requirements, etc. Also examined are the effects of using a limited number of active members in terms of the vibrational performance when compared with the 'ideal' distributed control law.

On the Improvement of Convergence Performance for Integrated Design of Wind Turbine Blade Using a Vector Dominating Multi-objective Evolution Algorithm

NASA Astrophysics Data System (ADS)

Wang, L.; Wang, T. G.; Wu, J. H.; Cheng, G. P.

2016-09-01

A novel multi-objective optimization algorithm incorporating evolution strategies and vector mechanisms, referred as VD-MOEA, is proposed and applied in aerodynamic- structural integrated design of wind turbine blade. In the algorithm, a set of uniformly distributed vectors is constructed to guide population in moving forward to the Pareto front rapidly and maintain population diversity with high efficiency. For example, two- and three- objective designs of 1.5MW wind turbine blade are subsequently carried out for the optimization objectives of maximum annual energy production, minimum blade mass, and minimum extreme root thrust. The results show that the Pareto optimal solutions can be obtained in one single simulation run and uniformly distributed in the objective space, maximally maintaining the population diversity. In comparison to conventional evolution algorithms, VD-MOEA displays dramatic improvement of algorithm performance in both convergence and diversity preservation for handling complex problems of multi-variables, multi-objectives and multi-constraints. This provides a reliable high-performance optimization approach for the aerodynamic-structural integrated design of wind turbine blade.

Finite Element Aircraft Simulation of Turbulence

NASA Technical Reports Server (NTRS)

McFarland, R. E.

1997-01-01

A turbulence model has been developed for realtime aircraft simulation that accommodates stochastic turbulence and distributed discrete gusts as a function of the terrain. This model is applicable to conventional aircraft, V/STOL aircraft, and disc rotor model helicopter simulations. Vehicle angular activity in response to turbulence is computed from geometrical and temporal relationships rather than by using the conventional continuum approximations that assume uniform gust immersion and low frequency responses. By using techniques similar to those recently developed for blade-element rotor models, the angular-rate filters of conventional turbulence models are not required. The model produces rotational rates as well as air mass translational velocities in response to both stochastic and deterministic disturbances, where the discrete gusts and turbulence magnitudes may be correlated with significant terrain features or ship models. Assuming isotropy, a two-dimensional vertical turbulence field is created. A novel Gaussian interpolation technique is used to distribute vertical turbulence on the wing span or lateral rotor disc, and this distribution is used to compute roll responses. Air mass velocities are applied at significant centers of pressure in the computation of the aircraft's pitch and roll responses.

Algorithms to eliminate the influence of non-uniform intensity distributions on wavefront reconstruction by quadri-wave lateral shearing interferometers

NASA Astrophysics Data System (ADS)

Chen, Xiao-jun; Dong, Li-zhi; Wang, Shuai; Yang, Ping; Xu, Bing

2017-11-01

In quadri-wave lateral shearing interferometry (QWLSI), when the intensity distribution of the incident light wave is non-uniform, part of the information of the intensity distribution will couple with the wavefront derivatives to cause wavefront reconstruction errors. In this paper, we propose two algorithms to reduce the influence of a non-uniform intensity distribution on wavefront reconstruction. Our simulation results demonstrate that the reconstructed amplitude distribution (RAD) algorithm can effectively reduce the influence of the intensity distribution on the wavefront reconstruction and that the collected amplitude distribution (CAD) algorithm can almost eliminate it.

Experimental study of a very high frequency, 162 MHz, segmented electrode, capacitively coupled plasma discharge

NASA Astrophysics Data System (ADS)

Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

2016-09-01

Radio-frequency capacitively coupled plasma (CCP) discharge operating at a very high frequency, 30-300 MHz, offers many advantages over standard 13.56 MHz CCP. However, there is a limited flexibility on the choice of driving frequency and substrate size due to plasma non-uniformity caused by the standing wave effect and edge effect. To overcome this issue segmented electrode CCP's are proposed and researched. Despite its numerous advantages the power coupling mechanism and plasma chemistry in this type of discharge are not fully understood due to lack of experimental data. In this paper, we present the experimental study of a segmented electrode, 3x4 tile array (10x10 cm square tile with 1 cm tile-to-tile separation), CCP discharge driven at 162 MHz. We measured plasma uniformity and gas temperature using hairpin probe and optical emission spectroscopy respectively. A homemade RF compensated Langmuir probe is employed to measure the Electron Energy Distribution Function (EEDF) by second harmonic technique. Energy resolved quadrupole mass spectrometer is utilized to measure the ion energy distribution. Discharge/plasma properties are investigated for several operating conditions and for power coupling mode in both washer board and checker board configuration. The experimental results show that the uniform plasma density can be maintained over a large area along with highly non-equilibrium condition to produce unique gas phase plasma chemistry.

A frequency quantum interpretation of the surface renewal model of mass transfer

PubMed Central

Mondal, Chanchal

2017-01-01

The surface of a turbulent liquid is visualized as consisting of a large number of chaotic eddies or liquid elements. Assuming that surface elements of a particular age have renewal frequencies that are integral multiples of a fundamental frequency quantum, and further assuming that the renewal frequency distribution is of the Boltzmann type, performing a population balance for these elements leads to the Danckwerts surface age distribution. The basic quantum is what has been traditionally called the rate of surface renewal. The Higbie surface age distribution follows if the renewal frequency distribution of such elements is assumed to be continuous. Four age distributions, which reflect different start-up conditions of the absorption process, are then used to analyse transient physical gas absorption into a large volume of liquid, assuming negligible gas-side mass-transfer resistance. The first two are different versions of the Danckwerts model, the third one is based on the uniform and Higbie distributions, while the fourth one is a mixed distribution. For the four cases, theoretical expressions are derived for the rates of gas absorption and dissolved-gas transfer to the bulk liquid. Under transient conditions, these two rates are not equal and have an inverse relationship. However, with the progress of absorption towards steady state, they approach one another. Assuming steady-state conditions, the conventional one-parameter Danckwerts age distribution is generalized to a two-parameter age distribution. Like the two-parameter logarithmic normal distribution, this distribution can also capture the bell-shaped nature of the distribution of the ages of surface elements observed experimentally in air–sea gas and heat exchange. Estimates of the liquid-side mass-transfer coefficient made using these two distributions for the absorption of hydrogen and oxygen in water are very close to one another and are comparable to experimental values reported in the literature. PMID:28791137

Combined effects of total grain-size distribution and crosswind on the rise of eruptive volcanic columns

NASA Astrophysics Data System (ADS)

Girault, F.; Carazzo, G.; Tait, S.; Kaminski, E.

2016-10-01

The maximum height of an explosive volcanic column, H, depends on the 1/4th power of the eruptive mass flux, Q, and on the 3/4th power of the stratification of the atmosphere, N. Expressed as scaling laws, this relationship has made H a widely used proxy to estimate Q. Two additional effects are usually included to produce more accurate and robust estimates of Q based on H: particle sedimentation from the volcanic column, which depends on the total grain-size distribution (TGSD) and the atmospheric crosswind. Both coarse TGSD and strong crosswind have been shown to decrease strongly the maximum column height, and TGSD, which also controls the effective gas content in the column, influences the stability of the column. However, the impact of TGSD and of crosswind on the dynamics of the volcanic column are commonly considered independently. We propose here a steady-state 1D model of an explosive volcanic column rising in a windy atmosphere that explicitly accounts for particle sedimentation and wind together. We consider three typical wind profiles: uniform, linear, and complex, with the same maximum wind velocity of 15 m s- 1. Subject to a uniform wind profile, the calculations show that the maximum height of the plume strongly decreases for any TGSD. The effect of TGSD on maximum height is smaller for uniform and complex wind profiles than for a linear profile or without wind. The largest differences of maximum heights arising from different wind profiles are observed for the largest source mass fluxes (> 107 kg s- 1) for a given TGSD. Compared to no wind conditions, the field of column collapse is reduced for any wind profile and TGSD at the vent, an effect that is the strongest for small mass fluxes and coarse TGSD. Provided that the maximum plume height and the wind profile are known from real-time observations, the model predicts the mass discharge rate feeding the eruption for a given TGSD. We apply our model to a set of eight historical volcanic eruptions for which all the required information is known. Taking into account the measured wind profile and the actual TGSD at the vent substantially improves (by ≈ 30%) the agreement between the mass discharge rate calculated from the model based on plume height and the field observation of deposit mass divided by eruption duration, relative to a model taking into account TGSD only. This study contributes to the improvement of the characterization of volcanic source term required as input to larger scale models of ash and aerosol dispersion.

Raman spectroscopy for the analytical quality control of low-dose break-scored tablets.

PubMed

Gómez, Diego A; Coello, Jordi; Maspoch, Santiago

2016-05-30

Quality control of solid dosage forms involves the analysis of end products according to well-defined criteria, including the assessment of the uniformity of dosage units (UDU). However, in the case of break-scored tablets, given that tablet splitting is widespread as a means to adjust doses, the uniform distribution of the active pharmaceutical ingredient (API) in all the possible fractions of the tablet must be assessed. A general procedure to accomplish with both issues, using Raman spectroscopy, is presented. It is based on the acquisition of a collection of spectra in different regions of the tablet, that later can be selected to determine the amount of API in the potential fractions that can result after splitting. The procedure has been applied to two commercial products, Sintrom 1 and Sintrom 4, with API (acenocoumarol) mass proportion of 2% and 0.7% respectively. Partial Least Squares (PLS) calibration models were constructed for the quantification of acenocoumarol in whole tablets using HPLC as a reference analytical method. Once validated, the calibration models were used to determine the API content in the different potential fragments of the scored Sintrom 4 tablets. Fragment mass measurements were also performed to estimate the range of masses of the halves and quarters that could result after tablet splitting. The results show that Raman spectroscopy can be an alternative analytical procedure to assess the uniformity of content, both in whole tablets as in its potential fragments, and that Sintrom 4 tablets can be perfectly split in halves, but some cautions have to be taken when considering the fragmentation in quarters. A practical alternative to the use of UDU test for the assessment of tablet fragments is proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

Tracing the signatures of heavy ions in the plasma environment of 67P/Churyumov-Gerasimenko: Ion Composition Analyzer (ICA) observations

NASA Astrophysics Data System (ADS)

Nicolaou, G.; Yamauchi, M.; Wieser, M.; Nilsson, H.; Behar, E.; Stenberg Wieser, G.

2016-12-01

The Ion Composition Analyzer (ICA) on board ROSETTA is a part of the Rosetta Plasma Consortium (RPC). It is designed to measure the 3-D velocity distribution function of the plasma ions in the environment of the comet 67P/Churyumov-Gerasimenko. Besides the solar wind plasma ions, ICA detected the heavy ions of cometary origin at both low energy (< 100 eV) and at the keV range. So far, ICA distinguished ions of water origin but in principle it should be able to detect CO2+. However, we have not yet succeeded to separate CO2+ ions from O+ or H2O+ ion, mainly due to non-uniform sensitivity and noise level at different mass-channels//azimuthal-sectors, and high cross talk. In May 2016, when ROSETTA was relatively close to the comet (between 6 and 20 km), we observe a second plasma ion population in a higher energy per charge range ( 60-200 eV/q) than the water group ions at 30- 50eV/q. To examine whether this secondary population is still the water group or other ions, such as CO2+, we cleaned the raw data by correcting the non-uniform sensitivity assuming that the noise level should be uniform over different channels. After such a simple cleaning we already found that the mass peak at low energy and that for higher-energy are occasionally similar but in some cases are quite different. Furthermore, we investigate few cases where the low-energy mass peak seems to consist of different Gaussian slopes, indicating that this peak could be composed of two mass peaks. In this presentation we show our techniques we follow to process the data, and we show how we identify the secondary ion component from the May 2016 data.

Cosmology with galaxy cluster phase spaces

NASA Astrophysics Data System (ADS)

Stark, Alejo; Miller, Christopher J.; Huterer, Dragan

2017-07-01

We present a novel approach to constrain accelerating cosmologies with galaxy cluster phase spaces. With the Fisher matrix formalism we forecast constraints on the cosmological parameters that describe the cosmological expansion history. We find that our probe has the potential of providing constraints comparable to, or even stronger than, those from other cosmological probes. More specifically, with 1000 (100) clusters uniformly distributed in the redshift range 0 ≤z ≤0.8 , after applying a conservative 80% mass scatter prior on each cluster and marginalizing over all other parameters, we forecast 1 σ constraints on the dark energy equation of state w and matter density parameter ΩM of σw=0.138 (0.431 ) and σΩM=0.007(0.025 ) in a flat universe. Assuming 40% mass scatter and adding a prior on the Hubble constant we can achieve a constraint on the Chevallier-Polarski-Linder parametrization of the dark energy equation of state parameters w0 and wa with 100 clusters in the same redshift range: σw 0=0.191 and σwa=2.712. Dropping the assumption of flatness and assuming w =-1 we also attain competitive constraints on the matter and dark energy density parameters: σΩ M=0.101 and σΩ Λ=0.197 for 100 clusters uniformly distributed in the range 0 ≤z ≤0.8 after applying a prior on the Hubble constant. We also discuss various observational strategies for tightening constraints in both the near and far future.

An analytical study of the free and forced vibration response of a ribbed plate with free boundary conditions

NASA Astrophysics Data System (ADS)

Lin, Tian Ran; Zhang, Kai

2018-05-01

An analytical study to predict the vibration response of a ribbed plate with free boundary conditions is presented. The analytical solution was derived using a double cosine integral transform technique and then utilized to study the free and forced vibration of the ribbed plate, as well as the effect of the rib on the modal response of the uniform plate. It is shown that in addition to the three zero-frequency rigid body modes of the plate, the vibration modes of the uniform plate can be classified into four mode groups according to the symmetric properties of the plate with respect to the two orthogonal middle lines parallel to the plate edges. The four mode groups correspond to a double symmetric group, a double anti-symmetric group and two symmetric/anti-symmetric groups. Whilst the inclusion of the rib to the plate is shown to cause distortion to the distribution of vibration modes, most modes can still be traced back to the original modes of the uniform plate. Both the mass and stiffness of the rib are shown to affect the modal vibration of the uniform plate, whereby a dominant effect from the rib mass leads to a decrease in the modal frequency of the plate, whereas a dominant effect from the rib stiffness leads to an increase in plate modal frequency. When the stiffened rib behaves as an effective boundary to the plate vibration, an original plate mode becomes a pair of degenerate modes, whereby one mode has a higher frequency and the other mode has a lower frequency than that of the original mode.

Exposure and toxicity assessment of ultrafine particles from nearby traffic in urban air in seoul, Korea.

PubMed

Yang, Ji-Yeon; Kim, Jin-Yong; Jang, Ji-Young; Lee, Gun-Woo; Kim, Soo-Hwan; Shin, Dong-Chun; Lim, Young-Wook

2013-01-01

We investigated the particle mass size distribution and chemical properties of air pollution particulate matter (PM) in the urban area and its capacity to induce cytotoxicity in human bronchial epithelial (BEAS-2B) cells. To characterize the mass size distributions and chemical concentrations associated with urban PM, PM samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor close to nearby traffic in an urban area from December 2007 to December 2009. PM samples for in vitro cytotoxicity testing were collected by a mini-volume air sampler with PM10 and PM2.5 inlets. The PM size distributions were bi-modal, peaking at 0.18 to 0.32 and 1.8 to 3.2 µm. The mass concentrations of the metals in fine particles (0.1 to 1.8 µm) accounted for 45.6 to 80.4% of the mass concentrations of metals in PM10. The mass proportions of fine particles of the pollutants related to traffic emission, lead (80.4%), cadmium (69.0%), and chromium (63.8%) were higher than those of other metals. Iron was the dominant transition metal in the particles, accounting for 64.3% of the PM10 mass in all the samples. We observed PM concentration-dependent cytotoxic effects on BEAS-2B cells. We found that exposure to PM2.5 and PM10 from a nearby traffic area induced significant increases in protein expression of inflammatory cytokines (IL-6 and IL-8). The cell death rate and release of cytokines in response to the PM2.5 treatment were higher than those with PM10. The combined results support the hypothesis that ultrafine particles from vehicular sources can induce inflammatory responses related to environmental respiratory injury.

Spatial and temporal distribution of trunk-injected imidacloprid in apple tree canopies.

PubMed

Aćimović, Srđan G; VanWoerkom, Anthony H; Reeb, Pablo D; Vandervoort, Christine; Garavaglia, Thomas; Cregg, Bert M; Wise, John C

2014-11-01

Pesticide use in orchards creates drift-driven pesticide losses which contaminate the environment. Trunk injection of pesticides as a target-precise delivery system could greatly reduce pesticide losses. However, pesticide efficiency after trunk injection is associated with the underinvestigated spatial and temporal distribution of the pesticide within the tree crown. This study quantified the spatial and temporal distribution of trunk-injected imidacloprid within apple crowns after trunk injection using one, two, four or eight injection ports per tree. The spatial uniformity of imidacloprid distribution in apple crowns significantly increased with more injection ports. Four ports allowed uniform spatial distribution of imidacloprid in the crown. Uniform and non-uniform spatial distributions were established early and lasted throughout the experiment. The temporal distribution of imidacloprid was significantly non-uniform. Upper and lower crown positions did not significantly differ in compound concentration. Crown concentration patterns indicated that imidacloprid transport in the trunk occurred through radial diffusion and vertical uptake with a spiral pattern. By showing where and when a trunk-injected compound is distributed in the apple tree canopy, this study addresses a key knowledge gap in terms of explaining the efficiency of the compound in the crown. These findings allow the improvement of target-precise pesticide delivery for more sustainable tree-based agriculture. © 2014 Society of Chemical Industry.

Critical capacity, travel time delays and travel time distribution of rapid mass transit systems

NASA Astrophysics Data System (ADS)

Legara, Erika Fille; Monterola, Christopher; Lee, Kee Khoon; Hung, Gih Guang

2014-07-01

We set up a mechanistic agent-based model of a rapid mass transit system. Using empirical data from Singapore's unidentifiable smart fare card, we validate our model by reconstructing actual travel demand and duration of travel statistics. We subsequently use this model to investigate two phenomena that are known to significantly affect the dynamics within the RTS: (1) overloading in trains and (2) overcrowding in the RTS platform. We demonstrate that by varying the loading capacity of trains, a tipping point emerges at which an exponential increase in the duration of travel time delays is observed. We also probe the impact on the rail system dynamics of three types of passenger growth distribution across stations: (i) Dirac delta, (ii) uniform and (iii) geometric, which is reminiscent of the effect of land use on transport. Under the assumption of a fixed loading capacity, we demonstrate the dependence of a given origin-destination (OD) pair on the flow volume of commuters in station platforms.

Active and passive controls of Jeffrey nanofluid flow over a nonlinear stretching surface

NASA Astrophysics Data System (ADS)

Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Alsaedi, Ahmed

This communication explores magnetohydrodynamic (MHD) boundary-layer flow of Jeffrey nanofluid over a nonlinear stretching surface with active and passive controls of nanoparticles. A nonlinear stretching surface generates the flow. Effects of thermophoresis and Brownian diffusion are considered. Jeffrey fluid is electrically conducted subject to non-uniform magnetic field. Low magnetic Reynolds number and boundary-layer approximations have been considered in mathematical modelling. The phenomena of impulsing the particles away from the surface in combination with non-zero mass flux condition is known as the condition of zero mass flux. Convergent series solutions for the nonlinear governing system are established through optimal homotopy analysis method (OHAM). Graphs have been sketched in order to analyze that how the temperature and concentration distributions are affected by distinct physical flow parameters. Skin friction coefficient and local Nusselt and Sherwood numbers are also computed and analyzed. Our findings show that the temperature and concentration distributions are increasing functions of Hartman number and thermophoresis parameter.

On magnetohydrodynamic flow of second grade nanofluid over a nonlinear stretching sheet

NASA Astrophysics Data System (ADS)

Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Ahmad, Bashir

2016-06-01

This research article addresses the magnetohydrodynamic (MHD) flow of second grade nanofluid over a nonlinear stretching sheet. Heat and mass transfer aspects are investigated through the thermophoresis and Brownian motion effects. Second grade fluid is assumed electrically conducting through a non-uniform applied magnetic field. Mathematical formulation is developed subject to small magnetic Reynolds number and boundary layer assumptions. Newly constructed condition having zero mass flux of nanoparticles at the boundary is incorporated. Transformations have been invoked for the reduction of partial differential systems into the set of nonlinear ordinary differential systems. The governing nonlinear systems have been solved for local behavior. Graphical results of different influential parameters are studied and discussed in detail. Computations for skin friction coefficient and local Nusselt number have been carried out. It is observed that the effects of thermophoresis parameter on the temperature and nanoparticles concentration distributions are qualitatively similar. The temperature and nanoparticles concentration distributions are enhanced for the larger magnetic parameter.

Pore scale study of multiphase multicomponent reactive transport during CO 2 dissolution trapping

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

Chen, Li; Wang, Mengyi; Kang, Qinjun

Solubility trapping is crucial for permanent CO 2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO 2-water two-phase flow, multicomponent (CO 2(aq), H +, HCO 3 –, CO 3 2 – and OH –) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO 2(aq) concentration, scCO 2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is requiredmore » by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Lastly, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO 2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.« less

Pore scale study of multiphase multicomponent reactive transport during CO 2 dissolution trapping

DOE PAGES

Chen, Li; Wang, Mengyi; Kang, Qinjun; ...

2018-04-26

Solubility trapping is crucial for permanent CO 2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO 2-water two-phase flow, multicomponent (CO 2(aq), H +, HCO 3 –, CO 3 2 – and OH –) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO 2(aq) concentration, scCO 2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is requiredmore » by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Lastly, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO 2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.« less

Pore scale study of multiphase multicomponent reactive transport during CO2 dissolution trapping

NASA Astrophysics Data System (ADS)

Chen, Li; Wang, Mengyi; Kang, Qinjun; Tao, Wenquan

2018-06-01

Solubility trapping is crucial for permanent CO2 sequestration in deep saline aquifers. For the first time, a pore-scale numerical method is developed to investigate coupled scCO2-water two-phase flow, multicomponent (CO2(aq), H+, HCO3-, CO32- and OH-) mass transport, heterogeneous interfacial dissolution reaction, and homogeneous dissociation reactions. Pore-scale details of evolutions of multiphase distributions and concentration fields are presented and discussed. Time evolutions of several variables including averaged CO2(aq) concentration, scCO2 saturation, and pH value are analyzed. Specific interfacial length, an important variable which cannot be determined but is required by continuum models, is investigated in detail. Mass transport coefficient or efficient dissolution rate is also evaluated. The pore-scale results show strong non-equilibrium characteristics during solubility trapping due to non-uniform distributions of multiphase as well as slow mass transport process. Complicated coupling mechanisms between multiphase flow, mass transport and chemical reactions are also revealed. Finally, effects of wettability are also studied. The pore-scale studies provide deep understanding of non-linear non-equilibrium multiple physicochemical processes during CO2 solubility trapping processes, and also allow to quantitatively predict some important empirical relationships, such as saturation-interfacial surface area, for continuum models.

Rotational properties of hypermassive neutron stars from binary mergers

NASA Astrophysics Data System (ADS)

Hanauske, Matthias; Takami, Kentaro; Bovard, Luke; Rezzolla, Luciano; Font, José A.; Galeazzi, Filippo; Stöcker, Horst

2017-08-01

Determining the differential-rotation law of compact stellar objects produced in binary neutron stars mergers or core-collapse supernovae is an old problem in relativistic astrophysics. Addressing this problem is important because it impacts directly on the maximum mass these objects can attain and, hence, on the threshold to black-hole formation under realistic conditions. Using the results from a large number of numerical simulations in full general relativity of binary neutron star mergers described with various equations of state and masses, we study the rotational properties of the resulting hypermassive neutron stars. We find that the angular-velocity distribution shows only a modest dependence on the equation of state, thus exhibiting the traits of "quasiuniversality" found in other aspects of compact stars, both isolated and in binary systems. The distributions are characterized by an almost uniformly rotating core and a "disk." Such a configuration is significantly different from the j -constant differential-rotation law that is commonly adopted in equilibrium models of differentially rotating stars. Furthermore, the rest-mass contained in such a disk can be quite large, ranging from ≃0.03 M⊙ in the case of high-mass binaries with stiff equations of state, up to ≃0.2 M⊙ for low-mass binaries with soft equations of state. We comment on the astrophysical implications of our findings and on the long-term evolutionary scenarios that can be conjectured on the basis of our simulations.

HEAT TRANSFER FROM SURFACES OF NON-UNIFORM TEMPERATURE DISTRIBUTION. PART II. TURBULENT TRANSFER FROM ISOTHERMAL SPANWISE STRIPS ON A FLAT PLATE

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

Sogin, H.H.; Goldstein, R.J.

1960-02-01

Experiments were performed on mass transfer by forced convection from naphthalene strips on a flat plate to an air stream at ordinary temperature and pressure. Turbulence was induced in the boundary layer by means of a wire strip. In all cases there was a hydrodynamic starting length upstream of the strips. The ratio of this inert length to the total length was varied from about 0.80 to 0.96. The flow was practically incompressible with Reynolds number, based on the total length, varying from 175,000 to 486,000. The Schmidt number was 2.5. The experimental results fell in proximity to the Sebanmore » step function factor when they were reduced after the massmomentum analysis of Deissler and Loeffler for a surface of uniform vapor pressure. When Karman's formulation of the mass- momentum analogy was assumed, the data fell between the values predicted by the Seban and by the Rubesin expression for the step function factor. The results were well correlated by the Colburn analogy in conjunction with the Rubesin step function factor. (auth)« less

Investigation the evaporation-condensation problem by means of the joint numerical solution of the Boltzmann kinetic equation and interface modelling

NASA Astrophysics Data System (ADS)

Shiskova, I. N.; Kryukov, A. P.; Levashov, V. Yu

2017-11-01

The paper is devoted to research of the heat and mass transfer processes in liquid and vapor phase on the basis of the uniform approach assuming the through description of liquid, interface and vapor. Multiparticles interactions in liquid will be taken into account. The problem is studied when temperature in the depth of liquid differs from temperature in the vapor region. In this case there are both mass flux and heat flux. The study of influence of the correlations resulting from interactions of molecules set in thin near-surface liquid layers and an interface on intensity of evaporation is made. As a result of calculations the equilibrium line of the liquid-vapor saturation is obtained, which corresponds good enough with experimental data. Distributions of density, temperature, pressure, heat and mass fluxes, both in a liquid and in vapor are also presented.

The Morphology and Uniformity of Circumstellar OH/H2O Masers around OH/IR Stars

NASA Astrophysics Data System (ADS)

Felli, Derek Sean

Even though low mass stars ( 8 solar masses), the more massive stars drive the chemical evolution of galaxies from which the next generation of stars and planets can form. Understanding mass loss of asymptotic giant branch stars contributes to our understanding of the chemical evolution of the galaxy, stellar populations, and star formation history. Stars with mass 8 solar masses go supernova. In both cases, these stars enrich their environments with elements heavier than simple hydrogen and helium molecules. While some general info about how stars die and form planetary nebulae are known, specific details are missing due to a lack of high-resolution observations and analysis of the intermediate stages. For example, we know that mass loss in stars creates morphologically diverse planetary nebulae, but we do not know the uniformity of these processes, and therefore lack detailed models to better predict how spherically symmetric stars form asymmetric nebulae. We have selected a specific group of late-stage stars and observed them at different scales to reveal the uniformity of mass loss through different layers close to the star. This includes observing nearby masers that trace the molecular shell structure around these stars. This study revealed detailed structure that was analyzed for uniformity to place constraints on how the mass loss processes behave in models. These results will feed into our ability to create more detailed models to better predict the chemical evolution of the next generation of stars and planets.

The Global and Radial Stellar Mass Assembly of Milky Way-sized Galaxies

NASA Astrophysics Data System (ADS)

Avila-Reese, Vladimir; González-Samaniego, Alejandro; Colín, Pedro; Ibarra-Medel, Héctor; Rodríguez-Puebla, Aldo

2018-02-01

We study the global and radial stellar mass assembly of eight zoomed-in Milky Way (MW)-sized galaxies produced in hydrodynamics cosmological simulations. The disk-dominated galaxies (four) show a fast initial stellar mass growth in the innermost parts, driven mostly by in situ star formation (SF), but since z ∼ 2‑1, the SF has entered a long-term quenching phase. The outer regions follow this trend but more gently, as they are more external. As a result, the radial stellar mass growth is highly inside-out due to both inside-out structural growth and inside-out SF quenching. The half-mass radius evolves fast; for instance, {R}0.5(z = 1) < 0.5 {R}0.5 (z = 0). Two other runs resemble lenticular galaxies. One also shows a pronounced inside-out growth, and the other one presents a nearly uniform radial mass assembly. The other two galaxies suffered late major mergers. Their normalized radial mass growth histories (MGHs) are very close, but with periods of outside-in assembly during or after the mergers. For all of the simulations, the archaeological radial MGHs calculated from the z = 0 stellar particle age distribution are similar to current MGHs, which shows that the mass assembly by ex situ stars and the radial mass transport do not significantly change their radial mass distributions. Our results agree qualitatively with observational inferences from the fossil record method applied to a survey of local galaxies and from look-back observations of progenitors of MW-sized galaxies. However, the inside-out growth mode is more pronounced, and the {R}0.5 growth is faster in simulations than in observational inferences.

Effects of beam irregularity on uniform scanning

NASA Astrophysics Data System (ADS)

Kim, Chang Hyeuk; Jang, Sea duk; Yang, Tae-Keun

2016-09-01

An active scanning beam delivery method has many advantages in particle beam applications. For the beam is to be successfully delivered to the target volume by using the active scanning technique, the dose uniformity must be considered and should be at least 2.5% in the case of therapy application. During beam irradiation, many beam parameters affect the 2-dimensional uniformity at the target layer. A basic assumption in the beam irradiation planning stage is that the shape of the beam is symmetric and follows a Gaussian distribution. In this study, a pure Gaussian-shaped beam distribution was distorted by adding parasitic Gaussian distribution. An appropriate uniform scanning condition was deduced by using a quantitative analysis based on the gamma value of the distorted beam and 2-dimensional uniformities.

Rapid Analysis of the Size Distribution of Metal-Containing Aerosol

PubMed Central

Park, Jae Hong; Mudunkotuwa, Imali A.; Crawford, Kathryn J.; Anthony, T. Renée; Grassian, Vicki H.; Peters, Thomas M.

2017-01-01

Conventional methods to measure the metallic content of particles by size are time consuming and expensive, requiring collection of particles with a cascade impactor and subsequent metals analysis by inductively coupled plasma mass spectrometry (ICP-MS). In this work, we describe a rapid way to measure the size distribution of metal-containing particles from 10 nm to 20 μm, using a nano micro-orifice uniform-deposit impactor (nano-MOUDI) to size-selective and collect particles that are then analyzed with a field portable X-ray fluorescence (FP-XRF) to determine metal composition and concentration. The nano-MOUDI was used to sample a stainless-steel aerosol produced by a spark discharge system. The particle-laden substrates were then analyzed directly with FP-XRF and then with ICP-MS. Results from FP-XRF were linearly correlated with results from ICP-MS (R2 = 0.91 for Fe and R2 = 0.84 for Cr). Although the FP-XRF was unable to detect Fe particles at mass per substrate loadings less than 2.5 μg effectively, it produced results similar to those using the ICP-MS at a mass per substrate loading greater than 2.5 μg. PMID:28871214

Structural Configuration Analysis of Crew Exploration Vehicle Concepts

NASA Technical Reports Server (NTRS)

Mukhopadhyay, V.

2006-01-01

Structural configuration modeling and finite element analysis of crew exploration vehicle (CEV) concepts are presented. In the structural configuration design approach, parametric solid models of the pressurized shell and tanks are developed. The CEV internal cabin pressure is same as in the International Space Station (ISS) to enable docking with the ISS without an intermediate airlock. Effects of this internal pressure load on the stress distribution, factor of safety, mass and deflections are investigated. Uniform 7 mm thick skin shell, 5 mm thick shell with ribs and frames, and isogrid skin construction options are investigated. From this limited study, the isogrid construction appears to provide most strength/mass ratio. Initial finite element analysis results on the service module tanks are also presented. These rapid finite element analyses, stress and factor of safety distribution results are presented as a part of lessons learned and to build up a structural mass estimation and sizing database for future technology support. This rapid structural analysis process may also facilitate better definition of the vehicles and components for rapid prototyping. However, these structural analysis results are highly conceptual and exploratory in nature and do not reflect current configuration designs being conducted at the program level by NASA and industry.

Urban mass transportation industry uniform system of accounts and records and reporting system. Volume I. General description.

DOT National Transportation Integrated Search

1977-01-10

The purpose of the report is to present and document the detailed features of the uniform system of accounts and records and reporting system required by Section 15 of the Urban Mass Transportation Act of 1964, as amended. This report is presented in...

Urban mass transportation industry uniform system of accounts and records and reporting system. Volume III. Reporting system forms and instructions--required.

DOT National Transportation Integrated Search

1977-01-10

The purpose of the report is to present and document the detailed features of the uniform system of accounts and records and reporting system required by Section 15 of the Urban Mass Transportation Act of 1964, as amended. Volume 3 contains illustrat...

Distribution of a viscous binder during high shear granulation--sensitivity to the method of delivery and its impact on product properties.

PubMed

Tan, Bernice Mei Jin; Loh, Zhi Hui; Soh, Josephine Lay Peng; Liew, Celine Valeria; Heng, Paul Wan Sia

2014-01-02

Binder distribution in the powder mass during high shear granulation is especially critical with the use of viscous liquid binders and with short processing times. A viscous liquid binder was delivered into the powder mass at two flow rates using three methods: pouring, pumping and spraying from a pressure pot. Binder content analyses at the scale of individual granules were conducted to investigate the impact of different delivery conditions on the homogeneity of binder distribution. There was clear evidence of non-uniformity of binder content among individual granules across all delivery conditions, particularly for the fast rates of delivery. Poorer reproducibility values of tablet thickness and disintegration time were observed when binder was poured but this may be overcome by pumping or spraying from the pressure pot. Greater homogeneity of binder distribution occurred with the slow rates of delivery and led to the earlier onset of granule growth and a consequent increase in granule size. Larger granule size and lower proportion of fines were in turn associated with increased granule bulk density and improvement of granule flow. In conclusion, delivery of a viscous binder at a slow rate either by pumping or via a pressure pot was most desirable during granulation. Copyright © 2013 Elsevier B.V. All rights reserved.

Evaluation of dripper clogging using magnetic water in drip irrigation

NASA Astrophysics Data System (ADS)

Khoshravesh, Mojtaba; Mirzaei, Sayyed Mohammad Javad; Shirazi, Pooya; Valashedi, Reza Norooz

2018-06-01

This study was performed to investigate the uniformity of distribution of water and discharge variations in drip irrigation using magnetic water. Magnetic water was achieved by transition of water using a robust permanent magnet connected to a feed pipeline. Two main factors including magnetic and non-magnetic water and three sub-factor of salt concentration including well water, addition of 150 and 300 mg L-1 calcium carbonate to irrigation water with three replications were applied. The result of magnetic water on average dripper discharge was significant at ( P ≤ 0.05). At the final irrigation, the average dripper discharge and distribution uniformity were higher for the magnetic water compared to the non-magnetic water. The magnetic water showed a significant effect ( P ≤ 0.01) on distribution uniformity of drippers. At the first irrigation, the water distribution uniformity was almost the same for both the magnetic water and the non-magnetic water. The use of magnetic water for drip irrigation is recommended to achieve higher uniformity.

The International Deep Planet Survey. II. The frequency of directly imaged giant exoplanets with stellar mass

NASA Astrophysics Data System (ADS)

Galicher, R.; Marois, C.; Macintosh, B.; Zuckerman, B.; Barman, T.; Konopacky, Q.; Song, I.; Patience, J.; Lafrenière, D.; Doyon, R.; Nielsen, E. L.

2016-10-01

Context. Radial velocity and transit methods are effective for the study of short orbital period exoplanets but they hardly probe objects at large separations for which direct imaging can be used. Aims: We carried out the international deep planet survey of 292 young nearby stars to search for giant exoplanets and determine their frequency. Methods: We developed a pipeline for a uniform processing of all the data that we have recorded with NIRC2/Keck II, NIRI/Gemini North, NICI/Gemini South, and NACO/VLT for 14 yr. The pipeline first applies cosmetic corrections and then reduces the speckle intensity to enhance the contrast in the images. Results: The main result of the international deep planet survey is the discovery of the HR 8799 exoplanets. We also detected 59 visual multiple systems including 16 new binary stars and 2 new triple stellar systems, as well as 2279 point-like sources. We used Monte Carlo simulations and the Bayesian theorem to determine that 1.05+2.80-0.70% of stars harbor at least one giant planet between 0.5 and 14 MJ and between 20 and 300 AU. This result is obtained assuming uniform distributions of planet masses and semi-major axes. If we consider power law distributions as measured for close-in planets instead, the derived frequency is 2.30+5.95-1.55%, recalling the strong impact of assumptions on Monte Carlo output distributions. We also find no evidence that the derived frequency depends on the mass of the hosting star, whereas it does for close-in planets. Conclusions: The international deep planet survey provides a database of confirmed background sources that may be useful for other exoplanet direct imaging surveys. It also puts new constraints on the number of stars with at least one giant planet reducing by a factor of two the frequencies derived by almost all previous works. Tables 11-15 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/594/A63

Simulation of angular and energy distributions of the PTB beta secondary standard.

PubMed

Faw, R E; Simons, G G; Gianakon, T A; Bayouth, J E

1990-09-01

Calculations and measurements have been performed to assess radiation doses delivered by the PTB Secondary Standard that employs 147Pm, 204Tl, and 90Sr:90Y sources in prescribed geometries, and features "beam-flattening" filters to assure uniformity of delivered doses within a 5-cm radius of the axis from source to detector plane. Three-dimensional, coupled, electron-photon Monte Carlo calculations, accounting for transmission through the source encapsulation and backscattering from the source mounting, led to energy spectra and angular distributions of electrons penetrating the source encapsulation that were used in the representation of pseudo sources of electrons for subsequent transport through the atmosphere, filters, and detectors. Calculations were supplemented by measurements made using bare LiF TLD chips on a thick polymethyl methacrylate phantom. Measurements using the 204Tl and 90Sr:90Y sources revealed that, even in the absence of the beam-flattening filters, delivered dose rates were very uniform radially. Dosimeter response functions (TLD:skin dose ratios) were calculated and confirmed experimentally for all three beta-particle sources and for bare LiF TLDs ranging in mass thickness from 10 to 235 mg cm-2.

Microphysics of mass-transport in coupled droplet-pairs at low Reynolds number and the role of convective dynamics

NASA Astrophysics Data System (ADS)

Dong, Qingming; Sau, Amalendu

2016-06-01

Interfacial mass-transport and redistribution in the micro-scale liquid droplets are important in diverse fields of research interest. The role of the "inflow" and the "outflow" type convective eddy-pairs in the entrainment of outer solute and internal relocation are examined for different homogeneous and heterogeneous water droplet pairs appearing in a tandem arrangement. Two micro-droplets of pure (rain) water interact with an oncoming outer air stream (Re ≤ 100) contaminated by uniformly distributed SO2. By virtue of separation/attachment induced non-uniform interfacial shear-stress gradient, the well-defined inflow/outflow type pairs of recirculating eddy-based convective motion quickly develops, and the eddies effectively attract/repel the accumulated outer solute and control the physical process of mass-transport in the droplet-pair. The non-uniformly shear-driven flow interaction and bifurcation of the circulatory internal flow lead to growth of important micro-scale "secondary" eddies which suitably regroup with the adjacent "primary" one to create the sustained inflow/outflow type convective dynamics. The presently derived flow characteristics and in-depth analysis help to significantly improve our understanding of the micro-droplet based transport phenomena in a wider context. By tuning "Re" (defined in terms of the droplet diameter and the average oncoming velocity of the outer air) and gap-ratio "α," the internal convective forcing and the solute entrainment efficiency could be considerably enhanced. The quantitative estimates for mass entrainment, convective strength, and saturation characteristics for different coupled micro-droplet pairs are extensively examined here for 0.2 ≤ α ≤ 2.0 and 30 ≤ Re ≤ 100. Interestingly, for the compound droplets, with suitably tuned radius-ratio "B" (of upstream droplet with respect to downstream one) the generated "inflow" type coherent convective dynamics helped to significantly augment the centre-line mass flow, which in turn facilitate faster saturation of the upstream droplet. However, for heterogeneous droplet-pairs containing solid nucleus, while increased solid-fraction "S" (the ratio between the radius of the solid nucleus and that of the droplet) through 0.25 ≤ S ≤ 0.45 caused gradual reductions of convective strength and mass absorption rate (RSO2) for the upstream droplet, beyond a critical value S ≥ 0.45 the RSO2 therein continued to rise again owing to the reduced film thickness.

National mass care strategy: a national integrated approach.

PubMed

Mintz, Amy; Gonzalez, Waddy

2013-01-01

Mass care refers to a wide range of humanitarian activities that collectively provide life- sustaining services, such as emergency sheltering, feeding, reunification, distribution of emergency supplies and recovery information, before or in the aftermath of an emergency or disaster. Most services are coordinated and provided by non-governmental organisations and/or local government. Based on the lessons learned in the aftermath of Hurricanes Katrina and Rita in 2005, the American Red Cross, the Federal Emergency Management Agency and the National Voluntary Organizations Active in Disasters joined efforts to expand national mass care capabilities in order to support survivors in the wake of catastrophic events, as well as to enhance the integration of volunteers and non-governmental organisations into the broader national effort. These efforts resulted in the creation of the National Mass Care Council in 2010, with representatives of Federal and State agencies, voluntary organisations and the private sector working together to develop a unified approach to mass care and to ensure the provision of consistent and uniform services across the USA, regardless of the magnitude of the event.

Exponential Thurston maps and limits of quadratic differentials

NASA Astrophysics Data System (ADS)

Hubbard, John; Schleicher, Dierk; Shishikura, Mitsuhiro

2009-01-01

We give a topological characterization of postsingularly finite topological exponential maps, i.e., universal covers g\\colon{C}to{C}setminus\\{0\\} such that 0 has a finite orbit. Such a map either is Thurston equivalent to a unique holomorphic exponential map λ e^z or it has a topological obstruction called a degenerate Levy cycle. This is the first analog of Thurston's topological characterization theorem of rational maps, as published by Douady and Hubbard, for the case of infinite degree. One main tool is a theorem about the distribution of mass of an integrable quadratic differential with a given number of poles, providing an almost compact space of models for the entire mass of quadratic differentials. This theorem is given for arbitrary Riemann surfaces of finite type in a uniform way.

Analysis of incident-energy dependence of delayed neutron yields in actinides

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

Nasir, Mohamad Nasrun bin Mohd, E-mail: monasr211@gmail.com; Metorima, Kouhei, E-mail: kohei.m2420@hotmail.co.jp; Ohsawa, Takaaki, E-mail: ohsawa@mvg.biglobe.ne.jp

The changes of delayed neutron yields (ν{sub d}) of Actinides have been analyzed for incident energy up to 20MeV using realized data of precursor after prompt neutron emission, from semi-empirical model, and delayed neutron emission probability data (P{sub n}) to carry out a summation method. The evaluated nuclear data of the delayed neutron yields of actinide nuclides are still uncertain at the present and the cause of the energy dependence has not been fully understood. In this study, the fission yields of precursor were calculated considering the change of the fission fragment mass yield based on the superposition of fivesmore » Gaussian distribution; and the change of the prompt neutrons number associated with the incident energy dependence. Thus, the incident energy dependent behavior of delayed neutron was analyzed.The total number of delayed neutron is expressed as ν{sub d}=∑Y{sub i} • P{sub ni} in the summation method, where Y{sub i} is the mass yields of precursor i and P{sub ni} is the delayed neutron emission probability of precursor i. The value of Y{sub i} is derived from calculation of post neutron emission mass distribution using 5 Gaussian equations with the consideration of large distribution of the fission fragments. The prompt neutron emission ν{sub p} increases at higher incident-energy but there are two different models; one model says that the fission fragment mass dependence that prompt neutron emission increases uniformly regardless of the fission fragments mass; and the other says that the major increases occur at heavy fission fragments area. In this study, the changes of delayed neutron yields by the two models have been investigated.« less

Evolution of Welding-Fume Aerosols with Time and Distance from the Source: A study was conducted on the spatiotemporal variability in welding-fume concentrations for the characterization of first- and second-hand exposure to welding fumes.

PubMed

Cena, L G; Chen, B T; Keane, M J

2016-08-01

Gas metal arc welding fumes were generated from mild-steel plates and measured near the arc (30 cm), representing first-hand exposure of the welder, and farther away from the source (200 cm), representing second-hand exposure of adjacent workers. Measurements were taken during 1-min welding runs and at subsequent 5-min intervals after the welding process was stopped. Number size distributions were measured in real time. Particle mass distributions were measured using a micro-orifice uniform deposition impactor, and total mass concentrations were measured with polytetrafluorothylene filters. Membrane filters were used for collecting morphology samples for electron microscopy. Average mass concentrations measured near the arc were 45 mg/m 3 and 9 mg/m 3 at the farther distance. The discrepancy in concentrations at the two distances was attributed to the presence of spatter particles, which were observed only in the morphology samples near the source. As fumes aged over time, mass concentrations at the farther distance decreased by 31% (6.2 mg/m 3 ) after 5 min and an additional 13% (5.4 mg/m 3 ) after 10 min. Particle number and mass distributions during active welding were similar at both distances, indicating similar exposure patterns for welders and adjacent workers. Exceptions were recorded for particles smaller than 50 nm and larger than 3 μm, where concentrations were higher near the arc, indicating higher exposures of welders. These results were confirmed by microscopy analysis. As residence time increased, number concentrations decreased dramatically. In terms of particle number concentrations, second-hand exposures to welding fumes during active welding may be as high as first-hand exposures.

Urban mass transportation industry uniform system of accounts and records and reporting system. Volume IV. Reporting system forms and instructions - voluntary.

DOT National Transportation Integrated Search

1977-01-10

The purpose of the report is to present and document the detailed features of the uniform system of accounts and records and reporting system required by Section 15 of the Urban Mass Transportation Act of 1964, as amended. This report is presented in...

Demonstration of UV LED versatility when paired with molded UV transmitting glass optics to produce unique irradiance patterns

NASA Astrophysics Data System (ADS)

Jasenak, Brian

2017-02-01

Ultraviolet light-emitting diode (UV LED) adoption is accelerating; they are being used in new applications such as UV curing, germicidal irradiation, nondestructive testing, and forensic analysis. In many of these applications, it is critically important to produce a uniform light distribution and consistent surface irradiance. Flat panes of fused quartz, silica, or glass are commonly used to cover and protect UV LED arrays. However, they don't offer the advantages of an optical lens design. An investigation was conducted to determine the effect of a secondary glass optic on the uniformity of the light distribution and irradiance. Glass optics capable of transmitting UV-A, UV-B, and UV-C wavelengths can improve light distribution, uniformity, and intensity. In this work, two simulation studies were created to illustrate distinct irradiance patterns desirable for potential real world applications. The first study investigates the use of a multi-UV LED array and optic to create a uniform irradiance pattern on the flat two dimensional (2D) target surface. The uniformity was improved by designing both the LED array and molded optic to produce a homogenous pattern. The second study investigated the use of an LED light source and molded optic to improve the light uniformity on the inside of a canister. The case study illustrates the requirements for careful selection of LED based on light distribution and subsequent design of optics. The optic utilizes total internal reflection to create optimized light distribution. The combination of the LED and molded optic showed significant improvement in uniformity on the inner surface of the canister. The simulations illustrate how the application of optics can significantly improve UV light distribution which can be critical in applications such as UV curing and sterilization.

Probing Cloud-Driven Variability on Two of the Youngest, Lowest-Mass Brown Dwarfs in the Solar Neighborhood

NASA Astrophysics Data System (ADS)

Schneider, Adam; Cushing, Michael; Kirkpatrick, J. Davy

2016-08-01

Young, late-type brown dwarfs share many properties with directly imaged giant extrasolar planets. They therefore provide unique testbeds for investigating the physical conditions present in this critical temperature and mass regime. WISEA 1147-2040 and 2MASS 1119-1137, two recently discovered late-type (~L7) brown dwarfs, have both been determined to be members of the ~10 Myr old TW Hya Association (Kellogg et al. 2016, Schneider et al. 2016). Each has an estimated mass of 5-6 MJup, making them two of the youngest and lowest-mass free floating objects yet found in the solar neighborhood. As such, these two planetary mass objects provide unparalleled laboratories for investigating giant planet-like atmospheres far from the contaminating starlight of a host sun. Condensate clouds play a critical role in shaping the emergent spectra of both brown dwarfs and gas giant planets, and can cause photometric variability via their non-uniform spatial distribution. We propose to photometrically monitor WISEA 1147-2040 and 2MASS 1119-1137 in order to search for the presence of cloud-driven variability to 1) investigate the potential trend of low surface gravity with high-amplitude variability in a previously unexplored mass regime and 2) explore the angular momentum evolution of isolated planetary mass objects.

Flow field design and optimization based on the mass transport polarization regulation in a flow-through type vanadium flow battery

NASA Astrophysics Data System (ADS)

Zheng, Qiong; Xing, Feng; Li, Xianfeng; Ning, Guiling; Zhang, Huamin

2016-08-01

Vanadium flow battery holds great promise for use in large scale energy storage applications. However, the power density is relatively low, leading to significant increase in the system cost. Apart from the kinetic and electronic conductivity improvement, the mass transport enhancement is also necessary to further increase the power density and reduce the system cost. To better understand the mass transport limitations, in the research, the space-varying and time-varying characteristic of the mass transport polarization is investigated based on the analysis of the flow velocity and reactant concentration in the bulk electrolyte by modeling. The result demonstrates that the varying characteristic of mass transport polarization is more obvious at high SoC or high current densities. To soften the adverse impact of the mass transport polarization, a new rectangular plug flow battery with a plug flow and short flow path is designed and optimized based on the mass transport polarization regulation (reducing the mass transport polarization and improving its uniformity of distribution). The regulation strategy of mass transport polarization is practical for the performance improvement in VFBs, especially for high power density VFBs. The findings in the research are also applicable for other flow batteries and instructive for practical use.

Ultra-thin carbon-fiber paper fabrication and carbon-fiber distribution homogeneity evaluation method

NASA Astrophysics Data System (ADS)

Zhang, L. F.; Chen, D. Y.; Wang, Q.; Li, H.; Zhao, Z. G.

2018-01-01

A preparation technology of ultra-thin Carbon-fiber paper is reported. Carbon fiber distribution homogeneity has a great influence on the properties of ultra-thin Carbon-fiber paper. In this paper, a self-developed homogeneity analysis system is introduced to assist users to evaluate the distribution homogeneity of Carbon fiber among two or more two-value images of carbon-fiber paper. A relative-uniformity factor W/H is introduced. The experimental results show that the smaller the W/H factor, the higher uniformity of the distribution of Carbon fiber is. The new uniformity-evaluation method provides a practical and reliable tool for analyzing homogeneity of materials.

A CAD Approach to Developing Mass Distribution and Composition Models for Spaceflight Radiation Risk Analyses

NASA Astrophysics Data System (ADS)

Zapp, E.; Shelfer, T.; Semones, E.; Johnson, A.; Weyland, M.; Golightly, M.; Smith, G.; Dardano, C.

For roughly the past three decades, combinatorial geometries have been the predominant mode for the development of mass distribution models associated with the estimation of radiological risk for manned space flight. Examples of these are the MEVDP (Modified Elemental Volume Dose Program) vehicle representation of Liley and Hamilton, and the quadratic functional representation of the CAM/CAF (Computerized Anatomical Male/Female) human body models as modified by Billings and Yucker. These geometries, have the advantageous characteristics of being simple for a familiarized user to maintain, and because of the relative lack of any operating system or run-time library dependence, they are also easy to transfer from one computing platform to another. Unfortunately they are also limited in the amount of modeling detail possible, owing to the abstract geometric representation. In addition, combinatorial representations are also known to be error-prone in practice, since there is no convenient method for error identification (i.e. overlap, etc.), and extensive calculation and/or manual comparison may is often necessary to demonstrate that the geometry is adequately represented. We present an alternate approach linking materials -specific, CAD-based mass models directly to geometric analysis tools requiring no approximation with respect to materials , nor any meshing (i.e. tessellation) of the representative geometry. A new approach to ray tracing is presented which makes use of the fundamentals of the CAD representation to perform geometric analysis directly on the NURBS (Non-Uniform Rational BSpline) surfaces themselves. In this way we achieve a framework for- the rapid, precise development and analysis of materials-specific mass distribution models.

Scale Mixture Models with Applications to Bayesian Inference

NASA Astrophysics Data System (ADS)

Qin, Zhaohui S.; Damien, Paul; Walker, Stephen

2003-11-01

Scale mixtures of uniform distributions are used to model non-normal data in time series and econometrics in a Bayesian framework. Heteroscedastic and skewed data models are also tackled using scale mixture of uniform distributions.

Effects of physical and chemical heterogeneity on water-quality samples obtained from wells

USGS Publications Warehouse

Reilly, Thomas E.; Gibs, Jacob

1993-01-01

Factors that affect the mass of chemical constituents entering a well include the distributions of flow rate and chemical concentrations along and near the screened or open section of the well. Assuming a layered porous medium (with each layer being characterized by a uniform hydraulic conductivity and chemical concentration), a knowledge of the flow from each layer along the screened zone and of the chemical concentrations in each layer enables the total mass entering the well to be determined. Analyses of hypothetical systems and a site at Galloway, NJ, provide insight into the temporal variation of water-quality data observed when withdrawing water from screened wells in heterogeneous ground-water systems.The analyses of hypothetical systems quantitatively indicate the cause-and-effect relations that cause temporal variability in water samples obtained from wells. Chemical constituents that have relatively uniform concentrations with depth may not show variations in concentrations in the water discharged from a well after the well is purged (evacuation of standing water in the well casing). However, chemical constituents that do not have uniform concentrations near the screened interval of the well may show variations in concentrations in the well discharge water after purging because of the physics of ground-water flow in the vicinity of the screen.Water-quality samples were obtained through time over a 30 minute period from a site at Galloway, NJ. The water samples were analyzed for aromatic hydrocarbons, and the data for benzene, toluene, and meta+para xylene were evaluated for temporal variations. Samples were taken from seven discrete zones, and the flow-weighted concentrations of benzene, toluene, and meta+para xylene all indicate an increase in concentration over time during pumping. These observed trends in time were reproduced numerically based on the estimated concentration distribution in the aquifer and the flow rates from each zone.The results of the hypothetical numerical experiments and the analysis of the field data both corroborate the impact of physical and chemical heterogeneity in the aquifer on water-quality samples obtained from wells. If temporal variations in concentrations of chemical constituents are observed, they may indicate variability in the ground-water system being sampled, which may give insight into the chemical distributions within the aquifer and provide guidance in the positioning of new sampling devices or wells.

Experimental and numerical studies of micro PEM fuel cell

NASA Astrophysics Data System (ADS)

Peng, Rong-Gui; Chung, Chen-Chung; Chen, Chiun-Hsun

2011-10-01

A single micro proton exchange membrane fuel cell (PEMFC) has been produced using Micro-electromechanical systems (MEMS) technology with the active area of 2.5 cm2 and channel depth of about 500 µm. A theoretical analysis is performed in this study for a novel MEMS-based design of amicro PEMFC. Themodel consists of the conservation equations of mass, momentum, species and electric current in a fully integrated finite-volume solver using the CFD-ACE+ commercial code. The polarization curves of simulation are well correlated with experimental data. Three-dimensional simulations are carried out to treat prediction and analysis of micro PEMFC temperature, current density and water distributions in two different fuel flow rates (15 cm3/min and 40 cm3/min). Simulation results show that temperature distribution within the micro PEMFC is affected by water distribution in the membrane and indicate that low and uniform temperature distribution in the membrane at low fuel flow rates leads to increased membrane water distribution and obtains superior micro PEMFC current density distribution under 0.4V operating voltage. Model predictions are well within those known for experimental mechanism phenomena.

The distribution of physiotherapists in ontario: understanding the market drivers.

PubMed

Holyoke, Paul; Verrier, Molly C; Landry, Michel D; Deber, Raisa B

2012-01-01

To understand the factors that affect the distribution of physiotherapists in Ontario by examining three potential influences in the multi-payer physiotherapy (PT) market: population need, critical mass (related to academic health science centres [AHSCs]), and market forces. Physiotherapist density and distribution were calculated from 2003 and 2005 College of Physiotherapists of Ontario registration data. Physiotherapists' workplaces were classified as not-for-profit (NFP) hospitals, other NFP, or for-profit (FP), and their locations were classified by census division (CD) types (cities and counties). Physiotherapist density varied significantly and distribution was neither uniformly responsive to population need, nor driven primarily by market forces. The largest factor was an AHSC in a CD; physiotherapists locate disproportionately in NFP hospitals in AHSCs rather than in the growing FP sector. While some patterns can be discerned in the distribution and densities of physiotherapists across Ontario, further work needs to be done to identify why population need and market forces appear to be less influential, and why CDs with AHSCs are so attractive to physiotherapists. With this additional information, it may be possible to identify ways to influence uneven distribution in the future.

Design and simulation of novel flow field plate geometry for proton exchange membrane fuel cells

NASA Astrophysics Data System (ADS)

Ruan, Hanxia; Wu, Chaoqun; Liu, Shuliang; Chen, Tao

2016-10-01

Bipolar plate is one of the many important components of proton exchange membrane fuel cell (PEMFC) stacks as it supplies fuel and oxidant to the membrane-electrode assembly (MEA), removes water, collects produced current and provides mechanical support for the single cells in the stack. The flow field design of a bipolar plate greatly affects the performance of a PEMFC. It must uniformly distribute the reactant gases over the MEA and prevent product water flooding. This paper aims at improving the fuel cell performance by optimizing flow field designs and flow channel configurations. To achieve this, a novel biomimetic flow channel for flow field designs is proposed based on Murray's Law. Computational fluid dynamics based simulations were performed to compare three different designs (parallel, serpentine and biomimetic channel, respectively) in terms of current density distribution, power density distribution, pressure distribution, temperature distribution, and hydrogen mass fraction distribution. It was found that flow field designs with biomimetic flow channel perform better than that with convectional flow channel under the same operating conditions.

A comparison of intensity modulated x-ray therapy to intensity modulated proton therapy for the delivery of non-uniform dose distributions

NASA Astrophysics Data System (ADS)

Flynn, Ryan

2007-12-01

The distribution of biological characteristics such as clonogen density, proliferation, and hypoxia throughout tumors is generally non-uniform, therefore it follows that the optimal dose prescriptions should also be non-uniform and tumor-specific. Advances in intensity modulated x-ray therapy (IMXT) technology have made the delivery of custom-made non-uniform dose distributions possible in practice. Intensity modulated proton therapy (IMPT) has the potential to deliver non-uniform dose distributions as well, while significantly reducing normal tissue and organ at risk dose relative to IMXT. In this work, a specialized treatment planning system was developed for the purpose of optimizing and comparing biologically based IMXT and IMPT plans. The IMXT systems of step-and-shoot (IMXT-SAS) and helical tomotherapy (IMXT-HT) and the IMPT systems of intensity modulated spot scanning (IMPT-SS) and distal gradient tracking (IMPT-DGT), were simulated. A thorough phantom study was conducted in which several subvolumes, which were contained within a base tumor region, were boosted or avoided with IMXT and IMPT. Different boosting situations were simulated by varying the size, proximity, and the doses prescribed to the subvolumes, and the size of the phantom. IMXT and IMPT were also compared for a whole brain radiation therapy (WBRT) case, in which a brain metastasis was simultaneously boosted and the hippocampus was avoided. Finally, IMXT and IMPT dose distributions were compared for the case of non-uniform dose prescription in a head and neck cancer patient that was based on PET imaging with the Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone (Cu-ATSM) hypoxia marker. The non-uniform dose distributions within the tumor region were comparable for IMXT and IMPT. IMPT, however, was capable of delivering the same non-uniform dose distributions within a tumor using a 180° arc as for a full 360° rotation, which resulted in the reduction of normal tissue integral dose by a factor of up to three relative to IMXT, and the complete sparing of organs at risk distal to the tumor region.

An evaluation of surface micro- and mesoplastic pollution in pelagic ecosystems of the Western Mediterranean Sea.

PubMed

Faure, Florian; Saini, Camille; Potter, Gaël; Galgani, François; de Alencastro, Luiz Felippe; Hagmann, Pascal

2015-08-01

This study examines the distribution, abundance and characteristics of surface micro- and mesoplastic debris in the Western Mediterranean Sea. 41 samples were collected in 2011 (summer) and 2012 (summer). Results, firstly, revealed that micro- (<5 mm) and mesoplastic debris were widely and uniformly distributed in this area with average concentrations of 130,000 parts/km(2) and 5700 parts/km(2), respectively. Importantly, a strong correlation between micro- and mesoplastic concentrations was identified. Secondly, a classification based on the shape and appearance of microplastics indicated the predominant presence of fragments (73%) followed by thin films (14%). Thirdly, the average mass ratio of microplastic to dry organic matter has been measured at 0.5, revealing a significant presence of microplastics in comparison to plankton. Finally, a correction method was applied in order to correct wind mixing effect on microplastics' vertical distribution. This data allows for a comprehensive view, for the first time, of the spatial distribution and nature of plastic debris in the Western Mediterranean Sea.

Applications of Bayesian Statistics to Problems in Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Meegan, Charles A.

1997-01-01

This presentation will describe two applications of Bayesian statistics to Gamma Ray Bursts (GRBS). The first attempts to quantify the evidence for a cosmological versus galactic origin of GRBs using only the observations of the dipole and quadrupole moments of the angular distribution of bursts. The cosmological hypothesis predicts isotropy, while the galactic hypothesis is assumed to produce a uniform probability distribution over positive values for these moments. The observed isotropic distribution indicates that the Bayes factor for the cosmological hypothesis over the galactic hypothesis is about 300. Another application of Bayesian statistics is in the estimation of chance associations of optical counterparts with galaxies. The Bayesian approach is preferred to frequentist techniques here because the Bayesian approach easily accounts for galaxy mass distributions and because one can incorporate three disjoint hypotheses: (1) bursts come from galactic centers, (2) bursts come from galaxies in proportion to luminosity, and (3) bursts do not come from external galaxies. This technique was used in the analysis of the optical counterpart to GRB970228.

Higgs and superparticle mass predictions from the landscape

NASA Astrophysics Data System (ADS)

Baer, Howard; Barger, Vernon; Serce, Hasan; Sinha, Kuver

2018-03-01

Predictions for the scale of SUSY breaking from the string landscape go back at least a decade to the work of Denef and Douglas on the statistics of flux vacua. The assumption that an assortment of SUSY breaking F and D terms are present in the hidden sector, and their values are uniformly distributed in the landscape of D = 4, N = 1 effective supergravity models, leads to the expectation that the landscape pulls towards large values of soft terms favored by a power law behavior P( m soft) ˜ m soft n . On the other hand, similar to Weinberg's prediction of the cosmological constant, one can assume an anthropic selection of weak scales not too far from the measured value characterized by m W,Z,h ˜ 100 GeV. Working within a fertile patch of gravity-mediated low energy effective theories where the superpotential μ term is ≪ m 3/2, as occurs in models such as radiative breaking of Peccei-Quinn symmetry, this biases statistical distributions on the landscape by a cutoff on the parameter ΔEW, which measures fine-tuning in the m Z - μ mass relation. The combined effect of statistical and anthropic pulls turns out to favor low energy phenomenology that is more or less agnostic to UV physics. While a uniform selection n = 0 of soft terms produces too low a value for m h , taking n = 1 and 2 produce most probabilistically m h ˜ 125 GeV for negative trilinear terms. For n ≥ 1, there is a pull towards split generations with {m}_{\\tilde{q},\\tilde{ℓ}}(1,2)˜ 10-30 TeV whilst {m}_{{\\tilde{t}}_1}˜ 1-2 TeV . The most probable gluino mass comes in at ˜ 3 - 4 TeV — apparently beyond the reach of HL-LHC (although the required quasi-degenerate higgsinos should still be within reach). We comment on consequences for SUSY collider and dark matter searches.

Neighborhood Structural Similarity Mapping for the Classification of Masses in Mammograms.

PubMed

Rabidas, Rinku; Midya, Abhishek; Chakraborty, Jayasree

2018-05-01

In this paper, two novel feature extraction methods, using neighborhood structural similarity (NSS), are proposed for the characterization of mammographic masses as benign or malignant. Since gray-level distribution of pixels is different in benign and malignant masses, more regular and homogeneous patterns are visible in benign masses compared to malignant masses; the proposed method exploits the similarity between neighboring regions of masses by designing two new features, namely, NSS-I and NSS-II, which capture global similarity at different scales. Complementary to these global features, uniform local binary patterns are computed to enhance the classification efficiency by combining with the proposed features. The performance of the features are evaluated using the images from the mini-mammographic image analysis society (mini-MIAS) and digital database for screening mammography (DDSM) databases, where a tenfold cross-validation technique is incorporated with Fisher linear discriminant analysis, after selecting the optimal set of features using stepwise logistic regression method. The best area under the receiver operating characteristic curve of 0.98 with an accuracy of is achieved with the mini-MIAS database, while the same for the DDSM database is 0.93 with accuracy .

Three-phase boundary length in solid-oxide fuel cells: A mathematical model

NASA Astrophysics Data System (ADS)

Janardhanan, Vinod M.; Heuveline, Vincent; Deutschmann, Olaf

A mathematical model to calculate the volume specific three-phase boundary length in the porous composite electrodes of solid-oxide fuel cell is presented. The model is exclusively based on geometrical considerations accounting for porosity, particle diameter, particle size distribution, and solids phase distribution. Results are presented for uniform particle size distribution as well as for non-uniform particle size distribution.

Spatial Burnout in Water Reactors with Nonuniform Startup Distributions of Uranium and Boron

NASA Technical Reports Server (NTRS)

Fox, Thomas A.; Bogart, Donald

1955-01-01

Spatial burnout calculations have been made of two types of water moderated cylindrical reactor using boron as a burnable poison to increase reactor life. Specific reactors studied were a version of the Submarine Advanced Reactor (sAR) and a supercritical water reactor (SCW) . Burnout characteristics such as reactivity excursion, neutron-flux and heat-generation distributions, and uranium and boron distributions have been determined for core lives corresponding to a burnup of approximately 7 kilograms of fully enriched uranium. All reactivity calculations have been based on the actual nonuniform distribution of absorbers existing during intervals of core life. Spatial burnout of uranium and boron and spatial build-up of fission products and equilibrium xenon have been- considered. Calculations were performed on the NACA nuclear reactor simulator using two-group diff'usion theory. The following reactor burnout characteristics have been demonstrated: 1. A significantly lower excursion in reactivity during core life may be obtained by nonuniform rather than uniform startup distribution of uranium. Results for SCW with uranium distributed to provide constant radial heat generation and a core life corresponding to a uranium burnup of 7 kilograms indicated a maximum excursion in reactivity of 2.5 percent. This compared to a maximum excursion of 4.2 percent obtained for the same core life when w'anium was uniformly distributed at startup. Boron was incorporated uniformly in these cores at startup. 2. It is possible to approach constant radial heat generation during the life of a cylindrical core by means of startup nonuniform radial and axial distributions of uranium and boron. Results for SCW with nonuniform radial distribution of uranium to provide constant radial heat generation at startup and with boron for longevity indicate relatively small departures from the initially constant radial heat generation distribution during core life. Results for SAR with a sinusoidal distribution rather than uniform axial distributions of boron indicate significant improvements in axial heat generation distribution during the greater part of core life. 3. Uranium investments for cylindrical reactors with nonuniform radial uranium distributions which provide constant radial heat generation per unit core volume are somewhat higher than for reactors with uniform uranium concentration at startup. On the other hand, uranium investments for reactors with axial boron distributions which approach constant axial heat generation are somewhat smaller than for reactors with uniform boron distributions at startup.

The current impact flux on Mars and its seasonal variation

NASA Astrophysics Data System (ADS)

JeongAhn, Youngmin; Malhotra, Renu

2015-12-01

We calculate the present-day impact flux on Mars and its variation over the martian year, using the current data on the orbital distribution of known Mars-crossing minor planets. We adapt the Öpik-Wetherill formulation for calculating collision probabilities, paying careful attention to the non-uniform distribution of the perihelion longitude and the argument of perihelion owed to secular planetary perturbations. We find that, at the current epoch, the Mars crossers have an axial distribution of the argument of perihelion, and the mean direction of their eccentricity vectors is nearly aligned with Mars' eccentricity vector. These previously neglected angular non-uniformities have the effect of depressing the mean annual impact flux by a factor of about 2 compared to the estimate based on a uniform random distribution of the angular elements of Mars-crossers; the amplitude of the seasonal variation of the impact flux is likewise depressed by a factor of about 4-5. We estimate that the flux of large impactors (of absolute magnitude H < 16) within ±30° of Mars' aphelion is about three times larger than when the planet is near perihelion. Extrapolation of our results to a model population of meter-size Mars-crossers shows that if these small impactors have a uniform distribution of their angular elements, then their aphelion-to-perihelion impact flux ratio would be 11-15, but if they track the orbital distribution of the large impactors, including their non-uniform angular elements, then this ratio would be about 3. Comparison of our results with the current dataset of fresh impact craters on Mars (detected with Mars-orbiting spacecraft) appears to rule out the uniform distribution of angular elements.

Adding muscle where you need it: non-uniform hypertrophy patterns in elite sprinters.

PubMed

Handsfield, G G; Knaus, K R; Fiorentino, N M; Meyer, C H; Hart, J M; Blemker, S S

2017-10-01

Sprint runners achieve much higher gait velocities and accelerations than average humans, due in part to large forces generated by their lower limb muscles. Various factors have been explored in the past to understand sprint biomechanics, but the distribution of muscle volumes in the lower limb has not been investigated in elite sprinters. In this study, we used non-Cartesian MRI to determine muscle sizes in vivo in a group of 15 NCAA Division I sprinters. Normalizing muscle sizes by body size, we compared sprinter muscles to non-sprinter muscles, calculated Z-scores to determine non-uniformly large muscles in sprinters, assessed bilateral symmetry, and assessed gender differences in sprinters' muscles. While limb musculature per height-mass was 22% greater in sprinters than in non-sprinters, individual muscles were not all uniformly larger. Hip- and knee-crossing muscles were significantly larger among sprinters (mean difference: 30%, range: 19-54%) but only one ankle-crossing muscle was significantly larger (tibialis posterior, 28%). Population-wide asymmetry was not significant in the sprint population but individual muscle asymmetries exceeded 15%. Gender differences in normalized muscle sizes were not significant. The results of this study suggest that non-uniform hypertrophy patterns, particularly large hip and knee flexors and extensors, are advantageous for fast sprinting. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A revised model for Jeffrey nanofluid subject to convective condition and heat generation/absorption

PubMed Central

Hayat, Tasawar; Aziz, Arsalan; Muhammad, Taseer; Alsaedi, Ahmed

2017-01-01

Here magnetohydrodynamic (MHD) boundary layer flow of Jeffrey nanofluid by a nonlinear stretching surface is addressed. Heat generation/absorption and convective surface condition effects are considered. Novel features of Brownian motion and thermophoresis are present. A non-uniform applied magnetic field is employed. Boundary layer and small magnetic Reynolds number assumptions are employed in the formulation. A newly developed condition with zero nanoparticles mass flux is imposed. The resulting nonlinear systems are solved. Convergence domains are explicitly identified. Graphs are analyzed for the outcome of sundry variables. Further local Nusselt number is computed and discussed. It is observed that the effects of Hartman number on the temperature and concentration distributions are qualitatively similar. Both temperature and concentration distributions are enhanced for larger Hartman number. PMID:28231298

Microstructure and trapped field of YBCO bulk single-grain superconductors prepared by interior seeding

NASA Astrophysics Data System (ADS)

Radusovska, M.; Diko, P.; Piovarci, S.; Park, S.-D.; Jun, B.-H.; Kim, C.-J.

2017-10-01

The microstructural analyses of YBCO bulk single-grain superconductors grown by interior seeding with taller and shorter upper pellets have shown that a suitable upper pellet height can lower the porosity in the upper part of the sample, produce a more appropriate distribution of pinning centres in the form of Y-211 particles and suppress subgrain formation with a higher crystal misalignment in the c-growth sector (c-GS), which can lead to a higher measured trapped magnetic field and a more uniform cone of the trapped-field profile. The observed bulging of the sample surface at the c-GS can be explained by the edge melt distribution model, which shows that macroscopic mass transport to the growth sector occurs with higher growth rates.

Application of Statistically Derived CPAS Parachute Parameters

NASA Technical Reports Server (NTRS)

Romero, Leah M.; Ray, Eric S.

2013-01-01

The Capsule Parachute Assembly System (CPAS) Analysis Team is responsible for determining parachute inflation parameters and dispersions that are ultimately used in verifying system requirements. A model memo is internally released semi-annually documenting parachute inflation and other key parameters reconstructed from flight test data. Dispersion probability distributions published in previous versions of the model memo were uniform because insufficient data were available for determination of statistical based distributions. Uniform distributions do not accurately represent the expected distributions since extreme parameter values are just as likely to occur as the nominal value. CPAS has taken incremental steps to move away from uniform distributions. Model Memo version 9 (MMv9) made the first use of non-uniform dispersions, but only for the reefing cutter timing, for which a large number of sample was available. In order to maximize the utility of the available flight test data, clusters of parachutes were reconstructed individually starting with Model Memo version 10. This allowed for statistical assessment for steady-state drag area (CDS) and parachute inflation parameters such as the canopy fill distance (n), profile shape exponent (expopen), over-inflation factor (C(sub k)), and ramp-down time (t(sub k)) distributions. Built-in MATLAB distributions were applied to the histograms, and parameters such as scale (sigma) and location (mu) were output. Engineering judgment was used to determine the "best fit" distribution based on the test data. Results include normal, log normal, and uniform (where available data remains insufficient) fits of nominal and failure (loss of parachute and skipped stage) cases for all CPAS parachutes. This paper discusses the uniform methodology that was previously used, the process and result of the statistical assessment, how the dispersions were incorporated into Monte Carlo analyses, and the application of the distributions in trajectory benchmark testing assessments with parachute inflation parameters, drag area, and reefing cutter timing used by CPAS.

Chemical characterization and source apportionment of size-resolved particles in Hong Kong sub-urban area

NASA Astrophysics Data System (ADS)

Gao, Yuan; Lee, Shun-Cheng; Huang, Yu; Chow, Judith C.; Watson, John G.

2016-03-01

Size-resolved particulate matter (PM) samples were collected with a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) at a sub-urban site (Tung Chung) in Hong Kong for four non-consecutive months representing four seasons from 2011 to 2012. Major chemical components were water-soluble anions (i.e., Cl-, NO3-, and SO42 -), cations (i.e., NH4+, Na+, K+, and Ca2 +), organic and elemental carbon and elements. Both chemical mass closure and positive matrix factorization (PMF) were employed to understand the chemical composition, resolve particle size modes, and evaluate the PM sources. Tri-modal size distributions were found for PM mass and major chemical components (e.g., SO42 -, NH4+, and OC). Mass median aerodynamic diameters (MMADs) with similar standard deviations (1.32 < σ < 1.42) were 0.4, 0.7 and 3.8 μm, consistent with condensation, droplet and coarse modes. A bi-modal distribution peaking at condensation and droplet modes was found for EC, with a single mode peaking at 3.8 μm for Cl-. Besides secondary SO42 -, carbonaceous aerosol dominated the condensation mode with 27% by engine exhaust and 18-19% each by residual oil combustion (shipping) and coal/biomass burning. Secondary SO42 - is also the most dominant component in the droplet mode, accounting for 23% of PM mass, followed by an industrial source (19%). Engine exhaust, secondary NO3-, and sea salt each accounted for 13-15% of PM mass. Sea salt and soil are the dominated sources in the coarse mode, accounting for 80% of coarse mass.

The physics origin of the hierarchy of bodies in space

NASA Astrophysics Data System (ADS)

Bejan, A.; Wagstaff, R. W.

2016-03-01

Here we show that bodies of the same size suspended uniformly in space constitute a system (a "suspension") in a state of uniform volumetric tension because of mass-to-mass forces of attraction. The system "snaps" hierarchically, and evolves faster to a state of reduced tension when the bodies coalesce spontaneously nonuniformly, i.e., hierarchically, into few large and many small bodies suspended in the same space. Hierarchy, not uniformity, is the design that emerges, and it is in accord with the constructal law. The implications of this principle of physics in natural organization and evolution are discussed.

A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode

PubMed Central

Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.

2013-01-01

Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions. PMID:23983449

A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode

NASA Astrophysics Data System (ADS)

Rieker, G. B.; Poehlmann, F. R.; Cappelli, M. A.

2013-07-01

Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.

A Thomson-type mass and energy spectrometer for characterizing ion energy distributions in a coaxial plasma gun operating in a gas-puff mode.

PubMed

Rieker, G B; Poehlmann, F R; Cappelli, M A

2013-07-01

Measurements of ion energy distribution are performed in the accelerated plasma of a coaxial electromagnetic plasma gun operating in a gas-puff mode at relatively low discharge energy (900 J) and discharge potential (4 kV). The measurements are made using a Thomson-type mass and energy spectrometer with a gated microchannel plate and phosphor screen as the ion sensor. The parabolic ion trajectories are captured from the sensor screen with an intensified charge-coupled detector camera. The spectrometer was designed and calibrated using the Geant4 toolkit, accounting for the effects on the ion trajectories of spatial non-uniformities in the spectrometer magnetic and electric fields. Results for hydrogen gas puffs indicate the existence of a class of accelerated protons with energies well above the coaxial discharge potential (up to 24 keV). The Thomson analyzer confirms the presence of impurities of copper and iron, also of relatively high energies, which are likely erosion or sputter products from plasma-electrode interactions.

On the oblateness and rotation rate of Neptune's atmosphere

NASA Technical Reports Server (NTRS)

Hubbard, W. B.

1986-01-01

Recent observations of a stellar occultation by Neptune give an oblateness of 0.022 + or - 0.004 for Neptune's atmosphere at the 1-microbar pressure level. This results is consistent with hydrostatic equilibrium at a uniform atmospheric rotation period of 15 hours, although the error bars on quantities used in the calculation are such that an 18-hour period is not excluded. The oblateness of a planetary atmosphere is determined from stellar occultations by measuring the times at which a specified point on immersion or emersion occultation profiles is reached. Whether this standard procedure for deriving the shape of the atmosphere is consistent with what is known about vertical and horizontal temperature gradients in Neptune's atmosphere is evaluated. The nature of the constraint placed on the interior mass distribution by an oblateness determined in this manner is consided, as is the effects of possible differential rotation. A 15-hour Neptune internal mass distribution is approximately homologous to Uranus', but an 18-hour period is not. The implications for Neptune's interior structure if its body rotation period is actually 18 hours are discussed.

Improvement of illumination uniformity for LED flat panel light by using micro-secondary lens array.

PubMed

Lee, Hsiao-Wen; Lin, Bor-Shyh

2012-11-05

LED flat panel light is an innovative lighting product in recent years. However, current flat panel light products still contain some drawbacks, such as narrow lighting areas and hot spots. In this study, a micro-secondary lens array technique was proposed and applied for the design of the light guide surface to improve the illumination uniformity. By using the micro-secondary lens array, the candela distribution of the LED flat panel light can be adjusted to similar to batwing distribution to improve the illumination uniformity. The experimental results show that the enhancement of the floor illumination uniformity is about 61%, and that of the wall illumination uniformity is about 20.5%.

The nonuniformity of antibody distribution in the kidney and its influence on dosimetry.

PubMed

Flynn, Aiden A; Pedley, R Barbara; Green, Alan J; Dearling, Jason L; El-Emir, Ethaar; Boxer, Geoffrey M; Boden, Robert; Begent, Richard H J

2003-02-01

The therapeutic efficacy of radiolabeled antibody fragments can be limited by nephrotoxicity, particularly when the kidney is the major route of extraction from the circulation. Conventional dose estimates in kidney assume uniform dose deposition, but we have shown increased antibody localization in the cortex after glomerular filtration. The purpose of this study was to measure the radioactivity in cortex relative to medulla for a range of antibodies and to assess the validity of the assumption of uniformity of dose deposition in the whole kidney and in the cortex for these antibodies with a range of radionuclides. Storage phosphor plate technology (radioluminography) was used to acquire images of the distributions of a range of antibodies of various sizes, labeled with 125I, in kidney sections. This allowed the calculation of the antibody concentration in the cortex relative to the medulla. Beta-particle point dose kernels were then used to generate the dose-rate distributions from 14C, 131I, 186Re, 32P and 90Y. The correlation between the actual dose-rate distribution and the corresponding distribution calculated assuming uniform antibody distribution throughout the kidney was used to test the validity of estimating dose by assuming uniformity in the kidney and in the cortex. There was a strong inverse relationship between the ratio of the radioactivity in the cortex relative to that in the medulla and the antibody size. The nonuniformity of dose deposition was greatest with the smallest antibody fragments but became more uniform as the range of the emissions from the radionuclide increased. Furthermore, there was a strong correlation between the actual dose-rate distribution and the distribution when assuming a uniform source in the kidney for intact antibodies along with medium- to long-range radionuclides, but there was no correlation for small antibody fragments with any radioisotope or for short-range radionuclides with any antibody. However, when the cortex was separated from the whole kidney, the correlation between the actual dose-rate distribution and the assumed dose-rate distribution, if the source was uniform, increased significantly. During radioimmunotherapy, the extent of nonuniformity of dose deposition in the kidney depends on the properties of the antibody and radionuclide. For dosimetry estimates, the cortex should be taken as a separate source region when the radiopharmaceutical is small enough to be filtered by the glomerulus.

Determination of the microbolometric FPA's responsivity with imaging system's radiometric considerations

NASA Astrophysics Data System (ADS)

Gogler, Slawomir; Bieszczad, Grzegorz; Krupinski, Michal

2013-10-01

Thermal imagers and used therein infrared array sensors are subject to calibration procedure and evaluation of their voltage sensitivity on incident radiation during manufacturing process. The calibration procedure is especially important in so-called radiometric cameras, where accurate radiometric quantities, given in physical units, are of concern. Even though non-radiometric cameras are not expected to stand up to such elevated standards, it is still important, that the image faithfully represents temperature variations across the scene. Detectors used in thermal camera are illuminated by infrared radiation transmitted through an infrared transmitting optical system. Often an optical system, when exposed to uniform Lambertian source forms a non-uniform irradiation distribution in its image plane. In order to be able to carry out an accurate non-uniformity correction it is essential to correctly predict irradiation distribution from a uniform source. In the article a non-uniformity correction method has been presented, that takes into account optical system's radiometry. Predictions of the irradiation distribution have been confronted with measured irradiance values. Presented radiometric model allows fast and accurate non-uniformity correction to be carried out.

Effects on Subtalar Joint Stress Distribution After Cannulated Screw Insertion at Different Positions and Directions.

PubMed

Yuan, Cheng-song; Chen, Wan; Chen, Chen; Yang, Guang-hua; Hu, Chao; Tang, Kang-lai

2015-01-01

We investigated the effects on subtalar joint stress distribution after cannulated screw insertion at different positions and directions. After establishing a 3-dimensional geometric model of a normal subtalar joint, we analyzed the most ideal cannulated screw insertion position and approach for subtalar joint stress distribution and compared the differences in loading stress, antirotary strength, and anti-inversion/eversion strength among lateral-medial antiparallel screw insertion, traditional screw insertion, and ideal cannulated screw insertion. The screw insertion approach allowing the most uniform subtalar joint loading stress distribution was lateral screw insertion near the border of the talar neck plus medial screw insertion close to the ankle joint. For stress distribution uniformity, antirotary strength, and anti-inversion/eversion strength, lateral-medial antiparallel screw insertion was superior to traditional double-screw insertion. Compared with ideal cannulated screw insertion, slightly poorer stress distribution uniformity and better antirotary strength and anti-inversion/eversion strength were observed for lateral-medial antiparallel screw insertion. Traditional single-screw insertion was better than double-screw insertion for stress distribution uniformity but worse for anti-rotary strength and anti-inversion/eversion strength. Lateral-medial antiparallel screw insertion was slightly worse for stress distribution uniformity than was ideal cannulated screw insertion but superior to traditional screw insertion. It was better than both ideal cannulated screw insertion and traditional screw insertion for anti-rotary strength and anti-inversion/eversion strength. Lateral-medial antiparallel screw insertion is an approach with simple localization, convenient operation, and good safety. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Circular, confined distribution for charged particle beams

DOEpatents

Garnett, Robert W.; Dobelbower, M. Christian

1995-01-01

A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location.

Circular, confined distribution for charged particle beams

DOEpatents

Garnett, R.W.; Dobelbower, M.C.

1995-11-21

A charged particle beam line is formed with magnetic optics that manipulate the charged particle beam to form the beam having a generally rectangular configuration to a circular beam cross-section having a uniform particle distribution at a predetermined location. First magnetic optics form a charged particle beam to a generally uniform particle distribution over a square planar area at a known first location. Second magnetic optics receive the charged particle beam with the generally square configuration and affect the charged particle beam to output the charged particle beam with a phase-space distribution effective to fold corner portions of the beam toward the core region of the beam. The beam forms a circular configuration having a generally uniform spatial particle distribution over a target area at a predetermined second location. 26 figs.

On the vertical distribution of water vapor in the Martian tropics

NASA Technical Reports Server (NTRS)

Haberle, Robert M.

1988-01-01

Although measurements of the column abundance of atmospheric water vapor on Mars have been made, measurements of its vertical distribution have not. How water is distributed in the vertical is fundamental to atmosphere-surface exchange processes, and especially to transport within the atmosphere. Several lines of evidence suggest that in the lowest several scale heights of the atmosphere, water vapor is nearly uniformly distributed. However, most of these arguments are suggestive rather than conclusive since they only demonstrate that the altitude to saturation is very high if the observed amount of water vapor is distributed uniformly. A simple argument is presented, independent of the saturation constraint, which suggests that in tropical regions, water vapor on Mars should be very nearly uniformly mixed on an annual and zonally averaged basis.

Relation between Water Balance and Climatic Variables Associated with the Geographical Distribution of Anurans

PubMed Central

Titon, Braz; Gomes, Fernando Ribeiro

2015-01-01

Amphibian species richness increases toward the equator, particularly in humid tropical forests. This relation between amphibian species richness and environmental water availability has been proposed to be a consequence of their high rates of evaporative water loss. In this way, traits that estimate water balance are expected to covary with climate and constrain a species’ geographic distribution. Furthermore, we predicted that coexisting species of anurans would have traits that are adapted to local hydric conditions. We compared the traits that describe water balance in 17 species of anurans that occur in the mesic Atlantic Forest and xeric Cerrado (savannah) habitats of Brazil. We predicted that species found in the warmer and dryer areas would show a lower sensitivity of locomotor performance to dehydration (SLPD), increased resistance to evaporative water loss (REWL) and higher rates of water uptake (RWU) than species restricted to the more mesic areas. We estimated the allometric relations between the hydric traits and body mass using phylogenetic generalized least squares. These regressions showed that REWL scaled negatively with body mass, whereas RWU scaled positively with body mass. Additionally, species inhabiting areas characterized by higher and more seasonally uniform temperatures, and lower and more seasonally concentrated precipitation, such as the Cerrado, had higher RWU and SLPD than species with geographical distributions more restricted to mesic environments, such as the Atlantic Forest. These results support the hypothesis that the interspecific variation of physiological traits shows an adaptation pattern to abiotic environmental traits. PMID:26469787

Identifying airborne metal particles sources near an optoelectronic and semiconductor industrial park

NASA Astrophysics Data System (ADS)

Chen, Ho-Wen; Chen, Wei-Yea; Chang, Cheng-Nan; Chuang, Yen-Hsun; Lin, Yu-Hao

2016-06-01

The recently developed Central Taiwan Science Park (CTSP) in central Taiwan is home to an optoelectronic and semiconductor industrial cluster. Therefore, exploring the elemental compositions and size distributions of airborne particles emitted from the CTSP would help to prevent pollution. This study analyzed size-fractionated metal-rich particle samples collected in upwind and downwind areas of CTSP during Jan. and Oct. 2013 by using micro-orifice uniform deposited impactor (MOUDI). Correlation analysis, hierarchical cluster analysis and particle mass-size distribution analysis are performed to identify the source of metal-rich particle near the CTSP. Analyses of elemental compositions and particle size distributions emitted from the CTSP revealed that the CTSP emits some metals (V, As, In Ga, Cd and Cu) in the ultrafine particles (< 1 μm). The statistical analysis combines with the particle mass-size distribution analysis could provide useful source identification information. In airborne particles with the size of 0.32 μm, Ga could be a useful pollution index for optoelectronic and semiconductor emission in the CTSP. Meanwhile, the ratios of As/Ga concentration at the particle size of 0.32 μm demonstrates that humans near the CTSP would be potentially exposed to GaAs ultrafine particles. That is, metals such as Ga and As and other metals that are not regulated in Taiwan are potentially harmful to human health.

Logical optimization for database uniformization

NASA Technical Reports Server (NTRS)

Grant, J.

1984-01-01

Data base uniformization refers to the building of a common user interface facility to support uniform access to any or all of a collection of distributed heterogeneous data bases. Such a system should enable a user, situated anywhere along a set of distributed data bases, to access all of the information in the data bases without having to learn the various data manipulation languages. Furthermore, such a system should leave intact the component data bases, and in particular, their already existing software. A survey of various aspects of the data bases uniformization problem and a proposed solution are presented.

Quasi-Uniform High Speed Foam Crush Testing Using a Guided Drop Mass Impact

NASA Technical Reports Server (NTRS)

Jones, Lisa E. (Technical Monitor); Kellas, Sotiris

2004-01-01

A relatively simple method for measuring the dynamic crush response of foam materials at various loading rates is described. The method utilizes a drop mass impact configuration with mass and impact velocity selected such that the crush speed remains approximately uniform during the entire sample crushing event. Instrumentation, data acquisition, and data processing techniques are presented, and limitations of the test method are discussed. The objective of the test method is to produce input data for dynamic finite element modeling involving crash and energy absorption characteristics of foam materials.

The NUONCE engine for LEO networks

NASA Technical Reports Server (NTRS)

Lo, Martin W.; Estabrook, Polly

1995-01-01

Typical LEO networks use constellations which provide a uniform coverage. However, the demand for telecom service is dynamic and unevenly distributed around the world. We examine a more efficient and cost effective design by matching the satellite coverage with the cyclical demand for service around the world. Our approach is to use a non-uniform satellite distribution for the network. We have named this constellation design NUONCE for Non Uniform Optimal Network Communications Engine.

Suspension concentration distribution in turbulent flows: An analytical study using fractional advection-diffusion equation

NASA Astrophysics Data System (ADS)

Kundu, Snehasis

2018-09-01

In this study vertical distribution of sediment particles in steady uniform turbulent open channel flow over erodible bed is investigated using fractional advection-diffusion equation (fADE). Unlike previous investigations on fADE to investigate the suspension distribution, in this study the modified Atangana-Baleanu-Caputo fractional derivative with a non-singular and non-local kernel is employed. The proposed fADE is solved and an analytical model for finding vertical suspension distribution is obtained. The model is validated against experimental as well as field measurements of Missouri River, Mississippi River and Rio Grande conveyance channel and is compared with the Rouse equation and other fractional model found in literature. A quantitative error analysis shows that the proposed model is able to predict the vertical distribution of particles more appropriately than previous models. The validation results shows that the fractional model can be equally applied to all size of particles with an appropriate choice of the order of the fractional derivative α. It is also found that besides particle diameter, parameter α depends on the mass density of particle and shear velocity of the flow. To predict this parameter, a multivariate regression is carried out and a relation is proposed for easy application of the model. From the results for sand and plastic particles, it is found that the parameter α is more sensitive to mass density than the particle diameter. The rationality of the dependence of α on particle and flow characteristics has been justified physically.

Bio-convection on the nonlinear radiative flow of a Carreau fluid over a moving wedge with suction or injection

NASA Astrophysics Data System (ADS)

Raju, C. S. K.; Ibrahim, S. M.; Anuradha, S.; Priyadharshini, P.

2016-11-01

In modern days, the mass transfer rate is challenging to the scientists due to its noticeable significance for industrial as well as engineering applications; owing to this we attempt to study the cross-diffusion effects on the magnetohydrodynamic nonlinear radiative Carreau fluid over a wedge filled with gyro tactic microorganisms. Numerical results are presented graphically as well as in tabular form with the aid of the Runge-Kutta and Newton methods. The effects of pertinent parameters on velocity, temperature, concentration and density of motile organism distributions are presented and discussed for two cases (suction and injection flows). For real-life application we also calculated the local Nusselt and Sherwood numbers. It is observed that thermal and concentration profiles are not uniform in the suction and injection flow cases. It is found that the heat and mass transport phenomenon is high in the injection case, while heat and mass transfer rates are high in the suction flow case.

Direct numerical simulation of incompressible multiphase flow with phase change

NASA Astrophysics Data System (ADS)

Lee, Moon Soo; Riaz, Amir; Aute, Vikrant

2017-09-01

Simulation of multiphase flow with phase change is challenging because of the potential for unphysical pressure oscillations, spurious velocity fields and mass flux errors across the interface. The resulting numerical errors may become critical when large density contrasts are present. To address these issues, we present a new approach for multiphase flow with phase change that features, (i) a smooth distribution of sharp velocity jumps and mass flux within a narrow region surrounding the interface, (ii) improved mass flux projection from the implicit interface onto the uniform Cartesian grid and (iii) post-advection velocity correction step to ensure accurate velocity divergence in interfacial cells. These new features are implemented in combination with a sharp treatment of the jumps in pressure and temperature gradient. A series of 1-D, 2-D, axisymmetric and 3-D problems are solved to verify the improvements afforded by the new approach. Axisymmetric film boiling results are also presented, which show good qualitative agreement with heat transfer correlations as well as experimental observations of bubble shapes.

Cooling water distribution system

DOEpatents

Orr, Richard

1994-01-01

A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using an interconnected series of radial guide elements, a plurality of circumferential collector elements and collector boxes to collect and feed the cooling water into distribution channels extending along the curved surface of the steel containment vessel. The cooling water is uniformly distributed over the curved surface by a plurality of weirs in the distribution channels.

Performance of intraclass correlation coefficient (ICC) as a reliability index under various distributions in scale reliability studies.

PubMed

Mehta, Shraddha; Bastero-Caballero, Rowena F; Sun, Yijun; Zhu, Ray; Murphy, Diane K; Hardas, Bhushan; Koch, Gary

2018-04-29

Many published scale validation studies determine inter-rater reliability using the intra-class correlation coefficient (ICC). However, the use of this statistic must consider its advantages, limitations, and applicability. This paper evaluates how interaction of subject distribution, sample size, and levels of rater disagreement affects ICC and provides an approach for obtaining relevant ICC estimates under suboptimal conditions. Simulation results suggest that for a fixed number of subjects, ICC from the convex distribution is smaller than ICC for the uniform distribution, which in turn is smaller than ICC for the concave distribution. The variance component estimates also show that the dissimilarity of ICC among distributions is attributed to the study design (ie, distribution of subjects) component of subject variability and not the scale quality component of rater error variability. The dependency of ICC on the distribution of subjects makes it difficult to compare results across reliability studies. Hence, it is proposed that reliability studies should be designed using a uniform distribution of subjects because of the standardization it provides for representing objective disagreement. In the absence of uniform distribution, a sampling method is proposed to reduce the non-uniformity. In addition, as expected, high levels of disagreement result in low ICC, and when the type of distribution is fixed, any increase in the number of subjects beyond a moderately large specification such as n = 80 does not have a major impact on ICC. Copyright © 2018 John Wiley & Sons, Ltd.

Disentangling rotational velocity distribution of stars

NASA Astrophysics Data System (ADS)

Curé, Michel; Rial, Diego F.; Cassetti, Julia; Christen, Alejandra

2017-11-01

Rotational speed is an important physical parameter of stars: knowing the distribution of stellar rotational velocities is essential for understanding stellar evolution. However, rotational speed cannot be measured directly and is instead the convolution between the rotational speed and the sine of the inclination angle vsin(i). The problem itself can be described via a Fredhoml integral of the first kind. A new method (Curé et al. 2014) to deconvolve this inverse problem and obtain the cumulative distribution function for stellar rotational velocities is based on the work of Chandrasekhar & Münch (1950). Another method to obtain the probability distribution function is Tikhonov regularization method (Christen et al. 2016). The proposed methods can be also applied to the mass ratio distribution of extrasolar planets and brown dwarfs (in binary systems, Curé et al. 2015). For stars in a cluster, where all members are gravitationally bounded, the standard assumption that rotational axes are uniform distributed over the sphere is questionable. On the basis of the proposed techniques a simple approach to model this anisotropy of rotational axes has been developed with the possibility to ``disentangling'' simultaneously both the rotational speed distribution and the orientation of rotational axes.

Integrated-Circuit Pseudorandom-Number Generator

NASA Technical Reports Server (NTRS)

Steelman, James E.; Beasley, Jeff; Aragon, Michael; Ramirez, Francisco; Summers, Kenneth L.; Knoebel, Arthur

1992-01-01

Integrated circuit produces 8-bit pseudorandom numbers from specified probability distribution, at rate of 10 MHz. Use of Boolean logic, circuit implements pseudorandom-number-generating algorithm. Circuit includes eight 12-bit pseudorandom-number generators, outputs are uniformly distributed. 8-bit pseudorandom numbers satisfying specified nonuniform probability distribution are generated by processing uniformly distributed outputs of eight 12-bit pseudorandom-number generators through "pipeline" of D flip-flops, comparators, and memories implementing conditional probabilities on zeros and ones.

Pharmaceutical Equivalence of Distributed Generic Antiretroviral (ARV) in Asian Settings: The Cross-Sectional Surveillance Study - PEDA Study.

PubMed

Sapsirisavat, Vorapot; Vongsutilers, Vorasit; Thammajaruk, Narukjaporn; Pussadee, Kanitta; Riyaten, Prakit; Kerr, Stephen; Avihingsanon, Anchalee; Phanuphak, Praphan; Ruxrungtham, Kiat

2016-01-01

Ensuring that medicines meet quality standards is mandatory for ensuring safety and efficacy. There have been occasional reports of substandard generic medicines, especially in resource-limiting settings where policies to control quality may be less rigorous. As HIV treatment in Thailand depends mostly on affordable generic antiretrovirals (ARV), we performed quality assurance testing of several generic ARV available from different sources in Thailand and a source from Vietnam. We sampled Tenofovir 300mg, Efavirenz 600mg and Lopinavir/ritonavir 200/50mg from 10 primary hospitals randomly selected from those participating in the National AIDS Program, 2 non-government organization ARV clinics, and 3 private drug stores. Quality of ARV was analyzed by blinded investigators at the Faculty of Pharmaceutical Science, Chulalongkorn University. The analysis included an identification test for drug molecules, a chemical composition assay to quantitate the active ingredients, a uniformity of mass test and a dissolution test to assess in-vitro drug release. Comparisons were made against the standards described in the WHO international pharmacopeia. A total of 42 batches of ARV from 15 sources were sampled from January-March 2015. Among those generics, 23, 17, 1, and 1 were Thai-made, Indian-made, Vietnamese-made and Chinese-made, respectively. All sampled products, regardless of manufacturers or sources, met the International Pharmacopeia standards for composition assay, mass uniformity and dissolution. Although local regulations restrict ARV supply to hospitals and clinics, samples of ARV could be bought from private drug stores even without formal prescription. Sampled generic ARVs distributed within Thailand and 1 Vietnamese pharmacy showed consistent quality. However some products were illegally supplied without prescription, highlighting the importance of dispensing ARV for treatment or prevention in facilities where continuity along the HIV treatment and care cascade is available.

Event Patterns Extracted from Transverse Momentum and Rapidity Spectra of Z Bosons and Quarkonium States Produced in pp and Pb-Pb Collisions at LHC

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

Chen, Ya-Hui; Liu, Fu-Hu; Lacey, Roy A.

Trmore » ansverse momentum ( p T ) and rapidity ( y ) spectra of Z bosons and quarkonium states (some charmonium c c ¯ mesons such as J / ψ and ψ ( 2 S ) and some bottomonium b b ¯ mesons such as Υ ( 1 S ) , Υ ( 2 S ) , and Υ ( 3 S ) ) produced in proton-proton (pp) and lead-lead (Pb-Pb) collisions at the large hadron collider (LHC) are uniformly described by a hybrid model of two-component Erlang distribution for p T spectrum and two-component Gaussian distribution for y spectrum. The former distribution results from a multisource thermal model, and the latter one results from the revised Landau hydrodynamic model. The modelling results are in agreement with the experimental data measured in pp collisions at center-of-mass energies s = 2.76 and 7 TeV and in Pb-Pb collisions at center-of-mass energy per nucleon pair s N N = 2.76 TeV. Based on the parameter values extracted from p T and y spectra, the event patterns (particle scatter plots) in two-dimensional p T - y space and in three-dimensional velocity space are obtained.« less

Event Patterns Extracted from Transverse Momentum and Rapidity Spectra of Z Bosons and Quarkonium States Produced in pp and Pb-Pb Collisions at LHC

DOE PAGES

Chen, Ya-Hui; Liu, Fu-Hu; Lacey, Roy A.

2016-10-01

Trmore » ansverse momentum ( p T ) and rapidity ( y ) spectra of Z bosons and quarkonium states (some charmonium c c ¯ mesons such as J / ψ and ψ ( 2 S ) and some bottomonium b b ¯ mesons such as Υ ( 1 S ) , Υ ( 2 S ) , and Υ ( 3 S ) ) produced in proton-proton (pp) and lead-lead (Pb-Pb) collisions at the large hadron collider (LHC) are uniformly described by a hybrid model of two-component Erlang distribution for p T spectrum and two-component Gaussian distribution for y spectrum. The former distribution results from a multisource thermal model, and the latter one results from the revised Landau hydrodynamic model. The modelling results are in agreement with the experimental data measured in pp collisions at center-of-mass energies s = 2.76 and 7 TeV and in Pb-Pb collisions at center-of-mass energy per nucleon pair s N N = 2.76 TeV. Based on the parameter values extracted from p T and y spectra, the event patterns (particle scatter plots) in two-dimensional p T - y space and in three-dimensional velocity space are obtained.« less

Effects of external pressure on the performance and ageing of single-layer lithium-ion pouch cells

NASA Astrophysics Data System (ADS)

Mussa, Abdilbari Shifa; Klett, Matilda; Lindbergh, Göran; Lindström, Rakel Wreland

2018-05-01

The effects of external compression on the performance and ageing of NMC(1/3)/Graphite single-layer Li-ion pouch cells are investigated using a spring-loaded fixture. The influence of pressure (0.66, 0.99, 1.32, and 1.98 MPa) on impedance is characterized in fresh cells that are subsequently cycled at the given pressure levels. The aged cells are analyzed for capacity fade and impedance rise at the cell and electrode level. The effect of pressure distribution that may occur in large-format cells or in a battery pack is simulated using parallel connected cells. The results show that the kinetic and mass transport resistance increases with pressure in a fresh cell. An optimum pressure around 1.3 MPa is shown to be beneficial to reduce cyclable-lithium loss during cycling. The minor active mass losses observed in the electrodes are independent of the ageing pressure, whereas ageing pressure affects the charge transfer resistance of both NMC and graphite electrodes and the ohmic resistance of the cell. Pressure distribution induces current distribution but the enhanced current throughput at lower pressures cell does not accelerate its ageing. Conclusions from this work can explain some of the discrepancies in non-uniform ageing reported in the literature and indicate coupling between electrochemistry and mechanics.

Spatial effect of conical angle on optical-thermal distribution for circumferential photocoagulation

PubMed Central

Truong, Van Gia; Park, Suhyun; Tran, Van Nam; Kang, Hyun Wook

2017-01-01

A uniformly diffusing applicator can be advantageous for laser treatment of tubular tissue. The current study investigated various conical angles for diffuser tips as a critical factor for achieving radially uniform light emission. A customized goniometer was employed to characterize the spatial uniformity of the light propagation. An ex vivo model was developed to quantitatively compare the temperature development and irreversible tissue coagulation. The 10-mm diffuser tip with angle at 25° achieved a uniform longitudinal intensity profile (i.e., 0.90 ± 0.07) as well as a consistent thermal denaturation on the tissue. The proposed conical angle can be instrumental in determining the uniformity of light distribution for the photothermal treatment of tubular tissue. PMID:29296495

A New Method for Determining Permethrin Level on Military Uniform Fabrics

DTIC Science & Technology

2017-06-01

new desorption- gas chromatography–mass spectrometry based screening tool for permethrin content in military fabrics was developed. The method allows...SUBJECT TERMS permethrin, Army Combat Uniform, ACU, camouflage, desorption- gas chromatography-mass spectrometry, D-GC-MS 16. SECURITY CLASSIFICATION OF...and the permethrin contained in the specimens is extracted with solvent with a recovery rate of at least 95%. Samples are analyzed using a gas

Investigation of the High Mobility IGZO Thin Films by Using Co-Sputtering Method

PubMed Central

Hsu, Chao-Ming; Tzou, Wen-Cheng; Yang, Cheng-Fu; Liou, Yu-Jhen

2015-01-01

High transmittance ratio in visible range, low resistivity, and high mobility of IGZO thin films were prepared at room temperature for 30 min by co-sputtering of Zn2Ga2O5 (Ga2O3 + 2 ZnO, GZO) ceramic and In2O3 ceramic at the same time. The deposition power of pure In2O3 ceramic target was fixed at 100 W and the deposition power of GZO ceramic target was changed from 80 W to 140 W. We chose to investigate the deposition power of GZO ceramic target on the properties of IGZO thin films. From the SEM observations, all of the deposited IGZO thin films showed a very smooth and featureless surface. From the measurements of XRD patterns, only the amorphous structure was observed. We aimed to show that the deposition power of GZO ceramic target had large effect on the Eg values, Hall mobility, carrier concentration, and resistivity of IGZO thin films. Secondary ion mass spectrometry (SIMS) analysis in the thicknesses’ profile of IGZO thin films found that In and Ga elements were uniform distribution and Zn element were non-uniform distribution. The SIMS analysis results also showed the concentrations of Ga and Zn elements increased and the concentrations of In element was almost unchanged with increasing deposition power.

Performance enhancement of iron-chromium redox flow batteries by employing interdigitated flow fields

NASA Astrophysics Data System (ADS)

Zeng, Y. K.; Zhou, X. L.; Zeng, L.; Yan, X. H.; Zhao, T. S.

2016-09-01

The catalyst for the negative electrode of iron-chromium redox flow batteries (ICRFBs) is commonly prepared by adding a small amount of Bi3+ ions in the electrolyte and synchronously electrodepositing metallic particles onto the electrode surface at the beginning of charge process. Achieving a uniform catalyst distribution in the porous electrode, which is closely related to the flow field design, is critically important to improve the ICRFB performance. In this work, the effects of flow field designs on catalyst electrodeposition and battery performance are investigated. It is found that compared to the serpentine flow field (SFF) design, the interdigitated flow field (IFF) forces the electrolyte through the porous electrode between the neighboring channels and enhances species transport during the processes of both the catalyst electrodeposition and iron/chromium redox reactions, thus enabling a more uniform catalyst distribution and higher mass transport limitation. It is further demonstrated that the energy efficiency of the ICRFB with the IFF reaches 80.7% at a high current density (320 mA cm-2), which is 8.2% higher than that of the ICRFB with the SFF. With such a high performance and intrinsically low-cost active materials, the ICRFB with the IFF offers a great promise for large-scale energy storage.

A tuneable approach to uniform light distribution for artificial daylight photodynamic therapy.

PubMed

O'Mahoney, Paul; Haigh, Neil; Wood, Kenny; Brown, C Tom A; Ibbotson, Sally; Eadie, Ewan

2018-06-16

Implementation of daylight photodynamic therapy (dPDT) is somewhat limited by variable weather conditions. Light sources have been employed to provide artificial dPDT indoors, with low irradiances and longer treatment times. Uniform light distribution across the target area is key to ensuring effective treatment, particularly for large areas. A novel light source is developed with tuneable direction of light emission in order to meet this challenge. Wavelength composition of the novel light source is controlled such that the protoporphyrin-IX (PpIX) weighed spectra of both the light source and daylight match. The uniformity of the light source is characterised on a flat surface, a model head and a model leg. For context, a typical conventional PDT light source is also characterised. Additionally, the wavelength uniformity across the treatment site is characterised. The PpIX-weighted spectrum of the novel light source matches with PpIX-weighted daylight spectrum, with irradiance values within the bounds for effective dPDT. By tuning the direction of light emission, improvements are seen in the uniformity across large anatomical surfaces. Wavelength uniformity is discussed. We have developed a light source that addresses the challenges in uniform, multiwavelength light distribution for large area artificial dPDT across curved anatomical surfaces. Copyright © 2018. Published by Elsevier B.V.

Galaxy Groups in the 2Mass Redshift Survey

NASA Astrophysics Data System (ADS)

Lu, Yi; Yang, Xiaohu; Shi, Feng; Mo, H. J.; Tweed, Dylan; Wang, Huiyuan; Zhang, Youcai; Li, Shijie; Lim, S. H.

2016-11-01

A galaxy group catalog is constructed from the 2MASS Redshift Survey (2MRS) with the use of a halo-based group finder. The halo mass associated with a group is estimated using a “GAP” method based on the luminosity of the central galaxy and its gap with other member galaxies. Tests using mock samples show that this method is reliable, particularly for poor systems containing only a few members. On average, 80% of all the groups have completeness \\gt 0.8, and about 65% of the groups have zero contamination. Halo masses are estimated with a typical uncertainty of ∼ 0.35 {dex}. The application of the group finder to the 2MRS gives 29,904 groups from a total of 43,246 galaxies at z≤slant 0.08, with 5286 groups having two or more members. Some basic properties of this group catalog is presented, and comparisons are made with other group catalogs in overlap regions. With a depth to z∼ 0.08 and uniformly covering about 91% of the whole sky, this group catalog provides a useful database to study galaxies in the local cosmic web, and to reconstruct the mass distribution in the local universe.

Representing Color Ensembles.

PubMed

Chetverikov, Andrey; Campana, Gianluca; Kristjánsson, Árni

2017-10-01

Colors are rarely uniform, yet little is known about how people represent color distributions. We introduce a new method for studying color ensembles based on intertrial learning in visual search. Participants looked for an oddly colored diamond among diamonds with colors taken from either uniform or Gaussian color distributions. On test trials, the targets had various distances in feature space from the mean of the preceding distractor color distribution. Targets on test trials therefore served as probes into probabilistic representations of distractor colors. Test-trial response times revealed a striking similarity between the physical distribution of colors and their internal representations. The results demonstrate that the visual system represents color ensembles in a more detailed way than previously thought, coding not only mean and variance but, most surprisingly, the actual shape (uniform or Gaussian) of the distribution of colors in the environment.

Trapping of Neutrinos in Extremely Compact Stars and the Influence of Brane Tension on This Process

NASA Astrophysics Data System (ADS)

Stuchlík, Zdenäěk; Hladík, Jan; Urbanec, Martin

We present estimates on the efficiency of neutrino trapping in brany extremely compact stars, using the simplest model with uniform distribution of energy density, assuming massless neutrinos and uniform distribution of neutrino emissivity. Computation have been done for two different uniform-density stellar solution in the Randall-Sundrum II type braneworld, namely with the Reissner-Nordström-type of geometry and the second one, derived by Germani and Maartens.1

Frequency graded 1D metamaterials: A study on the attenuation bands

NASA Astrophysics Data System (ADS)

Banerjee, Arnab; Das, Raj; Calius, Emilio P.

2017-08-01

Depending on the frequency, waves can either propagate (transmission band) or be attenuated (attenuation band) while travelling through a one-dimensional spring-mass chain with internal resonators. The literature on wave propagation through a 1D mass-in-mass chain is vast and continues to proliferate because of its versatile applicability in condensed matter physics, optics, chemistry, acoustics, and mechanics. However, in all these areas, a uniformly periodic arrangement of identical linear resonating units is normally used which limits the attenuation band to a narrow frequency range. To counter this limitation of linear uniformly periodic metamaterials, the attenuation bandwidth in a one-dimensional finite chain with frequency graded linear internal resonators are investigated in this paper. The result shows that a properly tuned frequency graded arrangement of resonating units can extend the upper part of the attenuation band of 1D metamaterial theoretically up to infinity and also increases the lower part of the attenuation bandwidth by around 40% of an equivalent uniformly periodic metamaterial without increasing the mass. Therefore, the frequency graded metamaterials can be a potential solution towards low frequency and wideband acoustic or vibration insulation. In addition, this paper provides analytical expressions for the attenuation and transmission frequency limits for a periodic mass-in-mass metamaterial and demonstrates the attenuation band is generated by the high absolute value of the effective mass not only due to the negative effective mass.

Estimating recharge at Yucca Mountain, Nevada, USA: Comparison of methods

USGS Publications Warehouse

Flint, A.L.; Flint, L.E.; Kwicklis, E.M.; Fabryka-Martin, J. T.; Bodvarsson, G.S.

2002-01-01

Obtaining values of net infiltration, groundwater travel time, and recharge is necessary at the Yucca Mountain site, Nevada, USA, in order to evaluate the expected performance of a potential repository as a containment system for high-level radioactive waste. However, the geologic complexities of this site, its low precipitation and net infiltration, with numerous mechanisms operating simultaneously to move water through the system, provide many challenges for the estimation of the spatial distribution of recharge. A variety of methods appropriate for arid environments has been applied, including water-balance techniques, calculations using Darcy's law in the unsaturated zone, a soil-physics method applied to neutron-hole water-content data, inverse modeling of thermal profiles in boreholes extending through the thick unsaturated zone, chloride mass balance, atmospheric radionuclides, and empirical approaches. These methods indicate that near-surface infiltration rates at Yucca Mountain are highly variable in time and space, with local (point) values ranging from zero to several hundred millimeters per year. Spatially distributed net-infiltration values average 5 mm/year, with the highest values approaching 20 mm/year near Yucca Crest. Site-scale recharge estimates range from less than 1 to about 12 mm/year. These results have been incorporated into a site-scale model that has been calibrated using these data sets that reflect infiltration processes acting on highly variable temporal and spatial scales. The modeling study predicts highly non-uniform recharge at the water table, distributed significantly differently from the non-uniform infiltration pattern at the surface.

Experimental Research on Optimizing Inlet Airflow of Wet Cooling Towers under Crosswind Conditions

NASA Astrophysics Data System (ADS)

Chen, You Liang; Shi, Yong Feng; Hao, Jian Gang; Chang, Hao; Sun, Feng Zhong

2018-01-01

A new approach of installing air deflectors around tower inlet circumferentially was proposed to optimize the inlet airflow and reduce the adverse effect of crosswinds on the thermal performance of natural draft wet cooling towers (NDWCT). And inlet airflow uniformity coefficient was defined to analyze the uniformity of circumferential inlet airflow quantitatively. Then the effect of air deflectors on the NDWCT performance was investigated experimentally. By contrast between inlet air flow rate and cooling efficiency, it has been found that crosswinds not only decrease the inlet air flow rate, but also reduce the uniformity of inlet airflow, which reduce NDWCT performance jointly. After installing air deflectors, the inlet air flow rate and uniformity coefficient increase, the uniformity of heat and mass transfer increases correspondingly, which improve the cooling performance. In addition, analysis on Lewis factor demonstrates that the inlet airflow optimization has more enhancement of heat transfer than mass transfer, but leads to more water evaporation loss.

Distribution of active faulting along orogenic wedges: Minimum-work models and natural analogue

NASA Astrophysics Data System (ADS)

Yagupsky, Daniel L.; Brooks, Benjamin A.; Whipple, Kelin X.; Duncan, Christopher C.; Bevis, Michael

2014-09-01

Numerical 2-D models based on the principle of minimum work were used to examine the space-time distribution of active faulting during the evolution of orogenic wedges. A series of models focused on thin-skinned thrusting illustrates the effects of arid conditions (no erosion), unsteady state conditions (accretionary influx greater than erosional efflux) and steady state conditions (accretionary influx balances erosional efflux), on the distribution of fault activity. For arid settings, a general forward accretion sequence prevails, although a significant amount of internal deformation is registered: the resulting fault pattern is a rather uniform spread along the profile. Under fixed erosional efficiency settings, the frontal advance of the wedge-front is inhibited, reaching a steady state after a given forward propagation. Then, the applied shortening is consumed by surface ruptures over a narrow frontal zone. Under a temporal increase in erosional efficiency (i.e., transient non-steady state mass balance conditions), a narrowing of the synthetic wedge results; a rather diffuse fault activity distribution is observed during the deformation front retreat. Once steady balanced conditions are reached, a single long-lived deformation front prevails. Fault activity distribution produced during the deformation front retreat of the latter scenario, compares well with the structural evolution and hinterlandward deformation migration identified in southern Bolivian Subandes (SSA) from late Miocene to present. This analogy supports the notion that the SSA is not in steady state, but is rather responding to an erosional efficiency increase since late Miocene. The results shed light on the impact of different mass balance conditions on the vastly different kinematics found in mountain ranges, suggesting that those affected by growing erosion under a transient unbalanced mass flux condition tend to distribute deformation along both frontal and internal faults, while others under balanced conditions would display focused deformation on a limited number of steady structures.

High density, uniformly distributed W/UO2 for use in Nuclear Thermal Propulsion

NASA Astrophysics Data System (ADS)

Tucker, Dennis S.; Barnes, Marvin W.; Hone, Lance; Cook, Steven

2017-04-01

An inexpensive, quick method has been developed to obtain uniform distributions of UO2 particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO2 particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

Distributed Pore Chemistry in Porous Organic Polymers

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

1999-01-01

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge. wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions. and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Distributed Pore Chemistry in Porous Organic Polymers in Tissue Culture Flasks

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

1999-01-01

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclose. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Distributed Pore Chemistry in Porous Organic Polymers

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

1998-01-01

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The sub-strate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphorylcholine groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic region, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Studying Star Formation in the Central Molecular Zone using 22 GHz Water and 6.7 GHz Methanol Masers

NASA Astrophysics Data System (ADS)

Rickert, Matthew; Yusef-Zadeh, Farhad; Ott, Juergen; Meier, David S.; SWAG

2016-01-01

The inner 400 pc of our Galaxy, or the so-called the central molecular zone (CMZ), has a unique environment with a large mass of dense, warm molecular gas. One of the premier questions is how star formation (SF) differs in this unique environment from elsewhere in the Galaxy. We intend to address this issue by identifying improved numbers and locations of early sites of SF. We have conducted high resolution surveys of the CMZ, looking for early SF indicators such as 22 GHz water and 6.7 GHz methanol masers. We present the initial water maser results from the SWAG survey and methanol results from the first full VLA survey of 6.7 GHz methanol masers in the CMZ. These surveys span beyond the inner 1.2ο x 0.5ο of the Galaxy, including Sgr B through Sgr C. The improved spatial and spectral resolutions (~26" and 2 km s-1) and sensitivity (RMS ~10 mJy beam-1) of our ATCA observations have allowed us to identify over 140 water maser candidates in the SWAG survey. This is a factor of 3 more than detected from prior surveys of the CMZ. The preliminary distribution of these candidates appears to be uniform along Galactic longitude. Should this distribution persist for water masers associated with star formation (as opposed to those produced by evolved stars), then this result would imply a more uniform distribution of recent SF activity in the CMZ. Prior works have shown that 2/3 of the molecular gas mass is located at positive Galactic longitudes, and young stellar objects (YSOs) identified by IR SEDs are located predominantly at negative Galactic longitudes. A combination of these results can provide insight on the evolution of SF within the CMZ. We are currently comparing the water maser positions to other catalogs (ex. OH/IR stars) in order to distinguish between the mechanisms producing these masers. We are also currently working on determining the distribution of 6.7 GHz methanol masers. These masers do not contain the same ambiguity as water masers as to their source and are only produced by high mass star formation. Finally we have also conducted the first on-the-fly (OTF) VLA survey of 22 GHz water masers spanning the inner 2.0ο x 0.5ο, with 0.3" and 0.4 km s-1 spatial and spectral resolutions.

Passive containment cooling water distribution device

DOEpatents

Conway, Lawrence E.; Fanto, Susan V.

1994-01-01

A passive containment cooling system for a nuclear reactor containment vessel. Disclosed is a cooling water distribution system for introducing cooling water by gravity uniformly over the outer surface of a steel containment vessel using a series of radial guide elements and cascading weir boxes to collect and then distribute the cooling water into a series of distribution areas through a plurality of cascading weirs. The cooling water is then uniformly distributed over the curved surface by a plurality of weir notches in the face plate of the weir box.

Optimal design and management of chlorination in drinking water networks: a multi-objective approach using Genetic Algorithms and the Pareto optimality concept

NASA Astrophysics Data System (ADS)

Nouiri, Issam

2017-11-01

This paper presents the development of multi-objective Genetic Algorithms to optimize chlorination design and management in drinking water networks (DWN). Three objectives have been considered: the improvement of the chlorination uniformity (healthy objective), the minimization of chlorine booster stations number, and the injected chlorine mass (economic objectives). The problem has been dissociated in medium and short terms ones. The proposed methodology was tested on hypothetical and real DWN. Results proved the ability of the developed optimization tool to identify relationships between the healthy and economic objectives as Pareto fronts. The proposed approach was efficient in computing solutions ensuring better chlorination uniformity while requiring the weakest injected chlorine mass when compared to other approaches. For the real DWN studied, chlorination optimization has been crowned by great improvement of free-chlorine-dosing uniformity and by a meaningful chlorine mass reduction, in comparison with the conventional chlorination.

Passive shimming of a superconducting magnet using the L1-norm regularized least square algorithm.

PubMed

Kong, Xia; Zhu, Minhua; Xia, Ling; Wang, Qiuliang; Li, Yi; Zhu, Xuchen; Liu, Feng; Crozier, Stuart

2016-02-01

The uniformity of the static magnetic field B0 is of prime importance for an MRI system. The passive shimming technique is usually applied to improve the uniformity of the static field by optimizing the layout of a series of steel shims. The steel pieces are fixed in the drawers in the inner bore of the superconducting magnet, and produce a magnetizing field in the imaging region to compensate for the inhomogeneity of the B0 field. In practice, the total mass of steel used for shimming should be minimized, in addition to the field uniformity requirement. This is because the presence of steel shims may introduce a thermal stability problem. The passive shimming procedure is typically realized using the linear programming (LP) method. The LP approach however, is generally slow and also has difficulty balancing the field quality and the total amount of steel for shimming. In this paper, we have developed a new algorithm that is better able to balance the dual constraints of field uniformity and the total mass of the shims. The least square method is used to minimize the magnetic field inhomogeneity over the imaging surface with the total mass of steel being controlled by an L1-norm based constraint. The proposed algorithm has been tested with practical field data, and the results show that, with similar computational cost and mass of shim material, the new algorithm achieves superior field uniformity (43% better for the test case) compared with the conventional linear programming approach. Copyright © 2016 Elsevier Inc. All rights reserved.

Eye safety analysis for non-uniform retinal scanning laser trajectories

NASA Astrophysics Data System (ADS)

Schelinski, Uwe; Dallmann, Hans-Georg; Grüger, Heinrich; Knobbe, Jens; Pügner, Tino; Reinig, Peter; Woittennek, Franziska

2016-03-01

Scanning the retinae of the human eyes with a laser beam is an approved diagnosis method in ophthalmology; moreover the retinal blood vessels form a biometric modality for identifying persons. Medical applied Scanning Laser Ophthalmoscopes (SLOs) usually contain galvanometric mirror systems to move the laser spot with a defined speed across the retina. Hence, the load of laser radiation is uniformly distributed and eye safety requirements can be easily complied. Micro machined mirrors also known as Micro Electro Mechanical Systems (MEMS) are interesting alternatives for designing retina scanning systems. In particular double-resonant MEMS are well suited for mass fabrication at low cost. However, their Lissajous-shaped scanning figure requires a particular analysis and specific measures to meet the requirements for a Class 1 laser device, i.e. eye-safe operation. The scanning laser spot causes a non-uniform pulsing radiation load hitting the retinal elements within the field of view (FoV). The relevant laser safety standards define a smallest considerable element for eye-related impacts to be a point source that is visible with an angle of maximum 1.5 mrad. For non-uniform pulsing expositions onto retinal elements the standard requires to consider all particular impacts, i.e. single pulses, pulse sequences in certain time intervals and cumulated laser radiation loads. As it may be expected, a Lissajous scanning figure causes the most critical radiation loads at its edges and borders. Depending on the applied power the laser has to be switched off here to avoid any retinal injury.

Computer simulation for improving radio frequency (RF) heating uniformity of food products: A review.

PubMed

Huang, Zhi; Marra, Francesco; Subbiah, Jeyamkondan; Wang, Shaojin

2018-04-13

Radio frequency (RF) heating has great potential for achieving rapid and volumetric heating in foods, providing safe and high-quality food products due to deep penetration depth, moisture self-balance effects, and leaving no chemical residues. However, the nonuniform heating problem (usually resulting in hot and cold spots in the heated product) needs to be resolved. The inhomogeneous temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms or insects may not be controlled in the cold spots. The mathematical modeling for RF heating processes has been extensively studied in a wide variety of agricultural products recently. This paper presents a comprehensive review of recent progresses in computer simulation for RF heating uniformity improvement and the offered solutions to reduce the heating nonuniformity. It provides a brief introduction on the basic principle of RF heating technology, analyzes the applications of numerical simulation, and discusses the factors influencing the RF heating uniformity and the possible methods to improve heating uniformity. Mathematical modeling improves the understanding of RF heating of food and is essential to optimize the RF treatment protocol for pasteurization and disinfestation applications. Recommendations for future research have been proposed to further improve the accuracy of numerical models, by covering both heat and mass transfers in the model, validating these models with sample movement and mixing, and identifying the important model parameters by sensitivity analysis.

Global deformation of the Earth, surface mass anomalies, and the geodetic infrastructure required to study these processes

NASA Astrophysics Data System (ADS)

Kusche, J.; Rietbroek, R.; Gunter, B.; Mark-Willem, J.

2008-12-01

Global deformation of the Earth can be linked to loading caused by mass changes in the atmosphere, the ocean and the terrestrial hydrosphere. World-wide geodetic observation systems like GPS, e.g., the global IGS network, can be used to study the global deformation of the Earth directly and, when other effects are properly modeled, provide information regarding the surface loading mass (e.g., to derive geo-center motion estimates). Vice versa, other observing systems that monitor mass change, either through gravitational changes (GRACE) or through a combination of in-situ and modeled quantities (e.g., the atmosphere, ocean or hydrosphere), can provide indirect information on global deformation. In the framework of the German 'Mass transport and mass distribution' program, we estimate surface mass anomalies at spherical harmonic resolution up to degree and order 30 by linking three complementary data sets in a least squares approach. Our estimates include geo-center motion and the thickness of a spatially uniform layer on top of the ocean surface (that is otherwise estimated from surface fluxes, evaporation and precipitation, and river run-off) as a time-series. As with all current Earth observing systems, each dataset has its own limitations and do not realize homogeneous coverage over the globe. To assess the impact that these limitations might have on current and future deformation and loading mass solutions, a sensitivity study was conducted. Simulated real-case and idealized solutions were explored in which the spatial distribution and quality of GPS, GRACE and OBP data sets were varied. The results show that significant improvements, e.g., over the current GRACE monthly gravity fields, in particular at the low degrees, can be achieved when these solutions are combined with present day GPS and OBP products. Our idealized scenarios also provide quantitative implications on how much surface mass change estimates may improve in the future when improved observing systems become available.

Rapid mass segregation in small stellar clusters

NASA Astrophysics Data System (ADS)

Spera, Mario; Capuzzo-Dolcetta, Roberto

2017-12-01

In this paper we focus our attention on small-to-intermediate N-body systems that are, initially, distributed uniformly in space and dynamically `cool' (virial ratios Q=2T/|Ω| below ˜0.3). In this work, we study the mass segregation that emerges after the initial violent dynamical evolution. At this scope, we ran a set of high precision N-body simulations of isolated clusters by means of HiGPUs, our direct summation N-body code. After the collapse, the system shows a clear mass segregation. This (quick) mass segregation occurs in two phases: the first shows up in clumps originated by sub-fragmentation before the deep overall collapse; this segregation is partly erased during the deep collapse to re-emerge, abruptly, during the second phase, that follows the first bounce of the system. In this second stage, the proper clock to measure the rate of segregation is the dynamical time after virialization, which (for cold and cool systems) may be significantly different from the crossing time evaluated from initial conditions. This result is obtained for isolated clusters composed of stars of two different masses (in the ratio mh/ml=2), at varying their number ratio, and is confirmed also in presence of a massive central object (simulating a black hole of stellar size). Actually, in stellar systems starting their dynamical evolution from cool conditions, the fast mass segregation adds to the following, slow, secular segregation which is collisionally induced. The violent mass segregation is an effect persistent over the whole range of N (128 ≤ N ≤1,024) investigated, and is an interesting feature on the astronomical-observational side, too. The semi-steady state reached after virialization corresponds to a mass segregated distribution function rather than that of equipartition of kinetic energy per unit mass as it should result from violent relaxation.

Uniform Sampling Table Method and its Applications II--Evaluating the Uniform Sampling by Experiment.

PubMed

Chen, Yibin; Chen, Jiaxi; Chen, Xuan; Wang, Min; Wang, Wei

2015-01-01

A new method of uniform sampling is evaluated in this paper. The items and indexes were adopted to evaluate the rationality of the uniform sampling. The evaluation items included convenience of operation, uniformity of sampling site distribution, and accuracy and precision of measured results. The evaluation indexes included operational complexity, occupation rate of sampling site in a row and column, relative accuracy of pill weight, and relative deviation of pill weight. They were obtained from three kinds of drugs with different shape and size by four kinds of sampling methods. Gray correlation analysis was adopted to make the comprehensive evaluation by comparing it with the standard method. The experimental results showed that the convenience of uniform sampling method was 1 (100%), odds ratio of occupation rate in a row and column was infinity, relative accuracy was 99.50-99.89%, reproducibility RSD was 0.45-0.89%, and weighted incidence degree exceeded the standard method. Hence, the uniform sampling method was easy to operate, and the selected samples were distributed uniformly. The experimental results demonstrated that the uniform sampling method has good accuracy and reproducibility, which can be put into use in drugs analysis.

Size distribution of ions in atmospheric aerosols

NASA Astrophysics Data System (ADS)

Krivácsy, Z.; Molnár, Á.

The aim of this paper is to present data about the concentration and size distribution of ions in atmospheric aerosol under slightly polluted urban conditions in Hungary. Concentration of inorganic cations (ammonium, sodium, potassium, calcium, magnesium), inorganic anions (sulfate, nitrate, chloride, carbonate) and organic acids (oxalic, malonic, succinic, formic and acetic acid) for 8 particle size range between 0.0625 and 16 μm were determined. As was the case for ammonium, sulfate and nitrate, the organic acids were mostly found in the fine particle size range. Potassium and chloride were rather uniformly distributed between fine and coarse particles. Sodium, calcium, magnesium and carbonate were practically observed in the coarse mode. The results obtained for the summer and the winter half-year were also compared. The mass concentrations were recalculated in equivalents, and the ion balance was found to be reasonable in most cases. Measurement of the pH of the aerosol extracts indicates that the aerosol is acidic in the fine mode, but alkaline in the coarse particle size range.

Preconditioned wire array Z-pinches driven by a double pulse current generator

NASA Astrophysics Data System (ADS)

Wu, Jian; Lu, Yihan; Sun, Fengju; Li, Xingwen; Jiang, Xiaofeng; Wang, Zhiguo; Zhang, Daoyuan; Qiu, Aici; Lebedev, Sergey

2018-07-01

Suppression of the core-corona structure and wire ablation in wire array Z-pinches is investigated using a novel double pulse current generator ‘Qin-1’ facility. The ‘Qin-1’ facility allows coupling a ∼10 kA 20 ns prepulse generator with a ∼0.8 MA 160 ns main current generator. The tailored prepulse current preheats wires to a gaseous state and the time interval between the prepulse and the main current pulse allows formation of a more uniform mass distribution for the implosion. The implosion of a gasified two aluminum-wire array showed no ablation phase and allowed all array mass to participate in the implosion. The initial perturbations formed from the inhomogeneous ablation were suppressed, however, the magneto Rayleigh–Taylor (MRT) instability during the implosion was still significant and further researches on the generation and development of the MRT instabilities of this gasified wire array are needed.

The vibration characteristics of a coupled helicopter rotor-fuselage by a finite element analysis

NASA Technical Reports Server (NTRS)

Rutkowski, M. J.

1983-01-01

The dynamic coupling between the rotor system and the fuselage of a simplified helicopter model in hover was analytically investigated. Mass, aerodynamic damping, and elastic and centrifugal stiffness matrices are presented for the analytical model; the model is based on a beam finite element, with polynomial mass and stiffness distributions for both the rotor and fuselage representations. For this analytical model, only symmetric fuselage and collective blade degrees of freedom are treated. Real and complex eigen-analyses are carried out to obtain coupled rotor-fuselage natural modes and frequencies as a function of rotor speed. Vibration response results are obtained for the coupled system subjected to a radially uniform, harmonic blade loading. The coupled response results are compared with response results from an uncoupled analysis in which hub loads for an isolated rotor system subjected to the same sinusoidal blade loading as the coupled system are applied to a free-free fuselage.

Method for forming an in situ oil shale retort with horizontal free faces

DOEpatents

Ricketts, Thomas E.; Fernandes, Robert J.

1983-01-01

A method for forming a fragmented permeable mass of formation particles in an in situ oil shale retort is provided. A horizontally extending void is excavated in unfragmented formation containing oil shale and a zone of unfragmented formation is left adjacent the void. An array of explosive charges is formed in the zone of unfragmented formation. The array of explosive charges comprises rows of central explosive charges surrounded by a band of outer explosive charges which are adjacent side boundaries of the retort being formed. The powder factor of each outer explosive charge is made about equal to the powder factor of each central explosive charge. The explosive charges are detonated for explosively expanding the zone of unfragmented formation toward the void for forming the fragmented permeable mass of formation particles having a reasonably uniformly distributed void fraction in the in situ oil shale retort.

Stacked waveguide reactors with gradient embedded scatterers for high-capacity water cleaning

DOE PAGES

Ahsan, Syed Saad; Gumus, Abdurrahman; Erickson, David

2015-11-04

We present a compact water-cleaning reactor with stacked layers of waveguides containing gradient patterns of optical scatterers that enable uniform light distribution and augmented water-cleaning rates. Previous photocatalytic reactors using immersion, external, or distributive lamps suffer from poor light distribution that impedes scalability. Here, we use an external UV-source to direct photons into stacked waveguide reactors where we scatter the photons uniformly over the length of the waveguide to thin films of TiO 2-catalysts. In conclusion, we also show 4.5 times improvement in activity over uniform scatterer designs, demonstrate a degradation of 67% of the organic dye, and characterize themore » degradation rate constant.« less

Stacked waveguide reactors with gradient embedded scatterers for high-capacity water cleaning

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

Ahsan, Syed Saad; Gumus, Abdurrahman; Erickson, David

We present a compact water-cleaning reactor with stacked layers of waveguides containing gradient patterns of optical scatterers that enable uniform light distribution and augmented water-cleaning rates. Previous photocatalytic reactors using immersion, external, or distributive lamps suffer from poor light distribution that impedes scalability. Here, we use an external UV-source to direct photons into stacked waveguide reactors where we scatter the photons uniformly over the length of the waveguide to thin films of TiO 2-catalysts. In conclusion, we also show 4.5 times improvement in activity over uniform scatterer designs, demonstrate a degradation of 67% of the organic dye, and characterize themore » degradation rate constant.« less

Engineered surface scatterers in edge-lit slab waveguides to improve light delivery in algae cultivation.

PubMed

Ahsan, Syed Saad; Pereyra, Brandon; Jung, Erica E; Erickson, David

2014-10-20

Most existing photobioreactors do a poor job of distributing light uniformly due to shading effects. One method by which this could be improved is through the use of internal wave-guiding structures incorporating engineered light scattering schemes. By varying the density of these scatterers, one can control the spatial distribution of light inside the reactor enabling better uniformity of illumination. Here, we compare a number of light scattering schemes and evaluate their ability to enhance biomass accumulation. We demonstrate a design for a gradient distribution of surface scatterers with uniform lateral scattering intensity that is superior for algal biomass accumulation, resulting in a 40% increase in the growth rate.

Elastic field of a spherical inclusion with non-uniform eigenfields in second strain gradient elasticity

NASA Astrophysics Data System (ADS)

Delfani, M. R.; Latifi Shahandashti, M.

2017-09-01

In this paper, within the complete form of Mindlin's second strain gradient theory, the elastic field of an isolated spherical inclusion embedded in an infinitely extended homogeneous isotropic medium due to a non-uniform distribution of eigenfields is determined. These eigenfields, in addition to eigenstrain, comprise eigen double and eigen triple strains. After the derivation of a closed-form expression for Green's function associated with the problem, two different cases of non-uniform distribution of the eigenfields are considered as follows: (i) radial distribution, i.e. the distributions of the eigenfields are functions of only the radial distance of points from the centre of inclusion, and (ii) polynomial distribution, i.e. the distributions of the eigenfields are polynomial functions in the Cartesian coordinates of points. While the obtained solution for the elastic field of the latter case takes the form of an infinite series, the solution to the former case is represented in a closed form. Moreover, Eshelby's tensors associated with the two mentioned cases are obtained.

THE SWIFT GRB HOST GALAXY LEGACY SURVEY. II. REST-FRAME NEAR-IR LUMINOSITY DISTRIBUTION AND EVIDENCE FOR A NEAR-SOLAR METALLICITY THRESHOLD

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

Perley, D. A.; Tanvir, N. R.; Hjorth, J.

2016-01-20

We present rest-frame near-IR (NIR) luminosities and stellar masses for a large and uniformly selected population of gamma-ray burst (GRB) host galaxies using deep Spitzer Space Telescope imaging of 119 targets from the Swift GRB Host Galaxy Legacy Survey spanning 0.03 < z < 6.3, and we determine the effects of galaxy evolution and chemical enrichment on the mass distribution of the GRB host population across cosmic history. We find a rapid increase in the characteristic NIR host luminosity between z ∼ 0.5 and z ∼ 1.5, but little variation between z ∼ 1.5 and z ∼ 5. Dust-obscured GRBs dominate the massive host population but are only rarely seen associated withmore » low-mass hosts, indicating that massive star-forming galaxies are universally and (to some extent) homogeneously dusty at high redshift while low-mass star-forming galaxies retain little dust in their interstellar medium. Comparing our luminosity distributions with field surveys and measurements of the high-z mass–metallicity relation, our results have good consistency with a model in which the GRB rate per unit star formation is constant in galaxies with gas-phase metallicity below approximately the solar value but heavily suppressed in more metal-rich environments. This model also naturally explains the previously reported “excess” in the GRB rate beyond z ≳ 2; metals stifle GRB production in most galaxies at z < 1.5 but have only minor impact at higher redshifts. The metallicity threshold we infer is much higher than predicted by single-star models and favors a binary progenitor. Our observations also constrain the fraction of cosmic star formation in low-mass galaxies undetectable to Spitzer to be small at z < 4.« less

The Impact of Uncertain Physical Parameters on HVAC Demand Response

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

Sun, Yannan; Elizondo, Marcelo A.; Lu, Shuai

HVAC units are currently one of the major resources providing demand response (DR) in residential buildings. Models of HVAC with DR function can improve understanding of its impact on power system operations and facilitate the deployment of DR technologies. This paper investigates the importance of various physical parameters and their distributions to the HVAC response to DR signals, which is a key step to the construction of HVAC models for a population of units with insufficient data. These parameters include the size of floors, insulation efficiency, the amount of solid mass in the house, and efficiency of the HVAC units.more » These parameters are usually assumed to follow Gaussian or Uniform distributions. We study the effect of uncertainty in the chosen parameter distributions on the aggregate HVAC response to DR signals, during transient phase and in steady state. We use a quasi-Monte Carlo sampling method with linear regression and Prony analysis to evaluate sensitivity of DR output to the uncertainty in the distribution parameters. The significance ranking on the uncertainty sources is given for future guidance in the modeling of HVAC demand response.« less

Simulation of radial solute segregation in vertical Bridgman growth of pyridine-doped benzene, a surrogate for binary organic nonlinear optical materials

NASA Astrophysics Data System (ADS)

Lee, Hanjie; Pearlstein, Arne J.

2000-09-01

We present steady axisymmetric computations of solute distributions and radial segregation for vertical Bridgman growth of pyridine-doped benzene, a binary aromatic system with anisotropic solid-phase thermal conductivity, that serves as a model of solute transport in crystal growth of organic nonlinear optical materials. The radial variation of solid-phase mass fraction ( Cs) of pyridine, which is rejected at the growing interface, depends strongly on growth conditions. High growth velocities tend to increase Cs near the centerline, the ampoule wall, or both, and low growth velocities give more nearly uniform radial distributions. The maximum ampoule-wall temperature gradient also affects radial segregation, with convex-to-the-liquid interfaces at small temperature gradients being associated with radially monotonic Cs distributions, and ridged interfaces at higher gradients being associated with nonmonotonic distributions having maxima at the centerline and ampoule wall. Nonuniformity is strongly determined by both interface shape and the nature of the flow near the interface. Solute is transported down to the interface by a large toroidal vortex, and swept radially inward to the centerline by a second, flattened toroidal cell. When the interface is depressed at its junction with the ampoule wall, rejected solute accumulates in the overlying liquid, where convection is relatively weak, resulting in local solute enrichment of the solid. Computations at normal and zero gravity show that for two very similar interface shapes, a maximum in the radial solid-phase solute distribution at the ampoule wall is associated with the interface shape, while the maximum on the centerline is associated with sweeping of solute to the centerline by a vortical flow on the interface. We also show that radial solute segregation depends significantly on whether account is taken of the anisotropy of the solid-phase thermal conductivity. Finally, the computations provide guidance as to the minimum ampoule length required to produce an axially uniform solute distribution over at least part of the length of a boule.

Investigation on inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet

NASA Astrophysics Data System (ADS)

Yang, Ce; Wang, Yingjun; Lao, Dazhong; Tong, Ding; Wei, Longyu; Liu, Yixiong

2016-08-01

The inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet structures were studied in numerical method, mainly focused on three issues including the amounts and differences of the inlet recirculation in different working conditions, the circumferential non-uniform distributions of the inlet recirculation, the recirculation velocity distributions of the upstream slot of the rear impeller. The results show that there are some differences between the recirculation of the front impeller and that of the rear impeller in whole working conditions. In design speed, the recirculation flow rate of the rear impeller is larger than that of the front impeller in the large flow range, but in the small flow range, the recirculation flow rate of the rear impeller is smaller than that of the front impeller. In different working conditions, the recirculation velocity distributions of the front and rear impeller are non-uniform along the circumferential direction and their non-uniform extents are quite different. The circumferential non-uniform extent of the recirculation velocity varies with the working conditions change. The circumferential non-uniform extent of the recirculation velocity of front impeller and its distribution are determined by the static pressure distribution of the front impeller, but that of the rear impeller is decided by the coupling effects of the inlet flow distortion of the rear impeller, the circumferential unsymmetrical distribution of the upstream slot and the asymmetric structure of the volute. In the design flow and small flow conditions, the recirculation velocities at different circumferential positions of the mean line of the upstream slot cross-section of the rear impeller are quite different, and the recirculation velocities distribution forms at both sides of the mean line are different. The recirculation velocity distributions in the cross-section of the upstream slot depend on the static pressure distributions in the intake duct.

Local Burn-Up Effects in the NBSR Fuel Element

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

Brown N. R.; Hanson A.; Diamond, D.

2013-01-31

This study addresses the over-prediction of local power when the burn-up distribution in each half-element of the NBSR is assumed to be uniform. A single-element model was utilized to quantify the impact of axial and plate-wise burn-up on the power distribution within the NBSR fuel elements for both high-enriched uranium (HEU) and low-enriched uranium (LEU) fuel. To validate this approach, key parameters in the single-element model were compared to parameters from an equilibrium core model, including neutron energy spectrum, power distribution, and integral U-235 vector. The power distribution changes significantly when incorporating local burn-up effects and has lower power peakingmore » relative to the uniform burn-up case. In the uniform burn-up case, the axial relative power peaking is over-predicted by as much as 59% in the HEU single-element and 46% in the LEU single-element with uniform burn-up. In the uniform burn-up case, the plate-wise power peaking is over-predicted by as much as 23% in the HEU single-element and 18% in the LEU single-element. The degree of over-prediction increases as a function of burn-up cycle, with the greatest over-prediction at the end of Cycle 8. The thermal flux peak is always in the mid-plane gap; this causes the local cumulative burn-up near the mid-plane gap to be significantly higher than the fuel element average. Uniform burn-up distribution throughout a half-element also causes a bias in fuel element reactivity worth, due primarily to the neutronic importance of the fissile inventory in the mid-plane gap region.« less

STARS DO NOT EAT THEIR YOUNG MIGRATING PLANETS: EMPIRICAL CONSTRAINTS ON PLANET MIGRATION HALTING MECHANISMS

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

Plavchan, Peter; Bilinski, Christopher

The discovery of ''hot Jupiters'' very close to their parent stars confirmed that Jovian planets migrate inward via several potential mechanisms. We present empirical constraints on planet migration halting mechanisms. We compute model density functions of close-in exoplanets in the orbital semi-major axis-stellar mass plane to represent planet migration that is halted via several mechanisms, including the interior 1:2 resonance with the magnetospheric disk truncation radius, the interior 1:2 resonance with the dust sublimation radius, and several scenarios for tidal halting. The models differ in the predicted power-law dependence of the exoplanet orbital semi-major axis as a function of stellarmore » mass, and thus we also include a power-law model with the exponent as a free parameter. We use a Bayesian analysis to assess the model success in reproducing empirical distributions of confirmed exoplanets and Kepler candidates that orbit interior to 0.1 AU. Our results confirm a correlation of the halting distance with stellar mass. Tidal halting provides the best fit to the empirical distribution of confirmed Jovian exoplanets at a statistically robust level, consistent with the Kozai mechanism and the spin-orbit misalignment of a substantial fraction of hot Jupiters. We can rule out migration halting at the interior 1:2 resonances with the magnetospheric disk truncation radius and the interior 1:2 resonance with the dust disk sublimation radius, a uniform random distribution, and a distribution with no dependence on stellar mass. Note that our results do not rule out Type-II migration, but rather eliminate the role of a circumstellar disk in stopping exoplanet migration. For Kepler candidates, which have a more restricted range in stellar mass compared to confirmed planets, we are unable to discern between the tidal dissipation and magnetospheric disk truncation braking mechanisms at a statistically significant level. The power-law model favors exponents in the range of 0.38-0.9. This is larger than that predicted for tidal halting (0.23-0.33), which suggests that additional physics may be missing in the tidal halting theory.« less

Modeling surface response of the Greenland Ice Sheet to interglacial climate

NASA Astrophysics Data System (ADS)

Rau, Dominik; Rogozhina, Irina

2013-04-01

We present a new parameterization of surface mass balance (SMB) of the Greenland Ice Sheet (GIS) under interglacial climate conditions validated against recent satellite observations on a regional scale. Based on detailed analysis of the modeled surface melting and refreezing rates, we conclude that the existing SMB parameterizations fail to capture either spatial pattern or amplitude of the observed surface response of the GIS. This is due to multiple simplifying assumptions adopted by the majority of modeling studies within the frame of the positive degree day method. Modeled spatial distribution of surface melting is found to be highly sensitive to a choice of daily temperature standard deviation (SD) and degree-day factors, which are generally assumed to have uniform distribution across the entire Greenland region. However, the use of uniform SD distribution and the range of commonly used SD values are absolutely unsupported by the ERA-40 and ERA-Interim climate data. In this region, SD distribution is highly inhomogeneous and characterized by low amplitudes during the summer months in the areas where most surface ice melting occurs. In addition, the use of identical degree day factors on both the eastern and western slopes of the GIS results in overestimation of surface runoff along the western coast of Greenland and significant underestimation along its eastern coast. Our approach is to make use of (i) spatially and seasonally variable SDs derived from ERA-40 and ERA-Interim time series, and (ii) spatially variable degree-day factors, measured across Greenland, Arctic Canada, Norway, Spitsbergen and Iceland. We demonstrate that the new approach is extremely efficient for modeling the evolution of the GIS during the observational period and the entire Holocene interglacial.

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

Duenas, Maria Emilia; Klein, Adam T.; Alexander, Liza E.

Metabolism in plants is compartmentalized among different tissues, cells and subcellular organelles. Mass spectrometry imaging (MSI) with matrix-assisted laser desorption ionization (MALDI) has recently advanced to allow for the visualization of metabolites at single-cell resolution. Here we applied 5- and 10 μm high spatial resolution MALDI-MSI to the asymmetric Kranz anatomy of Zea mays (maize) leaves to study the differential localization of two major anionic lipids in thylakoid membranes, sulfoquinovosyldiacylglycerols (SQDG) and phosphatidylglycerols (PG). The quantification and localization of SQDG and PG molecular species, among mesophyll (M) and bundle sheath (BS) cells, are compared across the leaf developmental gradient frommore » four maize genotypes (the inbreds B73 and Mo17, and the reciprocal hybrids B73 × Mo17 and Mo17 × B73). SQDG species are uniformly distributed in both photosynthetic cell types, regardless of leaf development or genotype; however, PG shows photosynthetic cell-specific differential localization depending on the genotype and the fatty acyl chain constituent. Overall, 16:1-containing PGs primarily contribute to the thylakoid membranes of M cells, whereas BS chloroplasts are mostly composed of 16:0-containing PGs. Furthermore, PG 32:0 shows genotype-specific differences in cellular distribution, with preferential localization in BS cells for B73, but more uniform distribution between BS and M cells in Mo17. Maternal inheritance is exhibited within the hybrids, such that the localization of PG 32:0 in B73 × Mo17 is similar to the distribution in the B73 parental inbred, whereas that of Mo17 × B73 resembles the Mo17 parent. As a result, this study demonstrates the power of MALDI-MSI to reveal unprecedented insights on metabolic outcomes in multicellular organisms at single-cell resolution.« less

Apparatus and process to enhance the uniform formation of hollow glass microspheres

DOEpatents

Schumacher, Ray F

2013-10-01

A process and apparatus is provided for enhancing the formation of a uniform population of hollow glass microspheres. A burner head is used which directs incoming glass particles away from the cooler perimeter of the flame cone of the gas burner and distributes the glass particles in a uniform manner throughout the more evenly heated portions of the flame zone. As a result, as the glass particles are softened and expand by a released nucleating gas so as to form a hollow glass microsphere, the resulting hollow glass microspheres have a more uniform size and property distribution as a result of experiencing a more homogenous heat treatment process.

Harnessing mass differential confinement effects in magnetized rotating plasmas to address new separation needs

NASA Astrophysics Data System (ADS)

Gueroult, R.; Rax, J.-M.; Zweben, S. J.; Fisch, N. J.

2018-01-01

The ability to separate large volumes of mixed species based on atomic mass appears desirable for a variety of emerging applications with high societal impact. One possibility to meet this objective consists in leveraging mass differential effects in rotating plasmas. Beyond conventional centrifugation, rotating plasmas offer in principle additional ways to separate elements based on mass. Single ion orbits show that ion radial mass separation in a uniform magnetized plasma column can be achieved by applying a tailored electric potential profile across the column, or by driving a rotating magnetic field within the column. Furthermore, magnetic pressure and centrifugal effects can be combined in a non-uniform geometry to separate ions based on mass along the field lines. Practical application of these separation schemes hinges on the ability to produce the desirable electric and magnetic field configuration within the plasma column.

Influence of a non-uniform free stream velocity distribution on performance/acoustics of counterrotating propeller configurations

NASA Astrophysics Data System (ADS)

Allen, C. S.; Korkan, K. D.

1991-01-01

A methodology for predicting the performance and acoustics of counterrotating propeller configurations was modified to take into account the effects of a non-uniform free stream velocity distribution entering the disk plane. The method utilizes the analytical techniques of Lock and Theodorson as described by Davidson to determine the influence of the non-uniform free stream velocity distribution in the prediction of the steady aerodynamic loads. The unsteady load contribution is determined according to the procedure of Leseture with rigid helical tip vortices simulating the previous rotations of each propeller. The steady and unsteady loads are combined to obtain the total blade loading required for acoustic prediction employing the Ffowcs Williams-Hawking equation as simplified by Succi with the assumption of compact sources. The numerical method is used to redesign the previous commuter class counterrotating propeller configuration of Denner. The specifications, performance, and acoustics of the new design are compared with the results of Denner thereby determining the influence of the non-uniform free stream velocity distribution on these metrics.

Leonid Storm Flux Analysis From One Leonid MAC Video AL50R

NASA Technical Reports Server (NTRS)

Gural, Peter S.; Jenniskens, Peter; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

A detailed meteor flux analysis is presented of a seventeen-minute portion of one videotape, collected on November 18, 1999, during the Leonid Multi-instrument Aircraft Campaign. The data was recorded around the peak of the Leonid meteor storm using an intensified CCD camera pointed towards the low southern horizon. Positions of meteors on the sky were measured. These measured meteor distributions were compared to a Monte Carlo simulation, which is a new approach to parameter estimation for mass ratio and flux. Comparison of simulated flux versus observed flux levels, seen between 1:50:00 and 2:06:41 UT, indicate a magnitude population index of r = 1.8 +/- 0.1 and mass ratio of s = 1.64 +/- 0.06. The average spatial density of the material contributing to the Leonid storm peak is measured at 0.82 +/- 0.19 particles per square kilometer per hour for particles of at least absolute visual magnitude +6.5. Clustering analysis of the arrival times of Leonids impacting the earth's atmosphere over the total observing interval shows no enhancement or clumping down to time scales of the video frame rate. This indicates a uniformly random temporal distribution of particles in the stream encountered during the 1999 epoch. Based on the observed distribution of meteors on the sky and the model distribution, recommendations am made for the optimal pointing directions for video camera meteor counts during future ground and airborne missions.

Distribution and regularity of injection from a multicylinder fuel-injection pump

NASA Technical Reports Server (NTRS)

Rothrock, A M; Marsh, E T

1936-01-01

This report presents the results of performance test conducted on a six-cylinder commercial fuel-injection pump that was adjusted to give uniform fuel distribution among the cylinders at a throttle setting of 0.00038 pound per injection and a pump speed of 750 revolutions per minute. The throttle setting and pump speed were then varied through the operating range to determine the uniformity of distribution and regularity of injection.

Flow coating apparatus and method of coating

DOEpatents

Hanumanthu, Ramasubrahmaniam; Neyman, Patrick; MacDonald, Niles; Brophy, Brenor; Kopczynski, Kevin; Nair, Wood

2014-03-11

Disclosed is a flow coating apparatus, comprising a slot that can dispense a coating material in an approximately uniform manner along a distribution blade that increases uniformity by means of surface tension and transfers the uniform flow of coating material onto an inclined substrate such as for example glass, solar panels, windows or part of an electronic display. Also disclosed is a method of flow coating a substrate using the apparatus such that the substrate is positioned correctly relative to the distribution blade, a pre-wetting step is completed where both the blade and substrate are completed wetted with a pre-wet solution prior to dispensing of the coating material onto the distribution blade from the slot and hence onto the substrate. Thereafter the substrate is removed from the distribution blade and allowed to dry, thereby forming a coating.

Continuous-variable quantum key distribution in uniform fast-fading channels

NASA Astrophysics Data System (ADS)

Papanastasiou, Panagiotis; Weedbrook, Christian; Pirandola, Stefano

2018-03-01

We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of uniform fading channels. These are lossy channels whose transmissivity changes according to a uniform probability distribution. We assume the worst-case scenario where an eavesdropper induces a fast-fading process, where she chooses the instantaneous transmissivity while the remote parties may only detect the mean statistical effect. We analyze coherent-state protocols in various configurations, including the one-way switching protocol in reverse reconciliation, the measurement-device-independent protocol in the symmetric configuration, and its extension to a three-party network. We show that, regardless of the advantage given to the eavesdropper (control of the fading), these protocols can still achieve high rates under realistic attacks, within reasonable values for the variance of the probability distribution associated with the fading process.

Spinning solutions in general relativity with infinite central density

NASA Astrophysics Data System (ADS)

Flammer, P. D.

2018-05-01

This paper presents general relativistic numerical simulations of uniformly rotating polytropes. Equations are developed using MSQI coordinates, but taking a logarithm of the radial coordinate. The result is relatively simple elliptical differential equations. Due to the logarithmic scale, we can resolve solutions with near-singular mass distributions near their center, while the solution domain extends many orders of magnitude larger than the radius of the distribution (to connect with flat space-time). Rotating solutions are found with very high central energy densities for a range of adiabatic exponents. Analytically, assuming the pressure is proportional to the energy density (which is true for polytropes in the limit of large energy density), we determine the small radius behavior of the metric potentials and energy density. This small radius behavior agrees well with the small radius behavior of large central density numerical results, lending confidence to our numerical approach. We compare results with rotating solutions available in the literature, which show good agreement. We study the stability of spherical solutions: instability sets in at the first maximum in mass versus central energy density; this is also consistent with results in the literature, and further lends confidence to the numerical approach.

Composite uranium carbide targets at TRIUMF: Development and characterization with SEM, XRD, XRF and L-edge densitometry

NASA Astrophysics Data System (ADS)

Kunz, Peter; Bricault, Pierre; Dombsky, Marik; Erdmann, Nicole; Hanemaayer, Vicky; Wong, John; Lützenkirchen, Klaus

2013-09-01

The production of radioactive ion beams (RIB) from spallation targets by irradiation with a continuous 500 MeV proton beam, has been routine at TRIUMF for several years. Based on the experience with composite refractory carbide targets a procedure for the fabrication of UC2/C targets was developed. It includes the preparation of UC2 by carbothermal reduction of UO2, the slip-casting of fine-grained UC2/C slurry on graphite foil under inert gas atmosphere and the cutting of composite target discs which are stacked up to a lamellar structure. The thermal properties of such an arrangement are adequate to withstand the high power deposition of an intense, continuous proton beam and also beneficial for the fast release of short-lived radioactive isotopes. Molecular structure, particle size and the impact of sintering of the target discs were investigated via XRD and SEM. Thickness and mass distribution were measured with position-sensitive LIII-edge densitometry. The results confirm that the properties of the UC2/C target material are well suited for RIB production at TRIUMF while there is still room for improvement with regard to uniformity of mass distribution in target disc thickness.

An overabundance of low-density Neptune-like planets

NASA Astrophysics Data System (ADS)

Cubillos, Patricio; Erkaev, Nikolai V.; Juvan, Ines; Fossati, Luca; Johnstone, Colin P.; Lammer, Helmut; Lendl, Monika; Odert, Petra; Kislyakova, Kristina G.

2017-04-01

We present a uniform analysis of the atmospheric escape rate of Neptune-like planets with estimated radius and mass (restricted to Mp < 30 M⊕). For each planet, we compute the restricted Jeans escape parameter, Λ, for a hydrogen atom evaluated at the planetary mass, radius, and equilibrium temperature. Values of Λ ≲ 20 suggest extremely high mass-loss rates. We identify 27 planets (out of 167) that are simultaneously consistent with hydrogen-dominated atmospheres and are expected to exhibit extreme mass-loss rates. We further estimate the mass-loss rates (Lhy) of these planets with tailored atmospheric hydrodynamic models. We compare Lhy to the energy-limited (maximum-possible high-energy driven) mass-loss rates. We confirm that 25 planets (15 per cent of the sample) exhibit extremely high mass-loss rates (Lhy > 0.1 M⌖ Gyr-1), well in excess of the energy-limited mass-loss rates. This constitutes a contradiction, since the hydrogen envelopes cannot be retained given the high mass-loss rates. We hypothesize that these planets are not truly under such high mass-loss rates. Instead, either hydrodynamic models overestimate the mass-loss rates, transit-timing-variation measurements underestimate the planetary masses, optical transit observations overestimate the planetary radii (due to high-altitude clouds), or Neptunes have consistently higher albedos than Jupiter planets. We conclude that at least one of these established estimations/techniques is consistently producing biased values for Neptune planets. Such an important fraction of exoplanets with misinterpreted parameters can significantly bias our view of populations studies, like the observed mass-radius distribution of exoplanets for example.

Experimental and numerical modeling research of rubber material during microwave heating process

NASA Astrophysics Data System (ADS)

Chen, Hailong; Li, Tao; Li, Kunling; Li, Qingling

2018-05-01

This paper aims to investigate the heating behaviors of block rubber by experimental and simulated method. The COMSOL Multiphysics 5.0 software was utilized in numerical simulation work. The effects of microwave frequency, power and sample size on temperature distribution are examined. The effect of frequency on temperature distribution is obvious. The maximum and minimum temperatures of block rubber increase first and then decrease with frequency increasing. The microwave heating efficiency is maximum in the microwave frequency of 2450 MHz. However, more uniform temperature distribution is presented in other microwave frequencies. The influence of microwave power on temperature distribution is also remarkable. The smaller the power, the more uniform the temperature distribution on the block rubber. The effect of power on microwave heating efficiency is not obvious. The effect of sample size on temperature distribution is evidently found. The smaller the sample size, the more uniform the temperature distribution on the block rubber. However, the smaller the sample size, the lower the microwave heating efficiency. The results can serve as references for the research on heating rubber material by microwave technology.

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

Sánchez-Salcedo, F. J.; Chametla, Raul O., E-mail: jsanchez@astro.unam.mx

Using time-dependent linear theory, we investigate the morphology of the gravitational wake induced by a binary, whose center of mass moves at velocity V{sub cm} against a uniform background of gas. For simplicity, we assume that the components of the binary are on circular orbits about their common center of mass. The consequences of dynamical friction is twofold. First, gas dynamical friction may drag the center of mass of the binary and cause the binary to migrate. Second, drag forces also induce a braking torque, which causes the orbits of the components of the binary to shrink. We compute themore » drag forces acting on one component of the binary due to the gravitational interaction with its own wake. We show that the dynamical friction force responsible for decelerating the center of mass of the binary is smaller than it is in the point-mass case because of the loss of gravitational focusing. We show that the braking internal torque depends on the Mach numbers of each binary component about their center of mass, and also on the Mach number of the center of mass of the binary. In general, the internal torque decreases with increasing the velocity of the binary relative to the ambient gas cloud. However, this is not always the case. We also mention the relevance of our results to the period distribution of binaries.« less

Post-processing of metal matrix composites by friction stir processing

NASA Astrophysics Data System (ADS)

Sharma, Vipin; Singla, Yogesh; Gupta, Yashpal; Raghuwanshi, Jitendra

2018-05-01

In metal matrix composites non-uniform distribution of reinforcement particles resulted in adverse affect on the mechanical properties. It is of great interest to explore post-processing techniques that can eliminate particle distribution heterogeneity. Friction stir processing is a relatively newer technique used for post-processing of metal matrix composites to improve homogeneity in particles distribution. In friction stir processing, synergistic effect of stirring, extrusion and forging resulted in refinement of grains, reduction of reinforcement particles size, uniformity in particles distribution, reduction in microstructural heterogeneity and elimination of defects.

Electrohydrodynamic simulation of an electrospray in a colloid thruster

NASA Astrophysics Data System (ADS)

Jugroot, Manish; Forget, Martin; Malardier-Jugroot, Cecile

2012-02-01

A precise understanding of electrosprays is highly interesting as the complexity of micro-technology (such as nano-material processing, spacecraft propulsion and mass-spectrometers) systems increases. A multi-component CFD-based model coupling fluid dynamics, charged species dynamics and electric field is developed. The simulations describe the charged fluid interface with emphasis on the Taylor cone formation and cone-jet transition under the effect of a electric field. The goal is to recapture this transition from a rounded liquid interface into a Taylor cone from an initial uniform distribution, without making assumptions on the behaviour, geometry or charge distribution of the system. The time evolution of the interface highlights the close interaction among space charge, coulombic forces and the surface tension, which appear as governing and competing processes in the transition. The results from the coupled formalism provide valuable insights on the physical phenomena and will be applied to a colloid thruster for small spacecrafts.

On the spray pulsations of the effervescent atomizers

NASA Astrophysics Data System (ADS)

Mlkvik, Marek; Knizat, Branislav

2018-06-01

The presented paper focuses on the comparison of the two effervescent atomizer configurations—the outside-in-gas (OIG) and the outside-in-liquid (OIL). The comparison was based on the spray pulsation assessment by different methods. The atomizers were tested under the same operating conditions given by the constant injection pressure (0.14 MPa) and the gas to the liquid mass ratio (GLR) varying from 2.5 to 5%. The aqueous maltodextrin solution was used as the working liquid (μ = 60 and 146 mPa·s). We found that the time-averaging method does not provide sufficient spray quality description. Based on the cumulative distribution function (CDF) we found that the OIG atomizer generated the spray with non-uniform droplet size distribution at all investigated GLRs. Exceptionally large droplets were present even in the spray which appeared stable when was analyzed by the time-averaging method.

Characterization of a 5-eV neutral atomic oxygen beam facility

NASA Technical Reports Server (NTRS)

Vaughn, J. A.; Linton, R. C.; Carruth, M. R., Jr.; Whitaker, A. F.; Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.

1991-01-01

An experimental effort to characterize an existing 5-eV neutral atomic oxygen beam facility being developed at Princeton Plasma Physics Laboratory is described. This characterization effort includes atomic oxygen flux and flux distribution measurements using a catalytic probe, energy determination using a commercially designed quadrupole mass spectrometer (QMS), and the exposure of oxygen-sensitive materials in this beam facility. Also, comparisons were drawn between the reaction efficiencies of materials exposed in plasma ashers, and the reaction efficiencies previously estimated from space flight experiments. The results of this study show that the beam facility is capable of producing a directional beam of neutral atomic oxygen atoms with the needed flux and energy to simulate low Earth orbit (LEO) conditions for real time accelerated testing. The flux distribution in this facility is uniform to +/- 6 percent of the peak flux over a beam diameter of 6 cm.

A Multi-Step Approach to Assessing LIGO Test Mass Coatings

NASA Astrophysics Data System (ADS)

Glover, Lamar; Goff, Michael; Linker, Seth; Neilson, Joshua; Patel, Jignesh; Pinto, Innocenzo; Principe, Maria; Villarama, Ethan; Arriaga, Eddy; Barragan, Erik; Chao, Shiuh; Daneshgaran, Lara; DeSalvo, Riccardo; Do, Eric; Fajardo, Cameron

2018-02-01

Photographs of the LIGO Gravitational Wave detector mirrors illuminated by the standing beam were analyzed with an astronomical software tool designed to identify stars within images, which extracted hundreds of thousands of point-like scatterers uniformly distributed across the mirror surface, likely distributed through the depth of the coating layers. The sheer number of the observed scatterers implies a fundamental, thermodynamic origin during deposition or processing. If identified as crystallites, these scatterers would be a possible source of the mirror dissipation and thermal noise, which limit the sensitivity of observatories to Gravitational Waves. In order to learn more about the composition and location of the detected scatterers, a feasibility study is underway to develop a method that determines the location of the scatterers by producing a complete mapping of scatterers within test samples, including their depth distribution, optical amplitude distribution, and lateral distribution. Also, research is underway to accurately identify future materials and/or coating methods that possess the largest possible mechanical quality factor (Q). Current efforts propose a new experimental approach that will more precisely measure the Q of coatings by depositing them onto 100 nm Silicon Nitride membranes.

A Pearson Random Walk with Steps of Uniform Orientation and Dirichlet Distributed Lengths

NASA Astrophysics Data System (ADS)

Le Caër, Gérard

2010-08-01

A constrained diffusive random walk of n steps in ℝ d and a random flight in ℝ d , which are equivalent, were investigated independently in recent papers (J. Stat. Phys. 127:813, 2007; J. Theor. Probab. 20:769, 2007, and J. Stat. Phys. 131:1039, 2008). The n steps of the walk are independent and identically distributed random vectors of exponential length and uniform orientation. Conditioned on the sum of their lengths being equal to a given value l, closed-form expressions for the distribution of the endpoint of the walk were obtained altogether for any n for d=1,2,4. Uniform distributions of the endpoint inside a ball of radius l were evidenced for a walk of three steps in 2D and of two steps in 4D. The previous walk is generalized by considering step lengths which have independent and identical gamma distributions with a shape parameter q>0. Given the total walk length being equal to 1, the step lengths have a Dirichlet distribution whose parameters are all equal to q. The walk and the flight above correspond to q=1. Simple analytical expressions are obtained for any d≥2 and n≥2 for the endpoint distributions of two families of walks whose q are integers or half-integers which depend solely on d. These endpoint distributions have a simple geometrical interpretation. Expressed for a two-step planar walk whose q=1, it means that the distribution of the endpoint on a disc of radius 1 is identical to the distribution of the projection on the disc of a point M uniformly distributed over the surface of the 3D unit sphere. Five additional walks, with a uniform distribution of the endpoint in the inside of a ball, are found from known finite integrals of products of powers and Bessel functions of the first kind. They include four different walks in ℝ3, two of two steps and two of three steps, and one walk of two steps in ℝ4. Pearson-Liouville random walks, obtained by distributing the total lengths of the previous Pearson-Dirichlet walks according to some specified probability law are finally discussed. Examples of unconstrained random walks, whose step lengths are gamma distributed, are more particularly considered.

Monitoring extent of moisture variations due to leachate recirculation in an ELR/bioreactor landfill using resistivity imaging.

PubMed

Manzur, Shahed Rezwan; Hossain, Md Sahadat; Kemler, Vance; Khan, Mohammad Sadik

2016-09-01

Bioreactor or enhanced leachate recirculation (ELR) landfills are designed and operated for accelerated waste stabilization, accelerated decomposition, and an increased rate of gas generation. The major aspects of a bioreactor landfill are the addition of liquid and the recirculation of collected leachate back into the waste mass through the subsurface leachate recirculation system (LRS). The performance of the ELR landfill largely depends on the existing moisture content within the waste mass; therefore, it is of utmost importance to determine the moisture variations within the landfill. Traditionally, the moisture variation of the ELR landfill is determined by collecting samples through a bucket auger boring from the landfill, followed by laboratory investigation. Collecting the samples through a bucket auger boring is time consuming, labor intensive, and cost prohibitive. Moreover, it provides the information for a single point within the waste mass, but not for the moisture distribution within the landfill. Fortunately, 2D resistivity imaging (RI) can be performed to assess the moisture variations within the landfill and provide a continuous image of the subsurface, which can be utilized to evaluate the performance of the ELR landfill. During this study, the 2D resistivity imaging technique was utilized to determine the moisture distribution and moisture movement during the recirculation process of an ELR landfill in Denton, Texas, USA. A horizontal recirculation pipe was selected and monitored periodically for 2.5years, using the RI technique, to investigate the performance of the leachate recirculation. The RI profile indicated that the resistivity of the solid waste decreased as much as 80% with the addition of water/leachate through the recirculation pipe. In addition, the recirculated leachate traveled laterally between 11m and 16m. Based on the resistivity results, it was also observed that the leachate flow throughout the pipe was non-uniform. The non-uniformity of the leachate flow confirms that the flow of leachate through waste is primarily through preferential flow paths due the heterogeneous nature of the waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quality of anthelminthic medicines available in Jimma Ethiopia.

PubMed

Belew, Sileshi; Suleman, Sultan; Wynendaele, Evelien; D'Hondt, Matthias; Kosgei, Anne; Duchateau, Luc; De Spiegeleer, Bart

2018-01-01

Soil-transmitted helminthiasis and schistosomiasis are major public health problems in Ethiopia. Mass deworming of at-risk population using a single dose administration of 400mg albendazole (ABZ) or 500mg mebendazole (MBZ) for treatment of common intestinal worms and 40mg of praziquantel (PZQ) per kg body weight for treatment of schistosomiasis is one of the strategies recommended by World Health Organization (WHO) in order to control the morbidity of soil-transmitted helminthiasis and schistosomiasis. Since storage condition, climate, way of transportation and distribution route could all affect the quality of medicines, regular assessment by surveys is very critical to ensure the therapeutic outcome, to minimize risk of toxicity to the patient and resistance of parasites. Therefore, this study was conducted to assess the pharmaceutical quality of ABZ, MBZ and PZQ tablet brands commonly available in Jimma town (south west Ethiopia). Retail pharmacies (n=10) operating in Jimma town were selected using simple random sampling method. Samples of anthelminthic medicines available in the selected pharmacies were collected. Sample information was recorded and encompassed trade name, active ingredient name, manufacturer's name and full address, labeled medicine strength, dosage form, number of units per container, dosage statement, batch/lot number, manufacturing and expiry dates, storage information and presence of leaflets/package insert. Moreover, a first visual inspection was performed encompassing uniformity of color, uniformity of size, breaks, cracks, splits, embedded surface spots or visual contaminations. Finally, physico-chemical quality attributes investigated encompassed mass uniformity, quantity of active pharmaceutical ingredient (API), disintegration and dissolution, all following Pharmacopoeial test methods The physical characteristics of dosage form, packaging and labeling information of all samples complied with criteria given in the WHO checklists. The mass uniformity of tablets of each brand of ABZ, MBZ and PZQ complied with the pharmacopoeial specification limits, i.e no more than 2 individual masses >5% of average tablet weight, and none deviate by more than 10%. The quantity of APIs in all investigated tablet brands were within the 90-110% label claim (l.c.) limits, ranging between 95.05 and 110.09% l.c. Disintegration times were in line with the pharmacopoeial specification limit for immediate release (IR) tablets, ranging between 0.5 and 13min. However, the dissolution results (mean±SD, n=6) of one ABZ brand (i.e. Wormin ® , Q=59.21±0.99% at 30min) and two PZQ brands (i.e. Bermoxel ® , Q=63.43%±0.7 and Distocide ® , Q=62.43%±1.67, at 75min) showed poor dissolution, failing the United States Pharmacopoeia (USP) dissolution specification limit. Copyright © 2017 Elsevier B.V. All rights reserved.

The Use of Compressive Sensing to Reconstruct Radiation Characteristics of Wide-Band Antennas from Sparse Measurements

DTIC Science & Technology

2015-06-01

of uniform- versus nonuniform -pattern reconstruction, of transform function used, and of minimum randomly distributed measurements needed to...the radiation-frequency pattern’s reconstruction using uniform and nonuniform randomly distributed samples even though the pattern error manifests...5 Fig. 3 The nonuniform compressive-sensing reconstruction of the radiation

V/V(max) test applied to SMM gamma-ray bursts

NASA Technical Reports Server (NTRS)

Matz, S. M.; Higdon, J. C.; Share, G. H.; Messina, D. C.; Iadicicco, A.

1992-01-01

We have applied the V/V(max) test to candidate gamma-ray bursts detected by the Gamma-Ray Spectrometer (GRS) aboard the SMM satellite to examine quantitatively the uniformity of the burst source population. For a sample of 132 candidate bursts identified in the GRS data by an automated search using a single uniform trigger criterion we find average V/V(max) = 0.40 +/- 0.025. This value is significantly different from 0.5, the average for a uniform distribution in space of the parent population of burst sources; however, the shape of the observed distribution of V/V(max) is unusual and our result conflicts with previous measurements. For these reasons we can currently draw no firm conclusion about the distribution of burst sources.

Radionuclide distribution dynamics in skeletons of beagles fed 90Sr: Correlation with injected 226Ra and 239Pu

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

Parks, N.J.

Data for the bone-by-bone redistribution of 90Sr in the beagle skeleton are reported for a period of 4000 d following a midgestation-to-540-d-exposure by ingestion. The partitioned clearance model (PCM) that was originally developed to describe bone-by-bone radionuclide redistribution of 226Ra after eight semimonthly injections at ages 435-535 d has been fitted to the 90Sr data. The parameter estimates for the PCM that describe the distribution and clearance of 226Ra after deposition on surfaces following injection and analogous parameter estimates for 90Sr after uniform deposition in the skeleton as a function of Ca mass are given. Fractional compact bone masses permore » bone group (mi,COM) are also predicted by the model and compared to measured values; a high degree of correlation (r = 0.84) is found. Bone groups for which the agreement between the model and experimental values of mi,COM was poor had tissue-to-calcium weight ratios about 1.5 times those for bones that agreed well. Metabolically defined surface in PCM is initial activity fraction per Ca fraction in a given skeletal component for intravenously injected alkaline earth (Sae) radionuclides; comparisons are made to similarly defined surface (Sact) values from 239Pu injection studies. The patterns of Sae and Sact distribution throughout the skeleton are similar.« less

Design and development of novel bandages for compression therapy.

PubMed

Rajendran, Subbiyan; Anand, Subhash

2003-03-01

During the past few years there have been increasing concerns relating to the performance of bandages, especially their pressure distribution properties for the treatment of venous leg ulcers. This is because compression therapy is a complex system and requires two or multi-layer bandages, and the performance properties of each layer differs from other layers. The widely accepted sustained graduated compression mainly depends on the uniform pressure distribution of different layers of bandages, in which textile fibres and bandage structures play a major role. This article examines how the fibres, fibre blends and structures influence the absorption and pressure distribution properties of bandages. It is hoped that the research findings will help medical professionals, especially nurses, to gain an insight into the development of bandages. A total of 12 padding bandages have been produced using various fibres and fibre blends. A new technique that would facilitate good resilience and cushioning properties, higher and more uniform pressure distribution and enhanced water absorption and retention was adopted during the production. It has been found that the properties of developed padding bandages, which include uniform pressure distribution around the leg, are superior to existing commercial bandages and possess a number of additional properties required to meet the criteria stipulated for an ideal padding bandage. Results have indicated that none of the mostly used commercial padding bandages provide the required uniform pressure distribution around the limb.

Simulation of an active cooling system for photovoltaic modules

NASA Astrophysics Data System (ADS)

Abdelhakim, Lotfi

2016-06-01

Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water also acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.

Sensitivity analysis of lake mass balance in discontinuous permafrost: the example of disappearing Twelvemile Lake, Yukon Flats, Alaska (USA)

USGS Publications Warehouse

Jepsen, S.M.; Voss, C.I.; Walvoord, Michelle Ann; Rose, J.R.; Minsley, B.J.; Smith, B.D.

2013-01-01

Many lakes in northern high latitudes have undergone substantial changes in surface area over the last four decades, possibly as a result of climate warming. In the discontinuous permafrost of Yukon Flats, interior Alaska (USA), these changes have been non-uniform across adjacent watersheds, suggesting local controls on lake water budgets. Mechanisms that could explain the decreasing mass of one lake in Yukon Flats since the early 1980s, Twelvemile Lake, are identified via a scoping analysis that considers plausible changes in snowmelt mass and infiltration, permafrost distribution, and climate warming. Because predicted changes in evaporation (2 cmyr-1) are inadequate to explain the observed 17.5 cmyr-1 reduction in mass balance, other mechanisms are required. The most important potential mechanisms are found to involve: (1) changes in shallow, lateral groundwater flow to the lake possibly facilitated by vertical freeze-thaw migration of the permafrost table in gravel; (2) increased loss of lake water as downward groundwater flow through an open talik to a permeable subpermafrost flowpath; and (3) reduced snow meltwater inputs due to decreased snowpack mass and increased infiltration of snowmelt into, and subsequent evaporation from, fine-grained sediment mantling the permafrost-free lake basin.

Design of passive interconnections in tall buildings subject to earthquake disturbances to suppress inter-storey drifts

NASA Astrophysics Data System (ADS)

Yamamoto, K.; Smith, MC

2016-09-01

This paper studies the problem of passive control of a multi-storey building subjected to an earthquake disturbance. The building is represented as a homogeneous mass chain model, i.e., a chain of identical masses in which there is an identical passive connection between neighbouring masses and a similar connection to a movable point. The paper considers passive interconnections of the most general type, which may require the use of inerters in addition to springs and dampers. It is shown that the scalar transfer functions from the disturbance to a given inter-storey drift can be represented as complex iterative maps. Using these expressions, two graphical approaches are proposed: one gives a method to achieve a prescribed value for the uniform boundedness of these transfer functions independent of the length of the mass chain, and the other is for a fixed length of the mass chain. A case study is presented to demonstrate the effectiveness of the proposed techniques using a 10-storey building model. The disturbance suppression performance of the designed interconnection is also verified for a 10-storey building model which has a different stiffness distribution but with the same undamped first natural frequency as the homogeneous model.

Optical, thermal and combustion properties of self-colored polyamide nanocomposites reinforced with azo dye surface modified ZnO nanoparticles

NASA Astrophysics Data System (ADS)

Hajibeygi, Mohsen; Shabanian, Meisam; Omidi-Ghallemohamadi, Mehrdad; Khonakdar, Hossein Ali

2017-09-01

New self-colored aromatic-polyamide (PA) nanocomposites containing azo and naphthalene chromophores were prepared with azo-dye surface-modified ZnO nanoparticles (SMZnO) using solution method in dimethylformamide. The X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results showed the uniform distribution for ZnO nanoparticles in the PA matrix. The UV-vis spectra of PA/ZnO nanocomposites (PANC) showed a blue shift as well as reduction in absorbance intensities and the photoluminescence studies revealed that the increasing intensities of the violet emission in SMZnO loading. From thermo gravimetric analysis (TGA), the temperature at 10% mass loss (T10) increased from 291.8 °C to 387.6 °C for PANC containing 8 mass% of SMZnO, as well as the char yield enhanced significantly, which was about 23.5% higher than the neat PA. The peak heat release rate resulted from microscale combustion calorimeter (MCC), by 8 mass% loading of SMZnO, decreased about 56.9% lower than the neat PA.

Statistical distributions of avalanche size and waiting times in an inter-sandpile cascade model

NASA Astrophysics Data System (ADS)

Batac, Rene; Longjas, Anthony; Monterola, Christopher

2012-02-01

Sandpile-based models have successfully shed light on key features of nonlinear relaxational processes in nature, particularly the occurrence of fat-tailed magnitude distributions and exponential return times, from simple local stress redistributions. In this work, we extend the existing sandpile paradigm into an inter-sandpile cascade, wherein the avalanches emanating from a uniformly-driven sandpile (first layer) is used to trigger the next (second layer), and so on, in a successive fashion. Statistical characterizations reveal that avalanche size distributions evolve from a power-law p(S)≈S-1.3 for the first layer to gamma distributions p(S)≈Sαexp(-S/S0) for layers far away from the uniformly driven sandpile. The resulting avalanche size statistics is found to be associated with the corresponding waiting time distribution, as explained in an accompanying analytic formulation. Interestingly, both the numerical and analytic models show good agreement with actual inventories of non-uniformly driven events in nature.

Simulation of air velocity in a vertical perforated air distributor

NASA Astrophysics Data System (ADS)

Ngu, T. N. W.; Chu, C. M.; Janaun, J. A.

2016-06-01

Perforated pipes are utilized to divide a fluid flow into several smaller streams. Uniform flow distribution requirement is of great concern in engineering applications because it has significant influence on the performance of fluidic devices. For industrial applications, it is crucial to provide a uniform velocity distribution through orifices. In this research, flow distribution patterns of a closed-end multiple outlet pipe standing vertically for air delivery in the horizontal direction was simulated. Computational Fluid Dynamics (CFD), a tool of research for enhancing and understanding design was used as the simulator and the drawing software SolidWorks was used for geometry setup. The main purpose of this work is to establish the influence of size of orifices, intervals between outlets, and the length of tube in order to attain uniformity of exit flows through a multi outlet perforated tube. However, due to the gravitational effect, the compactness of paddy increases gradually from top to bottom of dryer, uniform flow pattern was aimed for top orifices and larger flow for bottom orifices.

School Uniform Policies in Public Schools

ERIC Educational Resources Information Center

Brunsma, David L.

2006-01-01

The movement for school uniforms in public schools continues to grow despite the author's research indicating little if any impact on student behavior, achievement, and self-esteem. The author examines the distribution of uniform policies by region and demographics, the impact of these policies on perceptions of school climate and safety, and…

Processing and Characterization of Nanoparticle Coatings for Quartz Crystal Microbalance Measurements

PubMed Central

Torrey, Jessica D.; Kirschling, Teresa L.; Greenlee, Lauren F.

2015-01-01

The quartz-crystal microbalance is a sensitive and versatile tool for measuring adsorption of a variety of compounds (e.g. small molecules, polymers, biomolecules, nanoparticles and cells) to surfaces. While the technique has traditionally been used for measuring adsorption to flat surfaces and thin ridged films, it can also be extended to study adsorption to nanoparticle surfaces when the nanoparticles are fixed to the crystal surface. The sensitivity and accuracy of the measurement depend on the users’ ability to reproducibly prepare a thin uniform nanoparticle coating. This study evaluated four coating techniques, including spin coating, spray coating, drop casting, and electrophoretic deposition, for two unique particle chemistries [nanoscale zero valent iron (nZVI) and titanium dioxide (TiO2)] to produce uniform and reproducible nanoparticle coatings for real-time quartz-crystal microbalance measurements. Uniform TiO2 coatings were produced from a 50 mg/mL methanol suspension via spin coating. Nanoscale zero-valent iron was best applied by spray coating a low concentration 1.0 mg/mL suspended in methanol. The application of multiple coatings, rather than an increase in the suspension concentration, was the best method to increase the mass of nanoparticles on the crystal surface while maintaining coating uniformity. An upper mass threshold was determined to be approximately 96 µg/cm2; above this mass, coatings no longer maintained their uniform rigid characteristic, and a low signal to noise ratio resulted in loss of measurable signal from crystal resonances above the fundamental. PMID:26958434

Aging transition in systems of oscillators with global distributed-delay coupling.

PubMed

Rahman, B; Blyuss, K B; Kyrychko, Y N

2017-09-01

We consider a globally coupled network of active (oscillatory) and inactive (nonoscillatory) oscillators with distributed-delay coupling. Conditions for aging transition, associated with suppression of oscillations, are derived for uniform and gamma delay distributions in terms of coupling parameters and the proportion of inactive oscillators. The results suggest that for the uniform distribution increasing the width of distribution for the same mean delay allows aging transition to happen for a smaller coupling strength and a smaller proportion of inactive elements. For gamma distribution with sufficiently large mean time delay, it may be possible to achieve aging transition for an arbitrary proportion of inactive oscillators, as long as the coupling strength lies in a certain range.

Learning Probabilities From Random Observables in High Dimensions: The Maximum Entropy Distribution and Others

NASA Astrophysics Data System (ADS)

Obuchi, Tomoyuki; Cocco, Simona; Monasson, Rémi

2015-11-01

We consider the problem of learning a target probability distribution over a set of N binary variables from the knowledge of the expectation values (with this target distribution) of M observables, drawn uniformly at random. The space of all probability distributions compatible with these M expectation values within some fixed accuracy, called version space, is studied. We introduce a biased measure over the version space, which gives a boost increasing exponentially with the entropy of the distributions and with an arbitrary inverse `temperature' Γ . The choice of Γ allows us to interpolate smoothly between the unbiased measure over all distributions in the version space (Γ =0) and the pointwise measure concentrated at the maximum entropy distribution (Γ → ∞ ). Using the replica method we compute the volume of the version space and other quantities of interest, such as the distance R between the target distribution and the center-of-mass distribution over the version space, as functions of α =(log M)/N and Γ for large N. Phase transitions at critical values of α are found, corresponding to qualitative improvements in the learning of the target distribution and to the decrease of the distance R. However, for fixed α the distance R does not vary with Γ which means that the maximum entropy distribution is not closer to the target distribution than any other distribution compatible with the observable values. Our results are confirmed by Monte Carlo sampling of the version space for small system sizes (N≤ 10).

Light extraction from organic light-emitting diodes for lighting applications by sand-blasting substrates.

PubMed

Chen, Shuming; Kwok, Hoi Sing

2010-01-04

Light extraction from organic light-emitting diodes (OLEDs) by scattering the light is one of the effective methods for large-area lighting applications. In this paper, we present a very simple and cost-effective method to rough the substrates and hence to scatter the light. By simply sand-blasting the edges and back-side surface of the glass substrates, a 20% improvement of forward efficiency has been demonstrated. Moreover, due to scattering effect, a constant color over all viewing angles and uniform light pattern with Lambertian distribution has been obtained. This simple and cost-effective method may be suitable for mass production of large-area OLEDs for lighting applications.

Numerical-assisted design of a wind tunnel used in the estimation of volatilization from water, waste or soil.

PubMed

Baléo, J N; Le Cloirec, P

2006-04-01

Numerical simulations of the flow inside two wind tunnel geometries used for determining emission volatilization have been conducted. The flow pattern was examined in a plane close to the emitting surface. A reduced surface, characterizing the low velocity zones in this plane, has been defined. The proposed geometry modification, consisting of a convergent/divergent system, decreases the low velocity regions by a factor ranging between 2 and 3.5. Large vortices present in the conventional configuration are almost eliminated. The new velocity distribution, close to the emitting surface, is more uniform and should therefore generate a more efficient mass transfer to the flowing air.

Colombia: A Country Under Constant Threat of Disasters

DTIC Science & Technology

2014-05-22

disasters strike every nation in the world , and although these events do not occur with uniformity of distribution, developing nations suffer the greatest...strike every nation in the world , and although these events do not occur with uniformity of distribution, developing nations suffer the greatest...have been victims 4IHS Janes, “Jane’s World Insurgency and Terrorism.” Fuerzas Armadas

Corrosion behavior of ultrafine-grained AA2024 aluminum alloy produced by cryorolling

NASA Astrophysics Data System (ADS)

Laxman Mani Kanta, P.; Srivastava, V. C.; Venkateswarlu, K.; Paswan, Sharma; Mahato, B.; Das, Goutam; Sivaprasad, K.; Krishna, K. Gopala

2017-11-01

The objectives of this study were to produce ultrafine-grained (UFG) AA2024 aluminum alloy by cryorolling followed by aging and to evaluate its corrosion behavior. Solutionized samples were cryorolled to 85% reduction in thickness. Subsequent aging resulted in a UFG structure with finer precipitates of Al2CuMg in the cryorolled alloy. The (1) solutionized and (2) solutionized and cryorolled samples were uniformly aged at 160°C/24 h and were designated as CGPA and CRPA, respectively; these samples were subsequently subjected to corrosion studies. Potentiodynamic polarization studies in 3.5wt% NaCl solution indicated an increase in corrosion potential and a decrease in corrosion current density for CRPA compared to CGPA. In the case of CRPA, electrochemical impedance spectroscopic studies indicated the presence of two complex passive oxide layers with a higher charge transfer resistance and lower mass loss during intergranular corrosion tests. The improved corrosion resistance of CRPA was mainly attributed to its UFG structure, uniform distribution of fine precipitates, and absence of coarse grain-boundary precipitation and associated precipitate-free zones as compared with the CGPA alloy.

Post-Detonation Energy Release from TNT-Aluminum Explosives

NASA Astrophysics Data System (ADS)

Zhang, Fan; Anderson, John; Yoshinaka, Akio

2007-06-01

Detonation and post-detonation energy release from TNT and TNT-aluminum composite have been experimentally studied in an air-filled chamber, 26 m^3 in volume and 3 m in diameter. While TNT has a high oxygen deficiency, experiments with 1.1 kg to 4 kg charges yield energy releases reaching only 86% of theoretical equilibrium values, possibly due to the non-uniform mixing between the detonation products and air. In order to improve mixing and further increase afterburning energy, large mass fractions of large aluminum particles are combined with TNT. The effect of particle distribution is also investigated in two composite configurations, whereby the aluminum particles are uniformly mixed in cast TNT or arranged in a shell surrounding a TNT cylinder. It is shown that the TNT-aluminum composite outperforms pure TNT, while improved performance is achieved for the shell configuration due to enhanced spatial mixing of hot fuels with oxidizing gases. Comparisons with the equilibrium theory and a liquid-based aluminized composite explosive (with an oxygen deficiency less than that of TNT) are conducted to further explore the mixing and afterburning mechanism.

Controlling Growth High Uniformity Indium Selenide (In2Se3) Nanowires via the Rapid Thermal Annealing Process at Low Temperature.

PubMed

Hsu, Ya-Chu; Hung, Yu-Chen; Wang, Chiu-Yen

2017-09-15

High uniformity Au-catalyzed indium selenide (In 2 Se 3) nanowires are grown with the rapid thermal annealing (RTA) treatment via the vapor-liquid-solid (VLS) mechanism. The diameters of Au-catalyzed In 2 Se 3 nanowires could be controlled with varied thicknesses of Au films, and the uniformity of nanowires is improved via a fast pre-annealing rate, 100 °C/s. Comparing with the slower heating rate, 0.1 °C/s, the average diameters and distributions (standard deviation, SD) of In 2 Se 3 nanowires with and without the RTA process are 97.14 ± 22.95 nm (23.63%) and 119.06 ± 48.75 nm (40.95%), respectively. The in situ annealing TEM is used to study the effect of heating rate on the formation of Au nanoparticles from the as-deposited Au film. The results demonstrate that the average diameters and distributions of Au nanoparticles with and without the RTA process are 19.84 ± 5.96 nm (30.00%) and about 22.06 ± 9.00 nm (40.80%), respectively. It proves that the diameter size, distribution, and uniformity of Au-catalyzed In 2 Se 3 nanowires are reduced and improved via the RTA pre-treated. The systemic study could help to control the size distribution of other nanomaterials through tuning the annealing rate, temperatures of precursor, and growth substrate to control the size distribution of other nanomaterials. Graphical Abstract Rapid thermal annealing (RTA) process proved that it can uniform the size distribution of Au nanoparticles, and then it can be used to grow the high uniformity Au-catalyzed In 2 Se 3 nanowires via the vapor-liquid-solid (VLS) mechanism. Comparing with the general growth condition, the heating rate is slow, 0.1 °C/s, and the growth temperature is a relatively high growth temperature, > 650 °C. RTA pre-treated growth substrate can form smaller and uniform Au nanoparticles to react with the In 2 Se 3 vapor and produce the high uniformity In 2 Se 3 nanowires. The in situ annealing TEM is used to realize the effect of heating rate on Au nanoparticle formation from the as-deposited Au film. The byproduct of self-catalyzed In 2 Se 3 nanoplates can be inhibited by lowering the precursors and growth temperatures.

The influence of gyroscopic forces on the dynamic behavior and flutter of rotating blades

NASA Technical Reports Server (NTRS)

Sisto, F.; Chang, A. T.

1983-01-01

The structural dynamics of a cantilever turbomachine blade mounted on a spinning and precessing rotor are investigated. Both stability and forced vibration are considered with a blade model that increases in complexity (and verisimilitude) from a spring-restrained point mass, to a uniform cantilever, to a twisted uniform cantilever turbomachine blade mounted on a spinning and precessing rotor are investigated. Both stability and forced vibration are considered with a blade model that increases in complexity (and verisimilitude) from a spring-restrained point mass, to a uniform cantilever, to a twisted uniform cantilever, to a tapered twisted cantilever of arbitrary cross-section. In every instance the formulation is from first principles using a finite element based on beam theory. Both ramp-type and periodic-type precessional angular displacements are considered. In concluding, forced vibrating and flutter are studied using the final and most sophisticated structural model. The analysis of stability is presented and a number of numerical examples are worked out.

Formulation design of oral pediatric Acetazolamide suspension: dose uniformity and physico-chemical stability study.

PubMed

Santoveña, Ana; Suárez-González, Javier; Martín-Rodríguez, Cristina; Fariña, José B

2017-03-01

The formulation of an active pharmaceutical ingredient (API) as oral solution or suspension in pediatrics is a habitual practice, due to the non-existence of many commercialized medicines in pediatric doses. It is also the simplest way to prepare and administer them to this vulnerable population. The design of a formulation that assures the dose and the system stability depends on the physico-chemical properties of the API. In this study, we formulate a class IV API, Acetazolamide (AZM) as suspension for oral administration to pediatric population. The suspension must comply attributes of quality, safety and efficacy for this route of administration. We use simple compounding procedures, as well as fewer pure excipients, as recommended for children. Mass and uniformity content assays and physical and chemical stability studies were performed. To quantify the API an UPLC method was used. We verified the physico-chemical stability of the suspensions and that they passed the mass test of the European Pharmacopeia (EP), but not the dose uniformity test. This reveals that AZM must be formulated as liquid forms with a more complex system of excipients (not usually indicated in pediatrics), or otherwise solid forms capable of assuring uniformity of mass and dose for every dosage unit.

Effect of the Temperature of the Moderator on the Velocity Distribution of Neutrons with Numerical Calculations for H as Moderator

DOE R&D Accomplishments Database

Wigner, E. P.; Wilkins, J. E. Jr.

1944-09-14

In this paper we set up an integral equation governing the energy distribution of neutrons that are being slowed down uniformly throughout the entire space by a uniformly distributed moderator whose atoms are in motion with a Maxwellian distribution of velocities. The effects of chemical binding and crystal reflection are ignored. When the moderator is hydrogen, the integral equation is reduced to a differential equation and solved by numerical methods. In this manner we obtain a refinement of the dv/v{sup 2} law. (auth)

Characterization of Dispersive Ultrasonic Rayleigh Surface Waves in Asphalt Concrete

NASA Astrophysics Data System (ADS)

In, Chi-Won; Kim, Jin-Yeon; Jacobs, Laurence J.; Kurtis, Kimberly E.

2008-02-01

This research focuses on the application of ultrasonic Rayleigh surface waves to nondestructively characterize the mechanical properties and structural defects (non-uniformly distributed aggregate) in asphalt concrete. An efficient wedge technique is developed in this study to generate Rayleigh surface waves that is shown to be effective in characterizing Rayleigh waves in this highly viscoelastic (attenuating) and heterogeneous medium. Experiments are performed on an asphalt-concrete beam produced with uniformly distributed aggregate. Ultrasonic techniques using both contact and non-contact sensors are examined and their results are compared. Experimental results show that the wedge technique along with an air-coupled sensor appears to be effective in characterizing Rayleigh waves in asphalt concrete. Hence, measurement of theses material properties needs to be investigated in non-uniformly distributed aggregate material using these techniques.

Three-Dimensional Radiobiologic Dosimetry: Application of Radiobiologic Modeling to Patient-Specific 3-Dimensional Imaging–Based Internal Dosimetry

PubMed Central

Prideaux, Andrew R.; Song, Hong; Hobbs, Robert F.; He, Bin; Frey, Eric C.; Ladenson, Paul W.; Wahl, Richard L.; Sgouros, George

2010-01-01

Phantom-based and patient-specific imaging-based dosimetry methodologies have traditionally yielded mean organ-absorbed doses or spatial dose distributions over tumors and normal organs. In this work, radiobiologic modeling is introduced to convert the spatial distribution of absorbed dose into biologically effective dose and equivalent uniform dose parameters. The methodology is illustrated using data from a thyroid cancer patient treated with radioiodine. Methods Three registered SPECT/CT scans were used to generate 3-dimensional images of radionuclide kinetics (clearance rate) and cumulated activity. The cumulated activity image and corresponding CT scan were provided as input into an EGSnrc-based Monte Carlo calculation: The cumulated activity image was used to define the distribution of decays, and an attenuation image derived from CT was used to define the corresponding spatial tissue density and composition distribution. The rate images were used to convert the spatial absorbed dose distribution to a biologically effective dose distribution, which was then used to estimate a single equivalent uniform dose for segmented volumes of interest. Equivalent uniform dose was also calculated from the absorbed dose distribution directly. Results We validate the method using simple models; compare the dose-volume histogram with a previously analyzed clinical case; and give the mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for an illustrative case of a pediatric thyroid cancer patient with diffuse lung metastases. The mean absorbed dose, mean biologically effective dose, and equivalent uniform dose for the tumor were 57.7, 58.5, and 25.0 Gy, respectively. Corresponding values for normal lung tissue were 9.5, 9.8, and 8.3 Gy, respectively. Conclusion The analysis demonstrates the impact of radiobiologic modeling on response prediction. The 57% reduction in the equivalent dose value for the tumor reflects a high level of dose nonuniformity in the tumor and a corresponding reduced likelihood of achieving a tumor response. Such analyses are expected to be useful in treatment planning for radionuclide therapy. PMID:17504874

Enhancement of viability of muscle precursor cells on 3D scaffold in a perfusion bioreactor.

PubMed

Cimetta, E; Flaibani, M; Mella, M; Serena, E; Boldrin, L; De Coppi, P; Elvassore, N

2007-05-01

The aim of this study was to develop a methodology for the in vitro expansion of skeletal-muscle precursor cells (SMPC) in a three-dimensional (3D) environment in order to fabricate a cellularized artificial graft characterized by high density of viable cells and uniform cell distribution over the entire 3D domain. Cell seeding and culture within 3D porous scaffolds by conventional static techniques can lead to a uniform cell distribution only on the scaffold surface, whereas dynamic culture systems have the potential of allowing a uniform growth of SMPCs within the entire scaffold structure. In this work, we designed and developed a perfusion bioreactor able to ensure long-term culture conditions and uniform flow of medium through 3D collagen sponges. A mathematical model to assist the design of the experimental setup and of the operative conditions was developed. The effects of dynamic vs static culture in terms of cell viability and spatial distribution within 3D collagen scaffolds were evaluated at 1, 4 and 7 days and for different flow rates of 1, 2, 3.5 and 4.5 ml/min using C2C12 muscle cell line and SMPCs derived from satellite cells. C2C12 cells, after 7 days of culture in our bioreactor, perfused applying a 3.5 ml/min flow rate, showed a higher viability resulting in a three-fold increase when compared with the same parameter evaluated for cultures kept under static conditions. In addition, dynamic culture resulted in a more uniform 3D cell distribution. The 3.5 ml/min flow rate in the bioreactor was also applied to satellite cell-derived SMPCs cultured on 3D collagen scaffolds. The dynamic culture conditions improved cell viability leading to higher cell density and uniform distribution throughout the entire 3D collagen sponge for both C2C12 and satellite cells.

A VERSATILE FAMILY OF GALACTIC WIND MODELS

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

Bustard, Chad; Zweibel, Ellen G.; D’Onghia, Elena, E-mail: bustard@wisc.edu

2016-03-01

We present a versatile family of model galactic outflows including non-uniform mass and energy source distributions, a gravitational potential from an extended mass source, and radiative losses. The model easily produces steady-state wind solutions for a range of mass-loading factors, energy-loading factors, galaxy mass, and galaxy radius. We find that, with radiative losses included, highly mass-loaded winds must be driven at high central temperatures, whereas low mass-loaded winds can be driven at low temperatures just above the peak of the cooling curve, meaning radiative losses can drastically affect the wind solution even for low mass-loading factors. By including radiative losses,more » we are able to show that subsonic flows can be ignored as a possible mechanism for expelling mass and energy from a galaxy compared to the more efficient transonic solutions. Specifically, the transonic solutions with low mass loading and high energy loading are the most efficient. Our model also produces low-temperature, high-velocity winds that could explain the prevalence of low-temperature material in observed outflows. Finally, we show that our model, unlike the well-known Chevalier and Clegg model, can reproduce the observed linear relationship between wind X-ray luminosity and star formation rate (SFR) over a large range of SFR from 1–1000 M{sub ⊙} yr{sup −1} assuming the wind mass-loading factor is higher for low-mass, and hence, low-SFR galaxies. We also constrain the allowed mass-loading factors that can fit the observed X-ray luminosity versus SFR trend, further suggesting an inverse relationship between mass loading and SFR as explored in advanced numerical simulations.« less

High-resolution imaging of selenium in kidneys: a localized selenium pool associated with glutathione peroxidase 3

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

Malinouski, M.; Kehr, S.; Finney, L.

2012-04-17

Recent advances in quantitative methods and sensitive imaging techniques of trace elements provide opportunities to uncover and explain their biological roles. In particular, the distribution of selenium in tissues and cells under both physiological and pathological conditions remains unknown. In this work, we applied high-resolution synchrotron X-ray fluorescence microscopy (XFM) to map selenium distribution in mouse liver and kidney. Liver showed a uniform selenium distribution that was dependent on selenocysteine tRNA{sup [Ser]Sec} and dietary selenium. In contrast, kidney selenium had both uniformly distributed and highly localized components, the latter visualized as thin circular structures surrounding proximal tubules. Other parts ofmore » the kidney, such as glomeruli and distal tubules, only manifested the uniformly distributed selenium pattern that co-localized with sulfur. We found that proximal tubule selenium localized to the basement membrane. It was preserved in Selenoprotein P knockout mice, but was completely eliminated in glutathione peroxidase 3 (GPx3) knockout mice, indicating that this selenium represented GPx3. We further imaged kidneys of another model organism, the naked mole rat, which showed a diminished uniformly distributed selenium pool, but preserved the circular proximal tubule signal. We applied XFM to image selenium in mammalian tissues and identified a highly localized pool of this trace element at the basement membrane of kidneys that was associated with GPx3. XFM allowed us to define and explain the tissue topography of selenium in mammalian kidneys at submicron resolution.« less

Cell growth and differentiation on feeder layers is predicted to be influenced by bioreactor geometry.

PubMed

Peng, C A; Palsson, B Ø

1996-06-05

Tissue function is comprised of a complex interplay between biological and physicochemical rate processes. The design of bioreactors for tissue engineering must account for these processes simultaneously in order to obtain a bioreactor that provides a uniform environment for tissue growth and development. In the present study we consider the effects of fluid flow and mass transfer on the growth of a tissue in a parallel-plate bioreactor configuration. The parenchymal cells grow on a preformed stromal (feeder) layer that secretes a growth factor that stimulates parenchymal stem cell replication and differentiation. The biological dynamics are described by a unilineage model that describes the replication and differentiation of the tissue stem cell. The physicochemical rates are described by the Navier-Stokes and convective-diffusion equations. The model equations are solved by a finite element method. Two dimensionless groups govern the behavior of the solution. One is the Graetz number (Gz) that describes the relative rates of convection and diffusion, and the other a new dimensionless ratio (designated by P) that describes the interplay of the growth factor production, diffusion, and stimulation. Four geometries (slab, gondola, diamond, and radial shapes) for the parallel-plate bioreactor are analyzed. The uniformity of cell growth is measured by a two-dimensional coefficient of variance. The concentration distribution of the stroma-derived growth factor was computed first based on fluid flow and bioreactor geometry. Then the concomitant cell density distribution was obtained by integrating the calculated growth factor concentration with the parenchymal cell growth and unilineage differentiation process. The spatiotemporal cell growth patterns in four different bioreactor configurations were investigated under a variety of combinations of Gz (10(-1), 10(0), and 10(1)) and P(10(-2), 10(-1), 10(0), 10(1), and 10(2)). The results indicate high cell density and uniformity can be achieved for parameter values of P = 0.01, ..., 0.1 and Gz = 0.1, ..., 1.0. Among the four geometries investigated the radial-flow-type bioreactor provides the most uniform environment in which parenchymal cells can grow and differentiate ex vivo due to the absence of walls that are parallel to the flow paths creating slow flowing regions.

Flow instabilities in non-uniformly heated helium jet arrays used for divertor PFCs

DOE PAGES

Youchison, Dennis L.

2015-07-30

In this study, due to a lack of prototypical experimental data, little is known about the off-normal behavior of recently proposed divertor jet cooling concepts. This article describes a computational fluid dynamics (CFD) study on two jet array designs to investigate their susceptibility to parallel flow instabilities induced by non-uniform heating and large increases in the helium outlet temperature. The study compared a single 25-jet helium-cooled modular divertor (HEMJ) thimble and a micro-jet array with 116 jets. Both have pure tungsten armor and a total mass flow rate of 10 g/s at a 600 °C inlet temperature. We investigated flowmore » perturbations caused by a 30 MW/m 2 off-normal heat flux applied over a 25 mm 2 area in addition to the nominal 5 MW/m 2 applied over a 75 mm 2 portion of the face. The micro-jet array exhibited lower temperatures and a more uniform surface temperature distribution than the HEMJ thimble. We also investigated the response of a manifolded nine-finger HEMJ assembly using the nominal heat flux and a 274 mm 2 heated area. For the 30 MW/m2 case, the micro-jet array absorbed 750 W in the helium with a maximum armor surface temperature of 1280 °C and a fluid/solid interface temperature of 801 °C. The HEMJ absorbed 750 W with a maximum armor surface temperature of 1411 °C and a fluid/solid interface temperature of 844 °C. For comparison, both the single HEMJ finger and the micro-jet array used 5-mm-thick tungsten armor. The ratio of maximum to average temperature and variations in the local heat transfer coefficient were lower for the micro-jet array compared to the HEMJ device. Although high heat flux testing is required to validate the results obtained in these simulations, the results provide important guidance in jet design and manifolding to increase heat removal while providing more even temperature distribution and minimizing non-uniformity in the gas flow and thermal stresses at the armor joint.« less

A Comprehensive Theory of Algorithms for Wireless Networks and Mobile Systems

DTIC Science & Technology

2016-06-08

David Peleg. Nonuniform SINR+Voronoi Diagrams are Effectively Uniform. In Yoram Moses, editor, Distributed Computing: 29th International Symposium...in Computer Science, page 559. Springer, 2014. [16] Erez Kantor, Zvi Lotker, Merav Parter, and David Peleg. Nonuniform sINR+Voronoi dia- grams are...Merav Parter, and David Peleg. Nonuniform SINR+Voronoi diagrams are effectively uniform. In Yoram Moses, editor, Distributed Computing - 29th

The Mean Distance to the nth Neighbour in a Uniform Distribution of Random Points: An Application of Probability Theory

ERIC Educational Resources Information Center

Bhattacharyya, Pratip; Chakrabarti, Bikas K.

2008-01-01

We study different ways of determining the mean distance (r[subscript n]) between a reference point and its nth neighbour among random points distributed with uniform density in a D-dimensional Euclidean space. First, we present a heuristic method; though this method provides only a crude mathematical result, it shows a simple way of estimating…

Electrophoretic sample insertion. [device for uniformly distributing samples in flow path

NASA Technical Reports Server (NTRS)

Mccreight, L. R. (Inventor)

1974-01-01

Two conductive screens located in the flow path of an electrophoresis sample separation apparatus are charged electrically. The sample is introduced between the screens, and the charge is sufficient to disperse and hold the samples across the screens. When the charge is terminated, the samples are uniformly distributed in the flow path. Additionally, a first separation by charged properties has been accomplished.

Couette flow of an incompressible fluid in a porous channel with mass transfer

NASA Astrophysics Data System (ADS)

Niranjana, N.; Vidhya, M.; Govindarajan, A.

2018-04-01

The present discussion deals with the study of couette flow through a porous medium of a viscous incompressible fluid between two infinite horizontal parallel porous flat plates with heat and mass transfer. The stationary plate and the plate in uniform motion are subjected to transverse sinusoidal injection and uniform suction of the fluid. Due to this type of injection velocity, the flow becomes three dimensional. The analytical solutions of the nonlinear partial differential equations of this problem are obtained by using perturbation technique. Expressions for the velocity, temperature fields and the rate of heat and mass transfers are obtained. Effects of the following parameters Schmidt number (Sc), Modified Grashof number (Gm) on the velocity, temperature and concentration fields are obtained numerically and depicted through graphs. The rate of heat and mass transfer are also analyzed.

A Smart Cage With Uniform Wireless Power Distribution in 3D for Enabling Long-Term Experiments With Freely Moving Animals.

PubMed

Mirbozorgi, S Abdollah; Bahrami, Hadi; Sawan, Mohamad; Gosselin, Benoit

2016-04-01

This paper presents a novel experimental chamber with uniform wireless power distribution in 3D for enabling long-term biomedical experiments with small freely moving animal subjects. The implemented power transmission chamber prototype is based on arrays of parallel resonators and multicoil inductive links, to form a novel and highly efficient wireless power transmission system. The power transmitter unit includes several identical resonators enclosed in a scalable array of overlapping square coils which are connected in parallel to provide uniform power distribution along x and y. Moreover, the proposed chamber uses two arrays of primary resonators, facing each other, and connected in parallel to achieve uniform power distribution along the z axis. Each surface includes 9 overlapped coils connected in parallel and implemented into two layers of FR4 printed circuit board. The chamber features a natural power localization mechanism, which simplifies its implementation and ease its operation by avoiding the need for active detection and control mechanisms. A single power surface based on the proposed approach can provide a power transfer efficiency (PTE) of 69% and a power delivered to the load (PDL) of 120 mW, for a separation distance of 4 cm, whereas the complete chamber prototype provides a uniform PTE of 59% and a PDL of 100 mW in 3D, everywhere inside the chamber with a size of 27×27×16 cm(3).

Numerical simulation for the magnetic force distribution in electromagnetic forming of small size flat sheet

NASA Astrophysics Data System (ADS)

Chen, Xiaowei; Wang, Wenping; Wan, Min

2013-12-01

It is essential to calculate magnetic force in the process of studying electromagnetic flat sheet forming. Calculating magnetic force is the basis of analyzing the sheet deformation and optimizing technical parameters. Magnetic force distribution on the sheet can be obtained by numerical simulation of electromagnetic field. In contrast to other computing methods, the method of numerical simulation has some significant advantages, such as higher calculation accuracy, easier using and other advantages. In this paper, in order to study of magnetic force distribution on the small size flat sheet in electromagnetic forming when flat round spiral coil, flat rectangular spiral coil and uniform pressure coil are adopted, the 3D finite element models are established by software ANSYS/EMAG. The magnetic force distribution on the sheet are analyzed when the plane geometries of sheet are equal or less than the coil geometries under fixed discharge impulse. The results showed that when the physical dimensions of sheet are less than the corresponding dimensions of the coil, the variation of induced current channel width on the sheet will cause induced current crowding effect that seriously influence the magnetic force distribution, and the degree of inhomogeneity of magnetic force distribution is increase nearly linearly with the variation of induced current channel width; the small size uniform pressure coil will produce approximately uniform magnetic force distribution on the sheet, but the coil is easy to early failure; the desirable magnetic force distribution can be achieved when the unilateral placed flat rectangular spiral coil is adopted, and this program can be take as preferred one, because the longevity of flat rectangular spiral coil is longer than the working life of small size uniform pressure coil.

Computer simulation of random variables and vectors with arbitrary probability distribution laws

NASA Technical Reports Server (NTRS)

Bogdan, V. M.

1981-01-01

Assume that there is given an arbitrary n-dimensional probability distribution F. A recursive construction is found for a sequence of functions x sub 1 = f sub 1 (U sub 1, ..., U sub n), ..., x sub n = f sub n (U sub 1, ..., U sub n) such that if U sub 1, ..., U sub n are independent random variables having uniform distribution over the open interval (0,1), then the joint distribution of the variables x sub 1, ..., x sub n coincides with the distribution F. Since uniform independent random variables can be well simulated by means of a computer, this result allows one to simulate arbitrary n-random variables if their joint probability distribution is known.

Cylindrically distributing optical fiber tip for uniform laser illumination of hollow organs

NASA Astrophysics Data System (ADS)

Buonaccorsi, Giovanni A.; Burke, T.; MacRobert, Alexander J.; Hill, P. D.; Essenpreis, Matthias; Mills, Timothy N.

1993-05-01

To predict the outcome of laser therapy it is important to possess, among other things, an accurate knowledge of the intensity and distribution of the laser light incident on the tissue. For irradiation of the internal surfaces of hollow organs, modified fiber tips can be used to shape the light distribution to best suit the treatment geometry. There exist bulb-tipped optical fibers emitting a uniform isotropic distribution of light suitable for the treatment of organs which approximate a spherical geometry--the bladder, for example. For the treatment of organs approximating a cylindrical geometry--e.g. the oesophagus--an optical fiber tip which emits a uniform cylindrical distribution of light is required. We report on the design, development and testing of such a device, the CLD fiber tip. The device was made from a solid polymethylmethacrylate (PMMA) rod, 27 mm in length and 4 mm in diameter. One end was shaped and 'silvered' to form a mirror which reflected the light emitted from the delivery fiber positioned at the other end of the rod. The shape of the mirror was such that the light fell with uniform intensity on the circumferential surface of the rod. This surface was coated with BaSO4 reflectance paint to couple the light out of the rod and onto the surface of the tissue.

The global impact distribution of Near-Earth objects

NASA Astrophysics Data System (ADS)

Rumpf, Clemens; Lewis, Hugh G.; Atkinson, Peter M.

2016-02-01

Asteroids that could collide with the Earth are listed on the publicly available Near-Earth object (NEO) hazard web sites maintained by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). The impact probability distribution of 69 potentially threatening NEOs from these lists that produce 261 dynamically distinct impact instances, or Virtual Impactors (VIs), were calculated using the Asteroid Risk Mitigation and Optimization Research (ARMOR) tool in conjunction with OrbFit. ARMOR projected the impact probability of each VI onto the surface of the Earth as a spatial probability distribution. The projection considers orbit solution accuracy and the global impact probability. The method of ARMOR is introduced and the tool is validated against two asteroid-Earth collision cases with objects 2008 TC3 and 2014 AA. In the analysis, the natural distribution of impact corridors is contrasted against the impact probability distribution to evaluate the distributions' conformity with the uniform impact distribution assumption. The distribution of impact corridors is based on the NEO population and orbital mechanics. The analysis shows that the distribution of impact corridors matches the common assumption of uniform impact distribution and the result extends the evidence base for the uniform assumption from qualitative analysis of historic impact events into the future in a quantitative way. This finding is confirmed in a parallel analysis of impact points belonging to a synthetic population of 10,006 VIs. Taking into account the impact probabilities introduced significant variation into the results and the impact probability distribution, consequently, deviates markedly from uniformity. The concept of impact probabilities is a product of the asteroid observation and orbit determination technique and, thus, represents a man-made component that is largely disconnected from natural processes. It is important to consider impact probabilities because such information represents the best estimate of where an impact might occur.

Kinetic market models with single commodity having price fluctuations

NASA Astrophysics Data System (ADS)

Chatterjee, A.; Chakrabarti, B. K.

2006-12-01

We study here numerically the behavior of an ideal gas like model of markets having only one non-consumable commodity. We investigate the behavior of the steady-state distributions of money, commodity and total wealth, as the dynamics of trading or exchange of money and commodity proceeds, with local (in time) fluctuations in the price of the commodity. These distributions are studied in markets with agents having uniform and random saving factors. The self-organizing features in money distribution are similar to the cases without any commodity (or with consumable commodities), while the commodity distribution shows an exponential decay. The wealth distribution shows interesting behavior: gamma like distribution for uniform saving propensity and has the same power-law tail, as that of the money distribution, for a market with agents having random saving propensity.

Dynamics of market structure driven by the degree of consumer’s rationality

NASA Astrophysics Data System (ADS)

Yanagita, Tatsuo; Onozaki, Tamotsu

2010-03-01

We study a simple model of market share dynamics with boundedly rational consumers and firms interacting with each other. As the number of consumers is large, we employ a statistical description to represent firms’ distribution of consumer share, which is characterized by a single parameter representing how rationally the mass of consumers pursue higher utility. As the boundedly rational firm does not know the shape of demand function it faces, it revises production and price so as to raise its profit with the aid of a simple reinforcement learning rule. Simulation results show that (1) three phases of market structure, i.e. the uniform share phase, the oligopolistic phase, and the monopolistic phase, appear depending upon how rational consumers are, and (2) in an oligopolistic phase, the market share distribution of firms follows Zipf’s law and the growth-rate distribution of firms follows Gibrat’s law, and (3) an oligopolistic phase is the best state of market in terms of consumers’ utility but brings the minimum profit to the firms because of severe competition based on the moderate rationality of consumers.

Scenario-based modelling of mass transfer mechanisms at a petroleum contaminated field site-numerical implications.

PubMed

Vasudevan, M; Nambi, Indumathi M; Suresh Kumar, G

2016-06-15

Knowledge about distribution of dissolved plumes and their influencing factors is essential for risk assessment and remediation of light non-aqueous phase liquid contamination in groundwater. Present study deals with the applicability of numerical model for simulating various hydro-geological scenarios considering non-uniform source distribution at a petroleum contaminated site in Chennai, India. The complexity associated with the hydrogeology of the site has limited scope for on-site quantification of petroleum pipeline spillage. The change in fuel composition under mass-transfer limited conditions was predicted by simultaneously comparing deviations in aqueous concentrations and activity coefficients (between Raoult's law and analytical approaches). The effects of source migration and weathering on the dissolution of major soluble fractions of petroleum fuel were also studied in relation to the apparent change in their activity coefficients and molar fractions. The model results were compared with field observations and found that field conditions were favourable for biodegradation, especially for the aromatic fraction (benzene and toluene (nearly 95% removal), polycyclic aromatic hydrocarbons (up to 65% removal) and xylene (nearly 45% removal). The results help to differentiate the effect of compositional non-ideality from rate-limited dissolution towards tailing of less soluble compounds (alkanes and trimethylbenzene). Although the effect of non-ideality decreased with distance from the source, the assumption of spatially varying residual saturation could effectively illustrate post-spill scenario by estimating the consequent decrease in mass transfer rate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Luminosity distance in ``Swiss cheese'' cosmology with randomized voids. II. Magnification probability distributions

NASA Astrophysics Data System (ADS)

Flanagan, Éanna É.; Kumar, Naresh; Wasserman, Ira; Vanderveld, R. Ali

2012-01-01

We study the fluctuations in luminosity distances due to gravitational lensing by large scale (≳35Mpc) structures, specifically voids and sheets. We use a simplified “Swiss cheese” model consisting of a ΛCDM Friedman-Robertson-Walker background in which a number of randomly distributed nonoverlapping spherical regions are replaced by mass-compensating comoving voids, each with a uniform density interior and a thin shell of matter on the surface. We compute the distribution of magnitude shifts using a variant of the method of Holz and Wald , which includes the effect of lensing shear. The standard deviation of this distribution is ˜0.027 magnitudes and the mean is ˜0.003 magnitudes for voids of radius 35 Mpc, sources at redshift zs=1.0, with the voids chosen so that 90% of the mass is on the shell today. The standard deviation varies from 0.005 to 0.06 magnitudes as we vary the void size, source redshift, and fraction of mass on the shells today. If the shell walls are given a finite thickness of ˜1Mpc, the standard deviation is reduced to ˜0.013 magnitudes. This standard deviation due to voids is a factor ˜3 smaller than that due to galaxy scale structures. We summarize our results in terms of a fitting formula that is accurate to ˜20%, and also build a simplified analytic model that reproduces our results to within ˜30%. Our model also allows us to explore the domain of validity of weak-lensing theory for voids. We find that for 35 Mpc voids, corrections to the dispersion due to lens-lens coupling are of order ˜4%, and corrections due to shear are ˜3%. Finally, we estimate the bias due to source-lens clustering in our model to be negligible.

The Center of Mass of a Soft Spring

ERIC Educational Resources Information Center

Serna, Juan D.; Joshi, Amitabh

2011-01-01

This article uses calculus to find the center of mass of a soft, vertically suspended, cylindrical helical spring, which necessarily is stretched non-uniformly by the action of gravity. A general expression for the vertical position of the center of mass is obtained and compared with other results in the literature.

Uniformly sized gold nanoparticles derived from PS-b-P2VP block copolymer templates for the controllable synthesis of Si nanowires.

PubMed

Lu, Jennifer Q; Yi, Sung Soo

2006-04-25

A monolayer of gold-containing surface micelles has been produced by spin-coating solution micelles formed by the self-assembly of the gold-modified polystyrene-b-poly(2-vinylpyridine) block copolymer in toluene. After oxygen plasma removed the block copolymer template, highly ordered and uniformly sized nanoparticles have been generated. Unlike other published methods that require reduction treatments to form gold nanoparticles in the zero-valent state, these as-synthesized nanoparticles are in form of metallic gold. These gold nanoparticles have been demonstrated to be an excellent catalyst system for growing small-diameter silicon nanowires. The uniformly sized gold nanoparticles have promoted the controllable synthesis of silicon nanowires with a narrow diameter distribution. Because of the ability to form a monolayer of surface micelles with a high degree of order, evenly distributed gold nanoparticles have been produced on a surface. As a result, uniformly distributed, high-density silicon nanowires have been generated. The process described herein is fully compatible with existing semiconductor processing techniques and can be readily integrated into device fabrication.

Spatial model of the gecko foot hair: functional significance of highly specialized non-uniform geometry.

PubMed

Filippov, Alexander E; Gorb, Stanislav N

2015-02-06

One of the important problems appearing in experimental realizations of artificial adhesives inspired by gecko foot hair is so-called clusterization. If an artificially produced structure is flexible enough to allow efficient contact with natural rough surfaces, after a few attachment-detachment cycles, the fibres of the structure tend to adhere one to another and form clusters. Normally, such clusters are much larger than original fibres and, because they are less flexible, form much worse adhesive contacts especially with the rough surfaces. Main problem here is that the forces responsible for the clusterization are the same intermolecular forces which attract fibres to fractal surface of the substrate. However, arrays of real gecko setae are much less susceptible to this problem. One of the possible reasons for this is that ends of the seta have more sophisticated non-uniformly distributed three-dimensional structure than that of existing artificial systems. In this paper, we simulated three-dimensional spatial geometry of non-uniformly distributed branches of nanofibres of the setal tip numerically, studied its attachment-detachment dynamics and discussed its advantages versus uniformly distributed geometry.

Pattern optimization of compound optical film for uniformity improvement in liquid-crystal displays

NASA Astrophysics Data System (ADS)

Huang, Bing-Le; Lin, Jin-tang; Ye, Yun; Xu, Sheng; Chen, En-guo; Guo, Tai-Liang

2017-12-01

The density dynamic adjustment algorithm (DDAA) is designed to efficiently promote the uniformity of the integrated backlight module (IBLM) by adjusting the microstructures' distribution on the compound optical film (COF), in which the COF is constructed in the SolidWorks and simulated in the TracePro. In order to demonstrate the universality of the proposed algorithm, the initial distribution is allocated by the Bezier curve instead of an empirical value. Simulation results maintains that the uniformity of the IBLM reaches over 90% only after four rounds. Moreover, the vertical and horizontal full width at half maximum of angular intensity are collimated to 24 deg and 14 deg, respectively. Compared with the current industry requirement, the IBLM has an 85% higher luminance uniformity of the emerging light, which demonstrate the feasibility and universality of the proposed algorithm.

Terawatt x-ray free-electron-laser optimization by transverse electron distribution shaping

DOE PAGES

Emma, C.; Wu, J.; Fang, K.; ...

2014-11-03

We study the dependence of the peak power of a 1.5 Å Terawatt (TW), tapered x-ray free-electron laser (FEL) on the transverse electron density distribution. Multidimensional optimization schemes for TW hard x-ray free-electron lasers are applied to the cases of transversely uniform and parabolic electron beam distributions and compared to a Gaussian distribution. The optimizations are performed for a 200 m undulator and a resonant wavelength of λ r = 1.5 Å using the fully three-dimensional FEL particle code GENESIS. The study shows that the flatter transverse electron distributions enhance optical guiding in the tapered section of the undulator andmore » increase the maximum radiation power from a maximum of 1.56 TW for a transversely Gaussian beam to 2.26 TW for the parabolic case and 2.63 TW for the uniform case. Spectral data also shows a 30%–70% reduction in energy deposited in the sidebands for the uniform and parabolic beams compared with a Gaussian. An analysis of the transverse coherence of the radiation shows the coherence area to be much larger than the beam spotsize for all three distributions, making coherent diffraction imaging experiments possible.« less

Integrated Joule switches for the control of current dynamics in parallel superconducting strips

NASA Astrophysics Data System (ADS)

Casaburi, A.; Heath, R. M.; Cristiano, R.; Ejrnaes, M.; Zen, N.; Ohkubo, M.; Hadfield, R. H.

2018-06-01

Understanding and harnessing the physics of the dynamic current distribution in parallel superconducting strips holds the key to creating next generation sensors for single molecule and single photon detection. Non-uniformity in the current distribution in parallel superconducting strips leads to low detection efficiency and unstable operation, preventing the scale up to large area sensors. Recent studies indicate that non-uniform current distributions occurring in parallel strips can be understood and modeled in the framework of the generalized London model. Here we build on this important physical insight, investigating an innovative design with integrated superconducting-to-resistive Joule switches to break the superconducting loops between the strips and thus control the current dynamics. Employing precision low temperature nano-optical techniques, we map the uniformity of the current distribution before- and after the resistive strip switching event, confirming the effectiveness of our design. These results provide important insights for the development of next generation large area superconducting strip-based sensors.

Adaptive particle-based pore-level modeling of incompressible fluid flow in porous media: a direct and parallel approach

NASA Astrophysics Data System (ADS)

Ovaysi, S.; Piri, M.

2009-12-01

We present a three-dimensional fully dynamic parallel particle-based model for direct pore-level simulation of incompressible viscous fluid flow in disordered porous media. The model was developed from scratch and is capable of simulating flow directly in three-dimensional high-resolution microtomography images of naturally occurring or man-made porous systems. It reads the images as input where the position of the solid walls are given. The entire medium, i.e., solid and fluid, is then discretized using particles. The model is based on Moving Particle Semi-implicit (MPS) technique. We modify this technique in order to improve its stability. The model handles highly irregular fluid-solid boundaries effectively. It takes into account viscous pressure drop in addition to the gravity forces. It conserves mass and can automatically detect any false connectivity with fluid particles in the neighboring pores and throats. It includes a sophisticated algorithm to automatically split and merge particles to maintain hydraulic connectivity of extremely narrow conduits. Furthermore, it uses novel methods to handle particle inconsistencies and open boundaries. To handle the computational load, we present a fully parallel version of the model that runs on distributed memory computer clusters and exhibits excellent scalability. The model is used to simulate unsteady-state flow problems under different conditions starting from straight noncircular capillary tubes with different cross-sectional shapes, i.e., circular/elliptical, square/rectangular and triangular cross-sections. We compare the predicted dimensionless hydraulic conductances with the data available in the literature and observe an excellent agreement. We then test the scalability of our parallel model with two samples of an artificial sandstone, samples A and B, with different volumes and different distributions (non-uniform and uniform) of solid particles among the processors. An excellent linear scalability is obtained for sample B that has more uniform distribution of solid particles leading to a superior load balancing. The model is then used to simulate fluid flow directly in REV size three-dimensional x-ray images of a naturally occurring sandstone. We analyze the quality and consistency of the predicted flow behavior and calculate absolute permeability, which compares well with the available network modeling and Lattice-Boltzmann permeabilities available in the literature for the same sandstone. We show that the model conserves mass very well and is stable computationally even at very narrow fluid conduits. The transient- and the steady-state fluid flow patterns are presented as well as the steady-state flow rates to compute absolute permeability. Furthermore, we discuss the vital role of our adaptive particle resolution scheme in preserving the original pore connectivity of the samples and their narrow channels through splitting and merging of fluid particles.

Odd nitrogen production by meteoroids

NASA Technical Reports Server (NTRS)

Park, C.; Menees, G. P.

1978-01-01

The process by which odd nitrogen species (atomic nitrogen and nitric oxide) are formed during atmospheric entry of meteoroids is analyzed theoretically. An ablating meteoroid is assumed to be a point source of mass with a continuum regime evolving in its wake. The amounts of odd nitrogen species, produced by high-temperature reactions of air in the continuum wake, are calculated by numerical integration of chemical rate equations. Flow properties are assumed to be uniform across the wake, and 29 reactions involving five neutral species and five singly ionized species are considered, as well as vibrational and electron temperature nonequilibrium phenomena. The results, when they are summed over the observed mass, velocity, and entry-angle distribution of meteoroids, provide odd-nitrogen-species annual global production rates as functions of altitude. The peak production of nitric oxide is found to occur at an altitude of about 85 km; atomic nitrogen production peaks at about 95 km. The total annual rate for nitric oxide is 40 million kg; for atomic nitrogen it is 170 million kg.

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity.

PubMed

Gagne, Nolan L; Cutright, Daniel R; Rivard, Mark J

2012-09-01

To improve tumor dose conformity and homogeneity for COMS plaque brachytherapy by investigating the dosimetric effects of varying component source ring radionuclides and source strengths. The MCNP5 Monte Carlo (MC) radiation transport code was used to simulate plaque heterogeneity-corrected dose distributions for individually-activated source rings of 14, 16 and 18 mm diameter COMS plaques, populated with (103)Pd, (125)I and (131)Cs sources. Ellipsoidal tumors were contoured for each plaque size and MATLAB programming was developed to generate tumor dose distributions for all possible ring weighting and radionuclide permutations for a given plaque size and source strength resolution, assuming a 75 Gy apical prescription dose. These dose distributions were analyzed for conformity and homogeneity and compared to reference dose distributions from uniformly-loaded (125)I plaques. The most conformal and homogeneous dose distributions were reproduced within a reference eye environment to assess organ-at-risk (OAR) doses in the Pinnacle(3) treatment planning system (TPS). The gamma-index analysis method was used to quantitatively compare MC and TPS-generated dose distributions. Concentrating > 97% of the total source strength in a single or pair of central (103)Pd seeds produced the most conformal dose distributions, with tumor basal doses a factor of 2-3 higher and OAR doses a factor of 2-3 lower than those of corresponding uniformly-loaded (125)I plaques. Concentrating 82-86% of the total source strength in peripherally-loaded (131)Cs seeds produced the most homogeneous dose distributions, with tumor basal doses 17-25% lower and OAR doses typically 20% higher than those of corresponding uniformly-loaded (125)I plaques. Gamma-index analysis found > 99% agreement between MC and TPS dose distributions. A method was developed to select intra-plaque ring radionuclide compositions and source strengths to deliver more conformal and homogeneous tumor dose distributions than uniformly-loaded (125)I plaques. This method may support coordinated investigations of an appropriate clinical target for eye plaque brachytherapy.

Impact of deformed extreme-ultraviolet pellicle in terms of CD uniformity

NASA Astrophysics Data System (ADS)

Kim, In-Seon; Yeung, Michael; Barouch, Eytan; Oh, Hye-Keun

2015-07-01

The usage of the extreme ultraviolet (EUV) pellicle is regarded as the solution for defect control since it can protect the mask from airborne debris. However some obstacles disrupt real-application of the pellicle such as structural weakness, thermal damage and so on. For these reasons, flawless fabrication of the pellicle is impossible. In this paper, we discuss the influence of deformed pellicle in terms of non-uniform intensity distribution and critical dimension (CD) uniformity. It was found that non-uniform intensity distribution is proportional to local tilt angle of pellicle and CD variation was linearly proportional to transmission difference. When we consider the 16 nm line and space pattern with dipole illumination (σc=0.8, σr=0.1, NA=0.33), the transmission difference (max-min) of 0.7 % causes 0.1 nm CD uniformity. Influence of gravity caused deflection to the aerial image is small enough to ignore. CD uniformity is less than 0.1 nm even for the current gap of 2 mm between mask and pellicle. However, heat caused EUV pellicle wrinkle might cause serious image distortion because a wrinkle of EUV pellicle causes a transmission loss variation as well as CD non-uniformity. In conclusion, local angle of a wrinkle, not a period or an amplitude of a wrinkle is a main factor to CD uniformity, and local angle of less than ~270 mrad is needed to achieve 0.1 nm CD uniformity with 16 nm L/S pattern.

Hydrostatic bearings for a turbine fluid flow metering device

DOEpatents

Fincke, J.R.

1980-05-02

A rotor assembly fluid metering device has been improved by development of a hydrostatic bearing fluid system which provides bearing fluid at a common pressure to rotor assembly bearing surfaces. The bearing fluid distribution system produces a uniform film of fluid distribution system produces a uniform film of fluid between bearing surfaces and allows rapid replacement of bearing fluid between bearing surfaces, thereby minimizing bearing wear and corrosion.

Percolation Laws of a Fractal Fracture-Pore Double Medium

NASA Astrophysics Data System (ADS)

Zhao, Yangsheng; Feng, Zengchao; Lv, Zhaoxing; Zhao, Dong; Liang, Weiguo

2016-12-01

The fracture-pore double porosity medium is one of the most common media in nature, for example, rock mass in strata. Fracture has a more significant effect on fluid flow than a pore in a fracture-pore double porosity medium. Hence, the fracture effect on percolation should be considered when studying the percolation phenomenon in porous media. In this paper, based on the fractal distribution law, three-dimensional (3D) fracture surfaces, and two-dimensional (2D) fracture traces in rock mass, the locations of fracture surfaces or traces are determined using a random function of uniform distribution. Pores are superimposed to build a fractal fracture-pore double medium. Numerical experiments were performed to show percolation phenomena in the fracture-pore double medium. The percolation threshold can be determined from three independent variables (porosity n, fracture fractal dimension D, and initial value of fracture number N0). Once any two are determined, the percolation probability exists at a critical point with the remaining parameter changing. When the initial value of the fracture number is greater than zero, the percolation threshold in the fracture-pore medium is much smaller than that in a pore medium. When the fracture number equals zero, the fracture-pore medium degenerates to a pore medium, and both percolation thresholds are the same.

Development of extended release dosage forms using non-uniform drug distribution techniques.

PubMed

Huang, Kuo-Kuang; Wang, Da-Peng; Meng, Chung-Ling

2002-05-01

Development of an extended release oral dosage form for nifedipine using the non-uniform drug distribution matrix method was conducted. The process conducted in a fluid bed processing unit was optimized by controlling the concentration gradient of nifedipine in the coating solution and the spray rate applied to the non-pareil beads. The concentration of nifedipine in the coating was controlled by instantaneous dilutions of coating solution with polymer dispersion transported from another reservoir into the coating solution at a controlled rate. The USP dissolution method equipped with paddles at 100 rpm in 0.1 N hydrochloric acid solution maintained at 37 degrees C was used for the evaluation of release rate characteristics. Results indicated that (1) an increase in the ethyl cellulose content in the coated beads decreased the nifedipine release rate, (2) incorporation of water-soluble sucrose into the formulation increased the release rate of nifedipine, and (3) adjustment of the spray coating solution and the transport rate of polymer dispersion could achieve a dosage form with a zero-order release rate. Since zero-order release rate and constant plasma concentration were achieved in this study using the non-uniform drug distribution technique, further studies to determine in vivo/in vitro correlation with various non-uniform drug distribution dosage forms will be conducted.

Simulation of an active cooling system for photovoltaic modules

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

Abdelhakim, Lotfi

Photovoltaic cells are devices that convert solar radiation directly into electricity. However, solar radiation increases the photovoltaic cells temperature [1] [2]. The temperature has an influence on the degradation of the cell efficiency and the lifetime of a PV cell. This work reports on a water cooling technique for photovoltaic panel, whereby the cooling system was placed at the front surface of the cells to dissipate excess heat away and to block unwanted radiation. By using water as a cooling medium for the photovoltaic solar cells, the overheating of closed panel is greatly reduced without prejudicing luminosity. The water alsomore » acts as a filter to remove a portion of solar spectrum in the infrared band but allows transmission of the visible spectrum most useful for the PV operation. To improve the cooling system efficiency and electrical efficiency, uniform flow rate among the cooling system is required to ensure uniform distribution of the operating temperature of the PV cells. The aims of this study are to develop a 3D thermal model to simulate the cooling and heat transfer in Photovoltaic panel and to recommend a cooling technique for the PV panel. The velocity, pressure and temperature distribution of the three-dimensional flow across the cooling block were determined using the commercial package, Fluent. The second objective of this work is to study the influence of the geometrical dimensions of the panel, water mass flow rate and water inlet temperature on the flow distribution and the solar panel temperature. The results obtained by the model are compared with experimental results from testing the prototype of the cooling device.« less

Controlled irrigation of a structured packing as a method for increasing the efficiency of liquid mixture separation in the distillation column

NASA Astrophysics Data System (ADS)

Pavlenko, A. N.; Zhukov, V. E.; Pecherkin, N. I.; Nazarov, A. D.; Li, X.; Li, H.; Gao, X.; Sui, H.

2017-09-01

The use of modern structured packing in the distillation columns allows much more even distribution of the liquid film over the packing surface, but it does not completely solve the problem of uniform distribution of flow parameters over the entire height of the packing. Negative stratification of vapor along the packing height caused by different densities of vapor mixture components and higher temperature in the lower part of the column leads to formation of large-scale maldistributions of temperature and mixture composition over the column cross-section even under the conditions of uniform irrigation of packing with liquid. In these experiments, the idea of compensatory action of liquid distributor on the large-scale maldistribution of mixture composition over the column cross-section was implemented. The experiments were carried out in the distillation column with the diameter of 0.9 m on 10 layers of the Mellapak 350Y packing with the total height of 2.1 m. The mixture of R-21 and R-114 was used as the working mixture. To irrigate the packing, the liquid distributorr with 126 independently controlled solenoid valves overlapping the holes with the diameter of 5 mm, specially designed by the authors, was used. Response of the column to the action of liquid distributor was observed in real time according to the indications of 3 groups of thermometers mounted in 3 different cross-sections of the column. The experiments showed that the minimal correction of the drip point pattern in the controlled liquid distributor can significantly affect the pattern of flow parameter distribution over the cross-section and height of the mass transfer surface and increase separation efficiency of the column within 20%.

WE-DE-201-12: Thermal and Dosimetric Properties of a Ferrite-Based Thermo-Brachytherapy Seed

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

Warrell, G; Shvydka, D; Parsai, E I

Purpose: The novel thermo-brachytherapy (TB) seed provides a simple means of adding hyperthermia to LDR prostate permanent implant brachytherapy. The high blood perfusion rate (BPR) within the prostate motivates the use of the ferrite and conductive outer layer design for the seed cores. We describe the results of computational analyses of the thermal properties of this ferrite-based TB seed in modelled patient-specific anatomy, as well as studies of the interseed and scatter (ISA) effect. Methods: The anatomies (including the thermophysical properties of the main tissue types) and seed distributions of 6 prostate patients who had been treated with LDR brachytherapymore » seeds were modelled in the finite element analysis software COMSOL, using ferrite-based TB and additional hyperthermia-only (HT-only) seeds. The resulting temperature distributions were compared to those computed for patient-specific seed distributions, but in uniform anatomy with a constant blood perfusion rate. The ISA effect was quantified in the Monte Carlo software package MCNP5. Results: Compared with temperature distributions calculated in modelled uniform tissue, temperature distributions in the patient-specific anatomy were higher and more heterogeneous. Moreover, the maximum temperature to the rectal wall was typically ∼1 °C greater for patient-specific anatomy than for uniform anatomy. The ISA effect of the TB and HT-only seeds caused a reduction in D90 similar to that found for previously-investigated NiCu-based seeds, but of a slightly smaller magnitude. Conclusion: The differences between temperature distributions computed for uniform and patient-specific anatomy for ferrite-based seeds are significant enough that heterogeneous anatomy should be considered. Both types of modelling indicate that ferrite-based seeds provide sufficiently high and uniform hyperthermia to the prostate, without excessively heating surrounding tissues. The ISA effect of these seeds is slightly less than that for the previously-presented NiCu-based seeds.« less

The distribution of cigarette prices under different tax structures: findings from the International Tobacco Control Policy Evaluation (ITC) Project

PubMed Central

Shang, Ce; Chaloupka, Frank J; Zahra, Nahleen; Fong, Geoffrey T

2013-01-01

Background The distribution of cigarette prices has rarely been studied and compared under different tax structures. Descriptive evidence on price distributions by countries can shed light on opportunities for tax avoidance and brand switching under different tobacco tax structures, which could impact the effectiveness of increased taxation in reducing smoking. Objective This paper aims to describe the distribution of cigarette prices by countries and to compare these distributions based on the tobacco tax structure in these countries. Methods We employed data for 16 countries taken from the International Tobacco Control Policy Evaluation Project to construct survey-derived cigarette prices for each country. Self-reported prices were weighted by cigarette consumption and described using a comprehensive set of statistics. We then compared these statistics for cigarette prices under different tax structures. In particular, countries of similar income levels and countries that impose similar total excise taxes using different tax structures were paired and compared in mean and variance using a two-sample comparison test. Findings Our investigation illustrates that, compared with specific uniform taxation, other tax structures, such as ad valorem uniform taxation, mixed (a tax system using ad valorem and specific taxes) uniform taxation, and tiered tax structures of specific, ad valorem and mixed taxation tend to have price distributions with greater variability. Countries that rely heavily on ad valorem and tiered taxes also tend to have greater price variability around the median. Among mixed taxation systems, countries that rely more heavily on the ad valorem component tend to have greater price variability than countries that rely more heavily on the specific component. In countries with tiered tax systems, cigarette prices are skewed more towards lower prices than are prices under uniform tax systems. The analyses presented here demonstrate that more opportunities exist for tax avoidance and brand switching when the tax structure departs from a uniform specific tax. PMID:23792324

The distribution of cigarette prices under different tax structures: findings from the International Tobacco Control Policy Evaluation (ITC) Project.

PubMed

Shang, Ce; Chaloupka, Frank J; Zahra, Nahleen; Fong, Geoffrey T

2014-03-01

The distribution of cigarette prices has rarely been studied and compared under different tax structures. Descriptive evidence on price distributions by countries can shed light on opportunities for tax avoidance and brand switching under different tobacco tax structures, which could impact the effectiveness of increased taxation in reducing smoking. This paper aims to describe the distribution of cigarette prices by countries and to compare these distributions based on the tobacco tax structure in these countries. We employed data for 16 countries taken from the International Tobacco Control Policy Evaluation Project to construct survey-derived cigarette prices for each country. Self-reported prices were weighted by cigarette consumption and described using a comprehensive set of statistics. We then compared these statistics for cigarette prices under different tax structures. In particular, countries of similar income levels and countries that impose similar total excise taxes using different tax structures were paired and compared in mean and variance using a two-sample comparison test. Our investigation illustrates that, compared with specific uniform taxation, other tax structures, such as ad valorem uniform taxation, mixed (a tax system using ad valorem and specific taxes) uniform taxation, and tiered tax structures of specific, ad valorem and mixed taxation tend to have price distributions with greater variability. Countries that rely heavily on ad valorem and tiered taxes also tend to have greater price variability around the median. Among mixed taxation systems, countries that rely more heavily on the ad valorem component tend to have greater price variability than countries that rely more heavily on the specific component. In countries with tiered tax systems, cigarette prices are skewed more towards lower prices than are prices under uniform tax systems. The analyses presented here demonstrate that more opportunities exist for tax avoidance and brand switching when the tax structure departs from a uniform specific tax.

A Mass Spectrometry Study of Isotope Separation in the Laser Plume

NASA Astrophysics Data System (ADS)

Suen, Timothy Wu

Accurate quantification of isotope ratios is critical for both preventing the development of illicit weapons programs in nuclear safeguards and identifying the source of smuggled material in nuclear forensics. While isotope analysis has traditionally been performed by mass spectrometry, the need for in situ measurements has prompted the development of optical techniques, such as laser-induced breakdown spectroscopy (LIBS) and laser ablation molecular isotopic spectrometry (LAMIS). These optical measurements rely on laser ablation for direct solid sampling, but several past studies have suggested that the distribution of isotopes in the ablation plume is not uniform. This study seeks to characterize isotope separation in the laser plume through the use of orthogonal-acceleration time-of-flight mass spectrometry. A silver foil was ablated with a Nd:YAG at 355 nm at an energy of 50 muJ with a spot size of 71 mum, for a fluence of 1.3 J/cm2 and an irradiance of 250 MW/cm2. Flat-plate repellers were used to sample the plume, and a temporal profile of the ions was obtained by varying the time delay on the high-voltage pulse. A spatial profile along the axis of the plume was generated by changing the position of the sample, which yielded snapshots of the isotopic composition with time. In addition, the reflectron time-of-flight system was used as an energy filter in conjunction with the repellers to sample slices of the laser plasma orthogonal to the plume axis. Mass spectrometry of the plume revealed a fast ion distribution and a slow ion distribution. Measurements taken across the entire plume showed the fast 109Ag ions slightly ahead in both space and time, causing the 107Ag fraction to drop to 0.34 at 3 mus, 4 mm from the sample surface. Although measurements centered on the near side of the plume did not show isotope separation, the slow ions on the far side of the plume included much more 109Ag than 107Ag. In addition to examining the isotope content of the ablation plume, this study has developed a mass spectrometry characterization technique that may be useful for investigating chemical reactions during laser ablation.

Shape Classification Using Wasserstein Distance for Brain Morphometry Analysis.

PubMed

Su, Zhengyu; Zeng, Wei; Wang, Yalin; Lu, Zhong-Lin; Gu, Xianfeng

2015-01-01

Brain morphometry study plays a fundamental role in medical imaging analysis and diagnosis. This work proposes a novel framework for brain cortical surface classification using Wasserstein distance, based on uniformization theory and Riemannian optimal mass transport theory. By Poincare uniformization theorem, all shapes can be conformally deformed to one of the three canonical spaces: the unit sphere, the Euclidean plane or the hyperbolic plane. The uniformization map will distort the surface area elements. The area-distortion factor gives a probability measure on the canonical uniformization space. All the probability measures on a Riemannian manifold form the Wasserstein space. Given any 2 probability measures, there is a unique optimal mass transport map between them, the transportation cost defines the Wasserstein distance between them. Wasserstein distance gives a Riemannian metric for the Wasserstein space. It intrinsically measures the dissimilarities between shapes and thus has the potential for shape classification. To the best of our knowledge, this is the first. work to introduce the optimal mass transport map to general Riemannian manifolds. The method is based on geodesic power Voronoi diagram. Comparing to the conventional methods, our approach solely depends on Riemannian metrics and is invariant under rigid motions and scalings, thus it intrinsically measures shape distance. Experimental results on classifying brain cortical surfaces with different intelligence quotients demonstrated the efficiency and efficacy of our method.

Shape Classification Using Wasserstein Distance for Brain Morphometry Analysis

PubMed Central

Su, Zhengyu; Zeng, Wei; Wang, Yalin; Lu, Zhong-Lin; Gu, Xianfeng

2015-01-01

Brain morphometry study plays a fundamental role in medical imaging analysis and diagnosis. This work proposes a novel framework for brain cortical surface classification using Wasserstein distance, based on uniformization theory and Riemannian optimal mass transport theory. By Poincare uniformization theorem, all shapes can be conformally deformed to one of the three canonical spaces: the unit sphere, the Euclidean plane or the hyperbolic plane. The uniformization map will distort the surface area elements. The area-distortion factor gives a probability measure on the canonical uniformization space. All the probability measures on a Riemannian manifold form the Wasserstein space. Given any 2 probability measures, there is a unique optimal mass transport map between them, the transportation cost defines the Wasserstein distance between them. Wasserstein distance gives a Riemannian metric for the Wasserstein space. It intrinsically measures the dissimilarities between shapes and thus has the potential for shape classification. To the best of our knowledge, this is the first work to introduce the optimal mass transport map to general Riemannian manifolds. The method is based on geodesic power Voronoi diagram. Comparing to the conventional methods, our approach solely depends on Riemannian metrics and is invariant under rigid motions and scalings, thus it intrinsically measures shape distance. Experimental results on classifying brain cortical surfaces with different intelligence quotients demonstrated the efficiency and efficacy of our method. PMID:26221691

CFD simulation of the gas flow in a pulse tube cryocooler with two pulse tubes

NASA Astrophysics Data System (ADS)

Yin, C. L.

2015-12-01

In this paper, in order to instruct the next optimization work, a two-dimension Computational Fluid Dynamics (CFD) model is developed to simulate temperature distribution and velocity distribution of oscillating fluid in the DPTC by individual phase-shifting. It is found that the axial temperature distribution of regenerator is generally uniform and the temperatures near the center at the same cross setion of two pulse tubes are obviously higher than their near wall temperatures. The wall temperature difference about 0-7 K exists between the two pulse tubes. The velocity distribution near the center of the regenerator is uniform and there is obvious injection stream coming at the center of the pulse tubes from the hot end. The formation reason of temperature distribution and velocity distribution is explained.

Plasmon mass scale in two-dimensional classical nonequilibrium gauge theory

NASA Astrophysics Data System (ADS)

Lappi, T.; Peuron, J.

2018-02-01

We study the plasmon mass scale in classical gluodynamics in a two-dimensional configuration that mimics the boost-invariant initial color fields in a heavy-ion collision. We numerically measure the plasmon mass scale using three different methods: a hard thermal loop (HTL) expression involving the quasiparticle spectrum constructed from Coulomb gauge field correlators, an effective dispersion relation, and the measurement of oscillations between electric and magnetic energies after introducing a spatially uniform perturbation to the electric field. We find that the HTL expression and the uniform electric field measurement are in rough agreement. The effective dispersion relation agrees with other methods within a factor of 2. We also study the dependence on time and occupation number, observing similar trends as in three spatial dimensions, where a power-law dependence sets in after an occupation-number-dependent transient time. We observe a decrease of the plasmon mass squared as t-1 / 3 at late times.

Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

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

Balal, N.; Magory, E.; Bandurkin, I. V.

2015-10-19

It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect ismore » designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.« less

Evaporative Mass Transfer Behavior of a Complex Immiscible Liquid

PubMed Central

McColl, Colleen M.; Johnson, Gwynn R.; Brusseau, Mark L.

2010-01-01

A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult’s law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium. PMID:18614196

Interferometric study on the mass transfer in cryogenic distillation under magnetic field

NASA Astrophysics Data System (ADS)

Bao, S. R.; Zhang, R. P.; Y Rong, Y.; Zhi, X. Q.; Qiu, L. M.

2017-12-01

Cryogenic distillation has long been used for the mass production of industrial gases because of its features of high efficiency, high purity, and capability to produce noble gases. It is of great theoretical and practical significance to explore methods to improve the mass transfer efficiency in cryogenic distillation. The negative correlation between the susceptibility of paramagnetic oxygen and temperature provides a new possibility of comprehensive utilization of boiling point and susceptibility differences in cryogenic distillation. Starting from this concept, we proposed a novel distillation intensifying method by using gradient magnetic field, in which the magnetic forces enhance the transport of the oxygen molecules to the liquid phase in the distillation. In this study, a cryogenic testbed was designed and fabricated to study the diffusion between oxygen and nitrogen under magnetic field. A Mach-Zehnder interferometer was used to visualize the concentration distribution during the diffusion process. The mass transfer characteristics with and without magnetic field, in the chamber filled with the magnetized medium, were systematically studied. The concentration redistribution of oxygen was observed, and the stable stratified diffusion between liquid oxygen and nitrogen was prolonged by the non-uniform magnetic field. The experimental results show that the magnetic field can efficiently influence the mass transfer in cryogenic distillation, which can provide a new mechanism for the optimization of air separation process.

Evaporative mass transfer behavior of a complex immiscible liquid.

PubMed

McColl, Colleen M; Johnson, Gwynn R; Brusseau, Mark L

2008-09-01

A series of laboratory experiments was conducted with a multiple-component immiscible liquid, collected from the Picillo Farm Superfund Site in Rhode Island, to examine liquid-vapor mass-transfer behavior. The immiscible liquid, which comprises solvents, oils, pesticides, PCBs, paint sludges, explosives, and other compounds, was characterized using gas chromatography and gas chromatography/mass spectrometry to determine mole fractions of selected constituents. Batch experiments were conducted to evaluate equilibrium phase-partitioning behavior. Two sets of air-stripping column studies were conducted to examine the mass-transfer dynamics of five selected target compounds present in the immiscible-liquid mixture. One set of column experiments was designed to represent a system with free-phase immiscible liquid present; the other was designed to represent a system with a residual phase of immiscible liquid. Initial elution behavior of all target components generally appeared to be ideal for both systems, as the initial vapor-phase concentrations were similar to vapor-phase concentrations measured for the batch experiment and those estimated using Raoult's law (incorporating the immiscible-liquid composition data). Later-stage removal of 1,2-dichlorobenzene appeared to be rate limited for the columns containing free-phase immiscible liquid and no porous medium. Conversely, evaporative mass transfer appeared to be ideal throughout the experiment conducted with immiscible liquid distributed relatively uniformly as a residual phase within a sandy porous medium.

High-Resolution Imaging of Selenium in Kidneys: A Localized Selenium Pool Associated with Glutathione Peroxidase 3

PubMed Central

Malinouski, Mikalai; Kehr, Sebastian; Finney, Lydia; Vogt, Stefan; Carlson, Bradley A.; Seravalli, Javier; Jin, Richard; Handy, Diane E.; Park, Thomas J.; Loscalzo, Joseph; Hatfield, Dolph L.

2012-01-01

Abstract Aim: Recent advances in quantitative methods and sensitive imaging techniques of trace elements provide opportunities to uncover and explain their biological roles. In particular, the distribution of selenium in tissues and cells under both physiological and pathological conditions remains unknown. In this work, we applied high-resolution synchrotron X-ray fluorescence microscopy (XFM) to map selenium distribution in mouse liver and kidney. Results: Liver showed a uniform selenium distribution that was dependent on selenocysteine tRNA[Ser]Sec and dietary selenium. In contrast, kidney selenium had both uniformly distributed and highly localized components, the latter visualized as thin circular structures surrounding proximal tubules. Other parts of the kidney, such as glomeruli and distal tubules, only manifested the uniformly distributed selenium pattern that co-localized with sulfur. We found that proximal tubule selenium localized to the basement membrane. It was preserved in Selenoprotein P knockout mice, but was completely eliminated in glutathione peroxidase 3 (GPx3) knockout mice, indicating that this selenium represented GPx3. We further imaged kidneys of another model organism, the naked mole rat, which showed a diminished uniformly distributed selenium pool, but preserved the circular proximal tubule signal. Innovation: We applied XFM to image selenium in mammalian tissues and identified a highly localized pool of this trace element at the basement membrane of kidneys that was associated with GPx3. Conclusion: XFM allowed us to define and explain the tissue topography of selenium in mammalian kidneys at submicron resolution. Antioxid. Redox Signal. 16, 185–192. PMID:21854231

Regular expansion solutions for small Peclet number heat or mass transfer in concentrated two-phase particulate systems

NASA Technical Reports Server (NTRS)

Yaron, I.

1974-01-01

Steady state heat or mass transfer in concentrated ensembles of drops, bubbles or solid spheres in uniform, slow viscous motion, is investigated. Convective effects at small Peclet numbers are taken into account by expanding the nondimensional temperature or concentration in powers of the Peclet number. Uniformly valid solutions are obtained, which reflect the effects of dispersed phase content and rate of internal circulation within the fluid particles. The dependence of the range of Peclet and Reynolds numbers, for which regular expansions are valid, on particle concentration is discussed.

Airborne measurements of organosulfates over the continental U.S.

NASA Astrophysics Data System (ADS)

Liao, Jin; Froyd, Karl D.; Murphy, Daniel M.; Keutsch, Frank N.; Yu, Ge; Wennberg, Paul O.; St. Clair, Jason M.; Crounse, John D.; Wisthaler, Armin; Mikoviny, Tomas; Jimenez, Jose L.; Campuzano-Jost, Pedro; Day, Douglas A.; Hu, Weiwei; Ryerson, Thomas B.; Pollack, Ilana B.; Peischl, Jeff; Anderson, Bruce E.; Ziemba, Luke D.; Blake, Donald R.; Meinardi, Simone; Diskin, Glenn

2015-04-01

Organosulfates are important secondary organic aerosol (SOA) components and good tracers for aerosol heterogeneous reactions. However, the knowledge of their spatial distribution, formation conditions, and environmental impact is limited. In this study, we report two organosulfates, an isoprene-derived isoprene epoxydiols (IEPOX) (2,3-epoxy-2-methyl-1,4-butanediol) sulfate and a glycolic acid (GA) sulfate, measured using the NOAA Particle Analysis Laser Mass Spectrometer (PALMS) on board the NASA DC8 aircraft over the continental U.S. during the Deep Convective Clouds and Chemistry Experiment (DC3) and the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS). During these campaigns, IEPOX sulfate was estimated to account for 1.4% of submicron aerosol mass (or 2.2% of organic aerosol mass) on average near the ground in the southeast U.S., with lower concentrations in the western U.S. (0.2-0.4%) and at high altitudes (<0.2%). Compared to IEPOX sulfate, GA sulfate was more uniformly distributed, accounting for about 0.5% aerosol mass on average, and may be more abundant globally. A number of other organosulfates were detected; none were as abundant as these two. Ambient measurements confirmed that IEPOX sulfate is formed from isoprene oxidation and is a tracer for isoprene SOA formation. The organic precursors of GA sulfate may include glycolic acid and likely have both biogenic and anthropogenic sources. Higher aerosol acidity as measured by PALMS and relative humidity tend to promote IEPOX sulfate formation, and aerosol acidity largely drives in situ GA sulfate formation at high altitudes. This study suggests that the formation of aerosol organosulfates depends not only on the appropriate organic precursors but also on emissions of anthropogenic sulfur dioxide (SO2), which contributes to aerosol acidity.

SDSS-IV MaNGA: the spatial distribution of star formation and its dependence on mass, structure, and environment

NASA Astrophysics Data System (ADS)

Spindler, Ashley; Wake, David; Belfiore, Francesco; Bershady, Matthew; Bundy, Kevin; Drory, Niv; Masters, Karen; Thomas, Daniel; Westfall, Kyle; Wild, Vivienne

2018-05-01

We study the spatially resolved star formation of 1494 galaxies in the SDSS-IV MaNGA Survey. Star formation rates (SFRs) are calculated using a two-step process, using H α in star-forming regions and Dn4000 in regions identified as active galactic nucleus/low-ionization (nuclear) emission region [AGN/LI(N)ER] or lineless. The roles of secular and environmental quenching processes are investigated by studying the dependence of the radial profiles of specific star formation rate on stellar mass, galaxy structure, and environment. We report on the existence of `centrally suppressed' galaxies, which have suppressed Specific Star Formation Rate (SSFR) in their cores compared to their discs. The profiles of centrally suppressed and unsuppressed galaxies are distributed in a bimodal way. Galaxies with high stellar mass and core velocity dispersion are found to be much more likely to be centrally suppressed than low-mass galaxies, and we show that this is related to morphology and the presence of AGN/LI(N)ER like emission. Centrally suppressed galaxies also display lower star formation at all radii compared to unsuppressed galaxies. The profiles of central and satellite galaxies are also compared, and we find that satellite galaxies experience lower specific star formation rates at all radii than central galaxies. This uniform suppression could be a signal of the stripping of hot halo gas in the process known as strangulation. We find that satellites are not more likely to be suppressed in their cores than centrals, indicating that the core suppression is an entirely internal process. We find no correlation between the local environment density and the profiles of star formation rate surface density.

Free in-plane vibration of circular arches.

NASA Technical Reports Server (NTRS)

Veletsos, A. S.; Austin, W. J.; Lopes Pereira, C. A.; Wung, S.-J.

1972-01-01

Numerical data are presented for the natural frequencies and modes of vibration of hinged and fixed, uniform, circular arches vibrating in their own plane, and the effects of the various parameters affecting the response are analyzed. It is shown that the vibrational modes may be almost purely flexural, or almost purely extensional, or the extensional and flexural actions may be strongly coupled. The conditions of occurrence of each type of behavior are defined, and simple approximate formulas are derived; using these formulas, the free vibrational characteristics of arches may be estimated to a satisfactory degree of accuracy for most practical applications. The approach used to derive the approximate formulas may also be applied to arches having other boundary conditions, shapes, or distributions of stiffness and mass.

Isotropy equilibrium of the double woven fabric with cotton face and wool reverse fibrous compositions

NASA Astrophysics Data System (ADS)

Rahnev, I.; Rimini, G.

2017-10-01

The equilibrium of the masses and the mechanical properties between the warp and the weft is a determining factor for the quality of the woven fabrics. When the fabric has a multi-layered structure and is designed for protective clothing, the uniform distribution of the elastical resistance acquires a paramount importance for the consumer properties. Isotropy in the sense of absolute equalising of the properties between the base and the weft evaluates the achieved optimum cohesion between the weaving threads and directs the weaving cycle settings. The possible variation of the ratio between the elastic modules of the warp and the weft, depending on the weft spacing and the warp tension, is the basic idea of this article.

The Design and Construction of the MICE Spectrometer Solenoids

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

Wang, Bert; Wahrer, Bob; Taylor, Clyde

2008-08-02

The purpose of the MICE spectrometer solenoid is to provide a uniform field for a scintillating fiber tracker. The uniform field is produced by a long center coil and two short end coils. Together, they produce 4T field with a uniformity of better than 1% over a detector region of 1000 mm long and 300 mm in diameter. Throughout most of the detector region, the field uniformity is better than 0.3%. In addition to the uniform field coils, we have two match coils. These two coils can be independently adjusted to match uniform field region to the focusing coil field.more » The coil package length is 2544 mm. We present the spectrometer solenoid cold mass design, the powering and quench protection circuits, and the cryogenic cooling system based on using three cryocoolers with re-condensers.« less

High-voltage electrode optimization towards uniform surface treatment by a pulsed volume discharge

NASA Astrophysics Data System (ADS)

Ponomarev, A. V.; Pedos, M. S.; Scherbinin, S. V.; Mamontov, Y. I.; Ponomarev, S. V.

2015-11-01

In this study, the shape and material of the high-voltage electrode of an atmospheric pressure plasma generation system were optimised. The research was performed with the goal of achieving maximum uniformity of plasma treatment of the surface of the low-voltage electrode with a diameter of 100 mm. In order to generate low-temperature plasma with the volume of roughly 1 cubic decimetre, a pulsed volume discharge was used initiated with a corona discharge. The uniformity of the plasma in the region of the low-voltage electrode was assessed using a system for measuring the distribution of discharge current density. The system's low-voltage electrode - collector - was a disc of 100 mm in diameter, the conducting surface of which was divided into 64 radially located segments of equal surface area. The current at each segment was registered by a high-speed measuring system controlled by an ARM™-based 32-bit microcontroller. To facilitate the interpretation of results obtained, a computer program was developed to visualise the results. The program provides a 3D image of the current density distribution on the surface of the low-voltage electrode. Based on the results obtained an optimum shape for a high-voltage electrode was determined. Uniformity of the distribution of discharge current density in relation to distance between electrodes was studied. It was proven that the level of non-uniformity of current density distribution depends on the size of the gap between electrodes. Experiments indicated that it is advantageous to use graphite felt VGN-6 (Russian abbreviation) as the material of the high-voltage electrode's emitting surface.

The Effect of Small Sample Size on Measurement Equivalence of Psychometric Questionnaires in MIMIC Model: A Simulation Study.

PubMed

Jamali, Jamshid; Ayatollahi, Seyyed Mohammad Taghi; Jafari, Peyman

2017-01-01

Evaluating measurement equivalence (also known as differential item functioning (DIF)) is an important part of the process of validating psychometric questionnaires. This study aimed at evaluating the multiple indicators multiple causes (MIMIC) model for DIF detection when latent construct distribution is nonnormal and the focal group sample size is small. In this simulation-based study, Type I error rates and power of MIMIC model for detecting uniform-DIF were investigated under different combinations of reference to focal group sample size ratio, magnitude of the uniform-DIF effect, scale length, the number of response categories, and latent trait distribution. Moderate and high skewness in the latent trait distribution led to a decrease of 0.33% and 0.47% power of MIMIC model for detecting uniform-DIF, respectively. The findings indicated that, by increasing the scale length, the number of response categories and magnitude DIF improved the power of MIMIC model, by 3.47%, 4.83%, and 20.35%, respectively; it also decreased Type I error of MIMIC approach by 2.81%, 5.66%, and 0.04%, respectively. This study revealed that power of MIMIC model was at an acceptable level when latent trait distributions were skewed. However, empirical Type I error rate was slightly greater than nominal significance level. Consequently, the MIMIC was recommended for detection of uniform-DIF when latent construct distribution is nonnormal and the focal group sample size is small.

The Effect of Small Sample Size on Measurement Equivalence of Psychometric Questionnaires in MIMIC Model: A Simulation Study

PubMed Central

Jafari, Peyman

2017-01-01

Evaluating measurement equivalence (also known as differential item functioning (DIF)) is an important part of the process of validating psychometric questionnaires. This study aimed at evaluating the multiple indicators multiple causes (MIMIC) model for DIF detection when latent construct distribution is nonnormal and the focal group sample size is small. In this simulation-based study, Type I error rates and power of MIMIC model for detecting uniform-DIF were investigated under different combinations of reference to focal group sample size ratio, magnitude of the uniform-DIF effect, scale length, the number of response categories, and latent trait distribution. Moderate and high skewness in the latent trait distribution led to a decrease of 0.33% and 0.47% power of MIMIC model for detecting uniform-DIF, respectively. The findings indicated that, by increasing the scale length, the number of response categories and magnitude DIF improved the power of MIMIC model, by 3.47%, 4.83%, and 20.35%, respectively; it also decreased Type I error of MIMIC approach by 2.81%, 5.66%, and 0.04%, respectively. This study revealed that power of MIMIC model was at an acceptable level when latent trait distributions were skewed. However, empirical Type I error rate was slightly greater than nominal significance level. Consequently, the MIMIC was recommended for detection of uniform-DIF when latent construct distribution is nonnormal and the focal group sample size is small. PMID:28713828

Characterization and improvement of field CD uniformity for implementation of 0.15-μm technology device using KrF stepper

NASA Astrophysics Data System (ADS)

Hyun, Yoon-Suk; Kim, Dong-Joo; Koh, Cha-Won; Park, Sung-Nam; Kwon, Won-Taik

2003-06-01

xAs the design rule of semiconductor device shrinks, the field CD uniformity gets more important. For mass production of 0.15 μm technology device using KrF stepper having 0.63NA, the improvement of field CD uniformity was one of key issues because field CD uniformity is directly related to device characteristics in some layers. We have experienced steppers that show poor illumination uniformity. With those steppers there was large CD difference of about 10nm between field center and field edges as shown in Figure 1. Although we were using verified reticles, we could not get an acceptable CD uniformity in a field with those steppers. The Field CD uniformity is dominantly dependent of the illumination uniformity of stepper and mask quality. With these optimization, we could control DICD difference between field center and edge to be less than 5nm. In this paper, we characterized the dependency of field CD uniformity according to illumination systems with stepper and scanner, annular illumination uniformity at various stigma, mask CD uniformity and the several types of novel gray filter specifically developed.

Enhancement of a 2D front-tracking algorithm with a non-uniform distribution of Lagrangian markers

NASA Astrophysics Data System (ADS)

Febres, Mijail; Legendre, Dominique

2018-04-01

The 2D front tracking method is enhanced to control the development of spurious velocities for non-uniform distributions of markers. The hybrid formulation of Shin et al. (2005) [7] is considered. A new tangent calculation is proposed for the calculation of the tension force at markers. A new reconstruction method is also proposed to manage non-uniform distributions of markers. We show that for both the static and the translating spherical drop test case the spurious currents are reduced to the machine precision. We also show that the ratio of the Lagrangian grid size Δs over the Eulerian grid size Δx has to satisfy Δs / Δx > 0.2 for ensuring such low level of spurious velocity. The method is found to provide very good agreement with benchmark test cases from the literature.

Results on Vertex Degree and K-Connectivity in Uniform S-Intersection Graphs

DTIC Science & Technology

2014-01-01

distribution. A uniform s-intersection graph models the topology of a secure wireless sensor network employing the widely used s-composite key predistribution scheme. Our theoretical findings is also confirmed by numerical results.

3D reconstruction from non-uniform point clouds via local hierarchical clustering

NASA Astrophysics Data System (ADS)

Yang, Jiaqi; Li, Ruibo; Xiao, Yang; Cao, Zhiguo

2017-07-01

Raw scanned 3D point clouds are usually irregularly distributed due to the essential shortcomings of laser sensors, which therefore poses a great challenge for high-quality 3D surface reconstruction. This paper tackles this problem by proposing a local hierarchical clustering (LHC) method to improve the consistency of point distribution. Specifically, LHC consists of two steps: 1) adaptive octree-based decomposition of 3D space, and 2) hierarchical clustering. The former aims at reducing the computational complexity and the latter transforms the non-uniform point set into uniform one. Experimental results on real-world scanned point clouds validate the effectiveness of our method from both qualitative and quantitative aspects.

Visualization of self-heating of an all climate battery by infrared thermography

NASA Astrophysics Data System (ADS)

Zhang, Guangsheng; Tian, Hua; Ge, Shanhai; Marple, Dan; Sun, Fengchun; Wang, Chao-Yang

2018-02-01

Self-heating Li-ion battery (SHLB), a.k.a. all climate battery, has provided a novel and practical solution to the low temperature power loss challenge. During its rapid self-heating, it is critical to keep the heating process and temperature distributions uniform for superior battery performance, durability and safety. Through infrared thermography of an experimental SHLB cell activated from various low ambient temperatures, we find that temperature distribution is uniform over the active electrode area, suggesting uniform heating. We also find that a hot spot exists at the activation terminal during self-heating, which provides diagnostics for improvement of next generation SHLB cells without the hot spot.

SN 1987A - The evolution from red to blue

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

Tuchman, Y.; Wheeler, J.C.

1989-11-01

Envelope models in thermal and dynamic equilibrium are used to explore the nature of the transition of SK -69 deg 202, the progenitor of SN 1987A, from the Hayashi track to its final blue position in the H-R diagram. Loci of possible thermal equilibrium solutions are presented as a function of Teff and M(C/O), the mass of the carbon/oxygen core interior to the helium burning shell. It is found that uniform helium enrichment of the envelope results in red-blue evolution but that the resulting blue solution is much hotter than SK -69 deg 202. Solutions in which the only changemore » is to redistribute the portion of the envelope enriched in helium during main-sequence convective core contraction into a step function with Y of about 0.5 at a mass cut of about 10 solar masses give a natural transition from red to blue and a final value of Teff in agreement with observations. It is argued that SK -69 deg 202 probably fell on a post-Hayashi track sequence at moderate Teff. The possible connection of this sequence to the step distribution in the H-R diagram of the LMC. 19 refs.« less

Investigation of geological structures with a view to HLRW disposal, as revealed through 3D inversion of aeromagnetic and gravity data and the results of CSAMT exploration

NASA Astrophysics Data System (ADS)

An, Zhiguo; Di, Qingyun

2016-12-01

The Alxa area in Inner Mongolia has been selected as a possible site for geological disposal of high-level radioactive waste (HLRW). Based on results of a previous study on crustal stability, the Tamusu rock mass has been chosen as the target. To determine the geological structure of this rock mass, aeromagnetic and gravity data are collected and inverted. Three-dimensional (3D) inversion horizontal slices show that the internal density of the rock mass and the distribution of magnetic properties are not uniform, with fractures and fragmentation being present. To confirm this result, the controlled source audio-frequency magnetotelluric method (CSAMT) was applied to explore the geological structures, the typical CSAMT sounding curve was analyzed, and the response characteristics of the geological structure and surrounding rock are distinguished. The original data were processed and interpreted in combination with data from surface geology and drilling and logging data. It is found that the CSAMT results were consistent with those from 3D inversion of the gravity and magnetic data, confirming the existence of fractures and fragmentation in the exploration area.

Fluid outlet at the bottom of an in situ oil shale retort

DOEpatents

Hutchins, Ned M.

1984-01-01

Formation is excavated from within the boundaries of a retort site in formation containing oil shale for forming at least one retort level void extending horizontally across the retort site, leaving at least one remaining zone of unfragmented formation within the retort site. A production level drift is excavated below the retort level void, leaving a lower zone of unfragmented formation between the retort level void and the production level drift. A plurality of raises are formed between the production level drift and the retort level void for providing product withdrawal passages distributed generally uniformly across the horizontal cross section of the retort level void. The product withdrawal passages are backfilled with a permeable mass of particles. Explosive placed within the remaining zone of unfragmented formation above the retort level void is detonated for explosively expanding formation within the retort site toward at least the retort level void for forming a fragmented permeable mass of formation particles containing oil shale within the boundaries of the retort site. During retorting operations products of retorting are conducted from the fragmented mass in the retort through the product withdrawal passages to the production level void. The products are withdrawn from the production level void.

Study of flow behavior in all-vanadium redox flow battery using spatially resolved voltage distribution

NASA Astrophysics Data System (ADS)

Bhattarai, Arjun; Wai, Nyunt; Schweiss, Rüdiger; Whitehead, Adam; Scherer, Günther G.; Ghimire, Purna C.; Nguyen, Tam D.; Hng, Huey Hoon

2017-08-01

Uniform flow distribution through the porous electrodes in a flow battery cell is very important for reducing Ohmic and mass transport polarization. A segmented cell approach can be used to obtain in-situ information on flow behaviour, through the local voltage or current mapping. Lateral flow of current within the thick felts in the flow battery can hamper the interpretation of the data. In this study, a new method of segmenting a conventional flow cell is introduced, which for the first time, splits up both the porous felt as well as the current collector. This dual segmentation results in higher resolution and distinct separation of voltages between flow inlet to outlet. To study the flow behavior for an undivided felt, monitoring the OCV is found to be a reliable method, instead of voltage or current mapping during charging and discharging. Our approach to segmentation is simple and applicable to any size of the cell.

Effects of grain development on formation of resistant starch in rice.

PubMed

Shu, Xiaoli; Sun, Jian; Wu, Dianxing

2014-12-01

Three rice mutants with different contents of resistant starch (RS) were selected to investigate the effects of grain filling process on the formation of resistant starch. During grain development, the content of RS was increased with grain maturation and showed negative correlations with the grain weight and the starch molecular weight (Mn, Mw) and a positive correlation with the distribution of molecular mass (polydispersity, Pd). The morphologies of starch granules in high-RS rice were almost uniform in single starch granules and exhibited different proliferation modes from common rice. The lower activities of ADP-glucose pyrophosphorylase and starch branching enzyme and the higher activity of starch synthase and starch de-branching enzyme observed in high-RS rice might be responsible for the formation of small irregular starch granules with large spaces between them. In addition, the lower molecular weight and the broad distribution of molecular weights lead to differences in the physiochemical properties of starch. Copyright © 2014 Elsevier Ltd. All rights reserved.

Flow quality of NAL two-dimensional transonic wind tunnel. Part 1: Mach number distributions, flow angularities and preliminary study of side wall boundary layer suction

NASA Technical Reports Server (NTRS)

Sakakibara, Seizo; Takashima, Kazuaki; Miwa, Hitoshi; Oguni, Yasuo; Sato, Mamoru; Kanda, Hiroshi

1988-01-01

Experimental data on the flow quality of the National Aerospace Laboratory two-dimensional transonic wind tunnel are presented. Mach number distributions on the test section axis show good uniformity which is characterized by the two sigma (standard deviation) values of 0.0003 to 0.001 for a range of Mach numbers from 0.4 to 1.0. Flow angularities, which were measured by using a wing model with a symmetrical cross section, remained within 0.04 deg for Mach numbers from 0.2 to 0.8. Side wall boundary layer suction was applied through a pair of porous plates. The variation of aerodynamic properties of the model due to the suction mass flow rate change is presented with a brief discussion. Two dimensionality of the flow over the wing span is expected to be improved by applying the appropriate suction rate, which depends on the Mach number, Reynolds number, and lift coefficient.

Special features of large-size resistors for high-voltage pulsed installations

NASA Astrophysics Data System (ADS)

Minakova, N. N.; Ushakov, V. Ya.

2017-12-01

Many structural materials in pulsed power engineering operate under extreme conditions. For example, in high-voltage electrophysical installations among which there are multistage high-voltage pulse generators (HVPG), rigid requirements are imposed on characteristics of solid-state resistors that are more promising in comparison with widely used liquid resistors. Materials of such resistors shall be able to withstand strong electric fields, operate at elevated temperatures, in transformer oil, etc. Effective charge of high-voltage capacitors distributed over the HVPG steps (levels) requires uniform voltage distribution along the steps of the installation that can be obtained using large-size resistors. For such applications, polymer composite materials are considered rather promising. They can work in transformer oil and have small mass in comparison with bulky resistors on inorganic basis. This allows technical solutions already developed and implemented in HVPG with liquid resistors to be employed. This paper is devoted to the solution of some tasks related to the application of filled polymers in high-voltage engineering.

Homogenization limit for a multiband effective mass model in heterostructures

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

Morandi, O., E-mail: morandi@ipcms.unistra.fr

We study the homogenization limit of a multiband model that describes the quantum mechanical motion of an electron in a quasi-periodic crystal. In this approach, the distance among the atoms that constitute the material (lattice parameter) is considered a small quantity. Our model include the description of materials with variable chemical composition, intergrowth compounds, and heterostructures. We derive the effective multiband evolution system in the framework of the kp approach. We study the well posedness of the mathematical problem. We compare the effective mass model with the standard kp models for uniform and non-uniforms crystals. We show that in themore » limit of vanishing lattice parameter, the particle density obtained by the effective mass model, converges to the exact probability density of the particle.« less

Conformational effects on cationization of poly(ethylene glycol) by alkali metal ions in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

NASA Astrophysics Data System (ADS)

Shimada, Kayori; Matsuyama, Shigetomo; Saito, Takeshi; Kinugasa, Shinichi; Nagahata, Ritsuko; Kawabata, Shin-Ichirou

2005-12-01

Conformational effects of polymer chains on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) were studied by using an equimolar mixture of uniform poly(ethylene glycol)s (PEGs) and by molecular dynamics simulations. Uniform PEGs with degrees of polymerization n = 8-39 were separated from commercial PEG samples by preparative supercritical fluid chromatography. MALDI-TOFMS spectra of an equimolar mixture of the uniform PEGs in aqueous ethanol were measured by adding a mixture of 2,5-dihydroxybenzoic acid (as a matrix reagent) and five alkali metal chlorides (LiCl, NaCl, KCl, RbCl, and CsCl). After optimization of the matrix concentration and laser power, five types of adduct cationized by Li+, Na+, K+, Rb+, and Cs+ could be identified simultaneously in the same spectrum. In the lower molecular-mass region around 103, the spectral intensity increase rapidly with increasing molecular mass of PEG; this rapid increase in the spectral intensity started at a lower molecular mass for smaller adduct cations. Molecular dynamics simulations were used to calculated the affinity of PEG for the adduct cations. These experimental and simulated results showed that the observed spectral intensities in MALDI-TOFMS were markedly affected by the species of adduct cations and the degree of polymerization of the PEG, and that they were dependent on the stability of the PEG-cation complex.

Design and testing of a uniformly solar energy TIR-R concentration lenses for HCPV systems.

PubMed

Shen, S C; Chang, S J; Yeh, C Y; Teng, P C

2013-11-04

In this paper, total internal reflection-refraction (TIR-R) concentration (U-TIR-R-C) lens module were designed for uniformity using the energy configuration method to eliminate hot spots on the surface of solar cell and increase conversion efficiency. The design of most current solar concentrators emphasizes the high-power concentration of solar energy, however neglects the conversion inefficiency resulting from hot spots generated by uneven distributions of solar energy concentrated on solar cells. The energy configuration method proposed in this study employs the concept of ray tracing to uniformly distribute solar energy to solar cells through a U-TIR-R-C lens module. The U-TIR-R-C lens module adopted in this study possessed a 76-mm diameter, a 41-mm thickness, concentration ratio of 1134 Suns, 82.6% optical efficiency, and 94.7% uniformity. The experiments demonstrated that the U-TIR-R-C lens module reduced the core temperature of the solar cell from 108 °C to 69 °C and the overall temperature difference from 45 °C to 10 °C, and effectively relative increased the conversion efficiency by approximately 3.8%. Therefore, the U-TIR-R-C lens module designed can effectively concentrate a large area of sunlight onto a small solar cell, and the concentrated solar energy can be evenly distributed in the solar cell to achieve uniform irradiance and effectively eliminate hot spots.

Comparison of Turbulent Heat-Transfer Results for Uniform Wall Heat Flux and Uniform Wall Temperature

NASA Technical Reports Server (NTRS)

Siegel, R.; Sparrow, E. M.

1960-01-01

The purpose of this note is to examine in a more precise way how the Nusselt numbers for turbulent heat transfer in both the fully developed and thermal entrance regions of a circular tube are affected by two different wall boundary conditions. The comparisons are made for: (a) Uniform wall temperature (UWT); and (b) uniform wall heat flux (UHF). Several papers which have been concerned with the turbulent thermal entrance region problem are given. 1 Although these analyses have all utilized an eigenvalue formulation for the thermal entrance region there were differences in the choices of eddy diffusivity expressions, velocity distributions, and methods for carrying out the numerical solutions. These differences were also found in the fully developed analyses. Hence when making a comparison of the analytical results for uniform wall temperature and uniform wall heat flux, it was not known if differences in the Nusselt numbers could be wholly attributed to the difference in wall boundary conditions, since all the analytical results were not obtained in a consistent way. To have results which could be directly compared, computations were carried out for the uniform wall temperature case, using the same eddy diffusivity, velocity distribution, and digital computer program employed for uniform wall heat flux. In addition, the previous work was extended to a lower Reynolds number range so that comparisons could be made over a wide range of both Reynolds and Prandtl numbers.

Variable area fuel cell process channels

DOEpatents

Kothmann, Richard E.

1981-01-01

A fuel cell arrangement having a non-uniform distribution of fuel and oxidant flow paths, on opposite sides of an electrolyte matrix, sized and positioned to provide approximately uniform fuel and oxidant utilization rates, and cell conditions, across the entire cell.

10 CFR Appendix A to Subpart K of... - Uniform Test Method for Measuring the Energy Consumption of Distribution Transformers

Code of Federal Regulations, 2014 CFR

2014-01-01

... Uniform Test Method is used to test more than one unit of a basic model to determine the efficiency of... one ampere and the test current is limited to 15 percent of the winding current. Connect the... 10 Energy 3 2014-01-01 2014-01-01 false Uniform Test Method for Measuring the Energy Consumption...

Confined energy distribution for charged particle beams

DOEpatents

Jason, Andrew J.; Blind, Barbara

1990-01-01

A charged particle beam is formed to a relatively larger area beam which is well-contained and has a beam area which relatively uniformly deposits energy over a beam target. Linear optics receive an accelerator beam and output a first beam with a first waist defined by a relatively small size in a first dimension normal to a second dimension. Nonlinear optics, such as an octupole magnet, are located about the first waist and output a second beam having a phase-space distribution which folds the beam edges along the second dimension toward the beam core to develop a well-contained beam and a relatively uniform particle intensity across the beam core. The beam may then be expanded along the second dimension to form the uniform ribbon beam at a selected distance from the nonlinear optics. Alternately, the beam may be passed through a second set of nonlinear optics to fold the beam edges in the first dimension. The beam may then be uniformly expanded along the first and second dimensions to form a well-contained, two-dimensional beam for illuminating a two-dimensional target with a relatively uniform energy deposition.

Fisheye camera method for spatial non-uniformity corrections in luminous flux measurements with integrating spheres

NASA Astrophysics Data System (ADS)

Kokka, Alexander; Pulli, Tomi; Poikonen, Tuomas; Askola, Janne; Ikonen, Erkki

2017-08-01

This paper presents a fisheye camera method for determining spatial non-uniformity corrections in luminous flux measurements with integrating spheres. Using a fisheye camera installed into a port of an integrating sphere, the relative angular intensity distribution of the lamp under test is determined. This angular distribution is used for calculating the spatial non-uniformity correction for the lamp when combined with the spatial responsivity data of the sphere. The method was validated by comparing it to a traditional goniophotometric approach when determining spatial correction factors for 13 LED lamps with different angular spreads. The deviations between the spatial correction factors obtained using the two methods ranged from -0.15 % to 0.15%. The mean magnitude of the deviations was 0.06%. For a typical LED lamp, the expanded uncertainty (k = 2 ) for the spatial non-uniformity correction factor was evaluated to be 0.28%. The fisheye camera method removes the need for goniophotometric measurements in determining spatial non-uniformity corrections, thus resulting in considerable system simplification. Generally, no permanent modifications to existing integrating spheres are required.

The mass function of black holes 1

NASA Astrophysics Data System (ADS)

Natarajan, Priyamvada; Volonteri, Marta

2012-05-01

In this paper, we compare the observationally derived black hole mass function (BHMF) of luminous (>1045-1046 erg s-1) broad-line quasars (BLQSOs) at 1 < z < 4.5 drawn from the Sloan Digital Sky Survey (SDSS) presented by Kelly et al., with models of merger-driven black hole (BH) growth in the context of standard hierarchical structure formation models. In these models, we explore two distinct black hole seeding prescriptions at the highest redshifts: 'light seeds'- remnants of Population III stars and 'massive seeds' that form from the direct collapse of pre-galactic discs. The subsequent merger triggered mass build-up of the black hole population is tracked over cosmic time under the assumption of a fixed accretion rate as well as rates drawn from the distribution derived by Merloni & Heinz. Four model snapshots at z= 1.25, 2, 3.25 and 4.25 are compared with the SDSS-derived BHMFs of BLQSOs. We find that the light seed models fall short of reproducing the observationally derived mass function of BLQSOs at MBH > 109 M⊙ throughout the redshift range; the massive seed models with a fixed accretion rate of 0.3 Edd, or with accretion rates drawn from the Merloni & Heinz distribution provide the best fit to the current observational data at z > 2, although they overestimate the high-mass end of the mass function at lower redshifts. At low redshifts, a drastic drop in the accretion rate is observed and this is explained as arising due to the diminished gas supply available due to consumption by star formation or changes in the geometry of the inner feeding regions. Therefore, the overestimate at the high-mass end of the black hole mass function for the massive seed models can be easily modified, as the accretion rate is likely significantly lower at these epochs than what we assume. For the Merloni & Heinz model, examining the Eddington ratio distributions fEdd, we find that they are almost uniformly sampled from fEdd= 10-2 to 1 at z≃ 1, while at high redshift, current observations suggest accretion rates close to Eddington, if not mildly super-Eddington, at least for these extremely luminous quasars. Our key findings are that the duty cycle of super-massive black holes powering BLQSOs increases with increasing redshift for all models and models with Population III remnants as black hole seeds are unable to fit the observationally derived BHMFs for BLQSOs, lending strong support for the massive seeding model.

Orbital Motion of Electrically Charged Spheres in Microgravity

ERIC Educational Resources Information Center

Banerjee, Shubho; Andring, Kevin; Campbell, Desmond; Janeski, John; Keedy, Daniel; Quinn, Sean; Hoffmeister, Brent

2008-01-01

The similar mathematical forms of Coulomb's law and Newton's law of gravitation suggest that two uniformly charged spheres should be able to orbit each other just as two uniform spheres of mass are known to do. In this paper we describe an experiment that we performed to demonstrate such an orbit. This is the first published account of a…

Maxwell-Faraday Stresses in Electromagnetic Fields and the Self-Force on a Uniformly Accelerating Point Charge

ERIC Educational Resources Information Center

Rowland, D. R.

2007-01-01

The physical analysis of a uniformly accelerating point charge provides a rich problem to explore in advanced courses in electrodynamics and relativity since it brings together fundamental concepts in relation to electromagnetic radiation, Einstein's equivalence principle and the inertial mass of field energy in ways that reveal subtleties in each…

Combined Loads Test Fixture for Thermal-Structural Testing Aerospace Vehicle Panel Concepts

NASA Technical Reports Server (NTRS)

Fields, Roger A.; Richards, W. Lance; DeAngelis, Michael V.

2004-01-01

A structural test requirement of the National Aero-Space Plane (NASP) program has resulted in the design, fabrication, and implementation of a combined loads test fixture. Principal requirements for the fixture are testing a 4- by 4-ft hat-stiffened panel with combined axial (either tension or compression) and shear load at temperatures ranging from room temperature to 915 F, keeping the test panel stresses caused by the mechanical loads uniform, and thermal stresses caused by non-uniform panel temperatures minimized. The panel represents the side fuselage skin of an experimental aerospace vehicle, and was produced for the NASP program. A comprehensive mechanical loads test program using the new test fixture has been conducted on this panel from room temperature to 500 F. Measured data have been compared with finite-element analyses predictions, verifying that uniform load distributions were achieved by the fixture. The overall correlation of test data with analysis is excellent. The panel stress distributions and temperature distributions are very uniform and fulfill program requirements. This report provides details of an analytical and experimental validation of the combined loads test fixture. Because of its simple design, this unique test fixture can accommodate panels from a variety of aerospace vehicle designs.

Leveraging the power of a planet population: Mass-radius relation, host star multiplicity, and composition distribution of Kepler's sub-Neptunes

NASA Astrophysics Data System (ADS)

Wolfgang, Angie K.

With the advent of large, dedicated planet hunting surveys, the search for extrasolar planets has evolved into an effort to understand the properties and formation of a planet population whose characteristics continue to surprise the provincial perspective we've derived from our own Solar System. The Kepler Mission in particular has enabled a large number of these studies, as it was designed to stare simultaneously at thousands of stars for several years and its automated transit search pipeline enables fairly uniform detection criteria and characterizable completeness and false positive rates. With the detection of nearly 5000 planet candidates, 80% of which are smaller than 4 REarth, Kepler has especially illuminated the unexpectedly vast sub-Neptune population. Such a rich dataset provides an unprecedented opportunity for rigorous statistical study of the physics of these planets that have no analogs in our Solar System. Contributing to this endeavor, I present the statistical characterization of several aspects of this population, including the comparison between Kepler's planet candidates and low-mass occurrence rates inferred from radial velocity detections, the relationship between a sub-Neptune's mass and its radius, the frequency of Kepler planet candidate host stars which have nearby visual companions as revealed by follow-up high resolution imaging, and the distribution of gaseous mass fractions that these sub-Neptunes could possess given a rock-plus-hydrogen composition. To do so, I have used sophisticated statistical analyses such as Monte Carlo simulations and hierarchical Bayesian modeling to tie theory more closely to observations and have acquired near infrared laser guide star adaptive optics imaging of 196 Kepler Objects of Interest. I find that even within this sub-Neptune population these planets are very diverse in nature: there is intrinsic scatter in masses at a given radius, the planet host stars have visual companions at a wide range of separations, and the composition distribution spans two orders of magnitude, with a peak at 1% hydrogen and helium by mass. There is much work to be done to explain this diversity quantitatively, and especially to tie these results to various planet formation scenarios; I have no doubt that many more surprises await us.

Modelling the growth of plants with a uniform growth logistics.

PubMed

Kilian, H G; Bartkowiak, D; Kazda, M; Kaufmann, D

2014-05-21

The increment model has previously been used to describe the growth of plants in general. Here, we examine how the same logistics enables the development of different superstructures. Data from the literature are analyzed with the increment model. Increments are growth-invariant molecular clusters, treated as heuristic particles. This approach formulates the law of mass action for multi-component systems, describing the general properties of superstructures which are optimized via relaxation processes. The daily growth patterns of hypocotyls can be reproduced implying predetermined growth invariant model parameters. In various species, the coordinated formation and death of fine roots are modeled successfully. Their biphasic annual growth follows distinct morphological programs but both use the same logistics. In tropical forests, distributions of the diameter in breast height of trees of different species adhere to the same pattern. Beyond structural fluctuations, competition and cooperation within and between the species may drive optimization. All superstructures of plants examined so far could be reproduced with our approach. With genetically encoded growth-invariant model parameters (interaction with the environment included) perfect morphological development runs embedded in the uniform logistics of the increment model. Copyright © 2014 Elsevier Ltd. All rights reserved.

Examination of global correlations in ground deformation for terrestrial reference frame estimation

NASA Astrophysics Data System (ADS)

Chin, T. M.; Abbondanza, C.; Argus, D. F.; Gross, R. S.; Heflin, M. B.; Parker, J. W.; Wu, X.

2016-12-01

The KALman filter for REFerence frames (KALREF, Wu et al. 2015) has been developed to produce terrestrial reference frame (TRF) solutions. TRFs consist of precise position coordinates and velocity vectors of terrestrial reference sites (with the geocenter as the origin) along with the Earth orientation parameters, and they are produced by combining decades worth of space geodetic data using site tie data. To perform the combination, KALREF relies on stochastic models of the geophysical processes that are causing the Earth's surface to deform and reference sites to be displaced. We are investigating application of the GRACE data to improve the KALREF stochastic models by determining spatial statistics of the deformation of the Earth's surface caused by mass loading. A potential target of improvement is the non-uniform distribution of the geodetic observation sites, which can introduce bias in TRF estimates of the geocenter. The global and relatively uniform coverage of the GRACE measurements is expected to be free of such bias and allow us to improve physical realism of the stochastic model. For such a goal, we examine the spatial correlations in ground deformation derived from several GRACE data sets.[Wu et al. 2015: Journal of Geophysical Research (Solid Earth) 120:3775-3802

Estimating Hyrdologic Properties of Groundwater Wells Using Tracer Pulse Dynamic Flow Profiling

NASA Astrophysics Data System (ADS)

Miles, K. A.; Heller, N.

2016-12-01

Traditional groundwater well design places the pump intake above the top of the well screen. It is common in this case to design the well screen for uniform entrance velocity along the profile of the well screen, even though non-uniform flow may occur. Particularly in the case where the pump is set near the very top or bottom of the well, there are instances where the zonal testing with a test pump indicates favorable water quality at one pump depth of the groundwater production well, and the water quality results yielded from the well at another depth are not compliant with federal and state regulatory limits for various naturally occurring and anthropogenic compounds. Well bore flow velocity and chemistry were determined using the USGS Tracer Pulse Dynamic Flow Profiling method along the length of well screens, while varying the pump depth. The information was then used to perform a flow and chemical mass balance to characterize the distribution of flow and chemical contribution, groundwater well screen entrance velocities, and hydrologic parameters. The presented results show pump placement affecting the average chemical discharge, and entrance velocities along the length of well screens.

Characteristics of trace metals in traffic-derived particles in Hsuehshan Tunnel, Taiwan: size distribution, fingerprinting metal ratio, and emission factor

NASA Astrophysics Data System (ADS)

Lin, Y.-C.; Tsai, C.-J.; Wu, Y.-C.; Zhang, R.; Chi, K.-H.; Huang, Y.-T.; Lin, S.-H.; Hsu, S.-C.

2014-05-01

Traffic emissions are a significant source of airborne particulate matter (PM) in ambient environments. These emissions contain high abundance of toxic metals and thus pose adverse effects on human health. Size-fractionated aerosol samples were collected from May to September 2013 by using micro-orifice uniform deposited impactor (MOUDI). Sample collection was conducted simultaneously at the inlet and outlet sites of Hsuehshan Tunnel in northern Taiwan, which is the second longest freeway tunnel (12.9 km) in Asia. Such endeavor aims to characterize the chemical constituents, size distributions, and fingerprinting ratios, as well as the emission factors of particulate metals emitted by vehicle fleets. A total of 36 metals in size-resolved aerosols were determined through inductively coupled plasma mass spectrometry. Three major groups, namely, tailpipe emissions (Zn, Pb, and V), wear debris (Cu, Cd, Fe, Ga, Mn, Mo, Sb, and Sn), and resuspended dust (Ca, Mg, K, and Rb), of airborne PM metals were categorized on the basis of the results of enrichment factor, correlation matrix, and principal component analysis. Size distributions of wear-originated metals resembled the pattern of crustal elements, which were predominated by super-micron particulates (PM1-10). By contrast, tailpipe exhaust elements such as Zn, Pb, and V were distributed mainly in submicron particles. By employing Cu as a tracer of wear abrasion, several inter-metal ratios, including Fe/Cu (14), Ba/Cu (1.05), Sb/Cu (0.16), Sn/Cu (0.10), and Ga/Cu (0.03), served as fingerprints for wear debris. Emission factor of PM10 mass was estimated to be 7.7 mg vkm-1. The metal emissions were mostly predominated in super-micron particles (PM1-10). Finally, factors that possibly affect particulate metal emissions inside Hsuehshan Tunnel are discussed.

Accretion rates of protoplanets 2: Gaussian distribution of planestesimal velocities

NASA Technical Reports Server (NTRS)

Greenzweig, Yuval; Lissauer, Jack J.

1991-01-01

The growth rate of a protoplanet embedded in a uniform surface density disk of planetesimals having a triaxial Gaussian velocity distribution was calculated. The longitudes of the aspses and nodes of the planetesimals are uniformly distributed, and the protoplanet is on a circular orbit. The accretion rate in the two body approximation is enhanced by a factor of approximately 3, compared to the case where all planetesimals have eccentricity and inclination equal to the root mean square (RMS) values of those variables in the Gaussian distribution disk. Numerical three body integrations show comparable enhancements, except when the RMS initial planetesimal eccentricities are extremely small. This enhancement in accretion rate should be incorporated by all models, analytical or numerical, which assume a single random velocity for all planetesimals, in lieu of a Gaussian distribution.

Therapeutic analysis of high-dose-rate {sup 192}Ir vaginal cuff brachytherapy for endometrial cancer using a cylindrical target volume model and varied cancer cell distributions

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

Zhang, Hualin, E-mail: hualin.zhang@northwestern.edu; Donnelly, Eric D.; Strauss, Jonathan B.

Purpose: To evaluate high-dose-rate (HDR) vaginal cuff brachytherapy (VCBT) in the treatment of endometrial cancer in a cylindrical target volume with either a varied or a constant cancer cell distributions using the linear quadratic (LQ) model. Methods: A Monte Carlo (MC) technique was used to calculate the 3D dose distribution of HDR VCBT over a variety of cylinder diameters and treatment lengths. A treatment planning system (TPS) was used to make plans for the various cylinder diameters, treatment lengths, and prescriptions using the clinical protocol. The dwell times obtained from the TPS were fed into MC. The LQ model wasmore » used to evaluate the therapeutic outcome of two brachytherapy regimens prescribed either at 0.5 cm depth (5.5 Gy × 4 fractions) or at the vaginal mucosal surface (8.8 Gy × 4 fractions) for the treatment of endometrial cancer. An experimentally determined endometrial cancer cell distribution, which showed a varied and resembled a half-Gaussian distribution, was used in radiobiology modeling. The equivalent uniform dose (EUD) to cancer cells was calculated for each treatment scenario. The therapeutic ratio (TR) was defined by comparing VCBT with a uniform dose radiotherapy plan in term of normal cell survival at the same level of cancer cell killing. Calculations of clinical impact were run twice assuming two different types of cancer cell density distributions in the cylindrical target volume: (1) a half-Gaussian or (2) a uniform distribution. Results: EUDs were weakly dependent on cylinder size, treatment length, and the prescription depth, but strongly dependent on the cancer cell distribution. TRs were strongly dependent on the cylinder size, treatment length, types of the cancer cell distributions, and the sensitivity of normal tissue. With a half-Gaussian distribution of cancer cells which populated at the vaginal mucosa the most, the EUDs were between 6.9 Gy × 4 and 7.8 Gy × 4, the TRs were in the range from (5.0){sup 4} to (13.4){sup 4} for the radiosensitive normal tissue depending on the cylinder size, treatment lengths, prescription depth, and dose as well. However, for a uniform cancer cell distribution, the EUDs were between 6.3 Gy × 4 and 7.1 Gy × 4, and the TRs were found to be between (1.4){sup 4} and (1.7){sup 4}. For the uniformly interspersed cancer and radio-resistant normal cells, the TRs were less than 1. The two VCBT prescription regimens were found to be equivalent in terms of EUDs and TRs. Conclusions: HDR VCBT strongly favors cylindrical target volume with the cancer cell distribution following its dosimetric trend. Assuming a half-Gaussian distribution of cancer cells, the HDR VCBT provides a considerable radiobiological advantage over the external beam radiotherapy (EBRT) in terms of sparing more normal tissues while maintaining the same level of cancer cell killing. But for the uniform cancer cell distribution and radio-resistant normal tissue, the radiobiology outcome of the HDR VCBT does not show an advantage over the EBRT. This study strongly suggests that radiation therapy design should consider the cancer cell distribution inside the target volume in addition to the shape of target.« less

Forecasting the Rupture Directivity of Large Earthquakes: Centroid Bias of the Conditional Hypocenter Distribution

NASA Astrophysics Data System (ADS)

Donovan, J.; Jordan, T. H.

2012-12-01

Forecasting the rupture directivity of large earthquakes is an important problem in probabilistic seismic hazard analysis (PSHA), because directivity is known to strongly influence ground motions. We describe how rupture directivity can be forecast in terms of the "conditional hypocenter distribution" or CHD, defined to be the probability distribution of a hypocenter given the spatial distribution of moment release (fault slip). The simplest CHD is a uniform distribution, in which the hypocenter probability density equals the moment-release probability density. For rupture models in which the rupture velocity and rise time depend only on the local slip, the CHD completely specifies the distribution of the directivity parameter D, defined in terms of the degree-two polynomial moments of the source space-time function. This parameter, which is zero for a bilateral rupture and unity for a unilateral rupture, can be estimated from finite-source models or by the direct inversion of seismograms (McGuire et al., 2002). We compile D-values from published studies of 65 large earthquakes and show that these data are statistically inconsistent with the uniform CHD advocated by McGuire et al. (2002). Instead, the data indicate a "centroid biased" CHD, in which the expected distance between the hypocenter and the hypocentroid is less than that of a uniform CHD. In other words, the observed directivities appear to be closer to bilateral than predicted by this simple model. We discuss the implications of these results for rupture dynamics and fault-zone heterogeneities. We also explore their PSHA implications by modifying the CyberShake simulation-based hazard model for the Los Angeles region, which assumed a uniform CHD (Graves et al., 2011).

Polymer powder processing of cryomilled polycaprolactone for solvent-free generation of homogeneous bioactive tissue engineering scaffolds.

PubMed

Lim, Jing; Chong, Mark Seow Khoon; Chan, Jerry Kok Yen; Teoh, Swee-Hin

2014-06-25

Synthetic polymers used in tissue engineering require functionalization with bioactive molecules to elicit specific physiological reactions. These additives must be homogeneously dispersed in order to achieve enhanced composite mechanical performance and uniform cellular response. This work demonstrates the use of a solvent-free powder processing technique to form osteoinductive scaffolds from cryomilled polycaprolactone (PCL) and tricalcium phosphate (TCP). Cryomilling is performed to achieve micrometer-sized distribution of PCL and reduce melt viscosity, thus improving TCP distribution and improving structural integrity. A breakthrough is achieved in the successful fabrication of 70 weight percentage of TCP into a continuous film structure. Following compaction and melting, PCL/TCP composite scaffolds are found to display uniform distribution of TCP throughout the PCL matrix regardless of composition. Homogeneous spatial distribution is also achieved in fabricated 3D scaffolds. When seeded onto powder-processed PCL/TCP films, mesenchymal stem cells are found to undergo robust and uniform osteogenic differentiation, indicating the potential application of this approach to biofunctionalize scaffolds for tissue engineering applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A general description of detachment for multidimensional modelling of biofilms.

PubMed

Xavier, Joao de Bivar; Picioreanu, Cristian; van Loosdrecht, Mark C M

2005-09-20

A general method for describing biomass detachment in multidimensional biofilm modelling is introduced. Biomass losses from processes acting on the entire surface of the biofilm, such as erosion, are modelled using a continuous detachment speed function F(det). Discrete detachment events, i.e. sloughing, are implicitly derived from simulations. The method is flexible to allow F(det) to take several forms, including expressions dependent on any state variables such as the local biofilm density. This methodology for biomass detachment was integrated with multidimensional (2D and 3D) particle-based multispecies biofilm models by using a novel application of the level set method. Application of the method is illustrated by trends in the dynamics of biofilms structure and activity derived from simulations performed on a simple model considering uniform biomass (case study I) and a model discriminating biomass composition in heterotrophic active mass, extracellular polymeric substances (EPS) and inert mass (case study II). Results from case study I demonstrate the effect of applied detachment forces as a fundamental factor influencing steady-state biofilm activity and structure. Trends from experimental observations reported in literature were correctly described. For example, simulation results indicated that biomass sloughing is reduced when erosion forces are increased. Case study II illustrates the application of the detachment methodology to systems with non-uniform biomass composition. Simulations carried out at different bulk concentrations of substrate show changes in biofilm structure (in terms of shape, density and spatial distribution of biomass components) and activity (in terms of oxygen and substrate consumption) as a consequence of either oxygen-limited or substrate-limited growth. (c) 2005 Wiley Periodicals, Inc.

Investigation of the Spatiotemporal Responses of Nanoparticles in Tumor Tissues with a Small-Scale Mathematical Model

PubMed Central

Chou, Cheng-Ying; Huang, Chih-Kang; Lu, Kuo-Wei; Horng, Tzyy-Leng; Lin, Win-Li

2013-01-01

The transport and accumulation of anticancer nanodrugs in tumor tissues are affected by many factors including particle properties, vascular density and leakiness, and interstitial diffusivity. It is important to understand the effects of these factors on the detailed drug distribution in the entire tumor for an effective treatment. In this study, we developed a small-scale mathematical model to systematically study the spatiotemporal responses and accumulative exposures of macromolecular carriers in localized tumor tissues. We chose various dextrans as model carriers and studied the effects of vascular density, permeability, diffusivity, and half-life of dextrans on their spatiotemporal concentration responses and accumulative exposure distribution to tumor cells. The relevant biological parameters were obtained from experimental results previously reported by the Dreher group. The area under concentration-time response curve (AUC) quantified the extent of tissue exposure to a drug and therefore was considered more reliable in assessing the extent of the overall drug exposure than individual concentrations. The results showed that 1) a small macromolecule can penetrate deep into the tumor interstitium and produce a uniform but low spatial distribution of AUC; 2) large macromolecules produce high AUC in the perivascular region, but low AUC in the distal region away from vessels; 3) medium-sized macromolecules produce a relatively uniform and high AUC in the tumor interstitium between two vessels; 4) enhancement of permeability can elevate the level of AUC, but have little effect on its uniformity while enhancement of diffusivity is able to raise the level of AUC and improve its uniformity; 5) a longer half-life can produce a deeper penetration and a higher level of AUC distribution. The numerical results indicate that a long half-life carrier in plasma and a high interstitial diffusivity are the key factors to produce a high and relatively uniform spatial AUC distribution in the interstitium. PMID:23565142

Singularity free N-body simulations called 'Dynamic Universe Model' don't require dark matter

NASA Astrophysics Data System (ADS)

Naga Parameswara Gupta, Satyavarapu

For finding trajectories of Pioneer satellite (Anomaly), New Horizons satellite going to Pluto, the Calculations of Dynamic Universe model can be successfully applied. No dark matter is assumed within solar system radius. The effect on the masses around SUN shows as though there is extra gravitation pull toward SUN. It solves the Dynamics of Extra-solar planets like Planet X, satellite like Pioneer and NH for 3-Position, 3-velocity 3-accelaration for their masses, considering the complex situation of Multiple planets, Stars, Galaxy parts and Galaxy centre and other Galaxies Using simple Newtonian Physics. It already solved problems Missing mass in Galaxies observed by galaxy circular velocity curves successfully. Singularity free Newtonian N-body simulations Historically, King Oscar II of Sweden an-nounced a prize to a solution of N-body problem with advice given by Güsta Mittag-Leffler in 1887. He announced `Given a system of arbitrarily many mass points that attract each according to Newton's law, under the assumption that no two points ever collide, try to find a representation of the coordinates of each point as a series in a variable that is some known function of time and for all of whose values the series converges uniformly.'[This is taken from Wikipedia]. The announced dead line that time was1st June 1888. And after that dead line, on 21st January 1889, Great mathematician Poincaré claimed that prize. Later he himself sent a telegram to journal Acta Mathematica to stop printing the special issue after finding the error in his solution. Yet for such a man of science reputation is important than money. [ Ref Book `Celestial mechanics: the waltz of the planets' By Alessandra Celletti, Ettore Perozzi, page 27]. He realized that he has been wrong in his general stability result! But till now nobody could solve that problem or claimed that prize. Later all solutions resulted in singularities and collisions of masses, given by many people . . . . . . . . . . . . . . . . . . . . . . . . .. Now I can say that the Dynamic Universe Model solves this classical N-body problem where only Newtonian Gravi-tation law and classical Physics were used. The solution converges at all points. There are no multiple values, diverging solutions or divided by zero singularities. Collisions of masses depend on physical values of masses and their space distribution only. These collisions do not happen due to internal inherent problems of Dynamic universe Model. If the mass distribution is homogeneous and isotropic, the masses will colloid. If the mass distribution is heterogeneous and anisotropic, they do not colloid. This approach solves many problems which otherwise can not be solved by General relativity, Steady state universe model etc. . .

Nonimaging polygonal mirrors achieving uniform irradiance distributions on concentrating photovoltaic cells.

PubMed

Schmitz, Max; Dähler, Fabian; Elvinger, François; Pedretti, Andrea; Steinfeld, Aldo

2017-04-10

We introduce a design methodology for nonimaging, single-reflection mirrors with polygonal inlet apertures that generate a uniform irradiance distribution on a polygonal outlet aperture, enabling a multitude of applications within the domain of concentrated photovoltaics. Notably, we present single-mirror concentrators of square and hexagonal perimeter that achieve very high irradiance uniformity on a square receiver at concentrations ranging from 100 to 1000 suns. These optical designs can be assembled in compound concentrators with maximized active area fraction by leveraging tessellation. More advanced multi-mirror concentrators, where each mirror individually illuminates the whole area of the receiver, allow for improved performance while permitting greater flexibility for the concentrator shape and robustness against partial shading of the inlet aperture.

Use of Radon for Evaluation of Atmospheric Transport Models: Sensitivity to Emissions

NASA Technical Reports Server (NTRS)

Gupta, Mohan L.; Douglass, Anne R.; Kawa, S. Randolph; Pawson, Steven

2004-01-01

This paper presents comparative analyses of atmospheric radon (Rn) distributions simulated using different emission scenarios and the observations. Results indicate that the model generally reproduces observed distributions of Rn but there are some biases in the model related to differences in large-scale and convective transport. Simulations presented here use an off-line three-dimensional chemical transport model driven by assimilated winds and two scenarios of Rn fluxes (atom/cm s) from ice-free land surfaces: (A) globally uniform flux of 1.0, and (B) uniform flux of 1.0 between 60 deg. S and 30 deg. N followed by a sharp linear decrease to 0.2 at 70 deg. N. We considered an additional scenario (C) where Rn emissions for case A were uniformly reduced by 28%. Results show that case A overpredicts observed Rn distributions in both hemispheres. Simulated northern hemispheric (NH) Rn distributions from cases B and C compare better with the observations, but are not discernible from each other. In the southern hemisphere, surface Rn distributions from case C compare better with the observations. We performed a synoptic scale source-receptor analysis for surface Rn to locate regions with ratios B/A and B/C less than 0.5. Considering an uncertainty in regional Rn emissions of a factor of two, our analysis indicates that additional measurements of surface Rn particularly during April-October and north of 50 deg. N over the Pacific as well as Atlantic regions would make it possible to determine if the proposed latitude gradient in Rn emissions is superior to a uniform flux scenario.

Effects of non-uniform temperature gradients on surface tension driven two component magneto convection in a porous- fluid system

NASA Astrophysics Data System (ADS)

Manjunatha, N.; Sumithra, R.

2018-04-01

The problem of surface tension driven two component magnetoconvection is investigated in a Porous-Fluid system, consisting of anincompressible two component electrically conducting fluid saturatedporous layer above which lies a layer of the same fluid in the presence of a uniform vertical magnetic field. The lower boundary of the porous layeris rigid and the upper boundary of the fluid layer is free with surfacetension effects depending on both temperature and concentration, boththese boundaries are insulating to heat and mass. At the interface thevelocity, shear and normal stress, heat and heat flux, mass and mass fluxare assumed to be continuous suitable for Darcy-Brinkman model. Theeigenvalue problem is solved in linear, parabolic and inverted parabolictemperature profiles and the corresponding Thermal Marangoni Numberis obtained for different important physical parameters.

Advanced Technology for Ultra-Low Power System-on-Chip (SoC)

DTIC Science & Technology

2017-06-01

design at IDS=1mA/μm compared with that in experimental 14nm-node FinFET. The redistributed electric field along the channel length direction can... design can result in more uniform electron density and electron velocity distributions compared to a homojunction device. This uniform electron... design at IDS=1mA/μm compared with that in experimental 14nm-node FinFET. 14 Approved for public release, distribution is unlimited. 0 5 10 15 20

World cup soccer players tend to be born with sun and moon in adjacent zodiacal signs

PubMed Central

Verhulst, J

2000-01-01

The ecliptic elongation of the moon with respect to the sun does not show uniform distribution on the birth dates of the 704 soccer players selected for the 1998 World Cup. However, a uniform distribution is expected on astronomical grounds. The World Cup players show a very pronounced tendency (p = 0.00001) to be born on days when the sun and moon are in adjacent zodiacal signs. Key Words: soccer; World Cup; astrology; moon PMID:11131239

Electromagnetic Fields of a Uniform Sphere in a Uniform Conducting Medium with Application to Dipole Sources

DTIC Science & Technology

1991-09-01

12b. DISTRIBUTION CODE Approved for public release; distribution is unlimited. 13. ABSTRACT (Maximum 200 words) Vector spherical harmonic expansions are...electric and magnetic field vectors from E rand B - r alone. Genural expressions are given relating the scattered field expansion coefficients to the source...Prescnbed by ANSI Std. Z39-18 29W-102 NCSC TR 426-90 CONTENTS Pag o INTRODUCTION 1 BACKGROUND 1 ANGULAR MOMENTUM OPERATOR AND VECTOR SPHERICAL

Electron kinematics in a plasma focus

NASA Technical Reports Server (NTRS)

Hohl, F.; Gary, S. P.

1977-01-01

The results of numerical integrations of the three-dimensional relativistic equations of motion of electrons subject to given electric and magnetic fields are presented. Fields due to two different models are studied: (1) a circular distribution of current filaments, and (2) a uniform current distribution; both the collapse and the current reduction phases are studied in each model. Decreasing current in the uniform current model yields 100 keV electrons accelerated toward the anode and, as for earlier ion computations, provides general agreement with experimental results.

Chemotaxis Increases the Residence Time Distribution of Bacteria in Granular Media Containing Distributed Contaminant Sources

NASA Astrophysics Data System (ADS)

Adadevoh, J.; Triolo, S.; Ramsburg, C. A.; Ford, R.

2015-12-01

The use of chemotactic bacteria in bioremediation has the potential to increase access to, and biotransformation of, contaminant mass within the subsurface environment. This laboratory-scale study aimed to understand and quantify the influence of chemotaxis on residence times of pollutant-degrading bacteria within homogeneous treatment zones. Focus was placed on a continuous flow sand-packed column system in which a uniform distribution of naphthalene crystals created distributed sources of dissolved phase contaminant. A 10 mL pulse of Pseudomonas putida G7, which is chemotactic to naphthalene, and Pseudomonas putida G7 Y1, a non-chemotactic mutant strain, were simultaneously introduced into the sand-packed column at equal concentrations. Breakthrough curves obtained for the bacteria from column experiments conducted with and without naphthalene were used to quantify the effect of chemotaxis on transport parameters. In the presence of the chemoattractant, longitudinal dispersivity of PpG7 increased by a factor of 3 and percent recovery decreased from 21% to 12%. The results imply that pore-scale chemotaxis responses are evident at an interstitial fluid velocity of 1.7 m/d, which is within the range of typical groundwater flow. Within the context of bioremediation, chemotaxis may work to enhance bacterial residence times in zones of contamination thereby improving treatment.

Observational Appearance and Spectrum of Black-Hole Winds

NASA Astrophysics Data System (ADS)

Fukue, Jun; Iino, Eriko

2010-12-01

We examine the observational appearance of an optically thick, spherically symmetric, relativistic wind (a black-hole wind), focusing our attention on the emerging spectrum. In a relativistic flow, the apparent optical depth becomes small (large) in the downstream (upstream) direction due to the Lorentz-Fitzgerald contraction. As a result, the location of the apparent photosphere of the wind is remarkably modified, and there appears a relativistic limb-darkening (center-brightening) effect, where the comoving temperature distribution of the apparent photosphere is enhanced (reduced) at the center (in the limb). In addition, due to the usual Doppler boost, the observed temperature distribution is greatly changed. These relativistic effects modify the expected spectrum. When the wind speed is subrelativistic, the observed temperature distribution is almost uniform, and the spectra of the black-hole wind are blackbody-like. When the wind speed becomes relativistic, on the other hand, the observed temperature distribution, Tobs, exhibits a power-law nature of Tobs ∝ r-1, where r is the distance from the disk center, and the observed spectra Sν become a modified blackbody, which has a power-law part of Sν ∝ ν, where ν is the frequency. We briefly examine the effects of the spatial variation of the wind speed and the mass-loss rate.

THE STATISTICAL MECHANICS OF PLANET ORBITS

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

Tremaine, Scott, E-mail: tremaine@ias.edu

2015-07-10

The final “giant-impact” phase of terrestrial planet formation is believed to begin with a large number of planetary “embryos” on nearly circular, coplanar orbits. Mutual gravitational interactions gradually excite their eccentricities until their orbits cross and they collide and merge; through this process the number of surviving bodies declines until the system contains a small number of planets on well-separated, stable orbits. In this paper we explore a simple statistical model for the orbit distribution of planets formed by this process, based on the sheared-sheet approximation and the ansatz that the planets explore uniformly all of the stable region ofmore » phase space. The model provides analytic predictions for the distribution of eccentricities and semimajor axis differences, correlations between orbital elements of nearby planets, and the complete N-planet distribution function, in terms of a single parameter, the “dynamical temperature,” that is determined by the planetary masses. The predicted properties are generally consistent with N-body simulations of the giant-impact phase and with the distribution of semimajor axis differences in the Kepler catalog of extrasolar planets. A similar model may apply to the orbits of giant planets if these orbits are determined mainly by dynamical evolution after the planets have formed and the gas disk has disappeared.« less

Vertical distribution (0 1000 m) of macrozooplankton, estimated using the Underwater Video Profiler, in different hydrographic regimes along the northern portion of the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Stemmann, L.; Hosia, A.; Youngbluth, M. J.; Søiland, H.; Picheral, M.; Gorsky, G.

2008-01-01

The vertical distribution (0-1000 m depth) of macrozooplankton along the northern portion of the Mid-Atlantic Ridge (59°58N, 25°53W to 41°29N, 28°19W) was investigated during the MAR-ECO program (June and July 2004) using the Underwater Video Profiler (UVP). Twelve relatively large (>1 cm) groups were selected from the recorded images: sarcodines (with two sub-groups), crustaceans (excluding copepods), chaetognaths, ctenophores (with two sub-groups cydippids and lobates), siphonophores, medusae (with three sub-groups Aeginura grimaldii, Aglantha spp. and all other medusae), appendicularians, and thaliaceans. The numerically dominant groups over the whole area were crustaceans (26%), medusae (20%) and appendicularians (17%). The gelatinous fauna were consistently most numerous at 400-900 m. Appendicularians, ctenophores and Aeginura grimaldii occurred mostly below 300 m (maximum concentrations of 75, 58, and 30 individuals 100 m -3, respectively). Siphonophores, Aglantha spp. and the other medusae were more uniformly distributed in the water column (maxima of 42, 42 and 300 individuals 100 m -3, respectively). The macrozooplankton community below 200 m varied with the spatial distribution of the water masses, suggesting that the Sub-Polar Front restricts the mixing of macrozooplankton communities down to 1000 m depth.

High level continuity for coordinate generation with precise controls

NASA Technical Reports Server (NTRS)

Eiseman, P. R.

1982-01-01

Coordinate generation techniques with precise local controls have been derived and analyzed for continuity requirements up to both the first and second derivatives, and have been projected to higher level continuity requirements from the established pattern. The desired local control precision was obtained when a family of coordinate surfaces could be uniformly distributed without a consequent creation of flat spots on the coordinate curves transverse to the family. Relative to the uniform distribution, the family could be redistributed from an a priori distribution function or from a solution adaptive approach, both without distortion from the underlying transformation which may be independently chosen to fit a nontrivial geometry and topology.

It's a Holiday!!

ERIC Educational Resources Information Center

Ratliff, Michael I.; Mc Shane, Janet M.

2008-01-01

This article studies various holiday distributions, the most interesting one being Easter. Gauss' Easter algorithm and Microsoft Excel are used to determine that the Easter distribution can be closely approximated by the convolution of two well-known uniform distributions. (Contains 8 figures.)

Theoretical study of liquid droplet dispersion in a venturi scrubber.

PubMed

Fathikalajahi, J; Talaie, M R; Taheri, M

1995-03-01

The droplet concentration distribution in an atomizing scrubber was calculated based on droplet eddy diffusion by a three-dimensional dispersion model. This model is also capable of predicting the liquid flowing on the wall. The theoretical distribution of droplet concentration agrees well with experimental data given by Viswanathan et al. for droplet concentration distribution in a venturi-type scrubber. The results obtained by the model show a non-uniform distribution of drops over the cross section of the scrubber, as noted by the experimental data. While the maximum of droplet concentration distribution may depend on many operating parameters of the scrubber, the results of this study show that the highest uniformity of drop distribution will be reached when penetration length is approximately equal to one-fourth of the depth of the scrubber. The results of this study can be applied to evaluate the removal efficiency of a venturi scrubber.

Isolation and Connectivity in Random Geometric Graphs with Self-similar Intensity Measures

NASA Astrophysics Data System (ADS)

Dettmann, Carl P.

2018-05-01

Random geometric graphs consist of randomly distributed nodes (points), with pairs of nodes within a given mutual distance linked. In the usual model the distribution of nodes is uniform on a square, and in the limit of infinitely many nodes and shrinking linking range, the number of isolated nodes is Poisson distributed, and the probability of no isolated nodes is equal to the probability the whole graph is connected. Here we examine these properties for several self-similar node distributions, including smooth and fractal, uniform and nonuniform, and finitely ramified or otherwise. We show that nonuniformity can break the Poisson distribution property, but it strengthens the link between isolation and connectivity. It also stretches out the connectivity transition. Finite ramification is another mechanism for lack of connectivity. The same considerations apply to fractal distributions as smooth, with some technical differences in evaluation of the integrals and analytical arguments.

Fundamental Properties of the SHIELD Galaxies

NASA Astrophysics Data System (ADS)

Cannon, John; Adams, Betsey; Giovanelli, Riccardo; Haynes, Martha; Jones, Michael; McQuinn, Kristen; Rhode, Katherine; Salzer, John; Skillman, Evan

2018-05-01

The ALFALFA survey has significantly advanced our knowledge of the HI mass function (HIMF), particularly at the low mass end. From the ALFALFA survey, we have constructed a sample of all of the galaxies with HI masses less than 20 million solar masses. Observations of this 82 galaxy sample allow, for the first time, a characterization of the lowest HI mass galaxies at redshift zero. Specifically, this sample can be used to determine the low HI-mass ends of various fundamental scaling relations, including the critical baryonic Tully Fisher relation (BTFR) and the mass-metallicity (M-Z) relation. The M-Z relation and the BTFR are cosmologically important, but current samples leave the low-mass parameter spaces severely underpopulated. A full understanding of these relationships depends critically on accurate stellar masses of this complete sample of uniformly-selected galaxies. Here, we request imaging of the 70 galaxies in our sample that have not been observed with Spitzer. The proposed imaging will allow us to measure stellar masses and inclinations of the sample galaxies using a uniform observational approach. Comparison with (existing and in progress) interferometric HI imaging and with ground-based optical imaging and spectroscopy will enable a robust mass decomposition in each galaxy and accurate placements on the aforementioned scaling relationships. The observations proposed here will allow us to populate the mass continuum between mini-halos and bona fide dwarf galaxies, and to address a range of fundamental questions in galaxy formation and near-field cosmology.

From School Choice to Student Voice.

ERIC Educational Resources Information Center

Heckman, Paul E.; Montera, Viki L.

2001-01-01

Educational mass marketing approaches are like fast-food franchises; they offer homogeneous, standardized products that cannot satisfy every consumer's needs. A niche market looks inside the masses to address more individual, specialized choices missing from the menu. Variability, not uniformity, should guide development of public schooling. (MLH)

Loads and Performance Data from a Wind-Tunnel Test of Generic Model Helicopter Rotor Blades

NASA Technical Reports Server (NTRS)

Yeager, William T., Jr.; Wilbur, Matthew L.

2005-01-01

An investigation was conducted in the NASA Langley Transonic Dynamics Tunnel to acquire data for use in assessing the ability of current and future comprehensive analyses to predict helicopter rotating-system and fixed-system vibratory loads. The investigation was conducted with a generic model helicopter rotor system using blades with rectangular planform, no built-in twist, uniform radial distribution of mass and stiffnesses, and a NACA 0012 airfoil section. Rotor performance data, as well as mean and vibratory components of blade bending and torsion moments, fixed-system forces and moments, and pitch link loads were obtained at advance ratios up to 0.35 for various combinations of rotor shaft angle-of-attack and collective pitch. The data are presented without analysis.

Particle and gas emissions from a simulated coal-burning household fire pit.

PubMed

Tian, Linwei; Lucas, Donald; Fischer, Susan L; Lee, S C; Hammond, S Katharine; Koshland, Catherine P

2008-04-01

An open fire was assembled with firebricks to simulate the household fire pit used in rural China, and 15 different coals from this area were burned to measure the gaseous and particulate emissions. Particle size distribution was studied with a microorifice uniform-deposit impactor (MOUDI). Over 90% of the particulate mass was attributed to sub-micrometer particles. The carbon balance method was used to calculate the emission factors. Emission factors for four pollutants (particulate matter, CO2, total hydrocarbons, and NOx) were 2-4 times higherfor bituminous coals than for anthracites. In past inventories of carbonaceous emissions used for climate modeling, these two types of coal were not treated separately. The dramatic emission factor difference between the two types of coal warrants attention in the future development of emission inventories.

Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

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

Aab, A.; Abreu, P.; Andringa, S.

2017-04-01

We present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed for energies above 5 ⋅ 10{sup 18} eV, i.e. the region of the all-particle spectrum above the so-called 'ankle' feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated through a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies, hard spectra and heavy chemical composition. We also show that uncertainties aboutmore » physical quantities relevant to UHECR propagation and shower development have a non-negligible impact on the fit results.« less

Platinum-gold nanoclusters as catalyst for direct methanol fuel cells.

PubMed

Giorgi, L; Giorgi, R; Gagliardi, S; Serra, E; Alvisi, M; Signore, M A; Piscopiello, E

2011-10-01

Nanosized platinum-gold alloys clusters have been deposited on gas diffusion electrode by sputter deposition. The deposits were characterized by FE-SEM, TEM and XPS in order to verify the formation of alloy nanoparticles and to study the influence of deposition technique on the nanomorphology. The deposition by sputtering process allowed a uniform distribution of metal particles on porous surface of carbon supports. Typical island growth mode was observed with the formation of a dispersed metal nanoclusters (mean size about 5 nm). Cyclic voltammetry was used to determine the electrochemical active surface and the electrocatalytic performance of the PtAu electrocatalysts for methanol oxidation reaction. The data were re-calculated in the form of mass specific activity (MSA). The sputter-catalyzed electrodes showed higher performance and stability compared to commercial catalysts.

Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

NASA Astrophysics Data System (ADS)

Aab, A.; Abreu, P.; Aglietta, M.; Samarai, I. Al; Albuquerque, I. F. M.; Allekotte, I.; Almela, A.; Alvarez Castillo, J.; Alvarez-Muñiz, J.; Anastasi, G. A.; Anchordoqui, L.; Andrada, B.; Andringa, S.; Aramo, C.; Arqueros, F.; Arsene, N.; Asorey, H.; Assis, P.; Aublin, J.; Avila, G.; Badescu, A. M.; Balaceanu, A.; Barreira Luz, R. J.; Beatty, J. J.; Becker, K. H.; Bellido, J. A.; Berat, C.; Bertaina, M. E.; Bertou, X.; Biermann, P. L.; Billoir, P.; Biteau, J.; Blaess, S. G.; Blanco, A.; Blazek, J.; Bleve, C.; Boháčová, M.; Boncioli, D.; Bonifazi, C.; Borodai, N.; Botti, A. M.; Brack, J.; Brancus, I.; Bretz, T.; Bridgeman, A.; Briechle, F. L.; Buchholz, P.; Bueno, A.; Buitink, S.; Buscemi, M.; Caballero-Mora, K. S.; Caccianiga, L.; Cancio, A.; Canfora, F.; Caramete, L.; Caruso, R.; Castellina, A.; Cataldi, G.; Cazon, L.; Chavez, A. G.; Chinellato, J. A.; Chudoba, J.; Clay, R. W.; Colalillo, R.; Coleman, A.; Collica, L.; Coluccia, M. R.; Conceição, R.; Contreras, F.; Cooper, M. J.; Coutu, S.; Covault, C. E.; Cronin, J.; D'Amico, S.; Daniel, B.; Dasso, S.; Daumiller, K.; Dawson, B. R.; de Almeida, R. M.; de Jong, S. J.; De Mauro, G.; de Mello Neto, J. R. T.; De Mitri, I.; de Oliveira, J.; de Souza, V.; Debatin, J.; Deligny, O.; Di Giulio, C.; di Matteo, A.; Díaz Castro, M. L.; Diogo, F.; Dobrigkeit, C.; D'Olivo, J. C.; Dorosti, Q.; dos Anjos, R. C.; Dova, M. T.; Dundovic, A.; Ebr, J.; Engel, R.; Erdmann, M.; Erfani, M.; Escobar, C. O.; Espadanal, J.; Etchegoyen, A.; Falcke, H.; Farrar, G.; Fauth, A. C.; Fazzini, N.; Fick, B.; Figueira, J. M.; Filipčič, A.; Fratu, O.; Freire, M. M.; Fujii, T.; Fuster, A.; Gaior, R.; García, B.; Garcia-Pinto, D.; Gaté, F.; Gemmeke, H.; Gherghel-Lascu, A.; Ghia, P. L.; Giaccari, U.; Giammarchi, M.; Giller, M.; Głas, D.; Glaser, C.; Golup, G.; Gómez Berisso, M.; Gómez Vitale, P. F.; González, N.; Gorgi, A.; Gorham, P.; Grillo, A. F.; Grubb, T. D.; Guarino, F.; Guedes, G. P.; Hampel, M. R.; Hansen, P.; Harari, D.; Harrison, T. A.; Harton, J. L.; Haungs, A.; Hebbeker, T.; Heck, D.; Heimann, P.; Herve, A. E.; Hill, G. C.; Hojvat, C.; Holt, E.; Homola, P.; Hörandel, J. R.; Horvath, P.; Hrabovský, M.; Huege, T.; Hulsman, J.; Insolia, A.; Isar, P. G.; Jandt, I.; Jansen, S.; Johnsen, J. A.; Josebachuili, M.; Kääpä, A.; Kambeitz, O.; Kampert, K. H.; Katkov, I.; Keilhauer, B.; Kemp, E.; Kemp, J.; Kieckhafer, R. M.; Klages, H. O.; Kleifges, M.; Kleinfeller, J.; Krause, R.; Krohm, N.; Kuempel, D.; Kukec Mezek, G.; Kunka, N.; Kuotb Awad, A.; LaHurd, D.; Lauscher, M.; Legumina, R.; Leigui de Oliveira, M. A.; Letessier-Selvon, A.; Lhenry-Yvon, I.; Link, K.; Lopes, L.; López, R.; López Casado, A.; Luce, Q.; Lucero, A.; Malacari, M.; Mallamaci, M.; Mandat, D.; Mantsch, P.; Mariazzi, A. G.; Mariş, I. C.; Marsella, G.; Martello, D.; Martinez, H.; Martínez Bravo, O.; Masías Meza, J. J.; Mathes, H. J.; Mathys, S.; Matthews, J.; Matthews, J. A. J.; Matthiae, G.; Mayotte, E.; Mazur, P. O.; Medina, C.; Medina-Tanco, G.; Melo, D.; Menshikov, A.; Micheletti, M. I.; Middendorf, L.; Minaya, I. A.; Miramonti, L.; Mitrica, B.; Mockler, D.; Mollerach, S.; Montanet, F.; Morello, C.; Mostafá, M.; Müller, A. L.; Müller, G.; Muller, M. A.; Müller, S.; Mussa, R.; Naranjo, I.; Nellen, L.; Nguyen, P. H.; Niculescu-Oglinzanu, M.; Niechciol, M.; Niemietz, L.; Niggemann, T.; Nitz, D.; Nosek, D.; Novotny, V.; Nožka, H.; Núñez, L. A.; Ochilo, L.; Oikonomou, F.; Olinto, A.; Palatka, M.; Pallotta, J.; Papenbreer, P.; Parente, G.; Parra, A.; Paul, T.; Pech, M.; Pedreira, F.; Pȩkala, J.; Pelayo, R.; Peña-Rodriguez, J.; Pereira, L. A. S.; Perlín, M.; Perrone, L.; Peters, C.; Petrera, S.; Phuntsok, J.; Piegaia, R.; Pierog, T.; Pieroni, P.; Pimenta, M.; Pirronello, V.; Platino, M.; Plum, M.; Porowski, C.; Prado, R. R.; Privitera, P.; Prouza, M.; Quel, E. J.; Querchfeld, S.; Quinn, S.; Ramos-Pollan, R.; Rautenberg, J.; Ravignani, D.; Revenu, B.; Ridky, J.; Risse, M.; Ristori, P.; Rizi, V.; Rodrigues de Carvalho, W.; Rodriguez Fernandez, G.; Rodriguez Rojo, J.; Rogozin, D.; Roncoroni, M. J.; Roth, M.; Roulet, E.; Rovero, A. C.; Ruehl, P.; Saffi, S. J.; Saftoiu, A.; Salamida, F.; Salazar, H.; Saleh, A.; Salesa Greus, F.; Salina, G.; Sánchez, F.; Sanchez-Lucas, P.; Santos, E. M.; Santos, E.; Sarazin, F.; Sarmento, R.; Sarmiento, C. A.; Sato, R.; Schauer, M.; Scherini, V.; Schieler, H.; Schimp, M.; Schmidt, D.; Scholten, O.; Schovánek, P.; Schröoder, F. G.; Schulz, A.; Schulz, J.; Schumacher, J.; Sciutto, S. J.; Segreto, A.; Settimo, M.; Shadkam, A.; Shellard, R. C.; Sigl, G.; Silli, G.; Sima, O.; Śmiałkowski, A.; Šmída, R.; Snow, G. R.; Sommers, P.; Sonntag, S.; Sorokin, J.; Squartini, R.; Stanca, D.; Stanič, S.; Stasielak, J.; Stassi, P.; Strafella, F.; Suarez, F.; Suarez Durán, M.; Sudholz, T.; Suomijärvi, T.; Supanitsky, A. D.; Swain, J.; Szadkowski, Z.; Taboada, A.; Taborda, O. A.; Tapia, A.; Theodoro, V. M.; Timmermans, C.; Todero Peixoto, C. J.; Tomankova, L.; Tomé, B.; Torralba Elipe, G.; Travnicek, P.; Trini, M.; Ulrich, R.; Unger, M.; Urban, M.; Valdés Galicia, J. F.; Valiño, I.; Valore, L.; van Aar, G.; van Bodegom, P.; van den Berg, A. M.; van Vliet, A.; Varela, E.; Vargas Cárdenas, B.; Varner, G.; Vázquez, J. R.; Vázquez, R. A.; Veberič, D.; Vergara Quispe, I. D.; Verzi, V.; Vicha, J.; Villaseñor, L.; Vorobiov, S.; Wahlberg, H.; Wainberg, O.; Walz, D.; Watson, A. A.; Weber, M.; Weindl, A.; Wiencke, L.; Wilczyński, H.; Winchen, T.; Wirtz, M.; Wittkowski, D.; Wundheiler, B.; Yang, L.; Yelos, D.; Yushkov, A.; Zas, E.; Zavrtanik, D.; Zavrtanik, M.; Zepeda, A.; Zimmermann, B.; Ziolkowski, M.; Zong, Z.; Zong, Z.

2017-04-01

We present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed for energies above 5 ṡ 1018 eV, i.e. the region of the all-particle spectrum above the so-called "ankle" feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated through a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies, hard spectra and heavy chemical composition. We also show that uncertainties about physical quantities relevant to UHECR propagation and shower development have a non-negligible impact on the fit results.

Fundamental aspects in quantitative ultrasonic determination of fracture toughness: The scattering of a single ellipsoidal inhomogeneity

NASA Technical Reports Server (NTRS)

Fu, L. S. W.

1982-01-01

The scattering of a single ellipsoidal inhomogeneity is studied via an eigenstrain approach. The displacement field is given in terms of volume integrals that involve eigenstrains that are related to mismatch in mass density and that in elastic moduli. The governing equations for these unknown eigenstrains are derived. Agreement with other approaches for the scattering problem is shown. The formulation is general and both the inhomogeneity and the host medium can be anisotrophic. The axisymmetric scattering of an ellipsoidal inhomogeneity in a linear elastic isotropic medium is given as an example. The angular and frequency dependence of the scattered displacement field, the differential and total cross sections are formally given in series expansions for the case of uniformly distributed eigenstrains.

A recirculation aerosol wind tunnel for evaluating aerosol samplers and measuring particle penetration through protective clothing materials.

PubMed

Jaques, Peter A; Hsiao, Ta-Chih; Gao, Pengfei

2011-08-01

A recirculation aerosol wind tunnel was designed to maintain a uniform airflow and stable aerosol size distribution for evaluating aerosol sampler performance and determining particle penetration through protective clothing materials. The oval-shaped wind tunnel was designed to be small enough to fit onto a lab bench, have optimized dimensions for uniformity in wind speed and particle size distributions, sufficient mixing for even distribution of particles, and minimum particle losses. Performance evaluation demonstrates a relatively high level of spatial uniformity, with a coefficient of variation of 1.5-6.2% for wind velocities between 0.4 and 2.8 m s(-1) and, in this range, 0.8-8.5% for particles between 50 and 450 nm. Aerosol concentration stabilized within the first 5-20 min with, approximately, a count median diameter of 135 nm and geometric standard deviation of 2.20. Negligible agglomerate growth and particle loss are suggested. The recirculation design appears to result in unique features as needed for our research.

A method for improving the light intensity distribution in dental light-curing units.

PubMed

Arikawa, Hiroyuki; Takahashi, Hideo; Minesaki, Yoshito; Muraguchi, Kouichi; Matsuyama, Takashi; Kanie, Takahito; Ban, Seiji

2011-01-01

A method for improving the uniformity of the radiation light from dental light-curing units (LCUs), and the effect on the polymerization of light-activated composite resin are investigated. Quartz-tungsten halogen, plasma-arc, and light-emitting diode LCUs were used, and additional optical elements such as a mixing tube and diffusing screen were employed to reduce the inhomogeneity of the radiation light. The distribution of the light intensity from the light guide tip was measured across the guide tip, as well as the distribution of the surface hardness of the light-activated resin emitted with the LCUs. Although the additional optical elements caused 13.2-25.9% attenuation of the light intensity, the uniformity of the light intensity of the LCUs was significantly improved in the modified LCUs, and the uniformity of the surface hardness of the resin was also improved. Our results indicate that the addition of optical elements to the LCU may be a simple and effective method for reducing inhomogeneity in radiation light from the LCUs.

Synthesis of uniformly distributed single- and double-sided zinc oxide (ZnO) nanocombs

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

Altintas Yildirim, Ozlem; Liu, Yuzi; Petford-Long, Amanda K.

Uniformly distributed single- and double-sided zinc oxide (ZnO) nanocomb structures have been prepared by a vapor-liquid-solid technique from a mixture of ZnO nanoparticles and graphene nanoplatelets. The ZnO seed nanoparticles were synthesized via a simple precipitation method. The structure of the ZnO nanocombs could easily be controlled by tuning the carrier-gas flow rate during growth. Higher flow rate resulted in the formation of uniformly-distributed single-sided comb structures with nanonail-shaped teeth, as a result of the self-catalysis effect of the catalytically active Zn-terminated polar (0001) surface. Lower gas flow rate was favorable for production of double-sided comb structures with the twomore » sets of teeth at an angle of similar to 110 degrees to each other along the comb ribbon, which was attributed to the formation of a bicrystal nanocomb ribbon. Lastly, the formation of such a double-sided structure with nanonail-shaped teeth has not previously been reported.« less

Synthesis of uniformly distributed single- and double-sided zinc oxide (ZnO) nanocombs

DOE PAGES

Altintas Yildirim, Ozlem; Liu, Yuzi; Petford-Long, Amanda K.

2015-08-21

Uniformly distributed single- and double-sided zinc oxide (ZnO) nanocomb structures have been prepared by a vapor-liquid-solid technique from a mixture of ZnO nanoparticles and graphene nanoplatelets. The ZnO seed nanoparticles were synthesized via a simple precipitation method. The structure of the ZnO nanocombs could easily be controlled by tuning the carrier-gas flow rate during growth. Higher flow rate resulted in the formation of uniformly-distributed single-sided comb structures with nanonail-shaped teeth, as a result of the self-catalysis effect of the catalytically active Zn-terminated polar (0001) surface. Lower gas flow rate was favorable for production of double-sided comb structures with the twomore » sets of teeth at an angle of similar to 110 degrees to each other along the comb ribbon, which was attributed to the formation of a bicrystal nanocomb ribbon. Lastly, the formation of such a double-sided structure with nanonail-shaped teeth has not previously been reported.« less

Redundancy and Reduction: Speakers Manage Syntactic Information Density

ERIC Educational Resources Information Center

Jaeger, T. Florian

2010-01-01

A principle of efficient language production based on information theoretic considerations is proposed: Uniform Information Density predicts that language production is affected by a preference to distribute information uniformly across the linguistic signal. This prediction is tested against data from syntactic reduction. A single multilevel…

Transverse Motion of a Particle with an Oscillating Charge and Variable Mass in a Magnetic Field

NASA Astrophysics Data System (ADS)

Alisultanov, Z. Z.; Ragimkhanov, G. B.

2018-03-01

The problem of motion of a particle with an oscillating electric charge and variable mass in an uniform magnetic field has been solved. Three laws of mass variation have been considered: linear growth, oscillations, and stepwise growth. Analytical expressions for the particle velocity at different time dependences of the particle mass are obtained. It is established that simultaneous consideration of changes in the mass and charge leads to a significant change in the particle trajectory.

Modular Exhaust Design and Manufacturing Techniques for Low Cost Mid Volume Rapid Buidl to Order Systems

DTIC Science & Technology

2014-08-06

the pressure field is uniform across them, but which allow mass flow to be diverted. Series elements have a constant mass flow across the ports...they can be used to calculate the pressure and mass flow after the element from the pressure and mass flow prior to the element, as shown in...the matrix product of each transfer matrix in turn. The final matrix gives no information about the pressures and mass flows within the element

Improved high power/high frequency inductor

NASA Technical Reports Server (NTRS)

Mclyman, W. T. (Inventor)

1990-01-01

A toroidal core is mounted on an alignment disc having uniformly distributed circumferential notches or holes therein. Wire is then wound about the toroidal core in a uniform pattern defined by the notches or holes. Prior to winding, the wire may be placed within shrink tubing. The shrink tubing is then wound about the alignment disc and core and then heat-shrunk to positively retain the wire in the uniform position on the toroidal core.

Direct computation of thermodynamic properties of chemically reacting air with consideration to CFD

NASA Astrophysics Data System (ADS)

Iannelli, Joe

2003-10-01

This paper details a two-equation procedure to calculate exactly mass and mole fractions, pressure, temperature, specific heats, speed of sound and the thermodynamic and jacobian partial derivatives of pressure and temperature for a five-species chemically reacting equilibrium air. The procedure generates these thermodynamic properties using as independent variables either pressure and temperature or density and internal energy, for CFD applications. An original element in this procedure consists in the exact physically meaningful solution of the mass-fraction and mass-action equations. Air-equivalent molecular masses for oxygen and nitrogen are then developed to account, within a mixture of only oxygen and nitrogen, for the presence of carbon dioxide, argon and the other noble gases within atmospheric air. The mathematical formulation also introduces a versatile system non-dimensionalization that makes the procedure uniformly applicable to flows ranging from shock-tube flows with zero initial velocity to aerothermodynamic flows with supersonic/hypersonic free-stream Mach numbers. Over a temperature range of more than 10000 K and pressure and density ranges corresponding to an increase in altitude in standard atmosphere of 30000 m above sea level, the predicted distributions of mole fractions, constant-volume specific heat, and speed of sound for the model five species agree with independently published results, and all the calculated thermodynamic properties, including their partial derivatives, remain continuous, smooth, and physically meaningful.

Quantification of black carbon mixing state from traffic: Implications for aerosol optical properties

DOE PAGES

Willis, Megan D.; Healy, Robert M.; Riemer, Nicole; ...

2016-04-14

The climatic impacts of black carbon (BC) aerosol, an important absorber of solar radiation in the atmosphere, remain poorly constrained and are intimately related to its particle-scale physical and chemical properties. Using particle-resolved modelling informed by quantitative measurements from a soot-particle aerosol mass spectrometer, we confirm that the mixing state (the distribution of co-emitted aerosol amongst fresh BC-containing particles) at the time of emission significantly affects BC-aerosol optical properties even after a day of atmospheric processing. Both single particle and ensemble aerosol mass spectrometry observations indicate that BC near the point of emission co-exists with hydrocarbon-like organic aerosol (HOA) inmore » two distinct particle types: HOA-rich and BC-rich particles. The average mass fraction of black carbon in HOA-rich and BC-rich particle classes was < 0.1 and 0.8, respectively. Notably, approximately 90 % of BC mass resides in BC-rich particles. This new measurement capability provides quantitative insight into the physical and chemical nature of BC-containing particles and is used to drive a particle-resolved aerosol box model. Lastly, significant differences in calculated single scattering albedo (an increase of 0.1) arise from accurate treatment of initial particle mixing state as compared to the assumption of uniform aerosol composition at the point of BC injection into the atmosphere.« less

Improved Zirconia Oxygen-Separation Cell

NASA Technical Reports Server (NTRS)

Walsh, John V.; Zwissler, James G.

1988-01-01

Cell structure distributes feed gas more evenly for more efficent oxygen production. Multilayer cell structure containing passages, channels, tubes, and pores help distribute pressure evenly over zirconia electrolytic membrane. Resulting more uniform pressure distribution expected to improve efficiency of oxygen production.

On a neutral particle with permanent magnetic dipole moment in a magnetic medium

NASA Astrophysics Data System (ADS)

Bakke, K.; Salvador, C.

2018-03-01

We investigate quantum effects that stem from the interaction of a permanent magnetic dipole moment of a neutral particle with an electric field in a magnetic medium. We consider a long non-conductor cylinder that possesses a uniform distribution of electric charges and a non-uniform magnetization. We discuss the possibility of achieving this non-uniform magnetization from the experimental point of view. Besides, due to this non-uniform magnetization, the permanent magnetic dipole moment of the neutral particle also interacts with a non-uniform magnetic field. This interaction gives rise to a linear scalar potential. Then, we show that bound states solutions to the Schrödinger-Pauli equation can be achieved.

Adapting radiotherapy to hypoxic tumours

NASA Astrophysics Data System (ADS)

Malinen, Eirik; Søvik, Åste; Hristov, Dimitre; Bruland, Øyvind S.; Rune Olsen, Dag

2006-10-01

In the current work, the concepts of biologically adapted radiotherapy of hypoxic tumours in a framework encompassing functional tumour imaging, tumour control predictions, inverse treatment planning and intensity modulated radiotherapy (IMRT) were presented. Dynamic contrast enhanced magnetic resonance imaging (DCEMRI) of a spontaneous sarcoma in the nasal region of a dog was employed. The tracer concentration in the tumour was assumed related to the oxygen tension and compared to Eppendorf histograph measurements. Based on the pO2-related images derived from the MR analysis, the tumour was divided into four compartments by a segmentation procedure. DICOM structure sets for IMRT planning could be derived thereof. In order to display the possible advantages of non-uniform tumour doses, dose redistribution among the four tumour compartments was introduced. The dose redistribution was constrained by keeping the average dose to the tumour equal to a conventional target dose. The compartmental doses yielding optimum tumour control probability (TCP) were used as input in an inverse planning system, where the planning basis was the pO2-related tumour images from the MR analysis. Uniform (conventional) and non-uniform IMRT plans were scored both physically and biologically. The consequences of random and systematic errors in the compartmental images were evaluated. The normalized frequency distributions of the tracer concentration and the pO2 Eppendorf measurements were not significantly different. 28% of the tumour had, according to the MR analysis, pO2 values of less than 5 mm Hg. The optimum TCP following a non-uniform dose prescription was about four times higher than that following a uniform dose prescription. The non-uniform IMRT dose distribution resulting from the inverse planning gave a three times higher TCP than that of the uniform distribution. The TCP and the dose-based plan quality depended on IMRT parameters defined in the inverse planning procedure (fields and step-and-shoot intensity levels). Simulated random and systematic errors in the pO2-related images reduced the TCP for the non-uniform dose prescription. In conclusion, improved tumour control of hypoxic tumours by dose redistribution may be expected following hypoxia imaging, tumour control predictions, inverse treatment planning and IMRT.

Luminescence imaging of water during uniform-field irradiation by spot scanning proton beams

NASA Astrophysics Data System (ADS)

Komori, Masataka; Sekihara, Eri; Yabe, Takuya; Horita, Ryo; Toshito, Toshiyuki; Yamamoto, Seiichi

2018-06-01

Luminescence was found during pencil-beam proton irradiation to water phantom and range could be estimated from the luminescence images. However, it is not yet clear whether the luminescence imaging is applied to the uniform fields made of spot-scanning proton-beam irradiations. For this purpose, imaging was conducted for the uniform fields having spread out Bragg peak (SOBP) made by spot scanning proton beams. We designed six types of the uniform fields with different ranges, SOBP widths and irradiation fields. One of the designed fields was irradiated to water phantom and a cooled charge coupled device camera was used to measure the luminescence image during irradiations. We estimated the ranges, field widths, and luminescence intensities from the luminescence images and compared those with the dose distribution calculated by a treatment planning system. For all types of uniform fields, we could obtain clear images of the luminescence showing the SOBPs. The ranges and field widths evaluated from the luminescence were consistent with those of the dose distribution calculated by a treatment planning system within the differences of  ‑4 mm and  ‑11 mm, respectively. Luminescence intensities were almost proportional to the SOBP widths perpendicular to the beam direction. The luminescence imaging could be applied to uniform fields made of spot scanning proton beam irradiations. Ranges and widths of the uniform fields with SOBP could be estimated from the images. The luminescence imaging is promising for the range and field width estimations in proton therapy.

Streamline similarity method for flow distributions and shock losses at the impeller inlet of the centrifugal pump

NASA Astrophysics Data System (ADS)

Zhang, Zh.

2018-02-01

An analytical method is presented, which enables the non-uniform velocity and pressure distributions at the impeller inlet of a pump to be accurately computed. The analyses are based on the potential flow theory and the geometrical similarity of the streamline distribution along the leading edge of the impeller blades. The method is thus called streamline similarity method (SSM). The obtained geometrical form of the flow distribution is then simply described by the geometrical variable G( s) and the first structural constant G I . As clearly demonstrated and also validated by experiments, both the flow velocity and the pressure distributions at the impeller inlet are usually highly non-uniform. This knowledge is indispensible for impeller blade designs to fulfill the shockless inlet flow condition. By introducing the second structural constant G II , the paper also presents the simple and accurate computation of the shock loss, which occurs at the impeller inlet. The introduction of two structural constants contributes immensely to the enhancement of the computational accuracies. As further indicated, all computations presented in this paper can also be well applied to the non-uniform exit flow out of an impeller of the Francis turbine for accurately computing the related mean values.

Effect of Formulation and Process Parameters on Chitosan Microparticles Prepared by an Emulsion Crosslinking Technique.

PubMed

Rodriguez, Lidia B; Avalos, Abraham; Chiaia, Nicholas; Nadarajah, Arunan

2017-05-01

There are many studies about the synthesis of chitosan microparticles; however, most of them have very low production rate, have wide size distribution, are difficult to reproduce, and use harsh crosslinking agents. Uniform microparticles are necessary to obtain repeatable drug release behavior. The main focus of this investigation was to study the effect of the process and formulation parameters during the preparation of chitosan microparticles in order to produce particles with narrow size distribution. The technique evaluated during this study was emulsion crosslinking technique. Chitosan is a biocompatible and biodegradable material but lacks good mechanical properties; for that reason, chitosan was ionically crosslinked with sodium tripolyphosphate (TPP) at three different ratios (32, 64, and 100%). The model drug used was acetylsalicylic acid (ASA). During the preparation of the microparticles, chitosan was first mixed with ASA and then dispersed in oil containing an emulsifier. The evaporation of the solvents hardened the hydrophilic droplets forming microparticles with spherical shape. The process and formulation parameters were varied, and the microparticles were characterized by their morphology, particle size, drug loading efficiency, and drug release behavior. The higher drug loading efficiency was achieved by using 32% mass ratio of TPP to chitosan. The average microparticle size was 18.7 μm. The optimum formulation conditions to prepare uniform spherical microparticles were determined and represented by a region in a triangular phase diagram. The drug release analyses were evaluated in phosphate buffer solution at pH 7.4 and were mainly completed at 24 h.

ISS-Crystal Growth of Photorefractive Materials (BSO): Critical Design Issues for Optimized Data Extraction from Space Experiments

NASA Technical Reports Server (NTRS)

Hyers, Robert W.; Motakef, S.; Witt, A. F.; Wuensch, B.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Realization of the full potential of photorefractive materials in device technology is seriously impeded by our inability to achieve controlled formation of critical defects during single crystal growth and by difficulties in meeting the required degree of compositional uniformity on a micro-scale over macroscopic dimensions. The exact nature and origin of the critical defects which control photorefractivity could not as yet be identified because of gravitational interference. There exists, however, strong evidence that the density of defect formation and their spatial distribution are adversely affected by gravitational interference which precludes the establishment of quantifiable and controllable heat and mass transfer conditions during crystal growth. The current, NASA sponsored research at MIT is directed at establishing a basis for the development of a comprehensive approach to the optimization of property control during melt growth of photorefractive materials, making use of the m-g environment, provided in the International Space Station. The objectives to be pursued in m-g research on photorefractive BSO (Bi12SiO20) are: (a) identification of the x-level(s) responsible for photorefractivity in undoped BSO; (b) development of approaches leading to the control of x-level formation at uniform spatial distribution; (c) development of doping and processing procedures for optimization of the critical, application specific parameters, spectral response, sensitivity, response time and matrix stability. The presentation will focus on: the rationale for the justification of the space experiment, ground-based development efforts, design considerations for the space experiments, strategic plan of the space experiments, and approaches to the quantitative analysis of the space experiments.

Temperature distributions in tissues during local hyperthermia by stationary or steered beams of unfocused or focused ultrasound.

PubMed Central

Lele, P. P.; Parker, K. J.

1982-01-01

Temperature distributions resulting from insonation with stationary or steered beams of unfocused or focused ultrasound were measured in tissue-equivalent phantom, beef muscle in vitro, dog muscle mass, and transplanted murine tumours in vivo. Arrays of 4 to 6 thermocouples stepped through the volume of interest under computer control were used to measure the steady-state temperatures at 600 to 800 locations in both in vitro and in vivo experiments. The results were confirmed in spontaneous tumours in dog patients using fewer multi-thermocouple probes. Plane wave ultrasound was found to result in spatially non-uniform hyperthermia even in superficial tumours. The region of maximum temperature rise was small in extent and was situated at a depth which varied in the different models from 0.5 to 1.0 cm. Neither its location nor its extent could be varied by spatial manipulations of the transducer or by changing the insonation parameters except the ultrasonic frequency. A second region of hyperthermia was produced at depth by reflective heating if an ultrasonically reflective target, such as bone or air-containing tissue, was located below the target tissue. On the other hand, using available steered, focused ultrasound techniques, tumours (whether situated superficially or at depth) could be heated to a uniform, controllable temperature without undesirable temperature elevation in surrounding normal tissues. The use of steered, focused ultrasound permits deposition of energy to be tailored to the specific needs of each individual tumour. The small size of the focal region enables heating of tumours even when located near ultrasound reflecting targets. PMID:6950746

A dilute Cu(Ni) alloy for synthesis of large-area Bernal stacked bilayer graphene using atmospheric pressure chemical vapour deposition

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

Madito, M. J.; Bello, A.; Dangbegnon, J. K.

2016-01-07

A bilayer graphene film obtained on copper (Cu) foil is known to have a significant fraction of non-Bernal (AB) stacking and on copper/nickel (Cu/Ni) thin films is known to grow over a large-area with AB stacking. In this study, annealed Cu foils for graphene growth were doped with small concentrations of Ni to obtain dilute Cu(Ni) alloys in which the hydrocarbon decomposition rate of Cu will be enhanced by Ni during synthesis of large-area AB-stacked bilayer graphene using atmospheric pressure chemical vapour deposition. The Ni doped concentration and the Ni homogeneous distribution in Cu foil were confirmed with inductively coupledmore » plasma optical emission spectrometry and proton-induced X-ray emission. An electron backscatter diffraction map showed that Cu foils have a single (001) surface orientation which leads to a uniform growth rate on Cu surface in early stages of graphene growth and also leads to a uniform Ni surface concentration distribution through segregation kinetics. The increase in Ni surface concentration in foils was investigated with time-of-flight secondary ion mass spectrometry. The quality of graphene, the number of graphene layers, and the layers stacking order in synthesized bilayer graphene films were confirmed by Raman and electron diffraction measurements. A four point probe station was used to measure the sheet resistance of graphene films. As compared to Cu foil, the prepared dilute Cu(Ni) alloy demonstrated the good capability of growing large-area AB-stacked bilayer graphene film by increasing Ni content in Cu surface layer.« less

A dilute Cu(Ni) alloy for synthesis of large-area Bernal stacked bilayer graphene using atmospheric pressure chemical vapour deposition

NASA Astrophysics Data System (ADS)

Madito, M. J.; Bello, A.; Dangbegnon, J. K.; Oliphant, C. J.; Jordaan, W. A.; Momodu, D. Y.; Masikhwa, T. M.; Barzegar, F.; Fabiane, M.; Manyala, N.

2016-01-01

A bilayer graphene film obtained on copper (Cu) foil is known to have a significant fraction of non-Bernal (AB) stacking and on copper/nickel (Cu/Ni) thin films is known to grow over a large-area with AB stacking. In this study, annealed Cu foils for graphene growth were doped with small concentrations of Ni to obtain dilute Cu(Ni) alloys in which the hydrocarbon decomposition rate of Cu will be enhanced by Ni during synthesis of large-area AB-stacked bilayer graphene using atmospheric pressure chemical vapour deposition. The Ni doped concentration and the Ni homogeneous distribution in Cu foil were confirmed with inductively coupled plasma optical emission spectrometry and proton-induced X-ray emission. An electron backscatter diffraction map showed that Cu foils have a single (001) surface orientation which leads to a uniform growth rate on Cu surface in early stages of graphene growth and also leads to a uniform Ni surface concentration distribution through segregation kinetics. The increase in Ni surface concentration in foils was investigated with time-of-flight secondary ion mass spectrometry. The quality of graphene, the number of graphene layers, and the layers stacking order in synthesized bilayer graphene films were confirmed by Raman and electron diffraction measurements. A four point probe station was used to measure the sheet resistance of graphene films. As compared to Cu foil, the prepared dilute Cu(Ni) alloy demonstrated the good capability of growing large-area AB-stacked bilayer graphene film by increasing Ni content in Cu surface layer.

Water Mass Classification on a Highly Variable Arctic Shelf Region: Origin of Laptev Sea Water Masses and Implications for the Nutrient Budget

NASA Astrophysics Data System (ADS)

Bauch, D.; Cherniavskaia, E.

2018-03-01

Large gradients and inter annual variations on the Laptev Sea shelf prevent the use of uniform property ranges for a classification of major water masses. The central Laptev Sea is dominated by predominantly marine waters, locally formed polynya waters and riverine summer surface waters. Marine waters enter the central Laptev Sea from the northwestern Laptev Sea shelf and originate from the Kara Sea or the Arctic Ocean halocline. Local polynya waters are formed in the Laptev Sea coastal polynyas. Riverine summer surface waters are formed from Lena river discharge and local melt. We use a principal component analysis (PCA) in order to assess the distribution and importance of water masses within the Laptev Sea. This mathematical method is applied to hydro-chemical summer data sets from the Laptev Sea from five years and allows to define water types based on objective and statistically significant criteria. We argue that the PCA-derived water types are consistent with the Laptev Sea hydrography and indeed represent the major water masses on the central Laptev Sea shelf. Budgets estimated for the thus defined major Laptev Sea water masses indicate that freshwater inflow from the western Laptev Sea is about half or in the same order of magnitude as freshwater stored in locally formed polynya waters. Imported water dominates the nutrient budget in the central Laptev Sea; and only in years with enhanced local polynya activity is the nutrient budget of the locally formed water in the same order as imported nutrients.

Preliminary Results from the STARDUST Encounter with Wild 2 Comet obtained by the Dust Flux Monitor Instrument

NASA Astrophysics Data System (ADS)

Economou, T. E.; Tuzzolino, A. J.; Green, S. F.

On January 2nd, 2004, the Stardust spacecraft successfully encountered the Wild 2 comet. The Dust Flux Monitor Instrument (DFMI) provided quantitative measurements of dust particle fluxes and particle mass distribution throughout the entire flythrough. The DFMI consists of two different dust detector systems --- a polyvinylidene fluoride (PVDF) dust sensor unit (SU), which measures particles in the 10-11 to 10-4 mass, and a dual acoustic sensor system (DASS), which utilizes two piezoelectric accelerometers mounted on the first two layers of the spacecraft Whipple dust shield to measure the flux ofparticles with mass larger than 10-4 g. The DFMI on the stardust mission was designed, built and tested at the University of Chicago. The Open University provided the calibration and will perform the analysis of the data from the acoustic sensors. The DFMI instrument was turned on 15 minutes before the estimated closest approach. It started to detect the first dust particles just a few minutes before the closest approach with both types of the sensors in the instrument. As the S/C was departing the comet several more dust particle streams were encountered some 2-12 minutes after the closest approach. The time distribution of dust particles detected by DFMI is not uniform and they seem to come in closely spaced swarms of particles separated by many seconds with no events. The source of these particles is believed to be several of the jet streams that were observed in many of the images obtained by the navigation camera on the STARDUST spacecraft. Data flux rates and dust particle mass distribution are currently being evaluated and will be presented at the meeting. The instrument detected thousands of small particles and a few of them were large enough to even penetrate the first layer of the Whipple bumper shield. From the DFMI data it has been estimated that more than several thousands particles larger than 20 μ in diameter have been collected in the aerogel collector that will returned back to Earth in January 2006.

The nature of organic carbon in density-fractionated sediments in the Sacramento-San Joaquin River Delta (California)

NASA Astrophysics Data System (ADS)

Wakeham, S. G.; Canuel, E. A.

2016-02-01

Rivers are the primary means by which sediments and carbon are transported from the terrestrial biosphere to the oceans but gaps remain in our understanding of carbon associations from source to sink. Bed sediments from the Sacramento-San Joaquin River Delta (CA) were fractionated according to density and analyzed for sediment mass distribution, elemental (C and N) composition, mineral surface area, and stable carbon and radiocarbon isotope compositions of organic carbon (OC) and fatty acids to evaluate the nature of organic carbon in river sediments. OC was unevenly distributed among density fractions. Mass and OC were in general concentrated in mesodensity (1.6-2.0 and 2.0-2.5 g cm-3) fractions, comprising 84.0 ± 1.3 % of total sediment mass and 80.8 ± 13.3 % of total OC (TOC). Low-density (< 1.6 g cm-3) material, although rich in OC (34.0 ± 2.0 % OC) due to woody debris, constituted only 17.3 ± 12.8 % of TOC. High-density (> 2.5 g cm-3) organic-poor, mineral-rich material made-up 13.7 ± 1.4 % of sediment mass and 2.0 ± 0.9 % of TOC. Stable carbon isotope compositions of sedimentary OC were relatively uniform across bulk and density fractions (δ13C -27.4 ± 0.5 ‰). Radiocarbon content varied from Δ14C values of -382 (radiocarbon age 3800 yr BP) to +94 ‰ (modern) indicating a mix of young and old OC. Fatty acids were used to further constrain the origins of sedimentary OC. Short-chain n-C14-n-C18 fatty acids of algal origin were depleted in 13C (δ13C -37.5 to -35.2 ‰) but were enriched in 14C (Δ14C > 0) compared to long-chain n-C24-n-C28 acids of vascular plant origins with higher δ13C (-33.0 to -31.0 ‰) but variable Δ14C values (-180 and 61 ‰). These data demonstrate the potentially complex source and age distributions found within river sediments and provide insights about sediment and organic matter supply to the Delta.

Secondary motion in three-dimensional branching networks

NASA Astrophysics Data System (ADS)

Guha, Abhijit; Pradhan, Kaustav

2017-06-01

A major aim of the present work is to understand and thoroughly document the generation, the three-dimensional distribution, and the evolution of the secondary motion as the fluid progresses downstream through a branched network. Six generations (G0-G5) of branches (involving 63 straight portions and 31 bifurcation modules) are computed in one go; such computational challenges are rarely taken in the literature. More than 30 × 106 computational elements are employed for high precision of computed results and fine quality of the flow visualization diagrams. The study of co-planar vis-à-vis non-planar space-filling configurations establishes a quantitative evaluation of the dependence of the fluid dynamics on the three-dimensional arrangement of the same individual branches. As compared to the secondary motion in a simple curved pipe, three distinctive features, viz., the change of shape and size of the flow-cross-section, the division of non-uniform primary flow in a bifurcation module, and repeated switchover from clockwise to anticlockwise curvature and vice versa in the flow path, make the present situation more complex. It is shown that the straight portions in the network, in general, attenuate the secondary motion, while the three-dimensionally complex bifurcation modules generate secondary motion and may alter the number, arrangement, and structure of vortices. A comprehensive picture of the evolution of quantitative flow visualizations of the secondary motion is achieved by constructing contours of secondary velocity | v → S | , streamwise vorticity ω S , and λ 2 iso-surfaces. It is demonstrated, for example, that for in-plane configuration, the vortices on any plane appear in pair (i.e., for each clockwise rotating vortex, there is an otherwise identical anticlockwise vortex), whereas the vortices on a plane for the out-of-plane configuration may be dissimilar, and there may even be an odd number of vortices. We have formulated three new parameters (ES/P, δ S F , and δ G n ) for a quantitative description of the overall features of the secondary flow field. δ S F represents a non-uniformity index of the secondary flow in an individual branch, ES/P represents the mass-flow-averaged relative kinetic energy of the secondary motion in an individual branch, and δ G n provides a measure of the non-uniformity of the secondary flow between various branches of the same generation Gn. The repeated enhancement of the secondary kinetic energy in the bifurcation modules is responsible for the occurrence of significant values of ES/P even in generation G5. For both configurations, it is found that for any bifurcation module, the value of ES/P is greater in that daughter branch in which the mass-flow rate is greater. Even though the various contour plots of the complex secondary flow structure appear visually very different from one another, the values of δ S F are found to lie within a small range ( 0.37 ≤ δ S F ≤ 0.66 ) for the six-generation networks studied. It is shown that δ G n grows as the generation number Gn increases. It is established that the out-of-plane configuration, in general, creates more secondary kinetic energy (higher ES/P), a similar level of non-uniformity in the secondary flow in an individual branch (similar δ S F ), and a significantly lower level of non-uniformity in the distribution of secondary motion among various branches of the same generation (much lower δ G n ), as compared to the in-plane arrangement of the same branches.

Secondary motion in three-dimensional branching networks

PubMed Central

Guha, Abhijit; Pradhan, Kaustav

2017-01-01

A major aim of the present work is to understand and thoroughly document the generation, the three-dimensional distribution, and the evolution of the secondary motion as the fluid progresses downstream through a branched network. Six generations (G0-G5) of branches (involving 63 straight portions and 31 bifurcation modules) are computed in one go; such computational challenges are rarely taken in the literature. More than 30 × 106 computational elements are employed for high precision of computed results and fine quality of the flow visualization diagrams. The study of co-planar vis-à-vis non-planar space-filling configurations establishes a quantitative evaluation of the dependence of the fluid dynamics on the three-dimensional arrangement of the same individual branches. As compared to the secondary motion in a simple curved pipe, three distinctive features, viz., the change of shape and size of the flow-cross-section, the division of non-uniform primary flow in a bifurcation module, and repeated switchover from clockwise to anticlockwise curvature and vice versa in the flow path, make the present situation more complex. It is shown that the straight portions in the network, in general, attenuate the secondary motion, while the three-dimensionally complex bifurcation modules generate secondary motion and may alter the number, arrangement, and structure of vortices. A comprehensive picture of the evolution of quantitative flow visualizations of the secondary motion is achieved by constructing contours of secondary velocity v→S, streamwise vorticity ωS, and λ2 iso-surfaces. It is demonstrated, for example, that for in-plane configuration, the vortices on any plane appear in pair (i.e., for each clockwise rotating vortex, there is an otherwise identical anticlockwise vortex), whereas the vortices on a plane for the out-of-plane configuration may be dissimilar, and there may even be an odd number of vortices. We have formulated three new parameters (ES/P, δSF, and δGn) for a quantitative description of the overall features of the secondary flow field. δSF represents a non-uniformity index of the secondary flow in an individual branch, ES/P represents the mass-flow-averaged relative kinetic energy of the secondary motion in an individual branch, and δGn provides a measure of the non-uniformity of the secondary flow between various branches of the same generation Gn. The repeated enhancement of the secondary kinetic energy in the bifurcation modules is responsible for the occurrence of significant values of ES/P even in generation G5. For both configurations, it is found that for any bifurcation module, the value of ES/P is greater in that daughter branch in which the mass-flow rate is greater. Even though the various contour plots of the complex secondary flow structure appear visually very different from one another, the values of δSF are found to lie within a small range (0.37≤δSF≤0.66) for the six-generation networks studied. It is shown that δGn grows as the generation number Gn increases. It is established that the out-of-plane configuration, in general, creates more secondary kinetic energy (higher ES/P), a similar level of non-uniformity in the secondary flow in an individual branch (similar δSF), and a significantly lower level of non-uniformity in the distribution of secondary motion among various branches of the same generation (much lower δGn), as compared to the in-plane arrangement of the same branches. PMID:28713213

Advanced collapsible tank for liquid containment

NASA Technical Reports Server (NTRS)

Flanagan, David T.; Hopkins, Robert C.

1993-01-01

Tanks for bulk liquid containment will be required to support advanced planetary exploration programs. Potential applications include storage of potable, process, and waste water, and fuels and process chemicals. The launch mass and volume penalties inherent in rigid tanks suggest that collapsible tanks may be more efficient. Collapsible tanks are made of lightweight flexible material and can be folded compactly for storage and transport. Although collapsible tanks for terrestrial use are widely available, a new design was developed that has significantly less mass and bulk than existing models. Modelled after the shape of a sessible drop, this design features a dual membrane with a nearly uniform stress distribution and a low surface-to-volume ratio. It can be adapted to store a variety of liquids in nearly any environment with constant acceleration field. Three models of 10L, 50L, and 378L capacity have been constructed and tested. The 378L (100 gallon) model weighed less than 10 percent of a commercially available collapsible tank of equivalent capacity, and required less than 20 percent of the storage space when folded for transport.

Silica-based waste form for immobilization of iodine from reprocessing plant off-gas streams

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

Matyáš, Josef; Canfield, Nathan; Sulaiman, Sannoh

A high selectivity and sorption capacity for iodine and a feasible consolidation to a durable SiO2-based waste form makes silver-functionalized silica aerogel (Ag0-aerogel) an attractive choice for the removal and sequestration of iodine compounds from the off-gas of a nuclear fuel reprocessing plant. Hot uniaxial pressing of iodine-loaded Ag0-aerogel (20.2 mass% iodine) at 1200°C for 30 min under 29 MPa pressure provided a partially sintered product with residual open porosity of 16.9% that retained ~93% of sorbed iodine. Highly iodine-loaded Ag0-aerogel was successfully consolidated by hot isostatic pressing at 1200°C with a 30-min hold and under 207 MPa. The fullymore » densified waste form had a bulk density of 3.3 g/cm3 and contained ~39 mass% iodine. The iodine was retained in the form of nano- and micro-particles of AgI that were uniformly distributed inside and along boundaries of fused silica grains.« less

Experimental study of flash boiling spray vaporization through quantitative vapor concentration and liquid temperature measurements

NASA Astrophysics Data System (ADS)

Zhang, Gaoming; Hung, David L. S.; Xu, Min

2014-08-01

Flash boiling sprays of liquid injection under superheated conditions provide the novel solutions of fast vaporization and better air-fuel mixture formation for internal combustion engines. However, the physical mechanisms of flash boiling spray vaporization are more complicated than the droplet surface vaporization due to the unique bubble generation and boiling process inside a superheated bulk liquid, which are not well understood. In this study, the vaporization of flash boiling sprays was investigated experimentally through the quantitative measurements of vapor concentration and liquid temperature. Specifically, the laser-induced exciplex fluorescence technique was applied to distinguish the liquid and vapor distributions. Quantitative vapor concentration was obtained by correlating the intensity of vapor-phase fluorescence with vapor concentration through systematic corrections and calibrations. The intensities of two wavelengths were captured simultaneously from the liquid-phase fluorescence spectra, and their intensity ratios were correlated with liquid temperature. The results show that both liquid and vapor phase of multi-hole sprays collapse toward the centerline of the spray with different mass distributions under the flash boiling conditions. Large amount of vapor aggregates along the centerline of the spray to form a "gas jet" structure, whereas the liquid distributes more uniformly with large vortexes formed in the vicinity of the spray tip. The vaporization process under the flash boiling condition is greatly enhanced due to the intense bubble generation and burst. The liquid temperature measurements show strong temperature variations inside the flash boiling sprays with hot zones present in the "gas jet" structure and vortex region. In addition, high vapor concentration and closed vortex motion seem to have inhibited the heat and mass transfer in these regions. In summary, the vapor concentration and liquid temperature provide detailed information concerning the heat and mass transfer inside flash boiling sprays, which is important for the understanding of its unique vaporization process.

A statistical analysis of seeds and other high-contrast exoplanet surveys: massive planets or low-mass brown dwarfs?

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

Brandt, Timothy D.; Spiegel, David S.; McElwain, Michael W.

2014-10-20

We conduct a statistical analysis of a combined sample of direct imaging data, totalling nearly 250 stars. The stars cover a wide range of ages and spectral types, and include five detections (κ And b, two ∼60 M {sub J} brown dwarf companions in the Pleiades, PZ Tel B, and CD–35 2722B). For some analyses we add a currently unpublished set of SEEDS observations, including the detections GJ 504b and GJ 758B. We conduct a uniform, Bayesian analysis of all stellar ages using both membership in a kinematic moving group and activity/rotation age indicators. We then present a new statisticalmore » method for computing the likelihood of a substellar distribution function. By performing most of the integrals analytically, we achieve an enormous speedup over brute-force Monte Carlo. We use this method to place upper limits on the maximum semimajor axis of the distribution function derived from radial-velocity planets, finding model-dependent values of ∼30-100 AU. Finally, we model the entire substellar sample, from massive brown dwarfs to a theoretically motivated cutoff at ∼5 M {sub J}, with a single power-law distribution. We find that p(M, a)∝M {sup –0.65} {sup ±} {sup 0.60} a {sup –0.85} {sup ±} {sup 0.39} (1σ errors) provides an adequate fit to our data, with 1.0%-3.1% (68% confidence) of stars hosting 5-70 M {sub J} companions between 10 and 100 AU. This suggests that many of the directly imaged exoplanets known, including most (if not all) of the low-mass companions in our sample, formed by fragmentation in a cloud or disk, and represent the low-mass tail of the brown dwarfs.« less

VELOCITY SELECTOR METHOD FOR THE SEPARATION OF ISOTOPES

DOEpatents

Britten, R.J.

1957-12-31

A velocity selector apparatus is described for separating and collecting an enriched fraction of the isotope of a particular element. The invention has the advantage over conventional mass spectrometers in that a magnetic field is not used, doing away with the attendant problems of magnetic field variation. The apparatus separates the isotopes by selectively accelerating the ionized constituents present in a beam of the polyisotopic substance that are of uniform kinetic energy, the acceleration being applied intermittently and at spaced points along the beam and in a direction normal to the direction of the propagation of the uniform energy beam whereby a transverse displacement of the isotopic constituents of different mass is obtained.

Penetrance of Polygenic Obesity Susceptibility Loci across the Body Mass Index Distribution.

PubMed

Abadi, Arkan; Alyass, Akram; Robiou du Pont, Sebastien; Bolker, Ben; Singh, Pardeep; Mohan, Viswanathan; Diaz, Rafael; Engert, James C; Yusuf, Salim; Gerstein, Hertzel C; Anand, Sonia S; Meyre, David

2017-12-07

A growing number of single-nucleotide polymorphisms (SNPs) have been associated with body mass index (BMI) and obesity, but whether the effects of these obesity-susceptibility loci are uniform across the BMI distribution remains unclear. We studied the effects of 37 BMI-associated SNPs in 75,230 adults of European ancestry across BMI percentiles by using conditional quantile regression (CQR) and meta-regression (MR) models. The effects of nine SNPs (24%)-rs1421085 (FTO; p = 8.69 × 10 -15 ), rs6235 (PCSK1; p = 7.11 × 10 -6 ), rs7903146 (TCF7L2; p = 9.60 × 10 -6 ), rs11873305 (MC4R; p = 5.08 × 10 -5 ), rs12617233 (FANCL; p = 5.30 × 10 -5 ), rs11672660 (GIPR; p = 1.64 × 10 -4 ), rs997295 (MAP2K5; p = 3.25 × 10 -4 ), rs6499653 (FTO; p = 6.23 × 10 -4 ), and rs3824755 (NT5C2; p = 7.90 × 10 -4 )-increased significantly across the sample BMI distribution. We showed that such increases stemmed from unadjusted gene interactions that enhanced the effects of SNPs in persons with a high BMI. When 125 height-associated SNPs were analyzed for comparison, only one (<1%), rs6219 (IGF1, p = 1.80 × 10 -4 ), showed effects that varied significantly across height percentiles. Cumulative gene scores of these SNPs (GS-BMI and GS-height) showed that only GS-BMI had effects that increased significantly across the sample distribution (BMI: p = 7.03 × 10 -37 ; height: p = 0.499). Overall, these findings underscore the importance of gene-gene and gene-environment interactions in shaping the genetic architecture of BMI and advance a method for detecting such interactions by using only the sample outcome distribution. Copyright © 2017 American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Composition and structure of porcine digital flexor tendon-bone insertion tissues.

PubMed

Chandrasekaran, Sandhya; Pankow, Mark; Peters, Kara; Huang, Hsiao-Ying Shadow

2017-11-01

Tendon-bone insertion is a functionally graded tissue, transitioning from 200 MPa tensile modulus at the tendon end to 20 GPa tensile modulus at the bone, across just a few hundred micrometers. In this study, we examine the porcine digital flexor tendon insertion tissue to provide a quantitative description of its collagen orientation and mineral concentration by using Fast Fourier Transform (FFT) based image analysis and mass spectrometry, respectively. Histological results revealed uniformity in global collagen orientation at all depths, indicative of mechanical anisotropy, although at mid-depth, the highest fiber density, least amount of dispersion, and least cellular circularity were evident. Collagen orientation distribution obtained through 2D FFT of histological imaging data from fluorescent microscopy agreed with past measurements based on polarized light microscopy. Results revealed global fiber orientation across the tendon-bone insertion to be preserved along direction of physiologic tension. Gradation in the fiber distribution orientation index across the insertion was reflective of a decrease in anisotropy from the tendon to the bone. We provided elemental maps across the fibrocartilage for its organic and inorganic constituents through time-of-flight secondary ion mass spectrometry (TOF-SIMS). The apatite intensity distribution from the tendon to bone was shown to follow a linear trend, supporting past results based on Raman microprobe analysis. The merit of this study lies in the image-based simplified approach to fiber distribution quantification and in the high spatial resolution of the compositional analysis. In conjunction with the mechanical properties of the insertion tissue, fiber, and mineral distribution results for the insertion from this may potentially be incorporated into the development of a structural constitutive approach toward computational modeling. Characterizing the properties of the native insertion tissue would provide the microstructural basis for developing biomimetic scaffolds to recreate the graded morphology of a fibrocartilaginous insertion. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3050-3058, 2017. © 2017 Wiley Periodicals, Inc.

Ion distribution in dry polyelectrolyte multilayers: a neutron reflectometry study

DOE PAGES

Ghoussoub, Yara E.; Zerball, Maximilian; Fares, Hadi M.; ...

2018-02-09

Counterions were found to be uniformly distributed in polycation-terminated films of poly(diallyldimethylammonium) and poly(styrenesulfonate) prepared on silicon wafers using layer-by-layer adsorption.

A Complete Library of Infrared Spectral Energy Distributions for z=0 Galaxies

NASA Astrophysics Data System (ADS)

Sandstrom, Karin

CONTEXT: Half of the light emitted by galaxies is starlight absorbed and reprocessed into the infrared by dust. The spectral energy distribution (SED) of this IR emission encodes information on the mass and properties of the dust, the radiation field heating it, and the bolometric luminosity of the region. This makes IR emission a main tool to estimate star formation rates (SFRs) and to trace the distribution of the interstellar medium (ISM) in galaxies. The dust itself also plays key roles in the physics of star formation, and thereby galaxy evolution. This critical information on dust and its dependence on environment can only be reliably measured when we have observations with full wavelength coverage of the IR SED that resolve galaxies. With no new IR imaging missions on the horizon, the remarkably thorough census conducted by Herschel, Spitzer, and WISE of the nearby (D < 50 Mpc) galaxy population is the definitive resource on dust at z=0 for the foreseeable future. Such observations allow us to understand the behavior of the IR SED and so inform observations from the major new facilities ALMA and JWST, which have amazing sensitivity and resolution but limited wavelength coverage. OBJECTIVES: We will create a library of matched resolution, uniformly processed IR SEDs for all 532 local galaxies with resolved mapping in the Herschel, Spitzer, and WISE archives. We will associate the SED measurements with rich "value added" data, including fits of physical models to the IR SED (yielding small grain fractions, temperature, and dust masses), host galaxy properties (e.g., stellar mass, SFR, morphology, inclination), and local conditions in the galaxy (SFR and stellar surface density, ISM gas mass and metallicity where available). The library will be created for a range of spatial and angular scales and served through IRSA/MAST, providing a major high level legacy resource that will be useful to a wide community. We will exploit this database to address three major questions: (1) What powers the dust emission from galaxies and how does dust emission relate to the star formation rate? (2) How are dust and gas related across the galaxy population and how can dust emission best be used to trace gas? and (3) How does the dust grain population vary in response to local environment across galaxies? METHODS: We will use established techniques to uniformly process the archival data, fit models to the spectral energy distributions, match the data in resolution. These have been successfully deployed on similar data by individual teams (including us), but we will apply them to an order of magnitude larger sample. PERCEIVED SIGNIFICANCE: Dust is a main mediator of cloud and star formation, and thus galaxy evolution. Therefore, the properties and evolution of dust in galaxies is directly relevant to key NASA science goals to "Discover how the universe works, explore how it began and evolved, and search for life on planets around other stars." These are also essential tools to understand "How did we get here?" In practical terms, the database that we propose to create would be a major resource for many scientists: a tool to understand the physics of dust and the ISM for those studying local galaxies and a major aid to interpret monochromatic observations of high-z galaxies and galaxy surveys. This should have a large impact in the ALMA and (soon) JWST communities.

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

Higa, Kenneth; Zhao, Hui; Parkinson, Dilworth Y.

The internal structure of a porous electrode strongly influences battery performance. Understanding the dynamics of electrode slurry drying could aid in engineering electrodes with desired properties. For instance, one might monitor the dynamic, spatially-varying thickness near the edge of a slurry coating, as it should lead to non-uniform thickness of the dried film. This work examines the dynamic behavior of drying slurry drops consisting of SiO x and carbon black particles in a solution of carboxymethylcellulose and deionized water, as an experimental model of drying behavior near the edge of a slurry coating. An X-ray radiography-based procedure is developed tomore » calculate the evolving spatial distribution of active material particles from images of the drying slurry drops. To the authors’ knowledge, this study is the first to use radiography to investigate battery slurry drying, as well as the first to determine particle distributions from radiography images of drying suspensions. The dynamic results are consistent with tomography reconstructions of the static, fully-dried films. It is found that active material particles can rapidly become non-uniformly distributed within the drops. Heating can promote distribution uniformity, but seemingly must be applied very soon after slurry deposition. Higher slurry viscosity is found to strongly restrain particle redistribution.« less

Facile synthesis of concentrated gold nanoparticles with low size-distribution in water: temperature and pH controls

NASA Astrophysics Data System (ADS)

Li, Chunfang; Li, Dongxiang; Wan, Gangqiang; Xu, Jie; Hou, Wanguo

2011-07-01

The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

Misinterpretation of statistical distance in security of quantum key distribution shown by simulation

NASA Astrophysics Data System (ADS)

Iwakoshi, Takehisa; Hirota, Osamu

2014-10-01

This study will test an interpretation in quantum key distribution (QKD) that trace distance between the distributed quantum state and the ideal mixed state is a maximum failure probability of the protocol. Around 2004, this interpretation was proposed and standardized to satisfy both of the key uniformity in the context of universal composability and operational meaning of the failure probability of the key extraction. However, this proposal has not been verified concretely yet for many years while H. P. Yuen and O. Hirota have thrown doubt on this interpretation since 2009. To ascertain this interpretation, a physical random number generator was employed to evaluate key uniformity in QKD. In this way, we calculated statistical distance which correspond to trace distance in quantum theory after a quantum measurement is done, then we compared it with the failure probability whether universal composability was obtained. As a result, the degree of statistical distance of the probability distribution of the physical random numbers and the ideal uniformity was very large. It is also explained why trace distance is not suitable to guarantee the security in QKD from the view point of quantum binary decision theory.

IR-camera methods for automotive brake system studies

NASA Astrophysics Data System (ADS)

Dinwiddie, Ralph B.; Lee, Kwangjin

1998-03-01

Automotive brake systems are energy conversion devices that convert kinetic energy into heat energy. Several mechanisms, mostly related to noise and vibration problems, can occur during brake operation and are often related to non-uniform temperature distribution on the brake disk. These problems are of significant cost to the industry and are a quality concern to automotive companies and brake system vendors. One such problem is thermo-elastic instabilities in brake system. During the occurrence of these instabilities several localized hot spots will form around the circumferential direction of the brake disk. The temperature distribution and the time dependence of these hot spots, a critical factor in analyzing this problem and in developing a fundamental understanding of this phenomenon, were recorded. Other modes of non-uniform temperature distributions which include hot banding and extreme localized heating were also observed. All of these modes of non-uniform temperature distributions were observed on automotive brake systems using a high speed IR camera operating in snap-shot mode. The camera was synchronized with the rotation of the brake disk so that the time evolution of hot regions could be studied. This paper discusses the experimental approach in detail.

Marcus-Hush-Chidsey theory of electron transfer to and from species bound at a non-uniform electrode surface: Theory and experiment

NASA Astrophysics Data System (ADS)

Henstridge, Martin C.; Batchelor-McAuley, Christopher; Gusmão, Rui; Compton, Richard G.

2011-11-01

Two simple models of electrode surface inhomogeneity based on Marcus-Hush theory are considered; a distribution in formal potentials and a distribution in electron tunnelling distances. Cyclic voltammetry simulated using these models is compared with that simulated using Marcus-Hush theory for a flat, uniform and homogeneous electrode surface, with the two models of surface inhomogeneity yielding broadened peaks with decreased peak-currents. An edge-plane pyrolytic graphite electrode is covalently modified with ferrocene via 'click' chemistry and the resulting voltammetry compared with each of the three previously considered models. The distribution of formal potentials is seen to fit the experimental data most closely.

The Fate of Colloidal Swarms in Fractures

NASA Astrophysics Data System (ADS)

Pyrak-Nolte, L. J.; Olander, M. K.

2009-12-01

In the next 10-20 years, nano- and micro-sensor engineering will advance to the stage where sensor swarms could be deployed in the subsurface to probe rock formations and the fluids contained in them. Sensor swarms are groups of nano- or micro- sensors that are maintained as a coherent group to enable either sensor-to-sensor communication and/or coherent transmission of information as a group. The ability to maintain a swarm of sensors depends on the complexity of the flow paths in the rock, on the size and shape of the sensors and on the chemical interaction among the sensors, fluids, and rock surfaces. In this study, we investigate the effect of fracture aperture and fluid currents on the formation, evolution and break-up of colloidal swarms under gravity. Transparent cubic samples (100 mm x 100 mm x 100 mm) containing synthetic fractures with uniform and non-uniform aperture distributions were used to quantify the effect of aperture on swarm formation, swarm velocity, and swarm geometry using optical imaging. A fracture with a uniform aperture distribution was fabricated from two polished rectangular prisms of acrylic. A fracture with a non-uniform aperture distribution was created with a polished rectangular acrylic prism and an acrylic replica of an induced fracture surface from a carbonate rock. A series of experiments were performed to determine how swarm movement and geometry are affected as the walls of the fracture are brought closer together from 50 mm to 1 mm. During the experiments, the fracture was fully saturated with water. We created the swarms using two different particle sizes in dilute suspension (~ 1.0% by mass) . The particles were 3 micron diameter fluorescent polymer beads and 25 micron diameter soda-lime glass beads. The swarm behavior was imaged using an optical fluorescent imaging system composed of a CCD camera illuminated by a 100 mW diode-pumped doubled YAG laser. A swam was created when approximately 0.01 g drop of the suspension was released under gravity into the water. The swarm density is slightly greater than water and falls faster than the terminal velocity of an individual particle in water. The cohesiveness of the swarm was maintained over 50 mm to 95 mm even in the presence of fluid currents. The swarm velocity decreased with decreasing fracture aperture. When the apertures are small, swarms break-up and reform as they pass through a variable aperture fracture. Acknowledgment: The authors wish to acknowledge support of this work by the Geosciences Research Program, Office of Basic Energy Sciences US Department of Energy (DE-FG02-09ER16022) and the Summer Undergraduate Research Fellowship program at Purdue University.

An Investigation into Performance Modelling of a Small Gas Turbine Engine

DTIC Science & Technology

2012-10-01

b = Combustor part load constant f = Fuel to mass flow ratio or scale factor h = Enthalpy F = Force P = Pressure T = Temperature W = Mass flow...HP engine performance parameters[5,6] Parameter Condition (ISA, SLS) Value Thrust 108000 rpm 230 N Pressure Ratio 108000 rpm 4 Mass Flow Rate...system. The reasons for removing the electric starter were to ensure uniform flow through the bell- mouth for mass flow rate measurement, eliminate a

Uniform-related infection control practices of dental students

PubMed Central

Aljohani, Yazan; Almutadares, Mohammed; Alfaifi, Khalid; El Madhoun, Mona; Albahiti, Maysoon H; Al-Hazmi, Nadia

2017-01-01

Background Uniform-related infection control practices are sometimes overlooked and underemphasized. In Saudi Arabia, personal protective equipment must meet global standards for infection control, but the country’s Islamic legislature also needs to be taken into account. Aim To assess uniform-related infection control practices of a group of dental students in a dental school in Saudi Arabia and compare the results with existing literature related to cross-contamination through uniforms in the dental field. Method A questionnaire was formulated and distributed to dental students at King Abdulaziz University Faculty of Dentistry in Jeddah, Saudi Arabia, which queried the students about their uniform-related infection control practices and their methods and frequency of laundering and sanitizing their uniforms, footwear, and name tags. Results There is a significant difference between genders with regard to daily uniform habits. The frequency of uniform washing was below the standard and almost 30% of students were not aware of how their uniforms are washed. Added to this, there is no consensus on a unified uniform for male and female students. Conclusion Information on preventing cross-contamination through wearing uniforms must be supplied, reinforced, and emphasized while taking into consideration the cultural needs of the Saudi society. PMID:28490894

Development of on-site PAFC stacks

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

Hotta, K.; Matsumoto, Y.; Horiuchi, H.

1996-12-31

PAFC (Phosphoric Acid Fuel Cell) has been researched for commercial use and demonstration plants have been installed in various sites. However, PAFC don`t have a enough stability yet, so more research and development must be required in the future. Especially, cell stack needs a proper state of three phases (liquid, gas and solid) interface. It is very difficult technology to keep this condition for a long time. In the small size cell with the electrode area of 100 cm{sup 2}, gas flow and temperature distributions show uniformity. But in the large size cell with the electrode area of 4000 cm{supmore » 2}, the temperature distributions show non-uniformity. These distributions would cause to be shorten the cell life. Because these distributions make hot-spot and gas poverty in limited parts. So we inserted thermocouples in short-stack for measuring three-dimensional temperature distributions and observed effects of current density and gas utilization on temperature.« less

Some limit theorems for ratios of order statistics from uniform random variables.

PubMed

Xu, Shou-Fang; Miao, Yu

2017-01-01

In this paper, we study the ratios of order statistics based on samples drawn from uniform distribution and establish some limit properties such as the almost sure central limit theorem, the large deviation principle, the Marcinkiewicz-Zygmund law of large numbers and complete convergence.

Tensile testing grips ensure uniform loading of bimetal tubing specimens

NASA Technical Reports Server (NTRS)

Driscol, S. D.; Hunt, V.

1968-01-01

Tensile testing grip uniformly distributes stresses to the internal and external tube of bimetal tubing specimens. The grip is comprised of a slotted external tube grip, a slotted internal tube grip, a machine bolt and nut, an internal grip expansion cone, and an external grip compression nut.

The mixing of rain with near-surface water

Treesearch

Dennis F. Houk

1976-01-01

Rain experiments were run with various temperature differences between the warm rain and the cool receiving water. The rain intensities were uniform and the raindrop sizes were usually uniform (2.2 mm, 3.6 mm, and 5.5 mm diameter drops). Two drop size distributions were also used.

Anode current density distribution in a cusped field thruster

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

Wu, Huan, E-mail: wuhuan58@qq.com; Liu, Hui, E-mail: hlying@gmail.com; Meng, Yingchao

2015-12-15

The cusped field thruster is a new electric propulsion device that is expected to have a non-uniform radial current density at the anode. To further study the anode current density distribution, a multi-annulus anode is designed to directly measure the anode current density for the first time. The anode current density decreases sharply at larger radii; the magnitude of collected current density at the center is far higher compared with the outer annuli. The anode current density non-uniformity does not demonstrate a significant change with varying working conditions.

Evaluation of lithium alloy anode materials for Li-TiS2 cells

NASA Technical Reports Server (NTRS)

Huang, C.-K.; Subbarao, S.; Shen, D. H.; Deligiannis, F.; Attia, A.; Halpert, G.

1991-01-01

A study was performed to select candidate lithium alloy anode materials and establish selection criteria. Some of the selected alloy materials were evaluated for their electrochemical properties and performance. This paper describes the criteria for the selection of alloys and the findings of the studies. Li-Si and Li-Cd alloys have been found to be unstable in the EC+2-MeTHF-based electrolyte. The Li-Al alloy system was found to be promising among the alloy systems studied in view of its stability and reversibility. Unfortunately, the large volume changes of LiAl alloys during charge/discharge cycling cause considerable 'exfoliation' of its active mass. This paper also describes ways how to address this problem. The rate of disintegration of this anode would probably be surpressed by the presence of an inert solid solution or a uniform distribution of precipitates within the grains of the active mass. It was discovered that the addition of a small quantity of Mn may improve the mechanical properties of LiAl. In an attempt to reduce the Li-Al alloy vs. Li voltage, it was observed that LiAlPb(0.1)Cd(0.3) material can be cycled at 1.5 mA/sq cm without exfoliation of the active mass.

Localization of phonons in mass-disordered alloys: A typical medium dynamical cluster approach

DOE PAGES

Jarrell, Mark; Moreno, Juana; Raja Mondal, Wasim; ...

2017-07-20

The effect of disorder on lattice vibrational modes has been a topic of interest for several decades. In this article, we employ a Green's function based approach, namely, the dynamical cluster approximation (DCA), to investigate phonons in mass-disordered systems. Detailed benchmarks with previous exact calculations are used to validate the method in a wide parameter space. An extension of the method, namely, the typical medium DCA (TMDCA), is used to study Anderson localization of phonons in three dimensions. We show that, for binary isotopic disorder, lighter impurities induce localized modes beyond the bandwidth of the host system, while heavier impuritiesmore » lead to a partial localization of the low-frequency acoustic modes. For a uniform (box) distribution of masses, the physical spectrum is shown to develop long tails comprising mostly localized modes. The mobility edge separating extended and localized modes, obtained through the TMDCA, agrees well with results from the transfer matrix method. A reentrance behavior of the mobility edge with increasing disorder is found that is similar to, but somewhat more pronounced than, the behavior in disordered electronic systems. Our work establishes a computational approach, which recovers the thermodynamic limit, is versatile and computationally inexpensive, to investigate lattice vibrations in disordered lattice systems.« less

Localization of phonons in mass-disordered alloys: A typical medium dynamical cluster approach

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

Jarrell, Mark; Moreno, Juana; Raja Mondal, Wasim

The effect of disorder on lattice vibrational modes has been a topic of interest for several decades. In this article, we employ a Green's function based approach, namely, the dynamical cluster approximation (DCA), to investigate phonons in mass-disordered systems. Detailed benchmarks with previous exact calculations are used to validate the method in a wide parameter space. An extension of the method, namely, the typical medium DCA (TMDCA), is used to study Anderson localization of phonons in three dimensions. We show that, for binary isotopic disorder, lighter impurities induce localized modes beyond the bandwidth of the host system, while heavier impuritiesmore » lead to a partial localization of the low-frequency acoustic modes. For a uniform (box) distribution of masses, the physical spectrum is shown to develop long tails comprising mostly localized modes. The mobility edge separating extended and localized modes, obtained through the TMDCA, agrees well with results from the transfer matrix method. A reentrance behavior of the mobility edge with increasing disorder is found that is similar to, but somewhat more pronounced than, the behavior in disordered electronic systems. Our work establishes a computational approach, which recovers the thermodynamic limit, is versatile and computationally inexpensive, to investigate lattice vibrations in disordered lattice systems.« less

Analytical modeling of large amplitude free vibration of non-uniform beams carrying a both transversely and axially eccentric tip mass

NASA Astrophysics Data System (ADS)

Malaeke, Hasan; Moeenfard, Hamid

2016-03-01

The objective of this paper is to study large amplitude flexural-extensional free vibration of non-uniform cantilever beams carrying a both transversely and axially eccentric tip mass. The effects of variable axial force is also taken into account. Hamilton's principle is utilized to obtain the partial differential equations governing the nonlinear vibration of the system as well as the corresponding boundary conditions. A numerical finite difference scheme is proposed to find the natural frequencies and mode shapes of the system which is validated specifically for a beam with linearly varying cross section. Using a single mode approximation in conjunction with the Lagrange method, the governing equations are reduced to a set of two nonlinear ordinary differential equations in terms of end displacement components of the beam which are coupled due to the presence of the transverse eccentricity. These temporal coupled equations are then solved analytically using the multiple time scales perturbation technique. The obtained analytical results are compared with the numerical ones and excellent agreement is observed. The qualitative and quantitative knowledge resulting from this research is expected to enable the study of the effects of eccentric tip mass and non-uniformity on the large amplitude flexural-extensional vibration of beams for improved dynamic performance.

Research on acting mechanism and behavior of a gas bubble in the air dense medium fluidized bed

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

Tao, X.; Chen, Q.; Yang, Y.

1996-12-31

Coal dry beneficiation with air-dense medium fluidized bed has now been established as a high efficiency dry separation technology, it is the application of fluidization technology to the coal preparation field. The tiny particle media forms an uniform and stable fluidized bed with a density acted by airflow, which is used to separate 80{micro}m to {approximately}6mm size coal. This technology has achieved satisfied industrialization results, and attracted the expert`s attention in the field. In fluidized bed, the interaction between gas and solid was mainly decided by the existence state of heavy media particles mass (position and distance) relative velocity ofmore » gas-solid two phase, as well turbulent action. A change of vertical gas-solid fluidizing state essentially is the one of a energy transforming process. For a coal separating process with air-dense medium fluidized bed, the gas bubble, producing a turbulent and stirring action in the bed, leads to two effects. It can promote a uniform distribution of heavy media particles, and a uniform and stability of a bed density. Otherwise it will decrease effective contacts between gas-solids two phases, producing a bigger gas bubble. Therefore controlling a gas bubble size in bed should be optimized. This paper analyzes mutual movement between gas-solid, and studies the gas bubble behavior in the bed. A mechanic mode and a separating process of coal in the bed is discussed. It aims to research the coal separating mechanism with air-dense fluidized bed.« less

Impact of temporal probability in 4D dose calculation for lung tumors.

PubMed

Rouabhi, Ouided; Ma, Mingyu; Bayouth, John; Xia, Junyi

2015-11-08

The purpose of this study was to evaluate the dosimetric uncertainty in 4D dose calculation using three temporal probability distributions: uniform distribution, sinusoidal distribution, and patient-specific distribution derived from the patient respiratory trace. Temporal probability, defined as the fraction of time a patient spends in each respiratory amplitude, was evaluated in nine lung cancer patients. Four-dimensional computed tomography (4D CT), along with deformable image registration, was used to compute 4D dose incorporating the patient's respiratory motion. First, the dose of each of 10 phase CTs was computed using the same planning parameters as those used in 3D treatment planning based on the breath-hold CT. Next, deformable image registration was used to deform the dose of each phase CT to the breath-hold CT using the deformation map between the phase CT and the breath-hold CT. Finally, the 4D dose was computed by summing the deformed phase doses using their corresponding temporal probabilities. In this study, 4D dose calculated from the patient-specific temporal probability distribution was used as the ground truth. The dosimetric evaluation matrix included: 1) 3D gamma analysis, 2) mean tumor dose (MTD), 3) mean lung dose (MLD), and 4) lung V20. For seven out of nine patients, both uniform and sinusoidal temporal probability dose distributions were found to have an average gamma passing rate > 95% for both the lung and PTV regions. Compared with 4D dose calculated using the patient respiratory trace, doses using uniform and sinusoidal distribution showed a percentage difference on average of -0.1% ± 0.6% and -0.2% ± 0.4% in MTD, -0.2% ± 1.9% and -0.2% ± 1.3% in MLD, 0.09% ± 2.8% and -0.07% ± 1.8% in lung V20, -0.1% ± 2.0% and 0.08% ± 1.34% in lung V10, 0.47% ± 1.8% and 0.19% ± 1.3% in lung V5, respectively. We concluded that four-dimensional dose computed using either a uniform or sinusoidal temporal probability distribution can approximate four-dimensional dose computed using the patient-specific respiratory trace.

A simplified model of biosonar echoes from foliage and the properties of natural foliages.

PubMed

Ming, Chen; Zhu, Hongxiao; Müller, Rolf

2017-01-01

Foliage echoes could play an important role in the sensory ecology of echolocating bats, but many aspects of their sensory information content remain to be explored. A realistic numerical model for these echoes could support the development of hypotheses for the relationship between foliage properties and echo parameters. In prior work by the authors, a simple foliage model based on circular disks distributed uniformly in space has been developed. In the current work, three key simplifications used in this model have been examined: (i) representing leaves as circular disks, (ii) neglecting shading effects between leaves, and (iii) the uniform spatial distribution of the leaves. The target strengths of individual leaves and shading between them have been examined in physical experiments, whereas the impact of the spatial leaf distribution has been studied by modifying the numerical model to include leaf distributions according to a biomimetic model for natural branching patterns (L-systems). Leaf samples from a single species (leatherleaf arrowwood) were found to match the relationship between size and target strength of the disk model fairly well, albeit with a large variability part of which could be due to unaccounted geometrical features of the leaves. Shading between leaf-sized disks did occur for distances below 50 cm and could hence impact the echoes. Echoes generated with L-system models in two distinct tree species (ginkgo and pine) showed consistently more temporal inhomogeneity in the envelope amplitudes than a reference with uniform distribution. However, these differences were small compared to effects found in response to changes in the relative orientation of simulated sonar beam and foliage. These findings support the utility of the uniform leaf distribution model and suggest that bats could use temporal inhomogeneities in the echoes to make inferences regarding the relative positioning of their sonar and a foliage.

A simplified model of biosonar echoes from foliage and the properties of natural foliages

PubMed Central

Zhu, Hongxiao; Müller, Rolf

2017-01-01

Foliage echoes could play an important role in the sensory ecology of echolocating bats, but many aspects of their sensory information content remain to be explored. A realistic numerical model for these echoes could support the development of hypotheses for the relationship between foliage properties and echo parameters. In prior work by the authors, a simple foliage model based on circular disks distributed uniformly in space has been developed. In the current work, three key simplifications used in this model have been examined: (i) representing leaves as circular disks, (ii) neglecting shading effects between leaves, and (iii) the uniform spatial distribution of the leaves. The target strengths of individual leaves and shading between them have been examined in physical experiments, whereas the impact of the spatial leaf distribution has been studied by modifying the numerical model to include leaf distributions according to a biomimetic model for natural branching patterns (L-systems). Leaf samples from a single species (leatherleaf arrowwood) were found to match the relationship between size and target strength of the disk model fairly well, albeit with a large variability part of which could be due to unaccounted geometrical features of the leaves. Shading between leaf-sized disks did occur for distances below 50 cm and could hence impact the echoes. Echoes generated with L-system models in two distinct tree species (ginkgo and pine) showed consistently more temporal inhomogeneity in the envelope amplitudes than a reference with uniform distribution. However, these differences were small compared to effects found in response to changes in the relative orientation of simulated sonar beam and foliage. These findings support the utility of the uniform leaf distribution model and suggest that bats could use temporal inhomogeneities in the echoes to make inferences regarding the relative positioning of their sonar and a foliage. PMID:29240840

Differences in simulated fire spread over Askervein Hill using two advanced wind models and a traditional uniform wind field

Treesearch

Jason Forthofer; Bret Butler

2007-01-01

A computational fluid dynamics (CFD) model and a mass-consistent model were used to simulate winds on simulated fire spread over a simple, low hill. The results suggest that the CFD wind field could significantly change simulated fire spread compared to traditional uniform winds. The CFD fire spread case may match reality better because the winds used in the fire...

Self-organization of cosmic radiation pressure instability. II - One-dimensional simulations

NASA Technical Reports Server (NTRS)

Hogan, Craig J.; Woods, Jorden

1992-01-01

The clustering of statistically uniform discrete absorbing particles moving solely under the influence of radiation pressure from uniformly distributed emitters is studied in a simple one-dimensional model. Radiation pressure tends to amplify statistical clustering in the absorbers; the absorbing material is swept into empty bubbles, the biggest bubbles grow bigger almost as they would in a uniform medium, and the smaller ones get crushed and disappear. Numerical simulations of a one-dimensional system are used to support the conjecture that the system is self-organizing. Simple statistics indicate that a wide range of initial conditions produce structure approaching the same self-similar statistical distribution, whose scaling properties follow those of the attractor solution for an isolated bubble. The importance of the process for large-scale structuring of the interstellar medium is briefly discussed.

Evaluation of illumination system uniformity for wide-field biomedical hyperspectral imaging

NASA Astrophysics Data System (ADS)

Sawyer, Travis W.; Siri Luthman, A.; E Bohndiek, Sarah

2017-04-01

Hyperspectral imaging (HSI) systems collect both spatial (morphological) and spectral (chemical) information from a sample. HSI can provide sensitive analysis for biological and medical applications, for example, simultaneously measuring reflectance and fluorescence properties of a tissue, which together with structural information could improve early cancer detection and tumour characterisation. Illumination uniformity is a critical pre-condition for quantitative data extraction from an HSI system. Non-uniformity can cause glare, specular reflection and unwanted shading, which negatively impact statistical analysis procedures used to extract abundance of different chemical species. Here, we model and evaluate several illumination systems frequently used in wide-field biomedical imaging to test their potential for HSI. We use the software LightTools and FRED. The analysed systems include: a fibre ring light; a light emitting diode (LED) ring; and a diffuse scattering dome. Each system is characterised for spectral, spatial, and angular uniformity, as well as transfer efficiency. Furthermore, an approach to measure uniformity using the Kullback-Leibler divergence (KLD) is introduced. The KLD is generalisable to arbitrary illumination shapes, making it an attractive approach for characterising illumination distributions. Although the systems are quite comparable in their spatial and spectral uniformity, the most uniform angular distribution is achieved using a diffuse scattering dome, yielding a contrast of 0.503 and average deviation of 0.303 over a ±60° field of view with a 3.9% model error in the angular domain. Our results suggest that conventional illumination sources can be applied in HSI, but in the case of low light levels, bespoke illumination sources may offer improved performance.

Uniform magnetic targeting of magnetic particles attracted by a new ferromagnetic biological patch.

PubMed

Pei, Ning; Cai, Lanlan; Yang, Kai; Ma, Jiaqi; Gong, Yongyong; Wang, Qixin; Huang, Zheyong

2018-02-01

A new non-toxic ferromagnetic biological patch (MBP) was designed in this paper. The MBP consisted of two external layers that were made of transparent silicone, and an internal layer that was made of a mixture of pure iron powder and silicon rubber. Finite-element analysis showed that the local inhomogeneous magnetic field (MF) around the MBP was generated when MBP was placed in a uniform MF. The local MF near the MBP varied with the uniform MF and shape of the MBP. Therefore, not only could the accumulation of paramagnetic particles be adjusted by controlling the strength of the uniform MF, but also the distribution of the paramagnetic particles could be improved with the different shape of the MBP. The relationship of the accumulation of paramagnetic particles or cells, magnetic flux density, and fluid velocity were studied through in vitro experiments and theoretical considerations. The accumulation of paramagnetic particles first increased with increment in the magnetic flux density of the uniform MF. But when the magnetic flux density of the uniform MF exceeded a specific value, the magnetic flux density of the MBP reached saturation, causing the accumulation of paramagnetic particles to fall. In addition, the adsorption morphology of magnetic particles or cells could be improved and the uniform distribution of magnetic particles could be achieved by changing the shape of the MBP. Also, MBP may be used as a new implant to attract magnetic drug carrier particles in magnetic drug targeting. Bioelectromagnetics. 39:98-107, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Spatial distribution visualization of PWM continuous variable-rate spray

USDA-ARS?s Scientific Manuscript database

Chemical application is a dynamic spatial distribution process, during which spray liquid covers the targets with certain thickness and uniformity. Therefore, it is important to study the 2-D and 3-D (dimensional) spray distribution to evaluate spraying quality. The curve-surface generation methods ...

Studies on thermokinetic of Chlorella pyrenoidosa devolatilization via different models.

PubMed

Chen, Zhihua; Lei, Jianshen; Li, Yunbei; Su, Xianfa; Hu, Zhiquan; Guo, Dabin

2017-11-01

The thermokinetics of Chlorella pyrenoidosa (CP) devolatilization were investigated based on iso-conversional model and different distributed activation energy models (DAEM). Iso-conversional process result showed that CP devolatilization roughly followed a single-step with mechanism function of f(α)=(1-α) 3 , and kinetic parameters pair of E 0 =180.5kJ/mol and A 0 =1.5E+13s -1 . Logistic distribution was the most suitable activation energy distribution function for CP devolatilization. Although reaction order n=3.3 was in accordance with iso-conversional process, Logistic DAEM could not detail the weight loss features since it presented as single-step reaction. The un-uniform feature of activation energy distribution in Miura-Maki DAEM, and weight fraction distribution in discrete DAEM reflected weight loss features. Due to the un-uniform distribution of activation and weight fraction, Miura-Maki DAEM and discreted DAEM could describe weight loss features. Copyright © 2017 Elsevier Ltd. All rights reserved.

Distribution of volumes of individual glomeruli in kidneys at autopsy: association with age, nephron number, birth weight and body mass index.

PubMed

Hoy, W E; Hughson, M D; Zimanyi, M; Samuel, T; Douglas-Denton, R; Holden, L; Mott, S; Bertram, J F

2010-11-01

Glomerular hypertrophy occurs in a number of normal and pathological states. Glomerular volume in kidneys at autopsy is usually indirectly derived from estimates of total glomerular mass and nephron number, and provides only a single value per kidney, with no indication of the range of volumes of glomeruli within the kidney of any given subject. We review findings of the distribution of volumes of different glomeruli within subjects without kidney disease, and their correlations with age, nephron number, birth weight and body mass index (BMI). The study describes findings from autopsy kidneys of selected adult white males from the Southeast USA who had unexpected deaths, and who did not have renal scarring or renal disease. Total glomerular (nephron) number and total glomerular volume were estimated using the disector/fractionator combination, and mean glomerular volume (Vglom) was derived. The volumes of 30 individual glomeruli (IGV) in each subject were determined using the disector/Cavalieri method. IGV values were compared by categories of age, nephron number, birth weight and BMI. There was substantial variation in IGV within subjects. Older age, lower nephron number, lower birth weight and gross obesity were associated with higher mean IGV and with greater IGV heterogeneity. High Vglom and high IGVs were associated with more glomerulosclerosis. However, amongst the generally modest numbers of sclerosed glomeruli, the pattern was uniformly of ischemic collapse of the glomerular tuft. There was no detectable focal segmental glomerular tuft injury. In this series of people without overt renal disease, greater age, nephron deficit, lower birth weight and obesity were marked by glomerular enlargement and greater glomerular volume heterogeneity within individuals.

Numerical investigation of a heat transfer characteristics of an impingement cooling system with non-uniform temperature on a cooled surface

NASA Astrophysics Data System (ADS)

Marzec, K.; Kucaba-Pietal, A.

2016-09-01

A series of numerical analysis have been performed to investigate heat transfer characteristics of an impingement cooling array of ten jets directed to the flat surface with different heat flux qw(x). A three-dimensional finite element model was used to solve equations of heat and mass transfer. The study focused on thermal stresses reduction on a cooled surface and aims at answering the question how the Nusselt number distribution on the cooled surface is affected by various inlet flow parameters for different heat flux distributions. The setup consists of a cylindrical plenum with an inline array of ten impingement jets. Simulation has been performed using the Computational Fluid Dynamics (CFD) code Ansys CFX. The k - ω shear stress transport (SST) turbulence model is used in calculations. The numerical analysis of the different mesh density results in good convergence of the GCI index, what excluded mesh size dependency. The physical model is simplified by using the steady state analysis and the incompressible and viscous flow of the fluid.

Distributor means for charging particulate material into receptacles

DOEpatents

Greaves, Melvin J.

1977-06-14

Disclosed are receptacles, such as shaft furnaces illustrated by a blast furnace and an upright oil shale retort, embodying rotatable charge distributor means for distributing particulate charge material in the furnace, which charge distributor means can provide a high uniformity of distribution of various sizes of particles and also can provide and maintain a stock line of desired contour and heighth in the receptacle. The distributor means includes a hopper having rigidly fixed to it a plurality of downwardly extending chutes with lower discharge portions that discharge in concentric circular zones at the stock line. The distributor means includes a segmented portion at the juncture of the hopper and the chutes that divides the charge material discharged into the hopper in proportion to the area of the circular zone at the stock line that is fed by the chute. The distributor means embodies means for providing mass flow of the particulate charge material through the chutes to the stock line and for avoiding segregation between larger and smaller particles of charge material deposited at the stock line.

Thermal Modeling and Management of Solid Oxide Fuel Cells Operating with Internally Reformed Methane

NASA Astrophysics Data System (ADS)

Wu, Yiyang; Shi, Yixiang; Cai, Ningsheng; Ni, Meng

2018-06-01

A detailed three-dimensional mechanistic model of a large-scale solid oxide fuel cell (SOFC) unit running on partially pre-reformed methane is developed. The model considers the coupling effects of chemical and electrochemical reactions, mass transport, momentum and heat transfer in the SOFC unit. After model validation, parametric simulations are conducted to investigate how the methane pre-reforming ratio affects the transport and electrochemistry of the SOFC unit. It is found that the methane steam reforming reaction has a "smoothing effect", which can achieve more uniform distributions of gas compositions, current density and temperature among the cell plane. In the case of 1500 W/m2 power density output, adding 20% methane absorbs 50% of internal heat production inside the cell, reduces the maximum temperature difference inside the cell from 70 K to 22 K and reduces the cathode air supply by 75%, compared to the condition of completely pre-reforming of methane. Under specific operating conditions, the pre-reforming ratio of methane has an optimal range for obtaining a good temperature distribution and good cell performance.

Packing of Fruit Fly Parasitoids for Augmentative Releases

PubMed Central

Montoya, Pablo; Cancino, Jorge; Ruiz, Lía

2012-01-01

The successful application of Augmentative Biological Control (ABC) to control pest fruit flies (Diptera: Tephritidae) confronts two fundamental requirements: (1) the establishment of efficient mass rearing procedures for the species to be released, and (2) the development of methodologies for the packing and release of parasitoids that permit a uniform distribution and their optimal field performance under an area-wide approach. Parasitoid distributions have been performed by ground and by air with moderate results; both options face challenges that remain to be addressed. Different devices and strategies have been used for these purposes, including paper bags and the chilled adult technique, both of which are commonly used when releasing sterile flies. However, insect parasitoids have morphological and behavioral characteristics that render the application of such methodologies suboptimal. In this paper, we discuss an alternate strategy for the augmentative release of parasitoids and describe packing conditions that favor the rearing and emergence of adult parasitoids for increased field performance. We conclude that the use of ABC, including the packaging of parasitoids, requires ongoing development to ensure that this technology remains a viable and effective control technique for pest fruit flies. PMID:26466634

Investigation of low-latitude hydrogen emission in terms of a two-component interstellar gas model

NASA Technical Reports Server (NTRS)

Baker, P. L.; Burton, W. B.

1975-01-01

High-resolution 21-cm hydrogen line observations at low galactic latitude are analyzed to determine the large-scale distribution of galactic hydrogen. Distribution parameters are found by model fitting, optical depth effects are computed using a two-component gas model suggested by the observations, and calculations are made for a one-component uniform spin-temperature gas model to show the systematic departures between this model and data obtained by incorrect treatment of the optical depth effects. Synthetic 21-cm line profiles are computed from the two-component model, and the large-scale trends of the observed emission profiles are reproduced together with the magnitude of the small-scale emission irregularities. Values are determined for the thickness of the galactic hydrogen disk between half density points, the total observed neutral hydrogen mass of the galaxy, and the central number density of the intercloud hydrogen atoms. It is shown that typical hydrogen clouds must be between 1 and 13 pc in diameter and that optical thinness exists on large-scale despite the presence of optically thin gas.

Kyllinga brevifolia mediated greener silver nanoparticles

NASA Astrophysics Data System (ADS)

Isa, Norain; Bakhari, Nor Aziyah; Sarijo, Siti Halimah; Aziz, Azizan; Lockman, Zainovia

2017-12-01

Kyllinga brevifolia extract (KBE) was studied in this research as capping as well as reducing agent for the synthesis of greener plant mediated silver nanoparticles. This research was conducted in order to identify the compounds in the KBE that probable to work as reductant for the synthesis of Kyllinga brevifolia-mediated silver nanoparticles (AgNPs). Screening test such as Thin Layer Chromatography (TLC), Fourier Transform Infra-Red (FTIR), Carlo Erba Elemental analysis and Gas Chromatography-Mass Spectroscopy (GCMS) were used in identifying the natural compounds in KBE. The as-prepared AgNPs were characterized by UV-vis spectroscopy (UV-vis), Transmission Electron Microscope (TEM) and X-ray Diffraction (XRD). The TEM images showed that the as-synthesized silver have quasi-spherical particles are distributed uniformly with a narrow distribution from 5 nm to 40 nm. The XRD results demonstrated that the obtained AgNPs were face centre-cubic (FCC) structure. The catalytic activity of AgNPs on reduction of methylene blue (MB) using sodium borohydride (SB) was analyzed using UV-vis spectroscopy. This study showed that the efficacy of mediated AgNPs in catalysing the reduction of MB.

Taylor dispersion in wind-driven current

NASA Astrophysics Data System (ADS)

Li, Gang; Wang, Ping; Jiang, Wei-Quan; Zeng, Li; Li, Zhi; Chen, G. Q.

2017-12-01

Taylor dispersion associated with wind-driven currents in channels, shallow lakes and estuaries is essential to hydrological environmental management. For solute dispersion in a wind-driven current, presented in this paper is an analytical study of the evolution of concentration distribution. The concentration moments are intensively derived for an accurate presentation of the mean concentration distribution, up to the effect of kurtosis. The vertical divergence of concentration is then deduced by Gill's method of series expansion up to the fourth order. Based on the temporal evolution of the vertical concentration distribution, the dispersion process in the wind-driven current is concretely characterized. The uniform shear leads to a special symmetrical distribution of mean concentration free of skewness. The non-uniformity of vertical concentration is caused by convection and smeared out gradually by the effect of diffusion, but fails to disappear even at large times.

Mass and heat transfer in crushed oil shale

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

Carley, J.F.; Ott, L.L.; Swecker, J.L.

1995-03-01

Studies of heat and mass transfer in packed beds, which disagree substantially in their findings, have nearly all been done with beds of regular particles of uniform size, whereas oil-shale retorting involves particles of diverse irregular shapes and sizes. The authors, in 349 runs, measured mass-transfer rates front naphthalene particles buried in packed beds by passing through air at room temperature. An exact catalog between convection of heat and mass makes it possible to infer heat-transfer coefficients from measured mass-transfer coefficients and fluid properties. Some beds consisted of spheres, naphthalene and inert, of the same, contrasting or distributed sizes. Inmore » some runs, naphthalene spheres were buried in beds of crushed shale, some in narrow screen ranges and others with a wide size range. In others, naphthalene lozenges of different shapes were buried in beds of crushed shale in various bed axis orientations. This technique permits calculation of the mass-transfer coefficient for each active particle in the bed rather than, as in most past studies, for the bed as a whole. The data are analyzed by the traditional correlation of Colburn j{sub D} vs. Reynolds number and by multiple regression of the mass-transfer coefficient on air rate, sizes of active and inert particles, void fraction, and temperature. Principal findings are: local Reynolds number should be based on the active-particle size, not the average for the whole bed; differences between shallow and deep beds are not appreciable; mass transfer is 26% faster for spheres and lozenges buried in shale than in all-sphere beds; orientation of lozenges in shale beds has little or no effect on mass-transfer rate; and for mass or heat transfer in shale beds, log(j{center_dot}{epsilon}) = {minus}0.0747 - 0.6344 log N{sub Re} + 0. 0592 log {sup 2} N{sub Re}.« less

Typomorphic Characteristics of Molybdenite from the Bystrinsky Cu-Au Porphyry-Skarn Deposit, Eastern Transbaikal Region, Russia

NASA Astrophysics Data System (ADS)

Kovalenker, V. A.; Trubkin, N. V.; Abramova, V. D.; Plotinskaya, O. Yu.; Kiseleva, G. D.; Borisovskii, S. E.; Yazykova, Yu. I.

2018-01-01

The paper presents pioneering data on the composition, texture, and crystal structure of molybdenite from various types of molybdenum mineralization at the Bystrinsky Cu-Au-Fe porphyry-skarn deposit in the eastern Transbaikal region, Russia. The data were obtained using electron microprobe analysis (EMPA), laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), and high-resolution transmission electron microscopy (HRTEM). Molybdenite found at the deposit in skarn, sulfide-poor quartz veins, and quartz-feldspar alteration markedly differs in the concentrations of trace elements determined by their species in the mineral, as well as in its structural features. Molybdenite-2H from skarn associated with phyllosilicates occurs as ultrafine crystals with uniform shape and texture; no dislocations or inclusions were found but amorphous silica was. The molybdenite composition is highly contrasting in the content and distribution of both structure-related (Re, W, and Se) and other (Mn, Co, Ni, Cu, Zn, As, Ag, Cd, Sb, Te, Ag, Pd, Au, Hg, Pb, and Bi) metals. In the sulfide-poor quartz veins, highly structurally heterogeneous (2H + 3R) molybdenite microcrystals with abundant defects (dislocations and volumetrically distributed inclusions) are associated with illite, goethite, and barite. Some single crystals are unique three-phase (2H + 3R polytypes + amorphous MoS2). The mineral has a low concentration of all trace elements, which are uniformly distributed. However, individual domains with uniquely high Pd, Te, Ni, Hg, and W concentrations caused by mineral inclusions are found in some grains. Molybdenite from quartz-feldspar alteration is characterized by low concentrations of all trace elements except for Re and Se, which enrich some domains of the grains. Our data indicate that the compositional and structural heterogeneity of molybdenite from the Bystrinsky deposit are its crucial features, which obviously correlate with the types of Mo mineralization.

Numerical Modeling of Fluid Flow in Solid Tumors

PubMed Central

Soltani, M.; Chen, P.

2011-01-01

A mathematical model of interstitial fluid flow is developed, based on the application of the governing equations for fluid flow, i.e., the conservation laws for mass and momentum, to physiological systems containing solid tumors. The discretized form of the governing equations, with appropriate boundary conditions, is developed for a predefined tumor geometry. The interstitial fluid pressure and velocity are calculated using a numerical method, element based finite volume. Simulations of interstitial fluid transport in a homogeneous solid tumor demonstrate that, in a uniformly perfused tumor, i.e., one with no necrotic region, because of the interstitial pressure distribution, the distribution of drug particles is non-uniform. Pressure distribution for different values of necrotic radii is examined and two new parameters, the critical tumor radius and critical necrotic radius, are defined. Simulation results show that: 1) tumor radii have a critical size. Below this size, the maximum interstitial fluid pressure is less than what is generally considered to be effective pressure (a parameter determined by vascular pressure, plasma osmotic pressure, and interstitial osmotic pressure). Above this size, the maximum interstitial fluid pressure is equal to effective pressure. As a consequence, drugs transport to the center of smaller tumors is much easier than transport to the center of a tumor whose radius is greater than the critical tumor radius; 2) there is a critical necrotic radius, below which the interstitial fluid pressure at the tumor center is at its maximum value. If the tumor radius is greater than the critical tumor radius, this maximum pressure is equal to effective pressure. Above this critical necrotic radius, the interstitial fluid pressure at the tumor center is below effective pressure. In specific ranges of these critical sizes, drug amount and therefore therapeutic effects are higher because the opposing force, interstitial fluid pressure, is low in these ranges. PMID:21673952

rpSPH: a novel smoothed particle hydrodynamics algorithm

NASA Astrophysics Data System (ADS)

Abel, Tom

2011-05-01

We suggest a novel discretization of the momentum equation for smoothed particle hydrodynamics (SPH) and show that it significantly improves the accuracy of the obtained solutions. Our new formulation which we refer to as relative pressure SPH, rpSPH, evaluates the pressure force with respect to the local pressure. It respects Newton's first law of motion and applies forces to particles only when there is a net force acting upon them. This is in contrast to standard SPH which explicitly uses Newton's third law of motion continuously applying equal but opposite forces between particles. rpSPH does not show the unphysical particle noise, the clumping or banding instability, unphysical surface tension and unphysical scattering of different mass particles found for standard SPH. At the same time, it uses fewer computational operations and only changes a single line in existing SPH codes. We demonstrate its performance on isobaric uniform density distributions, uniform density shearing flows, the Kelvin-Helmholtz and Rayleigh-Taylor instabilities, the Sod shock tube, the Sedov-Taylor blast wave and a cosmological integration of the Santa Barbara galaxy cluster formation test. rpSPH is an improvement in these cases. The improvements come at the cost of giving up exact momentum conservation of the scheme. Consequently, one can also obtain unphysical solutions particularly at low resolutions.

Enhanced Catalytic Activities of NiPt Truncated Octahedral Nanoparticles toward Ethylene Glycol Oxidation and Oxygen Reduction in Alkaline Electrolyte.

PubMed

Xia, Tianyu; Liu, Jialong; Wang, Shouguo; Wang, Chao; Sun, Young; Gu, Lin; Wang, Rongming

2016-05-04

The high cost and poor durability of Pt nanoparticles (NPs) are great limits for the proton exchange membrane fuel cells (PEMFCs) from being scaled-up for commercial applications. Pt-based bimetallic NPs together with a uniform distribution can effectively reduce the usage of expensive Pt while increasing poison resistance of intermediates. In this work, a simple one-pot method was used to successfully synthesize ultrafine (about 7.5 nm) uniform NiPt truncated octahedral nanoparticles (TONPs) in dimethylformamid (DMF) without any seeds or templates. The as-prepared NiPt TONPs with Pt-rich surfaces exhibit greatly improved catalytic activities together with good tolerance and better stability for ethylene glycol oxidation reaction (EGOR) and oxygen reduction reaction (ORR) in comparison with NiPt NPs and commercial Pt/C catalysts in alkaline electrolyte. For example, the value of mass and specific activities for EGOR are 23.2 and 17.6 times higher comparing with those of commercial Pt/C, respectively. Our results demonstrate that the dramatic enhancement is mainly attributed to Pt-rich surface, larger specific surface area, together with coupling between Ni and Pt atoms. This developed method provides a promising pathway for simple preparation of highly efficient electrocatalysts for PEMFCs in the near future.

Effects of gravity on sheared and nonsheared turbulent nonpremixed flames

NASA Technical Reports Server (NTRS)

Elghobashi, Said; Lee, Yong-Yao; Zhong, Rongbin

1995-01-01

The present numerical study is concerned with the fundamental physics of the multiway interaction between turbulence, chemical reaction, and buoyancy in a nonpremixed flame. The method of direct numerical simulation (DNS) is used to solve the instantaneous, three-dimensional governing equations. Because of the present supercomputer limitations, we consider two simple flow geometries, namely an initially uniform flow without shear (equivalent to grid-generated turbulence) and an initially uniform shear flow. In each flow, the fuel and oxidant initially exist as two separate streams. As the reactants mix, chemical reaction takes place and exothermic energy is released causing variations in density. In the presence of a gravity field, the spatial and temporal distributions of the induced buoyancy forces depend on the local density gradients and the direction of the gravitational acceleration. The effects of buoyancy include the generation of local shear, baroclinic production or destruction of vorticity, and countergradient heat and mass transport. Increased vorticity and small-scale turbulence promote further mixing and reaction. However, if the strain-rates become too high, local flame extinction can occur. Our objective is to gain an understanding of the complex interactions between the physical phenomena involved, with particular attention to the effects of buoyancy on the turbulence structure, flame behavior, and factors influencing flame extinction.

Capillary suspensions as beneficial formulation concept for high energy density Li-ion battery electrodes

NASA Astrophysics Data System (ADS)

Bitsch, Boris; Gallasch, Tobias; Schroeder, Melanie; Börner, Markus; Winter, Martin; Willenbacher, Norbert

2016-10-01

We introduce a novel formulation concept to prepare high capacity graphite electrodes for lithium ion batteries. The concept is based on the capillary suspension phenomenon: graphite and conductive agent are dispersed in an aqueous binder solution and the organic solvent octanol is added as immiscible, secondary fluid providing the formation of a sample-spanning network resulting in unique stability and coating properties. No additional processing steps compared to conventional slurry preparation are required. The resulting ultra-thick electrodes comprise mass loadings of about 16.5 mg cm-2, uniform layer thickness, and superior edge contours. The adjustment of mechanical energy input ensures uniform distribution of the conductive agent and sufficient electronic conductivity of the final dry composite electrode. The resulting pore structure is due to the stable network provided by the secondary fluid which evaporates residue-free during drying. Constant current-constant potential (CC-CP) cycling clearly indicates that the corresponding microstructure significantly improves the kinetics of reversible Li+ (de-) intercalation. A double layer electrode combining a conventionally prepared layer coated directly onto the Cu current collector with an upper layer stabilized with octanol was prepared applying wet-on-wet coating. CC-CP cycling data confirms that staged porosity within the electrode cross section results in superior electrochemical performance.

FAIMS Operation for Realistic Gas Flow Profile and Asymmetric Waveforms Including Electronic Noise and Ripple

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

Shvartsburg, Alexandre A.; Tang, Keqi; Smith, Richard D.

The use of Field Asymmetric waveform Ion Mobility Spectrometry (FAIMS) has rapidly grown with the advent of commercial FAIMS systems coupled to mass spectrometry. However, many fundamental aspects of FAIMS remain obscure, hindering its technological improvement and expansion of analytical utility. Recently, we developed a comprehensive numerical simulation approach to FAIMS that can handle any device geometry and operational conditions. The formalism was originally set up in one dimension for a uniform gas flow and limited to ideal asymmetric voltage waveforms. Here we extend the model to account for a realistic gas flow velocity distribution in the analytical gap, axialmore » ion diffusion, and waveform imperfections (e.g. noise and ripple). The non-uniformity of gas flow velocity profile has only a minor effect, slightly improving resolution. However, waveform perturbations are significant even at very low levels, in some cases {approx} 0.01% of nominal voltage. These perturbations always improve resolution and decrease sensitivity. Variation of noise or ripple amplitude produces a trade-off between resolution and sensitivity. This trade-off is physically equivalent to that obtained via adjustment of the gap width and/or asymmetric waveform frequency, but the scaling of low-frequency ripple appears to be a more practical way to control FAIMS resolution.« less

White matter hyperintensities on MRI in high-altitude U-2 pilots.

PubMed

McGuire, Stephen; Sherman, Paul; Profenna, Leonardo; Grogan, Patrick; Sladky, John; Brown, Anthony; Robinson, Andrew; Rowland, Laura; Hong, Elliot; Patel, Beenish; Tate, David; Kawano, Elaine S; Fox, Peter; Kochunov, Peter

2013-08-20

To demonstrate that U-2 pilot occupational exposure to hypobaria leads to increased incidence of white matter hyperintensities (WMH) with a more uniform distribution throughout the brain irrespective of clinical neurologic decompression sickness history. We evaluated imaging findings in 102 U-2 pilots and 91 controls matched for age, health, and education levels. Three-dimensional, T2-weighted, high-resolution (1-mm isotropic) imaging data were collected using fluid-attenuated inversion recovery sequence on a 3-tesla MRI scanner. Whole-brain and regional WMH volume and number were compared between groups using a 2-tailed Wilcoxon rank sum test. U-2 pilots demonstrated an increase in volume (394%; p = 0.004) and number (295%; p < 0.001) of WMH. Analysis of regional distribution demonstrated WMH more uniformly distributed throughout the brain in U-2 pilots compared with mainly frontal distribution in controls. Pilots with occupational exposure to hypobaria showed a significant increase in WMH lesion volume and number. Unlike the healthy controls with predominantly WMH in the frontal white matter, WMH in pilots were more uniformly distributed throughout the brain. This is consistent with our hypothesized pattern of damage produced by interaction between microemboli and cerebral tissue, leading to thrombosis, coagulation, inflammation, and/or activation of innate immune response, although further studies will be necessary to clarify the pathologic mechanisms responsible.

White matter hyperintensities on MRI in high-altitude U-2 pilots

PubMed Central

Sherman, Paul; Profenna, Leonardo; Grogan, Patrick; Sladky, John; Brown, Anthony; Robinson, Andrew; Rowland, Laura; Hong, Elliot; Patel, Beenish; Tate, David; Kawano, Elaine S.; Fox, Peter; Kochunov, Peter

2013-01-01

Objective: To demonstrate that U-2 pilot occupational exposure to hypobaria leads to increased incidence of white matter hyperintensities (WMH) with a more uniform distribution throughout the brain irrespective of clinical neurologic decompression sickness history. Methods: We evaluated imaging findings in 102 U-2 pilots and 91 controls matched for age, health, and education levels. Three-dimensional, T2-weighted, high-resolution (1-mm isotropic) imaging data were collected using fluid-attenuated inversion recovery sequence on a 3-tesla MRI scanner. Whole-brain and regional WMH volume and number were compared between groups using a 2-tailed Wilcoxon rank sum test. Results: U-2 pilots demonstrated an increase in volume (394%; p = 0.004) and number (295%; p < 0.001) of WMH. Analysis of regional distribution demonstrated WMH more uniformly distributed throughout the brain in U-2 pilots compared with mainly frontal distribution in controls. Conclusion: Pilots with occupational exposure to hypobaria showed a significant increase in WMH lesion volume and number. Unlike the healthy controls with predominantly WMH in the frontal white matter, WMH in pilots were more uniformly distributed throughout the brain. This is consistent with our hypothesized pattern of damage produced by interaction between microemboli and cerebral tissue, leading to thrombosis, coagulation, inflammation, and/or activation of innate immune response, although further studies will be necessary to clarify the pathologic mechanisms responsible. PMID:23960192

Project FARE Task IV Report: Urban Mass Transportation Industry Financial and Operating Data Reporting System. Volume I. Task and Project Summary.

DOT National Transportation Integrated Search

1973-11-01

The report contains a description of the uniform reporting system for the urban mass transit industry designed and tested in Project FARE. It is presented in five volumes. Volume I contains a description of how Task IV was accomplished and the conclu...

Project FARE task II report : urban mass transportation industry survey of reporting capability : interim task II report for July-November 1972 period

DOT National Transportation Integrated Search

1972-11-01

Report contains a description of the work done to evaluate the capability of the urban mass transit industry to report financial and operating data through a uniform reporting system. Techniques used in the evaluation included a questionnaire survey ...

Diagnosing Trouble Spots Caused by an Irrigation System

Treesearch

John R. Scholtes

2002-01-01

I discuss a testing procedure to determine the water distribution pattern of a sprinkler irrigation system and steps that may be taken to improve uniformity of application. All irrigation systems require testing and maintenance to assure that water application is as uniform as possible. Even new systems installed to a manufacturer's specifications should be "...

Analyses of the Impact of School Uniforms on Violence in North Carolina Public High Schools

ERIC Educational Resources Information Center

Johnson, Wesley Scott

2010-01-01

This study incorporated a multiple-methods design utilizing both quantitative and qualitative data. The quantitative portion investigated several annual reports distributed by the North Carolina Department of Public Instruction (NCDPI) to explore the impact of school uniform policies on incidents of crime and violence and occurrences of…

Beam uniformity of flat top lasers

NASA Astrophysics Data System (ADS)

Chang, Chao; Cramer, Larry; Danielson, Don; Norby, James

2015-03-01

Many beams that output from standard commercial lasers are multi-mode, with each mode having a different shape and width. They show an overall non-homogeneous energy distribution across the spot size. There may be satellite structures, halos and other deviations from beam uniformity. However, many scientific, industrial and medical applications require flat top spatial energy distribution, high uniformity in the plateau region, and complete absence of hot spots. Reliable standard methods for the evaluation of beam quality are of great importance. Standard methods are required for correct characterization of the laser for its intended application and for tight quality control in laser manufacturing. The International Organization for Standardization (ISO) has published standard procedures and definitions for this purpose. These procedures have not been widely adopted by commercial laser manufacturers. This is due to the fact that they are unreliable because an unrepresentative single-pixel value can seriously distort the result. We hereby propose a metric of beam uniformity, a way of beam profile visualization, procedures to automatically detect hot spots and beam structures, and application examples in our high energy laser production.

The Corrosion Characteristics and Tensile Behavior of Reinforcement under Coupled Carbonation and Static Loading

PubMed Central

Xu, Yidong

2015-01-01

This paper describes the non-uniform corrosion characteristics and mechanical properties of reinforcement under coupled action of carbonation and static loading. The two parameters, namely area-box (AB) value and arithmetical mean deviation (Ra), are adopted to characterize the corrosion morphology and pitting distribution from experimental observations. The results show that the static loading affects the corrosion characteristics of reinforcement. Local stress concentration in corroded reinforcement caused by tensile stress drives the corrosion pit pattern to be more irregular. The orthogonal test results from finite element simulations show that pit shape and pit depth are the two significant factors affecting the tensile behavior of reinforcement. Under the condition of similar corrosion mass loss ratio, the maximum plastic strain of corroded reinforcement increases with the increase of Ra and load time-history significantly. PMID:28793729

Worldwide data sets constrain the water vapor uptake coefficient in cloud formation

PubMed Central

Raatikainen, Tomi; Nenes, Athanasios; Seinfeld, John H.; Morales, Ricardo; Moore, Richard H.; Lathem, Terry L.; Lance, Sara; Padró, Luz T.; Lin, Jack J.; Cerully, Kate M.; Bougiatioti, Aikaterini; Cozic, Julie; Ruehl, Christopher R.; Chuang, Patrick Y.; Anderson, Bruce E.; Flagan, Richard C.; Jonsson, Haflidi; Mihalopoulos, Nikos; Smith, James N.

2013-01-01

Cloud droplet formation depends on the condensation of water vapor on ambient aerosols, the rate of which is strongly affected by the kinetics of water uptake as expressed by the condensation (or mass accommodation) coefficient, αc. Estimates of αc for droplet growth from activation of ambient particles vary considerably and represent a critical source of uncertainty in estimates of global cloud droplet distributions and the aerosol indirect forcing of climate. We present an analysis of 10 globally relevant data sets of cloud condensation nuclei to constrain the value of αc for ambient aerosol. We find that rapid activation kinetics (αc > 0.1) is uniformly prevalent. This finding resolves a long-standing issue in cloud physics, as the uncertainty in water vapor accommodation on droplets is considerably less than previously thought. PMID:23431189

Worldwide data sets constrain the water vapor uptake coefficient in cloud formation.

PubMed

Raatikainen, Tomi; Nenes, Athanasios; Seinfeld, John H; Morales, Ricardo; Moore, Richard H; Lathem, Terry L; Lance, Sara; Padró, Luz T; Lin, Jack J; Cerully, Kate M; Bougiatioti, Aikaterini; Cozic, Julie; Ruehl, Christopher R; Chuang, Patrick Y; Anderson, Bruce E; Flagan, Richard C; Jonsson, Haflidi; Mihalopoulos, Nikos; Smith, James N

2013-03-05

Cloud droplet formation depends on the condensation of water vapor on ambient aerosols, the rate of which is strongly affected by the kinetics of water uptake as expressed by the condensation (or mass accommodation) coefficient, αc. Estimates of αc for droplet growth from activation of ambient particles vary considerably and represent a critical source of uncertainty in estimates of global cloud droplet distributions and the aerosol indirect forcing of climate. We present an analysis of 10 globally relevant data sets of cloud condensation nuclei to constrain the value of αc for ambient aerosol. We find that rapid activation kinetics (αc > 0.1) is uniformly prevalent. This finding resolves a long-standing issue in cloud physics, as the uncertainty in water vapor accommodation on droplets is considerably less than previously thought.

Cell-Culture Reactor Having a Porous Organic Polymer Membrane

NASA Technical Reports Server (NTRS)

Koontz, Steven L. (Inventor)

2000-01-01

A method for making a biocompatible polymer article using a uniform atomic oxygen treatment is disclosed. The substrate may be subsequently optionally grated with a compatibilizing compound. Compatibilizing compounds may include proteins, phosphory1choline groups, platelet adhesion preventing polymers, albumin adhesion promoters, and the like. The compatibilized substrate may also have a living cell layer adhered thereto. The atomic oxygen is preferably produced by a flowing afterglow microwave discharge, wherein the substrate resides in a sidearm out of the plasma. Also, methods for culturing cells for various purposes using the various membranes are disclosed as well. Also disclosed are porous organic polymers having a distributed pore chemistry (DPC) comprising hydrophilic and hydrophobic regions, and a method for making the DPC by exposing the polymer to atomic oxygen wherein the rate of hydrophilization is greater than the rate of mass loss.

Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

DOE PAGES

Aab, A.; Abreu, P.; Aglietta, M.; ...

2017-04-20

In this paper, we present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed for energies above 5 • 10 18 eV, i.e. the region of the all-particle spectrum above the so-called 'ankle' feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated through a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies, hard spectra and heavy chemical composition. We also show thatmore » uncertainties about physical quantities relevant to UHECR propagation and shower development have a non-negligible impact on the fit results.« less

Combined fit of spectrum and composition data as measured by the Pierre Auger Observatory

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

Aab, A.; Abreu, P.; Aglietta, M.

In this paper, we present a combined fit of a simple astrophysical model of UHECR sources to both the energy spectrum and mass composition data measured by the Pierre Auger Observatory. The fit has been performed for energies above 5 • 10 18 eV, i.e. the region of the all-particle spectrum above the so-called 'ankle' feature. The astrophysical model we adopted consists of identical sources uniformly distributed in a comoving volume, where nuclei are accelerated through a rigidity-dependent mechanism. The fit results suggest sources characterized by relatively low maximum injection energies, hard spectra and heavy chemical composition. We also show thatmore » uncertainties about physical quantities relevant to UHECR propagation and shower development have a non-negligible impact on the fit results.« less

Peano-like paths for subaperture polishing of optical aspherical surfaces.

PubMed

Tam, Hon-Yuen; Cheng, Haobo; Dong, Zhichao

2013-05-20

Polishing can be more uniform if the polishing path provides uniform coverage of the surface. It is known that Peano paths can provide uniform coverage of planar surfaces. Peano paths also contain short path segments and turns: (1) all path segments have the same length, (2) path segments are mutually orthogonal at the turns, and (3) path segments and turns are uniformity distributed over the domain surface. These make Peano paths an attractive candidate among polishing tool paths because they enhance multidirectional approaches of the tool to each surface location. A method for constructing Peano paths for uniform coverage of aspherical surfaces is proposed in this paper. When mapped to the aspherical surface, the path also contains short path segments and turns, and the above attributes are approximately preserved. Attention is paid so that the path segments are still well distributed near the vertex of the surface. The proposed tool path was used in the polishing of a number of parabolic BK7 specimens using magnetorheological finishing (MRF) and pitch with cerium oxide. The results were rather good for optical lenses and confirm that a Peano-like path was useful for polishing, for MRF, and for pitch polishing. In the latter case, the surface roughness achieved was 0.91 nm according to WYKO measurement.