Indian Academy of Sciences (India)
V C Petwal; J N Rao; Jishnu Dwivedi; V K Senecha; K V Subbaiah
2010-03-01
A prototype pulsed electron beam irradiation facility for radiation processing of food and medical products is being commissioned at our centre in Indore, India. Analysis of surface dose and uniformity for a pulsed beam facility is of crucial importance because it is influenced by various operating parameters such as beam current, pulse repetition rate (PRR), scanning current profile and frequency, scanning width and product conveying speed. A large number of experiments are required to determine the harmonized setting of these operating parameters for achieving uniform dose. Since there is no readily available tool to set these parameters, use of Monte Carlo methods and computational tools can prove to be the most viable and time saving technique to support the assessment of the dose distribution. In the present study, Monte Carlo code, MCNP, is used to simulate the transport of 10 MeV electron beam through various mediums coming into the beam path and generate an equivalent dose profile in a polystyrene phantom for stationary state. These results have been verified with experimentally measured dose profile, showing that results are in good agreement within 4%. The Monte Carlo simulation further has been used to optimize the overlapping between the successive pulses of a scan to achieve ± 5% dose uniformity along the scanning direction. A mathematical model, which uses the stationary state data, is developed to include the effect of conveyor speed. The algorithm of the model is discussed and the results are compared with the experimentally measured values, which show that the agreement is better than 15%. Finally, harmonized setting for operating parameters of the accelerator are derived to deliver uniform surface dose in the range of 1–13 kGy/pass.
Deposition uniformity inspection in IC wafer surface
Li, W. C.; Lin, Y. T.; Jeng, J. J.; Chang, C. L.
2014-03-01
This paper focuses on the task of automatic visual inspection of color uniformity on the surface of integrated circuits (IC) wafers arising from the layering process. The oxide thickness uniformity within a given wafer with a desired target thickness is of great importance for modern semiconductor circuits with small oxide thickness. The non-uniform chemical vapor deposition (CVD) on a wafer surface will proceed to fail testing in Wafer Acceptance Test (WAT). Early detection of non-uniform deposition in a wafer surface can reduce material waste and improve production yields. The fastest and most low-priced inspection method is a machine vision-based inspection system. In this paper, the proposed visual inspection system is based on the color representations which were reflected from wafer surface. The regions of non-uniform deposition present different colors from the uniform background in a wafer surface. The proposed inspection technique first learns the color data via color space transformation from uniform deposition of normal wafer surfaces. The individual small region statistical comparison scheme then proceeds to the testing wafers. Experimental results show that the proposed method can effectively detect the non-uniform deposition regions on the wafer surface. The inspection time of the deposited wafers is quite compatible with the atmospheric pressure CVD time.
Controlled uniform coating from the interplay of Marangoni flows and surface-adsorbed macromolecules
Kim, Hyoungsoo; Um, Eujin; Jacobi, Ian; Button, Ernie; Stone, Howard A
2016-01-01
Surface coatings and patterning technologies are essential for various physicochemical applications. In this Letter, we describe key parameters to achieve uniform particle coatings in binary solutions: First, multiple sequential Marangoni flows, set by solute and surfactant simultaneously, prevent non-uniform particle distributions and continuously mix suspended materials during droplet evaporation. Second, we show the importance of particle-surface interactions that can be established by surface-adsorbed macromolecules. To achieve a uniform deposit in a binary mixture a small concentration of surfactant and surface-adsorbed polymer (0.05 wt% each) is sufficient, which offers a new physicochemical avenue for control of coatings.
The Relationship of School Uniforms to Student Attendance, Achievement, and Discipline
Sowell, Russell Edward
2012-01-01
This causal-comparative study examined the relationship of school uniforms to attendance, academic achievement, and discipline referral rates, using data collected from two high schools in rural southwest Georgia county school systems, one with a uniforms program and one without a uniforms program. After accounting for race and students with…
Dressed for Success: Do School Uniforms Improve Student Behavior, Attendance, and Achievement?
Scott Imberman; Elisabetta Gentile
2009-01-01
Concerns about safety in urban schools has led many school districts to require uniforms for their students. However, we know very little about what impact school uniforms have had on the educational environment. In this paper we use a unique dataset to assess how uniform adoption affects student achievement and behavior in a large urban school district in the southwest. Since each school in the district could decide independently about whether or not to adopt uniforms, we are able to use var...
Ward, Ella Porter
1999-01-01
One of the many attempts to solve problems that plague America's schools is the implementation of uniform dress code policies. Those who favor uniforms contend that uniforms will increase attendance, enhance academic achievement, and improve classroom environment. Prior research studies ( Behling, 1991; Hughes, 1996; and Hoffler-Riddick, 1998) on the effects of mandatory school uniforms have been inconclusive in their findings. The purpose of this study was to examine the impact of mandatory...
Dressed for Success? The Effect of School Uniforms on Student Achievement and Behavior
Elisabetta Gentile; Imberman, Scott A.
2011-01-01
Uniform use in public schools is rising, but we know little about how they affect students. Using a unique dataset from a large urban school district in the southwest United States, we assess how uniforms affect behavior, achievement and other outcomes. Each school in the district determines adoption independently, providing variation over schools and time. By including student and school fixed-effects we find evidence that uniform adoption improves attendance in secondary grades, while in el...
Brunsma, David L.; Rockquemore, Kerry A.
1998-01-01
Examined 10th-grade data from the 1988 National Educational Longitudinal Study to investigate the effects of school uniforms on student attendance, behavior problems, substance use, and academic achievement. Data from public, private, and Catholic schools indicated that uniforms had no direct effect on substance use, attendance, or behavior, and a…
Precise evaluation of uniform Doo-Sabin surfaces
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Using eigenanalysis of uniform Doo-Sabin subdivision surfaces, parameterization approaches for two types of Doo-Sabin subdivision surfaces are developed, and evaluation methods for values and derivatives of Doo-Sabin surfaces at arbitrary parameters are presented by means of non-iterative approaches. Generalized basis functions for Doo-Sabin surfaces are also derived. Thus, the prejudice is disproved further that subdivision surfaces cannot be evaluated precisely.
Uniform algal growth in photobioreactors using surface scatterers
Ahsan, Syed S.; Pereyra, Brandon; Erickson, David
2014-03-01
Cultures of algae, such as cyanobacteria, are a promising source of renewable energy. However, algal growth is highly dependent on light intensity and standard photobioreactors do a poor job of distributing light uniformly for algal utilization due to shading effects in dense algal cultures. Engineered scattering schemes are already employed in current slab-waveguide technologies, like edge-lit LEDs. Stacking such slab-waveguides that uniformly distribute light could potentially yield photobioreactors to overcome the shading effect and grow extremely high densities of algal cultures that would lower monetary and energetic costs. Here, we characterize and design a scattering scheme for specific application within photobioreactors which employs a gradient distribution of surface scatterers with uniform lateral scattering intensity. This uniform scattering scheme is shown to be superior for algal cultivation.
Continuity of non-uniform recursive subdivision surfaces
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Since Doo-Sabin and Catmull-Clark surfaces were proposed in 1978, eigenstructure, convergence and continuity analyses of stationary subdivision have been performed very well, but it has been very difficult to prove the convergence and continuity of non-uniform recursive subdivision surfaces (NURSSes, for short) of arbitrary topology. In fact, so far a problem whether or not there exists the limit surface as well as G1 continuity of a non-uniform Catmull-Clark subdivision has not been solved yet. Here the concept of equivalent knot spacing is introduced. A new technique for eigenanalysis, convergence and continuity analyses of non-uniform Catmull-Clark surfaces is proposed such that the convergence and G1 continuity of NURSSes at extraordinary points are proved. In addition, slightly improved rules for NURSSes are developed. This offers us one more alternative for modeling free-form surfaces of arbitrary topologies with geometric features such as cusps, sharp edges, creases and darts, while elsewhere maintaining the same order of continuity as B-spline surfaces.
Continuity of non-uniform recursive subdivision surfaces
Institute of Scientific and Technical Information of China (English)
秦开怀; 王华维
2000-01-01
Since Doo-Sabin and Catmull-Clark surfaces were proposed in 1978, eigenstructure, convergence and continuity analyses of stationary subdivision have been performed very well, but it has been very difficult to prove the convergence and continuity of non-uniform recursive subdivision surfaces (NURSSes, for short) of arbitrary topology. In fact, so far a problem whether or not there exists the limit surface as well as G1 continuity of a non-uniform Catmull-Clark subdivision has not been solved yet. Here the concept of equivalent knot spacing is introduced. A new technique for eigenanaly-sis, convergence and continuity analyses of non-uniform Catmull-Clark surfaces is proposed such that the convergence and G1 continuity of NURSSes at extraordinary points are proved. In addition, slightly improved rules for NURSSes are developed. This offers us one more alternative for modeling free-form surfaces of arbitrary topologies with geometric features such as cusps, sharp edges, creases and darts, while elsewhere ma
Line printing solution-processable small molecules with uniform surface profile via ink-jet printer.
Liu, Huimin; Xu, Wei; Tan, Wanyi; Zhu, Xuhui; Wang, Jian; Peng, Junbiao; Cao, Yong
2016-03-01
Line printing offers a feasible approach to remove the pixel well structure which is widely used to confine the ink-jet printed solution. In the study, a uniform line is printed by an ink-jet printer. To achieve a uniform surface profile of the printed line, 10vol% low-volatile solvent DMA (3,4-Dimethylanisole) is mixed with high-volatile solvent Pxy (p-xylene) as the solvent. After a solution-processable small molecule is dissolved, the surface tension of DMA solution becomes lower than that of Pxy solution, which creates an inward Marangoni flow during the solvent evaporation. The inward Marangoni flow balances out the outward capillary flow, thereby forming a flat film surface. The line width of the printed line depends on the contact angle of the solution on the hole injection layer.
Gentile, Elisabetta; Imberman, Scott A.
2011-01-01
Uniform use in public schools is rising, but we know little about how they affect students. Using a unique dataset from a large urban school district in the southwest United States, we assess how uniforms affect behavior, achievement and other outcomes. Each school in the district determines adoption independently, providing variation over schools…
High-voltage electrode optimization towards uniform surface treatment by a pulsed volume discharge
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.
Energy Technology Data Exchange (ETDEWEB)
Coppe, Jean-Philippe [Kinogea Inc., 2168 Shattuck Ave, Berkeley, CA 94704 (United States); Xu Zhida; Chen Yi; Logan Liu, G, E-mail: loganliu@illinois.edu [Micro and Nanotechnology Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL (United States)
2011-06-17
Molecular probe arrays printed on solid surfaces such as DNA, peptide, and protein microarrays are widely used in chemical and biomedical applications especially genomic and proteomic studies (Pollack et al 1999 Nat. Genet. 23 41-6, Houseman et al 2002 Nat. Biotechnol. 20 270-4, Sauer et al 2005 Nat. Rev. Genet. 6 465-76) as well as surface imaging and spectroscopy (Mori et al 2008 Anal. Biochem. 375 223-31, Liu et al 2006 Nat. Nanotechnol. 1 47-52, Liu 2010 IEEE J. Sel. Top. Quantum Electron. 16 662-71). Unfortunately the printed molecular spots on solid surfaces often suffer low distribution uniformity due to the lingering 'coffee stain' (Deegan et al 1997 Nature 389 827-9) problem of molecular accumulations and blotches, especially around the edge of deposition spots caused by solvent evaporation and convection processes. Here we present, without any surface chemistry modification, a unique solid surface of high-aspect-ratio silver-coated silicon nanocone arrays that allows highly uniform molecular deposition and thus subsequent uniform optical imaging and spectroscopic molecular detection. Both fluorescent Rhodamine dye molecules and unlabeled oligopeptides are printed on the metallic nanocone photonic substrate surface as circular spot arrays. In comparison with the printed results on ordinary glass slides and silver-coated glass slides, not only high printing density but uniform molecular distribution in every deposited spot is achieved. The high-uniformity and repeatability of molecular depositions on the 'coffee stain'-free nanocone surface is confirmed by laser scanning fluorescence imaging and surface enhanced Raman imaging experiments. The physical mechanism for the uniform molecular deposition is attributed to the superhydrophobicity and localized pinned liquid-solid-air interface on the silver-coated silicon nanocone surface. The unique surface properties of the presented nanocone surface enabled high-density, high-uniformity probe
Coppé, Jean-Philippe; Xu, Zhida; Chen, Yi; Logan Liu, G.
2011-06-01
Molecular probe arrays printed on solid surfaces such as DNA, peptide, and protein microarrays are widely used in chemical and biomedical applications especially genomic and proteomic studies (Pollack et al 1999 Nat. Genet. 23 41-6, Houseman et al 2002 Nat. Biotechnol. 20 270-4, Sauer et al 2005 Nat. Rev. Genet. 6 465-76) as well as surface imaging and spectroscopy (Mori et al 2008 Anal. Biochem. 375 223-31, Liu et al 2006 Nat. Nanotechnol. 1 47-52, Liu 2010 IEEE J. Sel. Top. Quantum Electron. 16 662-71). Unfortunately the printed molecular spots on solid surfaces often suffer low distribution uniformity due to the lingering 'coffee stain' (Deegan et al 1997 Nature 389 827-9) problem of molecular accumulations and blotches, especially around the edge of deposition spots caused by solvent evaporation and convection processes. Here we present, without any surface chemistry modification, a unique solid surface of high-aspect-ratio silver-coated silicon nanocone arrays that allows highly uniform molecular deposition and thus subsequent uniform optical imaging and spectroscopic molecular detection. Both fluorescent Rhodamine dye molecules and unlabeled oligopeptides are printed on the metallic nanocone photonic substrate surface as circular spot arrays. In comparison with the printed results on ordinary glass slides and silver-coated glass slides, not only high printing density but uniform molecular distribution in every deposited spot is achieved. The high-uniformity and repeatability of molecular depositions on the 'coffee stain'-free nanocone surface is confirmed by laser scanning fluorescence imaging and surface enhanced Raman imaging experiments. The physical mechanism for the uniform molecular deposition is attributed to the superhydrophobicity and localized pinned liquid-solid-air interface on the silver-coated silicon nanocone surface. The unique surface properties of the presented nanocone surface enabled high-density, high-uniformity probe spotting beneficial
Liu, Yichao; He, Sailing; Ma, Yungui
2014-01-01
Extended from its electromagnetic counterpart, transformation thermodynamics applied to thermal conduction equations can map a virtual geometry into a physical thermal medium, realizing the manipulation of heat flux with almost arbitrarily desired diffusion paths, which provides unprecedented opportunities to create thermal devices unconceivable or deemed impossible before. In this work we employ this technique to design an efficient plate heater that can transiently achieve a large surface of uniform temperature powered by a small thermal source. As opposed to the traditional approach of relying on the deployment of a resistor network, our approach fully takes advantage of an advanced functional material system to guide the heat flux to achieve the desired temperature heating profile. A different set of material parameters for the transformed device has been developed, offering the parametric freedom for practical applications. As a proof of concept, the proposed devices are implemented with engineered therm...
Shi, Donglu; Wang, S. X.; van Ooij, Wim J.; Wang, L. M.; Zhao, Jiangang; Yu, Zhou
2001-02-01
Surface modification of nanoparticles will present great challenges due to their extremely small dimensions, high surface areas, and high surface energies. In this research, we demonstrate the uniform deposition of ultrathin polymer films of 2 nm on the surfaces of alumina nanoparticles. The deposited film can also be tailored to multilayers. Time-of-flight secondary ion mass spectroscopy was used to confirm the pyrrole thin film on the nanoparticle surfaces. Using such a nanocoating, it is possible to alter the intrinsic properties of materials that cannot be achieved by conventional methods and materials.
Tian, Chao; Chen, Jia; Zhang, Bo; Shan, Lianqiang; Zhou, Weimin; Liu, Dongxiao; Bi, Bi; Zhang, Feng; Wang, Weiwu; Zhang, Baohan; Gu, Yuqiu
2015-05-01
The uniformity of the compression driver is of fundamental importance for inertial confinement fusion (ICF). In this paper, the illumination uniformity on a spherical capsule during the initial imprinting phase directly driven by laser beams has been considered. We aim to explore methods to achieve high direct drive illumination uniformity on laser facilities designed for indirect drive ICF. There are many parameters that would affect the irradiation uniformity, such as Polar Direct Drive displacement quantity, capsule radius, laser spot size and intensity distribution within a laser beam. A novel approach to reduce the root mean square illumination non-uniformity based on multi-parameter optimizing approach (particle swarm optimization) is proposed, which enables us to obtain a set of optimal parameters over a large parameter space. Finally, this method is applied to improve the direct drive illumination uniformity provided by Shenguang III laser facility and the illumination non-uniformity is reduced from 5.62% to 0.23% for perfectly balanced beams. Moreover, beam errors (power imbalance and pointing error) are taken into account to provide a more practical solution and results show that this multi-parameter optimization approach is effective. PMID:25969321
Impact of non-uniform surface magnetic fields on stellar winds
Holzwarth, V R
2005-01-01
Observations of active stars reveal highly non-uniform surface distributions of magnetic flux. Theoretical models considering magnetised stellar winds however often presume uniform surface magnetic fields, characterised by a single magnetic field strength. The present work investigates the impact of non-uniform surface magnetic field distributions on the stellar mass and angular momentum loss rates. The approach of Weber & Davis (1967) is extended to non-equatorial latitudes to quantify the impact of latitude-dependent magnetic field distributions over a large range of stellar rotation rates and thermal wind properties. The analytically prescribed field patterns are dominated by magnetic flux concentrations at intermediate and high latitudes. The global stellar mass loss rates are found to be rather insensitive to non-uniformities of the surface magnetic field. Depending on the non-uniformity of the field distribution, the angular momentum loss rates deviate in contrast at all rotation rates between -60% ...
Lin, Changyu; Zou, Ding; Liu, Tao; Djordjevic, Ivan B
2016-08-01
A mutual information inspired nonbinary coded modulation design with non-uniform shaping is proposed. Instead of traditional power of two signal constellation sizes, we design 5-QAM, 7-QAM and 9-QAM constellations, which can be used in adaptive optical networks. The non-uniform shaping and LDPC code rate are jointly considered in the design, which results in a better performance scheme for the same SNR values. The matched nonbinary (NB) LDPC code is used for this scheme, which further improves the coding gain and the overall performance. We analyze both coding performance and system SNR performance. We show that the proposed NB LDPC-coded 9-QAM has more than 2dB gain in symbol SNR compared to traditional LDPC-coded star-8-QAM. On the other hand, the proposed NB LDPC-coded 5-QAM and 7-QAM have even better performance than LDPC-coded QPSK. PMID:27505775
Ensuring uniformity of strengthening for machine parts surfaces by shot-peening
Directory of Open Access Journals (Sweden)
Z.A. Stotsko
2010-11-01
Full Text Available Purpose: of this paper is developing the mathematical models of shot-peening, in which is reflected moving shot-peening head or machine parts surfaces during treating that will achieve uniformity of treatment machine parts.Design/methodology/approach: The main methods used for the theoretical research are mathematical modelling, integral calculus, fundamentals of analytic geometry, probability theory. It is used approved enough and well known numerical methods for calculations after mathematical models.Findings: Method of mathematical modeling for shot-peening is developed based on the energy conception. Mathematical model in which is reflected moving shot-peened head or machine parts surfaces during treating is created. It allows forecasting the characteristics of surface quality depending on the technological modes of treatment.Research limitations/implications: It is planned developing and improving the methods of shot-peening mathematical modeling in future research by extending theirs for the curvilinear treated surfaces, which has movement relative to the nozzle of shot-peening head after the different laws of motion, and for different kinds of materials, especially for metal joint endoprosthesis biomaterials.Practical implications: has the applied software, elaborated on the basis of the models, that allows providing for automation of calculations of the characteristics of surface quality depending on the technological modes of treatment.Originality/value: It is pioneered receiving functional dependences in which is reflected moving shot-peened head or machine parts surfaces during treating. Created functional dependences takes into account the distribution of characteristics of working medium (mass and velocity all along the cross-sections of shot blast.
Nazir, Habiba; Lv, Piping; Wang, Lianyan; Lian, Guoping; Zhu, Shiping; Ma, Guanghui
2011-12-01
Emulsions are commonly used in foods, pharmaceuticals and home-personal-care products. For emulsion based products, it is highly desirable to control the droplet size distribution to improve storage stability, appearance and in-use property. We report preparation of uniform-sized silicone oil microemulsions with different droplets diameters (1.4-40.0 μm) using SPG membrane emulsification technique. These microemulsions were then added into model shampoos and conditioners to investigate the effects of size, uniformity, and storage stability on silicone oil deposition on hair surface. We observed much improved storage stability of uniform-sized microemulsions when the droplets diameter was ≤22.7 μm. The uniform-sized microemulsion of 40.0 μm was less stable but still more stable than non-uniform sized microemulsions prepared by conventional homogenizer. The results clearly indicated that uniform-sized droplets enhanced the deposition of silicone oil on hair and deposition increased with decreasing droplet size. Hair switches washed with small uniform-sized droplets had lower values of coefficient of friction compared with those washed with larger uniform and non-uniform droplets. Moreover the addition of alginate thickener in the shampoos and conditioners further enhanced the deposition of silicone oil on hair. The good correlation between silicone oil droplets stability, deposition on hair and resultant friction of hair support that droplet size and uniformity are important factors for controlling the stability and deposition property of emulsion based products such as shampoo and conditioner. PMID:21920528
Constructing iterative non-uniform B-spline curve and surface to fit data points
Institute of Scientific and Technical Information of China (English)
LIN Hongwei; WANG Guojin; DONG Chenshi
2004-01-01
In this paper, based on the idea of profit and loss modification, we present the iterative non-uniform B-spline curve and surface to settle a key problem in computer aided geometric design and reverse engineering, that is, constructing the curve (surface)fitting (interpolating) a given ordered point set without solving a linear system. We start with a piece of initial non-uniform B-spline curve (surface) which takes the given point set as its control point set. Then by adjusting its control points gradually with iterative formula,we can get a group of non-uniform B-spline curves (surfaces) with gradually higher precision. In this paper, using modern matrix theory, we strictly prove that the limit curve (surface) of the iteration interpolates the given point set. The non-uniform B-spline curves (surfaces) generated with the iteration have many advantages, such as satisfying the NURBS standard, having explicit expression, gaining locality, and convexity preserving,etc.
Electroosmotic flow in Hele-Shaw configurations with non-uniform surface charge
Boyko, Evgeniy; Gat, Amir D; Bercovici, Moran
2015-01-01
We present an analytical study, validated by numerical simulations, of electroosmotic flow in a Hele-Shaw cell with non-uniform surface charge patterning. Applying the lubrication approximation and assuming thin electric double layer, we obtain a pair of uncoupled Poisson equations which relate the pressure and the stream function, respectively, to gradients in the zeta potential distribution parallel and perpendicular to the applied electric field. We solve the governing equations for the fundamental case of a disk with uniform zeta potential and show that the flow-field in the outer region takes the form of a pure dipole. We illustrate the ability to generate complex flow-fields around smooth convex regions by superposition of such disks with uniform zeta potential and a uniform pressure driven flow. This method may be useful for future on-chip devices, allowing flow control without the need for mechanical components.
Walko, R. L.; Medvigy, D.; Avissar, R.
2013-12-01
Variable-resolution computational grids can substantially improve the benefit-to-cost ratio in many environmental modeling applications, but they can also introduce unwanted and unrealistic numerical anomalies if not properly utilized. For example, we showed in previous studies that resolved (non-parameterized) atmospheric convection develops more quickly as resolution increases. Furthermore, on variable grids that transition from resolved to parameterized convection, timing and intensity of the convection in both regimes is generally disparate unless special care is taken to tune the parameterization. In both cases, the convection that develops first (due to purely numerical reasons) tends to suppress convection elsewhere by inducing subsidence in the surrounding environment. This highly nonlinear competition, while desirable when induced by natural causes such as surface inhomogeneity, is highly undesirable when it is a numerical artifact of variable grid resolution and/or selective application of convective parameterization. Our current research is aimed at leveling the playing field for convection across a variable resolution grid so that the above problems are avoided. The underlying idea is to apply the same or very similar 'convective machinery' to all areas of the grid. For convection-resolving regions of the grid, this machinery is simply the model grid itself, along with explicit representation of dynamics and a bulk microphysics parameterization. For coarser regions of the grid, the local environment is sampled from one or more grid columns (depending on local resolution) and fed to a separate 'convective processor', which determines the convective response to that environment and feeds the result back to the host grid. The convective processor chooses to either (1) explicitly resolve convective activity in the given environment on a separate (independent) limited-area 3D computational grid of comparable resolution to the convection-resolving part of the
Effect of non-uniform surface resistance on the quality factor of superconducting niobium cavity
Tan, Weiwei; Lu, Xiangyang; Yang, Ziqin; Zhao, Jifei; Yang, Deyu; Yang, Yujia
2016-08-01
The formula Rs = G /Q0 is commonly used in the calculation of the surface resistance of radio frequency niobium superconducting cavities. The applying of such equation is under the assumption that surface resistance is consistent over the cavity. However, the distribution of the magnetic field varies over the cavity. The magnetic field in the equator is much higher than that in the iris. According to Thermal Feedback Theory, it leads non-uniform distribution of the density of heat flux, which results in a different temperature distribution along the cavity inter surface. The BCS surface resistance, which depends largely on the temperature, is different in each local inner surface. In this paper, the effect of surface non-uniform resistance on the quality factor has been studied, through the calculation of Q0 in the original definition of it. The results show that it is necessary to consider the non-uniform distribution of magnetic field when the accelerating field is above 20 MV/m for TESLA cavities. Also, the effect of inhomogeneity of residual resistance on the quality factor is discussed. Its distribution barely affects the quality factor.
Rong, Yun; Zhang, Lei; Liu, Zhenzhong; Dai, Liwei; Huang, Youju; Chen, Tao
2016-06-01
Hierarchical Au nanostructures have attracted considerable attention owing to their rich hot-spots in inherent structures that have found various applications in surface-enhanced Raman scattering (SERS) based sensing and imaging. Herein we facilely synthesized uniform hierarchical raspberry-like Au nanostructures with tunable size via a seed-mediated growth approach employing a binary mixture of quaternized chitosan (QCS) and 5-bromosalicylic acid (5-BrSA). 5-BrSA plays an important role in tuning shapes and improving uniformity of resultant gold nanoparticles (AuNPs). The obtained raspberry-like Au nanostructures have a spherical profile and randomly arranged protrusions on the outsides, and their size can be finely tuned in a range from 50 to 120 nm. The rough surfaces of the special raspberry-like Au nanostructures endow them higher SERS performance than spherical Au spheres with smooth surfaces, which is promising for the application of SERS based sensors and optical imaging. PMID:27427615
Mishra, Pawan
2015-05-06
We investigated the design and growth of compositionally-graded InGaN multiple quantum wells (MQW) based light-emitting diode (LED) without an electron-blocking layer (EBL). Numerical investigation showed uniform carrier distribution in the active region, and higher radiative recombination rate for the optimized graded-MQW design, i.e. In0→xGa1→(1-x)N / InxGa(1-x)N / Inx→0Ga(1-x)→1N, as compared to the conventional stepped-MQW-LED. The composition-grading schemes, such as linear, parabolic, and Fermi-function profiles were numerically investigated for comparison. The stepped- and graded-MQW-LED were then grown using plasma assisted molecular beam epitaxy (PAMBE) through surface-stoichiometry optimization based on reflection high-energy electron-diffraction (RHEED) in-situ observations. Stepped- and graded-MQW-LED showed efficiency roll over at 160 A/cm2 and 275 A/cm2, respectively. The extended threshold current density roll-over (droop) in graded-MQW-LED is due to the improvement in carrier uniformity and radiative recombination rate, consistent with the numerical simulation.
Uniform Regularity and Vanishing Viscosity Limit for the Free Surface Navier-Stokes Equations
Masmoudi, Nader; Rousset, Frederic
2016-09-01
We study the inviscid limit of the free boundary Navier-Stokes equations. We prove the existence of solutions on a uniform time interval by using a suitable functional framework based on Sobolev conormal spaces. This allows us to use a strong compactness argument to justify the inviscid limit. Our approach does not rely on the justification of asymptotic expansions. In particular, we get a new existence result for the Euler equations with free surface from the one for Navier-Stokes.
Radiation flaw detector for testing non-uniform surface bodies of revolution
International Nuclear Information System (INIS)
Radiation flaw detector for testing bodies of revolution with non-uniform surface, welded joints, etc., based on spatial filtration and differentiation of ionizing radiation flux has been described. The calculation of the most important unit of flaw detector - integrators - is made. Experimental studies of the sensitivity have shown, that the radiation flaw detector can be used for rapid testing of products with the sensitivity comparable with the sensitivity of radiographic testing of steel
Influence of Gloss and Surface Roughness of Coated Ink Jet Papers on Print Uniformity
Directory of Open Access Journals (Sweden)
Ivana Jurič
2013-12-01
Full Text Available The final print quality depends on the quality of the digital image as well as the properties of the printing system, the inks and the paper used. One of the most widely used digital printing technologies is ink jet, where ink is ejected directly onto a substrate from a jet device driven by an electronic signal. Most ink jet inks have low viscosity and low surface tension, which pose high demands upon the surface properties of the paper. The aim of this study was to investigate the influence of paper properties of commercially available papers suitable for ink jet printing on print mottle, non-uniformity. We used two high glossy, one glossy, one semi-glossy and two matte papers. For the assessment of the surface properties, we measured surface roughness with the portable Roughness Tester TR 200. We also measured surface gloss with QIP Glossmaster. To characterise the print mottle we used the image analysis method – Gray level co-occurrence matrix (GLCM. Print mottle was estimated according to five GLCM parameters: Contrast, Correlation, Entropy, Energy and Homogeneity. Results obtained in this paper showed that the surface properties of paper are not in any direct relation with print uniformity.
A uniformly valid asymptotic solution of the surface wave problem due to underwater sources
International Nuclear Information System (INIS)
The two-dimensional linearized problem of surface waves in water of finite (or infinite) depth due to a stationary periodic source situated at a finite depth below the free surface, is considered. The formal solution of the problem is derived by using Laplace and Fourier transforms. A uniformly valid asymptotic expansion of the wave integral is obtained by using the method of Bleistein in the case of finite depth and that of Vander Waerden in the case of infinite depth. Physical interpretation of the results so derived is given. (author)
The Electric Field of a Uniformly Charged Non-Conducting Cubic Surface
McCreery, Kaitlin
2016-01-01
As an integrative and insightful example for undergraduates learning about electrostatics, we discuss how to use symmetry, Coulomb's Law, superposition, Gauss's law, and visualization to understand the electric field produced by a non-conducting cubic surface that is covered with a uniform surface charge density. We first discuss how to deduce qualitatively, using only elementary physics, the surprising fact that the electric field inside the cubic surface is nonzero and has a complex structure, pointing inwards towards the cube center from the midface of each cube and pointing outwards towards each edge and corner. We then discuss how to understand the quantitative features of the electric field by plotting an analytical expression for E along symmetry lines and on symmetry surfaces. This example would be a good choice for group problem solving in a recitation or flipped classroom.
Critical thickness of an optimum extended surface characterized by uniform heat transfer coefficient
Leontiou, Theodoros
2015-01-01
We consider the heat transfer problem associated with a periodic array of extended surfaces (fins) subjected to convection heat transfer with a uniform heat transfer coefficient. Our analysis differs from the classical approach as (i) we consider two-dimensional heat conduction and (ii) the base of the fin is included in the heat transfer process. The problem is modeled as an arbitrary two-dimensional channel whose upper surface is flat and isothermal, while the lower surface has a periodic array of extensions/fins which are subjected to heat convection with a uniform heat transfer coefficient. Using the generalized Schwarz-Christoffel transformation the domain is mapped onto a straight channel where the heat conduction problem is solved using the boundary element method. The boundary element solution is subsequently used to pose a shape optimization problem, i.e. an inverse problem, where the objective function is the normalized Shape Factor and the variables of the optimization are the parameters of the Sch...
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The influence of ambient current fields on the mild-slope approximation is reassessed using theHamiltonian variational principle. Considering the slowly modulated non-uniform currents which may possess both verti-cal and horizontal variations, the extended mild-slope equation for surface waves propagating over slowly varying topogra-phy is derived. It is found that for large current velocities comparable to the wave celerity and the group velocity, the ex-tended mild-slope equation is valid. For the validity of the geometric optics-approximation, additional conditions con-cerning current fields should be satisfied.
Surface plasmon resonance microscopy: Achieving a quantitative optical response
Peterson, Alexander W.; Halter, Michael; Plant, Anne L.; Elliott, John T.
2016-09-01
Surface plasmon resonance (SPR) imaging allows real-time label-free imaging based on index of refraction and changes in index of refraction at an interface. Optical parameter analysis is achieved by application of the Fresnel model to SPR data typically taken by an instrument in a prism based figuration. We carry out SPR imaging on a microscope by launching light into a sample and collecting reflected light through a high numerical aperture microscope objective. The SPR microscope enables spatial resolution that approaches the diffraction limit and has a dynamic range that allows detection of subnanometer to submicrometer changes in thickness of biological material at a surface. However, unambiguous quantitative interpretation of SPR changes using the microscope system could not be achieved using the Fresnel model because of polarization dependent attenuation and optical aberration that occurs in the high numerical aperture objective. To overcome this problem, we demonstrate a model to correct for polarization diattenuation and optical aberrations in the SPR data and develop a procedure to calibrate reflectivity to index of refraction values. The calibration and correction strategy for quantitative analysis was validated by comparing the known indices of refraction of bulk materials with corrected SPR data interpreted with the Fresnel model. Subsequently, we applied our SPR microscopy method to evaluate the index of refraction for a series of polymer microspheres in aqueous media and validated the quality of the measurement with quantitative phase microscopy.
Roux-Marchand, Thibaut; Beyssen, Denis; Sarry, Frederic; Elmazria, Omar
2015-04-01
When a microdroplet is put on the Rayleigh surface acoustic wave path, longitudinal waves are radiated into the liquid and induce several phenomena such as the wellknown surface acoustic wave streaming. At the same time, the temperature of the microdroplet increases as it has been shown. In this paper, we study the temperature uniformity of a microdroplet heated by Rayleigh surface acoustic wave for discrete microfluidic applications such as biological reactions. To precisely ascertain the temperature uniformity and not interfere with the biological reaction, we used an infrared camera. We then tested the temperature uniformity as a function of three parameters: the microdroplet volume, the Rayleigh surface acoustic wave frequency, and the continuous applied radio frequency power. Based on these results, we propose a new device structure to develop a future lab on a chip based on reaction temperatures.
Rivulet flow round a horizontal cylinder subject to a uniform surface shear stress
Paterson, C.
2014-09-14
© 2014 © The Author, 2014. Published by Oxford University Press; all rights reserved. For Permissions, please email: journals.permissions@oup.com. The steady flow of a slowly varying rivulet with prescribed flux in the azimuthal direction round a large stationary horizontal cylinder subject to a prescribed uniform azimuthal surface shear stress is investigated. In particular, we focus on the case where the volume flux is downwards but the shear stress is upwards, for which there is always a solution corresponding to a rivulet flowing down at least part of one side of the cylinder. We consider both a rivulet with constant non-zero contact angle but slowly varying width (that is, de-pinned contact lines) and a rivulet with constant width but slowly varying contact angle (that is, pinned contact lines), and show that they have qualitatively different behaviour. When shear is present, a rivulet with constant non-zero contact angle can never run all the way from the top to the bottom of the cylinder, and so we consider the scenario in which an infinitely wide two-dimensional film of uniform thickness covers part of the upper half of the cylinder and \\'breaks\\' into a single rivulet with constant non-zero contact angle. In contrast, a sufficiently narrow rivulet with constant width can run all the way from the top to the bottom of the cylinder, whereas a wide rivulet can do so only if its contact lines de-pin, and so we consider the scenario in which the contact lines of a wide rivulet de-pin on the lower half of the cylinder.
Energy Technology Data Exchange (ETDEWEB)
Hou, H.Q.; Choquette, K.D.; Hammons, B.E.; Breiland, W.G.; Crawford, M.H.; Lear, K.L. [Sandia National Labs., Albuquerque, NM (United States). Center for Compound Semiconductors Technology
1997-05-01
The authors present the growth and characterization of vertical-cavity surface emitting lasers (VCSELs) from visible to near-infrared wavelength grown by metalorganic vapor phase epitaxy. Discussions on the growth issue of VCSEL materials include the control on growth rate and composition using an in situ normal-incidence reflectometer, optimization of ultra-high material uniformity, and comprehensive p- and n-type doping study in AlGaAs by CCl{sub 4} and Si{sub 2}H{sub 6} over the entire Al composition range. They will also demonstrate the recent achievements of selectively-oxidized VCSELs which include the first room-temperature continuous-wave demonstration of all-AlGaAs 700-nm red VCSELs, high-performance n-side up 850-nm VCSELs, and low threshold current and low-threshold voltage 1.06 {micro}m VCSELs using InGaAs/GaAsP strain-compensated quantum wells.
Cheruvathur, Sudha; Lass, Eric A.; Campbell, Carelyn E.
2016-03-01
17-4 precipitation hardenable (PH) stainless steel is a useful material when a combination of high strength and good corrosion resistance up to about 315°C is required. In the wrought form, this steel has a fully martensitic structure that can be strengthened by precipitation of fine Cu-rich face-centered cubic phase upon aging. When fabricated via additive manufacturing (AM), specifically laser powder-bed fusion, 17-4 PH steel exhibits a dendritic structure containing a substantial fraction of nearly 50% of retained austenite along with body centered cubic/martensite and fine niobium carbides preferentially aligned along interdendritic boundaries. The effect of post-build thermal processing on the material microstructure is studied in comparison to that of conventionally produced wrought 17-4 PH with the intention of creating a more uniform, fully martensitic microstructure. The recommended stress relief heat treatment currently employed in industry for post-processing of AM 17-4 PH steel is found to have little effect on the as-built dendritic microstructure. It is found that, by implementing the recommended homogenization heat treatment regimen of Aerospace Materials Specification 5355 for CB7Cu-1, a casting alloy analog to 17-4 PH, the dendritic solidification structure is eliminated, resulting in a microstructure containing about 90% martensite with 10% retained austenite.
On the Heat Transfer through a Solid Slab Heated Uniformly and Continuously on One of Its Surfaces
Marin, E.; Lara-Bernal, A.; Calderon, A.; Delgado-Vasallo, O.
2011-01-01
Some peculiarities of the heat transfer through a sample that is heated by the superficial absorption of light energy under continuous uniform illumination are discussed. We explain, using a different approach to that presented in a recent article published in this journal (Salazar "et al" 2010 "Eur. J. Phys." 31 1053-9), that the front surface of…
Outram, B. I.; Elston, S. J.; Tuffin, R.; Siemianowski, S.; Snow, B.
2013-06-01
The chiral-flexoelectrooptic effect in a Uniform Lying Helix (ULH) configuration provides a sub-millisecond in-plane rotation of the optic axis with the application of a transverse field. This enables displays with a wide viewing angle without costly in-plane-type electrodes. The salient challenge is one of alignment of the ULH, which is not topologically compatible with uniform alignment surface treatments. Here, we create a micro-grooved surface structure with features on the micron scale by using a replica-moulding technique. When the cell is assembled, the micro-grooves create channels, and using surface-energy considerations, we explain how and show experimentally that the channels align a cholesteric material in the ULH geometry with the helicoidal axis oriented parallel to the channels. The resultant alignment provides a high level of contrast between crossed polarizers and exhibits an electrooptic response with a switching time of the order of tens of microseconds.
Institute of Scientific and Technical Information of China (English)
Hu Huang; Jia Fu
2006-01-01
A fully three-dimensional surface gravitycapillary short-crested wave system is studied as two progressive wave-trains of equal amplitude and frequency, which are collinear with uniform currents and doubly-periodic in the horizontal plane, are propagating at an angle to each other. The first-and second-order asymptotic analytical solutions of the short-crested wave system are obtained via a perturbation expansion in a small parameter associated with the wave steepness, therefore depicting a series of typical three-dimensional wave patterns involving currents, shallow and deep water, and surface capillary waves, and comparing them with each other.
Pourali, N.; Foroutan, G.
2016-07-01
The uniformity of film deposition on charged nanoparticles, trapped near the sheath of a capacitively coupled plasma reactor, is studied by numerical simulation of the multi-fluid plasma equations, surface deposition processes, and nanoparticle heating effects. It is found that the anisotropy in the ion flux onto the powered electrode may be hold responsible for the film nonuniformity. The nonuniformity increases with increasing of the particle radius, although small particles lose sphericity faster than the large particles. Because of the electron temperature dependence of the deposition rate and the incident ion flux, higher electron temperatures lead to more nonuniform film deposition. However, the uniformity is improved and the sphericity is restored by the increase in the background gas pressure and/or temperature.
Qian, Shizhi; Joo, Sang W; Ai, Ye; Cheney, Marcos A; Hou, Wensheng
2009-01-15
The electrokinetic ionic-current rectification in a conical nanopore with linearly varying surface-charge distributions is studied theoretically by using a continuum model composed of a coupled system of the Nernst-Planck equations for the ionic-concentration field and the Poisson equation for the electric potential in the electrolyte solution. The numerical analysis includes the electrochemistry inside reservoirs connected to the nanopore, neglected in previous studies, and more precise accounts of the ionic current are provided. The surface-charge distribution, especially near the tip of the nanopore, significantly affects the ionic enrichment and depletion, which, in turn, influence the resulting ionic current and the rectification. It is shown that non-uniform surface-charge distribution can reverse the direction, or sense, of the rectification. Further insights into the ionic-current rectification are provided by discussing the intriguing details of the electric potential and ionic-concentration fields, leading to the rectification. Rationale for future studies on ionic-current rectification, associated with other non-uniform surface-charge distributions and electroosmotic convection for example, is discussed.
Yuan, Hao; Song, Qingwen; Tang, Xiaoyan; Zhang, Yimeng; Zhang, Yimen; Zhang, Yuming
2016-09-01
In this paper, a 4H-SiC Junction Barrier Schottky diode (JBS) with non-uniform floating limiting rings (FLRs) has been investigated and fabricated using n type 4H-SiC epitaxial layer with thickness of 31 μm and doping concentration of 3.3 × 1015 cm-3. According to the simulated results, the key parameters of a FLRs design to achieve a high voltage are the minimum space between two adjacent doped rings, spacing growth step and number of rings. The experimental results also show a great agreement with simulated results. Meanwhile, a near-ideal breakdown voltage of 3.7 kV was achieved, which yield around 95% of the parallel-plane breakdown voltage. The forward characteristics show that the fabricated JBS diodes have a forward current density of 210 A/cm2 at 3 V and a specific on-resistance (Rsp-on) of 7.58 mΩ cm2. Different FLRs parameters have no effect on the forward device performance.
Natural convection flow of Cu-H2O nanofluid along a vertical wavy surface with uniform heat flux
Habiba, Farjana; Molla, Md. Mamun; Khan, M. A. Hakim
2016-07-01
A numerical study on natural convection flow of Cu-Water nanofluid along a vertical wavy surface with uniform heat flux has been carried out. The governing boundary layer equations are transformed into parabolic partial differential equations by applying a suitable set of variables. The resulting nonlinear system of equations are then mapped into a regular rectangular computational domain and solved numerically by using an implicit finite difference method. Numerical results are thoroughly discussed in terms of velocity and temperature distributions, surface temperature distribution, skin friction coefficient and Nusselt number coefficient for selected key parameters such as solid volume fraction of nanofluid (ϕ) and amplitude (α) of surface waviness. In addition, velocity vectors, streamlines and isotherms are plotted to visualize momentum and thermal flow pattern within the boundary layer region.
MHD flow and heat transfer from continuous surface in uniform free stream of non-Newtonian fluid
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
An analysis is carried out to study the steady flow and heat transfer characteristics from a continuous flat surface moving in a parallel free stream of an electrically conducting non-Newtonian viscoelastic fluid. The flow is subjected to a transverse uniform magnetic field. The constitutive equation of the fluid is modeled by that for a second grade fluid. Numerical results are obtained for the distribution of velocity and temperature profiles. The effects of various physical parameters like viscoelastic parameter, magnetic parameter and Prandtl number on various momentum and heat transfer characteristics are discussed in detail and shown graphically.
Directory of Open Access Journals (Sweden)
Stephanie Oyola-Reynoso
2015-12-01
Full Text Available Modifying the chemistry of a surface has been widely used to influence interfacial properties of a material or nature of interaction between two materials. This article provides an overview on the role of polyfunctional molecules, specifically silanes, in surface modification of polar surfaces (bearing soft nucleophiles. An emphasis on the mechanism of the reaction in the presence of adsorbed water, where the modifying reagents are hydrolysable, is discussed. To highlight the complexity of the reaction, modification of paper with trichlorosilanes is highlighted. Preparation of hydrophobic cellulosic paper, and structure–property relations under different treatment conditions is used to highlight that a monolayer is not always formed during the surface modification. Gel-formation via step-growth polymerization suggests that at the right monomer:adsorbed water ratio, a monolayer will not form but rather self-assembly driven particle formation will occur leading to a textured surface. The review highlights recent work indicating that the focus on monolayer formation, is at the very least, not always the case but gel formation, with concomitant self-assembly, might be the culprit in understanding challenges associated with the use of polyfunctional molecules in surface modification.
Energy Technology Data Exchange (ETDEWEB)
Tang, Junqi; Zhao, Qianrun; Zhang, Ning; Man, Shi-Qing, E-mail: man_shiqing@yahoo.com
2014-07-01
A large-area efficient surface enhanced Raman scattering (SERS) substrate was deposited by Langmuir–Blodgett (LB) assembly and followed by sputter coating process. The interparticle distance of silica nanospheres was convenient and readily regulated by controlling the surface pressure. After sputter coating with a small amount of gold, the nanocomposite film was formed. The surfaces of nanostructures were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The applicability of the nanostructures as SERS substrates was investigated by adsorption of crystal violet (CV) molecules. Different SERS effects were observed on deposited gold nanostructure upon large-area silica nanospheres monolayer with diameter of 250, 570 and 800 nm. It was also discussed the nanospheres with diameter of 250 nm for the fabrication of ordered arrangement of monolayers at surface pressures of 10–30 mN/m. These substrates with the close-packed nanospheres and sputtering of gold were found to exhibit high and uniform enhancement of the Raman signal across the entire surface. The averaged surface enhancement factor (ASEF) was calculated and discussed. The fabricated nanocomposite structures could be utilized as low-cost SERS-active substrates for biomedical and analytical chemistry field.
The Hydrogen Abstraction from A Diamond(111) Surface in A Uniform Electric Field
Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Kang, Jeung Ku.; Musgrave, Charles B.; Arnold, James O. (Technical Monitor)
1998-01-01
Bond breaking in a strong electric field is shown to arise from a crossing of the ionic and covalent asymptotes. The specific example of hydrogen abstraction from a diamond(111) surface is studied using a cluster model. The addition of nearby atoms in both the parallel and perpendicular direction to the electric field are found to have an effect. It is also shown that the barrier is not only related to the position of the ionic and covalent asymptotes.
International Nuclear Information System (INIS)
A solvent soaking and rinsing method, in which the solvent was allowed to soak all over the surface followed by a spinning for solvent draining, was found to produce perovskite layers with high uniformity on a centimeter scale and with much improved reliability. Besides the enhanced crystallinity and surface morphology due to the rinsing induced surface precipitation that constrains the grain growth underneath in the precursor films, large-area uniformity with film thickness determined exclusively by the rotational speed of rinsing spinning for solvent draining was observed. With chloroform as rinsing solvent, highly uniform and mirror-like perovskite layers of area as large as 8 cm × 8 cm were produced and highly uniform planar perovskite solar cells with power conversion efficiency of 10.6 ± 0.2% as well as much prolonged lifetime were obtained. The high uniformity and reliability observed with this solvent soaking and rinsing method were ascribed to the low viscosity of chloroform as well as its feasibility of mixing with the solvent used in the precursor solution. Moreover, since the surface precipitation forms before the solvent draining, this solvent soaking and rinsing method may be adapted to spinless process and be compatible with large-area and continuous production. With the large-area uniformity and reliability for the resultant perovskite layers, this chloroform soaking and rinsing approach may thus be promising for the mass production and commercialization of large-area perovskite solar cells
Institute of Scientific and Technical Information of China (English)
GAO Zhiqiu; BIAN Lingen; CHEN Zhigang; Michael SPARROW; ZHANG Jiahua
2006-01-01
This paper describes the application of the variance method for flux estimation over a mixed agricultural region in China. Eddy covariance and flux variance measurements were conducted in a near-surface layer over a non-uniform land surface in the central plain of China from 7 June to 20 July 2002. During this period, the mean canopy height was about 0.50 m. The study site consisted of grass (10% of area), beans (15%), corn (15%) and rice (60%). Under unstable conditions, the standard deviations of temperature and water vapor density (normalized by appropriate scaling parameters), observed by a single instrument,followed the Monin-Obukhov similarity theory. The similarity constants for heat (CT) and water vapor (Cq) were 1.09 and 1.49, respectively. In comparison with direct measurements using eddy covariance techniques, the flux variance method, on average, underestimated sensible heat flux by 21% and latent heat flux by 24%, which may be attributed to the fact that the observed slight deviations (20% or 30% at most) of the similarity "constants" may be within the expected range of variation of a single instrument from the generally-valid relations.
van Kalleveen, Irene M. L.; Boer, VO; Luijten, Peter R.; Klomp, DWJ
2015-01-01
Purpose: Going to ultrahigh field MRI (e. g., 7 Tesla [ T]), the nonuniformity of the B_1 field and the increased radiofrequency (RF) power deposition become challenging. While surface coils improve the power efficiency in B_1, its field remains nonuniform. In this work, an RF pulse was designed tha
School Uniforms. Research Brief
Walker, Karen
2007-01-01
Does clothing make the person or does the person make the clothing? How does what attire a student wears to school affect their academic achievement? In 1996, President Clinton cited examples of school violence and discipline issues that might have been avoided had the students been wearing uniforms ("School uniforms: Prevention or suppression?").…
Directory of Open Access Journals (Sweden)
Luwei Zhou
2014-01-01
Full Text Available This study demonstrated that near infrared chemical imaging (NIR-CI was a rapid and nondestructive technique for discrimination of chlorpheniramine maleate (CPM and assessment of its surface content uniformity (SCU in a pharmaceutical formulation. The characteristic wavenumber method was used for discriminating CPM distribution on the tablet surface. To assess the surface content uniformity of CPM, binary image and statistical measurement were proposed. Furthermore, high-performance liquid chromatography (HPLC was used as reference method for accurately determining volume content of CPM in the sample. Moreover, HPLC was performed to assess volume content uniformity (VCU of CPM in whole region and part region of the tablets. The NIR-CI result showed that the spatial distribution of CPM was heterogeneous on the tablet surface. Through the comparison of content uniformity of CPM determined by NIR-CI and HPLC, respectively, it demonstrated that a high degree of VCU did not imply a high degree of SCU of the samples. These results indicate that HPLC method is not suitable for testing SCU, and this has been verified by NIR-CI. This study proves the feasibility of NIR-CI for rapid discrimination of CPM and assessment of its SCU, which is helpful for the quality control of commercial CPM tablets.
Modeling and simulation of protein-surface interactions: achievements and challenges.
Ozboyaci, Musa; Kokh, Daria B; Corni, Stefano; Wade, Rebecca C
2016-01-01
Understanding protein-inorganic surface interactions is central to the rational design of new tools in biomaterial sciences, nanobiotechnology and nanomedicine. Although a significant amount of experimental research on protein adsorption onto solid substrates has been reported, many aspects of the recognition and interaction mechanisms of biomolecules and inorganic surfaces are still unclear. Theoretical modeling and simulations provide complementary approaches for experimental studies, and they have been applied for exploring protein-surface binding mechanisms, the determinants of binding specificity towards different surfaces, as well as the thermodynamics and kinetics of adsorption. Although the general computational approaches employed to study the dynamics of proteins and materials are similar, the models and force-fields (FFs) used for describing the physical properties and interactions of material surfaces and biological molecules differ. In particular, FF and water models designed for use in biomolecular simulations are often not directly transferable to surface simulations and vice versa. The adsorption events span a wide range of time- and length-scales that vary from nanoseconds to days, and from nanometers to micrometers, respectively, rendering the use of multi-scale approaches unavoidable. Further, changes in the atomic structure of material surfaces that can lead to surface reconstruction, and in the structure of proteins that can result in complete denaturation of the adsorbed molecules, can create many intermediate structural and energetic states that complicate sampling. In this review, we address the challenges posed to theoretical and computational methods in achieving accurate descriptions of the physical, chemical and mechanical properties of protein-surface systems. In this context, we discuss the applicability of different modeling and simulation techniques ranging from quantum mechanics through all-atom molecular mechanics to coarse
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.
Melikhov, Sergey A
2011-01-01
Although topological and uniform approaches to foundations of what was then known as Analysis Situs originated in the same works by M. Frechet and F. Riesz, uniform spaces hopelessly lagged behind in development, and were never taken seriously in algebraic and geometric topology, due in part to the lack of a coherent theory of quotient spaces, and of a reasonable notion of a polyhedron in the uniform category. Yet there are painful side effects of the usual topological foundations: for instance, the non-metrizability of the cone over the real line, and the non-metrizability of RP^\\infty (as a CW-complex or as the geometric realization of a simplicial set). We show that (the topology of) quotient uniformity is, after all, far nicer than quotient topology in the context of metrizable spaces, and that (metrizable, possibly locally infinite-dimensional) uniform polyhedra do exist - and behave nicely - which appears to provide a satisfactory solution to an old open-ended problem by Isbell.
Liu, Feng; Jin, Zhongxiu; Zhu, Jun; Xu, Yafeng; Zhou, Li; Dai, Songyuan
2016-06-01
Achieving high surface coverage of the colloidal quantum dots (QDs) on TiO2 films has been challenging for quantum dot-sensitized solar cells (QDSCs). Herein, a general surface engineering approach was proposed to increase the loading of these QDs. It was found that S2- treatment/QD re-uptake process can significantly improve the attachment of the QDs on TiO2 films. Surface concentration of the QDs was improved by ∼60%, which in turn greatly enhances light absorption and decreases carrier recombination in QDSCs. Ensuing QDSCs with optimized QD loading exhibit a power conversion efficiency of 3.66%, 83% higher than those fabricated with standard procedures.
International Nuclear Information System (INIS)
This paper presents a uniform micro/nano double-roughened superhydrophobic surface with a high static contact angle (CA) and low contact angle hysteresis (CAH). The proposed micro/nano complex structured surfaces were self-fabricated simply and efficiently using a very simple and low-cost nonlithographic sequential process, which consists of aluminum (Al) sputtering, anodization of the Al layer and pore widening, without specific equipment and additional subsequent processes. The wetting properties of the fabricated surfaces were characterized by measuring the static CAs and the CAHs after plasma polymerized fluorocarbon coating with a low surface energy. The measured static CA and CAH were 154 ± 2.3° and 5.7 ± 0.8°, respectively, showing that the fabricated double-roughened surfaces exhibit superhydrophobic behaviors clearly. In addition, the proposed double-scaled surfaces at a wafer-level exhibited uniform superhydrophobic behaviors across the wafer with an apparent CA and CAH of 153.9 ± 0.8° and 4.9 ± 1.3°, respectively.
International Nuclear Information System (INIS)
Free convection flow of a conducting fluid near an isothermal sheet with a uniform free stream of constant velocity and temperature is investigated. The sheet is linearly stretched in the presence of a uniform strong transverse magnetic field and the Hall effects are taken into account. The effect of internal heat generation or absorption is also considered. The boundary layer equations governing the problem under consideration have been transformed into a system of ordinary differential equations, which are solved numerically. Velocity and temperature functions are shown on graphs and the numerical values of functions affecting the shear stress and the rate of heat transfer are entered in a table. The effects of the magnetic field, the Hall and the heat source/sink parameters on these functions are discussed. The results are compared with those known from the literature. (orig.)
García Aguilar, Andrés
2013-01-01
Con esta tesis ”Desarrollo de una Teoría Uniforme de la Difracción para el Análisis de los Campos Electromagnéticos Dispersados y Superficiales sobre un Cilindro” hemos iniciado una nueva línea de investigación que trata de responder a la siguiente pregunta: ¿cuál es la impedancia de superficie que describe una estructura de conductor eléctrico perfecto (PEC) convexa recubierta por un material no conductor? Este tipo de estudios tienen interés hoy en día porque ayudan a predecir el campo elec...
Surface accuracy achieved by upsetting of preforms generated by laser rod end melting
Directory of Open Access Journals (Sweden)
Brüning Heiko
2015-01-01
Full Text Available Cold forming generally allows the reproduction of parts with a high production rate and low waste of material. For this reason, many small parts for example of the body of a smartphone undergo at least one forming operation during their fabrication, e.g. screws, brackets or springs. However, when the size of forming products is reduced to the micro range, size effects appear and affect the forming process. One size effect leads to the fact that conventional multi stage upsetting processes cannot be scaled to micro range accordingly. As a consequence, the maximum achievable upset ratio decreases from 2.3 in macro range to values below 2 in micro range. This reduces the efficiency of the upsetting process significantly as more upsetting stages have to be carried out to reach the desired shape of the forming product. A very promising approach to reduce required forming stages is the laser rod end melting process which takes advantage of a size effect. Herein, the lower end of a rod is melted by the energy of a laser beam. The molten part of the rod automatically forms spherical due to surface tension. This droplet-shaped part is called “preform”. After total cooling, the preform is upset within a single stage cold forming operation to achieve the desired shape. In this paper, results of the upsetting operation with regard to surface accuracy of the forming product are presented. It is shown that surface characteristics with dimensions as small as 500 nm can be reasonably reproduced.
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
The paper studies the problem of the unsteady two-dimensional stagnation-point flow of an incompressible viscous fluid over a flat deformable sheet. The flow is started impulsively from rest and the sheet is suddenly stretched in its own plane with a velocity proportional to the distance from the stagnation point. An analytical series solution is obtained by means of the homotopy analysis method (HAM). Also, the homotopy-Pade′ technique is employed. An explicit formula for the local friction coefficient is provided. The present formula, different from the perturbation solution, is accurate and uniformly valid for all dimensionless time in the whole spatial region and for all possible values of physical parameter λ, defined as the ratio of the potential flow velocity to the sheet sudden stretching velocity. Numerical tests are done to verify the present formula for its validity and accuracy.
Kaskela, Antti; Mustonen, Kimmo; Laiho, Patrik; Ohno, Yutaka; Kauppinen, Esko I
2015-12-30
We report the fabrication of thin film transistors (TFTs) from networks of nonbundled single-walled carbon nanotubes with controlled surface densities. Individual nanotubes were synthesized by using a spark generator-based floating catalyst CVD process. High uniformity and the control of SWCNT surface density were realized by mixing of the SWCNT aerosol in a turbulent flow mixer and monitoring the online number concentration with a condensation particle counter at the reactor outlet in real time. The networks consist of predominantly nonbundled SWCNTs with diameters of 1.0-1.3 nm, mean length of 3.97 μm, and metallic to semiconducting tube ratio of 1:2. The ON/OFF ratio and charge carrier mobility of SWCNT TFTs were simultaneously optimized through fabrication of devices with SWCNT surface densities ranging from 0.36 to 1.8 μm(-2) and channel lengths and widths from 5 to 100 μm and from 100 to 500 μm, respectively. The density optimized TFTs exhibited excellent performance figures with charge carrier mobilities up to 100 cm(2) V(-1) s(-1) and ON/OFF current ratios exceeding 1 × 10(6), combined with high uniformity and more than 99% of devices working as theoretically expected. PMID:26666626
Directory of Open Access Journals (Sweden)
Sygut P.
2016-06-01
Full Text Available The paper presents the results of theoretical studies influence of non-uniform temperature distribution along the feedstock length to the unit friction force working on the metal contact surface with the roll change during the round bars 70 mm in diameter continuous rolling process. This value is one of the major factors affecting the grooves wear during the rolling process. The studies were carried out based on the actual engineering data for 160 × 160 mm square cross-section feedstock of steel S355J0. Numerical modelling of the rolling process was performed using Forge2008®, a finite-element based computer program.
Directory of Open Access Journals (Sweden)
Jia Ge
2014-01-01
Full Text Available We present an alternative method of depositing a high-quality passivation film for heterojunction silicon wafer solar cells, in this paper. The deposition of hydrogenated intrinsic amorphous silicon suboxide is accomplished by decomposing hydrogen, silane, and carbon dioxide in an industrial remote inductively coupled plasma platform. Through the investigation on CO2 partial pressure and process temperature, excellent surface passivation quality and optical properties are achieved. It is found that the hydrogen content in the film is much higher than what is commonly reported in intrinsic amorphous silicon due to oxygen incorporation. The observed slow depletion of hydrogen with increasing temperature greatly enhances its process window as well. The effective lifetime of symmetrically passivated samples under the optimal condition exceeds 4.7 ms on planar n-type Czochralski silicon wafers with a resistivity of 1 Ωcm, which is equivalent to an effective surface recombination velocity of less than 1.7 cms−1 and an implied open-circuit voltage (Voc of 741 mV. A comparison with several high quality passivation schemes for solar cells reveals that the developed inductively coupled plasma deposited films show excellent passivation quality. The excellent optical property and resistance to degradation make it an excellent substitute for industrial heterojunction silicon solar cell production.
DEFF Research Database (Denmark)
Saio, Hideyuki; Kurtz, Donald W.; Takata, Masao;
2015-01-01
We have found a rotationally split series of core g-mode triplets and surface p-mode multiplets in a main-sequence F star, KIC 9244992. Comparison with models shows that the star has a mass of about 1.45 M-circle dot, and is at an advanced stage of main-sequence evolution in which the central...... hydrogen abundance mass fraction is reduced to about 0.1. This is the second case, following KIC 11145123, of an asteroseismic determination of the rotation of the deep core and surface of an A-F main-sequence star. We have found, essentially model independently, that the rotation near the surface...... transport in the interior of an A-F star during the main-sequence stage is much stronger than that expected from standard theoretical formulations....
Energy Technology Data Exchange (ETDEWEB)
Ma, Zhipeng [Hebei Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); Shao, Guangjie, E-mail: shaoguangjie@ysu.edu.cn [Hebei Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China); State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); Wang, Xu [The Equipment Research Institute of the General Logistic Department of the CPLA, Beijing 100010 (China); Song, Jianjun; Wang, Guiling; Liu, Tingting [Hebei Key Laboratory of Applied Chemistry, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004 (China)
2014-02-14
A facile solvothermal synthesis and esterification reaction combined with a high temperature calcination technique has been developed to prepare the uniform carbon coating LiFePO{sub 4} nanoplates. The carbon coating LiFePO{sub 4} nanoplates are investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscope (TEM), galvanostatic intermittent titration technique (GITT) and galvanostatic charge–discharge test. A reasonable growth mechanism of LiFePO{sub 4} nanoplates is proposed on the basis of time dependent experimental results. The results show that each nanoplate is a LiFePO{sub 4} single crystal with the large (010) plane. According to Raman spectroscopy analysis, carbon is uniformly coated on the surface of LiFePO{sub 4} nanoplates. Electrochemical test results also indicate that the carbon coating LiFePO{sub 4} nanoplates exhibit a high reversible specific capacity of 144.8 mAh g{sup −1} at 0.5 C and 116.9 mAh g{sup −1} under lower discharging rate at −20 °C. - Highlights: • LiFePO{sub 4} nanoplates prepared by facile solvothermal synthesis expose large (010) plane. • The polyester network formed by the esterification reaction could entirely wrap LiFePO{sub 4}. • The polyester wrapped on the surface of LiFePO{sub 4} transformed into the uniform carbon layer after calcination. • LiFePO{sub 4}/C nanoplates have good high-rate and low-temperature performance.
Directory of Open Access Journals (Sweden)
Kuczyński Paweł
2014-06-01
Full Text Available The paper deals with a solution of radiation heat transfer problems in enclosures filled with nonparticipating medium using ray tracing on hierarchical ortho-Cartesian meshes. The idea behind the approach is that radiative heat transfer problems can be solved on much coarser grids than their counterparts from computational fluid dynamics (CFD. The resulting code is designed as an add-on to OpenFOAM, an open-source CFD program. Ortho-Cartesian mesh involving boundary elements is created based upon CFD mesh. Parametric non-uniform rational basis spline (NURBS surfaces are used to define boundaries of the enclosure, allowing for dealing with domains of complex shapes. Algorithm for determining random, uniformly distributed locations of rays leaving NURBS surfaces is described. The paper presents results of test cases assuming gray diffusive walls. In the current version of the model the radiation is not absorbed within gases. However, the ultimate aim of the work is to upgrade the functionality of the model, to problems in absorbing, emitting and scattering medium projecting iteratively the results of radiative analysis on CFD mesh and CFD solution on radiative mesh.
Institute of Scientific and Technical Information of China (English)
J. Reece Roth; Z.Y. Chen; Peter P.- Y. Tsai
2001-01-01
Direct exposure of samples to the active species of air generated by a One AtmosphereUniform Glow Discharge Plasma (OA UGDP) has been used to etch and to increasethe surface energy of metallic surfaces, photoresist, polymer films, and nonwoven fab-rics. The OAUGDP is a non-thermal plasma with the classical characteristics of aDC normal glow discharge that operates in air (and other gases) at atmospheric pres-sure. Neither a vacuum system nor batch processing is necessary. A wide range ofapplications to metals, photoresist, films, fabrics, and polymeric webs can be accom-modated by direct exposure of the workpiece to the plasma in parallel-plate reactors.This technology is simple, it produces effects that can be obtained in no other way atone atmosphere; it generates minimal pollutants or unwanted by-products; and it issuitable for individual sample or online treatment of metallic surfaces, wafers, films.and fabrics.``Early exposures of solid materials to the OA UGDP required minutes to produce rela-tively small increases of surface energy. These durations appeared too long for com-mercial application to fast-moving webs. Recent improvements in OA UGDP gas com-position, power density, plasma quality, recirculating gas flow, and impedance match-ing of the power supply to the parallel plate plasma reactor have made it possible toraise the surface energy ofa variety of polymeric webs (PP, PET, PE, etc.) to levels of60 to 70 dynes/crn with one second of exposure. In air plasmas, the high surface ener-gies are not durable, and fall to 50 dynes/em after periods of weeks to months. Here.we report the exposure of metallic surfaces, photoresist, polymeric films, and nonwo-ven fabrics made of PP and PET to an impedance matched parallel plate OA UGDPfor durations ranging from one second to several tens of seconds. Data will be re-ported on the surface energy, wettability, wickability, and aging effect of polymericfilms and fabrics as functions of time of exposure, and time
Energy Technology Data Exchange (ETDEWEB)
1978-08-31
This report is a six-part statistical summary of surface weather observations for Anderson AFB, Agana, Guam. It contains the following parts: (A) Weather Conditions; Atmospheric Phenomena; (B) Precipitation, Snowfall and Snow Depth (daily amounts and extreme values); (C) Surface winds; (D) Ceiling Versus Visibility; Sky Cover; (E) Psychrometric Summaries (daily maximum and minimum temperatures, extreme maximum and minimum temperatures, psychrometric summary of wet-bulb temperature depression versus dry-bulb temperature, means and standard deviations of dry-bulb, wet-bulb and dew-point temperatures and relative humidity); and (F) Pressure Summary (means, standard, deviations, and observation counts of station pressure and sea-level pressure). Data in this report are presented in tabular form, in most cases in percentage frequency of occurrence or cumulative percentage frequency of occurrence tables.
Nesic, Jelena; Rtimi, Sami; Laub, Danièle; Roglic, Goran M; Pulgarin, Cesar; Kiwi, John
2014-11-01
This study presents new evidence for the events leading to Escherichia coli reduction in the absence of light irradiation on TiO2-polyester (from now on TiO2-PES. By transmission electron microscopy (TEM) the diffusion of TiO2 NP's aggregates with the E. coli outer lipo-polyssacharide (LPS) layer is shown to be a prerequisite for the loss of bacterial cultivability. Within 30 min in the dark the TiO2 aggregates interact with E. coli cell wall leading within 120 min to the complete loss of bacterial cultivability on a TiO2-PES 5% TiO2 sample. The bacterial reduction was observed to increase with a higher TiO2 loading on the PES up to 5%. Bacterial disinfection on TiO2-PES in the dark was slower compared to the runs under low intensity simulated sunlight light irradiation. The interaction between the TiO2 aggregates and the E. coli cell wall is discussed in terms of the competition between the TiO2 units collapsing to form TiO2-aggregates at a physiologic pH-value followed by the electrostatic interaction with the bacteria surface. TiO2-PES samples were able to carry repetitive bacterial inactivation. This presents a potential for practical applications. X-ray photoelectron spectroscopy (XPS) evidence was found for the reduction of Ti4+ to Ti3+ contributing to redox interactions between TiO2-PES and the bacterial cell wall. Insight is provided into the mechanism of interaction between the E. coli cell wall and TiO2 NP's. The properties of the TiO2-PES surface like percentage atomic concentration, TiO2-loading, optical absorption, surface charge and crystallographic phases are reported in this study. PMID:25444660
ACHIEVING THRESHOLD BARRIER OF 1 nm ROUGHNESS VALUE OF SILICON SURFACE BY DIAMOND TURNING
Institute of Scientific and Technical Information of China (English)
1998-01-01
1 nm roughness value of silicon surface by diamond turning is obtained firstly and three novel techniques are proposed. The surface integrity is studied in detail by using atomic force microscope, scanning electron microscope, and stylus surface instrument. The diamond tool sharpness hasa considerable influence on the machined surface, therefore a novel technique-brightness modulation for measuring accurately the edge of the cutter is proposed. Mirror surfaces are assessed by another novel technique-a measure of their reflectivity. A third technique, single grit diamond machining is carried out. It supplies a experimental evidence for verifying the obtained high quality turned surfaces.
Directory of Open Access Journals (Sweden)
Sun D
2016-06-01
Full Text Available Deqing Sun,1,2 Aiying Xue,3 Bin Zhang,1 Xia Xue,1 Jie Zhang,1 Wenjie Liu1 1Department of Pharmacy, the Second Hospital of Shandong University, Jinan, People’s Republic of China; 2School of Pharmaceutical Sciences, Shandong University, Jinan, People’s Republic of China; 3Department of Cardiology, the Second Hospital of Shandong University, Jinan, People’s Republic of China Abstract: Acetylpuerarin (AP, an acetylated derivative of puerarin, shows brain-protective effects in animals. However, AP has low oral bioavailability because of its poor water solubility. The objective of this study was to design and develop poly(lactide-co-glycolide (PLGA nanoparticles (NPs to enhance the oral bioavailability of AP. The NPs were prepared using a solvent diffusion method optimized via uniform design (UD combined with response surface methodology (RSM and characterized by their morphology, particle size, zeta (ζ-potential, encapsulation efficiency (EE, drug loading (DL, and in vitro drug release. A pharmacokinetic study was conducted in Wistar rats administered a single oral dose of 30 mg/kg AP. The optimized NPs were spherical and uniform in shape, with an average particle size of 145.0 nm, a polydispersity index (PI of 0.153, and a ζ-potential of -14.81 mV. The release of AP from the PLGA NPs showed an initial burst release followed by a sustained release, following Higuchi’s model. The EE and DL determined in the experiments were 90.51% and 17.07%, respectively. The area under the plasma concentration-time curve (AUC0-∞ of AP-PLGA-NPs was 6,175.66±350.31 h ng/mL, which was 2.75 times greater than that obtained from an AP suspension. This study showed that PLGA NPs can significantly enhance the oral bioavailability of AP. Keywords: acetylpuerarin, nanoparticles, poly(lactic-co-glycolic acid, pharmacokinetics, bioavailability
International Nuclear Information System (INIS)
Document available in extended abstract form only. In the framework of clay barrier concept for underground nuclear waste storage, montmorillonite and bentonite have been widely used as reference materials for sorption. Recently, accompanying modelling work aims at understanding and predicting sorption in more complex systems where clay are assumed to be representative of the most reactive natural phases. This 'bottom-up' approach relies on a good confidence in the mechanistic understanding of sorption phenomena. The present study aims at reviewing clay sorption experimental and modelling works with a focus on divalent metals surface complexation mechanisms. Clay sorption processes together with current modelling concepts will be discussed. Based on this current knowledge, criteria will be set up to select data that are relevant for surface complexation model calibration (especially ionic strength, pH, clay preparation, metal to clay ratio and solubility limits). We identified missing information, which is necessary to model sorption data in a mechanistic way, together with experimental features that cast doubt on the ability of surface complexation models to catch adequately the nature of divalent metal sorption on montmorillonite edge surface. Problematic experimental features will be highlighted, especially those related to the reversibility of sorption (surface complexation model approaches make the hypothesis of total reversibility) and the effect of solid to liquid ratio (RSL) on sorption distribution coefficients (thermodynamic equilibrium condition agrees only with a constant distribution coefficient as a function of RSL). Neglecting these possible problems, models available in the literature will be then tested in terms of efficiency (data fit) and mechanistic likelihood. Although the link between edge surface charge and edge surface potential is complicated by the spill-over of electrostatic field present on basal and interlayer surfaces on edge surfaces
Li, Q
2013-01-01
In this paper, we aim to address an important issue about the pseudopotential lattice Boltzmann (LB) model, which has attracted much attention as a mesoscopic model for simulating interfacial dynamics of complex fluids, but suffers from the problem that the surface tension cannot be tuned independently of the density ratio. In the literature, a multi-range potential was devised to adjust the surface tension [Sbragaglia et al., Phys. Rev. E, 2007, 75, 026702; Sbragaglia et al. Soft Matter, 2012, 8, 10773]. However, this approach was found to be unable to keep the density ratio unchanged when the surface tension is adjusted. An alternative approach is therefore proposed in the present work. The basic strategy is to add a new source term to the LB equation so as to tune the surface tension of the pseudopotential LB model. The proposed approach can guarantee that the adjustment of the surface tension does not affect the mechanical stability condition of the pseudopotential LB model, and thus provides a separate c...
Diamond-turning HP-21 beryllium to achieve an optical surface
International Nuclear Information System (INIS)
Investigation of diamond turning on beryllium was made in anticipation of obtaining an optical finish. Although results of past experiences were poor, it was decided to continue diamond turning on beryllium beyond initial failures. By changing speed and using coolant, partial success was achieved. Tool wear was the major problem. Tests were made to establish and plot wear as a function of cutting speed and time. Slower speeds did cause lower wear rates, but at no time did wear reach an acceptable level. The machine, tools, and procedure used were chosen based on the results of preliminary attempts and on previous experience. It was unnecessary to use an air-bearing spindle because tool failure governed the best finish that could be expected. All tools of diamond composition, whether single crystal or polycrystalline, wore at unacceptable rates. Based on present technology, it must be concluded that beryllium cannot be feasibly diamond turned to achieve an optical finish. (22 fig.)
Wang, Jian-Ping; Chen, Yong-Zhen; Wang, Yi; Yuan, Shi-Jie; Yu, Han-Qing
2011-11-01
Pulp mill wastewater was treated using the coagulation-flocculation process with aluminum chloride as the coagulant and a modified natural polymer, starch-g-PAM-g-PDMC [polyacrylamide and poly (2-methacryloyloxyethyl) trimethyl ammonium chloride], as the flocculant. A novel approach with a combination of response surface methodology (RSM) and uniform design (UD) was employed to evaluate the effects and interactions of three main influential factors, coagulant dosage, flocculant dosage and pH, on the treatment efficiency in terms of the supernatant turbidity and lignin removals as well as the water recovery. The optimal conditions obtained from the compromise of the three desirable responses, supernatant turbidity removal, lignin removal and water recovery efficiency, were as follows: coagulant dosage of 871 mg/L, flocculant dosage of 22.3 mg/L and pH 8.35. Confirmation experiments demonstrated that such a combination of the UD and RSM is a powerful and useful approach for optimizing the coagulation-flocculation process for the pulp mill wastewater treatment. PMID:21920576
Achievable Efficiency of Numerical Methods for Simulations of Solar Surface Convection
Grimm-Strele, Hannes; Muthsam, Herbert J
2014-01-01
We investigate the achievable efficiency of both the time and the space discretisation methods used in Antares. We show that the fifth order variant of WENO combined with a second order Runge-Kutta scheme is not only more accurate than standard first and second order schemes, but also more efficient taking the computation time into account. Then, we calculate the error decay rates of WENO with several explicit Runge-Kutta schemes for advective and diffusive problems with smooth and non-smooth initial conditions. With this data, we estimate the computational costs of three-dimensional simulations and show that SSP RK(3,2) is the most efficient scheme considered in this comparison.
Sullivan, J. M.
2012-01-01
We use the lubrication approximation to analyze three closely related problems involving a thin rivulet or ridge (i.e., a two-dimensional droplet) of fluid subject to a prescribed uniform transverse shear stress at its free surface due to an external airflow, namely a rivulet draining under gravity down a vertical substrate, a rivulet driven by a longitudinal shear stress at its free surface, and a ridge on a horizontal substrate, and find qualitatively similar behaviour for all three problems. We show that, in agreement with previous numerical studies, the free surface profile of an equilibrium rivulet/ridge with pinned contact lines is skewed as the shear stress is increased from zero, and that there is a maximum value of the shear stress beyond which no solution with prescribed semi-width is possible. In practice, one or both of the contact lines will de-pin before this maximum value of the shear stress is reached, and so we consider situations in which the rivulet/ridge de-pins at one or both contact lines. In the case of de-pinning only at the advancing contact line, the rivulet/ridge is flattened and widened as the shear stress is increased from its critical value, and there is a second maximum value of the shear stress beyond which no solution with a prescribed advancing contact angle is possible. In contrast, in the case of de-pinning only at the receding contact line, the rivulet/ridge is thickened and narrowed as the shear stress is increased from its critical value, and there is a solution with a prescribed receding contact angle for all values of the shear stress. In general, in the case of de-pinning at both contact lines there is a critical "yield" value of the shear stress beyond which no equilibrium solution is possible and the rivulet/ridge will evolve unsteadily. In the Appendix, we show that an equilibrium rivulet/ridge with prescribed flux/area is quasi-statically stable to two-dimensional perturbations. © 2012 American Institute of Physics.
International Nuclear Information System (INIS)
Full text: Goat meat (chevon) is the costliest meat in Indian sub-continent due to its widen acceptance amongst the consumers. Behind this acceptance, its virtue over other meats, mainly because it is devoid of any religious restrictions is considered as one of the important factors to endow with nutrition to the human population. Indian sub-continent is having the highest number of goat 124.36 Million and about 36 percent of this population is slaughtered annually. Consumers demand safe and hygienic meat and it is the onus of the technocrats or the scientists to provide guarantee in this regard. It has been reported by a number of researchers that a major part of food borne interic infections could be transferred from the body of the animal to the meat. To avoid this situation a several technique of surface decontamination have been tried with varying degrees of success. Out of these, the chlorinated water was found to be effective and easy method; but, in course of time, its bleaching effect, preparation of its standardized solution and transfer of its certain odour to the carcass and subsequent to the meat put this technique on a question mark and obligated the scientist to take up this aspect of work for further analyses. With all these in perspectives and also to identify a simple, convenient to adopt, cheap and ecofriendly with hazardous left over effect and in consistent with the existing legislature, this work was outlined, where hot water (80 deg C), lactic acid, chlorine solution and acidified sodium chlorite solutions were used as surface decontaminants on chevon carcass. The work was designed to have a comparative study on the effect of different surface decontaminants, namely, hot water (80 deg C for 2 minutes), 2% lactic acid for 30 seconds, 1200 ppm acidified sodium chlorite (ASC) for 5 seconds and 50 ppm chlorine solution for 5 minutes in a form of dip and spray on the surface of dressed chevon carcass for 0, 24, 48 and 72 hours of storage. The
Li, Chunhui; Guan, Guangying; Huang, Zhihong; Wang, Ruikang K.; Nabi, Ghulam
2015-03-01
By combining with the phase sensitive optical coherence tomography (PhS-OCT), vibration and surface acoustic wave (SAW) methods have been reported to provide elastography of skin tissue respectively. However, neither of these two methods can provide the elastography in full skin depth in current systems. This paper presents a feasibility study on an optical coherence elastography method which combines both vibration and SAW in order to give the quantitative mechanical properties of skin tissue with full depth range, including epidermis, dermis and subcutaneous fat. Experiments are carried out on layered tissue mimicking phantoms and in vivo human forearm and palm skin. A ring actuator generates vibration while a line actuator were used to excited SAWs. A PhS-OCT system is employed to provide the ultrahigh sensitive measurement of the generated waves. The experimental results demonstrate that by the combination of vibration and SAW method the full skin bulk mechanical properties can be quantitatively measured and further the elastography can be obtained with a sensing depth from ~0mm to ~4mm. This method is promising to apply in clinics where the quantitative elasticity of localized skin diseases is needed to aid the diagnosis and treatment.
Hahn, William; Fairchild, Chris; Childs, R. Joseph
2015-01-01
This study investigated differences in Uniform Certified Public Accountant Exam (UCPAE) pass rates between candidates who graduated from Council for Christian Colleges & Universities member schools (CCCU-member) and candidates who graduated from institutions that are not CCCU members. The data set included 1,131 institutions (72,453…
Should Students Wear Uniforms?
Cohn, Carol A.; Siegel, Loren
1996-01-01
Two essays present opposing viewpoints on school uniforms. One suggests that uniforms make safer schools and better students. The other states that teenagers will rebel, and the uniform debate is a diversion from more pressing problems in education. The article includes brief opinion statements from teachers and other professionals. (SM)
White, Kerry A.
2000-01-01
In 1994, Long Beach (California) Unified School District began requiring uniforms in all elementary and middle schools. Now, half of all urban school systems and many suburban schools have uniform policies. Research on uniforms' effectiveness is mixed. Tightened dress codes may be just as effective and less litigious. (MLH)
Dowling-Sendor, Benjamin
2002-01-01
Reviews a recent decision in "Littlefield" by the 5th Circuit upholding a school uniform policy. Advises board member who wish to adopt a school uniform policy to solicit input from parents and students, research the experiences of other school districts with uniform policies, and articulate the interests they wish to promote through uniform…
Cohn, Carl A.
1996-01-01
Shortly after implementing a mandatory school uniform policy, the Long Beach (California) Public Schools can boast 99% compliance and a substantial reduction in school crime. The uniforms can't be confused with gang colors, save parents money, and help identify outsiders. A sidebar lists ingredients for a mandatory uniform policy. (MLH)
Directory of Open Access Journals (Sweden)
Elena eBoccardi
2015-11-01
Full Text Available The design and characterization of a new family of multifunctional scaffolds based on bioactive glass (BG of 45S5 composition for bone tissue engineering and drug delivery applications is presented. These BG-based scaffolds are developed via a replication method of polyurethane packaging foam. In order to increase the therapeutic functionality, the scaffolds were coated with mesoporous silica particles (MCM-41, which act as an in-situ drug delivery system. These sub-micron spheres are characterized by large surface area and pore volume with a narrow pore diameter distribution. The solution used for the synthesis of the silica mesoporous particles was designed to obtain at the same time a high ordered mesoporous structure and spherical shape, both are key factors for achieving the desired controlled drug release. The MCM-41 particles were synthesized directly inside the BG-based scaffolds and the drug release capability of this combined system was evaluated. Moreover the effect of MCM-41 particle coating on the bioactivity of the BG-based scaffolds was assessed. The results indicate that it is possible to obtain a multifunctional scaffold system characterized by high and interconnected porosity, high bioactivity and sustained drug delivery capability.
Boccardi, Elena; Philippart, Anahí; Juhasz-Bortuzzo, Judith A.; Beltrán, Ana M.; Novajra, Giorgia; Vitale-Brovarone, Chiara; Spiecker, Erdmann; Boccaccini, Aldo R.
2015-01-01
The design and characterization of a new family of multifunctional scaffolds based on bioactive glass (BG) of 45S5 composition for bone tissue engineering and drug delivery applications are presented. These BG-based scaffolds are developed via a replication method of polyurethane packaging foam. In order to increase the therapeutic functionality, the scaffolds were coated with mesoporous silica particles (MCM-41), which act as an in situ drug delivery system. These sub-micron spheres are characterized by large surface area and pore volume with a narrow pore diameter distribution. The solution used for the synthesis of the silica mesoporous particles was designed to obtain a high-ordered mesoporous structure and spherical shape – both are key factors for achieving the desired controlled drug release. The MCM-41 particles were synthesized directly inside the BG-based scaffolds, and the drug-release capability of this combined system was evaluated. Moreover, the effect of MCM-41 particle coating on the bioactivity of the BG-based scaffolds was assessed. The results indicate that it is possible to obtain a multifunctional scaffold system characterized by high and interconnected porosity, high bioactivity, and sustained drug delivery capability. PMID:26594642
School Uniform Policies in Public Schools
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…
Is the Target of 1 Day of Stay per 1% Total Body Surface Area Burned Achieved in Chemical Burns?
Tan, Teresa; Wong, David S Y
2016-02-01
The length of hospital stay (LOS) is a standard parameter used to reflect quality and evaluate outcomes in acute burn care. This study aims to assess whether the target of 1 day of stay per 1% total body surface area (TBSA) burned was achieved in acute chemical burns management and factors affecting the LOS. A retrospective analysis of the records of patients who suffered from chemical burn injuries admitted to a university burn center over a continuous 14-year period was performed.A total of 118 patients were admitted over the period for chemical burns. Only 14% of cases achieved the target stated. Factors associated with lengthening of the hospital stay included TBSA, ocular involvement, the cause of injury, and the need for surgery during the same admission.The LOS in chemical burns frequently exceeds 1 day of stay per 1% TBSA burned. Many factors can contribute to a patient's LOS and are worth exploring in order to see if the impact of these factors could be minimized. Early surgical intervention should help to reduce the LOS if reliable methods of burn wound depth assessment are available.
Uniform Practical Nonlinear Output Regulation
Marconi, Lorenzo; Praly, Laurent
2008-01-01
International audience In this paper, we present a solution to the problem of asymptotic and practical semiglobal regulation by output feedback for nonlinear systems. A key feature of the proposed approach is that practical regulation is achieved uniformly with respect to the dimension of the internal model and to the gain of the stabilizer near the zero error manifold. This property renders the approach interesting for a number of real cases by bridging the gap between output regulation t...
Directory of Open Access Journals (Sweden)
Hongyan Yang
2014-12-01
Full Text Available We propose a novel metal-coupled metal-insulator-metal (MC-MIM waveguide which can achieve a highly efficient surface plasmon polaritons (SPPs excitation. The MC-MIM waveguide is formed by inserting a thin metal film in the insulator of an MIM. The introduction of the metal film, functioning as an SPPs coupler, provides a space for the interaction between SPPs and a confined electromagnetic field of the intermediate metal surface, which makes energy change and phase transfer in the metal-dielectric interface, due to the joint action of incomplete electrostatic shielding effect and SPPs coupling. Impacts of the metal film with different materials and various thickness on SPPs excitation are investigated. It is shown that the highest efficient SPPs excitation is obtained when the gold film thickness is 60 nm. The effect of refractive index of upper and lower symmetric dielectric layer on SPPs excitation is also discussed. The result shows that the decay value of refractive index is 0.3. Our results indicate that this proposed MC-MIM waveguide may offer great potential in designing a new SPPs source.
Indian Academy of Sciences (India)
Sunita Rani; Ram Chander Verma
2013-08-01
The solution of the static deformation of a homogeneous, isotropic, perfectly elastic half-space caused by uniform movement along a long vertical tensile fracture is well known. In this paper, we study the problem of static deformation of a homogeneous, isotropic, perfectly elastic half-space caused by a nonuniform movement along a long vertical tensile fracture of infinite length and finite depth. Four movement profiles are considered: linear, parabolic, elliptic and cubic. The deformation corresponding to the four non-uniform movement profiles is compared numerically with the deformation due to a uniform case, assuming the source potency to be the same. The equality in source potency is achieved in two ways: One, by varying the depth of fracture and keeping the surface discontinuity constant and the other way, by keeping the depth of fracture constant and varying the surface discontinuity. It is found that the effect of non-uniformity in movement in the near field is noteworthy. The far field is not affected significantly by the non-uniformity in movement. In the first case, horizontal displacement is significantly affected rather than vertical displacement. In the second case, non-uniformity in movement changes the magnitude of the displacement at the surface. Also, the displacements around a long vertical tensile fracture for different movement profiles are plotted in three dimensions.
International Nuclear Information System (INIS)
Graphical abstract: Li1.2Mn0.52Co0.08Ni0.2O2 cathode material uniformly nanocoated with samarium fluoride (SmF3) has been successfully synthesized through a chemical deposition method followed by low-temperature hydrothermal treatment. The surface modified cathode shows a significantly improved cycling stability and rate capability. - Highlights: • Samarium fluoride is originally used as coating material of Li-rich layered cathode. • Low-temperature hydrothermal treatment is employed to establish uniform surface coating. • Cathode nanocoated with SmF3 shows improved rate capability and cycling stability. • Coating material suppresses the side reaction between electrode and electrolyte. - Abstract: Surface nanocoating of lithium-rich layered Li1.2Mn0.52Co0.08Ni0.2O2 with samarium fluoride (SmF3) has been performed through a chemical deposition route combined with a low-temperature hydrothermal treatment. The surface-modified Li1.2Mn0.52Co0.08Ni0.2O2 particles are uniformly and completely covered by an amorphous SmF3 protective layer with a thin thickness of ∼20 nm. After surface modification, the coated Li1.2Mn0.52Co0.08Ni0.2O2 as cathode shows a significantly improved cycling stability, keeping a capacity retention of 84.5% after 150 cycles at 2 C, much higher than 68.9%forits uncoated counterpart. Moreover, the coated sample delivers an enhanced rate capability with an average capacity of ∼132.3 mA h g−1 when charged at 5 C and discharged at 0.2 C, while the uncoated counterpart only exhibits a capacity of ∼111.4 mA h g−1 under the same conditions. Our results reveal that the remarkably improved electrochemical performance of the surface-modified cathode is attributed to the presence of uniform, robust, and nanoscale SmF3 coating layer, which not only suppresses the growth of SEI layer by reducing the side reaction between cathode and electrolyte solution, but also strengthens the structure stability of the Li-rich layered cathode materials
Institute of Scientific and Technical Information of China (English)
Linda
2008-01-01
The uniforms for Beijing Olympics’ workers, technical staff and volunteers have been unveiled to mark the 200-day countdown to the Games. The uniforms feature the key element of the clouds of promise and will be in three colors:red for Beijing Olympic Games Committee staff, blue
Institute of Scientific and Technical Information of China (English)
张少强; 徐少春; 沈小军; 高阳; 伍成波
2011-01-01
The performance of pumping and airblast style U-type radiant tube heating unit was studied,and the temperature uniformity of the radiant tube surface and the factors affecting the temperature distribution were studied mainly. It was found that the temperature uniformity of the radiant tube surface could be regulated accessorially by regulating the quantity of the primary air and the second air, when the structure of burner was definite. With the rise of the preheated air temperature and the temperature in the heating furnace, the temperature uniformity of radiant tube surface also could be improved. Whereas the effect of the zero pressure location was not obvious to the temperature distribution of the radiant tube surface.%对抽-鼓式U型辐射管加热装置进行了研究,主要研究了辐射管表面温度的均匀性及其影响因素.实验研究表明:当燃烧器结构一定时,调节一、二次进风量的配比,可辅助性的调节辐射管表面温度的均匀性.随着空气预热温度及炉膛温度的升高,同样能改善辐射管表面温度的均匀性.而辐射管内零压面的位置对辐射管表面温度分布的影响很小.
Jiang, Wenting; Fu, Yuanting; Yang, Fang; Yang, Yufeng; Liu, Ting; Zheng, Wenjie; Zeng, Lilan; Chen, Tianfeng
2014-08-27
The poor permeability of glioma parenchyma represents a major limit for antiglioblastoma drug delivery. Gracilaria lemaneiformis polysaccharide (GLP), which has a high binding affinity to αvβ3 integrin overexpressed in glioma cells, was employed in the present study to functionalize selenium nanoparticles (SeNPs) to achieve antiglioblastoma efficacy. GLP-SeNPs showed satisfactory size distribution, high stability, and selectivity between cancer and normal cells. In U87 glioma cell membrane, which has a high integrin expression level, GLP-SeNPs exhibited significantly higher cellular uptake than unmodified SeNPs. As expected, U87 cells exhibited a greater uptake of GLP-SeNPs than C6 cells with low integrin expression level. Furthermore, the internalization of GLP-SeNPs was inhibited by cyclo-(Arg-Gly-Asp-Phe-Lys) peptides, suggesting that cellular uptake into U87 cells and C6 cells occurred via αvβ3 integrin-mediated endocytosis. For U87 cells, the cytotoxicity of SeNPs decorated by GLP was enhanced significantly because of the induction of various apoptosis signaling pathways. Internalized GLP-SeNPs triggered intracellular reactive oxygen species downregulation. Therefore, p53, MAPKs, and AKT pathways were activated to advance cell apoptosis. These findings suggest that surface decoration of nanomaterials with GLP could be an efficient strategy for design and preparation of glioblastoma targeting nanodrugs.
Shaoming, Bao; Yabing, Ke; Yanqing, Zheng; Lina, Cheng; Honglang, Li
2016-02-01
To achieve the monotonic frequency-temperature response for a high-temperature langasite (LGS) surface-acoustic-wave (SAW) sensor in a wide temperature range, a method utilizing two substrate cuts with different propagation angles on the same substrate plane was proposed. In this method, the theory of effective permittivity is adopted to calculate the temperature coefficients of frequency (TCF), electromechanical coupling coefficients (k2), and power flow angle (PFA) for different propagation angles on the same substrate plane, and then the two substrate cuts were chosen to have large k2 and small PFA, as well as the difference in their TCFs (ΔTCF) to always have the same sign of their values. The Z-cut LGS substrate plane was taken as an example, and the two suitable substrate cuts with propagation angles of 74 and 80° were chosen to derive a monotonic frequency-temperature response for LGS SAW sensors at -50 to 540 °C. Experiments on a LGS SAW sensor using the above two substrate cuts were designed, and its measured frequency-temperature response at -50 to 540 °C agreed well with the theory, demonstrating the high accuracy of the proposed method.
Zainol, Ismail; Yaakob, Omar
2016-06-01
Fishing is a major local industry in Malaysia, particularly in rural areas. However, the rapidly increasing price of fuel is seriously affecting the industry's viability. At present, outboard petrol engines are the preferred choice for use in small-scale fishing boats because they deliver the advantages of high speed and low weight, they are easy to install, and they use minimal space. Petrol outboard engines are known to consume a greater amount of fuel than inboard diesel engines, but installing diesel engines with conventional submerged propellers in existing small-scale fishing boats is not economically viable because major hullform modifications and extra expenditure are required to achieve this. This study describes a proposal to enable reductions in fuel consumption by introducing the combined use of a diesel engine and surface-piercing propeller (SPP). An analysis of fuel consumption reduction is presented, together with an economic feasibility study. Resulting data reveal that the use of the proposed modifications would save 23.31 liters of fuel per trip (40.75 %) compared to outboard motors, equaling annual savings of RM 3962 per year.
Jiang, Wenting; Fu, Yuanting; Yang, Fang; Yang, Yufeng; Liu, Ting; Zheng, Wenjie; Zeng, Lilan; Chen, Tianfeng
2014-08-27
The poor permeability of glioma parenchyma represents a major limit for antiglioblastoma drug delivery. Gracilaria lemaneiformis polysaccharide (GLP), which has a high binding affinity to αvβ3 integrin overexpressed in glioma cells, was employed in the present study to functionalize selenium nanoparticles (SeNPs) to achieve antiglioblastoma efficacy. GLP-SeNPs showed satisfactory size distribution, high stability, and selectivity between cancer and normal cells. In U87 glioma cell membrane, which has a high integrin expression level, GLP-SeNPs exhibited significantly higher cellular uptake than unmodified SeNPs. As expected, U87 cells exhibited a greater uptake of GLP-SeNPs than C6 cells with low integrin expression level. Furthermore, the internalization of GLP-SeNPs was inhibited by cyclo-(Arg-Gly-Asp-Phe-Lys) peptides, suggesting that cellular uptake into U87 cells and C6 cells occurred via αvβ3 integrin-mediated endocytosis. For U87 cells, the cytotoxicity of SeNPs decorated by GLP was enhanced significantly because of the induction of various apoptosis signaling pathways. Internalized GLP-SeNPs triggered intracellular reactive oxygen species downregulation. Therefore, p53, MAPKs, and AKT pathways were activated to advance cell apoptosis. These findings suggest that surface decoration of nanomaterials with GLP could be an efficient strategy for design and preparation of glioblastoma targeting nanodrugs. PMID:25073123
Aminfar, H.; Mohammadpourfard, M.; Khajeh, K.
2016-01-01
Effect of geometry on the atherosclerosis is a significant issue, so the 3D s-shape and 2D axisymmetric stenosis tube as a blood vessel have been analyzed in this work. This paper has focused on the most important parameters in the LSC uptake, inlet Re number and infiltration velocity in the presence of non-uniform magnetic field. The magnetic field is arising from the thin wire with electric current placed vertically to the arterial blood vessel. According to the results of this study, applying magnetic field can be a treatment for atherosclerosis by reducing LSC along the vessel wall. It is observed that, application of magnetic field leads to production of a vortex in the flow, high strain rate, increment of WSS, and also reduction in LSC. For solving the mass transport equation, Lumen-wall model has been used. Blood flow has been considered laminar and incompressible containing Ferro fluid (blood and 4 vol% Fe3O4) under steady state conditions. Numerical solution of governing equations was obtained by using the single-phase model and control volume technique for flow field.
Rodiet, Christophe; Remy, Benjamin; Degiovanni, Alain
2016-05-01
In this paper, it is shown how to select the optimal wavelengths minimizing the relative error and the standard deviation of the temperature. Furthermore, it is shown that the optimal wavelengths in mono-spectral and bi-spectral methods (for a Planck's law) can be determined by laws analogous to the displacement Wien's law. The simplicity of these laws can thus allow real-time selection of optimal wavelengths for a control/optimization of industrial processes, for example. A more general methodology to obtain the optimal wavelengths selection in a multi-spectral method (taking into account the spectral variations of the global transfer function including the emissivity variations) for temperature measurement of surfaces exhibiting non-uniform emissivity, is also presented. This latter can then find an interest in glass furnaces temperature measurement with spatiotemporal non-uniformities of emissivity, the control of biomass pyrolysis, the surface temperature measurement of buildings or heating devices, for example. The goal consists of minimizing the standard deviation of the estimated temperature (optimal design experiment). For the multi-spectral method, two cases will be treated: optimal global and optimal constrained wavelengths selection (to the spectral range of the detector, for example). The estimated temperature results obtained by different models and for different number of parameters and wavelengths are compared. These different points are treated from theoretical, numerical and experimental points of view.
Energy Technology Data Exchange (ETDEWEB)
Cabrera, Lourdes I., E-mail: lourisa_cabrera@yahoo.com [Universita degli Studi di Firenze, LA.M.M. c/o dipartimento di Chimica (Italy); Somoza, Alvaro [Faculty of Science Module C-IX, Instituto Madrileno de Estudios Avanzados-Nanociencia (Spain); Marco, Jose F. [Instituto de Quimica-Fisica ' ROCASOLANO' , CSIC (Spain); Serna, Carlos J.; Puerto Morales, M. [Instituto de Ciencia de Materiales de Madrid, CSIC (Spain)
2012-06-15
Cubic monodisperse MFe{sub 2}O{sub 4} ferrite nanoparticles (M = Fe, Co, and Mn) with tunable sizes between 7 and 20 nm and a narrow size distribution have been achieved in a one step synthesis by thermal decomposition of Fe(III), Co (II), and Mn(II) oleates. These nanoparticles have been functionalized with dimercaptosuccinic acid (DMSA), 11-mercaptoundecanoic acid (MUA), and bis(carboxymethyl)(2-maleimidylethyl)ammonium 4-toluenesulfonate (MATS) to grant them aqueous stability and the possibility for further functionalization with different biomolecules. Their structural, magnetic, and colloidal properties have also been studied to determine their chemical and physical properties and the degree of stability under physiological conditions that will determine their future use in biomedical applications.
International Nuclear Information System (INIS)
Cubic monodisperse MFe2O4 ferrite nanoparticles (M = Fe, Co, and Mn) with tunable sizes between 7 and 20 nm and a narrow size distribution have been achieved in a one step synthesis by thermal decomposition of Fe(III), Co (II), and Mn(II) oleates. These nanoparticles have been functionalized with dimercaptosuccinic acid (DMSA), 11-mercaptoundecanoic acid (MUA), and bis(carboxymethyl)(2-maleimidylethyl)ammonium 4-toluenesulfonate (MATS) to grant them aqueous stability and the possibility for further functionalization with different biomolecules. Their structural, magnetic, and colloidal properties have also been studied to determine their chemical and physical properties and the degree of stability under physiological conditions that will determine their future use in biomedical applications.
Uniform and Robust Peptoid Microsphere Coatings
Servoss, Shannon L.; Phillip Blake; Melissa L. Hebert; Dhaval S. Shah
2013-01-01
Peptoids that are helical and partially water soluble have been shown to self-assemble into microspheres when the peptoid solution is dried on a silicon substrate. Such microsphere coatings have great potential for use in biosensor technologies, specifically to increase the surface area for binding. However, in order to be useful, the peptoids must consistently form uniform coatings. In this study we investigated the effects of various coating protocol parameters on the uniformity of the resu...
H. Buhrman; B. Hescott; S. Homer; L. Torenvliet
2010-01-01
We study properties of non-uniform reductions and related completeness notions. We strengthen several results of Hitchcock and Pavan (ICALP (1), Lecture Notes in Computer Science, vol. 4051, pp. 465-476, Springer, 2006) and give a trade-off between the amount of advice needed for a reduction and its
International Nuclear Information System (INIS)
Surface-enhanced Raman spectroscopy (SERS) is a powerful vibrational spectroscopy technique for highly sensitive structural detection of low concentration analyte. The SERS activities largely depend on the topography of the substrate. In this review, we summarize the recent progress in SERS substrate, especially focusing on the three-dimensional (3D) noble-metal substrate with hierarchical nanostructure. Firstly, we introduce the background and general mechanism of 3D hierarchical SERS nanostructures. Then, a systematic overview on the fabrication, growth mechanism, and SERS property of various noble-metal substrates with 3D hierarchical nanostructures is presented. Finally, the applications of 3D hierarchical nanostructures as SERS substrates in many fields are discussed. (invited review — international conference on nanoscience and technology, china 2013)
International Nuclear Information System (INIS)
Highlights: • A simple hydrothermal method was used to produce carbon nanospheres (CNSs). • The size of CNSs was controlled by the concentration of initial sucrose solution. • The size of CNSs was reduced to 100 nm by post-annealing of the CNSs. • A glass substrate was coated with CNSs thick film using spin coating method. • Contact angle of a water droplet was 153° indicating the film is super-hydrophobic. - Abstract: A simple hydrothermal method was used to produce high yield, monodisperse and tightly controllable size of carbon nanospheres (CNSs) by adjusting the concentration of initial sucrose solution in a sealed autoclave at 170 °C for 8 h. By changing the solution concentration from 0.5 to 0.1 mol l−1, the sizes of carbon spheres (CS) were reduced from about 2500 to about 300 nm. Also by increasing the solution volume to the vessel volume ratio (Vs/Vv) from 5/6 to 11/13, the yield of CS was increased from 25% up to about 55% of initial raw materials. It was found that by post-annealing of the 300 nm CNSs at 435 °C for 30 min, their diameters were reduced to 100 nm. Moreover, annealing in air atmosphere had a noticeable influence on the surface functional groups and bonds of CNSs. In addition, CNSs were used to fabricate hydrophobic surfaces by coating their ethanolic colloidal solution on glass substrates. The measured contact angle (CA) of a water droplet was about 153°, indicating that the CNSs thick layers were super-hydrophobic. The size dependence of CNSs on the different parameters has been discussed
Energy Technology Data Exchange (ETDEWEB)
Joula, Mohsen Heidari; Farbod, Mansoor, E-mail: farbod_m@scu.ac.ir
2015-08-30
Highlights: • A simple hydrothermal method was used to produce carbon nanospheres (CNSs). • The size of CNSs was controlled by the concentration of initial sucrose solution. • The size of CNSs was reduced to 100 nm by post-annealing of the CNSs. • A glass substrate was coated with CNSs thick film using spin coating method. • Contact angle of a water droplet was 153° indicating the film is super-hydrophobic. - Abstract: A simple hydrothermal method was used to produce high yield, monodisperse and tightly controllable size of carbon nanospheres (CNSs) by adjusting the concentration of initial sucrose solution in a sealed autoclave at 170 °C for 8 h. By changing the solution concentration from 0.5 to 0.1 mol l{sup −1}, the sizes of carbon spheres (CS) were reduced from about 2500 to about 300 nm. Also by increasing the solution volume to the vessel volume ratio (V{sub s}/V{sub v}) from 5/6 to 11/13, the yield of CS was increased from 25% up to about 55% of initial raw materials. It was found that by post-annealing of the 300 nm CNSs at 435 °C for 30 min, their diameters were reduced to 100 nm. Moreover, annealing in air atmosphere had a noticeable influence on the surface functional groups and bonds of CNSs. In addition, CNSs were used to fabricate hydrophobic surfaces by coating their ethanolic colloidal solution on glass substrates. The measured contact angle (CA) of a water droplet was about 153°, indicating that the CNSs thick layers were super-hydrophobic. The size dependence of CNSs on the different parameters has been discussed.
Directory of Open Access Journals (Sweden)
M.A. Samad
2013-01-01
Full Text Available An analysis is carried out to investigate the effects of MHD free convection heat transfer of power-law non-Newtonian fluids along a stretching sheet. This has been done under the simultaneous action of suction, heat generation/absorption, thermal radiation and uniform transverse magnetic field. The stretching sheet is assumed to continuously moving with a power-law velocity and maintaining a uniform surface heat flux. The governing nonlinear partial differential equations are transformed into a system of nonlinear ordinary differential equations using appropriate similarity transformations. The resulting non-linear equations are solved numerically using Nachtsheim-Swigert shooting iterative technique along with sixth order Runge-Kutta integration scheme. Numerical results for the non-dimensional velocity and temperature profiles are shown graphically and discussed. The effects of skin-friction coefficient and the local Nusselt number which are of physical and engineering interest are studied and presented graphically as well as in the form of tables for the variation of different physically important parameters. A comparison of the present study is also performed with the previously published study and found excellent agreement.
Energy Technology Data Exchange (ETDEWEB)
Jing, Qiang; Yang, Hang; Li, Wancheng, E-mail: liwc@jlu.edu.cn; Wu, Guoguang, E-mail: wugg@jlu.edu.cn; Zhang, Yuantao; Gao, Fubin; Zhao, Yang; Du, Guotong
2015-03-15
Highlights: • High density uniform InN nanocolumns were obtained on p-GaAs(0 0 1) substrate. • Indium beam irradiation method had improved the crystal quality largely. • Stoichiometric ratio of all InN samples was close to 1:1 gotten by in situ XPS spectra. - Abstract: Through Indium beam irradiation toward the substrate before growing, high density uniform InN nanocolumns were obtained on p-GaAs(0 0 1) substrate and their possible one dimensional (1D) growth mechanism was analyzed. Rocking curves of all samples showed that Indium beam irradiation method had improved the crystal quality largely, which might be an effective way to release the strain between hexagonal InN(0 0 0 1) and cubic GaAs(0 0 1) with large lattice mismatch. Through quantitative analysis of XPS spectra gotten by in situ measurement, it was found that the InN stoichiometric ratio of all three samples were close to 1:1, which revealed that there was no residual metal at the tip of our nanocolumns. No catalyst or residual metal left could keep its electronic and optical property intact. All three samples showed strong photoluminescence at room temperature. To effectively release the strain and get well surface and interface are important for heterojunction optoelectronic device based on InN.
High-voltage electrode optimization towards uniform surfacetreatment by a pulsed volume discharge
Ponomarev, A. V.; Pedos, M. S.; Scherbinin, S. V.; Mamontov, Y. I.; Ponomarev, Sergey Viktorovich
2015-01-01
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 r...
Pemantle, Robin
2004-01-01
There are several good reasons you might want to read about uniform spanning trees, one being that spanning trees are useful combinatorial objects. Not only are they fundamental in algebraic graph theory and combinatorial geometry, but they predate both of these subjects, having been used by Kirchoff in the study of resistor networks. This article addresses the question about spanning trees most natural to anyone in probability theory, namely what does a typical spanning tree look like?
Hanna Karaszewska; Maciej Muskała
2012-01-01
The article discusses the problems of women who work in the uniformed services with the particular emphasis on the performing of the occupation of the prison service. It presents the legal issues relating to equal treatment of men and women in the workplace, formal factors influencing their employment, the status of women in prison, and the problems of their conducting in the professional role. The article also presents the results of research conducted in Poland and all over the world, on th...
Uniform Requirements for Manuscripts
Institute of Scientific and Technical Information of China (English)
2011-01-01
@@ Introduction The Uniform requirements are instructions to authors on how to prepare manuscripts.If authors prepare their manuscripts in the style specified in these requirements, editors of the participating journals will not return the manuscripts for changes in style before considering them for publication.In the publishing process, however, the journals may alter accepted manuscripts to conform with details of their publication styles.
Shaikh, Shazia; Singh, Anil Kumar; Sharma, Kuldeep; Sinha, Sucharita
2016-01-01
45S5 Hench bio-glass (BG) has gained interest in research because of its potential clinical applications. Several studies in-vivo and in-vitro have been in progress to improve bio-integration efficiency of this glass. In present contribution, surface modification of Hench BG has been done employing a femtosecond (fs) laser beam, resulting in increased effective surface area of the sample. These surface modified samples were subsequently immersed in simulated body fluid for varying number of days and characterized using Scanning electron microscope, energy dispersive X-ray analysis, X-ray diffraction, and micro-Raman spectroscopy. In-vitro studies indicated superior growth of hydroxyapatite (HAP) layer on the laser treated samples in comparison to the untreated samples. Presence of strong XRD peaks confirmed faster growth of HAP on laser treated samples. Raman peaks, five times more intense and relatively narrower represented higher crystallinity of hydroxyapatite layer on laser treated BG.
23 CFR 655.604 - Achieving basic uniformity.
2010-04-01
... Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS TRAFFIC OPERATIONS Traffic Control Devices on Federal-Aid and Other Streets and Highways § 655.604... traffic control devices or the installation of needed traffic control devices on or off the...
Energy Technology Data Exchange (ETDEWEB)
Worley, C.M.
1986-05-07
The objective of this research was to: (1) determine the nature of a thin coating on an explosive material which was applied using a starved addition microencapsulation technique, (2) understand the coating/crystal bond, and (3) investigate the wettability/adhesion of plastic/solvent combinations using the coating process. The coating used in this work was a Firestone Plastic Company copolymer (FPC-461) of vinylchloride/trifluorochloroethylene in a 1.5/1.0 weight ratio. The energetic explosive examined was pentaerythritoltetranitrate (PETN). The coating process used was starved addition followed by a solvent evaporation technique. Surface analytical studies, completed for characterization of the coating process, show (1) evidence that the polymer coating is present, but not continuous, over the surface of PETN; (2) the average thickness of the polymer coating is between 16-32 A and greater than 44 A, respectively, for 0.5 and 20 wt % coated PETN; (3) no changes in surface chemistry of the polymer or the explosive material following microencapsulation; and (4) the presence of explosive material on the surface of 0.5 wt % FPC-461 coated explosives. 5 refs., 15 figs., 6 tabs.
Uniform distribution of sequences
Kuipers, L
2006-01-01
The theory of uniform distribution began with Hermann Weyl's celebrated paper of 1916. In later decades, the theory moved beyond its roots in diophantine approximations to provide common ground for topics as diverse as number theory, probability theory, functional analysis, and topological algebra. This book summarizes the theory's development from its beginnings to the mid-1970s, with comprehensive coverage of both methods and their underlying principles.A practical introduction for students of number theory and analysis as well as a reference for researchers in the field, this book covers un
Energy Technology Data Exchange (ETDEWEB)
Giovannini, Massimo, E-mail: massimo.giovannini@cern.ch [Department of Physics, Theory Division, CERN, 1211 Geneva 23 (Switzerland); INFN, Section of Milan-Bicocca, 20126 Milan (Italy)
2015-06-30
Cosmological singularities are often discussed by means of a gradient expansion that can also describe, during a quasi-de Sitter phase, the progressive suppression of curvature inhomogeneities. While the inflationary event horizon is being formed the two mentioned regimes coexist and a uniform expansion can be conceived and applied to the evolution of spatial gradients across the protoinflationary boundary. It is argued that conventional arguments addressing the preinflationary initial conditions are necessary but generally not sufficient to guarantee a homogeneous onset of the conventional inflationary stage.
Directory of Open Access Journals (Sweden)
Hanna Karaszewska
2012-12-01
Full Text Available The article discusses the problems of women who work in the uniformed services with the particular emphasis on the performing of the occupation of the prison service. It presents the legal issues relating to equal treatment of men and women in the workplace, formal factors influencing their employment, the status of women in prison, and the problems of their conducting in the professional role. The article also presents the results of research conducted in Poland and all over the world, on the functioning of women in prison and their relations with officers of the Prison Service, as well as with inmates.
Energy Technology Data Exchange (ETDEWEB)
Amore, Paolo; Saenz, Ricardo A; Salvo, Koen [Facultad de Ciencias, CUICBAS, Universidad de Colima, Bernal DIaz del Castillo 340 Colima, Colima (Mexico); Fernandez, Francisco M [INIFTA (UNLP, CCT La Plata-Conicet), Diag. 113 y 64 S/N, Sucursal 4, Casilla de Correo 16, 1900 La Plata (Argentina)], E-mail: paolo.amore@gmail.com, E-mail: fernande@quimica.unlp.edu.ar, E-mail: rasaenz@ucol.mx, E-mail: koen.salvo@gmail.com
2009-03-20
In this paper we derive four sets of sinc-like functions, defined on a finite interval and obeying different boundary conditions. The functions in each set are orthogonal and their nodes are uniformly distributed on the interval. We have applied each set to solve a large class of eigenvalue equations, with different boundary conditions, both on finite intervals and on the real line, showing that precise numerical results can be obtained efficiently and rapidly. A comparison with results available in the literature is also performed.
Design and performance of high uniformity linear filament electron gun
Iqbal, Munawar; Fazal-e-Aleem
2006-10-01
We describe new features and results from the previously reported [M. Iqbal et al., Rev. Sci. Instrum. 74, 4616 (2003)] thermionic long (up to 140mm) cathode, electromagnetically focused electron beam gun. The gun which was tested up to 50kW (5000mA×10kV) achieves power density of 33kW/cm2 at the target. The cathode temperature and emission current was uniform over a length of 100mm of the cathode. The beam density profile along the line cathode strongly relates to the temperature distribution along the line cathode. The gun has a remarkable application in heat treatment of large surface area and to coat large substrate surfaces at much faster evaporation rates with lower cost.
Lin, Chin-An; Tsai, Meng-Lin; Wei, Wan-Rou; Lai, Kun-Yu; He, Jr-Hau
2016-01-26
Fused-silica packaging glass fabricated with a hierarchical structure by integrating small (ultrathin nanorods) and large (honeycomb nanowalls) structures was demonstrated with exceptional light-harvesting solar performance, which is attributed to the subwavelength feature of the nanorods and an efficient scattering ability of the honeycomb nanowalls. Si solar cells covered with the hierarchically structured packaging glass exhibit enhanced conversion efficiency by 5.2% at normal incidence, and the enhancement went up to 46% at the incident angle of 60°. The hierarchical structured packaging glass shows excellent self-cleaning characteristics: 98.8% of the efficiency is maintained after 6 weeks of outdoor exposure, indicating that the nanostructured surface effectively repels polluting dust/particles. The presented self-cleaning omnidirectional light-harvesting design using the hierarchical structured packaging glass is a potential universal scheme for practical solar applications. PMID:26623934
Huang, Jianfeng
2015-08-13
Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core–shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy that are some 30-fold higher than that of AuNR@Au. When incubated with a H2O2 solution (0.5 m), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620–690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.
Elimination of Quench Cracking by Controlling Agitation Uniformity
Institute of Scientific and Technical Information of China (English)
CANALE, Lauralice C.F; TOTTEN, George E
2004-01-01
Uniform agitation of the quenchant is a critically important control parameter in optimizing distortion control and reducing steel cracking. Quenching with ultrasonic agitation or in the presence of electrical and magnetic fields provide uniform agitation leading to improved uniformity of the stress fields within the metal not readily achievable with more traditional agitation methods such as propeller pumps and sprays. These methods provide the additional potential advantage of varying agitation throughout the cooling cycle to achieve a wide range of cooling profiles not readily achievable with quenchants and more traditional agitation systems currently in use.
Uniformly rotating neutron stars
Boshkayev, Kuantay
2016-01-01
In this chapter we review the recent results on the equilibrium configurations of static and uniformly rotating neutron stars within the Hartle formalism. We start from the Einstein-Maxwell-Thomas-Fermi equations formulated and extended by Belvedere et al. (2012, 2014). We demonstrate how to conduct numerical integration of these equations for different central densities ${\\it \\rho}_c$ and angular velocities $\\Omega$ and compute the static $M^{stat}$ and rotating $M^{rot}$ masses, polar $R_p$ and equatorial $R_{\\rm eq}$ radii, eccentricity $\\epsilon$, moment of inertia $I$, angular momentum $J$, as well as the quadrupole moment $Q$ of the rotating configurations. In order to fulfill the stability criteria of rotating neutron stars we take into considerations the Keplerian mass-shedding limit and the axisymmetric secular instability. Furthermore, we construct the novel mass-radius relations, calculate the maximum mass and minimum rotation periods (maximum frequencies) of neutron stars. Eventually, we compare a...
Uniform quantized electron gas.
Høye, Johan S; Lomba, Enrique
2016-10-19
In this work we study the correlation energy of the quantized electron gas of uniform density at temperature T = 0. To do so we utilize methods from classical statistical mechanics. The basis for this is the Feynman path integral for the partition function of quantized systems. With this representation the quantum mechanical problem can be interpreted as, and is equivalent to, a classical polymer problem in four dimensions where the fourth dimension is imaginary time. Thus methods, results, and properties obtained in the statistical mechanics of classical fluids can be utilized. From this viewpoint we recover the well known RPA (random phase approximation). Then to improve it we modify the RPA by requiring the corresponding correlation function to be such that electrons with equal spins can not be on the same position. Numerical evaluations are compared with well known results of a standard parameterization of Monte Carlo correlation energies. PMID:27546166
Uniform quantized electron gas
Høye, Johan S.; Lomba, Enrique
2016-10-01
In this work we study the correlation energy of the quantized electron gas of uniform density at temperature T = 0. To do so we utilize methods from classical statistical mechanics. The basis for this is the Feynman path integral for the partition function of quantized systems. With this representation the quantum mechanical problem can be interpreted as, and is equivalent to, a classical polymer problem in four dimensions where the fourth dimension is imaginary time. Thus methods, results, and properties obtained in the statistical mechanics of classical fluids can be utilized. From this viewpoint we recover the well known RPA (random phase approximation). Then to improve it we modify the RPA by requiring the corresponding correlation function to be such that electrons with equal spins can not be on the same position. Numerical evaluations are compared with well known results of a standard parameterization of Monte Carlo correlation energies.
Should School Nurses Wear Uniforms?
Journal of School Health, 2001
2001-01-01
This 1958 paper questions whether school nurses should wear uniforms (specifically, white uniforms). It concludes that white uniforms are often associated with the treatment of ill people, and since many people have a fear reaction to them, they are not necessary and are even undesirable. Since school nurses are school staff members, they should…
Compact Flyeye concentrator with improved irradiance uniformity on solar cell
Zhuang, Zhenfeng; Yu, Feihong
2013-08-01
A Flyeye concentrator with improved irradiance distribution on the solar cell in a concentrator photovoltaic system is proposed. This Flyeye concentrator is composed of four surfaces: a refractive surface, mirror surface, freeform surface, and transmissive surface. Based on the principles of geometrical optics, the contours of the proposed Flyeye concentrator are calculated according to Fermat's principle, the edge-ray principle, and the ray reversibility principle without solving partial differential equations or using an optimization algorithm, therefore a slope angle control method is used to construct the freeform surface. The solid model is established by applying a symmetry of revolution around the optical axis. Additionally, the optical performance for the Flyeye concentrator is simulated and analyzed by Monte-Carlo method. Results show that the Flyeye concentrator optical efficiency of >96.2% is achievable with 1333× concentration ratio and ±1.3 deg acceptance angle, and 1.3 low aspect ratio (average thickness to entry aperture diameter ratio). Moreover, comparing the Flyeye concentrator specification to that of the Köhler concentrator and the traditional Fresnel-type concentrator, results indicate that this concentrator has the advantages of improved uniformity, reduced thickness, and increased tolerance to the incident sunlight.
Uniform Stability of Damped Nonlinear Vibrations of an Elastic String
Indian Academy of Sciences (India)
Ganesh C Gorain; Sujit K Bose
2003-11-01
Here we are concerned about uniform stability of damped nonlinear transverse vibrations of an elastic string fixed at its two ends. The vibrations governed by nonlinear integro-differential equation of Kirchoff type, is shown to possess energy uniformly bounded by exponentially decaying function of time. The result is achieved by considering an energy-like Lyapunov functional for the system.
The Influence of a Mandatory School Uniform Policy.
Pate, Sharon Shamburger
This essay examines the influence of a mandatory school-uniform dress code on academic achievement and discipline infractions. In addition, student gender and type of school district were compared to show the influence of this policy. Only schools that implemented a mandatory school-uniform policy in 1996 and had data for discipline infractions…
Skin carcinogenesis following uniform and non-uniform β irradiation
International Nuclear Information System (INIS)
Where workers or the general public may be exposed to ionising radiation, the irradiation is rarely uniform. The risk figures and dose limits recommended by the International Commission on Radiological Protection (ICRP) are based largely on clinical and epidemiological studies of reasonably uniform irradiated organs. The paucity of clinical or experimental data for highly non-uniform exposures has prevented the ICRP from providing adequate recommendations. This weakness has led on a number of occasions to the postulate that highly non-uniform exposures of organs could be 100,000 times more carcinogenic than ICRP risk figures would predict. This so-called ''hot-particle hypothesis'' found little support among reputable radiobiologists, but could not be clearly and definitively refuted on the basis of experiment. An experiment, based on skin tumour induction in mouse skin, is described which was developed to test the hypothesis. The skin of 1200 SAS/4 male mice has been exposed to a range of uniform and non-uniform sources of the β emitter 170Tm (Emax ∼ 1 MeV). Non-uniform exposures were produced using arrays of 32 or 8 2-mm diameter sources distributed over the same 8-cm2 area as a uniform control source. Average skin doses varied from 2-100 Gy. The results for the non-uniform sources show a 30% reduction in tumour incidence by the 32-point array at the lower mean doses compared with the response from uniform sources. The eight-point array showed an order-of-magnitude reduction in tumour incidence compared to uniform irradiation at low doses. These results, in direct contradiction to the ''hot particle hypothesis'', indicate that non-uniform exposures produce significantly fewer tumours than uniform exposures. (author)
Extensional Uniformity for Boolean Circuits
McKenzie, Pierre; Vollmer, Heribert
2008-01-01
Imposing an extensional uniformity condition on a non-uniform circuit complexity class C means simply intersecting C with a uniform class L. By contrast, the usual intensional uniformity conditions require that a resource-bounded machine be able to exhibit the circuits in the circuit family defining C. We say that (C,L) has the "Uniformity Duality Property" if the extensionally uniform class C \\cap L can be captured intensionally by means of adding so-called "L-numerical predicates" to the first-order descriptive complexity apparatus describing the connection language of the circuit family defining C. This paper exhibits positive instances and negative instances of the Uniformity Duality Property.
Directory of Open Access Journals (Sweden)
D.C. Robertson
2012-02-01
Full Text Available 1979 saw the celebration of the 150th anniversary of the founding of an educational establishment in the Cape which was to develop into the University of Cape Town. To mark this anniversary the authors have presented a short history of UCT in uniform, highlighting the multifarious contributions made by UCTstudents and staff. This documented history clearly indicates the valuable contribution that not only UCT but all South African universities and their members have made in the past and will be called to make in the future. Changes in national service policy particularly with regard to urban commandos have resulted in the replacement of the UCT Regiment by the Cape Garrison Artillery. However, the loss of the UCT Regiment itself, certainly does not point to the end of UCT's contribution to the defence of South Africa. For at this very moment, in diverse regiments throughout South Africa, members of the UCT community are making a valiant contribution in answering the call of their country.
Janicic, Predrag
2010-01-01
There is a huge number of problems, from various areas, being solved by reducing them to SAT. However, for most applications, translations into SAT are performed by specialized, problem-specific tools. In this paper we describe a novel approach for uniform solving of a wide class of problems by reducing them to SAT. The approach uses a new specification language that combines imperative and declarative programming paradigms. A problem is specified by a test (expressed in an imperative form) that a given set of values indeed makes a solution to the problem. In the solving phase, parameters of the problem are represented by (finite) vectors of propositional formulae and the specification is symbolically executed. An assertion that given values make a solution is transformed to an instance of the SAT problem and passed to a SAT solver. If the formula is satisfiable, its model is transformed back to variables describing the problem, i.e., to a solution of the problem. We also describe a system URSA that implement...
Uniform and Robust Peptoid Microsphere Coatings
Directory of Open Access Journals (Sweden)
Shannon L. Servoss
2013-06-01
Full Text Available Peptoids that are helical and partially water soluble have been shown to self-assemble into microspheres when the peptoid solution is dried on a silicon substrate. Such microsphere coatings have great potential for use in biosensor technologies, specifically to increase the surface area for binding. However, in order to be useful, the peptoids must consistently form uniform coatings. In this study we investigated the effects of various coating protocol parameters on the uniformity of the resulting peptoid microsphere coatings, including (i solvent, (ii administration technique, and (iii drying environment. In addition, we investigated the robustness of the coatings as well as the potential for using a glass substrate. These studies show that uniform, robust peptoid microsphere coatings can be formed using protic solvents, a full coverage administration technique, and drying in open air on silicon or glass substrates.
Assessment indices for uniform and non-uniform thermal environments
Institute of Scientific and Technical Information of China (English)
2008-01-01
Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments.30 subjects reported their overall thermal sensation,thermal comfort,and thermal acceptability in uniform and non-uniform conditions.The results show that these three assessment indices provide equivalent evaluations in uniform environments.However,overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform environments.The relationship between the percentage and the mean vote for each index is established.
School Uniforms: Esprit de Corps.
Ryan, Rosemary P.; Ryan, Thomas E.
1998-01-01
The benefits of school uniforms far outweigh their short-term costs. School uniforms not only keep students safe, but they increase their self-esteem, promote a more positive attitude toward school, lead to improved student behavior, and help blur social-class distinctions. Students are allowed to wear their own political or religious messages,…
Statistical Test for Bivariate Uniformity
Directory of Open Access Journals (Sweden)
Zhenmin Chen
2014-01-01
Full Text Available The purpose of the multidimension uniformity test is to check whether the underlying probability distribution of a multidimensional population differs from the multidimensional uniform distribution. The multidimensional uniformity test has applications in various fields such as biology, astronomy, and computer science. Such a test, however, has received less attention in the literature compared with the univariate case. A new test statistic for checking multidimensional uniformity is proposed in this paper. Some important properties of the proposed test statistic are discussed. As a special case, the bivariate statistic test is discussed in detail in this paper. The Monte Carlo simulation is used to compare the power of the newly proposed test with the distance-to-boundary test, which is a recently published statistical test for multidimensional uniformity. It has been shown that the test proposed in this paper is more powerful than the distance-to-boundary test in some cases.
Adjustable, Broadband, Selective Excitation with Uniform Phase
Cano, Kristin E.; Smith, Mari A.; Shaka, A. J.
2002-03-01
An advance in the problem of achieving broadband, selective, and uniform-phase excitation in NMR spectroscopy of liquids is outlined. Broadband means that, neglecting relaxation, any frequency bandwidth may be excited even when the available radiofrequency (RF) field strength is strictly limited. Selective means that sharp transition edges can be created between pure-phase excitation and no excitation at all. Uniform phase means that, neglecting spin-spin coupling, all resonance lines have nearly the same phase. Conventional uniform-phase excitation pulses (e.g., E-BURP), mostly based on amplitude modulation of the RF field, are not broadband: they have an achievable bandwidth that is strictly limited by the peak power available. Other compensated pulses based on adiabatic half-passage, like BIR-4, are not selective. By contrast, inversion pulses based on adiabatic fast passage can be broadband (and selective) in the sense above. The advance outlined is a way to reformulate these frequency modulated (FM) pulses for excitation, rather than just inversion.
Uniform Acceleration in General Relativity
Friedman, Yaakov
2016-01-01
We extend de la Fuente and Romero's defining equation for uniform acceleration in a general curved spacetime from linear acceleration to the full Lorentz covariant uniform acceleration. In a flat spacetime background, we have explicit solutions. We use generalized Fermi-Walker transport to parallel transport the Frenet basis along the trajectory. In flat spacetime, we obtain velocity and acceleration transformations from a uniformly accelerated system to an inertial system. We obtain the time dilation between accelerated clocks. We apply our acceleration transformations to the motion of a charged particle in a constant electromagnetic field and recover the Lorentz-Abraham-Dirac equation.
Hofmann, Steve
2012-01-01
We present a higher dimensional, scale-invariant version of a classical theorem of F. and M. Riesz. More precisely, we establish scale invariant absolute continuity of harmonic measure with respect to surface measure, along with higher integrability of the Poisson kernel, for a domain $\\Omega\\subset \\re^{n+1},\\, n\\geq 2$, with a uniformly rectifiable boundary, which satisfies the Harnack Chain condition plus an interior (but not exterior) corkscrew condition. In a companion paper to this one \\cite{HMU}, we also establish a converse, in which we deduce uniform rectifiability of the boundary, assuming scale invariant $L^q$ bounds, with $q>1$, on the Poisson kernel.
Sckool Dress Rule, Uniform Policies
Institute of Scientific and Technical Information of China (English)
潘志强
2005-01-01
Our schools believe that a uniform policy will provide a better environment, promote positive selfesteem, encourage an atmosphere for greater discipline, and increase learning opportunities for students by removing many of the distractions associated with various types of clothing.
Are School Uniforms a Good Fit? Results from the ECLS-K and the NELS
Yeung, Ryan
2009-01-01
One of the most common proposals put forth for reform of the American system of education is to require school uniforms. Proponents argue that uniforms can make schools safer and also improve school attendance and increase student achievement. Opponents contend that uniforms have not been proven to work and may be an infringement on the freedom of…
Non-uniform Hyperbolicity and Non-uniform Specification
Oliveira, Krerley
2011-01-01
Let $f$ be a $C^{1+\\alpha}\\,(\\alpha>0)$ diffeomorphism and $\\mu$ be an ergodic hyperbolic measure of $f$. We show that this system $(f,\\mu)$ naturally satisfies non-uniform specification property\\cite{STV}(see Definition \\ref{Def:NS}) and thus we can delete the assumption of non-uniform specification property in the main Theorem \\cite{STV} to establish an inequality between Lyapunov exponents and local recurrence properties. We also discuss generalized non-uniform specification property with respect to arbitrarily finite(infinite) orbit segments. Moreover, these results are also valid for any ergodic hyperbolic measure $\\mu$, in whose Oseledec splitting the stable bundle dominates the unstable bundle on the support of $\\mu$.
Design and testing of a uniformly solar energy TIR-R concentration lenses for HCPV systems.
Shen, S C; Chang, S J; Yeh, C Y; Teng, P C
2013-11-01
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.
Design and testing of a uniformly solar energy TIR-R concentration lenses for HCPV systems.
Shen, S C; Chang, S J; Yeh, C Y; Teng, P C
2013-11-01
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. PMID:24514935
Directory of Open Access Journals (Sweden)
Cristiano Mauro Assis Gomes
2011-01-01
Full Text Available O presente estudo investiga a relação entre a abordagem superficial e a abordagem profunda à aprendizagem na explicação do rendimento escolar. Algumas questões são delineadas buscando verificar o papel de cada uma das abordagens na proficiência escolar em séries distintas. Foram analisados dados de 684 estudantes da sexta série do ensino fundamental à terceira série do ensino médio de uma escola particular de Belo Horizonte, Minas Gerais. Foi delineado um modelo para comparação das séries escolares, através da modelagem por equação estrutural. O modelo desenhado apresentou bom grau de ajuste (c²=427,12; gl=182; CFI=0,95; RMSEA=0,04 para a amostra completa e para cada série escolar. Os resultados mostram que há uma participação distinta da abordagem superficial e da abordagem profunda no desempenho escolar nas diferentes séries. São discutidas implicações dos resultados para a teoria das abordagens.This study investigates the relationship between deep and surface approach to learning in explaining academic achievement. Some questions are outlined aiming to verify the role of each approach in student's proficiency in different grades. Data from 684 students from junior high school (6th year to high school (12th year of a private school in Belo Horizonte, Minas Gerais, were analyzed. A model was designed to compare the grades through structural equation modeling. The designed model showed a good fit (c² = 427.12; df = 182; CFI = .95, RMSEA = .04 for the full sample and for each grade. The results show that there is a distinct contribution of both approaches in academic achievement in the different grades. Further implications to the learning approach theory will be discussed.
Uniform excitations in magnetic nanoparticles
Directory of Open Access Journals (Sweden)
Steen Mørup
2010-11-01
Full Text Available We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering.
Harmonious coloring of uniform hypergraphs
Bartłomiej Bosek; Sebastian Czerwiński; Jarosław Grytczuk; Paweł Rzążewski
2016-01-01
A \\emph{harmonious coloring} of a $k$-uniform hypergraph $H$ is a vertex coloring such that no two vertices in the same edge share the same color, and each $k$-element subset of colors appears on at most one edge. The \\emph{% harmonious number} $h(H)$ is the least number of colors needed for such a coloring. %These notions arose as a natural extension of a widely studied %topic of harmonious coloring of simple graphs. We prove that $k$-uniform hypergraphs of bounded maxim...
Uniform excitations in magnetic nanoparticles
DEFF Research Database (Denmark)
Mørup, Steen; Frandsen, Cathrine; Hansen, Mikkel Fougt
2010-01-01
We present a short review of the magnetic excitations in nanoparticles below the superparamagnetic blocking temperature. In this temperature regime, the magnetic dynamics in nanoparticles is dominated by uniform excitations, and this leads to a linear temperature dependence of the magnetization...... and the magnetic hyperfine field, in contrast to the Bloch T3/2 law in bulk materials. The temperature dependence of the average magnetization is conveniently studied by Mössbauer spectroscopy. The energy of the uniform excitations of magnetic nanoparticles can be studied by inelastic neutron scattering....
International Nuclear Information System (INIS)
Ion implantation's unique contributions to FET processing are excellent uniformity and repeatability at low dose. These could be verified on product wafers but were difficult to measure on monitor wafers. This paper presents an MOS technique that integrates the C-V curve directly to obtain part of the implanted dose - the partial dose. This technique is fast and insensitive to measurement noise and dot-diameter variation. It uses standard MOS wafers and processing. Neither photo-defined dots nor special substrates are required. Presently the integral CdV technique for partial dose is used in several FET lines to measure both implant repeatability and uniformity. (orig.)
UOBPRM: A uniformly distributed obstacle-based PRM
Yeh, Hsin-Yi
2012-10-01
This paper presents a new sampling method for motion planning that can generate configurations more uniformly distributed on C-obstacle surfaces than prior approaches. Here, roadmap nodes are generated from the intersections between C-obstacles and a set of uniformly distributed fixed-length segments in C-space. The results show that this new sampling method yields samples that are more uniformly distributed than previous obstacle-based methods such as OBPRM, Gaussian sampling, and Bridge test sampling. UOBPRM is shown to have nodes more uniformly distributed near C-obstacle surfaces and also requires the fewest nodes and edges to solve challenging motion planning problems with varying narrow passages. © 2012 IEEE.
Directory of Open Access Journals (Sweden)
Tânia R.I. Rodrigues
2001-05-01
Full Text Available A avaliação da uniformidade de distribuição de água de um sistema de irrigação é feita acima da superfície do solo. Tendo em vista a importância da uniformidade no interior do solo quando submetido a uma irrigação, desenvolveu-se o presente trabalho com o objetivo de se avaliar a uniformidade de distribuição de água, tanto acima como no interior do solo, através dos coeficientes CUD e CUC, com um pivô central operando em condições de campo. Acima da superfície, a uniformidade foi obtida seguindo-se a metodologia da Associação Brasileira de Normas Técnicas (ABNT e se alocando duas linhas de coletores com abertura de 3º, a partir do ponto inicial do pivô. Propôs-se, para obtenção da uniformidade no interior do solo, a utilização da umidade determinada pelo TDR (Reflectometria no Domínio do Tempo visto que é uma técnica simples e produz resultados imediatos. Os resultados encontrados demonstraram que a uniformidade no interior do solo foi maior que na superfície, ficando acima da faixa recomendada, mostrando que a redistribuição da água no interior do solo promove maior uniformidade de umidade no perfil do solo que a encontrada na lâmina aplicada; portanto, no dimensionamento econômico de sistemas de irrigação, os coeficientes de uniformidade obtidos no interior do solo devem ser considerados.The evaluation of the uniformity of water distribution in an irrigation system is done above the surface of the soil. The main objective of this work was to evaluate the uniformity of water distribution in a central pivot under field conditions, through the use of the CUD and CUC coefficients. On the surface, the uniformity was obtained with the use of the ABNT methodology, therefore placing two collector lines displaced three degrees from the initial pivot position. In order to obtain the uniformity in the soil, the water content was determined with the TDR (Time Domain Reflectometry, which is a simple and fast
Hofmann, Steve; Martell, José María
2012-01-01
We present a higher dimensional, scale-invariant version of a classical theorem of F. and M. Riesz. More precisely, we establish scale invariant absolute continuity of harmonic measure with respect to surface measure, along with higher integrability of the Poisson kernel, for a domain $\\Omega\\subset \\mathbb{R}^{n+1},\\, n\\geq 2$, with a uniformly rectifiable boundary, which satisfies the Harnack Chain condition plus an interior (but not exterior) corkscrew condition. In a companion paper to th...
School Uniforms: Guidelines for Principals.
Essex, Nathan L.
2001-01-01
Principals desiring to develop a school-uniform policy should involve parents, teachers, community leaders, and student representatives; beware restrictions on religious and political expression; provide flexibility and assistance for low-income families; implement a pilot program; align the policy with school-safety issues; and consider legal…
Surface Plasmon Wave Adapter Designed with Transformation Optics
DEFF Research Database (Denmark)
Zhang, Jingjing; Xiao, Sanshui; Wubs, Martijn;
2011-01-01
On the basis of transformation optics, we propose the design of a surface plasmon wave adapter which confines surface plasmon waves on non-uniform metal surfaces and enables adiabatic mode transformation of surface plasmon polaritons with very short tapers. This adapter can be simply achieved...... with homogeneous anisotropic naturally occurring materials or subwavelength grating-structured dielectric materials. Full wave simulations based on a finite-element method have been performed to validate our proposal....
DEFF Research Database (Denmark)
Henningsson, Stefan
2016-01-01
competitive, national customs and regional economic organizations are seeking to establish a standardized solution for digital reporting of customs data. However, standardization has proven hard to achieve in the socio-technical e-Customs solution. In this chapter, the authors identify and describe what has...... to be harmonized in order for a global company to perceive e-Customs as standardized. In doing so, they contribute an explanation of the challenges associated with using a standardization mechanism for harmonizing socio-technical information systems....
DEFF Research Database (Denmark)
Henningsson, Stefan
2014-01-01
competitive, national customs and regional economic organizations are seeking to establish a standardized solution for digital reporting of customs data. However, standardization has proven hard to achieve in the socio-technical e-Customs solution. In this chapter, the authors identify and describe what has...... to be harmonized in order for a global company to perceive e-Customs as standardized. In doing so, they contribute an explanation of the challenges associated with using a standardization mechanism for harmonizing socio-technical information systems....
Group Composition, Group Interaction and Achievement in Cooperative Small Groups.
Webb, Noreen M.
This study investigated interaction and achievement in cooperative small groups in four junior high school mathematics classrooms. Ninety-six students learned a one-week unit on consumer mathematics in mixed-ability or uniform-ability groups. Students in mixed-ability groups scored higher on a problem-solving test than students in uniform-ability…
Energy Technology Data Exchange (ETDEWEB)
Lu, Chao; Wu, Hao, E-mail: hao.wu@scu.edu.cn; Chen, Baojun; Liu, Heng; Zhang, Yun, E-mail: y_zhang@scu.edu.cn
2015-06-15
Graphical abstract: Li{sub 1.2}Mn{sub 0.52}Co{sub 0.08}Ni{sub 0.2}O{sub 2} cathode material uniformly nanocoated with samarium fluoride (SmF{sub 3}) has been successfully synthesized through a chemical deposition method followed by low-temperature hydrothermal treatment. The surface modified cathode shows a significantly improved cycling stability and rate capability. - Highlights: • Samarium fluoride is originally used as coating material of Li-rich layered cathode. • Low-temperature hydrothermal treatment is employed to establish uniform surface coating. • Cathode nanocoated with SmF{sub 3} shows improved rate capability and cycling stability. • Coating material suppresses the side reaction between electrode and electrolyte. - Abstract: Surface nanocoating of lithium-rich layered Li{sub 1.2}Mn{sub 0.52}Co{sub 0.08}Ni{sub 0.2}O{sub 2} with samarium fluoride (SmF{sub 3}) has been performed through a chemical deposition route combined with a low-temperature hydrothermal treatment. The surface-modified Li{sub 1.2}Mn{sub 0.52}Co{sub 0.08}Ni{sub 0.2}O{sub 2} particles are uniformly and completely covered by an amorphous SmF{sub 3} protective layer with a thin thickness of ∼20 nm. After surface modification, the coated Li{sub 1.2}Mn{sub 0.52}Co{sub 0.08}Ni{sub 0.2}O{sub 2} as cathode shows a significantly improved cycling stability, keeping a capacity retention of 84.5% after 150 cycles at 2 C, much higher than 68.9%forits uncoated counterpart. Moreover, the coated sample delivers an enhanced rate capability with an average capacity of ∼132.3 mA h g{sup −1} when charged at 5 C and discharged at 0.2 C, while the uncoated counterpart only exhibits a capacity of ∼111.4 mA h g{sup −1} under the same conditions. Our results reveal that the remarkably improved electrochemical performance of the surface-modified cathode is attributed to the presence of uniform, robust, and nanoscale SmF{sub 3} coating layer, which not only suppresses the growth of SEI layer
Magnetic Propeller for Uniform Magnetic Field Levitation
Krinker, Mark
2008-01-01
Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symmetry causing origination of a net force. Unlike a wire with current, having radial energetic symmetry, the symmetry of the Virtual Wire System is closer to an axial wire. The third approach refers to the first two. It is based on creation of developed surface system, comprising the elements of the first two types. The developed surface approach is a way to drastically increase a thrust-to-weight ratio. The conducted experiments have confirmed feasibility of the proposed approaches.
Uniformity Analysis for Index of Retail Price
Institute of Scientific and Technical Information of China (English)
潘竞红; 曾庆洪; 刘梅英
2002-01-01
Using the Hodges-Ajne testing method, the uniformity of China retail price index was tested. The result, that population is submitting to uniform dist ribution, was obtained. The uniformity of CRPI indicates that the general price level is stable in the Ninth Five-Year Plan. Finally, the reasons causing the uniformity was analyzed.
Christiansen Revisited: Rethinking Quantification of Uniformity in Rainfall Simulator Studies
Green, Daniel; Pattison, Ian
2016-04-01
Rainfall simulators, whether based within a laboratory or field setting are used extensively within a number of fields of research, including plot-scale runoff, infiltration and erosion studies, irrigation and crop management and scaled investigations into urban flooding. Rainfall simulators offer a number of benefits, including the ability to create regulated and repeatable rainfall characteristics (e.g. intensity, duration, drop size distribution and kinetic energy) without relying on unpredictable natural precipitation regimes. Ensuring and quantifying spatially uniform simulated rainfall across the entirety of the plot area is of particular importance to researchers undertaking rainfall simulation. As a result, numerous studies have focused on the quantification and improvement of uniformity values. Several statistical methods for the assessment of rainfall simulator uniformity have been developed. However, the Christiansen Uniformity Coefficient (CUC) suggested by Christiansen (1942) is most frequently used. Despite this, there is no set methodology and researchers can adapt or alter factors such as the quantity, as well as the spacing, distance and location of the measuring beakers used to derive CUC values. Because CUC values are highly sensitive to the resolution of the data, i.e. the number of observations taken, many densely distributed measuring containers subjected to the same experimental conditions may generate a significantly lower CUC value than fewer, more sparsely distributed measuring containers. Thus, the simulated rainfall under a higher resolution sampling method could appear less uniform than when using a coarser resolution sampling method, despite being derived from the same initial rainfall conditions. Expressing entire plot uniformity as a single, simplified percentage value disregards valuable qualitative information about plot uniformity, such as the small-scale spatial distribution of rainfall over the plot surface and whether these
Uniform pricing and social welfare
Bertoletti, Paolo
2005-01-01
We re-examine the case for uniform pricing in a monopolistic third-degree price-discrimination setting by introducing differentiated costs. A profit-maximizing monopolist could then use price differentiation to reduce the production of the more costly goods, thereby decreasing average cost and increasing welfare. Indeed, monopolistic price differentiation can improve welfare and also aggregate consumer surplus even if, as in the benchmark linear case, total output does not increase. According...
Energy Technology Data Exchange (ETDEWEB)
Blue, C.A.; Sikka, V.K. [Oak Ridge National Lab., TN (United States); Chun, Jung-Hoon [Massachusetts Institute of Technology, Cambridge, MA (United States); Ando, T. [Tufts Univ., Medford, MA (United States)
1997-04-01
The uniform-droplet process is a new method of liquid-metal atomization that results in single droplets that can be used to produce mono-size powders or sprayed-on to substrates to produce near-net shapes with tailored microstructure. The mono-sized powder-production capability of the uniform-droplet process also has the potential of permitting engineered powder blends to produce components of controlled porosity. Metal and alloy powders are commercially produced by at least three different methods: gas atomization, water atomization, and rotating disk. All three methods produce powders of a broad range in size with a very small yield of fine powders with single-sized droplets that can be used to produce mono-size powders or sprayed-on substrates to produce near-net shapes with tailored microstructures. The economical analysis has shown the process to have the potential of reducing capital cost by 50% and operating cost by 37.5% when applied to powder making. For the spray-forming process, a 25% savings is expected in both the capital and operating costs. The project is jointly carried out at Massachusetts Institute of Technology (MIT), Tuffs University, and Oak Ridge National Laboratory (ORNL). Preliminary interactions with both finished parts and powder producers have shown a strong interest in the uniform-droplet process. Systematic studies are being conducted to optimize the process parameters, understand the solidification of droplets and spray deposits, and develop a uniform-droplet-system (UDS) apparatus appropriate for processing engineering alloys.
Energy Technology Data Exchange (ETDEWEB)
Salapare, Hernando S., E-mail: hssalapare@up.edu.ph [Plasma Physics Laboratory, National Institute of Physics, College of Science, University of the Philippines Diliman, Quezon City 1101 (Philippines); eUP Office and UP Information Technology Development Center, University of the Philippines, Quezon City 1101 (Philippines); Suarez, Beverly Anne T. [Physics Department, De La Salle University, 2401 Taft Avenue, Manila (Philippines); Cosiñero, Hannah Shamina O.; Bacaoco, Miguel Y.; Ramos, Henry J. [Plasma Physics Laboratory, National Institute of Physics, College of Science, University of the Philippines Diliman, Quezon City 1101 (Philippines)
2015-01-01
Poly(tetrafluoroethylene) (PTFE) was irradiated by CF{sub 4} plasma produced in the gas discharge ion source facility to produce stable and robust superhydrophobic surfaces and to enhance the materials' oleophilic property for biological applications. The characterizations employed on the samples are contact angle measurements, analysis of the surface morphology (scanning electron microscopy), surface roughness measurements (atomic force microscopy) and analysis of the surface chemistry (Fourier transform infrared spectroscopy). Superhydrophobic behavior with water contact angles as high as 156° was observed. The wettability of all the treated samples was found to be stable in time as evidenced by the statistically insignificant differences in the hysteresis contact angles. The level of enhanced hydrophobicity depended on the plasma energies (i.e. irradiation times, discharge current, and discharge voltage); higher plasma energies produced surfaces with high hydrophobicity. The plasma treatment also enhanced the oleophilic property of the materials' surface as evidenced by the decrease in the PDMS-oil contact angle from 33° to as low as 10°. The superhydrophobicity of the modified PTFE and the enhancement of its oleophilic property were due to (1) the changes in the roughness of the surface, (2) the formation of nanoparticles or nanostructures on the surface, and (3) the changes in the surface chemistry. - Highlights: • PTFE surfaces were treated with direct CF{sub 4} using the gas discharge ion source. • Stable superhydrophobic behavior with water contact angles as high as 156° was recorded. • Surface roughness increased as the surface exhibited enhanced hydrophobicity. • Carbon nanoparticles were observed on the superhydrophobic PTFE surface. • Enhanced oleophilic property was observed with change in the PDMS-oil contact angle from 33° to 10°.
International Nuclear Information System (INIS)
Poly(tetrafluoroethylene) (PTFE) was irradiated by CF4 plasma produced in the gas discharge ion source facility to produce stable and robust superhydrophobic surfaces and to enhance the materials' oleophilic property for biological applications. The characterizations employed on the samples are contact angle measurements, analysis of the surface morphology (scanning electron microscopy), surface roughness measurements (atomic force microscopy) and analysis of the surface chemistry (Fourier transform infrared spectroscopy). Superhydrophobic behavior with water contact angles as high as 156° was observed. The wettability of all the treated samples was found to be stable in time as evidenced by the statistically insignificant differences in the hysteresis contact angles. The level of enhanced hydrophobicity depended on the plasma energies (i.e. irradiation times, discharge current, and discharge voltage); higher plasma energies produced surfaces with high hydrophobicity. The plasma treatment also enhanced the oleophilic property of the materials' surface as evidenced by the decrease in the PDMS-oil contact angle from 33° to as low as 10°. The superhydrophobicity of the modified PTFE and the enhancement of its oleophilic property were due to (1) the changes in the roughness of the surface, (2) the formation of nanoparticles or nanostructures on the surface, and (3) the changes in the surface chemistry. - Highlights: • PTFE surfaces were treated with direct CF4 using the gas discharge ion source. • Stable superhydrophobic behavior with water contact angles as high as 156° was recorded. • Surface roughness increased as the surface exhibited enhanced hydrophobicity. • Carbon nanoparticles were observed on the superhydrophobic PTFE surface. • Enhanced oleophilic property was observed with change in the PDMS-oil contact angle from 33° to 10°
Topologies of (strong) uniform convergence on bornologies
Holá, Lubica; Novotný, Branislav
2012-01-01
We continue the study of topologies of strong uniform convergence on bornologies initiated in [G. Beer and S. Levi, Strong uniform continuity, J. Math Anal. Appl., 350:568-589, 2009] and [G. Beer and S. Levi, Uniform continuity, uniform convergence and shields, Set-Valued and Variational Analysis, 18:251-275, 2010]. We study cardinal invariants of topologies of (strong) uniform convergence on bornologies on the space of continuous real-valued functions and we also generalize some known result...
Wang, Xu; Schiavone, Peter
2016-07-01
Using complex variable methods and conformal mapping techniques, we demonstrate rigorously that two inhomogeneities of irregular shape interacting with a screw dislocation can indeed maintain uniform internal stress distributions. Our analysis indicates that while the internal uniform stresses are independent of the existence of the screw dislocation, the shapes of the two inhomogeneities required to achieve this uniformity depend on the Burgers vector, the location of the screw dislocation, and the size of the inhomogeneities. In addition, we find that this uniformity of the internal stress field is achievable also when the two inhomogeneities interact with an arbitrary number of discrete screw dislocations in the matrix.
Thomas Precession by Uniform Acceleration
Pardy, Miroslav
2015-01-01
We determine the nonlinear transformations between coordinate systems which are mutually in a constant symmetrical accelerated motion. The maximal acceleration limit follows from the kinematical origin and it is an analogue of the maximal velocity in special relativity. We derive the dependence of mass, length, time, Doppler effect, Cherenkov effect and transition radiation angle on acceleration as an analogue phenomena in special theory of relativity. The last application of our method is the Thomas precession by uniform acceleration with the possible role in the modern physics and cosmology. The comparison of derived results with other relativistic methods is necessary.
Analytical Solution of Coupled Laminar Heat-Mass Transfer in a Tube with Uniform Heat Flux
Institute of Scientific and Technical Information of China (English)
无
1992-01-01
Analytical solution is obtained of coupled laminar heat-mass transfer in a tube with uniform heat flux.This corresponds to the case when a layer of sublimable material is coated on the inner surface of a tube with its outer surface heated by uniform heat flux and this coated material will sublime as gas flows throught the tube.
Light beams focusing in periodically non-uniform crystalline medium
Directory of Open Access Journals (Sweden)
S.N.Kurilkina
2002-03-01
Full Text Available In the present paper the peculiarities of propagation and diffraction of optical waves in the crystalline periodically non-uniform media are considered. The dependence of light beam divergence in the crystal on curvatures of wave vector surface is obtained. It is shown, that presence of the periodic non-uniformity of the crystal and natural anisotropy lead to essential deformation of wave vector surface, namely, to the appearance of local regions with negative curvature and, hence, to the effect of light focusing in corresponding directions. The application of uniform electric field may intensify the light focusing. The crystalline diffraction lenses are proposed which are controlled by electric field and variation of incident light polarization.
Hofmann, Steve; Uriarte-Tuero, Ignacio
2012-01-01
We present the converse to a higher dimensional, scale-invariant version of a classical theorem of F. and M. Riesz. More precisely, for $n\\geq 2$, for an ADR domain $\\Omega\\subset \\re^{n+1}$ which satisfies the Harnack Chain condition plus an interior (but not exterior) Corkscrew condition, we show that absolute continuity of harmonic measure with respect to surface measure on $\\partial\\Omega$, with scale invariant higher integrability of the Poisson kernel, is sufficient to imply uniformly rectifiable of $\\partial\\Omega$.
Energy Technology Data Exchange (ETDEWEB)
Goo, Hyun Woo [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Asan Medical Center, Seoul (Korea, Republic of)
2011-07-15
A practical body-size adaptive protocol providing uniform image noise at various kV levels is not available for pediatric CT. To develop a practical contrast-enhanced pediatric chest CT protocol providing uniform image noise by using an individualized volume CT dose index (CTDIvol) determined by the cross-sectional area and density of the body at variable kV levels and with combined tube current modulation. A total of 137 patients (mean age, 7.6 years) underwent contrast-enhanced pediatric chest CT based on body weight. From the CTDIvol, image noise, and area and mean density of the cross-section at the lung base in the weight-based group, the best fit equation was estimated with a very high correlation coefficient ({gamma}{sup 2} = 0.86, P < 0.001). For the next study, 177 patients (mean age, 7.9 years; the CTDIvol group) underwent contrast-enhanced pediatric chest CT with the CTDIvol determined individually by the best fit equation. CTDIvol values on the dose report after CT scanning, noise differences from the target noise, areas, and mean densities were compared between these two groups. The CTDIvol values (mean{+-}standard deviation, 1.6 {+-} 0.7 mGy) and the noise differences from the target noise (1.1 {+-} 0.9 HU) of the CTDIvol group were significantly lower than those of the weight-based group (2.0 {+-} 1.0 mGy, 1.8 {+-} 1.4 HU) (P < 0.001). In contrast, no statistically significant difference was found in area (317.0 {+-} 136.8 cm{sup 2} vs. 326.3 {+-} 124.8 cm{sup 2}), mean density (-212.9 {+-} 53.1 HU vs. -221.1 {+-} 56.3 HU), and image noise (13.8 {+-} 2.3 vs. 13.6 {+-} 1.7 HU) between the weight-based and the CTDIvol groups (P > 0.05). Contrast-enhanced pediatric chest CT with the CTDIvol determined individually by the cross-sectional area and density of the body provides more uniform noise and better dose adaptation to body habitus than does weight-based CT at variable kV levels and with combined tube current modulation. (orig.)
Calculation of Uniform of Beam Scanning
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
For the electron beam application, it is always scanned by a dipole magnet. The uniform of the scanning has great influence for some application, such as the irradiation of the thyristor. There are two methods for improving the scanning uniform:
Jasenak, Brian; Willsey, Rachel; Willsey, Adam; Forish, James
2016-03-01
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 multi-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 and intensity. In this study, a UV transmitting glass formulation and secondary linear optic were designed and manufactured to demonstrate their effects on achievable irradiance intensity and uniformity. Prismatic patterning on the light source surface of the lens was used to minimize reflection losses on the incident surface of the glass. Fresnel optics were molded into the opposite side of the UV transmitting glass to control the refraction of the light and to gain the desired light intensity distribution from two multi-UV LED arrays. A 20% increase in relative irradiance was observed while maintaining the same coverage area. This work discusses the optical design and the resulting benefits of controlled light output on UV LED systems, which include reduced driving current, decreased thermal deterioration, improved energy efficiency, and longer LED lifetime.
Institute of Scientific and Technical Information of China (English)
J. O. KAMGANG; M. NAITAL; J.-M. HERRY; M.-N. BELLON-FONTAINE; J.-L. BRISSET; R. BRIANDET
2009-01-01
This study addressed the effects of treatment with gliding discharge plasma on the surface properties of solid materials, as well as the consequences concerning adherence of a mode bacterium. As evaluated by contact angles with selected liquids, plasma treatment caused an increase in surface hydrophilicity and in the Lewis acid-base components of the surface energy of all materials tested. These modifications were more marked for low density polyethylene and stainless steel than for polytetrafluoroethylene. After treatment, the hydrophilicity of the materials remained relatively stable for at least 20 days. Moreover, analysis of the topography of the materials by atomic force microscopy revealed that the roughness of both polymers was reduced by glidarc plasma treatment. As a result of all these modifications, solid substrates were activated towards micro-organisms and the adherence of S. epidermidis, a negatively charged Lewis-base and mildly hydrophilic strain selected as the model, was increased in almost all the cases tested.
Ta, Duy Tien; Guedens, Wanda; Vranken, Tom; Vanschoenbeek, Katrijn; Steen Redeker, Erik; Michiels, Luc; Adriaensens, Peter
2016-01-01
Surface bioconjugation of biomolecules has gained enormous attention for developing advanced biomaterials including biosensors. While conventional immobilization (by physisorption or covalent couplings using the functional groups of the endogenous amino acids) usually results in surfaces with low activity, reproducibility and reusability, the application of methods that allow for a covalent and uniformly oriented coupling can circumvent these limitations. In this study, the nanobody targeting Vascular Cell Adhesion Molecule-1 (NbVCAM1), an atherosclerotic biomarker, is engineered with a C-terminal alkyne function via Expressed Protein Ligation (EPL). Conjugation of this nanobody to azidified silicon wafers and Biacore™ C1 sensor chips is achieved via Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry to detect VCAM1 binding via ellipsometry and surface plasmon resonance (SPR), respectively. The resulting surfaces, covered with uniformly oriented nanobodies, clearly show an increased antigen binding affinity, sensitivity, detection limit, quantitation limit and reusability as compared to surfaces prepared by random conjugation. These findings demonstrate the added value of a combined EPL and CuAAC approach as it results in strong control over the surface orientation of the nanobodies and an improved detecting power of their targets-a must for the development of advanced miniaturized, multi-biomarker biosensor platforms. PMID:27399790
Ta, Duy Tien; Guedens, Wanda; Vranken, Tom; Vanschoenbeek, Katrijn; Steen Redeker, Erik; Michiels, Luc; Adriaensens, Peter
2016-01-01
Surface bioconjugation of biomolecules has gained enormous attention for developing advanced biomaterials including biosensors. While conventional immobilization (by physisorption or covalent couplings using the functional groups of the endogenous amino acids) usually results in surfaces with low activity, reproducibility and reusability, the application of methods that allow for a covalent and uniformly oriented coupling can circumvent these limitations. In this study, the nanobody targeting Vascular Cell Adhesion Molecule-1 (NbVCAM1), an atherosclerotic biomarker, is engineered with a C-terminal alkyne function via Expressed Protein Ligation (EPL). Conjugation of this nanobody to azidified silicon wafers and Biacore™ C1 sensor chips is achieved via Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) “click” chemistry to detect VCAM1 binding via ellipsometry and surface plasmon resonance (SPR), respectively. The resulting surfaces, covered with uniformly oriented nanobodies, clearly show an increased antigen binding affinity, sensitivity, detection limit, quantitation limit and reusability as compared to surfaces prepared by random conjugation. These findings demonstrate the added value of a combined EPL and CuAAC approach as it results in strong control over the surface orientation of the nanobodies and an improved detecting power of their targets—a must for the development of advanced miniaturized, multi-biomarker biosensor platforms. PMID:27399790
Directory of Open Access Journals (Sweden)
Duy Tien Ta
2016-07-01
Full Text Available Surface bioconjugation of biomolecules has gained enormous attention for developing advanced biomaterials including biosensors. While conventional immobilization (by physisorption or covalent couplings using the functional groups of the endogenous amino acids usually results in surfaces with low activity, reproducibility and reusability, the application of methods that allow for a covalent and uniformly oriented coupling can circumvent these limitations. In this study, the nanobody targeting Vascular Cell Adhesion Molecule-1 (NbVCAM1, an atherosclerotic biomarker, is engineered with a C-terminal alkyne function via Expressed Protein Ligation (EPL. Conjugation of this nanobody to azidified silicon wafers and Biacore™ C1 sensor chips is achieved via Copper(I-catalyzed azide-alkyne cycloaddition (CuAAC “click” chemistry to detect VCAM1 binding via ellipsometry and surface plasmon resonance (SPR, respectively. The resulting surfaces, covered with uniformly oriented nanobodies, clearly show an increased antigen binding affinity, sensitivity, detection limit, quantitation limit and reusability as compared to surfaces prepared by random conjugation. These findings demonstrate the added value of a combined EPL and CuAAC approach as it results in strong control over the surface orientation of the nanobodies and an improved detecting power of their targets—a must for the development of advanced miniaturized, multi-biomarker biosensor platforms.
Energy Technology Data Exchange (ETDEWEB)
Hui Tian, Charles Reece, Michael Kelley
2009-05-01
Future accelerators require unprecedented cavity performance, which is strongly influenced by interior surface nano-smoothness. Electropolishing (EP) is the technique of choice to be developed for high-field superconducting radio frequency (SRF) cavities. Electrochemical impedance spectroscopy (EIS) and related techniques point to the electropolishing mechanism of Nb in a sulphuric and hydrofluoric acid electrolyte controlled by a compact surface salt film under F- diffusion-limited mass transport control. These and other findings are guiding a systematic characterization to form the basis for cavities process optimization.
Dense packing on uniform lattices
Eloranta, Kari
2009-01-01
We study the Hard Core Model on the graphs ${\\rm {\\bf \\scriptstyle G}}$ obtained from Archimedean tilings i.e. configurations in $\\scriptstyle \\{0,1\\}^{{\\rm {\\bf G}}}$ with the nearest neighbor 1's forbidden. Our particular aim in choosing these graphs is to obtain insight to the geometry of the densest packings in a uniform discrete set-up. We establish density bounds, optimal configurations reaching them in all cases, and introduce a probabilistic cellular automaton that generates the legal configurations. Its rule involves a parameter which can be naturally characterized as packing pressure. It can have a critical value but from packing point of view just as interesting are the noncritical cases. These phenomena are related to the exponential size of the set of densest packings and more specifically whether these packings are maximally symmetric, simple laminated or essentially random packings.
Uniform magnetic excitations in nanoparticles
DEFF Research Database (Denmark)
Mørup, Steen; Hansen, Britt Rosendahl
2005-01-01
We have used a spin-wave model to calculate the temperature dependence of the (sublattice) magnetization of magnetic nanoparticles. The uniform precession mode, corresponding to a spin wave with wave vector q=0, is predominant in nanoparticles and gives rise to an approximately linear temperature...... dependence of the (sublattice) magnetization well below the superparamagnetic blocking temperature for both ferro-, ferri-, and antiferromagnetic particles. This is in accordance with the results of a classical model for collective magnetic excitations in nanoparticles. In nanoparticles of antiferromagnetic...... materials, quantum effects give rise to a small deviation from the linear temperature dependence of the (sublattice) magnetization at very low temperatures. The complex nature of the excited precession states of nanoparticles of antiferromagnetic materials, with deviations from antiparallel orientation...
Attitudes of Parents about School Uniforms.
West, Charles K.; Tidwell, Diane K.; Bomba, Anne K.; Elmore, Patsy Alexander
1999-01-01
Responses from 144 parents of fourth graders showed that 56% favored uniforms in public schools; most agreed that uniforms contributed to a conducive learning environment, promoted school spirit, and discouraged violence; and most disagreed that uniforms cost more than other types of clothing. (SK)
Some results on uniform arithmetic circuit complexity
DEFF Research Database (Denmark)
Frandsen, Gudmund Skovbjerg; Valence, Mark; Barrington, David A. Mix
1994-01-01
and polynomial-size unbounded fan-in arithmetic circuits satisfying a natural uniformity constraint (DLOGTIME-uniformity). A 1-input and 1-output arithmetic function over the fieldsF2n may be identified with ann-input andn-output Boolean function when field elements are represented as bit strings. We prove...... that if some such representation is X-uniform (where X is P or DLOGTIME), then the arithmetic complexity of a function (measured with X-uniform unbounded fan-in arithmetic circuits) is identical to the Boolean complexity of this function (measured with X-uniform threshold circuits). We show the existence...
Discovery of Uniformly Expanding Universe
Directory of Open Access Journals (Sweden)
Cahill R. T.
2012-01-01
Full Text Available Saul Perlmutter and the Brian Schmidt – Adam Riess teams reported that their Friedmann-model GR-based analysis of their supernovae magnitude-redshift data re- vealed a new phenomenon of “dark energy” which, it is claimed, forms 73% of the energy / matter density of the present-epoch universe, and which is linked to the further claim of an accelerating expansion of the universe. In 2011 Perlmutter, Schmidt and Riess received the Nobel Prize in Physics “for the discovery of the accelerating ex- pansion of the Universe through observations of distant supernovae”. Here it is shown that (i a generic model-independent analysis of this data reveals a uniformly expanding universe, (ii their analysis actually used Newtonian gravity, and finally (iii the data, as well as the CMB fluctuation data, does not require “dark energy” nor “dark matter”, but instead reveals the phenomenon of a dynamical space, which is absent from the Friedmann model.
Experimental Study on the Expansion Uniformity of Armature
Institute of Scientific and Technical Information of China (English)
HE Yuan-hang; WU Bi; MA Yue-fen; ZHANG Qing-ming
2009-01-01
A measurement system has been developed based on high-precision printed probes in printed circuit board (PCB) and steep rising-time probe adapters,which can be applied to study the expansion uniformity of armature in a helical magnetic flux compression generator (HFCG).The influences of wall thickness and initiation position on the expansion uniformity of armature in HFCG were experimentally investigated.The results show that the armature with thinner wall thickness will easily rupture due to the high pressure of detonation products inside,the armature with larger wall thickness will easily crack due to the tensile stress on the outer surface of the wall,the influence of the end effect on the expansion uniformity can be ignored if the distance between the first group of probe and the initiation point is more than 3 times the armature diameter.
Realization of perfect reconstruction non-uniform filter banks via a tree structure
Ling, Wing-Kuen; Tam, Kwong-Shun
2001-01-01
Obviously, a tree structure filter bank can be realized via a non-uniform filter bank, and perfect reconstruction is achieved if and only if each branch of the tree structure can provide perfect reconstruction. In this paper, the converse of this problem is studied. We show that a perfect reconstruction non-uniform filter bank with decimation ratio {2,4,4} can be realized via a tree structure and each branch of the tree structure achieves perfect reconstruction.
Uniform and Non-Uniform Optimum Scalar Quantizers Performances: A Comparative Study
Directory of Open Access Journals (Sweden)
Fendy Santoso
2008-05-01
Full Text Available The aim of this research is to investigate source coding, the representation of information source output by finite R bits/symbol. The performance of optimum quantisers subject to an entropy constraint has been studied. The definitive work in this area is best summarised by Shannon’s source coding theorem, that is, a source with entropy H can be encoded with arbitrarily small error probability at any rate R (bits/source output as long as R>H. Conversely, If R the error probability will be driven away from zero, independent of the complexity of the encoder and the decoder employed. In this context, the main objective of engineers is however to design the optimum code. Unfortunately, the rate-distortion theorem does not provide the recipe for such a design. The theorem does, however, provide the theoretical limit so that we know how close we are to the optimum. The full understanding of the theorem also helps in setting the direction to achieve such an optimum. In this research, we have investigated the performances of two practical scalar quantisers, i.e., a Lloyd-Max quantiser and the uniformly defined one and also a well-known entropy coding scheme, i.e., Huffman coding against their theoretically attainable optimum performance due to Shannon’s limit R. It has been shown that our uniformly defined quantiser could demonstrate superior performance. The performance improvements, in fact, are more noticeable at higher bit rates.
Gradient angle estimation by uniform directional simulation on a cone
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager
1997-01-01
A sample of uniformly distributed unit vectors on an n-dimensional spherical cone is generated. The distances to a given limit state surface in the directions of the unit vectors of the sample are calculated and each of these distances are projected on the cone axis. The theoretical distribution...... of these projections is derived assuming the limit-state surface to be a hyperplane. This distribution depends on the angle between the cone axis and the normal vector to the hyperplane. Assuming sufficient flatness of the actual limit-state surface within a neighbourhood of the cut point with the cone axis, the cone...
Alignment and Characterization of High Uniformity Imaging Spectrometers
Bender, Holly A.; Mouroulis, Pantazis; Eastwood, Michael L.; Green, Robert O.; Geier, Sven; Hochberg, Eric B.
2011-01-01
Imaging spectrometers require precise adjustments, in some cases at the sub-micrometer level, in order to achieve auniform response over both the spectral and spatial dimensions. We describe a set of measurement techniques and theircorresponding alignment adjustments to achieve the 95% or higher uniformity specifications required for Earthobservingimaging spectrometers. The methods are illustrated with measurements from the Next Generation Imaging Spectrometer system that has been built at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
School uniforms: tradition, benefit or predicament?
Van Aardt, Annette Marie; Wilken, Ilani
2012-01-01
This article focuses on the controversies surrounding school uniforms. Roleplayers in this debate in South Africa are parents, learners and educators, and arguments centre on aspects such as identity, economy and the equalising effect of school uniforms, which are considered in the literature to be benefits. Opposing viewpoints highlight the fact that compulsory uniforms infringe on learners’ constitutional rights to self-expression. The aim of this research was to determine the perspectives ...
On the Compactly Locally Uniformly Rotund Points of Orlicz Spaces
Indian Academy of Sciences (India)
Lili Chen; Yunan Cui
2007-11-01
In this paper, locally uniformly rotund points and compactly locally uniformly rotund points are introduced. Moreover, criteria for compactly locally uniformly rotund points in Orlicz spaces are given.
Micro-cantilevers for non-destructive characterization of nanograss uniformity
DEFF Research Database (Denmark)
Petersen, Dirch Hjorth; Wang, Fei; Olesen, Mikkel Buster;
2011-01-01
measurements may be useful for process uniformity characterization. The method is applied for characterization of TiW coated nanograss uniformity. Three-way flexible L-shaped cantilever electrodes are used to avoid damage to the fragile surface, and a relative standard deviation on measurement repeatability...
A School Uniform Program That Works.
Loesch, Paul C.
1995-01-01
According to advocates, school uniforms reduce gang influence, decrease families' clothing expenditures, and help mitigate potentially divisive cultural and economic differences. Aiming to improve school climate, a California elementary school adopted uniforms as a source of pride and affiliation. This article describes the development of the…
School Dress Codes and Uniform Policies.
Anderson, Wendell
2002-01-01
Opinions abound on what students should wear to class. Some see student dress as a safety issue; others see it as a student-rights issue. The issue of dress codes and uniform policies has been tackled in the classroom, the boardroom, and the courtroom. This Policy Report examines the whole fabric of the debate on dress codes and uniform policies…
School Uniform Policies: Students' Views of Effectiveness.
McCarthy, Teresa M.; Moreno, Josephine
2001-01-01
Focus-group interviews of New York City middle-school students about their perceptions of the effectiveness of the school-uniform policy. Finds that students' perceptions of the effects of school-uniform policy on school culture varied considerably with those intended by the principal. (Contains 40 references.) (PKP)
School Uniforms and Discourses on Childhood.
Bodine, Ann
2003-01-01
This ethnographic study examined the introduction of school uniforms in the public schools of one California city. Findings indicated that the uniform issue intersected with issues such as student safety and violence, family stress, egalitarianism, competitive dressing, and a power struggle over shaping the childhood environment. It was concluded…
Radionic Non-uniform Stable Black Strings
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2003-01-01
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.
A Uniform Syntax and Discourse Structure
DEFF Research Database (Denmark)
Hardt, Daniel
2013-01-01
I present arguments in favor of the Uniformity Hypothesis: the hypothesis that discourse can extend syntax dependencies without conflicting with them. I consider arguments that Uniformity is violated in certain cases involving quotation, and I argue that the cases presented in the literature...
Uniformity in a Dual Assessment System
Chicoine, David L.; Giertz, J Fred
1988-01-01
Variation in property tax assessment uniformity is studied using data from a "dual" assessment structure where county assessment authority overlaps township assessing responsibility and elected local assessors work with appointed county assessment officers. Particular attention is given to the impact of the size and organization of assessment jurisdictions on assessment uniformity.
Radionic Non-Uniform Black Strings
Tamaki, T.; Kanno, S.; Soda, J.
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.
Dynamic Deformation of Uniform Elastic Two-Layer Objects
Song, Miao
2009-01-01
This thesis presents a two-layer uniform facet elastic object for real-time simulation based on physics modeling method. It describes the elastic object procedural modeling algorithm with particle system from the simplest one-dimensional object, to more complex two-dimensional and three-dimensional objects. The double-layered elastic object consists of inner and outer elastic mass spring surfaces and compressible internal pressure. The density of the inner layer can be set different from the ...
Uniform Deterministic Discrete Method for Three Dimensional Systems
Institute of Scientific and Technical Information of China (English)
无
1997-01-01
For radiative direct exchange areas in three dimensional system,the Uniform Deterministic Discrete Method(UDDM) was adopted.The spherical surface dividing method for sending area element and the regular icosahedron for sending volume element can meet with the direct exchange area computation of any kind of zone pairs.The numerical examples of direct exchange area in three dimensional system with nonhomogeneous attenuation coefficients indicated that the UDDM can give very high numercal accuracy.
A uniform parametrization of moment tensors
Tape, Walter; Tape, Carl
2015-09-01
A moment tensor is a 3 × 3 symmetric matrix that expresses an earthquake source. We construct a parametrization of the 5-D space of all moment tensors of unit norm. The coordinates associated with the parametrization are closely related to moment tensor orientations and source types. The parametrization is uniform, in the sense that equal volumes in the coordinate domain of the parametrization correspond to equal volumes of moment tensors. Uniformly distributed points in the coordinate domain therefore give uniformly distributed moment tensors. A cartesian grid in the coordinate domain can be used to search efficiently over moment tensors. We find that uniformly distributed moment tensors have uniformly distributed orientations (eigenframes), but that their source types (eigenvalue triples) are distributed so as to favour double couples.
Graded Achievement, Tested Achievement, and Validity
Brookhart, Susan M.
2015-01-01
Twenty-eight studies of grades, over a century, were reviewed using the argument-based approach to validity suggested by Kane as a theoretical framework. The review draws conclusions about the meaning of graded achievement, its relation to tested achievement, and changes in the construct of graded achievement over time. "Graded…
Aripov, K. K.; Rumyantsev, V. D.
1984-02-01
A simple method of calculating the current voltage characteristics of solar cells, based on an equivalent resistance diode ladder network with stripline contacts, is applied to such cells with uniform thickness and various shapes of the active surface. Distributed resistance are represented by equivalent lumped ones. This procedure is applied first to the case of uniform illumination, using measured current voltage characteristics of cells and very precisely piecewise linearly approximated exponential current voltage characteristics of diodes. In the case of nonuniform illumination the latter is assumed to be axisymmetric, with the surface consisting of completely dark and uniformly bright segments. Numerical data is generated on this basis for GaAs cells of rectangular or sectoral shape uniformly illuminated and in the shape of circular disks either completely uniformly illuminated or with various configurations of concentric dark and bright zones. Nonuniform illumination is found to result in a flatter current voltage characteristic with a lower open circuit voltage.
Current Flow in Uniform Ferromagnets: Bulk and Surface Heating Rates
Sears, Matthew R.; Saslow, Wayne M.
2011-01-01
With spintronics applications in mind, we use irreversible thermodynamics to derive the rates of entropy production and heating near an interface when heat current, electric current, and spin current cross it. Associated with these currents are apparent discontinuities in temperature (\\Delta T), electrochemical potential (\\Delta \\tilde {\\mu}), and spin-dependent "magnetoelectrochemical potential" (\\Delta \\bar \\mu_{\\uparrow,\\downarrow}). This work applies to magnetic semiconductors and insulat...
Uniformity of material in the SME and MFT
International Nuclear Information System (INIS)
The DWPF will satisfy the product consistency specification in the Waste Acceptance Preliminary Specifications through control of the chemical composition of the glass product. This control will be achieved by ensuring that each batch of feed in the Slurry Mix Evaporator (SME) will produce glass which satisfies the specification. The purpose of this report is to determine what degree of uniformity can be expected of material in the SME and Metter Feed Tank (MFT). These vessels were designed based on a design development process which had proven successful for similar hard-to-mix feeds in the past. This process resulted in a design of the SME and MFT agitation systems which was intended to provide highly uniform melter feed material. Based on the results of extensive tests in protoypic equipment, the SME and MFT designs have met this design goal
Capacitated Vehicle Routing with Non-Uniform Speeds
Gortz, Inge Li; Nagarajan, Viswanath; Ravi, R
2010-01-01
The capacitated vehicle routing problem (CVRP) involves distributing (identical) items from a depot to a set of demand locations, using a single capacitated vehicle. We study a generalization of this problem to the setting of multiple vehicles having non-uniform speeds (that we call Heterogenous CVRP), and present a constant-factor approximation algorithm. The technical heart of our result lies in achieving a constant approximation to the following TSP variant (called Heterogenous TSP). Given a metric denoting distances between vertices, a depot r containing k vehicles with possibly different speeds, the goal is to find a tour for each vehicle (starting and ending at r), so that every vertex is covered in some tour and the maximum completion time is minimized. This problem is precisely Heterogenous CVRP when vehicles are uncapacitated. The presence of non-uniform speeds introduces difficulties for employing standard tour-splitting techniques. In order to get a better understanding of this technique in our con...
Towards a Uniform Cooperative Platform: Cova Approach and Experience
Institute of Scientific and Technical Information of China (English)
SHI MeiLin(史美林); JIANG JinLei(姜进磊)
2003-01-01
A cooperative platform called Cova is presented, which aims to uniformly model a wide range of cooperation scenarios and to reduce the groupware design and development work. To achieve these goals, Cova provides two facilities, namely a specification language for developers to describe various cooperation modes uniformly and a run-time system that provides some generalpurposed services guaranteeing the semantics specified. With these facilities, the developers can then concentrate on the application specific functions rather than the control mechanisms. Therefore, the development efficiency is promoted. This paper details the design and implementation issues of the platform including the model and the specification language, platform architecture,transaction management, service integration and so on. Application development with Cova platform is also covered.
Quantification of perceived macro-uniformity
Lee, Ki-Youn; Bang, Yousun; Choh, Heui-Keun
2011-01-01
Macro-uniformity refers to the subjective impression of overall uniformity in the print sample. By the efforts of INCITS W1.1 team, macro-uniformity is categorized into five types of attributes: banding, streaks, mottle, gradients, and moiré patterns, and the ruler samples are generated with perceptual scales. W1.1 macro-uniformity ruler is useful for judging the levels of print defect, but it is not an easy task to reproduce the samples having the same perceptual scales at different times in different places. An objective quantification method is more helpful and convenient for developers to analyze print quality and design printing system components. In this paper, we propose a method for measuring perceived macro-uniformity for a given print using a flat-bed scanner. First, banding, 2D noise, and gradients are separately measured, and they are converted to the perceptual scales based on subjective results of each attribute. The correlation coefficients between the measured values of the attributes and the perceptual scales are 0.92, 0.97, and 0.86, respectively. Another subjective test is performed to find the relationship between the overall macro-uniformity and the three attributes. The weighting factors are obtained by the experimental result, and the final macro-uniformity grade is determined by the weighted sums of each attribute.
Whiteness formula in CIELAB uniform color space
Institute of Scientific and Technical Information of China (English)
Guoxin He; Mingxun Zhou
2007-01-01
@@ Many attempts have been made to standardize the calculation of whiteness. Whiteness formulas currently in use satisfactorily characterize the appearance of commercial whiteness. However, they have poor correlations with the observers' evaluations, and are often unsuccessful in assessing tinted white samples.A whiteness formula in the CIELAB uniform color space is developed in this paper. Several whiteness formulas are analyzed and compared. The experimental results show that the whiteness formula in the CIELAB uniform color space agrees well with the visual ranking, and it is superior to the CIE whiteness formula and the others in visual correlativity, uniformity and applicability.
Uniform supersaturated design and its construction
Institute of Scientific and Technical Information of China (English)
FANG; Kaitai(方开泰); GE; Gennian(葛根年); LIU; Minqian(刘民千)
2002-01-01
Supersaturated designs are factorial designs in which the number of main effects is greater than the number of experimental runs. In this paper, a discrete discrepancy is proposed as a measure of uniformity for supersaturated designs, and a lower bound of this discrepancy is obtained asa benchmark of design uniformity. A construction method for uniform supersaturated designs via resolvable balanced incomplete block designs is also presented along with the investigation of properties of the resulting designs. The construction method shows a strong link between these two different kinds of designs.
Electrode structure for uniform corona discharge
Gange, R. A.; Steinmetz, C. C.
1976-01-01
Single corona-discharge needle is used to apply uniform charge to thermoplastic medium in holograph-storage system. Needle is connected to flat transparent electrode that is parallel to thermoplastic.
Variational Principles in Fang Uniform Spaces
Turinici, Mihai
2010-01-01
The variational principle in Fang uniform spaces due to Hamel [Nonlin. Anal., 62 (2005), 913-924] is deductible from the generalized metric version of Ekeland's [Bull. A.M.S. (N. S.), 1 (1979), 443-474].
LIMITING BEHAVIOR OF UNIFORM RECURSIVE TREES
Institute of Scientific and Technical Information of China (English)
Su Chun; Feng Qunqiang; Liu Jie
2007-01-01
The authors consider the limiting behavior of various branches in a uniform recursive tree with size growing to infinity. The limiting distribution of ζn,m, the number of branches with size m in a uniform recursive tree of order n, converges weakly to a Poisson distribution with parameter 1/m with convergence of all moments. The size of any large branch tends to infinity almost surely.
Increase of linear size uniformity of synthetic diamond grinding powder
Ilnitskaya, G.; Bogatyreva, G.; Novikov, N.; Shepelev, A.; Nevstryev, G.; Leshchenko, O.
2008-07-01
It has been shown in article that increase of powder uniformity is achieved by carrying out additional sorting of powders in the sizes and form of grains. The sorting process includes the following stages: chemical rounding of diamond grains by strong oxidants; special grain size classification on sieves with mesh sizes corresponded to geometrical progression of twentieth (R-20) and fortieth (R-40) number series; additional separation of diamond grains in narrow graininess by grain form. Diamond powder of AC6 100/80 series has been produced by this technology, as a result of that the content of basic fraction runs up 85%.
Differential cross section for photoionization of a hydrogen atom in a uniform electric field
International Nuclear Information System (INIS)
The differential cross section for the photoionisation of an atom in a uniform electric field can be observed if the photocurrent is registered on a plane screen perpendicular to the uniform field axis. It manifests a complicated structure due to both resonance and interference effects which are interpreted in terms of the classical electron trajectories. In certain experimental conditions, the pattern can achieve a macroscopic size. Tentative suggestions for the applications of the differential cross section observation are discussed. (Author)
Urošević, Stevan Lj
2014-01-01
This paper defines new structures of highly unidirectional uniform optical grating couplers which are all within constraints of the standard 45nm SOI-CMOS foundry process. Analysis in terms of unidirectivity and coupling efficiency is done. Maximum achieved unidirectivity (power radiation in one direction) is 98%. Unidirectional uniform gratings are fabricated in the standard 45nm SOI-CMOS foundry process. These gratings are measured and compared, using the new method of comparison, with typical bidirectional uniform gratings fabricated in the same process, in terms of coupling efficiency (in this case unidirectivity) with the standard singlemode fiber. For both types of gratings spectrum is given, measured with optical spectrum analyzer.
Analytical examination of a spiral beam scanning method for uniform irradiation
Energy Technology Data Exchange (ETDEWEB)
Fukuda, Mitsuhiro; Okumura, Susumu; Arakawa, Kazuo [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment
1997-03-01
A new circular beam scanning method for uniform irradiation of high-energy, intense ion beams over a large area has been developed. A sweeping speed and a trajectory density in a radial direction are kept constant to obtain uniform fluence distribution. A radial position of a beam spot on a target and an angular frequency of the circular motion are expressed by an irrational function of time. The beam is swept continuously, and a beam trajectory becomes spiral. More than 90 % uniformity of the fluence distribution can been achieved over a large area. (author)
Toward Uniformly Dispersed Battery Electrode Composite Materials: Characteristics and Performance.
Kwon, Yo Han; Huie, Matthew M; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S; Reichmanis, Elsa
2016-02-10
Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches for improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. The study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials. PMID:26765041
Liu, Liang; Ma, Siyuan; Pei, Yunheng; Xiong, Xiao; Sivakumar, Preeth; Singler, Timothy J
2016-08-24
We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive
Liu, Liang; Ma, Siyuan; Pei, Yunheng; Xiong, Xiao; Sivakumar, Preeth; Singler, Timothy J
2016-08-24
We report a method to achieve highly uniform inkjet-printed silver nitrate (AgNO3) and a reactive silver precursor patterns on rigid and flexible substrates functionalized with polydopamine (PDA) coatings. The printed AgNO3 patterns on PDA-coated substrates (glass and polyethylene terephthalate (PET)) exhibit a narrow thickness distribution ranging between 0.9 and 1 μm in the line transverse direction and uniform deposition profiles in the line axial direction. The deposited reactive silver precursor patterns on PDA-functionalized substrates also show "dome-shaped" morphology without "edge-thickened" structure due to "coffee-stain" effect. We posit that the highly uniform functional ink deposits formed on PDA-coated substrates are attributable to the strong binding interaction between the abundant catecholamine moieties at the PDA surface and the metallic silver cations (Ag(+) or Ag(NH3)(2+)) in the solutal inks. During printing of the ink rivulet and solvent evaporation, the substrate-liquid ink (S-L) interface is enriched with the silver-based cations and a solidification at the S/L interface is induced. The preferential solidification initiated at the S-L interface is further verified by the in situ visualization of the dynamic solidification process during solvent evaporation, and results suggest an enhanced crystal nucleation and growth localized at the S-L interface on PDA functionalized substrates. This interfacial interaction mediates solute transport in the liquid phase, resulting in the controlled enrichment of solute at the S-L interface and mitigated solute precipitation in both the contact line region and the liquid ink-vapor (L-V) interface due to evaporation. This mediated transport contributes to the final uniform solid deposition for both types of ink systems. This technique provides a complementary strategy for achieving highly uniform inkjet-printed crystalline structures, and can serve as an innovative foundation for high-precision additive
The Pension Tangle: Achieving Greater Uniformity of Pension Legislation and Regulation in Canada
Gretchen Van Riesen
2009-01-01
Canada’s maze of differing pension regulations by province and territory discourages the creation of national, single-employer pension plans. Four options for reform – and greater harmonization – should be on the table.
A uniform parameterization of moment tensors
Tape, C.; Tape, W.
2015-12-01
A moment tensor is a 3 x 3 symmetric matrix that expresses an earthquake source. We construct a parameterization of the five-dimensional space of all moment tensors of unit norm. The coordinates associated with the parameterization are closely related to moment tensor orientations and source types. The parameterization is uniform, in the sense that equal volumes in the coordinate domain of the parameterization correspond to equal volumes of moment tensors. Uniformly distributed points in the coordinate domain therefore give uniformly distributed moment tensors. A cartesian grid in the coordinate domain can be used to search efficiently over moment tensors. We find that uniformly distributed moment tensors have uniformly distributed orientations (eigenframes), but that their source types (eigenvalue triples) are distributed so as to favor double couples. An appropriate choice of a priori moment tensor probability is a prerequisite for parameter estimation. As a seemingly sensible choice, we consider the homogeneous probability, in which equal volumes of moment tensors are equally likely. We believe that it will lead to improved characterization of source processes.
Nurses' uniform: an investigation of mobility.
Stubbs, D A; Buckle, P W; Hudson, M P; Butler, P E; Rivers, P M
1985-01-01
An investigation of the mobility of nurses under three clothing conditions is reported. The need for such a study has arisen as a result of the concern over a possible mismatch between mobility and patient handling requirements. Thirty-seven nurses participated under two of the clothing conditions ('National' dress uniform, Trouser/tunic combination). In addition, ten of these nurses volunteered to provide control data by being measured in a leotard or a swimming costume. Eleven static and sixteen dynamic anthropometric measures were considered. Each nurse was asked to complete a short questionnaire, relating to her subjective attitudes to the uniform and to her own physical state at the time of measurement. Whilst both uniforms imposed restrictions on the shoulder girdle and trunk of up to 10%, the area of greatest concern was the mobility of the hip joint. Hip flexion was reduced by 26% in the dress uniform. The implications of these findings for patient handling procedures are discussed, as are those of the relationship between the environment and the material. Uniform and the nursing image is also considered.
Uniform dimension results for Gaussian random fields
Institute of Scientific and Technical Information of China (English)
WU DongSheng; XIAO YiMin
2009-01-01
Let X = {X(t), t ∈ RN} be a Gaussian random field with values in Rd defined by x(t) = (x1(t),…,xd(t)), At∈RN.(1)The properties of space and time anisotropy of X and their connections to uniform Hausdorff dimension results are discussed. It is shown that in general the uniform Hausdorff dimension result does not hold for the image sets of a space-anisotropic Gaussian random field X. When X is an (N, d)-Gaussian random field as in (1), where X1,..., Xd are independent copies of a real valued, centered Gaussian random field Xo which is anisotropic in the time variable. We establish uniform Hausdorff dimension results for the image sets of X. These results extend the corresponding results on one-dimensional Brownian motion, fractional Brownian motion and the Brownian sheet.
Ultrasonic transducer design for uniform insonation
International Nuclear Information System (INIS)
Techniques used in transducer development for acoustical imaging have been evaluated for the purpose of producing broad, uniform ultrasonic fields from planar radiators. Such fields should be useful in hyperthermia, physical therapy, and ultrasonic bioeffects studies. Fourier inversion of the circ function yielded a source velocity distribution proportional to (P/r) exp ((-ik/2Z) (2Z/sup 2/+r/sup 2/)) J/sub 1/(krP/Z), where r is the radial source coordinate, k is the wave number, and P is the desired radius of uniform insonation at a depth Z in water. This source distribution can be truncated without significantly degrading the solution. A simpler solution consists of exponentially shading the edge of an otherwise uniformly excited disk transducer. This approach was successfully approximated experimentally
DEFF Research Database (Denmark)
Kohlenbach, Ulrich
2002-01-01
The so-called weak Konig's lemma WKL asserts the existence of an infinite path b in any infinite binary tree (given by a representing function f). Based on this principle one can formulate subsystems of higher-order arithmetic which allow to carry out very substantial parts of classical mathematics...... but are 20-conservative over primitive recursive arithmetic PRA (and even weaker fragments of arithmetic). In Kohlenbach [10] (J. Symbolic Logic 57 (1992) 1239-1273) we established such conservation results relative to finite type extensions PRA of PRA (together with a quantifier-free axiom of choice schema...... which-relative to PRA -implies the schema of 10-induction). In this setting one can consider also a uniform version UWKL of WKL which asserts the existence of a functional which selects uniformly in a given infinite binary tree f an infinite path f of that tree. This uniform version of WKL...
Uniform dimension results for Gaussian random fields
Institute of Scientific and Technical Information of China (English)
2009-01-01
Let X = {X(t),t ∈ RN} be a Gaussian random field with values in Rd defined by X(t) =(X1(t),...,Xd(t)), t ∈ RN.(1) The properties of space and time anisotropy of X and their connections to uniform Hausdorff dimension results are discussed.It is shown that in general the uniform Hausdorff dimension result does not hold for the image sets of a space-anisotropic Gaussian random field X.When X is an(N,d)-Gaussian random field as in(1),where X1,...,Xd are independent copies of a real valued,centered Gaussian random field X0 which is anisotropic in the time variable.We establish uniform Hausdorff dimension results for the image sets of X.These results extend the corresponding results on one-dimensional Brownian motion,fractional Brownian motion and the Brownian sheet.
Estimating achievement from fame
Simkin, M. V.; Roychowdhury, V. P.
2009-01-01
We report a method for estimating people's achievement based on their fame. Earlier we discovered (cond-mat/0310049) that fame of fighter pilot aces (measured as number of Google hits) grows exponentially with their achievement (number of victories). We hypothesize that the same functional relation between achievement and fame holds for other professions. This allows us to estimate achievement for professions where an unquestionable and universally accepted measure of achievement does not exi...
Uniform wire segmentation algorithm of distributed interconnects
Institute of Scientific and Technical Information of China (English)
Yin Guoli; Lin Zhenghui
2007-01-01
A uniform wire segmentation algorithm for performance optimization of distributed RLC interconnects was proposed in this paper. The optimal wire length for identical segments and buffer size for buffer insertion are obtained through computation and derivation, based on a 2-pole approximation model of distributed RLC interconnect. For typical inductance value and long wires under 180nm technology, experiments show that the uniform wire segmentation technique proposed in the paper can reduce delay by about 27% ～ 56% , while requires 34%～69% less total buffer usage and thus 29% to 58% less power consumption. It is suitable for long RLC interconnect performance optimization.
Uniform color space is not homogeneous
Kuehni, Rolf G.
2002-06-01
Historical data of chroma scaling and hue scaling are compared and evidence is shown that we do not have a reliable basis in either case. Several data sets indicate explicitly or implicitly that the number of constant sized hue differences between unique hues as well as in the quadrants of the a*, b* diagram differs making what is commonly regarded as uniform color space inhomogeneous. This problem is also shown to affect the OSA-UCS space. A Euclidean uniform psychological or psychophysical color space appears to be impossible.
Methods for obtaining a uniform volume concentration of implanted ions
International Nuclear Information System (INIS)
Three simple practical methods of irradiations with high energy particles providing the conditions for obtaining a uniform volume concentration of the implanted ions in the massive samples are described in the present paper. Realization of the condition of two-sided irradiation of a plane sample during its rotation in the flux of the projectiles is the basis of the first method. The use of free air as a filter with varying absorbent ability due to movement of the irradiated sample along ion beam brought to the atmosphere is at the basis of the second method of uniform ion alloying. The third method for obtaining a uniform volume concentration of the implanted ions in a massive sample consists of irradiation of a sample through the absorbent filter in the shape of a foil curved according to the parabolic law moving along its surface. The first method is the most effective for obtaining a great number of the samples, for example, for mechanical tests, the second one - for irradiation in different gaseous media, and the third one - for obtaining high concentrations of the implanted ions under controlled (regulated) thermal and deformation conditions. 2 refs., 7 figs
Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng
2013-11-21
NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times. PMID:24096887
Achieving Control of Coating Process in your Foundry
DEFF Research Database (Denmark)
Di Muoio, G. L.; Tiedje, N. S.
2015-01-01
Achieving control of coating thickness in foundry moulds is needed in order to guarantee uniform properties of the mould but also to achieve control of drying time. Since drying time of water based coatings is heavily dependent on the amount of water present in the coating layer, a stable coating...
Designing porous metallic glass compact enclosed with surface iron oxides
Energy Technology Data Exchange (ETDEWEB)
Cho, Jae Young; Park, Hae Jin; Hong, Sung Hwan; Kim, Jeong Tae; Kim, Young Seok; Park, Jun-Young; Lee, Naesung [Hybrid Materials Center (HMC), Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Seo, Yongho [Graphene Research Institute (GRI) & HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, Jin Man, E-mail: jinman_park@hotmail.com [Global Technology Center, Samsung Electronics Co., Ltd, 129 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-742 (Korea, Republic of); Kim, Ki Buem, E-mail: kbkim@sejong.ac.kr [Hybrid Materials Center (HMC), Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 209 Neungdong-ro, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)
2015-06-25
Highlights: • Porous metallic glass compact was developed using electro-discharge sintering process. • Uniform PMGC can only be achieved when low electrical input energy was applied. • Functional iron-oxides were formed on the surface of PMGCs by hydrothermal technique. - Abstract: Porous metallic glass compact (PMGC) using electro-discharge sintering (EDS) process of gas atomized Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} metallic glass powder was developed. The formation of uniform PMGC can only be achieved when low electrical input energy was applied. Functional iron-oxides were formed on the surface of PMGCs by hydrothermal technique. This finding suggests that PMGC can be applied in the new area such as catalyst via hydrothermal technique and offer a promising guideline for using the metallic glasses as a potential functional application.
Long and uniform plasma columns generated by linear field-applicators based on stripline technology
Energy Technology Data Exchange (ETDEWEB)
Pollak, J [Groupe de physique des plasmas, Universite de Montreal, C.P. 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Moisan, M [Groupe de physique des plasmas, Universite de Montreal, C.P. 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Zakrzewski, Z [Polish Academy of Sciences, IMP-PAN, 80-952 Gdansk (Poland)
2007-05-15
Long plasma columns generated by high-frequency (HF) fields and extending over distances longer than the free-space wavelength of the applied electromagnetic (EM) field are of interest in various applications. A commonly used method to achieve such long plasma columns calls for the propagation of EM surface waves that use the plasma as their propagating medium. In such a case, the HF field applicator, called a wave launcher, is much shorter than the actual length of the plasma column. Long plasma columns can also be sustained by using field applicators that run along the full length of the discharge tube. Most such linear applicators rely on waveguide components. However, it is possible to use transverse electric magnetic planar-transmission-lines based on stripline technology to design efficient linear field applicators. Using such an approach, we have developed a new type of HF linear field applicator that operates on a relatively wide frequency range (typically, 200-2450 MHz). Comparison of the discharge that it generates with a surface-wave discharge (SWD) sustained under similar operating conditions shows that the discharge volume is larger than that obtained with a SWD at the same power level, hence a lower gas temperature and a plasma column more axially uniform, two valuable features for some applications. The contraction of these plasma columns is shown to occur at higher gas pressures than with SWDs. All these measurements are carried out in argon as the discharge gas.
Uniform Or Free Dress Code in Schools
Erkan, Doç. Dr. Serdar
2003-01-01
This article attempts to synthesize opinions, results of experiments and research about school dress code policies. Synthesis suggests that there are positive as well as negative effects and consequences of mandatory school uniform policy. Pilot projects should be implemented and social and cultural effects should be examined prior to any decision regarding changes in current dress codes and policies.
School Uniforms in Urban Public High Schools
Draa, Virginia Ann Bendel
2005-01-01
The purpose of this study was to determine whether or not the implementation of a mandatory uniform policy in urban public high schools improved school performance measures at the building level for rates of attendance, graduation, academic proficiency, and student conduct as measured by rates of suspensions and expulsions. Sixty-four secondary…
UNIFORM QUASINILPOTENCY: DEFINITIONS, CONDITIONS, EXAMPLES OF APPLICATIONS
Sumin, Vladimir
2010-01-01
Definition of uniform quasinilpotent family of the operators and definition of superuniform quasinilpotent family of the operators are introduced. Corresponding conditions for functional operators are formulated. Applications of these definititions and conditions in the theory of controllable Volterra functional-operator equations are discussed. Financial support of Russian Fundamental Researches Fund (project 07-01-00495), analytical aimed departmental program "Development of Scientific Pote...
School Uniform Revisited: Procedure, Pressure and Equality
Carney, Damian; Sinclair, Adele
2006-01-01
The House of Lords' decision in "R. (on the application of Begum) v. The Headteacher and Governors of Denbigh High School" considered whether a particular school uniform policy infringed a student's right to manifest her religion under Article 9. This paper analyses the content of this decision, and explores how schools should approach the issue…
Product of n independent uniform random variables
Dettmann, Carl P.; Georgiou, Orestis
2009-01-01
Abstract We give an alternative proof of a useful formula for calculating the probability density function of the product of n uniform, independently and identically distributed random variables. Ishihara (2002, in Japanese) proves the result by induction; here we use Fourier analysis and contour integral methods which provide a more intuitive explanation of how the convolution theorem acts in this case. correspondance: Corresponding author. ...
Mandatory School Uniforms and Freedom of Expression
Vopat, Mark C.
2010-01-01
On 10 December 2007 the Akron City School Board--following the precedent set by many school systems across the United States and the world--instituted a policy of mandatory school uniforms for all students in grades K-8. The measure was met with mixed reviews. While many parents supported the measure, a small group of parents from a selective,…
Uniform infinite and Gibbs causal triangulations
Zohren, Stefan
2012-01-01
We discuss uniform infinite causal triangulations (UICT) and Gibbs causal triangulations which are probabilistic models for the causal dynamical triangulations (CDT) approach to quantum gravity. Since there is a bijection between causal triangulations and planar rooted trees we first discuss some as
Dynamic Uniform Scaling for Multiobjective Genetic Algorithms
DEFF Research Database (Denmark)
Pedersen, Gerulf; Goldberg, David E.
2004-01-01
Before Multiobjective Evolutionary Algorithms (MOEAs) can be used as a widespread tool for solving arbitrary real world problems there are some salient issues which require further investigation. One of these issues is how a uniform distribution of solutions along the Pareto non-dominated front c...
Uniforms: Are They a Good Fit?
Boutelle, Marsha
2008-01-01
In an era where some parents seem unwilling or unable to draw the "clothes" line with their children, where pop culture influences kids' clothing choices as never before, and school safety--including gang violence--is at the top of everyone's minds, school uniforms and dress codes can play a significant role. What that role should be, however, is…
MODERATOR ELEMENTS FOR UNIFORM POWER NUCLEAR REACTOR
Balent, R.
1963-03-12
This patent describes a method of obtaining a flatter flux and more uniform power generation across the core of a nuclear reactor. The method comprises using moderator elements having differing moderating strength. The elements have an increasing amount of the better moderating material as a function of radial and/or axial distance from the reactor core center. (AEC)
Downsampling Non-Uniformly Sampled Data
Directory of Open Access Journals (Sweden)
Fredrik Gustafsson
2007-10-01
Full Text Available Decimating a uniformly sampled signal a factor D involves low-pass antialias filtering with normalized cutoff frequency 1/D followed by picking out every Dth sample. Alternatively, decimation can be done in the frequency domain using the fast Fourier transform (FFT algorithm, after zero-padding the signal and truncating the FFT. We outline three approaches to decimate non-uniformly sampled signals, which are all based on interpolation. The interpolation is done in different domains, and the inter-sample behavior does not need to be known. The first one interpolates the signal to a uniformly sampling, after which standard decimation can be applied. The second one interpolates a continuous-time convolution integral, that implements the antialias filter, after which every Dth sample can be picked out. The third frequency domain approach computes an approximate Fourier transform, after which truncation and IFFT give the desired result. Simulations indicate that the second approach is particularly useful. A thorough analysis is therefore performed for this case, using the assumption that the non-uniformly distributed sampling instants are generated by a stochastic process.
UMAPRM: Uniformly sampling the medial axis
Yeh, Hsin-Yi Cindy
2014-05-01
© 2014 IEEE. Maintaining clearance, or distance from obstacles, is a vital component of successful motion planning algorithms. Maintaining high clearance often creates safer paths for robots. Contemporary sampling-based planning algorithms That utilize The medial axis, or The set of all points equidistant To Two or more obstacles, produce higher clearance paths. However, They are biased heavily Toward certain portions of The medial axis, sometimes ignoring parts critical To planning, e.g., specific Types of narrow passages. We introduce Uniform Medial Axis Probabilistic RoadMap (UMAPRM), a novel planning variant That generates samples uniformly on The medial axis of The free portion of C
Ma, Da; Tian, Shaomin; Baryza, Jeremy; Luft, J Christopher; DeSimone, Joseph M
2015-10-01
To achieve the great potential of siRNA based gene therapy, safe and efficient systemic delivery in vivo is essential. Here we report reductively responsive hydrogel nanoparticles with highly uniform size and shape for systemic siRNA delivery in vivo. "Blank" hydrogel nanoparticles with high aspect ratio were prepared using continuous particle fabrication based on PRINT (particle replication in nonwetting templates). Subsequently, siRNA was conjugated to "blank" nanoparticles via a disulfide linker with a high loading ratio of up to 18 wt %, followed by surface modification to enhance transfection. This fabrication process could be easily scaled up to prepare large quantity of hydrogel nanoparticles. By controlling hydrogel composition, surface modification, and siRNA loading ratio, siRNA conjugated nanoparticles were highly tunable to achieve high transfection efficiency in vitro. FVII-siRNA conjugated nanoparticles were further stabilized with surface coating for in vivo siRNA delivery to liver hepatocytes, and successful gene silencing was demonstrated at both mRNA and protein levels.
Perceptual uniformity of commonly used color spaces
Avanaki, Ali; Espig, Kathryn; Kimpe, Tom; Xthona, Albert; Marchessoux, Cedric; Rostang, Johan; Piepers, Bastian
2014-03-01
Use of color images in medical imaging has increased significantly the last few years. Color information is essential for applications such as ophthalmology, dermatology and clinical photography. Use of color at least brings benefits for other applications such as endoscopy, laparoscopy and digital pathology. Remarkably, as of today, there is no agreed standard on how color information needs to be visualized for medical applications. This lack of standardization results in large variability of how color images are visualized and it makes quality assurance a challenge. For this reason FDA and ICC recently organized a joint summit on color in medical imaging (CMI). At this summit, one of the suggestions was that modalities such as digital pathology could benefit from using a perceptually uniform color space (T. Kimpe, "Color Behavior of Medical Displays," CMI presentation, May 2013). Perceptually uniform spaces have already been used for many years in the radiology community where the DICOM GSDF standard provides linearity in luminance but not in color behavior. In this paper we quantify perceptual uniformity, using CIE's ΔE2000 as a color distance metric, of several color spaces that are typically used for medical applications. We applied our method to theoretical color spaces Gamma 1.8, 2.0, & 2.2, standard sRGB, and DICOM (correction LUT for gray applied to all primaries). In addition, we also measured color spaces (i.e., native behavior) of a high-end medical display (Barco Coronis Fusion 6MP DL, MDCC-6130), and a consumer display (Dell 1907FP). Our results indicate that sRGB & the native color space on the Barco Coronis Fusion exhibit the least non-uniformity within their group. However, the remaining degree of perceptual non-uniformity is still significant and there is room for improvement.
Development of Fresnel-based Concentrated Photovoltaic (CPV System with Uniform Irradiance
Directory of Open Access Journals (Sweden)
Irfan Ullah
2014-12-01
Full Text Available Different designs have been presented to achieve high concentration and uniformity for the concentrated photovoltaic (CPV system. Most of the designs have issues of low efficiency in terms of irradiance uniformity. To this end, we present a design methodology to increase irradiance uniformity over solar cell. The system consists of an eight-fold Fresnel lens as a primary optical element (POE and an optical lens, which consists of eight parts, as a secondary optical element (SOE. Sunlight is focused through the POE and then light is spread over cell through the SOE. In the design, maximum sunlight is passed over cell by minimizing losses. Results have shown that the proposed CPV design gives good irradiance uniformity. The concentration module based on this novel design is a promising option for the development of a cost-effective photovoltaic solar energy generation.
Longitudinal oscillations in a non-uniform spatially dispersive plasma
Energy Technology Data Exchange (ETDEWEB)
Calogeracos, Alex, E-mail: a.calogeracos@yahoo.co.uk
2015-03-15
Longitudinal oscillations of the electron fluid in the hydrodynamic model of a metal are examined with pressure effects taken into account. It is well-known that this entails spatial dispersion. The equilibrium electron number density is taken to be non-uniform and a non-self-adjoint fourth order differential equation obeyed by the electric potential is derived. A velocity potential necessary for the description of sound waves is introduced in the standard fashion and the generalized version of Bloch orthogonality appropriate to a non-uniform background is deduced. We observe a duality between electric and velocity potentials in the sense that the respective differential operators are adjoint to each other. The spectrum is calculated in the special case of an exponential profile for the equilibrium electron number density. The surface plasmons are connected with the analytic properties of the scattering amplitude in the complex plane. The phase shift at threshold is expressed in terms of the number of surface plasmon modes via an expression reminiscent of Levinson’s statement in quantum mechanics.
Molecular Dynamics Simulations of Janus Particle Dynamics in Uniform Flow
Archereau, Aurelien Y M; Willmott, Geoff R
2016-01-01
We use molecular dynamics simulations to study the dynamics of Janus particles, micro- or nanoparticles which are not spherically symmetric, in the uniform flow of a simple liquid. In particular we consider spheres with an asymmetry in the solid-liquid interaction over their surfaces and calculate the forces and torques experienced by the particles as a function of their orientation with respect to the flow. We also examine particles that are deformed slightly from a spherical shape. We compare the simulation results to the predictions of a previously introduced theoretical approach, which computes the forces and torques on particles with variable slip lengths or aspherical deformations that are much smaller than the particle radius. We find that there is good agreement between the forces and torques computed from our simulations and the theoretical predictions, when the slip condition is applied to the first layer of liquid molecules adjacent to the surface.
On the weak uniform rotundity of Banach spaces
Directory of Open Access Journals (Sweden)
Wen D. Chang
2003-01-01
Full Text Available We prove that if Xi,i=1,2,…, are Banach spaces that are weak* uniformly rotund, then their lp product space (p>1 is weak* uniformly rotund, and for any weak or weak* uniformly rotund Banach space, its quotient space is also weak or weak* uniformly rotund, respectively.
Uniform Algebras Over Complete Valued Fields
Mason, Jonathan W
2012-01-01
UNIFORM algebras have been extensively investigated because of their importance in the theory of uniform approximation and as examples of complex Banach algebras. An interesting question is whether analogous algebras exist when a complete valued field other than the complex numbers is used as the underlying field of the algebra. In the Archimedean setting, this generalisation is given by the theory of real function algebras introduced by S. H. Kulkarni and B. V. Limaye in the 1980s. This thesis establishes a broader theory accommodating any complete valued field as the underlying field by involving Galois automorphisms and using non-Archimedean analysis. The approach taken keeps close to the original definitions from the Archimedean setting. Basic function algebras are defined and generalise real function algebras to all complete valued fields. Several examples are provided. Each basic function algebra is shown to have a lattice of basic extensions related to the field structure. In the non-Archimedean settin...
Influence on discharge uniformity of electrodes configuration
Zheng Jian; Sui Zhan; Lu Jing Ping; Zheng Kui Xing; Zhang Xiong Jun; Dong Yun; Feng Bin
2002-01-01
Large area glow discharge plasma that is transparent and highly conductive can be used as electrodes in Pockels cell to extend the switch aperture. To investigate this technology, a glow discharging chamber with a clear aperture of 5 cm x 5 cm was constructed, and hollow cathode, button cathode, pin cathode, bar cathode and bar anode were designed and produced. Using CCD imaging system, the discharging uniformity of different cathodes was tested with bar anode and under the different pressure pre-ionization voltage and main discharging voltage. A uniform plasma can be obtained with a hollow cathode when the pre-ionization voltage is about 700 V, the pressure is about 30 Pa, and the main discharging voltage is about 4 kV, which can be used for the plasma electrode of Pockels cell
Non-uniform tube representation of proteins
DEFF Research Database (Denmark)
Hansen, Mikael Sonne
Treating the full protein structure is often neither computationally nor physically possible. Instead one is forced to consider various reduced models capturing the properties of interest. Previous work have used tubular neighborhoods of the C-alpha backbone. However, assigning a unique radius...... might not correctly capture volume exclusion - of crucial importance when trying to understand a proteins $3$d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X......-ray crystallographic resolution ~ 3Å while a varying radius accounts for the different sizes of side chains. Such a non-uniform tube better capture the protein geometry and has numerous applications in structural/computational biology from the classification of protein structures to sequence-structure prediction....
Non-Uniform Tube Representation of Proteins
DEFF Research Database (Denmark)
Hansen, Mikael Sonne
Treating the full protein structure is often neither computationally nor physically possible. Instead one is forced to consider various reduced models capturing the properties of interest. Previous work have used tubular neighborhoods of the C-alpha backbone. However, assigning a unique radius...... might not correctly capture volume exclusion - of crucial importance when trying to understand a protein's 3d-structure. We propose a new reduced model treating the protein as a non-uniform tube with a radius reflecting the positions of atoms. The tube representation is well suited considering X......-ray crystallographic resolution ~ 3Å while a varying radius accounts for the different sizes of side chains. Such a non-uniform tube better captures the protein geometry and has numerous applications in structural/computational biology from the classification of protein structures to sequence-structure prediction....
Dynamic Uniform Scaling for Multiobjective Genetic Algorithms
DEFF Research Database (Denmark)
Pedersen, Gerulf; Goldberg, D.E.
2004-01-01
Before Multiobjective Evolutionary Algorithms (MOEAs) can be used as a widespread tool for solving arbitrary real world problems there are some salient issues which require further investigation. One of these issues is how a uniform distribution of solutions along the Pareto non-dominated front can......, the issue of obtaining a diverse set of solutions for badly scaled objective functions will be investigated and proposed solutions will be implemented using the NSGA-II algorithm....
Enhanced temperature uniformity by tetrahedral laser heating
Schroers, Jan; Bossuyt, Sven; Rhim, Won-Kyu; Li, Jianzhong; Zhou, Zhenhua; Johnson, William L.
2004-01-01
emperature profile on a spherical sample that is heated by laser beams in various geometries while processed in vacuum is analyzed. Sample heating by one or four laser beams was considered. An analytical expression was derived for directional sample heating cases. It suggests an enhanced temperature uniformity over the samples when heated with four diffuse laser beams arranged in a tetrahedral geometry. This was experimentally verified by heating a spherical stainless steel sample by laser be...
Uniform convergence to equilibrium for granular media
Bolley, François; Guillin, Arnaud
2012-01-01
We study the long time asymptotics of a nonlinear, nonlocal equation used in the modelling of granular media. We prove a uniform exponential convergence to equilibrium for degenerately convex and non convex interaction or confinement potentials, improving in particular results by J. A. Carrillo, R. J. McCann and C. Villani. The method is based on studying the dissipation of the Wasserstein distance between a solution and the steady state.
Sequential Testing with Uniformly Distributed Size
Stanislav Anatolyev; Grigory Kosenok
2011-01-01
Sequential procedures of testing for structural stability do not provide enough guidance on the shape of boundaries that are used to decide on acceptance or rejection, requiring only that the overall size of the test is asymptotically controlled. We introduce and motivate a reasonable criterion for a shape of boundaries which requires that the test size be uniformly distributed over the testing period. Under this criterion, we numerically construct boundaries for most popular sequential tests...
Weighted averages, uniform distribution, and strict ergodicity
International Nuclear Information System (INIS)
A circle of problems related to the application of the Riesz and Voronoi summation methods in ergodic theory, number theory, and probability theory is considered. The first digit paradox is discussed, strengthenings of the classical result of Weyl on the uniform distribution of the fractional parts of the values of a polynomial are indicated, and the possibility of sharpening the Birkhoff-Khinchin ergodic theorem is considered. In conclusion, some unsolved problems are listed
Magnetic Propeller for Uniform Magnetic Field Levitation
Krinker, Mark; Bolonkin, Alexander
2008-01-01
Three new approaches to generating thrust in uniform magnetic fields are proposed. The first direction is based on employing Lorentz force acting on partial magnetically shielded 8-shaped loop with current in external magnetic field, whereby a net force rather than a torque origins. Another approach, called a Virtual Wire System, is based on creating a magnetic field having an energetic symmetry (a virtual wire), with further superposition of external field. The external field breaks the symm...
Beam uniformity of flat top lasers
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.
Directory of Open Access Journals (Sweden)
Ajab Akbarally
2007-06-01
Full Text Available A new subclass of analytic functions $ k-SP_\\lambda(\\alpha $ is introduced by applying certain operators of fractional calculus to $k$-uniformly starlike and $ k $-uniformly convex functions of order $ \\alpha $. Some theorems on coefficient bounds and growth and distortion theorems for this subclass are found. The radii of close to convexity, starlikeness and convexity for this subclass is also derived.
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.
Rapid magnetofluidic mixing in a uniform magnetic field.
Zhu, Gui-Ping; Nguyen, Nam-Trung
2012-11-21
This paper reports the investigation of mixing phenomena caused by the interaction between a uniform magnetic field and a magnetic fluid in a microfluidic chamber. The flow system consists of a water-based ferrofluid and a mixture of DI water and glycerol. Under a uniform magnetic field, the mismatch in magnetization of the fluids leads to instability at the interface and subsequent rapid mixing. The mismatch of magnetization is determined by concentration of magnetic nanoparticles. Full mixing at a relatively low magnetic flux density up to 10 mT can be achieved. The paper discusses the impact of key parameters such as magnetic flux density, flow rate ratio and viscosity ratio on the mixing efficiency. Two main mixing regimes are observed. In the improved diffusive mixing regime under low field strength, magnetic particles of the ferrofluid migrate into the diamagnetic fluid. In the bulk transport regime under high field strength, the fluid system is mixed rapidly by magnetically induced secondary flow in the chamber. The mixing concept potentially provides a wireless solution for a lab-on-a-chip system that is low-cost, robust, free of induced heat and independent of pH level or ion concentration. PMID:22990170
Uniform Doping in Quantum-Dots-Based Dilute Magnetic Semiconductor.
Saha, Avijit; Shetty, Amitha; Pavan, A R; Chattopadhyay, Soma; Shibata, Tomohiro; Viswanatha, Ranjani
2016-07-01
Effective manipulation of magnetic spin within a semiconductor leading to a search for ferromagnets with semiconducting properties has evolved into an important field of dilute magnetic semiconductors (DMS). Although a lot of research is focused on understanding the still controversial origin of magnetism, efforts are also underway to develop new materials with higher magnetic temperatures for spintronics applications. However, so far, efforts toward quantum-dots(QDs)-based DMS materials are plagued with problems of phase separation, leading to nonuniform distribution of dopant ions. In this work, we have developed a strategy to synthesize highly crystalline, single-domain DMS system starting from a small magnetic core and allowing it to diffuse uniformly inside a thick CdS semiconductor matrix and achieve DMS QDs. X-ray absorption fine structure (XAFS) spectroscopy and energy-dispersive X-ray spectroscopy-scanning transmission electron microscopy (STEM-EDX) indicates the homogeneous distribution of magnetic impurities inside the semiconductor QDs leading to superior magnetic property. Further, the versatility of this technique was demonstrated by obtaining ultra large particles (∼60 nm) with uniform doping concentration as well as demonstrating the high quality magnetic response. PMID:27295453
Uniform Doping in Quantum-Dots-Based Dilute Magnetic Semiconductor.
Saha, Avijit; Shetty, Amitha; Pavan, A R; Chattopadhyay, Soma; Shibata, Tomohiro; Viswanatha, Ranjani
2016-07-01
Effective manipulation of magnetic spin within a semiconductor leading to a search for ferromagnets with semiconducting properties has evolved into an important field of dilute magnetic semiconductors (DMS). Although a lot of research is focused on understanding the still controversial origin of magnetism, efforts are also underway to develop new materials with higher magnetic temperatures for spintronics applications. However, so far, efforts toward quantum-dots(QDs)-based DMS materials are plagued with problems of phase separation, leading to nonuniform distribution of dopant ions. In this work, we have developed a strategy to synthesize highly crystalline, single-domain DMS system starting from a small magnetic core and allowing it to diffuse uniformly inside a thick CdS semiconductor matrix and achieve DMS QDs. X-ray absorption fine structure (XAFS) spectroscopy and energy-dispersive X-ray spectroscopy-scanning transmission electron microscopy (STEM-EDX) indicates the homogeneous distribution of magnetic impurities inside the semiconductor QDs leading to superior magnetic property. Further, the versatility of this technique was demonstrated by obtaining ultra large particles (∼60 nm) with uniform doping concentration as well as demonstrating the high quality magnetic response.
Ultraporous films with uniform nanochannels by block copolymer micelles assembly
Nunes, Suzana Pereira
2010-10-12
Films with high pore density and regularity that are easy to manufacture by conventional large-scale technology are key components aimed for fabrication of new generations of magnetic arrays for storage media, medical scaffolds, and artificial membranes. However, potential manufacture strategies like the self-assembly of block copolymers, which lead to amazing regular patterns, could be hardly reproduced up to now using commercially feasible methods. Here we report a unique production method of nanoporous films based on the self-assembly of copper(II) ion-polystyrene-b-poly(4-vinylpyridine) complexes and nonsolvent induced phase separation. Extremely high pore densities and uniformity were achieved. Water fluxes of 890 L m-2 h-1 bar-1 were obtained, which are at least 1 order of magnitude higher than those of commercially available membranes with comparable pore size. The pores are also stimuli (pH)-responsive. © 2010 American Chemical Society.
Student academic achievement in college chemistry
Tabibzadeh, Kiana S.
General Chemistry is required for variety of baccalaureate degrees, including all medical related fields, engineering, and science majors. Depending on the institution, the prerequisite requirement for college level General Chemistry varies. The success rate for this course is low. The purpose of this study is to examine the factors influencing student academic achievement and retention in General Chemistry at the college level. In this study student achievement is defined by those students who earned grades of "C" or better. The dissertation contains in-depth studies on influence of Intermediate Algebra as a prerequisite compared to Fundamental Chemistry for student academic achievement and student retention in college General Chemistry. In addition the study examined the extent and manner in which student self-efficacy influences student academic achievement in college level General Chemistry. The sample for this part of the study is 144 students enrolled in first semester college level General Chemistry. Student surveys determined student self-efficacy level. The statistical analyses of study demonstrated that Fundamental Chemistry is a better prerequisite for student academic achievement and student retention. The study also found that student self-efficacy has no influence on student academic achievement. The significance of this study will be to provide data for the purpose of establishing a uniform and most suitable prerequisite for college level General Chemistry. Finally the variables identified to influence student academic achievement and enhance student retention will support educators' mission to maximize the students' ability to complete their educational goal at institutions of higher education.
Radiative processes of uniformly accelerated entangled atoms
Menezes, G
2015-01-01
We study radiative processes of uniformly accelerated entangled atoms, interacting with an electromagnetic field prepared in the Minkowski vacuum state. We discuss the structure of the rate of variation of the atomic energy for two atoms travelling in different hyperbolic world lines. We identify the contributions of vacuum fluctuations and radiation reaction to the generation of entanglement as well as to the decay of entangled states. Our results resemble the situation in which two inertial atoms are coupled individually to two spatially separated cavities at different temperatures. In addition, for equal accelerations we obtain that the maximally entangled antisymmetric Bell state is a decoherence-free state.
Uniform Approximation of Vapnik-Chervonenkis Classes
Adams, Terrence M
2010-01-01
For any family of measurable sets in a probability space, we show that either (i) the family has infinite Vapnik-Chervonenkis (VC) dimension or (ii) for every epsilon > 0 there is a finite partition pi such the pi-boundary of each set has measure at most epsilon. Immediate corollaries include the fact that a family with finite VC dimension has finite bracketing numbers, and satisfies uniform laws of large numbers for every ergodic process. From these corollaries, we derive analogous results for VC major and VC graph families of functions.
A uniform system for evaluation of substances
Energy Technology Data Exchange (ETDEWEB)
Zandt, P.T.J. van der [Directorate-General for Environmental Protection, The Hague (Netherlands); Vermeire, T.J. [National Inst. for Public Health and Environmental Protection, Bilthoven (Netherlands); Roelfzeme, H. [Directorate-General for Public Health, Rijswijk (Netherlands)
1994-12-31
One of the action points that have been formulated in the Netherlands` first Environmental Policy Plan was the development, in co-operation with industry, of a system for the rapid screening of potential risks of chemicals. In the ``Uniform System for Evaluation of Substances`` (USES 1.0) project different methods for assessment of risks to man and environment that had been developed for new and existing substances and pesticides have been integrated and harmonized. USES 1.0 provides a decision-supporting tool that may be applied by governments and industries in both nation and international (OECD, EU) risk management processes.
Quantum Radiation of Uniformly Accelerated Spherical Mirrors
Frolov, V
2001-01-01
We study quantum radiation generated by a uniformly accelerated motion of small spherical mirrors. To obtain Green's function for a scalar massless field we use Wick's rotation. In the Euclidean domain the problem is reduced to finding an electric potential in 4D flat space in the presence of a metallic toroidal boundary. The latter problem is solved by a separation of variables. After performing an inverse Wick's rotation we obtain the Hadamard function in the wave-zone regime and use it to calculate the vacuum fluctuations and the vacuum expectation for the energy density flux in the wave zone.
Radionic Non-uniform Black Strings
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2003-01-01
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of the black strings. From the brane point of view, the black string appears as the deformed dilatonic black hole which becomes dilatonic black hole in the single brane limit and reduces to the Reissner-Nordstr\\"om black hole in the close limit of two-branes. The stability of solutions is demonstrated using the catastrophe theory. From ...
Killing Microorganisms with the One Atmosphere Uniform Glow Discharge Plasma
South, Suzanne; Kelly-Wintenberg, Kimberly; Montie, T. C.; Reece Roth, J.; Sherman, Daniel; Morrison, Jim; Chen, Zhiyu; Karakaya, Fuat
2000-10-01
There is an urgent need for the development of new technologies for sterilization and decontamination in the fields of healthcare and industrial and food processing that are safe, cost-effective, broad-spectrum, and not deleterious to samples. One technology that meets these criteria is the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). The OAUGDP operates in air and produces uniform plasma without filamentary discharges at room temperature, making this technology advantageous for sterilization of heat sensitive materials. The OAUGDP operates in a frequency band determined by the ion trapping mechanisms provided that, for air, the electric field is above 8.5kV/cm. The OAUGDP efficiently generates plasma reactive oxygen species (ROS) including atomic oxygen and oxygen free radicals without the requirement of a vacuum system. We have demonstrated the efficacy of the OAUGDP in killing microorganisms including bacteria, yeast, viruses, and spores in seconds to minutes on a variety of surfaces such as glass, films and fabrics, stainless steel, paper, and agar.
Elastic deformations driven by non-uniform lubrication flows
Rubin, Shimon; Gat, Amir; Bercovici, Moran
2016-01-01
The ability to create dynamic deformations of micron-sized structures is relevant to a wide variety of applications such as adaptable optics, soft robotics, and reconfigurable microfluidic devices. In this work we examine non-uniform lubrication flow as a mechanism to create complex deformation fields in an elastic plate. We consider a Kirchoff-Love elasticity model for the plate and Hele-Shaw flow in a narrow gap between the plate and a parallel rigid surface. Based on linearization of the Reynolds equation, we obtain a governing equation which relates elastic deformations to gradients in non-homogenous physical properties of the fluid (e.g. body forces, viscosity, and slip velocity). We then focus on a specific case of non-uniform Helmholtz-Smoluchowski electroosmotic slip velocity, and provide a method for determining the zeta-potential distribution necessary to generate arbitrary static and quasi-static deformations of the elastic plate. Extending the problem to time-dependent solutions, we analyze transi...
Chitta, Subhashini; Steinhoff, John
2015-11-01
This paper describes the use of Vorticity Confinement (VC) to efficiently treat complex blunt bodies with thin shed vortex sheets and attached boundary layers. Because these flows involve turbulence in the vortical regions, there is currently no ab initio method to treat them on current or foreseeable computers. In fact, in spite of years of turbulence modeling efforts (such as LES or RANS), serious flaws in aerodynamic design involving vortex shedding may still be left undetected until the expensive prototype or production stage. Our basic premise is that, for a class of real-world problems requiring simulating ensembles of flow conditions for overall accuracy, conventional turbulence models suffer cost constraints. For these reasons, VC is used to rapidly simulate many operating conditions, as is often done in expensive testing programs for flying prototypes, and in realistic simulations. To achieve dramatically lower computational cost, VC treats the entire flow in a uniform, coarse grid with solid surfaces ``immersed'' in the grid so that they can be quickly generated for many configurations with no requirement for adaptive or conforming fine grids. Also, the VC method has the efficiency of panel methods, but the generality and ease of use of Euler equation methods. We would like to thank Dr. Frank Caradonna for his suggestions and support.
Zeng, Gaofeng
2014-03-01
An Ag-controlled co-plating method was developed for the preparation of palladium/silver alloy membranes on porous tubular alumina supports. By controlling the feed rate of Ag to the Pd bath, the concentration of the silver in the plating bath was restricted during the course of plating. As a result, preferential deposition of silver at the beginning was suppressed and uniform dispersion of silver inside the membrane with silver composition in the desired range was achieved. Ultrathin (∼2.5 μm) PdAg alloy membranes with uniform silver composition of ∼25% were successfully obtained. The membrane showed a hydrogen permeance of 0.88 mol m-2 s-1 and pure-gas H2/N2 selectivity of 2140 at 823 K with ΔP = 100 kPa. Only one hydride phase existed in the studied temperature range from 373 to 823 K with ΔPH=100kPa. Direct comparisons with the conventional simply-mixed co-plating method showed that membranes made by the novel Ag-controlled co-plating method had much more uniform silver distribution, smoother surface, denser membrane structure, higher utilization rate of metal sources, and shorter alloying time. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Chen, Chia-Yun; Hsu, Li-Jen; Hsiao, Po-Hsuan; Yu, Chang-Tze Ricky
2015-11-01
We present a facile, reliable and controllable two-steps electroless deposition for uniformly decorating the silver (Ag) nanoparticles (NPs) on the highly aspect ratio of silicon (Si) nanowire arrays. Different from the direct Ag-loading process, which is normally challenged by the non-uniform coating of Ag, the formation of Ag NPs using such innovative electroless process is no longer to be limited at top nanowire surfaces solely; instead, each Ag+/Si interface can initiate the galvanic reduction of Ag+ ions, thus resulting in the uniform formation of Ag NPs on the entire Si nanowire arrays. In addition, systematic explorations of surface-enhanced Raman scattering (SERS) capability as well as antibacterial activity of the Ag/Si-incorporated nanostructures were performed, and the optimized Ag loadings on Si nanowire-based substrates along with the kinetic investigations were further revealed, which may benefit their practical applications in sensing, medical and biological needs.
Uniformly accelerated observer in a thermal bath
Kolekar, Sanved
2013-01-01
We investigate the quantum field aspects in flat spacetime for an uniformly accelerated observer moving in a thermal bath. In particular, we obtain an exact closed expression of the reduced density matrix for an uniformly accelerated observer with acceleration $a = 2\\pi T$ when the state of the quantum field is a thermal bath at temperature $T^\\prime$. We find that the density matrix has a simple form with an effective partition function $Z$ being a product, $Z = Z_T Z_{T^\\prime}$, of two thermal partition functions corresponding to temperatures $T$ and $T^\\prime$ and hence is not thermal, even when $T = T^\\prime$. We show that, even though the partition function has a product structure, the two thermal baths are, in fact, interacting systems; although in the high frequency limit $\\omega_k \\gg T$ and $\\omega_k \\gg T^\\prime$, the interactions are found to become sub-dominant. We further demonstrate that the resulting spectrum of the Rindler particles can be interpreted in terms of spontaneous and stimulated em...
Lang's conjectures, conjecture H, and uniformity
Abramovich, D
1995-01-01
The purpose of this note is to wish a happy birthday to Professor Lucia Caporaso.* We prove that Conjecture H of Caporaso et. al. ([CHarM], sec. 6) together with Lang's conjecture implies the uniformity of rational points on varieties of general type, as predicted in [CHarM]; a few applications in arithmetic and geometry are stated. Let X be a variety of general type defined over a number field K. It was conjectured by S. Lang that the set of rational points X(K) is not Zariski dense in X. In the paper [CHarM] of L. Caporaso, J. Harris and B. Mazur it is shown that the above conjecture of Lang implies the existence of a uniform bound on the number of K-rational points of all curves of fixed genus g over K. The paper [CHarM] has immediately created a chasm among arithmetic geometers. This chasm, which often runs right in the middle of the personalities involved, divides between loyal believers of Lang's conjecture, who marvel in this powerful implication, and the disbelievers, who try (so far in vain) to use t...
Energy Technology Data Exchange (ETDEWEB)
T.R. Bieler; D. Baars; K.T. Hartwig; C. Compton; T.L. Grimm
2009-05-26
Two strategies for improving the surface finish of niobium sheet used in superconducting radio frequency cavities were examined, using slices of single (or large-grain) material from an ingot, and equal channel angle extrusion (ECAE) preprocessing of ingot material to achieve a uniform and small grain size prior to subsequent rolling. The effect of these two processing paths on final microstructure, texture, and surface finish are discussed.
Automated design of a uniform distribution using faceted reflectors
Cassarly, William J.; David, Stuart R.; Jenkins, David G.; Riser, Andrew; Davenport, Thomas L.
2000-07-01
Faceted reflectors are a ubiquitous means for providing uniform illumination in many commercial lighting products, examples being newer flashlights, department-store display lighting, and the faceted reflectors found in overhead projectors. However, the design of faceted reflectors using software has often been more limited by the tools available to design them than by the imagination of the designers. One of the keys to enabling a broader range of design options has been to allow more complex surfaces using constructive solid geometry (CSG). CSG uses Boolean operations on basic geometric primitives to define shapes to create individual facets. In this paper, we describe an improved faceted reflector design algorithm and use it to create a wide range of CSG-based reflectors. The performance of various reflectors is compared using a Monte Carlo ray-trace method.
College Achievement and Earnings
Gemus, Jonathan
2010-01-01
I study the size and sources of the monetary return to college achievement as measured by cumulative Grade Point Average (GPA). I first present evidence that the return to achievement is large and statistically significant. I find, however, that this masks variation in the return across different groups of people. In particular, there is no relationship between GPA and earnings for graduate degree holders but a large and positive relationship for people without a graduate degree. To reconcile...
Characterizing uniform star formation efficiencies with marginally stable galactic discs
Wong, O. Ivy; Meurer, G. R.; Zheng, Z.; Heckman, T. M.; Thilker, D. A.; Zwaan, M. A.
2016-07-01
We examine the H I-based star formation efficiency (SFE_{H I}), the ratio of star formation rate to the atomic hydrogen (H I) mass, in the context of a constant stability star-forming disc model. Our observations of H I-selected galaxies show SFE_{H I} to be fairly constant (log SFE_{H I}=-9.65 yr-1 with a dispersion of 0.3 dex) across ˜5 orders of magnitude in stellar masses. We present a model to account for this result, whose main principle is that the gas within galaxies forms a uniform stability disc and that stars form within the molecular gas in this disc. We test two versions of the model differing in the prescription that determines the molecular gas fraction, based on either the hydrostatic pressure or the stellar surface density of the disc. For high-mass galaxies such as the Milky Way, we find that either prescription predicts SFE_{H I} similar to the observations. However, the hydrostatic pressure prescription is a more accurate SFE_{H I} predictor for low-mass galaxies. Our model is the first model that links the uniform SFE_{H I} observed in galaxies at low redshifts to star-forming discs with constant marginal stability. While the rotational amplitude Vmax is the primary driver of disc structure in our model, we find that the specific angular momentum of the galaxy may play a role in explaining a weak correlation between SFE_{H I} and effective surface brightness of the disc.
Kwon, Soon Gu; Hyeon, Taeghwan
2008-12-01
Nanocrystals exhibit interesting electrical, optical, magnetic, and chemical properties not achieved by their bulk counterparts. Consequently, to fully exploit the potential of nanocrystals, the synthesis of nanocrystals must focus on producing materials with uniform size and shape. Top-down physical processes can produce large quantities of nanocrystals, but controlling the size is difficult with these methods. On the other hand, colloidal chemical synthetic methods can produce uniform nanocrystals with a controlled particle size. In this Account, we present our synthesis of uniform nanocrystals of various shapes and materials, and we discuss the kinetics of nanocrystal formation. We employed four different synthetic approaches including thermal decomposition, nonhydrolytic sol-gel reactions, thermal reduction, and use of reactive chalcogen reagents. We synthesized uniform oxide nanocrystals via heat-up methods. This method involved slowly heat-up reaction mixtures composed of metal precursors, surfactants, and solvents from room temperature to high temperature. We then held reaction mixtures at an aging temperature for a few minutes to a few hours. Kinetics studies revealed a three-step mechanism for the synthesis of nanocrystals through the heat-up method with size distribution control. First, as metal precursors thermally decompose, monomers accumulate. At the aging temperature, burst nucleation occurs rapidly; at the end of this second phase, nucleation stops, but continued diffusion-controlled growth leads to size focusing to produce uniform nanocrystals. We used nonhydrolytic sol-gel reactions to synthesize various transition metal oxide nanocrystals. We employed ester elimination reactions for the synthesis of ZnO and TiO(2) nanocrystals. Uniform Pd nanoparticles were synthesized via a thermal reduction reaction induced by heating up a mixture of Pd(acac)(2), tri-n-octylphosphine, and oleylamine to the aging temperature. Similarly, we synthesized
Krupiński, Michał; Bareła, Jaroslaw; Firmanty, Krzysztof; Kastek, Mariusz
2013-10-01
Uneven response of particular detectors (pixels) to the same incident power of infrared radiation is an inherent feature of microbolometer focal plane arrays. As a result an image degradation occurs, known as Fixed Pattern Noise (FPN), which distorts the thermal representation of an observed scene and impairs the parameters of a thermal camera. In order to compensate such non-uniformity, several NUC correction methods are applied in digital data processing modules implemented in thermal cameras. Coefficients required to perform the non-uniformity correction procedure (NUC coefficients) are determined by calibrating the camera against uniform radiation sources (blackbodies). Non-uniformity correction is performed in a digital processing unit in order to remove FPN pattern in the registered thermal images. Relevant correction coefficients are calculated on the basis of recorded detector responses to several values of radiant flux emitted from reference IR radiation sources (blackbodies). The measurement of correction coefficients requires specialized setup, in which uniform, extended radiation sources with high temperature stability are one of key elements. Measurement stand for NUC correction developed in Institute of Optoelectronics, MUT, comprises two integrated extended blackbodies with the following specifications: area 200×200 mm, stabilized absolute temperature range +15 °C÷100 °C, and uniformity of temperature distribution across entire surface +/-0.014 °C. Test stand, method used for the measurement of NUC coefficients and the results obtained during the measurements conducted on a prototype thermal camera will be presented in the paper.
Code Compliant School Buildings Boost Student Achievement
Directory of Open Access Journals (Sweden)
Ronald B. Lumpkin
2014-11-01
Full Text Available Much of the focus in the literature in raising student achievement has included parental involvement, principal leadership, quality of instruction, students’ socioeconomic status, curriculum, and use of technology. Limited empirical research relates the condition of the school building as a variable that affects student achievement. Furthermore, there is no research that has examined the impact of building codes on achievement outcomes in the state of Florida. This research determined whether academic achievement of 4th-, 8th-, 9th-, and 10th-grade students as measured by the mathematics and reading subtests of the Florida Comprehensive Achievement Test (FCAT increased in new school buildings compliant to the 2000 Florida State Requirements for Educational Facilities. A causal-comparative design determined whether the independent variables, old and new school building influenced student achievement as measured by students’ FCAT mathematics and reading subtest scores. The control group was two cohorts of 4th-, 8th-, 9th-, and 10th-grade students who attended school in old buildings. The experimental group was two cohorts of 4th-, 8th-, 9th-, and 10th-grade students who attended school in new buildings. Transition from an old school into a new school was the treatment. Two hypotheses were formulated for testing and the research question for the inquiry was whether the percentage of students passing the FCAT mathematics and reading subtests increases after transitioning from an old school building into a new 2000 UBC (Uniform Building Code compliant facility.
Complex locally uniform rotundity of Musielak-Orlicz spaces
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The concepts of complex locally uniform rotundity and complex locally uniformly rotund point are introduced. The sufficient and necessary conditions of them are given in complex Musielak-Orlicz spaces.
78 FR 34020 - Federal Acquisition Regulation; Uniform Procurement Identification
2013-06-06
... procurement transactions. A number of public comments received during the rulemaking process expressed... 9000-AM60 Federal Acquisition Regulation; Uniform Procurement Identification AGENCY: Department of... Acquisition Regulation (FAR) to implement a uniform Procurement Instrument Identification (PIID)...
Energy Technology Data Exchange (ETDEWEB)
Woof, M.
2003-12-01
The paper reports on mechanical rock cutting in surface mining. Mining technology has moved a long way in recent years and the mining equipments achieved considerable success in direct rock cutting. 3 figs.
Rojas-Trigos, J. B.; Bermejo-Arenas, J. A.; Marin, E.
2012-01-01
In this paper, some heat transfer characteristics through a sample that is uniformly heated on one of its surfaces by a power density modulated by a periodical square wave are discussed. The solution of this problem has two contributions, comprising a transient term and an oscillatory term, superposed to it. The analytical solution is compared to…
Liouville theory and uniformization of four-punctured sphere
Hadasz, L; Hadasz, Leszek; Jaskolski, Zbigniew
2006-01-01
Few years ago Zamolodchikov and Zamolodchikov proposed an expression for the 4-point classical Liouville action in terms of the 3-point actions and the classical conformal block. In this paper we develop a method of calculating the uniformizing map and the uniformizing group from the classical Liouville action on n-punctured sphere and discuss the consequences of Zamolodchikovs conjecture for an explicit construction of the uniformizing map and the uniformizing group for the sphere with four punctures.
Uniform Approximation and Bracketing Properties of VC classes
Adams, Terrence M
2010-01-01
We show that the sets in a family with finite VC dimension can be uniformly approximated within a given error by a finite partition. Immediate corollaries include the fact that VC classes have finite bracketing numbers, satisfy uniform laws of averages under strong dependence, and exhibit uniform mixing. Our results are based on recent work concerning uniform laws of averages for VC classes under ergodic sampling.
A Computer Method of Steady Non-Uniform Gradually Varied Flow in Open Channel & in River
Institute of Scientific and Technical Information of China (English)
无
1999-01-01
Most of water flow in open channel or in river belongs to steady non-uniform flow. The surface profiles are caused by changes of channel section. It is very important to analyze its computation. According to the regularity of its surface change, the suitable sectional dimensions of open channel or flood control work can be designed. Commonly, computation of non-uniform flow adopts the traditional methods by hand or by graphic method. The speed and precision of computation are restricted. In this paper, a software to calculate water surface profile is introduced. The software is put forward by using C++ .By means of interpolate method and dialogue between user and computer, we can calculate the water surface profile much more quickly and exactly.
Reflective optics system for uniform spherical illumination.
Phipps, C R; Bodner, S E; Shearer, J W
1975-04-01
A reflective optical system is described that permits nearly uniform illumination of a small sphere with one or two laser beams. The primary application of this device is to studies of laser-driven implosion of small targets. Other applications include the production of plasma by optical breakdown of gases for spectroscopic studies and for optimum light collection in intensity-limited plasma diagnostics. Simple calculations show that the intensity mapping properties of this system are not excessively sensitive to variations in the radial intensity distribution nor to departures from diffraction-limited propagation in the input beams. Optical damage and the illuminated solid angle required at the focus determine the size of the device. PMID:20135009
Uniform trigonometric polynomial B-spline curves
Institute of Scientific and Technical Information of China (English)
吕勇刚; 汪国昭; 杨勋年
2002-01-01
This paper presents a new kind of uniform spline curve, named trigonometric polynomialB-splines, over space Ω = span{sint, cost, tk-3,tk-4,…,t,1} of which k is an arbitrary integerlarger than or equal to 3. We show that trigonometric polynomial B-spline curves have many similarV properties to traditional B-splines. Based on the explicit representation of the curve we have also presented the subdivision formulae for this new kind of curve. Since the new spline can include both polynomial curves and trigonometric curves as special cases without rational form, it can be used as an efficient new model for geometric design in the fields of CAD/CAM.
Frames of most uniform Hubble flow
Kraljic, David
2016-01-01
It has been observed that the locally measured Hubble parameter converges quickest to the background value and the dipole structure of the velocity field is smallest in the reference frame of the Local Group of galaxies. We study the statistical properties of Lorentz boosts with respect to the Cosmic Microwave Background frame which make the Hubble flow look most uniform around a particular observer. We use a very large N-Body simulation to extract the dependence of the boost velocities on the local environment such as underdensities, overdensities, and bulk flows. We find that the observation is not unexpected if we are located in an underdensity, which is indeed the case for our position in the universe. The amplitude of the measured boost velocity for our location is consistent with the expectation in the standard cosmology.
Designing divertor targets for uniform power load
Dekeyser, W.; Reiter, D.; Baelmans, M.
2015-08-01
Divertor design for next step fusion reactors heavily relies on 2D edge plasma modeling with codes as e.g. B2-EIRENE. While these codes are typically used in a design-by-analysis approach, in previous work we have shown that divertor design can alternatively be posed as a mathematical optimization problem, and solved very efficiently using adjoint methods adapted from computational aerodynamics. This approach has been applied successfully to divertor target shape design for more uniform power load. In this paper, the concept is further extended to include all contributions to the target power load, with particular focus on radiation. In a simplified test problem, we show the potential benefits of fully including the radiation load in the design cycle as compared to only assessing this load in a post-processing step.
Enhanced coherent Raman emission from uniform plasmas
International Nuclear Information System (INIS)
A mechanism for the coherent emission of radio and microwaves from a warm uniform plasma is proposed. The output power from this mechanism appears to have the characteristics of a classical parametric amplification process. An earlier kinetic theory model for radiation by the scattering of plasma waves in a homogeneous plasma is revamped and modified to incorporate the dominant role of longitudinal Rayleigh scattered waves which stimulate the emission of transverse combination radiation (sum and difference of impressed and natural frequencies) by the resonant Raman scattering process in the plasma. This results in intense radio or microwave radiation at approximately twice the plasma frequency, the intensity depending upon plasma parameters. This intensity, its angular pattern, and the threshold condition for its enhanced emission are calculated. Comparisons of the computed results with the laboratory observation of the radiation output from dc discharges in argon gas, and from a helium theta-pinch plasma are made. Both qualitative and quantitative agreement are found
Non-Uniformity and Generalised Sacks Splitting
Institute of Scientific and Technical Information of China (English)
COOPER S.Barry; LI Ang Sheng
2002-01-01
We show that there do not exist computable functions f1(e, i), f2 (e, i), g1(e, i), g2(e, i) such that for all e, i ∈ω,(1) (Wf1(e,i) - Wf2(e,i)) ≤T (We - Wi);(2) (Wg1(e,i) - Wg2(e,i))≤T (We - Wi);(3) (We - Wi) ≤T (Wf1(e,i) - Wf2(e,i)) (Wg1(e,i) - Wg2(e,i));(4) (We - Wi) T (Wf1(e,i) - Wf2(e,i)) unless (We - Wi) ≤T ; and (5) (We - Wi) T (Wg1(e,i) - Wg2(e,i)) unless (We - Wi) ≤T .It follows that the splitting theorems of Sacks and Cooper cannot be combined uniformly.
Reflector Design Method for Rotational Uniform Illuminance System with LED
Institute of Scientific and Technical Information of China (English)
ZHANG Qi-hui; WANG Hong; JI Ling-ling
2009-01-01
Based on nonimaging design method,uniform illuminance systems with LED source were developed to create a uniform illuminated circular region with a desired size in a screen at a prescribed place.By using ray-tracing software based on Monte-Carlo method,the simulation results show that in the illuminated region the luminous uniformity is higher than 90%.
Beyond Fashion Patrol: School Uniforms in the Middle Grades.
Kommer, David
1999-01-01
Discusses the benefits of school uniforms in fulfilling the educational objectives of middle school reform. Considers the role of uniforms in establishing student affiliation with the school and in adolescent development. Describes the development of a uniform program and notes issues of cost and legality. (JPB)
Dynamic thermoelectricity in uniform bipolar semiconductor
Volovichev, I. N.
2016-07-01
The theory of the dynamic thermoelectric effect has been developed. The effect lies in an electric current flowing in a closed circuit that consists of a uniform bipolar semiconductor, in which a non-uniform temperature distribution in the form of the traveling wave is created. The calculations are performed for the one-dimensional model in the quasi-neutrality approximation. It was shown that the direct thermoelectric current prevails, despite the periodicity of the thermal excitation, the circuit homogeneity and the lack of rectifier properties of the semiconductor system. Several physical reasons underlining the dynamic thermoelectric effect are found. One of them is similar to the Dember photoelectric effect, its contribution to the current flowing is determined by the difference in the electron and hole mobilities, and is completely independent of the carrier Seebeck coefficients. The dependence of the thermoelectric short circuit current magnitude on the semiconductor parameters, as well as on the temperature wave amplitude, length and velocity is studied. It is shown that the magnitude of the thermoelectric current is proportional to the square of the temperature wave amplitude. The dependence of the thermoelectric short circuit current on the temperature wave length and velocity is the nonmonotonic function. The optimum values for the temperature wave length and velocity, at which the dynamic thermoelectric effect is the greatest, have been deduced. It is found that the thermoelectric short circuit current changes its direction with decreasing the temperature wave length under certain conditions. The prospects for the possible applications of the dynamic thermoelectric effect are also discussed.
Uniformity Tests in Circular Data: Review
Directory of Open Access Journals (Sweden)
Ismet DOGAN
2015-10-01
Full Text Available Circular data are a large class of directional data, which are interest in many fields. Examples include phenomena that are periodic in time, including those dependent on hours of the day (hospital visits, times of birth, etc. or days of the year (unemployment or sales variations. The elementary but also fundamental property of circular data is that the beginning and end of the scale coincide: for example, 0° = 360°. An immediate implication is that the arithmetic mean is likely to be a poor summary: the mean of 1° and 359° cannot sensibly be 180°. The solution is use the vector mean direction as circular mean. The statistical analysis of angular or circular data differs from the analysis of linear data. Unlike linear distributions, which are often two-tailed and infinite, circular distributions exhibit finite closure because a circular data set comes back on itself, and therefore, 0° and 360° are actually the same point on a circle. Circular statistics is concerned mainly with observations which are unit vectors in the plane. Thus the sample space is typically a circle or a sphere, so that standart methods for analysing univariate or multivariate measurement data can?t be used. Special circular methods are required take into account the structure of these sample spaces. In most circular statistical analyses, the null hypothesis is a uniform distribution in which all directions occur with equal probability. In this study, eight different testing methods improved for uniformity in angular data have been introduced and these methods were compared with each other by using the information obtained from the literature.
Viadero, Debra
2005-01-01
This article reports on the effectiveness of school uniform policies. At Stephen Decatur Middle School, it is the school's policy that all students wear the standard school attire consisting of khaki pants with polo shirts in white, burgundy, or navy blue. Some of the shirts also sport an embroidered Decatur eagle, an optional embellishment.…
Politicas de uniformes y codigos de vestuario (Uniforms and Dress-Code Policies). ERIC Digest.
Lumsden, Linda
This digest in Spanish examines schools' dress-code policies and discusses the legal considerations and research findings about the effects of such changes. Most revisions to dress codes involve the use of uniforms, typically as a way to curb school violence and create a positive learning environment. A recent survey of secondary school principals…
Wu, C.; de Jong, J. R.; van Andel, H. A. Gratama; van der Have, F.; Vastenhouw, B.; Laverman, P.; Boerman, O. C.; Dierckx, R. A. J. O.; Beekman, F. J.
2011-01-01
Attenuation of photon flux on trajectories between the source and pinhole apertures affects the quantitative accuracy of reconstructed single-photon emission computed tomography (SPECT) images. We propose a Chang-based non-uniform attenuation correction (NUA-CT) for small-animal SPECT/CT with focusi
Wu, C.; Jong, J.R. de; Gratama van Andel, H.A.; Have, F. van der; Vastenhouw, B.; Laverman, P.; Boerman, O.C.; Dierckx, R.A.; Beekman, F.J.
2011-01-01
Attenuation of photon flux on trajectories between the source and pinhole apertures affects the quantitative accuracy of reconstructed single-photon emission computed tomography (SPECT) images. We propose a Chang-based non-uniform attenuation correction (NUA-CT) for small-animal SPECT/CT with focusi
Uniform trapped fields produced by stacks of HTS coated conductor tape
Mitchell-Williams, T. B.; Baskys, A.; Hopkins, S. C.; Kalitka, V.; Molodyk, A.; Glowacki, B. A.; Patel, A.
2016-08-01
The trapped magnetic field profile of stacks of GdBa2Cu3O7‑x superconducting tape was investigated. Angled stacks of superconducting tape were magnetized and found to produce very uniform trapped field profiles. The angled stacks were made of 12 mm × 24 mm solder coated tape pieces and were bonded together following a brief consolidation heat treatment. Layering multiple stacks together and adding a ferromagnetic plate beneath the samples were both found to enhance the magnitude and uniformity of the trapped field profiles. Stationary and time-dependent critical state finite element models were also developed to complement the experimental results and investigate the magnetization process. The size and shapes possible with the angled stacks make them attractive for applications requiring uniform magnetic fields over larger areas than can be achieved with existing bulk rings or tape annuli.
Large-area, uniform white light LED source on a flexible substrate.
Sher, Chin-Wei; Chen, Kuo-Ju; Lin, Chien-Chung; Han, Hau-Vei; Lin, Huang-Yu; Tu, Zong-Yi; Tu, Hsien-Hao; Honjo, Keiji; Jiang, Hsin-Yi; Ou, Sin-Liang; Horng, Ray-Hua; Li, Xiuling; Fu, Chien-Chung; Kuo, Hao-Chung
2015-09-21
This study demonstrates the flexible white LED structure with high lumen efficiency and uniform optical performance for neutral white and warm white CCT. Flip-chip LEDs were attached on a polyimide substrate with copper strips as electrical and thermal conduction paths. Yellow phosphors are mixed with polydimenthysiloxane (PDMS) to provide mechanical support and flexibility. The light efficiency of this device can reach 120 lm/W and 85% of light output uniformity of the emission area can be achieved. Moreover, the optical simulation is employed to evaluate various designs of this flexible film in order to obtain uniform output. Both the pitch between the individual devices and the thickness of the phosphor film are calculated for optimization purpose. This flexible white LED with high lumen efficiency and good reliability is suitable for the large area fixture in the general lighting applications. PMID:26406747
Coupled-modetheory for magneto-optical fiber Bragg grating under non-uniform magnetic field
Institute of Scientific and Technical Information of China (English)
LIU Fen; WU Bao-jian; LU Xin
2011-01-01
According to the perturbation theory,the coupled-mode equations for guided optical waves in the magneto-optical fiber Bragg gratings(MFBGs) under non-uniform magnetic field are derived.The equivalent relation between the magneticallyinduced non-uniform fiber Bragg grating(MnFBG) and the corresponding non-magnetic chirped grating is expressed and verified by the piecewise-uniform MFBG model under linear magnetic field.On the basis of the equivalent relation,the MnFBGs can be effectively investigated by means of simulations.The characteristics of the MnFBGs under three typical magnetic field distributions with application to optical pulse compression are simulated,and the minimal pulse width can be achieved for the same magneto-optical coupling parameter of 2.2 × 103 m-1.
International Nuclear Information System (INIS)
Australia is a federation of nine jurisdictions, each with independent radiation protection legislation. The existing legislative non-uniformity across the jurisdictions has constituted an impediment for operators who must comply with differing legislative requirements in different jurisdictions. To address this issue, a National Competition Policy Review of Radiation Protection Legislation took place in 2000/2001. It has produced 19 Recommendations, which addressed objectives of the legislation, the need to regulate, alternative regulatory approaches, national uniformity, licensing and registration, strict and prescriptive standards, advertising and promotional activities, compliance costs and cost recovery issues. The Review has recommended that jurisdictions should retain the regulatory approach to achieve radiation protection objectives rather than leave them to be decided by market forces. But the approach should be performance-based, i.e. outcome-focused rather than prescriptive. An Implementation Plan of the Recommendations has been created which, by the end of 2004, will produce the National Directory for Radiation Protection. The Directory, which will become a consolidated repository of radiation protection standards, guidelines, codes of practice and administrative principles will provide a uniform national framework for radiation protection legislation in Australia. It will provide guidance for the jurisdictions redrawing their legislations. Because of its central role in shaping future legislation, the Directory will contain only those provisions, which have passed a formal process (process for issue resolution) concluded by an approval by the Australian Health Ministers Conference. Such process will also expedite the uniform adoption nationwide of legislative trends emerging from international radiation protection recommendations and standards. This Australian model might be a viable example for other multi-jurisdictional countries to consider
Energy Technology Data Exchange (ETDEWEB)
NONE
2000-03-01
A silicon standard substance using boron as an impurity whose quantity has been controlled was prepared as a standard substance for secondary ion-mass spectrography (SIMS), and given an evaluation test. Boron used for addition was prepared in three levels in the concentration range from 10{sup 16} atoms/cm{sup 3} to 10{sup 18} atoms/cm{sup 3}. On both of epitaxial silicon and bulk silicon crystals, the concentration variation in the added boron was suppressed to {+-} 5% or less of the targeted value in the area of wafer center {+-} 30 mm, and verified of the uniformity satisfying the specifications as the standard substance. Standard methods were established on the concentration measurement by using the SIMS and the concentration calibration on boron added uniformly into silicon. Concentrations were determined with variance of about {+-} 10% on boron with medium concentration (10{sup 17} atoms/cm{sup 3}) and high concentration (10{sup 18} atoms/cm{sup 3}) through a round-robin test. Thus, it was made possible to provide boron to the standard substance, and the target for sample preparation was achieved. The silicon standard substance requested by ISO14237 can now be provided, opening the way for registration in the future in Japan as the certified standard substance. (NEDO)
School Size as a Factor in Elementary School Achievement.
Alspaugh, John W.; Gao, Rui
The relationship between elementary school enrollment and fifth-grade achievement was explored using data from a large urban Missouri school district. The district's 39 elementary schools received uniform allocations of resources from the district and used the same instructional materials but varied considerably in K-5 enrollment, socioeconomic…
Uniformity pattern and related criteria for two-level factorials
Institute of Scientific and Technical Information of China (English)
FANG; Kaitai; QIN; Hong
2005-01-01
In this paper,the study of projection properties of two-level factorials in view of geometry is reported.The concept of uniformity pattern is defined.Based on this new concept,criteria of uniformity resolution and minimum projection uniformity are proposed for comparing two-level factorials.Relationship between minimum projection uniformity and other criteria such as minimum aberration,generalized minimum aberration and orthogonality is made explict.This close relationship raises the hope of improving the connection between uniform design theory and factorial design theory.Our results provide a justification of orthogonality,minimum aberration,and generalized minimum aberration from a natural geometrical interpretation.
Explorations in achievement motivation
Helmreich, Robert L.
1982-01-01
Recent research on the nature of achievement motivation is reviewed. A three-factor model of intrinsic motives is presented and related to various criteria of performance, job satisfaction and leisure activities. The relationships between intrinsic and extrinsic motives are discussed. Needed areas for future research are described.
Intelligence and Educational Achievement
Deary, Ian J.; Strand, Steve; Smith, Pauline; Fernandes, Cres
2007-01-01
This 5-year prospective longitudinal study of 70,000+ English children examined the association between psychometric intelligence at age 11 years and educational achievement in national examinations in 25 academic subjects at age 16. The correlation between a latent intelligence trait (Spearman's "g"from CAT2E) and a latent trait of educational…
Setting and Achieving Objectives.
Knoop, Robert
1986-01-01
Provides basic guidelines which school officials and school boards may find helpful in negotiating, establishing, and managing objectives. Discusses characteristics of good objectives, specific and directional objectives, multiple objectives, participation in setting objectives, feedback on goal process and achievement, and managing a school…
Compression gain of spin wave signals in a magnonic YIG waveguide with thermal non-uniformity
Kolokoltsev, O.; Gómez-Arista, Ivan; Qureshi, N.; Acevedo, A.; Ordóñez-Romero, César L.; Grishin, A.
2015-03-01
We report on the observation of the compression gain of the signals carried by surface spin waves (MSSWs) in yittrium iron garnet films as a result of non-uniform optical heating of the spin wave medium. Efficient gain takes place if a frequency downshift of the spin wave spectrum induced by the heating is compensated by the corresponding non-uniformity of the bias magnetic field. It is proposed that the effect can be understood in part as an interaction between spin waves and a thermally induced potential well in the sample.
Directory of Open Access Journals (Sweden)
Leonhard eLücken
2013-05-01
Full Text Available Several brain diseases are characterized by abnormalneuronal synchronization. Desynchronization of abnormal neural synchronyis theoretically compelling because of the complex dynamical mechanismsinvolved. We here present a novel type of coordinated reset (CR stimulation.CR means to deliver phase resetting stimuli at different neuronalsub-populations sequentially, i.e. at times equidistantly distributedin a stimulation cycle. This uniform timing pattern seems to be intuitiveand actually applies to the neural network models used for the studyof CR so far. CR resets the population to an unstable cluster statefrom where it passes through a desynchronized transient, eventuallyresynchronizing if left unperturbed. In contrast, we show that theoptimal stimulation times are nonuniform. Using the model of weaklypulse-coupled neurons with phase response curves, we provide an approachthat enables to determine optimal stimulation timing patterns thatsubstantially maximize the desynchronized transient time followingthe application of CR stimulation. This approach includes an optimizationsearch for clusters in a low-dimensional pulse coupled map. As a consequence,model-specific non-uniformly spaced cluster states cause considerablylonger desynchronization transients. Intriguingly, such a desynchronizationboost with non-uniform CR stimulation can already be achieved by onlyslight modifications of the uniform CR timing pattern. Our resultssuggest that the non-uniformness of the stimulation times can be amedically valuable parameter in the calibration procedure for CR stimulation,where the latter has successfully been used in clinical and pre-clinicalstudies for the treatment of Parkinson's disease and tinnitus.
1/12-Scale scoping experiments to characterize double-shell tank slurry uniformity: Test plan
International Nuclear Information System (INIS)
Million gallon double-shell tanks (DSTs) at Hanford are used to store transuranic, high-level, and low-level wastes. These wastes generally consist of a large volume of salt-laden solution covering a smaller volume of settled sludge primarily containing metal hydroxides. These wastes will be retrieved and processed into immobile waste forms suitable for permanent disposal. The current retrieval concept is to use submerged dual-nozzle pumps to mobilize the settled solids by creating jets of fluid that are directed at the tank solids. The pumps oscillate, creating arcs of high-velocity fluid jets that sweep the floor of the tank. After the solids are mobilized, the pumps will continue to operate at a reduced flow rate sufficient to maintain the particles in a uniform suspension. The objectives of these 1/12-scale scoping experiments are to determine how Reynolds number, Froude number, and gravitational settling parameter affect the degree of uniformity achieved during jet mixer pump operation in the full-scale double-shell tanks; develop linear models to predict the degree of uniformity achieved by jet mixer pumps operating in the full-scale double-shell tanks; apply linear models to predict the degree of uniformity that will be achieved in tank 241-AZ-101 and determine whether contents of that tank will be uniform to within ± 10% of the mean concentration; and obtain experimental concentration and jet velocity data to compared with the TEMPEST computational and modeling predictions to guide further code development
Achievement and Social Ascription: A Comparison of Public and Private High Schools.
Bickel, Robert
1986-01-01
Public and private schooling have a roughly uniform effect on achievement, but variability among students' home and neighborhood environments mask the leveling effect. Includes an historical discussion of egalitarianism and stratification in American education. (PS)
Superhydrophobic Behavior on Nano-structured Surfaces
Schaeffer, Daniel
2008-05-01
Superhydrophobic behavior is observed in natural occurrences and has been thoroughly studied over the past few years. Water repellant properties on uniform arrays of vertically aligned nano-cones were investigated to determine the highest achievable contact angle (a measure of water drop repellency), which is measured from the reference plane on which the water drop sits to the tangent line of the point at which the drop makes contact with the reference plane. At low aspect ratios (height vs. width of the nano-cones), surface tension pulls the water into the nano-cone array, resulting in a wetted surface. Higher aspect ratios reverse the effect of the surface tension, resulting in a larger contact angle that causes water drops to roll off the surface. Fiber drawing, bundling, and redrawing are used to produce the structured array glass composite surface. Triple-drawn fibers are fused together, annealed, and sliced into thin wafers. The surface of the composite glass is etched to form nano-cones through a differential etching process and then coated with a fluorinated self-assembled monolayer (SAM). Cone aspect ratios can be varied through changes in the chemistry and concentration of the etching acid solution. Superhydrophobic behavior occurs at contact angles >150 and it is predicted and measured that optimal behavior is achieved when the aspect ratio is 4:1, which displays contact angles >=175 .
Directory of Open Access Journals (Sweden)
Ashwini M. Deshpande
2014-02-01
Full Text Available Considering the sparseness property of images, a sparse representation based iterative deblurring method is presented for single image deblurring under uniform and non-uniform motion blur. The approach taken is based on sparse and redundant representations over adaptively training dictionaries from single blurred-noisy image itself. Further, the K-SVD algorithm is used to obtain a dictionary that describes the image contents effectively. Comprehensive experimental evaluation demonstrate that the proposed framework integrating the sparseness property of images, adaptive dictionary training and iterative deblurring scheme together significantly improves the deblurring performance and is comparable with the state-of-the art deblurring algorithms and seeks a powerful solution to an ill-conditioned inverse problem.
The Uniformization of Certain Algebraic Hypergeometric Functions
Maier, Robert S
2009-01-01
The hypergeometric functions ${}_nF_{n-1}$ are higher transcendental functions, but for certain parameter values they become algebraic. This occurs, e.g., if the defining hypergeometric differential equation has irreducible but imprimitive monodromy. It is shown that many algebraic ${}_nF_{n-1}$'s of this type can be represented as combinations of certain explicitly algebraic functions of a single variable, i.e., the roots of trinomial equations. This generalizes a result of Birkeland. Any tuple of roots of a trinomial equation traces out a projective algebraic curve, and it is determined when this curve is of genus zero, i.e., admits a rational parametrization. Any such parametrization yields a hypergeometric identity that explicitly uniformizes a family of algebraic ${}_nF_{n-1}$'s. Even if the governing curve is of positive genus, it is shown how it may be possible to construct single-valued or multivalued parametrizations of individual algebraic ${}_nF_{n-1}$'s, by computation in rings of symmetric polyno...
Producing Uniform Lesion Pattern in HIFU Ablation
Zhou, Yufeng; Kargl, Steven G.; Hwang, Joo Ha
2009-04-01
High intensity focused ultrasound (HIFU) is emerging as a modality for treatment of solid tumors. The temperature at the focus can reach over 65° C denaturing cellular proteins resulting in coagulative necrosis. Typically, HIFU parameters are the same for each treated spot in most HIFU control systems. Because of thermal diffusion from nearby spots, the size of lesions will gradually become larger as the HIFU therapy progresses, which may cause insufficient treatment of initial spots, and over-treatment of later ones. It is found that the produced lesion pattern also depends on the scanning pathway. From the viewpoint of the physician creating uniform lesions and minimizing energy exposure are preferred in tumor ablation. An algorithm has been developed to adaptively determine the treatment parameters for every spot in a theoretical model in order to maintain similar lesion size throughout the HIFU therapy. In addition, the exposure energy needed using the traditional raster scanning is compared with those of two other scanning pathways, spiral scanning from the center to the outside and from the outside to the center. The theoretical prediction and proposed algorithm were further evaluated using transparent gel phantoms as a target. Digital images of the lesions were obtained, quantified, and then compared with each other. Altogether, dynamically changing treatment parameters can improve the efficacy and safety of HIFU ablation.
Measures and metrics in uniform gravitational fields
Alberici, M
2005-01-01
A partially alternative derivation of the expression for the time dilation effect in a uniform static gravitational field is obtained by means of a thought experiment in which rates of clocks at rest at different heights are compared using as reference a clock bound to a free falling reference system (FFRS). Derivations along these lines have already been proposed, but generally introducing some shortcut in order to make the presentation elementary. The treatment is here exact: the clocks whose rates one wishes to compare are let to describe their world lines (Rindler's hyperbolae) with respect to the FFRS, and the result is obtained by comparing their lengths in space-time. The exercise may nonetheless prove pedagogically instructive insofar as it shows that the some results of General Relativity (GR) can be obtained in terms of physical and geometrical reasoning without having recourse to the general formalism. The corresponding GR metric is derived, to the purpose of making a comparison to the solutions of...
Uniformly Accelerated Mirrors; 1, Mean Fluxes
Obadia, N
2003-01-01
The Davies-Fulling model describes the scattering of a massless field by a moving mirror in 1+1 dimensions. When the mirror travels under uniform acceleration, one encounters severe problems which are due to the infinite blue shift effects associated with the horizons. On one hand, the Bogoliubov coefficients are ill-defined and the total energy emitted diverges. On the other hand, the instantaneous mean flux vanishes. To obtained well-defined expressions we introduce an alternative model based on an action principle. The usefulness of this model is to allow to switch on and off the interaction at asymptotically large times. By an appropriate choice of the switching function, we obtain analytical expressions for the scattering amplitudes and the fluxes emitted by the mirror. When the coupling is constant, we recover the vanishing flux. However it is now followed by transients which inevitably become singular when the switching off is performed at late time. Our analysis reveals that the scattering amplitudes ...
Structurally uniform and atomically precise carbon nanostructures
Segawa, Yasutomo; Ito, Hideto; Itami, Kenichiro
2016-01-01
Nanometre-sized carbon materials consisting of benzene units oriented in unique geometric patterns, hereafter named nanocarbons, conduct electricity, absorb and emit light, and exhibit interesting magnetic properties. Spherical fullerene C60, cylindrical carbon nanotubes and sheet-like graphene are representative forms of nanocarbons, and theoretical simulations have predicted several exotic 3D nanocarbon structures. At present, synthetic routes to nanocarbons mainly lead to mixtures of molecules with a range of different structures and properties, which cannot be easily separated or refined into pure forms. Some researchers believe that it is impossible to synthesize these materials in a precise manner. Obtaining ‘pure’ nanocarbons is a great challenge in the field of nanocarbon science, and the construction of structurally uniform nanocarbons, ideally as single molecules, is crucial for the development of functional materials in nanotechnology, electronics, optics and biomedical applications. This Review highlights the organic chemistry approach — more specifically, bottom-up construction with atomic precision — that is currently the most promising strategy towards this end.
Uniform Page Migration Problem in Euclidean Space
Directory of Open Access Journals (Sweden)
Amanj Khorramian
2016-08-01
Full Text Available The page migration problem in Euclidean space is revisited. In this problem, online requests occur at any location to access a single page located at a server. Every request must be served, and the server has the choice to migrate from its current location to a new location in space. Each service costs the Euclidean distance between the server and request. A migration costs the distance between the former and the new server location, multiplied by the page size. We study the problem in the uniform model, in which the page has size D = 1 . All request locations are not known in advance; however, they are sequentially presented in an online fashion. We design a 2.75 -competitive online algorithm that improves the current best upper bound for the problem with the unit page size. We also provide a lower bound of 2.732 for our algorithm. It was already known that 2.5 is a lower bound for this problem.
Uniform distribution of TiCp in TiCp/Zn-Al composites prepared by XDTM
Institute of Scientific and Technical Information of China (English)
王香; 马旭梁; 李庆芬; 曾松岩
2002-01-01
The prefabricated Al/TiC alloy with high TiC particle content was prepared by XDTM process. The uniform distribution process of TiC particles in the stationary zinc melt was studied and analyzed using self-made experimental equipment, and the model of the uniform distribution process was built. The results show that zinc diffuses into the prepared Al/TiC alloy after it is placed in the zinc melt at temperatures below the melting point of aluminum, which leads to the decrease of the liquidus temperature of Al-Zn alloy in the surface layer of Al/TiC alloy. When the liquidus temperature of Al-Zn alloy is equal to or below the temperature of zinc melt, Al-Zn alloy melts and TiC particles drop with it from the Al/TiC alloy and then transfer into the zinc melt and finally distribute uniformly in it.
An integral formulation for wave propagation on weakly non-uniform potential flows
Mancini, Simone; Sinayoko, Samuel; Gabard, Gwenael; Tournour, Michel
2015-01-01
An integral formulation for acoustic radiation in moving flows is presented. It is based on a potential formulation for acoustic radiation on weakly non-uniform subsonic mean flows. This work is motivated by the absence of suitable kernels for wave propagation on non-uniform flow. The integral solution is formulated using a Green's function obtained by combining the Taylor and Lorentz transformations. Although most conventional approaches based on either transform solve the Helmholtz problem in a transformed domain, the current Green's function and associated integral equation are derived in the physical space. A dimensional error analysis is developed to identify the limitations of the current formulation. Numerical applications are performed to assess the accuracy of the integral solution. It is tested as a means of extrapolating a numerical solution available on the outer boundary of a domain to the far field, and as a means of solving scattering problems by rigid surfaces in non-uniform flows. The results...
Achieveing Organizational Excellence Through
Directory of Open Access Journals (Sweden)
Mehdi Abzari
2009-04-01
Full Text Available AbstractToday, In order to create motivation and desirable behavior in employees, to obtain organizational goals,to increase human resources productivity and finally to achieve organizational excellence, top managers oforganizations apply new and effective strategies. One of these strategies to achieve organizational excellenceis creating desirable corporate culture. This research has been conducted to identify the path to reachorganizational excellence by creating corporate culture according to the standards and criteria oforganizational excellence. The result of the so-called research is this paper in which researchers foundtwenty models and components of corporate culture and based on the Industry, organizational goals andEFQM model developed a model called "The Eskimo model of Culture-Excellence". The method of theresearch is survey and field study and the questionnaires were distributed among 116 managers andemployees. To assess the reliability of questionnaires, Cronbach alpha was measured to be 95% in the idealsituation and 0/97 in the current situation. Systematic sampling was done and in the pre-test stage 45questionnaires were distributed. A comparison between the current and the ideal corporate culture based onthe views of managers and employees was done and finally it has been concluded that corporate culture isthe main factor to facilitate corporate excellence and success in order to achieve organizational effectiveness.The contribution of this paper is that it proposes a localized –applicable model of corporate excellencethrough reinforcing corporate culture.
Achieving Small World Properties using Bio-Inspired Techniques in Wireless Networks
Agarwal, Rachit; Gauthier, Vincent; Becker, Monique; Yeo, Chai Kiat; Lee, Bu Sung
2011-01-01
Self-Organization properties of the nodes play an important role in an autonomous wireless sensor environment in achieving network wide characteristics. Self-Organization can be used to achieve small world characteristics in a network. In real networks, however, where there is non-uniform distribution of nodes and overall connectivity of the network is less, achieving small world properties while increasing connectivity must be studied. We believe that network connectivity can be increased and small world properties can be achieved with the help of beamforming, biologically inspired algorithms and using local information. Most of the researches performed in direction of achieving above mentioned goals in wireless networks assume knowledge of network with either heterogeneous or hybrid uniform deployment. We propose that without the knowledge of the global environment or introduction of any special features in the network, we can achieve our goal with the help of inspirations from the nature in a non-uniform n...
Zhang, Lianbin
2015-01-01
The preparation of biomimetic superhydrophobic surfaces with hydrophilic micro-sized patterns is highly desirable, but a one-step, mask-free method to produce such surfaces has not previously been reported. We have developed a direct method to produce superhydrophilic micropatterns on superhydrophobic surfaces based on inkjet printing technology. This work was inspired by the efficient fog-harvesting behavior of Stenocara beetles in the Namib Desert. A mussel-inspired ink consisting of an optimized solution of dopamine was applied directly by inkjet printing to superhydrophobic surfaces. Stable Wenzel\\'s microdroplets of the dopamine solution with well-defined micropatterns were obtained on these surfaces. Superhydrophilic micropatterns with well-controlled dimensions were then readily achieved on the superhydrophobic surfaces by the formation of polydopamine via in situ polymerization. The micropatterned superhydrophobic surfaces prepared by this inkjet printing method showed enhanced water collection efficiency compared with uniform superhydrophilic and superhydrophobic surfaces. This method can be used for the facile large-scale patterning of superhydrophobic surfaces with high precision and superior pattern stability and is therefore a key step toward patterning superhydrophobic surfaces for practical applications. This journal is
Alexander Röder; Elena García-Gareta; Christina Theodoropoulos; Nikola Ristovski; Keith A. Blackwood; Woodruff, Maria A.
2015-01-01
The use of biopolymers as a three dimensional (3D) support structure for cell growth is a leading tissue engineering approach in regenerative medicine. Achieving consistent cell seeding and uniform cell distribution throughout 3D scaffold culture in vitro is an ongoing challenge. Traditionally, 3D scaffolds are cultured within tissue culture plates to enable reproducible cell seeding and ease of culture media change. In this study, we compared two different well-plates with different surface ...
Uniform Convergence Analysis for Singularly Perturbed Elliptic Problems with Parabolic Layers
Institute of Scientific and Technical Information of China (English)
Jichun Li; Yitung Chen
2008-01-01
In this paper, using Lin's integral identity technique, we prove the optimal uniform convergence O(Nx-2 ln2Nx+ Ny-2 In2Ny) in the L2-norm for singularly per-turbed problems with parabolic layers. The error estimate is achieved by bilinear fi-nite elements on a Shishkin type mesh. Here Nx and Ny are the number of elements in the x- and y-directions, respectively. Numerical results are provided supporting our theoretical analysis.
Spatially uniform enhancement of single quantum dot emission using plasmonic grating decoupler
Arunandan Kumar; Jean-Claude Weeber; Alexandre Bouhelier; Fabien Eloi; Stéphanie Buil; Xavier Quélin; Michel Nasilowski; Benoit Dubertret; Jean-Pierre Hermier; Gérard Colas des Francs
2015-01-01
We demonstrate a spatially uniform enhancement of individual quantum dot (QD) fluorescence emission using plasmonic grating decouplers on thin gold or silver films. Individual QDs are deposited within the grating in a controlled way to investigate the position dependency on both the radiation pattern and emission enhancement. We also describe the optimization of the grating decoupler. We achieve a fluorescence enhancement ~3 times higher than using flat plasmon film, for any QD position in th...
Spatially uniform enhancement of single quantum dot emission using plasmonic grating decoupler
Kumar, Arunandan; Weeber, Jean-Claude; Bouhelier, Alexandre; Eloi, Fabien; Buil, Stéphanie; Quélin, Xavier; Nasilowski, Michel; Dubertret, Benoit; Hermier, Jean-Pierre; Colas Des Francs, Gérard
2015-11-01
We demonstrate a spatially uniform enhancement of individual quantum dot (QD) fluorescence emission using plasmonic grating decouplers on thin gold or silver films. Individual QDs are deposited within the grating in a controlled way to investigate the position dependency on both the radiation pattern and emission enhancement. We also describe the optimization of the grating decoupler. We achieve a fluorescence enhancement ~3 times higher than using flat plasmon film, for any QD position in the grating.
International Nuclear Information System (INIS)
In this study, TiO2 nanotube arrays (TiO2-NTs) with various intertube spaces were fabricated in the electrolyte with different water contents and the CdS nanoparticles (CdS NPs) were further deposited onto the TiO2-NTs as a sensitizer via a sequential chemical bath deposition (S-CBD) method. The FE-SEM, TEM, XRD and XPS results demonstrated that the CdS NPs were uniformly deposited onto the surface of TiO2-NTs. It was found that higher water content in electrolyte was in favor of large intertube space and pore size and the uniform deposition of CdS NPs. The photocatalytic degradation of methyl orange was tested with the as-prepared CdS/TiO2-NTs under visible light (λ>400 nm). It was found that the photodegradation rate reached as high as 96.7% under visible irradiation for 180 min. In addition, a reasonable degradation rate of 75.8% was achieved even after 5 cycles, suggesting a good photocatalytic stability of the as-prepared CdS/TiO2-NTs. - Graphical abstract: The whole sheet of CdS NPs sensitized TiO2-NTs with the Ti subtract was used for degradation of methyl orange under visible light (λ>400 nm) on a XPA-7 photochemical reactor. - Highlights: • Intertube space, pore size were controlled by changing water content in electrolyte. • CdS nanoparticles were uniformly deposited onto the surface of TiO2 nanotubes. • The catalyst with Ti substrate used as a whole was very convenient for recycling. • Visible-light photocatalytic activity and stability were highly enhanced
Das materialidades da escola: o uniforme escolar On the materialities of school: the school uniform
Directory of Open Access Journals (Sweden)
Ivanir Ribeiro
2012-09-01
Full Text Available Este texto dedica-se a situar o uniforme escolar como objeto histórico e como importante fonte do e no universo escolar. Para tanto, empreende-se uma revisão da literatura que aborda a temática e investe-se em uma reflexão que concebe esse artefato como uma das expressões da materialidade que dá contornos à forma escolar, tomando-o na perspectiva da cultura material. Alguns autores servem aqui de referência: Richard Bucaille, Jean-Marie Pesez e Ulpiano Bezerra de Meneses, nos estudos em que se dedicam à cultura material; Agustín Benito Escolano e Rosa Fátima de Souza, nos trabalhos em que voltam o olhar para cultura material escolar; Inês Dussel e Katiene Nogueira da Silva, autoras que abordam diretamente a questão dos uniformes escolares. Não menos importantes para efeitos deste artigo são os trabalhos que tratam do movimento higienista, particularmente aqueles levados a cabo por José Gondra. Os dados levantados e as reflexões efetuadas indiciam dois movimentos (ou tensões nada desprezíveis. Por um lado, são evidentes as dificuldades encontradas para adoção dos uniformes escolares por todos os alunos, tanto por parte do Estado quanto por parte das famílias, devido ao fato de eles representarem um custo elevado, principalmente os calçados, artigos pouco utilizados pela maioria da população até, no mínimo, meados do século XX. Por outro lado, há indícios de que esse traje desempenhava uma função niveladora importante. Por meio dele, criava-se uma ideia de padronização e democratização do ensino, mesmo que em aparência, além de se dar visibilidade pública a uma instituição social cada vez mais importante: a escola.This text is devoted to situate the school uniform as a historical object, and as an important source on and in the school universe. For that, a literature survey is carried out on this theme, and a reflection is conducted envisaging this artifact as one of the expressions of materiality that
Spherical Accretion in a Uniformly Expanding Universe
Colpi, Monica; Shapiro, Stuart L.; Wasserman, Ira
1996-10-01
We consider spherically symmetric accretion of material from an initially homogeneous, uniformly expanding medium onto a Newtonian point mass M. The gas is assumed to evolve adiabatically with a constant adiabatic index F, which we vary over the range Γ ɛ [1, 5/3]. We use a one-dimensional Lagrangian code to follow the spherical infall of material as a function of time. Outflowing shells gravitationally bound to the point mass fall back, giving rise to a inflow rate that, after a rapid rise, declines as a power law in time. If there were no outflow initially, Bondi accretion would result, with a characteristic accretion time-scale ta,0. For gas initially expanding at a uniform rate, with a radial velocity U = R/t0 at radius R, the behavior of the flow at all subsequent times is determined by ta,0/t0. If ta,0/t0 ≫ 1, the gas has no time to respond to pressure forces, so the fluid motion is nearly collisionless. In this case, only loosely bound shells are influenced by pressure gradients and are pushed outward. The late-time evolution of the mass accretion rate Mdot is close to the result for pure dust, and we develop a semianalytic model that accurately accounts for the small effect of pressure gradients in this limit. In the opposite regime, ta,0/t0 ≪ 1, pressure forces significantly affect the motion of the gas. At sufficiently early times, t ≤ ttr, the flow evolved along a sequence of quasi-stationary, Bondi-like states, with a time-dependent Mdot determined by the slowly varying gas density at large distances. However, at later times, t ≥ ttr, the fluid flow enters a dustllke regime; ttr is the time when the instantaneous Bondi accretion radius reaches the marginally bound radius. The transition time ttr depends sensitively on ta,0/t0 for a given Γ and can greatly exceed t0. We show that there exists a critical value Γ = 11/9, below which the transition from fluid to ballistic motion disappears. As one application of our calculations, we consider the
Multi Product Inventory Optimization using Uniform Crossover Genetic Algorithm
Narmadha, S; Sathish, G
2010-01-01
Inventory management is considered to be an important field in Supply Chain Management because the cost of inventories in a supply chain accounts for about 30 percent of the value of the product. The service provided to the customer eventually gets enhanced once the efficient and effective management of inventory is carried out all through the supply chain. The precise estimation of optimal inventory is essential since shortage of inventory yields to lost sales, while excess of inventory may result in pointless storage costs. Thus the determination of the inventory to be held at various levels in a supply chain becomes inevitable so as to ensure minimal cost for the supply chain. The minimization of the total supply chain cost can only be achieved when optimization of the base stock level is carried out at each member of the supply chain. This paper deals with the problem of determination of base stock levels in a ten member serial supply chain with multiple products produced by factories using Uniform Crosso...
Gamma-ray burst jets: uniform or structured?
Salafia, O S; Nappo, F; Ghisellini, G; Ghirlanda, G; Salvaterra, R; Tagliaferri, G
2015-01-01
The structure of Gamma-Ray Burst (GRB) jets impacts on their prompt and afterglow emission properties. Insights into the still unknown structure of GRBs can be achieved by studying how different structures impact on the luminosity function (LF): i) we show that low ($10^{46} 10^{50}$ erg/s) luminosity GRBs can be described by a unique LF; ii) we find that a uniform jet (seen on- and off-axis) as well as a very steep structured jet (i.e. $\\epsilon(\\theta) \\propto \\theta^{-s}$ with $s > 4$) can reproduce the current LF data; iii) taking into account the emission from the whole jet (i.e. including contributions from mildly relativistic, off-axis jet elements) we find that $E_{\\rm iso}(\\theta_{\\rm v})$ (we dub this quantity "apparent structure") can be very different from the intrinsic structure $\\epsilon(\\theta)$: in particular, a jet with a Gaussian intrinsic structure has an apparent structure which is more similar to a power law. This opens a new viewpoint on the quasi-universal structured jet hypothesis.
Contourlet Filter Design Based on Chebyshev Best Uniform Approximation
Yang, Guoan; Fang, Xiaofeng; Jing, Mingli; Zhang, Songjun; Hou, Ming
2010-12-01
The contourlet transform can deal effectively with images which have directional information such as contour and texture. In contrast to wavelets for which there exists many good filters, the contourlet filter design for image processing applications is still an ongoing work. Therefore, this paper presents an approach for designing the contourlet filter based on the Chebyshev best uniform approximation for achieving an efficient image denoising applications using hidden Markov tree models in the contourlet domain. Here, we design both the optimal 9/7 wavelet filter banks with rational coefficients and new pkva 12 filter. In this paper, the Laplacian pyramid followed by the direction filter banks decomposition in the contourlet transform using the two filter banks above and the image denoising applications in the contourlet hidden Markov tree model are implemented, respectively. The experimental results show that the denoising performance of the test image Zelda in terms of peak signal-to-noise ratio is improved by 0.33 dB than using CDF 9/7 filter banks with irrational coefficients on the JPEG2000 standard and standard pkva 12 filter, and visual effects are as good as compared with the research results of Duncan D.-Y. Po and Minh N. Do.
Principle of uniformity of temperature difference field in heat exchanger
Institute of Scientific and Technical Information of China (English)
过增元; 李志信; 周森泉; 熊大曦
1996-01-01
A principle of uniformity of temperature difference field (TDF) in heat exchangers is advanced.It states that the more uniform the temperature difference field,the higher the effectiveness of heat exchanger for a given NTU and C,.Analytical and numerical results on the uniformity of TDF and effectiveness of thirteen types of heat exchangers show the validity of the uniformity principle.Its further verification is given by the asymptotical solution of TDF in terms of a recurrence formula of heat transfer area distribution.The analyses of entropy generation caused by heat transfer indicate that the uniformity principle is based on the second law of thermodynamics.Two ways,redistributing heat transfer areas and varying the connection between tubes,are presented for the improvement of the uniformity of TDF and the consequent increase of effectiveness for crossflow heat exchangers.
CONSTRUCTING UNIFORM DESIGNS WITH TWO- OR THREE-LEVEL
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
When the number of runs is large, to search for uniform designs in the sense of low-discrepancy is an NP hard problem. The number of runs of most of the available uniform designs is small (≤ 50). In this article, the authors employ a kind of the so-called Hamming distance method to construct uniform designs with two- or three-level such that some resulting uniform designs have a large number of runs. Several infinite classes for the existence of uniform designs with the same Hamming distances between any distinct rows are also obtained simultaneously. Two measures of uniformity, the centered L2-discrepancy (CD, for short) and wrap-around L2-discrepancy (WD, for short), are employed.
Motion Planning of Redundant Manipulators for Painting Uniform Thick Coating in Irregular Duct
Directory of Open Access Journals (Sweden)
Yan Chen
2016-01-01
Full Text Available The paper presents a motion planning method of redundant manipulator for painting uniform thick coating on the interior of irregular duct of some aircrafts. Discontinuous peripheral painting method is employed by analyzing the restrictions during painting the duct. For improving the longitudinal uniformity of thick coating, the interlacing painting method plans two sets of sweeping paths and an interlacing distance between the starting paths of the two times of painting. The interlacing distance and overlapping distance are optimized by establishing and analyzing the model of longitudinal uniformity. To enhance the transverse uniformity, sweeping speeds for curved surfaces are calculated by the ratio of transfer efficiency after the basic sweeping speed for the plane is determined. The intertwining method, minimizing the sum of the weighed distances between the duct centerline and key points of the manipulator links, is employed for the joint trajectory planning without collision. The simulation and experiment results show that the redundant manipulators can finish painting the internal surface of the irregular S-shaped duct without collision. The maximum relative deviation is 16.3% and the thicknesses of all measurement points satisfy the acceptance criteria of the factory.
14 CFR Section 19 - Uniform Classification of Operating Statistics
2010-01-01
... Statistics Section 19 Section 19 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION... AIR CARRIERS Operating Statistics Classifications Section 19 Uniform Classification of Operating Statistics...
The Influence of Non-Uniform High Heat Flux on Thermal Stress of Thermoelectric Power Generator
Directory of Open Access Journals (Sweden)
Tingzhen Ming
2015-11-01
Full Text Available A thermoelectric generator (TEG device which uses solar energy as heat source would achieve higher efficiency if there is a higher temperature difference between the hot-cold ends. However, higher temperature or higher heat flux being imposed upon the hot end will cause strong thermal stress, which will have a negative influence on the life cycle of the thermoelectric module. Meanwhile, in order to get high heat flux, a Fresnel lens is required to concentrate solar energy, which will cause non-uniformity of heat flux on the hot end of the TEG and further influence the thermal stress of the device. This phenomenon is very common in solar TEG devices but seldom research work has been reported. In this paper, numerical analysis on the heat transfer and thermal stress performance of a TEG module has been performed considering the variation on the power of the heat flux being imposed upon the hot-end; the influence of non-uniform high heat flux on thermal stress has also been analyzed. It is found that non-uniformity of high heat flux being imposed upon the hot end has a significant effect on the thermal stress of TEG and life expectation of the device. Taking the uniformity of 100% as standard, when the heating uniformity is 70%, 50%, 30%, and 10%, respectively, the maximum thermal stress of TEG module increased by 3%, 6%, 12%, and 22% respectively. If we increase the heat flux on the hot end, the influence of non-uniformity on the thermal stress will be more remarkable.
Uniform yeast cell assembly via microfluidics.
Chang, Ya-Wen; He, Peng; Marquez, Samantha M; Cheng, Zhengdong
2012-06-01
This paper reports the use of microfluidic approaches for the fabrication of yeastosomes (yeast-celloidosomes) based on self-assembly of yeast cells onto liquid-solid or liquid-gas interfaces. Precise control over fluidic flows in droplet- and bubble-forming microfluidic devices allows production of monodispersed, size-selected templates. The general strategy to organize and assemble living cells is to tune electrostatic attractions between the template (gel or gas core) and the cells via surface charging. Layer-by-Layer (LbL) polyelectrolyte deposition was employed to invert or enhance charges of solid surfaces. We demonstrated the ability to produce high-quality, monolayer-shelled yeastosome structures under proper conditions when sufficient electrostatic driving forces are present. The combination of microfluidic fabrication with cell self-assembly enables a versatile platform for designing synthetic hierarchy bio-structures. PMID:22655026
Slovick, Brian A.; Krenz, Peter M.; Zummo, Guy; Boreman, Glenn D.
2010-03-01
Infrared dipole-coupled bolometers receive radiation more efficiently when illuminated through a high permittivity, antireflection (AR) coated, hemispherical immersion lens. To maintain the enhanced responsivity for all illumination angles, the AR coating must be uniform over the hemispherical surface. An evaporation method for depositing a uniform AR coating on the hemispherical surface is presented. The lens is tilted relative to the source, which can be either electron-beam or thermal, and rotated throughout the deposition. Evaporation at an angle of 70° yields a uniform film with less than 10% thickness variation over a 120° full angle of the hemispherical surface. A theoretical model is developed and compared to profilometer measurements. In all cases, there is general agreement between theory and measurement. A single dipole is fabricated onto the flat surface of an AR-coated germanium immersion lens and the responsivity is measured for both substrate-side and air-side illumination. With a zinc sulfide (ZnS) single-layer AR coating, substrate-side illumination yields a broadside antenna response 49 ± 2.7 times greater than air-side illumination.
Rubber-induced uniform laser shock wave pressure for thin metal sheets microforming
Energy Technology Data Exchange (ETDEWEB)
Shen, Zongbao, E-mail: szb@ujs.edu.cn; Wang, Xiao; Liu, Huixia; Wang, Yayuan; Wang, Cuntang
2015-02-01
Highlights: • The rubber is introduced to smooth laser shock wave pressure. • The mechanism of rubber-induced smoothing effect is proposed. • Smoothing effect is mainly due to the radial expansion of plasma cloud on rubber. • The good surface quality can be obtained under rubber dynamic loading. - Abstract: Laser shock microforming of thin metal sheets is a new high velocity forming technique, which employs laser shock wave to deform the thin metal sheets. The spatial distribution of forming pressure is mainly dependent on the laser beam. A new type of laser shock loading method is introduced which gives a uniform pressure distribution. A low density rubber is inserted between the laser beam and the thin metal sheets. The mechanism of rubber-induced smoothing effect on confined laser shock wave is proposed. Plasticine is used to perform the smoothing effect experiments due to its excellent material flow ability. The influence of rubber on the uniformity of laser shock wave pressure is studied by measuring the surface micro topography of the deformed plasticine. And the four holes forming experiment is used to verify the rubber-induced uniform pressure on thin metal sheets surface. The research results show the possibility of smoothing laser shock wave pressure using rubber. And the good surface quality can be obtained under rubber dynamic loading.
Uniform estimates for cubic oscillatory integrals
Gressman, Philip T.
2007-01-01
This paper establishes the optimal decay rate for scalar oscillatory integrals in $n$ variables which satisfy a nondegeneracy condition on the third derivatives. The estimates proved are stable under small linear perturbations, as encountered when computing the Fourier transform of surface-carried measures. The main idea of the proof is to construct a nonisotropic family of balls which locally capture the scales and directions in which cancellation occurs.
An alternative time marker for the study of the uniform and uniformly accelerated movements
Directory of Open Access Journals (Sweden)
Osmar Henrique Moura da Silva
2003-01-01
Full Text Available This work presents a type of time marker set up with materials of low cost for the study of uniform movements as well as those accelerated by gravitacional force. A mechanism used to measure its frequency is coupled to it in order to find the approximate value of the acceleration of the local gravity. The experiment, that is adapted to be used during a kinematics class, can also be presented by the students at a science fair, for being a stimulating factor as it involves the students’ participation in its construction.
Das materialidades da escola: o uniforme escolar On the materialities of school: the school uniform
Ivanir Ribeiro; Vera Lucia Gaspar da Silva
2012-01-01
Este texto dedica-se a situar o uniforme escolar como objeto histórico e como importante fonte do e no universo escolar. Para tanto, empreende-se uma revisão da literatura que aborda a temática e investe-se em uma reflexão que concebe esse artefato como uma das expressões da materialidade que dá contornos à forma escolar, tomando-o na perspectiva da cultura material. Alguns autores servem aqui de referência: Richard Bucaille, Jean-Marie Pesez e Ulpiano Bezerra de Meneses, nos estudos em que s...
The ℓ-distribution method for modeling non-gray absorption in uniform and non-uniform gaseous media
André, Frédéric
2016-08-01
The ℓ-distribution modeling is proposed for radiative heat transfer in uniform and non-uniform non-gray gaseous media. The method is partly based on the application of results from the k-moment method. It combines this technique with several concepts from probability theory: the notion of rank transmutation maps allows extending the k-moment method to an infinite number of k-moments; copula models appear naturally to extend the method from uniform to non-uniform gas paths. The ℓ-distribution approach is shown to provide results: (1) more accurate - up to three orders of magnitude - than usual k-distribution approaches in uniform media, (2) as precise as correlated-k models in non-uniform situations. All these results are obtained at a computational cost lower than k-distribution models. Differences and similarities between k- and ℓ-distribution methods are discussed.
Achieving English Spoken Fluency
Institute of Scientific and Technical Information of China (English)
王鲜杰
2000-01-01
Language is first and foremost oral,spoken language,speaking skill is the most important one of the four skills(L,S,R,W)and also it is the most difficult one of the four skills. To have an all-round command of a language one must be able to speak and to understand the spoken language, it is not enough for a language learner only to have a good reading and writing skills. As Englisn language teachers, we need to focus on improving learners' English speaking skill to meet the need of our society and our country and provide learner some useful techniques to achieving their English spoken fluency. This paper focuses on the spoken how to improving learners speaking skill.
Achieving diagnosis by consensus
LENUS (Irish Health Repository)
Kane, Bridget
2009-08-01
This paper provides an analysis of the collaborative work conducted at a multidisciplinary medical team meeting, where a patient’s definitive diagnosis is agreed, by consensus. The features that distinguish this process of diagnostic work by consensus are examined in depth. The current use of technology to support this collaborative activity is described, and experienced deficiencies are identified. Emphasis is placed on the visual and perceptual difficulty for individual specialities in making interpretations, and on how, through collaboration in discussion, definitive diagnosis is actually achieved. The challenge for providing adequate support for the multidisciplinary team at their meeting is outlined, given the multifaceted nature of the setting, i.e. patient management, educational, organizational and social functions, that need to be satisfied.
Tan, Ming K.; Yeo, Leslie Y.; Friend, James R.
2010-12-01
We present an experimental approach for controlled switching between uniform flow for pumping and vortical flow for mixing in a microchannel fabricated onto a piezoelectric substrate. For particle laden fluids, this arrangement permits a choice between transport and alignment of microparticles. Using surface acoustic waves with amplitudes beyond 1 nm, the transition from uniform to mixing flows occurs when the acoustic wavelength in the fluid is reduced to a dimension smaller than the channel width, i.e., λf≥Wch for uniform flow and λfmixing flow. On the other hand, using relatively weak surface acoustic waves with amplitudes below 1 nm, particles in an initially homogeneous suspension agglomerate into equally spaced lines with a separation of λf/2. Switching the transducer between its fundamental resonant frequency f0 and its first harmonic frequency f1+˜2f0 causes a switch between uniform and mixing flow, while switching between large and small amplitude excitation allows one to choose whether to collect the particles in the flow along nodal lines parallel to the channel. These results are uniquely achieved without requiring the microfabrication of complex microchannel architectures and control schemes; the switching is simply achieved by adjusting two parameters: the acoustic excitation frequency and amplitude.
Bang, W; Bradley, P A; Vold, E L; Boettger, J C; Fernández, J C
2015-01-01
In a recent experiment on the Trident laser facility, a laser-driven beam of quasi-monoenergetic aluminum ions was used to heat solid gold and diamond foils isochorically to 5.5 eV and 1.7 eV, respectively. Here theoretical calculations are presented that suggest the gold and diamond were heated uniformly by these laser-driven ion beams. According to calculations and SESAME equation-of-state tables, laser-driven aluminum ion beams achievable on Trident, with a finite energy spread of (delta E)/E ~ 20%, are expected to heat the targets more uniformly than a beam of 140 MeV aluminum ions with zero energy spread. The robustness of the expected heating uniformity relative to the changes in the incident ion energy spectra is evaluated, and expected plasma temperatures of various target materials achievable with the current experimental platform are presented.
Trivelpiece-Gould modes in a uniform unbounded plasma
Stenzel, R. L.; Urrutia, J. M.
2016-09-01
Trivelpiece-Gould (TG) modes originally described electrostatic surface waves on an axially magnetized cylindrical plasma column. Subsequent studies of electromagnetic waves in such plasma columns revealed two modes, a predominantly magnetic helicon mode (H) and the mixed magnetic and electrostatic Trivelpiece-Gould modes (TG). The latter are similar to whistler modes near the oblique cyclotron resonance in unbounded plasmas. The wave propagation in cylindrical geometry is assumed to be paraxial while the modes exhibit radial standing waves. The present work shows that TG modes also arise in a uniform plasma without radial standing waves. It is shown experimentally that oblique cyclotron resonance arises in large mode number helicons. Their azimuthal wave number far exceeds the axial wave number which creates whistlers near the oblique cyclotron resonance. Cyclotron damping absorbs the TG mode and can energize electrons in the center of a plasma column rather than the edge of conventional TG modes. The angular orbital field momentum can produce new perpendicular wave-particle interactions.
Uniform electric field induced lateral migration of a sedimenting drop
Bandopadhyay, Aditya; Chakraborty, Suman
2015-01-01
We investigate the motion of a sedimenting spherical drop in the presence of an applied uniform electric field in an otherwise arbitrary direction in the limit of low surface charge convection. We analytically solve the electric potential in and around the leaky dielectric drop, and solve for the Stokesian velocity and pressure fields. We obtain the drop velocity through perturbations in powers of the electric Reynolds number which signifies the importance of the charge relaxation time scale as compared to the convective time scale. We show that in the presence of electric field either in the sedimenting direction or orthogonal to it, there is a change in the drop velocity only in the direction of sedimentation due to an asymmetric charge distribution in the same direction. However, in the presence of an electric field applied in both the directions, and depending on the permittivities and conductivities of the two fluids, we obtain a non-intuitive lateral migration of drop in addition to the buoyancy driven ...
Institute of Scientific and Technical Information of China (English)
Xiaoning Jing
2015-01-01
In order to exploit the enhancement of the multi-objective evolutionary algorithm based on decomposition (MOEA/D), we propose an improved algorithm with uniform de-sign (UD), i.e. MOEA/D-UD. Three mechanisms in MOEA/D-UD are modified by introducing an experimental design method cal ed UD. To ful y employ the information contained in the domain of the multi-objective problem, we apply UD to initialize a uniformly scattered population. Then, motivated by the analysis of the re-lationship between weight vectors and optimal solutions of scalar subproblems in the study of MOEA/D with adaptive weight ad-justment (MOEA/D-AWA), a new weight vector design method based on UD is introduced. To distinguish real sparse regions from pseudo sparse regions, i.e. discontinuous regions, of the complex Pareto front, the weight vector adjustment strategy in MOEA/D-UD adequately utilizes the information from neighbors of individuals. In the experimental study, we compare MOEA/D-UD with three outstanding algorithms, namely MOEA/D with the dif-ferential evolution operator (MOEA/D-DE), MOEA/D-AWA and the nondominated sorting genetic algorithm II (NSGA-II) on nineteen test instances. The experimental results show that MOEA/D-UD is capable of obtaining a wel-converged and wel diversified set of solutions within an acceptable execution time.
Armenta Salas, Michelle; Helms Tillery, Stephen I
2016-01-01
The neural mechanisms that take place during learning and adaptation can be directly probed with brain-machine interfaces (BMIs). We developed a BMI controlled paradigm that enabled us to enforce learning by introducing perturbations which changed the relationship between neural activity and the BMI's output. We introduced a uniform perturbation to the system, through a visuomotor rotation (VMR), and a non-uniform perturbation, through a decorrelation task. The controller in the VMR was essentially unchanged, but produced an output rotated at 30° from the neurally specified output. The controller in the decorrelation trials decoupled the activity of neurons that were highly correlated in the BMI task by selectively forcing the preferred directions of these cell pairs to be orthogonal. We report that movement errors were larger in the decorrelation task, and subjects needed more trials to restore performance back to baseline. During learning, we measured decreasing trends in preferred direction changes and cross-correlation coefficients regardless of task type. Conversely, final adaptations in neural tunings were dependent on the type controller used (VMR or decorrelation). These results hint to the similar process the neural population might engage while adapting to new tasks, and how, through a global process, the neural system can arrive to individual solutions. PMID:27601981
Geometry Modeling of Ship Hull Based on Non-uniform B-spline
Institute of Scientific and Technical Information of China (English)
WANG Hu; ZOU Zao-jian
2008-01-01
In order to generate the three-dimensional (3-D) hull surface accurately and smoothly, a mixed method which is made up of non-uniform B-spline together with an iterative procedure was developed. By using the iterative method the data points on each section curve are calculated and the generalized waterlines and transverse section curves are determined. Then using the non-uniform B-spline expression, the control vertex net of the hull is calculated based on the generalized waterlines and section curves. A ship with tunnel stern was taken as test case. The numerical results prove that the proposed approach for geometry modeling of 3-D ship hull surface is accurate and effective.
Nonlinear deformation of a ferrofluid droplet in a uniform magnetic field.
Zhu, Gui-Ping; Nguyen, Nam-Trung; Ramanujan, R V; Huang, Xiao-Yang
2011-12-20
This paper reports experimental and numerical results of the deformation of a ferrofluid droplet on a superhydrophobic surface under the effect of a uniform magnetic field. A water-based ferrofluid droplet surrounded by immiscible mineral oil was stretched by a magnetic field parallel to the substrate surface. The results show that an increasing flux density increases the droplet width and decreases the droplet height. A numerical model was established to study the equilibrium shape of the ferrofluid droplet. The governing equations for physical fields, including the magnetic field, are solved by the finite volume method. The interface between the two immiscible liquids was tracked by the level-set method. Nonlinear magnetization was implemented in the model. Comparison between experimental and numerical results shows that the numerical model can predict well the nonlinear deformation of a ferrofluid droplet in a uniform magnetic field. PMID:22044246
Achievement Goals and Achievement Emotions: A Meta-Analysis
Huang, Chiungjung
2011-01-01
This meta-analysis synthesized 93 independent samples (N = 30,003) in 77 studies that reported in 78 articles examining correlations between achievement goals and achievement emotions. Achievement goals were meaningfully associated with different achievement emotions. The correlations of mastery and mastery approach goals with positive achievement…
Fabrication of uniformly cell-laden porous scaffolds using a gas-in-liquid templating technique.
Takei, Takayuki; Aokawa, Ryuta; Shigemitsu, Takamasa; Kawakami, Koei; Yoshida, Masahiro
2015-11-01
Design of porous scaffolds in tissue engineering field was challenging. Uniform immobilization of cells in the scaffolds with high porosity was essential for homogeneous tissue formation. The present study was aimed at fabricating uniformly cell-laden porous scaffolds with porosity >74% using the gas-in-liquid foam templating technique. To this end, we used gelatin, microbial transglutaminase and argon gas as a scaffold material, cross-linker of the protein and porogen of scaffold, respectively. We confirmed that a porosity of >74% could be achieved by increasing the gas volume delivered to a gelatin solution. Pore size in the scaffold could be controlled by stirring speed, stirring time and the pore size of the filter through which the gas passed. The foaming technique enabled us to uniformly immobilize a human hepatoblastoma cell line in scaffold. Engraftment efficiency of the cell line entrapped within the scaffold in nude mice was higher than that of cells in free-form. These results showed that the uniformly cell-laden porous scaffolds were promising for tissue engineering.
Uniform electric field generation in circular multi-well culture plates using polymeric inserts
Tsai, Hsieh-Fu; Cheng, Ji-Yen; Chang, Hui-Fang; Yamamoto, Tadashi; Shen, Amy Q.
2016-05-01
Applying uniform electric field (EF) in vitro in the physiological range has been achieved in rectangular shaped microchannels. However, in a circular-shaped device, it is difficult to create uniform EF from two electric potentials due to different electrical resistances originated from the length difference between the diameter of the circle and the length of any parallel chord of the bottom circular chamber where cells are cultured. To address this challenge, we develop a three-dimensional (3D) computer-aided designed (CAD) polymeric insert to create uniform EF in circular shaped multi-well culture plates. A uniform EF with a coefficient of variation (CV) of 1.2% in the 6-well plate can be generated with an effective stimulation area percentage of 69.5%. In particular, NIH/3T3 mouse embryonic fibroblast cells are used to validate the performance of the 3D designed Poly(methyl methacrylate) (PMMA) inserts in a circular-shaped 6-well plate. The CAD based inserts can be easily scaled up (i.e., 100 mm dishes) to further increase effective stimulation area percentages, and also be implemented in commercially available cultureware for a wide variety of EF-related research such as EF-cell interaction and tissue regeneration studies.
Energy Technology Data Exchange (ETDEWEB)
Yang Min; Li Xiaoping; Xie Kai; Liu Donglin [School of Electronical and Mechanical Engineering, Xidian University, Xi' an Shaanxi 710071 (China); Liu Yanming [School of Telecommunications Engineering, Xidian University, Xi' an Shaanxi 710071 (China)
2013-01-15
A large volume uniform plasma generator is proposed for the experiments of electromagnetic (EM) wave propagation in plasma, to reproduce a 'black out' phenomenon with long duration in an environment of the ordinary laboratory. The plasma generator achieves a controllable approximate uniform plasma in volume of 260 mm Multiplication-Sign 260 mm Multiplication-Sign 180 mm without the magnetic confinement. The plasma is produced by the glow discharge, and the special discharge structure is built to bring a steady approximate uniform plasma environment in the electromagnetic wave propagation path without any other barriers. In addition, the electron density and luminosity distributions of plasma under different discharge conditions were diagnosed and experimentally investigated. Both the electron density and the plasma uniformity are directly proportional to the input power and in roughly reverse proportion to the gas pressure in the chamber. Furthermore, the experiments of electromagnetic wave propagation in plasma are conducted in this plasma generator. Blackout phenomena at GPS signal are observed under this system and the measured attenuation curve is of reasonable agreement with the theoretical one, which suggests the effectiveness of the proposed method.
Uniform electric field generation in circular multi-well culture plates using polymeric inserts
Tsai, Hsieh-Fu; Cheng, Ji-Yen; Chang, Hui-Fang; Yamamoto, Tadashi; Shen, Amy Q.
2016-01-01
Applying uniform electric field (EF) in vitro in the physiological range has been achieved in rectangular shaped microchannels. However, in a circular-shaped device, it is difficult to create uniform EF from two electric potentials due to different electrical resistances originated from the length difference between the diameter of the circle and the length of any parallel chord of the bottom circular chamber where cells are cultured. To address this challenge, we develop a three-dimensional (3D) computer-aided designed (CAD) polymeric insert to create uniform EF in circular shaped multi-well culture plates. A uniform EF with a coefficient of variation (CV) of 1.2% in the 6-well plate can be generated with an effective stimulation area percentage of 69.5%. In particular, NIH/3T3 mouse embryonic fibroblast cells are used to validate the performance of the 3D designed Poly(methyl methacrylate) (PMMA) inserts in a circular-shaped 6-well plate. The CAD based inserts can be easily scaled up (i.e., 100 mm dishes) to further increase effective stimulation area percentages, and also be implemented in commercially available cultureware for a wide variety of EF-related research such as EF-cell interaction and tissue regeneration studies. PMID:27193911
Jia, Yonggao; Chen, Chao; Jia, Dan; Li, Shuxin; Ji, Shulin; Ye, Changhui
2016-04-20
The uniformity of the sheet resistance of transparent conductive films is one of the most important quality factors for touch panel applications. However, the uniformity of silver nanowire transparent conductive films is far inferior to that of indium-doped tin oxide (ITO). Herein, we report a dynamic heating method using infrared light to achieve silver nanowire transparent conductive films with high uniformity. This method can overcome the coffee ring effect during the drying process and suppress the aggregation of silver nanowires in the film. A nonuniformity factor of the sheet resistance of the as-prepared silver nanowire transparent conductive films could be as low as 6.7% at an average sheet resistance of 35 Ω/sq and a light transmittance of 95% (at 550 nm), comparable to that of high-quality ITO film in the market. In addition, a mechanical study shows that the sheet resistance of the films has little change after 5000 bending cycles, and the film could be used in touch panels for human-machine interactive input. The highly uniform and mechanically stable silver nanowire transparent conductive films meet the requirement for many significant applications and could play a key role in the display market in a near future. PMID:27054546
Droplet condensation on chemically homogeneous and heterogeneous surfaces
Ashrafi, Amir; Moosavi, Ali
2016-09-01
Nucleation and growth of condensing droplets on horizontal surfaces are investigated via a 2-D double distribution function thermal lattice Boltzmann method. First, condensation on completely uniform surface is investigated and different mechanisms which cause dropwise and filmwise condensation are studied. The results reveal the presence of cooled vapor layer instability in the condensation on completely smooth surfaces. In the second step, condensation on chemically heterogeneous surfaces is investigated. Moreover, the effect of non-uniformity in the surface temperature is also studied. The results indicate that the vapor layer instability and the nucleation start from the heterogeneities. The effects of different numbers of heterogeneities, their distance, and hydrophobicity on the condensation are also inspected. It is shown that by increasing the hydrophobicity of the heterogeneities and considering an optimum space between the heterogeneities, maximum condensation performance can be achieved. Finally, condensation on wettability gradient surfaces is studied and the effects of the gradient form and contact angle of the core region on the condensation are studied. It is shown that hydrophobicity of the core region plays a key role in increasing the condensation performance. A heat transfer analysis and flow dynamics of dropwise condensation as a function of time is also presented and it is shown that the results are in good agreements with the previous theoretical and experimental results.
Uniform bounds for expressions involving modified Bessel functions
Gaunt, Robert E.
2013-01-01
In this paper, we obtain uniform bounds for a number of expressions that involve derivatives and integrals of modified Bessel functions. These uniform bounds are motivated by the need to bound such expressions in the study of variance-gamma and product normal approximations via Stein's method.
7 CFR 51.1447 - Fairly uniform in color.
2010-01-01
... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly uniform in color. 51.1447 Section 51.1447... color. Fairly uniform in color means that 90 percent or more of the kernels in the lot have skin color within the range of one or two color classifications....
7 CFR 51.2085 - Fairly uniform color.
2010-01-01
... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly uniform color. 51.2085 Section 51.2085 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... color. Fairly uniform color means that the shells do not show excessive variation in color,...
7 CFR 51.1407 - Fairly uniform in color.
2010-01-01
... 7 Agriculture 2 2010-01-01 2010-01-01 false Fairly uniform in color. 51.1407 Section 51.1407 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... in color. Fairly uniform in color means that the shells do not show sufficient variation in color...
Uniform attractors of non-autonomous dissipative semilinear wave equations
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
The asymptotic long time behaviors of a certain type of non-autonomous dissipative semilinear wave equations are studied. The existence of uniform attractors is proved and their upper bounds for both Hausdorff and Fractal dimensions of uniform are given when the external force satisfies suitable conditions.
Evaluation of School Uniform Policy in Turkey: A Case Study
Cinoglu, Mustafa
2014-01-01
The purpose of this study is to evaluate the results of current school uniform policies according to views of stakeholders. Descriptive case study method was used for this study to understand the concerns of the stakeholders about school uniforms. Data was collected through interviews with stakeholders and also reviewing the documents in TOKI…
A directional uniformity of periodic point distribution and mixing
Miles, R
2010-01-01
For mixing Z^d-actions generated by commuting automorphisms of a compact abelian group, we show that directional mixing and directional convergence of the uniform measure supported on periodic points to Haar measure occurs at a uniform rate independent of the direction. The proof exploits the tight connection between the adelic amoeba associated to the action and the dynamics.
Radionic Non-uniform Black Strings --short version--
Tamaki, Takashi; Kanno, Sugumi; Soda, Jiro
2003-01-01
Non-uniform black strings in the two-brane system are investigated using the effective action approach. It is shown that the radion acts as a non-trivial hair of black strings. The stability of solutions is demonstrated using the catastrophe theory. The black strings are shown to be non-uniform.
The FEL-TNO uniform open systems model
Luiijf, H.A.M.; Overbeek, P.L.
1989-01-01
The FEL-TNO Uniform Open Systems Model is based upon the IS0/0SI Basic Reference Model and integrates operating systems, (OSI) networks, equipment and media into one single uniform nodel. Usage of the model stimulates the development of operating systen and network independent applications and puts
22 CFR 1203.735-212 - Wearing of uniforms.
2010-04-01
... 22 Foreign Relations 2 2010-04-01 2010-04-01 true Wearing of uniforms. 1203.735-212 Section 1203.735-212 Foreign Relations UNITED STATES INTERNATIONAL DEVELOPMENT COOPERATION AGENCY EMPLOYEE... employees are not considered uniforms within the meaning of this section except that, for ICA, MOA VII...
Regular-uniform convergence and the open-open topology
Porter, Kathryn F.
2001-01-01
In 1994, Bânzaru introduced the concept of regular-uniform, or r-uniform, convergence on a family of functions. We discuss the relationship between this topology and the open-open topology, which was described in 1993 by Porter, on various collections of functions.
46 CFR 310.63 - Uniforms and textbooks.
2010-10-01
... 46 Shipping 8 2010-10-01 2010-10-01 false Uniforms and textbooks. 310.63 Section 310.63 Shipping MARITIME ADMINISTRATION, DEPARTMENT OF TRANSPORTATION TRAINING MERCHANT MARINE TRAINING Admission and Training of Midshipmen at the United States Merchant Marine Academy § 310.63 Uniforms and textbooks....
Measurement Method of the Thickness Uniformity for Polymer Films
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Several methods for investigating the thickness uniformity of polymer thin films are presented as well as their measurement principles. A comparison of these experimental methods is given.The cylindrical lightwave reflection method is found to can obtain the thickness distribution along a certain direction.It is a simple and suitable method to evaluate the film thickness uniformity.
The demagnetizing field of a non-uniform rectangular prism
DEFF Research Database (Denmark)
Smith, Anders; Nielsen, Kaspar Kirstein; Christensen, Dennis;
2010-01-01
The effect of demagnetization on the magnetic properties of a rectangular ferromagnetic prism under non-uniform conditions is investigated. A numerical model for solving the spatially varying internal magnetic field is developed, validated and applied to relevant cases. The demagnetizing field......-uniformity of the internal field, especially for non-constant temperature distributions and composite magnetic materials....
Ground subsidence due to uniform fluid extraction over a circular region within an aquifer
Selvadurai, A. P. S.; Kim, Jueun
2015-04-01
This paper examines the ground subsidence caused by the uniform extraction of fluids from a disc-shaped region located within a poroelastic halfspace. Biot's theory of poroelasticity is used to examine the problem. The fluid extraction over the circular region at the interior of the poroelastic domain induces time-dependent axisymmetric surface settlements. The theoretical results are also used to examine the accuracy of a multi-physics computational scheme that can be used to examine more complex geological settings.
The Key Factor for Uniform and Patterned Glow Dielectric Barrier Discharge
Institute of Scientific and Technical Information of China (English)
OUYANG Ji-Ting; DUAN Xiao-Xi; XU Shao-Wei; HE Feng
2012-01-01
We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure. A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay, while the patterned structure appears above a critical frequency when the space charge is nonuniform. The patterns start from the electrode edge where the electric field is significantly distorted, characterized by the patterned seed electrons that always form ahead of the surface charges. The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges. The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure.%We present the results from 2D fluid modeling of the key roles controlling the glow dielectric barrier discharge (DBD) structure.A uniform DBD can be sustained at lower frequency when the space charge reaches uniformity due to plasma decay,while the patterned structure appears above a critical frequency when the space charge is nonuniform.The patterns start from the electrode edge where the electric field is significantly distorted,characterized by the patterned seed electrons that always form ahead of the surface charges.The formation of the patterned DBD structure is associated with the lateral inhibition of the local increase of space charges.The distribution of the volume seed electrons plays a key role in the DBD structure while the distribution of surface charge is a result of the formed structure.
Picard-Fuchs Uniformization: Modularity of the Mirror Map and Mirror-Moonshine
Doran, Charles F.
1998-01-01
Motivated by a conjecture of Lian and Yau concerning the mirror map in string theory, we determine when the mirror map q-series of certain elliptic curve and K3 surface families are Hauptmoduln (genus zero modular functions). Our geometric criterion for modularity characterizes orbifold uniformization properties of their Picard-Fuchs equations, effectively demystifying the mirror-moonshine phenomenon. A longer, more comprehensive treatment of these results will appear shortly.
Uniform dimension results of multi-parameter stable processes
Institute of Scientific and Technical Information of China (English)
林火南
1999-01-01
The problem of uniform dimensions for multi-parameter processes, which may not possess the uniform stochastic H(?)lder condition, is investigated. The problem of uniform dimension for multi-parameter stable processes is solved. That is, if Z is a stable (N, d, α)-process and αN≤d, then (?)E(?)R_+~N, dimZ(E)=α·dimE holds with probability 1, where Z(E)={x:(?)t∈E, Z_t=x} is the image set of Z on E. The uniform upper bounds for multi-parameter processes with independent increments under general conditions are also given. Most conclusions about uniform dimension can be considered as special cases of our results.
Energy Technology Data Exchange (ETDEWEB)
Temporal, M., E-mail: mauro.temporal@hotmail.com [Centre de Mathématiques et de Leurs Applications, ENS Cachan and CNRS, 61 Av. du President Wilson, F-94235 Cachan Cedex (France); Canaud, B. [CEA, DIF, F-91297 Arpajon Cedex (France); Garbett, W. J. [AWE plc, Aldermaston, Reading, Berkshire RG7 4PR (United Kingdom); Ramis, R. [ETSI Aeronáutica y del Espacio, Universidad Politécnica de Madrid, 28040 Madrid (Spain)
2015-10-15
The implosion uniformity of a directly driven spherical inertial confinement fusion capsule is considered within the context of the Laser Mégajoule configuration. Two-dimensional (2D) hydrodynamic simulations have been performed assuming irradiation with two laser beam cones located at 49° and 131° with respect to the axis of symmetry. The laser energy deposition causes an inward shock wave whose surface is tracked in time, providing the time evolution of its non-uniformity. The illumination model has been used to optimize the laser intensity profiles used as input in the 2D hydro-calculations. It is found that a single stationary laser profile does not maintain a uniform shock front over time. To overcome this drawback, it is proposed to use two laser profiles acting successively in time, in order to dynamically stabilize the non-uniformity of the shock front.
Rubber-induced uniform laser shock wave pressure for thin metal sheets microforming
Shen, Zongbao; Wang, Xiao; Liu, Huixia; Wang, Yayuan; Wang, Cuntang
2015-02-01
Laser shock microforming of thin metal sheets is a new high velocity forming technique, which employs laser shock wave to deform the thin metal sheets. The spatial distribution of forming pressure is mainly dependent on the laser beam. A new type of laser shock loading method is introduced which gives a uniform pressure distribution. A low density rubber is inserted between the laser beam and the thin metal sheets. The mechanism of rubber-induced smoothing effect on confined laser shock wave is proposed. Plasticine is used to perform the smoothing effect experiments due to its excellent material flow ability. The influence of rubber on the uniformity of laser shock wave pressure is studied by measuring the surface micro topography of the deformed plasticine. And the four holes forming experiment is used to verify the rubber-induced uniform pressure on thin metal sheets surface. The research results show the possibility of smoothing laser shock wave pressure using rubber. And the good surface quality can be obtained under rubber dynamic loading.
Rapid analysis of non-uniformly sampled pulsed field gradient data for velocity estimation.
Raghavan, K; Park, J C; Pavlovskaya, G E; Gibbs, S J
2001-06-01
Bretthorst's recent generalization of the Lomb-Scargle periodogram shows that a sufficient statistic for frequency estimation from non-uniformly, but simultaneously sampled quadrature data is equivalent to the FFT of those data with the missing samples replaced by zeros. We have applied this concept to the rapid analysis of pulsed field gradient MRI data which have been non-uniformly sampled in the velocity encoding wave vector q. For a small number of q samples, it is more computationally efficient to calculate the periodogram directly rather than using the FFT algorithm with a large number of zeros. The algorithm we have implemented for finding the peak of the generalized periodogram is simple and robust; it involves repeated apodization and grid searching of the periodogram until the desired velocity resolution is achieved. The final estimate is refined by quadratic interpolation. We have tested the method for fully developed Poiseuille flow of a Newtonian fluid and have demonstrated substantial improvement in the precision of velocity measurement achievable in a fixed acquisition time with non-uniform sampling. The method is readily extendible to multidimensional data. Analysis of a 256 by 256 pixel image with 8 q samples and an effective velocity resolution of better than 1/680 of the Nyquist range requires approximately 1 minute computation time on a 400 MHz SUN Ultrasparc II processor. PMID:11672628
A snapback suppressed reverse-conducting IGBT with uniform temperature distribution
Chen, Wei-Zhong; Li, Ze-Hong; Zhang, Bo; Ren, Min; Zhang, Jin-Ping; Liu, Yong; Li, Zhao-Ji
2014-01-01
A novel reverse-conducting insulated-gate bipolar transistor (RC-IGBT) featuring a floating P-plug is proposed. The P-plug is embedded in the n-buffer layer to obstruct the electron current from flowing directly to the n-collector, which achieves the hole emission from the p-collector at a small collector size and suppresses the snapback effectively. Moreover, the current is uniformly distributed in the whole wafer at both IGBT mode and diode mode, which ensures the high temperature reliability of the RC-IGBT. Additionally, the P-plug acts as the base of the N-buffer/P-float/N-buffer transistor, which can be activated to extract the excessive carriers at the turn-off process. As the the simulation results show, for the proposed RC-IGBT, it achieves almost snapback-free output characteristics with a uniform current density and a uniform temperature distribution, which can greatly increase the reliability of the device.
A New Uniform Phase Bridge Functional: Test and Its Application to Non-uniform Phase Fluid
Institute of Scientific and Technical Information of China (English)
ZHOU Shi-Qi; CHEN Hong; ZHANG Xiao-Qi
2003-01-01
A new bridge functional as a function of indirect correlation function was proposed, which was basedon analysis on the asymptotic behavior of the Ornstein-Zernike (OZ) equation system and a series expansion whoserenormalization resulted in an adjustable parameter determined by the thermodynamics consistency condition. Theproposed bridge functional was tested by applying it to bulk hard sphere and hard core Yukawa fluid for the predictionof structure and thermodynamics properties based on the OZ equation. As an application, the present bridge functionalwas employed for non-uniform fluid of the above two kinds by means of the density functional theory methodology, theresulting density distribution profiles were in good agreement with the available computer simulation data.
Surface modification of polymeric materials by cold atmospheric plasma jet
Energy Technology Data Exchange (ETDEWEB)
Kostov, K.G., E-mail: kostov@feg.unesp.br [Faculty of Engineering in Guaratinguetá–FEG, Universidade Estadual Paulista–UNESP Guaratiguetá, 12516-410, SP (Brazil); Nishime, T.M.C.; Castro, A.H.R. [Faculty of Engineering in Guaratinguetá–FEG, Universidade Estadual Paulista–UNESP Guaratiguetá, 12516-410, SP (Brazil); Toth, A. [Institute of Material and Environmental Chemistry, Hungarian Academy of Science P.O. Box 17, H-1525, Budapest (Hungary); Hein, L.R.O. [Faculty of Engineering in Guaratinguetá–FEG, Universidade Estadual Paulista–UNESP Guaratiguetá, 12516-410, SP (Brazil)
2014-09-30
Highlights: • We investigate polymer surface modification by atmospheric pressure plasma jet APPJ. • Jet operation conditions for uniform surface modification were determined. • The APPJ added O atoms to the polymer surface and also enhanced the roughness. • The degree of polymer surface modification by APPJ and DBD were compared. • The APPJ is more efficient in attaching O atoms and produces less polymer fragments. - Abstract: In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source – the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40° in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure.
Energy Technology Data Exchange (ETDEWEB)
Bakhshayesh, A. M.; Mohammadi, M. R., E-mail: mrm41@cam.ac.uk; Masihi, N.; Akhlaghi, M. H. [Sharif University of Technology, Department of Materials Science and Engineering (Iran, Islamic Republic of)
2013-09-15
A new facile strategy for fabrication of high surface area electrode in the form of mixtures of coated carbon nanotubes (CNTs) and TiO{sub 2} nanoparticles with various weight ratios is reported. The so-called polymeric gel process was used to deposit thick film containing uniform distribution of TiO{sub 2} nanoparticles and coated CNTs with high porosity by dip coating for dye-sensitized solar cells (DSSCs) applications. Based on simultaneous differential thermal analysis, the minimum annealing temperature to obtain inorganic- and organic-free films was determined at 500 Degree-Sign C. X-ray diffraction analysis revealed that deposited films were composed of primary nanoparticles with crystallite size in the range 21-45 nm. Field emission scanning electron microscope images showed that deposited films had porous morphology containing uniform spherical particles with diameter around 2.5 {mu}m and coated CNTs with TiO{sub 2} nanoparticles (TNTs). The spherical particles were composed of small nanoparticles ({approx}60 nm), improving light scattering and dye loading of the DSSC. Moreover, TNTs were uniformly incorporated into the electrodes, improving electron transportation. X-ray photoelectron spectroscopy was presented as an obvious proof for the inclusion of CNTs into the TiO{sub 2} matrix. Ultraviolet-visible spectroscopy showed that CNT introduction enhanced the visible light absorption of photoanode by shifting the absorption onset to visible light region. An enhancement of power conversion efficiency (PCE) from 6.53 % for pure TiO{sub 2} to 7.38 % for CNT-TiO{sub 2} electrode containing 0.025 wt% CNTs was achieved. This well-incorporated study would present an intellectual development in the fabrication of low-cost CNT consolidated DSSCs with high PCE.
Differential orientation of 10T1/2 mesenchymal cells on non-uniform stretch environments.
Richardson, W J; van der Voort, D D; Wilson, E; Moore, J E
2013-09-01
Non-uniform stress and strain fields are prevalent in many tissues in vivo, and often exacerbated by disease or injury. These mechanical gradients potentially play a role in contributing to pathological conditions, presenting a need for experimental tools to allow investigation of cell behavior within non-uniformly stimulated environments. Herein, we employ two in vitro cell-stretching devices (one previously published; one newly presented) capable of subjecting cells to cyclic, non-uniform stretches upon the surface of either a circular elastomeric membrane or a cylindrical PDMS tube. After 24 hours of cyclic stretch, 10T1/2 cells on both devices showed marked changes in long-axis orientation, with tendencies to align parallel to the direction of minimal deformation. The degree of this response varied depending on location within the stretch gradients. These results demonstrated the feasibility of conducting cell mechanobiology investigations with the two novel devices, while also highlighting the experimental capabilities of non-uniform mechanical environments for these types of studies. Such capabilities include robust data collection for developing mechanobiological dose-response curves, signal threshold identification, and potential spatial targeting for drug delivery. PMID:24396979
ACTION OF UNIFORM SEARCH ALGORITHM WHEN SELECTING LANGUAGE UNITS IN THE PROCESS OF SPEECH
Directory of Open Access Journals (Sweden)
Nekipelova Irina Mikhaylovna
2013-04-01
Full Text Available The article is devoted to research of action of uniform search algorithm when selecting by human of language units for speech produce. The process is connected with a speech optimization phenomenon. This makes it possible to shorten the time of cogitation something that human want to say, and to achieve the maximum precision in thoughts expression. The algorithm of uniform search works at consciousness and subconsciousness levels. It favours the forming of automatism produce and perception of speech. Realization of human's cognitive potential in the process of communication starts up complicated mechanism of self-organization and self-regulation of language. In turn, it results in optimization of language system, servicing needs not only human's self-actualization but realization of communication in society. The method of problem-oriented search is used for researching of optimization mechanisms, which are distinctive to speech producing and stabilization of language.
Directory of Open Access Journals (Sweden)
Chunduri SreenivasaRao
2012-10-01
Full Text Available For high fidelity sound reproduction, it is necessary to use long filter coefficients in audio crosstalk cancellation. To implement these long filters on real-time DSP processors, conventional overlap save technique suffers from more computational power as well as processing delay. To overcome these technical problems, mixed uniform partitioned convolution technique is proposed. This method is derived by combining uniform partitioned convolution with mixed filtering technique. With the proposed method, it is possible to perform audio crosstalk cancellation even at the order of ten thousand filter taps with less computations and short processing delay. The proposed technique was implemented on 32-bit floating point DSP processor and design was provided with efficient memory management to achieve optimization in computational complexity. The computational comparison of this method with conventional methods shows that the proposed technique is very efficient for long filters
Influence of multilayer films condenser on imaging uniformity of Schwarzschild microscope
International Nuclear Information System (INIS)
The method for improving the uniformity of the image using multilayer films condenser is proposed. The optical structure of the condenser is designed, which concentrates 80% energy radiated by plasma to about 0.8 mm diameter range. Based on the system's wavelength and incidence angle of light, the Mo/Si multilayer films with period of 9.64 nm and layers of 30 is designed and the coatings are deposited with magnetron sputtering. The reflectivity of optical elements at 18.2 nm is 51.7%. The grid backlit by EUV rays focused using condenser is imaging via Schwarzschild microscope on CCD. The results show that spatial resolution of 2.5 μm can be achieved in the 1.2 mm field, and the non-uniformity of image caused by the obscuration of objective is eliminated absolutely. (authors)
Extension of the modal wave-front reconstruction algorithm to non-uniform illumination.
Ma, Xiaoyu; Mu, Jie; Rao, ChangHui; Yang, Jinsheng; Rao, XueJun; Tian, Yu
2014-06-30
Attempts are made to eliminate the effects of non-uniform illumination on the precision of wave-front measurement. To achieve this, the relationship between the wave-front slope at a single sub-aperture and the distributions of the phase and light intensity of the wave-front were first analyzed to obtain the relevant theoretical formulae. Then, based on the principle of modal wave-front reconstruction, the influence of the light intensity distribution on the wave-front slope is introduced into the calculation of the reconstruction matrix. Experiments were conducted to prove that the corrected modal wave-front reconstruction algorithm improved the accuracy of wave-front reconstruction. Moreover, the correction is conducive to high-precision wave-front measurement using a Hartmann wave-front sensor in the presence of non-uniform illumination.
Li, Li; Gu, Chun; Xu, Lixin; Zhou, Shenlei
2016-04-01
The self-adapting algorithms are improved to optimize a beam configuration in the direct drive laser fusion system with the solid state lasers. A configuration of 32 laser beams is proposed for achieving a high uniformity illumination, with a root-mean-square deviation at 10-4 level. In our optimization, the parameters such as beam number, beam arrangement, and beam intensity profile are taken into account. The illumination uniformity robustness versus the parameters such as intensity profile deviations, power imbalance, intensity profile noise, the pointing error, and the target position error is also discussed. In this study, the model is assumed a solid-sphere illumination, and refraction effects of incident light on the corona are not considered. Our results may have a potential application in the design of the direct-drive laser fusion of the Shen Guang-II Upgrading facility (SG-II-U, China).
Local Synthesis and Tooth Contact Analysis of Face-Milled, Uniform Tooth Height Spiral Bevel Gears
Litvin, F. L.; Wang, A. G.
1996-01-01
Face-milled spiral bevel gears with uniform tooth height are considered. An approach is proposed for the design of low-noise and localized bearing contact of such gears. The approach is based on the mismatch of contacting surfaces and permits two types of bearing contact either directed longitudinally or across the surface to be obtained. Conditions to avoid undercutting were determined. A Tooth Contact Analysis (TCA) was developed. This analysis was used to determine the influence of misalignment on meshing and contact of the spiral bevel gears. A numerical example that illustrates the theory developed is provided.
A fluorescent laser-diffuser arrangement for uniform backlighting
Jain, Saransh; Somasundaram, S.; Anand, T. N. C.
2016-02-01
Laser-light diffusers are used in conjunction with pulsed lasers to generate bright, spatially uniform background illumination for imaging and particle sizing applications. The present paper describes a cost effective way of fabricating a fluorescent laser-light diffuser. The procedure to obtain a uniform background using laser illumination is explained. To characterize the diffuser, images are acquired using a CCD camera with the illumination provided using the diffuser and the variations of pixel intensity values along the centerline of the images are plotted. It is observed that the standard deviation of pixel intensity values is fairly small. Hence, these diffusers are suitable for experiments that need a uniform background.
Uniformly expanding vacuum: a possible interpretation of the dark energy
Huang, Peng
2016-01-01
Following the spirit of the equivalence principle, we take a step further to recognize the free fall of the observer as a method to eliminate causes that would lead the perceived vacuum to change its original state. Thus, it is expected that the vacuum should be in a rigid Minkowski state or be uniformly expanding. By carefully investigating the impact on measurement caused by the expansion, we clarify the exact meaning of the uniformly expanding vacuum and find that the cosmological-constant-like dark energy is in fact a manifestation and the observational confirmation of uniformly expanding vacuum.
Transverse vibrations of arbitrary non-uniform beams
Institute of Scientific and Technical Information of China (English)
郭树起; 杨绍普
2014-01-01
Free and steady state forced transverse vibrations of non-uniform beams are investigated with a proposed method, leading to a series solution. The obtained series is verified to be convergent and linearly independent in a convergence test and by the non-zero value of the corresponding Wronski determinant, respectively. The obtained solution is rigorous, which can be reduced to a classical solution for uniform beams. The proposed method can deal with arbitrary non-uniform Euler-Bernoulli beams in principle, but the methods in terms of special functions or elementary functions can only work in some special cases.
UNIFORM PACKING DIMENSION RESULTS FOR MULTIPARAMETER STABLE PROCESSES
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
In this article, authors discuss the problem of uniform packing dimension of the image set of multiparameter stochastic processes without random uniform H(o)lder condition, and obtain the uniform packing dimension of multiparameter stable processes.If Z is a stable (N, d, α)-process and αN ≤ d, then the following holds with probability 1 Dim Z(E) = α DimE for any Borel setE ∈ B(R+N),where Z(E) = {x: (E) t ∈ E, Z(t) = x}. Dim(E) denotes the packing dimension of E.
Personal Exposure to Contaminant Sources in a Uniform Velocity Field
DEFF Research Database (Denmark)
Brohus, Henrik; Nielsen, Peter V.
The objective of this study has been to determine the personal exposure to a contaminant source in a uniform velocity field. This was done by full-scale measurements and computer simulations. The results showed a significant dependence on the velocity field both regarding the direction and the ma...... the usual operation range. Guidelines for personal exposure reduction in a uniform velocity field are discussed.......The objective of this study has been to determine the personal exposure to a contaminant source in a uniform velocity field. This was done by full-scale measurements and computer simulations. The results showed a significant dependence on the velocity field both regarding the direction...
Constructing uniform color space in CIECAM97s
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The uniformity of two pairs of color spaces based on CIE 1997 color appearance model (CIECAM97s) is analyzed according to color-discrimination ellipses that are constructed using color-difference evaluation data. A new uniform color space named Jucs a ucs b ucs is deduced by re-scaling the coordinates of lightness, redness-greenness and vellowness-blueness in two initial color spaces using linear regression method. The uniformity of the new color space is obviously improved compared with the initial color spaces.
Chemical vapor deposition reactor. [providing uniform film thickness
Chern, S. S.; Maserjian, J. (Inventor)
1977-01-01
An improved chemical vapor deposition reactor is characterized by a vapor deposition chamber configured to substantially eliminate non-uniformities in films deposited on substrates by control of gas flow and removing gas phase reaction materials from the chamber. Uniformity in the thickness of films is produced by having reactive gases injected through multiple jets which are placed at uniformally distributed locations. Gas phase reaction materials are removed through an exhaust chimney which is positioned above the centrally located, heated pad or platform on which substrates are placed. A baffle is situated above the heated platform below the mouth of the chimney to prevent downdraft dispersion and scattering of gas phase reactant materials.
2010-04-01
... participated in the assessment. (b) Method B—Uniform Averaging Procedure. A school may use uniform averaging... 25 Indians 1 2010-04-01 2010-04-01 false If a school fails to achieve its annual measurable... Adequate Yearly Progress § 30.116 If a school fails to achieve its annual measurable objectives, what...
Attitude Towards Physics and Additional Mathematics Achievement Towards Physics Achievement
Veloo, Arsaythamby; Nor, Rahimah; Khalid, Rozalina
2015-01-01
The purpose of this research is to identify the difference in students' attitude towards Physics and Additional Mathematics achievement based on gender and relationship between attitudinal variables towards Physics and Additional Mathematics achievement with achievement in Physics. This research focused on six variables, which is attitude towards…
Liu, Yuxi; Dai, Hongxing; Deng, Jiguang; Zhang, Lei; Zhao, Zhenxuan; Li, Xinwei; Wang, Yuan; Xie, Shaohua; Yang, Huanggen; Guo, Guangsheng
2013-08-01
Uniform hollow spherical rhombohedral LaMO3 and solid spherical cubic MOx (M = Mn and Co) NPs were fabricated using the PMMA-templating strategy. Hollow spherical LaMO3 and solid spherical MOx NPs possessed surface areas of 21-33 and 21-24 m(2)/g, respectively. There were larger amounts of surface-adsorbed oxygen species and better low-temperature reducibility on/of the hollow spherical LaMO3 samples than on/of the solid spherical MOx samples. Hollow spherical LaMO3 and solid spherical MOx samples outperformed their nanosized counterparts for oxidation of CO and toluene, with the best catalytic activity being achieved over the solid spherical Co3O4 sample for CO oxidation (T50% = 81 °C and T90% = 109 °C) at space velocity = 10,000 mL/(g h) and the hollow spherical LaCoO3 sample for toluene oxidation (T50% = 220 °C and T90% = 237 °C) at space velocity = 20,000 mL/(g h). It is concluded that the higher surface areas and oxygen adspecies concentrations and better low-temperature reducibility are responsible for the excellent catalytic performance of the hollow spherical LaCoO3 and solid spherical Co3O4 NPs. We believe that the PMMA-templating strategy provides an effective route to prepare uniform perovskite-type oxide and transition-metal oxide NPs.
Condensation on surface energy gradient shifts drop size distribution toward small drops.
Macner, Ashley M; Daniel, Susan; Steen, Paul H
2014-02-25
During dropwise condensation from vapor onto a cooled surface, distributions of drops evolve by nucleation, growth, and coalescence. Drop surface coverage dictates the heat transfer characteristics and depends on both drop size and number of drops present on the surface at any given time. Thus, manipulating drop distributions is crucial to maximizing heat transfer. On earth, manipulation is achieved with gravity. However, in applications with small length scales or in low gravity environments, other methods of removal, such as a surface energy gradient, are required. This study examines how chemical modification of a cooled surface affects drop growth and coalescence, which in turn influences how a population of drops evolves. Steam is condensed onto a horizontally oriented surface that has been treated by silanization to deliver either a spatially uniform contact angle (hydrophilic, hydrophobic) or a continuous radial gradient of contact angles (hydrophobic to hydrophilic). The time evolution of number density and associated drop size distributions are measured. For a uniform surface, the shape of the drop size distribution is unique and can be used to identify the progress of condensation. In contrast, the drop size distribution for a gradient surface, relative to a uniform surface, shifts toward a population of small drops. The frequent sweeping of drops truncates maturation of the first generation of large drops and locks the distribution shape at the initial distribution. The absence of a shape change indicates that dropwise condensation has reached a steady state. Previous reports of heat transfer enhancement on chemical gradient surfaces can be explained by this shift toward smaller drops, from which the high heat transfer coefficients in dropwise condensation are attributed to. Terrestrial applications using gravity as the primary removal mechanism also stand to benefit from inclusion of gradient surfaces because the critical threshold size required for
Directory of Open Access Journals (Sweden)
Christopher Martinez
2007-02-01
Full Text Available Hashing algorithms long have been widely adopted to design a fast address look-up process which involves a search through a large database to find a record associated with a given key. Hashing algorithms involve transforming a key inside each target data to a hash value hoping that the hashing would render the database a uniform distribution with respect to this new hash value. The close the final distribution is to uniform, the less search time would be required when a query is made. When the database is already key-wise uniformly distributed, any regular hashing algorithm, such as bit-extraction, bit-group XOR, etc., would easily lead to a statistically perfect uniform distribution after the hashing. On the other hand, if records in the database are instead not uniformly distributed as in almost all known practical applications, then even different regular hash functions would lead to very different performance. When the target database has a key with a highly skewed distributed value, performance delivered by regular hashing algorithms usually becomes far from desirable. This paper aims at designing a hashing algorithm to achieve the highest probability in leading to a uniformly distributed hash result from a non-uniformly distributed database. An analytical pre-process on the original database is first performed to extract critical information that would significantly benefit the design of a better hashing algorithm. This process includes sorting on the bits of the key to prioritize the use of them in the XOR hashing sequence, or in simple bit extraction, or even a combination of both. Such an ad hoc hash design is critical to adapting to all real-time situations when there exists a changing (and/or expanding database with an irregular non-uniform distribution. Significant improvement from simulation results is obtained in randomly generated data as well as real data.
Magnetic vortex driven by non-uniform injection of spin-polarized current in nano-scale spin valves
International Nuclear Information System (INIS)
We demonstrate that a current pulse of a non-uniform spin-polarized current density in a nanomagnet can drive, apart from magnetization reversal a static magnetic vortex. This vortex configuration can be achieved in low shape anisotropy spin valves of elliptical cross-sectional area. These non-uniform configurations exist also in presence of either ion mill damages below the nano-aperture or thermal effects at low temperature. We performed a numerical experiment of spin-torque driven ferromagnetic resonance in a magnetic vortex configuration, our results predict a frequency response with a few maxima and minima related to small oscillation of the vortex state around its equilibrium configuration
The Uniform:a combination of Style and Philosophy
Murphy, James Peter
2009-01-01
Well groomed staff not only give your pub an edge but they are a prerequisite to your overall business success. Uniforms play an important role and sometimes they can be a true reflection of your bars or hotels business philosophy
Valuation theoretic and model theoretic aspects of local uniformization
Kuhlmann, Franz-Viktor
2010-01-01
This paper gives a survey on a valuation theoretical approach to local uniformization in positive characteristic, the model theory of valued fields in positive characteristic, and their connection with the valuation theoretical phenomenon of defect.
Health Center Program Data-Uniform Data System
U.S. Department of Health & Human Services — HRSA's Bureau of Primary Health Care's Uniform Data System (UDS) tracks a variety of information, including patient demographics, services provided, clinical...
Difference schemes on non-uniform mesh and their application
Institute of Scientific and Technical Information of China (English)
MA Yanwen; GAO Hui; FU Dexun; LI Xinliang
2004-01-01
High order accurate schemes are needed to simulate the multi-scale complex flow fields to get fine structures in simulation of the complex flows with large gradient of fluid parameters near the wall, and schemes on non-uniform mesh are desirable for many CFD (computational fluid dynamics) workers. The construction methods of difference approximations and several difference approximations on non-uniform mesh are presented. The accuracy of the methods and the influence of stretch ratio of the neighbor mesh increment on accuracy are discussed. Some comments on these methods are given, and comparison of the accuracy of the results obtained by schemes based on both non-uniform mesh and coordinate transformation is made, and some numerical examples with non-uniform mesh are presented.
Uniform fuel target implosion in heavy ion inertial fusion
Kawata, S.; Karino, T.; Kondo, S.; Iinuma, T.; Barada, D.; Ma, Y. Y.; Ogoyski, A. I.
2016-05-01
For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the non-uniformity mitigation mechanisms in the heavy ion beam (HIB) illumination are discussed in heavy ion inertial fusion (HIF). A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to the radiation energy smoothing for the HIB illumination non-uniformity. The large density-gradient scale, which is typically ∼500μm in HIF targets, also contributes to a reduction of the Rayleigh- Taylor instability growth rate. In HIF a wobbling HIBs illumination would also reduce the Rayleigh-Taylor instability growth and to realize a uniform implosion.
Uniform irradiation system using beam scanning method for cyclotron
International Nuclear Information System (INIS)
JAERI AVF-cyclotron is equipped with an ion beam scanner for large area irradiation. The two-dimensional fluence distribution of ion beam obtained using cellulose triacetate film dosimeter was not uniform. This is resulted from the distortion of excitation current for electromagnet of the scanner. So, the beam scanning condition, i.e., the relation between the ion species, the beam profile and the scanning width, was extremely limited to make a good uniformity. We have developed a beam scanning simulator to get fluence distributions by calculation and then compared the simulated distributions with the measured ones. It was revealed that the both of them are in good agreement and the beam scanning condition to get good uniformity was led by using this simulator. On the basis of these results, the power supply of scanner was improved. A good uniformity of beam distribution was available. (author)
75 FR 34654 - Uniformed Services Accounts and Death Benefits
2010-06-18
... the Internal Revenue Code (26 U.S.C. 401(k)). Uniformed Services Accounts/Death Benefits--Agency's New... particular, the Agency, which has created a new optical character recognition (OCR) Form TSP-3,...
Calculating Method of Moments Uniform Bin Width Histograms
James S. Weber
2016-01-01
A clear articulation of Method of Moments (MOM) Histograms is instructive and has waited 121 years since 1895. Also of interest are enabling uniform bin width (UBW) shape level sets. Mean-variance MOM uniform bin width frequency and density histograms are not unique, however ranking them by histogram skewness compared to data skewness helps. Although theoretical issues rarely take second place to calculations, here calculations based on shape level sets are central and challenge uncritically ...
Uniform large-area thermionic cathode for SCALPEL
Katsap, Victor; Sewell, Peter B.; Waskiewicz, Warren K.; Zhu, Wei
1999-11-01
An electron beam lithography tool, which employs the SCALPEL technique, requires an extremely uniform beam to illuminate the scattering Mask, with the cathode operating in the temperature limited mode. It has been previously shown that LaB6 cathodes are not stable in this mode of operation. We have explored the possibility of implementing refined Tantalum-based emitters in the SCALPEL source cathode, and have developed large-area flat cathodes featuring suitably high emission uniformity under temperature limited operation.
On random flights with non-uniformly distributed directions
De Gregorio, Alessandro
2011-01-01
This paper deals with a new class of random flights $\\underline{\\bf X}_d(t),t>0,$ defined in the real space $\\mathbb{R}^d, d\\geq 2,$ characterized by non-uniform probability distributions on the multidimensional sphere. These random motions differ from similar models appeared in literature which take directions according to the uniform law. The family of angular probability distributions introduced in this paper depends on a parameter $\
Polyelectrolytes polarization in non-uniform electric fields
Farahpour, Farnoush; Varnik, Fathollah; Ejtehadi, Mohammad Reza
2014-01-01
Stretching dynamics of polymers in microfluidics is of particular interest for polymer scientists. As a charged polymer, a polyelectrolyte can be deformed from its coiled equilibrium configuration to an extended chain by applying uniform or non-uniform electric fields. By means of hybrid lattice Boltzmann-molecular dynamics simulations, we investigate how the condensed counterions around the polyelectrolyte contribute to the polymer stretching in inhomogeneous fields. As an application, we di...
Improving Random Walk Estimation Accuracy with Uniform Restarts
Avrachenkov, Konstantin; Ribeiro, Bruno; Towsley, Don
2010-01-01
This work proposes and studies the properties of a hybrid sampling scheme that mixes independent uniform node sampling and random walk (RW)-based crawling. We show that our sampling method combines the strengths of both uniform and RW sampling while minimizing their drawbacks. In particular, our method increases the spectral gap of the random walk, and hence, accelerates convergence to the stationary distribution. The proposed method resembles PageRank but unlike PageRank preserves time-rever...
Vibrating Breakup of Jet for Uniform Metal Droplets
Institute of Scientific and Technical Information of China (English)
Shengdong GAO; Yingxue YAO; Chengsong CUI
2007-01-01
Uniform droplet formation from capillary stream breakup provides promising opportunities for many applications such as solder balls manufacturing, circuit board printing and rapid prototype manufacturing. In this study an apparatus capable of making monosize metal spheres by vibrating breakup has been developed. The droplets were electrically charged to avoid collision and merging with one another during flight. As a result, uniformly sized tin powders (180μm in diameter) were obtained after cooling and solidification.
Harmonic measure and approximation of uniformly rectifiable sets
Bortz, Simon; Hofmann, Steve
2015-01-01
Let $E\\subset \\mathbb{R}^{n+1}$, $n\\ge 1$, be a uniformly rectifiable set of dimension $n$. We show $E$ that has big pieces of boundaries of a class of domains which satisfy a 2-sided corkscrew condition, and whose connected components are all chord-arc domains (with uniform control of the various constants). As a consequence, we deduce that $E$ has big pieces of sets for which harmonic measure belongs to weak-$A_\\infty$
Automatic Sampling with the Ratio-of-uniforms Method
Leydold, Josef
1999-01-01
Applying the ratio-of-uniforms method for generating random variates results in very efficient, fast and easy to implement algorithms. However parameters for every particular type of density must be precalculated analytically. In this paper we show, that the ratio-of-uniforms method is also useful for the design of a black-box algorithm suitable for a large class of distributions, including all with log-concave densities. Using polygonal envelopes and squeezes results in an algorithm that is ...
Flow in pipes with non-uniform curvature and torsion
Gammack, David; Hydon, Peter E.
2001-01-01
This paper describes steady and unsteady flows in pipes with small, slowly varying curvature and torsion. Four new pipe shapes are studied, using Germano's extension of the Dean equations. Analytic and numerical solutions are obtained for flows driven by a steady pressure gradient. Oscillatory flows in pipes with non-uniform curvature are obtained by numerical methods. The effects of the non-uniformities in curvature and torsion are discussed, with particular reference to wall shear stress.
Uniformly Most Powerful Invariant Test and Its Application
Institute of Scientific and Technical Information of China (English)
ZHANG Shuang-lin; SHA Qui-ying; ZHOU Wen-hai
2001-01-01
The authors consider the uniformly most powerful invariant test of the testing problems (Ⅰ)H0: μ′∑-1μ ≥ C H1: μ＇∑-1μ ＜ C and(Ⅱ) H00: ≥ C H11: ＜C under m-dimensional normal population Nm (μ, ∑ ) and normal linear model ( Y, Xβ, σ2 ) respectively.Furthermore, an application of the uniformly most powerful invariant test is given.
Effects of a uniform acceleration on atom-field interactions
Marino, Jamir; Passante, Roberto; Rizzuto, Lucia; Spagnolo, Salvatore
2014-01-01
We review some quantum electrodynamical effects related to the uniform acceleration of atoms in vacuum. After discussing the energy level shifts of a uniformly accelerated atom in vacuum, we investigate the atom-wall Casimir-Polder force for accelerated atoms, and the van der Waals/Casimir-Polder interaction between two accelerated atoms. The possibility of detecting the Unruh effect through these phenomena is also discussed in detail.
Statistical Mechanics Approach for Uniform and Non-uniform Fluid with Hard Core and Interaction Tail
Institute of Scientific and Technical Information of China (English)
ZHOU Shi-Qi; CHEN Hong; LING Si-Li; XIANG Xian-Wei; ZHANG Xiao-Qi
2003-01-01
One recently proposed self-consistent hard sphere bridge functional was combined with an exponential function exp(-cr) and a re-normalized indirect correlation function to construct the bridge function for fluid with hard core and interaction tail. In the present approach, the adjustable parameter α was determined by the thermodynamic consistency realized on the compressibility modulus, the re-normalization of the indirect correlation function was realized by a modified Mayer function with the interaction potential replaced by the perturbative part of the interaction potential. As an example, the present bridge function was combined with the Ornstein-Zernike (OZ) equation to predict structure and thermodynamics properties in very good agreement with the simulation data available for Lennard-Jones (L J). Based on the universality principle of the free energy density functional and the test particle trick, the numerical solution of the OZ equation was employed to construct the first order direct correlation function of the non-uniform fluid as a functional of the density distribution by means of the indirect correlation function. In the framework of the density functional theory, the numerically obtained functional predicted the density distribution of LJ fluid confined in two planar hard walls that is in good agreement with the simulation data.
Directory of Open Access Journals (Sweden)
Pavuluri Srinivasu
2011-01-01
Full Text Available Development of new counter electrode materials is vital for commercialization of efficient dye-sensitized solar cells (DSCs process. Research on DSCs has been focused mainly on using platinum as counter electrode, which makes them expensive. In this paper, we report DSCs fabricated with high surface area mesoporous carbon thin film with uniform spherical particles as counter electrode. An overall light-to-electricity efficiency as high as 7.6% has been achieved under illumination of air mass (AM 1.5 sunlight (100 mW/cm2. In comparison with activated carbon, high surface area mesoporous carbon shows superior performance. Our results show that mesoporous carbon with high specific surface area and uniform pore size distribution proved to be better efficient electrode material for DSCs.
Rips complexes and covers in the uniform category
Brodskiy, N; Labuz, B; Mitra, A
2007-01-01
Berestovskii and Plaut introduced a theory of covers for uniform spaces generalizing their work for topological groups. The class of uniform spaces for which their theory works well are so-called coverable spaces. In their approach composition of covers may not be a cover and it is difficult to determine if a particular compact space is coverable. Part of the problem is that they generalize only regular covers in topology and those may not be preserved by compositions. In this paper we introduce covers for uniform spaces by expanding the concept of generalized paths of Krasinkiewicz and Minc. We use paths in Rips complexes and their homotopy classes possess a natural uniform structure. Applying Rips complexes leads to a natural class of uniform spaces for which our theory of covers works as well as the classical one, namely the class of uniformly joinable spaces. In the case of metric continua (compact and connected metric spaces) that class is identical with pointed 1-movable spaces, a well-understood class ...
Uniformity of fuel target implosion in Heavy Ion Fusion
Kawata, S; Suzuki, T; Karino, T; Barada, D; Ogoyski, A I; Ma, Y Y
2015-01-01
In inertial confinement fusion the target implosion non-uniformity is introduced by a driver beams' illumination non-uniformity, a fuel target alignment error in a fusion reactor, the target fabrication defect, et al. For a steady operation of a fusion power plant the target implosion should be robust against the implosion non-uniformities. In this paper the requirement for the implosion uniformity is first discussed. The implosion uniformity should be less than a few percent. A study on the fuel hotspot dynamics is also presented and shows that the stagnating plasma fluid provides a significant enhancement of vorticity at the final stage of the fuel stagnation. Then non-uniformity mitigation mechanisms of the heavy ion beam (HIB) illumination are also briefly discussed in heavy ion inertial fusion (HIF). A density valley appears in the energy absorber, and the large-scale density valley also works as a radiation energy confinement layer, which contributes to a radiation energy smoothing. In HIF a wobbling he...
Cherokee Culture and School Achievement.
Brown, Anthony D.
1980-01-01
Compares the effect of cooperative and competitive behaviors of Cherokee and Anglo American elementary school students on academic achievement. Suggests changes in teaching techniques and lesson organization that might raise academic achievement while taking into consideration tribal traditions that limit scholastic achievement in an…
Cpuf: Chirped-Pulse Microwave Spectroscopy in Pulsed Uniform Supersonic Flows
Suits, Arthur; Abeysekera, Chamara; Zack, Lindsay N.; Joalland, Baptiste; Ariyasingha, Nuwandi M.; Park, Barratt; Field, Robert W.; Sims, Ian
2015-06-01
Chirped-pulse Fourier-transform microwave spectroscopy has stimulated a resurgence of interest in rotational spectroscopy owing to the dramatic reduction in spectral acquisition time it enjoys when compared to cavity-based instruments. This suggests that it might be possible to adapt the method to study chemical reaction dynamics and even chemical kinetics using rotational spectroscopy. The great advantage of this would be clear, quantifiable spectroscopic signatures for polyatomic products as well as the possibility to identify and characterize new radical reaction products and transient intermediates. To achieve this, however, several conditions must be met: 1) products must be thermalized at low temperature to maximize the population difference needed to achieve adequate signal levels and to permit product quantification based on the rotational line strength; 2) a large density and volume of reaction products is also needed to achieve adequate signal levels; and 3) for kinetics studies, a uniform density and temperature is needed throughout the course of the reaction. These conditions are all happily met by the uniform supersonic flow produced from a Laval nozzle expansion. In collaboration with the Field group at MIT we have developed a new instrument we term a CPUF (Chirped-pulse/Uniform Flow) spectrometer in which we can study reaction dynamics, photochemistry and kinetics using broadband microwave and millimeter wave spectroscopy as a product probe. We will illustrate the performance of the system with a few examples of photodissociation and reaction dynamics, and also discuss a number of challenges unique to the application of chirped-pulse microwave spectroscopy in the collisional environment of the flow. Future directions and opportunities for application of CPUF will also be explored.
Highly uniform hole spacing micro brushes based on aligned carbon nanotube arrays
Yang, Zhi; Zhu, Xingzhong; Huang, Xiaolu; Cheng, Yingwu; Liu, Yun; Geng, Huijuan; Wu, Yue; Su, Yanjie; Wei, Hao; Zhang, Yafei
2013-11-01
Highly uniform hole spacing micro brushes were fabricated based on aligned carbon nanotube (CNT) arrays synthesized by chemical vapor deposition method with the assistance of anodic aluminum oxide (AAO) template. Different micro brushes from CNT arrays were constructed on silicon, glass, and polyimide substrates, respectively. The micro brushes had highly uniform hole spacing originating from the regularly periodic pore structure of AAO template. The CNT arrays, serving as bristles, were firmly grafted on the substrates. The brushes can easily clean particles with scale of micrometer on the surface of silicon wafer and from the narrow spaces between the electrodes in a series of cleaning experiments. The results show the potential application of the CNT micro brushes as a cleaning tool in microelectronics manufacture field.
Elastic Wave Propagation Simulation in Heterogeneous Anisotropic Media on Non-uniform Grids
Institute of Scientific and Technical Information of China (English)
孙卫涛; 杨慧珠
2004-01-01
A finite-difference method with spatially non-uniform grids was developed to simulate elastic wave propagation in heterogeneous anisotropic media. The method is very simple and requires less compution time. Complicated geometric structures, such as low-velocity layers, cased boreholes and nonplanar interfaces, are treated with fine non-uniform grids. Unlike the multi-grid scheme, this method does not require interpolation between the fine and coarse grids and all grids are computed in the same spatial iteration. Planar or nonplanar surfaces including underground lens and cased boreholes are easily treated in a way similar to regular grid points. The Higdon's absorbing boundary condition was used to eliminate boundary reflections. Numerical simulations show that the method has satisfactory stability and accuracy.The proposed scheme more efficiently simulates wave propagation in heterogeneous anisotropic media than conventional methods using regular rectangular grids of equal accuracy.
Radiometric calibration of frame transfer CCD camera with uniform source system
Zhou, Jiankang; Shi, Rongbao; Chen, Yuheng; Zhou, Yuying; Shen, Weimin
2010-08-01
This paper presents a radiometric calibration method based on visibility function and uniform source system. The uniform system is mainly comprised of an integrating sphere and a monitoring silicon detector. The current of the silicon detector with a visibility function filter corresponds to the luminance at the exit port of integrating sphere through standard luminance meter transfer. The radiance at the camera entrance pupil is calculated for different solar zenith angles and Earth surface albedos by the MODTRAN atmospheric code. To simplify the calibration process, the radiance at its entrance pupil is integrated by visibility function. The shift smear of the frame transfer CCD is removed by the radiometric calibration and the amending ratio factor is introduced in the retrieving methods. The imaging experiment verifies the reliability of the calibration method and retrieves good quality image.
A precise model of LED lighting and its application in uniform illumination system
Institute of Scientific and Technical Information of China (English)
WU Feng-tie; HUANG Qi-lu
2011-01-01
Optical models directly effect the irradiance distribution of observed surface.Traditionally,approximate Lambertian models are widely used in designing the light-emitting diodes(LED) arrays in spite of their errors compared with the experimental data.But now a novel LED optical model for uniform illumination system has been proposed,in which the curvefitting technique is used to reduce the inherited errors and modify those previous models.The points from the curve of the LED light intensity are adopted,and a spline curve is designed for fitting,which obtains the revised mode.To verify its feasibility,we apply the new model in a 4 × 4 array design.The results show that compared with the approximate Lambertian,the light intensity distribution produced by the fitting model is more uniform and intense,as is expected.
A method for real time detecting of non-uniform magnetic field
Marusenkov, Andriy
2015-04-01
The principle of measuring magnetic signatures for observing diverse objects is widely used in Near Surface work (unexploded ordnance (UXO); engineering & environmental; archaeology) and security and vehicle detection systems as well. As a rule, the magnitude of the signals to be measured is much lower than that of the quasi-uniform Earth magnetic field. Usually magnetometers for these purposes contain two or more spatially separated sensors to estimate the full tensor gradient of the magnetic field or, more frequently, only partial gradient components. The both types (scalar and vector) of magnetic sensors could be used. The identity of the scale factors and proper alignment of the sensitivity axes of the vector sensors are very important for deep suppression of the ambient field and detection of weak target signals. As a rule, the periodical calibration procedure is used to keep matching sensors' parameters as close as possible. In the present report we propose the technique for detection magnetic anomalies, which is almost insensitive to imperfect matching of the sensors. This method based on the idea that the difference signals between two sensors are considerably different when the instrument is rotated or moved in uniform and non-uniform fields. Due to the misfit of calibration parameters the difference signal observed at the rotation in the uniform field is similar to the total signal - the sum of the signals of both sensors. Zero change of the difference and total signals is expected, if the instrument moves in the uniform field along a straight line. In contrast, the same move in the non-uniform field produces some response of each of the sensors. In case one measures dB/dx and moves along x direction, the sensors signals is shifted in time with the lag proportional to the distance between sensors and the speed of move. It means that the difference signal looks like derivative of the total signal at move in the non-uniform field. So, using quite simple
Students' Achievement Goals, Learning-Related Emotions and Academic Achievement
Directory of Open Access Journals (Sweden)
Marko eLüftenegger
2016-05-01
Full Text Available In the present research, the recently proposed 3x2 model of achievement goals is tested and associations with achievement emotions and their joint influence on academic achievement are investigated. The study was conducted with 388 students using the 3x2 Achievement Goal Questionnaire including the six proposed goal constructs (task-approach, task-avoidance, self-approach, self-avoidance, other-approach, other-avoidance and the enjoyment and boredom scales from the Achievement Emotion Questionnaire. Exam grades were used as an indicator of academic achievement. Findings from CFAs provided strong support for the proposed structure of the 3x2 achievement goal model. Self-based goals, other-based goals and task-approach goals predicted enjoyment. Task-approach goals negatively predicted boredom. Task-approach and other-approach predicted achievement. The indirect effects of achievement goals through emotion variables on achievement were assessed using bias-corrected bootstrapping. No mediation effects were found. Implications for educational practice are discussed.
An Applied Method for Designing Maximally Decimating Non-uniform Filter Banks
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Assembling individual line phase filters to form a multi-channel filter bank allows the synthesis filter to be similar to corresponding analysis filters, and the design calculation can be simple. The appropriate relations between synthesis filters and analysis filters eliminate most aliasing resulting from decimation in non-uniform maximally decimating filter banks, and LS algorithm and Remez algorithm are used to optimize the composite character. This design method can achieve approximate Perfect-Reconstruction. An example is given in which the general parameter filters with approximate line phase are used as units of a filter bank.
An effect of dummy cathode on thickness uniformity in electroforming process
Directory of Open Access Journals (Sweden)
Chul-Woo Park
2014-01-01
Full Text Available This study examines the solution for one of the most difficult problems of electroforming process “thickness deviation”. As an effective solution, an auxiliary electrode (dummy cathode is considered. Generally, the thickness of an edge plating area is almost twice the center area or greater. An auxiliary electrode (intentionally attached dummy cathode has helped to achieve more uniform thickness of the electroformed-nickel layer by preventing excessive electric charge. In addition, computer-aided analysis was performed to determine the optimal condition of electroforming process and to confirm the experimental result.
Linear Uniform Receptiveness in a Pi-Calculus with Location Failures
DEFF Research Database (Denmark)
Hüttel, Hans; Garm Nielsen, Johannes; Finderup, Peter;
2010-01-01
failures. In this paper we extend the notion of receptiveness to DpiF and give sound characterizations of the property of linear uniform receptiveness in DpiF in the form of two type systems. Our first type system ensures receptiveness, the property that no pending output will ever be left unattended. We...... achieve this by ensuring linearity and by ensuring that the input and output remain at the same location, such that location failure will effectively remove either both or none. Our second type system allows for migration but ensures that input capabilities remain within locations which are hidden from...... the context and thus not subject to failures....
Taha, T. J.; Thakur, D. B.; Van der Meer, T. H.
2012-11-01
In this work, heat transfer surface modification and heat transfer measurement technique is developed. Heat transfer investigation was aimed to study the effect of carbon nano fibers (extremely high thermal conductive material) on the enhancement level in heat transfer. Synthesis of these carbon nano structures is achieved using thermal catalytic chemical vapor deposition process (TCCVD) on a 50 μm pure nickel (Ni270) wire. The micro wire samples covered with CNF layers were subjected to a uniform flow from a nozzle. Heat transfer measurement was achieved by a controlled heat dissipation through the micro wire to attain a constant temperature during the flow. This measurement technique is adopted from hot wire anemometry calibration method. Synthesis of carbon nano structures, heat transfer surface characterization and measurement technique are evaluated. Preliminary results indicate that an average enhancement in Nusselt Number of 17% is achieved.
Rabin
2000-10-01
It is commonly assumed that the cooling-rate along the microslide of a directional solidification stage is uniformly distributed, an assumption which is typically applied in low cooling-rates studies. A new directional solidification stage has recently been presented, which is specified to achieve high cooling-rates of up to 1.8 x 104 degrees C min-1, where cooling-rates are still assumed to be uniformly distributed. The current study presents a closed-form solution to the temperature distribution and to the cooling-rate in the microslide. Thermal analysis shows that the cooling-rate is by no means uniformly distributed and can vary by several hundred percent along the microslide in some cases. Therefore, the mathematical solution presented in this study is essential for experimental planning of high cooling-rate experiments.
Uniformity of dielectric barrier discharges using mesh electrodes
Ye, Qizheng; Wu, Yunfei; Li, Xingwang; Chen, Tian; Shao, Guiwei
2012-12-01
In this paper, the uniformities of dielectric barrier discharges (DBDs) produced by different mesh electrodes are studied. If the aperture of the mesh electrode is long enough, the discharge spots are periodic. If the aperture is smaller than 0.5 mm, the discharge spots will be distributed randomly and even more densely than when produced by a planar electrode. Because the evaluation of the uniformity of the DBD, which consists of a large number of microdischarges, is different from that of a glow DBD or a Townsend DBD, the coefficient of variation (CV) of the gray level distribution of the discharge light emission is used to describe the uniformity of the DBD. The smaller the value of CV, the more uniform is the discharge. The experimental results show that the uniformity of the DBD produced by some mesh electrodes is even better than that by a planar electrode if the aperture of the mesh electrode is small enough. On the other hand, a new dimensionless scale invariant (h), which includes the combined effect of the aperture and the normalized change rate of the field strength of the avalanche head, is presented to analyze the physical mechanisms leading to a relatively uniform DBD according to the condition of the slow development of many avalanches at a low electric field. The calculated results show that the variation trend of h for different mesh electrodes is almost the same as that of the CV. This means that the dimensionless scale invariant h can be used to study the discharge uniformity.
Developable algebraic surfaces
Institute of Scientific and Technical Information of China (English)
CHEN Dongren; WANG Guojin
2004-01-01
An algebraic surface can be defined by an implicit polynomial equation F(x,y,z)=0. In this paper, general characterizations of developable algebraic surfaces of arbitrary degree are presented. Using the shift operators of the subscripts of Bézier ordinates, the uniform apparent discriminants of developable algebraic surfaces to their Bézier ordinates are given directly. To degree 2 algebraic surfaces, which are widely used in computer aided geometric design and graphics, all possible developable surface types are obtained. For more conveniently applying algebraic surfaces of high degree to computer aided geometric design, the notion of ε-quasi-developable surfaces is introduced, and an example of using a quasi-developable algebraic surface of degree 3 to interpolate three curves of degree 2 is given.
Characterization of uniform scanning proton beams with analytical models
Demez, Nebi
Tissue equivalent phantoms have an important place in radiation therapy planning and delivery. They have been manufactured for use in conventional radiotherapy. Their tissue equivalency for proton beams is currently in active investigation. The Bragg-Kleeman rule was used to calculate water equivalent thickness (WET) for available tissue equivalent phantoms from CIRS (Norfolk, VA, USA). WET's of those phantoms were also measured using proton beams at Hampton University Proton Therapy Institute (HUPTI). WET measurements and calculations are in good agreement within ˜1% accuracy except for high Z phantoms. Proton beams were also characterized with an analytical proton dose calculation model, Proton Loss Model (PLM) [26], to investigate protons interactions in water and those phantoms. Depth-dose and lateral dose profiles of protons in water and in those phantoms were calculated, measured, and compared. Water Equivalent Spreadness (WES) was also investigated for those phantoms using the formula for scattering power ratio. Because WES is independent of incident energy of protons, it is possible to estimate spreadness of protons in different media by just knowing WES. Measurements are usually taken for configuration of the treatment planning system (TPS). This study attempted to achieve commissioning data for uniform scanning proton planning with analytical methods, PLM, which have been verified with published measurements and Monte Carlo calculations. Depth doses and lateral profiles calculated by PLM were compared with measurements via the gamma analysis method. While gamma analysis shows that depth doses are in >90% agreement with measured depth doses, the agreement falls to PLM data were imported into the TPS (PLM-TPS). PLM-TPS was tested with different patient cases. The PLM-TPS treatment plans for 5 prostate cases show acceptable agreement. The Planning Treatment Volume (PTV) coverage was 100 % with PLM-TPS except for one case in which the coverage is 99%. The
International Nuclear Information System (INIS)
A compact, all-permanent-magnet single-frequency ECR ion source with a large uniformly distributed ECR plasma volume has been designed and is presently under construction at the Oak Ridge National Laboratory (ORNL). The central region of the field is designed to achieve a flat-field (constant mod-B) which extends over the length of the central field region along the axis of symmetry and radially outward to form a uniformly distributed ECR plasma volume. The magnetic field design strongly contrasts with those used in conventional ECR ion sources where the central field regions are approximately parabolic and the consequent ECR zones are surfaces. The plasma confinement magnetic field mirror has a mirror ratio Bmax/BECR of slightly greater than two. The source is designed to operate at a nominal RF frequency of 6 GHz. The central flat magnetic field region can be easily adjusted by mechanical means to tune the source to the resonant conditions within the limits of 5.5 to 6.8 GHz. The RF injection system is broadband to ensure excitation of transverse electric (TE) modes so that the RF power is largely concentrated in the resonant plasma volume which lies along and surrounds the axis of symmetry of the source. Because of the much larger ECR zone, the probability for absorption of microwave power is dramatically increased thereby increasing the probability for acceleration of electrons, the electron temperature of the plasma and, consequently, the hot electron population within the plasma volume of the source. The creation of an ECR volume rather than a surface is commensurate with higher charge states and higher beam intensities within a particular charge state
Achieving monospermy or preventing polyspermy?
Directory of Open Access Journals (Sweden)
Dale B
2016-06-01
Full Text Available Brian Dale Centre for Assisted Fertilization, Naples, Italy Abstract: Images of sea urchin oocytes with hundreds of spermatozoa attached to their surface have fascinated scientists for over a century and led to the idea that oocytes have evolved mechanisms to allow the penetration of one spermatozoon while repelling supernumerary spermatozoa. Popular texts have extrapolated this concept, to the mammals and amphibians, and in many cases to include all the Phyla. Here, it is argued that laboratory experiments, using sea urchin oocytes deprived of their extracellular coats and inseminated at high densities, are artifactual and that the experiments leading to the idea of a fast block to polyspermy are flawed. Under natural conditions, the number of spermatozoa at the site of fertilization is extremely low, compared with the numbers generated. The sperm:oocyte ratio is regulated first by dilution in externally fertilizing species and the female reproductive tract in those with internal fertilization, followed by a bottleneck created by the oocytes extracellular coats. In order to progress to the oocyte plasma membrane, the fertilizing spermatozoon must encounter and respond to a correct sequence of signals from the oocytes extracellular coats. Those that do not, are halted in their progression by defective signaling and fall to the wayside. Final success and entry is finely tuned by the spermatozoon anchoring to an actin-rich predetermined site on the plasma membrane. In this review, the variation in the form, function, and number of gametes produced across the animal kingdom and the many ways in which sperm–oocyte interactions are regulated to reduce numbers are discussed. Since in nature, final sperm:oocyte ratios approach unity it would appear that selective pressures have favored the achievement of monospermy, rather than the evolution of polyspermy preventing mechanisms. Keywords: monospermy, natural conditions, polyspermy, laboratory
Erofeev, M. V.; Baksht, E. Kh.; Burachenko, A. G.; Tarasenko, V. F.
2015-09-01
The subject matters in this work are (i) the spatial structure of a volume (diffuse) discharge initiated in atmospheric-pressure air in a heavily nonuniform electric field by nanosecond voltage pulses and (ii) the influence of its plasma on the surface of a plane aluminum anode. It is shown that a diffuse discharge initiated by nanosecond voltage pulses makes it possible to uniformly process the anode's surface in atmospheric-pressure air in contrast to a spark discharge, which results in microcracking, locally changes the surface properties, and thereby degrades the surface.
Investigation of differential surface removal due to electropolishing at JLab
Energy Technology Data Exchange (ETDEWEB)
Marhauser, Frank [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Folkie, James [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Reece, Charles [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
2015-09-01
Surface chemistry carried out for Superconducting Radio Frequency (SRF) cavities such as Buffered Chemical Polishing (BCP) and Electropolishing (EP) aims to uniformly remove the internal surface of a cavity along the entire structure and within each cell from equator to iris in order to obtain an equally etched surface. A uniform removal, however, is not readily achievable due to the complex fluid flow and varying temperatures of the acid mixture, which can lead to differential etching. This needs to be considered when envisaging a certain surface damage removal throughout the interior. The process-specific differential etching influences the target frequency set at the manufacturing stage as well as the field flatness and length of the as-built cavity. We report on analyses of JLab's present EP system using experimental data for six nine-cell cavities that have been processed recently in the frame of the LCLS-II high-Q development plan. In conjunction with numerical simulations, the differential etching and the impact on field flatness is assessed.
Institute of Scientific and Technical Information of China (English)
亚敏; 戴福隆; 谢惠民; 吕坚
2003-01-01
Hole-drilling method is one of the most convenient methods for engineering residual ment data, hole-drilling technique can be used to solve non-uniform residual stress problems, both (MIIHD) for non-uniform residual stress measurement is introduced. Three dimensional finite element model is constructed by ABAQUS to obtain the coefficients for the residual stress calculation.An experimental system including real-time measurement, automatic data processing and residual stresses calculation is established. Two applications for non-uniform in-depth residual stress of surface nanocrystalline material and non-uniform in-plane residual stress of friction stir welding are presented.Experimental results show that MIIHD is effective for both non-uniform in-depth and in-plane residual stress measurements.
Non-uniform sampling of NMR relaxation data
Energy Technology Data Exchange (ETDEWEB)
Linnet, Troels E.; Teilum, Kaare, E-mail: kaare.teilum@bio.ku.dk [University of Copenhagen, SBiNLab and the Linderstrøm-Lang Centre for Protein Science, Department of Biology (Denmark)
2016-02-15
The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of {sup 15}N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition reconstructs the non-uniform sampled spectra with high accuracy. For two of the four analyzed datasets, a coverage of only 20 % results in essentially the same results as the fully sampled data. As exemplified by other data, such a low coverage is in general not enough to produce reliable results. We find that a coverage level not compromising the final results can be estimated by recording a single full two-dimensional spectrum and reducing the spectrum quality in silico.
Non-uniform sampling of NMR relaxation data
International Nuclear Information System (INIS)
The use of non-uniform sampling of NMR spectra may give significant reductions in the data acquisition time. For quantitative experiments such as the measurement of spin relaxation rates, non-uniform sampling is however not widely used as inaccuracies in peak intensities may lead to errors in the extracted dynamic parameters. By systematic reducing the coverage of the Nyquist grid of 15N Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion datasets for four different proteins and performing a full data analysis of the resulting non-uniform sampled datasets, we have compared the performance of the multi-dimensional decomposition and iterative re-weighted least-squares algorithms in reconstructing spectra with accurate peak intensities. As long as a single fully sampled spectrum is included in a series of otherwise non-uniform sampled two-dimensional spectra, multi-dimensional decomposition reconstructs the non-uniform sampled spectra with high accuracy. For two of the four analyzed datasets, a coverage of only 20 % results in essentially the same results as the fully sampled data. As exemplified by other data, such a low coverage is in general not enough to produce reliable results. We find that a coverage level not compromising the final results can be estimated by recording a single full two-dimensional spectrum and reducing the spectrum quality in silico
The Predictiveness of Achievement Goals
Directory of Open Access Journals (Sweden)
Huy P. Phan
2013-11-01
Full Text Available Using the Revised Achievement Goal Questionnaire (AGQ-R (Elliot & Murayama, 2008, we explored first-year university students’ achievement goal orientations on the premise of the 2 × 2 model. Similar to recent studies (Elliot & Murayama, 2008; Elliot & Thrash, 2010, we conceptualized a model that included both antecedent (i.e., enactive learning experience and consequence (i.e., intrinsic motivation and academic achievement of achievement goals. Two hundred seventy-seven university students (151 women, 126 men participated in the study. Structural equation modeling procedures yielded evidence that showed the predictive effects of enactive learning experience and mastery goals on intrinsic motivation. Academic achievement was influenced intrinsic motivation, performance-approach goals, and enactive learning experience. Enactive learning experience also served as an antecedent of the four achievement goal types. On the whole, evidence obtained supports the AGQ-R and contributes, theoretically, to 2 × 2 model.
The Mechanics of Human Achievement
Duckworth, Angela L.; Eichstaedt, Johannes C.; Ungar, Lyle H.
2015-01-01
Countless studies have addressed why some individuals achieve more than others. Nevertheless, the psychology of achievement lacks a unifying conceptual framework for synthesizing these empirical insights. We propose organizing achievement-related traits by two possible mechanisms of action: Traits that determine the rate at which an individual learns a skill are talent variables and can be distinguished conceptually from traits that determine the effort an individual puts forth. This approach takes inspiration from Newtonian mechanics: achievement is akin to distance traveled, effort to time, skill to speed, and talent to acceleration. A novel prediction from this model is that individual differences in effort (but not talent) influence achievement (but not skill) more substantially over longer (rather than shorter) time intervals. Conceptualizing skill as the multiplicative product of talent and effort, and achievement as the multiplicative product of skill and effort, advances similar, but less formal, propositions by several important earlier thinkers. PMID:26236393
Mathematics Achievement in High- and Low-Achieving Secondary Schools
Mohammadpour, Ebrahim; Shekarchizadeh, Ahmadreza
2015-01-01
This paper identifies the amount of variance in mathematics achievement in high- and low-achieving schools that can be explained by school-level factors, while controlling for student-level factors. The data were obtained from 2679 Iranian eighth graders who participated in the 2007 Trends in International Mathematics and Science Study. Of the…
Effect of non-uniform magnetic field on crystal growth by floating-Zone method in microgravity
Institute of Scientific and Technical Information of China (English)
李凯; 胡文瑞
2001-01-01
The magnetic damping effect of the non-uniform magnetic field on the floating-zone crystal growth process in microgravity is studied by numerical simulation. The results show that the non-uni-form magnetic field with designed configuration can effectively reduce the flow near the free surface and then in the melt zone. At the same time, the designed magnetic field can improve the impurity concen-tration non-uniformity along the solidification interface. The primary principles of the magnetic field con-figuration design are also discussed.
Luminescent Surface Quaternized Carbon Dots
Bourlinos, Athanasios B.
2012-01-10
Thermal oxidation of a salt precursor made from the acid base combination of tris(hydroxymethyl)aminomethane and betaine hydrochloride results in light-emitting surface quaternized carbon dots that are water-dispersible, display anion exchange properties, and exhibit uniform size/surface charge. © 2011 American Chemical Society.
André, Frédéric
2016-05-01
An accurate treatment of non-uniformities is required in many applications involving radiative heat transfer in gaseous media. Usual techniques to handle path non-uniformities rely on simplifying assumptions, such as scaling or correlation of gas spectra. Those approximations are usually accurate but may also fail to provide accurate results, especially when large temperature gradients are considered. The objective of the present work is to show that this problem can be treated rigorously. The proposed method can be applied to any arbitrary narrow band model. It is based on some results from Polynomial Chaos' framework and copulas theory. Although the mathematical derivation may appear sophisticated, applying the method is straightforward. It is shown that adding only one coefficient to any uniform narrow band model (for a simple case involving a non-uniform column discretized into two uniform sub-paths) allows to achieve almost LBL accuracy for radiative heat transfer calculations. The technique is described and applied to some "severe" test cases from the literature.
Surface-enhanced Raman nanodomes
Energy Technology Data Exchange (ETDEWEB)
Choi, Charles J; Xu Zhida; Wu, Hsin-Yu; Liu, Gang Logan; Cunningham, Brian T, E-mail: bcunning@illinois.edu [Department of Electrical and Computer Engineering, Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, IL 61801 (United States)
2010-10-15
We demonstrate a surface-enhanced Raman scattering (SERS) substrate consisting of a closely spaced metal nanodome array fabricated on flexible plastic film. We used a low-cost, large-area replica molding process to produce a two-dimensional periodic array of cylinders that is subsequently overcoated with SiO{sub 2} and silver thin films to form dome-shaped structures. Finite element modeling was used to investigate the electromagnetic field distribution of the nanodome array structure and the effect of the nanodome separation distance on the electromagnetic field enhancement. The SERS enhancement from the nanodome array substrates was experimentally verified using rhodamine 6G as the analyte. With a separation distance of 17 nm achieved between adjacent domes using a process that is precisely controlled during thin film deposition, a reproducible SERS enhancement factor of 1.37 x 10{sup 8} was demonstrated. The nanoreplica molding process presented in this work allows for simple, low-cost, high-throughput fabrication of uniform nanoscale SERS substrates over large surface areas without the requirement for high resolution lithography or defect-free deposition of spherical microparticle monolayer templates.
Attribution theory in science achievement
Craig, Martin
Recent research reveals consistent lags in American students' science achievement scores. Not only are the scores lower in the United States compared to other developed nations, but even within the United States, too many students are well below science proficiency scores for their grade levels. The current research addresses this problem by examining potential malleable factors that may predict science achievement in twelfth graders using 2009 data from the National Assessment of Educational Progress (NAEP). Principle component factor analysis was conducted to determine the specific items that contribute to each overall factor. A series of multiple regressions were then analyzed and formed the predictive value of each of these factors for science achievement. All significant factors were ultimately examined together (also using multiple regression) to determine the most powerful predictors of science achievement, identifying factors that predict science achievement, the results of which suggested interventions to strengthen students' science achievement scores and encourage persistence in the sciences at the college level and beyond. Although there is a variety of research highlighting how students in the US are falling behind other developing nations in science and math achievement, as yet, little research has addressed ways of intervening to address this gap. The current research is a starting point, seeking to identify malleable factors that contribute to science achievement. More specifically, this research examined the types of attributions that predict science achievement in twelfth grade students.
Uniform integration of gold nanoparticles in PDMS microfluidics with 3D micromixing
SadAbadi, H.; Packirisamy, M.; Wuthrich, R.
2015-09-01
The integration of gold nanoparticles (AuNPs) on the surface of polydimethylsiloxane (PDMS) microfluidics for biosensing applications is a challenging task. In this paper we address this issue by integration of pre-synthesized AuNPs (in a microreactor) into a microfluidic system. This method explored the affinity of AuNPs toward the PDMS surface so that the pre-synthesized particles will be adsorbed onto the channel walls. AuNPs were synthesized inside a microreactor before integration. In order to improve the size uniformity of the synthesized AuNPs and also to provide full mixing of reactants, a 3D-micromixer was designed, fabricated and then integrated with the microreactor in a single platform. SEM and UV/Vis spectroscopy were used to characterize the AuNPs on the PDMS surface.
Sensitivity analysis and study of the mixing uniformity of a microfluidic mixer
Ivorra, Benjamin; Ramos, Ángel M; Santiago, Juan G
2015-01-01
We consider a microfluidic mixer based on hydrodynamic focusing, which is used to initiate the folding process of individual proteins. The folding process is initiated by quickly diluting a local denaturant concentration, and we define mixing time as the time advecting proteins experience a specified to achieve a local drop in denaturant concentration. In previous work, we presented a minimization of mixing time which considered optimal geometry and flow conditions, and achieved a design with a predicted mixing time of 0.10 $\\mu$s. The aim of the current paper is twofold. First, we explore the sensitivity of mixing time to key geometric and flow parameters. In particular, we study the angle between inlets, the shape of the channel intersections, channel widths, mixer depth, mixer symmetry, inlet velocities, working fluid physical properties, and denaturant concentration thresholds. Second, we analyze the uniformity of mixing times as a function of inlet flow streamlines. We find the shape of the intersection,...
Finding the Most Uniform Changes in Vowel Polygon Caused by Psychological Stress
Directory of Open Access Journals (Sweden)
M. Stanek
2015-06-01
Full Text Available Using vowel polygons, exactly their parameters, is chosen as the criterion for achievement of differences between normal state of speaker and relevant speech under real psychological stress. All results were experimentally obtained by created software for vowel polygon analysis applied on ExamStress database. Selected 6 methods based on cross-correlation of different features were classified by the coefficient of variation and for each individual vowel polygon, the efficiency coefficient marking the most significant and uniform differences between stressed and normal speech were calculated. As the best method for observing generated differences resulted method considered mean of cross correlation values received for difference area value with vector length and angle parameter couples. Generally, best results for stress detection are achieved by vowel triangles created by /i/-/o/-/u/ and /a/-/i/-/o/ vowel triangles in formant planes containing the fifth formant F5 combined with other formants.
Uniform convergence of Vapnik--Chervonenkis classes under ergodic sampling
Adams, Terrence M; 10.1214/09-AOP511
2010-01-01
We show that if $\\mathcal{X}$ is a complete separable metric space and $\\mathcal{C}$ is a countable family of Borel subsets of $\\mathcal{X}$ with finite VC dimension, then, for every stationary ergodic process with values in $\\mathcal{X}$, the relative frequencies of sets $C\\in\\mathcal{C}$ converge uniformly to their limiting probabilities. Beyond ergodicity, no assumptions are imposed on the sampling process, and no regularity conditions are imposed on the elements of $\\mathcal{C}$. The result extends existing work of Vapnik and Chervonenkis, among others, who have studied uniform convergence for i.i.d. and strongly mixing processes. Our method of proof is new and direct: it does not rely on symmetrization techniques, probability inequalities or mixing conditions. The uniform convergence of relative frequencies for VC-major and VC-graph classes of functions under ergodic sampling is established as a corollary of the basic result for sets.
New non-linear photovoltaic effect in uniform bipolar semiconductor
Energy Technology Data Exchange (ETDEWEB)
Volovichev, I. [A. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Ac. Proscura St., Kharkov 61085 (Ukraine)
2014-11-21
A linear theory of the new non-linear photovoltaic effect in the closed circuit consisting of a non-uniformly illuminated uniform bipolar semiconductor with neutral impurities is developed. The non-uniform photo-excitation of impurities results in the position-dependant current carrier mobility that breaks the semiconductor homogeneity and induces the photo-electromotive force (emf). As both the electron (or hole) mobility gradient and the current carrier generation rate depend on the light intensity, the photo-emf and the short-circuit current prove to be non-linear functions of the incident light intensity at an arbitrarily low illumination. The influence of the sample size on the photovoltaic effect magnitude is studied. Physical relations and distinctions between the considered effect and the Dember and bulk photovoltaic effects are also discussed.
Influence of Using Parameters on Stirring Uniformity of Mixer
Institute of Scientific and Technical Information of China (English)
LIU Honghai; MA Dengeheng
2011-01-01
Stirring uniformity of mixture depends not only on structural parameters of the mixer,motion parameters, but also to a large extent on the using parameters.Based on the analysis of the structure and working principle of mixer,these factors that affecting mixer performance was studied.The mathematical model of mixer performance characteristics was established by theoretical analysis,which associated with the mechanical structure, motion parameters and using parameters. According to the mathematical model,the effects of the mixer filling rate, stirring time,and other using parameters on the uniformity were studied. In each stirring cycle, the minimum number of revolutions formula for shaft was obtained. In addition,in different filling rates,the relationship between stirring shaft rotation laps and stirring uniformity was obtained too.Finally,full-scale experimental verification was conducted.
Inviscid Uniform Shear Flow past a Smooth Concave Body
Directory of Open Access Journals (Sweden)
Abdullah Murad
2014-01-01
Full Text Available Uniform shear flow of an incompressible inviscid fluid past a two-dimensional smooth concave body is studied; a stream function for resulting flow is obtained. Results for the same flow past a circular cylinder or a circular arc or a kidney-shaped body are presented as special cases of the main result. Also, a stream function for resulting flow around the same body is presented for an oncoming flow which is the combination of a uniform stream and a uniform shear flow. Possible fields of applications of this study include water flows past river islands, the shapes of which deviate from circular or elliptical shape and have a concave region, or past circular arc-shaped river islands and air flows past concave or circular arc-shaped obstacles near the ground.
Formation of Enhanced Uniform Chiral Fields in Symmetric Dimer Nanostructures
Tian, Xiaorui; Sun, Mengtao
2015-01-01
Chiral fields with large optical chirality are very important in chiral molecules analysis, sensing and other measurements. Plasmonic nanostructures have been proposed to realize such super chiral fields for enhancing weak chiral signals. However, most of them cannot provide uniform chiral near-fields close to the structures, which makes these nanostructures not so efficient for applications. Plasmonic helical nanostructures and blocked squares have been proved to provide uniform chiral near-fields, but structure fabrication is a challenge. In this paper, we show that very simple plasmonic dimer structures can provide uniform chiral fields in the gaps with large enhancement of both near electric fields and chiral fields under linearly polarized light illumination with polarization off the dimer axis at dipole resonance. 30 times of volume averaged chiral field enhancement is gotten in the whole gap. Chiral fields with opposite handedness can be obtained simply by changing the polarization to the other side of...
Analysis of distribution uniformity of nodes in wireless sensor networks
Institute of Scientific and Technical Information of China (English)
Zhang Zhenjiang
2007-01-01
Wireless sensor networks have several special characteristics which make against the network coverage, such as shortage of energy, difficulty with energy supply and so on. In order to prolong the lifetime of wireless sensor networks, it is necessary to balance the whole network load. As the energy consumption is related to the situation of nodes, the distribution uniformity must be considered. In this paper, a new model is proposed to evaluate the nodes distribution uniformity by considering some parameters which include compression discrepancy, sparseness discrepancy, self discrepancy, maximum cavity radius and minimum cavity radius. The simulation results show that the presented model could be helpful for measuring the distribution uniformity of nodes scattered randomly in wireless sensor networks.
Uniform distribution of initial states: The physical basis of probability
Zhang Kechen
1990-02-01
For repetitive experiments performed on a deterministic system with initial states restricted to a certain region in phase space, the relative frequency of an event has a definite value insensitive to the preparation of the experiments only if the initial states leading to that event are distributed uniformly in the prescribed region. Mechanical models of coin tossing and roulette spinning and equal a priori probability hypothesis in statistical mechanics are considered in the light of this principle. Probabilities that have arisen from uniform distributions of initial states do not necessarily submit to Kolmogorov's axioms of probability. In the finite-dimensional case, a uniform distribution in phase space either in the coarse-grained sense or in the limit sense can be formulated in a unified way.
Carbides composite surface layers produced by (PTA)
Energy Technology Data Exchange (ETDEWEB)
Tajoure, Meloud, E-mail: Tajoore2000@yahoo.com [MechanicalEng.,HIHM,Gharian (Libya); Tajouri, Ali, E-mail: Tajouri-am@yahoo.com, E-mail: dr.mokhtarphd@yahoo.com; Abuzriba, Mokhtar, E-mail: Tajouri-am@yahoo.com, E-mail: dr.mokhtarphd@yahoo.com [Materials and Metallurgical Eng., UOT, Tripoli (Libya); Akreem, Mosbah, E-mail: makreem@yahoo.com [Industrial Research Centre,Tripoli (Libya)
2013-12-16
The plasma transferred arc technique was applied to deposit a composite layer of nickel base with tungsten carbide in powder form on to surface of low alloy steel 18G2A type according to polish standard. Results showed that, plasma transferred arc hard facing process was successfully conducted by using Deloro alloy 22 plus tungsten carbide powders. Maximum hardness of 1489 HV and minimum dilution of 8.4 % were achieved by using an arc current of 60 A. However, when the current was further increased to 120 A and the dilution increases with current increase while the hardness decreases. Microstructure of the nickel base deposit with tungsten carbide features uniform distribution of reinforcement particles with regular grain shape half - dissolved in the matrix.
Dai, Pengcheng; Xue, Yanming; Wang, Xuebin; Weng, Qunhong; Zhang, Chao; Jiang, Xiangfen; Tang, Daiming; Wang, Xi; Kawamoto, Naoyuki; Ide, Yusuke; Mitome, Masanori; Golberg, Dmitri; Bando, Yoshio
2015-11-01
How to concentrate target molecules on the surface of a SERS substrate is a key problem in the practical application of SERS. Herein, we designed for the first time a pollutant capturing surface enhanced Raman spectroscopy (SERS) substrate, namely porous BN microfibers uniformly decorated with Ag nanoparticles, in which the BN microfibers adsorb pollutants, while the Ag nanoparticles provide SERS activity. This SERS substrate captures pollutants from an aqueous solution completely and accumulates them all on its surface without introducing noise signals. The pores of BN protect the silver particles from aggregation which makes BN/Ag a stable and recyclable SERS substrate. What's more, while the dyes are thoroughly concentrated from a diluted solution, the SERS detection limit is easily enhanced, from 10-6 M to 10-9 M.How to concentrate target molecules on the surface of a SERS substrate is a key problem in the practical application of SERS. Herein, we designed for the first time a pollutant capturing surface enhanced Raman spectroscopy (SERS) substrate, namely porous BN microfibers uniformly decorated with Ag nanoparticles, in which the BN microfibers adsorb pollutants, while the Ag nanoparticles provide SERS activity. This SERS substrate captures pollutants from an aqueous solution completely and accumulates them all on its surface without introducing noise signals. The pores of BN protect the silver particles from aggregation which makes BN/Ag a stable and recyclable SERS substrate. What's more, while the dyes are thoroughly concentrated from a diluted solution, the SERS detection limit is easily enhanced, from 10-6 M to 10-9 M. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05625j
The equivalence between pointwise Hardy inequalities and uniform fatness
Korte, Riikka; Tuominen, Heli
2009-01-01
We prove an equivalence result between the validity of a pointwise Hardy inequality in a domain and uniform capacity density of the complement. This result is new even in Euclidean spaces, but our methods apply in general metric spaces as well. We also present a new transparent proof for the fact that uniform capacity density implies the classical integral version of the Hardy inequality in the setting of metric spaces. In addition, we consider the relations between the above concepts and certain Hausdorff content conditions.