Science.gov

Sample records for account numerical results

  1. Results from Numerical General Relativity

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2011-01-01

    For several years numerical simulations have been revealing the details of general relativity's predictions for the dynamical interactions of merging black holes. I will review what has been learned of the rich phenomenology of these mergers and the resulting gravitational wave signatures. These wave forms provide a potentially observable record of the powerful astronomical events, a central target of gravitational wave astronomy. Asymmetric radiation can produce a thrust on the system which may accelerate the single black hole resulting from the merger to high relative velocity.

  2. Numerical taxonomy on data: Experimental results

    SciTech Connect

    Cohen, J.; Farach, M.

    1997-12-01

    The numerical taxonomy problems associated with most of the optimization criteria described above are NP - hard [3, 5, 1, 4]. In, the first positive result for numerical taxonomy was presented. They showed that if e is the distance to the closest tree metric under the L{sub {infinity}} norm. i.e., e = min{sub T} [L{sub {infinity}} (T-D)], then it is possible to construct a tree T such that L{sub {infinity}} (T-D) {le} 3e, that is, they gave a 3-approximation algorithm for this problem. We will refer to this algorithm as the Single Pivot (SP) heuristic.

  3. Engineering Accountability for Results into Public Education.

    ERIC Educational Resources Information Center

    Lessinger, Leon

    "Accountability" is a classical term in management theory, but new in education. It is the product of the process of performance contracting, in which a public authority grants money to a local educational agency to contract with private enterprise to achieve specific goals within a specific period for specific costs. This process can be…

  4. Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis

    NASA Astrophysics Data System (ADS)

    Gabriele, Papadia; Antonio, Del Prete; Alfredo, Anglani

    2010-06-01

    The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time [1]. Accurate simulation results are fundamental for the tooling and the product designs. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Many factors can influence the final simulation results and many studies have been carried out about materials [2], yield criteria [3] and plastic deformation [4,5], process parameters [6] and their optimization. In order to develop a reliable hydromechanical deep drawing (HDD) numerical model the authors have been worked out specific activities based on the evaluation of the effective stiffness of the blankholder structure [7]. In this paper after an appropriate tuning phase of the blankholder force distribution, the experimental activity has been taken into account to improve the accuracy of the numerical model. In the first phase, the effective capability of the blankholder structure to transfer the applied load given by hydraulic actuators to the blank has been explored. This phase ended with the definition of an appropriate subdivision of the blankholder active surface in order to take into account the effective pressure map obtained for the given loads configuration. In the second phase the numerical results obtained with the developed subdivision have been compared with the experimental data of the studied model. The numerical model has been then improved, finding the best solution for the blankholder force distribution.

  5. Numerical simulations of catastrophic disruption: Recent results

    NASA Astrophysics Data System (ADS)

    Benz, W.; Asphaug, E.; Ryan, E. V.

    1994-12-01

    Numerical simulations have been used to study high velocity two-body impacts. In this paper, a two-dimensional Largrangian finite difference hydro-code and a three-dimensional smooth particle hydro-code (SPH) are described and initial results reported. These codes can be, and have been, used to make specific predictions about particular objects in our solar system. But more significantly, they allow us to explore a broad range of collisional events. Certain parameters (size, time) can be studied only over a very restricted range within the laboratory; other parameters (initial spin, low gravity, exotic structure or composition) are difficult to study at all experimentally. The outcomes of numerical simulations lead to a more general and accurate understanding of impacts in their many forms.

  6. Aiming for Accountability: Lessons Learned from Eight States. Reaching Results.

    ERIC Educational Resources Information Center

    Harvard Family Research Project, Cambridge, MA.

    Interest is growing in planning and implementing new systems of holding child and family services accountable for results. The Results-Based Accountability (RBA) Project at the Harvard Family Research Project (HFRP) has supported and built upon recent state efforts to develop these new accountability systems for child and family services. This…

  7. Numerical Results of 3-D Modeling of Moon Accumulation

    NASA Astrophysics Data System (ADS)

    Khachay, Yurie; Anfilogov, Vsevolod; Antipin, Alexandr

    2014-05-01

    For the last time for the model of the Moon usually had been used the model of mega impact in which the forming of the Earth and its sputnik had been the consequence of the Earth's collision with the body of Mercurial mass. But all dynamical models of the Earth's accumulation and the estimations after the Pb-Pb system, lead to the conclusion that the duration of the planet accumulation was about 1 milliard years. But isotopic results after the W-Hf system testify about a very early (5-10) million years, dividing of the geochemical reservoirs of the core and mantle. In [1,2] it is shown, that the account of energy dissipating by the decay of short living radioactive elements and first of all Al26,it is sufficient for heating even small bodies with dimensions about (50-100) km up to the iron melting temperature and can be realized a principal new differentiation mechanism. The inner parts of the melted preplanets can join and they are mainly of iron content, but the cold silicate fragments return to the supply zone and additionally change the content of Moon forming to silicates. Only after the increasing of the gravitational radius of the Earth, the growing area of the future Earth's core can save also the silicate envelope fragments [3]. For understanding the further system Earth-Moon evolution it is significant to trace the origin and evolution of heterogeneities, which occur on its accumulation stage.In that paper we are modeling the changing of temperature,pressure,velocity of matter flowing in a block of 3d spherical body with a growing radius. The boundary problem is solved by the finite-difference method for the system of equations, which include equations which describe the process of accumulation, the Safronov equation, the equation of impulse balance, equation Navier-Stocks, equation for above litho static pressure and heat conductivity in velocity-pressure variables using the Businesque approach.The numerical algorithm of the problem solution in velocity

  8. Great Expectations: Holding Ourselves and Our Schools Accountable for Results

    ERIC Educational Resources Information Center

    US Department of Education, 2009

    2009-01-01

    This report traces the evolution of education in America from a privilege for a few to a necessity for all, and discusses the need to promote high standards and accountability in the classroom. Eight specific areas are highlighted: (1) "A History of Expectations" traces the history of the public school in America and its shift in the 20th century…

  9. Prandtl's Equations: Numerical Results about Singularity Formation and a New Numerical Method

    NASA Astrophysics Data System (ADS)

    Puppo, Gabriella

    1990-01-01

    In this work, new numerical results about singularity formation for unsteady Prandtl's equations are presented. Extensive computations with a Lax Wendroff scheme for the impulsively started circular cylinder show that the gradient of the velocity becomes infinite in a finite time. The accuracy and the simplicity of the Lax Wendroff scheme allow us to couple the resolution given by second order accuracy in space with the detail of an extremely fine grid. Thus, while these computations confirm previous results about singularity formation (Van Dommelen and Shen, Cebeci, Wang), they differ in other respects. In fact the peak in the velocity gradient appears to be located upstream of the region of reversed flow and away from the zero vorticity line. Some analytic arguments are also presented to support these conclusions, independently of the computations. In the second part of this work another new numerical method to solve the unsteady Prandtl equations is proposed. This numerical scheme derives from Chorin's Vortex Sheet method. The equations are also solved with operator splitting, but, unlike Chorin's, this scheme is deterministic. This feature is achieved using a Lagrangian particle formulation for the convective step and solving the diffusion step with finite differences on an Eulerian mesh. Finally, a numerical convergence proof is presented.

  10. Numerical Results of Earth's Core Accumulation 3-D Modelling

    NASA Astrophysics Data System (ADS)

    Khachay, Yurie; Anfilogov, Vsevolod

    2013-04-01

    For a long time as a most convenient had been the model of mega impact in which the early forming of the Earth's core and mantle had been the consequence of formed protoplanet collision with the body of Mercurial mass. But all dynamical models of the Earth's accumulation and the estimations after the Pb-Pb system, lead to the conclusion that the duration of the planet accumulation was about 1 milliard years. But isotopic results after the W-Hf system testify about a very early (5-10) million years, dividing of the geochemical reservoirs of the core and mantle. In [1,3] it is shown, that the account of energy dissipating by the decay of short living radioactive elements and first of all Al,it is sufficient for heating even small bodies with dimensions about (50-100) km up to the iron melting temperature and can be realized a principal new differentiation mechanism. The inner parts of the melted preplanets can join and they are mainly of iron content, but the cold silicate fragments return to the supply zone. Only after the increasing of the gravitational radius, the growing area of the future core can save also the silicate envelope fragments. All existing dynamical accumulation models are constructed by using a spherical-symmetrical model. Hence for understanding the further planet evolution it is significant to trace the origin and evolution of heterogeneities, which occur on the planet accumulation stage. In that paper we are modeling distributions of temperature, pressure, velocity of matter flowing in a block of 3D- spherical body with a growing radius. The boundary problem is solved by the finite-difference method for the system of equations, which include equations which describe the process of accumulation, the Safronov equation, the equation of impulse balance, equation Navier-Stocks, equation for above litho static pressure and heat conductivity in velocity-pressure variables using the Businesque approach. The numerical algorithm of the problem solution in

  11. Advanced Numerical Imaging Procedure Accounting for Non-Ideal Effects in GPR Scenarios

    NASA Astrophysics Data System (ADS)

    Comite, Davide; Galli, Alessandro; Catapano, Ilaria; Soldovieri, Francesco

    2015-04-01

    The capability to provide fast and reliable imaging of targets and interfaces in non-accessible probed scenarios is a topic of great scientific interest, and many investigations have shown that Ground Penetrating Radar (GPR) can provide an efficient technique to conduct this kind of analysis in various applications of geophysical nature and civil engineering. In these cases, the development of an efficient and accurate imaging procedure is strongly dependent on the capability of accounting for the incident field that activates the scattering phenomenon. In this frame, based on a suitable implementation of an electromagnetic (EM) CAD tool (CST Microwave Studio), it has been possible to accurately and efficiently model the radiation pattern of real antennas in environments typically considered in GPR surveys [1]. A typical scenario of our interest is constituted by targets hidden in a ground medium, described by certain EM parameters and probed by a movable GPR using interfacial antennas [2]. The transmitting and receiving antennas considered here are Vivaldi ones, but a wide variety of other antennas can be modeled and designed, similar to those ones available in commercial GPR systems. Hence, an advanced version of a well-known microwave tomography approach (MTA) [3] has been implemented, both in the canonical 2D scalar case and in the more realistic 3D vectorial one. Such an approach is able to account for the real distribution of the radiated and scattered EM fields. Comparisons of results obtained by means of a 'conventional' implementation of the MTA, where the antennas are modeled as ideal line sources, and by means of our 'advanced' approach, which instead takes into account the radiation features of the chosen antenna type, have been carried out and discussed. Since the antenna radiation patterns are modified by the probed environment, whose EM features and the possible stratified structure usually are not exactly known, the imaging capabilities of the MTA

  12. Comparisons between physical model and numerical model results

    SciTech Connect

    Sagasta, P.F.

    1986-04-01

    Physical modeling scaling laws provide the opportunity to compare results among numerical modeling programs, including two- and three-dimensional interactive-raytracing and more sophisticated wave-equation-approximation methods, and seismic data collected over a known, three-dimensional model in a water tank. The sixfold closely spaced common-midpoint water-tank data modeled for this study simulate a standard marine three-dimensional survey shot over a three-layered physical model (a structured upper layer overlying two flat layers. Using modeling theory, the physical-tank model dimensions scale to realistic exploration dimensions, and the ultrasonic frequencies scale to seismic frequencies of 2-60 Hz. A comparison of P and converted-S events and amplitudes among these physical tank data and numerical modeling results illustrates many of the advantages and limitations of modeling methods available to the exploration geophysicist. The ability of three-dimensional raytracing to model off-line events and more closely predict waveform phase due to geometric effects shows the greater usefulness of three-dimensional modeling methods over two-dimensional methods in seismic interpretation. Forward modeling of P to Sv-converted events and multiples predicts their presence in the seismic data. The geometry of the physical model leads to examples where raytracing approximations are limited and the more time-consuming finite-element technique is useful to better understand wave propagation within the physical model. All of the numerical modeling programs used show limitations in matching the amplitudes and phase of events in the physical-model seismic data.

  13. Analysis of Numerical Simulation Results of LIPS-200 Lifetime Experiments

    NASA Astrophysics Data System (ADS)

    Chen, Juanjuan; Zhang, Tianping; Geng, Hai; Jia, Yanhui; Meng, Wei; Wu, Xianming; Sun, Anbang

    2016-06-01

    Accelerator grid structural and electron backstreaming failures are the most important factors affecting the ion thruster's lifetime. During the thruster's operation, Charge Exchange Xenon (CEX) ions are generated from collisions between plasma and neutral atoms. Those CEX ions grid's barrel and wall frequently, which cause the failures of the grid system. In order to validate whether the 20 cm Lanzhou Ion Propulsion System (LIPS-200) satisfies China's communication satellite platform's application requirement for North-South Station Keeping (NSSK), this study analyzed the measured depth of the pit/groove on the accelerator grid's wall and aperture diameter's variation and estimated the operating lifetime of the ion thruster. Different from the previous method, in this paper, the experimental results after the 5500 h of accumulated operation of the LIPS-200 ion thruster are presented firstly. Then, based on these results, theoretical analysis and numerical calculations were firstly performed to predict the on-orbit lifetime of LIPS-200. The results obtained were more accurate to calculate the reliability and analyze the failure modes of the ion thruster. The results indicated that the predicted lifetime of LIPS-200's was about 13218.1 h which could satisfy the required lifetime requirement of 11000 h very well.

  14. Accountability.

    ERIC Educational Resources Information Center

    Mullen, David J., Ed.

    This monograph, prepared to assist Georgia elementary principals to better understand accountability and its implications for educational improvement, sets forth many of the theoretical and philosophical bases from which accountability is being considered. Leon M. Lessinger begins this 5-paper presentation by describing the need for accountability…

  15. Accountability.

    ERIC Educational Resources Information Center

    Lashway, Larry

    1999-01-01

    This issue reviews publications that provide a starting point for principals looking for a way through the accountability maze. Each publication views accountability differently, but collectively these readings argue that even in an era of state-mandated assessment, principals can pursue proactive strategies that serve students' needs. James A.…

  16. Accountability.

    ERIC Educational Resources Information Center

    The Newsletter of the Comprehensive Center-Region VI, 1999

    1999-01-01

    Controversy surrounding the accountability movement is related to how the movement began in response to dissatisfaction with public schools. Opponents see it as one-sided, somewhat mean-spirited, and a threat to the professional status of teachers. Supporters argue that all other spheres of the workplace have accountability systems and that the…

  17. Family Life Program Accountability Norms: How Do Your Results Compare?

    ERIC Educational Resources Information Center

    Fetsch, Robert J.

    1997-01-01

    Participants in cooperative extension family life programs (N=916) identified family strains, coping, quality of life, self-esteem, stress, and willingness to support extension services with tax dollars. The resulting normative data can be used to measure the impact of cooperative extension programs. (SK)

  18. Accounting for elite indoor 200 m sprint results.

    PubMed

    Usherwood, James R; Wilson, Alan M

    2006-03-22

    Times for indoor 200 m sprint races are notably worse than those for outdoor races. In addition, there is a considerable bias against competitors drawn in inside lanes (with smaller bend radii). Centripetal acceleration requirements increase average forces during sprinting around bends. These increased forces can be modulated by changes in duty factor (the proportion of stride the limb is in contact with the ground). If duty factor is increased to keep limb forces constant, and protraction time and distance travelled during stance are unchanging, bend-running speeds are reduced. Here, we use results from the 2004 Olympics and World Indoor Championships to show quantitatively that the decreased performances in indoor competition, and the bias by lane number, are consistent with this 'constant limb force' hypothesis. Even elite athletes appear constrained by limb forces. PMID:17148323

  19. Numerical model of the highlatitude ionosphere taking into account the solar wind parameters

    NASA Astrophysics Data System (ADS)

    Uvarov, Viacheslav Mikhailovich; Lukianova, Renata

    The high latitude ionosphere is driven by both magnetospheric and solar UV inputs and, therefore, quite variable and poor predictable. Empirical models are unable to describe these complex dependencies while physics-based mathematical models are more successful in reproducing the plasma density features. In this contribution we present a numerical model of the polar ionosphere. The three-dimensional model covers the E-region, F-region and topside poleward of 40° latitude in the altitude range from 90 km to 650 km. The main output is an electron density distribution at a specified times and under a specified solar wind conditions. The model consists of two blocks: calculation the convection electric field and calculation of the ionospheric plasma parameters. The convection block includes an analytical representation of the large-scale convection patterns and their dependence on the interplanetary magnetic field (IMF) orientation. The density distributions of O+ and generalized ion species are obtained from a numerical solution of the appropriate continuity equations as a function of height. The empirical model is used to calculate the thermospheric temperature, composition, and density. Flux tubes of plasma are followed as they convect and corotate through a moving neutral atmosphere during many hours. The offset between the geomagnetic and geographic poles are also taken into account. Model simulations for different IMF conditions, solar cycle, season, universal time (UT) and magnetic activity were used to elucidate the evolution of the high latitude ionospheric morphological features. The global features such as the tongue of ionization, plasma cavity, polar and auroral peaks are well reproduced and quantified. Model electron density profiles are compared with observations using the EISCAT incoherent scatter radar and ionosonde.

  20. Busted Butte: Achieving the Objectives and Numerical Modeling Results

    SciTech Connect

    W.E. Soll; M. Kearney; P. Stauffer; P. Tseng; H.J. Turin; Z. Lu

    2002-10-07

    The Unsaturated Zone Transport Test (UZTT) at Busted Butte is a mesoscale field/laboratory/modeling investigation designed to address uncertainties associated with flow and transport in the UZ site-process models for Yucca Mountain. The UZTT test facility is located approximately 8 km southeast of the potential Yucca Mountain repository area. The UZTT was designed in two phases, to address five specific objectives in the UZ: the effect of heterogeneities, flow and transport (F&T) behavior at permeability contrast boundaries, migration of colloids , transport models of sorbing tracers, and scaling issues in moving from laboratory scale to field scale. Phase 1A was designed to assess the influence of permeability contrast boundaries in the hydrologic Calico Hills. Visualization of fluorescein movement , mineback rock analyses, and comparison with numerical models demonstrated that F&T are capillary dominated with permeability contrast boundaries distorting the capillary flow. Phase 1B was designed to assess the influence of fractures on F&T and colloid movement. The injector in Phase 1B was located at a fracture, while the collector, 30 cm below, was placed at what was assumed to be the same fracture. Numerical simulations of nonreactive (Br) and reactive (Li) tracers show the experimental data are best explained by a combination of molecular diffusion and advective flux. For Phase 2, a numerical model with homogeneous unit descriptions was able to qualitatively capture the general characteristics of the system. Numerical simulations and field observations revealed a capillary dominated flow field. Although the tracers showed heterogeneity in the test block, simulation using heterogeneous fields did not significantly improve the data fit over homogeneous field simulations. In terms of scaling, simulations of field tracer data indicate a hydraulic conductivity two orders of magnitude higher than measured in the laboratory. Simulations of Li, a weakly sorbing tracer

  1. Numerical Investigation of the Hydrogen Jet Flammable Envelope Extent with Account for Unsteady Phenomena

    NASA Astrophysics Data System (ADS)

    Chernyavsky, Boris; Benard, Pierre

    2010-11-01

    An important aspect of safety analysis in hydrogen applications is determination of the extent of flammable gas envelope in case of hydrogen jet release. Experimental investigations had shown significant disagreements between the extent of average flammable envelope predicted by steady-state numerical methods, and the region observed to support ignition, with proposed cause being non-steady jet phenomena resulting in significant variations of instantaneous gas concentration and velocity fields in the jet. In order to investigate the influence of these transient phenomena, a numerical investigation of hydrogen jet at low Mach number had been performed using unsteady Large Eddy Simulation. Instantaneous hydrogen concentration and velocity fields were monitored to determine instantaneous flammable envelope. The evolution of the instantaneous fields, including the development of the turbulence structures carrying hydrogen, their extent and frequency, and their relation with averaged fields had been characterized. Simulation had shown significant variability of the flammable envelope, with jet flapping causing shedding of large scale rich and lean gas pockets from the main jet core, which persist for significant times and substantially alter the extent of flammability envelope.

  2. Numerical calculations of high-altitude differential charging: Preliminary results

    NASA Technical Reports Server (NTRS)

    Laframboise, J. G.; Godard, R.; Prokopenko, S. M. L.

    1979-01-01

    A two dimensional simulation program was constructed in order to obtain theoretical predictions of floating potential distributions on geostationary spacecraft. The geometry was infinite-cylindrical with angle dependence. Effects of finite spacecraft length on sheath potential profiles can be included in an approximate way. The program can treat either steady-state conditions or slowly time-varying situations, involving external time scales much larger than particle transit times. Approximate, locally dependent expressions were used to provide space charge, density profiles, but numerical orbit-following is used to calculate surface currents. Ambient velocity distributions were assumed to be isotropic, beam-like, or some superposition of these.

  3. Non-Shock Initiation Model for Explosive Families: Numerical Results

    NASA Astrophysics Data System (ADS)

    Todd, S. N.; Anderson, M. U.; Caipen, T. L.; Grady, D. E.

    2009-12-01

    A damage initiated reaction (DMGIR) computational model is being developed for the CTH shock physics code to predict the response of an explosive to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of reaction in the explosive, and its growth to detonation. The DMGIR model is a complement to the History Variable Reactive Burn (HVRB) model embedded in the current CTH code. Specifically designed experiments are supporting the development, implementation, and validation of the DMGIR numerical approach. PBXN-5 was the initial explosive material used experimentally to develop the DMGIR model. This explosive represents a family of plastically bonded explosives with good mechanical strength and rigid body properties. The model has been extended to cast explosives represented by Composition B.

  4. Spurious frequencies as a result of numerical boundary treatments

    NASA Technical Reports Server (NTRS)

    Abarbanel, Saul; Gottlieb, David

    1990-01-01

    The stability theory for finite difference Initial Boundary-Value approximations to systems of hyperbolic partial differential equations states that the exclusion of eigenvalues and generalized eigenvalues is a sufficient condition for stability. The theory, however, does not discuss the nature of numerical approximations in the presence of such eigenvalues. In fact, as was shown previously, for the problem of vortex shedding by a 2-D cylinder in subsonic flow, stating boundary conditions in terms of the primitive (non-characteristic) variables may lead to such eigenvalues, causing perturbations that decay slowly in space and remain periodic time. Characteristic formulation of the boundary conditions avoided this problem. A more systematic study of the behavior of the (linearized) one-dimensional gas dynamic equations under various sets of oscillation-inducing legal boundary conditions is reported.

  5. Comparison of numerical and experimental results of the flow in the U9 Kaplan turbine model

    NASA Astrophysics Data System (ADS)

    Petit, O.; Mulu, B.; Nilsson, H.; Cervantes, M.

    2010-08-01

    The present work compares simulations made using the OpenFOAM CFD code with experimental measurements of the flow in the U9 Kaplan turbine model. Comparisons of the velocity profiles in the spiral casing and in the draft tube are presented. The U9 Kaplan turbine prototype located in Porjus and its model, located in Älvkarleby, Sweden, have curved inlet pipes that lead the flow to the spiral casing. Nowadays, this curved pipe and its effect on the flow in the turbine is not taken into account when numerical simulations are performed at design stage. To study the impact of the inlet pipe curvature on the flow in the turbine, and to get a better overview of the flow of the whole system, measurements were made on the 1:3.1 model of the U9 turbine. Previously published measurements were taken at the inlet of the spiral casing and just before the guide vanes, using the laser Doppler anemometry (LDA) technique. In the draft tube, a number of velocity profiles were measured using the LDA techniques. The present work extends the experimental investigation with a horizontal section at the inlet of the draft tube. The experimental results are used to specify the inlet boundary condition for the numerical simulations in the draft tube, and to validate the computational results in both the spiral casing and the draft tube. The numerical simulations were realized using the standard k-e model and a block-structured hexahedral wall function mesh.

  6. Numerical simulations to account for boulder movements on Lanyu Island, Taiwan: tsunami or storm?

    NASA Astrophysics Data System (ADS)

    Nakamura, Mamoru; Arashiro, Yasuhisa; Shiga, Shota

    2014-12-01

    Boulders that originated from the Holocene coral terrace and coral reef are distributed on the coral terrace or talus on the shore of Lanyu Island, Taiwan. We employed numerical simulation of storm waves and estimated whether the boulders could be moved by storm waves with a return period of 50 years, by larger storm waves with return periods of hundreds of years, or by tsunamis. The coral boulders are distributed between 36 and 128 m from the shoreline at elevations of 2.7 to 9.3 m. The sizes of the boulders are in the range 0.3 to 6.4 m. The boulder volume and a-axis length versus distance from the shore show weak and moderate correlation ( r = 0.21 and 0.48), respectively. We reproduced the runup of waves using the equation of continuity for a two-dimensional non-compressive fluid and the Navier-Stokes formula. In order to handle the free surface of the fluid, the volume of fluid method was applied. For the flow velocity to move the boulder, we employed the theoretical formula for the transport of boulders. We used the wave height for a return period of 50 years and set the height of the input wave to 13.1 m. The results show that all the large boulders on Lanyu Island could be moved by storm waves with a return period of 50 years. Moreover, the computations show that most of the boulders could not have been transported by tsunamis generated by the Mw8.7 earthquakes. The ages of two boulders indicate that they were transported after 340 and 6,330 years ago. If these boulders were moved by tsunamis several hundred years ago, they would have been relocated subsequently by storm waves.

  7. Comparison Between Numerical and Experimental Results on Mechanical Stirrer and Bubbling in a Cylindrical Tank - 13047

    SciTech Connect

    Lima da Silva, M.; Sauvage, E.; Brun, P.; Gagnoud, A.; Fautrelle, Y.; Riva, R.

    2013-07-01

    The process of vitrification in a cold crucible heated by direct induction is used in the fusion of oxides. Its feature is the production of high-purity materials. The high-level of purity of the molten is achieved because this melting technique excludes the contamination of the charge by the crucible. The aim of the present paper is to analyze the hydrodynamic of the vitrification process by direct induction, with the focus in the effects associated with the interaction between the mechanical stirrer and bubbling. Considering the complexity of the analyzed system and the goal of the present work, we simplified the system by not taking into account the thermal and electromagnetic phenomena. Based in the concept of hydraulic similitude, we performed an experimental study and a numerical modeling of the simplified model. The results of these two studies were compared and showed a good agreement. The results presented in this paper in conjunction with the previous work contribute to a better understanding of the hydrodynamics effects resulting from the interaction between the mechanical stirrer and air bubbling in the cold crucible heated by direct induction. Further works will take into account thermal and electromagnetic phenomena in the presence of mechanical stirrer and air bubbling. (authors)

  8. Sediment Pathways Across Trench Slopes: Results From Numerical Modeling

    NASA Astrophysics Data System (ADS)

    Cormier, M. H.; Seeber, L.; McHugh, C. M.; Fujiwara, T.; Kanamatsu, T.; King, J. W.

    2015-12-01

    Until the 2011 Mw9.0 Tohoku earthquake, the role of earthquakes as agents of sediment dispersal and deposition at erosional trenches was largely under-appreciated. A series of cruises carried out after the 2011 event has revealed a variety of unsuspected sediment transport mechanisms, such as tsunami-triggered sheet turbidites, suggesting that great earthquakes may in fact be important agents for dispersing sediments across trench slopes. To complement these observational data, we have modeled the pathways of sediments across the trench slope based on bathymetric grids. Our approach assumes that transport direction is controlled by slope azimuth only, and ignores obstacles smaller than 0.6-1 km; these constraints are meant to approximate the behavior of turbidites. Results indicate that (1) most pathways issued from the upper slope terminate near the top of the small frontal wedge, and thus do not reach the trench axis; (2) in turn, sediments transported to the trench axis are likely derived from the small frontal wedge or from the subducting Pacific plate. These results are consistent with the stratigraphy imaged in seismic profiles, which reveals that the slope apron does not extend as far as the frontal wedge, and that the thickness of sediments at the trench axis is similar to that of the incoming Pacific plate. We further applied this modeling technique to the Cascadia, Nankai, Middle-America, and Sumatra trenches. Where well-defined canyons carve the trench slopes, sediments from the upper slope may routinely reach the trench axis (e.g., off Costa Rica and Cascadia). In turn, slope basins that are isolated from the canyons drainage systems must mainly accumulate locally-derived sediments. Therefore, their turbiditic infill may be diagnostic of seismic activity only - and not from storm or flood activity. If correct, this would make isolated slope basins ideal targets for paleoseismological investigation.

  9. Numerical simulation results in the Carthage Cotton Valley field

    SciTech Connect

    Meehan, D.N.; Pennington, B.F.

    1982-01-01

    By coordinating three-dimensional reservoir simulations with pressure-transient tests, core analyses, open-hole and production logs, evaluations of tracer data during hydraulic fracturing, and geologic mapping, Champlin Petroleum obtained better predictions of the reserves and the long-term deliverability of the very tight (less than 0.1-md) Cotton Valley gas reservoir in east Texas. The simulation model that was developed proved capable of optimizing the well spacing and the fracture length. The final history match with the simulator indicated that the formation permeability of the very tight producing zones is substantially lower than suggested by conventional core analysis, 640-acre well spacing will not drain this reservoir efficiently in a reasonable time, and reserves are higher than presimulation estimates. Other results showed that even very long-term pressure buildups in this multilayer reservoir may not reach the straight line required in the conventional Horner pressure-transient analysis, type curves reflecting finite fracture flow capacity can be very useful, and pressure-drawdown analyses from well flow rates and flowing tubing pressure can provide good initial estimates of reservoir and fracture properties for detailed reservoir simulation without requiring expensive, long-term shut-ins of the well.

  10. A theory of scintillation for two-component power law irregularity spectra: Overview and numerical results

    NASA Astrophysics Data System (ADS)

    Carrano, Charles S.; Rino, Charles L.

    2016-06-01

    We extend the power law phase screen theory for ionospheric scintillation to account for the case where the refractive index irregularities follow a two-component inverse power law spectrum. The two-component model includes, as special cases, an unmodified power law and a modified power law with spectral break that may assume the role of an outer scale, intermediate break scale, or inner scale. As such, it provides a framework for investigating the effects of a spectral break on the scintillation statistics. Using this spectral model, we solve the fourth moment equation governing intensity variations following propagation through two-dimensional field-aligned irregularities in the ionosphere. A specific normalization is invoked that exploits self-similar properties of the structure to achieve a universal scaling, such that different combinations of perturbation strength, propagation distance, and frequency produce the same results. The numerical algorithm is validated using new theoretical predictions for the behavior of the scintillation index and intensity correlation length under strong scatter conditions. A series of numerical experiments are conducted to investigate the morphologies of the intensity spectrum, scintillation index, and intensity correlation length as functions of the spectral indices and strength of scatter; retrieve phase screen parameters from intensity scintillation observations; explore the relative contributions to the scintillation due to large- and small-scale ionospheric structures; and quantify the conditions under which a general spectral break will influence the scintillation statistics.

  11. High Numerates Count Icons and Low Numerates Process Large Areas in Pictographs: Results of an Eye-Tracking Study.

    PubMed

    Kreuzmair, Christina; Siegrist, Michael; Keller, Carmen

    2016-08-01

    In two experiments, we investigated the influence of numeracy on individuals' information processing of pictographs depending on numeracy via an eye-tracker. In two conditions, participants from the general population were presented with a scenario depicting the risk of having cancer and were asked to indicate their perceived risk. The risk level was high (63%) in experiment 1 (N = 70) and low (6%) in experiment 2 (N = 69). In the default condition, participants were free to use their default strategy for information processing. In the guiding-toward-the-number condition, they were prompted to count icons in the pictograph by answering with an explicit number. We used eye-tracking parameters related to the distance between sequential fixations to analyze participants' strategies for processing numerical information. In the default condition, the higher the numeracy was, the shorter the distances traversed in the pictograph were, indicating that participants counted the icons. People lower in numeracy performed increased large-area processing by comparing highlighted and nonhighlighted parts of the pictograph. In the guiding-toward-the-number condition, participants used short distances regardless of their numeracy, supporting the notion that short distances represent counting. Despite the different default processing strategies, participants processed the pictograph with a similar depth and derived similar risk perceptions. The results show that pictographs are beneficial for communicating medical risk. Pictographs make the gist salient by making the part-to-whole relationship visually available, and they facilitate low numerates' non-numeric processing of numerical information. Contemporaneously, pictographs allow high numerates to numerically process and rely on the number depicted in the pictograph.

  12. Numerical prediction of freezing fronts in cryosurgery: comparison with experimental results.

    PubMed

    Fortin, André; Belhamadia, Youssef

    2005-08-01

    Recent developments in scientific computing now allow to consider realistic applications of numerical modelling to medicine. In this work, a numerical method is presented for the simulation of phase change occurring in cryosurgery applications. The ultimate goal of these simulations is to accurately predict the freezing front position and the thermal history inside the ice ball which is essential to determine if cancerous cells have been completely destroyed. A semi-phase field formulation including blood flow considerations is employed for the simulations. Numerical results are enhanced by the introduction of an anisotropic remeshing strategy. The numerical procedure is validated by comparing the predictions of the model with experimental results. PMID:16298846

  13. Account of near-cathode sheath in numerical models of high-pressure arc discharges

    NASA Astrophysics Data System (ADS)

    Benilov, M. S.; Almeida, N. A.; Baeva, M.; Cunha, M. D.; Benilova, L. G.; Uhrlandt, D.

    2016-06-01

    Three approaches to describing the separation of charges in near-cathode regions of high-pressure arc discharges are compared. The first approach employs a single set of equations, including the Poisson equation, in the whole interelectrode gap. The second approach employs a fully non-equilibrium description of the quasi-neutral bulk plasma, complemented with a newly developed description of the space-charge sheaths. The third, and the simplest, approach exploits the fact that significant power is deposited by the arc power supply into the near-cathode plasma layer, which allows one to simulate the plasma-cathode interaction to the first approximation independently of processes in the bulk plasma. It is found that results given by the different models are generally in good agreement, and in some cases the agreement is even surprisingly good. It follows that the predicted integral characteristics of the plasma-cathode interaction are not strongly affected by details of the model provided that the basic physics is right.

  14. Accounting for Long Term Sediment Storage in a Watershed Scale Numerical Model for Suspended Sediment Routing

    NASA Astrophysics Data System (ADS)

    Keeler, J. J.; Pizzuto, J. E.; Skalak, K.; Karwan, D. L.; Benthem, A.; Ackerman, T. R.

    2015-12-01

    Quantifying the delivery of suspended sediment from upland sources to downstream receiving waters is important for watershed management, but current routing models fail to accurately represent lag times in delivery resulting from sediment storage. In this study, we route suspended sediment tagged by a characteristic tracer using a 1-dimensional model that implicitly includes storage and remobilization processes and timescales. From an input location where tagged sediment is added, the model advects suspended sediment downstream at the velocity of the stream (adjusted for the intermittency of transport events). Deposition rates are specified by the fraction of the suspended load stored per kilometer of downstream transport (presumably available from a sediment budget). Tagged sediment leaving storage is evaluated from a convolution equation based on the probability distribution function (pdf) of sediment storage waiting times; this approach avoids the difficulty of accurately representing complex processes of sediment remobilization from floodplain and other deposits. To illustrate the role of storage on sediment delivery, we compare exponential and bounded power-law waiting time pdfs with identical means of 94 years. In both cases, the median travel time for sediment to reach the depocenter in fluvial systems less than 40km long is governed by in-channel transport and is unaffected by sediment storage. As the channel length increases, however, the median sediment travel time reflects storage rather than in-channel transport; travel times do not vary significantly between the two different waiting time functions. At distances of 50, 100, and 200 km, the median travel time for suspended sediment is 36, 136, and 325 years, orders of magnitude slower than travel times associated with in-channel transport. These computations demonstrate that storage can be neglected for short rivers, but for longer systems, storage controls the delivery of suspended sediment.

  15. Three-dimensional convection in horizontal cylinders - Numerical solutions and comparison with experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Smutek, C.; Bontoux, P.; Roux, B.; Schiroky, G. H.; Hurford, A. C.

    1985-01-01

    The results of a three-dimensional numerical simulation of Boussinesq free convection in a horizontal differentially heated cylinder are presented. The computation was based on a Samarskii-Andreyev scheme (described by Leong, 1981) and a false-transient advancement in time, with vorticity, velocity, and temperature as dependent variables. Solutions for velocity and temperature distributions were obtained for Rayleigh numbers (based on the radius) Ra = 74-18,700, thus covering the core- and boundary-layer-driven regimes. Numerical solutions are compared with asymptotic analytical solutions and experimental data. The numerical results well represent the complex three-dimensional flows found experimentally.

  16. Numerical results using the conforming VEM for the convection-diffusion-reaction equation with variable coefficients.

    SciTech Connect

    Manzini, Gianmarco; Cangiani, Andrea; Sutton, Oliver

    2014-10-02

    This document presents the results of a set of preliminary numerical experiments using several possible conforming virtual element approximations of the convection-reaction-diffusion equation with variable coefficients.

  17. Comparison of results of experimental research with numerical calculations of a model one-sided seal

    NASA Astrophysics Data System (ADS)

    Joachimiak, Damian; Krzyślak, Piotr

    2015-06-01

    Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.

  18. Bad-good constraints on a polarity correspondence account for the spatial-numerical association of response codes (SNARC) and markedness association of response codes (MARC) effects.

    PubMed

    Leth-Steensen, Craig; Citta, Richie

    2016-01-01

    Performance in numerical classification tasks involving either parity or magnitude judgements is quicker when small numbers are mapped onto a left-sided response and large numbers onto a right-sided response than for the opposite mapping (i.e., the spatial-numerical association of response codes or SNARC effect). Recent research by Gevers et al. [Gevers, W., Santens, S., Dhooge, E., Chen, Q., Van den Bossche, L., Fias, W., & Verguts, T. (2010). Verbal-spatial and visuospatial coding of number-space interactions. Journal of Experimental Psychology: General, 139, 180-190] suggests that this effect also arises for vocal "left" and "right" responding, indicating that verbal-spatial coding has a role to play in determining it. Another presumably verbal-based, spatial-numerical mapping phenomenon is the linguistic markedness association of response codes (MARC) effect whereby responding in parity tasks is quicker when odd numbers are mapped onto left-sided responses and even numbers onto right-sided responses. A recent account of both the SNARC and MARC effects is based on the polarity correspondence principle [Proctor, R. W., & Cho, Y. S. (2006). Polarity correspondence: A general principle for performance of speeded binary classification tasks. Psychological Bulletin, 132, 416-442]. This account assumes that stimulus and response alternatives are coded along any number of dimensions in terms of - and + polarities with quicker responding when the polarity codes for the stimulus and the response correspond. In the present study, even-odd parity judgements were made using either "left" and "right" or "bad" and "good" vocal responses. Results indicated that a SNARC effect was indeed present for the former type of vocal responding, providing further evidence for the sufficiency of the verbal-spatial coding account for this effect. However, the decided lack of an analogous SNARC-like effect in the results for the latter type of vocal responding provides an important

  19. 26 CFR 1.381(c)(21)-1 - Pre-1954 adjustments resulting from change in method of accounting.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... method of accounting. 1.381(c)(21)-1 Section 1.381(c)(21)-1 Internal Revenue INTERNAL REVENUE SERVICE...(c)(21)-1 Pre-1954 adjustments resulting from change in method of accounting. (a) Carryover... to adjustments arising from changes in accounting methods initiated by the taxpayer attributable...

  20. Problems Resulting from the Implementation of a Pilot Program in Accountability.

    ERIC Educational Resources Information Center

    Field, David A.

    The concept of accountability has become very important recently to both teachers and administrators. Despite this, very few experimental projects dealing with accountability have been attempted--especially in the field of physical education. A program of accountability was conducted at Ball State University, Muncie, Indiana, in the Department of…

  1. Numerical modeling of on-orbit propellant motion resulting from an impulsive acceleration

    NASA Technical Reports Server (NTRS)

    Aydelott, John C.; Mjolsness, Raymond C.; Torrey, Martin D.; Hochstein, John I.

    1987-01-01

    In-space docking and separation maneuvers of spacecraft that have large fluid mass fractions may cause undesirable spacecraft motion in response to the impulsive-acceleration-induced fluid motion. An example of this potential low gravity fluid management problem arose during the development of the shuttle/Centaur vehicle. Experimentally verified numerical modeling techniques were developed to establish the propellant dynamics, and subsequent vehicle motion, associated with the separation of the Centaur vehicle from the shuttle orbiter cargo bay. Although the shuttle/Centaur development activity was suspended, the numerical modeling techniques are available to predict on-orbit liquid motion resulting from impulsive accelerations for other missions and spacecraft.

  2. Three-Dimensional Numerical Simulations of Equatorial Spread F: Results and Observations in the Pacific Sector

    NASA Technical Reports Server (NTRS)

    Aveiro, H. C.; Hysell, D. L.; Caton, R. G.; Groves, K. M.; Klenzing, J.; Pfaff, R. F.; Stoneback, R.; Heelis, R. A.

    2012-01-01

    A three-dimensional numerical simulation of plasma density irregularities in the postsunset equatorial F region ionosphere leading to equatorial spread F (ESF) is described. The simulation evolves under realistic background conditions including bottomside plasma shear flow and vertical current. It also incorporates C/NOFS satellite data which partially specify the forcing. A combination of generalized Rayleigh-Taylor instability (GRT) and collisional shear instability (CSI) produces growing waveforms with key features that agree with C/NOFS satellite and ALTAIR radar observations in the Pacific sector, including features such as gross morphology and rates of development. The transient response of CSI is consistent with the observation of bottomside waves with wavelengths close to 30 km, whereas the steady state behavior of the combined instability can account for the 100+ km wavelength waves that predominate in the F region.

  3. Numerical model of the lowermost Mississippi River as an alluvial-bedrock reach: preliminary results

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Nittrouer, J. A.; Mohrig, D. C.; Parker, G.

    2012-12-01

    Recent field studies reveal that the river bed of the Lower Mississippi River is characterized by a transition from alluvium (upstream) to bedrock (downstream). In particular, in the downstream 250 km of the river, fields of actively migrating bedforms alternate with deep zones where a consolidated substratum is exposed. Here we present a first version of a one-dimensional numerical model able to capture the alluvial-bedrock transition in the lowermost Mississippi River, defined herein as the 500-km reach between the Old River Control Structure and the Gulf of Mexico. The flow is assumed to be steady, and the cross-section is divided in two regions, the river channel and the floodplain. The streamwise variation of channel and floodplain geometry is described with synthetic relations derived from field observations. Flow resistance in the river channel is computed with the formulation for low-slope, large sand bed rivers due to Wright and Parker, while a Chezy-type formulation is implemented on the floodplain. Sediment is modeled in terms of bed material and wash load. Suspended load is computed with the Wright-Parker formulation. This treatment allows either uniform sediment or a mixture of different grain sizes, and accounts for stratification effects. Bedload transport rates are estimated with the relation for sediment mixtures of Ashida and Michiue. Previous work documents reasonable agreement between these load relations and field measurements. Washload is routed through the system solving the equation of mass conservation of sediment in suspension in the water column. The gradual transition from the alluvial reach to the bedrock reach is modeled in terms of a "mushy" layer of specified thickness overlying the non-erodible substrate. In the case of a fully alluvial reach, the channel bed elevation is above this mushy layer, while in the case of partial alluvial cover of the substratum, the channel bed elevation is within the mushy layer. Variations in base

  4. Finite difference model for aquifer simulation in two dimensions with results of numerical experiments

    USGS Publications Warehouse

    Trescott, Peter C.; Pinder, George Francis; Larson, S.P.

    1976-01-01

    The model will simulate ground-water flow in an artesian aquifer, a water-table aquifer, or a combined artesian and water-table aquifer. The aquifer may be heterogeneous and anisotropic and have irregular boundaries. The source term in the flow equation may include well discharge, constant recharge, leakage from confining beds in which the effects of storage are considered, and evapotranspiration as a linear function of depth to water. The theoretical development includes presentation of the appropriate flow equations and derivation of the finite-difference approximations (written for a variable grid). The documentation emphasizes the numerical techniques that can be used for solving the simultaneous equations and describes the results of numerical experiments using these techniques. Of the three numerical techniques available in the model, the strongly implicit procedure, in general, requires less computer time and has fewer numerical difficulties than do the iterative alternating direction implicit procedure and line successive overrelaxation (which includes a two-dimensional correction procedure to accelerate convergence). The documentation includes a flow chart, program listing, an example simulation, and sections on designing an aquifer model and requirements for data input. It illustrates how model results can be presented on the line printer and pen plotters with a program that utilizes the graphical display software available from the Geological Survey Computer Center Division. In addition the model includes options for reading input data from a disk and writing intermediate results on a disk.

  5. Numerical time-step restrictions as a result of capillary waves

    NASA Astrophysics Data System (ADS)

    Denner, Fabian; van Wachem, Berend G. M.

    2015-03-01

    The propagation of capillary waves on material interfaces between two fluids imposes a strict constraint on the numerical time-step applied to solve the equations governing this problem and is directly associated with the stability of interfacial flow simulations. The explicit implementation of surface tension is the generally accepted reason for the restrictions on the temporal resolution caused by capillary waves. In this article, a fully-coupled numerical framework with an implicit treatment of surface tension is proposed and applied, demonstrating that the capillary time-step constraint is in fact a constraint imposed by the temporal sampling of capillary waves, irrespective of the type of implementation. The presented results show that the capillary time-step constraint can be exceeded by several orders of magnitude, with the explicit as well as the implicit treatment of surface tension, if capillary waves are absent. Furthermore, a revised capillary time-step constraint is derived by studying the temporal resolution of capillary waves based on numerical stability and signal processing theory, including the Doppler shift caused by an underlying fluid motion. The revised capillary time-step constraint assures a robust, aliasing-free result, as demonstrated by representative numerical experiments, and is in the static case less restrictive than previously proposed time-step limits associated with capillary waves.

  6. Improving the trust in results of numerical simulations and scientific data analytics

    SciTech Connect

    Cappello, Franck; Constantinescu, Emil; Hovland, Paul; Peterka, Tom; Phillips, Carolyn; Snir, Marc; Wild, Stefan

    2015-04-30

    This white paper investigates several key aspects of the trust that a user can give to the results of numerical simulations and scientific data analytics. In this document, the notion of trust is related to the integrity of numerical simulations and data analytics applications. This white paper complements the DOE ASCR report on Cybersecurity for Scientific Computing Integrity by (1) exploring the sources of trust loss; (2) reviewing the definitions of trust in several areas; (3) providing numerous cases of result alteration, some of them leading to catastrophic failures; (4) examining the current notion of trust in numerical simulation and scientific data analytics; (5) providing a gap analysis; and (6) suggesting two important research directions and their respective research topics. To simplify the presentation without loss of generality, we consider that trust in results can be lost (or the results’ integrity impaired) because of any form of corruption happening during the execution of the numerical simulation or the data analytics application. In general, the sources of such corruption are threefold: errors, bugs, and attacks. Current applications are already using techniques to deal with different types of corruption. However, not all potential corruptions are covered by these techniques. We firmly believe that the current level of trust that a user has in the results is at least partially founded on ignorance of this issue or the hope that no undetected corruptions will occur during the execution. This white paper explores the notion of trust and suggests recommendations for developing a more scientifically grounded notion of trust in numerical simulation and scientific data analytics. We first formulate the problem and show that it goes beyond previous questions regarding the quality of results such as V&V, uncertainly quantification, and data assimilation. We then explore the complexity of this difficult problem, and we sketch complementary general

  7. Cenosphere formation from heavy fuel oil: a numerical analysis accounting for the balance between porous shells and internal pressure

    NASA Astrophysics Data System (ADS)

    Reddy, Vanteru M.; Rahman, Mustafa M.; Gandi, Appala N.; Elbaz, Ayman M.; Schrecengost, Robert A.; Roberts, William L.

    2016-01-01

    and 430 µm respectively, for 700, 900 and 1100 µm HFO droplets. The present numerical model is validated with experimental results available from the literature. Total variation between computational and experimental results is in the range of 3-7%.

  8. Numerical and experimental study of local heat transfer enhancement in helically coiled pipes. Preliminary results.

    NASA Astrophysics Data System (ADS)

    Bozzoli, F.; Cattani, L.; Rainieri, S.; Zachár, A.

    2015-11-01

    In the last years, the attention of heat transfer equipments manufacturers turned toward helically coiled-tube heat exchangers, especially with regards to applications for viscous and/or particulate products. The recent progress achieved in numerical simulation motivated many research groups to develop numerical models for this kind of apparatuses. These models, intended both to improve the knowledge of the fundamental heat transfer mechanisms in curved geometries and to support the industrial design of this kind of apparatuses, are usually validated throughout the comparison with either theoretical or experimental evidences by considering average heat transfer performances. However, this approach doesn't guarantee that the validated models are able to reproduce local effects in details, which are so important in this kind of non-standard geometries. In the present paper a numerical model of convective heat transfer in coiled tubes for laminar flow regime was formulated and discussed. Its goodness was checked throughout the comparison with the latest experimental outcomes of Bozzoli et al. [1] in terms of convective heat flux distribution along the boundary of the duct, by ensuring the effectiveness of the model also in the description of local behaviours. Although the present paper reports only preliminary results of this simulation/validation process, it could be of interest for the research community because it proposes a novel approach that could be useful to validate many numerical models for nonstandard geometries.

  9. Integration of Substance Abuse Treatment Organizations into Accountable Care Organizations: Results from a National Survey

    PubMed Central

    D’Aunno, Thomas; Friedmann, Peter D.; Chen, Qixuan; Wilson, Donna M.

    2016-01-01

    To meet their aims of managing population health to improve the quality and cost of health care in the United States, accountable care organizations (ACOs) will need to focus on coordinating care for individuals with substance abuse disorders. The prevalence of these disorders is high, and these individuals often suffer from comorbid chronic medical and social conditions. This article examines the extent to which the nation’s fourteen thousand specialty substance abuse treatment (SAT) organizations, which have a daily census of more than 1 million patients, are contracting with ACOs across the country; we also examine factors associated with SAT organization involvement with ACOs. We draw on data from a recent (2014) nationally representative survey of executive directors and clinical supervisors from 635 SAT organizations. Results show that only 15 percent of these organizations had signed contracts with ACOs. Results from multivariate analyses show that directors’ perceptions of market competition, organizational ownership, and geographic location are significantly related to SATinvolvement with ACOs. We discuss implications for integrating the SAT specialty system with the mainstream health care system. PMID:26124307

  10. Integration of Substance Abuse Treatment Organizations into Accountable Care Organizations: Results from a National Survey.

    PubMed

    D'Aunno, Thomas; Friedmann, Peter D; Chen, Qixuan; Wilson, Donna M

    2015-08-01

    To meet their aims of managing population health to improve the quality and cost of health care in the United States, accountable care organizations (ACOs) will need to focus on coordinating care for individuals with substance abuse disorders. The prevalence of these disorders is high, and these individuals often suffer from comorbid chronic medical and social conditions. This article examines the extent to which the nation's fourteen thousand specialty substance abuse treatment (SAT) organizations, which have a daily census of more than 1 million patients, are contracting with ACOs across the country; we also examine factors associated with SAT organization involvement with ACOs. We draw on data from a recent (2014) nationally representative survey of executive directors and clinical supervisors from 635 SAT organizations. Results show that only 15 percent of these organizations had signed contracts with ACOs. Results from multivariate analyses show that directors' perceptions of market competition, organizational ownership, and geographic location are significantly related to SAT involvement with ACOs. We discuss implications for integrating the SAT specialty system with the mainstream health care system. PMID:26124307

  11. Integration of Substance Abuse Treatment Organizations into Accountable Care Organizations: Results from a National Survey.

    PubMed

    D'Aunno, Thomas; Friedmann, Peter D; Chen, Qixuan; Wilson, Donna M

    2015-08-01

    To meet their aims of managing population health to improve the quality and cost of health care in the United States, accountable care organizations (ACOs) will need to focus on coordinating care for individuals with substance abuse disorders. The prevalence of these disorders is high, and these individuals often suffer from comorbid chronic medical and social conditions. This article examines the extent to which the nation's fourteen thousand specialty substance abuse treatment (SAT) organizations, which have a daily census of more than 1 million patients, are contracting with ACOs across the country; we also examine factors associated with SAT organization involvement with ACOs. We draw on data from a recent (2014) nationally representative survey of executive directors and clinical supervisors from 635 SAT organizations. Results show that only 15 percent of these organizations had signed contracts with ACOs. Results from multivariate analyses show that directors' perceptions of market competition, organizational ownership, and geographic location are significantly related to SAT involvement with ACOs. We discuss implications for integrating the SAT specialty system with the mainstream health care system.

  12. Forecasting Energy Market Contracts by Ambit Processes: Empirical Study and Numerical Results

    PubMed Central

    Di Persio, Luca; Marchesan, Michele

    2014-01-01

    In the present paper we exploit the theory of ambit processes to develop a model which is able to effectively forecast prices of forward contracts written on the Italian energy market. Both short-term and medium-term scenarios are considered and proper calibration procedures as well as related numerical results are provided showing a high grade of accuracy in the obtained approximations when compared with empirical time series of interest. PMID:27437500

  13. Forecasting Energy Market Contracts by Ambit Processes: Empirical Study and Numerical Results.

    PubMed

    Di Persio, Luca; Marchesan, Michele

    2014-01-01

    In the present paper we exploit the theory of ambit processes to develop a model which is able to effectively forecast prices of forward contracts written on the Italian energy market. Both short-term and medium-term scenarios are considered and proper calibration procedures as well as related numerical results are provided showing a high grade of accuracy in the obtained approximations when compared with empirical time series of interest.

  14. A method for data handling numerical results in parallel OpenFOAM simulations

    SciTech Connect

    Anton, Alin; Muntean, Sebastian

    2015-12-31

    Parallel computational fluid dynamics simulations produce vast amount of numerical result data. This paper introduces a method for reducing the size of the data by replaying the interprocessor traffic. The results are recovered only in certain regions of interest configured by the user. A known test case is used for several mesh partitioning scenarios using the OpenFOAM toolkit{sup ®}[1]. The space savings obtained with classic algorithms remain constant for more than 60 Gb of floating point data. Our method is most efficient on large simulation meshes and is much better suited for compressing large scale simulation results than the regular algorithms.

  15. Ground-based PIV and numerical flow visualization results from the surface tension driven convection experiment

    NASA Technical Reports Server (NTRS)

    Pline, Alexander D.; Wernet, Mark P.; Hsieh, Kwang-Chung

    1991-01-01

    The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the United States Microgravity Laboratory-1 (USML-1) Spacelab mission planned for June, 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electric, two dimensional Particle Image Velocimetry (PIV) technique called Particle Displacement Tracking (PDT), which uses a simple space domain particle tracking algorithm. Results using the ground based STDCE hardware, with a radiant flux heating mode, and the PDT system are compared to numerical solutions obtained by solving the axisymmetric Navier Stokes equations with a deformable free surface. The PDT technique is successful in producing a velocity vector field and corresponding stream function from the raw video data which satisfactorily represents the physical flow. A numerical program is used to compute the velocity field and corresponding stream function under identical conditions. Both the PDT system and numerical results were compared to a streak photograph, used as a benchmark, with good correlation.

  16. Ground-based PIV and numerical flow visualization results from the Surface Tension Driven Convection Experiment

    NASA Technical Reports Server (NTRS)

    Pline, Alexander D.; Werner, Mark P.; Hsieh, Kwang-Chung

    1991-01-01

    The Surface Tension Driven Convection Experiment (STDCE) is a Space Transportation System flight experiment to study both transient and steady thermocapillary fluid flows aboard the United States Microgravity Laboratory-1 (USML-1) Spacelab mission planned for June, 1992. One of the components of data collected during the experiment is a video record of the flow field. This qualitative data is then quantified using an all electric, two dimensional Particle Image Velocimetry (PIV) technique called Particle Displacement Tracking (PDT), which uses a simple space domain particle tracking algorithm. Results using the ground based STDCE hardware, with a radiant flux heating mode, and the PDT system are compared to numerical solutions obtained by solving the axisymmetric Navier Stokes equations with a deformable free surface. The PDT technique is successful in producing a velocity vector field and corresponding stream function from the raw video data which satisfactorily represents the physical flow. A numerical program is used to compute the velocity field and corresponding stream function under identical conditions. Both the PDT system and numerical results were compared to a streak photograph, used as a benchmark, with good correlation.

  17. Recent Analytical and Numerical Results for The Navier-Stokes-Voigt Model and Related Models

    NASA Astrophysics Data System (ADS)

    Larios, Adam; Titi, Edriss; Petersen, Mark; Wingate, Beth

    2010-11-01

    The equations which govern the motions of fluids are notoriously difficult to handle both mathematically and computationally. Recently, a new approach to these equations, known as the Voigt-regularization, has been investigated as both a numerical and analytical regularization for the 3D Navier-Stokes equations, the Euler equations, and related fluid models. This inviscid regularization is related to the alpha-models of turbulent flow; however, it overcomes many of the problems present in those models. I will discuss recent work on the Voigt-regularization, as well as a new criterion for the finite-time blow-up of the Euler equations based on their Voigt-regularization. Time permitting, I will discuss some numerical results, as well as applications of this technique to the Magnetohydrodynamic (MHD) equations and various equations of ocean dynamics.

  18. Temperature Fields in Soft Tissue during LPUS Treatment: Numerical Prediction and Experiment Results

    SciTech Connect

    Kujawska, Tamara; Wojcik, Janusz; Nowicki, Andrzej

    2010-03-09

    Recent research has shown that beneficial therapeutic effects in soft tissues can be induced by the low power ultrasound (LPUS). For example, increasing of cells immunity to stress (among others thermal stress) can be obtained through the enhanced heat shock proteins (Hsp) expression induced by the low intensity ultrasound. The possibility to control the Hsp expression enhancement in soft tissues in vivo stimulated by ultrasound can be the potential new therapeutic approach to the neurodegenerative diseases which utilizes the known feature of cells to increase their immunity to stresses through the Hsp expression enhancement. The controlling of the Hsp expression enhancement by adjusting of exposure level to ultrasound energy would allow to evaluate and optimize the ultrasound-mediated treatment efficiency. Ultrasonic regimes are controlled by adjusting the pulsed ultrasound waves intensity, frequency, duration, duty cycle and exposure time. Our objective was to develop the numerical model capable of predicting in space and time temperature fields induced by a circular focused transducer generating tone bursts in multilayer nonlinear attenuating media and to compare the numerically calculated results with the experimental data in vitro. The acoustic pressure field in multilayer biological media was calculated using our original numerical solver. For prediction of temperature fields the Pennes' bio-heat transfer equation was employed. Temperature field measurements in vitro were carried out in a fresh rat liver using the 15 mm diameter, 25 mm focal length and 2 MHz central frequency transducer generating tone bursts with the spatial peak temporal average acoustic intensity varied between 0.325 and 1.95 W/cm{sup 2}, duration varied from 20 to 500 cycles at the same 20% duty cycle and the exposure time varied up to 20 minutes. The measurement data were compared with numerical simulation results obtained under experimental boundary conditions. Good agreement between

  19. Temperature Fields in Soft Tissue during LPUS Treatment: Numerical Prediction and Experiment Results

    NASA Astrophysics Data System (ADS)

    Kujawska, Tamara; Wójcik, Janusz; Nowicki, Andrzej

    2010-03-01

    Recent research has shown that beneficial therapeutic effects in soft tissues can be induced by the low power ultrasound (LPUS). For example, increasing of cells immunity to stress (among others thermal stress) can be obtained through the enhanced heat shock proteins (Hsp) expression induced by the low intensity ultrasound. The possibility to control the Hsp expression enhancement in soft tissues in vivo stimulated by ultrasound can be the potential new therapeutic approach to the neurodegenerative diseases which utilizes the known feature of cells to increase their immunity to stresses through the Hsp expression enhancement. The controlling of the Hsp expression enhancement by adjusting of exposure level to ultrasound energy would allow to evaluate and optimize the ultrasound-mediated treatment efficiency. Ultrasonic regimes are controlled by adjusting the pulsed ultrasound waves intensity, frequency, duration, duty cycle and exposure time. Our objective was to develop the numerical model capable of predicting in space and time temperature fields induced by a circular focused transducer generating tone bursts in multilayer nonlinear attenuating media and to compare the numerically calculated results with the experimental data in vitro. The acoustic pressure field in multilayer biological media was calculated using our original numerical solver. For prediction of temperature fields the Pennes' bio-heat transfer equation was employed. Temperature field measurements in vitro were carried out in a fresh rat liver using the 15 mm diameter, 25 mm focal length and 2 MHz central frequency transducer generating tone bursts with the spatial peak temporal average acoustic intensity varied between 0.325 and 1.95 W/cm2, duration varied from 20 to 500 cycles at the same 20% duty cycle and the exposure time varied up to 20 minutes. The measurement data were compared with numerical simulation results obtained under experimental boundary conditions. Good agreement between the

  20. Global Access to Safe Water: Accounting for Water Quality and the Resulting Impact on MDG Progress

    PubMed Central

    Onda, Kyle; LoBuglio, Joe; Bartram, Jamie

    2012-01-01

    Monitoring of progress towards the Millennium Development Goal (MDG) drinking water target relies on classification of water sources as “improved” or “unimproved” as an indicator for water safety. We adjust the current Joint Monitoring Programme (JMP) estimate by accounting for microbial water quality and sanitary risk using the only-nationally representative water quality data currently available, that from the WHO and UNICEF “Rapid Assessment of Drinking Water Quality”. A principal components analysis (PCA) of national environmental and development indicators was used to create models that predicted, for most countries, the proportions of piped and of other-improved water supplies that are faecally contaminated; and of these sources, the proportions that lack basic sanitary protection against contamination. We estimate that 1.8 billion people (28% of the global population) used unsafe water in 2010. The 2010 JMP estimate is that 783 million people (11%) use unimproved sources. Our estimates revise the 1990 baseline from 23% to 37%, and the target from 12% to 18%, resulting in a shortfall of 10% of the global population towards the MDG target in 2010. In contrast, using the indicator “use of an improved source” suggests that the MDG target for drinking-water has already been achieved. We estimate that an additional 1.2 billion (18%) use water from sources or systems with significant sanitary risks. While our estimate is imprecise, the magnitude of the estimate and the health and development implications suggest that greater attention is needed to better understand and manage drinking water safety. PMID:22690170

  1. Experimental and numerical results on the fluid flow driven by a traveling magnetic field

    NASA Astrophysics Data System (ADS)

    Lantzsch, R.; Galindo, V.; Grants, I.; Zhang, C.; Pätzold, O.; Gerbeth, G.; Stelter, M.

    2007-07-01

    A traveling magnetic field (TMF) driven flow and its transition from a laminar to a time-dependent flow is studied by means of ultrasonic Doppler velocimetry and numerical simulations. The experimental setup comprises a cylindrical cavity containing the electrically conducting model fluid GaInSn and a system of six equidistant coils, which are fed by an out-of-phase current to create an up- or downward directed TMF. Hence, a Lorentz force is induced in the melt which leads to meridional flow patterns. For numerical simulations commercial codes (Opera/Fidap) and a spectral code are used. The characteristic parameters of the magnetohydrodynamic model system are chosen close to the conditions used for vertical gradient freeze (VGF) crystal growth. The axisymmetric basic flow and its dependence on the dimensionless shielding parameter S are examined. It is shown that, for S>10, the flow velocity decreases significantly, whereas almost no influence is found for a smaller shielding parameter. The critical Reynolds number for the onset of instability is found in the range of 300-450. Good agreement between experimental results and the numerical simulations is achieved.

  2. Network model to study physiological processes of hypobaric decompression sickness: New numerical results

    NASA Astrophysics Data System (ADS)

    Zueco, Joaquín; López-González, Luis María

    2016-04-01

    We have studied decompression processes when pressure changes that take place, in blood and tissues using a technical numerical based in electrical analogy of the parameters that involved in the problem. The particular problem analyzed is the behavior dynamics of the extravascular bubbles formed in the intercellular cavities of a hypothetical tissue undergoing decompression. Numerical solutions are given for a system of equations to simulate gas exchanges of bubbles after decompression, with particular attention paid to the effect of bubble size, nitrogen tension, nitrogen diffusivity in the intercellular fluid and in the tissue cell layer in a radial direction, nitrogen solubility, ambient pressure and specific blood flow through the tissue over the different molar diffusion fluxes of nitrogen per time unit (through the bubble surface, between the intercellular fluid layer and blood and between the intercellular fluid layer and the tissue cell layer). The system of nonlinear equations is solved using the Network Simulation Method, where the electric analogy is applied to convert these equations into a network-electrical model, and a computer code (electric circuit simulator, Pspice). In this paper, numerical results new (together to a network model improved with interdisciplinary electrical analogies) are provided.

  3. Laboratory simulations of lidar returns from clouds: experimental and numerical results.

    PubMed

    Zaccanti, G; Bruscaglioni, P; Gurioli, M; Sansoni, P

    1993-03-20

    The experimental results of laboratory simulations of lidar returns from clouds are presented. Measurements were carried out on laboratory-scaled cloud models by using a picosecond laser and a streak-camera system. The turbid structures simulating clouds were suspensions of polystyrene spheres in water. The geometrical situation was similar to that of an actual lidar sounding a cloud 1000 m distant and with a thickness of 300 m. Measurements were repeated for different concentrations and different sizes of spheres. The results show how the effect of multiple scattering depends on the scattering coefficient and on the phase function of the diffusers. The depolarization introduced by multiple scattering was also investigated. The results were also compared with numerical results obtained by Monte Carlo simulations. Substantially good agreement between numerical and experimental results was found. The measurements showed the adequacy of modern electro-optical systems to study the features of multiple-scattering effects on lidar echoes from atmosphere or ocean by means of experiments on well-controlled laboratory-scaled models. This adequacy provides the possibility of studying the influence of different effects in the laboratory in well-controlled situations.

  4. Some analytical and numerical approaches to understanding trap counts resulting from pest insect immigration.

    PubMed

    Bearup, Daniel; Petrovskaya, Natalia; Petrovskii, Sergei

    2015-05-01

    Monitoring of pest insects is an important part of the integrated pest management. It aims to provide information about pest insect abundance at a given location. This includes data collection, usually using traps, and their subsequent analysis and/or interpretation. However, interpretation of trap count (number of insects caught over a fixed time) remains a challenging problem. First, an increase in either the population density or insects activity can result in a similar increase in the number of insects trapped (the so called "activity-density" problem). Second, a genuine increase of the local population density can be attributed to qualitatively different ecological mechanisms such as multiplication or immigration. Identification of the true factor causing an increase in trap count is important as different mechanisms require different control strategies. In this paper, we consider a mean-field mathematical model of insect trapping based on the diffusion equation. Although the diffusion equation is a well-studied model, its analytical solution in closed form is actually available only for a few special cases, whilst in a more general case the problem has to be solved numerically. We choose finite differences as the baseline numerical method and show that numerical solution of the problem, especially in the realistic 2D case, is not at all straightforward as it requires a sufficiently accurate approximation of the diffusion fluxes. Once the numerical method is justified and tested, we apply it to the corresponding boundary problem where different types of boundary forcing describe different scenarios of pest insect immigration and reveal the corresponding patterns in the trap count growth. PMID:25744607

  5. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    SciTech Connect

    O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

  6. Numerical simulation of electromagnetic fields and impedance of CERN LINAC4 H(-) source taking into account the effect of the plasma.

    PubMed

    Grudiev, A; Lettry, J; Mattei, S; Paoluzzi, M; Scrivens, R

    2014-02-01

    Numerical simulation of the CERN LINAC4 H(-) source 2 MHz RF system has been performed taking into account a realistic geometry from 3D Computer Aided Design model using commercial FEM high frequency simulation code. The effect of the plasma has been added to the model by the approximation of a homogenous electrically conducting medium. Electric and magnetic fields, RF power losses, and impedance of the circuit have been calculated for different values of the plasma conductivity. Three different regimes have been found depending on the plasma conductivity: (1) Zero or low plasma conductivity results in RF electric field induced by the RF antenna being mainly capacitive and has axial direction; (2) Intermediate conductivity results in the expulsion of capacitive electric field from plasma and the RF power coupling, which is increasing linearly with the plasma conductivity, is mainly dominated by the inductive azimuthal electric field; (3) High conductivity results in the shielding of both the electric and magnetic fields from plasma due to the skin effect, which reduces RF power coupling to plasma. From these simulations and measurements of the RF power coupling on the CERN source, a value of the plasma conductivity has been derived. It agrees well with an analytical estimate calculated from the measured plasma parameters. In addition, the simulated and measured impedances with and without plasma show very good agreement as well demonstrating validity of the plasma model used in the RF simulations.

  7. Numerical computation of the effective-one-body potential q using self-force results

    NASA Astrophysics Data System (ADS)

    Akcay, Sarp; van de Meent, Maarten

    2016-03-01

    The effective-one-body theory (EOB) describes the conservative dynamics of compact binary systems in terms of an effective Hamiltonian approach. The Hamiltonian for moderately eccentric motion of two nonspinning compact objects in the extreme mass-ratio limit is given in terms of three potentials: a (v ) , d ¯ (v ) , q (v ) . By generalizing the first law of mechanics for (nonspinning) black hole binaries to eccentric orbits, [A. Le Tiec, Phys. Rev. D 92, 084021 (2015).] recently obtained new expressions for d ¯(v ) and q (v ) in terms of quantities that can be readily computed using the gravitational self-force approach. Using these expressions we present a new computation of the EOB potential q (v ) by combining results from two independent numerical self-force codes. We determine q (v ) for inverse binary separations in the range 1 /1200 ≤v ≲1 /6 . Our computation thus provides the first-ever strong-field results for q (v ) . We also obtain d ¯ (v ) in our entire domain to a fractional accuracy of ≳10-8 . We find that our results are compatible with the known post-Newtonian expansions for d ¯(v ) and q (v ) in the weak field, and agree with previous (less accurate) numerical results for d ¯(v ) in the strong field.

  8. Accountability for Results: The Realities of Data-Driven Decision Making

    ERIC Educational Resources Information Center

    McCaw, Donna; Watkins, Sandra

    2007-01-01

    The format of this book addresses the most salient questions administrators, school board members, and community stakeholders need to ask to ensure academic and fiscal accountability, providing definitions, background information and the current research. Readers will be provided with sufficient knowledge to effectively question the financial…

  9. Motivations, Costs and Results of AOL: Perceptions of Accounting and Economics Faculty

    ERIC Educational Resources Information Center

    Eschenfelder, Mark J.; Bryan, Lois D.; Lee, Tanya M.

    2014-01-01

    The emphasis of the Association to Advance Collegiate Schools of Business (AACSB) on improving student learning through Assurance of Learning (AOL) makes faculty involvement in the process at AACSB accredited schools important. This study examines the attitudes of accounting and economics faculty at AACSB accredited institutions toward the AOL…

  10. Performance of semirigid timber frame with Lagscrewbolt connections: experimental, analytical, and numerical model results

    NASA Astrophysics Data System (ADS)

    Mori, Takuro; Nakatani, Makoto; Tesfamariam, Solomon

    2015-12-01

    This paper presents analytical and numerical models for semirigid timber frame with Lagscrewbolt (LSB) connections. A series of static and reverse cyclic experimental tests were carried out for different beam sizes (400, 500, and 600 mm depth) and column-base connections with different numbers of LSBs (4, 5, 8). For the beam-column connections, with increase in beam depth, moment resistance and stiffness values increased, and ductility factor reduced. For the column-base connection, with increase in the number of LSBs, the strength, stiffness, and ductility values increased. A material model available in OpenSees, Pinching4 hysteretic model, was calibrated for all connection test results. Finally, analytical model of the portal frame was developed and compared with the experimental test results. Overall, there was good agreement with the experimental test results, and the Pinching4 hysteretic model can readily be used for full-scale structural model.

  11. Numerical approach to constructing the lunar physical libration: results of the initial stage

    NASA Astrophysics Data System (ADS)

    Zagidullin, A.; Petrova, N.; Nefediev, Yu.; Usanin, V.; Glushkov, M.

    2015-10-01

    So called "main problem" it is taken as a model to develop the numerical approach in the theory of lunar physical libration. For the chosen model, there are both a good methodological basis and results obtained at the Kazan University as an outcome of the analytic theory construction. Results of the first stage in numerical approach are presented in this report. Three main limitation are taken to describe the main problem: -independent consideration of orbital and rotational motion of the Moon; - a rigid body model for the lunar body is taken and its dynamical figure is described by inertia ellipsoid, which gives us the mass distribution inside the Moon. - only gravitational interaction with the Earth and the Sun is considered. Development of selenopotential is limited on this stage by the second harmonic only. Inclusion of the 3-rd and 4-th order harmonics is the nearest task for the next stage.The full solution of libration problem consists of removing the below specified limitations: consideration of the fine effects, caused by planet perturbations, by visco-elastic properties of the lunar body, by the presence of a two-layer lunar core, by the Earth obliquity, by ecliptic rotation, if it is taken as a reference plane.

  12. Instability of surface lenticular vortices: results from laboratory experiments and numerical simulations

    NASA Astrophysics Data System (ADS)

    Lahaye, Noé; Paci, Alexandre; Smith, Stefan Llewellyn

    2016-04-01

    We examine the instability of lenticular vortices -- or lenses -- in a stratified rotating fluid. The simplest configuration is one in which the lenses overlay a deep layer and have a free surface, and this can be studied using a two-layer rotating shallow water model. We report results from laboratory experiments and high-resolution direct numerical simulations of the destabilization of vortices with constant potential vorticity, and compare these to a linear stability analysis. The stability properties of the system are governed by two parameters: the typical upper-layer potential vorticity and the size (depth) of the vortex. Good agreement is found between analytical, numerical and experimental results for the growth rate and wavenumber of the instability. The nonlinear saturation of the instability is associated with conversion from potential to kinetic energy and weak emission of gravity waves, giving rise to the formation of coherent vortex multipoles with trapped waves. The impact of flow in the lower layer is examined. In particular, it is shown that the growth rate can be strongly affected and the instability can be suppressed for certain types of weak co-rotating flow.

  13. Noninvasive assessment of mitral inertness: clinical results with numerical model validation

    NASA Technical Reports Server (NTRS)

    Firstenberg, M. S.; Greenberg, N. L.; Smedira, N. G.; McCarthy, P. M.; Garcia, M. J.; Thomas, J. D.

    2001-01-01

    Inertial forces (Mdv/dt) are a significant component of transmitral flow, but cannot be measured with Doppler echo. We validated a method of estimating Mdv/dt. Ten patients had a dual sensor transmitral (TM) catheter placed during cardiac surgery. Doppler and 2D echo was performed while acquiring LA and LV pressures. Mdv/dt was determined from the Bernoulli equation using Doppler velocities and TM gradients. Results were compared with numerical modeling. TM gradients (range: 1.04-14.24 mmHg) consisted of 74.0 +/- 11.0% inertial forcers (range: 0.6-12.9 mmHg). Multivariate analysis predicted Mdv/dt = -4.171(S/D (RATIO)) + 0.063(LAvolume-max) + 5. Using this equation, a strong relationship was obtained for the clinical dataset (y=0.98x - 0.045, r=0.90) and the results of numerical modeling (y=0.96x - 0.16, r=0.84). TM gradients are mainly inertial and, as validated by modeling, can be estimated with echocardiography.

  14. Numerical modelling of radon-222 entry into houses: an outline of techniques and results.

    PubMed

    Andersen, C E

    2001-05-14

    Numerical modelling is a powerful tool for studies of soil gas and radon-222 entry into houses. It is the purpose of this paper to review some main techniques and results. In the past, modelling has focused on Darcy flow of soil gas (driven by indoor-outdoor pressure differences) and combined diffusive and advective transport of radon. Models of different complexity have been used. The simpler ones are finite-difference models with one or two spatial dimensions. The more complex models allow for full three-dimensional and time dependency. Advanced features include: soil heterogeneity, anisotropy, fractures, moisture, non-uniform soil temperature, non-Darcy flow of gas, and flow caused by changes in the atmospheric pressure. Numerical models can be used to estimate the importance of specific factors for radon entry. Models are also helpful when results obtained in special laboratory or test structure experiments need to be extrapolated to more general situations (e.g. to real houses or even to other soil-gas pollutants). Finally, models provide a cost-effective test bench for improved designs of radon prevention systems. The paper includes a summary of transport equations and boundary conditions. As an illustrative example, radon entry is calculated for a standard slab-on-grade house.

  15. [Numerical Simulation of Propagation of Electric Excitation in the Heart Wall Taking into Account Its Fibrous-Laminar Structure].

    PubMed

    Vasserman, I N; Matveenko, V P; Shardakov, I N; Shestakov, A P

    2015-01-01

    The propagation of excitation wave in the inhomogeneous anisotropic finite element model of cardiac muscle is investigated. In this model, the inhomogeneity stands for the rotation of anisotropy axes through the wall thickness and results from a fibrous-laminar structure of the cardiac muscle tissue. Conductivity of the cardiac muscle is described using a monodomain model and the Aliev-Panfilov equations are used as the relationships between the transmembrane current and transmembrane potential. Numerical simulation is performed by applying the splitting algorithm, in which the partial differential solution to the nonlinear boundary value problem is reduced to a sequence of simple ordinary differential equations and linear partial differential equations. The simulation is carried out for a rectangular block of the cardiac tissue, the minimal size of which is considered to be the thickness of the heart wall. Two types of distribution of the fiber orientation angle are discussed. The first case corresponds 'to the left ventricle of a dog. The endocardium and epicardium fibers are generally oriented in the meridional direction. The angle of fiber orientation varies smoothly through the wall thickness making a half-turn. A circular layer, in which the fibers are oriented in the circumferential direction locates deep in the cardiac wall. The results of calculations show that for this case the wave form strongly depends on a place of initial excitation. For the endocardial and epicardial initial excitation one can see the earlier wave front propagation in the endocardium and epicardium, respectively. At the intramural initial excitation the simultaneous wave front propagation in the endocardium and epicardium occurs, but there is a wave front lag in the middle of the wall. The second case refers to the right ventricle of a swine, in which the endocardium and epicardium fibers are typically oriented in the circumferential direction, whereas the subepicardium fibers

  16. Long-Term Creep Behavior of the Intervertebral Disk: Comparison between Bioreactor Data and Numerical Results

    PubMed Central

    Castro, A. P. G.; Paul, C. P. L.; Detiger, S. E. L.; Smit, T. H.; van Royen, B. J.; Pimenta Claro, J. C.; Mullender, M. G.; Alves, J. L.

    2014-01-01

    The loaded disk culture system is an intervertebral disk (IVD)-oriented bioreactor developed by the VU Medical Center (VUmc, Amsterdam, The Netherlands), which has the capacity of maintaining up to 12 IVDs in culture, for approximately 3 weeks after extraction. Using this system, eight goat IVDs were provided with the essential nutrients and submitted to compression tests without losing their biomechanical and physiological properties, for 22 days. Based on previous reports (Paul et al., 2012, 2013; Detiger et al., 2013), four of these IVDs were kept in physiological condition (control) and the other four were previously injected with chondroitinase ABC (CABC), in order to promote degenerative disk disease (DDD). The loading profile intercalated 16 h of activity loading with 8 h of loading recovery to express the standard circadian variations. The displacement behavior of these eight IVDs along the first 2 days of the experiment was numerically reproduced, using an IVD osmo-poro-hyper-viscoelastic and fiber-reinforced finite element (FE) model. The simulations were run on a custom FE solver (Castro et al., 2014). The analysis of the experimental results allowed concluding that the effect of the CABC injection was only significant in two of the four IVDs. The four control IVDs showed no signs of degeneration, as expected. In what concerns to the numerical simulations, the IVD FE model was able to reproduce the generic behavior of the two groups of goat IVDs (control and injected). However, some discrepancies were still noticed on the comparison between the injected IVDs and the numerical simulations, namely on the recovery periods. This may be justified by the complexity of the pathways for DDD, associated with the multiplicity of physiological responses to each direct or indirect stimulus. Nevertheless, one could conclude that ligaments, muscles, and IVD covering membranes could be added to the FE model, in order to improve its accuracy and properly

  17. Long-Term Creep Behavior of the Intervertebral Disk: Comparison between Bioreactor Data and Numerical Results.

    PubMed

    Castro, A P G; Paul, C P L; Detiger, S E L; Smit, T H; van Royen, B J; Pimenta Claro, J C; Mullender, M G; Alves, J L

    2014-01-01

    The loaded disk culture system is an intervertebral disk (IVD)-oriented bioreactor developed by the VU Medical Center (VUmc, Amsterdam, The Netherlands), which has the capacity of maintaining up to 12 IVDs in culture, for approximately 3 weeks after extraction. Using this system, eight goat IVDs were provided with the essential nutrients and submitted to compression tests without losing their biomechanical and physiological properties, for 22 days. Based on previous reports (Paul et al., 2012, 2013; Detiger et al., 2013), four of these IVDs were kept in physiological condition (control) and the other four were previously injected with chondroitinase ABC (CABC), in order to promote degenerative disk disease (DDD). The loading profile intercalated 16 h of activity loading with 8 h of loading recovery to express the standard circadian variations. The displacement behavior of these eight IVDs along the first 2 days of the experiment was numerically reproduced, using an IVD osmo-poro-hyper-viscoelastic and fiber-reinforced finite element (FE) model. The simulations were run on a custom FE solver (Castro et al., 2014). The analysis of the experimental results allowed concluding that the effect of the CABC injection was only significant in two of the four IVDs. The four control IVDs showed no signs of degeneration, as expected. In what concerns to the numerical simulations, the IVD FE model was able to reproduce the generic behavior of the two groups of goat IVDs (control and injected). However, some discrepancies were still noticed on the comparison between the injected IVDs and the numerical simulations, namely on the recovery periods. This may be justified by the complexity of the pathways for DDD, associated with the multiplicity of physiological responses to each direct or indirect stimulus. Nevertheless, one could conclude that ligaments, muscles, and IVD covering membranes could be added to the FE model, in order to improve its accuracy and properly

  18. Combustion Of Moving Droplets And Of Droplets Suspended Within A Convective Environment: Transient Numerical Results

    NASA Technical Reports Server (NTRS)

    Gogos, George; Pope, Daniel N.

    2003-01-01

    The problem considered is that of a single-component liquid fuel (n-heptane) droplet undergoing evaporation and combustion in a hot, convective, low pressure, zero-gravity environment of infinite expanse. For a moving droplet, the relative velocity (U(sub infinity)) between the droplet and freestream is subject to change due to the influence of the drag force on the droplet. For a suspended droplet, the relative velocity is kept constant. The governing equations for the gas-phase and the liquid-phase consist of the unsteady, axisymmetric equations of mass, momentum, species (gas-phase only) and energy conservation. Interfacial conservation equations are employed to couple the two phases. Variable properties are used in the gas- and liquid-phase. Multicomponent diffusion in the gas-phase is accounted for by solving the Stefan-Maxwell equations for the species diffusion velocities. A one-step overall reaction is used to model the combustion. The governing equations are discretized using the finite volume and SIMPLEC methods. A colocated grid is adopted. Hyperbolic tangent stretching functions are used to concentrate grid points near the fore and aft lines of symmetry and at the droplet surface in both the gas- and liquid-phase. The discretization equations are solved using the ADI method with the TDMA used on each line of the two alternating directions. Iterations are performed within each time-step until convergence is achieved. The grid spacing, size of the computational domain and time-step were tested to ensure that all solutions are independent of these parameters. A detailed discussion of the numerical model is given.

  19. Re-Computation of Numerical Results Contained in NACA Report No. 496

    NASA Technical Reports Server (NTRS)

    Perry, Boyd, III

    2015-01-01

    An extensive examination of NACA Report No. 496 (NACA 496), "General Theory of Aerodynamic Instability and the Mechanism of Flutter," by Theodore Theodorsen, is described. The examination included checking equations and solution methods and re-computing interim quantities and all numerical examples in NACA 496. The checks revealed that NACA 496 contains computational shortcuts (time- and effort-saving devices for engineers of the time) and clever artifices (employed in its solution methods), but, unfortunately, also contains numerous tripping points (aspects of NACA 496 that have the potential to cause confusion) and some errors. The re-computations were performed employing the methods and procedures described in NACA 496, but using modern computational tools. With some exceptions, the magnitudes and trends of the original results were in fair-to-very-good agreement with the re-computed results. The exceptions included what are speculated to be computational errors in the original in some instances and transcription errors in the original in others. Independent flutter calculations were performed and, in all cases, including those where the original and re-computed results differed significantly, were in excellent agreement with the re-computed results. Appendix A contains NACA 496; Appendix B contains a Matlab(Reistered) program that performs the re-computation of results; Appendix C presents three alternate solution methods, with examples, for the two-degree-of-freedom solution method of NACA 496; Appendix D contains the three-degree-of-freedom solution method (outlined in NACA 496 but never implemented), with examples.

  20. Interpretation of high-dimensional numerical results for the Anderson transition

    SciTech Connect

    Suslov, I. M.

    2014-12-15

    The existence of the upper critical dimension d{sub c2} = 4 for the Anderson transition is a rigorous consequence of the Bogoliubov theorem on renormalizability of φ{sup 4} theory. For d ≥ 4 dimensions, one-parameter scaling does not hold and all existent numerical data should be reinterpreted. These data are exhausted by the results for d = 4, 5 from scaling in quasi-one-dimensional systems and the results for d = 4, 5, 6 from level statistics. All these data are compatible with the theoretical scaling dependences obtained from Vollhardt and Wolfle’s self-consistent theory of localization. The widespread viewpoint that d{sub c2} = ∞ is critically discussed.

  1. Chaoticity threshold in magnetized plasmas: Numerical results in the weak coupling regime

    SciTech Connect

    Carati, A. Benfenati, F.; Maiocchi, A.; Galgani, L.; Zuin, M.

    2014-03-15

    The present paper is a numerical counterpart to the theoretical work [Carati et al., Chaos 22, 033124 (2012)]. We are concerned with the transition from order to chaos in a one-component plasma (a system of point electrons with mutual Coulomb interactions, in a uniform neutralizing background), the plasma being immersed in a uniform stationary magnetic field. In the paper [Carati et al., Chaos 22, 033124 (2012)], it was predicted that a transition should take place when the electron density is increased or the field decreased in such a way that the ratio ω{sub p}/ω{sub c} between plasma and cyclotron frequencies becomes of order 1, irrespective of the value of the so-called Coulomb coupling parameter Γ. Here, we perform numerical computations for a first principles model of N point electrons in a periodic box, with mutual Coulomb interactions, using as a probe for chaoticity the time-autocorrelation function of magnetization. We consider two values of Γ (0.04 and 0.016) in the weak coupling regime Γ ≪ 1, with N up to 512. A transition is found to occur for ω{sub p}/ω{sub c} in the range between 0.25 and 2, in fairly good agreement with the theoretical prediction. These results might be of interest for the problem of the breakdown of plasma confinement in fusion machines.

  2. Verification of Numerical Weather Prediction Model Results for Energy Applications in Latvia

    NASA Astrophysics Data System (ADS)

    Sīle, Tija; Cepite-Frisfelde, Daiga; Sennikovs, Juris; Bethers, Uldis

    2014-05-01

    A resolution to increase the production and consumption of renewable energy has been made by EU governments. Most of the renewable energy in Latvia is produced by Hydroelectric Power Plants (HPP), followed by bio-gas, wind power and bio-mass energy production. Wind and HPP power production is sensitive to meteorological conditions. Currently the basis of weather forecasting is Numerical Weather Prediction (NWP) models. There are numerous methodologies concerning the evaluation of quality of NWP results (Wilks 2011) and their application can be conditional on the forecast end user. The goal of this study is to evaluate the performance of Weather Research and Forecast model (Skamarock 2008) implementation over the territory of Latvia, focusing on forecasting of wind speed and quantitative precipitation forecasts. The target spatial resolution is 3 km. Observational data from Latvian Environment, Geology and Meteorology Centre are used. A number of standard verification metrics are calculated. The sensitivity to the model output interpretation (output spatial interpolation versus nearest gridpoint) is investigated. For the precipitation verification the dichotomous verification metrics are used. Sensitivity to different precipitation accumulation intervals is examined. Skamarock, William C. and Klemp, Joseph B. A time-split nonhydrostatic atmospheric model for weather research and forecasting applications. Journal of Computational Physics. 227, 2008, pp. 3465-3485. Wilks, Daniel S. Statistical Methods in the Atmospheric Sciences. Third Edition. Academic Press, 2011.

  3. A Budget and Accounting of Metals at z ~ 0: Results from the COS-Halos Survey

    NASA Astrophysics Data System (ADS)

    Peeples, Molly S.; Werk, Jessica K.; Tumlinson, Jason; Oppenheimer, Benjamin D.; Prochaska, J. Xavier; Katz, Neal; Weinberg, David H.

    2014-05-01

    We present a budget and accounting of metals in and around star-forming galaxies at z ~ 0. We combine empirically derived star formation histories with updated supernova and asymptotic giant branch yields and rates to estimate the total mass of metals produced by galaxies with present-day stellar mass of 109.3-1011.6 M⊙. On the accounting side of the ledger, we show that a surprisingly constant 20%-25% mass fraction of produced metals remain in galaxies' stars, interstellar gas and interstellar dust, with little dependence of this fraction on the galaxy stellar mass (omitting those metals immediately locked up in remnants). Thus, the bulk of metals are outside of galaxies, produced in the progenitors of today's L* galaxies. The COS-Halos survey is uniquely able to measure the mass of metals in the circumgalactic medium (CGM, to impact parameters of <150 kpc) of low-redshift ~L* galaxies. Using these data, we map the distribution of CGM metals as traced by both the highly ionized O VI ion and a suite of low-ionization species; combined with constraints on circumgalactic dust and hotter X-ray emitting gas out to similar impact parameters, we show that ~40% of metals produced by M sstarf ~ 1010 M⊙ galaxies can be easily accounted for out to 150 kpc. With the current data, we cannot rule out a constant mass of metals within this fixed physical radius. This census provides a crucial boundary condition for the eventual fate of metals in galaxy evolution models. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO11598.

  4. Pericenter precession induced by a circumstellar disk on the orbit of massive bodies: comparison between analytical predictions and numerical results

    NASA Astrophysics Data System (ADS)

    Fontana, A.; Marzari, F.

    2016-05-01

    Context. Planetesimals and planets embedded in a circumstellar disk are dynamically perturbed by the disk gravity. It causes an apsidal line precession at a rate that depends on the disk density profile and on the distance of the massive body from the star. Aims: Different analytical models are exploited to compute the precession rate of the perihelion ϖ˙. We compare them to verify their equivalence, in particular after analytical manipulations performed to derive handy formulas, and test their predictions against numerical models in some selected cases. Methods: The theoretical precession rates were computed with analytical algorithms found in the literature using the Mathematica symbolic code, while the numerical simulations were performed with the hydrodynamical code FARGO. Results: For low-mass bodies (planetesimals) the analytical approaches described in Binney & Tremaine (2008, Galactic Dynamics, p. 96), Ward (1981, Icarus, 47, 234), and Silsbee & Rafikov (2015a, ApJ, 798, 71) are equivalent under the same initial conditions for the disk in terms of mass, density profile, and inner and outer borders. They also match the numerical values computed with FARGO away from the outer border of the disk reasonably well. On the other hand, the predictions of the classical Mestel disk (Mestel 1963, MNRAS, 126, 553) for disks with p = 1 significantly depart from the numerical solution for radial distances beyond one-third of the disk extension because of the underlying assumption of the Mestel disk is that the outer disk border is equal to infinity. For massive bodies such as terrestrial and giant planets, the agreement of the analytical approaches is progressively poorer because of the changes in the disk structure that are induced by the planet gravity. For giant planets the precession rate changes sign and is higher than the modulus of the theoretical value by a factor ranging from 1.5 to 1.8. In this case, the correction of the formula proposed by Ward (1981) to

  5. Numerical study of RF exposure and the resulting temperature rise in the foetus during a magnetic resonance procedure

    NASA Astrophysics Data System (ADS)

    Hand, J. W.; Li, Y.; Hajnal, J. V.

    2010-02-01

    Numerical simulations of specific absorption rate (SAR) and temperature changes in a 26-week pregnant woman model within typical birdcage body coils as used in 1.5 T and 3 T MRI scanners are described. Spatial distributions of SAR and the resulting spatial and temporal changes in temperature are determined using a finite difference time domain method and a finite difference bio-heat transfer solver that accounts for discrete vessels. Heat transfer from foetus to placenta via the umbilical vein and arteries as well as that across the foetal skin/amniotic fluid/uterine wall boundaries is modelled. Results suggest that for procedures compliant with IEC normal mode conditions (maternal whole-body averaged SARMWB <= 2 W kg-1 (continuous or time-averaged over 6 min)), whole foetal SAR, local foetal SAR10g and average foetal temperature are within international safety limits. For continuous RF exposure at SARMWB = 2 W kg-1 over periods of 7.5 min or longer, a maximum local foetal temperature >38 °C may occur. However, assessment of the risk posed by such maximum temperatures predicted in a static model is difficult because of frequent foetal movement. Results also confirm that when SARMWB = 2 W kg-1, some local SAR10g values in the mother's trunk and extremities exceed recommended limits.

  6. Surface conductivity in electrokinetic systems with porous and charged interfaces: Analytical approximations and numerical results.

    PubMed

    Barbati, Alexander C; Kirby, Brian J

    2016-07-01

    We derive an approximate analytical representation of the conductivity for a 1D system with porous and charged layers grafted onto parallel plates. Our theory improves on prior work by developing approximate analytical expressions applicable over an arbitrary range of potentials, both large and small as compared to the thermal voltage (RTF). Further, we describe these results in a framework of simplifying nondimensional parameters, indicating the relative dominance of various physicochemical processes. We demonstrate the efficacy of our approximate expression with comparisons to numerical representations of the exact analytical conductivity. Finally, we utilize this conductivity expression, in concert with other components of the electrokinetic coupling matrix, to describe the streaming potential and electroviscous effect in systems with porous and charged layers.

  7. Interacting steps with finite-range interactions: Analytical approximation and numerical results

    NASA Astrophysics Data System (ADS)

    Jaramillo, Diego Felipe; Téllez, Gabriel; González, Diego Luis; Einstein, T. L.

    2013-05-01

    We calculate an analytical expression for the terrace-width distribution P(s) for an interacting step system with nearest- and next-nearest-neighbor interactions. Our model is derived by mapping the step system onto a statistically equivalent one-dimensional system of classical particles. The validity of the model is tested with several numerical simulations and experimental results. We explore the effect of the range of interactions q on the functional form of the terrace-width distribution and pair correlation functions. For physically plausible interactions, we find modest changes when next-nearest neighbor interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms.

  8. Solar flare model: Comparison of the results of numerical simulations and observations

    NASA Astrophysics Data System (ADS)

    Podgorny, I. M.; Vashenyuk, E. V.; Podgorny, A. I.

    2009-12-01

    The electrodynamic flare model is based on numerical 3D simulations with the real magnetic field of an active region. An energy of ˜1032 erg necessary for a solar flare is shown to accumulate in the magnetic field of a coronal current sheet. The thermal X-ray source in the corona results from plasma heating in the current sheet upon reconnection. The hard X-ray sources are located on the solar surface at the loop foot-points. They are produced by the precipitation of electron beams accelerated in field-aligned currents. Solar cosmic rays appear upon acceleration in the electric field along a singular magnetic X-type line. The generation mechanism of the delayed cosmic-ray component is also discussed.

  9. Conductivity and scattering in graphene bilayers: Numerically exact results versus Boltzmann approach

    NASA Astrophysics Data System (ADS)

    Xu, Hengyi; Heinzel, T.; Zozoulenko, I. V.

    2011-09-01

    We derive analytical expressions for the conductivity of bilayer graphene (BLG) using the Boltzmann approach within the the Born approximation for a model of Gaussian disorders describing both short- and long-range impurity scattering. The range of validity of the Born approximation is established by comparing the analytical results to exact tight-binding numerical calculations. A comparison of the obtained density dependencies of the conductivity with experimental data shows that the BLG samples investigated experimentally so far are in the quantum scattering regime where the Fermi wavelength exceeds the effective impurity range. In this regime both short- and long-range scattering lead to the same linear density dependence of the conductivity. Our calculations imply that bilayer and single-layer graphene have the same scattering mechanisms. We also provide an upper limit for the effective, density-dependent spatial extension of the scatterers present in the experiments.

  10. Dynamics of Tachyon Fields and Inflation - Comparison of Analytical and Numerical Results with Observation

    NASA Astrophysics Data System (ADS)

    Milošević, M.; Dimitrijević, D. D.; Djordjević, G. S.; Stojanović, M. D.

    2016-06-01

    The role tachyon fields may play in evolution of early universe is discussed in this paper. We consider the evolution of a flat and homogeneous universe governed by a tachyon scalar field with the DBI-type action and calculate the slow-roll parameters of inflation, scalar spectral index (n), and tensor-scalar ratio (r) for the given potentials. We pay special attention to the inverse power potential, first of all to V(x)˜ x^{-4}, and compare the available results obtained by analytical and numerical methods with those obtained by observation. It is shown that the computed values of the observational parameters and the observed ones are in a good agreement for the high values of the constant X_0. The possibility that influence of the radion field can extend a range of the acceptable values of the constant X_0 to the string theory motivated sector of its values is briefly considered.

  11. Medical savings accounts: microsimulation results from a model with adverse selection.

    PubMed

    Zabinski, D; Selden, T M; Moeller, J F; Banthin, J S

    1999-04-01

    This paper examines medical savings accounts combined with high-deductible catastrophic health plans (MSA/CHPs), exploring the possible consequences of making tax preferred MSA/CHPs available to the entire employment-related health insurance market. The paper uses microsimulation methods to examine the equilibrium effects of MSA/CHPs on health care and non-health care expenditures, tax revenues, insurance premiums, and exposure to risk. If MSA/CHPs are offered alongside comprehensive plans, biased MSA/CHP enrollment can lead to premium spirals that drive out comprehensive coverage. Our estimates also raise concerns about equity, insofar as those who stand to lose the most tend to be poorer and in families with infant children.

  12. Numerous Numerals.

    ERIC Educational Resources Information Center

    Henle, James M.

    This pamphlet consists of 17 brief chapters, each containing a discussion of a numeration system and a set of problems on the use of that system. The numeration systems used include Egyptian fractions, ordinary continued fractions and variants of that method, and systems using positive and negative bases. The book is informal and addressed to…

  13. Thermodiffusion in concentrated ferrofluids: Experimental and numerical results on magnetic thermodiffusion

    NASA Astrophysics Data System (ADS)

    Sprenger, Lisa; Lange, Adrian; Odenbach, Stefan

    2014-02-01

    Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: ST‖ = -0.152 K-1 and ST⊥ = -0.257 K-1 at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ‖ and ξ⊥ used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field, the parameter can be determined to ξ‖ = {2.8; 9.1; 11.2}

  14. 222Rn transport in a fractured crystalline rock aquifer: Results from numerical simulations

    USGS Publications Warehouse

    Folger, P.F.; Poeter, E.; Wanty, R.B.; Day, W.; Frishman, D.

    1997-01-01

    Dissolved 222Rn concentrations in ground water from a small wellfield underlain by fractured Middle Proterozoic Pikes Peak Granite southwest of Denver, Colorado range from 124 to 840 kBq m-3 (3360-22700 pCi L-1). Numerical simulations of flow and transport between two wells show that differences in equivalent hydraulic aperture of transmissive fractures, assuming a simplified two-fracture system and the parallel-plate model, can account for the different 222Rn concentrations in each well under steady-state conditions. Transient flow and transport simulations show that 222Rn concentrations along the fracture profile are influenced by 222Rn concentrations in the adjoining fracture and depend on boundary conditions, proximity of the pumping well to the fracture intersection, transmissivity of the conductive fractures, and pumping rate. Non-homogeneous distribution (point sources) of 222Rn parent radionuclides, uranium and 226Ra, can strongly perturb the dissolved 222Rn concentrations in a fracture system. Without detailed information on the geometry and hydraulic properties of the connected fracture system, it may be impossible to distinguish the influence of factors controlling 222Rn distribution or to determine location of 222Rn point sources in the field in areas where ground water exhibits moderate 222Rn concentrations. Flow and transport simulations of a hypothetical multifracture system consisting of ten connected fractures, each 10 m in length with fracture apertures ranging from 0.1 to 1.0 mm, show that 222Rn concentrations at the pumping well can vary significantly over time. Assuming parallel-plate flow, transmissivities of the hypothetical system vary over four orders of magnitude because transmissivity varies with the cube of fracture aperture. The extreme hydraulic heterogeneity of the simple hypothetical system leads to widely ranging 222Rn values, even assuming homogeneous distribution of uranium and 226Ra along fracture walls. Consequently, it is

  15. Newest Results from the Investigation of Polymer-Induced Drag Reduction through Direct Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Dimitropoulos, Costas D.; Beris, Antony N.; Sureshkumar, R.; Handler, Robert A.

    1998-11-01

    This work continues our attempts to elucidate theoretically the mechanism of polymer-induced drag reduction through direct numerical simulations of turbulent channel flow, using an independently evaluated rheological model for the polymer stress. Using appropriate scaling to accommodate effects due to viscoelasticity reveals that there exists a great consistency in the results for different combinations of the polymer concentration and chain extension. This helps demonstrate that our obervations are applicable to very dilute systems, currently not possible to simulate. It also reinforces the hypothesis that one of the prerequisites for the phenomenon of drag reduction is sufficiently enhanced extensional viscosity, corresponding to the level of intensity and duration of extensional rates typically encountered during the turbulent flow. Moreover, these results motivate a study of the turbulence structure at larger Reynolds numbers and for different periodic computational cell sizes. In addition, the Reynolds stress budgets demonstrate that flow elasticity adversely affects the activities represented by the pressure-strain correlations, leading to a redistribution of turbulent kinetic energy amongst all directions. Finally, we discuss the influence of viscoelasticity in reducing the production of streamwise vorticity.

  16. A collaborative accountable care model in three practices showed promising early results on costs and quality of care.

    PubMed

    Salmon, Richard B; Sanderson, Mark I; Walters, Barbara A; Kennedy, Karen; Flores, Robert C; Muney, Alan M

    2012-11-01

    Cigna's Collaborative Accountable Care initiative provides financial incentives to physician groups and integrated delivery systems to improve the quality and efficiency of care for patients in commercial open-access benefit plans. Registered nurses who serve as care coordinators employed by participating practices are a central feature of the initiative. They use patient-specific reports and practice performance reports provided by Cigna to improve care coordination, identify and close care gaps, and address other opportunities for quality improvement. We report interim quality and cost results for three geographically and structurally diverse provider practices in Arizona, New Hampshire, and Texas. Although not statistically significant, these early results revealed favorable trends in total medical costs and quality of care, suggesting that a shared-savings accountable care model and collaborative support from the payer can enable practices to take meaningful steps toward full accountability for care quality and efficiency.

  17. Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 2: numerical results

    NASA Astrophysics Data System (ADS)

    Beniaiche, Ahmed; Ghenaiet, Adel; Carcasci, Carlo; Facchini, Bruno

    2016-05-01

    This paper presents a numerical validation of the aero-thermal study of a 30:1 scaled model reproducing an innovative trailing edge with one row of enlarged pedestals under stationary and rotating conditions. A CFD analysis was performed by means of commercial ANSYS-Fluent modeling the isothermal air flow and using k-ω SST turbulence model and an isothermal air flow for both static and rotating conditions (Ro up to 0.23). The used numerical model is validated first by comparing the numerical velocity profiles distribution results to those obtained experimentally by means of PIV technique for Re = 20,000 and Ro = 0-0.23. The second validation is based on the comparison of the numerical results of the 2D HTC maps over the heated plate to those of TLC experimental data, for a smooth surface for a Reynolds number = 20,000 and 40,000 and Ro = 0-0.23. Two-tip conditions were considered: open tip and closed tip conditions. Results of the average Nusselt number inside the pedestal ducts region are presented too. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.

  18. Comparative analysis of numerical simulation and PIV experimental results for a flow caused by field-enhanced dissociation

    NASA Astrophysics Data System (ADS)

    Chirkov, V. A.; Komarov, D. K.; Stishkov, Y. K.; Vasilkov, S. A.

    2015-10-01

    The paper studies a particular electrode system, two flat parallel electrodes with a dielectric plate having a small circular hole between them. Its main feature is that the region of the strong electric field is located far from metal electrode surfaces, which permits one to preclude the injection charge formation and to observe field-enhanced dissociation (the Wien effect) leading to the emergence of electrohydrodynamic (EHD) flow. The described electrode system was studied by way of both computer simulation and experiment. The latter was conducted with the help of the particle image velocimetry (or PIV) technique. The numerical research used trusted software package COMSOL Multiphysics, which allows solving the complete set of EHD equations and obtaining the EHD flow structure. Basing on the computer simulation and the comparison with experimental investigation results, it was concluded that the Wien effect is capable of causing intense (several centimeters per second) EHD flows in low-conducting liquids and has to be taken into account when dealing with EHD devices.

  19. Compressible magnetic Rayleigh-Taylor instability in stratified plasmas: Comparison of analytical and numerical results in the linear regime

    SciTech Connect

    Liberatore, S.; Jaouen, S.; Tabakhoff, E.; Canaud, B.

    2009-04-15

    Magnetic Rayleigh-Taylor instability is addressed in compressible hydrostatic media. A full model is presented and compared to numerical results from a linear perturbation code. A perfect agreement between both approaches is obtained in a wide range of parameters. Compressibility effects are examined and substantial deviations from classical Chandrasekhar growth rates are obtained and confirmed by the model and the numerical calculations.

  20. Analysis of formation pressure test results in the Mount Elbert methane hydrate reservoir through numerical simulation

    USGS Publications Warehouse

    Kurihara, M.; Sato, A.; Funatsu, K.; Ouchi, H.; Masuda, Y.; Narita, H.; Collett, T.S.

    2011-01-01

    Targeting the methane hydrate (MH) bearing units C and D at the Mount Elbert prospect on the Alaska North Slope, four MDT (Modular Dynamic Formation Tester) tests were conducted in February 2007. The C2 MDT test was selected for history matching simulation in the MH Simulator Code Comparison Study. Through history matching simulation, the physical and chemical properties of the unit C were adjusted, which suggested the most likely reservoir properties of this unit. Based on these properties thus tuned, the numerical models replicating "Mount Elbert C2 zone like reservoir" "PBU L-Pad like reservoir" and "PBU L-Pad down dip like reservoir" were constructed. The long term production performances of wells in these reservoirs were then forecasted assuming the MH dissociation and production by the methods of depressurization, combination of depressurization and wellbore heating, and hot water huff and puff. The predicted cumulative gas production ranges from 2.16??106m3/well to 8.22??108m3/well depending mainly on the initial temperature of the reservoir and on the production method.This paper describes the details of modeling and history matching simulation. This paper also presents the results of the examinations on the effects of reservoir properties on MH dissociation and production performances under the application of the depressurization and thermal methods. ?? 2010 Elsevier Ltd.

  1. Numerical Results for a Polytropic Cosmology Interpreted as a Dust Universe Producing Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Klapp, J.; Cervantes-Cota, J.; Chauvet, P.

    1990-11-01

    RESUMEN. A nivel cosmol6gico pensamos que se ha estado prodticiendo radiaci6n gravitacional en cantidades considerables dentro de las galaxias. Si los eventos prodnctores de radiaci6n gravitatoria han venido ocurriendo desde Ia epoca de Ia formaci6n de las galaxias, cuando menos, sus efectos cosmol6gicos pueden ser tomados en cuenta con simplicidad y elegancia al representar la producci6n de radiaci6n y, por consiguiente, su interacci6n con materia ordinaria fenomenol6gicamente a trave's de una ecuaci6n de estado politr6pica, como lo hemos mostrado en otros trabajos. Presentamos en este articulo resultados nunericos de este modelo. ABSTRACT A common believe in cosmology is that gravitational radiation in considerable quantities is being produced within the galaxies. Ifgravitational radiation production has been running since the galaxy formation epoch, at least, its cosmological effects can be assesed with simplicity and elegance by representing the production of radiation and, therefore, its interaction with ordinary matter phenomenologically through a polytropic equation of state as shown already elsewhere. We present in this paper the numerical results of such a model. K words: COSMOLOGY - GRAVITATION

  2. Intra-cratonic melting as a result of delamination of mantle lithosphere - insight from numerical modelling

    NASA Astrophysics Data System (ADS)

    Gorczyk, W.; Vogt, K.; Gerya, T.; Hobbs, B. E.

    2012-12-01

    It is becoming increasingly apparent that intense deformation, metamorphism and metasomatism occur within continental cratonic blocks far removed form subducting margins Such changes may occur intra-cratonically arising from lithospheric thickening and the development of gravitational instabilities, but mostly occur at the boundary of cratonic blocks. The contact of two cratons is characterized by rheological lateral variations within mantle-lithosphere and overlying crust. Tectonic stresses acting on craton/craton boundaries may lead to thinning or thickening due to delamination of the mantle lithosphere. This is reflected in tectonic deformation, topography evolution, melting and crustal metamorphism. To understand the controls on these processes a number of 2D, coupled petrological thermo-mechanical numerical experiments has been performed to test the response of a laterally weakened zone to a compressional regime. The results indicate that the presence of water-bearing minerals in the lithosphere and lower crust is essential to initiate melting, which in the later stages may expand to dry melting of crust and mantle. In the case of anhydrous crust and lithosphere, no melting occurs. Thus a variety of instabilities, melting behaviour and topographic responses occurs at the base of the lithosphere as well as intensive faulting and buckling in the crust dependent on the strength and "water" content of the lithosphere.

  3. Thermodiffusion in concentrated ferrofluids: Experimental and numerical results on magnetic thermodiffusion

    SciTech Connect

    Sprenger, Lisa Lange, Adrian; Odenbach, Stefan

    2014-02-15

    Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: S{sub T‖} = −0.152 K{sup −1} and S{sub T⊥} = −0.257 K{sup −1} at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ{sub ‖} and ξ{sub ⊥} used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field, the parameter can

  4. Active behavior of abdominal wall muscles: Experimental results and numerical model formulation.

    PubMed

    Grasa, J; Sierra, M; Lauzeral, N; Muñoz, M J; Miana-Mena, F J; Calvo, B

    2016-08-01

    In the present study a computational finite element technique is proposed to simulate the mechanical response of muscles in the abdominal wall. This technique considers the active behavior of the tissue taking into account both collagen and muscle fiber directions. In an attempt to obtain the computational response as close as possible to real muscles, the parameters needed to adjust the mathematical formulation were determined from in vitro experimental tests. Experiments were conducted on male New Zealand White rabbits (2047±34g) and the active properties of three different muscles: Rectus Abdominis, External Oblique and multi-layered samples formed by three muscles (External Oblique, Internal Oblique, and Transversus Abdominis) were characterized. The parameters obtained for each muscle were incorporated into a finite strain formulation to simulate active behavior of muscles incorporating the anisotropy of the tissue. The results show the potential of the model to predict the anisotropic behavior of the tissue associated to fibers and how this influences on the strain, stress and generated force during an isometric contraction. PMID:27111629

  5. Active behavior of abdominal wall muscles: Experimental results and numerical model formulation.

    PubMed

    Grasa, J; Sierra, M; Lauzeral, N; Muñoz, M J; Miana-Mena, F J; Calvo, B

    2016-08-01

    In the present study a computational finite element technique is proposed to simulate the mechanical response of muscles in the abdominal wall. This technique considers the active behavior of the tissue taking into account both collagen and muscle fiber directions. In an attempt to obtain the computational response as close as possible to real muscles, the parameters needed to adjust the mathematical formulation were determined from in vitro experimental tests. Experiments were conducted on male New Zealand White rabbits (2047±34g) and the active properties of three different muscles: Rectus Abdominis, External Oblique and multi-layered samples formed by three muscles (External Oblique, Internal Oblique, and Transversus Abdominis) were characterized. The parameters obtained for each muscle were incorporated into a finite strain formulation to simulate active behavior of muscles incorporating the anisotropy of the tissue. The results show the potential of the model to predict the anisotropic behavior of the tissue associated to fibers and how this influences on the strain, stress and generated force during an isometric contraction.

  6. Atmospheric turbulence in complex terrain: Verifying numerical model results with observations by remote-sensing instruments

    NASA Astrophysics Data System (ADS)

    Chan, P. W.

    2009-03-01

    The Hong Kong International Airport (HKIA) is situated in an area of complex terrain. Turbulent flow due to terrain disruption could occur in the vicinity of HKIA when winds from east to southwest climb over Lantau Island, a mountainous island to the south of the airport. Low-level turbulence is an aviation hazard to the aircraft flying into and out of HKIA. It is closely monitored using remote-sensing instruments including Doppler LIght Detection And Ranging (LIDAR) systems and wind profilers in the airport area. Forecasting of low-level turbulence by numerical weather prediction models would be useful in the provision of timely turbulence warnings to the pilots. The feasibility of forecasting eddy dissipation rate (EDR), a measure of turbulence intensity adopted in the international civil aviation community, is studied in this paper using the Regional Atmospheric Modelling System (RAMS). Super-high resolution simulation (within the regime of large eddy simulation) is performed with a horizontal grid size down to 50 m for some typical cases of turbulent airflow at HKIA, such as spring-time easterly winds in a stable boundary layer and gale-force southeasterly winds associated with a typhoon. Sensitivity of the simulation results with respect to the choice of turbulent kinetic energy (TKE) parameterization scheme in RAMS is also examined. RAMS simulation with Deardorff (1980) TKE scheme is found to give the best result in comparison with actual EDR observations. It has the potential for real-time forecasting of low-level turbulence in short-term aviation applications (viz. for the next several hours).

  7. A Hydrodynamic Theory for Spatially Inhomogeneous Semiconductor Lasers. 2; Numerical Results

    NASA Technical Reports Server (NTRS)

    Li, Jianzhong; Ning, C. Z.; Biegel, Bryan A. (Technical Monitor)

    2001-01-01

    We present numerical results of the diffusion coefficients (DCs) in the coupled diffusion model derived in the preceding paper for a semiconductor quantum well. These include self and mutual DCs in the general two-component case, as well as density- and temperature-related DCs under the single-component approximation. The results are analyzed from the viewpoint of free Fermi gas theory with many-body effects incorporated. We discuss in detail the dependence of these DCs on densities and temperatures in order to identify different roles played by the free carrier contributions including carrier statistics and carrier-LO phonon scattering, and many-body corrections including bandgap renormalization and electron-hole (e-h) scattering. In the general two-component case, it is found that the self- and mutual- diffusion coefficients are determined mainly by the free carrier contributions, but with significant many-body corrections near the critical density. Carrier-LO phonon scattering is dominant at low density, but e-h scattering becomes important in determining their density dependence above the critical electron density. In the single-component case, it is found that many-body effects suppress the density coefficients but enhance the temperature coefficients. The modification is of the order of 10% and reaches a maximum of over 20% for the density coefficients. Overall, temperature elevation enhances the diffusive capability or DCs of carriers linearly, and such an enhancement grows with density. Finally, the complete dataset of various DCs as functions of carrier densities and temperatures provides necessary ingredients for future applications of the model to various spatially inhomogeneous optoelectronic devices.

  8. Numerical and experimental results on the spectral wave transfer in finite depth

    NASA Astrophysics Data System (ADS)

    Benassai, Guido

    2016-04-01

    Determination of the form of the one-dimensional surface gravity wave spectrum in water of finite depth is important for many scientific and engineering applications. Spectral parameters of deep water and intermediate depth waves serve as input data for the design of all coastal structures and for the description of many coastal processes. Moreover, the wave spectra are given as an input for the response and seakeeping calculations of high speed vessels in extreme sea conditions and for reliable calculations of the amount of energy to be extracted by wave energy converters (WEC). Available data on finite depth spectral form is generally extrapolated from parametric forms applicable in deep water (e.g., JONSWAP) [Hasselmann et al., 1973; Mitsuyasu et al., 1980; Kahma, 1981; Donelan et al., 1992; Zakharov, 2005). The present paper gives a contribution in this field through the validation of the offshore energy spectra transfer from given spectral forms through the measurement of inshore wave heights and spectra. The wave spectra on deep water were recorded offshore Ponza by the Wave Measurement Network (Piscopia et al.,2002). The field regressions between the spectral parameters, fp and the nondimensional energy with the fetch length were evaluated for fetch-limited sea conditions. These regressions gave the values of the spectral parameters for the site of interest. The offshore wave spectra were transfered from the measurement station offshore Ponza to a site located offshore the Gulf of Salerno. The offshore local wave spectra so obtained were transfered on the coastline with the TMA model (Bouws et al., 1985). Finally the numerical results, in terms of significant wave heights, were compared with the wave data recorded by a meteo-oceanographic station owned by Naples Hydrographic Office on the coastline of Salerno in 9m depth. Some considerations about the wave energy to be potentially extracted by Wave Energy Converters were done and the results were discussed.

  9. "It's Not All about Grades": Accounting for Gendered Degree Results in Geography at Brunel University

    ERIC Educational Resources Information Center

    Smith, Fiona

    2004-01-01

    This paper explores the results of an 18-month study at Brunel University that aimed to explain the significant gendered differences in academic performance amongst geography students. Male students are doing considerably less well than their female peers, being awarded far fewer first class and upper second class degrees, a phenomenon that cannot…

  10. Numerical modeling of 1D heterogeneous combustion in porous media under free convection taking into account dependence of permeability on porosity

    NASA Astrophysics Data System (ADS)

    Lutsenko, N. A.

    2016-06-01

    Using numerical experiment the one-dimensional unsteady process of heterogeneous combustion in porous object under free convection is considered when the dependence of permeability on porosity is taken into account. The combustion is due to exothermic reaction between the fuel in the solid porous medium and oxidizer contained in the gas flowing through the porous object. In the present work the process is considered under natural convection, i.e. when the flow rate and velocity of the gas at the inlet to the porous objects are unknown, but the gas pressure at object boundaries is known. The influence of changing of permeability due to the changing of porosity on the solution is investigated using original numerical method, which is based on a combination of explicit and implicit finite-difference schemes. It was shown that taking into account the dependence of permeability on porosity, which is described by some known equations, can significantly change the solution in one-dimensional case. The changing of permeability due to the changing of porosity leads to the speed increasing of both cocurrent and the countercurrent combustion waves, and to the temperature increasing in the combustion zone of countercurrent combustion wave.

  11. THE 2D HEISENBERG ANTIFERROMAGNET IN HIGH-Tc SUPERCONDUCTIVITY:. A Review of Numerical Techniques and Results

    NASA Astrophysics Data System (ADS)

    Barnes, T.

    In this article we review numerical studies of the quantum Heisenberg antiferromagnet on a square lattice, which is a model of the magnetic properties of the undoped “precursor insulators” of the high temperature superconductors. We begin with a brief pedagogical introduction and then discuss zero and nonzero temperature properties and compare the numerical results to analytical calculations and to experiment where appropriate. We also review the various algorithms used to obtain these results, and discuss algorithm developments and improvements in computer technology which would be most useful for future numerical work in this area. Finally we list several outstanding problems which may merit further investigation.

  12. Effects of heterogeneity in aquifer permeability and biomass on biodegradation rate calculations - Results from numerical simulations

    USGS Publications Warehouse

    Scholl, M.A.

    2000-01-01

    Numerical simulations were used to examine the effects of heterogeneity in hydraulic conductivity (K) and intrinsic biodegradation rate on the accuracy of contaminant plume-scale biodegradation rates obtained from field data. The simulations were based on a steady-state BTEX contaminant plume-scale biodegradation under sulfate-reducing conditions, with the electron acceptor in excess. Biomass was either uniform or correlated with K to model spatially variable intrinsic biodegradation rates. A hydraulic conductivity data set from an alluvial aquifer was used to generate three sets of 10 realizations with different degrees of heterogeneity, and contaminant transport with biodegradation was simulated with BIOMOC. Biodegradation rates were calculated from the steady-state contaminant plumes using decreases in concentration with distance downgradient and a single flow velocity estimate, as is commonly done in site characterization to support the interpretation of natural attenuation. The observed rates were found to underestimate the actual rate specified in the heterogeneous model in all cases. The discrepancy between the observed rate and the 'true' rate depended on the ground water flow velocity estimate, and increased with increasing heterogeneity in the aquifer. For a lognormal K distribution with variance of 0.46, the estimate was no more than a factor of 1.4 slower than the true rate. For aquifer with 20% silt/clay lenses, the rate estimate was as much as nine times slower than the true rate. Homogeneous-permeability, uniform-degradation rate simulations were used to generate predictions of remediation time with the rates estimated from heterogeneous models. The homogeneous models were generally overestimated the extent of remediation or underestimated remediation time, due to delayed degradation of contaminants in the low-K areas. Results suggest that aquifer characterization for natural attenuation at contaminated sites should include assessment of the presence

  13. Recombination in liquid filled ionisation chambers with multiple charge carrier species: Theoretical and numerical results

    NASA Astrophysics Data System (ADS)

    Aguiar, P.; González-Castaño, D. M.; Gómez, F.; Pardo-Montero, J.

    2014-10-01

    Liquid-filled ionisation chambers (LICs) are used in radiotherapy for dosimetry and quality assurance. Volume recombination can be quite important in LICs for moderate dose rates, causing non-linearities in the dose rate response of these detectors, and needs to be corrected for. This effect is usually described with Greening and Boag models for continuous and pulsed radiation respectively. Such models assume that the charge is carried by two different species, positive and negative ions, each of those species with a given mobility. However, LICs operating in non-ultrapure mode can contain different types of electronegative impurities with different mobilities, thus increasing the number of different charge carriers. If this is the case, Greening and Boag models can be no longer valid and need to be reformulated. In this work we present a theoretical and numerical study of volume recombination in parallel-plate LICs with multiple charge carrier species, extending Boag and Greening models. Results from a recent publication that reported three different mobilities in an isooctane-filled LIC have been used to study the effect of extra carrier species on recombination. We have found that in pulsed beams the inclusion of extra mobilities does not affect volume recombination much, a behaviour that was expected because Boag formula for charge collection efficiency does not depend on the mobilities of the charge carriers if the Debye relationship between mobilities and recombination constant holds. This is not the case in continuous radiation, where the presence of extra charge carrier species significantly affects the amount of volume recombination.

  14. Preliminary results of numerical investigations at SECARB Cranfield, MS field test site

    NASA Astrophysics Data System (ADS)

    Choi, J.; Nicot, J.; Meckel, T. A.; Chang, K.; Hovorka, S. D.

    2008-12-01

    The Southeast Regional Carbon Sequestration partnership sponsored by DOE has chosen the Cranfield, MS field as a test site for its Phase II experiment. It will provide information on CO2 storage in oil and gas fields, in particular on storage permanence, storage capacity, and pressure buildup as well as on sweep efficiency. The 10,300 ft-deep reservoir produced 38 MMbbl of oil and 677 MMSCF of gas from the 1940's to the 1960's and is being retrofitted by Denbury Resources for tertiary recovery. CO2 injection started in July 2008 with a scheduled ramp up during the next few months. The Cranfield modeling team selected the northern section of the field for development of a numerical model using the multiphase-flow, compositional CMG-GEM software. Model structure was determined through interpretation of logs from old and recently-drilled wells and geophysical data. PETREL was used to upscale and export permeability and porosity data to the GEM model. Preliminary sensitivity analyses determined that relative permeability parameters and oil composition had the largest impact on CO2 behavior. The first modeling step consisted in history-matching the total oil, gas, and water production out of the reservoir starting from its natural state to determine the approximate current conditions of the reservoir. The fact that pressure recovered in the 40 year interval since end of initial production helps in constraining boundary conditions. In a second step, the modeling focused on understanding pressure evolution and CO2 transport in the reservoir. The presentation will introduce preliminary results of the simulations and confirm/explain discrepancies with field measurements.

  15. Accounting for vulnerable populations in rural hazard mitigation plans: results of a survey of emergency managers.

    PubMed

    Horney, Jennifer A; Nguyen, Mai; Cooper, John; Simon, Matthew; Ricchetti-Masterson, Kristen; Grabich, Shannon; Salvesen, David; Berke, Philip

    2013-01-01

    Rural areas of the United States are uniquely vulnerable to the impacts of natural disasters. One possible way to mitigate vulnerability to disasters in rural communities is to have a high-quality hazard mitigation plan in place. To understand the resources available for hazard mitigation planning and determine how well hazard mitigation plans in rural counties meet the needs of vulnerable populations, we surveyed the lead planning or emergency management official responsible for hazard mitigation plans in 96 rural counties in eight states in the Southeastern United States. In most counties, emergency management was responsible for implementing the county's hazard mitigation plan and the majority of counties had experienced a presidentially declared disaster in the last 5 years. Our research findings demonstrated that there were differences in subjective measures of vulnerability (as reported by survey respondents) and objective measures of vulnerability (as determined by US Census data). In addition, although few counties surveyed included outreach to vulnerable groups as a part of their hazard mitigation planning process, a majority felt that their hazard mitigation plan addressed the needs of vulnerable populations "well" or "very well." These differences could result in increased vulnerabilities in rural areas, particularly for certain vulnerable groups.

  16. On the anomalies in gravity associated with lateral inhomogeneities in temperature: 2. Numerical results

    NASA Astrophysics Data System (ADS)

    Gliko, A. O.; Molodenskii, S. M.

    2015-01-01

    ) are not only capable of significantly changing the magnitude of the radial displacements of the geoid but also altering their sign. Moreover, even in the uniform Earth's model, the effects of sphericity of its external surface and self-gravitation can also provide a noticeable contribution, which determines the signs of the coefficients in the expansion of the geoid's shape in the lower-order spherical functions. In order to separate these effects, below we present the results of the numerical calculations of the total effects of thermoelastic deformations for the two simplest models of spherical Earth without and with self-gravitation with constant density and complex-valued shear moduli and for the real Earth PREM model (which describes the depth distributions of density and elastic moduli for the high-frequency oscillations disregarding the rheology of the medium) and the modern models of the mantle rheology. Based on the calculations, we suggest the simplest interpretation of the present-day data on the relationship between the coefficients of spherical expansion of temperature, velocities of seismic body waves, the topography of the Earth's surface and geoid, and the data on the correlation between the lower-order coefficients in the expansions of the geoid and the corresponding terms of the expansions of horizontal inhomogeneities in seismic velocities. The suggested interpretation includes the estimates of the sign and magnitude for the ratios between the first coefficients of spherical expansions of seismic velocities, topography, and geoid. The presence of this correlation and the relationship between the signs and absolute values of these coefficients suggests that both the long-period oscillations of the geoid and the long-period variations in the velocities of seismic body waves are largely caused by thermoelastic deformations.

  17. Chaotic scattering in an open vase-shaped cavity: Topological, numerical, and experimental results

    NASA Astrophysics Data System (ADS)

    Novick, Jaison Allen

    We present a study of trajectories in a two-dimensional, open, vase-shaped cavity in the absence of forces The classical trajectories freely propagate between elastic collisions. Bound trajectories, regular scattering trajectories, and chaotic scattering trajectories are present in the vase. Most importantly, we find that classical trajectories passing through the vase's mouth escape without return. In our simulations, we propagate bursts of trajectories from point sources located along the vase walls. We record the time for escaping trajectories to pass through the vase's neck. Constructing a plot of escape time versus the initial launch angle for the chaotic trajectories reveals a vastly complicated recursive structure or a fractal. This fractal structure can be understood by a suitable coordinate transform. Reducing the dynamics to two dimensions reveals that the chaotic dynamics are organized by a homoclinic tangle, which is formed by the union of infinitely long, intersecting stable and unstable manifolds. This study is broken down into three major components. We first present a topological theory that extracts the essential topological information from a finite subset of the tangle and encodes this information in a set of symbolic dynamical equations. These equations can be used to predict a topologically forced minimal subset of the recursive structure seen in numerically computed escape time plots. We present three applications of the theory and compare these predictions to our simulations. The second component is a presentation of an experiment in which the vase was constructed from Teflon walls using an ultrasound transducer as a point source. We compare the escaping signal to a classical simulation and find agreement between the two. Finally, we present an approximate solution to the time independent Schrodinger Equation for escaping waves. We choose a set of points at which to evaluate the wave function and interpolate trajectories connecting the source

  18. Modeling the Fracturing of Rock by Fluid Injection - Comparison of Numerical and Experimental Results

    NASA Astrophysics Data System (ADS)

    Heinze, Thomas; Galvan, Boris; Miller, Stephen

    2013-04-01

    Fluid-rock interactions are mechanically fundamental to many earth processes, including fault zones and hydrothermal/volcanic systems, and to future green energy solutions such as enhanced geothermal systems and carbon capture and storage (CCS). Modeling these processes is challenging because of the strong coupling between rock fracture evolution and the consequent large changes in the hydraulic properties of the system. In this talk, we present results of a numerical model that includes poro-elastic plastic rheology (with hardening, softening, and damage), and coupled to a non-linear diffusion model for fluid pressure propagation and two-phase fluid flow. Our plane strain model is based on the poro- elastic plastic behavior of porous rock and is advanced with hardening, softening and damage using the Mohr- Coulomb failure criteria. The effective stress model of Biot (1944) is used for coupling the pore pressure and the rock behavior. Frictional hardening and cohesion softening are introduced following Vermeer and de Borst (1984) with the angle of internal friction and the cohesion as functions of the principal strain rates. The scalar damage coefficient is assumed to be a linear function of the hardening parameter. Fluid injection is modeled as a two phase mixture of water and air using the Richards equation. The theoretical model is solved using finite differences on a staggered grid. The model is benchmarked with experiments on the laboratory scale in which fluid is injected from below in a critically-stressed, dry sandstone (Stanchits et al. 2011). We simulate three experiments, a) the failure a dry specimen due to biaxial compressive loading, b) the propagation a of low pressure fluid front induced from the bottom in a critically stressed specimen, and c) the failure of a critically stressed specimen due to a high pressure fluid intrusion. Comparison of model results with the fluid injection experiments shows that the model captures most of the experimental

  19. Soliton-collision interferometer for the quantum nondemolition measurement of photon number: numerical results

    SciTech Connect

    Sakai, Y. Telephone Corporation, Musashino-shi, Tokyo 180 ); Hawkins, R.J. ); Friberg, S.R. Telephone Corporation, Musashino-shi, Tokyo 180 )

    1990-02-15

    Using analytic theory and numerical experiments, we show that a quantum nondemolition measurement of the photon number of optical solitons in a single-mode optical fiber can be made. We describe the soliton-collision interferometer with which we propose to make this measurement and discuss simulations of the performance of this interferometer.

  20. Chaotic structures of nonlinear magnetic fields. I - Theory. II - Numerical results

    NASA Technical Reports Server (NTRS)

    Lee, Nam C.; Parks, George K.

    1992-01-01

    A study of the evolutionary properties of nonlinear magnetic fields in flowing MHD plasmas is presented to illustrate that nonlinear magnetic fields may involve chaotic dynamics. It is shown how a suitable transformation of the coupled equations leads to Duffing's form, suggesting that the behavior of the general solution can also be chaotic. Numerical solutions of the nonlinear magnetic field equations that have been cast in the form of Duffing's equation are presented.

  1. A numerical modelling technique that can account for alternations of uplift and subsidence revealed by Late Cenozoic fluvial sequences

    NASA Astrophysics Data System (ADS)

    Westaway, Rob

    2012-09-01

    Alternations between fluvial incision and aggradation, in response to switches between uplift and subsidence and occurring over timescales of many hundreds of thousands of years, have been documented in many regions worldwide, contrasting markedly with the monotonic histories of uplift or subsidence evident elsewhere. It has been noted that this pattern of reversals in vertical crustal motion is only observed in regions where the mobile lower-crustal layer is thin, ≤ 6 km thick, suggesting a cause-and-effect connection with the physical properties of the underlying continental lithosphere. It is proposed that these reversals result from the interplay between the isostatic responses to erosional unloading by lower-crustal flow and by mantle lithosphere relaxation. Estimates of the characteristic timescale for relaxation of the continental mantle lithosphere range from several hundred thousand years in regions of ‘cold' crust, with a thin mobile lower-crustal layer, to a few tens of thousands of years in regions of ‘hot' crust, where the mobile lower-crustal layer is thicker. In regions of hot crust, relaxation of the mantle lithosphere requires a shorter characteristic timescale than flow within the lower crust. The complex interaction between these processes means that isostatic compensation of crustal thickening in regions of hot crust will typically involve surface uplift, the development of a lower-crustal ‘root', and thinning of the mantle lithosphere. The observation of alternations between uplift and subsidence in long-timescale fluvial sequences and the proposed physical interpretation demonstrate the importance of fluvial records for providing unique, high-resolution control on deformation of the continental lithosphere and for constraining its layered rheology.

  2. Accountability for All: Results from a Study on Accountability Policies Affecting Students with Disabilities Educated in Special Schools and Settings. Topical Review Six.

    ERIC Educational Resources Information Center

    Kyle, Stacey J.; Papadopoulou, Eleni; McLaughlin, Margaret J.

    2004-01-01

    The purpose of this topical review is to examine the current state of accountability policies that impact students with disabilities who are educated in special schools and settings. For the purpose of this review, special schools and settings are defined as public or private settings outside of comprehensive K-12 school buildings. This review…

  3. Ponderomotive stabilization of flute modes in mirrors Feedback control and numerical results

    NASA Technical Reports Server (NTRS)

    Similon, P. L.

    1987-01-01

    Ponderomotive stabilization of rigid plasma flute modes is numerically investigated by use of a variational principle, for a simple geometry, without eikonal approximation. While the near field of the studied antenna can be stabilizing, the far field has a small contribution only, because of large cancellation by quasi mode-coupling terms. The field energy for stabilization is evaluated and is a nonnegligible fraction of the plasma thermal energy. A new antenna design is proposed, and feedback stabilization is investigated. Their use drastically reduces power requirements.

  4. Estimation of geopotential from satellite-to-satellite range rate data: Numerical results

    NASA Technical Reports Server (NTRS)

    Thobe, Glenn E.; Bose, Sam C.

    1987-01-01

    A technique for high-resolution geopotential field estimation by recovering the harmonic coefficients from satellite-to-satellite range rate data is presented and tested against both a controlled analytical simulation of a one-day satellite mission (maximum degree and order 8) and then against a Cowell method simulation of a 32-day mission (maximum degree and order 180). Innovations include: (1) a new frequency-domain observation equation based on kinetic energy perturbations which avoids much of the complication of the usual Keplerian element perturbation approaches; (2) a new method for computing the normalized inclination functions which unlike previous methods is both efficient and numerically stable even for large harmonic degrees and orders; (3) the application of a mass storage FFT to the entire mission range rate history; (4) the exploitation of newly discovered symmetries in the block diagonal observation matrix which reduce each block to the product of (a) a real diagonal matrix factor, (b) a real trapezoidal factor with half the number of rows as before, and (c) a complex diagonal factor; (5) a block-by-block least-squares solution of the observation equation by means of a custom-designed Givens orthogonal rotation method which is both numerically stable and tailored to the trapezoidal matrix structure for fast execution.

  5. Interaction of a mantle plume and a segmented mid-ocean ridge: Results from numerical modeling

    NASA Astrophysics Data System (ADS)

    Georgen, Jennifer E.

    2014-04-01

    Previous investigations have proposed that changes in lithospheric thickness across a transform fault, due to the juxtaposition of seafloor of different ages, can impede lateral dispersion of an on-ridge mantle plume. The application of this “transform damming” mechanism has been considered for several plume-ridge systems, including the Reunion hotspot and the Central Indian Ridge, the Amsterdam-St. Paul hotspot and the Southeast Indian Ridge, the Cobb hotspot and the Juan de Fuca Ridge, the Iceland hotspot and the Kolbeinsey Ridge, the Afar plume and the ridges of the Gulf of Aden, and the Marion/Crozet hotspot and the Southwest Indian Ridge. This study explores the geodynamics of the transform damming mechanism using a three-dimensional finite element numerical model. The model solves the coupled steady-state equations for conservation of mass, momentum, and energy, including thermal buoyancy and viscosity that is dependent on pressure and temperature. The plume is introduced as a circular thermal anomaly on the bottom boundary of the numerical domain. The center of the plume conduit is located directly beneath a spreading segment, at a distance of 200 km (measured in the along-axis direction) from a transform offset with length 100 km. Half-spreading rate is 0.5 cm/yr. In a series of numerical experiments, the buoyancy flux of the modeled plume is progressively increased to investigate the effects on the temperature and velocity structure of the upper mantle in the vicinity of the transform. Unlike earlier studies, which suggest that a transform always acts to decrease the along-axis extent of plume signature, these models imply that the effect of a transform on plume dispersion may be complex. Under certain ranges of plume flux modeled in this study, the region of the upper mantle undergoing along-axis flow directed away from the plume could be enhanced by the three-dimensional velocity and temperature structure associated with ridge

  6. Recent numerical results on double-layer simulation in high-intensity laser--plasma interaction

    SciTech Connect

    Szichman, H.

    1988-06-01

    Numerical studies on dynamic electric fields and double layers created inside of plasmas irradiated at laser intensities of 10/sup 17/ and 10/sup 18/ Wcm/sup 2/ were carried out using a macroscopic two-fluid model including nonlinear forces and the complete intensity dependent optical response for heating and dielectric force effects. This was possible only by longer computation times since the temporal and spatial step sizes had to be reduced accordingly. Electrostatic fields as high as 10/sup 9/ and 10/sup 10/ Vcm were, respectively, measured for both laser intensities and the coupling of irradiated electromagnetic waves to generate Langmuir longitudinal waves is shown to be possible for the first time. The development and production of the well-known density minima (cavitons) because of nonlinear forces is also confirmed, their prominent appearance being in direct relation to the stronger effect of the high irradiances applied.

  7. Distribution of Steps with Finite-Range Interactions: Analytic Approximations and Numerical Results

    NASA Astrophysics Data System (ADS)

    GonzáLez, Diego Luis; Jaramillo, Diego Felipe; TéLlez, Gabriel; Einstein, T. L.

    2013-03-01

    While most Monte Carlo simulations assume only nearest-neighbor steps interact elastically, most analytic frameworks (especially the generalized Wigner distribution) posit that each step elastically repels all others. In addition to the elastic repulsions, we allow for possible surface-state-mediated interactions. We investigate analytically and numerically how next-nearest neighbor (NNN) interactions and, more generally, interactions out to q'th nearest neighbor alter the form of the terrace-width distribution and of pair correlation functions (i.e. the sum over n'th neighbor distribution functions, which we investigated recently.[2] For physically plausible interactions, we find modest changes when NNN interactions are included and generally negligible changes when more distant interactions are allowed. We discuss methods for extracting from simulated experimental data the characteristic scale-setting terms in assumed potential forms.

  8. The spectroscopic search for the trace aerosols in the planetary atmospheres - the results of numerical simulations

    NASA Astrophysics Data System (ADS)

    Blecka, Maria I.

    2010-05-01

    The passive remote spectrometric methods are important in examinations the atmospheres of planets. The radiance spectra inform us about values of thermodynamical parameters and composition of the atmospheres and surfaces. The spectral technology can be useful in detection of the trace aerosols like biological substances (if present) in the environments of the planets. We discuss here some of the aspects related to the spectroscopic search for the aerosols and dust in planetary atmospheres. Possibility of detection and identifications of biological aerosols with a passive InfraRed spectrometer in an open-air environment is discussed. We present numerically simulated, based on radiative transfer theory, spectroscopic observations of the Earth atmosphere. Laboratory measurements of transmittance of various kinds of aerosols, pollens and bacterias were used in modeling.

  9. Recent structure of the lithosphere beneath Siberia and surrounding areas based on the results of seismic tomography and numerical thermo-gravity modeling

    NASA Astrophysics Data System (ADS)

    Bushenkova, N.; Chervov, V.; Koulakov, I.

    2010-12-01

    In this study we investigate recent structure of the lithosphere and dynamics of the sub-lithosphere mantle beneath a large part of Eurasia based on results of seismic tomography and numerical modeling. The study area includes rigid old lithospheric blocks, such as Siberian Craton, Tarim plate, remnant parts of the Tuva-Mongolia continent, as well as more recent structures such as West-Siberian plate and orogenic belts in southern Siberia. Thickness of the lithosphere was estimated based on the regional tomographic model by Koulakov and Bushenkova (2010) using a method described by Bushenkova et al., (2008). These estimates were used to define the boundary conditions in numerical modeling. To reduce the marginal effects, the modeling area was considerably enlarged with Russian, North- and South China plates. However, the Indian plate and its movement were not taken into account in this model. The numerical modeling was performed in a spherical segment limited by latitude 0 E-150 E, longitude 0-80 N and depth 0-700 km using a regular grid of 151x81x36 and time step of 10 Ma. Here we solve numerically the Navier-Stokes equations using the Oberbeck-Boussinesq approximation in spherical coordinates. In our model viscosity depends on the pressure and temperature. The modeling shows that ascending flows and higher temperature (up to 100 degrees) are usually associated with thick lithosphere of cratons. These flows determine the shapes of convective cells far outside the craton and generate another ascending flow in non-cratonic areas. The areas with thin lithosphere are usually associated with descending flows and colder mantle. One of examples is an area between Siberian craton to the north and Tarim and North China plates to the south where the estimated thickness of the lithosphere is between 40-75 km. There we observe descending flows in the numerical model and lower temperatures according to the tomography result. Besides the tomography results, the numerical model

  10. Sound absorption of porous substrates covered by foliage: experimental results and numerical predictions.

    PubMed

    Ding, Lei; Van Renterghem, Timothy; Botteldooren, Dick; Horoshenkov, Kirill; Khan, Amir

    2013-12-01

    The influence of loose plant leaves on the acoustic absorption of a porous substrate is experimentally and numerically studied. Such systems are typical in vegetative walls, where the substrate has strong acoustical absorbing properties. Both experiments in an impedance tube and theoretical predictions show that when a leaf is placed in front of such a porous substrate, its absorption characteristics markedly change (for normal incident sound). Typically, there is an unaffected change in the low frequency absorption coefficient (below 250 Hz), an increase in the middle frequency absorption coefficient (500-2000 Hz) and a decrease in the absorption at higher frequencies. The influence of leaves becomes most pronounced when the substrate has a low mass density. A combination of the Biot's elastic frame porous model, viscous damping in the leaf boundary layers and plate vibration theory is implemented via a finite-difference time-domain model, which is able to predict accurately the absorption spectrum of a leaf above a porous substrate system. The change in the absorption spectrum caused by the leaf vibration can be modeled reasonably well assuming the leaf and porous substrate properties are uniform.

  11. Displacement-Based Seismic Design Procedure for Framed Buildings with Dissipative Braces Part II: Numerical Results

    SciTech Connect

    Mazza, Fabio; Vulcano, Alfonso

    2008-07-08

    For a widespread application of dissipative braces to protect framed buildings against seismic loads, practical and reliable design procedures are needed. In this paper a design procedure based on the Direct Displacement-Based Design approach is adopted, assuming the elastic lateral storey-stiffness of the damped braces proportional to that of the unbraced frame. To check the effectiveness of the design procedure, presented in an associate paper, a six-storey reinforced concrete plane frame, representative of a medium-rise symmetric framed building, is considered as primary test structure; this structure, designed in a medium-risk region, is supposed to be retrofitted as in a high-risk region, by insertion of diagonal braces equipped with hysteretic dampers. A numerical investigation is carried out to study the nonlinear static and dynamic responses of the primary and the damped braced test structures, using step-by-step procedures described in the associate paper mentioned above; the behaviour of frame members and hysteretic dampers is idealized by bilinear models. Real and artificial accelerograms, matching EC8 response spectrum for a medium soil class, are considered for dynamic analyses.

  12. Displacement-Based Seismic Design Procedure for Framed Buildings with Dissipative Braces Part II: Numerical Results

    NASA Astrophysics Data System (ADS)

    Mazza, Fabio; Vulcano, Alfonso

    2008-07-01

    For a widespread application of dissipative braces to protect framed buildings against seismic loads, practical and reliable design procedures are needed. In this paper a design procedure based on the Direct Displacement-Based Design approach is adopted, assuming the elastic lateral storey-stiffness of the damped braces proportional to that of the unbraced frame. To check the effectiveness of the design procedure, presented in an associate paper, a six-storey reinforced concrete plane frame, representative of a medium-rise symmetric framed building, is considered as primary test structure; this structure, designed in a medium-risk region, is supposed to be retrofitted as in a high-risk region, by insertion of diagonal braces equipped with hysteretic dampers. A numerical investigation is carried out to study the nonlinear static and dynamic responses of the primary and the damped braced test structures, using step-by-step procedures described in the associate paper mentioned above; the behaviour of frame members and hysteretic dampers is idealized by bilinear models. Real and artificial accelerograms, matching EC8 response spectrum for a medium soil class, are considered for dynamic analyses.

  13. Preliminary Results from Numerical Experiments on the Summer 1980 Heat Wave and Drought

    NASA Technical Reports Server (NTRS)

    Wolfson, N.; Atlas, R.; Sud, Y. C.

    1985-01-01

    During the summer of 1980, a prolonged heat wave and drought affected the United States. A preliminary set of experiments has been conducted to study the effect of varying boundary conditions on the GLA model simulation of the heat wave. Five 10-day numerical integrations with three different specifications of boundary conditions were carried out: a control experiment which utilized climatological boundary conditions, an SST experiment which utilized summer 1980 sea-surface temperatures in the North Pacific, but climatological values elsewhere, and a Soil Moisture experiment which utilized the values of Mintz-Serafini for the summer, 1980. The starting dates for the five forecasts were 11 June, 7 July, 21 July, 22 August, and 6 September of 1980. These dates were specifically chosen as days when a heat wave was already established in order to investigate the effect of soil moistures or North Pacific sea-surface temperatures on the model's ability to maintain the heat wave pattern. The experiments were evaluated in terms of the heat wave index for the South Plains, North Plains, Great Plains and the entire U.S. In addition a subjective comparison of map patterns has been performed.

  14. Hidden modes in open disordered media: analytical, numerical, and experimental results

    NASA Astrophysics Data System (ADS)

    Bliokh, Yury P.; Freilikher, Valentin; Shi, Z.; Genack, A. Z.; Nori, Franco

    2015-11-01

    We explore numerically, analytically, and experimentally the relationship between quasi-normal modes (QNMs) and transmission resonance (TR) peaks in the transmission spectrum of one-dimensional (1D) and quasi-1D open disordered systems. It is shown that for weak disorder there exist two types of the eigenstates: ordinary QNMs which are associated with a TR, and hidden QNMs which do not exhibit peaks in transmission or within the sample. The distinctive feature of the hidden modes is that unlike ordinary ones, their lifetimes remain constant in a wide range of the strength of disorder. In this range, the averaged ratio of the number of transmission peaks {N}{{res}} to the number of QNMs {N}{{mod}}, {N}{{res}}/{N}{{mod}}, is insensitive to the type and degree of disorder and is close to the value \\sqrt{2/5}, which we derive analytically in the weak-scattering approximation. The physical nature of the hidden modes is illustrated in simple examples with a few scatterers. The analogy between ordinary and hidden QNMs and the segregation of superradiant states and trapped modes is discussed. When the coupling to the environment is tuned by an external edge reflectors, the superradiance transition is reproduced. Hidden modes have been also found in microwave measurements in quasi-1D open disordered samples. The microwave measurements and modal analysis of transmission in the crossover to localization in quasi-1D systems give a ratio of {N}{{res}}/{N}{{mod}} close to \\sqrt{2/5}. In diffusive quasi-1D samples, however, {N}{{res}}/{N}{{mod}} falls as the effective number of transmission eigenchannels M increases. Once {N}{{mod}} is divided by M, however, the ratio {N}{{res}}/{N}{{mod}} is close to the ratio found in 1D.

  15. Solutions of the Two Dimensional Hubbard Model: Benchmarks and Results from a Wide Range of Numerical Algorithms

    NASA Astrophysics Data System (ADS)

    Leblanc, James

    In this talk we present numerical results for ground state and excited state properties (energies, double occupancies, and Matsubara-axis self energies) of the single-orbital Hubbard model on a two-dimensional square lattice. In order to provide an assessment of our ability to compute accurate results in the thermodynamic limit we employ numerous methods including auxiliary field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock. We illustrate cases where agreement between different methods is obtained in order to establish benchmark results that should be useful in the validation of future results.

  16. A review of numerical models for predicting the energy deposition and resultant thermal response of humans exposed to electromagnetic fields

    SciTech Connect

    Spiegal, R.J.

    1984-08-01

    For humans exposed to electromagnetic (EM) radiation, the resulting thermophysiologic response is not well understood. Because it is unlikely that this information will be determined from quantitative experimentation, it is necessary to develop theoretical models which predict the resultant thermal response after exposure to EM fields. These calculations are difficult and involved because the human thermoregulatory system is very complex. In this paper, the important numerical models are reviewed and possibilities for future development are discussed.

  17. Kinetic-Fluid Coupling in the Field of the Atomic Vapor Laser Isotopic Separation: Numerical Results in the Case of a Monospecies Perfect Gas

    NASA Astrophysics Data System (ADS)

    Dellacherie, Stéphane

    2003-05-01

    To describe the uranium gas expansion in the field of the Atomic Vapor Laser Isotopic Separation (AVLIS; SILVA in french) with a reasonable CPU time, we have to couple the resolution of the Boltzmann equation with the resolution of the Euler system. The resolution of the Euler system uses a kinetic scheme and the boundary condition at the kinetic - fluid interface — which defines the boundary between the Boltzmann area and the Euler area — is defined with the positive and negative half fluxes of the kinetic scheme. Moreover, in order to take into account the effect of the Knudsen layer through the resolution of the Euler system, we propose to use a Marshak condition to asymptoticaly match the Euler area with the uranium source. Numerical results show an excellent agreement between the results obtained with and without kinetic - fluid coupling.

  18. Image restoration by the method of convex projections: part 2 applications and numerical results.

    PubMed

    Sezan, M I; Stark, H

    1982-01-01

    The image restoration theory discussed in a previous paper by Youla and Webb [1] is applied to a simulated image and the results compared with the well-known method known as the Gerchberg-Papoulis algorithm. The results show that the method of image restoration by projection onto convex sets, by providing a convenient technique for utilizing a priori information, performs significantly better than the Gerchberg-Papoulis method.

  19. A numerically efficient finite element hydroelastic analysis. Volume 1: Theory and results

    NASA Technical Reports Server (NTRS)

    Coppolino, R. N.

    1976-01-01

    Symmetric finite element matrix formulations for compressible and incompressible hydroelasticity are developed on the basis of Toupin's complementary formulation of classical mechanics. Results of implementation of the new technique in the NASTRAN structural analysis program are presented which demonstrate accuracy and efficiency.

  20. Erratum: new numerical results and novel effective string predictions for Wilson loops

    NASA Astrophysics Data System (ADS)

    Billó, M.; Caselle, M.; Pellegrini, R.

    2013-04-01

    We correct a few misprints present in the published version, regarding eq.s (4.30), (4.35), (A.4) and (A.6). Plots and results of the paper are not affected since they were derived from the correct formulae.

  1. Three-dimensional Simulations of Thermonuclear Detonation with α-Network: Numerical Method and Preliminary Results

    NASA Astrophysics Data System (ADS)

    Khokhlov, A.; Domínguez, I.; Bacon, C.; Clifford, B.; Baron, E.; Hoeflich, P.; Krisciunas, K.; Suntzeff, N.; Wang, L.

    2012-07-01

    We describe a new astrophysical version of a cell-based adaptive mesh refinement code ALLA for reactive flow fluid dynamic simulations, including a new implementation of α-network nuclear kinetics, and present preliminary results of first three-dimensional simulations of incomplete carbon-oxygen detonation in Type Ia Supernovae.

  2. Multi-Country Experience in Delivering a Joint Course on Software Engineering--Numerical Results

    ERIC Educational Resources Information Center

    Budimac, Zoran; Putnik, Zoran; Ivanovic, Mirjana; Bothe, Klaus; Zdravkova, Katerina; Jakimovski, Boro

    2014-01-01

    A joint course, created as a result of a project under the auspices of the "Stability Pact of South-Eastern Europe" and DAAD, has been conducted in several Balkan countries: in Novi Sad, Serbia, for the last six years in several different forms, in Skopje, FYR of Macedonia, for two years, for several types of students, and in Tirana,…

  3. Increased heat transfer to elliptical leading edges due to spanwise variations in the freestream momentum: Numerical and experimental results

    NASA Technical Reports Server (NTRS)

    Rigby, D. L.; Vanfossen, G. J.

    1992-01-01

    A study of the effect of spanwise variation in momentum on leading edge heat transfer is discussed. Numerical and experimental results are presented for both a circular leading edge and a 3:1 elliptical leading edge. Reynolds numbers in the range of 10,000 to 240,000 based on leading edge diameter are investigated. The surface of the body is held at a constant uniform temperature. Numerical and experimental results with and without spanwise variations are presented. Direct comparison of the two-dimensional results, that is, with no spanwise variations, to the analytical results of Frossling is very good. The numerical calculation, which uses the PARC3D code, solves the three-dimensional Navier-Stokes equations, assuming steady laminar flow on the leading edge region. Experimentally, increases in the spanwise-averaged heat transfer coefficient as high as 50 percent above the two-dimensional value were observed. Numerically, the heat transfer coefficient was seen to increase by as much as 25 percent. In general, under the same flow conditions, the circular leading edge produced a higher heat transfer rate than the elliptical leading edge. As a percentage of the respective two-dimensional values, the circular and elliptical leading edges showed similar sensitivity to span wise variations in momentum. By equating the root mean square of the amplitude of the spanwise variation in momentum to the turbulence intensity, a qualitative comparison between the present work and turbulent results was possible. It is shown that increases in leading edge heat transfer due to spanwise variations in freestream momentum are comparable to those due to freestream turbulence.

  4. Yield criteria for porous media in plane strain: second-order estimates versus numerical results

    NASA Astrophysics Data System (ADS)

    Pastor, Joseph; Ponte Castañeda, Pedro

    2002-11-01

    This Note presents a comparison of some recently developed "second-order" homogenization estimates for two-dimensional, ideally plastic porous media subjected to plane strain conditions with corresponding yield analysis results using a new linearization technique and systematically optimized finite elements meshes. Good qualitative agreement is found between the second-order theory and the yield analysis results for the shape of the yield surfaces, which exhibit a corner on the hydrostatic axis, as well as for the dependence of the effective flow stress in shear on the porosity, which is found to be non-analytic in the dilute limit. Both of these features are inconsistent with the predictions of the standard Gurson model. To cite this article: J. Pastor, P. Ponte Castañeda, C. R. Mecanique 330 (2002) 741-747.

  5. Preliminary numerical modeling results - cone penetrometer (CPT) tip used as an electrode

    SciTech Connect

    Ramirez, A L

    2006-12-19

    Figure 1 shows the resistivity models considered in this study; log10 of the resistivity is shown. The graph on the upper left hand side shows a hypothetical resisitivity well log measured along a well in the upper layered model; 10% Gaussian noise has been added to the well log data. The lower model is identical to the upper one except for one square area located within the second deepest layer. Figure 2 shows the electrode configurations considered. The ''reference'' case (upper frame) considers point electrodes located along the surface and along a vertical borehole. The ''CPT electrode'' case (middle frame) assumes that the CPT tip serves as an electrode that is electrically connected to the push rod; the surface electrodes are used in conjuction with the moving CPT electrode. The ''isolated CPT electrode'' case assumes that the electrode at the CPT tip is electrically isolated from the pushrod. Note that the separate CPT push rods in the middle and lower frames are shown separated to clarify the figure; in reality, there is only one pushrod that is changing length as the probe advances. Figure 3 shows three pole-pole measurement schemes were considered; in all cases, the ''get lost'' electrodes were the leftmost and rightmost surface electrodes. The top frame shows the reference scheme where all surface and borehole electrodes can be used. The middle frame shows two possible configurations available when a CPT mounted electrode is used. Note that only one of the four poles can be located along the borehole at any given time; electrode combinations such as the one depicted in blue (upper frame) are not possible in this case. The bottom frame shows a sample configuration where only the surface electrodes are used. Figure 4 shows the results obtained for the various measurement schemes. The white lines show the outline of the true model (shown in Figure 1, upper frame). The starting initial model for these inversions is based on the electrical resistivity log

  6. A DGTD method for the numerical modeling of the interaction of light with nanometer scale metallic structures taking into account non-local dispersion effects

    NASA Astrophysics Data System (ADS)

    Schmitt, Nikolai; Scheid, Claire; Lanteri, Stéphane; Moreau, Antoine; Viquerat, Jonathan

    2016-07-01

    's equations coupled to a linearized non-local dispersion model relevant to plasmonics. While the method is presented in the general 3D case, numerical results are given for 2D simulation settings.

  7. Multilayered optical memory with bits stored as refractive index change. II. Numerical results of a waveguide multilayered optical memory.

    PubMed

    Guo, Hanming; Zhuang, Songlin; Guo, Shuwen; Chen, Jiabi; Liang, Zhongcheng

    2008-07-01

    In terms of the electromagnetic theory described in Part I of our current investigations [J. Opt. Soc. Am. A24, 1776 (2007)], the numerical method for and results of numerical computations corresponding to the electromagnetic theory of a waveguide multilayered optical memory are presented. Here the characteristics of the cross talk and the modulation contrast, the power of readout signals, the variation of the power of the readout signals with the scanning position along the track, and the distribution of the light intensity at the detector are investigated in detail. Results show that the polarization of the reading light, the feature sizes of bits, and the distances between the two adjacent tracks and the two adjacent bits on the same track have significant effects on the distribution of the light intensity at the detector, the power of the readout signals, the cross talk, and the modulation contrast. In addition, the optimal polarization of the reading light is also suggested.

  8. [Implementation results of emission standards of air pollutants for thermal power plants: a numerical simulation].

    PubMed

    Wang, Zhan-Shan; Pan, Li-Bo

    2014-03-01

    The emission inventory of air pollutants from the thermal power plants in the year of 2010 was set up. Based on the inventory, the air quality of the prediction scenarios by implementation of both 2003-version emission standard and the new emission standard were simulated using Models-3/CMAQ. The concentrations of NO2, SO2, and PM2.5, and the deposition of nitrogen and sulfur in the year of 2015 and 2020 were predicted to investigate the regional air quality improvement by the new emission standard. The results showed that the new emission standard could effectively improve the air quality in China. Compared with the implementation results of the 2003-version emission standard, by 2015 and 2020, the area with NO2 concentration higher than the emission standard would be reduced by 53.9% and 55.2%, the area with SO2 concentration higher than the emission standard would be reduced by 40.0%, the area with nitrogen deposition higher than 1.0 t x km(-2) would be reduced by 75.4% and 77.9%, and the area with sulfur deposition higher than 1.6 t x km(-2) would be reduced by 37.1% and 34.3%, respectively.

  9. Numerical predictions and experimental results of a dry bay fire environment.

    SciTech Connect

    Suo-Anttila, Jill Marie; Gill, Walter; Black, Amalia Rebecca

    2003-11-01

    The primary objective of the Safety and Survivability of Aircraft Initiative is to improve the safety and survivability of systems by using validated computational models to predict the hazard posed by a fire. To meet this need, computational model predictions and experimental data have been obtained to provide insight into the thermal environment inside an aircraft dry bay. The calculations were performed using the Vulcan fire code, and the experiments were completed using a specially designed full-scale fixture. The focus of this report is to present comparisons of the Vulcan results with experimental data for a selected test scenario and to assess the capability of the Vulcan fire field model to accurately predict dry bay fire scenarios. Also included is an assessment of the sensitivity of the fire model predictions to boundary condition distribution and grid resolution. To facilitate the comparison with experimental results, a brief description of the dry bay fire test fixture and a detailed specification of the geometry and boundary conditions are included. Overall, the Vulcan fire field model has shown the capability to predict the thermal hazard posed by a sustained pool fire within a dry bay compartment of an aircraft; although, more extensive experimental data and rigorous comparison are required for model validation.

  10. Analytical and Numerical Results for an Adhesively Bonded Joint Subjected to Pure Bending

    NASA Technical Reports Server (NTRS)

    Smeltzer, Stanley S., III; Lundgren, Eric

    2006-01-01

    A one-dimensional, semi-analytical methodology that was previously developed for evaluating adhesively bonded joints composed of anisotropic adherends and adhesives that exhibit inelastic material behavior is further verified in the present paper. A summary of the first-order differential equations and applied joint loading used to determine the adhesive response from the methodology are also presented. The method was previously verified against a variety of single-lap joint configurations from the literature that subjected the joints to cases of axial tension and pure bending. Using the same joint configuration and applied bending load presented in a study by Yang, the finite element analysis software ABAQUS was used to further verify the semi-analytical method. Linear static ABAQUS results are presented for two models, one with a coarse and one with a fine element meshing, that were used to verify convergence of the finite element analyses. Close agreement between the finite element results and the semi-analytical methodology were determined for both the shear and normal stress responses of the adhesive bondline. Thus, the semi-analytical methodology was successfully verified using the ABAQUS finite element software and a single-lap joint configuration subjected to pure bending.

  11. Are More Stringent NCLB State Accountability Systems Associated with Better Student Outcomes? An Analysis of NAEP Results across States

    ERIC Educational Resources Information Center

    Wei, Xin

    2012-01-01

    This study developed a comprehensive measure of the stringency level of NCLB states' accountability systems, including the strength of their annual measurable objectives, confidence intervals, performance indexing, retesting, minimum subgroup size, and the difficulty levels of proficiency standards. This study related accountability stringency in…

  12. Introduction of corrections taking into account interdependence of multigroup constants to the results of multigroup perturbation theory calculations

    SciTech Connect

    Raskach, K. F.

    2012-12-15

    In multigroup calculations of reactivity and sensitivity coefficients, methodical errors can appear if the interdependence of multigroup constants is not taken into account. For this effect to be taken into account, so-called implicit components of the aforementioned values are introduced. A simple technique for computing these values is proposed. It is based on the use of subgroup parameters.

  13. Urban Surface Network In Marseille: Network Optimization Using Numerical Simulations and Results

    NASA Astrophysics Data System (ADS)

    Pigeon, G.; Lemonsu, A.; Durand, P.; Masson, V.

    During the ESCOMPTE program (Field experiment to constrain models of atmo- spheric pollution and emissions transport) in Marseille between june and july 2001 an important device has been set up to describe the urban boundary layer over the built-up aera of Marseille. There was notably a network of 20 temperature and humid- ity sensors which has mesured the spatial and temporal variability of these parameters. Before the experiment the arrangement of the network had been optimized to get the maximum of information about these two varaibilities. We have worked on results of high resolution simulations containing the TEB scheme which represents the energy budgets associated with the gobal street geometry of the mesh. First, a qualitative analysis had enabled the identification of the characteristical phenomenons over the town of Marseille. There are narrows links beetween urban effects and local effects : marine advection and orography. Then, a quantitative analysis of the field has been developped. EOF (empirical orthogonal functions) have been used to characterised the spatial and temporal structures of the field evolution. Instrumented axis have been determined with all these results. Finally, we have choosen very carefully the locations of the instruments at the scale of the street to avoid that micro-climatic effects interfere with the meso-scale effect of the town. The recording of the mesurements, every 10 minutes, had started on the 12th of june and had finished on the 16th of july. We did not get any problem with the instrument and so all the period has been recorded every 10 minutes. The analysis of the datas will be led on different way. First, will be done a temporal study. We want to determine if the times when occur phenomenons are linked to the location in the town. We will interest particulary to the warming during the morning and the cooling during the evening. Then, we will look for correlation between the temperature and mixing ratio with the wind

  14. Numerical results for near surface time domain electromagnetic exploration: a full waveform approach

    NASA Astrophysics Data System (ADS)

    Sun, H.; Li, K.; Li, X., Sr.; Liu, Y., Sr.; Wen, J., Sr.

    2015-12-01

    Time domain or Transient electromagnetic (TEM) survey including types with airborne, semi-airborne and ground play important roles in applicants such as geological surveys, ground water/aquifer assess [Meju et al., 2000; Cox et al., 2010], metal ore exploration [Yang and Oldenburg, 2012], prediction of water bearing structures in tunnels [Xue et al., 2007; Sun et al., 2012], UXO exploration [Pasion et al., 2007; Gasperikova et al., 2009] etc. The common practice is introducing a current into a transmitting (Tx) loop and acquire the induced electromagnetic field after the current is cut off [Zhdanov and Keller, 1994]. The current waveforms are different depending on instruments. Rectangle is the most widely used excitation current source especially in ground TEM. Triangle and half sine are commonly used in airborne and semi-airborne TEM investigation. In most instruments, only the off time responses are acquired and used in later analysis and data inversion. Very few airborne instruments acquire the on time and off time responses together. Although these systems acquire the on time data, they usually do not use them in the interpretation.This abstract shows a novel full waveform time domain electromagnetic method and our recent modeling results. The benefits comes from our new algorithm in modeling full waveform time domain electromagnetic problems. We introduced the current density into the Maxwell's equation as the transmitting source. This approach allows arbitrary waveforms, such as triangle, half-sine, trapezoidal waves or scatter record from equipment, being used in modeling. Here, we simulate the establishing and induced diffusion process of the electromagnetic field in the earth. The traditional time domain electromagnetic with pure secondary fields can also be extracted from our modeling results. The real time responses excited by a loop source can be calculated using the algorithm. We analyze the full time gates responses of homogeneous half space and two

  15. Computing the dissipative part of the gravitational self force: II. Numerical implementation and preliminary results

    NASA Astrophysics Data System (ADS)

    Hughes, Scott; Flanagan, Eanna; Hinderer, Tanja; Ruangsri, Uchupol

    2015-04-01

    We describe how we have modified a frequency-domain Teukolsky-equation solver, previously used for computing orbit-averaged dissipation, in order to compute the dissipative piece of the gravitational self force on orbits of Kerr black holes. This calculation involves summing over a large number of harmonics. Each harmonic is independent of all others, so it is well suited to parallel computation. We show preliminary results for equatorial eccentric orbits and circular inclined orbits, demonstrating convergence of the harmonic expansion, as well as interesting phenomenology of the self force's behavior in the strong field. We conclude by discussing plans for using this force to study generic orbits, with a focus on the behavior of orbital resonances.

  16. Restricted diffusion in a model acinar labyrinth by NMR: Theoretical and numerical results

    NASA Astrophysics Data System (ADS)

    Grebenkov, D. S.; Guillot, G.; Sapoval, B.

    2007-01-01

    A branched geometrical structure of the mammal lungs is known to be crucial for rapid access of oxygen to blood. But an important pulmonary disease like emphysema results in partial destruction of the alveolar tissue and enlargement of the distal airspaces, which may reduce the total oxygen transfer. This effect has been intensively studied during the last decade by MRI of hyperpolarized gases like helium-3. The relation between geometry and signal attenuation remained obscure due to a lack of realistic geometrical model of the acinar morphology. In this paper, we use Monte Carlo simulations of restricted diffusion in a realistic model acinus to compute the signal attenuation in a diffusion-weighted NMR experiment. We demonstrate that this technique should be sensitive to destruction of the branched structure: partial removal of the interalveolar tissue creates loops in the tree-like acinar architecture that enhance diffusive motion and the consequent signal attenuation. The role of the local geometry and related practical applications are discussed.

  17. Radiative properties of a plasma moving across a magnetic field. I - Theoretical analysis. II - Numerical results

    NASA Technical Reports Server (NTRS)

    Roussel-Dupre, Robert; Miller, Ronald H.

    1993-01-01

    The early-time evolution of plasmas moving across a background magnetic field is addressed with a 2D model in which a plasma cloud is assumed to have formed instantaneously with a velocity across a uniform background magnetic field and with a Gaussian density profile in the two dimensions perpendicular to the direction of motion. This model treats both the dynamics associated with the formation of a polarization field and the generation and propagation of electromagnetic waves. In general, the results indicate that, to zeroth order, the plasma cloud behaves like a large dipole antenna oriented in the direction of the polarization field which oscillates at frequencies defined by the normal mode of the system. Radiation damping is shown to play an important role in defining the plasma cloud evolution, causing a rapid decay of the polarizaiton field and a loss of plasma kinetic energy and momentum on time scales comprable to several ion gyroperiods. Scaling laws are derived for the plasma momentum and energy loss rates, and predictions for the braking time, the amplitude and spectrum of the radiation field, and the total radiated power are presented for conditions relevant to the recent Combined Release and Radiation Effects Satellite experiments.

  18. Insight into collision zone dynamics from topography: numerical modelling results and observations

    NASA Astrophysics Data System (ADS)

    Bottrill, A. D.; van Hunen, J.; Allen, M. B.

    2012-11-01

    Dynamic models of subduction and continental collision are used to predict dynamic topography changes on the overriding plate. The modelling results show a distinct evolution of topography on the overriding plate, during subduction, continental collision and slab break-off. A prominent topographic feature is a temporary (few Myrs) basin on the overriding plate after initial collision. This "collisional mantle dynamic basin" (CMDB) is caused by slab steepening drawing, material away from the base of the overriding plate. Also, during this initial collision phase, surface uplift is predicted on the overriding plate between the suture zone and the CMDB, due to the subduction of buoyant continental material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the overriding plate cause the uplift to spread further into the overriding plate. This topographic evolution fits the stratigraphy found on the overriding plate of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the overriding plate contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene-Early Miocene the surface of the overriding plate sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. Our modelled topography changes fit well with this observed uplift and subsidence.

  19. Insight into collision zone dynamics from topography: numerical modelling results and observations

    NASA Astrophysics Data System (ADS)

    Bottrill, A. D.; van Hunen, J.; Allen, M. B.

    2012-07-01

    Dynamic models of subduction and continental collision are used to predict dynamic topography changes on the overriding plate. The modelling results show a distinct evolution of topography on the overriding plate, during subduction, continental collision and slab break-off. A prominent topographic feature is a temporary (few Myrs) deepening in the area of the back arc-basin after initial collision. This collisional mantle dynamic basin (CMDB) is caused by slab steepening drawing material away from the base of the overriding plate. Also during this initial collision phase, surface uplift is predicted on the overriding plate between the suture zone and the CMDB, due to the subduction of buoyant continental material and its isostatic compensation. After slab detachment, redistribution of stresses and underplating of the overriding plate causes the uplift to spread further into the overriding plate. This topographic evolution fits the stratigraphy found on the overriding plate of the Arabia-Eurasia collision zone in Iran and south east Turkey. The sedimentary record from the overriding plate contains Upper Oligocene-Lower Miocene marine carbonates deposited between terrestrial clastic sedimentary rocks, in units such as the Qom Formation and its lateral equivalents. This stratigraphy shows that during the Late Oligocene-Early Miocene the surface of the overriding plate sank below sea level before rising back above sea level, without major compressional deformation recorded in the same area. This uplift and subsidence pattern correlates well with our modelled topography changes.

  20. The Formation of Asteroid Satellites in Catastrophic Impacts: Results from Numerical Simulations

    NASA Technical Reports Server (NTRS)

    Durda, D. D.; Bottke, W. F., Jr.; Enke, B. L.; Asphaug, E.; Richardson, D. C.; Leinhardt, Z. M.

    2003-01-01

    We have performed new simulations of the formation of asteroid satellites by collisions, using a combination of hydrodynamical and gravitational dynamical codes. This initial work shows that both small satellites and ejected, co-orbiting pairs are produced most favorably by moderate-energy collisions at more direct, rather than oblique, impact angles. Simulations so far seem to be able to produce systems qualitatively similar to known binaries. Asteroid satellites provide vital clues that can help us understand the physics of hypervelocity impacts, the dominant geologic process affecting large main belt asteroids. Moreover, models of satellite formation may provide constraints on the internal structures of asteroids beyond those possible from observations of satellite orbital properties alone. It is probable that most observed main-belt asteroid satellites are by-products of cratering and/or catastrophic disruption events. Several possible formation mechanisms related to collisions have been identified: (i) mutual capture following catastrophic disruption, (ii) rotational fission due to glancing impact and spin-up, and (iii) re-accretion in orbit of ejecta from large, non-catastrophic impacts. Here we present results from a systematic investigation directed toward mapping out the parameter space of the first and third of these three collisional mechanisms.

  1. Effective Compressibility of A Bubbly Slurry: II. Fitting Numerical Results to Field Data and Implications

    SciTech Connect

    Kam, Seung I.; Gauglitz, Phillip A. ); Rossen, William R.

    2000-12-01

    The goal of this study is to fit model parameters to changes in waste level in response to barometric pressure changes in underground storage tanks at the Hanford Site. This waste compressibility is a measure of the quantity of gas, typically hydrogen and other flammable gases that can pose a safety hazard, retained in the waste. A one-dimensional biconical-pore-network model for compressibility of a bubbly slurry is presented in a companion paper. Fitting these results to actual waste level changes in the tanks implies that bubbles are long in the slurry layer and the ratio of pore-body radius to pore-throat radius is close to one; unfortunately, capillary effects can not be quantified unambiguously from the data without additional information on pore geometry. Therefore determining the quantity of gas in the tanks requires more than just slurry volume data. Similar ambiguity also exists with two other simple models: a capillary-tube model with contact angle hysteresis and spherical-p ore model.

  2. Chaotic escape from an open vase-shaped cavity. I. Numerical and experimental results

    NASA Astrophysics Data System (ADS)

    Novick, Jaison; Keeler, Matthew L.; Giefer, Joshua; Delos, John B.

    2012-01-01

    We present part I in a two-part study of an open chaotic cavity shaped as a vase. The vase possesses an unstable periodic orbit in its neck. Trajectories passing through this orbit escape without return. For our analysis, we consider a family of trajectories launched from a point on the vase boundary. We imagine a vertical array of detectors past the unstable periodic orbit and, for each escaping trajectory, record the propagation time and the vertical detector position. We find that the escape time exhibits a complicated recursive structure. This recursive structure is explored in part I of our study. We present an approximation to the Helmholtz equation for waves escaping the vase. By choosing a set of detector points, we interpolate trajectories connecting the source to the different detector points. We use these interpolated classical trajectories to construct the solution to the wave equation at a detector point. Finally, we construct a plot of the detector position versus the escape time and compare this graph to the results of an experiment using classical ultrasound waves. We find that generally the classical trajectories organize the escaping ultrasound waves.

  3. Numerical modeling of anti-icing systems and comparison to test results on a NACA 0012 airfoil

    NASA Technical Reports Server (NTRS)

    Al-Khalil, Kamel M.; Potapczuk, Mark G.

    1993-01-01

    A series of experimental tests were conducted in the NASA Lewis IRT on an electro-thermally heated NACA 0012 airfoil. Quantitative comparisons between the experimental results and those predicted by a computer simulation code were made to assess the validity of a recently developed anti-icing model. An infrared camera was utilized to scan the instantaneous temperature contours of the skin surface. Despite some experimental difficulties, good agreement between the numerical predictions and the experimental results were generally obtained for the surface temperature and the possibility for the runback to freeze. Some recommendations were given for an efficient operation of a thermal anti-icing system.

  4. Numerical Modeling of Anti-icing Systems and Comparison to Test Results on a NACA 0012 Airfoil

    NASA Technical Reports Server (NTRS)

    Al-Khalil, Kamel M.; Potapczuk, Mark G.

    1993-01-01

    A series of experimental tests were conducted in the NASA Lewis IRT on an electro-thermally heated NACA 0012 airfoil. Quantitative comparisons between the experimental results and those predicted by a computer simulation code were made to assess the validity of a recently developed anti-icing model. An infrared camera was utilized to scan the instantaneous temperature contours of the skin surface. Despite some experimental difficulties, good agreement between the numerical predictions and the experiment results were generally obtained for the surface temperature and the possibility for each runback to freeze. Some recommendations were given for an efficient operation of a thermal anti-icing system.

  5. Universal spatial correlations in the anisotropic Kondo screening cloud: Analytical insights and numerically exact results from a coherent state expansion

    NASA Astrophysics Data System (ADS)

    Florens, Serge; Snyman, Izak

    2015-11-01

    We analyze the spatial correlation structure of the spin density of an electron gas in the vicinity of an antiferromagnetically coupled Kondo impurity. Our analysis extends to the regime of spin-anisotropic couplings, where there are no quantitative results for spatial correlations in the literature. We use an original and numerically exact method, based on a systematic coherent-state expansion of the ground state of the underlying spin-boson Hamiltonian. It has not yet been applied to the computation of observables that are specific to the fermionic Kondo model. We also present an important technical improvement to the method that obviates the need to discretize modes of the Fermi sea, and allows one to tackle the problem in the thermodynamic limit. As a result, one can obtain excellent spatial resolution over arbitrary length scales, for a relatively low computational cost, a feature that gives the method an advantage over popular techniques such as the numerical and density-matrix renormalization groups. We find that the anisotropic Kondo model shows rich universal scaling behavior in the spatial structure of the entanglement cloud. First, SU(2) spin-symmetry is dynamically restored in a finite domain in the parameter space in the vicinity of the isotropic line, as expected from poor man's scaling. More surprisingly, we are able to obtain in closed analytical form a set of different, yet universal, scaling curves for strong exchange asymmetry, which are parametrized by the longitudinal exchange coupling. Deep inside the cloud, i.e., for distances smaller than the Kondo length, the correlation between the electron spin density and the impurity spin oscillates between ferromagnetic and antiferromagnetic values at the scale of the Fermi wavelength, an effect that is drastically enhanced at strongly anisotropic couplings. Our results also provide further numerical checks and alternative analytical approximations for the Kondo overlaps that were recently computed by

  6. Universal spectral statistics in Wigner-Dyson, chiral, and Andreev star graphs. I. Construction and numerical results

    NASA Astrophysics Data System (ADS)

    Gnutzmann, Sven; Seif, Burkhard

    2004-05-01

    In a series of two papers we investigate the universal spectral statistics of chaotic quantum systems in the ten known symmetry classes of quantum mechanics. In this first paper we focus on the construction of appropriate ensembles of star graphs in the ten symmetry classes. A generalization of the Bohigas-Giannoni-Schmit conjecture is given that covers all these symmetry classes. The conjecture is supported by numerical results that demonstrate the fidelity of the spectral statistics of star graphs to the corresponding Gaussian random-matrix theories.

  7. Solutions of the Two-Dimensional Hubbard Model: Benchmarks and Results from a Wide Range of Numerical Algorithms

    NASA Astrophysics Data System (ADS)

    LeBlanc, J. P. F.; Antipov, Andrey E.; Becca, Federico; Bulik, Ireneusz W.; Chan, Garnet Kin-Lic; Chung, Chia-Min; Deng, Youjin; Ferrero, Michel; Henderson, Thomas M.; Jiménez-Hoyos, Carlos A.; Kozik, E.; Liu, Xuan-Wen; Millis, Andrew J.; Prokof'ev, N. V.; Qin, Mingpu; Scuseria, Gustavo E.; Shi, Hao; Svistunov, B. V.; Tocchio, Luca F.; Tupitsyn, I. S.; White, Steven R.; Zhang, Shiwei; Zheng, Bo-Xiao; Zhu, Zhenyue; Gull, Emanuel; Simons Collaboration on the Many-Electron Problem

    2015-10-01

    Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies) of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.

  8. Community Accountability for Quality Schools: Results of the 2008 National Poll and the Civic Index for Quality Public Education

    ERIC Educational Resources Information Center

    Public Education Network, 2008

    2008-01-01

    For many years, policymakers and the public have been holding students and schools accountable for improvement, but there was no way to determine whether the public and its elected officials and community organizations were doing their part to strengthen public schools. To address this shortcoming, Public Education network (PEN), with funding from…

  9. 26 CFR 1.381(c)(21)-1 - Pre-1954 adjustments resulting from change in method of accounting.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... the rate of $2,000 each year. On November 1, 1963, all the assets of X Corporation are acquired by Y Corporation in a transaction to which section 381(a) applies. Y Corporation reports its income on a fiscal year ending June 30. X and Y Corporations must take into account the $20,000 adjustment at the rate...

  10. 26 CFR 1.381(c)(21)-1 - Pre-1954 adjustments resulting from change in method of accounting.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... the rate of $2,000 each year. On November 1, 1963, all the assets of X Corporation are acquired by Y Corporation in a transaction to which section 381(a) applies. Y Corporation reports its income on a fiscal year ending June 30. X and Y Corporations must take into account the $20,000 adjustment at the rate...

  11. 26 CFR 1.381(c)(21)-1 - Pre-1954 adjustments resulting from change in method of accounting.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... the rate of $2,000 each year. On November 1, 1963, all the assets of X Corporation are acquired by Y Corporation in a transaction to which section 381(a) applies. Y Corporation reports its income on a fiscal year ending June 30. X and Y Corporations must take into account the $20,000 adjustment at the rate...

  12. P-E Fit as Moderator of the Accountability--Employee Reactions Relationships: Convergent Results across Two Samples

    ERIC Educational Resources Information Center

    Lanivich, Stephen E.; Brees, Jeremy R.; Hochwarter, Wayne A.; Ferris, Gerald R.

    2010-01-01

    The current two-sample investigation, which incorporated Conservation of Resources (COR) and Person-Environment (P-E) fit theories, investigated the interaction effects of felt accountability x P-E fit on the work outcomes of job satisfaction, organizational commitment, depressed mood, and work intensity. Consistent with the conceptual…

  13. Using numeric simulations to inform experimental data analysis: A new method to account for characteristic bending under dynamic loading and release

    NASA Astrophysics Data System (ADS)

    Alexander, Scott; Brown, Justin

    2013-03-01

    Dynamic high pressure experiments are often subject to unwanted wave interactions such as reflections from window interfaces or free surfaces where there is an impedance mismatch. In ramp loading experiments or under shock loading of materials resulting in a complex wave structure, these wave interactions can result in changes to the observed wave speeds. This effect, known as characteristic bending, can lead to significant errors in the measured material properties if not properly accounted for. Several approaches exist to correct for characteristic bending, however, they are limited to a one-to-one material response. New methodology has been developed based on control system theory to correct for characteristic bending without this limitation. By comparing simulated in-situ and window (or free surface) data, a transfer function is defined which captures the effects due to wave interactions. Application of this function to the experimental data results in in-situ profiles free from perturbations due to wave interactions. Experimental data, both with and without strong characteristic bending present, will be presented to illustrate the utility of this new approach. Sandia National Labs is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Dept. of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  14. Paraxial light distribution in the focal region of a lens: a comparison of several analytical solutions and a numerical result

    NASA Astrophysics Data System (ADS)

    Wu, Yang; Kelly, Damien P.

    2014-12-01

    The distribution of the complex field in the focal region of a lens is a classical optical diffraction problem. Today, it remains of significant theoretical importance for understanding the properties of imaging systems. In the paraxial regime, it is possible to find analytical solutions in the neighborhood of the focus, when a plane wave is incident on a focusing lens whose finite extent is limited by a circular aperture. For example, in Born and Wolf's treatment of this problem, two different, but mathematically equivalent analytical solutions, are presented that describe the 3D field distribution using infinite sums of ? and ? type Lommel functions. An alternative solution expresses the distribution in terms of Zernike polynomials, and was presented by Nijboer in 1947. More recently, Cao derived an alternative analytical solution by expanding the Fresnel kernel using a Taylor series expansion. In practical calculations, however, only a finite number of terms from these infinite series expansions is actually used to calculate the distribution in the focal region. In this manuscript, we compare and contrast each of these different solutions to a numerically calculated result, paying particular attention to how quickly each solution converges for a range of different spatial locations behind the focusing lens. We also examine the time taken to calculate each of the analytical solutions. The numerical solution is calculated in a polar coordinate system and is semi-analytic. The integration over the angle is solved analytically, while the radial coordinate is sampled with a sampling interval of ? and then numerically integrated. This produces an infinite set of replicas in the diffraction plane, that are located in circular rings centered at the optical axis and each with radii given by ?, where ? is the replica order. These circular replicas are shown to be fundamentally different from the replicas that arise in a Cartesian coordinate system.

  15. Validation of numerical results of impact of viscoelastic slug and elastic rod through viscoelastic discontinuity analysis: Standard linear solid model

    NASA Astrophysics Data System (ADS)

    Musa, A. B.

    2015-05-01

    The study is about impact of a short elastic rod (or slug) on a stationary semi-infinite viscoelastic rod. The viscoelastic materials are modeled as standard linear solid which involve three material parameters and the motion is treated as one-dimensional. We first establish the governing equations pertaining to the impact of viscoelastic materials subject to certain boundary conditions for the case when an elastic slug moving at a speed V impacts a semi-infinite stationary viscoelastic rod. The objective is to validate the numerical results of stresses and velocities at the interface following wave transmissions and reflections in the slug after the impact using viscoelastic discontinuity. If the stress at the interface becomes tensile and the velocity changes its sign, then the slug and the rod part company. If the stress at the interface is compressive after the impact, the slug and the rod remain in contact. After modelling the impact and solve the governing system of partial differential equations in the Laplace transform domain, we invert the Laplace transformed solution numerically to obtain the stresses and velocities at the interface for several viscosity time constants and ratios of acoustic impedances. In inverting the Laplace transformed equations, we used the complex inversion formula because there is a branch cut and infinitely many poles within the Bromwich contour. In the viscoelastic discontinuity analysis, we look at the moving discontinuities in stress and velocity using the impulse-momentum relation and kinematical condition of compatibility. Finally, we discussed the relationship of the stresses and velocities using numeric and the validated stresses and velocities using viscoelastic discontinuity analysis.

  16. Paraxial light distribution in the focal region of a lens: a comparison of several analytical solutions and a numerical result

    PubMed Central

    Wu, Yang; Kelly, Damien P.

    2014-01-01

    The distribution of the complex field in the focal region of a lens is a classical optical diffraction problem. Today, it remains of significant theoretical importance for understanding the properties of imaging systems. In the paraxial regime, it is possible to find analytical solutions in the neighborhood of the focus, when a plane wave is incident on a focusing lens whose finite extent is limited by a circular aperture. For example, in Born and Wolf’s treatment of this problem, two different, but mathematically equivalent analytical solutions, are presented that describe the 3D field distribution using infinite sums of Un and Vn type Lommel functions. An alternative solution expresses the distribution in terms of Zernike polynomials, and was presented by Nijboer in 1947. More recently, Cao derived an alternative analytical solution by expanding the Fresnel kernel using a Taylor series expansion. In practical calculations, however, only a finite number of terms from these infinite series expansions is actually used to calculate the distribution in the focal region. In this manuscript, we compare and contrast each of these different solutions to a numerically calculated result, paying particular attention to how quickly each solution converges for a range of different spatial locations behind the focusing lens. We also examine the time taken to calculate each of the analytical solutions. The numerical solution is calculated in a polar coordinate system and is semi-analytic. The integration over the angle is solved analytically, while the radial coordinate is sampled with a sampling interval of Δρ and then numerically integrated. This produces an infinite set of replicas in the diffraction plane, that are located in circular rings centered at the optical axis and each with radii given by 2πm/Δρ, where m is the replica order. These circular replicas are shown to be fundamentally different from the replicas that arise in a Cartesian coordinate system. PMID

  17. PINTEX Data: Numeric results from the Polarized Internal Target Experiments (PINTEX) at the Indiana University Cyclotron Facility

    DOE Data Explorer

    Meyer, H. O.

    The PINTEX group studied proton-proton and proton-deuteron scattering and reactions between 100 and 500 MeV at the Indiana University Cyclotron Facility (IUCF). More than a dozen experiments made use of electron-cooled polarized proton or deuteron beams, orbiting in the 'Indiana Cooler' storage ring, and of a polarized atomic-beam target of hydrogen or deuterium in the path of the stored beam. The collaboration involved researchers from several midwestern universities, as well as a number of European institutions. The PINTEX program ended when the Indiana Cooler was shut down in August 2002. The website contains links to some of the numerical results, descriptions of experiments, and a complete list of publications resulting from PINTEX.

  18. Validation and Analysis of Numerical Results for a Two-Pass Trapezoidal Channel With Different Cooling Configurations of Trailing Edge.

    PubMed

    Siddique, Waseem; El-Gabry, Lamyaa; Shevchuk, Igor V; Fransson, Torsten H

    2013-01-01

    High inlet temperatures in a gas turbine lead to an increase in the thermal efficiency of the gas turbine. This results in the requirement of cooling of gas turbine blades/vanes. Internal cooling of the gas turbine blade/vanes with the help of two-pass channels is one of the effective methods to reduce the metal temperatures. In particular, the trailing edge of a turbine vane is a critical area, where effective cooling is required. The trailing edge can be modeled as a trapezoidal channel. This paper describes the numerical validation of the heat transfer and pressure drop in a trapezoidal channel with and without orthogonal ribs at the bottom surface. A new concept of ribbed trailing edge has been introduced in this paper which presents a numerical study of several trailing edge cooling configurations based on the placement of ribs at different walls. The baseline geometries are two-pass trapezoidal channels with and without orthogonal ribs at the bottom surface of the channel. Ribs induce secondary flow which results in enhancement of heat transfer; therefore, for enhancement of heat transfer at the trailing edge, ribs are placed at the trailing edge surface in three different configurations: first without ribs at the bottom surface, then ribs at the trailing edge surface in-line with the ribs at the bottom surface, and finally staggered ribs. Heat transfer and pressure drop is calculated at Reynolds number equal to 9400 for all configurations. Different turbulent models are used for the validation of the numerical results. For the smooth channel low-Re k-ɛ model, realizable k-ɛ model, the RNG k-ω model, low-Re k-ω model, and SST k-ω models are compared, whereas for ribbed channel, low-Re k-ɛ model and SST k-ω models are compared. The results show that the low-Re k-ɛ model, which predicts the heat transfer in outlet pass of the smooth channels with difference of +7%, underpredicts the heat transfer by -17% in case of ribbed channel compared to

  19. Validation and Analysis of Numerical Results for a Two-Pass Trapezoidal Channel With Different Cooling Configurations of Trailing Edge.

    PubMed

    Siddique, Waseem; El-Gabry, Lamyaa; Shevchuk, Igor V; Fransson, Torsten H

    2013-01-01

    High inlet temperatures in a gas turbine lead to an increase in the thermal efficiency of the gas turbine. This results in the requirement of cooling of gas turbine blades/vanes. Internal cooling of the gas turbine blade/vanes with the help of two-pass channels is one of the effective methods to reduce the metal temperatures. In particular, the trailing edge of a turbine vane is a critical area, where effective cooling is required. The trailing edge can be modeled as a trapezoidal channel. This paper describes the numerical validation of the heat transfer and pressure drop in a trapezoidal channel with and without orthogonal ribs at the bottom surface. A new concept of ribbed trailing edge has been introduced in this paper which presents a numerical study of several trailing edge cooling configurations based on the placement of ribs at different walls. The baseline geometries are two-pass trapezoidal channels with and without orthogonal ribs at the bottom surface of the channel. Ribs induce secondary flow which results in enhancement of heat transfer; therefore, for enhancement of heat transfer at the trailing edge, ribs are placed at the trailing edge surface in three different configurations: first without ribs at the bottom surface, then ribs at the trailing edge surface in-line with the ribs at the bottom surface, and finally staggered ribs. Heat transfer and pressure drop is calculated at Reynolds number equal to 9400 for all configurations. Different turbulent models are used for the validation of the numerical results. For the smooth channel low-Re k-ɛ model, realizable k-ɛ model, the RNG k-ω model, low-Re k-ω model, and SST k-ω models are compared, whereas for ribbed channel, low-Re k-ɛ model and SST k-ω models are compared. The results show that the low-Re k-ɛ model, which predicts the heat transfer in outlet pass of the smooth channels with difference of +7%, underpredicts the heat transfer by -17% in case of ribbed channel compared to

  20. RESULTS FROM A DEMONSTRATION OF RF-BASED UF6 CYLINDER ACCOUNTING AND TRACKING SYSTEM INSTALLED AT A USEC FACILITY

    SciTech Connect

    Pickett, Chris A; Kovacic, Donald N; Morgan, Jim; Younkin, James R; Carrick, Bernie; Ken, Whittle; Johns, R E

    2008-09-01

    Approved industry-standard cylinders are used globally for storing and transporting uranium hexafluoride (UF{sub 6}) at uranium enrichment plants and processing facilities. To verify that no diversion or undeclared production of nuclear material involving UF{sub 6} cylinders at the facility has occurred, the International Atomic Energy Agency (IAEA) conducts periodic, labor-intensive physical inspections to validate facility records, cylinder identities, and cylinder weights. A reliable cylinder monitoring system that would improve overall inspector effectiveness would be a significant improvement to the current international safeguards inspection regime. Such a system could include real-time unattended monitoring of cylinder movements, situation-specific rules-based event detection algorithms, and the capability to integrate with other types of safeguards technologies. This type of system could provide timely detection of abnormal operational activities that may be used to ensure more appropriate and efficient responses by the IAEA. A system of this type can reduce the reliance on paper records and have the additional benefit of facilitating domestic safeguards at the facilities at which it is installed. A radio-frequency (RF)-based system designed to track uranium hexafluoride (UF{sub 6}) cylinders during processing operations was designed, assembled, and tested at the United States Enrichment Corporation (USEC) facility in Portsmouth, Ohio, to determine the operational feasibility and durability of RF technology. The overall objective of the effort was to validate the robustness of RF technology for potential use as a future international safeguards tool for tracking UF6 cylinders at uranium-processing facilities. The results to date indicate that RF tags represent a feasible technique for tracking UF{sub 6} cylinders in operating facilities. Additional work will be needed to improve the operational robustness of the tags for repeated autoclave processing and to

  1. A budget and accounting of metals at z ∼ 0: Results from the COS-Halos survey

    SciTech Connect

    Peeples, Molly S.; Werk, Jessica K.; Prochaska, J. Xavier; Oppenheimer, Benjamin D.; Katz, Neal; Weinberg, David H.

    2014-05-01

    We present a budget and accounting of metals in and around star-forming galaxies at z ∼ 0. We combine empirically derived star formation histories with updated supernova and asymptotic giant branch yields and rates to estimate the total mass of metals produced by galaxies with present-day stellar mass of 10{sup 9.3}-10{sup 11.6} M{sub ☉}. On the accounting side of the ledger, we show that a surprisingly constant 20%-25% mass fraction of produced metals remain in galaxies' stars, interstellar gas and interstellar dust, with little dependence of this fraction on the galaxy stellar mass (omitting those metals immediately locked up in remnants). Thus, the bulk of metals are outside of galaxies, produced in the progenitors of today's L* galaxies. The COS-Halos survey is uniquely able to measure the mass of metals in the circumgalactic medium (CGM, to impact parameters of <150 kpc) of low-redshift ∼L* galaxies. Using these data, we map the distribution of CGM metals as traced by both the highly ionized O VI ion and a suite of low-ionization species; combined with constraints on circumgalactic dust and hotter X-ray emitting gas out to similar impact parameters, we show that ∼40% of metals produced by M {sub *} ∼ 10{sup 10} M{sub ☉} galaxies can be easily accounted for out to 150 kpc. With the current data, we cannot rule out a constant mass of metals within this fixed physical radius. This census provides a crucial boundary condition for the eventual fate of metals in galaxy evolution models.

  2. Introducing "É VIVO! Virtual Eruptions on a Supercomputer". A DVD aimed at sharing results from numerical simulations of explosive eruptions

    NASA Astrophysics Data System (ADS)

    de'Michieli Vitturi, M.; Todesco, M.; Neri, A.; Esposti Ongaro, T.; Tola, E.; Rocco, G.

    2011-12-01

    We present a new DVD of the INGV outreach series, aimed at illustrating our research work on pyroclastic flow modeling. Pyroclastic flows (or pyroclastic density currents) are hot, devastating clouds of gas and ashes, generated during explosive eruptions. Understanding their dynamics and impact is crucial for a proper hazard assessment. We employ a 3D numerical model which describes the main features of the multi-phase and multi-component process, from the generation of the flows to their propagation along complex terrains. Our numerical results can be translated into color animations, which describe the temporal evolution of flow variables such as temperature or ash concentration. The animations provide a detailed and effective description of the natural phenomenon which can be used to present this geological process to a general public and to improve the hazard perception in volcanic areas. In our DVD, the computer animations are introduced and commented by professionals and researchers who deals at various levels with the study of pyroclastic flows and their impact. Their comments are taken as short interviews, mounted in a short video (about 10 minutes), which describes the natural process, as well as the model and its applications to some explosive volcanoes like Vesuvio, Campi Flegrei, Mt. St. Helens and Soufriere Hills (Montserrat). The ensemble of different voices and faces provides a direct sense of the multi-disciplinary effort involved in the assessment of pyroclastic flow hazard. The video also introduces the people who address this complex problem, and the personal involvement beyond the scientific results. The full, uncommented animations of the pyroclastic flow propagation on the different volcanic settings are also provided in the DVD, that is meant to be a general, flexible outreach tool.

  3. Solutions of the two-dimensional Hubbard model: Benchmarks and results from a wide range of numerical algorithms

    SciTech Connect

    LeBlanc, J. P. F.; Antipov, Andrey E.; Becca, Federico; Bulik, Ireneusz W.; Chan, Garnet Kin-Lic; Chung, Chia -Min; Deng, Youjin; Ferrero, Michel; Henderson, Thomas M.; Jiménez-Hoyos, Carlos A.; Kozik, E.; Liu, Xuan -Wen; Millis, Andrew J.; Prokof’ev, N. V.; Qin, Mingpu; Scuseria, Gustavo E.; Shi, Hao; Svistunov, B. V.; Tocchio, Luca F.; Tupitsyn, I. S.; White, Steven R.; Zhang, Shiwei; Zheng, Bo -Xiao; Zhu, Zhenyue; Gull, Emanuel

    2015-12-14

    Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies) of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification of uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Furthermore, cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.

  4. Numerical Prediction of the Performance of Integrated Planar Solid-Oxide Fuel Cells, with Comparisons of Results from Several Codes

    SciTech Connect

    G. L. Hawkes; J. E. O'Brien; B. A. Haberman; A. J. Marquis; C. M. Baca; D. Tripepi; P. Costamagna

    2008-06-01

    A numerical study of the thermal and electrochemical performance of a single-tube Integrated Planar Solid Oxide Fuel Cell (IP-SOFC) has been performed. Results obtained from two finite-volume computational fluid dynamics (CFD) codes FLUENT and SOHAB and from a two-dimensional inhouse developed finite-volume GENOA model are presented and compared. Each tool uses physical and geometric models of differing complexity and comparisons are made to assess their relative merits. Several single-tube simulations were run using each code over a range of operating conditions. The results include polarization curves, distributions of local current density, composition and temperature. Comparisons of these results are discussed, along with their relationship to the respective imbedded phenomenological models for activation losses, fluid flow and mass transport in porous media. In general, agreement between the codes was within 15% for overall parameters such as operating voltage and maximum temperature. The CFD results clearly show the effects of internal structure on the distributions of gas flows and related quantities within the electrochemical cells.

  5. Solutions of the two-dimensional Hubbard model: Benchmarks and results from a wide range of numerical algorithms

    DOE PAGES

    LeBlanc, J. P. F.; Antipov, Andrey E.; Becca, Federico; Bulik, Ireneusz W.; Chan, Garnet Kin-Lic; Chung, Chia -Min; Deng, Youjin; Ferrero, Michel; Henderson, Thomas M.; Jiménez-Hoyos, Carlos A.; et al

    2015-12-14

    Numerical results for ground-state and excited-state properties (energies, double occupancies, and Matsubara-axis self-energies) of the single-orbital Hubbard model on a two-dimensional square lattice are presented, in order to provide an assessment of our ability to compute accurate results in the thermodynamic limit. Many methods are employed, including auxiliary-field quantum Monte Carlo, bare and bold-line diagrammatic Monte Carlo, method of dual fermions, density matrix embedding theory, density matrix renormalization group, dynamical cluster approximation, diffusion Monte Carlo within a fixed-node approximation, unrestricted coupled cluster theory, and multireference projected Hartree-Fock methods. Comparison of results obtained by different methods allows for the identification ofmore » uncertainties and systematic errors. The importance of extrapolation to converged thermodynamic-limit values is emphasized. Furthermore, cases where agreement between different methods is obtained establish benchmark results that may be useful in the validation of new approaches and the improvement of existing methods.« less

  6. Results of numerical modeling of the convective burning of particulate explosive systems in the presence of increasing pressure

    SciTech Connect

    Ermolaev, B.S.; Novozhilov, B.V.; Posvyanskii, V.S.; Sulimov, A.A.

    1986-03-01

    The authors analyze the results of a numerical simulation of the convective burning of explosive powders in the presence of increasing pressure. The formulation of the problem reproduces a typical experimental technique: a strong closed vessel with a channel uniformly filled with the explosive investigated is fitted with devices for initiating and recording the process of explosion. It is shown that the relation between the propagation velocities of the flame and the compression waves in the powder and the rate of pressure increase in the combustion zone is such that a narrow compaction zone is formed ahead of the ignition front. Another important result is obtained by analyzing the difference between the flame velocity and the gas flow velocity in the ignition front. A model of the process is given. The results of the investigation throw light on such aspects of the convective combustion mechanism and the transition from combustion to detonation as the role of compaction of the explosive in the process of flame propogation and the role of the rate of pressure increase and dissipative heating of the gas phase in the pores ahead of the ignition front.

  7. The nonmonotonic dose dependence of optically stimulated luminescence in Al2O3:C: Analytical and numerical simulation results

    NASA Astrophysics Data System (ADS)

    Chen, R.; Pagonis, V.; Lawless, J. L.

    2006-02-01

    Nonmonotonic dose dependence of optically stimulated luminescence (OSL) has been reported in a number of materials including Al2O3:C which is one of the main dosimetric materials. In a recent work, the nonmonotonic effect has been shown to result, under certain circumstances, from the competition either during excitation or during readout between trapping states or recombination centers. In the present work, we report on a study of the effect in a more concrete framework of two trapping states and two kinds of recombination centers involved in the luminescence processes in Al2O3:C. Using sets of trapping parameters, based on available experimental data, previously utilized to explain the nonmonotonic dose dependence of thermoluminescence including nonzero initial occupancies of recombination centers (F+ centers), the OSL along with the occupancies of the relevant traps and centers are simulated numerically. The connection between these different resulting quantities is discussed, giving a better insight as to the ranges of the increase and decrease of the integral OSL as a function of dose, as well as the constant equilibrium value occurring at high doses.

  8. Time-dependent thermocapillary convection in a Cartesian cavity - Numerical results for a moderate Prandtl number fluid

    NASA Technical Reports Server (NTRS)

    Peltier, L. J.; Biringen, S.

    1993-01-01

    The present numerical simulation explores a thermal-convective mechanism for oscillatory thermocapillary convection in a shallow Cartesian cavity for a Prandtl number 6.78 fluid. The computer program developed for this simulation integrates the two-dimensional, time-dependent Navier-Stokes equations and the energy equation by a time-accurate method on a stretched, staggered mesh. Flat free surfaces are assumed. The instability is shown to depend upon temporal coupling between large scale thermal structures within the flow field and the temperature sensitive free surface. A primary result of this study is the development of a stability diagram presenting the critical Marangoni number separating steady from the time-dependent flow states as a function of aspect ratio for the range of values between 2.3 and 3.8. Within this range, a minimum critical aspect ratio near 2.3 and a minimum critical Marangoni number near 20,000 are predicted below which steady convection is found.

  9. Experimental results and numerical modeling of a high-performance large-scale cryopump. I. Test particle Monte Carlo simulation

    SciTech Connect

    Luo Xueli; Day, Christian; Haas, Horst; Varoutis, Stylianos

    2011-07-15

    For the torus of the nuclear fusion project ITER (originally the International Thermonuclear Experimental Reactor, but also Latin: the way), eight high-performance large-scale customized cryopumps must be designed and manufactured to accommodate the very high pumping speeds and throughputs of the fusion exhaust gas needed to maintain the plasma under stable vacuum conditions and comply with other criteria which cannot be met by standard commercial vacuum pumps. Under an earlier research and development program, a model pump of reduced scale based on active cryosorption on charcoal-coated panels at 4.5 K was manufactured and tested systematically. The present article focuses on the simulation of the true three-dimensional complex geometry of the model pump by the newly developed ProVac3D Monte Carlo code. It is shown for gas throughputs of up to 1000 sccm ({approx}1.69 Pa m{sup 3}/s at T = 0 deg. C) in the free molecular regime that the numerical simulation results are in good agreement with the pumping speeds measured. Meanwhile, the capture coefficient associated with the virtual region around the cryogenic panels and shields which holds for higher throughputs is calculated using this generic approach. This means that the test particle Monte Carlo simulations in free molecular flow can be used not only for the optimization of the pumping system but also for the supply of the input parameters necessary for the future direct simulation Monte Carlo in the full flow regime.

  10. The Trichoderma harzianum demon: complex speciation history resulting in coexistence of hypothetical biological species, recent agamospecies and numerous relict lineages

    PubMed Central

    2010-01-01

    Background The mitosporic fungus Trichoderma harzianum (Hypocrea, Ascomycota, Hypocreales, Hypocreaceae) is an ubiquitous species in the environment with some strains commercially exploited for the biological control of plant pathogenic fungi. Although T. harzianum is asexual (or anamorphic), its sexual stage (or teleomorph) has been described as Hypocrea lixii. Since recombination would be an important issue for the efficacy of an agent of the biological control in the field, we investigated the phylogenetic structure of the species. Results Using DNA sequence data from three unlinked loci for each of 93 strains collected worldwide, we detected a complex speciation process revealing overlapping reproductively isolated biological species, recent agamospecies and numerous relict lineages with unresolved phylogenetic positions. Genealogical concordance and recombination analyses confirm the existence of two genetically isolated agamospecies including T. harzianum sensu stricto and two hypothetical holomorphic species related to but different from H. lixii. The exact phylogenetic position of the majority of strains was not resolved and therefore attributed to a diverse network of recombining strains conventionally called 'pseudoharzianum matrix'. Since H. lixii and T. harzianum are evidently genetically isolated, the anamorph - teleomorph combination comprising H. lixii/T. harzianum in one holomorph must be rejected in favor of two separate species. Conclusions Our data illustrate a complex speciation within H. lixii - T. harzianum species group, which is based on coexistence and interaction of organisms with different evolutionary histories and on the absence of strict genetic borders between them. PMID:20359347

  11. Using Student Test Results for Accountability and Improvement: A Literature Review. OECD Education Working Papers, No. 54

    ERIC Educational Resources Information Center

    Rosenkvist, Morten A.

    2010-01-01

    This report discusses the most relevant issues concerning using student test results in OECD countries. Initially the report provides an overview of how student test results are reported in OECD countries and how stakeholders in these countries use and perceive of the results. The report then reviews the literature relating to using student test…

  12. Global atmospheric response to specific linear combinations of the main SST modes.. Part I: numerical experiments and preliminary results

    NASA Astrophysics Data System (ADS)

    Trzaska, S.; Moron, V.; Fontaine, B.

    1996-10-01

    This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO) phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns) were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the equatorial Atlantic are discussed. Results are coherent with observations and show that interhemispheric and regional scale sea-surface-temperature anomaly (SST) patterns could significantly modulate the impact of ENSO phenomena: the impact of warm-phase ENSO, relative to the atmospheric model intercomparison project (AMIP) climatology, seems stronger when embedded in global and regional SSTA patterns representative of the post-1970 conditions [i.e. with temperatures warmer (colder) than the long-term mean in the southern hemisphere (northern hemisphere)]. Atlantic SSTAs may also play a significant role. Acknowledgements. We gratefully appreciate the on-line DMSP database facility at APL (Newell et al., 1991) from which this study has benefited greatly. We wish to thank E. Friis-Christensen for his encouragement and useful discussions. A. Y. would like to thank the Danish Meteorological Institute, where this work was done, for its hospitality during his stay there and the Nordic Baltic Scholarship Scheme for its financial support of this stay. Topical Editor K.-H. Glassmeier thanks M. J. Engebretson and H. Lühr for their help in evaluating this paper.--> Correspondence to: A. Yahnin-->

  13. Finding the Data: A Start-Up List of Outcome Measures with Annotations. A Companion Document to "The Case for Shifting to Results-Based Accountability."

    ERIC Educational Resources Information Center

    Brown, Brett; Weitz, Judith

    Shifting to results-based accountability is a difficult stage in reforming family and children's services. Heretofore, these services have been more concerned with the number of clients seen or papers processed than in their clients' quality of life. This document should help communities find the data they need to measure qualitative outcomes. It…

  14. On the role of numerical simulations in studies of reduced gravity-induced physiological effects in humans. Results from NELME.

    NASA Astrophysics Data System (ADS)

    Perez-Poch, Antoni

    Computer simulations are becoming a promising research line of work, as physiological models become more and more sophisticated and reliable. Technological advances in state-of-the-art hardware technology and software allow nowadays for better and more accurate simulations of complex phenomena, such as the response of the human cardiovascular system to long-term exposure to microgravity. Experimental data for long-term missions are difficult to achieve and reproduce, therefore the predictions of computer simulations are of a major importance in this field. Our approach is based on a previous model developed and implemented in our laboratory (NELME: Numercial Evaluation of Long-term Microgravity Effects). The software simulates the behaviour of the cardiovascular system and different human organs, has a modular archi-tecture, and allows to introduce perturbations such as physical exercise or countermeasures. The implementation is based on a complex electrical-like model of this control system, using inexpensive development frameworks, and has been tested and validated with the available experimental data. The objective of this work is to analyse and simulate long-term effects and gender differences when individuals are exposed to long-term microgravity. Risk probability of a health impairement which may put in jeopardy a long-term mission is also evaluated. . Gender differences have been implemented for this specific work, as an adjustment of a number of parameters that are included in the model. Women versus men physiological differences have been therefore taken into account, based upon estimations from the physiology bibliography. A number of simulations have been carried out for long-term exposure to microgravity. Gravity varying continuosly from Earth-based to zero, and time exposure are the two main variables involved in the construction of results, including responses to patterns of physical aerobic ex-ercise and thermal stress simulating an extra

  15. Numerical analysis of wellbore integrity: results from a field study of a natural CO2 reservoir production well

    NASA Astrophysics Data System (ADS)

    Crow, W.; Gasda, S. E.; Williams, D. B.; Celia, M. A.; Carey, J. W.

    2008-12-01

    An important aspect of the risk associated with geological CO2 sequestration is the integrity of existing wellbores that penetrate geological layers targeted for CO2 injection. CO2 leakage may occur through multiple pathways along a wellbore, including through micro-fractures and micro-annuli within the "disturbed zone" surrounding the well casing. The effective permeability of this zone is a key parameter of wellbore integrity required for validation of numerical models. This parameter depends on a number of complex factors, including long-term attack by aggressive fluids, poor well completion and actions related to production of fluids through the wellbore. Recent studies have sought to replicate downhole conditions in the laboratory to identify the mechanisms and rates at which cement deterioration occurs. However, field tests are essential to understanding the in situ leakage properties of the millions of wells that exist in the mature sedimentary basins in North America. In this study, we present results from a field study of a 30-year-old production well from a natural CO2 reservoir. The wellbore was potentially exposed to a 96% CO2 fluid from the time of cement placement, and therefore cement degradation may be a significant factor leading to leakage pathways along this wellbore. A series of downhole tests was performed, including bond logs and extraction of sidewall cores. The cores were analyzed in the laboratory for mineralogical and hydrologic properties. A pressure test was conducted over an 11-ft section of well to determine the extent of hydraulic communication along the exterior of the well casing. Through analysis of this pressure test data, we are able estimate the effective permeability of the disturbed zone along the exterior of wellbore over this 11-ft section. We find the estimated range of effective permeability from the field test is consistent with laboratory analysis and bond log data. The cement interfaces with casing and/or formation are

  16. The accountable health care act of Massachusetts: mixed results for an experiment in universal health care coverage.

    PubMed

    Norbash, Alexander; Hindson, David; Heineke, Janelle

    2012-10-01

    The affordable health care act of Massachusetts, signed into law in 2006, resulted in 98% of Massachusetts residents' having some form of insurance coverage by 2011, the highest coverage rate for residents of any state in the nation. With a strong economy, a low unemployment rate, a robust health care delivery system, an extremely low number of undocumented immigrants, and a low baseline uninsured rate, Massachusetts was well positioned for such an effort. Ingredients included mandates, the creation of separate insurance vehicles directed to both poverty-level and non-poverty-level residents, and the reallocation of the former free care pool. The mandates included consumer mandates and employer mandates; the consumer mandate applies to all Massachusetts residents at the risk of losing personal state tax exemptions, and the employer mandate applies to all Massachusetts businesses with 10 or more employees at the risk of per employee financial penalties. The insurance vehicles were created with premiums allocated on the basis of ability to pay by income classes. Unexpected effects included escalating taxpayer health care costs, with taxpayers shouldering the burden for the newly insured, continuing escalating health care costs at a rate greater than the national average, overburdening primary caregivers as newly insured sought new primary care gatekeepers in a system with primary caregiver shortages, and deprivation of support to the safety-net hospitals as a result of siphoned commonwealth free care pool funds. This exercise demonstrates specific benefits and shortfalls of the Massachusetts health care reform experiment, given the conditions and circumstances found in Massachusetts at the time of implementation. PMID:23025869

  17. An open-loop ground-water heat pump system: transient numerical modeling and site experimental results

    NASA Astrophysics Data System (ADS)

    Lo Russo, S.; Taddia, G.; Gnavi, L.

    2012-04-01

    KEY WORDS: Open-loop ground water heat pump; Feflow; Low-enthalpy; Thermal Affected Zone; Turin; Italy The increasing diffusion of low-enthalpy geothermal open-loop Groundwater Heat Pumps (GWHP) providing buildings air conditioning requires a careful assessment of the overall effects on groundwater system, especially in the urban areas where several plants can be close together and interfere. One of the fundamental aspects in the realization of an open loop low-enthalpy geothermal system is therefore the capacity to forecast the effects of thermal alteration produced in the ground, induced by the geothermal system itself. The impact on the groundwater temperature in the surrounding area of the re-injection well (Thermal Affected Zone - TAZ) is directly linked to the aquifer properties. The transient dynamic of groundwater discharge and temperature variations should be also considered to assess the subsurface environmental effects of the plant. The experimental groundwater heat pump system used in this study is installed at the "Politecnico di Torino" (NW Italy, Piedmont Region). This plant provides summer cooling needs for the university buildings. This system is composed by a pumping well, a downgradient injection well and a control piezometer. The system is constantly monitored by multiparameter probes measuring the dynamic of groundwater temperature. A finite element subsurface flow and transport simulator (FEFLOW) was used to investigate the thermal aquifer alteration. Simulations were continuously performed during May-October 2010 (cooling period). The numerical simulation of the heat transport in the aquifer was solved with transient conditions. The simulation was performed by considering only the heat transfer within the saturated aquifer, without any heat dispersion above or below the saturated zone due to the lack of detailed information regarding the unsaturated zone. Model results were compared with experimental temperature data derived from groundwater

  18. On the Improvement of Numerical Weather Prediction by Assimilation of Hub Height Wind Information in Convection-Resulted Models

    NASA Astrophysics Data System (ADS)

    Declair, Stefan; Stephan, Klaus; Potthast, Roland

    2015-04-01

    Determining the amount of weather dependent renewable energy is a demanding task for transmission system operators (TSOs). In the project EWeLiNE funded by the German government, the German Weather Service and the Fraunhofer Institute on Wind Energy and Energy System Technology strongly support the TSOs by developing innovative weather- and power forecasting models and tools for grid integration of weather dependent renewable energy. The key in the energy prediction process chain is the numerical weather prediction (NWP) system. With focus on wind energy, we face the model errors in the planetary boundary layer, which is characterized by strong spatial and temporal fluctuations in wind speed, to improve the basis of the weather dependent renewable energy prediction. Model data can be corrected by postprocessing techniques such as model output statistics and calibration using historical observational data. On the other hand, latest observations can be used in a preprocessing technique called data assimilation (DA). In DA, the model output from a previous time step is combined such with observational data, that the new model data for model integration initialization (analysis) fits best to the latest model data and the observational data as well. Therefore, model errors can be already reduced before the model integration. In this contribution, the results of an impact study are presented. A so-called OSSE (Observation Simulation System Experiment) is performed using the convective-resoluted COSMO-DE model of the German Weather Service and a 4D-DA technique, a Newtonian relaxation method also called nudging. Starting from a nature run (treated as the truth), conventional observations and artificial wind observations at hub height are generated. In a control run, the basic model setup of the nature run is slightly perturbed to drag the model away from the beforehand generated truth and a free forecast is computed based on the analysis using only conventional

  19. Thermodiffusion in concentrated ferrofluids: A review and current experimental and numerical results on non-magnetic thermodiffusion

    SciTech Connect

    Sprenger, Lisa Lange, Adrian; Odenbach, Stefan

    2013-12-15

    Ferrofluids are colloidal suspensions consisting of magnetic nanoparticles dispersed in a carrier liquid. Their thermodiffusive behaviour is rather strong compared to molecular binary mixtures, leading to a Soret coefficient (S{sub T}) of 0.16 K{sup −1}. Former experiments with dilute magnetic fluids have been done with thermogravitational columns or horizontal thermodiffusion cells by different research groups. Considering the horizontal thermodiffusion cell, a former analytical approach has been used to solve the phenomenological diffusion equation in one dimension assuming a constant concentration gradient over the cell's height. The current experimental work is based on the horizontal separation cell and emphasises the comparison of the concentration development in different concentrated magnetic fluids and at different temperature gradients. The ferrofluid investigated is the kerosene-based EMG905 (Ferrotec) to be compared with the APG513A (Ferrotec), both containing magnetite nanoparticles. The experiments prove that the separation process linearly depends on the temperature gradient and that a constant concentration gradient develops in the setup due to the separation. Analytical one dimensional and numerical three dimensional approaches to solve the diffusion equation are derived to be compared with the solution used so far for dilute fluids to see if formerly made assumptions also hold for higher concentrated fluids. Both, the analytical and numerical solutions, either in a phenomenological or a thermodynamic description, are able to reproduce the separation signal gained from the experiments. The Soret coefficient can then be determined to 0.184 K{sup −1} in the analytical case and 0.29 K{sup −1} in the numerical case. Former theoretical approaches for dilute magnetic fluids underestimate the strength of the separation in the case of a concentrated ferrofluid.

  20. Thermodiffusion in concentrated ferrofluids: A review and current experimental and numerical results on non-magnetic thermodiffusion

    NASA Astrophysics Data System (ADS)

    Sprenger, Lisa; Lange, Adrian; Odenbach, Stefan

    2013-12-01

    Ferrofluids are colloidal suspensions consisting of magnetic nanoparticles dispersed in a carrier liquid. Their thermodiffusive behaviour is rather strong compared to molecular binary mixtures, leading to a Soret coefficient (ST) of 0.16 K-1. Former experiments with dilute magnetic fluids have been done with thermogravitational columns or horizontal thermodiffusion cells by different research groups. Considering the horizontal thermodiffusion cell, a former analytical approach has been used to solve the phenomenological diffusion equation in one dimension assuming a constant concentration gradient over the cell's height. The current experimental work is based on the horizontal separation cell and emphasises the comparison of the concentration development in different concentrated magnetic fluids and at different temperature gradients. The ferrofluid investigated is the kerosene-based EMG905 (Ferrotec) to be compared with the APG513A (Ferrotec), both containing magnetite nanoparticles. The experiments prove that the separation process linearly depends on the temperature gradient and that a constant concentration gradient develops in the setup due to the separation. Analytical one dimensional and numerical three dimensional approaches to solve the diffusion equation are derived to be compared with the solution used so far for dilute fluids to see if formerly made assumptions also hold for higher concentrated fluids. Both, the analytical and numerical solutions, either in a phenomenological or a thermodynamic description, are able to reproduce the separation signal gained from the experiments. The Soret coefficient can then be determined to 0.184 K-1 in the analytical case and 0.29 K-1 in the numerical case. Former theoretical approaches for dilute magnetic fluids underestimate the strength of the separation in the case of a concentrated ferrofluid.

  1. Teaching Accounting with Computers.

    ERIC Educational Resources Information Center

    Shaoul, Jean

    This paper addresses the numerous ways that computers may be used to enhance the teaching of accounting and business topics. It focuses on the pedagogical use of spreadsheet software to improve the conceptual coverage of accounting principles and practice, increase student understanding by involvement in the solution process, and reduce the amount…

  2. Results from a Field Trial of the Radio Frequency Based Cylinder Accountability and Tracking System at the Global Nuclear Fuel Americas Fuel Fabrication Facility

    SciTech Connect

    Fitzgerald, Peter; Laughter, Mark D; Martyn, Rose; Pickett, Chris A; Rowe, Nathan C; Younkin, James R; Shephard, Adam M

    2010-01-01

    The Cylinder Accountability and Tracking System (CATS) is a tool designed for use by the International Atomic Energy Agency (IAEA) to improve overall inspector efficiency through real-time unattended monitoring of cylinder movements, site specific rules-based event detection, and the capability to integrate many types of monitoring technologies. The system is based on the tracking of cylinder movements using (radio frequency) RF tags, and the collection of data, such as accountability weights, that can be associated with the cylinders. This presentation will cover the installation and evaluation of the CATS at the Global Nuclear Fuels (GNF) fuel fabrication facility in Wilmington, NC. This system was installed to evaluate its safeguards applicability, operational durability under operating conditions, and overall performance. An overview of the system design and elements specific to the GNF deployment will be presented along with lessons learned from the installation process and results from the field trial.

  3. Influence the temperatures of the surface and gaseous environment of Mercury on IR radiance spectra -the results of numerical simulation

    NASA Astrophysics Data System (ADS)

    Blecka, Maria I.

    Mercury's atmosphere is very thin and is mainly made out of sodium but also tracers like potassium, oxygen and tiny amount of helium have been detected. There are various sources which provide supply of gases to the surface of the planet. The major sources are: the Solar Wind, which delivers hydrogen and helium, meteoritic impacts, which vaporize the surface rocks, and as the incoming objects, provides a small amounts of oxygen, iron, silicon and other components to the gaseous mixture, and also "volcanic" events as a sources of sulfurous gases can appear. The surface of Mercury shows quite extreme differences in temperature from one place to another, as well as temporal variations. The differences that occur are due to changes in distance from the Sun, day/night differences and changes, related to the latitude. The model we present provides estimates of the spectral radiance of Mercury in the Mid-Infrared spectral range. In our simulation the cumulative effects of the surface and detected species of the thin atmosphere of Mercury have been taken into account. The spectral shape of emissivity, taken from existing databases or published papers, characteristic for already known mineralogical composition were used. The various temperatures of the surface and parameters of the atmosphere have been taken into account. Our calculations are directly connected with the future spectrometric measurements of "MERTIS" on Bepi Colombo mission to Mercury. We expect that the future interpretation of data will benefit from our simulation of the signal to be acquired.

  4. Numerical simulations - Some results for the 2- and 3-D Hubbard models and a 2-D electron phonon model

    NASA Technical Reports Server (NTRS)

    Scalapino, D. J.; Sugar, R. L.; White, S. R.; Bickers, N. E.; Scalettar, R. T.

    1989-01-01

    Numerical simulations on the half-filled three-dimensional Hubbard model clearly show the onset of Neel order. Simulations of the two-dimensional electron-phonon Holstein model show the competition between the formation of a Peierls-CDW state and a superconducting state. However, the behavior of the partly filled two-dimensional Hubbard model is more difficult to determine. At half-filling, the antiferromagnetic correlations grow as T is reduced. Doping away from half-filling suppresses these correlations, and it is found that there is a weak attractive pairing interaction in the d-wave channel. However, the strength of the pair field susceptibility is weak at the temperatures and lattice sizes that have been simulated, and the nature of the low-temperature state of the nearly half-filled Hubbard model remains open.

  5. Static correlations in macro-ionic suspensions: Analytic and numerical results in a hypernetted-chain-mean-spherical approximation

    NASA Astrophysics Data System (ADS)

    Khan, Sheema; Morton, Thomas L.; Ronis, David

    1987-05-01

    The static correlations in highly charged colloidal and micellar suspensions, with and without added electrolyte, are examined using the hypernetted-chain approximation (HNC) for the macro-ion-macro-ion correlations and the mean-spherical approximation for the other correlations. By taking the point-ion limit for the counter-ions, an analytic solution for the counter-ion part of the problem can be obtained; this maps the macro-ion part of the problem onto a one-component problem where the macro-ions interact via a screened Coulomb potential with the Gouy-Chapman form for the screening length and an effective charge that depends on the macro-ion-macro-ion pair correlations. Numerical solutions of the effective one-component equation in the HNC approximation are presented, and in particular, the effects of macro-ion charge, nonadditive core diameters, and added electrolyte are examined. As we show, there can be a strong renormalization of the effective macro-ion charge and reentrant melting in colloidal crystals.

  6. Comparison between the results of the two and three-dimensional numerical simulations in an aortic bifurcation model

    NASA Astrophysics Data System (ADS)

    Deplano, V.; Pelissier, R.; Rieu, R.; Bontoux, P.

    1994-01-01

    Bifurcations are vascular singularities of interest because they are the privileged sites of atherosclerosis deposits, particularly the sites corresponding to wall shear stress extrema. The purpose of this paper is to compare the two- and three-dimensional characteristics of the velocity fields, the shear stress distributions and the secondary flows in a symmetrical aortic bifurcation. The branching angle is equal to 60^{circ} and the branch-to-trunk area ratio to 0.8. The numerical simulations are performed using the FIDAP programme. Although restrictive by the hypotheses of steady flow and rigid channel, with rectangular cross-sections, this study shows the importance of the three-dimensional effects in particular as far as concerned the wall shear stress behaviours. Les bifurcations sont des singularités vasculaires présentant un intérêt particulier car elles sont le site privilégié de dépôts athéromateux ; la localisation de ces dépôts dépendant des valeurs maximum du cisaillement en paroi. L'objectif de cette étude est de comparer les caractéristiques bidimensionnels et tridimensionnels des champs de vitesse, de la distribution du cisaillement pariétal et des écoulements secondaires dans un modèle de bifurcation aortique. L'angle de bifurcation est de 60^{circ} et le rapport des sections branche fille branche mère est de 0,8. Les simulations numériques sont effectuées sur la base du logiciel FIDAP. Bien que restrictifs de part certaines hypothèses, écoulement permanent dans un modèle de bifurcation rigide avec des sections rectangulaires, ces travaux montrent l'importance des effets tridimensionnels notamment au niveau du cisaillement pariétal.

  7. Ephemeral liquid water at the surface of the martian North Polar Residual Cap: Results of numerical modelling

    NASA Astrophysics Data System (ADS)

    Losiak, Anna; Czechowski, Leszek; Velbel, Michael A.

    2015-12-01

    Gypsum, a mineral that requires water to form, is common on the surface of Mars. Most of it originated before 3.5 Gyr when the Red Planet was more humid than now. However, occurrences of gypsum dune deposits around the North Polar Residual Cap (NPRC) seem to be surprisingly young: late Amazonian in age. This shows that liquid water was present on Mars even at times when surface conditions were as cold and dry as the present-day. A recently proposed mechanism for gypsum formation involves weathering of dust within ice (e.g., Niles, P.B., Michalski, J. [2009]. Nat. Geosci. 2, 215-220.). However, none of the previous studies have determined if this process is possible under current martian conditions. Here, we use numerical modelling of heat transfer to show that during the warmest days of the summer, solar irradiation may be sufficient to melt pure water ice located below a layer of dark dust particles (albedo ⩽ 0.13) lying on the steepest sections of the equator-facing slopes of the spiral troughs within martian NPRC. During the times of high irradiance at the north pole (every 51 ka; caused by variation of orbital and rotational parameters of Mars e.g., Laskar, J. et al. [2002]. Nature 419, 375-377.) this process could have taken place over larger parts of the spiral troughs. The existence of small amounts of liquid water close to the surface, even under current martian conditions, fulfils one of the main requirements necessary to explain the formation of the extensive gypsum deposits around the NPRC. It also changes our understanding of the degree of current geological activity on Mars and has important implications for estimating the astrobiological potential of Mars.

  8. Analysis of the global free infra-gravity wave climate for the SWOT mission, and preliminary results of numerical modelling

    NASA Astrophysics Data System (ADS)

    Rawat, A.; Aucan, J.; Ardhuin, F.

    2012-12-01

    All sea level variations of the order of 1 cm at scales under 30 km are of great interest for the future Surface Water Ocean Topography (SWOT) satellite mission. That satellite should provide high-resolution maps of the sea surface height for analysis of meso to sub-mesoscale currents, but that will require a filtering of all gravity wave motions in the data. Free infragravity waves (FIGWs) are generated and radiate offshore when swells and/or wind seas and their associated bound infragravity waves impact exposed coastlines. Free infragravity waves have dominant periods comprised between 1 and 10 minutes and horizontal wavelengths of up to tens of kilometers. Given the length scales of the infragravity waves wavelength and amplitude, the infragravity wave field will can a significant fraction the signal measured by the future SWOT mission. In this study, we analyze the data from recovered bottom pressure recorders of the Deep-ocean Assessment and Reporting of Tsunami (DART) program. This analysis includes data spanning several years between 2006 and 2010, from stations at different latitudes in the North and South Pacific, the North Atlantic, the Gulf of Mexico and the Caribbean Sea. We present and discuss the following conclusions: (1) The amplitude of free infragravity waves can reach several centimeters, higher than the precision sought for the SWOT mission. (2) The free infragravity signal is higher in the Eastern North Pacific than in the Western North Pacific, possibly due to smaller incident swell and seas impacting the nearby coastlines. (3) Free infragravity waves are higher in the North Pacific than in the North Atlantic, possibly owing to different average continental shelves configurations in the two basins. (4) There is a clear seasonal cycle at the high latitudes North Atlantic and Pacific stations that is much less pronounced or absent at the tropical stations, consistent with the generation mechanism of free infragravity waves. Our numerical model

  9. A comparison of the predictions of a simple kinetic theory with experimental and numerical results for a vibrated granular bed consisting of nearly elastic particles of two sizes

    NASA Astrophysics Data System (ADS)

    Wildman, R. D.; Jenkins, J. T.; Krouskop, P. E.; Talbot, J.

    2006-07-01

    A comparison of the predictions of a simple kinetic theory with experimental and numerical results for a vibrated granular bed consisting of nearly elastic particles of two sizes has been performed. The results show good agreement between the data sets for a range of numbers of each size of particle, and are particularly good for particle beds containing similar proportions of each species. The agreement suggests that such a model may be a good starting point for describing polydisperse systems of granular flows.

  10. Evaluation of ground-penetrating radar to detect free-phase hydrocarbons in fractured rocks - Results of numerical modeling and physical experiments

    USGS Publications Warehouse

    Lane, J.W.; Buursink, M.L.; Haeni, F.P.; Versteeg, R.J.

    2000-01-01

    The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons in bedrock fractures was evaluated using numerical modeling and physical experiments. The results of one- and two-dimensional numerical modeling at 100 megahertz indicate that GPR reflection amplitudes are relatively insensitive to fracture apertures ranging from 1 to 4 mm. The numerical modeling and physical experiments indicate that differences in the fluids that fill fractures significantly affect the amplitude and the polarity of electromagnetic waves reflected by subhorizontal fractures. Air-filled and hydrocarbon-filled fractures generate low-amplitude reflections that are in-phase with the transmitted pulse. Water-filled fractures create reflections with greater amplitude and opposite polarity than those reflections created by air-filled or hydrocarbon-filled fractures. The results from the numerical modeling and physical experiments demonstrate it is possible to distinguish water-filled fracture reflections from air- or hydrocarbon-filled fracture reflections, nevertheless subsurface heterogeneity, antenna coupling changes, and other sources of noise will likely make it difficult to observe these changes in GPR field data. This indicates that the routine application of common-offset GPR reflection methods for detection of hydrocarbon-filled fractures will be problematic. Ideal cases will require appropriately processed, high-quality GPR data, ground-truth information, and detailed knowledge of subsurface physical properties. Conversely, the sensitivity of GPR methods to changes in subsurface physical properties as demonstrated by the numerical and experimental results suggests the potential of using GPR methods as a monitoring tool. GPR methods may be suited for monitoring pumping and tracer tests, changes in site hydrologic conditions, and remediation activities.The suitability of common-offset ground-penetrating radar (GPR) to detect free-phase hydrocarbons

  11. Direct Numerical Simulation of Liquid Nozzle Spray with Comparison to Shadowgraphy and X-Ray Computed Tomography Experimental Results

    NASA Astrophysics Data System (ADS)

    van Poppel, Bret; Owkes, Mark; Nelson, Thomas; Lee, Zachary; Sowell, Tyler; Benson, Michael; Vasquez Guzman, Pablo; Fahrig, Rebecca; Eaton, John; Kurman, Matthew; Kweon, Chol-Bum; Bravo, Luis

    2014-11-01

    In this work, we present high-fidelity Computational Fluid Dynamics (CFD) results of liquid fuel injection from a pressure-swirl atomizer and compare the simulations to experimental results obtained using both shadowgraphy and phase-averaged X-ray computed tomography (CT) scans. The CFD and experimental results focus on the dense near-nozzle region to identify the dominant mechanisms of breakup during primary atomization. Simulations are performed using the NGA code of Desjardins et al (JCP 227 (2008)) and employ the volume of fluid (VOF) method proposed by Owkes and Desjardins (JCP 270 (2013)), a second order accurate, un-split, conservative, three-dimensional VOF scheme providing second order density fluxes and capable of robust and accurate high density ratio simulations. Qualitative features and quantitative statistics are assessed and compared for the simulation and experimental results, including the onset of atomization, spray cone angle, and drop size and distribution.

  12. Educational Accountability

    ERIC Educational Resources Information Center

    Pincoffs, Edmund L.

    1973-01-01

    Discusses educational accountability as the paradigm of performance contracting, presents some arguments for and against accountability, and discusses the goals of education and the responsibility of the teacher. (Author/PG)

  13. Numerical evaluation of cavitation shedding structure around 3D Hydrofoil: Comparison of PANS, LES and RANS results with experiments

    NASA Astrophysics Data System (ADS)

    Ji, B.; Peng, X. X.; Long, X. P.; Luo, X. W.; Wu, Y. L.

    2015-12-01

    Results of cavitating turbulent flow simulation around a twisted hydrofoil were presented in the paper using the Partially-Averaged Navier-Stokes (PANS) method (Ji et al. 2013a), Large-Eddy Simulation (LES) (Ji et al. 2013b) and Reynolds-Averaged Navier-Stokes (RANS). The results are compared with available experimental data (Foeth 2008). The PANS and LES reasonably reproduce the cavitation shedding patterns around the twisted hydrofoil with primary and secondary shedding, while the RANS model fails to simulate the unsteady cavitation shedding phenomenon and yields an almost steady flow with a constant cavity shape and vapor volume. Besides, it is noted that the predicted shedding vapor cavity by PANS is more turbulent and the shedding vortex is stronger than that by LES, which is more consistent with experimental photos.

  14. Influence of the quantum well models on the numerical simulation of planar InGaN/GaN LED results

    NASA Astrophysics Data System (ADS)

    Podgórski, J.; Woźny, J.; Lisik, Z.

    2016-04-01

    Within this paper, we present electric model of a light emitting diode (LED) made of gallium nitride (GaN) followed by examples of simulation results obtained by means of Sentaurus software, which is the part of the TCAD package. The aim of this work is to answer the question of whether physical models of quantum wells used in commercial software are suitable for a correct analysis of the lateral LEDs made of GaN.

  15. Numerical study of the SSME nozzle flow fields during transient operations: A comparison of the animated results with test

    NASA Technical Reports Server (NTRS)

    Wang, Ten-See; Dumas, Catherine

    1993-01-01

    A computational fluid dynamics (CFD) model has been applied to study the transient flow phenomena of the nozzle and exhaust plume of the Space Shuttle Main Engine (SSME), fired at sea level. The CFD model is a time accurate, pressure based, reactive flow solver. A six-species hydrogen/oxygen equilibrium chemistry is used to describe the chemical-thermodynamics. An adaptive upwinding scheme is employed for the spatial discretization, and a predictor, multiple corrector method is used for the temporal solution. Both engine start-up and shut-down processes were simulated. The elapse time is approximately five seconds for both cases. The computed results were animated and compared with the test. The images for the animation were created with PLOT3D and FAST and then animated with ABEKAS. The hysteresis effects, and the issues of free-shock separation, restricted-shock separation and the end-effects were addressed.

  16. Simulated forecast error and climate drift resulting from the omission of the upper stratosphere in numerical models

    NASA Technical Reports Server (NTRS)

    Boville, Byron A.; Baumhefner, David P.

    1990-01-01

    Using an NCAR community climate model, Version I, the forecast error growth and the climate drift resulting from the omission of the upper stratosphere are investigated. In the experiment, the control simulation is a seasonal integration of a medium horizontal general circulation model with 30 levels extending from the surface to the upper mesosphere, while the main experiment uses an identical model, except that only the bottom 15 levels (below 10 mb) are retained. It is shown that both random and systematic errors develop rapidly in the lower stratosphere with some local propagation into the troposphere in the 10-30-day time range. The random growth rate in the troposphere in the case of the altered upper boundary was found to be slightly faster than that for the initial-condition uncertainty alone. However, this is not likely to make a significant impact in operational forecast models, because the initial-condition uncertainty is very large.

  17. Application of the dynamic model of Saeman to an industrial rotary kiln incinerator: numerical and experimental results.

    PubMed

    Ndiaye, L G; Caillat, S; Chinnayya, A; Gambier, D; Baudoin, B

    2010-07-01

    In order to simulate granular materials structure in a rotary kiln under the steady-state regime, a mathematical model has been developed by Saeman (1951). This model enables the calculation of the bed profiles, the axial velocity and solids flow rate along the kiln. This model can be coupled with a thermochemical model, in the case of a reacting moving bed. This dynamic model was used to calculate the bed profile for an industrial size kiln and the model projections were validated by measurements in a 4 m diameter by 16 m long industrial rotary kiln. The effect of rotation speed under solids bed profile and the effect of the feed rate under filling degree were established. On the basis of the calculations and the experimental results a phenomenological relation for the residence time estimation was proposed for the rotary kiln.

  18. Viscous effects in rapidly rotating stars with application to white-dwarf models. III - Further numerical results

    NASA Technical Reports Server (NTRS)

    Durisen, R. H.

    1975-01-01

    Improved viscous evolutionary sequences of differentially rotating, axisymmetric, nonmagnetic, zero-temperature white-dwarf models are constructed using the relativistically corrected degenerate electron viscosity. The results support the earlier conclusion that angular momentum transport due to viscosity does not lead to overall uniform rotation in many interesting cases. Qualitatively different behaviors are obtained, depending on how the total mass M and angular momentum J compare with the M and J values for which uniformly rotating models exist. Evolutions roughly determine the region in M and J for which models with a particular initial angular momentum distribution can reach carbon-ignition densities in 10 b.y. Such models may represent Type I supernova precursors.

  19. Coupling of charged particles via Coulombic interactions: Numerical simulations and resultant kappa-like velocity space distribution functions

    NASA Astrophysics Data System (ADS)

    Randol, Brent M.; Christian, Eric R.

    2016-03-01

    A parametric study is performed using the electrostatic simulations of Randol and Christian in which the number density, n, and initial thermal speed, θ, are varied. The range of parameters covers an extremely broad plasma regime, all the way from the very weak coupling of space plasmas to the very strong coupling of solid plasmas. The first result is that simulations at the same ΓD, where ΓD (∝ n1/3θ-2) is the plasma coupling parameter, but at different combinations of n and θ, behave exactly the same. As a function of ΓD, the form of p(v), the velocity distribution function of v, the magnitude of v, the velocity vector, is studied. For intermediate to high ΓD, heating is observed in p(v) that obeys conservation of energy, and a suprathermal tail is formed, with a spectral index that depends on ΓD. For strong coupling (ΓD≫1), the form of the tail is v-5, consistent with the findings of Randol and Christian). For weak coupling (ΓD≪1), no acceleration or heating occurs, as there is no free energy. The dependence on N, the number of particles in the simulation, is also explored. There is a subtle dependence in the index of the tail, such that v-5 appears to be the N→∞ limit.

  20. Computer code for scattering from impedance bodies of revolution. Part 3: Surface impedance with s and phi variation. Analytical and numerical results

    NASA Technical Reports Server (NTRS)

    Uslenghi, Piergiorgio L. E.; Laxpati, Sharad R.; Kawalko, Stephen F.

    1993-01-01

    The third phase of the development of the computer codes for scattering by coated bodies that has been part of an ongoing effort in the Electromagnetics Laboratory of the Electrical Engineering and Computer Science Department at the University of Illinois at Chicago is described. The work reported discusses the analytical and numerical results for the scattering of an obliquely incident plane wave by impedance bodies of revolution with phi variation of the surface impedance. Integral equation formulation of the problem is considered. All three types of integral equations, electric field, magnetic field, and combined field, are considered. These equations are solved numerically via the method of moments with parametric elements. Both TE and TM polarization of the incident plane wave are considered. The surface impedance is allowed to vary along both the profile of the scatterer and in the phi direction. Computer code developed for this purpose determines the electric surface current as well as the bistatic radar cross section. The results obtained with this code were validated by comparing the results with available results for specific scatterers such as the perfectly conducting sphere. Results for the cone-sphere and cone-cylinder-sphere for the case of an axially incident plane were validated by comparing the results with the results with those obtained in the first phase of this project. Results for body of revolution scatterers with an abrupt change in the surface impedance along both the profile of the scatterer and the phi direction are presented.

  1. SLAC E155 and E155x Numeric Data Results and Data Plots: Nucleon Spin Structure Functions

    DOE Data Explorer

    The nucleon spin structure functions g1 and g2 are important tools for testing models of nucleon structure and QCD. Experiments at CERN, DESY, and SLAC have measured g1 and g2 using deep inelastic scattering of polarized leptons on polarized nucleon targets. The results of these experiments have established that the quark component of the nucleon helicity is much smaller than naive quark-parton model predictions. The Bjorken sum rule has been confirmed within the uncertainties of experiment and theory. The experiment E155 at SLAC collected data in March and April of 1997. Approximately 170 million scattered electron events were recorded to tape. (Along with several billion inclusive hadron events.) The data were collected using three independent fixed-angle magnetic spectrometers, at approximately 2.75, 5.5, and 10.5 degrees. The momentum acceptance of the 2.75 and 5.5 degree spectrometers ranged from 10 to 40 GeV, with momentum resolution of 2-4%. The 10.5 degree spectrometer, new for E155, accepted events of 7 GeV to 20 GeV. Each spectrometer used threshold gas Cerenkov counters (for particle ID), a segmented lead-glass calorimeter (for energy measurement and particle ID), and plastic scintillator hodoscopes (for tracking and momentum measurement). The polarized targets used for E155 were 15NH3 and 6LiD, as targets for measuring the proton and deuteron spin structure functions respectively. Experiment E155x recently concluded a successful two-month run at SLAC. The experiment was designed to measure the transverse spin structure functions of the proton and deuteron. The E155 target was also recently in use at TJNAF's Hall C (E93-026) and was returned to SLAC for E155x. E155x hopes to reduce the world data set errors on g2 by a factor of three. [Copied from http://www.slac.stanford.edu/exp/e155/e155_nickeltour.html, an information summary linked off the E155 home page at http://www.slac.stanford.edu/exp/e155/e155_home.html. The extension run, E155x, also makes

  2. Results.

    ERIC Educational Resources Information Center

    Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

    2001-01-01

    Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)

  3. On the energy dependence of the radial diffusion coefficient and spectra of inner radiation belt particles - Analytic solutions and comparison with numerical results

    NASA Technical Reports Server (NTRS)

    Westphalen, H.; Spjeldvik, W. N.

    1982-01-01

    A theoretical method by which the energy dependence of the radial diffusion coefficient may be deduced from spectral observations of the particle population at the inner edge of the earth's radiation belts is presented. This region has previously been analyzed with numerical techniques; in this report an analytical treatment that illustrates characteristic limiting cases in the L shell range where the time scale of Coulomb losses is substantially shorter than that of radial diffusion (L approximately 1-2) is given. It is demonstrated both analytically and numerically that the particle spectra there are shaped by the energy dependence of the radial diffusion coefficient regardless of the spectral shapes of the particle populations diffusing inward from the outer radiation zone, so that from observed spectra the energy dependence of the diffusion coefficient can be determined. To insure realistic simulations, inner zone data obtained from experiments on the DIAL, AZUR, and ESRO 2 spacecraft have been used as boundary conditions. Excellent agreement between analytic and numerical results is reported.

  4. Simultaneous Raman-Rayleigh-LIF Measurements and Numerical Modeling Results of a Lifted H2/N2 Turbulent Jet Flame in a Vitiated Coflow

    NASA Technical Reports Server (NTRS)

    Cabra, R.; Chen, J. Y.; Dibble, R. W.; Hamano, Y.; Karpetis, A. N.; Barlow, R. S.

    2002-01-01

    An experimental and numerical investigation is presented of a H2/N2 turbulent jet flame burner that has a novel vitiated coflow. The vitiated coflow emulates the recirculation region of most combustors, such as gas turbines or furnaces. Additionally, since the vitiated gases are coflowing, the burner allows for exploration of recirculation chemistry without the corresponding fluid mechanics of recirculation. Thus the vitiated coflow burner design facilitates the development of chemical kinetic combustion models without the added complexity of recirculation fluid mechanics. Scalar measurements are reported for a turbulent jet flame of H2/N2 in a coflow of combustion products from a lean ((empty set) = 0.25) H2/Air flame. The combination of laser-induced fluorescence, Rayleigh scattering, and Raman scattering is used to obtain simultaneous measurements of the temperature, major species, as well as OH and NO. Laminar flame calculation with equal diffusivity do agree when the premixing and preheating that occurs prior to flame stabilization is accounted for in the boundary conditions. Also presented is an exploratory pdf model that predicts the flame's axial profiles fairly well, but does not accurately predict the lift-off height.

  5. Numerical Relativity

    NASA Technical Reports Server (NTRS)

    Baker, John G.

    2009-01-01

    Recent advances in numerical relativity have fueled an explosion of progress in understanding the predictions of Einstein's theory of gravity, General Relativity, for the strong field dynamics, the gravitational radiation wave forms, and consequently the state of the remnant produced from the merger of compact binary objects. I will review recent results from the field, focusing on mergers of two black holes.

  6. Very high temperature laminar flow of a gas through the entrance region of a cooled tube - Numerical calculations and experimental results.

    NASA Technical Reports Server (NTRS)

    Back, L. H.

    1972-01-01

    The laminar flow equations in differential form are solved numerically on a digital computer for flow of a very high temperature gas through the entrance region of an externally cooled tube. The solution method is described and calculations are carried out in conjunction with experimental measurements. The agreement with experiment is good, with the result indicating relatively large energy and momentum losses in the highly cooled flows considered where the pressure is nearly uniform along the flow and the core flow becomes non-adiabatic a few diameters downstream of the inlet. The effects of a large range of Reynolds number and Mach number (viscous dissipation) are also investigated.

  7. Numerical nebulae

    NASA Astrophysics Data System (ADS)

    Rijkhorst, Erik-Jan

    2005-12-01

    The late stages of evolution of stars like our Sun are dominated by several episodes of violent mass loss. Space based observations of the resulting objects, known as Planetary Nebulae, show a bewildering array of highly symmetric shapes. The interplay between gasdynamics and radiative processes determines the morphological outcome of these objects, and numerical models for astrophysical gasdynamics have to incorporate these effects. This thesis presents new numerical techniques for carrying out high-resolution three-dimensional radiation hydrodynamical simulations. Such calculations require parallelization of computer codes, and the use of state-of-the-art supercomputer technology. Numerical models in the context of the shaping of Planetary Nebulae are presented, providing insight into their origin and fate.

  8. The formation of open fractures in brittle rocks and the evolution of permeability with fault slip- results from analogue and numerical models

    NASA Astrophysics Data System (ADS)

    van Gent, H. W.; Abe, S.; Urai, J. L.; Holland, M.

    2009-04-01

    The formation of open cavities as a result of (normal) faulting of a brittle material under low effective stress has profound effects on the hydraulic properties of rocks both near the surface and at depth. It is however often difficult to access the fault zone directly. Here we present the results from a series of analogue models of normal faults in brittle rocks. Fine grained, dry Hemihydrate powder (CaSO4 * 1/2 H2O) was used as the truly cohesive analogue material. An extensive characterization of material properties, including the porosity dependency of both tensile strength and cohesion, showed the increase of strength of the powder with burial in the experimental box. In side view observations of the analogue models three structural zones were distinguished; a pure tensile failure zone at the surface and pure shear failure zone near the bottom of the box. At mid-depths we observed a transitional zone with mixed mode failure and the formation of fault cavities. These cavities initiate at local dip-changes of the fault and can collapse with progressive deformation. The transitions between these zones can be directly related to the increase of material strength due to burial compaction. The intercalation of relatively softer sand layers and relatively stronger layers of a hemihydrate and graphite mixture resulted in a marked increase of the complexity of the fault zone, but the three structural zones remain clearly visible. The sand layers can form decollement surfaces and "sand-smears". The observed structures compare well with fault outcrops and fault related cave systems in carbonates, basalts and consolidated sandstone. We used Particle Image Velocimetry (PIV) to quantify deformation and strain and observed plastic deformation prior to brittle failure at increments to small for visual inspection. However, the forces involved remain largely unknown. Therefore we have used the Discrete Element Method (DEM) to numerically model the formation of open fractures

  9. Simultaneous Laser Raman-rayleigh-lif Measurements and Numerical Modeling Results of a Lifted Turbulent H2/N2 Jet Flame in a Vitiated Coflow

    NASA Technical Reports Server (NTRS)

    Cabra, R.; Chen, J. Y.; Dibble, R. W.; Myhrvold, T.; Karpetis, A. N.; Barlow, R. S.

    2002-01-01

    An experiment and numerical investigation is presented of a lifted turbulent H2/N2 jet flame in a coflow of hot, vitiated gases. The vitiated coflow burner emulates the coupling of turbulent mixing and chemical kinetics exemplary of the reacting flow in the recirculation region of advanced combustors. It also simplifies numerical investigation of this coupled problem by removing the complexity of recirculating flow. Scalar measurements are reported for a lifted turbulent jet flame of H2/N2 (Re = 23,600, H/d = 10) in a coflow of hot combustion products from a lean H2/Air flame ((empty set) = 0.25, T = 1,045 K). The combination of Rayleigh scattering, Raman scattering, and laser-induced fluorescence is used to obtain simultaneous measurements of temperature and concentrations of the major species, OH, and NO. The data attest to the success of the experimental design in providing a uniform vitiated coflow throughout the entire test region. Two combustion models (PDF: joint scalar Probability Density Function and EDC: Eddy Dissipation Concept) are used in conjunction with various turbulence models to predict the lift-off height (H(sub PDF)/d = 7,H(sub EDC)/d = 8.5). Kalghatgi's classic phenomenological theory, which is based on scaling arguments, yields a reasonably accurate prediction (H(sub K)/d = 11.4) of the lift-off height for the present flame. The vitiated coflow admits the possibility of auto-ignition of mixed fluid, and the success of the present parabolic implementation of the PDF model in predicting a stable lifted flame is attributable to such ignition. The measurements indicate a thickened turbulent reaction zone at the flame base. Experimental results and numerical investigations support the plausibility of turbulent premixed flame propagation by small scale (on the order of the flame thickness) recirculation and mixing of hot products into reactants and subsequent rapid ignition of the mixture.

  10. A Pariah Profession? Some Student Perceptions of Accounting and Accountancy.

    ERIC Educational Resources Information Center

    Fisher, Roy; Murphy, Vivienne

    1995-01-01

    Existing literature and a survey of 106 undergraduate accounting students in the United Kingdom were analyzed for perceptions of the accounting profession and the academic discipline of accounting. Results suggest that among accounting and nonaccounting students alike, there exist coexisting perceptions of accounting as having high status and low…

  11. Accountability and Institutional Research: Measuring Results. Proceedings of the Annual Conference of the North East Association for Institutional Research (24th, Hartford, Connecticut, November 1-4, 1997).

    ERIC Educational Resources Information Center

    North East Association for Institutional Research.

    This proceedings document is comprised of the 12 papers, panel presentations, and work shares presented at a 1997 conference on institutional research. The papers are: (1) "What Does Accountability in Higher Education Mean to You?" (William R. Dyson, Andrew G. De Rocco, John R. Doyle, and Merle W. Harris); (2) "The University of Delaware…

  12. Accountability for the Results of Educating Students with Disabilities: Assessment Conference Report on the New Assessment Provisions of the 1997 Amendments to the Individuals with Disabilities Education Act.

    ERIC Educational Resources Information Center

    Ysseldyke, James E.; Thurlow, Martha L.; Kozleski, Elizabeth; Reschly, Daniel

    Based on the findings of a 1998 conference on the new assessment and accountability requirements in the Individuals with Disabilities Education Act (IDEA), this report discusses critical issues that surround the assessment provisions included in the 1997 IDEA amendments and contains recommendations related to state and district-wide assessments…

  13. The measurement of enhancement in mathematical abilities as a result of joint cognitive trainings in numerical and visual- spatial skills: A preliminary study

    NASA Astrophysics Data System (ADS)

    Agus, M.; Mascia, M. L.; Fastame, M. C.; Melis, V.; Pilloni, M. C.; Penna, M. P.

    2015-02-01

    A body of literature shows the significant role of visual-spatial skills played in the improvement of mathematical skills in the primary school. The main goal of the current study was to investigate the impact of a combined visuo-spatial and mathematical training on the improvement of mathematical skills in 146 second graders of several schools located in Italy. Participants were presented single pencil-and-paper visuo-spatial or mathematical trainings, computerised version of the above mentioned treatments, as well as a combined version of computer-assisted and pencil-and-paper visuo-spatial and mathematical trainings, respectively. Experimental groups were presented with training for 3 months, once a week. All children were treated collectively both in computer-assisted or pencil-and-paper modalities. At pre and post-test all our participants were presented with a battery of objective tests assessing numerical and visuo-spatial abilities. Our results suggest the positive effect of different types of training for the empowerment of visuo-spatial and numerical abilities. Specifically, the combination of computerised and pencil-and-paper versions of visuo-spatial and mathematical trainings are more effective than the single execution of the software or of the pencil-and-paper treatment.

  14. Accountability Overboard

    ERIC Educational Resources Information Center

    Chieppo, Charles D.; Gass, James T.

    2009-01-01

    This article reports that special interest groups opposed to charter schools and high-stakes testing have hijacked Massachusetts's once-independent board of education and stand poised to water down the Massachusetts Comprehensive Assessment System (MCAS) tests and the accountability system they support. President Barack Obama and Massachusetts…

  15. Painless Accountability.

    ERIC Educational Resources Information Center

    Brown, R. W.; And Others

    The computerized Painless Accountability System is a performance objective system from which instructional programs are developed. Three main simplified behavioral response levels characterize this system: (1) cognitive, (2) psychomotor, and (3) affective domains. Each of these objectives are classified by one of 16 descriptors. The second major…

  16. Accounting Specialist.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This publication identifies 20 subjects appropriate for use in a competency list for the occupation of accounting specialist, 1 of 12 occupations within the business/computer technologies cluster. Each unit consists of a number of competencies; a list of competency builders is provided for each competency. Titles of the 20 units are as follows:…

  17. 3D models of slow motions in the Earth's crust and upper mantle in the source zones of seismically active regions and their comparison with highly accurate observational data: II. Results of numerical calculations

    NASA Astrophysics Data System (ADS)

    Molodenskii, S. M.; Molodenskii, M. S.; Begitova, T. A.

    2016-09-01

    In the first part of the paper, a new method was developed for solving the inverse problem of coseismic and postseismic deformations in the real (imperfectly elastic, radially and horizontally heterogeneous, self-gravitating) Earth with hydrostatic initial stresses from highly accurate modern satellite data. The method is based on the decomposition of the sought parameters in the orthogonalized basis. The method was suggested for estimating the ambiguity of the solution of the inverse problem for coseismic and postseismic deformations. For obtaining this estimate, the orthogonal complement is constructed to the n-dimensional space spanned by the system of functional derivatives of the residuals in the system of n observed and model data on the coseismic and postseismic displacements at a variety of sites on the ground surface with small variations in the models. Below, we present the results of the numerical modeling of the elastic displacements of the ground surface, which were based on calculating Green's functions of the real Earth for the plane dislocation surface and different orientations of the displacement vector as described in part I of the paper. The calculations were conducted for the model of a horizontally homogeneous but radially heterogeneous selfgravitating Earth with hydrostatic initial stresses and the mantle rheology described by the Lomnitz logarithmic creep function according to (M. Molodenskii, 2014). We compare our results with the previous numerical calculations (Okado, 1985; 1992) for the simplest model of a perfectly elastic nongravitating homogeneous Earth. It is shown that with the source depths starting from the first hundreds of kilometers and with magnitudes of about 8.0 and higher, the discrepancies significantly exceed the errors of the observations and should therefore be taken into account. We present the examples of the numerical calculations of the creep function of the crust and upper mantle for the coseismic deformations. We

  18. Active compensation of aperture discontinuities for WFIRST-AFTA: analytical and numerical comparison of propagation methods and preliminary results with a WFIRST-AFTA-like pupil

    NASA Astrophysics Data System (ADS)

    Mazoyer, Johan; Pueyo, Laurent; Norman, Colin; N'Diaye, Mamadou; van der Marel, Roeland P.; Soummer, Rémi

    2016-03-01

    The new frontier in the quest for the highest contrast levels in the focal plane of a coronagraph is now the correction of the large diffraction artifacts introduced at the science camera by apertures of increasing complexity. Indeed, the future generation of space- and ground-based coronagraphic instruments will be mounted on on-axis and/or segmented telescopes; the design of coronagraphic instruments for such observatories is currently a domain undergoing rapid progress. One approach consists of using two sequential deformable mirrors (DMs) to correct for aberrations introduced by secondary mirror structures and segmentation of the primary mirror. The coronagraph for the WFIRST-AFTA mission will be the first of such instruments in space with a two-DM wavefront control system. Regardless of the control algorithm for these multiple DMs, they will have to rely on quick and accurate simulation of the propagation effects introduced by the out-of-pupil surface. In the first part of this paper, we present the analytical description of the different approximations to simulate these propagation effects. In Appendix A, we prove analytically that in the special case of surfaces inducing a converging beam, the Fresnel method yields high fidelity for simulations of these effects. We provide numerical simulations showing this effect. In the second part, we use these tools in the framework of the active compensation of aperture discontinuities (ACAD) technique applied to pupil geometries similar to WFIRST-AFTA. We present these simulations in the context of the optical layout of the high-contrast imager for complex aperture telescopes, which will test ACAD on a optical bench. The results of this analysis show that using the ACAD method, an apodized pupil Lyot coronagraph, and the performance of our current DMs, we are able to obtain, in numerical simulations, a dark hole with a WFIRST-AFTA-like. Our numerical simulation shows that we can obtain contrast better than 2×10-9 in

  19. Comparison of interference-free numerical results with sample experimental data for the AEDC wall-interference model at transonic and subsonic flow conditions

    NASA Technical Reports Server (NTRS)

    Newman, P. A.; Allison, D. O.

    1974-01-01

    Numerical results obtained from two computer programs recently developed with NASA support and now available for use by others are compared with some sample experimental data taken on a rectangular-wing configuration in the AEDC 16-Foot Transonic Tunnel at transonic and subsonic flow conditions. This data was used in an AEDC investigation as reference data to deduce the tunnel-wall interference effects for corresponding data taken in a smaller tunnel. The comparisons were originally intended to see how well a current state-of-the-art transonic flow calculation for a simple 3-D wing agreed with data which was felt by experimentalists to be relatively interference-free. As a result of the discrepancies between the experimental data and computational results at the quoted angle of attack, it was then deduced from an approximate stress analysis that the sting had deflected appreciably. Thus, the comparisons themselves are not so meaningful, since the calculations must be repeated at the proper angle of attack. Of more importance, however, is a demonstration of the utility of currently available computational tools in the analysis and correlation of transonic experimental data.

  20. The effect of particles size distribution on aesthetic and thermal performances of polydisperse TiO2 pigmented coatings: Comparison between numerical and experimental results

    NASA Astrophysics Data System (ADS)

    Baneshi, Mehdi; Gonome, Hiroki; Komiya, Atsuki; Maruyama, Shigenao

    2012-05-01

    A new approach in designing pigmented coatings considering both visual and thermal concerns was introduced by authors in previous works. The objective was to design a pigmented coating with dark appearance which can stay cool while exposed to sunlight. This behavior can be achieved by coating a typical black substrate with a pigmented coating with controlled size and concentration of particles and coating thickness. In present work, the spectral behaviour of polydisperse TiO2 pigmented coatings was studied. The radiative properties of polydisperse TiO2 powders were evaluated and the radiative transfer in the pigmented coating was modelled using the radiation element method by ray emission model (REM2). The effects of particles size distribution on spectral reflectivity, optimization parameter, and color coordinates were discussed. The results of numerical calculation were validated by experimental reflectivity measurements of several TiO2 pigmented coating samples made from two different TiO2 powders with different size distributions of particles. The results show that our model can reasonably predict the spectral reflectivity of TiO2 pigmented coating samples. Moreover, the results of optimized monodisperse TiO2 pigmented coatings were again validated.

  1. Strong coupling results in the AdS 5 /CF T 4 correspondence from the numerical solution of the quantum spectral curve

    NASA Astrophysics Data System (ADS)

    Hegedűs, Árpád; Konczer, József

    2016-08-01

    In this paper, we solved numerically the Quantum Spectral Curve (QSC) equations corresponding to some twist-2 single trace operators with even spin from the sl(2) sector of AdS 5 /CFT 4 correspondence. We describe all technical details of the numerical method which are necessary to implement it in C++ language.

  2. Use of borehole radar reflection logging to monitor steam-enhanced remediation in fractured limestone-results of numerical modelling and a field experiment

    USGS Publications Warehouse

    Gregoire, C.; Joesten, P.K.; Lane, J.W.

    2006-01-01

    Ground penetrating radar is an efficient geophysical method for the detection and location of fractures and fracture zones in electrically resistive rocks. In this study, the use of down-hole (borehole) radar reflection logs to monitor the injection of steam in fractured rocks was tested as part of a field-scale, steam-enhanced remediation pilot study conducted at a fractured limestone quarry contaminated with chlorinated hydrocarbons at the former Loring Air Force Base, Limestone, Maine, USA. In support of the pilot study, borehole radar reflection logs were collected three times (before, during, and near the end of steam injection) using broadband 100 MHz electric dipole antennas. Numerical modelling was performed to predict the effect of heating on radar-frequency electromagnetic (EM) wave velocity, attenuation, and fracture reflectivity. The modelling results indicate that EM wave velocity and attenuation change substantially if heating increases the electrical conductivity of the limestone matrix. Furthermore, the net effect of heat-induced variations in fracture-fluid dielectric properties on average medium velocity is insignificant because the expected total fracture porosity is low. In contrast, changes in fracture fluid electrical conductivity can have a significant effect on EM wave attenuation and fracture reflectivity. Total replacement of water by steam in a fracture decreases fracture reflectivity of a factor of 10 and induces a change in reflected wave polarity. Based on the numerical modelling results, a reflection amplitude analysis method was developed to delineate fractures where steam has displaced water. Radar reflection logs collected during the three acquisition periods were analysed in the frequency domain to determine if steam had replaced water in the fractures (after normalizing the logs to compensate for differences in antenna performance between logging runs). Analysis of the radar reflection logs from a borehole where the temperature

  3. Flow Matching Results of an MHD Energy Bypass System on a Supersonic Turbojet Engine Using the Numerical Propulsion System Simulation (NPSS) Environment

    NASA Technical Reports Server (NTRS)

    Benyo, Theresa L.

    2011-01-01

    Flow matching has been successfully achieved for an MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment helped perform a thermodynamic cycle analysis to properly match the flows from an inlet employing a MHD energy bypass system (consisting of an MHD generator and MHD accelerator) on a supersonic turbojet engine. Working with various operating conditions (such as the applied magnetic field, MHD generator length and flow conductivity), interfacing studies were conducted between the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis. This paper further describes the analysis of a supersonic turbojet engine with an MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to a range of 0 to 7.0 Mach with specific net thrust range of 740 N-s/kg (at ambient Mach = 3.25) to 70 N-s/kg (at ambient Mach = 7). These results were achieved with an applied magnetic field of 2.5 Tesla and conductivity levels in a range from 2 mhos/m (ambient Mach = 7) to 5.5 mhos/m (ambient Mach = 3.5) for an MHD generator length of 3 m.

  4. Micro-scale finite element modeling of ultrasound propagation in aluminum trabecular bone-mimicking phantoms: A comparison between numerical simulation and experimental results.

    PubMed

    Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S

    2016-05-01

    The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures.

  5. Initial Flow Matching Results of MHD Energy Bypass on a Supersonic Turbojet Engine Using the Numerical Propulsion System Simulation (NPSS) Environment

    NASA Technical Reports Server (NTRS)

    Benyo, Theresa L.

    2010-01-01

    Preliminary flow matching has been demonstrated for a MHD energy bypass system on a supersonic turbojet engine. The Numerical Propulsion System Simulation (NPSS) environment was used to perform a thermodynamic cycle analysis to properly match the flows from an inlet to a MHD generator and from the exit of a supersonic turbojet to a MHD accelerator. Working with various operating conditions such as the enthalpy extraction ratio and isentropic efficiency of the MHD generator and MHD accelerator, interfacing studies were conducted between the pre-ionizers, the MHD generator, the turbojet engine, and the MHD accelerator. This paper briefly describes the NPSS environment used in this analysis and describes the NPSS analysis of a supersonic turbojet engine with a MHD generator/accelerator energy bypass system. Results from this study have shown that using MHD energy bypass in the flow path of a supersonic turbojet engine increases the useful Mach number operating range from 0 to 3.0 Mach (not using MHD) to an explored and desired range of 0 to 7.0 Mach.

  6. Micro-scale finite element modeling of ultrasound propagation in aluminum trabecular bone-mimicking phantoms: A comparison between numerical simulation and experimental results.

    PubMed

    Vafaeian, B; Le, L H; Tran, T N H T; El-Rich, M; El-Bialy, T; Adeeb, S

    2016-05-01

    The present study investigated the accuracy of micro-scale finite element modeling for simulating broadband ultrasound propagation in water-saturated trabecular bone-mimicking phantoms. To this end, five commercially manufactured aluminum foam samples as trabecular bone-mimicking phantoms were utilized for ultrasonic immersion through-transmission experiments. Based on micro-computed tomography images of the same physical samples, three-dimensional high-resolution computational samples were generated to be implemented in the micro-scale finite element models. The finite element models employed the standard Galerkin finite element method (FEM) in time domain to simulate the ultrasonic experiments. The numerical simulations did not include energy dissipative mechanisms of ultrasonic attenuation; however, they expectedly simulated reflection, refraction, scattering, and wave mode conversion. The accuracy of the finite element simulations were evaluated by comparing the simulated ultrasonic attenuation and velocity with the experimental data. The maximum and the average relative errors between the experimental and simulated attenuation coefficients in the frequency range of 0.6-1.4 MHz were 17% and 6% respectively. Moreover, the simulations closely predicted the time-of-flight based velocities and the phase velocities of ultrasound with maximum relative errors of 20 m/s and 11 m/s respectively. The results of this study strongly suggest that micro-scale finite element modeling can effectively simulate broadband ultrasound propagation in water-saturated trabecular bone-mimicking structures. PMID:26894840

  7. The role of indigenous traditional counting systems in children's development of numerical cognition: results from a study in Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Matang, Rex A. S.; Owens, Kay

    2014-09-01

    The Government of Papua New Guinea undertook a significant step in developing curriculum reform policy that promoted the use of Indigenous knowledge systems in teaching formal school subjects in any of the country's 800-plus Indigenous languages. The implementation of the Elementary Cultural Mathematics Syllabus is in line with the above curriculum emphasis. Given the aims of the reform, the research reported here investigated the influence of children's own mother tongue (Tok Ples) and traditional counting systems on their development of early number knowledge formally taught in schools. The study involved 272 school children from 22 elementary schools in four provinces. Each child participated in a task-based assessment interview focusing on eight task groups relating to early number knowledge. The results obtained indicate that, on average, children learning their traditional counting systems in their own language spent shorter time and made fewer mistakes in solving each task compared to those taught without Tok Ples (using English and/or the lingua franca, Tok Pisin). Possible reasons accounting for these differences are also discussed.

  8. Statistical methods applied to the study of opinion formation models: a brief overview and results of a numerical study of a model based on the social impact theory

    NASA Astrophysics Data System (ADS)

    Bordogna, Clelia María; Albano, Ezequiel V.

    2007-02-01

    The aim of this paper is twofold. On the one hand we present a brief overview on the application of statistical physics methods to the modelling of social phenomena focusing our attention on models for opinion formation. On the other hand, we discuss and present original results of a model for opinion formation based on the social impact theory developed by Latané. The presented model accounts for the interaction among the members of a social group under the competitive influence of a strong leader and the mass media, both supporting two different states of opinion. Extensive simulations of the model are presented, showing that they led to the observation of a rich scenery of complex behaviour including, among others, critical behaviour and phase transitions between a state of opinion dominated by the leader and another dominated by the mass media. The occurrence of interesting finite-size effects reveals that, in small communities, the opinion of the leader may prevail over that of the mass media. This observation is relevant for the understanding of social phenomena involving a finite number of individuals, in contrast to actual physical phase transitions that take place in the thermodynamic limit. Finally, we give a brief outlook of open questions and lines for future work.

  9. Numerical simulation of precipitation formation in the case orographically induced convective cloud: Comparison of the results of bin and bulk microphysical schemes

    NASA Astrophysics Data System (ADS)

    Sarkadi, N.; Geresdi, I.; Thompson, G.

    2016-11-01

    In this study, results of bulk and bin microphysical schemes are compared in the case of idealized simulations of pre-frontal orographic clouds with enhanced embedded convection. The description graupel formation by intensive riming of snowflakes was improved compared to prior versions of each scheme. Two methods of graupel melting coincident with collisions with water drops were considered: (1) all simulated melting and collected water drops increase the amount of melted water on the surface of graupel particles with no shedding permitted; (2) also no shedding permitted due to melting, but the collision with the water drops can induce shedding from the surface of the graupel particles. The results of the numerical experiments show: (i) The bin schemes generate graupel particles more efficiently by riming than the bulk scheme does; the intense riming of snowflakes was the most dominant process for the graupel formation. (ii) The collision-induced shedding significantly affects the evolution of the size distribution of graupel particles and water drops below the melting level. (iii) The three microphysical schemes gave similar values for the domain integrated surface precipitation, but the patterns reveal meaningful differences. (iv) Sensitivity tests using the bulk scheme show that the depth of the melting layer is sensitive to the description of the terminal velocity of the melting snow. (v) Comparisons against Convair-580 flight measurements suggest that the bin schemes simulate well the evolution of the pristine ice particles and liquid drops, while some inaccuracy can occur in the description of snowflakes riming. (vi) The bin scheme with collision-induced shedding reproduced well the quantitative characteristics of the observed bright band.

  10. Topography and tectonics of the central New Madrid seismic zone: Results of numerical experiements using a three-dimensional boundary element program

    NASA Technical Reports Server (NTRS)

    Gomberg, Joan; Ellis, Michael

    1994-01-01

    We present results of a series of numerical experiments designed to test hypothetical mechanisms that derive deformation in the New Madrid seismic zone. Experiments are constrained by subtle topography and the distribution of seismicity in the region. We use a new boundary element algorithm that permits calcuation of the three-dimensional deformation field. Surface displacement fields are calculated for the New Madrid zone under both far-field (plate tectonics scale) and locally derived driving strains. Results demonstrate that surface displacement fields cannot distinguish between either a far-field simple or pure shear strain field or one that involves a deep shear zone beneath the upper crustal faults. Thus, neither geomorphic nor geodetic studies alone are expected to reveal the ultimate driving mechanism behind the present-day deformation. We have also tested hypotheses about strain accommodation within the New Madrid contractional step-over by including linking faults, two southwest dipping and one vertical, recently inferred from microearthquake data. Only those models with step-over faults are able to predict the observed topography. Surface displacement fields for long-term, relaxed deformation predict the distribution of uplift and subsidence in the contractional step-over remarkably well. Generation of these displacement fields appear to require slip on both the two northeast trending vertical faults and the two dipping faults in the step-over region, with very minor displacements occurring during the interseismic period when the northeast trending vertical faults are locked. These models suggest that the gently dippling central step-over fault is a reverse fault and that the steeper fault, extending to the southeast of the step-over, acts as a normal fault over the long term.

  11. Dynamics of plume-triple junction interaction: Results from a series of three-dimensional numerical models and implications for the formation of oceanic plateaus

    NASA Astrophysics Data System (ADS)

    Dordevic, Mladen; Georgen, Jennifer

    2016-03-01

    Mantle plumes rising in the vicinity of mid-ocean ridges often generate anomalies in melt production and seafloor depth. This study investigates the dynamical interactions between a mantle plume and a ridge-ridge-ridge triple junction, using a parameter space approach and a suite of steady state, three-dimensional finite element numerical models. The top domain boundary is composed of three diverging plates, with each assigned half-spreading rates with respect to a fixed triple junction point. The bottom boundary is kept at a constant temperature of 1350°C except where a two-dimensional, Gaussian-shaped thermal anomaly simulating a plume is imposed. Models vary plume diameter, plume location, the viscosity contrast between plume and ambient mantle material, and the use of dehydration rheology in calculating viscosity. Importantly, the model results quantify how plume-related anomalies in mantle temperature pattern, seafloor depth, and crustal thickness depend on the specific set of parameters. To provide an example, one way of assessing the effect of conduit position is to calculate normalized area, defined to be the spatial dispersion of a given plume at specific depth (here selected to be 50 km) divided by the area occupied by the same plume when it is located under the triple junction. For one particular case modeled where the plume is centered in an intraplate position 100 km from the triple junction, normalized area is just 55%. Overall, these models provide a framework for better understanding plateau formation at triple junctions in the natural setting and a tool for constraining subsurface geodynamical processes and plume properties.

  12. Using High-Fidelity Analysis Methods and Experimental Results to Account for the Effects of Imperfections on the Buckling Response of Composite Shell Structures

    NASA Technical Reports Server (NTRS)

    Starnes, James H., Jr.; Hilburger, Mark W.

    2003-01-01

    The results of an experimental and analytical study of the effects of initial imperfections on the buckling response of unstiffened thin-walled compression-loaded graphite-epoxy cylindrical shells are presented. The analytical results include the effects of traditional and nontraditional initial imperfections and uncertainties in the values of selected shell parameters on the buckling loads of the shells. The nonlinear structural analysis results correlate very well with the experimental results. The high-fidelity nonlinear analysis procedure used to generate the analytical results can also be used to form the basis of a new shell design procedure that could reduce the traditional dependence on empirical results in the shell design process. KEYWORDS: high-fidelity nonlinear structural analysis, composite shells, shell stability, initial imperfections

  13. Numerical Modeling of LCROSS experiment

    NASA Astrophysics Data System (ADS)

    Sultanov, V. G.; Kim, V. V.; Matveichev, A. V.; Zhukov, B. G.; Lomonosov, I. V.

    2009-06-01

    The mission objectives of the Lunar Crater Observation and Sensing Satellite (LCROSS) include confirming the presence or absence of water ice in a permanently shadowed crater in the Moon's polar regions. In this research we present results of numerical modeling of forthcoming LCROSS experiment. The parallel FPIC3D gas dynamic code with implemented realistic equations of state (EOS) and constitutive relations [1] was used. New wide--range EOS for lunar ground was developed. We carried out calculations of impact of model body on the lunar surface at different angels. Situations of impact on dry and water ice--contained lunar ground were also taken into account. Modeling results are given for crater's shape and size along with amount of ejecta. [4pt] [1] V.E. Fortov, V.V. Kim, I.V. Lomonosov, A.V. Matveichev, A.V. Ostrik. Numerical modeling of hypervelocity impacts, Intern J Impact Engeneering, 33, 244-253 (2006)

  14. Life in the Pressure Cooker--School League Tables and English and Mathematics Teachers' Responses to Accountability in a Results-Driven Era

    ERIC Educational Resources Information Center

    Perryman, Jane; Ball, Stephen; Maguire, Meg; Braun, Annette

    2011-01-01

    This paper is based on case-study research in four English secondary schools. It explores the pressure placed on English and mathematics departments because of their results being reported in annual performance tables. It examines how English and maths departments enact policies of achievement, the additional power and extra resources the pressure…

  15. Transport and mixing dynamics from explosions in debris-filled volcanic conduits: Numerical results and implications for maar-diatreme volcanoes

    NASA Astrophysics Data System (ADS)

    Sweeney, Matthew R.; Valentine, Greg A.

    2015-09-01

    Most volcanoes experience some degree of phreatomagmatism during their lifetime. However, the current understanding of such processes remains limited relative to their magmatic counterparts. Maar-diatremes are a common volcano type that form primarily from phreatomagmatic explosions and are an ideal candidate to further our knowledge of deposits and processes resulting from explosive magma-water interaction due to their abundance as well as their variable levels of field exposure, which allows for detailed mapping and componentry. Two conceptual models of maar-diatreme volcanoes explain the growth and evolution of the crater (maar) and subsurface vent (diatreme) through repeated explosions caused by the interaction of magma and groundwater. One model predicts progressively deepening explosions as water is used up by phreatomagmatic explosions while the other allows for explosions at any level in the diatreme, provided adequate hydrologic conditions are present. In the former, deep-seated lithics in the diatreme are directly ejected and their presence in tephra rings is often taken as a proxy for the depth at which that particular explosion occurred. In the latter, deep-seated lithics are incrementally transported toward the surface via upward directed debris jets. Here we present a novel application of multiphase numerical modeling to assess the controls on length scales of debris jets and their role in upward transport of intra-diatreme material to determine the validity of the two models. The volume of gas generated during a phreatomagmatic explosion is a first order control on the vertical distance a debris jet travels. Unless extremely large amounts of magma and water are involved, it is unlikely that most explosions deeper than ∼ 250 m breach the surface. Other factors such as pressure and temperature have lesser effects on the length scales assuming they are within realistic ranges. Redistribution of material within a diatreme is primarily driven by

  16. 3D Air Quality and the Clean Air Interstate Rule: Lagrangian Sampling of CMAQ Model Results to Aid Regional Accountability Metrics

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Szykman, Jim; Pierce, Robert B.; Gilliland, A. B.; Engel-Cox, Jill; Weber, Stephanie; Kittaka, Chieko; Al-Saadi, Jassim A.; Scheffe, Rich; Dimmick, Fred; Tikvart, Joe

    2008-01-01

    The Clean Air Interstate Rule (CAIR) is expected to reduce transport of air pollutants (e.g. fine sulfate particles) in nonattainment areas in the Eastern United States. CAIR highlights the need for an integrated air quality observational and modeling system to understand sulfate as it moves in multiple dimensions, both spatially and temporally. Here, we demonstrate how results from an air quality model can be combined with a 3d monitoring network to provide decision makers with a tool to help quantify the impact of CAIR reductions in SO2 emissions on regional transport contributions to sulfate concentrations at surface monitors in the Baltimore, MD area, and help improve decision making for strategic implementation plans (SIPs). We sample results from the Community Multiscale Air Quality (CMAQ) model using ensemble back trajectories computed with the NASA Langley Research Center trajectory model to provide Lagrangian time series and vertical profile information, that can be compared with NASA satellite (MODIS), EPA surface, and lidar measurements. Results are used to assess the regional transport contribution to surface SO4 measurements in the Baltimore MSA, and to characterize the dominant source regions for low, medium, and high SO4 episodes.

  17. Numerical Development

    ERIC Educational Resources Information Center

    Siegler, Robert S.; Braithwaite, David W.

    2016-01-01

    In this review, we attempt to integrate two crucial aspects of numerical development: learning the magnitudes of individual numbers and learning arithmetic. Numerical magnitude development involves gaining increasingly precise knowledge of increasing ranges and types of numbers: from non-symbolic to small symbolic numbers, from smaller to larger…

  18. Experimental and Numerical Investigation of Forming and Springback Behavior and the Resulting Effects on Industrial Application on a Structural Part in Mass Production

    SciTech Connect

    Prexl, A.; Hoffmann, H.; Golle, M.; Kudrass, S.; Wahl, M.

    2011-01-17

    Springback prediction and compensation is nowadays a widely recommended discipline in finite element modeling. Many researches have shown an improvement of the accuracy in prediction of springback using advanced modeling techniques, e.g. by including the Bauschinger effect. In this work different models were investigated in the commercial simulation program AutoForm for a large series production part, manufactured from the dual phase steel HC340XD. The work shows the differences between numerical drawbead models and geometrically modeled drawbeads. Furthermore, a sensitivity analysis was made for a reduced kinematic hardening model, implemented in the finite element program AutoForm.

  19. Numerical Asymptotic Solutions Of Differential Equations

    NASA Technical Reports Server (NTRS)

    Thurston, Gaylen A.

    1992-01-01

    Numerical algorithms derived and compared with classical analytical methods. In method, expansions replaced with integrals evaluated numerically. Resulting numerical solutions retain linear independence, main advantage of asymptotic solutions.

  20. Numerical orbit generators of artificial earth satellites

    NASA Astrophysics Data System (ADS)

    Kugar, H. K.; Dasilva, W. C. C.

    1984-04-01

    A numerical orbit integrator containing updatings and improvements relative to the previous ones that are being utilized by the Departmento de Mecanica Espacial e Controle (DMC), of INPE, besides incorporating newer modellings resulting from the skill acquired along the time is presented. Flexibility and modularity were taken into account in order to allow future extensions and modifications. Characteristics of numerical accuracy, processing quickness, memory saving as well as utilization aspects were also considered. User's handbook, whole program listing and qualitative analysis of accuracy, processing time and orbit perturbation effects were included as well.

  1. Three dimensional dynamics of baroclinic tides at the Celtic Sea shelf break: on the results of in-situ observations and numerical modelling

    NASA Astrophysics Data System (ADS)

    Vlasenko, Vasiliy; Stashchuk, Nataliya; Inall, Mark; Hopkins, Jo

    2015-04-01

    The three-dimensional dynamics of baroclinic tides in the shelf-slope area of the Celtic Sea were investigated numerically and using observational data collected on the 376-th cruise of the R/V ``Discovery'' in June 2012. The time series recorded at a shelf-break mooring showed that semi-diurnal internal waves were accompanied by packets of internal solitary waves with maximum amplitudes up to 105 m, the largest internal waves ever recorded in the Celtic Sea. The observed baroclinic wave fields were replicated numerically using the Massachusetts Institute of Technology general circulation model. A fine-resolution grid with 115 m horizontal and 10 m vertical steps allowed the identification of two classes of short-scale internal waves. The first class was generated over headlands and resembles spiral-type internal waves that are typical for isolated underwater banks. The second class, generated within an area of isolated canyons, revealed properties of quasi-plane internal wave packets. The observed in-situ intensification of tidal bottom currents at the shelf break mooring is explained in terms of a tidal beam that was formed over supercritical bottom topography.

  2. Multiple scattering in the high-frequency limit with second-order shadowing function from 2D anisotropic rough dielectric surfaces: II. Comparison with numerical results

    NASA Astrophysics Data System (ADS)

    Bourlier, C.; Berginc, G.

    2004-07-01

    This second part presents illustrative examples of the model developed in the companion paper, which is based on the first- and second-order optics approximation. The surface is assumed to be Gaussian and the correlation height is chosen as anisotropic Gaussian. The incoherent scattering coefficient is computed for a height rms range from 0.5lgr to 1lgr (where lgr is the electromagnetic wavelength), for a slope rms range from 0.5 to 1 and for an incidence angle range from 0 to 70°. In addition, simulations are presented for an anisotropic Gaussian surface and when the receiver is not located in the plane of incidence. For a metallic and dielectric isotropic Gaussian surfaces, the cross- and co-polarizations are also compared with a numerical approach obtained from the forward-backward method with a novel spectral acceleration algorithm developed by Torrungrueng and Johnson (2001, JOSA A 18).

  3. Numerical impact simulation of gradually increased kinetic energy transfer has the potential to break up folded protein structures resulting in cytotoxic brain tissue edema.

    PubMed

    von Holst, Hans; Li, Xiaogai

    2013-07-01

    Although the consequences of traumatic brain injury (TBI) and its treatment have been improved, there is still a substantial lack of understanding the mechanisms. Numerical simulation of the impact can throw further lights on site and mechanism of action. A finite element model of the human head and brain tissue was used to simulate TBI. The consequences of gradually increased kinetic energy transfer was analyzed by evaluating the impact intracranial pressure (ICP), strain level, and their potential influences on binding forces in folded protein structures. The gradually increased kinetic energy was found to have the potential to break apart bonds of Van der Waals in all impacts and hydrogen bonds at simulated impacts from 6 m/s and higher, thereby superseding the energy in folded protein structures. Further, impacts below 6 m/s showed none or very slight increase in impact ICP and strain levels, whereas impacts of 6 m/s or higher showed a gradual increase of the impact ICP and strain levels reaching over 1000 KPa and over 30%, respectively. The present simulation study shows that the free kinetic energy transfer, impact ICP, and strain levels all have the potential to initiate cytotoxic brain tissue edema by unfolding protein structures. The definition of mild, moderate, and severe TBI should thus be looked upon as the same condition and separated only by a gradual severity of impact.

  4. Improved resolution and reduced clutter in ultra-wideband microwave imaging using cross-correlated back projection: experimental and numerical results.

    PubMed

    Jacobsen, S; Birkelund, Y

    2010-01-01

    Microwave breast cancer detection is based on the dielectric contrast between healthy and malignant tissue. This radar-based imaging method involves illumination of the breast with an ultra-wideband pulse. Detection of tumors within the breast is achieved by some selected focusing technique. Image formation algorithms are tailored to enhance tumor responses and reduce early-time and late-time clutter associated with skin reflections and heterogeneity of breast tissue. In this contribution, we evaluate the performance of the so-called cross-correlated back projection imaging scheme by using a scanning system in phantom experiments. Supplementary numerical modeling based on commercial software is also presented. The phantom is synthetically scanned with a broadband elliptical antenna in a mono-static configuration. The respective signals are pre-processed by a data-adaptive RLS algorithm in order to remove artifacts caused by antenna reverberations and signal clutter. Successful detection of a 7 mm diameter cylindrical tumor immersed in a low permittivity medium was achieved in all cases. Selecting the widely used delay-and-sum (DAS) beamforming algorithm as a benchmark, we show that correlation based imaging methods improve the signal-to-clutter ratio by at least 10 dB and improves spatial resolution through a reduction of the imaged peak full-width half maximum (FWHM) of about 40-50%.

  5. Professional Capital as Accountability

    ERIC Educational Resources Information Center

    Fullan, Michael; Rincón-Gallardo, Santiago; Hargreaves, Andy

    2015-01-01

    This paper seeks to clarify and spells out the responsibilities of policy makers to create the conditions for an effective accountability system that produces substantial improvements in student learning, strengthens the teaching profession, and provides transparency of results to the public. The authors point out that U.S. policy makers will need…

  6. Numerical Analysis Using WRF-SBM for the Cloud Microphysical Structures in the C3VP Field Campaign: Impacts of Supercooled Droplets and Resultant Riming on Snow Microphysics

    NASA Technical Reports Server (NTRS)

    Iguchi, Takamichi; Matsui, Toshihisa; Shi, Jainn J.; Tao, Wei-Kuo; Khain, Alexander P.; Hao, Arthur; Cifelli, Robert; Heymsfield, Andrew; Tokay, Ali

    2012-01-01

    Two distinct snowfall events are observed over the region near the Great Lakes during 19-23 January 2007 under the intensive measurement campaign of the Canadian CloudSat/CALIPSO validation project (C3VP). These events are numerically investigated using the Weather Research and Forecasting model coupled with a spectral bin microphysics (WRF-SBM) scheme that allows a smooth calculation of riming process by predicting the rimed mass fraction on snow aggregates. The fundamental structures of the observed two snowfall systems are distinctly characterized by a localized intense lake-effect snowstorm in one case and a widely distributed moderate snowfall by the synoptic-scale system in another case. Furthermore, the observed microphysical structures are distinguished by differences in bulk density of solid-phase particles, which are probably linked to the presence or absence of supercooled droplets. The WRF-SBM coupled with Goddard Satellite Data Simulator Unit (G-SDSU) has successfully simulated these distinctive structures in the three-dimensional weather prediction run with a horizontal resolution of 1 km. In particular, riming on snow aggregates by supercooled droplets is considered to be of importance in reproducing the specialized microphysical structures in the case studies. Additional sensitivity tests for the lake-effect snowstorm case are conducted utilizing different planetary boundary layer (PBL) models or the same SBM but without the riming process. The PBL process has a large impact on determining the cloud microphysical structure of the lake-effect snowstorm as well as the surface precipitation pattern, whereas the riming process has little influence on the surface precipitation because of the small height of the system.

  7. Numerical Integration

    ERIC Educational Resources Information Center

    Sozio, Gerry

    2009-01-01

    Senior secondary students cover numerical integration techniques in their mathematics courses. In particular, students would be familiar with the "midpoint rule," the elementary "trapezoidal rule" and "Simpson's rule." This article derives these techniques by methods which secondary students may not be familiar with and an approach that…

  8. Numerical Models of Broad Bandwidth Nanosecond Optical Parametric Oscillators

    SciTech Connect

    Bowers, M.S.; Gehr, R.J.; Smith, A.V.

    1998-10-14

    We describe results from three new methods of numerically modeling broad-bandwidth, nanosecond OPO's in the plane-wave approximate ion. They account for differences in group velocities among the three mixing waves, and also include a qutt~ttun noise model.

  9. Effect of the thickness variation and initial imperfection on buckling of composite cylindrical shells: Asymptotic analysis and numerical results by BOSOR4 and PANDA2

    NASA Technical Reports Server (NTRS)

    Li, Yi-Wei; Elishakoff, Isaac; Starnes, James H., Jr.; Bushnell, David

    1998-01-01

    This study is an extension of a previous investigation of the combined effect of axisymmetric thickness variation and axisymmetric initial geometric imperfection on buckling of isotropic shells under uniform axial compression. Here the anisotropic cylindrical shells are investigated by means of Koiter's energy criterion. An asymptotic formula is derived which can be used to determine the critical buckling load for composite shells with combined initial geometric imperfection and thickness variation. Results are compared with those obtained by the software packages BOSOR4 and PANDA2.

  10. Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 1—experimental results

    NASA Astrophysics Data System (ADS)

    Beniaiche, Ahmed; Ghenaiet, Adel; Facchini, Bruno

    2016-05-01

    The aero-thermal behavior of the flow field inside 30:1 scaled model reproducing an innovative smooth trailing edge of shaped wedge discharge duct with one row of enlarged pedestals have been investigated in order to determine the effect of rotation, inlet velocity and blowing conditions effects, for Re = 20,000 and 40,000 and Ro = 0-0.23. Two configurations are presented: with and without open tip configurations. Thermo-chromic liquid crystals technique is used to ensure a local measurement of the heat transfer coefficient on the blade suction side under stationary and rotation conditions. Results are reported in terms of detailed 2D HTC maps on the suction side surface as well as the averaged Nusselt number inside the pedestal ducts. Two correlations are proposed, for both closed and open tip configurations, based on the Re, Pr, Ro and a new non-dimensional parameter based on the position along the radial distance, to assess a reliable estimation of the averaged Nusselt number at the inter-pedestal region. A good agreement is found between prediction and experimental data with about ±10 to ±12 % of uncertainty, for the simple form correlation, and about ±16 % using a complex form. The obtained results help to predict the flow field visualization and the evaluation of the aero-thermal performance of the studied blade cooling system during the design step.

  11. The Numerical Comparison of Magnetic Susceptibility and Heat Capacity of TMNIN with the Result of a Quantum Monte Carlo Method for the Haldane System

    NASA Astrophysics Data System (ADS)

    Ito, Masakazu; Mito, Masaki; Deguchi, Hiroyuki; Takeda, Kazuyoshi

    1994-03-01

    The measurements of magnetic heat capacity and susceptibility of one-dimensional S=1 antiferromagnet (CH3)4NNi(NO2)3 (TMNIN) have been carried out in order to make comparison with the theoretical results of a quantum Monte Carlo method for the Haldane system. The results for the heat capacity, which show a broad maximum around 10 K, are well reproduced by the theory with the interaction J/k B=-12.0±1.0 K in the temperature range T>0.2\\mid J\\mid S(S+1)/k_B. The low temperature heat capacity exhibits an exponential decay with gap energy Δ/k B=5.3±0.2 K, which gives {\\mitΔ}=0.44\\mid J\\mid , in contrast to the linear dependence on temperature as in the case for half integer spin. The residual magnetic entropy below 0.7 K is estimated to be 0.07% of Nk B ln 3, which denies the possibility of three-dimensional ordering of the spin system at lower temperatures. The observed susceptibility also agrees with the theory with J/k B=-10.9 K and g=2.02 in the whole temperature region, when we take the effect from the finite length of the chains into consideration.

  12. Ground-water modeling of pumping effects near regional ground-water divides and river/aquifer systems - Results and implications of numerical experiments

    USGS Publications Warehouse

    Sheets, Rodney A.; Dumouchelle, Denise H.; Feinstein, Daniel T.

    2005-01-01

    Agreements between United States governors and Canadian territorial premiers establish water-management principles and a framework for protecting Great Lakes waters, including ground water, from diversion and consumptive uses. The issue of ground-water diversions out of the Great Lakes Basin by large-scale pumping near the divides has been raised. Two scenario models, in which regional ground-water flow models represent major aquifers in the Great Lakes region, were used to assess the effect of pumping near ground-water divides. The regional carbonate aquifer model was a generalized model representing northwestern Ohio and northeastern Indiana; the regional sandstone aquifer model used an existing calibrated ground-water flow model for southeastern Wisconsin. Various well locations and pumping rates were examined. Although the two models have different frameworks and boundary conditions, results of the models were similar. There was significant diversion of ground water across ground-water divides due to pumping within 10 miles of the divides. In the regional carbonate aquifer model, the percentage of pumped water crossing the divide ranges from about 20 percent for a well 10 miles from the divide to about 50 percent for a well adjacent to the divide. In the regional sandstone aquifer model, the percentages range from about 30 percent for a well 10 miles from the divide to about 50 percent for a well adjacent to the divide; when pumping on the west side of the divide, within 5 mi of the predevelopment divide, results in at least 10 percent of the water being diverted from the east side of the divide. Two additional scenario models were done to examine the effects of pumping near rivers. Transient models were used to simulate a rapid stage rise in a river during pumping at a well in carbonate and glacial aquifers near the river. Results of water-budget analyses indicate that induced infiltration, captured streamflow, and underflow were important for both glacial and

  13. Comparison of the Structurally Controlled Landslides Numerical Model Results to the M 7.2 2013 Bohol Earthquake Co-seismic Landslides

    NASA Astrophysics Data System (ADS)

    Macario Galang, Jan Albert; Narod Eco, Rodrigo; Mahar Francisco Lagmay, Alfredo

    2015-04-01

    The M 7.2 October 15, 2013 Bohol earthquake is the most destructive earthquake to hit the Philippines since 2012. The epicenter was located in Sagbayan municipality, central Bohol and was generated by a previously unmapped reverse fault called the "Inabanga Fault". Its name, taken after the barangay (village) where the fault is best exposed and was first seen. The earthquake resulted in 209 fatalities and over 57 billion USD worth of damages. The earthquake generated co-seismic landslides most of which were related to fault structures. Unlike rainfall induced landslides, the trigger for co-seismic landslides happen without warning. Preparedness against this type of landslide therefore, relies heavily on the identification of fracture-related unstable slopes. To mitigate the impacts of co-seismic landslide hazards, morpho-structural orientations or discontinuity sets were mapped in the field with the aid of a 2012 IFSAR Digital Terrain Model (DTM) with 5-meter pixel resolution and < 0.5 meter vertical accuracy. Coltop 3D software was then used to identify similar structures including measurement of their dip and dip directions. The chosen discontinuity sets were then keyed into Matterocking software to identify potential rock slide zones due to planar or wedged discontinuities. After identifying the structurally-controlled unstable slopes, the rock mass propagation extent of the possible rock slides was simulated using Conefall. The results were compared to a post-earthquake landslide inventory of 456 landslides. Out the total number of landslides identified from post-earthquake high-resolution imagery, 366 or 80% intersect the structural-controlled hazard areas of Bohol. The results show the potential of this method to identify co-seismic landslide hazard areas for disaster mitigation. Along with computer methods to simulate shallow landslides, and debris flow paths, located structurally-controlled unstable zones can be used to mark unsafe areas for settlement. The

  14. First-Person Accounts.

    ERIC Educational Resources Information Center

    Gribs, H.; And Others

    1995-01-01

    Personal accounts describe the lives of 2 individuals with deaf-blindness, one an 87-year-old woman who was deaf from birth and became totally blind over a 50-year period and the other of a woman who became deaf-blind as a result of a fever at the age of 7. Managing activities of daily life and experiencing sensory hallucinations are among topics…

  15. Numerical simulation of freeway traffic flow

    SciTech Connect

    Liu, G.; Lyrintzis, A.S.; Michalopoulos, P.G.

    1997-11-01

    A new high-order continuum model is presented in this paper. This high-order model exhibits smooth solutions rather than discontinuities, is able to describe the amplification of small disturbances on heavy traffic, and allows fluctuations of speed around the equilibrium values. Furthermore, unlike some earlier high-order models, it does not result in negative speeds at the tail of congested regions and disturbance propagation speeds greater than the flow speed. The model takes into account the relaxation time as a function of density and, in the equilibrium limit, it is consistent with the simple continuum model. A Riemann-problem-based numerical method is proposed for the solution of the new high-order model. Modeling of interrupted flow behavior such as merging, diverging, and weaving is also investigated. Based on the new high order model, the proposed numerical method and the modeling of interrupted flow, a versatile code is developed for the numerical simulation of freeway traffic flow that includes several freeway geometries. The authors compare the high-order model with the simple continuum model and the proposed numerical method with the Lax method based on 30-s and 5-min field data. The model is tested in interrupted flow situations (e.g., pipeline, merging, diverging, and weaving areas). A comparison of numerical results with limited field data shows that the high-order model performs better than the simple continuum model and describes better than a previously proposed method.

  16. MATERIAL CONTROL ACCOUNTING INMM

    SciTech Connect

    Hasty, T.

    2009-06-14

    Since 1996, the Mining and Chemical Combine (MCC - formerly known as K-26), and the United States Department of Energy (DOE) have been cooperating under the cooperative Nuclear Material Protection, Control and Accounting (MPC&A) Program between the Russian Federation and the U.S. Governments. Since MCC continues to operate a reactor for steam and electricity production for the site and city of Zheleznogorsk which results in production of the weapons grade plutonium, one of the goals of the MPC&A program is to support implementation of an expanded comprehensive nuclear material control and accounting (MC&A) program. To date MCC has completed upgrades identified in the initial gap analysis and documented in the site MC&A Plan and is implementing additional upgrades identified during an update to the gap analysis. The scope of these upgrades includes implementation of MCC organization structure relating to MC&A, establishing material balance area structure for special nuclear materials (SNM) storage and bulk processing areas, and material control functions including SNM portal monitors at target locations. Material accounting function upgrades include enhancements in the conduct of physical inventories, limit of error inventory difference procedure enhancements, implementation of basic computerized accounting system for four SNM storage areas, implementation of measurement equipment for improved accountability reporting, and both new and revised site-level MC&A procedures. This paper will discuss the implementation of MC&A upgrades at MCC based on the requirements established in the comprehensive MC&A plan developed by the Mining and Chemical Combine as part of the MPC&A Program.

  17. Numerical Modeling of Turbulent Combustion

    NASA Technical Reports Server (NTRS)

    Ghoneim, A. F.; Chorin, A. J.; Oppenheim, A. K.

    1983-01-01

    The work in numerical modeling is focused on the use of the random vortex method to treat turbulent flow fields associated with combustion while flame fronts are considered as interfaces between reactants and products, propagating with the flow and at the same time advancing in the direction normal to themselves at a prescribed burning speed. The latter is associated with the generation of specific volume (the flame front acting, in effect, as the locus of volumetric sources) to account for the expansion of the flow field due to the exothermicity of the combustion process. The model was applied to the flow in a channel equipped with a rearward facing step. The results obtained revealed the mechanism of the formation of large scale turbulent structure in the wake of the step, while it showed the flame to stabilize on the outer edges of these eddies.

  18. Multimedia and Management Accounting: Adding Creativity to Accounting.

    ERIC Educational Resources Information Center

    Heisz, Mary A.; Blake, Catherine M.; Andrusyszyn, Mary-Anne

    2000-01-01

    Describes the development of an interactive multimedia accounting module for management accounting at the University of Western Ontario. Discusses results of a study of graduate students that investigated the influence of the module on learning and retention compared to traditional instruction as well as students' perceptions of the module.…

  19. Managing global accounts.

    PubMed

    Yip, George S; Bink, Audrey J M

    2007-09-01

    Global account management--which treats a multinational customer's operations as one integrated account, with coherent terms for pricing, product specifications, and service--has proliferated over the past decade. Yet according to the authors' research, only about a third of the suppliers that have offered GAM are pleased with the results. The unhappy majority may be suffering from confusion about when, how, and to whom to provide it. Yip, the director of research and innovation at Capgemini, and Bink, the head of marketing communications at Uxbridge College, have found that GAM can improve customer satisfaction by 20% or more and can raise both profits and revenues by at least 15% within just a few years of its introduction. They provide guidelines to help companies achieve similar results. The first steps are determining whether your products or services are appropriate for GAM, whether your customers want such a program, whether those customers are crucial to your strategy, and how GAM might affect your competitive advantage. If moving forward makes sense, the authors' exhibit, "A Scorecard for Selecting Global Accounts," can help you target the right customers. The final step is deciding which of three basic forms to offer: coordination GAM (in which national operations remain relatively strong), control GAM (in which the global operation and the national operations are fairly balanced), and separate GAM (in which a new business unit has total responsibility for global accounts). Given the difficulty and expense of providing multiple varieties, the vast majority of companies should initially customize just one---and they should be careful not to start with a choice that is too ambitious for either themselves or their customers to handle.

  20. Managing global accounts.

    PubMed

    Yip, George S; Bink, Audrey J M

    2007-09-01

    Global account management--which treats a multinational customer's operations as one integrated account, with coherent terms for pricing, product specifications, and service--has proliferated over the past decade. Yet according to the authors' research, only about a third of the suppliers that have offered GAM are pleased with the results. The unhappy majority may be suffering from confusion about when, how, and to whom to provide it. Yip, the director of research and innovation at Capgemini, and Bink, the head of marketing communications at Uxbridge College, have found that GAM can improve customer satisfaction by 20% or more and can raise both profits and revenues by at least 15% within just a few years of its introduction. They provide guidelines to help companies achieve similar results. The first steps are determining whether your products or services are appropriate for GAM, whether your customers want such a program, whether those customers are crucial to your strategy, and how GAM might affect your competitive advantage. If moving forward makes sense, the authors' exhibit, "A Scorecard for Selecting Global Accounts," can help you target the right customers. The final step is deciding which of three basic forms to offer: coordination GAM (in which national operations remain relatively strong), control GAM (in which the global operation and the national operations are fairly balanced), and separate GAM (in which a new business unit has total responsibility for global accounts). Given the difficulty and expense of providing multiple varieties, the vast majority of companies should initially customize just one---and they should be careful not to start with a choice that is too ambitious for either themselves or their customers to handle. PMID:17886487

  1. International Accounting and the Accounting Educator.

    ERIC Educational Resources Information Center

    Laribee, Stephen F.

    The American Assembly of Collegiate Schools of Business (AACSB) has been instrumental in internationalizing the accounting curriculum by means of accreditation requirements and standards. Colleges and universities have met the AACSB requirements either by providing separate international accounting courses or by integrating international topics…

  2. School Centered Evidence Based Accountability

    ERIC Educational Resources Information Center

    Milligan, Charles

    2015-01-01

    Achievement scores drive much of the effort in today's accountability system, however, there is much more that occurs in every school, every day. School Centered Evidence Based Accountability can be used from micro to macro giving School Boards and Administration a process for monitoring the results of the entire school operation effectively and…

  3. A Harmonious Accounting Duo?

    ERIC Educational Resources Information Center

    Schapperle, Robert F.; Hardiman, Patrick F.

    1992-01-01

    Accountants have urged "harmonization" of standards between the Governmental Accounting Standards Board and the Financial Accounting Standards Board, recommending similar reporting of like transactions. However, varying display of similar accounting events does not necessarily indicate disharmony. The potential for problems because of differing…

  4. The Symbol Grounding Problem Revisited: A Thorough Evaluation of the ANS Mapping Account and the Proposal of an Alternative Account Based on Symbol–Symbol Associations

    PubMed Central

    Reynvoet, Bert; Sasanguie, Delphine

    2016-01-01

    Recently, a lot of studies in the domain of numerical cognition have been published demonstrating a robust association between numerical symbol processing and individual differences in mathematics achievement. Because numerical symbols are so important for mathematics achievement, many researchers want to provide an answer on the ‘symbol grounding problem,’ i.e., how does a symbol acquires its numerical meaning? The most popular account, the approximate number system (ANS) mapping account, assumes that a symbol acquires its numerical meaning by being mapped on a non-verbal and ANS. Here, we critically evaluate four arguments that are supposed to support this account, i.e., (1) there is an evolutionary system for approximate number processing, (2) non-symbolic and symbolic number processing show the same behavioral effects, (3) non-symbolic and symbolic numbers activate the same brain regions which are also involved in more advanced calculation and (4) non-symbolic comparison is related to the performance on symbolic mathematics achievement tasks. Based on this evaluation, we conclude that all of these arguments and consequently also the mapping account are questionable. Next we explored less popular alternative, where small numerical symbols are initially mapped on a precise representation and then, in combination with increasing knowledge of the counting list result in an independent and exact symbolic system based on order relations between symbols. We evaluate this account by reviewing evidence on order judgment tasks following the same four arguments. Although further research is necessary, the available evidence so far suggests that this symbol–symbol association account should be considered as a worthy alternative of how symbols acquire their meaning. PMID:27790179

  5. Effect of bandwidth and numerical aperture in optical scatterometry

    NASA Astrophysics Data System (ADS)

    Germer, Thomas A.; Patrick, Heather J.

    2010-03-01

    We consider the effects of finite spectral bandwidth and numerical aperture in scatterometry measurements and discuss efficient integration methods based upon Gaussian quadrature in one dimension (for spectral bandwidth averaging) and two dimensions inside a circle (for numerical aperture averaging). Provided the wavelength is not near a Wood's anomaly for the grating, we find that the resulting methods converge very quickly to a level suitable for most measurement applications. In the vicinity of a Wood's anomaly, however, the methods provide rather poor behavior. We also describe a method that can be used to extract the effective spectral bandwidth and numerical aperture for a scatterometry tool. We find that accounting for spectral bandwidth and numerical aperture is necessary to obtain satisfactory results in scatterometry.

  6. Accounting Students' Performance and Personality Types.

    ERIC Educational Resources Information Center

    Nourayi, Mahmoud M.; Cherry, Alan A.

    1993-01-01

    Completion of the Myers Briggs Type Inventory by 103 accounting majors revealed no significant differences among personality types in achievement, except that sensing types perform better in accounting in general. Results seem to belie the suggestion that accounting attracts introverts and that the intuitive type is best suited to accounting in…

  7. Demonstrating marketing accountability.

    PubMed

    Gombeski, William R; Britt, Jason; Taylor, Jan; Riggs, Karen; Wray, Tanya; Adkins, Wanda; Springate, Suzanne

    2008-01-01

    Pressure on health care marketers to demonstrate effectiveness of their strategies and show their contribution to organizational goals is growing. A seven-tiered model based on the concepts of structure (having the right people, systems), process (doing the right things in the right way), and outcomes (results) is discussed. Examples of measures for each tier are provided and the benefits of using the model as a tool for measuring, organizing, tracking, and communicating appropriate information are provided. The model also provides a framework for helping management understand marketing's value and can serve as a vehicle for demonstrating marketing accountability.

  8. Numerical investigation of processes in an optical plasmatron

    NASA Astrophysics Data System (ADS)

    Raizer, Iu. P.; Surzhikov, S. T.

    1984-11-01

    Equations describing a continuous optical discharge maintained by focused CO2-laser radiation in a stream of argon and air are numerically integrated. A one-dimensional model takes into account low subsonic speeds of the gas medium. The process is analyzed for various gas speeds and degrees of laser focusing; and it is found that sufficiently strong focusing yields a stable discharge even in a stationary gas (argon) medium. The results of numerical calculations are compared to previous experiments with atmospheric-pressure argon and the influence of radiant heat transfer on the propagation of the optical discharge is obtained. The results are used to analyze the physical features of plasmatron operation.

  9. The numerical response: rate of increase and food limitation in herbivores and predators.

    PubMed Central

    Bayliss, Peter; Choquenot, David

    2002-01-01

    Two types of numerical response function have evolved since Solomon first introduced the term to generalize features of Lotka-Volterra predator-prey models: (i) the demographic numerical response, which links change in consumer demographic rates to food availability; and (ii) the isocline numerical response, which links consumer abundance per se to food availability. These numerical responses are interchangeable because both recognize negative feedback loops between consumer and food abundance resulting in population regulation. We review how demographic and isocline numerical responses have been used to enhance our understanding of population regulation of kangaroos and possums, and argue that their utility may be increased by explicitly accounting for non-equilibrium dynamics (due to environmental variability and/or biological interactions) and the existence of multiple limiting factors. Interferential numerical response functions may help bridge three major historical dichotomies in population ecology (equilibrium versus non-equilibrium dynamics, extrinsic versus intrinsic regulation and demographic versus isocline numerical responses). PMID:12396515

  10. Negotiations and Accountability

    ERIC Educational Resources Information Center

    Hough, Charles R.

    1971-01-01

    School boards by state statutes are alone accountable for the education of their communities' youth. What's needed, the writer contends, is a rectification of the statutes so that all parties to negotiations are accountable. (Editor)

  11. LMAL Accounting Office 1936

    NASA Technical Reports Server (NTRS)

    1936-01-01

    Accounting Office: The Langley Memorial Aeronautical Laboratory's accounting office, 1936, with photographs of the Wright brothers on the wall. Although the Lab was named after Samuel P. Langley, most of the NACA staff held the Wrights as their heroes.

  12. Managerial Accounting. Study Guide.

    ERIC Educational Resources Information Center

    Plachta, Leonard E.

    This self-instructional study guide is part of the materials for a college-level programmed course in managerial accounting. The study guide is intended for use by students in conjuction with a separate textbook, Horngren's "Accounting for Management Control: An Introduction," and a workbook, Curry's "Student Guide to Accounting for Management…

  13. Accounting & Computing Curriculum Guide.

    ERIC Educational Resources Information Center

    Avani, Nathan T.; And Others

    This curriculum guide consists of materials for use in teaching a competency-based accounting and computing course that is designed to prepare students for employability in the following occupational areas: inventory control clerk, invoice clerk, payroll clerk, traffic clerk, general ledger bookkeeper, accounting clerk, account information clerk,…

  14. Accounting Education in Crisis

    ERIC Educational Resources Information Center

    Turner, Karen F.; Reed, Ronald O.; Greiman, Janel

    2011-01-01

    Almost on a daily basis new accounting rules and laws are put into use, creating information that must be known and learned by the accounting faculty and then introduced to and understood by the accounting student. Even with the 150 hours of education now required for CPA licensure, it is impossible to teach and learn all there is to learn. Over…

  15. The Accounting Capstone Problem

    ERIC Educational Resources Information Center

    Elrod, Henry; Norris, J. T.

    2012-01-01

    Capstone courses in accounting programs bring students experiences integrating across the curriculum (University of Washington, 2005) and offer unique (Sanyal, 2003) and transformative experiences (Sill, Harward, & Cooper, 2009). Students take many accounting courses without preparing complete sets of financial statements. Accountants not only…

  16. Frontiers in Numerical Relativity

    NASA Astrophysics Data System (ADS)

    Evans, Charles R.; Finn, Lee S.; Hobill, David W.

    2011-06-01

    Preface; Participants; Introduction; 1. Supercomputing and numerical relativity: a look at the past, present and future David W. Hobill and Larry L. Smarr; 2. Computational relativity in two and three dimensions Stuart L. Shapiro and Saul A. Teukolsky; 3. Slowly moving maximally charged black holes Robert C. Ferrell and Douglas M. Eardley; 4. Kepler's third law in general relativity Steven Detweiler; 5. Black hole spacetimes: testing numerical relativity David H. Bernstein, David W. Hobill and Larry L. Smarr; 6. Three dimensional initial data of numerical relativity Ken-ichi Oohara and Takashi Nakamura; 7. Initial data for collisions of black holes and other gravitational miscellany James W. York, Jr.; 8. Analytic-numerical matching for gravitational waveform extraction Andrew M. Abrahams; 9. Supernovae, gravitational radiation and the quadrupole formula L. S. Finn; 10. Gravitational radiation from perturbations of stellar core collapse models Edward Seidel and Thomas Moore; 11. General relativistic implicit radiation hydrodynamics in polar sliced space-time Paul J. Schinder; 12. General relativistic radiation hydrodynamics in spherically symmetric spacetimes A. Mezzacappa and R. A. Matzner; 13. Constraint preserving transport for magnetohydrodynamics John F. Hawley and Charles R. Evans; 14. Enforcing the momentum constraints during axisymmetric spacelike simulations Charles R. Evans; 15. Experiences with an adaptive mesh refinement algorithm in numerical relativity Matthew W. Choptuik; 16. The multigrid technique Gregory B. Cook; 17. Finite element methods in numerical relativity P. J. Mann; 18. Pseudo-spectral methods applied to gravitational collapse Silvano Bonazzola and Jean-Alain Marck; 19. Methods in 3D numerical relativity Takashi Nakamura and Ken-ichi Oohara; 20. Nonaxisymmetric rotating gravitational collapse and gravitational radiation Richard F. Stark; 21. Nonaxisymmetric neutron star collisions: initial results using smooth particle hydrodynamics

  17. The Relationship between Self-Perceptions of Accountability by High School Principals and Student Test Scores

    ERIC Educational Resources Information Center

    Koester, Edward L.

    2010-01-01

    The high school principalship has been designated an area of professional shortage by many states. Resignations and terminations have been numerous as a result of poor student test performance. The purpose of this ex post facto correlation study was to investigate the self-perceptions of accountability by high school principals as they related to…

  18. Protostellar Jets: Numerical Simulations

    NASA Astrophysics Data System (ADS)

    Vitorino, B. F.; Jatenco-Pereira, V.; Opher, R.

    1998-11-01

    Numerical simulations of astrophysical jets have been made in order to study their collimation and internal structure. Recently Ouyed & Pudritz (1997) did numerical simulations of axi-simetric magnetocentrifugal jets from a keplerian acretion disk employing the eulerian finite difference code Zeus-2D. During their simulation, it was raised a steady state jet confirming a lot of results of the MHD winds steady state theory. Following this scenario we did tridimensional numerial simulations of this model allowing the jet, after a perturbation, evolve into a not steady state producing the helical features observed in some protostellar jets.

  19. Learning numerical progressions.

    PubMed

    Vitz, P C; Hazan, D N

    1974-01-01

    Learning of simple numerical progressions and compound progressions formed by combining two or three simple progressions is investigated. In two experiments, time to solution was greater for compound vs simple progressions; greater the higher the progression's solution level; and greater if the progression consisted of large vs small numbers. A set of strategies is proposed to account for progression learning based on the assumption S computes differences between integers, differences between differences, etc., in a hierarchical fashion. Two measures of progression difficulty, each a summary of the strategies, are proposed; C1 is a count of the number of differences needed to solve a progression; C2 is the same count with higher level differences given more weight. The measures accurately predict in both experiments the mean time to solve 16 different progressions with C2 being somewhat superior. The measures also predict the learning difficulty of 10 other progressions reported by Bjork (1968).

  20. Emerging accounting trends accounting for leases.

    PubMed

    Valletta, Robert; Huggins, Brian

    2010-12-01

    A new model for lease accounting can have a significant impact on hospitals and healthcare organizations. The new approach proposes a "right-of-use" model that involves complex estimates and significant administrative burden. Hospitals and health systems that draw heavily on lease arrangements should start preparing for the new approach now even though guidance and a final rule are not expected until mid-2011. This article highlights a number of considerations from the lessee point of view.

  1. Optimal control design that accounts for model mismatch errors

    SciTech Connect

    Kim, T.J.; Hull, D.G.

    1995-02-01

    A new technique is presented in this paper that reduces the complexity of state differential equations while accounting for modeling assumptions. The mismatch controls are defined as the differences between the model equations and the true state equations. The performance index of the optimal control problem is formulated with a set of tuning parameters that are user-selected to tune the control solution in order to achieve the best results. Computer simulations demonstrate that the tuned control law outperforms the untuned controller and produces results that are comparable to a numerically-determined, piecewise-linear optimal controller.

  2. Public Accountancy Handbook.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Office of the Professions.

    A reference guide to laws, rules, and regulations that govern public accountancy practice in New York State is presented. In addition to identifying licensing requirements/procedures for certified public accountants, general provisions of Title VIII of the Education Law are covered, along with state management, professional misconduct, and…

  3. PLATO IV Accountancy Index.

    ERIC Educational Resources Information Center

    Pondy, Dorothy, Comp.

    The catalog was compiled to assist instructors in planning community college and university curricula using the 48 computer-assisted accountancy lessons available on PLATO IV (Programmed Logic for Automatic Teaching Operation) for first semester accounting courses. It contains information on lesson access, lists of acceptable abbreviations for…

  4. Public Accountancy Handbook.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Office of the Professions.

    The laws, rules and regulations of the State Education Department governing public accountancy practice in New York State are provided in this handbook. Licensure requirements are also described, and the forms for obtaining a license and first registration as a certified public accountant are provided. The booklet is divided into the following…

  5. Leadership for Accountability.

    ERIC Educational Resources Information Center

    Lashway, Larry

    2001-01-01

    This document explores issues of leadership for accountability and reviews five resources on the subject. These include: (1) "Accountability by Carrots and Sticks: Will Incentives and Sanctions Motivate Students, Teachers, and Administrators for Peak Performance?" (Larry Lashway); (2) "Organizing Schools for Teacher Learning" (Judith Warren…

  6. The Accountability Illusion: Arizona

    ERIC Educational Resources Information Center

    Thomas B. Fordham Institute, 2009

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and…

  7. The Accountability Illusion: Minnesota

    ERIC Educational Resources Information Center

    Thomas B. Fordham Institute, 2009

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and…

  8. The Accountability Illusion: Nevada

    ERIC Educational Resources Information Center

    Thomas B. Fordham Institute, 2009

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and…

  9. The Accountability Illusion: California

    ERIC Educational Resources Information Center

    Thomas B. Fordham Institute, 2009

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and…

  10. Accountability for What?

    ERIC Educational Resources Information Center

    Knowles, Rex; Knowles; Trudy

    2001-01-01

    Our emphasis on accountability overlooks children's differences. Half of all individuals who take a norm-referenced test will be below average. Should such students be pushed, mauled, and remediated or squeezed into a common learning mold? Holding teachers accountable for humane treatment of "whole children" is a worthier pursuit. (MLH)

  11. The Evolution of Accountability

    ERIC Educational Resources Information Center

    Webb, P. Taylor

    2011-01-01

    Campus 2020: Thinking ahead is a policy in British Columbia (BC), Canada, that attempted to hold universities accountable to performance. Within, I demonstrate how this Canadian articulation of educational accountability intended to develop "governmentality constellations" to control the university and regulate its knowledge output. This research…

  12. Accountability in Education.

    ERIC Educational Resources Information Center

    Chippendale, P. R., Ed.; Wilkes, Paula V., Ed.

    This collection of papers delivered at a conference on accountability held at Darling Downs Institute of Advanced Education in Australia examines the meaning of accountability in education for teachers, lecturers, government, parents, administrators, education authorities, and the society at large. In Part 1, W. G. Walker attempts to answer the…

  13. NUMERICAL SIMULATION OF NATURAL GAS-SWIRL BURNER

    SciTech Connect

    Ala Qubbaj

    2005-03-01

    A numerical simulation of a turbulent natural gas jet diffusion flame at a Reynolds number of 9000 in a swirling air stream is presented. The numerical computations were carried out using the commercially available software package CFDRC. The instantaneous chemistry model was used as the reaction model. The thermal, composition, flow (velocity), as well as stream function fields for both the baseline and air-swirling flames were numerically simulated in the near-burner region, where most of the mixing and reactions occur. The results were useful to interpret the effects of swirl in enhancing the mixing rates in the combustion zone as well as in stabilizing the flame. The results showed the generation of two recirculating regimes induced by the swirling air stream, which account for such effects. The present investigation will be used as a benchmark study of swirl flow combustion analysis as a step in developing an enhanced swirl-cascade burner technology.

  14. Accountability and Primary Healthcare

    PubMed Central

    Mukhi, Shaheena; Barnsley, Jan; Deber, Raisa B.

    2014-01-01

    This paper examines the accountability structures within primary healthcare (PHC) in Ontario; in particular, who is accountable for what and to whom, and the policy tools being used. Ontario has implemented a series of incremental reforms, using expenditure policy instruments, enforced through contractual agreements to provide a defined set of publicly financed services that are privately delivered, most often by family physicians. The findings indicate that reporting, funding, evaluation and governance accountability requirements vary across service provider models. Accountability to the funder and patients is most common. Agreements, incentives and compensation tools have been used but may be insufficient to ensure parties are being held responsible for their activities related to stated goals. Clear definitions of various governance structures, a cohesive approach to monitoring critical performance indicators and associated improvement strategies are important elements in operationalizing accountability and determining whether goals are being met. PMID:25305392

  15. Accountability and primary healthcare.

    PubMed

    Mukhi, Shaheena; Barnsley, Jan; Deber, Raisa B

    2014-09-01

    This paper examines the accountability structures within primary healthcare (PHC) in Ontario; in particular, who is accountable for what and to whom, and the policy tools being used. Ontario has implemented a series of incremental reforms, using expenditure policy instruments, enforced through contractual agreements to provide a defined set of publicly financed services that are privately delivered, most often by family physicians. The findings indicate that reporting, funding, evaluation and governance accountability requirements vary across service provider models. Accountability to the funder and patients is most common. Agreements, incentives and compensation tools have been used but may be insufficient to ensure parties are being held responsible for their activities related to stated goals. Clear definitions of various governance structures, a cohesive approach to monitoring critical performance indicators and associated improvement strategies are important elements in operationalizing accountability and determining whether goals are being met. PMID:25305392

  16. Accountability in delivering care.

    PubMed

    Castledine, G

    In the penultimate part of this series on issues in ward management facing charge nurses. George Castledine concentrates on the issue of accountability. The immensely powerful position of the charge nurse as arbitrator and co-ordinator of all health care given to the patient demands that helshe exercises this power responsibly and positively; hence, the crucial importance of accountability. The author explores this concept and also those of advocacy and conscientious objection. He concludes by suggesting that the ultimate area of accountability in nursing is the individual conscience of the practitioner and that in this may lie the key to the setting and maintenance of high standards of care.

  17. Numerical simulation of dusty plasmas

    SciTech Connect

    Winske, D.

    1995-09-01

    The numerical simulation of physical processes in dusty plasmas is reviewed, with emphasis on recent results and unresolved issues. Three areas of research are discussed: grain charging, weak dust-plasma interactions, and strong dust-plasma interactions. For each area, we review the basic concepts that are tested by simulations, present some appropriate examples, and examine numerical issues associated with extending present work.

  18. Experimental and numerical investigations on melamine wedges.

    PubMed

    Schneider, S

    2008-09-01

    Melamine wedges are often used as acoustic lining material for anechoic chambers. It was proposed here to study the effects of the mounting conditions on the acoustic properties of the melamine wedges used in the large anechoic chamber at the LMA. The results of the impedance tube measurements carried out show that the mounting conditions must be taken into account when assessing the quality of an acoustic lining. As it can be difficult to simulate these mounting conditions in impedance tube experiments, a numerical method was developed, which can be used to complete the experiments or for parametric studies. By combining the finite and the boundary element method, it is possible to investigate acoustic linings with almost no restrictions as to the geometry, material behavior, or mounting conditions. The numerical method presented here was used to study the acoustic properties of the acoustic lining installed in the anechoic chamber at the LMA. Further experiments showed that the behavior of the melamine foam is anisotropic. Numerical simulations showed that this anisotropy can be used to advantage when designing an acoustic lining.

  19. Computerized material accounting

    SciTech Connect

    Claborn, J.; Erkkila, B.

    1995-07-01

    With the advent of fast, reliable database servers running on inexpensive networked personal computers, it is possible to create material accountability systems that are easy to learn, easy to use, and cost-effective to implement. Maintaining the material data in a relational database allows data to be viewed in ways that were previously very difficult. This paper describes a software and hardware platforms for the implementation of such an accountability system.

  20. Accountability: A New Disneyland Fantasy

    ERIC Educational Resources Information Center

    Bundy, Robert F.

    1974-01-01

    Parents, professional educators, boards of education, legislators, and the general public are justifiably questioning the monies spent on education, school efficiency, what schools are actually accomplishing, and who controls the results of schooling. However, accountability, as envisioned by its major supporters, will address none of these…

  1. Accounting for the environment.

    PubMed

    Lutz, E; Munasinghe, M

    1991-03-01

    Environmental awareness in the 1980s has led to efforts to improve the current UN System of National Accounts (SNA) for better measurement of the value of environmental resources when estimating income. National governments, the UN, the International Monetary Fund, and the World Bank are interested in solving this issue. The World Bank relies heavily on national aggregates in income accounts compiled by means of the SNA that was published in 1968 and stressed gross domestic product (GDP). GDP measures mainly market activity, but it takes does not consider the consumption of natural capital, and indirectly inhibits sustained development. The deficiencies of the current method of accounting are inconsistent treatment of manmade and natural capital, the omission of natural resources and their depletion from balance sheets, and pollution cleanup costs from national income. In the calculation of GDP pollution is overlooked, and beneficial environmental inputs are valued at zero. The calculation of environmentally adjusted net domestic product (EDP) and environmentally adjusted net income (ENI) would lower income and growth rate, as the World Resources Institute found with respect to Indonesia for 1971-84. When depreciation for oil, timber, and top soil was included the net domestic product (NDP) was only 4% compared with a 7.1% GDP. The World Bank has advocated environmental accounting since 1983 in SNA revisions. The 1989 revised Blue Book of the SNA takes environment concerns into account. Relevant research is under way in Mexico and Papua New Guinea using the UN Statistical Office framework as a system for environmentally adjusted economic accounts that computes EDP and ENI and integrates environmental data with national accounts while preserving SNA concepts. PMID:12285741

  2. Thinking about Accountability

    PubMed Central

    Deber, Raisa B.

    2014-01-01

    Accountability is a key component of healthcare reforms, in Canada and internationally, but there is increasing recognition that one size does not fit all. A more nuanced understanding begins with clarifying what is meant by accountability, including specifying for what, by whom, to whom and how. These papers arise from a Partnership for Health System Improvement (PHSI), funded by the Canadian Institutes of Health Research (CIHR), on approaches to accountability that examined accountability across multiple healthcare subsectors in Ontario. The partnership features collaboration among an interdisciplinary team, working with senior policy makers, to clarify what is known about best practices to achieve accountability under various circumstances. This paper presents our conceptual framework. It examines potential approaches (policy instruments) and postulates that their outcomes may vary by subsector depending upon (a) the policy goals being pursued, (b) governance/ownership structures and relationships and (c) the types of goods and services being delivered, and their production characteristics (e.g., contestability, measurability and complexity). PMID:25305385

  3. Influence of Hydraulic Design on Stability and on Pressure Pulsations in Francis Turbines at Overload, Part Load and Deep Part Load based on Numerical Simulations and Experimental Model Test Results

    NASA Astrophysics Data System (ADS)

    Magnoli, M. V.; Maiwald, M.

    2014-03-01

    Francis turbines have been running more and more frequently in part load conditions, in order to satisfy the new market requirements for more dynamic and flexible energy generation, ancillary services and grid regulation. The turbines should be able to be operated for longer durations with flows below the optimum point, going from part load to deep part load and even speed-no-load. These operating conditions are characterised by important unsteady flow phenomena taking place at the draft tube cone and in the runner channels, in the respective cases of part load and deep part load. The current expectations are that new Francis turbines present appropriate hydraulic stability and moderate pressure pulsations at overload, part load, deep part load and speed-no-load with high efficiency levels at normal operating range. This study presents series of investigations performed by Voith Hydro with the objective to improve the hydraulic stability of Francis turbines at overload, part load and deep part load, reduce pressure pulsations and enlarge the know-how about the transient fluid flow through the turbine at these challenging conditions. Model test measurements showed that distinct runner designs were able to influence the pressure pulsation level in the machine. Extensive experimental investigations focused on the runner deflector geometry, on runner features and how they could reduce the pressure oscillation level. The impact of design variants and machine configurations on the vortex rope at the draft tube cone at overload and part load and on the runner channel vortex at deep part load were experimentally observed and evaluated based on the measured pressure pulsation amplitudes. Numerical investigations were employed for improving the understanding of such dynamic fluid flow effects. As example for the design and experimental investigations, model test observations and pressure pulsation curves for Francis machines in mid specific speed range, around nqopt = 50 min

  4. An Empirical Investigation of the Relevant Skills of Forensic Accountants

    ERIC Educational Resources Information Center

    DiGabriele, James A.

    2008-01-01

    The author investigated whether views of the relevant skills of forensic accountants differ among forensic accounting practitioners, accounting academics, and users of forensic accounting services. Universities and colleges are currently considering adding forensic accounting courses to their curriculum. The results of the present study provide…

  5. The Nature and Origins of Students' Perceptions of Accountants

    ERIC Educational Resources Information Center

    Hunt, Steven C.; Falgiani, A. Anthony; Intrieri, Robert C.

    2004-01-01

    In this research, the authors examined accounting and nonaccounting majors' impressions of accountants through a survey listing 58 characteristics. The results show that many students stereotypically perceived accountants as numbers crunchers and that nonaccounting majors held more negative perceptions of accountants than did accounting majors.…

  6. 17 CFR 17.01 - Identification of special accounts, volume threshold accounts, and omnibus accounts.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... accounts, volume threshold accounts, and omnibus accounts. 17.01 Section 17.01 Commodity and Securities..., CLEARING MEMBERS, AND FOREIGN BROKERS § 17.01 Identification of special accounts, volume threshold accounts... in § 17.02(b). (b) Identification of volume threshold accounts. Each clearing member shall...

  7. 18 CFR 367.2320 - Account 232, Accounts payable.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Account 232, Accounts... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT TO... ACT Balance Sheet Chart of Accounts Current and Accrued Liabilities § 367.2320 Account 232,...

  8. 18 CFR 367.2320 - Account 232, Accounts payable.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Account 232, Accounts... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT TO... ACT Balance Sheet Chart of Accounts Current and Accrued Liabilities § 367.2320 Account 232,...

  9. 18 CFR 367.2320 - Account 232, Accounts payable.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Account 232, Accounts... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT TO... ACT Balance Sheet Chart of Accounts Current and Accrued Liabilities § 367.2320 Account 232,...

  10. 18 CFR 367.2320 - Account 232, Accounts payable.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Account 232, Accounts... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT TO... ACT Balance Sheet Chart of Accounts Current and Accrued Liabilities § 367.2320 Account 232,...

  11. 18 CFR 367.2320 - Account 232, Accounts payable.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Account 232, Accounts... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT TO... ACT Balance Sheet Chart of Accounts Current and Accrued Liabilities § 367.2320 Account 232,...

  12. Excel in the Accounting Curriculum: Perceptions from Accounting Professors

    ERIC Educational Resources Information Center

    Ramachandran Rackliffe, Usha; Ragland, Linda

    2016-01-01

    Public accounting firms emphasize the importance of accounting graduates being proficient in Excel. Since many accounting graduates often aspire to work in public accounting, a question arises as to whether there should be an emphasis on Excel in accounting education. The purpose of this paper is to specifically look at this issue by examining…

  13. Dietary and urinary metabonomic factors possibly accounting for higher blood pressure of black compared with white Americans: results of International Collaborative Study on macro-/micronutrients and blood pressure.

    PubMed

    Stamler, Jeremiah; Brown, Ian J; Yap, Ivan K S; Chan, Queenie; Wijeyesekera, Anisha; Garcia-Perez, Isabel; Chadeau-Hyam, Marc; Ebbels, Timothy M D; De Iorio, Maria; Posma, Joram; Daviglus, Martha L; Carnethon, Mercedes; Holmes, Elaine; Nicholson, Jeremy K; Elliott, Paul

    2013-12-01

    Black compared with non-Hispanic white Americans have higher systolic and diastolic blood pressure and rates of prehypertension/hypertension. Reasons for these adverse findings remain obscure. Analyses here focused on relations of foods/nutrients/urinary metabolites and higher black blood pressure for 369 black compared with 1190 non-Hispanic white Americans aged 40 to 59 years from 8 population samples. Multiple linear regression, standardized data from four 24-hour dietary recalls per person, two 24-hour urine collections, and 8 blood pressure measurements were used to quantitate the role of foods, nutrients, and metabolites in higher black blood pressure. Compared with non-Hispanic white Americans, blacks' average systolic/diastolic pressure was higher by 4.7/3.4 mm Hg (men) and 9.0/4.8 mm Hg (women). Control for higher body mass index of black women reduced excess black systolic/diastolic pressure to 6.8/3.8 mm Hg. Lesser intake of vegetables, fruits, grains, vegetable protein, glutamic acid, starch, fiber, minerals, and potassium, and higher intake of processed meats, pork, eggs, and sugar-sweetened beverages, along with higher cholesterol and higher Na/K ratio, related to in higher black blood pressure. Control for 11 nutrient and 10 non-nutrient correlates reduced higher black systolic/diastolic pressure to 2.3/2.3 mm Hg (52% and 33% reduction in men) and to 5.3/2.8 mm Hg (21% and 27% reduction in women). Control for foods/urinary metabolites had little further influence on higher black blood pressure. Less favorable multiple nutrient intake by blacks than non-Hispanic white Americans accounted, at least in part, for higher black blood pressure. Improved dietary patterns can contribute to prevention/control of more adverse black blood pressure levels.

  14. STAR facility tritium accountancy

    SciTech Connect

    Pawelko, R. J.; Sharpe, J. P.; Denny, B. J.

    2008-07-15

    The Safety and Tritium Applied Research (STAR) facility has been established to provide a laboratory infrastructure for the fusion community to study tritium science associated with the development of safe fusion energy and other technologies. STAR is a radiological facility with an administrative total tritium inventory limit of 1.5 g (14,429 Ci) [1]. Research studies with moderate tritium quantities and various radionuclides are performed in STAR. Successful operation of the STAR facility requires the ability to receive, inventory, store, dispense tritium to experiments, and to dispose of tritiated waste while accurately monitoring the tritium inventory in the facility. This paper describes tritium accountancy in the STAR facility. A primary accountancy instrument is the tritium Storage and Assay System (SAS): a system designed to receive, assay, store, and dispense tritium to experiments. Presented are the methods used to calibrate and operate the SAS. Accountancy processes utilizing the Tritium Cleanup System (TCS), and the Stack Tritium Monitoring System (STMS) are also discussed. Also presented are the equations used to quantify the amount of tritium being received into the facility, transferred to experiments, and removed from the facility. Finally, the STAR tritium accountability database is discussed. (authors)

  15. STAR Facility Tritium Accountancy

    SciTech Connect

    R. J. Pawelko; J. P. Sharpe; B. J. Denny

    2007-09-01

    The Safety and Tritium Applied Research (STAR) facility has been established to provide a laboratory infrastructure for the fusion community to study tritium science associated with the development of safe fusion energy and other technologies. STAR is a radiological facility with an administrative total tritium inventory limit of 1.5g (14,429 Ci) [1]. Research studies with moderate tritium quantities and various radionuclides are performed in STAR. Successful operation of the STAR facility requires the ability to receive, inventory, store, dispense tritium to experiments, and to dispose of tritiated waste while accurately monitoring the tritium inventory in the facility. This paper describes tritium accountancy in the STAR facility. A primary accountancy instrument is the tritium Storage and Assay System (SAS): a system designed to receive, assay, store, and dispense tritium to experiments. Presented are the methods used to calibrate and operate the SAS. Accountancy processes utilizing the Tritium Cleanup System (TCS), and the Stack Tritium Monitoring System (STMS) are also discussed. Also presented are the equations used to quantify the amount of tritium being received into the facility, transferred to experiments, and removed from the facility. Finally, the STAR tritium accountability database is discussed.

  16. Planning for Accountability.

    ERIC Educational Resources Information Center

    Cuneo, Tim; Bell, Shareen; Welsh-Gray, Carol

    1999-01-01

    Through its Challenge 2000 program, Joint Venture: Silicon Valley Network's 21st Century Education Initiative has been working with K-12 schools to improve student performance in literature, math, and science. Clearly stated standards, appropriate assessments, formal monitoring, critical friends, and systemwide accountability are keys to success.…

  17. Student Attendance Accounting Manual.

    ERIC Educational Resources Information Center

    Freitas, Joseph M.

    In response to state legislation authorizing procedures for changes in academic calendars and measurement of student workload in California community colleges, this manual from the Chancellor's Office provides guidelines for student attendance accounting. Chapter 1 explains general items such as the academic calendar, admissions policies, student…

  18. Accountability for Productivity

    ERIC Educational Resources Information Center

    Wellman, Jane

    2010-01-01

    Productivity gains in higher education won't be made just by improving cost effectiveness or even performance. They need to be documented, communicated, and integrated into a strategic agenda to increase attainment. This requires special attention to "accountability" for productivity, meaning public presentation and communication of evidence about…

  19. The Accountability Illusion

    ERIC Educational Resources Information Center

    Cronin, John; Dahlin, Michael; Xiang, Yun; McCahon, Donna

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states have leeway to: (1) Craft their own academic standards, select their own tests, and define…

  20. Accounting for What Counts

    ERIC Educational Resources Information Center

    Milner, Joseph O.; Ferran, Joan E.; Martin, Katharine Y.

    2003-01-01

    No Child Left Behind legislation makes it clear that outside evaluators determine what gets taught in the classroom. It is important to ensure they measure what truly counts in school. This fact is poignantly and sadly true for the under funded, poorly resourced, "low performing" schools that may be hammered by administration accountants in the…

  1. Accountability: A Rationale.

    ERIC Educational Resources Information Center

    Brademas, John

    1974-01-01

    The idea of accountability has by now been interpreted in ways which are different enough from one another to have permitted a certain ambiguity to creep into the notion in its present use within the educational community. The principal purpose of this report is, therefore, to try to set forth some clearer statement of what the idea of…

  2. Fiscal Accounting Manual.

    ERIC Educational Resources Information Center

    California State Dept. of Housing and Community Development, Sacramento. Indian Assistance Program.

    Written in simple, easy to understand form, the manual provides a vehicle for the untrained person in bookkeeping to control funds received from grants for Indian Tribal Councils and Indian organizations. The method used to control grants (federal, state, or private) is fund accounting, designed to organize rendering services on a non-profit…

  3. Curtail Accountability, Cultivate Attainability

    ERIC Educational Resources Information Center

    Wraga, William G.

    2011-01-01

    The current test-driven accountability movement, codified in the No Child Left Behind Act of 2001 ([NCLB] 2002), was a misguided idea that will have the effect not of improving the education of children and youth, but of indicting the public school system of the United States. To improve education in the United States, politicians, policy makers,…

  4. Legal responsibility and accountability.

    PubMed

    Cox, Chris

    2010-06-01

    Shifting boundaries in healthcare roles have led to anxiety among some nurses about their legal responsibilities and accountabilities. This is partly because of a lack of education about legal principles that underpin healthcare delivery. This article explains the law in terms of standards of care, duty of care, vicarious liability and indemnity insurance.

  5. Accounting 202, 302.

    ERIC Educational Resources Information Center

    Manitoba Dept. of Education, Winnipeg.

    This teaching guide consists of guidelines for conducting two secondary-level introductory accounting courses. Intended for vocational business education students, the courses are designed to introduce financial principles and practices important to personal and business life, to promote development of clerical and bookkeeping skills sufficient…

  6. Democracy, Accountability, and Education

    ERIC Educational Resources Information Center

    Levinson, Meira

    2011-01-01

    Educational standards, assessments, and accountability systems are of immense political moment around the world. But there is no developed theory exploring the role that these systems should play within a democratic polity in particular. On the one hand, well-designed standards are public goods, supported by assessment and accountability…

  7. Educational Accounting Procedures.

    ERIC Educational Resources Information Center

    Tidwell, Sam B.

    This chapter of "Principles of School Business Management" reviews the functions, procedures, and reports with which school business officials must be familiar in order to interpret and make decisions regarding the school district's financial position. Among the accounting functions discussed are financial management, internal auditing, annual…

  8. CEBAF beam loss accounting

    SciTech Connect

    Ursic, R.; Mahoney, K.; Hovater, C.; Hutton, A.; Sinclair, C.

    1995-12-31

    This paper describes the design and implementation of a beam loss accounting system for the CEBAF electron accelerator. This system samples the beam curent throughout the beam path and measures the beam current accurately. Personnel Safety and Machine Protection systems use this system to turn off the beam when hazardous beam losses occur.

  9. Test-Based Teacher Evaluations: Accountability vs. Responsibility

    ERIC Educational Resources Information Center

    Bolyard, Chloé

    2015-01-01

    Gert Biesta contends that managerial accountability, which focuses on efficiency and competition, dominates the current political arena in education. Such accountability has influenced states' developments of test-based teacher evaluations in an attempt to quantify teachers' efficacy on student learning. With numerous state policies requiring the…

  10. Numerical simulation of electrophoresis separation processes

    NASA Technical Reports Server (NTRS)

    Ganjoo, D. K.; Tezduyar, T. E.

    1986-01-01

    A new Petrov-Galerkin finite element formulation has been proposed for transient convection-diffusion problems. Most Petrov-Galerkin formulations take into account the spatial discretization, and the weighting functions so developed give satisfactory solutions for steady state problems. Though these schemes can be used for transient problems, there is scope for improvement. The schemes proposed here, which consider temporal as well as spatial discretization, provide improved solutions. Electrophoresis, which involves the motion of charged entities under the influence of an applied electric field, is governed by equations similiar to those encountered in fluid flow problems, i.e., transient convection-diffusion equations. Test problems are solved in electrophoresis and fluid flow. The results obtained are satisfactory. It is also expected that these schemes, suitably adapted, will improve the numerical solutions of the compressible Euler and the Navier-Stokes equations.

  11. Numerical simulations of collisions between rotating particles

    NASA Astrophysics Data System (ADS)

    Salo, H.

    1987-04-01

    Numerical simulations of Keplerian systems consisting of 200 mutually colliding rotating particles show that friction and surface irregularity reduce the equilibrium velocity dispersion and transfer some of the energy of random velocities to rotational velocities. The results confirm the theoretical predictions of Salo (1987). Simulations are performed for identical and different particle sizes, and for a power-law distribution of sizes. Taking rotation into account is not found to alter the previously observed Rayleigh distribution of eccentricities and inclinations, while the components of the rotational velocities are found to follow a Gaussian distribution. Application to the rarefied regions of Saturn's rings suggests that friction is able to reduce the equilibrium geometric thickness by about one-half.

  12. Numerical simulations to study solar wind turbulence

    SciTech Connect

    Sharma, R. P.; Sharma, Nidhi; Kumar, Sanjay; Kumar, Sachin; Singh, H. D.

    2011-02-15

    Numerical simulation of coupled equations of kinetic Alfven wave (KAW) and ion acoustic wave is presented in the solar wind. The nonlinear dynamical equations satisfy the modified Zakharov system of equations by taking the nonadiabatic response of the background density. The ponderomotive nonlinearity is incorporated in the wave dynamics. The effect of Landau damping of KAW is taken into account. Localization of magnetic field intensity and the wavenumber spectra (perpendicular and parallel) of magnetic fluctuations are studied in solar plasmas around 1 a.u. Our results reveal the formation of damped localized structures and the steeper spectra that are in good agreement with the observations. These damped structures and steeper turbulent spectra can be responsible for plasma heating and particle acceleration in solar wind.

  13. Numerical simulation of double-diffusive finger convection

    USGS Publications Warehouse

    Hughes, J.D.; Sanford, W.E.; Vacher, H.L.

    2005-01-01

    A hybrid finite element, integrated finite difference numerical model is developed for the simulation of double-diffusive and multicomponent flow in two and three dimensions. The model is based on a multidimensional, density-dependent, saturated-unsaturated transport model (SUTRA), which uses one governing equation for fluid flow and another for solute transport. The solute-transport equation is applied sequentially to each simulated species. Density coupling of the flow and solute-transport equations is accounted for and handled using a sequential implicit Picard iterative scheme. High-resolution data from a double-diffusive Hele-Shaw experiment, initially in a density-stable configuration, is used to verify the numerical model. The temporal and spatial evolution of simulated double-diffusive convection is in good agreement with experimental results. Numerical results are very sensitive to discretization and correspond closest to experimental results when element sizes adequately define the spatial resolution of observed fingering. Numerical results also indicate that differences in the molecular diffusivity of sodium chloride and the dye used to visualize experimental sodium chloride concentrations are significant and cause inaccurate mapping of sodium chloride concentrations by the dye, especially at late times. As a result of reduced diffusion, simulated dye fingers are better defined than simulated sodium chloride fingers and exhibit more vertical mass transfer. Copyright 2005 by the American Geophysical Union.

  14. Iowa Community Colleges Accounting Manual.

    ERIC Educational Resources Information Center

    Iowa State Dept. of Education, Des Moines. Div. of Community Colleges and Workforce Preparation.

    This document describes account classifications and definitions for the accounting system of the Iowa community colleges. In view of the objectives of the accounting system, it is necessary to segregate the assets of the community college according to its source and intended use. Additionally, the accounting system should provide for accounting by…

  15. On the Numerical Dispersion of Electromagnetic Particle-In-Cell Code : Finite Grid Instability

    SciTech Connect

    Meyers, Michael David; Huang, Chengkun; Zeng, Yong; Yi, Sunghwan; Albright, Brian James

    2014-07-15

    The Particle-In-Cell (PIC) method is widely used in relativistic particle beam and laser plasma modeling. However, the PIC method exhibits numerical instabilities that can render unphysical simulation results or even destroy the simulation. For electromagnetic relativistic beam and plasma modeling, the most relevant numerical instabilities are the finite grid instability and the numerical Cherenkov instability. We review the numerical dispersion relation of the electromagnetic PIC algorithm to analyze the origin of these instabilities. We rigorously derive the faithful 3D numerical dispersion of the PIC algorithm, and then specialize to the Yee FDTD scheme. In particular, we account for the manner in which the PIC algorithm updates and samples the fields and distribution function. Temporal and spatial phase factors from solving Maxwell's equations on the Yee grid with the leapfrog scheme are also explicitly accounted for. Numerical solutions to the electrostatic-like modes in the 1D dispersion relation for a cold drifting plasma are obtained for parameters of interest. In the succeeding analysis, we investigate how the finite grid instability arises from the interaction of the numerical 1D modes admitted in the system and their aliases. The most significant interaction is due critically to the correct representation of the operators in the dispersion relation. We obtain a simple analytic expression for the peak growth rate due to this interaction.

  16. Khipu accounting in ancient Peru.

    PubMed

    Urton, Gary; Brezine, Carrie J

    2005-08-12

    Khipu are knotted-string devices that were used for bureaucratic recording and communication in the Inka Empire. We recently undertook a computer analysis of 21 khipu from the Inka administrative center of Puruchuco, on the central coast of Peru. Results indicate that this khipu archive exemplifies the way in which census and tribute data were synthesized, manipulated, and transferred between different accounting levels in the Inka administrative system.

  17. New prescriptions of turbulent transport from local numerical simulations

    NASA Astrophysics Data System (ADS)

    Prat, V.; Lignières, F.; Lesur, G.

    2015-01-01

    Massive stars often experience fast rotation, which is known to induce turbulent mixing with a strong impact on the evolution of these stars. Local direct numerical simulations of turbulent transport in stellar radiative zones are a promising way to constrain phenomenological transport models currently used in many stellar evolution codes. We present here the results of such simulations of stably-stratified sheared turbulence taking notably into account the effects of thermal diffusion and chemical stratification. We also discuss the impact of theses results on stellar evolution theory.

  18. Chloride diffusivity in hardened cement paste from microscale analyses and accounting for binding effects

    NASA Astrophysics Data System (ADS)

    Carrara, P.; De Lorenzis, L.; Bentz, D. P.

    2016-08-01

    The diffusion of chloride ions in hardened cement paste (HCP) under steady-state conditions and accounting for the highly heterogeneous nature of the material is investigated. The three-dimensional HCP microstructures are obtained through segmentation of x-ray images of real samples as well as from simulations using the cement hydration model CEMHYD3D. Moreover, the physical and chemical interactions between chloride ions and HCP phases (binding), along with their effects on the diffusive process, are explicitly taken into account. The homogenized diffusivity of the HCP is then derived through a least square homogenization technique. Comparisons between numerical results and experimental data from the literature are presented.

  19. Hospitals' Internal Accountability

    PubMed Central

    Kraetschmer, Nancy; Jass, Janak; Woodman, Cheryl; Koo, Irene; Kromm, Seija K.; Deber, Raisa B.

    2014-01-01

    This study aimed to enhance understanding of the dimensions of accountability captured and not captured in acute care hospitals in Ontario, Canada. Based on an Ontario-wide survey and follow-up interviews with three acute care hospitals in the Greater Toronto Area, we found that the two dominant dimensions of hospital accountability being reported are financial and quality performance. These two dimensions drove both internal and external reporting. Hospitals' internal reports typically included performance measures that were required or mandated in external reports. Although respondents saw reporting as a valuable mechanism for hospitals and the health system to monitor and track progress against desired outcomes, multiple challenges with current reporting requirements were communicated, including the following: 58% of survey respondents indicated that performance-reporting resources were insufficient; manual data capture and performance reporting were prevalent, with the majority of hospitals lacking sophisticated tools or technology to effectively capture, analyze and report performance data; hospitals tended to focus on those processes and outcomes with high measurability; and 53% of respondents indicated that valuable cross-system accountability, performance measures or both were not captured by current reporting requirements. PMID:25305387

  20. Hospitals' internal accountability.

    PubMed

    Kraetschmer, Nancy; Jass, Janak; Woodman, Cheryl; Koo, Irene; Kromm, Seija K; Deber, Raisa B

    2014-09-01

    This study aimed to enhance understanding of the dimensions of accountability captured and not captured in acute care hospitals in Ontario, Canada. Based on an Ontario-wide survey and follow-up interviews with three acute care hospitals in the Greater Toronto Area, we found that the two dominant dimensions of hospital accountability being reported are financial and quality performance. These two dimensions drove both internal and external reporting. Hospitals' internal reports typically included performance measures that were required or mandated in external reports. Although respondents saw reporting as a valuable mechanism for hospitals and the health system to monitor and track progress against desired outcomes, multiple challenges with current reporting requirements were communicated, including the following: 58% of survey respondents indicated that performance-reporting resources were insufficient; manual data capture and performance reporting were prevalent, with the majority of hospitals lacking sophisticated tools or technology to effectively capture, analyze and report performance data; hospitals tended to focus on those processes and outcomes with high measurability; and 53% of respondents indicated that valuable cross-system accountability, performance measures or both were not captured by current reporting requirements. PMID:25305387

  1. Numerical Optimization Using Computer Experiments

    NASA Technical Reports Server (NTRS)

    Trosset, Michael W.; Torczon, Virginia

    1997-01-01

    Engineering design optimization often gives rise to problems in which expensive objective functions are minimized by derivative-free methods. We propose a method for solving such problems that synthesizes ideas from the numerical optimization and computer experiment literatures. Our approach relies on kriging known function values to construct a sequence of surrogate models of the objective function that are used to guide a grid search for a minimizer. Results from numerical experiments on a standard test problem are presented.

  2. Numerical modeling of gas-liquid flows in mini- and microchannels

    NASA Astrophysics Data System (ADS)

    Guzei, D. V.; Minakov, A. V.; Pryazhnikov, M. I.; Dekterev, A. A.

    2015-01-01

    The paper presents the results of testing a methodology for calculating two-phase flows in mini- and microchannels. The numerical methodology is based on the known fluid-in-cell method (VOF method) and the CSF procedure to account for surface tension forces. Solutions of several test problems of two-phase flow in microchannels, including the water-oil emulsion flow and gas-liquid flow in microchannels of the T-type and the stationary slug flow in a circular minichannel, were considered with the aid of this technique. Comparisons of numerical results with experimental data were carried out. A good agreement between the results was obtained.

  3. Numerical Boundary Condition Procedures

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Topics include numerical procedures for treating inflow and outflow boundaries, steady and unsteady discontinuous surfaces, far field boundaries, and multiblock grids. In addition, the effects of numerical boundary approximations on stability, accuracy, and convergence rate of the numerical solution are discussed.

  4. Computerized accounting methods. Final report

    SciTech Connect

    1994-12-31

    This report summarizes the results of the research performed under the Task Order on computerized accounting methods in a period from 03 August to 31 December 1994. Computerized nuclear material accounting methods are analyzed and evaluated. Selected methods are implemented in a hardware-software complex developed as a prototype of the local network-based CONMIT system. This complex has been put into trial operation for test and evaluation of the selected methods at two selected ``Kurchatov Institute`` Russian Research Center (``KI`` RRC) nuclear facilities. Trial operation is carried out since the beginning of Initial Physical Inventory Taking in these facilities that was performed in November 1994. Operation of CONMIT prototype system was demonstrated in the middle of December 1994. Results of evaluation of CONMIT prototype system features and functioning under real operating conditions are considered. Conclusions are formulated on the ways of further development of computerized nuclear material accounting methods. The most important conclusion is a need to strengthen computer and information security features supported by the operating environment. Security provisions as well as other LANL Client/Server System approaches being developed by Los Alamos National Laboratory are recommended for selection of software and hardware components to be integrated into production version of CONMIT system for KI RRC.

  5. Teaching Elementary Accounting to Non-Accounting Majors

    ERIC Educational Resources Information Center

    Lloyd, Cynthia B.; Abbey, Augustus

    2009-01-01

    A central recurring theme in business education is the optimal strategy for improving introductory accounting, the gateway subject of business education. For many students, especially non-accounting majors, who are required to take introductory accounting as a requirement of the curriculum, introductory accounting has become a major obstacle for…

  6. New Frontiers: Training Forensic Accountants within the Accounting Program

    ERIC Educational Resources Information Center

    Ramaswamy, Vinita

    2007-01-01

    Accountants have recently been subject to very unpleasant publicity following the collapse of Enron and other major companies. There has been a plethora of accounting failures and accounting restatements of falsified earnings, with litigations and prosecutions taking place every day. As the FASB struggles to tighten the loopholes in accounting,…

  7. 18 CFR 367.1420 - Account 142, Customer accounts receivable.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT... GAS ACT Balance Sheet Chart of Accounts Current and Accrued Assets § 367.1420 Account 142, Customer... merchandising, jobbing and contract work. This account must not include amounts due from associate companies....

  8. Towards numerical prediction of cavitation erosion

    PubMed Central

    Fivel, Marc; Franc, Jean-Pierre; Chandra Roy, Samir

    2015-01-01

    This paper is intended to provide a potential basis for a numerical prediction of cavitation erosion damage. The proposed method can be divided into two steps. The first step consists in determining the loading conditions due to cavitation bubble collapses. It is shown that individual pits observed on highly polished metallic samples exposed to cavitation for a relatively small time can be considered as the signature of bubble collapse. By combining pitting tests with an inverse finite-element modelling (FEM) of the material response to a representative impact load, loading conditions can be derived for each individual bubble collapse in terms of stress amplitude (in gigapascals) and radial extent (in micrometres). This step requires characterizing as accurately as possible the properties of the material exposed to cavitation. This characterization should include the effect of strain rate, which is known to be high in cavitation erosion (typically of the order of several thousands s−1). Nanoindentation techniques as well as compressive tests at high strain rate using, for example, a split Hopkinson pressure bar test system may be used. The second step consists in developing an FEM approach to simulate the material response to the repetitive impact loads determined in step 1. This includes a detailed analysis of the hardening process (isotropic versus kinematic) in order to properly account for fatigue as well as the development of a suitable model of material damage and failure to account for mass loss. Although the whole method is not yet fully operational, promising results are presented that show that such a numerical method might be, in the long term, an alternative to correlative techniques used so far for cavitation erosion prediction. PMID:26442139

  9. Towards numerical prediction of cavitation erosion.

    PubMed

    Fivel, Marc; Franc, Jean-Pierre; Chandra Roy, Samir

    2015-10-01

    This paper is intended to provide a potential basis for a numerical prediction of cavitation erosion damage. The proposed method can be divided into two steps. The first step consists in determining the loading conditions due to cavitation bubble collapses. It is shown that individual pits observed on highly polished metallic samples exposed to cavitation for a relatively small time can be considered as the signature of bubble collapse. By combining pitting tests with an inverse finite-element modelling (FEM) of the material response to a representative impact load, loading conditions can be derived for each individual bubble collapse in terms of stress amplitude (in gigapascals) and radial extent (in micrometres). This step requires characterizing as accurately as possible the properties of the material exposed to cavitation. This characterization should include the effect of strain rate, which is known to be high in cavitation erosion (typically of the order of several thousands s(-1)). Nanoindentation techniques as well as compressive tests at high strain rate using, for example, a split Hopkinson pressure bar test system may be used. The second step consists in developing an FEM approach to simulate the material response to the repetitive impact loads determined in step 1. This includes a detailed analysis of the hardening process (isotropic versus kinematic) in order to properly account for fatigue as well as the development of a suitable model of material damage and failure to account for mass loss. Although the whole method is not yet fully operational, promising results are presented that show that such a numerical method might be, in the long term, an alternative to correlative techniques used so far for cavitation erosion prediction. PMID:26442139

  10. Theoretical and numerical studies of density modulated whistlers

    NASA Astrophysics Data System (ADS)

    Eliasson, B.; Shukla, P. K.

    2004-09-01

    Recently, observations from laboratory experiments, which are relevant to space observations as well, have conclusively revealed the amplitude modulation of whistlers by low-frequency perturbations. Our objective here is to present theoretical and simulation studies of amplitude modulated whistler packets on account of their interaction with background low-frequency density perturbations that are reinforced by the whistler ponderomotive force. Specifically, we show that nonlinear interactions between whistlers and finite amplitude density perturbations are governed by a nonlinear Schrödinger equation for the modulated whistlers, and a set of equations for arbitrary large amplitude density perturbations in the presence of the whistler ponderomotive force. The governing equations are solved numerically to show the existence of large scale density perturbations that are self-consistently created by localized modulated whistler wavepackets. Our numerical results are found to be in good agreement with experimental results, as well as have relevance to observations from magnetized space plasmas.

  11. 2D numerical modelling of meandering channel formation

    NASA Astrophysics Data System (ADS)

    XIAO, Y.; ZHOU, G.; YANG, F. S.

    2016-03-01

    A 2D depth-averaged model for hydrodynamic sediment transport and river morphological adjustment was established. The sediment transport submodel takes into account the influence of non-uniform sediment with bed surface armoring and considers the impact of secondary flow in the direction of bed-load transport and transverse slope of the river bed. The bank erosion submodel incorporates a simple simulation method for updating bank geometry during either degradational or aggradational bed evolution. Comparison of the results obtained by the extended model with experimental and field data, and numerical predictions validate that the proposed model can simulate grain sorting in river bends and duplicate the characteristics of meandering river and its development. The results illustrate that by using its control factors, the improved numerical model can be applied to simulate channel evolution under different scenarios and improve understanding of patterning processes.

  12. Numerical Propulsion System Simulation

    NASA Technical Reports Server (NTRS)

    Naiman, Cynthia

    2006-01-01

    The NASA Glenn Research Center, in partnership with the aerospace industry, other government agencies, and academia, is leading the effort to develop an advanced multidisciplinary analysis environment for aerospace propulsion systems called the Numerical Propulsion System Simulation (NPSS). NPSS is a framework for performing analysis of complex systems. The initial development of NPSS focused on the analysis and design of airbreathing aircraft engines, but the resulting NPSS framework may be applied to any system, for example: aerospace, rockets, hypersonics, power and propulsion, fuel cells, ground based power, and even human system modeling. NPSS provides increased flexibility for the user, which reduces the total development time and cost. It is currently being extended to support the NASA Aeronautics Research Mission Directorate Fundamental Aeronautics Program and the Advanced Virtual Engine Test Cell (AVETeC). NPSS focuses on the integration of multiple disciplines such as aerodynamics, structure, and heat transfer with numerical zooming on component codes. Zooming is the coupling of analyses at various levels of detail. NPSS development includes capabilities to facilitate collaborative engineering. The NPSS will provide improved tools to develop custom components and to use capability for zooming to higher fidelity codes, coupling to multidiscipline codes, transmitting secure data, and distributing simulations across different platforms. These powerful capabilities extend NPSS from a zero-dimensional simulation tool to a multi-fidelity, multidiscipline system-level simulation tool for the full development life cycle.

  13. Numerical model of Fanuc AM100iB robot

    NASA Astrophysics Data System (ADS)

    Cholewa, A.; Świder, J.; Zbilski, A.

    2016-08-01

    The article presents a numerical model of Fanuc AM 100iB robot, prepared in the form of a block diagram in Simulink software, using the SimMechanics toolbox. The main task of the numerical model of Fanuc AM 100iB robot is to calculate the value of torques putting a load on motor shafts, and to calculate the values of kinematic parameters of the robot's arms in real time and in interactive mode. The values and format of torques putting a load on subsequent joints, and then on the motor shafts, resulted from the effect of the simultaneous action of all torques and the delay, resulting from the implementation of numerical calculations in real time. The numerical model developed is a result of design focused on recreating the effects of simultaneous action of all these factors, which are present in the actual drives and affect the consumption of electricity. A very important criterion, taken into account when designing the model, was also its computational efficiency. In addition, the model was used to visualise the work of the tested machine in three-dimensional space.

  14. Processing biobased polymers using plasticizers: Numerical simulations versus experiments

    NASA Astrophysics Data System (ADS)

    Desplentere, Frederik; Cardon, Ludwig; Six, Wim; Erkoç, Mustafa

    2016-03-01

    In polymer processing, the use of biobased products shows lots of possibilities. Considering biobased materials, biodegradability is in most cases the most important issue. Next to this, bio based materials aimed at durable applications, are gaining interest. Within this research, the influence of plasticizers on the processing of the bio based material is investigated. This work is done for an extrusion grade of PLA, Natureworks PLA 2003D. Extrusion through a slit die equipped with pressure sensors is used to compare the experimental pressure values to numerical simulation results. Additional experimental data (temperature and pressure data along the extrusion screw and die are recorded) is generated on a dr. Collin Lab extruder producing a 25mm diameter tube. All these experimental data is used to indicate the appropriate functioning of the numerical simulation tool Virtual Extrusion Laboratory 6.7 for the simulation of both the industrial available extrusion grade PLA and the compound in which 15% of plasticizer is added. Adding the applied plasticizer, resulted in a 40% lower pressure drop over the extrusion die. The combination of different experiments allowed to fit the numerical simulation results closely to the experimental values. Based on this experience, it is shown that numerical simulations also can be used for modified bio based materials if appropriate material and process data are taken into account.

  15. Performance and Accountability Report

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The NASA Fiscal Year 2002 Performance and Accountability Report is presented. Over the past year, significant changes have been implemented to greatly improve NASA's management while continuing to break new ground in science and technology. Excellent progress has been made in implementing the President's Management Agenda. NASA is leading the government in its implementation of the five government-wide initiatives. NASA received an unqualified audit opinion on FY 2002 financial statements. The vast majority of performance goals have been achieved, furthering each area of NASA's mission. The contents include: 1) NASA Vision and Mission; 2) Management's Discussion and Analysis; 3) Performance; and 4) Financial.

  16. Results of correlations for transition location on a clean-up glove installed on an F-14 aircraft and design studies for a laminar glove for the X-29 aircraft accounting for spanwise pressure gradient

    NASA Technical Reports Server (NTRS)

    Goradia, S. H.; Bobbitt, P. J.; Morgan, H. L.; Ferris, J. C.; Harvey, William D.

    1989-01-01

    Results of correlative and design studies for transition location, laminar and turbulent boundary-layer parameters, and wake drag for forward swept and aft swept wings are presented. These studies were performed with the use of an improved integral-type boundary-layer and transition-prediction methods. Theoretical predictions were compared with flight measurements at subsonic and transonic flow conditions for the variable aft swept wing F-14 aircraft for which experimental pressure distributions, transition locations, and turbulent boundary-layer velocity profiles were measured. Flight data were available at three spanwise stations for several values of sweep, freestream unit Reynolds number, Mach numbers, and lift coefficients. Theory/experiment correlations indicate excellent agreement for both transition location and turbulent boundary-layer parameters. The results of parametric studies performed during the design of a laminar glove for the forward swept wing X-29 aircraft are also presented. These studies include the effects of a spanwise pressure gradient on transition location and wake drag for several values of freestream Reynolds numbers at a freestream Mach number of 0.9.

  17. A Class of TVD Type Combined Numerical Scheme for MHD Equations With a Survey About Numerical Methods in Solar Wind Simulations

    NASA Astrophysics Data System (ADS)

    Feng, Xueshang; Wu, S. T.; Wei, Fengsi; Fan, Quanlin

    2003-04-01

    It has been believed that three-dimensional, numerical, magnetohydrodynamic (MHD) modelling must play a crucial role in a seamless forecasting system. This system refers to space weather originating on the sun; propagation of disturbances through the solar wind and interplanetary magnetic field (IMF), and thence, transmission into the magnetosphere, ionosphere, and thermosphere. This role comes as no surprise to numerical modelers that participate in the numerical modelling of atmospheric environments as well as the meteorological conditions at Earth. Space scientists have paid great attention to operational numerical space weather prediction models. To this purpose practical progress has been made in the past years. Here first is reviewed the progress of the numerical methods in solar wind modelling. Then, based on our discussion, a new numerical scheme of total variation diminishing (TVD) type for magnetohydrodynamic equations in spherical coordinates is proposed by taking into account convergence, stability and resolution. This new MHD model is established by solving the fluid equations of MHD system with a modified Lax-Friedrichs scheme and the magnetic induction equations with MacCormack II scheme for the purpose of developing a combined scheme of quick convergence as well as of TVD property. To verify the validation of the scheme, the propagation of one-dimensional MHD fast and slow shock problem is discussed with the numerical results conforming to the existing results obtained by the piece-wise parabolic method (PPM). Finally, some conclusions are made.

  18. Standards-Based Accountability Systems. Policy Brief.

    ERIC Educational Resources Information Center

    Stapleman, Jan

    This policy brief summarizes research results and provides guidance regarding decisions associated with school accountability. Unlike previous notions of accountability, a standards-based system examines outputs, such as student performance and graduation rates, as well as inputs like the amount of instructional time or the number of books in the…

  19. Faculty Perceptions of Online Accounting Coursework

    ERIC Educational Resources Information Center

    Grossman, Amanda M.; Johnson, Leigh R.

    2015-01-01

    The perceptions of faculty members, who design and evaluate online accounting coursework content, are an important consideration in determining the quality inherent in such content. This study reports the results of a survey which examines accounting faculty members' attitudes towards online education (measured as their willingness to accept…

  20. An Accounting Scheme for Personality Study.

    ERIC Educational Resources Information Center

    Dillon, James J.; Feldman, S. Shirley

    Realizing the importance of human personality variables in comprehensive educational assessment structures, Operation PEP sought to develop a tool to assess specific human personality characteristics. The resulting accounting scheme is divided into three chapters: (1) an outline and definition of relevant terminology, (2) a scheme to account for…

  1. Changes to the Intermediate Accounting Course Sequence

    ERIC Educational Resources Information Center

    Davidson, Lesley H.; Francisco, William H.

    2009-01-01

    There is an ever-growing amount of information that must be covered in Intermediate Accounting courses. Due to recent accounting standards and the implementation of IFRS this trend is likely to continue. This report incorporates the results of a recent survey to examine the trend of spending more course time to cover this additional material.…

  2. Revamping High School Accounting Courses.

    ERIC Educational Resources Information Center

    Bittner, Joseph

    2002-01-01

    Provides ideas for updating accounting courses: convert to semester length; focus on financial reporting/analysis, financial statements, the accounting cycle; turn textbook exercises into practice sets for the accounting cycle; teach about corporate accounting; and address individual line items on financial statements. (SK)

  3. Where Are the Accounting Professors?

    ERIC Educational Resources Information Center

    Chang, Jui-Chin; Sun, Huey-Lian

    2008-01-01

    Accounting education is facing a crisis of shortage of accounting faculty. This study discusses the reasons behind the shortage and offers suggestions to increase the supply of accounting faculty. Our suggestions are as followings. First, educators should begin promoting accounting academia as one of the career choices to undergraduate and…

  4. Accountability and the New Essentials.

    ERIC Educational Resources Information Center

    Dowd, Steven B.

    The current emphasis in education on accountability is tending toward "push-button accountability." The challenge is to evaluate access and retention as well as other educationally relevant goals to define "quality" or "accountability." In higher education, accountability should be proven through assessment and should consist of proof that what…

  5. Water Accounting from Ungauged Basins

    NASA Astrophysics Data System (ADS)

    Bastiaanssen, W. G.; Savenije, H.

    2014-12-01

    Water scarcity is increasing globally. This requires a more accurate management of the water resources at river basin scale and understanding of withdrawals and return flows; both naturally and man-induced. Many basins and their tributaries are, however, ungauged or poorly gauged. This hampers sound planning and monitoring processes. While certain countries have developed clear guidelines and policies on data observatories and data sharing, other countries and their basin organization still have to start on developing data democracies. Water accounting quantifies flows, fluxes, stocks and consumptive use pertaining to every land use class in a river basin. The objective is to derive a knowledge base with certain minimum information that facilitates decision making. Water Accounting Plus (WA+) is a new method for water resources assessment reporting (www.wateraccounting.org). While the PUB framework has yielded several deterministic models for flow prediction, WA+ utilizes remote sensing data of rainfall, evaporation (including soil, water, vegetation and interception evaporation), soil moisture, water levels, land use and biomass production. Examples will be demonstrated that show how remote sensing and hydrological models can be smartly integrated for generating all the required input data into WA+. A standard water accounting system for all basins in the world - with a special emphasis on data scarce regions - is under development. First results of using remote sensing measurements and hydrological modeling as an alternative to expensive field data sets, will be presented and discussed.

  6. Numerical model for combined conductive and radiative heat transfer in annular packed beds

    SciTech Connect

    Kamiuto, K.; Saito, S.; Ito, K. . Dept. of Production Systems Engineering)

    1993-06-01

    A numerical model is developed for quantitatively analyzing combined conductive and radiative heat transfer in concentric annular packed beds. A packed bed is considered to be a continuous medium for heat transfer, but the porosity distribution within a packed bed is taken into account. To examine the validity of the proposed model, combined conductive and radiative heat transfer through annular packed beds of cordierite or porcelain beads is analyzed numerically using finite differences under conditions corresponding to heat transfer experiments of these packed beds. The resultant temperature profiles and heat transfer characteristics are compared with the experimental results.

  7. Financial accounting for radiology executives.

    PubMed

    Seidmann, Abraham; Mehta, Tushar

    2005-03-01

    The authors review the role of financial accounting information from the perspective of a radiology executive. They begin by introducing the role of pro forma statements. They discuss the fundamental concepts of accounting, including the matching principle and accrual accounting. The authors then explore the use of financial accounting information in making investment decisions in diagnostic medical imaging. The paper focuses on critically evaluating the benefits and limitations of financial accounting for decision making in a radiology practice.

  8. Diffraction patterns from multiple tilted laser apertures: numerical analysis

    NASA Astrophysics Data System (ADS)

    Kovalev, Anton V.; Polyakov, Vadim M.

    2016-03-01

    We propose a Rayleigh-Sommerfeld based method for numerical calculation of multiple tilted apertures near and far field diffraction patterns. Method is based on iterative procedure of fast Fourier transform based circular convolution of the initial field complex amplitudes distribution and impulse response function modified in order to account aperture and observation planes mutual tilt. The method is computationally efficient and has good accordance with the results of experimental diffraction patterns and can be applied for analysis of spatial noises occurring in master oscillator power amplifier laser systems. The example of diffraction simulation for a Phobos-Ground laser rangefinder amplifier is demonstrated.

  9. Automated attendance accounting system

    NASA Technical Reports Server (NTRS)

    Chapman, C. P. (Inventor)

    1973-01-01

    An automated accounting system useful for applying data to a computer from any or all of a multiplicity of data terminals is disclosed. The system essentially includes a preselected number of data terminals which are each adapted to convert data words of decimal form to another form, i.e., binary, usable with the computer. Each data terminal may take the form of a keyboard unit having a number of depressable buttons or switches corresponding to selected data digits and/or function digits. A bank of data buffers, one of which is associated with each data terminal, is provided as a temporary storage. Data from the terminals is applied to the data buffers on a digit by digit basis for transfer via a multiplexer to the computer.

  10. Computerized classified document accountability

    SciTech Connect

    Norris, C.B.; Lewin, R.

    1988-08-01

    This step-by-step procedure was established as a guideline to be used with the Savvy PC Database Program for the accountability of classified documents. Its purpose is to eventually phase out the use of logbooks for classified document tracking. The program runs on an IBM PC or compatible computer using a Bernoulli Box, a Hewlett Packard 71B Bar Code Reader, an IOMEGA Host Adapter Board for creating mirror images of data for backup purposes, and the Disk Operating System (DOS). The DOS batch files ''IN'' and ''OUT'' invoke the Savvy Databases for either entering incoming or outgoing documents. The main files are DESTRUCTION, INLOG, OUTLOG, and NAME-NUMBER. The fields in the files are Adding/Changing, Routing, Destroying, Search-Print by document identification, Search/Print Audit by bar code number, Print Holdings of a person, and Print Inventory of an office.

  11. Advanced Numerical Model for Irradiated Concrete

    SciTech Connect

    Giorla, Alain B.

    2015-03-01

    In this report, we establish a numerical model for concrete exposed to irradiation to address these three critical points. The model accounts for creep in the cement paste and its coupling with damage, temperature and relative humidity. The shift in failure mode with the loading rate is also properly represented. The numerical model for creep has been validated and calibrated against different experiments in the literature [Wittmann, 1970, Le Roy, 1995]. Results from a simplified model are shown to showcase the ability of numerical homogenization to simulate irradiation effects in concrete. In future works, the complete model will be applied to the analysis of the irradiation experiments of Elleuch et al. [1972] and Kelly et al. [1969]. This requires a careful examination of the experimental environmental conditions as in both cases certain critical information are missing, including the relative humidity history. A sensitivity analysis will be conducted to provide lower and upper bounds of the concrete expansion under irradiation, and check if the scatter in the simulated results matches the one found in experiments. The numerical and experimental results will be compared in terms of expansion and loss of mechanical stiffness and strength. Both effects should be captured accordingly by the model to validate it. Once the model has been validated on these two experiments, it can be applied to simulate concrete from nuclear power plants. To do so, the materials used in these concrete must be as well characterized as possible. The main parameters required are the mechanical properties of each constituent in the concrete (aggregates, cement paste), namely the elastic modulus, the creep properties, the tensile and compressive strength, the thermal expansion coefficient, and the drying shrinkage. These can be either measured experimentally, estimated from the initial composition in the case of cement paste, or back-calculated from mechanical tests on concrete. If some

  12. Accounting for Imperfect Detection in Ecology: A Quantitative Review

    PubMed Central

    Kellner, Kenneth F.; Swihart, Robert K.

    2014-01-01

    Detection in studies of species abundance and distribution is often imperfect. Assuming perfect detection introduces bias into estimation that can weaken inference upon which understanding and policy are based. Despite availability of numerous methods designed to address this assumption, many refereed papers in ecology fail to account for non-detection error. We conducted a quantitative literature review of 537 ecological articles to measure the degree to which studies of different taxa, at various scales, and over time have accounted for imperfect detection. Overall, just 23% of articles accounted for imperfect detection. The probability that an article incorporated imperfect detection increased with time and varied among taxa studied; studies of vertebrates were more likely to incorporate imperfect detection. Among articles that reported detection probability, 70% contained per-survey estimates of detection that were less than 0.5. For articles in which constancy of detection was tested, 86% reported significant variation. We hope that our findings prompt more ecologists to consider carefully the detection process when designing studies and analyzing results, especially for sub-disciplines where incorporation of imperfect detection in study design and analysis so far has been lacking. PMID:25356904

  13. The microphysics of accountability.

    PubMed

    Wieser, Bernhard

    2011-05-01

    How is it possible to deploy the law to create and perform accountability? To answer this question, I address the argumentative function of the law in order to legitimize genetic medicine. Using interview data, I will in particular elaborate on how medical experts strive to convince interviewing social scientists that their own professional action is above all ethical reproach. For this purpose, medical experts capitalize on the law in specific ways. It is the aim of this article to expound exactly how this happens during qualitative research interviews. The analysis of the interview data is informed by the works of Sheila Jasanoff and Michel Foucault. The former provides an instructive conceptual background for demonstrating how the law serves as an important element of accountability practices. The latter is known for his plea not to understand the law in repressive terms. Accordingly, the law does not prohibit specific medical practices, but in a specific sense it rather makes medical practice socially robust. Based on qualitative analysis of interview data, I conclude that referring to the law allows experts of genetic medicine to evade engaging with ethical and social aspects of their work. The law was rhetorically utilized to bring a discussion on such issues to a communicative closure. For that purpose, the existence of the law was presented as proof that undesirable practices would not be possible and consequently further discussions of the matter would be unnecessary. The law allows medical experts to transfer ethical problems to other places and actors and also to promote their professional interests.

  14. Newest insights from MHD numerical modeling of Pulsar Wind Nebulae

    NASA Astrophysics Data System (ADS)

    Olmi, B.; Del Zanna, L.; Amato, E.; Bucciantini, N.; Bandiera, R.

    2016-06-01

    Numerical MHD models are considered very successful in accounting for many of the observed properties of Pulsar Wind Nebulae (PWNe), especially those concerning the high energy emission morphology and the inner nebula dynamics. Although PWNe are known to be among the most powerful accelerators in nature, producing particles up to PeV energies, the mechanisms responsible of such an efficient acceleration are still a deep mystery. Indeed, these processes take place in one of the most hostile environment for particle acceleration: the relativistic and highly magnetized termination shock of the pulsar wind. The newest results from numerical simulations of the Crab Nebula, the PWN prototype, will be presented, with special attention to the problem of particle acceleration. In particular it will be shown how a multi-wavelengths analysis of the wisps properties can be used to constrain the particle acceleration mechanisms working at the Crab's termination shock, by identifying the particle acceleration site at the shock front.

  15. Accounting for results: how conservation organizations report performance information.

    PubMed

    Rissman, Adena R; Smail, Robert

    2015-04-01

    Environmental program performance information is in high demand, but little research suggests why conservation organizations differ in reporting performance information. We compared performance measurement and reporting by four private-land conservation organizations: Partners for Fish and Wildlife in the US Fish and Wildlife Service (national government), Forest Stewardship Council-US (national nonprofit organization), Land and Water Conservation Departments (local government), and land trusts (local nonprofit organization). We asked: (1) How did the pattern of performance reporting relationships vary across organizations? (2) Was political conflict among organizations' principals associated with greater performance information? and (3) Did performance information provide evidence of program effectiveness? Based on our typology of performance information, we found that most organizations reported output measures such as land area or number of contracts, some reported outcome indicators such as adherence to performance standards, but few modeled or measured environmental effects. Local government Land and Water Conservation Departments reported the most types of performance information, while local land trusts reported the fewest. The case studies suggest that governance networks influence the pattern and type of performance reporting, that goal conflict among principles is associated with greater performance information, and that performance information provides unreliable causal evidence of program effectiveness. Challenging simple prescriptions to generate more data as evidence, this analysis suggests (1) complex institutional and political contexts for environmental program performance and (2) the need to supplement performance measures with in-depth evaluations that can provide causal inferences about program effectiveness. PMID:25549998

  16. Accounting for results: how conservation organizations report performance information.

    PubMed

    Rissman, Adena R; Smail, Robert

    2015-04-01

    Environmental program performance information is in high demand, but little research suggests why conservation organizations differ in reporting performance information. We compared performance measurement and reporting by four private-land conservation organizations: Partners for Fish and Wildlife in the US Fish and Wildlife Service (national government), Forest Stewardship Council-US (national nonprofit organization), Land and Water Conservation Departments (local government), and land trusts (local nonprofit organization). We asked: (1) How did the pattern of performance reporting relationships vary across organizations? (2) Was political conflict among organizations' principals associated with greater performance information? and (3) Did performance information provide evidence of program effectiveness? Based on our typology of performance information, we found that most organizations reported output measures such as land area or number of contracts, some reported outcome indicators such as adherence to performance standards, but few modeled or measured environmental effects. Local government Land and Water Conservation Departments reported the most types of performance information, while local land trusts reported the fewest. The case studies suggest that governance networks influence the pattern and type of performance reporting, that goal conflict among principles is associated with greater performance information, and that performance information provides unreliable causal evidence of program effectiveness. Challenging simple prescriptions to generate more data as evidence, this analysis suggests (1) complex institutional and political contexts for environmental program performance and (2) the need to supplement performance measures with in-depth evaluations that can provide causal inferences about program effectiveness.

  17. Accounting for Results: How Conservation Organizations Report Performance Information

    NASA Astrophysics Data System (ADS)

    Rissman, Adena R.; Smail, Robert

    2015-04-01

    Environmental program performance information is in high demand, but little research suggests why conservation organizations differ in reporting performance information. We compared performance measurement and reporting by four private-land conservation organizations: Partners for Fish and Wildlife in the US Fish and Wildlife Service (national government), Forest Stewardship Council—US (national nonprofit organization), Land and Water Conservation Departments (local government), and land trusts (local nonprofit organization). We asked: (1) How did the pattern of performance reporting relationships vary across organizations? (2) Was political conflict among organizations' principals associated with greater performance information? and (3) Did performance information provide evidence of program effectiveness? Based on our typology of performance information, we found that most organizations reported output measures such as land area or number of contracts, some reported outcome indicators such as adherence to performance standards, but few modeled or measured environmental effects. Local government Land and Water Conservation Departments reported the most types of performance information, while local land trusts reported the fewest. The case studies suggest that governance networks influence the pattern and type of performance reporting, that goal conflict among principles is associated with greater performance information, and that performance information provides unreliable causal evidence of program effectiveness. Challenging simple prescriptions to generate more data as evidence, this analysis suggests (1) complex institutional and political contexts for environmental program performance and (2) the need to supplement performance measures with in-depth evaluations that can provide causal inferences about program effectiveness.

  18. Numerical studies of dilute and dense spray characteristics

    NASA Technical Reports Server (NTRS)

    Kim, Y. M.; Shang, H. M.; Chen, C. P.; Ziebarth, J. P.; Wang, T. S.

    1992-01-01

    Several issues involving the improvement of physical submodels and the computational efficiency in modeling dilute and dense spray combustion are discussed. First, the implementations of a dispersion width approach accounting for turbulent dispersion within each computational parcel is discussed. This is essentially a statistical transport model and the testings of this model confirm the capability of accurately representing dispersion in nearly-homogeneous and inhomogeneous turbulent flows with improved efficiency over the delta function stochastic separated flow model. To account for the dense spray effects, an existing drop collision and coalescence model and a Taylor analogy breakup (TAB) model were employed. These models were incorporated into a state-of-the-art multiphase all-speed transient flow solution procedure. Several examples including nonevaporating, evaporating, and burning dense spray cases were studied. The numerical results show reasonably good comparisons with available experimental data in terms of spray penetration, drop sizes, and overall configuration of a spray flame.

  19. The Impact of a Participant-Based Accounting Cycle Course on Student Performance in Intermediate Financial Accounting I

    ERIC Educational Resources Information Center

    Siagian, Ferdinand T.; Khan, Mohammad

    2016-01-01

    The authors investigated whether students in an Intermediate Financial Accounting I course who took a 1-credit, participant-based accounting cycle course performed better than students who did not take the accounting cycle course. Results indicate a higher likelihood of earning a better grade for students who took the accounting cycle course even…

  20. On the structure of gaseous confined laminar diffusion flames: Numerical investigation

    NASA Technical Reports Server (NTRS)

    Mawid, M. A.; Bulzan, D. L.; Aggarwal, S. K.

    1993-01-01

    The structure and characteristics of gaseous confined laminar diffusion flames are investigated by numerically solving the time-dependent two-dimensional axisymmetric conservation equations. The numerical model accounts for the important chemical and physical processes involved, including axial diffusion, viscous effects, radial convection, and finite-rate chemistry. The numerical results clearly show that the flame has a finite thickness and leakage of fuel vapor into the flame zone is possible. The effect of heat release is found to induce some radial flow. Predicted flame shape and dimensions are compared to the classical Burke-Schumann flame. The numerically calculated flame is observed to be about 15 percent taller and 5 percent narrower than that of the Burke-Schumann solution under the same conditions.

  1. Accounting Issues: An Essay Series. Part II--Accounts Receivable

    ERIC Educational Resources Information Center

    Laux, Judith A.

    2007-01-01

    This is the second in a series of articles designed to help academics refocus the introductory accounting course on the theoretical underpinnings of accounting. Intended as a supplement for the principles course, this article connects the asset Accounts Receivable to the essential theoretical constructs, discusses the inherent tradeoffs and…

  2. Solving Accounting Problems: Differences between Accounting Experts and Novices.

    ERIC Educational Resources Information Center

    Marshall, P. Douglas

    2002-01-01

    Performance of 90 accounting experts (faculty and practitioners) and 60 novices (senior accounting majors) was compared. Experts applied more accounting principles to solving problems. There were no differences in types of principles applied and no correlation between (1) principles applied and number of breadth comments or (2) importance placed…

  3. Keeping Public Officials Accountable through Dialogue: Resolving the Accountability Paradox.

    ERIC Educational Resources Information Center

    Roberts, Nancy C.

    2002-01-01

    Discusses Harmon's Accountability Paradox in relation to the accountability of public officials. Promotes the use of dialogue because its advantage outweighs its cost as a mechanism of accountability when officials confront problems that defy definition and solution and when traditional solution methods have failed. (Contains 54 references.) (JOW)

  4. 18 CFR 367.9040 - Account 904, Uncollectible accounts.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Account 904, Uncollectible accounts. 367.9040 Section 367.9040 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  5. 18 CFR 367.9040 - Account 904, Uncollectible accounts.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Account 904, Uncollectible accounts. 367.9040 Section 367.9040 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  6. 18 CFR 367.1420 - Account 142, Customer accounts receivable.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Account 142, Customer accounts receivable. 367.1420 Section 367.1420 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  7. 18 CFR 367.9040 - Account 904, Uncollectible accounts.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Account 904, Uncollectible accounts. 367.9040 Section 367.9040 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  8. 18 CFR 367.1430 - Account 143, Other accounts receivable.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Account 143, Other accounts receivable. 367.1430 Section 367.1430 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  9. 18 CFR 367.1840 - Account 184, Clearing accounts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Account 184, Clearing accounts. 367.1840 Section 367.1840 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT...

  10. 18 CFR 367.9040 - Account 904, Uncollectible accounts.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 18 Conservation of Power and Water Resources 1 2011-04-01 2011-04-01 false Account 904, Uncollectible accounts. 367.9040 Section 367.9040 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  11. 18 CFR 367.1840 - Account 184, Clearing accounts.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Account 184, Clearing accounts. 367.1840 Section 367.1840 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT...

  12. 18 CFR 367.1430 - Account 143, Other accounts receivable.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Account 143, Other accounts receivable. 367.1430 Section 367.1430 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  13. 18 CFR 367.1840 - Account 184, Clearing accounts.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Account 184, Clearing accounts. 367.1840 Section 367.1840 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY... POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES SUBJECT...

  14. 18 CFR 367.1420 - Account 142, Customer accounts receivable.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Account 142, Customer accounts receivable. 367.1420 Section 367.1420 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  15. 18 CFR 367.1430 - Account 143, Other accounts receivable.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Account 143, Other accounts receivable. 367.1430 Section 367.1430 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  16. 18 CFR 367.1420 - Account 142, Customer accounts receivable.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 18 Conservation of Power and Water Resources 1 2013-04-01 2013-04-01 false Account 142, Customer accounts receivable. 367.1420 Section 367.1420 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  17. 18 CFR 367.1420 - Account 142, Customer accounts receivable.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Account 142, Customer accounts receivable. 367.1420 Section 367.1420 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  18. 18 CFR 367.1430 - Account 143, Other accounts receivable.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 18 Conservation of Power and Water Resources 1 2014-04-01 2014-04-01 false Account 143, Other accounts receivable. 367.1430 Section 367.1430 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  19. 18 CFR 367.1430 - Account 143, Other accounts receivable.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 18 Conservation of Power and Water Resources 1 2012-04-01 2012-04-01 false Account 143, Other accounts receivable. 367.1430 Section 367.1430 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  20. 18 CFR 367.9040 - Account 904, Uncollectible accounts.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Account 904, Uncollectible accounts. 367.9040 Section 367.9040 Conservation of Power and Water Resources FEDERAL ENERGY..., FEDERAL POWER ACT AND NATURAL GAS ACT UNIFORM SYSTEM OF ACCOUNTS FOR CENTRALIZED SERVICE COMPANIES...

  1. Numerical friction experiments of heterogeneous fault with controlling shear stress by means of earthquake sequence simulations: Preliminary results on the relation between cm-scale and km-scale friction laws

    NASA Astrophysics Data System (ADS)

    Noda, H.; Hori, T.

    2014-12-01

    The scale effect of the friction law is crucial in connecting field observations, laboratory experiments, and natural fault behaviors. Here we present our recent study towards understanding of the scale effect of the friction law. The fault friction law is usually studied in laboratory experiments for cm-scale specimens, and one of the prominent problems is its direct applicability to the large-scale behavior. Small repeating earthquakes (repeaters) may be a realization of heterogeneous frictional property on faults, which were modeled by rate-weakening patches embedded in a rate-strengthening fault [e.g., Chen and Lapusta, 2009]. After the 2011 Tohoku-oki earthquake, so many repeaters were found in the Tohoku subduction zone [e.g., Kato and Igarashi, 2012]. But it is quite difficult to numerically resolve them in a large-scale simulation of the whole subduction zone, which is demanded for potential disaster mitigation. Then, it is important to investigate a spatiotemporally coarse-grained friction law of a fault region including unstable inclusions. We hypothesized that each point on a fault obeys the cm-scale friction law (the rate-state friction law in the aging law formulation) with sub-mm state evolution distance L, and assumed a rate-weakening circular patch (80 m diameter) which generates repeating events. We set 256 m periodicity along the fault, and conducted dynamic earthquake sequence simulations [e.g., Liu and Lapusta, 2009] by driving the system by far field stress τ0. We did not prescribe the long term slip rate by setting a region of constant slip rate as is done in previous studies. Those simulations can be seen as numerical friction experiments with controlling the shear stress and observing the slip rate. The macroscopic steady-state can be explained by a logarithmic law, with the frictional resistance slightly smaller and the rate-dependency slightly more rate-strengthening than the spatial average. The transient behavior on a step in τ0 can be

  2. Application of environmental accounting to pollution prevention

    SciTech Connect

    Del Mar, R.A.

    1997-08-19

    Environmental accounting represents a major paradigm shift in the way most companies account for costs and benefits. However, it is a change that must be made if pollution prevention is to become institutionalized into the corporate and government mainstream. Pollution prevention investments must be justified on an economic basis; without environmental accounting tools, pollution prevention investments cannot show their true profitability. This is because traditional accounting methods only track billable costs, thus ignoring some of the major benefits of pollution prevention investments, which are indirect savings resulting from a lessening of a company`s regulatory compliance burden and present and future liabilities. This paper discusses how to apply environmental accounting principles to pollution prevention assessments to improve the outcome of profitability analyses.

  3. NASA Accountability Report

    NASA Technical Reports Server (NTRS)

    1997-01-01

    NASA is piloting fiscal year (FY) 1997 Accountability Reports, which streamline and upgrade reporting to Congress and the public. The document presents statements by the NASA administrator, and the Chief Financial Officer, followed by an overview of NASA's organizational structure and the planning and budgeting process. The performance of NASA in four strategic enterprises is reviewed: (1) Space Science, (2) Mission to Planet Earth, (3) Human Exploration and Development of Space, and (4) Aeronautics and Space Transportation Technology. Those areas which support the strategic enterprises are also reviewed in a section called Crosscutting Processes. For each of the four enterprises, there is discussion about the long term goals, the short term objectives and the accomplishments during FY 1997. The Crosscutting Processes section reviews issues and accomplishments relating to human resources, procurement, information technology, physical resources, financial management, small and disadvantaged businesses, and policy and plans. Following the discussion about the individual areas is Management's Discussion and Analysis, about NASA's financial statements. This is followed by a report by an independent commercial auditor and the financial statements.

  4. Spills, drills, and accountability

    SciTech Connect

    1993-12-31

    NRDC seeks preventive approaches to oil pollution on U.S. coasts. The recent oil spills in Spain and Scotland have highlighted a fact too easy to forget in a society that uses petroleum every minute of every day: oil is profoundly toxic. One tiny drop on a bald eagle`s egg has been known to kill the embryo inside. Every activity involving oil-drilling for it, piping it, shipping it-poses risks that must be taken with utmost caution. Moreover, oil production is highly polluting. It emits substantial air pollution, such as nitrogen oxides that can form smog and acid rain. The wells bring up great quantities of toxic waste: solids, liquids and sludges often contaminated by oil, toxic metals, or even radioactivity. This article examines the following topics focusing on oil pollution control and prevention in coastal regions of the USA: alternate energy sources and accountability of pollutor; ban on offshore drilling as exemplified by the energy policy act; tanker free zones; accurate damage evaluations. Policy of the National Resource Defence Council is articulated.

  5. Holding services to account

    PubMed Central

    Clegg, J

    2008-01-01

    Background Recently, the frequency of audit inspections of health services for people with intellectual disability (ID) in the UK has increased, from occasional inquiries to a systematic audit of all services. From 2008, a process of continuous audit ‘surveillance’ of specialist health services is to be introduced. Similar regimes of inspection are in place for social care services. Aim To explore the conceptual positions which inform audit, through detailed examination of the investigation into the learning disability service at Sutton and Merton. Findings Audit is distinct from evaluation because it neither provides opportunities for service staff to give an account of their work nor represents a search for knowledge. Audit investigates adherence to government policy. In ID, audits measure aspirations derived from normalisation, despite research showing that some of these aspirations have not been achieved by any service. As audit consumes significant public resource, it is questionable whether the dominant finding of the Healthcare Commission's investigation into Sutton and Merton, that the ID service was chronically under-funded, represents value for money. Discussion and conclusions While basic checks on minimum standards will always be necessary, service excellence requires not audit but research-driven evaluation. Audits inhibit rather than open-up debate about improving support to people with ID. They impose an ideology, squander resource, and demoralise carers and staff. Evaluations challenge the implicit management-versus-professional binary enacted by audit, and can inform new care systems which make effective use of all those engaged with people with ID. PMID:18498335

  6. High-resolution numerical simulation and analysis of Mach reflection structures in detonation waves in low-pressure H2 - O2 - Ar mixtures: a summary of results obtained with the adaptive mesh refinement framework AMROC

    SciTech Connect

    Deiterding, Ralf

    2011-01-01

    Numerical simulation can be key to the understanding of the multi-dimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the non-equilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniques in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, i.e. under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis and a diagram of the transition boundaries between possible Mach reflection structures is constructed.

  7. High-Resolution Numerical Simulation and Analysis of Mach Reflection Structures in Detonation Waves in Low-Pressure H 2 –O 2 –Ar Mixtures: A Summary of Results Obtained with the Adaptive Mesh Refinement Framework AMROC

    DOE PAGES

    Deiterding, Ralf

    2011-01-01

    Numerical simulation can be key to the understanding of the multidimensional nature of transient detonation waves. However, the accurate approximation of realistic detonations is demanding as a wide range of scales needs to be resolved. This paper describes a successful solution strategy that utilizes logically rectangular dynamically adaptive meshes. The hydrodynamic transport scheme and the treatment of the nonequilibrium reaction terms are sketched. A ghost fluid approach is integrated into the method to allow for embedded geometrically complex boundaries. Large-scale parallel simulations of unstable detonation structures of Chapman-Jouguet detonations in low-pressure hydrogen-oxygen-argon mixtures demonstrate the efficiency of the described techniquesmore » in practice. In particular, computations of regular cellular structures in two and three space dimensions and their development under transient conditions, that is, under diffraction and for propagation through bends are presented. Some of the observed patterns are classified by shock polar analysis, and a diagram of the transition boundaries between possible Mach reflection structures is constructed.« less

  8. Accountability report - fiscal year 1997

    SciTech Connect

    1998-04-01

    This document contains the US NRC`s accountability report for fiscal year 1997. Topics include uses of funds, financial condition, program performance, management accountability, and the audited financial statement.

  9. How to Professionalize Accounting Programs

    ERIC Educational Resources Information Center

    Allyn, Robert G.

    1977-01-01

    The author, a certified public accountant on the State Board for Public Accountancy of New York, Discusses education and training programs to "professionalize" accounting, particularly the need for innovative learning modules that integrate the traditional sequence of courses in baccalaureate programs. (MF)

  10. Standardized Testing and School Accountability

    ERIC Educational Resources Information Center

    Wiliam, Dylan

    2010-01-01

    This article explores the use of standardized tests to hold schools accountable. The history of testing for accountability is reviewed, and it is shown that currently between-school differences account for less than 10% of the variance in student scores, in part because the progress of individuals is small compared to the spread of achievement…

  11. Vocational Accounting and Computing Programs.

    ERIC Educational Resources Information Center

    Avani, Nathan T.

    1986-01-01

    Describes an "Accounting and Computing" program in Michigan that emphasizes computerized accounting procedures. This article describes the program curriculum and duty areas (such as handling accounts receivable), presents a list of sample tasks in each duty area, and specifies components of each task. Computer equipment necessary for this program…

  12. Symphony Time Accounting Resource (STAR)

    SciTech Connect

    Newfield, S.E.; Booth, J.W.; Redman, D.L.

    1986-05-01

    The Symphony Time Accounting Resource, a new time accounting system, that can be run on personal computers instead of computer mainframes is described. This new system is useful for organizations that do work under several job order numbers and/or accounting codes and could also be adapted for use by organizations on the recharge system. 1 fig., 2 tabs.

  13. An Accounting Writing Proficiency Survey

    ERIC Educational Resources Information Center

    Firch, Tim; Campbell, Annhenrie; Filling, Steven; Lindsay, David H.

    2011-01-01

    Although there has been much discussion about improving college student writing with college-level courses, little is known about how accounting programs, in particular, are addressing the writing proficiency challenge. This study surveys the 852 accounting programs in the United States to identify the frequency and types of accounting writing…

  14. Mastering the Vocabulary of Accounting.

    ERIC Educational Resources Information Center

    Tischler, Helene

    Developed for use by students in an introductory accounting course, these learning modules deal with mastering the vocabulary of accounting. Focus of the modules is on vocabulary appearing in the first six chapters of the text, "Accounting Principles" by Niswonger and Fess. Covered in the individual modules are the following topics: discovering…

  15. 46 CFR Sec. 5 - Accounting.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 8 2010-10-01 2010-10-01 false Accounting. Sec. 5 Section 5 Shipping MARITIME... Sec. 5 Accounting. The General Agent shall record the amounts of compensation paid from the NSA... Accounting Office, at which time the Maritime Administration will take custody of the records....

  16. Contamination of Current Accountability Systems

    ERIC Educational Resources Information Center

    McGill-Franzen, Anne; Allington, Richard

    2006-01-01

    As public employees, educators should expect to be held accountable for their use of public funds. Nonetheless, the various state governments and now the U.S. Department of Education have implemented high-stakes achievement testing as the nearly singular approach to accountability. While these accountability efforts vary in a number of ways,…

  17. Numerical modeling of the spring thermal bar and pollutant transport in a large lake

    NASA Astrophysics Data System (ADS)

    Tsydenov, Bair O.; Kay, Anthony; Starchenko, Alexander V.

    2016-08-01

    The spring riverine thermal bar phenomenon is investigated numerically on an example of Lake Baikal, and the spread of pollutants coming from the Selenga River is forecast using the 2.5 D non-hydrostatic model in the Boussinesq approximation. This hydrodynamic model takes into account the diurnal variability of the heat fluxes on the lake surface and the effects of wind and the Earth's rotation. The results of numerical modeling show that the variability of the total heat flux over 24 h plays a significant role in the variation of the thermal bar movement rate that contributes to the rapid mixing of impurities entering with river water.

  18. Numerical comparison between relaxation and nonlinear equilibrium models. Application to chemical engineering

    NASA Astrophysics Data System (ADS)

    James, F.; Postel, M.; Sepúlveda, M.

    2000-04-01

    A model to take into account the finite exchange kinetic for the equilibrium between phases in the chromatography experiment is studied. The resulting hyperbolic system with a nonlinear relaxation term is then formally treated with a Chapman-Enskog type expansion. A first order correction to the classical quasilinear hyperbolic model is derived which consists of a nonlinear diffusion term. Numerical schemes for both models - relaxed and parabolic - are then tested and compared for different initial and boundary values. A range of validity for the first order approximation is obtained through numerical simulations where its computational performance indicates that it should be advantageously used.

  19. Direct numerical simulations of a reacting turbulent mixing layer by a pseudospectral-spectral element method

    NASA Technical Reports Server (NTRS)

    Mcmurtry, Patrick A.; Givi, Peyman

    1992-01-01

    An account is given of the implementation of the spectral-element technique for simulating a chemically reacting, spatially developing turbulent mixing layer. Attention is given to experimental and numerical studies that have investigated the development, evolution, and mixing characteristics of shear flows. A mathematical formulation is presented of the physical configuration of the spatially developing reacting mixing layer, in conjunction with a detailed representation of the spectral-element method's application to the numerical simulation of mixing layers. Results from 2D and 3D calculations of chemically reacting mixing layers are given.

  20. 12 CFR 390.281 - Account.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 5 2014-01-01 2014-01-01 false Account. 390.281 Section 390.281 Banks and... Associations § 390.281 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or United States...

  1. 12 CFR 161.2 - Account.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 1 2014-01-01 2014-01-01 false Account. 161.2 Section 161.2 Banks and Banking... ASSOCIATIONS § 161.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or United States...

  2. 12 CFR 561.2 - Account.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true Account. 561.2 Section 561.2 Banks and Banking... SAVINGS ASSOCIATIONS § 561.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or...

  3. 12 CFR 161.2 - Account.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 1 2012-01-01 2012-01-01 false Account. 161.2 Section 161.2 Banks and Banking... ASSOCIATIONS § 161.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or United States...

  4. 12 CFR 561.2 - Account.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 6 2013-01-01 2012-01-01 true Account. 561.2 Section 561.2 Banks and Banking... SAVINGS ASSOCIATIONS § 561.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or...

  5. 12 CFR 561.2 - Account.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Account. 561.2 Section 561.2 Banks and Banking... SAVINGS ASSOCIATIONS § 561.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or...

  6. 12 CFR 161.2 - Account.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 1 2013-01-01 2013-01-01 false Account. 161.2 Section 161.2 Banks and Banking... ASSOCIATIONS § 161.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or United States...

  7. 12 CFR 561.2 - Account.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false Account. 561.2 Section 561.2 Banks and Banking... SAVINGS ASSOCIATIONS § 561.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or...

  8. 12 CFR 390.281 - Account.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 5 2013-01-01 2013-01-01 false Account. 390.281 Section 390.281 Banks and... Associations § 390.281 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or United States...

  9. 12 CFR 390.281 - Account.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 5 2012-01-01 2012-01-01 false Account. 390.281 Section 390.281 Banks and... Associations § 390.281 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or United States...

  10. 12 CFR 561.2 - Account.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false Account. 561.2 Section 561.2 Banks and Banking... SAVINGS ASSOCIATIONS § 561.2 Account. The term account means any savings account, demand account, certificate account, tax and loan account, note account, United States Treasury general account or...

  11. Numerical predictions in acoustics

    NASA Technical Reports Server (NTRS)

    Hardin, Jay C.

    1992-01-01

    Computational Aeroacoustics (CAA) involves the calculation of the sound produced by a flow as well as the underlying flowfield itself from first principles. This paper describes the numerical challenges of CAA and recent research efforts to overcome these challenges. In addition, it includes the benefits of CAA in removing restrictions of linearity, single frequency, constant parameters, low Mach numbers, etc. found in standard acoustic analyses as well as means for evaluating the validity of these numerical approaches. Finally, numerous applications of CAA to both classical as well as modern problems of concern to the aerospace industry are presented.

  12. Numerical predictions in acoustics

    NASA Astrophysics Data System (ADS)

    Hardin, Jay C.

    Computational Aeroacoustics (CAA) involves the calculation of the sound produced by a flow as well as the underlying flowfield itself from first principles. This paper describes the numerical challenges of CAA and recent research efforts to overcome these challenges. In addition, it includes the benefits of CAA in removing restrictions of linearity, single frequency, constant parameters, low Mach numbers, etc. found in standard acoustic analyses as well as means for evaluating the validity of these numerical approaches. Finally, numerous applications of CAA to both classical as well as modern problems of concern to the aerospace industry are presented.

  13. Numerical solution of the time dependent neutron transport equation by the method of the characteristics

    SciTech Connect

    Talamo, Alberto

    2013-05-01

    This study presents three numerical algorithms to solve the time dependent neutron transport equation by the method of the characteristics. The algorithms have been developed taking into account delayed neutrons and they have been implemented into the novel MCART code, which solves the neutron transport equation for two-dimensional geometry and an arbitrary number of energy groups. The MCART code uses regular mesh for the representation of the spatial domain, it models up-scattering, and takes advantage of OPENMP and OPENGL algorithms for parallel computing and plotting, respectively. The code has been benchmarked with the multiplication factor results of a Boiling Water Reactor, with the analytical results for a prompt jump transient in an infinite medium, and with PARTISN and TDTORT results for cross section and source transients. The numerical simulations have shown that only two numerical algorithms are stable for small time steps.

  14. Adaptive Spontaneous Transitions between Two Mechanisms of Numerical Averaging.

    PubMed

    Brezis, Noam; Bronfman, Zohar Z; Usher, Marius

    2015-01-01

    We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two. PMID:26041580

  15. Adaptive Spontaneous Transitions between Two Mechanisms of Numerical Averaging

    PubMed Central

    Brezis, Noam; Bronfman, Zohar Z.; Usher, Marius

    2015-01-01

    We investigated the mechanism with which humans estimate numerical averages. Participants were presented with 4, 8 or 16 (two-digit) numbers, serially and rapidly (2 numerals/second) and were instructed to convey the sequence average. As predicted by a dual, but not a single-component account, we found a non-monotonic influence of set-size on accuracy. Moreover, we observed a marked decrease in RT as set-size increases and RT-accuracy tradeoff in the 4-, but not in the 16-number condition. These results indicate that in accordance with the normative directive, participants spontaneously employ analytic/sequential thinking in the 4-number condition and intuitive/holistic thinking in the 16-number condition. When the presentation rate is extreme (10 items/sec) we find that, while performance still remains high, the estimations are now based on intuitive processing. The results are accounted for by a computational model postulating population-coding underlying intuitive-averaging and working-memory-mediated symbolic procedures underlying analytical-averaging, with flexible allocation between the two. PMID:26041580

  16. Spatial–Numerical and Ordinal Positional Associations Coexist in Parallel

    PubMed Central

    Huber, Stefan; Klein, Elise; Moeller, Korbinian; Willmes, Klaus

    2016-01-01

    There is evidence for a systematic association of numbers and space. A prominent finding supporting this notion is the spatial-numerical association of response codes (SNARC) effect describing relatively faster responses to smaller numbers using a left-hand key and to larger numbers using a right-hand key. However, the assumption of the SNARC effect reflecting spatial-numerical associations was challenged recently. A working memory account was proposed suggesting that not numbers per se but their position in a memorized sequence is associated with space. Yet, there is also first evidence suggesting that this ordinal position and the SNARC effect may not be mutually exclusive. In the present study, we further examined the relationship between the ordinal position and the SNARC effect. We manipulated the number of items in the memorized ordered sequence and the number range employed. Results revealed both a significant ordinal position effect, but also a significant SNARC effect, substantiating the view that both effects are not mutually exclusive but may co-exist. Furthermore, we found that the SNARC effect was reduced when numbers ranging from 1 to 10 versus numbers ranging from 1 to 9 were employed. Thus, our results question a pure working memory account for the SNARC effect. Additionally, they highlight the critical role of the number range employed in research about the SNARC effect. PMID:27064216

  17. 77 FR 43542 - Cost Accounting Standards: Cost Accounting Standards 412 and 413-Cost Accounting Standards...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-25

    ... Harmonization Rule. The final rule was published at 76 FR 81296 on December 27, 2011. Generally, the technical... BUDGET Office of Federal Procurement Policy 48 CFR Part 9904 Cost Accounting Standards: Cost Accounting Standards 412 and 413--Cost Accounting Standards Pension Harmonization Rule AGENCY: Cost...

  18. Numerical simulations of plasmas

    SciTech Connect

    Dnestrovskii, Y.N.; Kostomarov, D.P.

    1986-01-01

    This book presents a modern, consistent, and systematic development of numerical computer simulation of plasmas in controlled thermonuclear fusion. The authors focus on recent Soviet research in mathematical modeling of Tokomak plasmas and present kinetic hydrodynamic and transport models.

  19. Rocket engine numerical simulator

    NASA Technical Reports Server (NTRS)

    Davidian, Ken

    1993-01-01

    The topics are presented in viewgraph form and include the following: a rocket engine numerical simulator (RENS) definition; objectives; justification; approach; potential applications; potential users; RENS work flowchart; RENS prototype; and conclusion.

  20. Rocket engine numerical simulation

    NASA Technical Reports Server (NTRS)

    Davidian, Ken

    1993-01-01

    The topics are presented in view graph form and include the following: a definition of the rocket engine numerical simulator (RENS); objectives; justification; approach; potential applications; potential users; RENS work flowchart; RENS prototype; and conclusions.

  1. Numerical Relativity and Astrophysics

    NASA Astrophysics Data System (ADS)

    Lehner, Luis; Pretorius, Frans

    2014-08-01

    Throughout the Universe many powerful events are driven by strong gravitational effects that require general relativity to fully describe them. These include compact binary mergers, black hole accretion, and stellar collapse, where velocities can approach the speed of light and extreme gravitational fields (ΦNewt/c2≃1) mediate the interactions. Many of these processes trigger emission across a broad range of the electromagnetic spectrum. Compact binaries further source strong gravitational wave emission that could directly be detected in the near future. This feat will open up a gravitational wave window into our Universe and revolutionize our understanding of it. Describing these phenomena requires general relativity, and—where dynamical effects strongly modify gravitational fields—the full Einstein equations coupled to matter sources. Numerical relativity is a field within general relativity concerned with studying such scenarios that cannot be accurately modeled via perturbative or analytical calculations. In this review, we examine results obtained within this discipline, with a focus on its impact in astrophysics.

  2. Numerical Techniques in Acoustics

    NASA Technical Reports Server (NTRS)

    Baumeister, K. J. (Compiler)

    1985-01-01

    This is the compilation of abstracts of the Numerical Techniques in Acoustics Forum held at the ASME's Winter Annual Meeting. This forum was for informal presentation and information exchange of ongoing acoustic work in finite elements, finite difference, boundary elements and other numerical approaches. As part of this forum, it was intended to allow the participants time to raise questions on unresolved problems and to generate discussions on possible approaches and methods of solution.

  3. FORTRAN manpower account program

    NASA Technical Reports Server (NTRS)

    Strand, J. N.

    1972-01-01

    Computer program for determining manpower costs for full time, part time, and contractor personnel is discussed. Twelve different tables resulting from computer output are described. Program is written in FORTRAN 4 for IBM 360/65 computer.

  4. Numerical simulation of dynamic processes in biomechanics using the grid-characteristic method

    NASA Astrophysics Data System (ADS)

    Beklemysheva, K. A.; Vasyukov, A. V.; Petrov, I. B.

    2015-08-01

    Results of the numerical simulation of mechanical processes occurring in biological tissues under dynamic actions are presented. The grid-characteristic method on unstructured grids is used to solve the system of equations of mechanics of deformable solids; this method takes into account the characteristic properties of the constitutive system of partial differential equations and produces adequate algorithms on interfaces between media and on the boundaries of integration domains.

  5. Maturity Effects on Students' Perceptions of How Accounting Scandals Impact the Accounting Profession

    ERIC Educational Resources Information Center

    Theuri, Peter; Weickgenannt, Andrea

    2008-01-01

    This study examines the impact of recent ethical scandals on business students' perceptions of the accounting profession and related regulatory reforms, and whether such perceptions may be differentiated by maturity. Student maturity is distinguished by age, class standing, and number of accounting classes taken so far. The study results are based…

  6. Numerical simulations of capillary barrier field tests

    SciTech Connect

    Morris, C.E.; Stormont, J.C.

    1997-12-31

    Numerical simulations of two capillary barrier systems tested in the field were conducted to determine if an unsaturated flow model could accurately represent the observed results. The field data was collected from two 7-m long, 1.2-m thick capillary barriers built on a 10% grade that were being tested to investigate their ability to laterally divert water downslope. One system had a homogeneous fine layer, while the fine soil of the second barrier was layered to increase its ability to laterally divert infiltrating moisture. The barriers were subjected first to constant infiltration while minimizing evaporative losses and then were exposed to ambient conditions. The continuous infiltration period of the field tests for the two barrier systems was modelled to determine the ability of an existing code to accurately represent capillary barrier behavior embodied in these two designs. Differences between the field test and the model data were found, but in general the simulations appeared to adequately reproduce the response of the test systems. Accounting for moisture retention hysteresis in the layered system will potentially lead to more accurate modelling results and is likely to be important when developing reasonable predictions of capillary barrier behavior.

  7. Ethical accountability in the cyberspace

    SciTech Connect

    Nance, K.L.; Strohmaier, M.

    1994-12-31

    Conformance with ethical behavior consists of adherence to the standards of conduct for any given group. When standards are not formalized, there can exist ethical disparity from which many diverse problems can result. These problems are especially evident in the cyberspace. Within the cyberspace, the {open_quote}given group{close_quote} is culturally and ethnically diverse. As such, it $8 difficult to hold the individuals to a nonformalized set of standards. Several important issues need to be addressed in order to balance each individual`s dual needs for freedom of expression and protection in the cyberspace. These issues include development of formalized standards, a general protocol for cross- cultural interaction, and ethical accountability.

  8. The Cyclical Relationship Approach in Teaching Basic Accounting Principles.

    ERIC Educational Resources Information Center

    Golen, Steven

    1981-01-01

    Shows how teachers can provide a more meaningful presentation of various accounting principles by illustrating them through a cyclical relationship approach. Thus, the students see the entire accounting relationship as a result of doing business. (CT)

  9. Theoretical and Numerical Investigations on Shallow Tunnelling in Unsaturated Soils

    NASA Astrophysics Data System (ADS)

    Soranzo, Enrico; Wu, Wei

    2013-04-01

    Excavation of shallow tunnels with the New Austrian Tunnelling Method (NATM) requires proper assessing of the tunnel face stability, to enable an open-face excavation, and the estimation of the correspondent surface settlements. Soils in a partially saturated condition exhibit a higher cohesion than in a fully saturated state, which can be taken into account when assessing the stability of the tunnel face. For the assessment of the face support pressure, different methods are used in engineering practice, varying from simple empirical and analytical formulations to advanced finite element analysis. Such procedures can be modified to account for the unsaturated state of soils. In this study a method is presented to incorporate the effect of partial saturation in the numerical analysis. The results are then compared with a simple analytical formulation derived from parametric studies. As to the numerical analysis, the variation of cohesion and of Young's modulus with saturation can be considered when the water table lies below the tunnel in a soil exhibiting a certain capillary rise, so that the tunnel is driven in a partially saturated layer. The linear elastic model with Mohr-Coulomb failure criterion can be extended to partially saturated states and calibrated with triaxial tests on unsaturated. In order to model both positive and negative pore water pressure (suction), Bishop's effective stress is incorporated into Mohr-Coulomb's failure criterion. The effective stress parameter in Bishop's formulation is related to the degree of saturation as suggested by Fredlund. If a linear suction distribution is assumed, the degree of saturation can be calculated from the Soil Water Characteristic Curve (SWCC). Expressions exist that relate the Young's modulus of unsaturated soils to the net mean stress and the matric suction. The results of the numerical computation can be compared to Vermeer & Ruse's closed-form formula that expresses the limit support pressure of the

  10. Numerical modeling of radionuclide migration through a borehole disposal site.

    PubMed

    Yeboah, Serwaa; Akiti, Thomas T; Fletcher, John J

    2014-01-01

    The migration of radionuclides from a borehole repository located about 20 km from the Akwapim fault line which lies in an area of high seismicity was analyzed for some selected radionuclides. In the event of a seismic activity, fractures and faults could be rejuvenated or initiated resulting in container failure leading to the release of radionuclides. A numerical model was solved using a two-dimensional finite element code (Comsol Multiphysics) by taking into account the effect of heterogeneities. Results showed that, the fractured medium created preferential pathways indicating that, fault zones generated potential paths for released radionuclides from a radioactive waste repository. The results obtained showed that variations in hydraulic conductivity as a result of the heterogeneity considered within the domain significantly affected the direction of flow.

  11. Accountability that Counts

    ERIC Educational Resources Information Center

    Milner, Joseph; Coker, Connie Pullum; Buchanan, Christy; Newsome, Debbie; Milner, Jonathan; Allen, Rodney; Williams, Melissa

    2009-01-01

    The North Carolina Governor's School offers a six-week residential summer program for four hundred academically talented rising juniors. This article measures the school's impact on these students in four fundamental areas: cognitive maturity, moral reasoning, personal learning style, and projections for the future. The results showed that…

  12. Spurious Numerical Solutions Of Differential Equations

    NASA Technical Reports Server (NTRS)

    Lafon, A.; Yee, H. C.

    1995-01-01

    Paper presents detailed study of spurious steady-state numerical solutions of differential equations that contain nonlinear source terms. Main objectives of this study are (1) to investigate how well numerical steady-state solutions of model nonlinear reaction/convection boundary-value problem mimic true steady-state solutions and (2) to relate findings of this investigation to implications for interpretation of numerical results from computational-fluid-dynamics algorithms and computer codes used to simulate reacting flows.

  13. Numerical Simulations of Ion Cloud Dynamics

    NASA Astrophysics Data System (ADS)

    Sillitoe, Nicolas; Hilico, Laurent

    We explain how to perform accurate numerical simulations of ion cloud dynamics by discussing the relevant orders of magnitude of the characteristic times and frequencies involved in the problem and the computer requirement with respect to the ion cloud size. We then discuss integration algorithms and Coulomb force parallelization. We finally explain how to take into account collisions, cooling laser interaction and chemical reactions in a Monte Carlo approach and discuss how to use random number generators to that end.

  14. Requirements definition by numerical simulation

    NASA Astrophysics Data System (ADS)

    Hickman, James J.; Kostas, Chris; Tsang, Kang T.

    1994-10-01

    We are investigating the issues involved in requirements definition for narcotics interdiction: how much of a particular signature is possible, how does this amount change for different conditions, and what is the temporal relationship in various scenarios. Our approach has been to simulate numerically the conditions that arise during vapor or particulate transport. The advantages of this approach are that (1) a broad range of scenarios can be rapidly and inexpensively analyzed by simulation, and (2) simulations can display quantities that are difficult or impossible to measure. The drawback of this approach is that simulations cannot include all of the phenomena present in a real measurement, and therefore the fidelity of the simulation results is always an issue. To address this limitation, we will ultimately combine the results of numerical simulations with measurements of physical parameters for inclusion in the simulation. In this paper, we discuss these issues and how they apply to the current problems in narcotics interdictions, especially cargo containers. We also show the results of 1D and 3D numerical simulations, and compare these results with analytical solutions. The results indicate that this approach is viable. We also present data from 3D simulations of vapor transport in a loaded cargo container and some of the issues present in this ongoing work.

  15. Computing numerically the access resistance of a pore.

    PubMed

    Aguilella-Arzo, Marcel; Aguilella, Vicente M; Eisenberg, R S

    2005-06-01

    The access resistance (AR) of a channel is an important component of the conductance of ion channels, particularly in wide and short channels, where it accounts for a substantial fraction of the total resistance to the movement of ions. The AR is usually calculated by using a classical and simple expression derived by Hall from electrostatics (J.E. Hall 1975 J. Gen. Phys. 66:531-532), though other expressions, both analytical and numerical, have been proposed. Here we report some numerical results for the AR of a channel obtained by solving the Poisson-Nernst-Planck equations at the entrance of a circular pore. Agreement is found between numerical calculations and analytical results from Hall's equation for uncharged pores in neutral membranes. However, for channels embedded in charged membranes, Hall's expression overestimates the AR, which is much lower and can even be neglected in some cases. The weak dependence of AR on the pore radius for charged membranes at low salt concentration can be exploited to separate the channel and the access contributions to the measured conductance. PMID:15756588

  16. Numerical solution of High-kappa model of superconductivity

    SciTech Connect

    Karamikhova, R.

    1996-12-31

    We present formulation and finite element approximations of High-kappa model of superconductivity which is valid in the high {kappa}, high magnetic field setting and accounts for applied magnetic field and current. Major part of this work deals with steady-state and dynamic computational experiments which illustrate our theoretical results numerically. In our experiments we use Galerkin discretization in space along with Backward-Euler and Crank-Nicolson schemes in time. We show that for moderate values of {kappa}, steady states of the model system, computed using the High-kappa model, are virtually identical with results computed using the full Ginzburg-Landau (G-L) equations. We illustrate numerically optimal rates of convergence in space and time for the L{sup 2} and H{sup 1} norms of the error in the High-kappa solution. Finally, our numerical approximations demonstrate some well-known experimentally observed properties of high-temperature superconductors, such as appearance of vortices, effects of increasing the applied magnetic field and the sample size, and the effect of applied constant current.

  17. Numerical simulation of thermoacoustic response of laboratory scale premixed multi-slit burner flames

    NASA Astrophysics Data System (ADS)

    O'Brien, Adam

    Thermoacoustic instabilities are an entirely unwanted, yet nearly inevitable phenomenon occurring in many practical premixed combustors. If not properly accounted and designed for, they can incur significant increases in the development combustion systems. The fact that such unexpected issues are encountered is indicative of a fundamental lack of understanding regarding the mechanisms that drive thermoacoustic phenomena. Numerical techniques are used to characterize the thermoacoustic response of premixed multi-slit bunsen burner flames. A symmetrical representation of the multi-slit burner is used, and the transfer function is computed at several different frequencies and at three different equivalence ratios. The numerical results are then compared against experimental results in order to determine the suitability of numerical techniques for studying thermoacoustics. A fully compressible Navier-Stokes combustion solver is used in conjunction with adaptive mesh refinement (AMR) for improved resolution at the flame interface.

  18. Analytical modeling and numerical simulations of the thermal behavior of trench-isolated bipolar transistors

    NASA Astrophysics Data System (ADS)

    Marano, I.; d'Alessandro, V.; Rinaldi, N.

    2009-03-01

    The thermal behavior of trench-isolated bipolar transistors is thoroughly investigated. Fully 3D numerical simulations are performed to analyze the impact of all technological parameters of interest. Based on numerical results, a novel strategy to analytically evaluate the temperature field is proposed, which accounts for the heat propagation through the trench and the nonuniform heat flux distribution over the interface between the silicon box surrounded by trench and the underlying substrate. The resulting model is proved to compare with numerical simulations more favorably than the other approaches available from the literature. As a consequence, it can be employed for an accurate, yet fast evaluation of the thermal resistance of a trench-isolated device as well as of the temperature gradients within the silicon box.

  19. Simulation of a numerical filter for enhancing earth radiation budget measurements

    NASA Technical Reports Server (NTRS)

    Green, R. N.

    1981-01-01

    The Earth Radiation Budget Experiment has the objective to collect the radiation budget data which are needed to determine the radiation budget at the top of the atmosphere (TOA) on a regional scale. A second objective is to determine the accuracy of the results. Three satellites will carry wide and medium field of view radiometers which measure the longwave and shortwave components of radiation. Scanning radiometers will be included to detect small spatial features. A proposal has been made to employ for the nonscanning radiometers a one-dimensional numerical filter which reduces satellite measurements to TOA radiant excitances. The numerical filter was initially formulated by House (1980). It enhances the resolution of the radiation budget along the satellite groundtrack. The accuracy of the numerical filter estimate is studied by simulating the data gathering and measurement inversion process. The results of the study are discussed, taking into account two error sources.

  20. Numerical Simulation and Clinical Verification of the Minimally Invasive Repair of Pectus Excavatum

    PubMed Central

    Zhong, WeiHong; Ye, JinDuo; Liu, JiFu; Zhang, ChunQiu; Zhao, MeiJiao

    2014-01-01

    Objective: In this article we proposed a modeling method by building an assembled model to simulate the orthopedic process of minimally invasive surgery for pectus excavatum and got the clinical verification, which aims to provide some references for clinic diagnoses, treatment, and surgery planning. Methods: The anterior chest model of a 15-year-old patient was built based on his CT images; and his finite element model and the Nuss bar were created. Coupling of nodal displacement was used to connect bones with cartilages of the anterior chest. Turning the Nuss bar over is completed by rotating displacement of it. By comparing the numerical simulation outcomes with clinical surgery results, the numerical simulation results were verified Results: The orthopedic process of minimally invasive surgery of pectus excavatum was simulated by model construction and numerical analysis. The stress, displacement fields and distribution of the contact pressure between the Nuss bar and costal cartilages were analyzed. The relationship between correcting force and displacement was obtained. Compared with the of clinical results, the numerical simulation results were close to that of the actual clinical surgery in displacement field, and the final contact position of the Nuss bar and the costal cartilages. Conclusion: Compared with the rigid model, the assembled simulation model is in more conformity with the actual clinical practice. The larger curvature results in the maximum equivalent stress, which is the main reason for clinical pain. Soft tissues and muscles should be taken into account in the numerical simulation process. PMID:26312072

  1. Procedural cost accounting: a survival tactic.

    PubMed

    Anderson, D J

    1985-01-01

    With the recent introduction of PPS and DRGs, nonprofit institutions in our industry have had to make major modifications in their methodology for fiscal soundness. One area that must be addressed is cost accounting and, more specifically, procedure cost accounting. Many hospital department managers have no formal training or education in cost accounting. Likewise, very few physicians receive cost-accounting training in their residency programs. Therefore, in the past, there has been little emphasis on this fiscal procedure. Cost accounting is the recording and classifying of the price paid for anything. The costs associated with a specific procedure are assembled into categories and compiled into a base figure with any additional indirect components or overhead costs taken into account. The resulting figure is then corrected for the institution's collection rate to assure complete recovery of all costs. This method is by no means the answer to every organization's needs; however, it is a starting place for managers. Radiology managers can improve upon this worksheet as their knowledge and understanding of the fiscal side of the hospital continues to grow. With more accurate methods for determining costs, managers can incorporate these into the process. The result will contribute to the final goal, a more efficient and cost effective operation.

  2. The Voluntary System of Accountability for Accountability and Institutional Assessment

    ERIC Educational Resources Information Center

    Keller, Christine M.; Hammang, John M.

    2008-01-01

    The Voluntary System of Accountability (VSA) provides a framework for public universities to provide evidence of success and increase public confidence. The goals of the VSA are threefold: (1) Demonstrate greater accountability and stewardship to the public; (2) Enhance effective educational practices by measuring educational outcomes; and (3)…

  3. Accountability Reporting and Tracking System

    1992-07-02

    ARTS is a micro based prototype of the data elements, screens, and information processing rules that apply to the Accountability Reporting Program. The system focuses on the Accountability Event. The Accountability Event is an occurrence of incurring avoidable costs. The system must be able to CRUD (Create, Retrieve, Update, Delete) instances of the Accountability Event. Additionally, the system must provide for a review committee to update the ''event record'' with findings and determination information. Lastly,more » the system must provide for financial representatives to perform a cost reporting process.« less

  4. WAPA Daily Energy Accounting Activities

    1990-10-01

    ISA (Interchange, Scheduling, & Accounting) is the interchange scheduling system used by the DOE Western Area Power Administration to perform energy accounting functions associated with the daily activities of the Watertown Operations Office (WOO). The system's primary role is to provide accounting functions for scheduled energy which is exchanged with other power companies and power operating organizations. The system has a secondary role of providing a historical record of all scheduled interchange transactions. The followingmore » major functions are performed by ISA: scheduled energy accounting for received and delivered energy; generation scheduling accounting for both fossil and hydro-electric power plants; metered energy accounting for received and delivered totals; energy accounting for Direct Current (D.C.) Ties; regulation accounting; automatic generation control set calculations; accounting summaries for Basin, Heartland Consumers Power District, and the Missouri Basin Municipal Power Agency; calculation of estimated generation for the Laramie River Station plant; daily and monthly reports; and dual control areas.« less

  5. Accountability Reporting and Tracking System

    SciTech Connect

    Jones, Jeffery

    1992-07-02

    ARTS is a micro based prototype of the data elements, screens, and information processing rules that apply to the Accountability Reporting Program. The system focuses on the Accountability Event. The Accountability Event is an occurrence of incurring avoidable costs. The system must be able to CRUD (Create, Retrieve, Update, Delete) instances of the Accountability Event. Additionally, the system must provide for a review committee to update the ''event record'' with findings and determination information. Lastly, the system must provide for financial representatives to perform a cost reporting process.

  6. Numerical Modeling of Ablation Heat Transfer

    NASA Technical Reports Server (NTRS)

    Ewing, Mark E.; Laker, Travis S.; Walker, David T.

    2013-01-01

    A unique numerical method has been developed for solving one-dimensional ablation heat transfer problems. This paper provides a comprehensive description of the method, along with detailed derivations of the governing equations. This methodology supports solutions for traditional ablation modeling including such effects as heat transfer, material decomposition, pyrolysis gas permeation and heat exchange, and thermochemical surface erosion. The numerical scheme utilizes a control-volume approach with a variable grid to account for surface movement. This method directly supports implementation of nontraditional models such as material swelling and mechanical erosion, extending capabilities for modeling complex ablation phenomena. Verifications of the numerical implementation are provided using analytical solutions, code comparisons, and the method of manufactured solutions. These verifications are used to demonstrate solution accuracy and proper error convergence rates. A simple demonstration of a mechanical erosion (spallation) model is also provided to illustrate the unique capabilities of the method.

  7. Toward Scientific Numerical Modeling

    NASA Technical Reports Server (NTRS)

    Kleb, Bil

    2007-01-01

    Ultimately, scientific numerical models need quantified output uncertainties so that modeling can evolve to better match reality. Documenting model input uncertainties and verifying that numerical models are translated into code correctly, however, are necessary first steps toward that goal. Without known input parameter uncertainties, model sensitivities are all one can determine, and without code verification, output uncertainties are simply not reliable. To address these two shortcomings, two proposals are offered: (1) an unobtrusive mechanism to document input parameter uncertainties in situ and (2) an adaptation of the Scientific Method to numerical model development and deployment. Because these two steps require changes in the computational simulation community to bear fruit, they are presented in terms of the Beckhard-Harris-Gleicher change model.

  8. Numerical simulation of small perturbation transonic flows

    NASA Technical Reports Server (NTRS)

    Seebass, A. R.; Yu, N. J.

    1976-01-01

    The results of a systematic study of small perturbation transonic flows are presented. Both the flow over thin airfoils and the flow over wedges were investigated. Various numerical schemes were employed in the study. The prime goal of the research was to determine the efficiency of various numerical procedures by accurately evaluating the wave drag, both by computing the pressure integral around the body and by integrating the momentum loss across the shock. Numerical errors involved in the computations that affect the accuracy of drag evaluations were analyzed. The factors that effect numerical stability and the rate of convergence of the iterative schemes were also systematically studied.

  9. Accountability Indicators from the Viewpoint of Statistical Method.

    ERIC Educational Resources Information Center

    Jordan, Larry

    Few people seriously regard students as "products" coming off an educational assembly line, but notions about accountability and quality improvement in higher education are pervaded by manufacturing ideas and metaphors. Because numerical indicators of quality are inevitably expressed by trend lines or statistical control chars of some kind, they…

  10. Accounting for adsorption and desorption in lattice Boltzmann simulations.

    PubMed

    Levesque, Maximilien; Duvail, Magali; Pagonabarraga, Ignacio; Frenkel, Daan; Rotenberg, Benjamin

    2013-07-01

    We report a Lattice-Boltzmann scheme that accounts for adsorption and desorption in the calculation of mesoscale dynamical properties of tracers in media of arbitrary complexity. Lattice Boltzmann simulations made it possible to solve numerically the coupled Navier-Stokes equations of fluid dynamics and Nernst-Planck equations of electrokinetics in complex, heterogeneous media. With the moment propagation scheme, it became possible to extract the effective diffusion and dispersion coefficients of tracers, or solutes, of any charge, e.g., in porous media. Nevertheless, the dynamical properties of tracers depend on the tracer-surface affinity, which is not purely electrostatic and also includes a species-specific contribution. In order to capture this important feature, we introduce specific adsorption and desorption processes in a lattice Boltzmann scheme through a modified moment propagation algorithm, in which tracers may adsorb and desorb from surfaces through kinetic reaction rates. The method is validated on exact results for pure diffusion and diffusion-advection in Poiseuille flows in a simple geometry. We finally illustrate the importance of taking such processes into account in the time-dependent diffusion coefficient in a more complex porous medium. PMID:23944584

  11. Accounting for adsorption and desorption in lattice Boltzmann simulations.

    PubMed

    Levesque, Maximilien; Duvail, Magali; Pagonabarraga, Ignacio; Frenkel, Daan; Rotenberg, Benjamin

    2013-07-01

    We report a Lattice-Boltzmann scheme that accounts for adsorption and desorption in the calculation of mesoscale dynamical properties of tracers in media of arbitrary complexity. Lattice Boltzmann simulations made it possible to solve numerically the coupled Navier-Stokes equations of fluid dynamics and Nernst-Planck equations of electrokinetics in complex, heterogeneous media. With the moment propagation scheme, it became possible to extract the effective diffusion and dispersion coefficients of tracers, or solutes, of any charge, e.g., in porous media. Nevertheless, the dynamical properties of tracers depend on the tracer-surface affinity, which is not purely electrostatic and also includes a species-specific contribution. In order to capture this important feature, we introduce specific adsorption and desorption processes in a lattice Boltzmann scheme through a modified moment propagation algorithm, in which tracers may adsorb and desorb from surfaces through kinetic reaction rates. The method is validated on exact results for pure diffusion and diffusion-advection in Poiseuille flows in a simple geometry. We finally illustrate the importance of taking such processes into account in the time-dependent diffusion coefficient in a more complex porous medium.

  12. Accountability in Education: Implications for Guidance Workers.

    ERIC Educational Resources Information Center

    Lessinger, Leon

    An accountability policy is seen as having three basic elements: demonstrated student accomplishment, independent accomplishment audits, and public reports. It requires the regular independent review of results obtained for resources expended. Effects resulting from implementation of such a policy are: (1) the focus of schooling shifts from…

  13. Meaning: A Verbal Behavior Account

    ERIC Educational Resources Information Center

    Lowenkron, Barry

    2004-01-01

    Although the verbal operants that comprise Skinner's account of verbal behavior provide a seemingly complete description of the behavior of the speaker with respect to what is ordinarily called the expression of meanings, it may be shown that the account is intrinsically deficient in describing the receptive behavior of listeners with regard to…

  14. Efficacy and Accountability in Organizations.

    ERIC Educational Resources Information Center

    Reitzug, Ulrich C.

    This study examined the relationship among accountability, efficacy, and organizational effectiveness by integrating findings from 17 research and development reports on Management by Objectives (MBO), an intervention that incorporates elements and processes of both accountability (goal-setting, measuring and monitoring, feedback) and efficacy…

  15. Peer-to-peer accountability.

    PubMed

    Guidi, M A

    1995-10-01

    Peer-to-peer accountability is an essential component of empowerment-based management models. To foster this environment, skills such as conflict resolution, team building, communication and group dynamics need to be identified and supported. The lack of peer-to-peer accountability can seriously hinder the development of management models. PMID:7566813

  16. Revised Accounting for Business Combinations

    ERIC Educational Resources Information Center

    Wilson, Arlette C.; Key, Kimberly

    2008-01-01

    The Financial Accounting Standards Board (FASB) has recently issued Statement of Financial Accounting Standards No. 141 (Revised 2007) Business Combinations. The object of this Statement is to improve the relevance, representational faithfulness, and comparability of reported information about a business combination and its effects. This Statement…

  17. The Accountability Illusion: New Mexico

    ERIC Educational Resources Information Center

    Thomas B. Fordham Institute, 2009

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and…

  18. PLATO Instruction for Elementary Accounting.

    ERIC Educational Resources Information Center

    McKeown, James C.

    A progress report of a study using computer assisted instruction (CAI) materials for an elementary course in accounting principles is presented. The study was based on the following objectives: (1) improvement of instruction in the elementary accounting sequence, and (2) help for transfer students from two-year institutions. The materials under…

  19. GASB's Basis of Accounting Project.

    ERIC Educational Resources Information Center

    Kovlak, Daniel L.

    1986-01-01

    In July 1984, the Governmental Accounting Standards Board began its "Measurement Focus/Basis of Accounting" project, which addresses measurement issues and revenue and expenditure recognition problems involving governmental funds. This article explains the project's background, alternatives discussed by the board, and tentative conclusions and…

  20. The Accountability Illusion: Rhode Island

    ERIC Educational Resources Information Center

    Thomas B. Fordham Institute, 2009

    2009-01-01

    The intent of the No Child Left Behind (NCLB) Act of 2001 is to hold schools accountable for ensuring that all their students achieve mastery in reading and math, with a particular focus on groups that have traditionally been left behind. Under NCLB, states submit accountability plans to the U.S. Department of Education detailing the rules and…