Accelerated convergence for incompressible flow calculations

Two improved algorithms which solve the steady-state Navier-Stokes equations, PISO and SIMPLER, are studied. Computations were carried out on progressively finer grids for the driven cavity and flow over a backward-facing step. The effects of relaxation factor, number of grid nodes and number of sweeps through the pressure equations are studied to evaluate the performance of the PISO and SIMPLER schemes. Results show that these improved schemes accelerate the convergence rate of the solution generally by a factor of two as compared to the SIMPLE method

Capital flows and Japanese asset volatility

Characterizing asset price volatility is an important goal for financial economists. The literature has shown that variables that proxy for the information arrival process can help explain and/or forecast volatility. Unfortunately, however, obtaining good measures of volume and/or order flow is expensive or difficult in decentralized markets such as foreign exchange. We investigate the extent that Japanese capital flows—which are released weekly—reflect information arrival that improves foreign exchange and equity volatility forecasts. We find that capital flows can help explain transitory shocks to GARCH volatility. Transactions by Japanese residents in foreign bond markets have the most explanatory power among capital flows and that power is much greater in the second subsample.Capital movements ; Foreign exchange ; Japan

Mesoscopic dynamical differences from quantum state preparation in a Bose-Hubbard trimer

Conventional wisdom is that quantum effects will tend to disappear as the number of quanta in a system increases, and the evolution of a system will become closer to that described by mean field classical equations. In this letter we combine newly developed experimental techniques to propose and analyse an experiment using a Bose-Hubbard trimer where the opposite is the case. We find that differences in the preparation of a centrally evacuated trimer can lead to readily observable differences in the subsequent dynamics which increase with system size. Importantly, these differences can be detected by the simple measurements of atomic number.Comment: 5 pages, 4 figures, theor

Reducing numerical diffusion for incompressible flow calculations

A number of approaches for improving the accuracy of incompressible, steady-state flow calculations are examined. Two improved differencing schemes, Quadratic Upstream Interpolation for Convective Kinematics (QUICK) and Skew-Upwind Differencing (SUD), are applied to the convective terms in the Navier-Stokes equations and compared with results obtained using hybrid differencing. In a number of test calculations, it is illustrated that no single scheme exhibits superior performance for all flow situations. However, both SUD and QUICK are shown to be generally more accurate than hybrid differencing

Flame radiation and liner heat transfer in a tubular-can combustor

Heat transfer within a combuster were examined. Total and spectral flame radiation in a tubular can combustor at a series of parametric operating conditions was measured. Radiation measurements were taken for a range of inlet air pressures from 0.34 to 2.0 MPa, inlet air temperatures from 533 to 700 K, with two different fuels, Jet-A and ERBS. Measurements of liner temperatures combined with the parametric radiation results allowed a calculation of the combustor liner heat loads. Flame emissivity was determined from the spectral measurements

Persistent current formation in a high-temperature Bose-Einstein condensate: an experimental test for c-field theory

Experimental stirring of a toroidally trapped Bose-Einstein condensate at high temperature generates a disordered array of quantum vortices that decays via thermal dissipation to form a macroscopic persistent current [T. W. Neely em et al. arXiv:1204.1102 (2012)]. We perform 3D numerical simulations of the experimental sequence within the Stochastic Projected Gross-Pitaevskii equation using ab initio determined reservoir parameters. We find that both damping and noise are essential for describing the dynamics of the high-temperature Bose field. The theory gives a quantitative account of the formation of a persistent current, with no fitted parameters.Comment: v2: 7 pages, 3 figures, new experimental data and numerical simulation

Fusion and Perspective Correction of Multiple Networked Video Sensors

A network of adaptive processing elements has been developed that transforms and fuses video captured from multiple sensors. Unlike systems that rely on end-systems to process data, this system distributes the computation throughout the network in order to reduce overall network bandwidth. The network architecture is scalable because it uses a hierarchy of processing engines to perform signal processing. Nodes within the network can be dynamically reprogrammed in order to compose video from multiple sources, digitally transform camera perspectives, and adapt the video format to meet the needs of specific applications. A prototype has been developed using reconfigurable hardware that collects and processes real-time, streaming video of an urban environment. Multiple video cameras gather data from different perspectives and fuse that data into a unified, top-down view. The hardware exploits both the spatial and temporal parallelism of the video streams and the regular processing when applying the transforms. Recon-figurable hardware allows for the functions at nodes to be reprogrammed for dynamic changes in topology. Hardware-based video processors also consume less power than high frequency software-based solutions. Performance and scalability are compared to a distributed software-based implementation. The reconfigurable hardware design is coded in VHDL and prototyped using Washington University’s Field Programmable Port Extender (FPX) platform. The transform engine circuit utilizes approximately 34 percent of the resources of a Xilinx Virtex 2000E FPGA, and can be clocked at frequencies up to 48 MHz. The com-position engine circuit utilizes approximately 39 percent of the resources of a Xilinx Virtex 2000E FPGA, and can be clocked at frequencies up to 45 MHz

Mississippi\u27s New Equitable Distribution Rules: The Ferguson Guidelines and Valuation`

Mississippi Focu