Models Of Physical Effects Research Articles

Mathematical Models and Software for Flexible Vehicle Simulation

The concept of universal program development to research the dynamic properties and simulate the flight of different types flexible vehicles is considered I. The basis of program is the structure, which allows carrying out the analysis of dynamic characteristics, simulation and visual information representation. The program package is supplied with the library of program modules. These modules are designed on the base of mathematical models of vehicle separate elements and different physical effects, such as flexibility, sloshing, sluggishness of engines, local angle of attack values, etc. Selection of different sets of program modules allows investigating different designs for known and prospective vehicle. The interface of the program enables changing data vehicle in a wide range, to simulate flight at any trajectory and to output results of the analysis in digital or graphic representation.

Orbit analysis of the satellite westpac

This paper addresses the computation of the orbit of the satellite WESTPAC, which was launched on July 10, 1998, into a circular orbit at an altitude of 835 km and with an inclination of 98 degrees. To obtain a high-quality orbit solution, all forces acting on the satellite need to be modelled as accurately as possible. This paper discusses the influence of the modelling of different physical effects on the motion of WESTPAC, in particular in terms of orbit quality. The study is based on observations taken by the global network of laser stations during the period from August 1, 1998, until March 30, 1999. In this study, a number of test cases are defined and investigated, focussing on optimum orbit quality. The latter is assessed by looking at the (weighted) rms-of-fit, the orbit overlaps of successive data arcs and the stability of independent solve-for parameters. The investigation has resulted in a “best” scenario which includes the following elements: the GRIM-5S1 gravity field solution, the MSIS86 model for atmospheric density, the GOT99.2 ocean tides model, drag coefficients solved-for at 12-hour intervals, and one set of 1-cpr accelerations in the along-track and cross-track directions. This scenario gives a fit of the laser range observations of 3.7 cm and an orbit quality of about 5, 10 and 20 cm in the radial, cross-track and along-track directions, respectively.

QSAR of benzene derivatives: comparison of classical descriptors, quantum theoretic parameters and flip regression, exemplified by phenylalkylamine hallucinogens.

A physical model of electronic effects in the QSAR of benzene derivatives, together with a regression technique for finding predictive equations, is presented. The model is simple, based on the quantum theoretic description of the benzene molecule, and accounts for the variance in activity of hallucinogenic phenylalkylamines as well as a classical description in terms of electronic (atomic charge, orbital energy), hydrophobic (Hansch pi) and steric (substituent volume) terms. The new model involves the energies of four pi-like near frontier orbitals and the orientations of their nodes. It is less affected by colinearity than the classical approach. This model more than any other illustrates the essential wave mechanical nature of the interaction of a drug with its receptor, as the pi-like orbitals involved are standing waves of probability of finding an electron in a given location in the field of the atomic nuclei, and have no classical counterpart.

A system-level simulation of complex multi-domain microsystems by using analogue hardware description languages

A simulation approach is presented, which permits the simulation of spatially distributed fields with behavioral models of other physical effects and accompanying electronics within a single simulator environment. The final system-level model is a blend of finite-element, analytical, semi-analytical and parametric behavioral models with complex analogue and digital circuit networks. Previously evaluated calculations revealed successful simulation of finite element models with more than 25 000 nodes by using analogue simulators with hardware description language. The relative error of static calculations in comparison with commercial finite element simulators is better than 0.002% and 0.08% for 2D and 3D models, respectively. The results obtained in transient model verification proved the accuracy of the method. The simulation of the flow sensor system, whose functionality is governed by coupled fluidic-thermal-electric domains, is employed to show the feasibility of the method for complex microsystem modeling.

Short-term prediction of local wind conditions

Using Numerical Weather Prediction (NWP) models it has been shown that they, combined with models (either physical or statistical) taking local effects into account, can be used to predict the wind locally better than the models commonly used today (as eg persistence). By “local” is meant at one distinct spot, as eg the location of a meteorological mast. The physical model of local effects takes the following into account: shelter from near-by obstacles, the effect of roughness changes and the effect of the local orography. The large-scale flow is linked to the surface flow by the geostrophic drag law, and the logarithmic wind profile. The predictions are made up to 36 hours ahead. The model is tested on data from 50 meteorological stations scattered all over Europe.

Reverse short-channel effect due to lateral diffusion of point-defect induced by source/drain ion implantation

Presents a physical model of reverse short-channel effects on threshold voltage caused by lateral diffusion of the Frenkel pairs (interstitial-vacancy) induced by ion implantation in source/drain region of n-channel MOS devices. Based on the process and device simulation, it is shown that lateral diffusion of the Frenkel pairs enhances diffusion of channel dopant, and results in nonuniform lateral distribution. This phenomenon causes the threshold voltage increase in the short-channel devices. The authors extracted parameters on point-defect diffusion from the comparison of calculated results with experimental data on threshold voltage. Calculated arsenic profile in the source/drain region using those parameters shows good agreement with the experimental data measured by secondary ion mass spectroscopy (SIMS). The close agreement between simulation and experimental results both on the arsenic profile in source/drain region and threshold voltage confirms the validity of the model and extracted parameters. >

Physical model of bathymetric effects on the Antarctic Circumpolar Current

Physical model of bathymetric effects on the Antarctic Circumpolar Current

Physical model of bathymetric effects on the Antarctic circumpolar current

Laboratory experiments were conducted to simulate some of the effects of the bathymetry of the southern ocean on the physical characteristics of the Antarctic Circumpolar Current (ACC). An idealized zonal wind stress, which varied inversely with the distance from the model Antarctic continent, was simulated in the laboratory model by a radially inward sink‐source flow in a thin layer along the surface of the circular test cell. The experiments demonstrated the feasibility of simulating the surface wind stress in physical models by source‐sink forcing. The present model, however, has the limitation of not accounting for such factors as the longitudinal variations in the wind shear and the decrease in wind stress on approaching the Antarctic continent from the north. Planetary beta effects were neglected because the topographic beta term can be shown to dominate over large portions of the model area. The neglect of beta effects is also a limitation of the model. In spite of these limitations, however, the simulations of the physical model for both the homogeneous and linearly stratified cases were shown to be in good agreement with observations of the ACC. These include well‐defined strong currents along the mid‐ocean ridge; strong perturbations in the vicinity of the Macquarie Ridge, Campbell Plateau, and Kerguelen Gaussberg Plateau; strong meridional transport to the east of the Drake Passage; and anomalies to the south (wave troughs) and to the north (wave ridges) of the main circumpolar current over ocean basins and mountain ridges, respectively. It was shown that the Eltanin and Udintsev fracture zones in the vicinity of 135°W are important factors in directing the ACC eastward across the Southeast Pacific Basin to the Drake Passage. The model results suggest that these fracture zones can influence the nature of the flow in the western Atlantic because of their control of the flow through the Drake Passage. The estimated volume transports through the Drake Passage based on the model results are in fair agreement with oceanic observations. Estimates of the spin‐up time of the system for homogeneous and stratified cases have been provided.

Numerical modeling of physical effects in the drawing of a glassy material into a fiber

Numerical modeling of physical effects in the drawing of a glassy material into a fiber

Performance Assessment with Realistic Data for a Hypothetical High-Level Waste Repository in A Salt Dome

ABSTRACTIn the frame of the European R&D program on “Management and Storage of Radioactive Waste” assessments for HLW repositories in different geological formations have been performed with realistic data. Part of this action was the discussion of altered evolution scenarios for a repository in a salt dome.For the considered HLW repository a combined altered evolution scenario with brine intrusion via the main anhydrite vein and brine intrusion from undetected brine pockets has been considered. For this scenario limited intrusions of brine at very early times are assumed, which inundate boreholes and parts of the repository. Radionuclides are leached out of the waste forms and contaminate the brine. At later times brine intrusion via the main anhydrite is assumed to take place. Under certain conditions contact between both amounts of brine is possible, and contaminated brine reaches the overburden. Here, the radionuclides are swept away with the groundwater flow.Decisive for the transport of radionuclides from the repository to the geosphere are several interacting effects (e.g. convergence, permeability, pressure) which determine the movement of brine through the drifts and seal-ings. For the parameters involved in the modelling of physical and chemical effects as realistic data as available (best estimate) were used. Local sensitivity studies show that with the best estimate values for some parameters the combined intrusion scenario is just at the transition point between release and no release.Results are obtained showing time histories for the decrease of the voids in the repository, release rates for relevant nuclides injected into the overburden, and for dose rates. Dependences on the model parameters are discussed and most relevant parameters are identified.

4075. Evaporated films of arsenic trisulfide: physical model of effects of light exposure and heat cycling. (USA)

4075. Evaporated films of arsenic trisulfide: physical model of effects of light exposure and heat cycling. (USA)

Evaporated films of arsenic trisulfide: Physical model of effects of light exposure and heat cycling

The optical-storage effect in evaporated films of arsenic trisulfide (As2S3) has been investigated. The physical and chemical aspects of the films were studied using a combination of etching, x-ray diffraction, ir spectroscopy, and annealing experiments. This study of the As2S3 optical-storage medium has culminated in the development of a physical model involving three well-defined states for the medium.