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Recent decades have witnessed a drastic increase in the fidelity of numerical weather prediction (NWP) modeling. Currently, both research-grade and operational NWP models regularly perform simulations with horizontal grid spacings as fine as 1 km. This migration towards higher resolution potentially improves NWP model solutions by increasing the resolvability of mesoscale processes and reducing dependency on empirical physics parameterizations. However, at the same time, the accuracy of highresolution simulations, particularly in the atmospheric boundary layer (ABL), are also sensitive to orographic forcing which can have significant variability on the same spatial scale as, or smaller than, NWP model grids. Despite this sensitivity, many high resolution atmospheric simulations do not consider uncertainty with respect to selection of static terrain height dataset. In this paper, we use the Weather Research and Forecasting (WRF) model to simulate realistic cases of lower tropospheric flow over and downstream of mountainous islands using both the default global 30 s United States Geographic Survey terrain height dataset (GTOPO30) and the 3 s Shuttle Radar Topography Mission (SRTM) terrain height dataset. Our results demonstrate cases where the differences between GTOPO30-based and SRTM-based model terrain height are significant enough to produce entirely different orographic wake mechanics, such as vortex shedding vs. no vortex shedding. These results are also compared to MODIS visible satellite imagery and highlight the importance of considering uncertain static boundary conditions when running high-resolution mesoscale models. [ABSTRACT FROM AUTHOR]

In order to easily enforce solid-wall boundary conditions in the presence of complex coastlines, we propose a new mass and energy conserving Brinkman penalization for the rotating shallow water equations. This penalization does not lead to higher wave speeds in the solid region. The error estimates for the penalization are derived analytically and verified numerically for linearized one dimensional equations. The penalization is implemented in a conservative dynamically adaptive wavelet method for the rotating shallow water equations on the sphere with bathymetry and coastline data from NOAA's ETOPO1 database. This code could form the dynamical core for a future global ocean model. The potential of the dynamically adaptive ocean model is illustrated by using it to simulate the 2004 Indonesian tsunami and wind-driven gyres. [ABSTRACT FROM AUTHOR]

An analytical solution of the Boussinesq equations for the motion of a viscous stably stratified fluid driven by a surface thermal forcing with large horizontal gradients (step changes) is obtained. The solution can be used to verify that computer codes for Boussinesq fluid system simulations are free of errors in formulation of wall boundary conditions, and to evaluate the relative performances of competing numerical algorithms. Because the solution pertains to flows driven by a surface thermal forcing, one of its main applications may be for testing the no-slip, impermeable wall boundary conditions for the pressure Poisson equation. Examples of such tests are presented. [ABSTRACT FROM AUTHOR]

This is a comment on a 2014 paper by Dai and Wang. It is argued that the validation in Dai and Wang's paper is an artifact caused by the boundary conditions of the level-set function, meaning that the effects reported in their paper have little physical relevance. Simulations are presented using Dai and Wang's methods to illustrate this claim. Remarks are made on the choice of boundary conditions for the level-set function, as well as the frequency of reinitialization, both of which are important topics that are sometimes overlooked.Asimple criterion is proposed for determining the appropriate reinitialization frequency in simulations of highly viscous flows. [ABSTRACT FROM AUTHOR]

A multiscale simulation method for modeling granular materials was proposed in this paper. The key links in this method were analyzed, and the computing framework was constructed. In this multiscale approach, the finite-element method was used to simulate the boundary value problem. From the discrete particle aggregation embedded in each gauss integral point, the constitutive relation was extracted for the overall solution. This approach did not require complex constitutive hypotheses on the macroscopic scale. The description of the contact constitutive behavior between particles was relatively simple on the mesoscopic scale. Meanwhile, the macroscopic response could be effectively described by the mesoscopic mechanism. After a program verification, a representative test was numerically modeled using this technique. Through biaxial compression multiscale test of particles, macro–mesoscopic mechanical properties were investigated. The present approach may prove useful in expanding our understanding of the mechanical behavior of granular materials. [ABSTRACT FROM AUTHOR]

Trotter's theorem forms the theoretical basis of most modern molecular dynamics. In essence this theorem states that a time displacement operator (a Lie operator) constructed by exponentiating a sum of noncommuting operators can be approximated by a product of single operators provided the time interval is 'very small.' In theory 'very small' implies infinitesimally small (at which point the approximate product becomes exact), while in practical analysis a finite time interval is divided into several small subintervals or steps. It follows, therefore, that the larger the number of steps the better the approximation to the exact time displacement operator. The question therefore arises: How many steps are sufficient? For bounded operators, standard theorems are available to provide the answer. In this paper we show that a very simple combinatorial formula can be derived which allows the computation of the global differences (as a function of the number of steps) between the Taylor coefficients of the exact time displacement operator and an approximate one constructed by using a finite number of steps. The formula holds for both bounded and nonbounded operators and shows, quantitatively, what is qualitatively expected-that the error decreases with increasing number of steps. Furthermore, the formula applies irrespective of the complexity of the system, boundary conditions, or the thermodynamic ensemble employed for averaging the initial conditions. The analysis yields explicit expressions for the Taylor coefficients which are then used to compute the errors. In the case of the algorithmically based practical numerical simulations in which fixed, albeit small, steps are repeatedly applied, the rise in the number of steps does not reduce the size of the steps but increases the total time of interest. The combinatorial formula shows that, here, the errors diverge. Furthermore, this work can be used to supplement other efforts such as the use of shadow Hamiltonians where the truncation of the series expansion of the latter will produce errors in the higher order propagator moments. [ABSTRACT FROM AUTHOR]

A method to sum over logarithmic potential in two-dimensions (2D) and Coulomb potential in three dimensions (3D) with periodic boundary conditions in all directions is given. We consider the most general form of unit cells, the rhombic cell in 2D and the triclinic cell in 3D. For the 3D case, this paper presents a generalization of Sperb’s work [R. Sperb, Mol. Simulation 22, 199 (1999)]. The expressions derived in this work converge extremely fast in all region of the simulation cell. We also obtain results for slab geometry. Furthermore, self-energies for both 2D as well as 3D cases are derived. Our general formulas can be employed to obtain Madelung constants for periodic structures. © 2005 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Fluid simulation has been one of the greatest successes of physics-based animation, generating hundreds of research papers and a great many special effects over the last fifteen years. However, the animation of large-scale, splashing liquids remains challenging. In this paper, we show that a novel combination of unilateral incompressibility, mass-full FLIP, and blurred boundaries is extremely well-suited to the animation of large-scale, violent, splashing liquids. [ABSTRACT FROM AUTHOR]

The presence of particles, which can intrude into the air bearing, is one of the most common factors in the failure of hard disk drives (HDDs). Previous studies have investigated particles trajectories with the assumption of ideal trapping or reflecting boundary conditions in air-filled drives. However, only the colliding particle with insufficient energy to escape the potential well will be trapped by the surface. In this paper, considering the particle-surface energy during the collision, the trapping criterion of the incident normal critical velocity ( V\text {ni}^{\mathrm {\ast }}) for Al2O3 particles is developed as the boundary conditions for different colliding surfaces inside a 2.5 in drive. Then, trapping status for Al2O3 particles and particles trajectories inside the drive are simulated by using the commercial computational fluid dynamics solver FLUENT with user-defined functions. The results reveal that the particles will travel longer distances until trapped by HDD components when considering the trapping criterion. In addition, smaller particles will more likely degrade the head–disk interface reliability, since they easily stick on the disk surface. [ABSTRACT FROM PUBLISHER]

Detailed 3D finite-element simulations are state of the art for structural analyses of wind turbine rotor blades. It is of utmost importance to validate the underlying modeling methodology in order to obtain reliable results. Validation of the global response can ideally be done by comparing simulations with full-scale blade tests. However, there is a lack of test results for which also the finite-element model with blade geometry and layup as well as the test documentation and results are completely available. The aim of this paper is to validate the presented fully parameterized blade modeling methodology that is implemented in an in-house model generator and to provide respective test results for validation purpose to the public. This methodology includes parameter definition based on splines for all design and material parameters, which enables fast and easy parameter analysis. A hybrid 3D shell/solid element model is created including the respective boundary conditions. The problem is solved via a commercially available finite-element code. A static full-scale blade test is performed, which is used as the validation reference. All information, e.g., on sensor location, displacement, and strains, is available to reproduce the tests. The tests comprise classical bending tests in flapwise and lead-lag directions according to IEC 61400-23 as well as torsion tests. For the validation of the modeling methodology, global blade characteristics from measurements and simulation are compared. These include the overall mass and center of gravity location, as well as their distributions along the blade, bending deflections, strain levels, and natural frequencies and modes. Overall, the global results meet the defined validation thresholds during bending, though some improvements are required for very local analysis and especially the response in torsion. As a conclusion, the modeling strategy can be rated as validated, though necessary improvements are highlighted for future works. [ABSTRACT FROM AUTHOR]

Summary: The commonly used advancing layers method to generate hybrid meshes suffers from many drawbacks. The generation of isotropic meshes for far‐field domains with irregular and complex boundary subdivisions after boundary layers advancing is time consuming and, in some cases, is not robust in 3D. To address these difficulties, this paper presents a novel method to generate hybrid polygonal meshes in 2D and polyhedral meshes in 3D for viscous flow simulations. In the proposed method, first, we generate a full Voronoi diagram for the appropriate distribution of generators that avoids the extra mesh generation required for the remaining holes in the advancing layers method. To recover the inner solid boundaries, we implement a robust boundary cell cutting process. Because the generators are located layer by layer near the boundaries, there is no requirement to consider all of the Voronoi cells. Only the first layer Voronoi cells must be cut, making the calculation very efficient. We have generated hybrid meshes using the present method for many viscous flow cases. The results show close agreement between the computations and the experimental results, thus indicating the reliability and effectiveness of the hybrid mesh generated by our method. [ABSTRACT FROM AUTHOR]

Part 1 of this paper has discussed the uncertainties arising from gaps in knowledge or limited understanding of the processes involved in different natural hazard areas. Such deficits may include uncertainties about frequencies, process representations, parameters, present and future boundary conditions, consequences and impacts, and the meaning of observations in evaluating simulation models. These are the epistemic uncertainties that can be difficult to constrain, especially in terms of event or scenario probabilities, even as elicited probabilities rationalized on the basis of expert judgements. This paper reviews the issues raised by trying to quantify the effects of epistemic uncertainties. Such scientific uncertainties might have significant influence on decisions made, say, for risk management, so it is important to examine the sensitivity of such decisions to different feasible sets of assumptions, to communicate the meaning of associated uncertainty estimates, and to provide an audit trail for the analysis. A conceptual framework for good practice in dealing with epistemic uncertainties is outlined and the implications of applying the principles to natural hazard assessments are discussed. Six stages are recognized, with recommendations at each stage as follows: (1) framing the analysis, preferably with input from potential users; (2) evaluating the available data for epistemic uncertainties, especially when they might lead to inconsistencies; (3) eliciting information on sources of uncertainty from experts; (4) defining a workflow that will give reliable and accurate results; (5) assessing robustness to uncertainty, including the impact on any decisions that are dependent on the analysis; and (6) communicating the findings and meaning of the analysis to potential users, stakeholders, and decision makers. Visualizations are helpful in conveying the nature of the uncertainty outputs, while recognizing that the deeper epistemic uncertainties might not be readily amenable to visualizations. [ABSTRACT FROM AUTHOR]

Ly, N.T.H. and Hoan N.T., 2018. Determination of nearshore wave climate using a transformation matrix from offshore wave data. In: Almar, R.; Almeida, L.P.; Viet, N.T., and Sall, M. (eds.), Tropical Coastal and Estuarine Dynamics. Journal of Coastal Research, Special Issue No. 81, pp. 14–21. Coconut Creek (Florida), ISSN 0749-0208. Nearshore wave climate is important for the assessment of coastal process and morphological changes. For port engineers, nearshore wave climate is crucial for the determination of operational conditions and downtime analysis. The nearshore wave climate is often derived by translation of the 10 to 30-year offshore time series to nearshore. Direct transformation of such large amount of observations is not feasible, since it requires an extremely long computational time. This paper describes an advanced technique to quickly derive nearshore wave conditions from offshore wave data. First, determination of matrix of boundary conditions in which matrix nodes are chosen to cover wave conditions at offshore boundary. Then, simulations of wave for each condition as described in the selected matrix of offshore conditions. The results are used to determine the matrix of wave conditions for any given nearshore location. This matrix consists of factors that specify the relation between the offshore (model forcing) and nearshore (model results) wave parameters. With this matrix, offshore wave observations can be translated to any nearshore location. With this technique, a 30-year long time series of offshore wave measurement can be rapidly (less than 2 days) translated to nearshore wave conditions. This paper discusses in detail the working principles of the technique, as well important aspects such as the optimization of boundary conditions matrix. [ABSTRACT FROM AUTHOR]

In this paper, the engine model is built and the boundary parameters of specified conditions are gotten by using GT-POWER software. The acoustic performance and fluid dynamics are analyzed by means of GT-POWER software and CFX module of ANSYS software. The original muffler is evaluated by searching the transmission loss and pressure loss. Based on the simulation results and muffler theory, the relevant parameters and layout of the original muffler structure are improved. Two different improved schemes are put forward, through the obtained acoustic data and the hydrodynamic performance diagram, the mufflers of two schemes are evaluated respectively. The results show that the improved schemes are feasible to enhance the performance of muffler and noise elimination effects in high frequency performs are well. [ABSTRACT FROM AUTHOR]

This paper describes an extension of the Tsui, Matsumura, and Tsui (1985) procedure, which is based on a multinomial distribution model within the dollar-unit sampling framework, with a Dirichlet prior distribution. The extended model and a different Dirichlet prior are used in this study to generate upper and lower bounds and two-sided confidence intervals for situations in which both understatement and overstatement errors are possible. The reported simulation study indicates that the achieved confidence levels of the proposed estimates are usually close to or greater than the nominal levels in repeated sampling for the populations studied. [ABSTRACT FROM AUTHOR]

This paper presents a liquid simulation technique that enforces the incompressibility condition using a stream function solve instead of a pressure projection. Previous methods have used stream function techniques for the simulation of detailed single-phase flows, but a formulation for liquid simulation has proved elusive in part due to the free surface boundary conditions. In this paper, we introduce a stream function approach to liquid simulations with novel boundary conditions for free surfaces, solid obstacles, and solid-fluid coupling. Although our approach increases the dimension of the linear system necessary to enforce incompressibility, it provides interesting and surprising benefits. First, the resulting flow is guaranteed to be divergence-free regardless of the accuracy of the solve. Second, our free- surface boundary conditions guarantee divergence-free motion even in the un- simulated air phase, which enables two-phase flow simulation by only computing a single phase. We implemented this method using a variant of FLIP simulation which only samples particles within a narrow band of the liquid surface, and we illustrate the effectiveness of our method for detailed two-phase flow simulations with complex boundaries, detailed bubble interactions, and two-way solid-fluid coupling. [ABSTRACT FROM AUTHOR]

This paper carries out numerical simulation for pressure driven microscale gas flows in transition flow regime. The relaxation time of LBM model was modified with the application of near wall effective mean free path combined with a combination of Bounce-back and Specular Reflection (BSR) boundary condition. The results in this paper are more close to those of DSCM and IP-DSCM compared with the results obtained by other LBM models. The calculation results show that in transition regime, with the increase of Knudsen number, the dimensionless slip velocity at the wall significantly increases, but the maximum linear deviation of nonlinear pressure distribution gradually decreases. [ABSTRACT FROM AUTHOR]

This paper was inspired by the field of ejector design and deals with the flow in the Laval's nozzle. The problems of achieving of a low pressure in a vacuum ring pump are described in the introduction to the paper. Then the machine is precisely classified into the machine category and work principle of the ejector is described, as well. There is explained also the advantage of using the preliminary ejector within a vacuum ring pump. The paper deals with the principle of ejector operation and its particular design parts. In the following part of the paper is a description of a meshing in the software GAMBIT and setting of the boundary conditions for CFD simulation in the software ANSYS, which is used for CFD analysis. [ABSTRACT FROM AUTHOR]

In this paper, we introduce the concept of cyclic p-contraction pair for single-valued mappings. Then we present some best proximity point results for such mappings defined on proximally complete pair of subsets of a metric space. Also, we provide some illustrative examples that compared our results with some earliest. Finally, by taking into account a fixed point consequence of our main result we give an existence and uniqueness result for a common solution of a system of second order boundary value problems. [ABSTRACT FROM AUTHOR]

This paper reports on the theoretical aspects and current development status of a self-consistent truly multiphysics algorithm. The algorithm is based upon the Courant-insensitive space–time conservation-element solution-element methodology. Previous attempts for electromagnetic solutions have applicability only in constant material domains with PEC boundary conditions. This paper reports on the extension of this algorithm for the solution of the generalized Maxwell equations, including linear-dispersive materials. The numerical solution is shown to be extremely accurate on highly nonuniform meshes and reduces to the classical Yee FDTD error properties in the uniform Cartesian grid limit. Validation problems and comparison with the ubiquitous baseline FDTD algorithm will be presented in 1-D (2-D space–time). Results show that the second-order CESE method has an accuracy equivalent to fourth–sixth order FDTD for equal grids with highly discontinuous coefficients (e.g., permittivity). [ABSTRACT FROM AUTHOR]

The inverse problem of the initial condition about the boundary value of the chord vibration equation is ill-posed. First, we transform it into a Fredholm integral equation. Second, we discretize it by the trapezoidal formula method, and then obtain a severely ill-conditioned linear equation, which is sensitive to the disturbance of the data. In addition, the tiny error of right data causes the huge concussion of the solution. We cannot obtain good results by the traditional method. In this paper, we solve this problem by the Tikhonov regularization method, and the numerical simulations demonstrate that this method is feasible and effective. [ABSTRACT FROM AUTHOR]

The simulation of fertigation in furrows and level furrow systems faces a number of problems resulting in relevant restrictions to its widespread application. In this paper, a simulation model is proposed that addresses some of these problems by: (1) implementing an infiltration model that adjusts to the variations in wetted perimeter; (2) using a friction model that adjusts to different flows and which uses an absolute roughness parameter; (3) adopting an equation for the estimation of the longitudinal diffusion coefficient; and (4) implementing a second-order TVD numerical scheme and specific treatments for the boundary conditions and the junctions. The properties of the proposed model were demonstrated using three numerical tests focusing on the numerical scheme and the treatments. The application of the model to the simulation of furrows and furrow systems is presented in a companion paper, in which the usefulness of the innovative aspects of the proposed model is demonstrated. [ABSTRACT FROM AUTHOR]

This paper investigates the sensitivity of gate-all-around (GAA) nanowire (NW) to process variations compared with multigate devices using analytical solutions of Poisson's equation verified with device simulation. GAA NW and multigate devices with both heavily doped and lightly doped channels have been examined regarding their immunity to process-induced variations and dopant number fluctuation. Our study indicates that the lightly doped GAA NW has the smallest threshold voltage (Vth) dispersion caused by process variations and dopant number fluctuation. Specifically, the GAA NW shows better immunity to channel thickness variation than multigate devices because of its inherently superior surrounding gate structure. For heavily doped devices, dopant number fluctuation may become the dominant factor in the determination of overall Vth variation. The Vth dispersion of GAA NW may therefore be larger than that of multigate MOSFETs because of its larger surface-to-volume ratio. [ABSTRACT FROM AUTHOR]

Thermal design of MEMS/NEMS packages is drawing more attention from both industrial and academic communities. When the system becomes extremely small, the atomistic effects have to be taken into account correctly. The finite element method is not capable of accurately capturing all the information, especially when it is applied to the small dimensions. In order to study failure behavior, precise modeling of interfacial thermal conductance is essential. In this paper, a multi-scale model is proposed to research interfacial thermal resistance in MEMS/NEMS packaging. The model combines a molecular dynamics simulation for the critical regions within the system with a FE method for a continuum description of the remainder of the system. For non-equilibrium simulations, the establishment of the proper boundary condition is very difficult. In this coupled model, the continuum subdomain serves primarily as a boundary model that provides the low frequency impedance and a sink for the energy associated with outgoing waves of the molecular dynamics model. The simulations results show that the temperature distribution is non-uniform along the interface, and the interface tends to accumulate much heat when the temperature of heat source changed. At the primary stage, the interfacial thermal resistance is unstable and will become very large at certain time steps. At the last stage, the change of interfacial thermal resistance tends to be stable. There are few direct experimental measurements of the interfacial thermal resistance between dissimilar materials, while the similar experimental results support the conclusions in this paper. [ABSTRACT FROM AUTHOR]

Compact thermal models are often used during joint electrothermal simulation of microelectromechanical systems (MEMS) and circuits. Formal model reduction allows generation of compact thermal models automatically from high-dimensional finite-element models. Unfortunately, it requires fixing a film coefficient employed to describe the convection boundary conditions. As a result, compact models produced by model reduction do not comply with the requirements of being boundary condition independent. In the present paper, the authors suggest an approach of successive series expansion with respect to the film coefficient as well as to the frequency during model reduction that allows to overcome the problem and keep the film coefficient as a symbolic parameter in the reduced model. The approach is justified with a numerical example of electrothermal simulation of a microthruster unit. [ABSTRACT FROM AUTHOR]

This paper presents a two-dimensional electromagnetic model for a microwave (2.45 GHz) plasma reactor operated by an axial injection torch. The model solves Maxwell’s equations, adopting a harmonic time description and considering the collision dispersion features of the plasma. Perfect-conductor boundary conditions are satisfied at the reactor walls, and absorbing boundary conditions are used at the open end of the coaxial waveguide powering the system. Simulations yield the distribution of the electromagnetic fields and the average power absorbed by the system for a given spatial profile of the plasma density (tailored from previous experimental measurements), with maximum values in the range 1014-1015 cm-3. Model results reveal that the system exhibits features similar to those of an air-filled, one-end-shorted circular metal waveguide, supporting evanescent or oscillatory solutions for radial dimensions below or above a critical radius, respectively. Results also show that the fractional average power absorbed by the plasma is strongly influenced by the system dimensions, which play a major role in defining the geometry pattern of the electromagnetic field distribution. Simulations are used to provide general guidelines for device optimization. [ABSTRACT FROM AUTHOR]

In this paper we introduce a mean field method for simulating complex molecular systems like liquids and solutions. Using well-established theoretical principles and models, we obtained a relatively simple approach which seems to provide a reliable description of the bulk molecular behavior of liquid water. Moreover, we have applied this approach to study simple solutes in solution, like sodium and chloride ions and acetone. Comparison with standard simulations, performed with periodic boundary conditions, shows that such a mean field method can reproduce the same structural and thermodynamical properties at low computational costs and represents a valid alternative for simulating solute-solvent systems, like solutions of large biomolecules. [ABSTRACT FROM AUTHOR]

In this paper we investigate the equilibrium properties of magnetic dipolar (ferro-) fluids and discuss finite-size effects originating from the use of different boundary conditions in computer simulations. Both periodic boundary conditions and a finite spherical box are studied. We demonstrate that periodic boundary conditions and subsequent use of Ewald sum to account for the long-range dipolar interactions lead to a much faster convergence (in terms of the number of investigated dipolar particles) of the magnetization curve and the initial susceptibility to their thermodynamic limits. Another unwanted effect of the simulations in a finite spherical box geometry is a considerable sensitivity to the container size. We further investigate the influence of the surface term in the Ewald sum -- that is, due to the surrounding continuum with magnetic permeability μ[SUBBC] - on the convergence properties of our observables and on the final results. The two different ways of evaluating the initial susceptibility, i.e., (1) by the magnetization response of the system to an applied field and (2) by the zero-field fluctuation of the mean-square dipole moment of the system, are compared in terms of speed and accuracy. [ABSTRACT FROM AUTHOR]

Quality control is an important factor for manufacturing companies looking to prosper in an era of globalization, market pressures, and technological advance. The functionality and product quality cannot be guaranteed without this important aspect. Manufactured parts have deviations from their nominal (CAD) shape caused by the manufacturing process. Thus, geometric inspection is a very important element in the quality control of mechanical parts. We have focused here on the profile inspection of non-rigid parts which are widely used in the aeronautic and automotive industries. Non-rigid parts can have different forms in a free- state condition compared with their nominal models due to residual stress and gravity loads. To solve this problem, dedicated inspection fixtures are generally used in industry to compensate for the displacement of such parts for simulating the use state in order to perform geometric inspections. These fixtures and the inspection process are expensive and time-consuming. Our aim is therefore to develop an inspection method which eliminates the need for specialized fixtures by acquiring a point cloud from the displaced part using a contactless measuring system such as optical scanning and comparing it with the CAD model for the identification of deviations. Using a non-rigid registration method and finite element analysis, we will numerically inspect the profile of a non-rigid part. To do so, a simulated displacement is performed using an improved definition of boundary conditions for simulating unfixed parts. In this paper, we will apply an improved method on two industrial non-rigid parts with free-form surfaces simulated with different types of displacement, defect, and measurement noise. [ABSTRACT FROM AUTHOR]

In this paper, we propose a single-lane cellular automata (CA) traffic model which takes into account the disorder in the length and the maximal speed of the vehicles (i.e. slow and fast) to study the satisfaction rate of the fast vehicles (i.e. the number of vehicles that run with their desired speed) with open boundary conditions in the case of a chain of one entry; where is the injecting rate of vehicles independent of their nature and is the extracting rate. The slow vehicles are injected with the conditional probability , where and is the concentration of the slow vehicles. It is found that for the low value of the injecting rate and for the high extraction rate , the satisfaction rate takes higher values. It also depends on the concentration of the slow vehicles injected on the road. Furthermore, we have shown that, in the case when , the satisfaction rate undergoes a transition from the maximal value to the minimal one and it takes a value near to zero in the case of . We have also found that the satisfaction rate depends strongly on the probability of overtaking, also the phase diagrams () are established for the different values of the slow vehicles concentrations . [ABSTRACT FROM AUTHOR]

Transverse vibration vertical to middle surface of thin plate is a prevalent problem. This paper presents a vibration differential equation under accurate boundary conditions with elastic theory and vibration theory. The equation is used in identifying the vibration characteristics of the thin plate. Using analytic method, the rectangular plate taken as an example, the complete simulation calculation was performed. As a result, the relationships between vibration natural frequency and geometrical sizes are given, effects which the plate length and the semi-sinusoid number along the plate length direction have on the frequency are obtained. Moreover, effects under two boundary conditions which half-sinusoid number has on the frequency are compared. [ABSTRACT FROM AUTHOR]

This paper proposes a different method for calculating a sound field diffracted by a rigid barrier based on the integral equation method, where a virtual boundary is assumed above the rigid barrier to divide the whole space into two subspaces. Based on the Kirchhoff-Helmholtz equation, the sound field in each subspace is determined with the source inside and the boundary conditions on the surface, and then the diffracted sound field is obtained by using the continuation conditions on the virtual boundary. Simulations are carried out to verify the feasibility of the proposed method. Compared to the MacDonald method and other existing methods, the proposed method is a rigorous solution for whole space and is also much easier to understand. [ABSTRACT FROM AUTHOR]

In the charge simulation method, the scattered wave is represented by a linear combination of electromagnetic waves radiated from fictitious sources which are arranged inside the scattering body. The singularities of the scattered wave are the true sources from which the scattered wave is radiated. Therefore, the arrangement of fictitious sources will be affected by the location of singularities of the exact solution. This paper treats the scattering by a perfectly conducting cylinder of electromagnetic waves radiated from a line source. Singularities of the exact solution are located by a simple method, making use of the taking the location of singularities into consideration is proposed. Numerical calculations of the residual error of the boundary condition are performed for an elliptic cylinder. The results show the effectiveness of the source arrangement. Calculations of the electric field distribution and scattering pattern are done by making use of the arrangement for the elliptic cylinder and a square cylinder. The fundamental properties of the line source scattering are clarified. [ABSTRACT FROM AUTHOR]

Summary: This paper discusses the formulation and the numerical performance of a fully implicit algorithm used to integrate a rate‐dependent model defined within a breakage mechanics framework. For this purpose, a Generalized Backward Euler (GBE) algorithm has been implemented according to two different linearization strategies: The former is derived by a direct linearization of the constitutive equations, while the latter introduces rate effects through a consistency parameter. The accuracy and efficiency of the GBE algorithm have been investigated by (1) performing material point analyses and (2) solving initial boundary value problems. In both cases, the overall performance of the underlying algorithm is inspected for a range of loading rates, thus simulating comminution from slow to fast dynamic problems. As the viscous response of the breakage model can be recast through a viscous nucleus function, the presented algorithm can be considered as a general framework to integrate constitutive equations relying on the overstress approach typical of Perzyna‐like viscoplastic models. [ABSTRACT FROM AUTHOR]

Insulator boundaries like electrode contacts, interfaces, and surfaces play decisive roles for the electric field distributions in high-voltage direct-current (HVDC) insulation. Well-known examples are charging effects at injecting and blocking electrode contacts, and at interfaces or surfaces. Reliable modeling of boundaries and interfaces poses a challenge and can be crucial for the quality of the resulting field distributions in HVDC equipment, but is in practice often put in second place of priority in simulation models. This paper emphasizes the macroscopic boundary conditions and related issues for electrical transport and illustrates their relevance with simple examples. Importance is attached to an appropriate compromise between physical generality and practical usability for simulations in the development process of HVDC insulation systems. [ABSTRACT FROM AUTHOR]

Guided waves are used for the non-destructive evaluation in automotive and aerospace industries. There is a trend leaning away from isotropic materials to the manufacturing based on composites. However, the elastic wave dynamics in such materials is considerably more complicated. Much effort has been committed to the calculation of guided waves' dispersion curves in composites. Lots of methods and tools are available, but it becomes difficult when there are more than one hundred layers. In this paper the calculation of dispersion diagrams and mode shapes using the stiffness matrix method is demonstrated. Boundary conditions are implemented into the stiffness matrix method that allow for the separate tracing of the various mode families. Shear horizontal modes are modeled with the transfer matrix method without facing any numerical instability. It is elucidated just how the occurrence of the mode families depends on the system's symmetry and wave propagation direction. As a result, the robustness and reliability of guided wave modeling by using the stiffness method is improved, and more information about the modes is yielded. This is demonstrated on exemplary layups of the fiber reinforced polymer T800/913, with up to 400 layers. Referencing is made against results from DISPERSE® (Imperial College London, London, UK) for selected cases. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to introduce the concept of observability for distributed hyperbolic systems evolving in spatial domain Ω. It consists of the reconstruction of the initial conditions, on a subregion Γ of ∂Ω, that the initial state and speed are to be observed between two prescribed functions given only on the boundary subregion Γ. We give some definitions and properties of this kind of observability and we describe two approaches to solve this problem which the first is based on subdifferential techniques and the second one uses the Lagrangian multiplier method. This last approach leads to an algorithm which is implemented numerically and illustrated through an example and numerical simulation. [ABSTRACT FROM AUTHOR]

Due to the compliance and geometrical defects of composite parts, gaps exist between assembly components after the preassembly. Assembly requirements impose to fill these gaps to eliminate any unexpected internal stresses. Although it is identified as a problematic and expensive nonadded value stage, a gap measurement is still needed. This paper develops a numerical process for gap prediction before the assembly step. After the assembly components are scanned in a specified configuration, finite element meshes are created using the scanned data and the shape variations of each component caused by constraints and forces in different configurations are evaluated by finite element analysis. Assembly gaps are finally assessed by assembling the simulated preassembly shapes of all components. The feasibility of the proposed method is proved by an experiment. [ABSTRACT FROM AUTHOR]

In the present work, we consider a parabolic convection‐diffusion‐reaction problem where the diffusion and convection terms are multiplied by two small parameters, respectively. In addition, we assume that the convection coefficient and the source term of the partial differential equation have a jump discontinuity. The presence of perturbation parameters leads to the boundary and interior layers phenomena whose appropriate numerical approximation is the main goal of this paper. We have developed a uniform numerical method, which converges almost linearly in space and time on a piecewise uniform space adaptive Shishkin‐type mesh and uniform mesh in time. Error tables based on several examples show the convergence of the numerical solutions. In addition, several numerical simulations are presented to show the effectiveness of resolving layer behavior and their locations. [ABSTRACT FROM AUTHOR]

Abstract: This paper proposes a novel time domain numerical scheme based on a modified finite‐difference time‐domain (FDTD) method for electromagnetic interference (EMI) analysis of braided cable networks. In this method, a reasonable physical boundary condition is constructed by a transfer impedance model, while the spatial fields can be applied by way of adding incentive items into the transmission line equations. Besides, the full‐wave finite‐difference time‐domain(2, 4) method with thin wire model, transmission line equation and the modified nodal analysis are combined in order to solve cable‐interconnect line network transient responses in the problem of field‐line‐circuit union simulation. This method has good agreements with HSPICE. In addition, the method is used successfully in analyzing a cable‐interconnect network with different shielding characteristics. [ABSTRACT FROM AUTHOR]

This paper describes the performance of the Regional Atmospheric Modeling System (RAMS) in simulating a winter drought event, based on two different forcing datasets. We ran EC (ERA-Interim reanalysis data as initial and lateral boundary forcing conditions) and FNL (NCEP-FNL reanalysis data) simulations for the 2008/2009 winter drought event to quantify the impact of any uncertainty in the different initial and lateral boundary forcing data on regional model outputs. The response of the winter mean atmospheric states to the variations in the initial and lateral boundary conditions was investigated on the basis of these simulation results. The spatio-temporal features of precipitation from the EC and FNL runs closely resembled those measured from the Global Summary Of the Day (GSOD) observations, although the EC run data outperformed the FNL run data in both their spatial distribution patterns and precipitation values. The water vapor flux values explain how the differences in the precipitation values between the EC and the FNL runs were generated, whereas temperature values were not sensitive to any changes in forcing data. The model results from these runs also slightly overestimated temperature on both spatial and temporal scales. For the tropospheric atmospheric data recorded at the Fuyang Meteorological Station in Anhui Province, neither the time series nor the statistical analyses showed any evidence of superiority between the two different driver datasets compared with radiosonde data. However, on closer inspection, the influence of different initial and lateral boundary conditions on modeling the tropospheric atmospheric data appeared to be evident. [ABSTRACT FROM AUTHOR]

Abstract: To use single‐column models (SCMs) as a research tool for parameterization development and process studies, the SCM must be supplied with realistic initial profiles, forcing fields, and boundary conditions. We propose a new technique for deriving these required profiles, motivated by the increase in number and scale of high‐resolution convection‐permitting simulations. We suggest that these high‐resolution simulations be coarse grained to the required resolution of an SCM, and thereby be used as a proxy for the true atmosphere. This paper describes the implementation of such a technique. We test the proposed methodology using high‐resolution data from the UK Met Office's Unified Model, with a resolution of 4 km, covering a large tropical domain. These data are coarse grained and used to drive the European Centre for Medium‐Range Weather Forecast's Integrated Forecasting System (IFS) SCM. The proposed method is evaluated by deriving IFS SCM forcing profiles from a consistent T639 IFS simulation. The SCM simulations track the global model, indicating a consistency between the estimated forcing fields and the true dynamical forcing in the global model. We demonstrate the benefits of selecting SCM forcing profiles from across a large domain, namely, robust statistics, and the ability to test the SCM over a range of boundary conditions. We also compare driving the SCM with the coarse‐grained data set to driving it using the European Centre for Medium‐Range Weather Forecast operational analysis. We conclude by highlighting the importance of understanding biases in the high‐resolution data set and suggest that our approach be used in combination with observationally derived forcing data sets. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to derive a set of boundary conditions appropriate for simulating a wide variety of electrochemical and biophysical systems which are not necessarily electrically neutral. This is done by using the method of Green’s function, a generalization of the method of images, for solving the Poisson equation to provide boundary conditions for simulating electrochemical reactions involving ions confined between metal electrodes as well as ions in membranes enclosed between regions of aqueous electrolytes. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]