The next generation of the public domain Storm Water Management Model (SWMM) code needs to be able to effectively use parallelization of 1000 + threads for high-resolution simulation of large urban drainage systems. W...
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ISBN:
(纸本)9783319998671;9783319998664
The next generation of the public domain Storm Water Management Model (SWMM) code needs to be able to effectively use parallelization of 1000 + threads for high-resolution simulation of large urban drainage systems. We propose a new explicit solution technique using a "no-neighbour" finite-volume algorithm. A no-neighbour algorithm is strictly limited in the design of its time/space discretization stencil to limit the communication bandwidth issues that typically cause codes to lose efficiency when applied over large numbers of parallel threads. Returning SWMM to an explicit solver creates a number of challenges for implementing the solution technique, but also raises some new possibilities for how the model can be used. In this work, we briefly describe the proposed algorithm and examine its performance in simulating a steep urban stream.
This paper develop a calculus model based on dedicated experiment for an innovative Reaction Control System (RCS) using hybrid rocket engine technology. Our RCS uses several hybrid micro-thrusters with their thrust mo...
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ISBN:
(纸本)9781479976973
This paper develop a calculus model based on dedicated experiment for an innovative Reaction Control System (RCS) using hybrid rocket engine technology. Our RCS uses several hybrid micro-thrusters with their thrust modulated by a separate control system. For RCS, each of the thrusters is able to burn a few minutes and its thrust is modulated within certain limits by controlling the oxidizer flow. These studies were presented in RAST 2013 and are based on our own experiments performed in Electromecanica Ploiesti. Based on this concept we achieve a calculation of the performances of the RCS and make a comparison between theoretical and experimental results. Conclusions and discussions will be focused on technological possibilities to improve RCS performance and possible areas of application of it.
In this Paper is introduced a time-discretization scheme for the numerical simulation of coupled thermomechanical. evolutions of SMA structures. A particular feature of this time-discretized problem is that its soluti...
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ISBN:
(纸本)0819462233
In this Paper is introduced a time-discretization scheme for the numerical simulation of coupled thermomechanical. evolutions of SMA structures. A particular feature of this time-discretized problem is that its solutions can be expressed as the solutions of a variational problem. This variational formulation allows one to study the existence and unicity of solutions. The approach presented is applied to simulate the propagation of a martensitic zone in a circular cylinder under traction.
In this paper, a coupled model of coating modification placed on a substrate is proposed. The model takes into account the different channels of stress effect on the evolution of coating and transition zone compositio...
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In this paper, a coupled model of coating modification placed on a substrate is proposed. The model takes into account the different channels of stress effect on the evolution of coating and transition zone composition. The coupled model of coated material modification by pulsed electron beam is formulated for the first time, with particular attention paid to the mutual influence of stresses arising from composition changes and diffusion transport. Examples of calculations for the Ta-TiN system are presented which demonstrate both qualitative and quantitative differences between coupled and uncoupled problems.
In this paper, an existing numerical algorithm for high-accurate computation of exact Carson formulas based on piecewise linear approximation is improved. Carson formulas are used for computing of per-unit-length (pul...
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ISBN:
(纸本)9781538632123
In this paper, an existing numerical algorithm for high-accurate computation of exact Carson formulas based on piecewise linear approximation is improved. Carson formulas are used for computing of per-unit-length (pul) self and mutual impedances of infinitely long parallel conductors. The proposed algorithm is based on piecewise quadratic approximation of kernel function and analytical integrations of approximated kernel function multiplied by the rest of two integrands. Using proposed algorithm, high-accurate results with desired computer machine n-digit accuracy can be easily obtained. Total number of sample points is significantly decreased with proposed algorithm in comparison with piecewise linear approximation. Results computed by two approximation methods are compared with high-accurate results computed by proposed numerical algorithm for large frequency range.
In this paper, the improved Chebyshev operational matrix method is proposed to solve a class of nonlinear Volterra integro-differential equation. The main characteristic behind this approach is that it reduces such pr...
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This article is based on ADAMS software platform to solve working space of the 4-DOF parallel mechanism. Design a kind of 4-DOF parallel mechanism and establish virtual prototype on ADAMS software platform. Then throu...
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ISBN:
(纸本)9783037857977
This article is based on ADAMS software platform to solve working space of the 4-DOF parallel mechanism. Design a kind of 4-DOF parallel mechanism and establish virtual prototype on ADAMS software platform. Then through enumeration three branched chain parameters combination, even without the premise of kinematics positive solution, we can solve it working space using the forward solving method and get the branched chain parameter with the reference point position corresponding numerical relations. It greatly simplifies the solution of the working space of parallel mechanism, is more advantageous to parameter optimization and trajectory planning of parallel mechanism.
Exchange and correlation holes are unique quantum concepts for understanding the nature of electron interactions based on quantum conditional probabilities. Among those, the exact exchange hole is of special interest ...
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Exchange and correlation holes are unique quantum concepts for understanding the nature of electron interactions based on quantum conditional probabilities. Among those, the exact exchange hole is of special interest since it is derived rigorously from first principles without approximations and is often modeled by approximate exchange expressions of density functional theory. In this work, the algorithm for the computation of the exact exchange hole for a given reference point is developed and implemented for molecular orbitals in Gaussian basis functions. The formulas include the spherical surface integral of a Gauss function. A computationally concise algorithm is proposed for obtaining the expansion coefficients of polynomial terms when the coordinate system is transformed from Cartesian to spherical. The result expression includes a number of cases of elementary integrals, the most difficult integral can be formed by linearly combining modified Bessel functions of the first kind. Direct applications of the standard approach using Mathematica and GSL are found to be inefficient and limited in the range of the parameters for the Bessel function. We propose an asymptotic function for the Bessel function. The relative error of the asymptotic function is in the order of 1e-16 with the first five terms of the asymptotic expansion. This new capability is used to explore the extent to which current popular model exchange holes resemble or differ from the exact exchange hole. Point-wise accuracy of the exchange holes for isolated atoms is important in local hybrid schemes, real-space models of static correlation and other. We find in this vein that among the models tested here only the BR89 exchange hole seems more or less suitable for that purpose, while better approximations are still very much on demand. Analyzing the deviations of model exchange holes from the exact exchange hole in molecules like H2 and Cr2 upon bond stretching reveals new aspects of the left-right
This thesis presents a simulation model for the dynamics of the human hand for application to an anthropomorphic prosthesis. The Articulated Body algorithm (ABA) algorithm was selected to model the dynamics of a tree ...
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This thesis presents a simulation model for the dynamics of the human hand for application to an anthropomorphic prosthesis. The Articulated Body algorithm (ABA) algorithm was selected to model the dynamics of a tree type robotic structure. The ABA is a numerical Newton-Euler based algorithm that solves the forward dynamics (obtaining the joint accelerations from the applied torques and forces) for a joint-link model. The main advantage of this algorithm resides in the analysis of the system link by link rather than the entire system analysis. This feature enables the implementation of a computationally efficient code and makes the algorithm generic enough to be applied to almost any robotic structure, with minimal additional effort. Furthermore, as the basic algorithm only handles serial structures, it was modified to include the effect of the gravity, loads on the end-effector, elasticity and damping at the joints, the generalization to tree-type structures, and, finally, the inclusion of impact analysis
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