An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynam...
详细信息
ISBN:
(纸本)0897919858
An original computational technique to generate close-to-equilibrium dense polymeric structures is proposed. Diffusion of small gases are studied on the equilibrated structures using massively parallel molecular dynamics simulations running on the Intel Teraflops (9216 Pentium Pro processors) and Intel Paragon (1840 processors). Compared to the current state-of-the-art equilibration methods this new technique appears to be faster by some orders of magnitude. The main advantage of the technique is that one can circumvent the bottlenecks in configuration space that inhibit relaxation in molecular dynamics simulations. The technique is based on the fact that tetravalent atoms (such as carbon and silicon) fit in the center of a regular tetrahedron and that regular tetrahedrons can be used to mesh the three-dimensional space. Thus, the problem of polymer equilibration described by continuous equations in molecular dynamics is reduced to a discrete problem where solutions are approximated by simple algorithms. Practical modeling applications include the construction of butyl rubber and ethylene-propylene-dimer-monomer (EPDM) models for oxygen and water diffusion calculations. Butyl and EPDM are used in O-ring systems and serve as sealing joints in many manufactured objects. Diffusion coefficients of small gases have been measured experimentally on both polymeric systems, and in general the diffusion coefficients in EPDM are an order of magnitude larger than in butyl. In order to better understand the diffusion phenomena, 10,000 atoms models were generated and equilibrated for butyl and EPDM. The models were submitted to a massively parallel molecular dynamics simulation to monitor the trajectories of the diffusing species. The massively parallel molecular dynamics code used in this paper achieves parallelism by a spatial-decomposition of the workload which enables it to run large problems in a scalable way where both memory cost and per-timestep execution speed scale line
This paper presents two design patterns useful for parallel computations of master-slave model. These patterns are concerned with task management and parallel and distributed data structures. They can be used to help ...
详细信息
ISBN:
(纸本)0780336763
This paper presents two design patterns useful for parallel computations of master-slave model. These patterns are concerned with task management and parallel and distributed data structures. They can be used to help address the issues of data partition and mapping, dynamic task allocation, and load balancing in parallel programming with the benefit of less programming efforts and better program structures. The patterns are described in object-oriented notation, accompanied with illustrative examples in C++. We also provide our experience in applying these patterns to two scientific simulation programs simulating Ising model and plasma respectively. Since master-slave model is a widely used parallel programming paradigm, the design patterns presented in this paper have large potential application in parallel computations.
In digital circuit simulation hidden opportunities for concurrent execution of models often exist, arising from the propagation delay associated with the generation of output events by the circuit models. An event pre...
详细信息
ISBN:
(纸本)9780818677861
In digital circuit simulation hidden opportunities for concurrent execution of models often exist, arising from the propagation delay associated with the generation of output events by the circuit models. An event prediction algorithm is developed to identify such parallelism, increasing the simulation execution rate. The algorithm uses an event prediction network and simulates circuits asynchronously and deadlock free, while honoring the preemptive semantics associated with digital circuit simulation.
Software project management skills are becoming an important component of software engineering education. Software engineers working in teams need to carefully plan and coordinate their efforts in order to be successf...
详细信息
Software project management skills are becoming an important component of software engineering education. Software engineers working in teams need to carefully plan and coordinate their efforts in order to be successful. Unfortunately, most universities provide inadequate education in software project management. Most use lecture-based approaches which provide the necessary steps in software project management, but are deficient in providing the students with hands-on experience. Software project simulation provides a bridge between course-based and hands-on experience. It provides an interactive environment of repeatable exercises. It also provides a medium for measurable evaluation of student performance which can be used to customize the education process to fit the needs of individual students. Our work focuses on using system dynamics modeling for simulating software development activities because of its ability to dynamically represent relevant project attributes in the software development process. A system dynamics model of the incremental software development process has been developed and validated. This paper describes a process for utilizing this system dynamics model to create simulation environments suitable for addressing specific education objectives. Benefits and guidelines for use of a tool of this kind are provided. Our experience with using this tool in a large class is also described.
This paper describes the parallelization of a diagnostic fault simulator for stuck-at faults in sequential circuits. The parallelization is performed by partitioning the diagnostic equivalence classes obtained by simu...
详细信息
This paper describes the parallelization of a diagnostic fault simulator for stuck-at faults in sequential circuits. The parallelization is performed by partitioning the diagnostic equivalence classes obtained by simulating the first few test vectors of the test set. The partitions are then simulated in parallel, independent of each other for the remaining vectors. Thus there is no communication overhead. Results on performance speedup and diagnostic resolution loss are provided for the ISCAS 89 benchmark circuits.
A PSPICE compatible equivalent electrical model amenable to AC simulation of a CMOS analog hearing aid system at the block level consisting of an AGC (Automatic Gain Control) Preamplifier, Class AB output buffer and e...
详细信息
A PSPICE compatible equivalent electrical model amenable to AC simulation of a CMOS analog hearing aid system at the block level consisting of an AGC (Automatic Gain Control) Preamplifier, Class AB output buffer and electroacoustic tranducers of a basic CMOS hearing aid system using a behavioral modeling approach has been carried out. The data for the behavioral description of all the CMOS subcircuits is extracted from the SPICE simulation using process and design parameters of a three micron low voltage CMOS technology. The proposed technique is adaptable to the characterisation of programmable hearing aids.
This paper presents an adaptive priority traffic control approach which uses a dynamic buffer allocation scheme, and an adaptive priority queuing technique for handling the delay-sensitive traffic in ATM networks. The...
详细信息
This paper presents an adaptive priority traffic control approach which uses a dynamic buffer allocation scheme, and an adaptive priority queuing technique for handling the delay-sensitive traffic in ATM networks. The former adjusts the buffer size based on the real traffic demand, while the latter adaptively change the priority. The simulation results show that diverse delay-sensitive traffic achieve satisfactory performance through our approach. It may fulfill the emerging needs of guaranteed services.
simulation under Virtual Reality is the front edge of simulation technology. And also, it provide a new method for integrated multisensor simulation under a united environment. In the past, most simulation and animati...
详细信息
ISBN:
(纸本)0780336763
simulation under Virtual Reality is the front edge of simulation technology. And also, it provide a new method for integrated multisensor simulation under a united environment. In the past, most simulation and animation systems utilized in robotics, which are concerned with simulation of the robot and its environment without simulation of sensors, have difficulty in handling robots that utilize sensory feedback in their operation. Currently, navigation and planning heavily depended on perception has already been mainstream in robotics. Sensor fusion plays a important role in navigation. So, it is important to do research on simulators which deal with multisensor, integrated robot simulation. In this paper, we present a system, which is integrated multisensor feedback under virtual reality, and describe the system architecture and dynamic behavior simulation model. Meanwhile, we also give the difference of simulation between VR system and general 2D system. We choice the mobile robot THMRIII as original source, and give it dynamic simulation model. In order to simulate the uncertainty of ultrasonic sensor, we identify three kinds of uncertainty, and give a ultrasonic sensor model based on fuzzy theory. The sensor simulation algorithm is presented. At the end of this paper, we conclude with discussion of sensor fusion under 3D visualized integrated environment.
暂无评论