MATLAB语言在异步电机仿真分析中的应用

本文应用MATLAB/Simulink模块库或直接应用MAT-LAB语句进行软件编程,对异步电机的稳态及动态特性进行了仿真分析,表明MATLAB语言可作为电机仿真分析中的一种方便、快捷、有力工具。     

Simulation as a tool for optimizing memory accesses on NUMA machines

Due to the inherent non-uniformity in the memory system, programmers and users of non-uniform memory access (NUMA) machines have to take special care of the memory performance of their applications. This paper discusses a variety of potential improvements with respect to cache misses, cache invalidations, and inter-node communication. This study is based on the simulation tool SIMT, which models the memory hierarchy in detail and is capable of providing complete, accurate information about all dynamic memory references. This information can be used to analyze the memory access behavior of applications and thereby forms the basis for any optimization with respect to memory accesses.     

Multi-period dynamic supply contracts with cancellation

This paper considers a class of multi-period dynamic supply contracts in which a buyer orders a product from a supplier in each period and the supplier allows the buyer to cancel a portion of an outstanding order with penalty during a planning horizon. We assume that both the buyer and the supplier have common knowledge. We first characterize the buyer's ordering and canceling policy that minimizes his expected cost during the planning horizon. We also characterize the supplier's optimal production policy under a very mild assumption on the costs of production and storage. Based on this structure, we then use simulation to show how the supplier chooses cancellation costs that minimize her expected cost during the planning horizon. Our simulation shows that both the buyer and the supplier would benefit from the contract.     

Market micro-structure analysis by multiagent simulation in X-Economy -- comparison among technical indices

We are developing an agent and server library referred to as X-Economy, by which we can execute multiagent simulations and network games for financial and economic systems. To this end, we analyzed the characteristics of network games in a financial context and compared them with traditional ones. X-Economy has also provided a new research direction in market micro-structure analysis. We executed several kinds of multiagent simulations for technical traders (indices) and obtained non-trivial suggestions regarding the relationship between the market randomness and the effectiveness of technical indices. For instance, the performance of complex technical indices seemed to deeply depend on the characteristics and nature of a market when a market became complex, i.e. it moved far from the Wiener process.     

Verifying Concurrent Data Structures by Simulation

We describe an approach to verifying concurrent data structures based on simulation between two Input/Output Automata (IOAs), modelling the specification and the implementation. We explain how we used this approach in mechanically verifying a simple lock-free stack implementation using forward simulation, and briefly discuss our experience in verifying three other lock-free algorithms which all required the use of backward simulation.     

Technology Evaluation of Hydrogen Light-Duty Vehicles

This study analyzed candidate hydrogen-fueled vehicles for near and long-term use associated with their efficiency, performance, and emissions. Various types of hydrogen-fueled vehicles were assessed using Argonne National Laboratory's Powertrain System Analysis Toolkit vehicle simulation model. These include hythane- and hydrogen-fueled internal combustion engines (ICEs), hydrogen-fueled hybrid electric propulsion, and direct hydrogen fuel cells. Vehicle sizes and configurations, consistent with the available component models/data, were simulated to compare efficiency and emissions with baseline conventional vehicles. The simulations provided salient information on the vehicle characteristics, performance, and efficiency, as functions of operating conditions on standard driving cycles. It was found that substantial gains in fuel economy can be achieved through hybridization both for conventional and fuel cell vehicles. When hybridized, hydrogen ICE configurations achieve similar fuel economy to gasoline counterparts. The results also confirm that ICE hybrid electric vehicles (HEV) achieve higher fuel economy than fuel cell configurations and comparable results with fuel cell HEV. Comparison of efficiency results for various driving cycles further indicates that cycles with low power demand are most suited for hybrid operations.     

Simultaneous Removal of Phenol and Nitrate in an Anaerobic Bioreactor

Phenol and nitrate are two major pollutants simultaneously occurring in several industrial wastewaters. In this study, a 110-day gradual enrichment of an anaerobic culture has been carried out at 25°C in an anaerobic bioreactor for continuously treating a synthetic wastewater containing 600?mg/L phenol and 430?mg/L?NO3?–N. The results showed that the enriched culture can utilize phenol as a sole electron donor and nitrate as a sole electron acceptor. At the end of the enrichment (on Day 110), 93.3% of phenol and 98.0% of NO3?–N were simultaneously removed at a hydraulic retention time of 20.25?h in the anaerobic bioreactor. The removal of 1?g?NO3?–N required about 3.19?g chemical oxygen demand as the electron donor. Batch tests further revealed that cresol, nitrophenol, and monochlorinated phenol (MCP) could exert detrimental influences on the treatment abilities of the enriched culture. However, the inhibitory effects of cresol were impermanent, as compared to those of nitrophenol and MCP. In order to operate the anaerobic bioreactor steadily, high concentrations of cresol should be diluted before being fed while the existence of nitrophenol and MCP in the bioreactor should be avoided.     

Large-Eddy Simulation of High Reynolds Number Turbulent Flow Past a Square Cylinder

Flow past a square cylinder at a Reynolds number of 21,400 has been studied numerically using the large-eddy simulation technique. A dynamic subgrid-scale stress model has been used for the small scales of turbulence. The time- and span-averaged axial and transverse velocities in the downstream of the cylinder are in good agreement with the experimental results. The distribution of turbulent normal and shear stresses is also well predicted. The coherent and incoherent components of turbulent fluctuations at some specified phases have been separated and their relative magnitudes downstream of the cylinder have been compared. The comparison shows more coherence in the near wake than the far wake, while the coherent and incoherent components are of comparable magnitude in the far wake. The far wake shows irregular phase-averaged structures.     

基于有限元方法的双定子永磁同步发电机齿槽转矩研究

永磁电机不通电时永磁体与有槽电枢铁心之间相互作用,产生齿槽转矩,引起永磁电机低速起动困难。为了有效地削弱双定子低速稀土永磁同步发电机齿槽转矩,在目前国内外永磁电机齿槽转矩研究的基础上,建立了双定子低速稀土永磁同步发电机齿槽转矩的解析表达式,针对表达式中影响齿槽转矩大小的因素,利用有限元方法进行了仿真分析,得到了影响齿槽转矩大小的变化规律,为发电机最优设计提供重要依据。     

A singleton failures semantics for Communicating Sequential Processes

This paper defines a new denotational semantics for the language of Communicating Sequential Processes (CSP). The semantics lies between the existing traces and failures models of CSP, providing a treatment of non-determinism in terms of singleton failures. Although the semantics does not represent a congruence upon the full language, it is adequate for sequential tests of non-deterministic processes. This semantics corresponds exactly to a commonly used notion of data refinement in Z and Object-Z: an abstract data type is refined when the corresponding process is refined in terms of singleton failures. The semantics is used to explore the relationship between data refinement and process refinement, and to derive a rule for data refinement that is both sound and complete. Received October 2001 Revised September 2002, February 2003, June 2004 and October 2005 Accepted November 2005 by I. J. Hayes