基于Simulation X的多轴转向系统功能安全仿真分析

基于ISO 26262《道路车辆功能安全》的标准要求,对特种车的多轴电液转向系统进行分析,以提高系统的安全性和可靠性。运用Simulation X软件建立详细的多轴特种车仿真模型,通过模拟故障模式注入进行仿真试验。对仿真结果和数据进行分析,评估得到故障的严重性、暴露度和可控性,从而确定相应的汽车安全完整性等级。基于故障注入仿真的汽车功能安全分析方法,在系统早期设计阶段可以作为评估架构安全性的重要手段。

Numerical Simulation of the Settling Flux of Biodeposition in a Bay with Cage Culture Through Similarity Theory and a Simplified Pollution Source

The settling flux of biodeposition affects the environmental quality of cage culture areas and determines their environmental carrying capacity.Simple and effective simulation of the settling flux of biodeposition is extremely important for determining the spatial distribution of biodeposition.Theoretically,biodeposition in cage culture areas without specific emission rules can be simplified as point source pollution.Fluent is a fluid simulation software that can simulate the dispersion of particulate matter simply and efficiently.Based on the simplification of pollution sources and bays,the settling flux of biodeposition can be easily and effectively simulated by Fluent fluid software.In the present work,the feasibility of this method was evaluated by simulation of the settling flux of biodeposition in Maniao Bay,Hainan Province,China,and 20 sampling sites were selected for determining the settling fluxes.At sampling sites P1,P2,P3,P4,P5,Z1,Z2,Z3,Z4,A1,A2,A3,A4,B1,B2,C1,C2,C3 and C4,the measured settling fluxes of biodeposition were 26.02,15.78,10.77,58.16,6.57,72.17,12.37,12.11,106.64,150.96,22.59,11.41,18.03,7.90,19.23,7.06,11.84,5.19 and 2.57 g d^(−1)m^(−2),respectively.The simulated settling fluxes of biodeposition at the corresponding sites were 16.03,23.98,8.87,46.90,4.52,104.77,16.03,8.35,180.83,213.06,39.10,17.47,20.98,9.78,23.25,7.84,15.90,6.06 and 1.65 g d^(−1)m^(−2),respectively.There was a positive correlation between the simulated settling fluxes and measured ones(R=0.94,P=2.22×10^(−9)<0.05),which implies that the spatial differentiation of biodeposition flux was well simulated.Moreover,the posterior difference ratio of the simulation was 0.38,and the small error probability was 0.94,which means that the simulated results reached an acceptable level from the perspective of relative error.Thus,if nonpoint source pollution is simplified to point source pollution and open waters are simplified based on similarity theory,the setting flux of biodeposition in the open waters can be simply and effectively simulated by the fluid simulation software Fluent.

On modeling approach for embedded real-time software simulation testing

Modeling technology has been introduced into software testing field. However, how to carry through the testing modeling effectively is still a difficulty. Based on combination of simulation modeling technology and embedded real-time software testing method, the process of simulation testing modeling is studied first. And then, the supporting environment of simulation testing modeling is put forward. Furthermore, an approach of embedded real-time software simulation testing modeling including modeling of cross-linked equipments of system under testing （SUT）, test case, testing scheduling, and testing system service is brought forward. Finally, the formalized description and execution system of testing models are given, with which we can realize real-time, closed loop, mad automated system testing for embedded real-time software.

DEVELOPMENT OF COMPUTER SIMULATION SOFTWAREON PHASE TRANSFORMATION DURING QUENCHING

A computer software to simulate the phase transformation during quenching is designed based on Avrami equation and Scheil additivity principle of incubation period. The isothermal transformation diagrams of supercooled austenite are described by cubic spline functions. This software is possess of a good graphic interface of Windows style, can simulate the whole process in austenite decomposition during continuous cooling. If the cooling rate was given, the fraction of various microstructures transformed of austenite decomposition during continuous cooling at any temperature can be calculated. The simulation results are checked with the quenching experiment of 45 steel. The results indicate that the simulation results are comparatively close to the experimental results.

Hierarchy-Based Team Software Process Simulation Model

According to the characteristic of Team Software Process （TSP）, it adopts a hierarchy-based model combined discrete event model with system dynamics model. This model represents TSP as form of two levels, the inner level embodies the continuity of the software process, the outer embodies the software development process by phases, and the structure and principle of the model is explained in detail, then formalization description of the model is offered. At last, an example is presented to demonstrate the simulation process and result. This model can simulate team software process from various angles, supervise and predict the software process. Also it can make the management of software development become more scientific and improve the quality of software.

Simulation of a Flexible Manufacturing System with AutoMod Software

A flexible manufacturing system (FMS) is a highly automated, complex system. Simulation is a well-proven method to design or analyze an FMS. Deployment of a radio frequency identification (RFID) system in FMS produces large volumes of RFID data streams, which provide valuable information to improve the operation of FMS. Different frameworks are presented in this paper regarding the use of RFID data streams in an FMS simulation. Simulations are performed with AutoMod software. Related technical details are also presented. The paper’s structure is complied as the following steps: step 1, the introduction of AMHS, FMS and AutoMod;step 2, FMS simulation using AutoMod software;step 3, simulation frameworks driven by RFID data streams;step 4, conclusion.

Application of 3-D numerical simulation software SRIFCAST to produce ductile iron castings

Based on a method using numerical simulation equations and their solution schemes for liquid metal flows andheat transfer during mold filling and the solidification process of casting, 3-D numerical simulation software SRIFCAST wascreated. This includes enmeshment of casting; velocity and temperature fields calculation; displaying iso-temperature lines;velocity vectors and 3-D temperature fields on a Windows 9x operating system. SRIFCAST was applied to produce soundcastings of automobile and diesel engines, and also to connect with microstructure simulation for ductile iron castings.

Component-based software reliability process simulation considering imperfect debugging

In view of the flaws of component-based software(CBS) reliability modeling and analysis,the low recognition degree of debugging process,too many assumptions and difficulties in obtaining the solution,a CBS reliability simulation process is presented incorporating the imperfect debugging and the limitation of debugging resources.Considering the effect of imperfect debugging on fault detection and correction process,a CBS integration testing model is sketched by multi-queue multichannel and finite server queuing model(MMFSQM).Compared with the analytical method based on parameters and other nonparametric approaches,the simulation approach can relax more of the usual reliability modeling assumptions and effectively expound integration testing process of CBS.Then,CBS reliability process simulation procedure is developed accordingly.The proposed simulation approach is validated to be sound and effective by simulation experiment studies and analysis.

Modeling and Simulation of Skid-mounted LNG Plants Using HYSYS Software

This study presents three kinds of skid-mounted plants, including single mixed refrigerant cycle (MRC), nitrogen expander cycle, and natural gas (NG) Claude cycle. Hysys simulation shows that single MRC is the most efficient cycle among the three. The specific power of single MRC liquefiers is 1485 kJ/kg, 15% higher than that of large liquefaction process. Considering the recovery of stranded-gas, commercial analysis suggests that the initial cost of LNG plants ranging from 1 to 100 m3 /day can be paid back in 2 to 4 years.

Simulation-Based Evaluation for the Impact of Personnel Capability on Software Testing Performance

This study presents a decision making process in three steps of knowledge management for test organization using process simulation and financial analysis. First, project cost assessment of test knowledge management process subjects to different project duration and number of staffs. Two knowledge management simulation models representing experienced personnel with knowledge sharing and inexperienced personnel with internal training respectively are employed to contrast test personnel capability. Second, performance evaluation of software testing process by different personnel capability is conducted to simulate system test using three project metrics, namely, duration, effort cost, and quality. Third, a comparative financial analysis is prepared to determine the best solution by return on investment, payback period, and benefit cost ratio. The results from three stages of finding are discussed to arrive at the final scenario. We provide a case study evaluating how software testing industry needs to build effective test organization with high quality personnel for sustainable development and improvement.

Software Simulation in GSM Environment and Hardware Implementation of Improved Multi-band Excitation Vocoder

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Software Architecture for Modeling and Simulation of Underwater Acoustic Information Systems

The simulation of underwater acoustic information flow is an important way to research sonar performance and its engagement effectiveness in the ocean environment.This paper analyzes the significance of modeling an open and sophisticated simulation software architecture by object-oriented method,and introduces the modeling processes and expression method of simulation architecture.According to the requirements of simulation system and the underwater acoustic information flow,the logical architecture of simulation software system is modeled by the object-oriented method.A use-case view captured the system requirements.The logical view shows the logical architecture of software system.The simulation software is decomposed into the loose coupling constituent parts by layering and partitioning the packages for maintainability.The design patterns enabled the simulation software to have good expansibility and reusability.The simulation system involving multi-targets and multi-sonar is developed based on the architecture model.Practices show that the model meets the needs for simulating an open and sophisticated system.

Simulation-based Graphic Method for Dynamic System Modeling

The first step for engineering students to understand the practical system is to describe the system,which means to establish the mathematic model for the considered system.However,traditional mathematical modeling techniques are not readily assimilated by students,because the traditional modeling needs to obey the complicated physical laws for different engineering areas and requires a highly iterative process.In this paper,the simulation-based graphic modeling method is introduced to help students model the system and improve their performance in engineering education.The results from the questionnaire indicate that the simulation-based graphic method can help students to do the modeling of the system and improve their performance compared to the traditional ways.

TikTak: A Scalable Simulator of Wireless Sensor Networks Including Hardware/Software Interaction

We present a simulation framework for wireless sensor networks developed to allow the design exploration and the complete microprocessor-instruction-level debug of network formation, data congestion, nodes interaction, all in one simulation environment. A specifically innovative feature is the co-emulation of selected nodes at clock-cycle-accurate hardware processing level, allowing code debug and exact execution latency evaluation (considering both protocol stack and application), together with other nodes at abstract protocol level, meeting a designer’s needs of simulation speed, scalability and reliability. The simulator is centered on the Zigbee protocol and can be retargeted for different node micro-architectures.

基于Plant Simulation的汽车内饰线运行参数优化方法研究

针对汽车内饰线易因开动率预估不准确导致实际产能与规划产能相差较大的难题,将二分法迭代优化与仿真分析相结合,提出了一种基于Plant Simulation的汽车内饰线运行参数优化方法。首先,根据汽车内饰线的工作原理及运行流程,利用Plant Simulation软件建立其仿真模型;其次,以预估开动率作为目标优化参数,通过二分法逐步产生新的预估开动率,根据规划产能更新生产节拍、工艺段速度和最佳滑板数等运行参数,利用仿真模型统计新参数作用下实际开动率和实际产能等指标,通过迭代逐步提升预估开动率与实际开动率的一致性,实现对汽车内饰线运行参数的优化;最后,以国内某新能源汽车内饰线的规划设计为例,证明了所提出优化方法的有效性。该研究可为汽车内饰线的产能分析及优化提供指导,具有较好的工程应用价值。