预喷射对生物柴油发动机排放性能的仿真分析

研究预喷射对生物柴油发动机排放性能问题,针对能源紧缺与排放法规,为了进一步降低柴油机排放,采用生物柴油替代石化柴油方法进行研究,利用GT-Suite软件建立了生物柴油发动机仿真模型,通过台架试验验证了仿真模型的准确性.对发动机在2200r/min时,采用不同生物柴油掺混比、预喷射量和预喷-主喷间隔对发动机排放和扭矩影响,建立了仿真优化方案,进行仿真的结果表明,生物柴油掺混比为5％、预喷量为5％、预喷-主喷间隔为10.CA方案对NOx和Soot排放与扭矩最优,表明上述研究对生物柴油发动机进一步优化预喷射方案具有借鉴意义.     

基于联合仿真技术的UUV发动机动力学研究

为了研究UUV热动力发动机的动力学性能,通过对发动机的剖析,应用UG软件建立了发动机的简化仿真模型,导入ADAMS软件环境中建立了发动机虚拟样机,并利用相关物理试验对样机进行了验证,然后结合MATLAB/Simulink软件建立了具有多个可控外部参数的发动机联合仿真动力学模型。通过联合仿真得到发动机关键部件的运动曲线和不同工况下关键部件之间的相互作用力,指出了降低相互作用力的途径,并联合ANSYS/Ls_dyna对主要传动零件进行了强度校核。仿真结果表明,联合仿真模型具有UUV热动力发动机的特点,对研究各参数与发动机动力学性能之间的关系以及结构优化均具有积极意义,为UUV热动力发动机的设计与改进提供了一种现代化方法和有效的依据。     

废气再循环–可变几何截面涡轮增压柴油发动机 燃气双环系统建模及协同控制

针对废气再循环(EGR)与可变几何截面涡轮增压(VGT)的柴油发动机,作者联合考虑其燃油动力转速调节回路与气体回路,提出了内外双环稳定动态反馈的控制策略.其中,内环回路是利用Lyapunov函数设计的控制器,控制燃油质量流量来跟踪柴油发动机转速;外环回路则设计EGR–VGT控制器,跟踪气体回路的进排气歧管压力及压气机空气质量流量,并克服了柴油发动机建模中的不稳定零动态问题.同时,研究了气体流量与EGR和VGT阀门开度之间的关系,通过设计流量开度转换模块实现了两者控制的转换.最后,通过专业发动机软件AMESim与仿真软件MATLAB/Simulink的联合仿真试验,验证了该控制策略对柴油发动机燃油动力转速调节与气体回路控制的有效性.     

发动机曲柄连杆机构动力学仿真分析平台研究

在研究发动机结构问题时,为更广泛地对各种类型发动机曲柄连杆机构进行快速准确的运动学和动力学性能分析,提出了搭建曲柄连杆机构动力学仿真分析平台,基于机械系统仿真分析软件MSC.ADAMS的动力学分析原理,并采用平台流程实现了对某发动机曲柄连杆机构的多刚体和多柔体系统动力学仿真分析,得到了零部件的运动学和动力学优化结果,为机构的优化设计以及后续整机振动噪声的分析预测提供了依据,同时也验证了仿真分析流程的合理性,为建立数字化发动机的整机仿真分析平台提供了借鉴.     

柴油机扭矩输出特性的动力学模拟

使用MSCNatran有限元软件与MSCAdams多体动力学计算软件对某8缸V型发动机的曲轴系统进行动力学仿真,比较气缸在不同发火次序下曲轴的扭矩输出特性,确定发动机合理的发火次序。为设计提供依据．     

基于BP网络的航空发动机传感器硬故障检测

研究了航空发动机传感器的故障类型.针对传感器硬故障本身的特点,使用神经网络训练并建立发动机传感器模型,依据建立的模型线计算出传感器正常运行时上下阈值,最后将计算出来的阈值嵌入到工控机中,进行航空发动机传感器在线实时硬故障检测的仿真模拟.整个算法软件采用C++语言编写,占用资源少、运行速度快、精度高、实时性强,根据仿真图形分析,该算法软件能够准确地监测航空发动机传感器的故障.     

基于刚-柔混合模型的300T铁水车动力学仿真

为保证300t铁水车的安全运输,采用刚-柔混合动力学模型研究了该车的动力学性能.以I-DEAS软件为柔性体仿真平台,ADAMS/Rail软件为多刚体系统仿真平台,给出了创建刚-柔混合动力学模型的技术路线,采用在系统外将所关心的对象柔性化的建模方法建立了某公司研制的特种车辆-300t铁水运输车的刚-柔混合动力学模型.基于刚-柔混合模型的动力学仿真结果表明:弹性轨道对该车运行平稳性和曲线通过性能的影响大于柔性转向架对运行平稳性和曲线通过性能的影响.因此,对这类特种车辆进行动力学仿真应采用弹性轨道.当计算规模很大无法考虑转向架的柔性效应时,仅使用弹性轨道所获得的结果也能达到相当的精度.     

基于ADAMS软件的发动机悬置系统仿真分析

设计合理的发动机动力总成悬置系统,对改善乘员乘坐的舒适性以及延长发动机及其它部件的使用寿命都起着非常重要的作用.以桑塔纳汽车发动机悬置系统的测最数据为依据,在ADAMS软件中建立了其六自由度的动力学仿真模型,应用ADAMS/Vibration模块对悬置系统进行了动力学仿真分析,发现该系统竖直方向隔振效果差,并对此进行了优化.再对优化后的结果进行试验,证明经优化后动力总成悬置系统的隔振性能有了明显改善.此方法可应用于发动机总成设计初期,通过仿真的方法,实现参数的优化.     

一种高压共轨柴油发动机的轨压控制算法

设计了一种应用于高压共轨柴油发动机的PID轨压控制算法,以解决传统轨压算法控制复杂性和计算效率的问题。本算法简化了处理工况,并针对柴油发动机特性对PID控制器进行了多项改进,并用其统一的处理运行工况下的轨压计算。通过仿真实验对算法进行了验证,实验结果证明本算法对输入发动机信号和轨压期望具有良好的跟随性和运行效率,并且轨压控制较为平稳,其波动幅度不超过1%,基本符合高压共轨柴油发动机正常工作的需要。     

航空发动机控制系统故障检测仿真平台研究

通过分析目前航空发动机控制系统故障检测仿真软件缺乏通用性、模块化的问题,将发动机建模、故障检测和组件开发技术相结合,提出并设计了航空发动机控制系统故障检测仿真平台,分析该平台的设计目标、软件总体架构与主要功能.针对某型涡扇发动机为研究对象,给出传感器与执行机构典型故障的模式分析和检测逻辑,在飞行包线设计点进行仿真计算.实践表明该平台能够准确实时仿真发动机控制系统典型故障,具有功能可靠、易扩展、工程化程度高的特点.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.