中间卸载式长距离带式输送机驱动控制策略

针对中间卸载式带式输送机在卸载滚筒的驱动控制不当时可能出现滚筒打滑、跳带、输送带松弛、物料堆积、中部和头部电动机功率负载不平衡等问题,提出利用Belt Analyst软件对2种中间卸载式输送机驱动控制方案进行仿真,并通过比较得出最优的多电动机协调方案:离主控制较近的驱动采用扭矩跟踪,相距较远的采用速度跟踪并延迟启动,延迟启动条件设为检测到2%额定带速较合理。为更好地减小输送带的动张力和消除输送带的黏弹性振动,分析比较了匀加速、组合匀加速、组合摆线、组合抛物线等4种速度控制方式的控制曲线和动载荷,得出合理的启动曲线应具有的特征:启动的时间足够长,以保证启动加速度小于规定的加速度;启动加速度较小且没有突变,因为动张力的大小主要取决于加速度最大值。     

长距离带式输送机三点驱动控制系统研究

针对目前带式输送机驱动控制研究忽略了输送带的黏弹性对启动过程的影响、不能较好地模拟带式输送机启动过程的问题,分析了输送带的力学特性及黏弹性模型,并选用Voigt模型对输送带进行建模;利用Simulink与AMESim联合仿真平台,分别对带式输送机的机械部分和电动机控制部分进行建模。根据直接转矩控制原理和协同控制思想设计了长距离带式输送机三点驱动控制系统。该系统采用主从控制策略,以头部驱动电动机为主驱动,其余为从驱动,控制带式输送机头部、中部、尾部3个驱动的输出转速和转矩,使得带式输送机以预设速度曲线平稳启动并运行。仿真结果表明,由于输送带的黏弹性作用及带式输送机加速度不断变化,导致带式输送机的负载转矩不断变化,但带式输送机头部、中部、尾部3个驱动均能很好地跟踪预设的启动速度,说明三点驱动控制系统能够很好地控制带式输送机的启动和运行过程。     

带式输送机张紧系统自适应控制策略研究

科技的进步导致对能源需求量增长,长距离、大运量带式输送机的增量越来越大。张紧系统是带式输送机的重要组成部分,输送带保持合理的张力范围是保证煤矿安全生产和带式输送机稳定运行的关键。通过对输送带驱动系统建立力学模型,得到输送带驱动不打滑最小张力,并通过与保持托辊间输送带合理下垂张力比对,得到输送带最小张力计算方法;并根据带式输送机运行过程分析,得出输送带张紧系统自适应控制策略工作环境及其控制方法,建立了基于模糊PID控制的输送带张力控制模型;通过Simulink对张紧系统自适应控制模型仿真,得到不同载荷下张紧力响应曲线。所建立张紧系统自适应控制方法响应快、超调小,能够满足输送带时变载荷自适应调节的使用需求。     

AMT驱动带式输送机的建模与仿真

研究带式输送机优化速度特性,针对带式输送机驱动装置效率低、物料运量不可变、造价高的问题,根据电控机械式自动变速器传动效率高、实现有级调速、成本低.为了提高系统的传动效率,改进驱动装置,提出一种以AMT作为传动系统,通过电子控制单元的操作实现自动驱动带式输送机进行起动的方案.分析方案的可行性,建立了AMT和带式输送机的动力学模型.利用Matlab工具,建立了AMT驱动带式输送机的仿真模型,并对起动过程进行仿真.仿真结果表明,使输送带的最大加速度和速度满足要求,且方案能保证离合器的优化特性,提高了传动效率,的确为方案的实现提供了理论支持.     

井下运输系统带式输送机防打滑分析

带式输送机是煤矿井下主要的运输设备,针对某矿主斜井输送机运行时出现打滑问题,依据输送机布置以及运行情况进行分析,发现其原因主要是输送机载荷过大、驱动滚筒制动器未能及时动作、输送带与滚筒间摩擦系数降低、输送带张力过小以及输送的原煤中含水率过大等.根据输送机的打滑情况,建议在转向鼓的侧面安装制动器,并通过与原来的逆止器一起...     

带式输送机一体化控制装置研制

针对带式输送机在缩带、张紧、卷带过程中存在作业程序多、劳动强度大的问题,设计了一种带式输送机一体化控制装置。该装置中的液压自动张紧装置完成带式输送机在运行过程中的自动张紧及工作面推移时的输送带储带任务;液压自动卷带装置把储带仓的输送带卷曲并移出带式输送机,再运至井上进行处理。实际应用表明,该装置运行效果较好,顺利完成了输送带的缩带、卷带工作。     

带式输送机液压自动拉紧装置的设计

文章在分析常见的带式输送机拉紧装置优缺点的基础上,设计了ZYL型液压自动拉紧装置,详细介绍了装置的结构组成、工作原理及特点。该自动拉紧装置采用液压技术,将拉紧油压转换为活塞杆的轴向移动,带动拉紧小车纵向移动以改变拉紧行程,拉紧行程的改变又转换为带式输送机拉紧滚筒的移动,从而改变输送带的张力,保证了输送带与拉紧滚筒间所必需的摩擦力;设置了电控箱控制液压拉紧装置的运行,可实现就地控制和远程控制。实际应用表明,该液压自动拉紧装置运行稳定、性能可靠、维护调整方便,可满足带式输送机各种运行工况的需要。     

矿用带式输送机智能监测系统研究

针对矿用带式输送机运行过程中存在的托辊、滚筒等关键部件与输送带摩擦发热,钢丝绳芯输送带内部损伤与撕裂,运行功耗大等问题,设计了一种矿用带式输送机智能监测系统。该系统包括基于弱磁检测法的钢丝绳芯输送带损伤监测系统、基于红外热成像温度检测法的带式输送机关键部件故障诊断与预警系统和基于视觉检测法的煤流监测、异物监测、胶带撕裂监测及人员安全监测系统,详细介绍了各系统的实现原理。对钢丝绳芯输送带内部损伤识别及带式输送机关键部件故障诊断预警进行了实验验证,结果表明该系统对钢丝绳芯输送带损伤识别的准确率约为98%,且可准确识别带式输送机关键部件故障并发出预警。     

长距输送系统中的力学模型研究与应用

本文通过分析长距离输送系统中胶带输送机的张力特性、负载特性和机械特性,建立了其速度和加速度驱动模型并进行了优化.针对某矿长距离胶带输送机采用变频器调速驱动的实际工程应用,系统采用可编程控制器作为主从控制器,实现了多驱动器之间的协调控制,使胶带输送机在轻载及重载工况下,均能有效控制其柔性负载的软起动/软停车动态过程,实现各驱动之间的功率平衡,降低直接起动/快速停车过程对机械和电气系统的冲击,大大增加了输送系统的安全性和可靠性.     

多机驱动带式输送机功率平衡控制方法

针对采用液体黏性软启动装置的多机驱动带式输送机在启动过程中各电动机功率不平衡的问题,提出了一种多机驱动带式输送机功率平衡控制方法:利用电流预测算法预测电动机电流,以提高控制响应速度;根据各电动机之间的预测电流偏差,通过比例微分控制算法调节液体黏性软启动装置所配用的控制泵给定频率,进而改变电动机电流,使各电动机电流差控制在一定范围内。现场应用结果表明,在带式输送机空载和重载启动时,该方法均能对电动机过大电流进行抑制调节,实现带式输送机平稳启动和功率平衡。     

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.