共查询到20条相似文献，搜索用时 78 毫秒
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电厂主汽温被控对象是一个大惯性、大迟延、非线性且对象变化的系统,基于BP神经网络的PID控制,利用神经网络的自学习、非线性和不依赖模型等特性实现PID参数的在线自整定,充分利用PID和神经网络的优点。用一个多层前向神经网络,采用反向传播算法,依据控制要求实时输出Kp、Ki、Kd,依次作为PID控制器的实时参数,代替传统PID参数靠经验的人工整定和工程整定,以达到对大迟延主汽温系统的良好控制。对这样一个系统在MATLAB平台上进行仿真研究,仿真结果表明基于BP神经网络的自整定PID控制具有良好的自适应能力和自学习能力,对大迟延和变对象的系统可取得良好的控制效果。 相似文献
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云计算下虚拟信息资源大数据特征集成调度 总被引：1，自引：0，他引：1
《科技通报》2015,(10)
研究大数据环境下基于云计算的虚拟企业信息系统构建和调度模型,通过对云计算环境下的虚拟企业信息资源特征集成调度,提高数据访问和管理能力。传统的集成调度方法采用层次分析法,通过粒子群(PSO)算法进行虚拟企业信息管理存储系统的任务调度,存在信息管理迟滞等问题。提出一种基于模糊循环堆栈控制的虚拟企业信息管理资源信息特征集成调度算法,把虚拟企业信息管理资源信息调度网络的能量节点进行模糊循环堆栈控制设计,得到虚拟企业信息管理资源信息调度配置的权值,实现对虚拟企业信息管理资源的大数据特征融合和集成。仿真实验表明,该算法能有效提高虚拟资源大数据特征集成调度成功率,执行时间缩短,具有较高的应用价值。 相似文献
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本文以飞思卡尔智能车比赛为例利用MC9S12XS128单片机控制的智能小车路径识别系统,研究智能车最优的控制算法。PID自整定的方法是对传统PID控制的改进,采用模糊控制器实现对PID参数的自整定,快速准确的对智能车进行转向控制。 相似文献
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本项设计一种电路简单、自动化程度高、安全快捷的红绿灯自动识别装置。介绍了以JN5148芯片为无线传感器网络实现数据无线传输的方法,每个路口的Zigbee端定时向空间发送一个数据包,当车载中的接收端接收到数据包时,便能通过ID字节判断出该数据包指示的是哪个路口的红绿灯信息,然后进行车辆与路口距离的检测并将信息通过OLED显示,从而实现了对红绿灯信息的自动识别。 相似文献
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以太网数据包采集主要目的是对已经封装好的数据本身所携带的标志信息进行分析和处理,并通过对每个数据包的监控来达到清除无用包和有害包,提高网络吞吐量,保护网络安全的目的。 相似文献
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基于Matlab GUI的PID参数整定平台开发 总被引：1，自引：0，他引：1
《中国科技信息》2021,(16)
PID控制算法是最早出现的控制算法,其应用领域较为广泛,在过程控制与运动控制中得到广泛的应用。在实际生产应用中,PID系统的应用核心便是PID参数整定,传统形式的PID整定效果欠佳,操作繁琐。在此借助计算机辅助软件MATLAB中提供的Simulink与GUI平台进行PID参数整定的仿真实验平台,初步确定PID参数,随后应用于现场控制,其操作简便,校正效果直观。 相似文献
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三容水箱液位控制系统具有过程控制中动态过程的一般特点：大惯性、大时延、非线性。NetCon系统提供了一个完整的NCS快速开发和实时控制解决方案,可以快速建立被控对象模型,进行控制系统的设计、仿真、实现以及组态、监控、调试等工作。本文以NetCon系统为基础,利用MATLAB工具箱设计了自整定模糊PID控制算法,并在三容水箱实际系统中得到了应用,取得了较好的控制效果。 相似文献
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以太网数据包采集主要目的是对已经封装好的数据本身所携带的标志信息进行分析和处理，并通过对每个数据包的监控来达到清除无用包和有害包，提高网络吞吐量，保护网络安全的目的。 相似文献
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A research group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol-a chemical found in the skins of red grapes in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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Active biological molecules functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery disease diagnosis therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction. 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献