全文获取类型
收费全文 | 128篇 |
免费 | 16篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 71篇 |
综合类 | 15篇 |
金属工艺 | 5篇 |
机械仪表 | 7篇 |
建筑科学 | 2篇 |
矿业工程 | 1篇 |
能源动力 | 1篇 |
水利工程 | 2篇 |
石油天然气 | 2篇 |
无线电 | 28篇 |
一般工业技术 | 5篇 |
冶金工业 | 1篇 |
自动化技术 | 12篇 |
出版年
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 6篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 17篇 |
2013年 | 7篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 11篇 |
2009年 | 10篇 |
2008年 | 6篇 |
2007年 | 6篇 |
2006年 | 7篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有152条查询结果,搜索用时 859 毫秒
1.
高功率激光系统通过空间滤波和中继成像抑制自聚焦 总被引:3,自引:1,他引:2
孟昭贤 《激光与光电子学进展》1998,35(9):8-12
讨论了由光束自聚焦引起的细丝形成和光束分裂,为了克服聚焦造成的破坏要求在光束传播中采用中继成像和空间滤波。 相似文献
2.
沈园云 《上海轻工业高等专科学校学报》2010,(1):52-54
通过对SEL-351A的零(负)序方向元件分别在接地方向、相间故障方向及三相短路故障方向的理论分析,结合电测试数据阐述了对SEL-351A继电器方向元件的认识。 相似文献
3.
本文提出了基于蚁群优化算法的方向过电流保护整定配合的优化模型。首先说明了方向过电流保护的时间特性,然后建立了方向过电流整定优化模型。优化目标是所有主保护动作时间之和最小,考虑了主后备保护配合约束、保护动作时间约束、启动电流约束等。本文所提方向过电流保护为非线性优化问题,提出利用改进蚁群优化算法来求解该模型。最后本文利用IEEE8节点进行仿真分析,并与其他方法进行对比,说明本文所提算法在求解保护配合优化问题的优势。 相似文献
4.
薛玉善 《石油化工高等学校学报》1997,10(1):31-34,38
研究了如何利用工业控制微机 IPC 实现对变电所的保护与监控 ,较详细地介绍监控系统的结构组成特点 .实现了微机监控与全数字继电保护技术的有机结合 .运行表明 ,可增强变电所的控制保护功能 ,提高自动化程度 ,同时也提出了实际运行中存在的下位微机在恶劣环境中抗干扰等问题 相似文献
5.
This paper develops a novel fault protection system for AC microgrids having a multiple grounding system. Communication-supported digital relays which have different protection modules are used for this novel microgrid protection system. The protection modules in a digital relay have various functionalities to protect AC microgrids from various fault types, such as: low/high-impedance ground faults and short-circuits. To effectively use the developed novel microgrid protection system, the first step is to reconfigure different microgrid structures into a standard microgrid configuration having a multiple-grounding system through using delta/wye-grounded or wye-grounded/wye-grounded transformers. Then, a fast–dependable–adaptable (FDA) fault protection algorithm is developed to protect AC microgrids from faults occurring at trunk lines, common buses or branch lines. At an islanded operation mode of AC microgrids, by using digital relays, a new protection module is designed to detect, locate, and classify the faults occurring at trunk lines and common AC buses, while other protection modules can use the existing protection methodologies (e.g. directional/non-directional overcurrent protection principles, etc.) to detect and clear the faults at source branches or load branches of the microgrids. At a grid-connected operation mode, standard overcurrent protection modules are applied for the FDA fault protection system. Simulation and experiment results obtained from various fault cases at a real low-voltage AC microgrid have validated the effective operation of the FDA fault protection system. 相似文献
6.
7.
Y. Sekine M. Hatata T. Yoshida 《International Journal of Electrical Power & Energy Systems》1984,6(3):181-191
The development of digital protection in Japan is determined by an industry policy which gives priority to the commercial development of products aimed at replacing conventional protective relay equipment. As a result of this policy, the use of digital relays has spread through Japan faster than in other countries. Major efforts have been made to establish the reliability of the dedicated digital hardware and improve the economics of digital protection. Progress in the use of digital protection will lead, in the near future, to the totally computerized substation system. 相似文献
8.
利用复杂环网方向保护最优整定配合中最小断点集 (MBPS)的启发知识 ,将MBPS的计算归结为解不等式———欠定方程组 ,进而等价为 0— 1整数二次规划问题 ,基于基因遗传优化计算原理 ,首次提出了MBPS问题的基因遗传计算方法 ,降低了问题的计算复杂性。 相似文献
9.
Y. Sekine Y. Tamura H. Yamaguchi Y. Yamakoshi J. Makino 《International Journal of Electrical Power & Energy Systems》1982,4(1):62-70
The present status of microprocessor applications in various fields of electric power systems is summarized. Special attention is directed towards development trends in the protection field where microprocessor applications are expected to cope with the increasingly stringent requirements for electric power supply reliability. Also discussed are the history, roles, design philosophy and basic schemes of microprocessor-based protective relaying systems. Only recently has their application reached a practical stage after long-term study and repeated field tests. 相似文献
10.
Christos K. Datsikas Kostas P. Peppas Fotis I. Lazarakis George S. Tombras 《AEUE-International Journal of Electronics and Communications》2010,64(11):1094-1099
In this paper we present analytical expressions for the lower bounds of the error performance of dual-hop amplify-and-forward transmissions over independent and not necessarily identical Generalized-K fading channels. Using a tight upper bound for the end-to-end SNR, a novel expression for the probability density function is derived. Based on the abovementioned formula, tight lower bounds for the average bit error probability for a variety of modulation schemes are derived. In order to validate the accuracy of the proposed mathematical analysis, various numerical and computer simulation results are presented. 相似文献