首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   201篇
  免费   33篇
  国内免费   4篇
化学   6篇
力学   10篇
数学   11篇
物理学   18篇
无线电   193篇
  2024年   2篇
  2023年   10篇
  2022年   5篇
  2021年   4篇
  2020年   10篇
  2019年   11篇
  2018年   5篇
  2017年   10篇
  2016年   8篇
  2015年   11篇
  2014年   15篇
  2013年   16篇
  2012年   19篇
  2011年   23篇
  2010年   9篇
  2009年   8篇
  2008年   10篇
  2007年   9篇
  2006年   9篇
  2005年   6篇
  2004年   7篇
  2003年   6篇
  2002年   2篇
  2001年   4篇
  2000年   6篇
  1999年   2篇
  1998年   3篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1993年   1篇
  1990年   2篇
排序方式: 共有238条查询结果,搜索用时 15 毫秒
111.
战术互联网的网络重组是在网络节点或通信链路发生故障,或受到安全威胁时,保证网络强壮性的重要手段之一。根据战术互联网特殊的移动网络环境,提出基于作战指挥原则的组织重组方法。仿真实验结果证明了这些方法的有效性。  相似文献   
112.
Partial shading causes power loss in a photovoltaic module by inducing a power mismatch within the module. This power loss can be significant in building‐applied and building‐integrated photovoltaic installations. Given the often repetitive nature of shade profiles in such applications, we propose to employ non‐reconfigurable or static configurations. We use our simulation tool to precompute static configurations, apply shading scenarios, such as a chimney or tree shade, and make a comparison between the energy yields of different static configurations, which includes that of a conventional module. We then identify the configuration characteristics that consistently yield a higher energy. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
113.
This paper presents a comprehensive mathematical model for integrated cell formation and inventory lot sizing problem. The proposed model seeks to minimize cell formation costs as well as the costs associated with production, while dynamic conditions, alternative routings, machine capacity limitation, operations sequences, cell size constraints, process deterioration, and machine breakdowns are also taken into account. The total cost consists of machine procurement, cell reconfiguration, preventive and corrective repairs, material handling (intra-cell and inter-cell), machine operation, part subcontracting, finished and unfinished parts inventory cost, and defective parts replacement costs. With respect to the multiple products, multiple process plans for each product and multiple routing alternatives for each process plan which are assumed in the proposed model, the model is combinatorial. Moreover, unreliability conditions are considered, because moving from “in-control” state to “out-of-control” state (process deterioration) and machine breakdowns make the model more practical and applicable. To conquer the breakdowns, preventive and corrective actions are adopted. Finally, a Particle Swarm Optimization (PSO)-based meta-heuristic is developed to overcome NP-completeness of the proposed model.  相似文献   
114.
An adaptive algorithm of fine synchronization for intermediate frequency architecture coherent optical orthogonal frequency division multiplexing (CO-OFDM) transmission system is proposed. The whole synchronization procedure is separated into two steps. In the first step, we use an auto-correlation-style algorithm to achieve the coarse symbol synchronization. In the second step, the proposed algorithm is used to achieve the adaptive fine synchronization. The merit of the proposed algorithm is that it can realize fine synchronization under different environments without adjusting the detect-threshold of timing metric in a dynamically reconfiguration network. And also the algorithm can implement in field-programmable gate array (FPGA) or other digital signal processing (DSP) chips easily. In this paper, the CO-OFDM model is analyzed in theory firstly. Secondly, an analysis on the performance of coarse synchronization algorithm used in this paper is made. Finally, the proposed fine synchronization algorithm is introduced in detail. The simulation experiment result demonstrates that the proposed algorithm achieves fine synchronization under different signal noise ratio (SNR) conditions after 6 fiber-spans transmission.  相似文献   
115.
Modular robots consist of many identical units (or atoms) that can attach together and perform local motions. By combining such motions, one can achieve a reconfiguration of the global shape of a robot. The term modular comes from the idea of grouping together a fixed number of atoms into a metamodule, which behaves as a larger individual component. Recently, a fair amount of research has focused on algorithms for universal reconfiguration using Crystalline and Telecube metamodules, which use expanding/contracting cubical atoms.From an algorithmic perspective, this work has achieved some of the best asymptotic reconfiguration times under a variety of different physical models. In this paper we show that these results extend to other types of modular robots, thus establishing improved upper bounds on their reconfiguration times. We describe a generic class of modular robots, and we prove that any robot meeting the generic class requirements can simulate the operation of a Crystalline atom by forming a six-arm structure. Previous reconfiguration bounds thus transfer automatically by substituting the six-arm structures for the Crystalline atoms. We also discuss four prototyped robots that satisfy the generic class requirements: M-TRAN, SuperBot, Molecube, and RoomBot.  相似文献   
116.
The main motivation of this paper is related to the lack of a high-level design flow for field-programmable gate array (FPGA) partial dynamic reconfiguration management. Our contribution consists in proposing a high-level add-on methodology to the Xilinx’s design flow for dynamic partial reconfiguration (DPR). The main objective is to give an abstract view of the developed application in order to facilitate the designer task. The suggested design flow offers an application-centric view on dynamic reconfiguration designs, which permits simplifying the optimisation and generation of such designs. A new formulation of the reconfigurable modules’ mapping process is put forward. This allows a design space exploration so as to find the convenient number of reconfigurable regions and their sizes as well as the reconfiguration sequence. A new tool was proposed to support our methodology by allowing creating and synthesising graphical models of the developed application. We introduce a new block diagram to represent this latter and a sequence model that can be used for the design optimisations. To validate the proposed DPR design environment, two application examples are given at the end of the paper. They demonstrate the usefulness of the suggested models and methods.  相似文献   
117.
介绍了一种使用动态局部重构技术设计可重构FIR数字滤波器的方法,是一种注重面积效率高、灵活性强,允许动态插入或删除局部模块的方法,并在Xilinx Virtex-4 FPGA上实现.这种设计方法比传统的FIR滤波器的设计方法具有占用资源更少、重构时间更短、高速灵活性等优点.  相似文献   
118.
通用化、小型化、高可靠性、使用便捷是对大型军用复杂武器装备外场保障设备的通用要求;近年来,随着网络技术、嵌入式计算机技术特别是“可重构计算”技术的发展,可重配置的嵌入式测控系统开发技术成为当前研究的一个热点;文章对该项技术进行了深入研究,并结合飞机子系统外场测试的实际情况,提出并设计实现了一种分布式可重配置航空测控系统;与传统的集中控制测试系统相比较,该系统的体积小、重量轻,使用方便,通过可重配置技术使得测控系统可适应不同的测试需求;该系统的设计实现对军用复杂武器装备外场检测设备设计具有很好的借鉴意义。  相似文献   
119.
复杂系统健康管理是测试技术、人工智能和信息技术的综合应用,它是由故障检测、故障隔离和重构(FDIR)技术演变而来,并且运用先进的推理技术,将管理功能从FDIR扩充到系统自主重构、系统资源重组,以安全、可靠地实现系统任务目标,减少维修人力和保障费用.文中对健康管理在机载雷达中的应用进行了研究.  相似文献   
120.
For a graph G=(V,E), the k-dominating graph Dk(G) of G has vertices corresponding to the dominating sets of G having cardinality at most k, where two vertices of Dk(G) are adjacent if and only if the dominating set corresponding to one of the vertices can be obtained from the dominating set corresponding to the second vertex by the addition or deletion of a single vertex. We denote the domination and upper domination numbers of G by γ(G) and Γ(G), respectively, and the smallest integer ε for which Dk(G) is connected for all kε by d0(G). It is known that Γ(G)+1d0(G)|V|, but constructing a graph G such that d0(G)>Γ(G)+1 appears to be difficult.We present two related constructions. The first construction shows that for each integer k3 and each integer r such that 1rk?1, there exists a graph Gk,r such that Γ(Gk,r)=k, γ(Gk,r)=r+1 and d0(Gk,r)=k+r=Γ(G)+γ(G)?1. The second construction shows that for each integer k3 and each integer r such that 1rk?1, there exists a graph Qk,r such that Γ(Qk,r)=k, γ(Qk,r)=r and d0(Qk,r)=k+r=Γ(G)+γ(G).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号