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   109篇
  免费   0篇
化学工业   11篇
轻工业   1篇
无线电   75篇
一般工业技术   5篇
冶金工业   3篇
自动化技术   14篇
  2022年   1篇
  2021年   1篇
  2018年   1篇
  2016年   1篇
  2015年   2篇
  2013年   2篇
  2012年   1篇
  2011年   1篇
  2010年   2篇
  2009年   2篇
  2008年   1篇
  2007年   2篇
  2006年   2篇
  2005年   2篇
  2004年   7篇
  2003年   5篇
  2002年   6篇
  2001年   5篇
  2000年   2篇
  1999年   7篇
  1998年   6篇
  1997年   6篇
  1996年   6篇
  1995年   2篇
  1994年   4篇
  1993年   1篇
  1992年   3篇
  1991年   2篇
  1990年   3篇
  1988年   4篇
  1987年   4篇
  1986年   2篇
  1985年   4篇
  1983年   1篇
  1980年   1篇
  1979年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1969年   2篇
  1967年   1篇
排序方式: 共有109条查询结果,搜索用时 15 毫秒
1.
Lightpath (wavelength) routing in large WDM networks   总被引:11,自引:0,他引:11  
We address the problem of efficient circuit switching in wide area optical networks. The solution provided is based on finding optimal routes for lightpaths and the new concept of semilightpaths. A lightpath is a fully optical transmission path, while a semilightpath is a transmission path constructed by chaining together several lightpaths, using wavelength conversion at their junctions. A fast and practical algorithm is presented to optimally route lightpaths and semilightpaths taking into account both the cost of using the wavelengths on links and the cost of wavelength conversion. We prove that the running time of the algorithm is the best possible in the wide class of algorithms allowing linear algebraic operations on weights. This class encompasses all known related practical methods. Additionally, our method works for any physical realization of wavelength conversion, independently whether it is done via optoelectronic conversion or in a fully optical way  相似文献   
2.
A parallel version of quicksort on a CRCW PRAM is developed. The algorithm uses n processors and a linear space to sort n keys in the expected time O(log n) with large probability.  相似文献   
3.
Wireless ATM networks require efficient mobility management to cope with frequent mobile handoff and rerouting of connections. Although much attention has been given in the literature to network architecture design to support wide-area mobility in public ATM networks, little has been done to the important issue of user mobility estimation and prediction to improve the connection reliability and bandwidth efficiency of the underlying system architecture. This paper treats the problem by developing a hierarchical user mobility model that closely represents the movement behavior of a mobile user, and that, when used with appropriate pattern matching and Kalman filtering techniques, yields an accurate location prediction algorithm, HLP, or hierarchical location prediction, which provides necessary information for advance resource reservation and advance optimal route establishment in wireless ATM networks  相似文献   
4.
An architectural approach that meets high bandwidth requirements by introducing a communication architecture based on lightpaths, optical transmission paths in the network, is introduced. Since lightpaths form the building block of the proposed architecture, its performance hinges on their efficient establishment and management. It is shown that although the problem of optimally establishing lightpaths is NP-complete, simple heuristics provide near optimal substitutes for several of the basic problems motivated by a lightpath-based architecture  相似文献   
5.
The effect of screw wear on the performance of a 2.5 in. diameter extruder is studied with the aid of computer simulations. The effect of progressively increasing flight clearance on the extrusion of low density polyethylene, polypropylene and nylon 6/6 is presented. The remedial effect of increased screw speed and its side effects on melting behavior, solids content, extrudate temperature and power consumption are also described.  相似文献   
6.
7.
A survey of quality of service in IEEE 802.11 networks   总被引:9,自引:0,他引:9  
Developed as a simple and cost-effective wireless technology for best effort services, IEEE 802.11 has gained popularity at an unprecedented rate. However, due to the lack of built-in quality of service support, IEEE 802.11 experiences serious challenges in meeting the demands of multimedia services and applications. This article surveys 802.11 QoS schemes, including service differentiation in the MAC layer, admission control and bandwidth reservation in MAC and higher layers, and link adaptation in the physical layer, designed to meet these challenges by providing the necessary enhancements for the required QoS. Furthermore, the article addresses issues that arise when end-to-end QoS has to be guaranteed in today's pervasive heterogeneous wired-cum-wireless networks. Among these challenges, protocol interoperability, multihop scheduling, full mobility support, and seamless vertical handoff among multiple mobile/wireless interfaces are specifically addressed.  相似文献   
8.
An algorithm for efficient communication between neighbours in multihop radio networks is proposed. The algorithm guarantees a bound on the transmission efficiency in a radio channel for arbitrary topology. The algorithm can be embedded in protocols for solving basic network problems such as broadcast, multicast, leader election, or finding shortest paths. The problem of bounded-time broadcasting utilizing the proposed algorithm is addressed. A polynomial solution in which the process of spreading information over the network is viewed as the expansion of a wave caused by a point of disturbance is presented. The broadcast originates at a source node and is accomplished in repeated transmission periods, emulating a wave progressing away from the source. The algorithm is used to select a subset of potential transmitters in each period, so that a tightly bound proportion of potential receivers receive the transmission without collisions, guaranteeing a high level of spatial reuse in the broadcast process  相似文献   
9.
Mobile number portability allows a mobile subscriber to switch operators without changing his/her telephone number. This article describes and analyzes mobile number portability routing mechanisms and their implementation costs. We first describe the signaling relay function (SRF)-based solution for call related and noncall related routing. Then we describe the intelligent network (IN)-based solution for call related routing. Cost recovery issues for number portability are discussed in this article from a technical perspective. We note that rules for cost recovery also depend on business and regulatory factors that vary from country to country.  相似文献   
10.
Modeling frame synchronization for UMTS high-speed downlink packet access   总被引:2,自引:0,他引:2  
Third Generation Partnership Project (3GPP) specification TR 25.950 proposed high-speed downlink packet access for the Universal Mobile Telecommunication System (UMTS). In this mechanism, an active set of cells is defined for every user equipment (UE) communication session. The cell with the best wireless link quality (called the serving cell) in the active set is selected for communication with the UE. When the wireless link quality of the old serving cell degrades below some threshold, a new serving cell in the active set is selected to continue the communication session. Our previous work proposed a high-speed downlink packet access (HSDPA) overflow control scheme with four frame synchronization algorithms to switch the serving cell, and formally proved the correctness of the scheme. We propose an analytic model to investigate the performance of these frame synchronization algorithms, and show how the user movement patterns affect the control message delivery costs of these algorithms.  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