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51.
一种嵌入式TCP/IP的实现 总被引:3,自引:0,他引:3
针对许多小型嵌入式系统要求结构紧凑、开销小的TCP/IP协议栈的需求,提出一种可移植的非路由器TCP/IP原型的实现。该TCP/IP原型基于某种小型嵌入式系统,依据RFC1122兼容性规定,提供IP、ARP、TCP、UDP服务和Berkeley Socket编程接口。该实现代码短小,开销低,性能能够满足多数应用需求,具有较强的可移植性。 相似文献
52.
Minimum copper loss flux-weakening control of surface mounted permanent magnet synchronous motors 总被引:1,自引:0,他引:1
Jiunn-Jiang Chen Kan-Ping Chin 《Power Electronics, IEEE Transactions on》2003,18(4):929-936
This study presents a novel current loop design method capable of automatic flux-weakening control with minimum copper loss for surface mounted permanent magnet synchronous motors (SPMSM). The proposed current controller can automatically re-compute the d-axis current command to defer output voltage saturation. Consequently, the motor operations in the flux-weakening region are also contained in the stable operating region. Analysis results indicate that since the output voltage vector in the flux-weakening region produced by this controller is consistently on the boundary of the maximum output voltage vector allowed by the inverter, the corresponding flux-weakening current is the optimal value in the sense of minimum copper loss. This minimum copper loss design differs from the maximum output torque design and the constant power design of the flux-weakening control methods found in the literature. Experimental results further demonstrate the feasibility of the proposed current controller and its ability to maximize the speed range of the motor drive for a given inverter capacity. 相似文献
53.
Zukerman M. Wong E.W.M. Rosberg Z. Gyu Myoung Lee Hai Le Vu 《Communications Letters, IEEE》2004,8(2):116-118
We provide teletraffic models for loss probability evaluation of optical burst switching (OBS). We show that the popular Engset formula is not exact for OBS modeling and demonstrate that in certain cases it is not appropriate. A new exact model is provided. The various models are compared using numerical results for various OBS alternatives with and without burst segmentation. 相似文献
54.
建设工程质量保证体系存在的问题及对策 总被引:13,自引:2,他引:11
结合建筑业市场管理体制的改革及其发展态势,就建筑工程质量保证体系存在的问题作了阐述,从加强勘察设计资格的管理,完善监理法规等方面,提出了健全和完善质保体系的措施。 相似文献
55.
Chuang C.T. Chin K. Stork J.M.C. Patton G.L. Crabbe E.F. Comfort J.H. 《Solid-State Circuits, IEEE Journal of》1992,27(2):225-228
A detailed study on the leverage of high-f T transistors for advanced high-speed bipolar circuit applications is presented. It is shown that for the standard ECL (emitter-coupled logic) circuit, the leverage of high f T is limited by the passive resistors (emitter-follower resistor and collector load resistor) and wire delay, especially in the low-power regime. For the standard NTL (nonthreshold logic) circuit, the leverage is higher due to its front-end configuration and lower power supply value. As the passive resistors are decoupled from the delay path in various advanced circuits utilizing active-pull-down schemes, the leverage of high FT becomes more significant 相似文献
56.
Yan R.-H. Lee K.F. Jeon D.Y. Kim Y.O. Park B.G. Pinto M.R. Rafferty C.S. Tennant D.M. Westerwick E.H. Chin G.M. Morris M.D. Early K. Mulgrew P. Mansfield W.M. Watts R.K. Voshchenkov A.M. Bokor J. Swartz R.G. Ourmazd A. 《Electron Device Letters, IEEE》1992,13(5):256-258
The authors report the implementation of deep-submicrometer Si MOSFETs that at room temperature have a unity-current-gain cutoff frequency (f T) of 89 GHz, for a drain-to-source bias of 1.5 V, a gate-to-source bias of 1 V, a gate oxide thickness of 40 Å, and a channel length of 0.15 μm. The fabrication procedure is mostly conventional, except for the e-beam defined gates. The speed performance is achieved through an intrinsic transit time of only 1.8 ps across the active device region 相似文献
57.
质子和中子的单粒子效应等效性实验研究 总被引:1,自引:0,他引:1
通过实验方法确定了高能质子和中子引起的单粒子效应等效关系,实验中采用金箔散射法降低了质子束流强度,并利用热释光剂量计(TLD)进行质子注量的监测,采用新研制的存储器长线实时监测系统,进行了64K位至4M位的SRAM器件单粒子效应实验,确定了两种粒子引起单粒子效应等效关系。 相似文献
58.
59.
本文对弹药内弹道性能检验的传统方法存在的问题进行了分析,提出了一种新的检验方法,重点对新的检验方法的数学模型的建立过程进行了论述。并对数学模型的精度进行了分析、检验和验证。 相似文献
60.
A new priority management policy, aprescheduling policy, is proposed. This policy can be applied on any conventional concurrency control protocol to schedule a real-time transaction. Costly preemption is avoided by the prescheduling policy, and parsing dataset of a transaction is not needed. Three widely used conventional concurrency control protocols (dynamic two-phase locking, basic timestamp ordering, and optimistic) are incorporated with the prescheduling policy to form three real-time concurrency control protocols. Performance of the three protocols is evaluated from three different viewpoints: database management systems, protocols, and transaction. From a database management system viewpoint, we show the prescheduling policy can improve the performance of protocols by raising thevalid ratio and reducingrestart counts. In general, two-phase locking with the prescheduling policy performs the best in most cases and yields the best choice for concurrency control in a real-time application. Deciding factors that affect performance of each protocol are identified from protocol viewpoint. Some suggestions are given for writing a timely transaction from the aspect of transaction viewpoint. 相似文献