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主要介绍了宽视角模式IPS和FFS的发展过程,并简要介绍了针对其自身存在的不足所进行的各种改进方法的原理、结构和改进效果,对各种方法的优缺点作出了评述。 相似文献
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一种全新的LCD宽视角技术 总被引:2,自引:1,他引:1
在边缘场开关模式向列液晶盒内,不论是在电极之间的液晶分子还是电极之上的液晶分子都可以在边缘场的驱动下转动,所以它具有比共面转换模式更好的透光率和宽视角特性。本文对这两种模式的结构和原理进行了比较,并介绍了针对其自身存在的不足所进行的各种改进方法的原理、结构和改进效果,对各种方法的优缺点做出了评述。 相似文献
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本文详细介绍了当前各种高频微波电路的封装模型,以及分析这些模型的场分析方法和分布网络分析方法。为了减少微波封装电路的插入和反射损耗,各种改进的加工技术被引入。 相似文献
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中分析了提高IEEE 802.11无线局域网吞吐量的各种方案,首先简要地介绍了介质接入控制协议,然后提出了六种改善吞吐量性能的方法,分别是改进介质接入协议、改变竞争窗口调节机制、MIB参数优化、调度策略、拥塞控制和Multi-MAC。最后,通过比较各种方法的性能和适应范围,提出了一种综合的解决方案。 相似文献
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Andrikopoulos I. Pavlou G. Georgatsos P. Karatzas N. Kavidopoulos K. Rothig L. Schaller S. Ooms D. Van Heuven P. 《Communications Magazine, IEEE》2001,39(5):146-155
IthACI has been a European project in the ACTS framework concentrating on fast layer 2 forwarding methods for IP traffic based on labeled flow mechanisms. The approach is also known as IP switching and is considered promising for enhancing IP performance. Several flavors of IP switching have been proposed by various vendors (e.g., IP switching by Ipsilon, Tag Switching by Cisco, ARIS by IBM, IPSOFACTO by the NEC), all of them different and not interoperable. IP switching has been adopted by the IETF under the umbrella of multiprotocol label switching (MPLS). Although MPLS has made remarkable progress, a number of issues remain largely open for further investigation. The scope of the IthACI project was to address such issues and propose solutions. The issues addressed were multicast, QoS, resource management, and mobility support in a multicast environment. IthACI conducted both theoretical and experimental work. Three network islands, each based on a different flavor of IP switching, were set-up and the interoperability of these different IP switching/MPLS flavors were investigated and demonstrated 相似文献
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LSI chips were developed that fit on a switching fabric using chip-to-chip optical interconnections; they have 10-Gb/s serial input and output ports, which facilitates the layout of optically interfaced switching element modules. A test switching module composed of these chips was operated at 10.2 Gb/s without bit errors. Ultrahigh-speed switching LSI chips have been developed for a future asynchronous transfer mode (ATM) switching system with an over-Tb/s capacity. Their serial input and output ports facilitate chip-to-chip optical interconnection. Cell-dropper and crosspoint-router LSI chips, composing the core of the switching element, were fabricated by using GaAs LSI technology. A test switching module composed of these chips was operated at 10.2 Gb/s without bit errors 相似文献
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寄生电感是影响功率管开关特性的重要因素之一,开关频率越高,寄生电感对低压增强型氮化镓高电子迁移率晶体管(GaN HEMT)的开关行为影响越深,使其无法发挥高速开关的性能优势。通过建立数学模型,理论分析了考虑各部分寄生电感后增强型GaN HEMT的开关过程,并推导了各阶段的持续时间和影响因素,然后通过建立双脉冲测试平台,对各部分寄生电感对开关特性的具体影响进行了实验验证。实验结果表明,寄生电感会使开关过程中的电流、电压出现振荡,影响开关速度和可靠性,并且各部分寄生电感对增强型GaN HEMT的开关过程影响程度不同,在实际PCB布局受到物理限制时,需要根据设计目标优化布局,合理分配各部分寄生电感以获得最优的开关性能。 相似文献
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本文根据国内外近十年来发表的光交换器件及光交换系统方面的文献对光交换技术的发展趋势加以综述。本文把光交换器件分为两大类,即光相关器件与光逻辑器件,并举例加以说明。对光交换系统则分为空分交换,时分交换及波分交换三大类予以叙述。并指出三维交换矩阵的开发可能是光交换技术独立于电子交换技术的一种新模式,利用光传输在时空上的特点,估计在近几年内光交换技术还会有新的突破。 相似文献
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We demonstrate polarization switching kinetics of poly(vinylidene fluoride-ran-trifluoroethylene) P(VDF-TrFE) nanodots depending on their sizes. Ferroelectric copolymer P(VDF-TrFE) nanodots, ranging from 20 to 250 nm in lateral size, were deposited on a Nb-doped SrTiO3 substrate by a position-controlled dip-pen nanolithography technique. Ferroelectric switching characteristics of P(VDF-TrFE) nanodots was investigated by piezoresponse force microscopy. Asymmetric switching behavior was observed during switching process, indicating that the threshold electric fields for polarization reversal were measured differently under the same conditions according to the switching polarity. Significantly, when the size of P(VDF-TrFE) nanodot approached around 250 nm, electric fields for polarization switching were compatible with those of the P(VDF-TrFE) thin film. We suggest that the electric fields required for polarization reversal of the P(VDF-TrFE) nanodots present asymmetric switching behaviors, and asymptotic behavior be observed as the nanodots increase in lateral size. 相似文献
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Reversible resistance change at room temperature by polarisation switching is reported in ferroelectric single crystals. Resistance switching up to six orders of magnitude in Mg-doped LiNbO/sub 3/ was found. The resistance change is caused by the polarisation switching and increases with Mg concentration. Based on these results, continuous switching properties and memory behaviours were demonstrated. 相似文献
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Nonlinear Sagnac interferometer switch and its applications 总被引:5,自引:0,他引:5
Ultrafast all-optical switching based on the optical Kerr effect in a Sagnac interferometer which consists of a dichroic polarization-maintaining fiber coupler and dispersion-shifted polarization-maintaining fiber loop is reported. This nonlinear Sagnac interferometer switch has the advantage of high stability originating from completely balanced interfering arms. In addition, because dispersion-shifted fibers were used, increases in switching power and switching time were prevented. Moreover, polarization fluctuation was completely suppressed due to the all-polarization maintaining fiber configuration. The required switching power for complete switching was measured to be 1.8 W for a 200-m-long fiber. All-optical time division demultiplexing and logic operations, including inversion and operation, using the nonlinear Sagnac interferometer switch were successfully demonstrated at 5 Gb/s 相似文献
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聂世刚 《电子产品可靠性与环境试验》2006,24(2):21-25
对加固计算机用开关电源的可靠性设计进行了系统的探讨。结合开关电源的原理.对影响其可靠性的因素和元器件的选用原则进行了阐述,着重分析了加固计算机用开关电源的可靠性设计:电应力设计、保护电路设计、热设计、电磁兼容性设计、安全性设计和三防设计。其目的在于提高加固计算机用开关电源的可靠性。 相似文献
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The dynamic switching characteristics of high-power GaAs Schottky and silicon p-i-n rectifiers are studied at various temperatures. Devices were first characterized to measure forward and reverse I-V, C-V, reverse breakdown voltage, and reverse-recovery performance. The same devices were characterized for turn on and turn off in switching circuits designed to study the dynamic switching performances under hard- and soft-switching conditions at different temperatures. Advanced two-dimensional (2-D) mixed device and circuit simulations were used to study the internal plasma dynamics under boundary conditions imposed by the circuit operation. It is shown that for hard-switching applications, GaAs Schottky power rectifiers exhibit significantly reduced switching power losses compared to silicon p-i-n rectifiers. For soft-switching applications, there is not a significant difference in the switching power losses for these two devices. Diode performance at elevated temperatures is measured and simulated, and temperature dependencies of switching and conduction power losses are analyzed 相似文献