经由受激拉曼绝热过程高效产生太赫兹

论证了在三能级系统中经由受激拉曼绝热过程产生太赫兹,分析了基本模型和泵浦激光与太赫兹产生相干的三能级的理论,并应用在横向激励二氧化碳激光光学泵浦重水分子中,可以产生波长为385 μm的太赫兹辐射.产生的太赫兹脉冲功率表现为蒸汽压的函数,并得到了最高太赫兹功率.该技术提供了一种鲁棒性非常好的产生太赫兹的方法.     

契比雪夫加权应用被动合成孔径处理算法研究

提出了将契比雪夫加权应用于被动合成孔径处理算法。被动合成孔径技术对小孔径基阵沿直线运动接收到的信号进行合成处理,从而达到虚拟大孔径基阵方位分辨力效果。将契比雪夫加权应用于线阵合成孔径前后波束图的指向性研究,对主瓣宽度变化予以合理解释。理论分析结合仿真验证表明,被动合成孔径处理算法应用契比雪夫加权可以在给定的旁瓣高度要求下获得等旁瓣级,等旁瓣级下可提高对弱目标信号的检测分辨能力。     

一种高可靠性电极式水位传感器模型研究

河流水位测量是水利信息化工程中的重要环节。据调查,现用于河流的水位传感器大都存在受测量环境影响大、可靠性不强、不利于系统集成等缺陷。电极式水位传感器是一种应用于锅炉汽包水位检测的传感器,采用数字测量方式,具有不受环境参数影响、稳定可靠等优点。通过对其感应方式进行改进,采用交变窄脉冲驱动电极,克服了传感器电极电化腐蚀,使其适用于河流的水位测量。经长时间实地验证,模型正确可靠,具有实用价值。     

新型模入通道保护模块在阀冷系统中的应用

针对目前换流阀冷却控制系统中,西门子模拟量输入通道易损坏的现状,介绍了一种新型的模拟量输入通道保护模块。该模块能有效避免高压直流输电工程中换流阀冷却系统模拟量输入通道易损坏的问题,提高了整个换流阀水冷控制系统模拟量采样的可靠性。     

电动汽车电机驱动系统效率优化控制

针对电动汽车专用PMSM控制系统的动态损耗问题,提出了一种改进的效率优化策略。分析了PMSM损耗模型,推导出系统损耗和定子磁链的关系,得到最优磁链与定子电阻相关。基于小波神经网络的动态定子电阻补偿方法,进而解决了由于最优磁链受动态定子电阻影响使得最优磁链难以准确计算的问题,以使电机驱动系统效率最佳。利用Matlab/Simulink仿真软件建立了系统模型,仿真结果证明,该策略能有效提高电动汽车驱动系统的效率。     

Interference Mitigation and Joint Decoding for Uplink LDPC-Coded Relay Cooperation

This paper proposes an efficient inter- ference mitigation and joint decoding scheme for uplink LDPC-coded relay cooperation over a Rayleigh fading channel, where a concatenation of Minimum-mean-squared error linear detectors （MMSE） and BP-based joint itera- tire decoding based on the introduced treble-layer Tanner graph are effectively designed to filter and decode the cor- rupted received sequence at a base station. It is demon- strated by theoretical analysis and numerical simulations that the proposed design can well combine the gains from coding and diversity, which consequently leads to a sig- nificant performance improvement over the conventional cooperation system under the same conditions.     

Second‐Order Statistics of System with Microdiversity and Macrodiversity Reception in Gamma‐Shadowed Rician Fading Channels

In this letter, a wireless communication system with microdiversity and macrodiversity reception in gamma‐shadowed Rician fading channels is considered. Exact and rapidly converging infinite‐series expressions for the average level crossing rate and average fade duration at the output of the system are provided. Numerical results are presented graphically to illustrate the proposed mathematical analysis and to examine the effects of the system's parameters on the quantities considered.     

Coexisting oblate and strongly triaxial structures in <Superscript>191</Superscript>Pt

Excited states in ¹⁹¹Pt have been populated using the reaction ¹⁸⁶W + ¹¹B at 85MeV beam energy. Gamma-ray coincidences were measured using the EUROGAM-II spectrometer array. The level scheme has been extended considerably. Evidence for favoured structures of highly triaxial shape with -90^° coexisting with oblate structures has been obtained by comparison with total Routhian surface and cranked shell model calculations. The presence of proton excitations in both positive- and negative-parity states has been confirmed.     

Phonetogram Changes for Trained Singers Over a Nine-Month Period of Vocal Training

Professional vocalists encounter demands requiring voluntary control of phonation, while utilizing a considerable range of frequency and intensity. These quantifiable acoustic events can be measured and represented in a phonetogram. Previous research has compared the phonetograms of trained and untrained voices and found significant differences between these groups. This study was designed to assess the effects of vocal training for singers over a period of nine months. Phonetogram contour changes were examined, with the primary focus on expansion of frequency range and/or intensity control. Twenty-one first-year, master's level, vocal music students, who were engaged in an intensive vocal performance curriculum, participated in this study. Following nine months of vocal training, significant differences were revealed in the subjects' mean frequency range and minimum vocal intensity across frequency levels. There was no significant difference for the mean maximum vocal intensity across frequency levels following vocal training.     

一种双极性三元数字信号发生器的设计

双极性三元数字信号发生器应用于某通信系统中,它采用5开关H桥电路结构,通过5个开关的有序导通实现将信号传输中的普通串行数字信号转换成双极性三元数字信号的功能。采用双极性三元数字信号作为调制信号,大大提高了某通信系统的抗干扰能力,确保该通讯系统在特殊情况下的正常使用。减小双极性三元数字信号的上升沿和下降沿时间,有利于提高通信系统的通信质量。文章详细介绍了该电路的设计方法,同时对其主要性能参数——输出码的高、低电平,上升与下降时间的实现方法进行了阐述。并简述了其混合集成产品的技术性能和使用情况。