S校正电容器损耗测试频率分析

通过试验和分析说明彩电用Ｓ校正电容器ｔｇδ的测试频率为１ｋＨｚ是不合适的，应选用更高一些的频率。当选用１０ｋＨｚ测试，ｔｇδ控制在４０×１０－４以下比较合适。     

The Lamb-dip spectrum of the J = 1 ← 0 transition of DF: Crossing resonances and hyperfine components

The Lamb-dip technique has been applied to the observation of the J = 1 ← 0 transition of DF: for the first time, the hyperfine structure due to D and F have been resolved by using microwave spectroscopy. The high accuracy of this technique allows us to provide hyperfine parameters that are in very good agreement with those obtained from molecular beam experiment. In addition, our frequencies together with the unresolved ones up to J″ value of 47 allow us to provide the most accurate ground state rotational constants of DF known at the moment. Furthermore, due to the presence of a relevant number of strong crossing resonances, the J = 1 ← 0 transition of DF can be considered an illustrative case to show how they modify the shape of Lamb-dip spectra.     

无线电测向设备测向误差与数据处理方法研究

通过对某型测向设备的测向精度试验获取的试验数据的分析处理发现，现行的标准和规范中采用的测向误差计算方法没有能够正确区分出设备的能力和试验环境的影响。不能完全客观公正地评价测向设备的真实性能。为了获得合理的测向结果，建议严格按照ITU的有关标准选择测向场地。并选择合适的误差计算方法。     

Quantitation of low concentrations of polysorbates in high protein concentration formulations by solid phase extraction and cobalt-thiocyanate derivatization

A spectrophotometric method was developed to quantify low polysorbate (PS) levels in biopharmaceutical formulations containing high protein concentrations. In the method, Oasis HLB solid phase extraction (SPE) cartridge was used to extract PS from high protein concentration formulations. After loading a sample, the cartridge was washed with 4 M guanidine HCl and 10% (v/v) methanol, and the retained PS was eluted by acetonitrile. Following the evaporation of acetonitrile, aqueous cobalt-thiocyanate reagent was added to react with the polyoxyethylene oxide chain of polysorbates to form a blue colored PS–cobaltothiocyante complex. This colored complex was then extracted into methylene chloride and measured spectrophotometrically at 620 nm. The method performance was evaluated on three products containing 30–40 mg L⁻¹ PS-20 and PS-80 in ≤70 g L⁻¹ protein formulations. The method was specific (no matrix interference identified in three types of protein formulations), sensitive (quantitation limit of 10 mg L⁻¹ PS) and robust with good precision (relative standard deviation ≤6.4%) and accuracy (spike recoveries from 95% to 101%). The linear range of the method for both PS-20 and PS-80 was 10 to 80 mg L⁻¹ PS. By diluting samples with 6 M guanidine HCl and/or using different methylene chloride volumes to extract the colored complexes of standards and samples, the method could accurately and precisely quantify 40 mg L⁻¹ PS in up to 300 g L⁻¹ protein formulations.     

Optimal power‐aware relay placement for cooperative wireless sensor networks

We study the problem of optimizing the symbol error probability (SEP) performance of cluster‐based cooperative wireless sensor networks. Recent studies in literature show that an efficient relay selection protocol based on simple geographical information of the nodes to execute cooperative diversity can significantly improve the SEP performance at the destination of such networks. As well, similar line of research on optimal power allocation (for the source and relay nodes) can be found in literature. However, to achieve the best SEP performance at the destination of a cooperative wireless sensor network, joint optimization of power allocation and relay placement should be accomplished. To this aim, we reformulate the SEP of a multi‐hop cooperative communication in a general form and optimize transmitted power level and relay placement simultaneously. This analysis is developed for both amplify‐and‐forward and decode‐and‐forward relaying protocols. Simulation results demonstrate that the proposed joint optimization can effectively improve the SEP performance of the network. Copyright © 2013 John Wiley & Sons, Ltd.     

正弦信号DFT之频谱泄漏问题的多角度分析

利用DFT计算连续正弦信号频谱时,其信号处理过程大致分为采样、数据截断和DFT计算这三个环节。重点从采样、数据截断及正弦信号本身的特点这三个方面着手,分析了四个影响频谱泄漏的因素,并给出了MATLAB仿真。分析结果对DFT的教学和应用,都具有一定的参考价值。     

低功耗多点螺栓松动监测系统研究

在煤矿罐道中螺栓紧固件受环境和罐笼升降带来的振动作用,使其产生松动带来矿井工作安全隐患,因此实现对罐道中多个螺栓地检测显得尤为重要。本文提出一种有效多点检测螺栓松动的系统,该系统基干簧开关、工作频率315 MHz的DF无线数据模块和编码器PT2262组成带有RFID的传感器检测电路。螺栓松动带动螺母一侧磁钢磁场地变化使干簧开关闭合,传感器检测电路工作,触发DF无线模块发射信息,无线终端则是由解码器PT2272组成解码电路接收收检测螺栓松动状态。通过对DF无线模块的频谱测试和螺栓松动检测实验得到在6 V电压下有效检测到300 m内多个螺栓松动。     

Dense subspaces of quasinormable spaces

Dense linear subspaces of quasinormable Fréchet spaces need not be quasinormable, as an example due to J. Bonet and S. Dierolf proved. A characterization of the quasinormability of dense linear subspaces of quasinormable locally convex spaces and several consequences are given. Moreover, an example of a dense linear subspace of a countable direct sum of Banach spaces, which is not quasinormable, is provided. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

单通道接收机实施空间谱估计测向

本文是应用空间谱估计技术测向的一种新方法。基于用权微扰算法得到的协方差矩阵，提出了用单通道接收机实施空间谱估计测向。从原理上讲，任何特征结构算法都适用。针对空间骨算法进行了计算机模拟，结果证明方法是有效的。并且这一方法有着重要的现实意义。     

中远红外双波段激光器增益介质匹配

对中远红外双波段激光器中DF和CO2两种增益介质的匹配进行了研究。根据对DF和CO2两种增益介质分布的理论分析,发现DF相比于CO2介质增益峰值位置更靠前,激活区长度更短,据此设计加工了一台双波段激光器,使CO2气体注入孔位置可调,通过D2和CO2注入孔位置的差别来实现两种介质增益峰值位置的匹配。实验证明了这种设计是有效的,并确定了激光器共同光轴的最佳位置位于D2气注入孔下游3 mm,CO2注入孔下游33 mm处,此处双波段激光的输出功率均接近最大值。