复杂电磁环境下的信号盲分离方法

介绍了基于盲源分离的信号处理基本思想,阐述了ICA,SOBI,AMUSE三种典型算法的原理、特点,通过仿真实验研究了这三种盲源分离算法对于常见波形信号和真实信号的分离性能及其抗噪能力,验证了算法的有效性和可行性。三种方法对于抑制干扰信号,进行信号的有效提取具有实际意义和使用价值。     

基于极化强度叠加模型的高功率微波混合气体传播特性

基于气体极化强度叠加模型,推导了混合气体的介电常数,得到了高功率微波在混合气体中传播时的折射指数和衰减系数。研究发现,高功率微波大气电离产生的混合气体是快速时变的色散有耗介质。根据其色散性分析了微波在混合气体中的传播速度以及微波脉冲在其中的展宽效应,同时,根据其有耗性对微波脉冲在混合气体中传播时的缩短效应进行了研究。研究结果均能自洽地过渡到对流层或电离层电波传播理论。     

润滑油对带膨胀机CO2跨临界循环的影响

本文对PAG、POE、PAO和AB四种润滑油特性进行了分析,结果表明PAG具有较好的综合性能.又从PAG/CO2混合物的溶解性和粘温特性证明了PAG比较适合CO2跨临界循环.最后对工质CO2夹带的微量PAG对压缩机、膨胀机、气体冷却器和蒸发器的性能影响分别进行了分析,并提出了超临界换热分析模型.结果表明润滑油虽然有助于改善压缩机、膨胀机性能,但造成了换热器性能的严重下降.     

Variational Bayesian-Based Improved Maximum Mixture Correntropy Kalman Filter for Non-Gaussian Noise

The maximum correntropy Kalman filter (MCKF) is an effective algorithm that was proposed to solve the non-Gaussian filtering problem for linear systems. Compared with the original Kalman filter (KF), the MCKF is a sub-optimal filter with Gaussian correntropy objective function, which has been demonstrated to have excellent robustness to non-Gaussian noise. However, the performance of MCKF is affected by its kernel bandwidth parameter, and a constant kernel bandwidth may lead to severe accuracy degradation in non-stationary noises. In order to solve this problem, the mixture correntropy method is further explored in this work, and an improved maximum mixture correntropy KF (IMMCKF) is proposed. By derivation, the random variables that obey Beta-Bernoulli distribution are taken as intermediate parameters, and a new hierarchical Gaussian state-space model was established. Finally, the unknown mixing probability and state estimation vector at each moment are inferred via a variational Bayesian approach, which provides an effective solution to improve the applicability of MCKFs in non-stationary noises. Performance evaluations demonstrate that the proposed filter significantly improves the existing MCKFs in non-stationary noises.     

聚乙烯醇聚离子复合物膜对95%乙醇脱水的红外光谱研究

将聚乙烯醇(PVA)聚离子复合物(PIC)膜在95%乙醇中浸泡48 h,在20~120℃(间隔20℃)下测定吸水后PIC膜的红外光谱,分析了3000 cm-1以上羟基伸缩振动基频随温度的变化情况,探讨了水与PIC膜中羟基的氢键作用。由于羟基谱带在3000 cm-1以上重叠比较严重,结合1000~1700 cm-1水与PIC膜中离子键之间的静电作用,采用二维相关分析提高光谱分辨率,定性地描述了95%乙醇中水与PIC膜之间的结合方式。结果表明:>3000 cm-1羟基的重叠谱带得到了分辨,证明了水与膜内羟基缔合优先吸附渗透,随温度变化早于膜内羟基自缔合被解吸与乙醇分离;确认了水和PIC膜内聚电解质基的吸收,证明了水与聚电解质基团靠静电作用被吸附,随温度升高被解吸与乙醇分离。为PIC膜对95%乙醇脱水分离性能研究提供了一种新方法。     

纳秒脉冲电压下同轴场畸变开关多通道放电特性

使气体开关形成多通道放电是减小开关电感、通道电阻、电极熔蚀,提高开关寿命和稳定性的有效措施。设计了一种同轴场畸变气体火花开关,研究了开关在纳秒脉冲电压下的多通道放电现象。研究了脉冲电压上升速率与多通道放电特性的关系,比较了两种体积比的SF6/Ar混合气体多通道放电特性。实验结果表明:一定气压下,平均通道数随着脉冲电压上升率增加而增多,电流分布趋向均匀;相同脉冲峰值与气压比值,不同气压下,高气压下的通道数较多;SF6/Ar混合气体中,氩气含量较高情况下多通道放电特性较好。最后,结合J.C.Martin的多通道放电理论对实验结果作出了初步解释。     

Measurements and modeling of high-temperature,high-pressure density for binary mixtures of propane with n-decane and propane with n-eicosane

Binary mixture density data are reported for propane (C₃) with n-decane (C₁₀) and with n-eicosane (C₂₀) at T = (320 to 525) K and pressures to 265 MPa. The (C₃ + C₁₀) mixture density data are in good agreement with available literature data to 70 MPa, which is the maximum reported literature pressure. There are no available binary mixture density data to compare to the (C₃ + C₂₀) mixture density data reported in the present study. The mixture density data are correlated with the Tait equation to facilitate interpolation of the data at different experimental conditions. Equations of state that are suitable for reservoir simulations are used to model the reported data. These models include the Peng–Robinson equation of state (PREoS), a volume-translated PREoS fit to high temperature, high pressure (HTHP) pure component density data, the PC-SAFT EoS, and modifications of the PC-SAFT EoS developed for better representation of HTHP data. The models give superior density predictions for (C₃ + C₁₀) mixtures compared to (C₃ + C₂₀) mixtures.     

A mel-frequency cepstral coefficient-based approach for surface roughness diagnosis in hard turning using acoustic signals and gaussian mixture models

During the last years, notable efforts have been made to develop reliable and industrially applicable machining monitoring systems based on different types of sensors, especially indirect methods that does not required to interrupt the machining process. As the main objective in machining processes is to produce a high-quality surface finish which, however, can be measured only at the end of the machining cycle, a more preferable method would be to monitor the quality during the cycle. Motivated by this premise, results of investigation on the relationship between audible sound emitted during process and the resulted surface finish are reported in this paper. Through experiments with AISI 52100 hardened steel, this work shows that such a correlation does exist between the surface roughness and the Mel-Frequency Cepstral Coefficients (MFCCs) and based on that correlation, a new quality monitoring method is proposed using Gaussian Mixture Models (GMM). Obtained results show that this method can identify three different levels of surface roughness with an average accuracy of 98.125%.     

赤霉素-葡萄糖-二氯化锡混合液测定水中无机磷的应用研究

引入赤霉素 -葡萄糖 -二氯化锡混合液作为钼蓝法的新显色剂 .在 1.0 mol/ L HNO3介质和有机相中 ,赤霉素 -葡萄糖 -二氯化锡混合物与无机磷杂多酸反应生成杂多蓝 ,经萃取分离测定有机相 ,λmax=690 nm,表观摩尔吸光系数为 2 .54× 10 4 L· mol-1· cm-1.PO3-4 浓度范围在 0 .1～ 4 mg/ L符合朗伯 -比耳定律 .赤霉素 -葡萄糖 -二氯化锡混合还原剂还原速度快 ,产物稳定性好 ,操作简便 ,结果令人满意     

水平流作用下行波对流的成长及周期性重复

数值模拟研究了在极其微弱的水平流动作用下，混合流体Rayleigh-Benard对流系统一 维行波斑图的成长及其时空演化问题.揭示了系统行波对流的周期性现象及其对水平流动强 度的依赖性. 关键词： 时空斑图 混合流体对流 水平流