基于信息融合的发动机机械故障诊断方法探讨

发动机故障是指发动机部分或完全丧失工作能力的现象。发动机机械常见的故障可分为摩擦损害、应力变形断裂损伤及化学腐蚀三类。汽车发动机因其结构复杂,工作条件恶劣,相对来讲发动机机械部分故障诊断更加复杂。文中从发动机机械损伤形式出发,分析发动机常见故障引起的异响、振动、温度过高等征兆,介绍了基于振动噪声检测、油液分析与温度检测多信息融合的发动机故障诊断方法。     

A DYNAMIC FAULT TOLERANT ALGORITHM FOR IMPROVISING PERFORMANCE OF MULTIMEDIA SERVICES

MultimediaServiceshasdrawnmuchattention frombothindustrialandacademicresearchersdueto theemergingconsumermarketresultfromfaster developmentofnetworkbandwidthandhighavaila bilityofmultimediatechnologies,suchasinterac tivemultimedia,videoondemand(VOD),multi…     

沃尔什变换对数字信号处理及传输的应用

分析了通过沃尔什变换和数据压缩后进行数据传输的理论和方法,认为信号接收端经过逆沃尔什变换可以较好地恢复原始信号,提出了一种新型的数据传输的可能性.     

Fault Early Diagnosis of Rolling Element Bearings Combining Wavelet Filtering and Degree of Cyclostationarity Analysis

The vibration signals of rolling element bearing are produced by a combination of periodic and random processes due to the machine＇s rotation cycle and interaction with the real world. The combination of such components can give rise to signals, which have periodically time-varying ensemble statistical and are best considered as cyclostationary. When the early fault occurs, the background noise is very heavy, it is difficult to disclose the la- tent periodic components successfully using cyclostationary analysis alone. In this paper the degree of cyclostationarity is combined with wavelet filtering for detection of rolling element bearing early faults. Using the proposed entropy minimization rule. The parameters of the wavelet filter are optimized. This method is shown to be effective in detecting rolling element bearing early fault when cyclostationary analysis by itself fails.     

多分量相移键控信号码速率盲估计

为解决单通道接收机同时截获到同一频带范围内的多分量相移键控信号的参数估计问题,提出了一种不经信号分离直接提取各独立信号分量码速率的盲估计算法.从理论上推导了多分量相移键控信号的二阶共轭循环自相关具有线性特性,因此可以不受干扰地提取各信号分量的码速率;进而提出了简单而有效的谱峰增强方法,与基于二阶共轭循环自相关获得的谱峰相比,用此法获得的谱峰更为清晰.仿真实验表明:用提出的算法,当双分量信号功率比为1:1且信噪比为-5 dB时,码速率估计的正确率可达98％;尤其是在单分量环境下,该算法比现有算法的性能提高4 dB以上.     

大骨节病X线诊断的一致度分析

本文报道了两组Ｘ线诊断者对１９４例大骨节病Ｘ线诊断的一致度分析结果。结果表明，大骨节病干骺端与骨端Ｘ线病变、病例诊断的一致率分别为８９．７４％、９０．２１％、９０．２１％，Ｋａｐｐａ值在０．７６～０．８０间，证明两组诊断者应用现试行的Ｘ线诊断标准的诊断一致度属于极好范围。同时发现诊断的不一致率在９．７８％～１０．２６％间，其主要原因是难以鉴别掌指骨干骺端与骨端的早期Ｘ线征与正常变异。作者认为建立一个大骨节病Ｘ线诊断的标准图谱将会提高诊断的一致度和准确性。     

CLASSIFICATIONS OF EEG SIGNALS FOR MENTAL TASKS USING ADAPTIVE RBF NETWORK

Objective This paper presents classifications of mental tasks based on EEG signals using an adaptive Radial Basis Function (RBF) network with optimal centers and widths for the Brain-Computer Interface (BCI) schemes. Methods Initial centers and widths of the network are selected by a cluster estimation method based on the distribution of the training set. Using a conjugate gradient descent method, they are optimized during training phase according to a regularized error function considering the influence of their changes to output values. Results The optimizing process improves the performance of RBF network, and its best cognition rate of three task pairs over four subjects achieves 87.0%. Moreover, this network runs fast due to the fewer hidden layer neurons. Conclusion The adaptive RBF network with optimal centers and widths has high recognition rate and runs fast. It may be a promising classifier for on-line BCI scheme.     

针刺条件下单一肌梭传入神经电信号的统计分析

本文应用分离单一肌梭的方法,对在针刺条件下肌梭的传入放电进行了统计分析,同时应用快速付里叶(Fourier)变换算法对其传入放电的波形特征作功率谱分析。结果表明,针刺时肌梭传入放电的频率明显增多且趋于平稳,而留针期间,肌梭的放电频率随留时间的延长而规律性递减,表现有一定的适应现象。提示针感的强弱应是针刺>留针>去针后。功率谱分析表明,针刺前、针刺时、留针及去针后等4种情况下,单一肌梭传入放电的主要能量都集中在低频段内,针刺时略向较高频率偏移,提示针刺时肌梭中的较粗纤维活动增强。     

基于盲分离的轮边减速器故障诊断

研究矿用汽车轮边减速器中太阳轮、行星轮和齿圈局部故障振动信号的频潜结构，对于轮边减速器故障诊断具有重要意义。文中模拟了太阳轮、行星轮和齿圈局部故障振动信号，利用盲分离算法将含噪声的混合信号分离，从信号分离结果来看，达到了预期效果，并应用频谱分析方法分别诊断出了太阳轮、行星轮和齿圈局部故障。为矿用汽车轮边减速器故障诊断提供了行之有效的方法。     

PERFORMANCE COMPARISON OF ECG COMPRESSION ALGORITHMS BASED ON CLINICAL DIAGNOSIS

IntroductionIn the research area of ECG,with the inter-vention of computer technology,data compressionis presenting more and more important role.Forexample,increase storage capacity of ECG's asdatabases for subsequent comparison or evalua-tion,feasibility of transmitting real- time ECG'sover internet,implementation of cost effectivereal- time rhythm algorithms,economical rapidtransmission of off- line ECG's over internet to aremote interpretation center,improved functionali-ty of ambulator…     

HI-FI AUDIO CODING TECHNOLOGY FOR ISDN

＠黄晓利＠陈健ＩｎｔｒｏｄｕｃｔｉｏｎＴｏｄａｙｍｏｒｅａｎｄｍｏｒｅｈｉｇｈ－ｑｕａｌｉｔｙ，ｄｉｇｉｔａｌｓｔｅｒｅｏｍｅｄｉａａｒｅｉｎｔｒｏｄｕｃｅｄｔｏｔｈｅｐｕｂｌｉｃ，ｉｎ－ｃｌｕｄｉｎｇＣＤ，ｄｉｇｉｔａｌａｕｄｉｏｔａｐｅ（ＤＡＴ），ｍｉ...     

KINETIC MODELLING AND PERFORMANCE ANALYSIS OF THE FOUR-POST-FRAME LIFTING MECHANICAL SYSTEM

IntroductionWith the increasing requirements ofexpandingthe production- scale of petrochemical products,the present low- throughput (6 0 0 bags/ hour) [1] ofhomemade palletizer becomes a barrier to developforwardly. How to realize the high- speed palletiza-tion is a troublesome problem but required to besolved as soon as posible. The main problem gen-erated due to high- speed palletizing is vibrationproblem of the four- post- frame and lifter,whichnot only worsen the shape of pallet- load,but …     

腮腺肿瘤568例临床分析

本文通过对568例腮腺肿瘤的分析,总结了腮腺肿瘤常出现的临床症状,提出了各类肿瘤的治疗原则,并对术后并发症,误诊原因,复发等问题进行了详细分析,最后重点讨论了腮腺肿瘤的发生、诊断、误诊原因;及术中对面神经的处理等问题。     

基于信号预处理和Hilbert变换的滚动轴承故障诊断

针对滚动轴承振动信号复杂和非平稳的特点,及故障信号常常淹没于各种噪声的情况,先利用消除趋势项和小波降噪对包含故障信息的信号进行预处理,再应用Hilbert变换对信号进行包络解调和频谱分析,提取滚动轴承故障特征频率,并判断其故障模式.对滚动轴承内圈、外圈和滚动体故障的诊断试验,证明了信号预处理和希尔伯特(Hilbert)变换相结合的方法对滚动轴承内圈和外圈局部损伤故障的诊断是有效的和可行的,但不能很好地检验出轴承滚动体的故障特征     

基于遗传算法的信号联锁故障处理中风险问题的研究

以遗传算法优化技术为基础,对铁路信号联锁故障处理中的风险问题因素进行了分析,期望减少电务部门故障处理流程中的风险,从而避免人为造成重大、大事故.     

脂肪肉瘤46例临床分析

本文报告我院1962年～1986年间收治的46例脂肪肉瘤资料,分析了其发病部位、治疗及预后。认为该病好发于四肢及腹膜后,瘤体大小相差悬殊,该瘤最有效的治疗是手术整块切除。但如瘤体过大,位于腹膜后而无法行完整切除时,可行包膜内挖除,仍可获得较好疗效。术后复发、再次手术亦可获得较长存活期。     

肾细胞癌120例临床分析

本文报告了我院1957～1984年共收治的肾脏恶性肿瘤216例其中肾细胞癌120例(55.6%),占肾脏肿瘤的第一位。有82例通过手术及活组织检查得到病理结果,透明细胞癌76例(占91.5%),颗粒细胞癌2例,未分化癌5例。在患者中31岁以上者占86.7%,而20岁以下者6例,其中年龄最小者为7岁(1例),值得注意。本组中75例做了肾切除术。术后随访,三年存活率为47.1%,五年存活率为32.9%,有23例存活五年以上。其中Ⅰ期17例,Ⅱ期6例。因此在今后应尽早诊断、治疗肾肿瘤,以提高长期存活率。     

DESIGN OF VARIABLE-COEFFICIENT-DIFFERENCE-EQUA-TION FILTERS AND THEIR APPLICATION

ＤＥＳＩＧＮＯＦＶＡＲＩＡＢＬＥ┐ＣＯＥＦＦＩＣＩＥＮＴ┐ＤＩＦＦＥＲＥＮＣＥ┐ＥＱＵＡ┐ＴＩＯＮＦＩＬＴＥＲＳＡＮＤＴＨＥＩＲＡＰＰＬＩＣＡＴＩＯＮ＊ＺｈｕＹｉｓｈｅｎｇ（朱贻盛）ＺｅｎｇＢｏｍｉｎｇ＊＊（曾博名）ＬｉＸｉａｏｈｕｉ＊＊（李晓辉）Ｇ...     

PERFORMANCE ANALYSIS OF HYBRID DS SFH/SSMA SYSTEMS OVER MULTIPATH FADING CHANNELS

ＩｎｔｒｏｄｕｃｔｉｏｎＤｉｒｅｃｔｓｅｑｕｅｎｃｅｓｐｒｅａｄｓｐｅｃｔｒｕｍｍｕｌｔｉｐｌｅａｃｃｅｓｓ（ＤＳ／ＳＳＭＡ）ｓｙｓｔｅｍｃａｎｏｆｆｅｒｈｉｇｈｅｒｃａｐａｃｉｔｙｔｈａｎｆｒｅｑｕｅｎｃｙｈｏｐｐｉｎｇｓｐｒｅａｄｓｐｅｃｔｒｕｍｍｕｌｔｉ－ｐｌｅａｃｃｅｓｓ（ＦＨ／ＳＳＭＡ）ｓｙｓｔｅｍ,ｂｕｔｔｈｅｃａｐａｃｉｔｙｏｆｔｈｅｓｙｓｔｅｍｄｅｐｅｎｄｓｇｒｅａｔｌｙｏｎｔｈｅｐｏｗｅｒｏｆｔｈｅｕｓｅｒ＇ｓｒｅｃｅｉｖｅｄｓｉｇｎａｌｓ,ｔｈａｔｉｓｓｏ－ｃａｌｌｅｄｎｅａ…     

1046例围产儿尸检病理分析的临床与优生意义

１９８５年１２月～１９９０年１２月底监测围产儿１５３８８１例，死亡３９５５例，尸检１０４６例，检出畸形５６７例，占５４．２１％，居首位。其次胎儿缺氧、肺炎、颅内出血２６３例（２５．１４％）及妊娠合并症１５４例（１４．７２％）。畸形中检出单纯内脏畸形２２８例（占尸检的２１．８％），以心脏畸形７３例（３２．０２％）最多。体表合并内脏畸形１６８例中以肾畸形５６例（３３．３３％）最多。有５３６例靠尸检证实死亡的原因或检出有关的遗传因素，为进一步产前诊断和优生咨询提供依据。