Application of Maximum Probability Approach to the Fault Diagnosis of a Servo System

In an actual control system, it is often difficult to find out where the faults are if only based on the outside fault phenomena, acquired frequently from a fault system. So the fault diagnosis by outside fault phenomena is considered. Based on the theory of fuzzy recognition and fault diagnosis, this method only depends on experience and statistical data to set up fuzzy query relationship between the outside phenomena (fault characters) and the fault sources (fault patterns). From this relationship the most probable fault sources can be obtained, to attain the goal of quick diagnosis. Based on the above approach, the standard fuzzy relationship matrix is stored in the computer as a system database. And experiment data are given to show the fault diagnosis results. The important parameters can be on line sampled and analyzed, and when faults occur, faults can be found, the alarm is given and the controller output is regulated.

群际背景下的元刻板印象研究反思

群际背景研究中,当群体身份显著且可能被外群体成员评价时,个体会激活元刻板印象,即个体将根据其所认为的外群体对其所属内群体的刻板印象来构建群际互动。本研究在还原“关系本质”的基础上,强调了使用诊断率法测量元刻板印象的重要性,分析了元刻板印象激活对群际关系的影响以及元刻板印象通过同化或对立发挥作用的行为机制,指出了积极元刻板印象及其作用研究的兴起。未来研究应重视诊断率法的运用,关注积极元刻板印象作用于群际关系的复杂心理机制,并结合我国目前社会流动和阶层分化的趋势,加强元刻板印象对群体态度和行为作用的本土化研究。

Particle swarm optimization based RVM classifier for non-linear circuit fault diagnosis

A relevance vector machine (RVM) based fault diagnosis method was presented for non-linear circuits. In order to simplify RVM classifier, parameters selection based on particle swarm optimization (PSO) and preprocessing technique based on the kurtosis and entropy of signals were used. Firstly, sinusoidal inputs with different frequencies were applied to the circuit under test (CUT). Then, the resulting frequency responses were sampled to generate features. The frequency response was sampled to compute its kurtosis and entropy, which can show the information capacity of signal. By analyzing the output signals, the proposed method can detect and identify faulty components in circuits. The results indicate that the fault classes can be classified correctly for at least 99% of the test data in example circuit. And the proposed method can diagnose hard and soft faults.

Unsuspected Gallbladder Cancer During or After Laparoscopic Cholecystectomy

Objective To summarize the clinical features and outcomes of unsuspected gallbladder carcinoma （HGC） detected during or after laparoscopic cholecystectomy. Methods Medical records of 8005 patients, who underwent laparoscopic cholecystectomy in Peking Hnion Medical College Hospital between June 1993 and June 2011, were reviewed. Patients that pathologically diagnosed as HGC were retrospectively studied in terms of clinical features, preoperative and postoperative diagnosis, surviving period, and complications. Results In the 8005 patients who received laparoscopic cholecystectomy, 36 （0.45%） were diagnosed as LIGC during （25 patients） or after （11 patients） laparoscopic cholecystectomy. The gallbladder cancer was staged as T1 in 16 patients, T2 in 11 patients, and T3 in 9 patients. The 1-, 3-, and 5-year survival rates of all the patients were 88.9% （32/36）, 63.9% （23/36）, and 58.3% （21/36）. The 5-year survival rates in T1 stage, T2 stage, and T3 stage patients were 100%, 75.0%, and 0.0%, respectively. Conclusions The survival rate of HGC is associated with tumor stage, not with operation approaches. Laparoscopic cholecystectomy is appropriate for T 1 patients.

Combined Signal Detection Method in Differential Frequency Hopping System

In order to enhance communication reliability of differential frequency hopping system, a receiver implemented with the concatenation of an optimal subblock-by-subblock maximum a posteriori probability (OBB-MAP) detector and a soft-decision Turbo decoder is proposed and validated in both AWGN and Rayleigh flat fading channels. It is shown that the OBB-MAP decoder can iteratively decode a cyclic trellis, and back-search the trellis for any state to obtain estimates for the prior information bits which can be employed by soft-decision Turbo decoder. The proposed receiver achieves a better bit error rate(BER) performance than maximum likelihood sequence estimation(MLSE) detector employing Viterbi algorithm. The simulation results demonstrate that the combined signal detection method improves communication quality.

Wave-electric field coupling imaging diagnostic method for filled subgrade

Thick earth-rock filled embankment of large earthwork volume often occurs during the construction of expressways in mountainous and hilly areas. The compaction quality of earth-rock filled subgrade will directly affect the settlement deformation and stability of the embankment after filled. Therefore, effective evaluation on the compaction quality of the earth-rock filled subgrade is an unsolved critical technical issue to control the construction quality of highway engineering. Based on the wave propagation and electrical resistivity characteristics of the earth and rock fillings, a theoretical model of the compaction quality detection by wave-electric field coupling imaging diagnostic method was established. Then, two filled subgrade models containing cavities and heterogeneous bodies respectively were make separately, and by the wave velocity testing and electrical resistivity testing, the wave-electric field coupling imaging diagnostic method was applied to these two model. The result shows that it is feasible to use the wave testing technique and the electrical resistivity testing technique for a diagnostic test of the subgrade compaction quality. Based on the abnormal areas reflected by the wave velocity imaging and electrical resistivity imaging results, we are able to analyze the scope and site of distress but not able to quantitatively evaluate the subgrade compaction quality. We can accurately qualitatively analyze the subgrade compaction quality based on the wave-electric field coupling calculation model of fill subgrade quality proposed by this paper.