Dynamics analysis of reciprocating compressor with a clearance between crankshaft and connecting rod

The dynamic characteristics of reciprocating compressor with clearance between crankshaft and connecting rod were studied. The clearance was regarded as massless virtual link and the dynamics model was established by using Lagrange equation. The variation law of displacement, velocity and acceleration are analyzed under different clearance and different speed conditions of the slider. No-load and load of reciprocating compressor motion were studied. through the phase diagram and the maximum Lyapunov index method. It is found that chaos generally exists reciprocating compressor with clearance between crankshaft and connecting rod and the piston force makes the chaotic motion more intense

Comparison on Training Mode of Graduate Education between France and China

France and China both are of typical power centralization with similar political management systems, and there are same and different aspects existing in higher education. so comparison between the two countries is meaningful. Curriculum provision, innovation ability cultivating and training mode are compared between France and China. Development trend of graduate education is also presented. Some enlightenment may be obtained to improve Chinese higher education level further

A Novel Method of Failure Sample Selection for Electrical Systems Using Ant Colony Optimization

The influence of failure propagation is ignored in failure sample selection based on traditional testability demonstration experiment method. Traditional failure sample selection generally causes the omission of some failures during the selection and this phenomenon could lead to some fearful risks of usage because these failures will lead to serious propagation failures. This paper proposes a new failure sample selection method to solve the problem. First, the method uses a directed graph and ant colony optimization (ACO) to obtain a subsequent failure propagation set (SFPS) based on failure propagation model and then we propose a new failure sample selection method on the basis of the number of SFPS. Compared with traditional sampling plan, this method is able to improve the coverage of testing failure samples, increase the capacity of diagnosis, and decrease the risk of using

Fault diagnosis of rolling bearing based on relevance vector machine and kernel principal component analysis

In order to improve the speed and accuracy of rolling bearing fault diagnosis on small samples, a method based on relevance vector machine (RVM) and Kernel Principle Component Analysis (KPCA) is proposed. Firstly, the wavelet packet energy of the vibration signal is extracted with the wavelet packet transform, which is used as fault feature vectors. Secondly, the dimension of feature vectors is reduced in order to weaken the correlation between the features. The important principal components are selected using KPCA as the new feature vectors under the criterion that the cumulative variance is greater than 95 %. Finally, the faults of rolling bearing are diagnosed through combining KPCA with RVM. Simulation experimental indicates the advantages of the presented method. Moreover, the proposed approach is applied to diagnoses rolling bearing fault. The results show that wavelet packet energy can express rolling bearing fault features accurately, KPCA can reduce the dimension of feature vectors effectively and the proposed method has better performance in the speed of fault diagnosis than the method based on support vector machine (SVM), which supplies a strategy of fault diagnosis for rolling bearing. In this paper, the performance of the proposed method is also compared with other diagnostic methods

An Equilibrium Bid Markup Strategy

Setting a bid markup strategy is a very difficult task. Nevertheless, it is important to construction firms or consulting engineering companies because the development of successful bidding strategies is a key factor to their survival in business. Based on the two bidding criteria of the conditional profit ratio and the work force continuity, this short paper first presents the explicit expression of an equilibrium bid markup strategy in procurement auctions. However, the two bidding criteria conflict with each other and tradeoffs must be made. To make tradeoffs between the two bidding criteria, a new bid markup selection making model is then developed by Cobb-Douglas utility function. The model generalizes the classical expected profit model in the sense that the latter's objective function is only a special case of the former. The result shows that the relative importance of a bidding criterion to another has significant effect on the selection of the equilibrium bid markup strategyThis work was supported partly by the National Natural Science Foundation of China (No. 71001097 and 71171052) and China Postdoctoral Science Foundation (No. 201104167)S

A Potential Role for the Interaction of Wolbachia Surface Proteins with the Brugia malayi Glycolytic Enzymes and Cytoskeleton in Maintenance of Endosymbiosis

The human filarial parasite Brugia malayi harbors an endosymbiotic bacterium of the genus Wolbachia. The Wolbachia represent an attractive target for the control of filarial induced disease as elimination of the bacteria affects molting, reproduction and survival of the worms. The molecular basis for the symbiotic relationship between Wolbachia and their filarial hosts has yet to be elucidated. To identify proteins involved in this process, we focused on the Wolbachia surface proteins (WSPs), which are known to be involved in bacteria-host interactions in other bacterial systems. Two WSP-like proteins (wBm0152 and wBm0432) were localized to various host tissues of the B. malayi female adult worms and are present in the excretory/secretory products of the worms. We provide evidence that both of these proteins bind specifically to B. malayi crude protein extracts and to individual filarial proteins to create functional complexes. The wBm0432 interacts with several key enzymes involved in the host glycolytic pathway, including aldolase and enolase. The wBm0152 interacts with the host cytoskeletal proteins actin and tubulin. We also show these interactions in vitro and have verified that wBm0432 and B. malayi aldolase, as well as wBm0152 and B. malayi actin, co-localize to the vacuole surrounding Wolbachia. We propose that both WSP protein complexes interact with each other via the aldolase-actin link and/or via the possible interaction between the host's enolase and the cytoskeleton, and play a role in Wolbachia distribution during worm growth and embryogenesis. © 2013 Melnikow et al

Research on Short-Circuit Discharge Characteristics of Capacitive Circuits Based on Safety Spark Test Apparatus

Based on the safety spark test apparatus, the short-circuit spark discharge (SCSD) characteristics of the simple capacitive circuit and switching converter are studied. It is pointed out that their SCSD process can be divided into four stages, that is, dielectric-breakdown stage, spark-generated stage, spark-maintenance stage, and spark-extinguish stage; moreover, there is different equivalent spark resistance in each stage. For the simple capacitive circuit, its spark resistance is larger and maintaining voltage is almost unchanged in the spark-maintenance stage. For the switching converter, its output short-circuit characteristics depend strongly on the load resistance and its maintaining voltage reduces rapidly with the decrease of the load resistance. The circuit model is proposed, which can simulate the output SCSD process of the switching converter. By using the least-squares method, the relationship expressions between the discharge duration and capacitance in each time-stage are derived and the corresponding equivalent resistance is obtained. The mathematical models are established, and the expressions of the discharge current and voltage are deduced. Experiment and simulation results are positive in the analysis showing the feasibility of the proposed models