Applied Mechanics and Materials Vols. 157-158

Abstract: In this work principal component analysis (PCA) was adopted to construct a background model and moving objects were detected by background subtraction method. Firstly, constructed the matrix of training samples by means of converting the video sequence to vectors. Then calculated the covariance matrix C of the training set, and acquired the eigenvalues and eigenvectors of C through SVD decomposition. Next, sorted the eigenvalues and reconstructed the background model by using several image vectors which had higher cumulative contribution. Finally, comparison experiments are performed with the detection results by GMM approach. Experimental results show that the proposed method in this paper could establish background models more accurate and have better effective of object detection.

Abstract: The goal of this paper is to develop a method to determine the mechanical properties of SPCC steel spot weld. The mechanical properties of a resistance spot weld could not easily be obtained due to the size of spot weld, and the non-uniformity around the weld zone. This research used an altered approach to obtain the mechanical properties of spot welds. The study based on the hardness measured on spot welds heat-treated surrogate SPCC specimens with the same hardness for the tensile tests. With the tensile test results and hardness measurement data, the correlation of the hardness and yielding strength and of the hardness and ultimate strength could be obtained. In this study, SPCC sheets with thickness of 0.8 mm were welded, and their hardness around the spot welds was measured. Based on the measured hardness, SPCC specimens were heat-treated to reach the hardness measured at different sub-zones of the spot weld. The mechanical properties and microstructure of sub-zones were studied. The relationship between hardness and other mechanical properties were established. The study provides good understanding of the potential failure in spot-welded structures. The results can also be further utilized for computer simulation of spot welds with failure modes to predict the performance of spot-welded vehicle body structures.

Abstract: This paper introduces advantages of XML as a data exchange format, and proposes a multi-database system architecture based on XML, a data exchange platform model. We takes full advantage of is the features of XML, including good extensibility and interactivity, to implement the XML-based integration program of heterogeneous databases, making all kinds of data described in a unified XML format. And we describe the actual workflow of the system in this model and theoretically analyze the implementation details of its core modules. Finally, the workflow and the multi-database work mode for users to access databases in the system model based on XML are presented.

Abstract: The disaster backup of oracle database has been a hot issue for a long time. However, mature solutions to disaster backup of oracle lob are limited, meanwhile, text and multimedia messages are stored as lob type in oracle database. This paper proposes a possible way to quickly capture, transfer and backup the changed data of oracle lob.

Abstract: For the complex terrain, in long-distance slurry pipeline, the core equipment of the running pipeline - valve monitoring is particularly important. This paper based on the actual running conditions of Yunnan Dahongshan pipeline, developed an intelligent valve control system. Valve monitoring and management can be seen in this system, which combines software programming, measurement technology, communication networks, as well as order management, fault management, spare parts management, query statistics. Getting running parameters rely on the monitoring system, and then for the mathematical model of solid traffic in slurry pipeline transportation, the slurry weight can be measured. The system achieved valve monitoring and management very well, improving the long-distance slurry pipeline running reliability.

Abstract: In this paper, a real-time location feedback control system based on multi-sensor network is proposed for the precise control of a moving robot. The target tracking network system is a real test-bed that consists of a group of ultrasonic sensor nodes, a mobile robot and two laptops. In order to pursue excellent tracking performance and modify the robot’s trajectory promptly, Extended Kalman Filtering algorithm as well as a kind of scheduling scheme based on location is applied in the system. The experiment result validates the correctness of the Extended Kalman Filter (EKF) and shows that the target tracking network system is effective for robot feedback control.

Abstract: This paper proposes an effective genetic algorithm for the job-shop scheduling problem (JSP) to minimize makespan time. An effective chromosome representation based on real coding is used to conveniently represent a solution of the JSP, and different strategies for selection, crossover and mutation are adopted. Simulation experimental results have shown that the scheduling model using the algorithm can allocate jobs efficiently and effectively.

Abstract: The influence of various technological parameters on laser-textured cast-iron surface is presented in this paper. A kind of micro-pits array was analyzed using single-factor method, where Nd3+: YAG solid laser is applied to obtained regular surface textures, and 3D surface morphology profiler used to compare the surface topographies related to technology. Among of the set of parameters, the distance between working surface and cavity mirror, pumping current and number of pulses were concerned variables in the process of manufacturing of microstructures. The geometry structures for variables were characterized by the radius and depth of micro-pits. Moreover, surface roughness for different technological parameter were expressed with Ra, Rq and Rt. Abbott curve was adopted for valuing the abrasion resistance of given textured surfaces. One optical range of parameters is achieved for improving the level of laser texturing surface.

Abstract: Owing to the incompleteness and asynchronicity of the observation data, it is hard for the asynchronous netted radar to track its target effectively under intense blanket jamming. This paper presents a kind of data fusion algorithm for the asynchronous sensors based on optimal linearization approach, providing a solution to the problem of target tracking of radar networks under blanket jamming. First, the optimal linearization processing technique of the observation equation is derived. Then, based on this, the state vector of the target is initially estimated in batch mode. Finally, the filtering is processed in sequence. The simulation results show that the data fusion algorithm presented in the paper can track the target in high accuracy.

Abstract: According to the shortage of the central heating system control equipment, design the heating regulation controller based on the embedded Linux operating system with the 32-bit processor S3C2440 as core. The system determine the second supply water temperature of heating network by measuring the outdoor temperature, and adjust heating temperature by the electric valve opening. This system has advantages of high sensitivity, good anti-interference abilityand good real-time performance, and good energy-saving effects.