查看更多>>摘要：The traditional calculation method of frequency-domain Green function mainly utilizes series or asymptotic expansion to carry out numerical approximation. This method requires very careful divisions of the regions the variables of the integrand. Thus the computing process can be time consuming, which greatly affects the calculation efficiency. Gaussian quadrature is applied to the numerical calculation of the frequency-domain Green function and its partial derivatives. The variation trend of Green function and its partial derivatives along the coordinate plane is analyzed. Comparison of the calculation result with that in existing references is made, which shows that the present method has greatly simplified the computing process, reduced the level of divisions of the regions of variables, improved the computing efficiency and provided higher accuracy.
查看更多>>摘要：For multi-actuators speed control system driven by single pump, several effective control methods have been proposed, such as flow feedback control, etc. These methods are effective only to the engineering equipment with fewer actuators. As for large vessels with more than ten actuators required for speed control, using traditional control methods will result in that costs much, the structure of the hydraulic system is very complicated, even unable to realize. In order to meet the coordinate action of many actuators, two ways based on throttle control and pressure compensation control are introduced in this paper. The research results based on the theoretical analysis of speed control error and adaptability, simulation research and experimental confirmation indicate that the throttle control method is limited by the number of actuators, load size and the speed error, but the pressure compensation control method is helpful to enhance rationality and the coordination of flow distribution between various actuators.
查看更多>>摘要：Cylinder shell stiffened by rings is used commonly in submersibles, and structure strength should be verified in the initial design stage considering the thickness of the shell, the number of rings, the shape of ring section and so on. Based on the statistical techniques, a strategy for optimization design of pressure hull is proposed in this paper. Its central idea is that: firstly the design variables are chosen by referring criterion for structure strength, then the samples for analysis are created in the design space; secondly finite element models corresponding to the samples are built and analyzed; thirdly the approximations of these analysis are constructed using these samples and responses obtained by finite element model; finally optimization design result is obtained using response surface model. The result shows that this method that can improve the efficiency and achieve optimal intention has valuable reference information for engineering application.
查看更多>>摘要：Towed fishery detector in horizontality works passively to detect the location of the shoals of fish through detecting their noises. It can facilitate the detection and reduce the cost as well. It can offset the noise in the signals received by the two vector hydrophones in the tow and reduce the interference from the ship for the efficient range of target detection. It can indicate the azimuth of each target by computing relatively on sound pressure and vector velocity and with the help of non-linear optimizing technology and multi-sources distinguishing by single vector hydrophone.
查看更多>>摘要：In this paper, the virtual prototype technology is used for the analyzing and optimizing high voltage breaker actuator's cam machine. While the high voltage breaker closing, the moving contactor can have the perfect dynamic property by the optimal data. The contactor's dynamic property curve should be in line with perfect dynamic property curve. The velocity curve can be gotten by analyzing virtual prototype. According to the theory of high voltage breaker's dynamic property, a smooth voltage curve can be fitted. This fitting curve as the perfect voltage curve can be used for optimizing the cam machine. Supposing other work condition is invariable, the key points on cam profile which decide the dynamic property of the cam machine are analyzed. The coordinates of the key points are optimized and the cam profile is amended. Analyzing the dynamic property of the breaker's virtual prototype with the amended cam machine, the contactor's dynamic property curve is perfect. In this paper, the optimal coordinates of the key points are used on the cam profile, and the high voltage breaker actuator's cam machine is optimal.
查看更多>>摘要：Failure in FMS includes two aspects: equipment breakdown and tool failure of which should be considered in an excellent FMS scheduling system. Most of past scheduling researches have only discussed the former and the analysis of the latter rarely seen in relevant papers. The scheduling system without tool failure processing seems to be not coincident to the actually production in which tool breakdowns are very common. This paper gives a dynamic scheduling simulation model with concern of the two kind failure using Object-Oriented technology and Colored Petri Net (OOCPN). Rescheduling strategy of tool failure is proposed and the simulation analysis is given which shows that our model and principle are effective and adaptable to actual case.
查看更多>>摘要：Offshore Wind Turbine (OWT) is a device to extract and convert offshore wind energy into useful electrical power. The typical concept design of monopile foundation structure for 1.5MW OWT is raised in this paper. The arrangement of the monopile and related accessorial facilities are especially considered during design. Mechanical characters of the foundation structure are emphatically analyzed, including static analysis, dynamic analysis, fatigue analysis and bucking analysis. The time domain approach is preferable for the dynamic response of foundation under the condition of earthquake and wave. Based on the analysis results, the reliability of the structure is proved to be satisfied with the requirements .The paper provides the reference for the design of OWT.
查看更多>>摘要：Functional periodicity is one of the important concepts of the complexity theory. Obtaining functional periodicity is the key of time-dependent complexity elimination. However, how to obtain functional periodicity is not mentioned in the complexity theory. This paper proposes a method which combines the complexity theory with su-field analysis. It can help the designers to obtain the functional periodicity of the system. A case study shows the application of the method.
查看更多>>摘要：A new type of resistance wind rotor with power-transmission cavity and three blades vertical axis is proposed. Computational Fluid Dynamics (CFD) is employed to numerically research the performance of blades in five typical rotation angles. The pressure of the wind rotor in the fluid field is got based on the static pressure contours of the blades in the five rotation angles. The simulation results show the positive pressure and the negative pressure appear around the blades in a cycle. Both of them can be motive power and resistance power to the wind rotor. The both power cancel out and the total torque output varies with the rotate location. Simulation results show that the largest torque appears at 90°while the least torque appears at 30°. Then, an instrument that measures torque output of wind rotor is designed. The torque output of the rotor in the five typed rotation angles is tested in a circle. The result indicates that distribution of the static torque output is like cosine wave in a cycle which is consistent with the results of the CFD. The studies provide the theory basis and the experimental introduction of the wind rotor designing.
Liu Zhi-haiZeng Qing-liangWang Cheng-longLi Yu-shan...
117-120页
查看更多>>摘要：The technologies of expert system, ontology modeling and reasoning are studied and applied in this paper. A framework of ontology-based expert system for equipment selection and matching in fully mechanized caving face is built up. The OWL(Web Ontology Language) based equipment knowledge base is set up, and the redundant test is made in the protege environment. The equipment selection and matching rules are built up by using SWRL(Semantic Web Rule Language). By using JAVA language, the output of equipment selection expert system is optimized based on the theory of Analytic Hierarchy Process. At last, the functions of the expert system are achieved under JESS(Java Expert System Shell) environment. Practical application shows that the equipments selected and matched by ontology-based expert system are more realistic.
NETL
NSTL