Advanced Materials Research Vols. 418-420

Abstract: A 2-DOF spatial mechanism was designed for pointing requirement. It can meet the requirement by adjusting the length of bipod. The kinematics analysis result which was made by Pro/Mechanism shows that this mechanism meets the design requirements; meanwhile, the main factors that have an impact on mechanism precision were analyzed by Pro/e Behavioral Modeling. The result shows the bipod is the key point to achieve mechanism precision. This study provides theoretical foundation for the follow-up manufacture and assembly.

Abstract: In the present investigation, a computational fluid dynamics technique is used to investigate the ventilated supercavitation reaction to the change of gas supply rate. Detached eddy simulation, a hybrid RANS-LES method is used for turbulence modeling, and improved Singhal’s model is used to simulate cavitation process. Simulation results show that the change of cavity shape is lagging behind that of gas supply. When gas supply is shut, cavities experience a series fluctuation before reaching equilibrium state, if natural cavitation numbers are large; in contrast, they are monotone decreasing under small natural cavitation numbers.

Abstract: The acceleration record of an earthquake ground motion is a nonstationary process with both amplitude and frequency content varying in time. The paper presents a general procedure for the analysis and simulation of strong earthquake ground motions based on parametric ARMA models. Structural design spectra are based on smoothed linear response spectra obtained from different events scaled by their peak values. Such an approach does not incorporate other characteristics of the excitation represented by measured data. This study investigate the use of non-stationary models which can be considered characteristic and representative of specific historical earthquakes. An earthquake record is regarded as a sample realization from a population of such samples, which could have been generated by the stochastic process characterized by an Autoregressive Moving Average (ARMA) model. This model is capable of reproducing the nonstationary amplitude as well as the frequency content of the earthquake ground accelerations. The moving time-window technique is applied to synthesize the near field earthquakes, Boumerdes-1, Boumerdes -2, and Boumerdes -3 2003 recorded on dense soils in Algeria. This model, is based on a low-order, time-invariant ARMA process excited by Gaussian white noise and amplitude modulated using a simple envelope function to account for the non-stationary characteristics. This simple model gives a reasonable fit to the observed ground motion. It is shown that the selected ARMA (2,1) model and the algorithm used for generating the accelerograms are able to preserve the features of the real earthquake records with different frequency content. In this evaluation, the linear and non linear responses of a given soil layer have been adopted. This study suggests the ability to characterize the earthquake by a minimum number of parameters.

Abstract: According to the structure strength optimization theory, each cavity die layer’s size and inter layer interference were obtained by using the Lame formula. The end angle and height difference were introduced into the finite element model, and a new and reasonable staged inclined end prestressed combined cavity die have been designed. The cavity die’s working life was forecasted by wear model and fatigue fracture model, and the conclusion was acquired that fatigue is the main factor to destroy the cavity die.

Abstract: In order to overcome steady-state error and low-velocity scrawl problems caused by friction in electro-hydraulic control system of engineering mechanical, method for overcoming nonlinear friction force of pressure pulsation system is adopted in this study. A new pressure pulsation system is proposed, mathematical model of the pressure pulsation system is established, based on the MATLAB fuzzy control strategy and simulation. The results show good dynamic performance of the system.

Abstract: Traditional method for measuring liquid level of absorption tower in wet flue gas desulfurization (WFGD) system is introduced in this paper, and it's found that measuring accuracy of the method exists in large deviation. A new method is proposed to measure liquid level of absorption tower for this situation. The local test results show that not only measurement result of new method is more close to the actual liquid level than traditional method, but also using new method can save operation cost and ensure the safety, stability, and economic operation of WFGD system.

Abstract: To improve the service performance of roller. The surface of roller was alloyed by a 5kW CO₂ laser. The microstructure, hardness and wear resistance were investigated by means of OM, XRD, Micro-hardness Testing Machine and MMS-2A screen display friction tester. The experimental results indicate that excellent metallurgical bonding is obtained between alloying layer and substrate, the main microstructure of laser alloying coating is composed of phases such as γ-Fe, Fe(Ni,Cr), (Fe,Cr)₇C₃, MoC, Fe₂MoC, WC and SiC etc. The strengthening mode is particle-reinforced mechanism. The corrosion resistance of connection zone is better than that of alloying zone. The average of microhardness value is as high as 718 HV, which is more two times than that of substrate, and the average of wear resistance value of alloying layer is approximately three times larger than that of substrate

Abstract: Traceability is a new requirement of supply chain quality information management, but many companies have not got any effective measures yet. In response to this issue, this study firstly focuses on the management approach for traceability and discusses the quality information that need to be identified and its characteristics, then a Radio Frequency Identification (RFID)-enabled method is proposed to record the quality information; after that, a BOM-based approach is used to organize the recorded quality information; linking of these quality information is made to achieve traceability. Finally a quality information management system is built on the proposed methodology and an application research in Auto parts manufacturing industry is used to demonstrate its effectiveness. Implementation result shows that the proposed methodology can achieve traceability effectively and supply chain product quality information management has indeed improved through ensured traceability.

Abstract: Taking Motorcycle Engine as the research object, force analysis of the single cylinder engine connecting rod bending and fracture by engine linkage dynamic model. By calculating the connecting rod compression, combustion chamber total pressure, reciprocating movement of the inertia force and from the rod bend parameters to compare the models currently on the market four types in the working state suffered total stress and strength margin safety factor, found that the safety factor of four models in general partial link is small, especially 152QMI engine connecting rod end connecting rod in the hole near easier to bend and break. This study provide a scientific basis for the engine connecting rod design, the quality of correction and failure analysis.

Abstract: This article simulated fuzzy control system by using MATLAB and compared the normal fuzzy control system with the fuzzy control system which has an integrator. Further more, the influence of quantize factors, proportional factors and integral constants on system was studied. The simulation results show that static error always exists in normal fuzzy control systems and proportional factors influence the stability of the system greatly. Put an integrator into a fuzzy control system, and static error can be eliminated and the system stability can be improved. The conclusion of simulation and practical experience, use fuzzy control system with integrator in reality. It can get good results.