Advanced Materials Research Vols. 690-693

Abstract: The forecasting of gas demand has become one of the major research fields in gas engineering. Gas demand possesses dual property of increasement and seasonal fluctuation simultaneously, so it makes gas demand variation possess complex nonlinear combined character. Accurately forecast were essential part of an efficient gas system planning and operation. In this paper, a new forecasting model which named regression combined neural network is put forward. In this approach we used regression to model the trend and used neural network for calculating predicted values and errors. Taking the advantages of regression analysis and artificial neural network, the model improves the forecasting accuracy of power demand obviously. The results indicate that the model is effective and feasible for load forecasting.

Abstract: Based on ADAMS CAR module, and the establishment of four - wheel steering vehicle virtual prototype model of the Motor Vehicles ( the WS ). Front and rear comer is proportional to the control strategy, the angle step experimental simulation model and simulation results are analyzed. The results showed that 4WS cars can improve low speed maneuverability and high speed stability, but high speed likely to increase driver fatigue strength.

Abstract: This paper is aimed at simulating and analyzing emission NO_x and Soot formation in the hydraulic free piston engine (HFPE) designed and constructed by Jilin University. The combustion process of HFPE is simulated by using the commercial CFD software AVL FIRE, and the flow field and factors that influence NO_x and Soot formation were analyzed. The simulated results indicate that NO is mainly distributed in the burned zone, whereas the distribution of Soot acts in accord with high unburnt equivalence ratio and high temperature burned zone. Injection timing increases, the amount of the formation of NO is reduced, whereas the mass fraction of Soot rises to a peak and descends. And small swirl ratio exerts a minor influence on emission mass fraction of HFPE.

Abstract: A new downhole intelligent throttling system has been designed to adapt to the variable downhole environment for natural gas exploitation. The downhole intelligent throttling system consists of the throttling structure and the automatic control system. The throttling structure refers to the poppet valve and the existing downhole throttling valve. Its throttling principle is based on the theory that the changing flow area affects the pressure. The automatic control system consists of the downhole motor, downhole sensors, data transmission channel and the Industrial Personal Computer (IPC). Temperature and pressure are monitored by the downhole sensors. These data are transmitted to the IPC to process through the data transmission channel. The IPC sends signals to control the downhole motor to adjust the throttling structure in real time. The downhole flow field has been simulated by using the ANSYS analysis software. The results include the gas pressure, velocity and temperature. They s how that the throttling structure can get the required smaller and more stable outlet pressure at the different inlet pressure. It is a feasible fundamental part to establish the whole downhole intelligent throttling system.

Abstract: Numerical modeling and analyzing of parachute inflation process is of prime interest for the mission analysis and design of parachute system. The inflation process and inflation law of a typical flat circular personnel parachute are presented. Then the fundamental equation of the mathematical model of parachute inflation process was formulated. Finally, the present model is used to calculate opening force, and the factors that influence parachute opening shock are analyzed.

Abstract: In the acquisition process of point cloud data, there exist speckles and noise point. This essay, based on geomagic, presents specific technical steps to remove isolated point in vitro, avoid point cloud resampling and remove point cloud noise. Applications showed that geomagic can, from the original point cloud process, find out useful point cloud, delete speckles, and through the methods of resampling and noise reduction processing, improve cloud quality and reduce data deviation thus improving the data processing efficiency.

Abstract: Taking minimum compliance of the bed of YKS5120B-3 NC gear shaper as the optimization objective, and the three-dimensional finite element relative density as design variables, the three-dimensional topology optimization mathematical model is established based on the interpolation method of solid isotropic material. The optimality criteria algorithm is used to update design variables. Topology optimization design of loaded bed is conducted and the optimal bed material distribution in the design domain is obtained. The new geometric model of the bed is reconstructed according to the optimal bed material distribution. Comparing the static analyses results of original model of the bed with reconstructed model of the bed, the correctness and the validity of the proposed method is verified.

Abstract: Aimed at the Chinese FEM (Finite Element Method) software market was occupied by foreign company, the article introduced the FEM software----Alpha System, which was developed by us. Alpha System could deal with heat transfer and structure static problems. It had 6 modules such as project management, geometric modeling, meshing, loading, solving, and visualization. Some of the key technologies were afforded to solve the difficulties on achieving the software. At last, a part of car rear axle was simulated by Alpha and Ansys. The contrast analysis of the result proved the accuracy of Alpha System. The article gives the reference on how to design the FEM System.

Abstract: The development of ultra-deep drilling and extended reach drilling present many critical challenges for the threaded connections. The reliability of threaded connections must be evaluated to ensure the structural and sealing integrity of drillstring in critical applications. Three-dimensional finite element analysis of threaded connections has been performed in this paper. Different types of loading composed of make-up torque, working torque, tension and bending loading are applied to the model. The makeup characteristics of threaded connections have been analyzed, and the reliability of threaded connections under severe conditions has been evaluated. The results show that von Mises stress distribution over threaded connections is highly uneven, tooth nearby two ends was bearing the most of load. It shows that ultra-deep drilling case is even more challenge than extend reach drilling case in the threaded connections, the reliability evaluation of threaded connections is important in those challenging drilling.

Abstract: Through the FEM analysis of the unloading wheel and unloading beam in unloading mechanism of the beam by using ANSYS, we obtained the deformation curve of unloading beam under the worst working conditions. The deformation compensation method can be used to manufacture the unloading beam for purpose of improving the machining accuracy. The straightness of guide of beam is up to 0.01mm/1000mm. We obtained that the maximum deformation of unloading wheel was 17.6, the maximum stress was 55.8MPa and the maximum contact stress was 37.5MPa. In order to ensure the security of unloading wheel, the consistency of theoretical result and simulation result were verified by using Hertz contact theory.