Papers by Keyword: Parameter Sensitivity

Abstract: The Chaboche unified model with kinematic recovery term was used to describe the cyclic plasticity and viscoplasticity of a new nickel-based superlloy. The model response sensitivities to the change of each parameter of this Chaboche model under either stress control or strain control are calculated and analysed. Influential parameters were identified. This has facilitated the design of an efficient test matrix and the development of a gradient-driven non-linear optimisation algorithm.

Abstract: In view of the difference in design, construction and the usage of the old and the new bridges, there are always stress defects in seamline because of the concrete creep and shrinkage, temperature effect and prestress loss, which seriously affect the service and driving safety. The current ways in foreign and domestic, such as plant steel and semi-rigid connection method, are passive processing based on structure, can’t ensure the long-term performance. According to the three direction stress existing in the seamline, this paper decomposes the material contribution and structure influence, putting forward respectively using material and structure to overcome the adverse situation, using material to remove partial long-term effect, and through the sensitivity analysis of related parameters, to make the structure bearing the rest adverse effect, ensuring the long-term performance of seamline. The relevant conclusion can provide reference for the design and construction of the concrete bridge seamline.

Abstract: As the depth and the length of the various underground cavern is increasing, the stability analysis of surrounding rock is very important. This paper first gives the analytical solution equation of the circular tunnel. About the city-gate water tunnel with no analytical solution, it can be solved by numerical method, which is based on the large finite element software ANSYS. The form of a calculation model for conveyance city-gate water tunnel was established. With the D - P criterion, it is nonlinear calculated for the computation of water conveyance tunnel. Then it is obtained that the stress characteristic and development of plastic zone characteristics of the surrounding rock of city-gate tunnel. It also gives the relationship between the development of plastic zone, plastic strain and coefficient of horizontal pressure, the internal friction angle. The last, it is analyzed the relationship between the different parameters and the plastic zone development of different parts of tunnel cavern. This result can provide technical reference for design and the tunnel construction.

Abstract: Based on the transformation project of rain and sewage diversion in a city, the optimized design of Larsen steel sheet pile supporting structure in pipe-pit excavation was made. Using three-dimensional finite element method to analyze the retaining characteristics of Larsen steel sheet pile, soil deformation of adjacent transverse brace in the middle position and surface subsidence were regarded as design control indicators; through numerical analysis of the geological conditions, load, pile length, horizontal interval of transverse brace and other factors on the sensitivity of the design control indicators, horizontal displacement of brace was regarded as a key factor in the optimal design, and accordingly, related optimized program was proposed. The implementation results show that the optimized scheme can improve the efficiency of construction, protect the safety of construction, and provide a reference for the design and construction of similar projects.

Abstract: The indirect vector control scheme is machine parameter dependent. And parameter identification schemes are themselves dependent on some motor parameters. This paper analyzes parameter sensitivities of two identification methods, reactive power model and q-axis flux model based on MRAS are analyzed through extensive simulations and experiments on an induction motor. Then a novel scheme is proposed based on hybrid model by combining the two adaptive models. The results demonstrate that the hybrid scheme is almost parameter independent in different operation conditions. And it is considered useful in practical application.

Abstract: In order to study the influencing parameters of the shear lag effects on the box-girder beam, the effective width was analyzed by the ways of looking up the present code and formula. Taking the simply supported and cantilever girder as the example, the parameter sensitivity was studied, such as width/span, cantilever length and span. The results showed that the shear lag effect of mid-span beam is small but the support beam is outstanding; the fixed amount relationship of the parameters and the shear lag effects was put forward. The conclusions will be useful for the design and construction of the box girder bridge.

Abstract: The site is located at mileage 50K +650, Tai-174 Road near the mountain slopes. The vertical range is about 150m and the area is 30000 m2. The present study adopted the finite element method program "the PLAXIS 8.2” to analysis. The contents include: (1) To analysis the slope stability on condition that to increase groundwater level is the antecedent of building a function which is the least squares difference between changing slope value and calculated value. Then this study explored the effect of the soil parameter values in different soil layer, parameter sensitivity, to the objective function. Simultaneously, this study sought the optimal parameters of the finite element model in this site in order to be the post-conditions analysis; (2) In order to prove the correctness, this study analyses and compared the data from sliding surface and tilt tube.

Abstract: In this study, an adaptive servo controller based on LQR is designed for flexible master-slave system (FMSS). A dynamics model, observer and servo controller based on LQR is built respectively. According to the parameter sensitive experiments, adaptive servo controller based on LQR is designed. This research focuses on the performance of rapid response and vibration suppression. Experimental results indicate that adaptive servo controller, which suppresses the saturation of the input torque to ensure the stability, has achieved short time delay and adequate vibration suppression.

Abstract: This paper establishes mathematical model of energy consumption economy for constant speed driving and acceleration driving. According to the model, influence degree calculation formulas of parameter sensitivity of vehicle mass, mechanical efficiency of transmission system, rolling resistance coefficient and air resistance factor to energy consumption economy are proposed, and analysis of energy consumption economy parameter sensitivity on a kind of BEV is conducted.

Abstract: To improve accuracy in the engineering design of hydraulic dampers, a dynamic mathematic model for its working fluid density, viscosity, modulus and stiffness is established. The dynamic flow loss due to volumetric change and pressure leakage is also formulated, wherein the dynamic back pressure in the air chamber is coupled. Simulation results show that most of the fluid properties change obviously when the damper is subjected to external excitations, they are not constant values. The viscosity would drop 74.68% and the flow loss would soar 298.68% with the increase of fluid temperature; the modulus and the stiffness would also drop over 20% when the entrapped air ratio increases, but the density is relatively robust to both variations. The established mathematic model gives a dynamic representation of the fluid property under real service conditions, it has already been applied to the engineering design of several hydraulic damper products in industry, and the effectiveness is validated by pertinent product experiments.