Heat transfer performance of heat pipe rotating about parallel axes

We conducted an experimental study of heat pipe rotating about parallel axes. The entire pin fin of non contact thermal resistance was used in the cooling section of the heat pipes. The experimental liquid filled volume range from 10% to 25%, and heat flux density range was 7×103W/m2 to 5.3×104 W/m2. A cooling current of air was formed by the heat pipe rotation. The Reynolds number range was 2.3×103 to 1.2×104. The experimental results indicate that the heat transfer performance of the heat pipe was the best when liquid filled volume reached 20%. The heat transfer capability strengthened gradually along with the increasing rotational speed. The change of the heat power had little impact on the heat transfer performance of the heat pipe. It was found that the absorption liquid core was of little use to the heat transfer performance of the heat pipe. Under the same conditions, the heat transfer performance of the parallel rotating heat pipe was 1.5 times that of co axial rotating heat pipe.     

Logistics distribution optimization technology for chainassembly manufacturing enterprises

According to the demand on just in time(JIT)distribution of chain assembly manufacturing enterprise, cost optimization of backup storage and distribution betimes were analyzed. A backup storage optimization model was formulated and quantitative analysis of the JIT backup storage optimization technology for the process of logistics distribution was carried out. The optimized distribution technique to realize JIT distribution was studied, and the distribution model of logistics center and the distribution algorithm flow were established. Finally, the proposed models were applied in the planning and construction of a logistics center of an electric appliance set chain enterprise with satisfactory results.     

Deforming mechanisms in a non mandrel drawing process of an aluminum tube from circular to rectangular cross section

An elasto plastic finite element method (FEM) was used to study the deforming mechanisms of an aluminum tube drawn without a mandrel from a circular to a rectangular cross section. The simplified dynamics model and FE model of the non mandrel drawing process were established based on the FEM software deform 3D and simulations subsequently performed. Based on the simulation results, the influence of different semi die angles on the drawing load was summarized, and the proper values were found. As for the blank instability during the drawing process, the tangential stress distribution rule along the rectangle sides was acquired. The drawing die sizing section then was modified with a camber angle of 178° to eliminate instability. The touch boundary and touch stress distribution during drawing process also were analyzed. The aluminum tube produced by the optimized drawing die possesses eligible dimensions and smooth inner surfaces.     

Handling performace evaluation of a vehicle stability control system based on a driver model

By combining a driver model, a vehicle system dynamics model, and a vehicle lateral stability control system, the performance of the driver vehicle road closed loop system through a pylon course slalom test was simulated. The simulation was done in accordance with the GB/T6323.1-94 standard. Vehicle stability control system effectiveness was evaluated by measuring the mean maximum yaw rate and the mean maximum steering wheel angle. The simulation results showed the slalom test value with lateral stability control was approximately 4% higher than without a stability control system. This indicates the controlling system improves vehicle handling stability.     

Dynamic Properties of Saturated Clay and Undisturbed Silty Clay

The apparatus for static and dynamic universal triaxial and torsional shear soil testing was employed to perform stress-controlled cyclic torsional shear testing under isotropic consolidated conditions. We conducted a dynamic torsion test of a single hollow sample to obtain its dynamic property data at different effective confining pressures with saturated clay and disturbed silty clay. The results show that the maximum dynamic shear modulus Gmax and ξ obtained from single sample of the cyclic shear test approached those of the traditional method of dynamic torsional testing. We indicate that G/Gmax～ γ andξ/ξmax ～γ of the two soils are independent of confining pressure and testing methods. Each G and ξ can be obtained from the equations we provide. Furthermore, the single sample test method can diminish the differences between the samples during experimentation and effectively provide convenience with authentic experimental results.     

Mechanical Performance of a Vertical Seismic Isolation System Employing a Dish Spring

The base isolation technique has been widely used in different countries to reduce seismic disasters during earthquakes. But most of these devices are effective only in horizontal earthquake responses and do not work well in vertical earthquake responses. We propose a vertical seismic isolation system composed of a dish spring and a visco-elastic damper. To study the stiffness and damping performance of this isolation system, a series of tests under static and dynamic loads were performed. The results show that this system is effective in solving problems related to strong vertical bearing capacity and vertical damping of vertical isolation. The system has not only appropriate vertical stiffness and damper performance, but also excellent mechanical performance. In addition, it is compact, easy to manufacture, and can serve as an ideal vertical damping device.     

Piezoelectric Control of Lifting Surface Flutter

Piezoelectric material was used to establish a single input/single output (SISO) model of a lifting surface with distributed piezoelectric actuators and piezoelectric sensors. The flutter equations and state space equations of piezoelectric laminated structures were also derived. MATLAB, NASTRAN and other software programs compiled by the authors also were used to analyze the flutter and dynamic characteristics. The stability of the closed loop was analyzed for the SISO. The result indicates that the control law can be employed for flutter suppression.     

Civil Servant House Subsidy Schemes of the Chinese Central Government

Based on a theoretical analysis of supply- and demand-side subsidies, the current housing subsidy schemes and practices of Chinese Central Government Departments were summarized. A discrete choice model was adopted to analyze the interrelationship between the housing subsidy choices of civil servants and impact factors. Several policy recommendations are offered for government to improve the efficiency of civil servant housing subsidy policies.     

Effects of Stone Powder on Wet Packing Density of Cement and Performances of Concrete

The amount of limestone powder, which is a by product of manufactured fine aggregate, is larger and larger with the increase of manufactured fine aggregate. Environment will be severely polluted if the powder is improperly used. The effects of limestone powder on workability, compressive strength, and impermeability of concrete were studied when cement is substituted for the mass proportion of 0, 10, 15, 20 percent with it. The results show that the performances of concrete are better improved when the percentage of limestone powder is about 10 percent. The wet packing density of mixture of limestone powder and cement was measured, and it shows that the degree of density was biggest when limestone powder is 10 percent. This shows that the best mixing proportion of limestone powder and cement may be determined through measuring the change of compactness of mixture of limestone powder and cement.     

Environmental Impact Modeling of Urban Sprawl in Beijing, P. R. China

City expansion is a major driving force altering local and regional hydrology and increasing non point source (NPS) pollution. To explore these environmental consequences of urbanization, long term runoff and NPS pollution were assessed in Beijing, P. R. China. The assessment was based on land use types, soil hydrology, and long term precipitation data. The environmental impact model L THIA was used. The outcomes indicate that the area likely would be subjected to impacts from urbanization on runoff and some types of NPS pollution. Urban sprawl will increase runoff volume considerably and significantly increase losses of COD and certain heavy metals such as Pb, Zn in runoff. The results of this study have significant implications for urban planning and decision making efforts to protect and remediate water and habitat quality in the Beijing area. The techniques described herein can be used in other areas.