Advanced Materials Research Vols. 452-453

Abstract: The stability of the high-speed running vehicle subjected to seismic excitations considering passengers' dynamics are considered. A vehicle consists of one body, two trucks and four wheel sets. A passenger is modeled by simple two degree of freedom vibration system. The equations of motion of the vehicle and passengers are calculated by Lagrangian equation of motion. Combining two models, the behavior of the vehicle subjected to actual seismic input considering passengers' dynamics are calculated by numerical simulation. The stability of the vehicle is evaluated by using the risk rate of rollover. We investigate the possibility of the rollover of the vehicle. We focus on the effect of the dynamic characteristics of the human and the number of the passengers when the vehicle is subjected to the seismic excitation.

Abstract: HDPE pipes have been widely used in industry, which were mostly buried underground. Because of special material properties, which were affected by temperature, it is necessary to get the temperature profile of buried HDPE pipe. Most past solutions for temperature distribution in buried pipe were numerical ones. The aim of this paper was to present a simple analytical model under steady-state heat transfer condition with a new special heat transfer coefficient introduced. FEM method was used to check this model. The influences of fluid temperature, soil surface temperature and soil depth on pipeline temperature were also analyzed. The results showed a good agreement between the analytical model and FEM method. And fluid temperature in pipe was proved to be the key factor that affected the pipe temperature .

Abstract: Slow light properties of the photonic crystal line-defect waveguide are researched with the plane wave expansion method. The structure of the waveguide is adjusted with several methods mentioned above at the same time and the slow light properties get better. For the structure of dielectric rods, central frequency and the group velocity of the guided modes decrease with the increase of the radii of the defected rods as well as the dielectric constant. Effects on the slow light from the change of the defected rods’ position are also studied, through moving the rods up and down; we get the almost linear guide mode which has flat slow light curve and smaller group velocity. In a word, group velocity of the slow light is mainly affected by the radii and dielectric constant of the defected rods, and group velocity dispersion is decided by the change of the defected rods’ location.

Abstract: Magnesium reduction retorts, as vital industrial equipment in Pidgeon Process, have a short service life. The dramatic temperature drop and rise in the retort is predicted to shorten service life. A mathematical model has been developed to simulate the phenomenon of heat transfer of retorts with different wall thickness and temperature of reactant compounds. The computed results are as follows: (1) the rising rate of temperature in the retort overweighs that in reactant compounds, and it takes less time to form a uniform temperature distribution; (2) the rise of retort’s wall thickness will aggravate the sharp temperature change; (3) when the temperature of reactant compounds being placed into increases, the situation will be improved.

Abstract: A new local path planning method for dual-arm mobile robot shuttling within the truss is presented. Like the probabilistic roadmaps method, this method proceeds in two stages: preprocessing stage and path planning stage. In preprocessing stage, the workspace is divided into a set of non-overlapping cubical cells. The nodes in the free workspace are stored in a matrix. In path planning stage, three query strategies are adopted to search the path from start point to goal point. Take use of vertex query strategy, the smooth path can be acquired in a fraction of a second. The algorithm is simple, and is applicable to any static environment with convex obstacles.

Abstract: The bolts of cover system are ruptures when cover system effected by transient load. According to the experiment data and research result to find, the frequency of loads is similar to cover system, and result in resonance. In order to eliminating resonance, change the original cover system frequency by adding damper. This paper adopts additional water mass method for wet modal; conclude inherent frequency and mode of vibration. Using FEM simulation on the two cases, to assess the effect of reduce load.

Abstract: The elastic wave band structures of the one dimensional rod phononic crystal are studied by the lumped-mass method. For the infinite periodic structure, the accuracy of numerical results is influenced by the number of discrete mass. The initial and stop frequecy of the first bandgap need different number of discrete mass to achieve calculation accuracy when two materials composed phononic crystal at different volume ratios. For the finite structure, the different arrangements make different width of the attenuation area at periodic load. The width of the bangap exhibits largely when the external load acts on the matrial with lower denstiy and elastic modulus in front of the higher density and elastic mudulus material.

Abstract: The temperature and humidity are two main environmental factors, which have influence on the life of solid propellant. Comparing with single factor aging life model, hygrothermal aging life model is more feasible, which takes temperature and humidity into consideration. In this paper two hygrothermal aging life models were established. The data of hygrothermal aging test of solid propellant was used for multiregression. According to significance analysis and comparison of two models, it was shown that two models both fit the test data well. Storage life of the solid propellant under normal condition was obtained by using the life models. The results of the research can provide reference for storage life prediction of solid propellant.

Abstract: From several basic structures for indoor computer wireless communication system, a new type of system structure was designed. Its conformation of optics system and achievement by module were described particularly through using Fresnel lens system. This system’s link could be transformed between directed LOS link and non-directed LOS link, which made the system communicate at a high-speed when there were no barriers between the emitter and receiver and keep a good convexity when barriers appeared. At last what should be noted for the analogue simulation was brought up.

Abstract: Steady laminar free convection in air from parallel circular cylinders set side-by-side is studied numerically. The SIMPLE-C algorithm is used for the solution of the mass, momentum, and energy transfer governing equations. Simulations are performed for tube-arrays consisting of 10 equally-spaced cylinders, for different center-to-center separation distances in the range between 1.4 and 6 cylinder-diameters, and for Rayleigh numbers spanning between 101 and 105.