Papers by Keyword: Barrier

Abstract: We report on the development of a new generation of SiC Schottky rectifier devices employing a Molybdenum based barrier metal system and a new stripe cell design for field shielding and optimized area utilization. The Schottky barrier height is reduced and thus the conduction losses are decreased significantly. The balance between forward conduction and reverse leakage losses as well as the homogeneity and stability of the new barrier system are investigated carefully.

Abstract: Composite character of ceramics is a base for creating new generation materials. It is established that the rational choice of the basic structural elements allows to control stress-strain state of the "loaded" ceramics and to slow down process of its degradation. The developed method of designing of details taking into account ceramics degradation at exploitation is described.

Abstract: The designs of the buildings are in addition to the static load exposed to ground vibrations spreading from the surrounding geological environment. Ground vibrations, which are produced by anthropogenic phenomena, are not usually the crucial load for the stability of the building. But this load have an adversely affect the walls of buildings or sensitive equipment in these buildings. This article will be deal with model study of underground barriers utilized as a protection against the spread of ground vibrations in geological environment. These underground barriers maybe used in the vicinity of roads or railway lines or in urban areas around the halls with heavy industrial activity. Material of underground barriers will be designed from material with different parameters, so that it could be assessed the best variant in terms of absorption of seismic waves. The different variations of the thickness of underground barriers and different distances from the source of vibration will be designed in the analysis. The analysis will be performed in mathematical models that will be created in the software’s based on the finite element method.

Abstract: Preventing tramcar accidents is very important in the production of the coal mine. In this paper, S7-200PLC and BP neural network are used to design a intelligent flexible anti-running system. The control system adopts normally closed and flexible bufferred barrier. Following is the simulation experiment scheme. The BP neural network is adopted to eliminate the influence of temperature and filter by photo-electric coupler, which can measure the accurate and reliable tramcar speed. If the speed is faster than set point, the system will give an alarm and barrier does not work ,which stops the harvesters continuing running. This method guarantees the safe operation of coal mine.

Abstract: The harmful ingredients in packaging materials and containers usually migrate to food during the machining and printing period. The permeability of packaging materials is very important for the food packaging safety. Several commonly used packaging materials were researched in this paper. Their permeability was characterized including the gas permeability, light-transmitting property, and the water vapor permeability. Some technologies which could improve the barrier property were brought forward. And the factors that impact the permeability were discussed in this research. Research on the permeability of packaging material is significant for food industry.

Abstract: External wind is one of the major factors that influence the spread of fire along building exterior facade in high-rise buildings. Fire simulation experiments are conducted .First, under two circumstances of low-speed and high-speed side-blown wind, observing barrier of window spill plume along building exterior facade under different dimensions of windows, windowsill walls and balconies. Then the correlation between smoke temperature near the exterior facade and dimensions of window, windowsill wall and balcony is obtained by numerical fitting and dimensional analyses. The correlation indicates that, on low-speed side-blown wind, spill plume spreading diagonal up downwind, balcony width plays a leading barrier; on high-speed side-blown wind, spill plume horizontal spreading downwind, balcony extension plays a leading barrier.

Abstract: Vertical spread of opening spill plume from underground garage fire is studied by FDS. How can cornice barrier prevent the vertical spread of opening spill plume under the effect of the thermal buoyancy is analyzed. Optimal technical solutions and design parameters are proposed to improve the fire safety of underground building and adjacent buildings. This study can provide theoretical and technical reference for the underground building design.

Abstract: PPP project success not only depends on governmental credit and private sectors capability, but also relies on the scientific and reasonable evaluation in early decision-making stage. Currently there are a lot of countries and regions internationally, where the method of VFM is used to the procurement of infrastructure projects, and achieves good results. Based on the analysis of status quo of decision-making of PPP project in China, the barrier to implement PPP projects assessment system based on VFM in china was thoroughly researched. Thus, reasonable proposals to promote the implementation of VFM assessment system smoothly in china were put forward.

Abstract: Numerical simulations of two dimensional laminar mixed convection flow over backward facing step with different inlet geometries in a duct is investigated by using finite volume method. The wall down downstream of the step is kept at a temperature of 330K and constant heat flux of 500W/m², while the other walls that form the other side of the duct are thermally insulated. Ethylene glycol is used as working fluid and three types of barrier which are triangular, parallelogram and semicircle are carried out to compare with a simple entrance of backward facing step. The Reynolds number was in the range of 50Re200 and fluid temperature is 300K at the inlet of the channel. Parallelogram inlet has the highest average velocity in all sections and highest average Nusselt number over downstream. Also triangular inlet has the highest shear stress all over the downstream of the duct and cause to make a highest skin friction coefficient.

Abstract: The Jacobian matrix represents the relationship of the linear mapping between the space velocity of robot operation and joint space velocity, which is the important link in the process of robot control. According to analyzing the gesture character of the inspection robot when it gets over the obstacles. This paper sets up the dynamitic model of robot by utilizing D-H. Based on that, it builds the Jacobian matrix by adopting differential transformation method, which establishes the foundation of the robots motion planning and real-time control.