Papers by Keyword: Arc

Abstract: Usage of polymer materials in a quenching chamber is one of the most effective methods of improving performance of an air circuit breaker [1, 2]. During a high current interruption in the air circuit breaker, an arc discharge touches the insulator, and ablation gasses are emitted [3]. It is considered that the quenching performance and an arc characteristic are affected by this ablation gasses. In order to clarify the quenching performance of each polymer material, we are conducting the experiments. With these experiments, the relationships of the ablation gasses among the number of arcing cycles, arcing peak voltage, arcing conductances, and the pressure rise will be discussed with four kinds of polymer materials.

Abstract: We have investigated the influence of the modes of adaptive pulse-arc welding and surfacing on the structure and physical-mechanical properties of welded joints of steel 09Mn2Si and the surfaced composition of this steel coated with a modified powder material of chromium carbide with the submicrocrystalline structure. It is shown that the pulsed mode of welding and surfacing can improve the homogeneity of the structure of the welded joint of steel and a surfaced coating and reduce the grain size of metals in both of them. Structural changes lead to an increase in ductility and toughness of the weld metal.

Abstract: Using C/C composite and chrome bronze as a friction couple, the frictional wear properties of C/C composite with electric current is studied in this paper. The results have shown that current, velocity and load are important factors to affect the frictional wear properties of C/C composite with electric current. Wear rate of C/C composite increases with the increase of arc energy .The coefficient of friction and the wear rate increase with the increase of velocity when the electric current is constant of 100A. The coefficient of friction increases but the wear rate decreases with the increase of load when the electric current is constant at 100A. The coefficient of friction decreases but the wear rate increases with the increase of current when the load is constant of 80N. Comparing with no electric current, the coefficient of friction of C/C composite with electric current decreases but the wear rate of that increases obviously. The wear mechanism of C/C composite is mainly of electric wear caused by arc erosion under the condition of current-carrying.

Abstract: The influence of cadmium oxide on the thermal decomposition behaviors of AP-CMDB propellants was studied by differential scanning calorimetry (DSC) and accelerating rate calorimetry (ARC). The test results show that the decomposition process of AP-CMDB can be divided into two stages. Cadmium oxide can increase the initial temperature, slow down the decomposition rate and improve the thermal safety of AP-CMDB.

Abstract: For rotational parts with irregular curve profile, in order to achieve its manual programming and machining, we need to segment the contour curve according to the change of curvature. Through the calculation, we can get the minimum arc to fit the segments, and calculate the circular endpoint coordinates and radius by using the drawing methods. Finally, we develop the NC program. By the analysis of the result, we find the method can simplify the programming and improve machining efficiency.

Abstract: In this paper, combined with the first phase of wuhan rail transit line No. 4 line network management service center B building curtain wall engineering practical problems, Auto CAD auxiliary polar coordinate method is used to rapidly and accurately complete curved plane positioning pay-off, forming method, this method has been applied in several projects, produced good economic and social benefits.

Abstract: The thermal safety of one new-type DB propellant SZQu-1 was studied by ARC. The test results were compared with the one of double-base propellant SF-3. The ARC test results show that, in an ideal adiabatic environment, the initial exothermic temperature for SZQu-1 is 129.0°C, the adiabatic temperature rise is 787.0°C, the maximum self-heating rate is 23329.9°C/min, the maximum pressure rise rate is 51.2×10⁵Pa·min^-1, and the maximum pressure produced by unit mass is 124.1×10⁵Pa·g^-1. The activation energy E is 212.2kJ·mol^-1, the frequency factor A is 1.3×10²² s^-1, and T_D24 is 123.0°C, which are calculated by the velocity constant method. The studies have revealed that, comparing with SF-3, SZQu-1 has worse thermal stability and stronger explosiveness.

Abstract: This paper demonstrates the synthesis of planar four-bar for path generation. The feature is that the path includes an arc segment. The users can prescribe coordinates of arc center, a precision point on the arc, and the corresponding pole. The four-bar is synthesized mainly with the aid of the Bobillier theorem. The tasks that the paths or coupler curves pass through at most two additional precision points are also considered. Several nonlinear equations thus have to be derived and combined to find the coordinates of the pivots in synthesizing the four-bar.

Abstract: According to the shape of 3-arcs blade the distribution function equations on 3-arcs blade surface were deduced and the hydraulic characteristics on blade surface were analyzed. Based on the establishment of relative velocity and pressure equations, the step change equations of relative velocity and pressure on blade surface were also deduced on connected line which was formed by the intersection of two cambered surfaces, and the reason and the relationships between control parameters were revealed. The step change value of relative velocity is equal to diameter difference of two intersect arc cylinders. The step change value of pressure is concerned with the position coordinates of initial origin of two intersect arc cylinders. Calculation example confirmed that the step changes of relative velocity and pressure will appear on intersection of two cambered surface.

Abstract: This paper mainly imagined and designed a bionic impeller with arc shape lamina especially little arc lamina, researched on its hydrodynamic performance on the base of the prior hydrodynamic performance research on straight panel shape lamina. Applied FLUENT software to gain the figures on lift force, propulsion, pressure nephogram, velocity diagram and volume fraction distributing of bionic impeller when depth h is at -7.5 cm, 0cm and 7.5 cm, discussed and analyzed the rules of hydrodynamics when h was altering, tamped the groundwork of optimizing the externality design of the bionic impeller further.