Applied Mechanics and Materials Vols. 52-54

Abstract: Virtual flux oriented direct power control (VFDPC) is combined space vector modulation (SVM) with PI of DC-link voltage, active power and reactive power to control the grid side converter in wind power generation system in this paper. VFDPC has reached good performances with PLL (phase lock loop). First the mathematical models of grid side converter, LCL filter and phase lock loop are given. Then the control strategy of grid side converter-based wind power generation system is given in detail. Finally the simulation model is modeled consisting of power circuits, such as the grid side converter, LCL filter, transformer grid, and control parts, such as PI controllers of DC-link voltage, active power, reactive power, and SVM, and so on. The simulation results have verified that the control strategy is feasible to fit for control of gird currents, active power, reactive power and DC-link voltage in wind power generation system.

Abstract: Based on mass experiments, gain the relation between the consistence of diamond bit and life, power consumption and granularity. Considering the relation of them, deduce a new method of calcuation for consistence design of diamond bit according to the given depth map of incising rock with diamond. Proved by practice, the method of calculation has a better practicability and veracity.

Abstract: By analyzing the rock fragmentation mechanism of diamond in diamond bit, the rock cutting depth with diamond, the area of diamond pressing into rock, the load on each diamond and the pressure on rock from diamond are calculated. After analyzing the result of calculation, it comes to a conclusion that volume crushing contributes most in rock fragmentation process of diamond bit. The method of choosing diamond quality in diamond bit is also explained as well. Selecting the quality of diamond plays a vital role in product performance. The effectiveness of diamond bit is involved with not only the density and particle size of diamond, but also the quality of diamond. Based on analyzing the rock fragmentation mechanism of diamond, this paper researches on selecting diamond quality.

Abstract: The shelf-life of a Fruit is critical in determining both its quality and profitability. Everyone benefits from healthy produce. Approximately Rs.105Crores {$200million} is lost each year in India due to waste caused by post harvest diseases, poor temperature management, bruising and other factors. Shelf life is nothing but date of minimum durability. An apple is not dead at the time of harvest. It remains a living, respir¬ing organism and continues to take in oxygen and give off carbon dioxide and another gas, ethylene. Since the apple is no longer receiving nutrients from the tree but is still respiring, it must use up the food it has stored over the growing season. The low temperature, high humidity, and exchange of gases through air circulation serve to slow those natural events as much as possible. A mathematical relationship has been established for predicting the shelf life of an apple. Our study quantitatively takes in to account parameters such as firmness, colour of apple, atmospheric temperature, and respiration rate. This fundamental equation could be potentially used by farmers, food malls, and big food chains. This relationship can be extended to predict shelf life of perishable fruits.

Abstract: Safety and reliability of liquid ammonia storage tank is very important. The stress of manhole is high and complex, so it is necessary to analyse welding stress of manhole of liquid ammonia storage tank. This paper ignored the complex process in the weld pool, simulated complex thermal process in weld pool by continuous conductive welding heat source, deduced the calculation formula of maximum stress by establishing Gaussian heat source model of carbon dioxide welding, and modified stress exponent k of cylindrical pressure vessel. This new method has a positive meaning for welding stress analysis of pressure vessel.

Abstract: Silane treatment has been applied as a chromium free multi-metal surface treatment for its characteristics of corrosion protection, adhesion promotion and metal surface passivation. Vinyltriethoxysilane(VTES) hydrolysis solutions with the concentration of 4% and 10% were prepared, respectively. Morphologies and microstructures of the VTES films both before and after the corrosion test were observed with a scanning electron microscope (SEM), and effect of cure temperature on the corrosion resistance of silane film was studied combined with electrochemical impedance spectroscopy (EIS). The results showed that the cure temperature affects condensation states of silanol groups –Si–OH in silane films and promotes the forming of –Si–O–Si– network structure, and as a consequence influences the corrosion resistance of VTES films.

Abstract: Globalization has always been controversial, but the overwhelming trend has become a fact of life. Globalization has emerged and penetrated in each field of human social life, the development of the city is no exception. On the analysis of urban development under the background of globalization for the appeal of low carbon mode, we initially proposed the possible paths of low carbon economy for urban development.

Abstract: A multidisciplinary optimization method about the thickness of engine hood based on pedestrian protection was proposed. The impacting zones of engine hood where HIC values of original engine hood were higher than the safety value of 1000 were selected as the cases of optimization. At the same time, the stiffness of torsion of engine hood and the deformation distance between the hood and the underneath hard parts in the engine bay were taken into account. The objective was the minimization of hood deformation above where the hard parts were located. The first type of constraint was that the HIC values were less than the safety value 1000 in the selected cases of optimization. The second type of constraint was that the torsion stiffness of engine hood was higher than that of the regulation. The pedestrian protection optimization model about the thickness of engine hood was constructed and solved. The results of optimization indicated that the obtained thickness by this method improved the performance of pedestrian protection.

Abstract: Process Parameter of slub yarn determine style of its fabric. A new method of measuring process parameter of slub yarn was put forward to improve precision and efficient . The basic principal of parallel-plate capacitor was introduced in this paper. And sample yarns were tested with test system of slubby yarn developed by ourselves. Time sequence for slub length and slub space of slubby yarn can be gotten. And distribution of slub length , slub space and slub scaling factor can also be obtained. The agreement can be attained compared with those original setting. Some error was analyzed also. Consequently this testing system is effectively, and can be adopted in practice.

Abstract: High-precision slub yarn can be produced by EJM128K type ring bobbin equipped with servo control system which has the characteristic of stability ,precision and rapidity to control slub length by analyzing the transfer function of it. The length of slub yarns was tested with USTER® TESTER5, and the distribution curve of slub length and slub space can be attained. The gauge of between front and middle roller affects slub length deflection. This result can control effectively slub length and produce high-class slub yarn.