On the basis of the traditional mechanical model of a grinding wheel rotor and the mechanical-electric coupling model with ideal sinusoidal supply, taking high-frequency converting current of inverter power switches i...On the basis of the traditional mechanical model of a grinding wheel rotor and the mechanical-electric coupling model with ideal sinusoidal supply, taking high-frequency converting current of inverter power switches into further consideration, a modified mechanical-electric coupling model is created. The created model consists of an inverter, a motorized spindle, a grinding wheel and grinding loads. Some typical non-stationary processes of the grinding system with two different supplies, including the starting, the speed rising and the break in grinding loads, are compared by making use of the created model. One supply is an ideal sinusoidal voltage source, the other is an inverter. The theoretical analysis of the high-order harmonic is also compared with the experimental result. The material strategy of suppressing high-order harmonic mechanical-electric coupling vibration by optimizing inverter operating parameters is proposed.展开更多
Ultra-high-speed grinding(UHSG)is a significant and powerful machining method in view of the enhanced productivity and precision demands.Previous researches regarding formation mechanisms and crucial technologies are ...Ultra-high-speed grinding(UHSG)is a significant and powerful machining method in view of the enhanced productivity and precision demands.Previous researches regarding formation mechanisms and crucial technologies are comprehensively and thoroughly summarized to highlight state-of-art technology of UHSG.On the basis of the interdependence between process and machine innovations,theoretically,grinding mechanisms in strain hardening,strain rate strengthening,thermal softening,size effect and process characteristics need more in-depth studies to clarify the dominance of UHSG.Technically,CFRP wheel integrating with the brazed bonding has a prominent advantage in bonding strength and grit′s configuration over vitrified bonding,which would be superior in UHSG.Furthermore,external high pressure cooling combining with inner jet cooling methods,accompanied by scraper plates to alleviate the effect of air boundary,are crucial and practical measures for realizing effective cooling in UHSG.Grinding processes,especially those being related to grinding parameters and precise in-process measuring approaches,are also prerequisite for fitting and investigation of UHSG.展开更多
In this paper, we present a solution to the ultra low voltage inverter by adding a keeper transistor in order to make the semi-floating-gate more stable and to reduce the current dissipation. Moreover, we also present...In this paper, we present a solution to the ultra low voltage inverter by adding a keeper transistor in order to make the semi-floating-gate more stable and to reduce the current dissipation. Moreover, we also present a differential ULV inverter and elaborate on the reliability and fault tolerance of the gate. The differential ULV gate compared to both a former ULV gate and standard CMOS are given. The results are obtained through Monte-Carlo simulations.展开更多
This research proposes a new theory in the field of physics and space technology, based on several scientific hypotheses and conclusions, as it plans to manufacture a “new magnetic focus” by means of high-speed cent...This research proposes a new theory in the field of physics and space technology, based on several scientific hypotheses and conclusions, as it plans to manufacture a “new magnetic focus” by means of high-speed centrifugal engines, by equipping a group of them, and installing heavy, dense fans, not for the purpose of air pressure, Rather, it works to rotate at a speed of up to 1000 kilometers per hour at an angle of 45 degrees, and is lined up in front of each other in a circle, so that the final result is to transfer the effort and weight of the propellers to an upper point in their midst, and this point will reach a large degree of density, size and mass, causing the generation of a point independent magnetic attraction, which pulls the motors upward, as a result of the mutual gravitational effect created by the motors. These hypotheses need a large number of experiments, applications, and analyze the use of specialists in physics, technology, technology, engine engineers, and others, and the correct results will cause a major revolution in the field of space technology, and this theory will be relied upon in many means of land, air, and space transportation and different fields.展开更多
基金National Hi-tech Research and Development Program of China(863 Program,No.2008AA04Z116)and Natural Science Foundation of Hunan Province,China.
文摘On the basis of the traditional mechanical model of a grinding wheel rotor and the mechanical-electric coupling model with ideal sinusoidal supply, taking high-frequency converting current of inverter power switches into further consideration, a modified mechanical-electric coupling model is created. The created model consists of an inverter, a motorized spindle, a grinding wheel and grinding loads. Some typical non-stationary processes of the grinding system with two different supplies, including the starting, the speed rising and the break in grinding loads, are compared by making use of the created model. One supply is an ideal sinusoidal voltage source, the other is an inverter. The theoretical analysis of the high-order harmonic is also compared with the experimental result. The material strategy of suppressing high-order harmonic mechanical-electric coupling vibration by optimizing inverter operating parameters is proposed.
基金Supported by the National Natural Science Foundation of China(51235004)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)+1 种基金the Fundamental Research Funds for the Central Universitiesthe Funding of Jiangsu Innovation Program for Graduate Education(CXZZ13_0154)
文摘Ultra-high-speed grinding(UHSG)is a significant and powerful machining method in view of the enhanced productivity and precision demands.Previous researches regarding formation mechanisms and crucial technologies are comprehensively and thoroughly summarized to highlight state-of-art technology of UHSG.On the basis of the interdependence between process and machine innovations,theoretically,grinding mechanisms in strain hardening,strain rate strengthening,thermal softening,size effect and process characteristics need more in-depth studies to clarify the dominance of UHSG.Technically,CFRP wheel integrating with the brazed bonding has a prominent advantage in bonding strength and grit′s configuration over vitrified bonding,which would be superior in UHSG.Furthermore,external high pressure cooling combining with inner jet cooling methods,accompanied by scraper plates to alleviate the effect of air boundary,are crucial and practical measures for realizing effective cooling in UHSG.Grinding processes,especially those being related to grinding parameters and precise in-process measuring approaches,are also prerequisite for fitting and investigation of UHSG.
文摘In this paper, we present a solution to the ultra low voltage inverter by adding a keeper transistor in order to make the semi-floating-gate more stable and to reduce the current dissipation. Moreover, we also present a differential ULV inverter and elaborate on the reliability and fault tolerance of the gate. The differential ULV gate compared to both a former ULV gate and standard CMOS are given. The results are obtained through Monte-Carlo simulations.
文摘This research proposes a new theory in the field of physics and space technology, based on several scientific hypotheses and conclusions, as it plans to manufacture a “new magnetic focus” by means of high-speed centrifugal engines, by equipping a group of them, and installing heavy, dense fans, not for the purpose of air pressure, Rather, it works to rotate at a speed of up to 1000 kilometers per hour at an angle of 45 degrees, and is lined up in front of each other in a circle, so that the final result is to transfer the effort and weight of the propellers to an upper point in their midst, and this point will reach a large degree of density, size and mass, causing the generation of a point independent magnetic attraction, which pulls the motors upward, as a result of the mutual gravitational effect created by the motors. These hypotheses need a large number of experiments, applications, and analyze the use of specialists in physics, technology, technology, engine engineers, and others, and the correct results will cause a major revolution in the field of space technology, and this theory will be relied upon in many means of land, air, and space transportation and different fields.
