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Some combinatorial optimization problems arising from VLSI circuit design


This paper is basically a survey to show a number of combinatorial optimization problems arising from VLSI circuit design.


A packing of the complete directed symmetric graph DKv with mcircuits, denoted by (v,m)DCP, is defined to be a family of arcdisjoint mcircuits of DKv such that any one arc of DKv occurs in at most one mcircuit.


According to different mechanics and analytical models, end force resulting from open magnetic circuit of PMLSM was greatly decreased by optimizing the length of the PMLSM mover.


The coupling ratio of the two MMI couplers deviates from 50:50 but the deviation is nearly the same, which is decided by good uniformity of semiconductor planar lightwave circuit (PLC) process.

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An attempt was made to substantiate strictly the tensor point of view on the electric circuit that was first introduced in the classical works of G.


This force arises as a result of the interaction of the current in a rigid rod, at whose ends the devices which close the electric circuit through the circumterrestrial plasma are located, with the magnetic field of the Earth.


The electric field induced by the space charge of bunches and the presence of an external electric circuit are taken into account.


The dispersion analysis of the frequencies of the real and imaginary parts of the complex impedance made it possible to reveal a unified equivalent electric circuit for these cells and to calculate its parameters.


An equivalent electric circuit that represents the integral electric response of all individual components of the sample is proposed.

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An electronic circuit for amplitude and phase measurements of the forced vibrations of the tip of the scanning atomicforce microscope by the current flowing through the piezoelectric cell exciting these vibrations is described.


Mixing is accomplished using an original electronic circuit designed for polynomial nonlinear correction of the control signal.


The interrogation system is designed for the sensor, and consists of a lowcost laser diode, a 3dB fiber coupler, a detector, and an electronic circuit to the process signal.


In the present paper, an impactresistant ball structure is proposed: sensors, an electronic circuit, a radio transceiver and a battery are wrapped up in cushion material and packed into an impactresistant outer shell.


We have constructed an electronic circuit which accurately mimics the dynamics of a nonequilibrium, bistable flow driven by additive, exponentially correlated, Gaussian noise.

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As a result, the engine current circuit is closed on the internal duct walls and engine charging becomes insignificant.


A theoretical model of this generator operating into inductive storage and to break point of the current circuit is described.


The application of this effect in pulsed highcurrent circuit breakers is discussed.


A novel topology for ripplefree input current circuit is put forward in the paper.


The threshold amplitude of the primary KAW is calculated in units of the background magnetic field strength in the chromospheric section of loop current circuit.

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 The circumferential vibration of a hollow quartz cylinder has been thoroughly studied. The empirical relation connecting the dimensions of the cylinder and the frequency of vibration has been formulated, and the temperature coefficients of the frequency determined. The temperature coefficient is practically zero for a wide range of temperature, when the ratio of the internal radius to the external radius of the cylinder approaches a value which is very close to 0.5.  以纯粹水晶割成空心圆柱,令圆柱之轴平行於晶体之光轴。于其里外二面,敷以铜质管状电极、置诸最简单之Pierce式振荡线路中,即能自生振动其振动之方式繁多,俱经吾人详细阐求,已在另文发表,茲不复赘。 各种振动方式中,以绕周振动发生最易。设圆柱内径与外径之比小于一去0.5极近之数,则绕周分三段而振动;设大于此数,则分六段而振动, 绕周振动之温度系数,亦经测定其法置圆柱於一特制之电炉中,连其二电极於振荡电路,令生振动。以所生高周率电流与一周率甚近之水晶片所生之高周率电流相干涉,由 是而生之低周率音差,复与一低周率振荡器相比较,若是则加热后圆柱振动周率之变化,可在该低周率振荡器上直接读之。 若是所得之结果绕周振动之温度系数,随其内外径之比而异。圆柱之绕周分三段而振动者,其温度系数常为正;内外径之比率增加,则温度系数减少。圆柱之线周分六段而振动者,其温度系数常为负;内外径之比率愈高,则温度系数愈大。惟适当三段振动告终六段振动肇端之时,则亘十馀度其周率几不以温度而变合二十馀度而平均计之其温度系数约为0.5×10~(6)/C,小於寻常水晶片者五十馀倍。割制此种圆柱,并无繁难,且电极简单,装置便利以之控制振荡,校... 以纯粹水晶割成空心圆柱,令圆柱之轴平行於晶体之光轴。于其里外二面,敷以铜质管状电极、置诸最简单之Pierce式振荡线路中,即能自生振动其振动之方式繁多,俱经吾人详细阐求,已在另文发表,茲不复赘。 各种振动方式中,以绕周振动发生最易。设圆柱内径与外径之比小于一去0.5极近之数,则绕周分三段而振动;设大于此数,则分六段而振动, 绕周振动之温度系数,亦经测定其法置圆柱於一特制之电炉中,连其二电极於振荡电路,令生振动。以所生高周率电流与一周率甚近之水晶片所生之高周率电流相干涉,由 是而生之低周率音差,复与一低周率振荡器相比较,若是则加热后圆柱振动周率之变化,可在该低周率振荡器上直接读之。 若是所得之结果绕周振动之温度系数,随其内外径之比而异。圆柱之绕周分三段而振动者,其温度系数常为正;内外径之比率增加,则温度系数减少。圆柱之线周分六段而振动者,其温度系数常为负;内外径之比率愈高,则温度系数愈大。惟适当三段振动告终六段振动肇端之时,则亘十馀度其周率几不以温度而变合二十馀度而平均计之其温度系数约为0.5×10~(6)/C,小於寻常水晶片者五十馀倍。割制此种圆柱,并无繁难,且电极简单,装置便利以之控制振荡,校准周率,对无线电通讯,裨益实多也。  The object of the present work is to investigate the characteristics of piezoelectric resonantors which are cut from the natural coloured quartz, and compare the results with those obtained from those plates cut from the ordinary clear quartz in order to see if coloured quartz might be used as piezoelectric material in practice. In this work four points were stressed, they are: (1) the frequency constants of piezoelectric oscillation, (2) its stability, (3) its selectivity and activity and (4) its frequencytemperature... The object of the present work is to investigate the characteristics of piezoelectric resonantors which are cut from the natural coloured quartz, and compare the results with those obtained from those plates cut from the ordinary clear quartz in order to see if coloured quartz might be used as piezoelectric material in practice. In this work four points were stressed, they are: (1) the frequency constants of piezoelectric oscillation, (2) its stability, (3) its selectivity and activity and (4) its frequencytemperature coefficient curves. Further more a comparison of the characteristics of oscillations before and after the heattreatment of the material was made. By the results of these experiments it concludes that the natural coloured quartz plates can be excited into piezoelectric oscillation and serve as piezoelectric resonantors. The frequency constant of a Ycut plate from coloured quartz is about 2% lower than that of same type cut plate from clear quartz, while the frequency constants of the Xcut plate and the ATcut plate from the coloured and clear quartz are practically the same. The heattreatment to the three types cut plates of both kinds of quartz has a definite influence on their frequency. This effect is more pronounced to the coloured quartz plates. Likewise, heattreatment improves, from the pointview of statistics, the selectivity and activity of oscillation of both kinds of quartz. Finally, the values of some coefficients of stiffness of the coloured and clear quartz were discussed.  本文的目的在于研究天然有色水晶在当作压电共振器用时它的压电振荡性能,并与无色水晶在这方面的性能上作一比较,以推断有色水晶是否可以应用到实际的控制电路振荡的工作中去。我们的工作分四方面进行:(一)有色水晶压电振荡的频率常数,(二)有色水晶压电振荡的稳定性,(三)有色水晶压电振荡的选择性及活动性,(四)有色水晶压电振荡的频率——温度系数。并且把有色水晶在用热处理方法去色后的这四方面实验结果与去色前的作一比较。实验的结果证明有色水晶是可以被激发压电振荡的,和无色水晶一样可以作控制电路振荡之用。有色水晶的Y截法的频率常数比无色水晶的约低2％。至于两种水晶的其余两种X截法及AT截法的频率常数基本上无差别。热处理能使两种水晶的三种截法的压电振荡频率有增高的倾向,这效应在有色水晶中更为显著。同样,热处理对于两种水晶三种截法的压电振荡的选择性及活动性,在统计数字上看来是有益处的。最后,就以上测量的结果,推算了并讨论了有色水晶和无色水晶的若干劲度系数异同之点。  An equivalent circuit of transistors operating in saturation region is suggested. This circuit contains a transistor operating in active region and a diode biased in forward direction. By using this equivalent circuit, the physical meaning of storage time of transistors may be explained more intuitively. With this, the storage time in drift transistor, Which is common base connected, has been investigated. By solving the continuity equation, the steady state and the transient components of the densities of minority... An equivalent circuit of transistors operating in saturation region is suggested. This circuit contains a transistor operating in active region and a diode biased in forward direction. By using this equivalent circuit, the physical meaning of storage time of transistors may be explained more intuitively. With this, the storage time in drift transistor, Which is common base connected, has been investigated. By solving the continuity equation, the steady state and the transient components of the densities of minority carriers in diode near the pnjunction is obtained. By setting these two components equal in magnitude and opposite in sign, we get a formula, from which the storage time may be determined. The storage time in some special cases has been calculated. The results show that the storage time depends upon the life time of minorities and the surface recombination velocities both in base region and in collector region. This may be a guide for design a transistor with more short storage time.  半导体三极管在饱和区工作时,其等效电路可以用一个三极管及一个由集电极及基极构成的二极管联成的电路表示出来,其中三极管在有源区工作,而二极管在正向偏压下工作。这样的等效电路具有比较明显的物理意义。利用这个电路来求漂移管在一个共基极电路中脉冲工作下的储存时间。解出非平衡少数载流子的连续性方程,求出二极管pn结附近非平衡少数载流子密度的稳定态分量及暂态分量,从而得到决定储存时间的方程。计算结果表明,储存时间与基极区域及集电极区域中非平衡载流子的寿命及表面复合速度有关。减少寿命及增加表面复合速度就可以减少储存时间。   << 更多相关文摘 
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