非圆齿轮-连杆型函数发生器的机构综合

给出了非圆齿轮－连杆型函数发生器综合时必须遵循的机构学制约条件，并提出了确定连杆机构处于极限位置时的非圆齿轮角速比的基本公式。以具有等速急回特性的曲柄滑块机构型函数发生器的机构综合为例，研制了有实用价值的非圆齿轮－连杆型函数发生器机构综合CAD软件。     

Potentiative effects of sulfhydryl compounds on carrageenin-induced oedema in rats and relationship to their potencies as inhibitors of angiostin-converting enzyme in vivo

Summary Carrageenin-induced oedema in rats was potentiated by oral administration of (4R)-3-[(2S)-3-mercapto-2-methylpropanoyl]-4-thiazolidinecarboxylic acid (SA291) and related sulfhydryl compounds, and the effect was closely correlated with their potencies as inhibitors of angiotensin-converting enzyme in vivo.Acknowledgment. The authors wish to thank Prof. H. Fujimura, Department of Pharmacology, Gifu University School of Medicine, for his helpful advice.     

Enhancing semiconductor device performance using ordered dopant arrays

As the size of semiconductor devices continues to shrink, the normally random distribution of the individual dopant atoms within the semiconductor becomes a critical factor in determining device performance--homogeneity can no longer be assumed. Here we report the fabrication of semiconductor devices in which both the number and position of the dopant atoms are precisely controlled. To achieve this, we make use of a recently developed single-ion implantation technique, which enables us to implant dopant ions one-by-one into a fine semiconductor region until the desired number is reached. Electrical measurements of the resulting transistors reveal that device-to-device fluctuations in the threshold voltage (Vth; the turn-on voltage of the device) are less for those structures with ordered dopant arrays than for those with conventional random doping. We also find that the devices with ordered dopant arrays exhibit a shift in Vth, relative to the undoped semiconductor, that is twice that for a random dopant distribution (- 0.4 V versus -0.2 V); we attribute this to the uniformity of electrostatic potential in the conducting channel region due to the ordered distribution of dopant atoms. Our results therefore serve to highlight the improvements in device performance that can be achieved through atomic-scale control of the doping process. Furthermore, ordered dopant arrays of this type may enhance the prospects for realizing silicon-based solid-state quantum computers.     

Grinding Characteristics Of Directionally Aligned SiC Whisker Wheel - Comparison With A12O3 Fiber Wheel

A unique SiC whisker wheel was invented, in which the whiskers were aligned normally to the grinding wheel surface. In this paper, grindabilities of the SiC whisker wheel are investigated and compared with those of other wheels of SiC grains, Al2O3 grains, as well as Al2O3 long and short fibres which were also aligned normally to the grinding wheel surface, respectively. The main research contents concern grinding characteristics of a directionally aligned SiC whisker wheel such as material-removal volume, wheel-wear rates, integrity of the ground surfaces, grinding ratios and grinding efficiency. Furthermore, grinding wheels of whiskers and fibres have a common disadvantage: they tend to load easily. The authors have proposed a simple method of loading-free grinding to overcome this propensity and investigate some related grinding characteristics under loading-free grinding conditions.     

基于洛毕达极限法则的机构奇异位置运动分析

提出了运用洛毕达极限法则分析机构通过死点或切换点的角速度或速比的新方法，并具体应用于具有切换点的GRASHOF neutral机构和GALLOWAY机构的运动分析，计算分析和实验结果证明：这两种特殊的平面双曲槽机构的运动周期是原动曲柄旋转二整周，而并非通常的一整周，发现当CALLOWAY机构的相对杆长差取很小值时，机构能输出具有超长近似停歇期和反向自锁特性的间歇运动，具有实用价值。     

台阶式溢洪道的消能问题

阐述了台阶式溢洪道的水流流况分类，叙述了在一定斜坡角度情况下的试验研究结论，并分析了台阶段各流况的试验资料下及游消力池水跃消能的试验资料，结果表明，台阶式溢洪道的总消能率可达95％左右，其中中台阶段消能率占85％以上，下游水跃消能只占总能量的10％左右，说明台阶式溢洪道具有很好的消能效果。     

Modification of visual,auditory, and somatosensory evoked responses in cortical primary receiving areas by nigral stimulation

Zusammenfassung Nachweis einer «unspezifischen» fördernden Wirkung von Stimulation der Substantia nigra auf «evoked potential» in den primären sensorischen Zentren des Grosshirns.

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Supported by a grant from the Japanese Ministry of Education.

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Acknowledgment. We thank Prof.N. Kato, Prof.Y. Iwase, Dr.S. Takahashi, and Dr.N. Tani for their help.     

Molecular dynamics simulation of the ice nucleation and growth process leading to water freezing

Upon cooling, water freezes to ice. This familiar phase transition occurs widely in nature, yet unlike the freezing of simple liquids, it has never been successfully simulated on a computer. The difficulty lies with the fact that hydrogen bonding between individual water molecules yields a disordered three-dimensional hydrogen-bond network whose rugged and complex global potential energy surface permits a large number of possible network configurations. As a result, it is very challenging to reproduce the freezing of 'real' water into a solid with a unique crystalline structure. For systems with a limited number of possible disordered hydrogen-bond network structures, such as confined water, it is relatively easy to locate a pathway from a liquid state to a crystalline structure. For pure and spatially unconfined water, however, molecular dynamics simulations of freezing are severely hampered by the large number of possible network configurations that exist. Here we present a molecular dynamics trajectory that captures the molecular processes involved in the freezing of pure water. We find that ice nucleation occurs once a sufficient number of relatively long-lived hydrogen bonds develop spontaneously at the same location to form a fairly compact initial nucleus. The initial nucleus then slowly changes shape and size until it reaches a stage that allows rapid expansion, resulting in crystallization of the entire system.