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江阴是一个近一百万人口、九十万农民的农村县。多年来,我们把搞好农村发行,当作重点来抓。县书店两个经理,一个专管农村发行。在县城,书店有一个综合门市部,三个书亭。在农村,有常年售书点37个,农村专、兼职图书发行员74人。平均每两个农村大队有一个图书代销店。书店配备8个专职农村发行员,常年在农村开展流动供应和辅导供销社售书点。1980年,在县以下农村共发行90多万元图书,比上年增加40％,全县每人平均购书额(不包括课本)达到1.05元,比上年每人平均0.56元增加88％。 相似文献
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A system for measuring the quality parameters of elevator guide rails is developed. The quality parameters the system can measure include straightness, flatness, squareness, width and height of the rail. The system consists of six parts:main guideway, auxiliary guideway, reference rail, saddle, control casing and measured rail. The guide rail to be measured is mounted on a bed. The straightness errors of surfaces are checked by five linear displacement sensors mounted on the saddle. The deviation of readings from the sensor, which is in contact with top guiding surface, gives the straightness error of the surface and height of the rail. The other four sensors are used to measure side guiding surfaces respectively and give other parameters including flatness on the surfaces, squareness, width and height of the rail. A novel calibration method is also developed to calibrate the straightness motion error of the system in horizontal and vertical directions. The deflection deformation of the measured rail is fitted by using a fourth-order polynomial. Experimental results show that the uncertainty of the system on the side surfaces after compensating the straightness motion error is less than 0. 01 mm, and the uncertainty of the system on the top surface after compensating the straightness motion error and the deflection deformation of the rail is less than 0.03 mm. 相似文献
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假设人脑存储着肢体的几何和动力学模型 ,以一个多层感知网络代表这个内部模型 ,仿真了在三种不同情况下人体肘关节韵律运动 :1)内部模型的参数与肢体的几何和动力学模型参数完全匹配 ,2 )上述参数不匹配 ,3 )存在外界干扰 .仿真结果显示模型的参数不匹配是导致肢体韵律运动误差的主要原因 .由此可见 ,运动学习过程就是内部模型不断更新以匹配肢体几何和动力学模型的过程 相似文献
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Neural microelectrode has been used by neuro-physiologists to explore the neural system for over ahalf century. In 1950, the metal thread, called thefirst microelectrode, was invented[1]. The progresshas been strongly dependent on the technologies avail-able for providing microelectrode assembly for high-quality, long-term stable neural recording and forstimulation of specific populations of neural cells. In1965, Moll suggested that the lithographic techniquesand silicon etching technology tha… 相似文献
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