电磁感应式位置传感器研究

为了实现对各种行程与定位系统进行准确的位置测量,针对电磁感应式位置传感器的电磁感应系统展开研究,在了解电磁感应系统工作原理的基础上,利用毕奥-萨伐尔定律推导出了余弦形式的激励线圈在空间某一点处所产生的磁感应强度的计算公式,并进一步通过Ansoft Maxwell电磁场有限元分析软件建立了电磁感应式传感器的模型,并对其进行了仿真分析.结果表明:激励线圈周围产生的磁感应强度大小成对称分布,且在距离激励线圈平面±2 mm的范围内强度较大.同时,感应线圈中电流大小成正弦规律变化,且频率与激励源频率相等.由分析结果可知,实际设计中选取传感器移动转子与激励线圈之间的距离为2 mm较为合适.     

CONSTANT VELOCITY IN LIFTING AS A CRITERION OF MUSCULAR SKILL*

The derivation of a measure of skill from changes in velocity throughout a lifting movement was studied. The distances traversed by the wrists in lifting n 10 kg weight to the height of 1-67 in were recorded photographically with the aid of neon lights flashing at 0.1 sec intervals. The values of velocity, acceleration and force were computed at successive stages throughout each movement.

A shift from constant acceleration to constant velocity in movement was significant after training. The estimates of this trend were made by comparing within movement: (a) the mean acceleration with the mean acceleration in the central phase of movement, (b) the kinetic energy developed with the square of mean velocity, (c) the maximum with the mean velocity.

The following effects were shown: as lifting became faster during training the peak velocity approached a constant; the peak velocity was not appreciably increased but the velocity in the initial and final phases of movement was progressively raised towards the peak; this was most pronounced for the mean velocity of lifting 1 -6 m/see and coincided with the greatest work output per litre of expired air. With even faster lifting the constant acceleration reappeared together with a sharp decline of the work output per litre of expired air.

With constant velocity in lifting which involved a vast number of muscles, a reduced force, used with the maximal velocity, reflects the characteristic relation between velocity of contraction and force. With constant acceleration great force coincides with great velocity, suggesting that the elastic element of the muscle engages the contractile mechanism and that a time lag between the motor discharge and its sensory feedback occurs which takes the velocity of the limbs out of control.

On the behavioural level the correspondence, approaching one to one, between the maximum and the mean velocity in movement was statistically a sensitive measure of progress in acquisition of skill.     

基于改进的遗传算法求解可满足性问题

遗传算法(GA)是由Holland提出的一种基于进化论的仿生算法,非常适于求解最优化问题.为了更好地利用SGA求解SAT问题,在将SAT问题等价转换为{0,1}n上的多项式是否存在零点的判断问题基础上,将局部搜索算法(LSA)与SGA相结合,给出一种求解3-SAT问题的改进混合遗传算法(MHGA),并通过对随机大规模3-SAT问题实例的实际求解验证了MHGA的可行性与有效性.     

安泰1250m~3高炉渣处理系统设计特点

详细介绍安泰1 250 m3高炉渣处理系统的设计参数、工艺布置、工艺流程特点、主要设施配置以及设计存在的不足。设计中吸收平流法、嘉恒法、INBA法渣处理工艺的优点,对渣处理工艺作出合理布置,满足了高炉生产要求。     

浅议工程项目竣工后的财务会计管理

工程项目峻工后 ,按照项目法施工管理要求工程项目经理部需办完清欠交接后撤销。在清欠交接过程中财务管理上要精心组织 ,各部门要各司其职相互监督协调 ,并安排具体负责人员 ,使收尾工作完满、清楚     

Bayesian aggregation of experts'' judgements on failure intensity

Predictive modelling in the field of dependability, such as repair cost modelling, is usually based on the failure intensity function of repairable systems. The experience feedback data needed to estimate the failure intensity function is, however, seldom available due to the unique character of the systems. Thus approaches that can capture the tacit knowledge of designers, operators and maintenance personnel and transform this to the mathematical format required in the predictive models, are needed. A Bayesian statistical approach is presented, which yields posterior distributions of the parameters of the Power Law and the Log-Linear intensity functions, which are used to model the trend in the data observed. Model-checking criteria are presented according to which the relative performance of the selected functions can be assessed. Numerical examples are also given.     

BJ374大汽车主减速器的安装与调整

介绍了ＢＪ３７４大汽车主减速器一级传动付（螺旋锥齿轮）传动的基本条件及对齿面接触区的一般要求，分析了螺旋锥齿轮安装调整规律，提出了切实可行的安装调整方案。     

Recycling of glaze waste through hydrocyclone separation

The purpose of this work was to evaluate the applicability of hydrocyclone technology to separate glaze components for reuse in an industrial process. A laboratory size hydrocyclone system was constructed using industrial components. Preliminary work showed that clean separation of the waste into three particle size ranges; < 5, 5-20, and > 20 μm, would allow for each component to be recycled. Hydrocyclones were used to separate particles which have different sedimentation velocities, calculated based on Stokes Law, but could not separate systems with particles that had different sizes and densities but similar sedimentation velocities. Thus, particle behavior in the system correlated to what is predicted by Stokes Law, which is based on laminar flow.The particle size distributions of the separated glaze waste shifted towards the target values of < 5, 5-20, and > 20 μm, but were broad and overlapped slightly. A more efficient system would be required for the waste to be completely reusable. Selective agglomeration of glaze constituents was proposed to increase efficiency of separation by creating narrower, more distinct particle size distributions. Sedimentation and titration tests were used to estimate the isoelectric point of glaze constituents. Hypothetical calculations demonstrated that selective agglomeration could be used to significantly increase the sedimentation velocity of particles.     

浅析我国清洁生产制度及立法现状

改革开放以来,我国取得了举世瞩目的成绩。但与此同时,人均资源占有不足、环境恶化等问题也日益严重。清洁生产是实施可持续发展战略的重要措施和可持续发展的优先领域。《清洁生产促进法》为我国推进清洁生产、构建循环经济,缓解资源危机提供了法律依据。     

用运算放大器改进法拉弟电磁感应定律演示实验

许多物理教材中对法拉弟电磁感应定律的演示都是利用尽可能多匝数的线圈及磁性较强的磁铁,期望产生较 大的感生电流,但实际上往往难以收到良好的效果。利用F741运算放大器及发光二极管对此实验加以改进,收效显著。