带式输送机测试台的研制

介绍了一种带式输送机性能测试台，论述了研制该装置的目的和设计思想，介绍了该装置的结构组成及在科研上的使用。利用该装置可以测试带式输送机多方面的性能参数。     

微操作并联机器人几何误差建模的参数误差转换法及误差敏感性分析

提出微操作并联机器人几何误差建模的参数误差转化法,建立正交结构6-PSS微操作并联机器人的几何误差模型,通过构造几何误差模型的Lagrange条件极值方程,对误差进行敏感性分析,最后讨论了各类参数误差在终端几何误差模型中的关联性。研究表明：所提出的方法简单明了,行之有效。     

1H-NMRD and17O-NMR assessment of water exchange and rotational dynamics of two potential MRI agents: MP-1177 (an extracellular agent) and MP-2269 (a blood pool agent)

The parameters that govern water proton magnetic relaxation (e.g. water exchange rates, and rotational and electronic correlation times) of representatives of two classes of Gd(III) complexes have been estimated, using two different approaches and the results compared with those derived for known analogs. The complexes studied are: (i) the non-ionic GdDTPA-bis(methoxyethyl-amide) [Gd(DTPA-BMEA)], a typical small-molecule extracellular MR agent, and (ii) the ionic Gd(III) complex of 4-pentylbicyclo[2.2.2]octane-1-carboxyl-di-l-aspartyl-lysine-derived-DTPA [GdL]⁴⁻, a prototype MR blood pool agent, which binds to serum albumin in vivo through non-covalent hydrophobic interactions. An¹⁷O-NMR study of [Gd(DTPA-BMEA)] gives a water exchange rate constant ofk _ex ²⁹⁸ =(0.39±0.02)×10⁶ s⁻¹, identical to that for the bismethylamide analog [Gd(DTPA-BMA)]. Both approaches yield longer rotational correlation times for [Gd(DTPA-BMEA)], consistent with its higher molecular weight. An¹⁷O-NMR study of [GdL]⁴⁻ gives a water exchange rate constant ofk _ex ²⁹⁸ =(4.2±0.1)×10⁶ s⁻¹, identical to that for [Gd(DTPA)]²⁻. The water exchange rate on [GdL]⁴⁻ did not decrease considerably when bound to albumin, the lowest limit isk _ex,GdL-BSA=k _ex,GdL/2. Both approaches yield identical rotational correlation times for [GdL]⁴⁻, however, it was difficult to derive a consistent rotational constant for the albumin-bound [GdL]⁴⁻ using the different approaches (values ranged between 1.0 and 23.0 ns).     

电气绝缘电压寿命指数N值的极大似然估计

电压寿命指数Ｎ 是描述绝缘老化性能的特征参数。由于二元Ｗｅｉｂｕｌｌ分布与电老化定律在评价绝缘电老化特性上存在等价性,为此给出了应用极大似然法对二元Ｗｅｉｂｕｌｌ分布进行参数估计从而获得电压寿命指数Ｎ 值的方法。出于演示和验证该方法的目的,最后给出了一个应用实例。     

新型高精度管材矫直机

介绍了西安重型机械研究所开发研制的“十一辊高精度管材矫直机”和“复合辊框架矫直机”的结构、布置、工作原理、机组型号、参数以及国内厂家的使用情况。实践证明, 新开发的矫直机结构合理、紧凑, 矫直精度高, 适用材质广泛, 生产效果良好。其中“十一辊高精度管材矫直机”获发明专利。     

探讨浓香型酒醅小茬与回缸发酵模型与产量质量的关系

在浓香型白酒的生产过程中,处于窖内中上部的小茬醅与回缸醅的发酵规律与位于窖池底部的大茬醅的发酵规律是完全不一致的.小茬与回缸醅的发酵是否正常对产酒数量以及原酒质量都起到十分重要的影响.通过深入研究和探索小茬、回缸等上层酒醅的发酵规律,得出普遍发酵规律曲线及异常发酵曲线,并从生产实际应用角度解析构建它们的最佳发酵模型,并...     

Mathematical Modelling and Simulation of Polymer Electrolyte Membrane Fuel Cells. Part I: Model Structures and Solving an Isothermal One-Cell Model

Amongst the various types of fuel cells, the polymer electrolyte membrane fuel cell (PEM-FC) can be used favourably in vehicles and for in house energy supply. The focus of the development of these cells is not only to provide cost-effective membranes and electrodes, but also to optimise the process engineering for single cells and to design multi-cell systems (cell stacks). This is a field in which we have successfully applied the methods of mathematical modelling and simulation. Initially, in this work, a partial model of a single membrane-electrode unit was developed in which the normal reaction technology fields (concentration, temperature, and flow-speed distributions) were calculated, but also the electrical potential and current density distribution in order to develop model structures for technically interesting PEM-FC. This allows the simulation of the effects that the geometric parameters (electrode and membrane data and the dimensions of the material feed and outlet channels) and the educt and coolant intake data have on the electrical and thermal output data of the cell. When complete, cell stacks consisting of a number of single cells, most of which have bipolar switching, are modelled the distribution of the gas flows over the single cells and the specific conditions of heat dissipation must also be taken into consideration. In addition to the distributions mentioned above, this simulation also produces characteristic current-voltage and power-voltage curves for each application that can be compared with the individual process variations and cell types, thus making it possible to evaluate them both technically and economically. The results of the simulation of characteristic process conditions of a PEM-FC operated on a semi-technical scale are presented, which have been determined by means of a three-dimensional model. The distributions of the electrical current density and all component voltage drops that are important for optimising the conditions of the process are determined and also the water concentration in the membrane as an important factor that influences the cell’s momentary output and the PEM-FC’s long-term stability.     

液压缸组合密封性能仿真与参数优化研究

通过改变伺服液压缸组合密封的结构型式,建立两种密封圈的仿真模型,利用ANSYS Workbench软件在静密封状态下,探究介质压力、压缩率、接触的摩擦因数对伺服液压缸密封性能的影响,并以密封圈最大Von-Mises应力和接触面最大接触压力作为密封性能的判定依据;而在动密封状态下建立泄漏量和启动压力动态特性的数学模型,并以二者数值大小作为密封性能的判定依据,从而优化密封圈的组成结构参数。结果表明:在静密封状态下,当改变其中任一参数时含有工字形圈的液压缸的最大Von-Mises应力和接触面最大接触压力明显优于含有O形圈的液压缸;而在动密封状态中,随着介质压力增加,两种模型的液压缸泄漏量不断减少,启动压力不断增加,并且含有工字形圈的液压缸泄漏量更少,表明工字形圈的密封性能优于O形圈的密封性能。而研究的工字形圈组合的格莱圈可为液压缸设计人员提供参考。     

详谈PCB钻孔孔壁镀铜开裂问题及解决方案

PCB作为重要的电子部件,其钻孔质量的优劣直接关系到产品性能的稳定程度,尤其在航空、航天、军事等重要领域,钻孔质量在电气连接特性及使用可靠性方面起着至关重要的作用。文章针对PCB钻孔过程中出现的孔壁镀层开裂问题,结合金属切削理论基础,从钻孔参数、刀具选择、板材结构与叠层、分段钻孔、材料对比等方面进行了详尽的分析与交叉实验比较,下面对具体解决过程与结果进行阐述。     

棒线材车间炉前送料弧形辊道主要参数确定

对棒线材车间炉前送料弧形辊道设计过程中的主要参数及其相互关系进行了分析,给出了计算公式,约束条件等。对其它工况的弧形辊道设计也有指导意义。