一种新的机器人手臂控制方法

从机器人手臂的关节电机力学出发，本文提出了一种独立于现行机器人关节控制器的离线补偿方法，通过对－２自由度机器人的数值研究，证明该法不仅能有效地克服由于惯性负载，关节间耦合与重力效应给控制系统带来的动态精度问题，而且还可以消除由于控制系统本身的固有特性所决定的系统的跟踪误差。     

A frame-based knowledge representation model and its mapping to nested relations

The first part of this paper introduces the basic constructs of a frame representation model and gives a formal definition for them. Subsequently the nested relational model (NF²) is described as an extension of the classical relational model to support relation-valued attributes. In the second part of this paper both models are compared with each other and a mapping of frame representation structures to NF² structures is specified. The structural similarities between frames and NF² relations are made clear and it is shown that their main difference is due to the type polymorphism introduced by the concept hierarchy of the frame model. This causes type collisions to occur in the strictly typed NF² model when frames are directly mapped to NF² structures. Two solutions to this problem are suggested and compared. The paper concludes with a reformulation of query operations of the frame model in terms of NF² algebra operations.     

WSP特殊螺纹接头油井管的研制

介绍了WSP特殊螺纹接头的基本结构和设计思想,运用有限元方法,重点论述了密封设计和连接强度设计的方法和准则,并通过全尺寸试验进行了验证。计算和试验结果表明,该接头具有先进的螺纹形式、合理的扭矩台肩和金属/金属密封结构,有效地克服了API圆螺纹和偏梯形螺纹的不足,螺纹达到了与管体等强度,气密封能力达到了管体的内壁屈服压力。研究结果可以为开发更多适合油气田实际的特殊螺纹接头油井管提供参考。     

Cognitive Operations in the Generation Effect on a Recall Test: Role of Aging and Divided Attention.

Generation effect (generated words are better memorized than read words) of anagrams, rhymes, and associates of target words was examined in young, elderly, and very old subjects. Experiments 1 and 2 showed that only young subjects benefit from the generation effect in a free-recall test when the rule is of a phonological nature. Experiments 3, 4, and 5 showed that the generation effect of rhymes was due to a resources-dependent self-initiated process. Experiments 4 and 5 showed that in a divided-attention situation, generation effect of rhymes is not significant in young subjects, but that the generation effect of semantic associates remains significant for both groups (Experiment 5). The results are discussed within the environmental support framework and the transfer-appropriate processing framework. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Early detection of ageing in solder joints through laser probe thermal analysis of the peltier effect

We have recently developed an optical contactless method for testing the quality of solder joints during accelerated thermal cycling ageing processes.¹ The method was based upon the measurement of the dynamic thermal behaviour of the joint to short bursts of Joule heating. It has proved to be efficient in revealing the formation of cracks at the lead-solder interface. We present a method to evaluate ageing at a much earlier stage in the cycling process. We have observed in earlier work,¹ that before cracks appear, structural changes occur in the solder at the lead-solder interface. The thermal response of the solder joint is recorded over time to a Peltier heat perturbation produced by flowing a current pulse through the interface where structural changes occur. The key point in this method is to discriminate the Peltier effect from the Joule thermal response because both effects generate heat. The variation of the early Peltier response in the thermal cycling ageing tests is seen as a quantitative signature of the structural changes in the lead-solder interface.     

Modeling flotation separation in a semi-batch process

A model for a semi-batch flotation separation process has been developed, based on available microprocess probabilities, and compared to experimental data obtained using a WEMCO laboratory flotation cell. In general, the model predicts the correct experimental trends. In many cases, the model also predicts removal efficiency very well. Parametric studies reveal that the model predictions are sensitive to a stability parameter, the turbulent energy density in the flotation cell, the contact angle between the solid particle and fluid, and the ratio of initial-to-critical film thickness.     

钻杆防磨技术的现状和发展

在深井超深井勘探过程中，由于径向力、涡动、横向振动等因素的存在，随着钻井时间的增长，钻柱作用于套管内壁的侧向力增大，导致套管磨损的问题越来越严重。介绍了近年来钻杆防磨技术的发展，主要从钻杆接头表面处理和钻杆保护器2方面来研究防磨减磨措施的现状和发展。     

挠性抗回旋PDC钻头的有限元分析

回旋是导致PDC钻头早期失效的主要原因，介绍了一种基于挠性钻头的构想设计的抗回旋PDC钻头，阐述了其结构和抗回旋原理。对挠性钻头的公、母接头进行了有限元应力分析，说明了模型建立、网格划分以及约束和载荷施加过程中所采用的方法和关键技术。有限元分析结果表明挠性钻头的强度满足要求。     

面向表面组装工艺技术的PCB焊盘设计

尽管电子设计类软件已相当先进和方便，而且更新速度也很快，但是仍然无法满足各个层次的设计人员的需求，特别是适合各种元素封装形式的焊盘设计库并不能让设计和制造者满意，为了在此方面对PCB设计有所帮助，从印制电路板焊盘的设计方法入手，针对表面组装工艺技术特点，分析了PCB焊盘对PCA可靠性的影响因素，并根据相关的质量要求提出了较为简便的设计方案。