A binary approximating method for graspable region determination of biped climbing robots

For a biped pole-climbing robot (BiPCR) with grippers, it is an essential demand to determine the target grasp configuration for climbing and transiting between poles, with the graspable region as a priori knowledge. The graspable region on the target pole is critically important for climbing path planning and motion control. To efficiently compute the graspable region for a BiPCR, we propose a novel binary approximating method in this paper. This method may also be applied to generate the three-dimensional (3-D) workspace of a manipulator with constant orientation. The grasping problem and the concept of graspable region for a BiPCR are first introduced. The binary approximating method and the corresponding algorithms are then presented to generate the graspable region. Additional constraints on a biped climbing robot with five degrees of freedom (DoFs) are presented as a supplement to the algorithm. A series of comprehensive simulations are conducted with the five-DoF and six-DoF climbing robots to verify the effectiveness of the proposed method. Finally, the dexterity of biped climbing robots with different DoFs is discussed.     

The effect of Al content on the wettability between liquid iron and MgOAl2O3 binary substrate

In the present study, the wettability between liquid iron with two different Al contents and MgOAl₂O₃ binary substrates was studied in reducing atmosphere. The contact angles between liquid iron with 18?ppm Al and MgO, MgO·Al₂O₃, Al₂O₃ were 133.5°, 113.7°, 126.9° respectively. With the variation of the substrate composition, the contact angles for the intermediate binary phases of the three components (MgO, MgO·Al₂O₃, Al₂O₃) obeyed the Cassie theory. In the experiment using iron with 370?ppm Al, all the contact angles were higher than that using low Al-containing iron. The surface of the iron drop was covered with an oxide layer, which mainly consisted of many small particles. With the variation of the substrate gradually from MgO to Al₂O₃, the composition of the oxide layer changed from MgO·Al₂O₃ to CaOAl₂O₃. The formation of the oxide layer prevented the spreading of liquid iron, leading to the increase of the contact angle.     

一种基于ARM的集中器的硬件实现

介绍了一种以ARM9为核心,以Windows CE5.0为操作系统的集中器。它符合国家电网的Q/GDW 374.2-2009技术标准,可以在国家电网中使用。给出了集中器的系统框图,介绍了集中器的主要实现电路,论述了其主要工作原理。     

An energy conservation replica placement strategy for Dynamo

With the fast development of cloud computing and wide application of cloud storage, the energy efficiency of cloud storage system is drawing significant attention from researchers or specialists. For the typical Dynamo cloud storage system, we design a new policy instead of the consistent hashing policy which is a combination of consistent hashing and sequential policy. The basic idea of this policy is that it divides the nodes into groups and allows each other to be mirror modes so it can find the full coverage subset of data items easily. Also we use autoregressive-moving-average model to estimate the task numbers of servers so that when under low utilization period, certain numbers of servers can be turned off to save energy. Based on the model, we demonstrate that it can save up to 23.7 % energy and maintain load balancing of servers. Furthermore, we compare our policy with Heuristic which is a classical energy conservation policy for cloud storage system that is based on consistent hash table. And we find several advantages of our policy which include finding the minimum subset of full coverage as well as other aspects.     

Cost-sensitive three-way email spam filtering

Email spam filtering is typically treated as a binary classification problem that can be solved by machine learning algorithms. We argue that a three-way decision approach provides a more meaningful way to users for precautionary handling their incoming emails. Three email folders instead of two are produced in a three-way spam filtering system, a suspected folder is added to allow users make further examinations of suspicious emails, thereby reducing the chances of misclassification. Different from existing ternary email spam filtering systems, we focus on two issues that are less studied, that is, the computation of required thresholds to define the three email categories, and the interpretation of the cost-sensitive characteristics of spam filtering. Instead of supplying the thresholds based on intuitive understandings of the levels of tolerance for errors, we systematically calculate the thresholds based on decision-theoretic rough set model. A loss function is interpreted as the costs of making classification decisions. A decision is made for which the overall cost is minimum. Experimental results show that the new approach reduces the error rate of misclassifying a legitimate email to spam and demonstrates a better performance for the cost-sensitivity aspect.     

Prediction of multicomponent adsorption equilibrium of gas mixtures including supercritical components

A new model to predict the adsorption equilibrium of mixtures containing supercritical components was presented. The difference in the adsorption mechanism between the supercritical components and the condensable components was accounted for in the new model. Lateral interaction in the adsorbed phase was also considered in the local isotherm. The new model was verified by the experimental data of the mixture CH₄/CO₂/C₂H₆ on activated carbon JX101 collected for 283-313 K and pressures up to . It was also verified with the experimental data published previously in literature. Considerable improvement in the prediction precision was achieved in using the new model to predict the adsorption of mixtures on activated carbon.     

UHMWPE纤维/LDPE复合材料防弹性能及机理研究

本文探讨了用超高分子量聚乙烯（UHMWPE）纤维增强低密度聚乙烯（LDPE）复合材料的防弹性能，研究了不同基体含量对复合材料防弹性能的影响。实验证明，UHMWPE纤维／LDPE复合材料具有较好的防弹性能，其最佳的基体含量在26％左右。同时，本文还通过分析防弹片材的断裂区域及复合材料的防弹机理确定了弹丸的变形情况和靶片“背凸”在防弹作用中的贡献。     

电除尘器绝缘子的设计与选择

根据电除尘器绝缘子的功能及工况条件，介绍了材质和结构形式的选择。对于电除尘器绝缘子材质的选择，首先要考虑承受运行电压的能力，其次是耐温性能和机械强度。对于结构形式的选择，应考虑有足够的厚度以耐电力冲击、足够大的爬电距离以防漏电或对地闪络、足够大的空间以防出现电晕或空间闪络。另外，介绍了高铝瓷绝缘子的成功应用及其优点。     

Investigation of allyl‐capped carbosilane dendrimers used as crosslinker for silicone rubber

High‐temperature vulcanized silicone rubber was prepared by using allyl‐capped carbosilane dendrimers, in which the core molecules were Si(CH₂CH?CH₂)₄ and Ph₂Si(CH₂CH?CH₂)₂ as crosslinker and nanoscale reinforcing filler, respectively. Allyl‐capped carbosilane dendrimers improved the mechanical properties of silicone rubber. The optimum tensile strength and tear strength were 9.6 MPa and 31.0 kN/m, respectively, when using SiG_n(allyl)m as the crosslinker and 10.1 MPa and 32.0 kN/m, respectively, when using Ph₂SiG_n(allyl)m as the crosslinker. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1772–1775, 2006     

数码辅助方法在毛细管流变仪测量粘度的应用

讨论了传统流变仪测量粘度上存在的问题，提出了改进的方案测量粘度，以减少误差。试验方案主要体现在用数码方法采集数据。