Robotic hand system design for mirror therapy rehabilitation after stroke

Microsystem Technologies - This paper developed a robotics-assisted device for the stroke patients to perform the hand rehabilitation. Not only the system can perform passive range of motion...     

子空间聚类改进算法研究综述

高维数据聚类是聚类技术的难点和重点,子空间聚类是实现高维数据集聚类的有效途径。CLIQUE算法是最早提出的基于密度和网格的子空间聚类算法,自动子空间聚类算法的实用性和高效性,带来了子空间聚类算法的空前发展。深入分析CLIQUE算法的优点和局限性;介绍了一些近几年提出的子空间聚类算法,并针对CLIQUE算法的局限性作了改进,聚类的效率和精确性得到了提高;最后对子空间聚类算法的发展趋势进行了讨论。     

Attribute selection method based on a hybrid BPNN and PSO algorithms

High dimensional data contain many redundant or irrelevant attributes, which will be difficult for data mining and a variety of pattern recognition. When implementing data mining or a variety of pattern recognition on high dimensional space, it is necessary to reduce the dimension of high dimensional space. In this paper, a new attribute importance measure and selection methods based on attribute ranking was proposed. In proposed attribute selection method, input output correlation (IOC) is applied for calculating attribute’ importance, and then sorts them according to descending order. The hybrid of Back Propagation Neural Network (BPNN) and Particle Swarm Optimization (PSO) algorithms is also proposed. PSO is used to optimize weights and thresholds of BPNN for overcoming the inherent shortcoming of BPNN. The experiment results show the proposed attribute selection method is an effective preproceesing technology.     

Design method for stabilization of earth slopes with micropiles

As one of the measures for slope fast reinforcement, micropiles are always designed as a group. In this paper, an analytic model for the ultimate resistance of micropile is proposed, based on a beam–column equation and an existing p–y curve method. As such, an iterative process to find the bending moment and shear capacity of the micropile section has been developed. The formulation for calculating the inner force and deflection of the micropile using the finite difference method is derived. Special attention is given to determine the spacing of micropiles with the aim of achieving the ultimate shear capacity of the micropile group. Thus, a new design method for micropiles for earth slope stabilization is proposed that includes details about choosing a location for the micropiles within the existing slope, selecting micropile cross section, estimating the length of the micropile, evaluating the shear capacity of the micropiles group, calculating the spacing required to provide force to stabilize the slope and the design of the concrete cap beam. The application of the method to an embankment landslide in Qinghai province, China, is described, and monitoring data indicated that slope movement had effectively ceased as a result of the slope stabilization measure, which verified the effectiveness of the design method.     

Understanding the Formation of Limited Interlamellar Bonding in Plasma Sprayed Ceramic Coatings Based on the Concept of Intrinsic Bonding Temperature

Interlamellar bonding is an important factor controlling the mechanical, thermal and electrical properties of plasma sprayed ceramic coatings. In order to understand the formation of limited interlamellar bonding, a theoretical model is proposed based on the concept of the intrinsic bonding temperature. The numerical simulation of the interface temperature between a molten splat and underlying splats was performed for splats with uniform and non-uniform thickness, in order to reveal the conditions for the interlamellar bonding formation. The interlamellar bonding ratio was theoretically estimated based on the bonding forming conditions. The features of interlamellar bonding revealed by the simulation agree well with the experimental observations. The bonding ratio of plasma sprayed coatings is significantly influenced by the distribution of splat thickness. According to the distribution of Al₂O₃ splat thickness in the coating, the theoretical estimation of bonding ratio yielded a value of 0.41 for the plasma sprayed Al₂O₃ coating at the ambient atmosphere conditions, which is reasonably consistent with the observation value. Therefore, the limited interlamellar bonding can be reasonably explained based on the sufficient condition that the maximum interface temperature between a molten splat and underlying splats is larger than the intrinsic bonding temperature.     

Novel epoxy/expandable graphite halogen-free flame retardant composites−preparation, characterization, and properties

In this work, expandable graphite (EG) was grafted using a coupling agent, 3-isocyanatopropyltriethoxysilane (IPTS). EG has a -O-C₂H₅ (-OEt) functional group which reacts with a polymer matrix through the sol-gel reaction. EG was functionalized by the coupling agent to form a covalent bonding between organic and inorganic phases, increasing the compatibility between the fillers and polymer, and thereby enhancing the thermal stability of the composites. FT-IR and X-ray photoelectron spectroscopy (XPS) were adopted to characterize the grafting reaction between IPTS and EG. Thermogravimetric analysis (TGA), the derivative of thermogravimetric weight (DTG) and the difference between the thermogravimetric weights (TG△) were employed to calculate the thermal stability of the composites. The limiting oxygen index (LOI) was utilized to classify the composites by flame retardancy. A scanning electron microscope (SEM) was applied to observe their morphology, and the behavior of expansion was discussed after the materials were burnt. TGA/MS was used to analyze the gas products during thermal degradation. The results demonstrate that functionalized EG can improve the thermal stability of composites and increase the flame retardancy.     

Adaptive coding scheme for wireless LANs with CSMA/CA MAC protocol

The generalised type II hybrid automatic repeat-request scheme based on rate-compatible convolutional codes is used to achieve adaptive error protection in wireless local access networks (LANs) with the CSMA/CA protocol. Simulation results show that this coding scheme is a suitable error control method for wireless LANs where the channel state is unpredictable     

Analysis of Radiated Fields for the Design of a RJ45 Connector Using FDTD Method

The finite-difference time-domain (FDTD) method is successfully used to calculate the electric fields radiated from a prototype of a RJ45 connector for Ethernet transmission. Simulation results of the electric fields radiated from the prototype of this RJ45 connector are validated by measurement data for vertical and horizontal polarizations in 300 ~ 1000 MHz frequency range. It is also found that simulation and measurement results for both vertical and horizontal polarizations are over the regulation limit at 600 MHz. In order to meet regulation limits, further studies are also conducted by taking numerous possible affecting factors on radiated electric fields into consideration for FDTD simulations; these include the aperture area, the location of the excitation, the material used for the aperture, enclosures with and without grounding. From simulation results presented in this paper, it is found that the magnitude of the higher emission levels can be reduced by reducing the aperture area, putting the location of excitation deeper into the connector, using materials with smaller dielectric constants and conductivities for the aperture, and adding a grounding enclosure on the RJ45 connector.     

Memory-aware kernel mechanism and policies for improving internode load balancing on NUMA systems

Although nonuniform memory access architecture provides better scalability for multicore systems, cores accessing memory on remote nodes take longer than those accessing on local nodes. Remote memory access accompanied by contention for internode interconnection degrades performance. Properly mapping threads to cores and data accessed to their nodes can substantially improve performance and energy efficiency. However, an operating system kernel's load-balancing activity may migrate threads across nodes, which thus messes up the thread mapping. Besides, subsequent data mapping behavior pays for the cost of page migration to reduce remote memory access. Once unsuitable threads are migrated, it is detrimental to system performance. This paper focuses on improving the kernel's internode load balancing on nonuniform memory access systems. We develop a memory-aware kernel mechanism and policies to reduce remote memory access incurred by internode thread migration. The Linux kernel's load balancing mechanism is modified to incorporate selection policies in the internode thread migration, and the kernel is modified to track the amount of memory used by each thread on each node. With this information, well-designed policies can then choose suitable threads for internode migration. The purpose is to avoid migrating a thread that might incur relatively more remote memory access and page migration. The experimental results show that with our mechanism and the proposed selection policies, the system performance is substantially increased when compared with the unmodified Linux kernel that does not consider memory usage and always migrates the first-fit thread in the runqueue that can be migrated to the target central processing unit.     

基于簇内乘积量化的最近邻检索方法

本文针对大规模高维数据近邻检索中的瓶颈问题,提出基于向量量化的一种检索方法—簇内乘积量化树方法.该方法运用向量量化和乘积量化的多层树状结构高效表征大规模高维数据集,与现有方法相比降低了索引表空桶率;其次提出基于贪心队列的近邻簇筛选方法减小了计算复杂度,加快了近邻检索速度;最后提出面量化方法用于近似计算候选数据集向量与查询向量间的距离,与点量化和线量化方法相比量化误差更小,提高了近邻查询准确率.本文提出的簇内乘积量化树算法在算子Sift和Gist描述的大规模高维数据集上与乘积量化树技术相比,首次召回准确率提高了57.7%,索引表空桶率降低幅度在50%以上,与局部优化乘积量化技术相比,查全率高达97%,而查询时间却仅需原来的1/9.实验结果表明本文提出的基于簇内乘积量化的近邻方法提升了近邻检索性能,为大规模高维数据集近邻检索提供了理论支持.