1,648 research outputs found

    Development of Arm Exo-skeleton for Bicep Brachii Muscle

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    This report presents the study on design of arm exoskeleton for stroke rehabilitation purpose. The mechanical design of the exoskeleton focuses on few aspects of the arm exoskeleton which are length and the design of the exoskeleton and motor specification. Besides, the experiment of obtaining surface electromyography (sEMG) signal for repetition training for physiotherapy patient purpose is carried out to observe the difference in amplitude and muscle signal of different subjects (four males and four females) due to the amount of training and the angle of the training. The signals are filtered and the average of the root mean square of the data is compared

    Micromechanics model for predicting effective elastic moduli of porous ceramic matrices with randomly oriented carbon nanotube reinforcements

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    Multi-step micromechanics-based models are developed to predict the overall effective elastic moduli of porous ceramic with randomly oriented carbon nanotube (CNT) reinforcements. The presence of porosity in the ceramic matrix that has been previously neglected in the literature is considered in present analysis. The ceramic matrix with porosity is first homogenized using a classical Mori-Tanaka model. Then, the homogenized porous ceramic matrix with randomly oriented CNTs is analysed using two micromechanics models. The results predicted by the present models are compared with experimental and analytical results that have been reported in literature. The comparison shows that the discrepancies between the present analytical results and experimental data are about 10% for 4 wt% of CNTs and about 0.5% for 8 wt% CNTs, both substantially lower than the discrepancies currently reported in the literature

    Modelling powder-binder segregation in powder injection moulding

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    Powder injection moulding (PIM) is a shape forming technique for advance ceramic or metal that allows low cost and complex shape manufacturing. The segregation between powder and binder is a common occurrence during PIM which leads to the inhomogeneity in the green bodies. A multiphase flow numerical model has been developed based on Eulerian approach to simulate this phenomenon in the injection stage of silicon nitride-based ceramics. A viscosity model based on experimental data of the feedstock is employed in the numerical model. Simulated results from the numerical model have been compared with experimental results. A powder distribution analysis is compared with density distribution test of the green bodies with similar process parameters and flow trends is compared experimental short shots

    Powder distribution on powder injection moulding of ceramic green compacts using thermogravimetric analysis and differential scanning calorimetry

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    Powder-binder separation during injection moulding causes defects such as cracking, warpage or anisotropic shrinkage during firing. In this paper, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) that were previously used to analyse powder distribution within the green body for metal injection moulding are used for ceramics. TGA and DSC are used to characterize the mass loss and heat of fusion of the binder system, silicon nitride feedstock and test-bars. TGA can measure the volume fraction of powder in green parts directly with 1.76 vol% difference from nominal volume fraction and variations up to 0.177 vol%. The DSC empirical model predicted volume fraction of powder in green parts with 1.76 vol% difference from nominal volume fraction and variations up to 1.710 vol%. Using rule of mixture, it over predicted volume fraction of powder in green parts by 6.78 vol% from nominal volume fraction and with variations up to 2.510 vol%

    The Role of Weight on Community Structure of Networks

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    The role of weight on the weighted networks is investigated by studying the effect of weight on community structures. We use weighted modularity QwQ^w to evaluate the partitions and Weighted Extremal Optimization algorithm to detect communities. Starting from idealized and empirical weighted networks, the distribution or matching between weights and edges are disturbed. Using dissimilarity function DD to distinguish the difference between community structures, it is found that the redistribution of weights does strongly affect the community structure especially in dense networks. This indicates that the community structure in networks is a suitable property to reflect the role of weight.Comment: 10 pages, 6 figure

    Modelling powder-binder segregation in powder injection moulding

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    Powder injection moulding (PIM) is a shape forming technique for advance ceramic or metal that allows low cost and complex shape manufacturing. The segregation between powder and binder is a common occurrence during PIM which leads to the inhomogeneity in the green bodies. A multiphase flow numerical model has been developed based on Eulerian approach to simulate this phenomenon in the injection stage of silicon nitride-based ceramics. A viscosity model based on experimental data of the feedstock is employed in the numerical model. Simulated results from the numerical model have been compared with experimental results. A powder distribution analysis is compared with density distribution test of the green bodies with similar process parameters and flow trends is compared experimental short shots

    Effective-stress finite element analysis of spudcan penetration with lattice leg in clay

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    10.1063/1.4826009AIP Conference Proceedings15582337-234

    Network of Econophysicists: a weighted network to investigate the development of Econophysics

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    The development of Econophysics is studied from the perspective of scientific communication networks. Papers in Econophysics published from 1992 to 2003 are collected. Then a weighted and directed network of scientific communication, including collaboration, citation and personal discussion, is constructed. Its static geometrical properties, including degree distribution, weight distribution, weight per degree, and betweenness centrality, give a nice overall description of the research works. The way we introduced here to measure the weight of connections can be used as a general one to construct weighted network.Comment: 6 pages, 7 figure
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