The high precision assemblies with considerable radial interference should be accompanied by heating and cooling processes.However,the mechanical properties of metals are greatly affected by thermal operations.So,for ...The high precision assemblies with considerable radial interference should be accompanied by heating and cooling processes.However,the mechanical properties of metals are greatly affected by thermal operations.So,for evaluating the stress distribution and distortion of teeth profiles in a gear/shaft assembly,a transient thermal analysis is necessary for finding the change in mechanical properties.The friction on the contact surface is another important parameter in interaction of the gear with the shaft.Evaluating the gear stress and deformation fields for several modes of heat transfer and friction coefficients showed that the maximum radial or tangential stresses on contact surface of the joint may have more than 8%increase by increasing friction coefficient;while the intensity of heat transfer at cooling stage has lower effect on stress distribution.展开更多
Traditional information retrieval systems respond to user queries with ranked lists of relevant documents. Since, XML （Extensible Markup Language） documents separate content and structure; XML-IR （information retri...Traditional information retrieval systems respond to user queries with ranked lists of relevant documents. Since, XML （Extensible Markup Language） documents separate content and structure; XML-IR （information retrieval） systems are able to retrieve only the relevant portions of documents. Therefore, users who utilize an XML-IR system could potentially receive highly relevant and precise material. We have developed the XML information retrieval system by using MySQL and Sphinx, which we call MEXIR. In our system, XML documents are stored into one table that has fixed relational schema. The schema is independent of the logical structure of XML documents. Each node in XML documents is represented by labels that express the positions in XML tree, namely ADXPI scheme. Our system has performance experiments on INEX collections and shown an average up to four seconds better than GPX. In addition, it has been reduced the size of the data down by 82.29 % compare to GPX system.展开更多
A novel fiber Bragg grating （FBG） rain gauge is proposed in this paper to achieve high precision rainfall measurement. One core sensitive FBG, a temperature compensation FBG and a mechanical transition system constr...A novel fiber Bragg grating （FBG） rain gauge is proposed in this paper to achieve high precision rainfall measurement. One core sensitive FBG, a temperature compensation FBG and a mechanical transition system construct this novel FBG rain gauge. Sensing principle of this FBG rain gauge is explained in detail, and its theoretical calculation model is also established, which shows that the relationship between center wavelength of sensitive FBG and external rainfall has very good linearity. To verify its detection performance, the calibration experiment on one prototype of this FBG rain gauge is carried out. After experiment data analysis, the detection precision of this FBG rain gauge is 15.4/.tm which is almost two orders of magnitude higher than that of the existing rainfall measurement device. The experimental data confirm that this FBG rain gauge can achieve rainfall measurement with high precision.展开更多
文摘The high precision assemblies with considerable radial interference should be accompanied by heating and cooling processes.However,the mechanical properties of metals are greatly affected by thermal operations.So,for evaluating the stress distribution and distortion of teeth profiles in a gear/shaft assembly,a transient thermal analysis is necessary for finding the change in mechanical properties.The friction on the contact surface is another important parameter in interaction of the gear with the shaft.Evaluating the gear stress and deformation fields for several modes of heat transfer and friction coefficients showed that the maximum radial or tangential stresses on contact surface of the joint may have more than 8%increase by increasing friction coefficient;while the intensity of heat transfer at cooling stage has lower effect on stress distribution.
文摘Traditional information retrieval systems respond to user queries with ranked lists of relevant documents. Since, XML （Extensible Markup Language） documents separate content and structure; XML-IR （information retrieval） systems are able to retrieve only the relevant portions of documents. Therefore, users who utilize an XML-IR system could potentially receive highly relevant and precise material. We have developed the XML information retrieval system by using MySQL and Sphinx, which we call MEXIR. In our system, XML documents are stored into one table that has fixed relational schema. The schema is independent of the logical structure of XML documents. Each node in XML documents is represented by labels that express the positions in XML tree, namely ADXPI scheme. Our system has performance experiments on INEX collections and shown an average up to four seconds better than GPX. In addition, it has been reduced the size of the data down by 82.29 % compare to GPX system.
文摘A novel fiber Bragg grating （FBG） rain gauge is proposed in this paper to achieve high precision rainfall measurement. One core sensitive FBG, a temperature compensation FBG and a mechanical transition system construct this novel FBG rain gauge. Sensing principle of this FBG rain gauge is explained in detail, and its theoretical calculation model is also established, which shows that the relationship between center wavelength of sensitive FBG and external rainfall has very good linearity. To verify its detection performance, the calibration experiment on one prototype of this FBG rain gauge is carried out. After experiment data analysis, the detection precision of this FBG rain gauge is 15.4/.tm which is almost two orders of magnitude higher than that of the existing rainfall measurement device. The experimental data confirm that this FBG rain gauge can achieve rainfall measurement with high precision.
