This paper presents a novel capacitance probe,i.e.,parallel-wire capacitance probe(PWCP),for two-phase flow measurement.Using finite element method(FEM),the sensitivity field of the PWCP is investigated and the optimu...This paper presents a novel capacitance probe,i.e.,parallel-wire capacitance probe(PWCP),for two-phase flow measurement.Using finite element method(FEM),the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters.Then,the response of PWCP for the oil-water stratified flow is calculated,and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness,and is almost independant of the angle between the oil-water interface and the sensor electrode.Finally,the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.展开更多
Based on the study of the characteristics of the cloud, firstly the interference mechanism of the capacitance proximity fuze passing through the cloud has been studied. Analysis shows that the medium property of the c...Based on the study of the characteristics of the cloud, firstly the interference mechanism of the capacitance proximity fuze passing through the cloud has been studied. Analysis shows that the medium property of the cloud only, has little effect on the capacitance proximity fuze. Secondly, the adherence interference of the cloud to capacitance proximity fuze has been studied for the first time in this paper. Then finite element analysis (FEA) method has been used to simulate the adherence interference of the cloud. Simulation result shows that the cloud adherence effect interferes the output of the capacitance fuze greatly. At last, experiments have been made for the study of the cloud interference.展开更多
Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue...Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue resistance to cyclic motion, and noiseless operation. Nitinol has found application in tactile displays which reproduce tactile parameters such as texture and shape, depending on the application. This paper presents the effects of thermal interference between adjacent Nitinol spring actuators in a tactile display. The tactile display is made of a 3 by 3 pin array whose spatial resolution was varied from 4 mm to 6 mm in steps of 1 mm while a current of 1.5 A was used to actuate 8 of the springs, and the centre spring was left unactivated to observe the thermal effects on it due to the heat gradient formed. A Finite Element (FE) model was developed using COMSOL Multiphysics and the results were further verified through experimentation. In both cases, there was visible thermal interference between actuators. The increase in spatial resolution saw a decrease in thermal interference by 12.7%. Using a fan to introduce forced convection, reduced the thermal interference in the simulation by 20% and during experimentation by 11%. The results of this research indicate a spatial resolution of 6 mm reduced the thermal inference to a negligible rate. However, thermal interference could not be eliminated with these two methods.展开更多
A numerical calculation method based on the finite element analysis of dynamic characteristics of artillery-fuze system is discussed in detail. Pretension element is used to mesh the couple structure between artillery...A numerical calculation method based on the finite element analysis of dynamic characteristics of artillery-fuze system is discussed in detail. Pretension element is used to mesh the couple structure between artillery and fuze to analyze the change of dynamic characteristics of artillery-fuze system when pre-tightening force varies between artillery and fuze. Numerical calculation of the finite element analysis and actual hammering test of a artillery-fuze system are carried out with the same input to verify the accuracy of numerical calculation. The results show that the finite element model of artillery-fuze system is credible and the calculation accuracy is perfect.展开更多
Water Tree is a corrosion phenomenon in cross-link polyethylene (XLPE) insulation. It is commonly found in underground cables. Water tree induced fault is difficult to detect due to its high impedance and difficult to...Water Tree is a corrosion phenomenon in cross-link polyethylene (XLPE) insulation. It is commonly found in underground cables. Water tree induced fault is difficult to detect due to its high impedance and difficult to model due to its random nature. In recent years, underground cables have become more popular in the power industry. They are resistant to environmental damage and has reduced space requirement. They are suitable to areas with high environment hazard or heavily populated areas where space is a constraining factor. As a result, studying and modeling the structure and effect of water tree become increasingly important. Since majority of the fault inducing water trees are vented trees which originated from the surface of the cable insulation, the mathematical model focuses on this particular type of water tree. To reduce the complexity of the model, the shape of the water tree afflicted region of the insulation is assumed to be ellipsoidal and the permittivity of the region is assumed to be linearly changing. Finite element analysis is used to analyze the water tree affected region. The resultant capacitance is calculated and compared with a physical model from Comsol. The result obtained using the proposed mathematical model and the result obtained using physical simulation through Comsol package agrees with each other. Hence, this method can be used to analyze the effect of water tree fault in large power systems.展开更多
This paper presents a numerical analysis for computation of free space capacitance of different arbitrarily shaped conducting bodies based on the finite element method with triangular subsection modeling. Evaluation o...This paper presents a numerical analysis for computation of free space capacitance of different arbitrarily shaped conducting bodies based on the finite element method with triangular subsection modeling. Evaluation of capacitance of different arbitrary shapes is important for the electrostatic analysis. Capacitance computation is an important step in the prediction of electrostatic discharge which causes electromagnetic interference. We specifically illustrated capacitance computation of electrostatic models like unit cube, rectangular plate, triangular plate, T-shaped plate, sphere and two touching spheres. Numerical data on the capacitance of conducting objects are presented. The results are compared with other available results in the literature. We used the COMSOL Multiphysics software for the simulation. The models are designed in three-dimensional form using electrostatic environment and can be applied to any spacecraft circuit modeling design. The findings of this study show that the finite element method is a more accurate method and can be applied to any circuit modeling design.展开更多
基金Supported by the National Natural Science Foundation of China （50974095, 41174109, 61104148）, and the National Science and Technology Mai or Projects （2011ZX05020-006）.
文摘This paper presents a novel capacitance probe,i.e.,parallel-wire capacitance probe(PWCP),for two-phase flow measurement.Using finite element method(FEM),the sensitivity field of the PWCP is investigated and the optimum sensor geometry is determiend in term of the characterisitc parameters.Then,the response of PWCP for the oil-water stratified flow is calculated,and it is found the PWCP has better linearity and sensitivity to the variation of water-layer thickness,and is almost independant of the angle between the oil-water interface and the sensor electrode.Finally,the static experiment for oil-water stratified flow is carried out and the calibration method of liquid holdup is presented.
文摘Based on the study of the characteristics of the cloud, firstly the interference mechanism of the capacitance proximity fuze passing through the cloud has been studied. Analysis shows that the medium property of the cloud only, has little effect on the capacitance proximity fuze. Secondly, the adherence interference of the cloud to capacitance proximity fuze has been studied for the first time in this paper. Then finite element analysis (FEA) method has been used to simulate the adherence interference of the cloud. Simulation result shows that the cloud adherence effect interferes the output of the capacitance fuze greatly. At last, experiments have been made for the study of the cloud interference.
文摘Over the years, there has been increased research interest in the application of Nitinol as an actuator, due to its shape memory behaviour, simplicity, high power-to-weight ratio, compactness, and extreme high fatigue resistance to cyclic motion, and noiseless operation. Nitinol has found application in tactile displays which reproduce tactile parameters such as texture and shape, depending on the application. This paper presents the effects of thermal interference between adjacent Nitinol spring actuators in a tactile display. The tactile display is made of a 3 by 3 pin array whose spatial resolution was varied from 4 mm to 6 mm in steps of 1 mm while a current of 1.5 A was used to actuate 8 of the springs, and the centre spring was left unactivated to observe the thermal effects on it due to the heat gradient formed. A Finite Element (FE) model was developed using COMSOL Multiphysics and the results were further verified through experimentation. In both cases, there was visible thermal interference between actuators. The increase in spatial resolution saw a decrease in thermal interference by 12.7%. Using a fan to introduce forced convection, reduced the thermal interference in the simulation by 20% and during experimentation by 11%. The results of this research indicate a spatial resolution of 6 mm reduced the thermal inference to a negligible rate. However, thermal interference could not be eliminated with these two methods.
基金the Ministerial Level Advanced Research Foundation (5140C9384029389C475)
文摘A numerical calculation method based on the finite element analysis of dynamic characteristics of artillery-fuze system is discussed in detail. Pretension element is used to mesh the couple structure between artillery and fuze to analyze the change of dynamic characteristics of artillery-fuze system when pre-tightening force varies between artillery and fuze. Numerical calculation of the finite element analysis and actual hammering test of a artillery-fuze system are carried out with the same input to verify the accuracy of numerical calculation. The results show that the finite element model of artillery-fuze system is credible and the calculation accuracy is perfect.
文摘Water Tree is a corrosion phenomenon in cross-link polyethylene (XLPE) insulation. It is commonly found in underground cables. Water tree induced fault is difficult to detect due to its high impedance and difficult to model due to its random nature. In recent years, underground cables have become more popular in the power industry. They are resistant to environmental damage and has reduced space requirement. They are suitable to areas with high environment hazard or heavily populated areas where space is a constraining factor. As a result, studying and modeling the structure and effect of water tree become increasingly important. Since majority of the fault inducing water trees are vented trees which originated from the surface of the cable insulation, the mathematical model focuses on this particular type of water tree. To reduce the complexity of the model, the shape of the water tree afflicted region of the insulation is assumed to be ellipsoidal and the permittivity of the region is assumed to be linearly changing. Finite element analysis is used to analyze the water tree affected region. The resultant capacitance is calculated and compared with a physical model from Comsol. The result obtained using the proposed mathematical model and the result obtained using physical simulation through Comsol package agrees with each other. Hence, this method can be used to analyze the effect of water tree fault in large power systems.
文摘This paper presents a numerical analysis for computation of free space capacitance of different arbitrarily shaped conducting bodies based on the finite element method with triangular subsection modeling. Evaluation of capacitance of different arbitrary shapes is important for the electrostatic analysis. Capacitance computation is an important step in the prediction of electrostatic discharge which causes electromagnetic interference. We specifically illustrated capacitance computation of electrostatic models like unit cube, rectangular plate, triangular plate, T-shaped plate, sphere and two touching spheres. Numerical data on the capacitance of conducting objects are presented. The results are compared with other available results in the literature. We used the COMSOL Multiphysics software for the simulation. The models are designed in three-dimensional form using electrostatic environment and can be applied to any spacecraft circuit modeling design. The findings of this study show that the finite element method is a more accurate method and can be applied to any circuit modeling design.
