A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrit...A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrite tip, interface curvature and anisotropy of the surface energy were extended to 3-D system in the model. Therefore, the model was able to describe the morphology evolution of 3-D dendrites. Then, the model was applied to simulate the mechanism of spacing adjustment for 3-D columnar dendrite growth, and the competitive growth of columnar dendrites with different preferred growth orientations under constant temperature gradient and pulling velocity. Directional solidification experiments of NH4Cl-H2O transparent alloy were performed. It was found that the simulated results compared well with the experimental results. Therefore, the model was reliable for simulating the 3-D dendrite growth of cubic system alloys.展开更多
An analytical approach to evaluate the performance of the 3G/ad hoc integrated network is presented. A channel model capturing both path loss and shadowing is applied to the analysis so as to characterize power fallof...An analytical approach to evaluate the performance of the 3G/ad hoc integrated network is presented. A channel model capturing both path loss and shadowing is applied to the analysis so as to characterize power falloff vs. distance. The 3G/ad hoc integrated network scenario model is introduced briefly. Based on this model, several performances of the 3G/ ad hoc integrated network in terms of outage probability, call dropping probability and new call blocking probability are evaluated. The corresponding performance formulae are deduced in accordance with the analytical models. Meanwhile, the formula of the 3G/ad hoc integrated network capacity is deduced on the basis of the formula of the outage probability. It is observed from extensive simulation and numerical analysis that the 3G/ad hoc integrated network remarkably outperforms the 3G network with regards to the network performance. This derived evaluation approach can be applied into planning and optimization of the 3G/ad hoc network.展开更多
Constructing the 3D virtual scene of a coal mine is the objective requirement for modernizing and processing information on coal mining production. It is also the key technology to establish a ＂digital mine＂. By exp...Constructing the 3D virtual scene of a coal mine is the objective requirement for modernizing and processing information on coal mining production. It is also the key technology to establish a ＂digital mine＂. By exploring current worldwide research, software and hardware tools and application demands, combined with the case study site （the Dazhuang mine of Pingdingshan coal group）, an approach for 3D geo-visualization of a mine surface plant and mine roadway is deeply discussed. In this study, the rapid modeling method for a large range virtual scene based on Arc/Info and SiteBuilder3D is studied, and automatic generation of a 3D scene from a 2D scene is realized. Such an automatic method which can convert mine roadway systems from 2D to 3D is realized for the Dazhuang mine. Some relevant application questions are studied, including attribute query, coordinate query, distance measure, collision detection and the dynamic interaction between 2D and 3D virtual scenes in the virtual scene of a mine surface plant and mine roadway. A prototype system is designed and developed.展开更多
A pinion-type electric power steering (EPS) equipped on a sedan is reached in this paper. A three-freedom dynamic model of this system is created. The variables affecting assist character is analyzed. The formulas of ...A pinion-type electric power steering (EPS) equipped on a sedan is reached in this paper. A three-freedom dynamic model of this system is created. The variables affecting assist character is analyzed. The formulas of simpled steering resistance force and the relationship between assist gain and vehicle speed are presented for the first time. Assist character is found based on the parameters of a sedan at last. This assist character is fit for the control rule of the EPS system through analyzing this character. The assist character figure offers reference for system design and control. Furthermore, this research method has generality for assist character of different kinds of vehicles.展开更多
A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF plan...A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF planar platform was established based on slippery course and bearing, and dSPACE real-time control system was used to perform the platform's motion control experiment on robot. Based on the kinematic equation and mechanical balance equation of moving platform, the stiffness of the robot system was analyzed and the calibration scheme of the system considering wire tension was put forward. Position servo control experiments were carried out, position servo tracking precision was analyzed, and real-time wire tension was detected. The results show that the moving error of the moving platform tracking is small (the maximum difference is about 3%), and the rotation error is large (the maximum difference is about 12%). The wire tension has wave properties (the wire tension fluctuation is about 10 N).展开更多
Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion...Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion has been analyzed. Due to this type of injection velocity, the flow becomes three-dimensional. Analytical expressions for the velocity, temperature, skin friction and rate of heat transfer were obtained. The important characteristics of the problem, namely the skin friction and the rate of heat transfer are discussed in detail with the help of graphs.展开更多
Objective:The aim of this study was to evaluate the efficacy of three-phase contrast material-enhanced MRI in assessing no-surgical treatment response in peripheral bronchogenic carcinoma preliminarily.Methods:Twenty-...Objective:The aim of this study was to evaluate the efficacy of three-phase contrast material-enhanced MRI in assessing no-surgical treatment response in peripheral bronchogenic carcinoma preliminarily.Methods:Twenty-two patients with bronchogenic carcinoma after no-surgical treatment underwent three-phase contrast material-enhanced MRI.Three scans were obtained at 25 s,120 s and 180 s respectively after nonionic contrast material was administrated via the antecubital vein at a rate of 2 mL/s by using an autoinjector.Precontrast and postcontrast signal intensity on every scan was recorded.Peak Height(PH) and Maximum Enhancement(Emax) were calculated.Enhancement pattern was evaluated on the images obtained at 120 s and 180 s after injection of contrast medium.Results:Precontrast signal intensity,postcontrast signal intensity at 120 s and 180 s were 478 ± 108,926 ± 209 and 1050 ± 252.PH(571 ± 225) and Emax(119 ± 49) of bronchogenic carcinoma after no-surgical treatment were significantly lower than those of bronchogenic carcinoma without any therapy(mean PH 655,mean Emax 150)(t = 2.178,P = 0.005 < 0.05,t = 4.196,P = 0.001 < 0.05).Six cases among 22 appeared homogeneous enhancement at 180 s.At 120 s,there were 4 cases with inhomogeneous enhancement,1 case with homogeneous enhancement,1 case with peripheral enhancement among the 6 cases.Conclusion:Bronchogenic carcinoma after no-surgical treatment shows a gradual increase to the PH after administration of contrast material.Three-phase contrast material-enhanced MRI can reflect the blood supply of bronchogenic carcinoma and might be effective approach for evaluation of no-surgical treatment response in bronchogenic carcinoma.展开更多
A numerical investigation was carried out on the effect of carbon nanotube(CNT)-water-nanofluid-filled Trombe wall on heat transfer and fluid flow inside a 3 D typical room.Time depending governing equations are consi...A numerical investigation was carried out on the effect of carbon nanotube(CNT)-water-nanofluid-filled Trombe wall on heat transfer and fluid flow inside a 3 D typical room.Time depending governing equations are considered with applying hot temperature at the left surface(collector) of the Trombe wall.The left wall(glazing) of the room and a square part(window) at the right wall are considered at cold temperature.The effects of Rayleigh number and the nanofluid volume fractions and the Trombe wall height on the temperature field,flow structure and heat transfer rate,are studied.The results show that the addition of nanoparticles and the increase of the Trombe wall height,enhance the heat transfer considerably and affect the flow structure and the temperature field.展开更多
基金Projects (2005CB724105, 2011CB706801) supported by the National Basic Research Program of ChinaProjects (10477010, 51171089) supported by the National Natural Science Foundation of China+1 种基金Project (2007AA04Z141) supported by the High-Tech Research and Development Program of ChinaProjects (2009ZX04006-041-04, 2011ZX04014-052) supported by the Important National Science & Technology Specific
文摘A three-dimensional （3-D） modified cellular automaton （MCA） method was developed for simulating the dendrite morphology of cubic system alloys. Two-dimensional （2-D） equations of growth velocities of the dendrite tip, interface curvature and anisotropy of the surface energy were extended to 3-D system in the model. Therefore, the model was able to describe the morphology evolution of 3-D dendrites. Then, the model was applied to simulate the mechanism of spacing adjustment for 3-D columnar dendrite growth, and the competitive growth of columnar dendrites with different preferred growth orientations under constant temperature gradient and pulling velocity. Directional solidification experiments of NH4Cl-H2O transparent alloy were performed. It was found that the simulated results compared well with the experimental results. Therefore, the model was reliable for simulating the 3-D dendrite growth of cubic system alloys.
基金The National Natural Science Foundation of China(No.60872004)the Research Fund of National Mobile Communications Research Laboratory of Southeast University(No.2010A08)the Fundamental Research Funds for the Central Universities(No.2009B21814)
文摘An analytical approach to evaluate the performance of the 3G/ad hoc integrated network is presented. A channel model capturing both path loss and shadowing is applied to the analysis so as to characterize power falloff vs. distance. The 3G/ad hoc integrated network scenario model is introduced briefly. Based on this model, several performances of the 3G/ ad hoc integrated network in terms of outage probability, call dropping probability and new call blocking probability are evaluated. The corresponding performance formulae are deduced in accordance with the analytical models. Meanwhile, the formula of the 3G/ad hoc integrated network capacity is deduced on the basis of the formula of the outage probability. It is observed from extensive simulation and numerical analysis that the 3G/ad hoc integrated network remarkably outperforms the 3G network with regards to the network performance. This derived evaluation approach can be applied into planning and optimization of the 3G/ad hoc network.
文摘Constructing the 3D virtual scene of a coal mine is the objective requirement for modernizing and processing information on coal mining production. It is also the key technology to establish a ＂digital mine＂. By exploring current worldwide research, software and hardware tools and application demands, combined with the case study site （the Dazhuang mine of Pingdingshan coal group）, an approach for 3D geo-visualization of a mine surface plant and mine roadway is deeply discussed. In this study, the rapid modeling method for a large range virtual scene based on Arc/Info and SiteBuilder3D is studied, and automatic generation of a 3D scene from a 2D scene is realized. Such an automatic method which can convert mine roadway systems from 2D to 3D is realized for the Dazhuang mine. Some relevant application questions are studied, including attribute query, coordinate query, distance measure, collision detection and the dynamic interaction between 2D and 3D virtual scenes in the virtual scene of a mine surface plant and mine roadway. A prototype system is designed and developed.
文摘A pinion-type electric power steering (EPS) equipped on a sedan is reached in this paper. A three-freedom dynamic model of this system is created. The variables affecting assist character is analyzed. The formulas of simpled steering resistance force and the relationship between assist gain and vehicle speed are presented for the first time. Assist character is found based on the parameters of a sedan at last. This assist character is fit for the control rule of the EPS system through analyzing this character. The assist character figure offers reference for system design and control. Furthermore, this research method has generality for assist character of different kinds of vehicles.
基金Project(20102304120007) supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject(QC2010009)supported by the Natural Science Foundation of Heilongjiang Province, China+1 种基金Projects(20110491030, LBH-Z10219) supported by China Postdoctoral Science FoundationProject(HEUCF120706) supported by the Fundamental Research Funds for the Central Universities of China
文摘A three-DOF (degree of freedom) planar robot completely restrained and positioned parallel pulled by four wires was studied. The wire driving properties were analyzed through experiments. The restrained three-DOF planar platform was established based on slippery course and bearing, and dSPACE real-time control system was used to perform the platform's motion control experiment on robot. Based on the kinematic equation and mechanical balance equation of moving platform, the stiffness of the robot system was analyzed and the calibration scheme of the system considering wire tension was put forward. Position servo control experiments were carried out, position servo tracking precision was analyzed, and real-time wire tension was detected. The results show that the moving error of the moving platform tracking is small (the maximum difference is about 3%), and the rotation error is large (the maximum difference is about 12%). The wire tension has wave properties (the wire tension fluctuation is about 10 N).
文摘Free convection flow between two vertical parallel plates with transverse sinusoidal injection of the fluid at the stationary plate and its corresponding removal by constant suction through the plate in uniform motion has been analyzed. Due to this type of injection velocity, the flow becomes three-dimensional. Analytical expressions for the velocity, temperature, skin friction and rate of heat transfer were obtained. The important characteristics of the problem, namely the skin friction and the rate of heat transfer are discussed in detail with the help of graphs.
文摘Objective:The aim of this study was to evaluate the efficacy of three-phase contrast material-enhanced MRI in assessing no-surgical treatment response in peripheral bronchogenic carcinoma preliminarily.Methods:Twenty-two patients with bronchogenic carcinoma after no-surgical treatment underwent three-phase contrast material-enhanced MRI.Three scans were obtained at 25 s,120 s and 180 s respectively after nonionic contrast material was administrated via the antecubital vein at a rate of 2 mL/s by using an autoinjector.Precontrast and postcontrast signal intensity on every scan was recorded.Peak Height(PH) and Maximum Enhancement(Emax) were calculated.Enhancement pattern was evaluated on the images obtained at 120 s and 180 s after injection of contrast medium.Results:Precontrast signal intensity,postcontrast signal intensity at 120 s and 180 s were 478 ± 108,926 ± 209 and 1050 ± 252.PH(571 ± 225) and Emax(119 ± 49) of bronchogenic carcinoma after no-surgical treatment were significantly lower than those of bronchogenic carcinoma without any therapy(mean PH 655,mean Emax 150)(t = 2.178,P = 0.005 < 0.05,t = 4.196,P = 0.001 < 0.05).Six cases among 22 appeared homogeneous enhancement at 180 s.At 120 s,there were 4 cases with inhomogeneous enhancement,1 case with homogeneous enhancement,1 case with peripheral enhancement among the 6 cases.Conclusion:Bronchogenic carcinoma after no-surgical treatment shows a gradual increase to the PH after administration of contrast material.Three-phase contrast material-enhanced MRI can reflect the blood supply of bronchogenic carcinoma and might be effective approach for evaluation of no-surgical treatment response in bronchogenic carcinoma.
基金funded by Scientific Research Deanship at University of Ha ’ il-Saudi Arabia through project number BA-2019。
文摘A numerical investigation was carried out on the effect of carbon nanotube(CNT)-water-nanofluid-filled Trombe wall on heat transfer and fluid flow inside a 3 D typical room.Time depending governing equations are considered with applying hot temperature at the left surface(collector) of the Trombe wall.The left wall(glazing) of the room and a square part(window) at the right wall are considered at cold temperature.The effects of Rayleigh number and the nanofluid volume fractions and the Trombe wall height on the temperature field,flow structure and heat transfer rate,are studied.The results show that the addition of nanoparticles and the increase of the Trombe wall height,enhance the heat transfer considerably and affect the flow structure and the temperature field.
