Machining-features of the workplace are described by using of the object-oriented （O-O） technology. Geometrical machining-features are recognized in the given cut region by using the maximum membership priciple abou...Machining-features of the workplace are described by using of the object-oriented （O-O） technology. Geometrical machining-features are recognized in the given cut region by using the maximum membership priciple about the fuzzy set. Depending on the IF-THEN rule and the fuzzy matching method, the rough information of the machining-process for high-speed milling （HSM） is extracted based on the database of machining-process for HSM. The optimization model of machining-process scheme is established to obtain shorter cut time, lower cost or higher surface quality. It is helpful to form successful cases for HSM. NC programming for HSM is realized according to optimized machining-process data from HSM cases selected by the optimization model and the extracted information of machining-process.展开更多
This paper investigates the cross-correlation characteristics of large-scale parameters(LSPs) and small-scale fading(SSF) for high-speed railway(HSR) multilink propagation scenarios, based on realistic measurements co...This paper investigates the cross-correlation characteristics of large-scale parameters(LSPs) and small-scale fading(SSF) for high-speed railway(HSR) multilink propagation scenarios, based on realistic measurements conducted on Beijing to Tianjin HSR line in China. A long-term evolution-based channel sounding system is utilized in the measurements to obtain the channel data. By applying a proposed time-delay based dynamic partition method, multi-link channel impulse responses are extracted from the raw channel data. Then, the statistical results of LSPs, including shadow fading, K-factor, and root-mean-square delay spread are derived and the cross-correlation coefficients of these LPSs are calculated. Moreover, the SSF spatial correlation and cross-correlation of SSF are analyzed. These results can be used to exploit multi-link channel model and to optimize the next-generation HSR communication system.展开更多
With consideration of railway operation in China and accompanying acci-dents and breakdowns, high-speed railway in China, Japan, France and Germany was analyzed, and the suggestions in intensifying high-speed railway ...With consideration of railway operation in China and accompanying acci-dents and breakdowns, high-speed railway in China, Japan, France and Germany was analyzed, and the suggestions in intensifying high-speed railway safety and disaster prevention were proposed, providing references for high-speed railway safety management and operation.展开更多
Performing surveys on a single section of a road is quite different from that on a road network. In the first case, the need for performance characteristics of the pavement may be of service to rehabilitation. Surveyi...Performing surveys on a single section of a road is quite different from that on a road network. In the first case, the need for performance characteristics of the pavement may be of service to rehabilitation. Surveying a road network, instead, aims to establish service levels, identify deficiencies and priorities and define budgets for maintenance. This challenge needs a methodological approach in order to widen the action plan and optimize the cost-benefit analysis of each asset through the use of preventive maintenance policies. High-speed monitoring systems on the market were specialized towards the necessity of measuring specific performance of the pavement or mapping land （data inventory）. The technological development of instrumentations such as inertial systems and synchronizers has enabled the integration of different devices and the achievement of the best correlation of data. This is the case of the LARAN （laser road analyzer）, whose helpfulness will be presented within a case study in which geometrical data and surface characteristic information-cracks, texture, profiles-were obtained through a unique survey. The cross-analysis resulted efficient for safety purposes and also for the identification of “black points” corresponding to boundary operative conditions of the road with respect to technical standards and recommendations.展开更多
The authors analyzed the engineering geological characteristics of the slope of the study area (K75+840-K76+340). Two typical cross-sections have been chosen to analyze the failure modes after the excavation of the hi...The authors analyzed the engineering geological characteristics of the slope of the study area (K75+840-K76+340). Two typical cross-sections have been chosen to analyze the failure modes after the excavation of the highway. Different types of the failure modes have been calculated and analyzed. The results show that some dealing methods have been advised to ensure the stability of the slopes.展开更多
The high angle of attack characteristics play an important role in the aerodynamic performances of the hypersonic space vehicle. The three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations and the two-equat...The high angle of attack characteristics play an important role in the aerodynamic performances of the hypersonic space vehicle. The three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations and the two-equation RNG k-? turbulence model have been employed to investigate the influence of the high angle of attack on the lift-to-drag ratio and the flow field characteristics of the hypersonic space vehicle, and the contributions of each component to the aerodynamic forces of the vehicle have been discussed as well. At the same time, in order to validate the numerical method, the predicted results have been compared with the available experimental data of a hypersonic slender vehicle, and the grid independency has been analyzed. The obtained results show that the predicted lift-to-drag ratio and pitching moment coefficient show very good agreement with the experimental data in the open literature, and the grid system makes only a slight difference to the numerical results. There exists an optimal angle of attack for the aerodynamic performance of the hypersonic space vehicle, and its value is 20°. When the angle of attack is 20°, the high pressure does not leak from around the leading edge to the upper surface. With the further increasing of the angle of attack, the high pressure spreads from the wing tips to the central area of the vehicle, and overflows from the leading edge again. Further, the head plays an important role in the drag performance of the vehicle, and the lift percentage of the flaperon is larger than that of the rudderevator. This illustrates that the optimization of the flaperon configuration is a great work for the improvement of the aerodynamic performance of the hypersonic space vehicle, especially for a high lift-to-drag ratio.展开更多
With the development of high-speed train,it is considerably concerned about the aerodynamic characteristics and operation safety issues of the high-speed train under extreme weather conditions.The aerodynamic performa...With the development of high-speed train,it is considerably concerned about the aerodynamic characteristics and operation safety issues of the high-speed train under extreme weather conditions.The aerodynamic performance of a high-speed train under heavy rain and strong crosswind conditions are modeled using the Eulerian two-phase model in this paper.The impact of heavy rainfall on train aerodynamics is investigated,coupling heavy rain and a strong crosswind.Results show that the lift force,side force,and rolling moment of the train increase significantly with wind speed up to 40 m/s under a rainfall rate of 60 mm/h.when considering the rain and wind conditions.The increases of the lift force,side force,and rolling moment may deteriorate the train operating safety and cause the train to overturn.A quasi-static stability analysis based on the moment balance is used to determine the limit safety speed of a train under different rain and wind levels.The results can provide a frame of reference for the train safe operation under strong rain and crosswind conditions.展开更多
Clonal selection feature selection algorithm （CSFS） based on clonal selection algorithm （CSA）, a new computational intelligence approach, has been proposed to perform the task of dimensionality reduction in high-d...Clonal selection feature selection algorithm （CSFS） based on clonal selection algorithm （CSA）, a new computational intelligence approach, has been proposed to perform the task of dimensionality reduction in high-dimensional images, and has better performance than traditional feature selection algorithms with more computational costs. In this paper, a fast clonal selection feature selection algorithm （FCSFS） for hyperspectral imagery is proposed to improve the convergence rate by using Cauchy mutation instead of non-uniform mutation as the primary immune operator. Two experiments are performed to evaluate the performance of the proposed algorithm in comparison with CSFS using hyperspectral remote sensing imagery acquired by the pushbroom hyperspectral imager （PHI） and the airborne visible/infrared imaging spectrometer （AVlRIS）, respectively. Experimental results demonstrate that the FCSFS converges faster than CSFS, hence providing an effective new option for dimensionality reduction of hyperspectral remote sensing imagery.展开更多
文摘Machining-features of the workplace are described by using of the object-oriented （O-O） technology. Geometrical machining-features are recognized in the given cut region by using the maximum membership priciple about the fuzzy set. Depending on the IF-THEN rule and the fuzzy matching method, the rough information of the machining-process for high-speed milling （HSM） is extracted based on the database of machining-process for HSM. The optimization model of machining-process scheme is established to obtain shorter cut time, lower cost or higher surface quality. It is helpful to form successful cases for HSM. NC programming for HSM is realized according to optimized machining-process data from HSM cases selected by the optimization model and the extracted information of machining-process.
基金supported by the Beijing Municipal Natural Science Foundation under Grant 4174102the National Natural Science Foundation of China under Grant 61701017+1 种基金the Open Research Fund through the National Mobile Communications Research Laboratory, Southeast University, under Grant 2018D11the Fundamental Research Funds for the Central Universities under Grant 2018JBM003
文摘This paper investigates the cross-correlation characteristics of large-scale parameters(LSPs) and small-scale fading(SSF) for high-speed railway(HSR) multilink propagation scenarios, based on realistic measurements conducted on Beijing to Tianjin HSR line in China. A long-term evolution-based channel sounding system is utilized in the measurements to obtain the channel data. By applying a proposed time-delay based dynamic partition method, multi-link channel impulse responses are extracted from the raw channel data. Then, the statistical results of LSPs, including shadow fading, K-factor, and root-mean-square delay spread are derived and the cross-correlation coefficients of these LPSs are calculated. Moreover, the SSF spatial correlation and cross-correlation of SSF are analyzed. These results can be used to exploit multi-link channel model and to optimize the next-generation HSR communication system.
基金Supported by Special Fund for Weather-scientific Research in the Public Interest(GYHY201306058)~~
文摘With consideration of railway operation in China and accompanying acci-dents and breakdowns, high-speed railway in China, Japan, France and Germany was analyzed, and the suggestions in intensifying high-speed railway safety and disaster prevention were proposed, providing references for high-speed railway safety management and operation.
文摘Performing surveys on a single section of a road is quite different from that on a road network. In the first case, the need for performance characteristics of the pavement may be of service to rehabilitation. Surveying a road network, instead, aims to establish service levels, identify deficiencies and priorities and define budgets for maintenance. This challenge needs a methodological approach in order to widen the action plan and optimize the cost-benefit analysis of each asset through the use of preventive maintenance policies. High-speed monitoring systems on the market were specialized towards the necessity of measuring specific performance of the pavement or mapping land （data inventory）. The technological development of instrumentations such as inertial systems and synchronizers has enabled the integration of different devices and the achievement of the best correlation of data. This is the case of the LARAN （laser road analyzer）, whose helpfulness will be presented within a case study in which geometrical data and surface characteristic information-cracks, texture, profiles-were obtained through a unique survey. The cross-analysis resulted efficient for safety purposes and also for the identification of “black points” corresponding to boundary operative conditions of the road with respect to technical standards and recommendations.
文摘The authors analyzed the engineering geological characteristics of the slope of the study area (K75+840-K76+340). Two typical cross-sections have been chosen to analyze the failure modes after the excavation of the highway. Different types of the failure modes have been calculated and analyzed. The results show that some dealing methods have been advised to ensure the stability of the slopes.
基金supported by the Science Foundation of the National University of Defense Technology (Grant No. JC11-01-02)National Natural Science Foundation of China (Grant Nos. 90816027, 61004094)
文摘The high angle of attack characteristics play an important role in the aerodynamic performances of the hypersonic space vehicle. The three-dimensional Reynolds Averaged Navier-Stokes (RANS) equations and the two-equation RNG k-? turbulence model have been employed to investigate the influence of the high angle of attack on the lift-to-drag ratio and the flow field characteristics of the hypersonic space vehicle, and the contributions of each component to the aerodynamic forces of the vehicle have been discussed as well. At the same time, in order to validate the numerical method, the predicted results have been compared with the available experimental data of a hypersonic slender vehicle, and the grid independency has been analyzed. The obtained results show that the predicted lift-to-drag ratio and pitching moment coefficient show very good agreement with the experimental data in the open literature, and the grid system makes only a slight difference to the numerical results. There exists an optimal angle of attack for the aerodynamic performance of the hypersonic space vehicle, and its value is 20°. When the angle of attack is 20°, the high pressure does not leak from around the leading edge to the upper surface. With the further increasing of the angle of attack, the high pressure spreads from the wing tips to the central area of the vehicle, and overflows from the leading edge again. Further, the head plays an important role in the drag performance of the vehicle, and the lift percentage of the flaperon is larger than that of the rudderevator. This illustrates that the optimization of the flaperon configuration is a great work for the improvement of the aerodynamic performance of the hypersonic space vehicle, especially for a high lift-to-drag ratio.
基金Project(No.2009BAG12A01-C03) supported by the National Key Technology R&D Program of China
文摘With the development of high-speed train,it is considerably concerned about the aerodynamic characteristics and operation safety issues of the high-speed train under extreme weather conditions.The aerodynamic performance of a high-speed train under heavy rain and strong crosswind conditions are modeled using the Eulerian two-phase model in this paper.The impact of heavy rainfall on train aerodynamics is investigated,coupling heavy rain and a strong crosswind.Results show that the lift force,side force,and rolling moment of the train increase significantly with wind speed up to 40 m/s under a rainfall rate of 60 mm/h.when considering the rain and wind conditions.The increases of the lift force,side force,and rolling moment may deteriorate the train operating safety and cause the train to overturn.A quasi-static stability analysis based on the moment balance is used to determine the limit safety speed of a train under different rain and wind levels.The results can provide a frame of reference for the train safe operation under strong rain and crosswind conditions.
基金Supported by the Major State Basic Research Development Program (973 Program) of China (No. 2009CB723905)the National High Technology Research and Development Program (863 Program) of China (Nos.2009AA12Z114, 2007AA12Z148, 2007AA12Z181)+2 种基金the National Natural Sci-ence Foundation of China(Nos. 40771139,40523005, 40721001)the Research Fund for the Doctoral Program of Higher Education of China(No.200804861058)the Foundation of National Laboratory of Pattern Recognition
文摘Clonal selection feature selection algorithm （CSFS） based on clonal selection algorithm （CSA）, a new computational intelligence approach, has been proposed to perform the task of dimensionality reduction in high-dimensional images, and has better performance than traditional feature selection algorithms with more computational costs. In this paper, a fast clonal selection feature selection algorithm （FCSFS） for hyperspectral imagery is proposed to improve the convergence rate by using Cauchy mutation instead of non-uniform mutation as the primary immune operator. Two experiments are performed to evaluate the performance of the proposed algorithm in comparison with CSFS using hyperspectral remote sensing imagery acquired by the pushbroom hyperspectral imager （PHI） and the airborne visible/infrared imaging spectrometer （AVlRIS）, respectively. Experimental results demonstrate that the FCSFS converges faster than CSFS, hence providing an effective new option for dimensionality reduction of hyperspectral remote sensing imagery.
