The major problems existing in the derailment studies are summarized according to analysis of the research status about train derailment in China and other countries of the world.(1) The current criteria for preventin...The major problems existing in the derailment studies are summarized according to analysis of the research status about train derailment in China and other countries of the world.(1) The current criteria for preventing derailment cannot assure that derailment will not occur.(2) It is not clear for train derailment mechanism.(3) There exist three fundamental problems in the calculation of train derailment as follows: ① The connecting condition of displacement between wheel and rail cannot be satisfied in establishment and solution of vibration equation group of train-track(bridge) time-variant system.② Only the lateral track irregularity is regarded as the exciting source of lateral vibration of train-track(bridge) time-variant system.The true exciting source,i.e.the wheel and rail contact status is neglected.③ The random lateral vibration of train-track (bridge) time-variant system is analyzed according to the random track irregularity and analysis theory of random vibration of time-invariant system.But the maximum responses of lateral vibration of train-track(bridge) time-variant system cannot be calculated,and furthermore train deraiment cannot be forecasted.The thinking and methods for solving these problems are also introduced.The train derailment mechanism,which is the result of losing stability in lateral vibration status of train-track(bridge) time-variant system,is proposed for the first time by analysis of characteristics of self-excitation of train vibration and losing stability in self-excitation vibration status of train derailment.So the key to analyzing train derailment is to analyze the stability of lateral vibration of train-track(bridge) time-variant system.The following conclusions are made by summarizing the existing analysis theory of stability of static and dynamic system.(1) Because of the characteristics of time-variant and self-excitation of train-track(bridge) system,the stability of lateral vibration of the system cannot directly be analyzed by the existing analysis theory of stability of static and dynamic system.(2) The common point of the existing analysis theory of stability of static and dynamic system is that the stability of static and dynamic system is evaluated by the comparison between the resisting force increment(or the increment of the work done by the resisting force) and the load increment(or the increment of the input energy) after the system status produces excursion.(3) Because of the characteristic of selfexcitation of lateral vibration of train-track(bridge) system,both of the load and resisting force of lateral vibration of the system is not clear.So the stability of lateral vibration status of the system must be evaluated by the increment criterion of the work done by the resisting force and the input energy,and not by the increment criterion of resisting force and load.The condition for the stability of the lateral vibration of train-track(bridge) system and no derailment of the train is put forward according to the concept that the Tacoma cable bridge will lose stability in self-excitation vibration status under the action of wind when the input energy accumulated in the course of vibration reaches the work done by the limited resisting force.That is,the work done by the limited resisting force is larger than the maximum input energy.A set of theory for random energy analysis of train derailment is proposed.And the main contents are as below.(1) Taking into account the connecting condition of wheel-rail displacement and the influence of the clearance between wheel flange and gauge line,the matrix equation of the spatial vibration of train-track (bridge) system is established to calculate the whole course of train derailment.(2) The geometric criterion of train derailment is established.(3) The method for calculating the whole course of train derailment is put forward.(4) The vibration responses of the whole course of train derailment are calculated.The relationship curve between the work done by the limited resisting force of the lateral vibration of the system and train speed is gained.And the increment expression of the work done by the limited resisting force of the lateral vibration of the system is also obtained.(5) The method for calculating the increment of the maximum input energy of the lateral vibration of the system is put forward.(6) The energy increment criteria for determining the stability status of the lateral vibration of the system and train derailment is established.The bogie frame hunting wave of a freight train on Beijing-Tonghua railway line is measured and the relationship curve between the standard deviation of the bogie frame hunting wave of the empty car and train speed is gained.The bogie frame hunting wave of a high-speed train on Qinhuangdao-Shenyang railway line for passenger traffic is also measured and the relationship curve between the standard deviation of the bogie frame hunting wave of the high speed train and train speed is obtained.A set of software TDAS v1.0 for analyzing train derailment with property right is independently developed based on the theory of random energy analysis for train derailment.According to the software,a grave derailment accident of number 33117 freight train on Changchun-tumen railway line is analyzed.Safety analyses are made of trains running on six bridges such as Nanjing Yangtz river bridge etc.with their lateral vibration amplitudes exceeding specifications.And derailment controlling of high speed trains running on supper major bridges such as Tianxinzhou combined highway and railway bridge,Hujiawan bridge and Hengyang-Xiangjiang bridge etc.on Wuhan-guangzhou railway line for passenger traffic is analyzed.All of the analysis results mentioned above have been applied by the corresponding railway departments.The preventive measures against derailment and methods for stipulating preventive standard against derailment are proposed.A derailment warning device is invented a national patent is also gained.To counter train derailment under normal condition of train operation,i.e.undefined derailment,the technical principle for a warning system against derailment is proposed.展开更多
An adaptive object tracking algorithm based on particle filtering and a modified Gradient Vector Flow (GVF) Snake is proposed for tracking moving and deforming objects. The original contours of objects are obtained by...An adaptive object tracking algorithm based on particle filtering and a modified Gradient Vector Flow (GVF) Snake is proposed for tracking moving and deforming objects. The original contours of objects are obtained by using the background differencing method,and the true contours of objects can be converged by means of the powerful searching ability of a modified GVF-Snake. Finally,an Energetic Particle Filtering (EPF) algorithm is obtained by combining particle filtering and a modified GVF-Snake,and by using K-means and the EPF algorithm,multiple objects can be tracked. The proposed tracking tactic for partially occluded objects can effectively improve its anti-occlusion ability. Experiments show that this algorithm can obtain better tracking effect even though the tracked object is occluded.展开更多
文摘The major problems existing in the derailment studies are summarized according to analysis of the research status about train derailment in China and other countries of the world.(1) The current criteria for preventing derailment cannot assure that derailment will not occur.(2) It is not clear for train derailment mechanism.(3) There exist three fundamental problems in the calculation of train derailment as follows: ① The connecting condition of displacement between wheel and rail cannot be satisfied in establishment and solution of vibration equation group of train-track(bridge) time-variant system.② Only the lateral track irregularity is regarded as the exciting source of lateral vibration of train-track(bridge) time-variant system.The true exciting source,i.e.the wheel and rail contact status is neglected.③ The random lateral vibration of train-track (bridge) time-variant system is analyzed according to the random track irregularity and analysis theory of random vibration of time-invariant system.But the maximum responses of lateral vibration of train-track(bridge) time-variant system cannot be calculated,and furthermore train deraiment cannot be forecasted.The thinking and methods for solving these problems are also introduced.The train derailment mechanism,which is the result of losing stability in lateral vibration status of train-track(bridge) time-variant system,is proposed for the first time by analysis of characteristics of self-excitation of train vibration and losing stability in self-excitation vibration status of train derailment.So the key to analyzing train derailment is to analyze the stability of lateral vibration of train-track(bridge) time-variant system.The following conclusions are made by summarizing the existing analysis theory of stability of static and dynamic system.(1) Because of the characteristics of time-variant and self-excitation of train-track(bridge) system,the stability of lateral vibration of the system cannot directly be analyzed by the existing analysis theory of stability of static and dynamic system.(2) The common point of the existing analysis theory of stability of static and dynamic system is that the stability of static and dynamic system is evaluated by the comparison between the resisting force increment(or the increment of the work done by the resisting force) and the load increment(or the increment of the input energy) after the system status produces excursion.(3) Because of the characteristic of selfexcitation of lateral vibration of train-track(bridge) system,both of the load and resisting force of lateral vibration of the system is not clear.So the stability of lateral vibration status of the system must be evaluated by the increment criterion of the work done by the resisting force and the input energy,and not by the increment criterion of resisting force and load.The condition for the stability of the lateral vibration of train-track(bridge) system and no derailment of the train is put forward according to the concept that the Tacoma cable bridge will lose stability in self-excitation vibration status under the action of wind when the input energy accumulated in the course of vibration reaches the work done by the limited resisting force.That is,the work done by the limited resisting force is larger than the maximum input energy.A set of theory for random energy analysis of train derailment is proposed.And the main contents are as below.(1) Taking into account the connecting condition of wheel-rail displacement and the influence of the clearance between wheel flange and gauge line,the matrix equation of the spatial vibration of train-track (bridge) system is established to calculate the whole course of train derailment.(2) The geometric criterion of train derailment is established.(3) The method for calculating the whole course of train derailment is put forward.(4) The vibration responses of the whole course of train derailment are calculated.The relationship curve between the work done by the limited resisting force of the lateral vibration of the system and train speed is gained.And the increment expression of the work done by the limited resisting force of the lateral vibration of the system is also obtained.(5) The method for calculating the increment of the maximum input energy of the lateral vibration of the system is put forward.(6) The energy increment criteria for determining the stability status of the lateral vibration of the system and train derailment is established.The bogie frame hunting wave of a freight train on Beijing-Tonghua railway line is measured and the relationship curve between the standard deviation of the bogie frame hunting wave of the empty car and train speed is gained.The bogie frame hunting wave of a high-speed train on Qinhuangdao-Shenyang railway line for passenger traffic is also measured and the relationship curve between the standard deviation of the bogie frame hunting wave of the high speed train and train speed is obtained.A set of software TDAS v1.0 for analyzing train derailment with property right is independently developed based on the theory of random energy analysis for train derailment.According to the software,a grave derailment accident of number 33117 freight train on Changchun-tumen railway line is analyzed.Safety analyses are made of trains running on six bridges such as Nanjing Yangtz river bridge etc.with their lateral vibration amplitudes exceeding specifications.And derailment controlling of high speed trains running on supper major bridges such as Tianxinzhou combined highway and railway bridge,Hujiawan bridge and Hengyang-Xiangjiang bridge etc.on Wuhan-guangzhou railway line for passenger traffic is analyzed.All of the analysis results mentioned above have been applied by the corresponding railway departments.The preventive measures against derailment and methods for stipulating preventive standard against derailment are proposed.A derailment warning device is invented a national patent is also gained.To counter train derailment under normal condition of train operation,i.e.undefined derailment,the technical principle for a warning system against derailment is proposed.
基金Supported by the Significant Term of Science and Technology Research in Ministry of Education (No. 205060)Open Research Fund of National Mobile Communications Research Laboratory,Southeast University (N200911)+2 种基金Significant Basic Research of Jiangsu Province Colleges and Universities Natural Science Projects (07 KJA51006)Research Fund of Nanjing College of Traffic Vocational Technology (JY0903)Huawei Science and Technology Fund
文摘An adaptive object tracking algorithm based on particle filtering and a modified Gradient Vector Flow (GVF) Snake is proposed for tracking moving and deforming objects. The original contours of objects are obtained by using the background differencing method,and the true contours of objects can be converged by means of the powerful searching ability of a modified GVF-Snake. Finally,an Energetic Particle Filtering (EPF) algorithm is obtained by combining particle filtering and a modified GVF-Snake,and by using K-means and the EPF algorithm,multiple objects can be tracked. The proposed tracking tactic for partially occluded objects can effectively improve its anti-occlusion ability. Experiments show that this algorithm can obtain better tracking effect even though the tracked object is occluded.
