Improvement of transportation infrastructure quality will lead to more sufficient market competition and promote the flow of resources with greater efficiency. This paper considers China's railway speed-up in 2007...Improvement of transportation infrastructure quality will lead to more sufficient market competition and promote the flow of resources with greater efficiency. This paper considers China's railway speed-up in 2007 as a quasi-natural experiment on China's transportation infrastructure quality improvement. With the initial operation of electric multiple units(EMUs) as the basis of grouping, this research examines the effect of railway speed-up on corporate total factor productivity(TFP) growth by the differencein-differences(DID) method. Overally, the results reveal positive effects both on firms' technological change and efficiency improvement, which lead to the increase of TFP. Based on subsamples divided by different regions and types of enterprises, further analysis indicates that the productivity of exporter, non-state and coastal firms has been mostly affected by the railway speed-up. These conclusions are verified by a placebo test. Besides, firms within "one-hour economic circle" have been shown more sensitive to the effect of railway speed increase.展开更多
The geometric shape of the wheel tread is mathematically expressed,and geometric parameters affecting the shape of the wheel were extracted as design variables.The vehicle dynamics simulation model was established bas...The geometric shape of the wheel tread is mathematically expressed,and geometric parameters affecting the shape of the wheel were extracted as design variables.The vehicle dynamics simulation model was established based on the vehicle suspension parameters and track conditions of the actual operation,and the comprehensive dynamic parameters of the vehicle were taken as the design objectives.The matching performance of the wheel equivalent conicity with the vehicle and track parameters was discussed,and the best equivalent conicity was determined as the constraint condition of the optimization problem;a numerical calculation program is written to solve the optimization model based on a multi-population genetic algorithm.The results show that the algorithm has a fast calculation speed and good convergence.Compared with the LM profile,the two optimized profiles effectively reduce the wheelset acceleration and improve the lateral stability of the bogie and vehicle stability during straight running.Due to the optimized profile increases the equivalent conicity under larger lateral displacement of the wheelset,the lateral wheel-rail force,derailment coefficient,wheel load reduction rate,and wear index are reduced when the train passes through the curve line.This paper provides a feasible way to ensure the speed-up operation of a freight train.展开更多
A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the ＂quantum speed-up capacity＂ which ...A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the ＂quantum speed-up capacity＂ which reveals the potential ability of a quantum system to be accelerated. We explore the evolutions of the speed-up capacity in different quantum channels for two-qubit states. We find that although the dynamics of the capacity is varying in different kinds of channels, it is positive in most situations which are considered in the context except one case in the amplitude-damping channel. We give the reasons for the different features of the dynamics. Anyway, the speed-up capacity can be improved by the memory effect. We find two ways which may be used to control the capacity in an experiment： selecting an appropriate coefficient of an initial state or changing the memory degree of environments.展开更多
为解决步进电动机加减速控制问题,给出了基于抛物线算法的FPGA实现方案,并在一片常用的可编程门阵列Cyclone I FPGA得到了具体验证。该方案综合运用FPGA可编程的逻辑功能,针对步进电动机控制特点,采样HDL硬件描述语言实现了SPI通讯模块...为解决步进电动机加减速控制问题,给出了基于抛物线算法的FPGA实现方案,并在一片常用的可编程门阵列Cyclone I FPGA得到了具体验证。该方案综合运用FPGA可编程的逻辑功能,针对步进电动机控制特点,采样HDL硬件描述语言实现了SPI通讯模块、计数模块、ROM模块等功能。整个控制系统精度高、调节快,运行效果表明,在加减速过程中加速度与速度的平稳性有了较大的改善,并且占用很少的逻辑单元。展开更多
This paper preliminarily evaluates the speedup,scalability,and prediction skill of the highperformance advanced regional eta coordinate model（H-AREM）,which is based on several parallel processing methods and decompo...This paper preliminarily evaluates the speedup,scalability,and prediction skill of the highperformance advanced regional eta coordinate model（H-AREM）,which is based on several parallel processing methods and decomposition strategies.Results show that the parallel version of the model that is based on a modular parallel framework and a multidimensional domain decomposition strategy performs better overall,e.g.it is faster and more scalable than the version based on a message passing interface and a one-dimensional decomposition strategy.In particular,the scalability of the H-AREM with a resolution of 8 km approaches 8099 cores.Moreover,in the H-AREM,higher resolutions result in more realistic precipitation predictions without remarkable increases in simulation time.展开更多
The support vector machine （SVM） is a novel machine learning tool in data mining. In this paper, the geometric approach based on the compressed convex hull （CCH） with a mathematical framework is introduced to solv...The support vector machine （SVM） is a novel machine learning tool in data mining. In this paper, the geometric approach based on the compressed convex hull （CCH） with a mathematical framework is introduced to solve SVM classification problems. Compared with the reduced convex hull （RCH）, CCH preserves the shape of geometric solids for data sets; meanwhile, it is easy to give the necessary and sufficient condition for determining its extreme points. As practical applications of CCH, spare and probabilistic speed-up geometric algorithms are developed. Results of numerical experiments show that the proposed algorithms can reduce kernel calculations and display nice performances.展开更多
Suppose a practical scene that when two or more parties want to schedule anappointment, they need to share their calendars with each other in order to make itpossible. According to the present result the whole communi...Suppose a practical scene that when two or more parties want to schedule anappointment, they need to share their calendars with each other in order to make itpossible. According to the present result the whole communication cost to solve thisproblem should be their calendars’ length by using a classical algorithm. In this work, weinvestigate the appointment schedule issue made by N users and try to accomplish it inquantum information case. Our study shows that the total communication cost will bequadratic times smaller than the conventional case if we apply a quantum algorithm in theappointment-scheduling problem.展开更多
基金supported by the National Social Science Foundation of China (NSFC) programs (14CJL020, 15CJL048)the Humanity and Social Science Youth Foundation Program of Ministry of Education of China (15YJC790006)
文摘Improvement of transportation infrastructure quality will lead to more sufficient market competition and promote the flow of resources with greater efficiency. This paper considers China's railway speed-up in 2007 as a quasi-natural experiment on China's transportation infrastructure quality improvement. With the initial operation of electric multiple units(EMUs) as the basis of grouping, this research examines the effect of railway speed-up on corporate total factor productivity(TFP) growth by the differencein-differences(DID) method. Overally, the results reveal positive effects both on firms' technological change and efficiency improvement, which lead to the increase of TFP. Based on subsamples divided by different regions and types of enterprises, further analysis indicates that the productivity of exporter, non-state and coastal firms has been mostly affected by the railway speed-up. These conclusions are verified by a placebo test. Besides, firms within "one-hour economic circle" have been shown more sensitive to the effect of railway speed increase.
基金The present work was supported by Sichuan Science and Technology Program(2020YJ0308 and 2021YJ0026).
文摘The geometric shape of the wheel tread is mathematically expressed,and geometric parameters affecting the shape of the wheel were extracted as design variables.The vehicle dynamics simulation model was established based on the vehicle suspension parameters and track conditions of the actual operation,and the comprehensive dynamic parameters of the vehicle were taken as the design objectives.The matching performance of the wheel equivalent conicity with the vehicle and track parameters was discussed,and the best equivalent conicity was determined as the constraint condition of the optimization problem;a numerical calculation program is written to solve the optimization model based on a multi-population genetic algorithm.The results show that the algorithm has a fast calculation speed and good convergence.Compared with the LM profile,the two optimized profiles effectively reduce the wheelset acceleration and improve the lateral stability of the bogie and vehicle stability during straight running.Due to the optimized profile increases the equivalent conicity under larger lateral displacement of the wheelset,the lateral wheel-rail force,derailment coefficient,wheel load reduction rate,and wear index are reduced when the train passes through the curve line.This paper provides a feasible way to ensure the speed-up operation of a freight train.
基金supported by the EU FP7 Marie–Curie Career Integration Fund(Grant No.631883)the Royal Society Research Fund(Grant No.RG150036)the Fundamental Research Fund for the Central Universities,China(Grant No.2018IB010)
文摘A potential acceleration of a quantum open system is of fundamental interest in quantum computation, quantum communication, and quantum metrology. In this paper, we investigate the ＂quantum speed-up capacity＂ which reveals the potential ability of a quantum system to be accelerated. We explore the evolutions of the speed-up capacity in different quantum channels for two-qubit states. We find that although the dynamics of the capacity is varying in different kinds of channels, it is positive in most situations which are considered in the context except one case in the amplitude-damping channel. We give the reasons for the different features of the dynamics. Anyway, the speed-up capacity can be improved by the memory effect. We find two ways which may be used to control the capacity in an experiment： selecting an appropriate coefficient of an initial state or changing the memory degree of environments.
文摘为解决步进电动机加减速控制问题,给出了基于抛物线算法的FPGA实现方案,并在一片常用的可编程门阵列Cyclone I FPGA得到了具体验证。该方案综合运用FPGA可编程的逻辑功能,针对步进电动机控制特点,采样HDL硬件描述语言实现了SPI通讯模块、计数模块、ROM模块等功能。整个控制系统精度高、调节快,运行效果表明,在加减速过程中加速度与速度的平稳性有了较大的改善,并且占用很少的逻辑单元。
基金jointly supported by the National Basic Research Program of China(973 Program)[grant number 6131270305]the Ministry of Water Resources'special research grant for non-profit public service[grant number 201301062-02]+1 种基金the National Natural Science Foundation of China[grant number61572058]the Strategic Priority Research Program of the Chinese Academy of Sciences[grant number XDA05110304]
文摘This paper preliminarily evaluates the speedup,scalability,and prediction skill of the highperformance advanced regional eta coordinate model（H-AREM）,which is based on several parallel processing methods and decomposition strategies.Results show that the parallel version of the model that is based on a modular parallel framework and a multidimensional domain decomposition strategy performs better overall,e.g.it is faster and more scalable than the version based on a message passing interface and a one-dimensional decomposition strategy.In particular,the scalability of the H-AREM with a resolution of 8 km approaches 8099 cores.Moreover,in the H-AREM,higher resolutions result in more realistic precipitation predictions without remarkable increases in simulation time.
基金Supported by the National Natural Science Foundation of China (No. 30571059)the National High-Tech Research and Development Program of China (No. 2006AA02Z190)Shanghai Leading Academic Discipline Project (No. 530405)
文摘The support vector machine （SVM） is a novel machine learning tool in data mining. In this paper, the geometric approach based on the compressed convex hull （CCH） with a mathematical framework is introduced to solve SVM classification problems. Compared with the reduced convex hull （RCH）, CCH preserves the shape of geometric solids for data sets; meanwhile, it is easy to give the necessary and sufficient condition for determining its extreme points. As practical applications of CCH, spare and probabilistic speed-up geometric algorithms are developed. Results of numerical experiments show that the proposed algorithms can reduce kernel calculations and display nice performances.
基金Supported by the National Natural Science Foundation of Chinaunder Grant Nos. 61501247, 61373131 and 61702277the Six Talent Peaks Project ofJiangsu Province (Grant No. 2015-XXRJ-013)+2 种基金Natural Science Foundation of JiangsuProvince (Grant No. BK20171458)he Natural Science Foundation of the HigherEducation Institutions of Jiangsu Province (China under Grant No. 16KJB520030)theNUIST Research Foundation for Talented Scholars under Grant No. 2015r014, PAPDand CICAEET funds.
文摘Suppose a practical scene that when two or more parties want to schedule anappointment, they need to share their calendars with each other in order to make itpossible. According to the present result the whole communication cost to solve thisproblem should be their calendars’ length by using a classical algorithm. In this work, weinvestigate the appointment schedule issue made by N users and try to accomplish it inquantum information case. Our study shows that the total communication cost will bequadratic times smaller than the conventional case if we apply a quantum algorithm in theappointment-scheduling problem.
