28 May 2023, Volume 41 Issue 10

    

Special to S&T Review
Exclusive：Advanced train control technolog
Reviews
Papers
Science and Technology Humanities

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Special to S&T Review
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  New theory on L. K. Hua's economic optimization

  Mu-Fa Chen

  Science & Technology Review. 2023, 41(10): 5-8. https://doi.org/10.3981/j.issn.1000-7857.2023.10.001

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  We summarize Loo-Keng Hua's important update on economic optimization theory before his immortal death, which unfortunately fell asleep for 37 years and was not awakened until the end of 2021. Next, we introduce its subsequent progress, including one revision, one re-update, and five new developments: a new method for stability analysis; product (industry) level (ranking); prediction and adjustment; optimization of economic structure; efficient algorithms for reordering and large matrix principal eigenvalues (as well as the top 6 eigenvalues in major and minor order). It is rare that multiple transformations provide exactly the same unstable time and product. In the early years, the proof of the Hua's economic collapse theorem was based on the ergodic theorem of the Markov chain, and the recent results are all based on the transition probability matrix of the Markov chain, which may be seen as a new approach to economic optimization research. These achievements have been applied to one provincial-level and five national level input-output tables in China, testing the rationality and reliability of the theory.
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  Research progress and prospect of ultrafast science

  LEI Bingying, ZHANG Liyi, LIN Hua, FU Yuxi, ZHAO Wei, HOU Xun

  Science & Technology Review. 2023, 41(10): 9-30. https://doi.org/10.3981/j. issn. 1000-7857.2023. 10.002

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  Ultrafast science employs ultrafast light sources and ultrafast measurement as the main approaches to understand, apply and control macroscopic matter through the measurement and manipulation of ultrafast kinetic processes of microscopic particles. As one of the most important frontiers in international science and technology, the development of ultrafast science will provide an important impetus for original innovation in numerous disciplines. Its breakthroughs will help to address many important issues related to the vital national needs and public health. This paper focuses on the research of ultrafast laser technology, ultrafast measurement technology and ultrafast dynamics in ultrafast science, mainly introducing their development status, frontier application and future prospect. In-depth analysis of the problems facing the development of ultrafast science in China is provided, and specific recommendations are proposed to promote its development, including strengthening top-level design, promoting industrialization, improving the evaluation mechanism for talent cultivation, supporting major scientific and technological infrastructures, and participating in international big science programs.
Exclusive：Advanced train control technolog
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  Research review of the protection and operation technology for virtually coupled train sets in metros

  TANG Tao, LUO Xiaolin, LIU Hongjie, ZHANG Yanbing

  Science & Technology Review. 2023, 41(10): 31-42. https://doi.org/10.3981/j.issn.1000-7857.2023.10.003

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  Metros have the problems of passenger crowding during the peak hours and waste of transport capacity during the non-rush hours. Virtual coupling (VC) is expected to be a good solution to this problem, by which train formation can be dynamically adjusted, thus the line capacity is adjusted. This paper introduces the concept and relevant research of VC, and the existing problems and possible solutions are presented. Train protection and operation control methods are two most important problems among them. For the former, although relative braking distance principle is adopted, the space-time relationship between successive trains is omitted, thus, a space-time-separation-based train protection principle is proposed in this paper; for the latter, most of the existing studies only focus on the cruising control of VC, while the problem of non-synchronous parking that exists in the process of VC arrival at a station is wrongly ignored, which is particularly important in metros, a cooperative-control-based train following method is presented to solve this problem. This paper can provide a reference for readers to understand the development trend of virtual coupling technology in metros and to engage in relevant research.
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  Advances in the application research of rail transit robots

  ZHU Ruixiang, PEI Xuan, HOU Taogang

  Science & Technology Review. 2023, 41(10): 43-61. https://doi.org/10.3981/j. issn. 1000-7857.2023.10.004

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  This paper summarizes the application of robotics in the three aspects of rail transit, i.e., equipment manu-facturing, maintenance inspection, and operation services. Combined with the development status of intel-ligent robot technology in this field, we summarize the key technology and challenges of robots. Thus to propose the future direction of the cooperation of robotics and rail transit.
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  A cooperative control based reference curve generating method for virtually coupled train sets

  LIU Hongjie, LANG Yinghui, ZHANG Lei, TANG Tao

  Science & Technology Review. 2023, 41(10): 62-72. https://doi.org/10.3981/j.issn.1000-7857.2023.10.005

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  Virtual Coupling has been a hot research topic in railways in recent years. The proposed control methods in the existing literature for virtually coupled train sets (VCTS) mainly try to operate train units with the constraint of maintaining a small gap distance, but pay insufficient attention to the needs in the entering station process, which affects the work of VCTS in a station and is thus one of the most important part of VCTS in unban rail transits. To fill this gap, this paper firstly proposes an unsynchronized stopping problem between the train units in a VCTS when entering a station, defines the concept and the calculation method of stopping time difference between the train units. Then, inspired by the multi-agent cooperative control methods in related fields, a cooperative control-based reference curve generating method for VCTS is proposed. Followed by it, a mathematical optimization model to generate the reference curves for the train units in a VCTS is formulated, and a reinforcement learning DQN (deep Q network) based algorithm is designed to solve this problem. Optimized reference curves for each train units are generated automatically, considering the global objects and all constraints of VCTS. Finally, based on the real data of trains and lines from Beijing Metro Line 11, numerical simulation experiments are conducted. Experimental results prove the effectiveness of the proposed method which outperforms a commonly used control method of VCTS in the literature.
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  Safety testing method for intelligent visual train positioning of urban rail transit

  XIE Dong, CHAI Ming, ZHANG Qiang, SUN Ye

  Science & Technology Review. 2023, 41(10): 73-81. https://doi.org/10.3981/j.issn.1000-7857.2023.10.006

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  In order to solve the problem that intelligent train visual positioning system based on deep learning is difficult to test, this paper proposes a safety test method for intelligent train visual positioning. Firstly, based on the idea of Image-to-Image translation, we construct a generative adversarial network (GAN) to generate test cases. Then we implement the quantitative evaluation of the error detection ability of test cases based on deep mutation testing. Finally, according to the characteristics of urban rail operation organization, we propose a parallel test platform architecture of "virtual-reality, semi-reality, reality" to support the construction of the test case generation model and test execution. The method proposed in this paper provides a basis for ensuring the safety of intelligent visual train positioning, provides a new research idea for the safety application of intelligent visual perception technology in the autonomous running of trains, and plays an essential role in ensuring the safety of trains.
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  Modeling and verification of stability control strategy of train-train communication train control system based on SPTG

  LU Wanli, LV Jidong

  Science & Technology Review. 2023, 41(10): 82-91. https://doi.org/10.3981/j.issn.1000-7857.2023.10.007

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  Next generation train control system（NGTC）based on Train-Train communication realizes highly efficient train tracking control through three control strategies of constant spacing, constant time interval, and dynamic headway. Since the leader train control is random in the platoon control, how to ensure the safety of the platoon in different control strategies is very important. This paper proposes a Train-Train communication control strategy modeling and verification method based on stochastic priced timed game（SPTG）. Firstly, according to the requirements of different control strategies, a platoon control model including a leader train and follower trains is established by using SPTG automata, and the stability is verified. Secondly, taking time as the cost function, Q-learning is used to obtain the optimal driving strategy of the platoon through the platoon's SPTG automata model. Finally, combined with multi-train operation tracking scenarios, the stability simulation optimization of the platoon is carried out. The result shows that the stability error of the platoon is smaller than that of the random operation of the platoon.
Reviews
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  Development trends of global antineoplastic antibody

  ZHANG Weiwei, GUAN Tong, XU Li, LI Chunying

  Science & Technology Review. 2023, 41(10): 92-100. https://doi.org/10.3981/j.issn.1000-7857.2023.10.008

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  Immune checkpoint antibody drugs have opened up a new era in the field of tumor treatment since the 20th century. In 2021, the global market share of antitumor monoclonal antibody drugs has reached 62 billion US dollars. In recent years, domestic enterprises have also accelerated their development in this field. However, a big gap still exists between these enterprises and international pharmaceutical giants. In this context, it is of vital significance to fully grasp the international research and development trends and the panorama of the R&D pipeline. The research topics of core articles in this research field in the past 10 years were analyzed, and the development trend of the field was revealed through the evolution of the research topics. Seven active research directions were identified. In-depth analysis of specific research directions was carried out through further data mining from professional databases and institutional websites. Comprehensive analysis indicated that three directions including the efficacy and safety surveillance of marketed antibody drugs and drug combination, new antibody drugs such as bispecific antibodies and antibody-drug conjugates, and new targets represented by 4-1BB have been the research hotspots and focuses in recent years. Adverse event monitoring of marketed drugs should be strengthened, and efforts should be stepped up to support the research and development of new antibody drugs.
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  Development situation, challenges and prospects of hydrogen refueling facilities in China

  LIU Wei, WAN Yanming, ZHANG Yan, LIN Hanchen

  Science & Technology Review. 2023, 41(10): 101-105. https://doi.org/10.3981/j.issn.1000-7857.2023.10.009

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  Along with "promoting the construction of hydrogenation facilities" written into the government work report, release of development of hydrogen energy for the 2021-2035 period and approval of 5 fuel cell vehicle demonstration city clusters, hydrogen energy and fuel cell industries in China are developing rapidly. In 2022, China completed 109 new hydrogen refueling stations, and has built 358 hydrogen refueling stations till the end of 2019, all ranking first in the world. The overall construction of hydrogenation facilities in China is characterized by "more, faster, synergy and innovative”. However, there still are many problems in the high-pressure and large-displacement HRS equipment technologies, hydrogen pricing mechanisms and quality testing etc. It is suggested that the government should promote enterprises to enhance collaborative innovation and break through the bottleneck of core equipment, improve the hydrogen pricing mechanism and regularly test the quality of hydrogen, and promote the high-quality development of hydrogenation facilities.
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  Research progress of friction dynamics of disc brake system

  WANG Jingyue,WANG Tongyi, Lü Kun, WANG Junnian

  Science & Technology Review. 2023, 41(10): 106-114. https://doi.org/10.3981/j.issn.1000-7857.2023.10.010

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  Based on the relevant research literature of disc brake at home and abroad, this paper summarizes the commonly used disc brake models and brake noise research methods, and introduces the application range, advantages and disadvantages of the models and research methods. The control measures of brake friction noise are analyzed from the aspects of optimizing brake structure, changing brake parameters and active control. Finally, the future research direction of disc brake is prospected.
Papers
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  Geological disaster factors and susceptibility evaluation in the hinterland of the Loess Plateau

  RUAN Zheng, ZHOU Shaowei, YAO Sheng, TIAN Yao

  Science & Technology Review. 2023, 41(10): 115-124. https://doi.org/10.3981/j.issn.1000-7857.2023.10.011

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  With the continuous acceleration of urbanization, the impact of human activities on geological hazards has gradually increased, and people's lives and property safety have been threatened. Controlling geological hazards cannot delay. In this paper, nine factors such as slope gradient, relative elevation difference, slope direction, slope type, engineering geology groups, geomorphic type, rainfall, distance from rivers and distance from major traffic arteries are selected as evaluation indicators. The Information Value Model is used to evaluate the geological hazards susceptibility. The results show that: (1) This County can be divided into four types: extremely high susceptibility, high susceptibility, medium susceptibility and low susceptibility. Low susceptibility type is the largest, accounting for 64.64%, and extremely high susceptibility type is the smallest, accounting for 0.39%. (2) According to the verification, it can be seen that the density of geological hazards points in the extremely high areas and high areas is higher than that in medium susceptibility and low susceptibility areas, and the results are reasonable.
Science and Technology Humanities
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  The interaction between science and diplomacy: A study of the relationship between China and the World Federation of Scientific Workers (1949-1966)

  CHEN Lu1, ZHANG Li2*

  Science & Technology Review. 2023, 41(10): 125-132. https://doi.org/10.3981/j.issn.1000-7857.2023.10.012

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  The World Federation of Scientific Workers, which was founded in 1946, is a non-governmental organization initiated by the British Association of Scientific Workers and other groups. Its members are scientific workers' groups from eastern and western countries. Since the establishment of the WFSW, China has been an important member of it, and has experienced its establishment, development and decline. This article summarized the development history of the WFSW by analyzing the relevant reports and archives of People's Daily, analyzed the development of the relationship between China and the WFSW from 1949 to 1966, and discussed in detail the interaction between China and the WFSW during this period. Then the article pointed out that the WFSW was an important international platform for China to contact western capitalist countries and publicize the political stand of New China during the period from 1949 to 1966. The Chinese government and the scientific community are the important forces to promote the development and growth of the WFSW. At the same time, participating in a series of meetings of the WFSW is a typical case in which the Chinese government serves the country's diplomacy through international activities of the scientific community. Besides, it still has certain reference significance for the development of China's diplomatic work at present.