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Dependability analysis of the data communication system in train control system

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Science China(Technological Sciences) 2009年第9期52卷 2605-2618页

作者： xu tianhua TANG Tao GAO ChunHai CAI BaiGen State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong UniversityBeijing 100044China

Communication based train control (CBTC) system is based on mobile communication and overcomes fixed blocks in order to increase track utilization and train safety. The data communication system (DCS) between trains and wayside equipment is a crucial factor for the safe and efficient operation of CBTC system. The dependability under various transmission conditions needs to be modeled and evaluated. In this paper,a stochastic reward net (SRN) model for DCS based IEEE 802.11 standard was developed,which captures all relevant failure and failure recovery behavior system aspects in a concise way. We compared the reliability,availability for DCS with and without access point (AP) and antenna redundant configuration. We also quantitatively evaluated and compared the frame loss probability for three DCS configurations with different train velocities and train numbers in one radio cell. Fixed-point iteration was adopted to simplify the analysis. Numerical results showed the significant improvement of the reliability,availability and the frame loss probability index for the full redundant configuration.

关键词： dependability analysis data communication system (DCS) stochastic reward net (SRN) communication based train control (CBTC)

Achievable information rate optimization in C‑band optical fber communication system

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Frontiers of Optoelectronics 2023年第2期16卷 123-128页

作者： Zheng Liu tianhua xu Ji Qi Joshua Uduagbomen Jian Zhao Tiegen Liu School of Precision Instrument and Opto-Electronics Engineering Tianjin UniversityTianjin 300072China School of Engineering University of WarwickCoventry CV47ALUK Department of Electronic and Electrical Engineering University College LondonLondon WC1E 7JEUK

Optical fber communication networks play an important role in the global telecommunication ***,nonlinear efects in the optical fber and transceiver noise greatly limit the performance of fber communication *** this paper,the product of mutual information(MI)and communication bandwidth is used as the metric of the achievable information rate(AIR).The MI loss caused by the transceiver is also considered in this work,and the bit-wise MI,generalized mutual information(GMI),is used to calculate the *** loss is more signifcant in the use of higher-order modulation *** AIR analysis is carried out in the QPSK,16QAM,64QAM and 256QAM modulation formats for the communication systems with diferent communication bandwidths and transmission distances based on the enhanced Gaussian noise(EGN)*** paper provides suggestions for the selection of the optimal modulation format in diferent transmission scenarios.

关键词： Optical fber communication Achievable information rate Mutual information Generalized mutual information

Formal verification of safety protocol in train control system

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Science China(Technological Sciences) 2011年第11期54卷 3078-3090页

作者： ZHANG Yan TANG Tao LI KePing MERA Jose Manuel ZHU Li ZHAO Lin xu tianhua State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing 100044 China Railway Technologies Research Centre Universidad Politecnica de Madrid Madrid 228006 Spain

In order to satisfy the safety-critical requirements,the train control system(TCS) often employs a layered safety communication protocol to provide reliable ***,both description and verification of the safety protocols may be formidable due to the system *** this paper,interface automata(IA) are used to describe the safety service interface behaviors of safety communication protocol.A formal verification method is proposed to describe the safety communication protocols using IA and translate IA model into PROMELA model so that the protocols can be verified by the model checker SPIN.A case study of using this method to describe and verify a safety communication protocol is *** verification results illustrate that the proposed method is effective to describe the safety protocols and verify deadlocks,livelocks and several mandatory consistency properties.A prototype of safety protocols is also developed based on the presented formally verifying method.

关键词： train control system safety communication protocol interface automata verification

Growth of Nd : YAG Free from Core and Dislocation

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Chinese Physics Letters 1993年第11期10卷 698-701页

作者： xu tianhua WU Zihe PENG Weiqing ZHEN Qimeng ZHOU Jianmin ZHANG Shengxiu XIE Sanwen xu Guangyu HANG Changmin Southwestern Institute of Technical Physics Chengdu 610041

Nd:YAG crystals free from core and dislocation have been grown by using the“controlled reversion of solid-liquid interface” *** basic idea of the method is to combine the respective advantages of both the convex and the flat interface growth and to overpass "safely"the interface reversion so that the whole crystal could be grown in stable fluid How states.

关键词： interface Nd:YAG dislocation

Characterization of distinct microbiota associated with androgenetic alopecia patients treated and untreated with platelet-rich plasma(PRP)

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Animal Models and Experimental Medicine 2024年第2期7卷 106-113页

作者： Qian Zhang Yanan Wang Cheng Ran Yingmei Zhou Zigang Zhao tianhua xu Hongwei Hou Yuan Lu Beijing Life Science Academy BeijingChina Department of Pathology Affiliated Hospital of Hebei UniversityBaodingChina Department of Otolaryngology Affiliated Hospital of Hebei UniversityBaodingChina Department of Dermatology Huazhong University of Science and Technology Union Shenzhen HospitalShenzhenChina Department of Dermatology Hainan Hospital of PLA General HospitalSanyaChina Department of Chemical Engineering Tsinghua UniversityBeijingChina

Background:Androgenic alopecia(AGA)is the most common type of hair loss in men,and there are many studies on the treatment of hair loss by platelet-rich plasma(PRP).The human scalp contains a huge microbiome,but its role in the process of hair loss remains unclear,and the relationship between PRP and the microbiome needs further ***,the purpose of this study was to investigate the effect of PRP treatment on scalp microbiota ***:We performed PRP treatment on 14 patients with AGA,observed their clinical efficacy,and collected scalp swab samples before and after *** scalp microflora of AGA patients before and after treatment was characterized by amplifying the V3-V4 region of the 16 s RNA gene and sequencing for bacterial ***:The results showed that PRP was effective in the treatment of AGA patients,and the hair growth increased *** results of relative abundance analysis of microbiota showed that after treatment,g_Cutibacterium increased and g_Staphylococcus decreased,which played a stable role in scalp *** addition,g_Lawsonella decreased,indicating that the scalp oil production decreased after ***:The findings suggest that PRP may play a role in treating AGA through scalp microbiome rebalancing.

关键词： androgenic alopecia microbiome platelet-rich plasma scalp

Highly sensitive and stable probe refractometer based on configurable plasmonic resonance with nano-modified fiber core

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Opto-Electronic Advances 2023年第6期6卷 38-51页

作者： Jianying Jing Kun Liu Junfeng Jiang tianhua xu Shuang Wang Tiegen Liu School of Precision Instruments and Opto-Electronics Engineering Tianjin UniversityTianjin 300072China Key Laboratory of Opto-Electronics Information Technology Ministry of EducationTianjin UniversityTianjin 300072China Tianjin Optical Fiber Sensing Engineering Center Institute of Optical Fiber SensingTianjin UniversityTianjin 300072China

A dispersion model is developed to provide a generic tool for configuring plasmonic resonance spectral *** customized design of the resonance curve aiming at specific detection requirements can be *** to the model,a probe-type nano-modified fiber optic configurable plasmonic resonance(NMF-CPR)sensor with tip hot spot enhancement is demonstrated for the measurement of the refractive index in the range of 1.3332-1.3432 corresponding to the low-concentration biomarker *** new-type sensing structure avoids excessive broadening and redshift of the resonance dip,which provides more possibilities for the surface modification of other functional *** tip hot spots in nanogaps between the Au layer and Au nanostars(AuNSs),the tip electric field enhancement of AuNSs,and the high carrier mobility of the WSe_(2)layer synergistically and significantly enhance the sensitivity of the ***-perimental results show that the sensitivity and the figure of merit of the tip hot spot enhanced fiber NMF-CPR sensor can achieve up to 2995.70 nm/RIU and 25.04 RIU^(−1),respectively,which are 1.68 times and 1.29 times higher than those of the conventional fiber plasmonic resonance *** results achieve good agreements with numerical simulations,demonstrate a better level compared to similar reported studies,and verify the correctness of the dispersion *** detection resolution of the sensor reaches up to 2.00×10^(−5)RIU,which is obviously higher than that of the conventional side-polished fiber plasmonic resonance *** indicates a high detection accuracy of the *** dense Au layer effectively prevents the intermediate nanomaterials from shedding and chemical degradation,which enables the sensor with high ***,the terminal reflective sensing structure can be used as a practical probe and can allow a more convenient operation.

关键词： fiber photonics sensor customized plasmonic resonance curve nano-modified fiber core tip hot spot effect high sensitivity and stability

基于递推最小二乘的红外焦平面非均匀校正算法

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光子学报 2006年第2期35卷 261-264页

作者：徐田华赵亦工西安电子科技大学模式识别与智能控制研究所西安710071

根据递推最小二乘和图像配准原理,提出了基于递推最小二乘的红外焦平面非均匀校正算法(简称ILS算法),有效降低算法的时间和空间复杂度,使噪音图像的校正处理能够实时完成.ILS算法具有噪音参量估计准确度高、收敛速度快和计算复杂度低等... 详细信息

根据递推最小二乘和图像配准原理,提出了基于递推最小二乘的红外焦平面非均匀校正算法(简称ILS算法),有效降低算法的时间和空间复杂度,使噪音图像的校正处理能够实时完成.ILS算法具有噪音参量估计准确度高、收敛速度快和计算复杂度低等优点.给出了算法的推导并用仿真数据对算法的有效性进行验证.

关键词：红外焦平面非均匀校正递推最小二乘

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列车控制系统中数据通信子系统的帧丢失概率

中国铁道科学 2008年第3期29卷 110-114页

作者：徐田华唐涛北京交通大学轨道交通控制与安全国家重点实验室北京100044

利用随机Petri网模型,综合随机信道恶化、越区切换、无线接入设备故障等无线信道失效因素,建立列车控制系统中数据通信子系统非冗余结构和冗余结构的帧丢失概率模型,给出分解的无线数据通信模型的定点迭代求解方程。分别计算:冗余结构... 详细信息

利用随机Petri网模型,综合随机信道恶化、越区切换、无线接入设备故障等无线信道失效因素,建立列车控制系统中数据通信子系统非冗余结构和冗余结构的帧丢失概率模型,给出分解的无线数据通信模型的定点迭代求解方程。分别计算:冗余结构、非冗余结构的数据通信系统的帧丢失概率;不同列车数量、不同列车运行速度对应的帧丢失概率。分析计算结果表明:冗余结构数据通信系统的帧丢失概率远低于非冗余结构的;主要原因是冗余结构数据通信系统不因单一AP通信中断而失效、有效消除了列车越区切换对帧丢失概率的影响。

关键词：数据通信子系统列车控制系统帧丢失概率随机Petri网冗余结构

An Application of Canny Edge Detection Algorithm to Rail Thermal Image Fault Detection

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Journal of Computer and Communications 2015年第11期3卷 19-24页

作者： Libo Cai Yu Ma Tangming Yuan Haifeng Wang tianhua xu Department of Computer Science University of York Heslington York UK National Engineering Research Center of Rail Transportation Operation and Control Systems Beijing Jiaotong University Beijing China Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing China

The paper discusses an application for rail track thermal image fault detection. In order to get better results from the Canny edge detection algorithm, the image needs to be processed in advance. The histogram equalization method is proposed to enhance the contrast of the image. Since a thermal image contains multiple parallel rail tracks, an algorithm has been developed to locate and separate the tracks that we are interested in. This is accomplished by applying the least squares linear fitting technique to represent the surface of a track. The performance of the application is evaluated by using a number of images provided by a specialised company and the results are essentially favourable.

关键词： Fault Detection Rail Thermal Image Canny Edge Detection Linear Least Squares