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Numerical study of wheel–rail adhesion performance of new-concept high-speed trains with aerodynamic wings

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2023年第8期24卷 673-691页

作者： Yang CHEN lin JING Tian LI Liang linG Kaiyun WANG State Key Laboratory of Traction Power Southwest Jiaotong UniversityChengdu 610011China

Wheel–rail adhesion is a complex tribological problem of wheel–rail rolling contact and is closely related to the operational safety of high-speed trains.A new design concept of high-speed trains was recently proposed with an expectation of a reduction of equivalent weight and total energy consumption by installing aerodynamic wings(aero-wings)on the roof,but it was accompanied by the disadvantage of deteriorating wheel–rail adhesion *** this study,a comprehensive multibody dynamics(MbD)model of the high-speed train with predesigned aero-wings is established using the commercial software SIMPACK,in which the real aerodynamic characteristics of the train are taken into *** available adhesion and adhesion margin are employed to evaluate the wheel–rail adhesion *** influences of aero-wing lift,train speed,and contact conditions on the wheel–rail adhesion level are *** results show that the load transfer caused by the action of aerodynamic load and braking torque was the main reason for the inconsistent adhesion condition of four *** influences of aero-wing lift and train speed on the wheel–rail adhesion performance are coupled;the available adhesion of both motor car and trailer is negatively correlated with aero-wing lift and train speed under all contact conditions,while the variation law of adhesion margin with train speed shows differences under different contact *** the wheel–rail interface was polluted by a‘third-body medium’such as water and oil,the wheel–rail adhesion performance was dramatically reduced and the wheelset tended to reach adhesion saturation and ***,track irregularity had little effect on the adhesion performance and could be ignored to save calculation *** results are of positive significance for reducing the wheel idling or sliding phenomenon and to ensure the safe operation of high-speed trains with aero-wings.

关键词： High-speed train Wheel–rail adhesion Aerodynamic wing Multi-body dynamics(MbD)

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Condition Monitoring of Turbines Using Nonlinear Mapping Method

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Wuhan University Journal of Natural Sciences 2004年第2期9卷 225-228页

作者： LiaoGuang-lan ShiTi-lin JiangNan SchoolofMechanicalScienceandEngineering HuazhongUniversityofScienceandTechnologyWuhan430074HubeiChina

Aiming at the non-linear nature of the signals generated from turbines, curvilinear component analysis (CCA), a novel nonlinear projection method that favors local topology conservation is presented for turbines conditions monitoring. This is accomplished in two steps. Time domain features are extracted from raw vibration signals, and then they are projected into a two-dimensional output space by using CCA method and form regions indicative of specific conditions, which helps classify and identify turbine states visually. Therefore, the variation of turbine conditions can be observed clearly with the trajectory of image points for the feature data in the two-dimensional space, and the occurrence and development of failures can be monitored in time. Key words condition monitoring - turbines - nonlinear mapping - curvilinear component analysis CLC number TP 17 - TH 17 Foundation item: Supported by the National Key basic Research Special Found of China (2003Cb716207) and the National Natural Science Foundation of China (50375047)biography: Liao Guang-lan (1974-), male, Ph. D. candidate, research direction: fault diagnosis, pattern recognition and neural networks.

关键词： condition monitoring turbines nonlinear mapping curvilinear component analysis

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IDS-INT:Intrusion detection system using transformer-based transfer learning for imbalanced network traffic

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Digital Communications and Networks 2024年第1期10卷 190-204页

作者： Farhan Ullah Shamsher Ullah Gautam Srivastava Jerry Chun-Wei lin School of Software Northwestern Polytechnical UniversityXian710072ShaanxiChina Knowledge Unit of Systems and Technology University of Management and TechnologySialkot 51040Pakistan Department of Math and Computer Science Brandon UniversityBrandonMB R7A 6A9Canada Department of Computer Science and Math Lebanese American UniversityBeirut1102Lebanon Western Norway University of Applied Sciences BergenNorway Research Centre for Interneural Computing China Medical UniversityTaichungTaiwanChina

A network intrusion detection system is critical for cyber security against llegitimate *** terms of feature perspectives,network traffic may include a variety of elements such as attack reference,attack type,a subcategory of attack,host information,malicious scripts,*** terms of network perspectives,network traffic may contain an imbalanced number of harmful attacks when compared to normal *** is challenging to identify a specific attack due to complex features and data imbalance *** address these issues,this paper proposes an Intrusion Detection System using transformer-based transfer learning for Imbalanced Network Traffic(IDS-INT).IDS-INT uses transformer-based transfer learning to learn feature interactions in both network feature representation and imbalanced ***,detailed information about each type of attack is gathered from network interaction descriptions,which include network nodes,attack type,reference,host information,***,the transformer-based transfer learning approach is developed to learn detailed feature representation using their semantic ***,the Synthetic Minority Oversampling Technique(SMOTE)is implemented to balance abnormal traffic and detect minority ***,the Convolution Neural Network(CNN)model is designed to extract deep features from the balanced network ***,the hybrid approach of the CNN-Long Short-Term Memory(CNN-LSTM)model is developed to detect different types of attacks from the deep *** experiments are conducted to test the proposed approach using three standard datasets,i.e.,UNsWNb15,CIC-IDS2017,and *** explainable AI approach is implemented to interpret the proposed method and develop a trustable model.

关键词： Network intrusion detection Transfer learning Features extraction Imbalance data Explainable AI Cybersecurity

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Identification of pollution sources in rivers using a hydrodynamic diffusion wave model and improved bayesian-Markov chain Monte Carlo algorithm

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Frontiers of Environmental Science & Engineering 2023年第7期17卷 91-105页

作者： Hailong Yin Yiyuan lin Huijin Zhang Ruibin Wu Zuxin xu Key Laboratory of Yangtze River Water Environment of Ministry of Education Tongji UniversityShanghai 200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China Fujian Provincial Key Laboratory of Green building Technology Fujian Academy of Building Research Co.Ltd.Fuzhou 350108China

Water quality restoration in rivers requires identification of the locations and discharges of pollution sources,and a reliable mathematical model to accomplish this identification is *** this paper,an innovative framework is presented to inversely estimate pollution sources for both accident preparedness and normal management of the allowable pollutant *** proposed model integrates the concepts of the hydrodynamic diffusion wave equation and an improved bayesian-Markov chain Monte Carlo method(MCMC).The methodological framework is tested using a designed case of a sudden wastewater spill incident(i.e.,source location,flow rate,and starting and ending times of the discharge)and a real case of multiple sewage inputs into a river(i.e.,locations and daily flows of sewage sources).The proposed modeling based on the improved bayesian-MCMC method can effectively solve high-dimensional search and optimization problems according to known river water levels at pre-set monitoring *** can adequately provide accurate source estimation parameters using only one simulation through exploration of the full parameter *** comparison,the inverse models based on the popular random walk Metropolis(RWM)algorithm and microbial genetic algorithm(MGA)do not produce reliable estimates for the two scenarios even after multiple simulation runs,and they fall into locally optimal *** much more water level data are available than water quality data,the proposed approach also provides a cost-effective solution for identifying pollution sources in rivers with the support of high-frequency water level data,especially for rivers receiving significant sewage discharges.

关键词： Identification of pollution sources Waterquality restoration bayesianinference Hydrodynamic model Inverseproblem

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Phase Noise Effects on the Performance of High-Order Digital Modulation Terahertz Communication System

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Chinese Journal of Electronics 2022年第3期31卷 589-594页

作者： DENG xianjin YANG Hao WU Qiuyu JIANG Jun lin Changxing Institute of Electronic Engineering China Academy of Engineering Physics Microsystem and Terahertz Research Center China Academy of Engineering Physics

As the carrier frequency goes into the terahertz band, the phase noise of the signal source has increasing impacts on the performance of the communication system. Considering a 16 QAM high-order digital modulation terahertz communication system(DMTCS),by comparing the influence of two kinds of local oscillator signal sources with different phase noise characteristics on the bit error rate(bER) performance of the system based on theoretical analysis and experimental research, it is found that the near-end phase noise of local oscillator signal source has a great influence on the bER performance of the DMTCS. The suppression of phase noise of the local oscillator signal source based on choosing loop bandwidth of the digital phase-locked loop(DPLL) at the receiving end is also discussed. It is found that the negative impacts of phase noise on bER performance of the system can be efficiently decreased by reasonably selecting the loop bandwidth of the DPLL.

关键词： DMTCS DPLL digital phase locked loops quadrature amplitude modulation 16QAM high-order digital modulation terahertz communication system digital phase-locked loop oscillators local oscillator signal source bER performance phase noise bit error rate performance signal sources near-end phase noise effects error statistics

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ProSync： A protective synchronization scheme for NC-OFDM based opportunistic spectrum sharing system

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High Technology Letters 2012年第2期18卷 186-190页

作者：侯炜 Zhang lin Shah xiuming Complex Engineered Systems Laboratory Department of Electronic EngineeringTsinghua UniversityBeijing 100084P.R.China

A protective synchronization scheme （ProSync） for the non-contiguous orthogonal frequency-division multiplexing （NC-OFDM） system is proposed in this paper, aiming to minimize the impact of cross-band interference in opportunistic dynamic spectrum sharing networks. ProSync partly shrinks the preamble at the transmitter and exploits two multi-band filters at the receiver. by doing so, the potential interference suffered by NC-OFDM users, including both the cross-band interference and self interference, can be greatly reduced. Simulation results verify the effectiveness of ProSync, which is able to lower the carrier frequency offset （CFO） estimation error by up to 50%, compared with the traditional method.

关键词： non-contiguous orthogonal frequency-division multiplexing (NC-OFDM) synchronization cross-band interference opportunistic spectrum sharing

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Flexible Nanocomposite Conductors for Electromagnetic Interference Shielding

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Nano-Micro Letters 2023年第10期15卷 210-259页

作者： Ze Nan Wei Wei Zhenhua lin Jingjing Chang Yue Hao State Key Discipline Laboratory of Wide band Gap Semiconductor Technology School of MicroelectronicsXidian University2 South Taibai RoadXi’an 710071People’s Republic of China Advanced Interdisciplinary Research Center for Flexible Electronics Xidian University2 South Taibai RoadXi’an 710071People’s Republic of China

With the extensive use of electronic communication technology in integrated circuit systems and wearable devices, electromagnetic interference(EMI) has increased dramatically. The shortcomings of conventional rigid EMI shielding materials include high brittleness, poor comfort, and unsuitability for conforming and deformable applications. Hitherto, flexible(particularly elastic) nanocomposites have attracted enormous interest due to their excellent deformability. However, the current flexible shielding nanocomposites present low mechanical stability and resilience, relatively poor EMI shielding performance, and limited multifunctionality. Herein, the advances in low-dimensional EMI shielding nanomaterials-based elastomers are outlined and a selection of the most remarkable examples is discussed. And the corresponding modification strategies and deformability performance are summarized. Finally, expectations for this quickly increasing sector are discussed, as well as future challenges.

关键词： Electromagnetic interference shielding Intrinsically stretchable nanocomposites Compressible monolith Low-dimensional materials Flexible devices

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Recent advances in engineered nanomaterials for acute kidney injury theranostics

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Nano Research 2021年第4期14卷 920-933页

作者： Lefeng Wang Yunjing Zhang Yangyang Li Jianghua Chen Weiqiang lin Kidney Disease Center the First Affiliated Hospital Zhejiang University School of MedicineInstitute of NephrologyZhejiang UniversityHangzhou 310003China Key Laboratory of Kidney Disease Prevention and Control Technology Hangzhou 310003China The Fourth Affiliated Hospital Institute of Translational Medicine Zhejiang University School of MedicineJinhua 322000China Key Laboratory of Womens Reproductive Health Research of Zhejiang Province Womens Hospital Zhejiang University School of Mediciney Hangzhou 310006China

Acute kidney injury(AKI),has become the focus of increasing attention due to its high risk of *** early diagnosis and treatment of AKI significantly reduce the risk of renal tissue damage and kidney ***,the efficient early diagnosis and treatment approach for AKI remains a *** screening via precise nanomaterial theranostics is a new alternative *** study summarizes the recent advances in functional nanomaterials in the early detection and treatment of *** challenges and problems in the use of nanomaterials for AKI in clinical applications are also *** is anticipated that highlighting these new advances will lay the foundation for further translational research on the promising application of nanomaterials for AKI.

关键词： acute kidney injury nanomaterials early detection therapy translational applications

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Not vegetation itself but mis-revegetation reduces water resources

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Science China Earth Sciences 2021年第3期64卷 404-411页

作者： Guoyi ZHOU Jun xIA Ping ZHOU Tingting SHI lin LI Institute of Ecology and School of Applied Meteorology Nanjing University of Information Science&TechnologyNanjing210044China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Research Center of Water Resources Chinese Academy of SciencesBeijing100101China Guangdong Open Laboratory of Geospatial Information Technology and Application Guangzhou Institute of GeographyGuangdong Academy of SciencesGuangzhou510070China

Increasing greening of planet Earth to slow down the rise of atmospheric CO_(2) concentrations is certainly desirable;however,its consequences on water resources are less affirmative and thus are a matter of wide ***,as the largest and most successful country of the world in terms of artificial revegetation,is naturally the focus of the concerns and *** on previous studies,we analyzed the mechanism for the effects of climate and watershed characteristics on water resources,explained various hydrological results and phenomena,and considered the ways in which water consumption by artificial revegetation projects can be ***,some guidelines are suggested for artificial revegetation at watershed scale with consideration of water resource *** findings of this study highlight the need for more top-down approaches when studying the mechanism of"forest and water".

关键词： Greening Climate Revegetation Water resources Top-down approaches

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Effect of SiO_(2)introduction on luminescence properties of LuAG:Mn^(2+) phosphors

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Journal of Rare Earths 2022年第2期40卷 253-259,I0003页

作者： Chenyao Zhao Hui lin Dawei Zhang Ruijin Hong Shengming Zhou Engineering Research Center of Optical Instrument and System Ministry of Education and Shanghai Key Lab of Modem Optical SystemUniversity of Shanghai for Science and TechnologyShanghai 200093China Laboratory of Micro-Nano Optoelectronic Materials and Devices Key Laboratory of Materials for High-Power LaserShanghai Institute of Optics and Fine MechanicsChinese Academy of SciencesShanghai 201800China

Mn^(2+)doped LuAG phosphors with different contents of Si^(4+)ions were synthesized via the solid-state reaction method and the effects of Si^(4+)doping on the crystal structure and luminescence properties of phosphors were *** patterns of all phosphors exhibit a pure phase but with different extents of *** to the 4 T1→6 A1 transition of Mn^(2+),the LuAG:Mn^(2+),Si^(4+)phosphors exhibit a broad emission band with an emission peak at 582 ***,the introduction of Si^(4+)not only improves the emission intensity but also induces a red-shift with the emission peak from 582 to 612 nm and the spectra broadening with the full width at half maximum value from 64 to 74 nm,which results from the decrease of bond length between O2-anions and Mn^(2+)cations and the re-absorption of Mn^(2+)-Mn^(2+)*** content of Si^(4+)replacement can weaken thermal quenching of Mn^(2+).Thus,via regulating the content of Si,the Mn^(2+),Si^(4+)co-doped LuAG phosphor with low correlated color temperature is a candidate for warm wLEDs.

关键词： Lu_(3)Al_(5)O_(12) Mn^(2+)luminescence Warm white LEDs Transition metal luminescence Rare earths

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