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1تقرير
المؤلفون: Pei, Xiaobing, Yang, Haoran, Shen, Gang
مصطلحات موضوعية: Computer Science - Machine Learning
الوصف: Recent studies have shown that attackers can catastrophically reduce the performance of GNNs by maliciously modifying the graph structure or node features on the graph. Adversarial training, which has been shown to be one of the most effective defense mechanisms against adversarial attacks in computer vision, holds great promise for enhancing the robustness of GNNs. There is limited research on defending against attacks by performing adversarial training on graphs, and it is crucial to delve deeper into this approach to optimize its effectiveness. Therefore, based on robust adversarial training on graphs, we propose a hierarchical constraint refinement framework (HC-Ref) that enhances the anti-perturbation capabilities of GNNs and downstream classifiers separately, ultimately leading to improved robustness. We propose corresponding adversarial regularization terms that are conducive to adaptively narrowing the domain gap between the normal part and the perturbation part according to the characteristics of different layers, promoting the smoothness of the predicted distribution of both parts. Moreover, existing research on graph robust adversarial training primarily concentrates on training from the standpoint of node feature perturbations and seldom takes into account alterations in the graph structure. This limitation makes it challenging to prevent attacks based on topological changes in the graph. This paper generates adversarial examples by utilizing graph structure perturbations, offering an effective approach to defend against attack methods that are based on topological changes. Extensive experiments on two real-world graph benchmarks show that HC-Ref successfully resists various attacks and has better node classification performance compared to several baseline methods.
الوصول الحر: http://arxiv.org/abs/2312.04879Test
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2دورية أكاديمية
المؤلفون: DING Yaqi, LYU Sheng, WANG Zihan, ZHANG Zhisen, LIU Weiwei, SHEN Gang
المصدر: Chengshi guidao jiaotong yanjiu, Vol 27, Iss 6, Pp 64-67 (2024)
مصطلحات موضوعية: urban rail transit, wheel set, wear model, fitting standard deviation, Transportation engineering, TA1001-1280
الوصف: Objective Based on the measured data of the train wheelsets on Shanghai Metro Line 17, the wheelset wear pattern is studied, and a wear model of wheel rim thickness and wheel diameter is established to improve the safety and maintenance efficiency of urban rail transit vehicles. Method The measured wheelset data are pre-processed to eliminate data errors. Curve fitting and error analysis method are used to establish the wear model of wheel rim thickness and wheel diameter. The fitting standard deviation of wear rate and that of the error value between the true value and the error fitting curve are used as evaluation indexes to evaluate the accuracy of the wear model. The wheelset wear model is verified with Train 1701 and Train 1721 respectively. Result & Conclusion Both the fitting standard deviation of 4th power fitting curve of wear rate for Train 1701 and Train 1721 wheelset rim thickness and wheel diameter, and that of 6th power fitting curve of the error value between the true value and the error fitting curve are close to zero, verifying that the vehicle wheelset wear model can accurately predict the wheelset wear of different types of trains and different vehicle positions of the same train on Shanghai Metro Line 17.
وصف الملف: electronic resource
العلاقة: https://doaj.org/toc/1007-869XTest
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3تقرير
المؤلفون: Shen, Gang, Ma, Mingyang, Xu, Guangxin
مصطلحات موضوعية: Computer Science - Multimedia
الوصف: To deliver ultra-high resolution 360-degree video (such as 8K, 12K, or even higher) across the internet, viewport-dependent streaming becomes necessary to save bandwidth. During viewport switches, clients and servers will instantly exchange coordination info and contents for the given viewports. However, those viewport switches pose a serious challenge for video encoding because the temporal dependency between contents within changing viewports is unpredictable. In existing practices, it is commonly noted that GOP (Group of Pictures) size in a bitstream intrinsically prohibits the reduction of the viewport switch latency, such as Motion-to-photon (MTP) latency, or motion-to-high-quality (MTHQ) latency. In this paper, we presented a Scalable Video Coding (SVC) based bitstream schema, which can structurally remove the impacts of GOP in viewport-dependent streaming and provide instant viewport switches within one-frame time (the best possible). In addition, combined with tiling, this new coding schema allows an efficient packing of the non-adjacent regions within a viewport of 360-degree video. Our experiments also show that the overall encoding with this SVC-based approach is faster than with multi-stream approaches. Compared with current 360-degree video streaming solutions based on MPEG-I OMAF, our approach is superior in terms of viewport switch latency, simplicity of viewport packing, and encoding performance.
الوصول الحر: http://arxiv.org/abs/2304.05654Test
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4رسالة جامعية
المؤلفون: Shen, Gang
المساهمون: Coules, Harry, De Luca, Flavia
الوصف: Large-amplitude cable vibrations are remarkably common in cable-stayed bridges subjected to wind and mechanical loading. This is due to low inherent damping of these structures. Although the high slenderness ratio of cables means that bending moments are not normally significant over their free length, local effects near the cable anchorage induce non-negligible bending stress variation under dynamic loading, which could lead to fatigue failure of stay cables in practical bridges. An analytical bending fatigue framework is proposed to estimate the fatigue life of low-sag cables subjected to harmonic loading. This work demonstrates that the use of a guide deviator (i.e. a device to relieve the bending moment at the anchorage) can significantly extend the cable's fatigue life. The fatigue life is greatly reduced if the cable jumps to a multi-modal dynamic response, so it is important to limit the cable response to within the single-mode zone. This can be achieved by using external damping. This framework also reveals that the dynamic response of cables under external loading is crucial for evaluating cable fatigue life more reliably. When the natural frequencies of a global vibrational mode and a cable mode are close in a cable-stayed bridge, there can be significant interactions between the cable and deck. This affects the cable's dynamic response and hence vulnerability to cable fatigue. A nonlinear cable-supported model is introduced, representing a single cable attached to the top of a deck section. Analytical solutions in the form of non-dimensional polynomial equations of the motion of the deck and cable are derived for the nonlinear system under external loading. The feedback of the cable vibration on the deck and cable response is non-negligible even for a relatively large mass ratio of the deck to cable. Therefore, for practical cable-stayed bridges the interaction between cable and deck needs to be considered to obtain an accurate dynamic response in some cases. In modern cable-stayed structures, the fatigue performance of cables depends on the fatigue properties of the individual seven-wire monostrands which together make up the cable. A new bending fatigue testing device for seven-wire monostrand was designed and manufactured. The key feature of this device is that it can control the fatigue loading in the axial and transverse directions of the cable independently. The fatigue endurance of monostrand with guide deviators is significantly longer than without guide deviators present, especially for smaller bending fatigue amplitudes. This is the intrinsic cause for the corresponding conclusion given by the dynamic framework. The bending fatigue life of monostrand is also reduced by increased constant or dynamic axial stress. Furthermore, experimental tests demonstrated that fatigue occurs due to the bending stress variation caused by the combination of bending moments and axial forces at the extreme edges of the monostrand cross-section, rather than due to relative movement and fretting between adjacent wires within the monostrand. The understanding of cable dynamics and the mechanisms of cable bending fatigue developed in this work could help designers build more efficient and more durable cable-stayed structures.
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5دورية أكاديمية
المؤلفون: Armstrong David, Shen Gang, Petocz Peter, Darendeliler M. Ali
المصدر: Australasian Orthodontic Journal, Vol 23, Iss 2, Pp 96-103 (2023)
الوصف: Well-finished orthodontic treatment begins with accurate positioning of the brackets on the teeth.
وصف الملف: electronic resource
العلاقة: https://doaj.org/toc/2207-7480Test
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6دورية أكاديمية
المؤلفون: Zhang, Zhanfei, Zhou, Jinsong, Sun, Wenjing, Thompson, David, Shen, Gang, Gong, Dao, Wang, Zegen, Wang, Tengfei, Li, Xiaoyu
الوصف: Railway vehicles are often subjected to stationary creep forces, such as those resulting from traction/braking, which can significantly affect their dynamic performance. This paper presents an analytical method to analyse the steering performance of elastically constrained wheelsets under stationary traction/braking torque. Two indices, which are independent of vehicle velocity, the ‘self-steering index’ and the ‘lateral flexibility index’, are proposed to evaluate the steering ability. The impact of traction/braking condition on the steering ability is analysed, in which the saturation characteristics of wheel-rail creep are considered. The findings confirm that stationary longitudinal creep forces, arising from traction/braking, negatively impact the steering ability of elastically constrained wheelsets. The lateral displacements are found to be larger with the same lateral external force and consequently flange contact may occur. To control the system to avoid it reaching this extreme, an optimized torque distribution strategy is proposed to minimize the impact of traction/braking on the self-steering ability. The analytical method presented in this study offers insights into the dynamics of railway vehicles under complex working conditions, facilitating further research in this field.
وصف الملف: text
العلاقة: https://eprints.soton.ac.uk/489262/1/Final_Analytical_Study_and_Evaluation_of_Self_Steering_Ability_of_Elastically_Suspended_Wheelsets_under_TractionBraking_Conditions.pdfTest; Zhang, Zhanfei, Zhou, Jinsong, Sun, Wenjing, Thompson, David, Shen, Gang, Gong, Dao, Wang, Zegen, Wang, Tengfei and Li, Xiaoyu (2024) Analytical study and evaluation of self-steering ability of elastically constrained wheelsets under traction/braking conditions. Vehicle System Dynamics. (In Press)
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7دورية أكاديمية
المؤلفون: Shen, Gang, Xia, Chengliangyi, Li, Yumei, Shen, Hua, Meng, Weizhi, Zhang, Mingwu
المصدر: Shen , G , Xia , C , Li , Y , Shen , H , Meng , W & Zhang , M 2024 , ' Traceable and Privacy-Preserving Authentication Scheme for Energy Trading in V2G Networks ' , Ieee Internet of Things Journal , vol. 11 , no. 4 , pp. 6664 - 6676 . https://doi.org/10.1109/JIOT.2023.3311800Test
مصطلحات موضوعية: Vehicle-to-grid (V2G), Authentication, Certificateless signature, Batch verification, Random oracle model (ROM), /dk/atira/pure/sustainabledevelopmentgoals/affordable_and_clean_energy, name=SDG 7 - Affordable and Clean Energy
الوصف: With the rapid popularization of electric vehicles (EVs) in modern society, vehicle-to-grid (V2G) has been widely concerned as an emerging technology. However, various privacy and security issues arise frequently in the energy interaction between EVs and the smart grid (SG), such as the lack of secure authentication and disclosure of EVs’ identity. Although many crypto-based schemes are proposed to achieve secure authentication of V2G networks, they rely on certification authority (CA) or private key generator (PKG). In response to this problem, some certificateless signature-based schemes have been proposed. Nevertheless, most of them are not suitable for V2G networks due to the high computational cost and communication overhead, and they do not consider the problem of tracking illegal signatures. Therefore, we propose a traceable and privacy-preserving authentication scheme with supporting batch verification for energy trading in V2G networks. We use the method of binary tree level traversal to quickly track EVs with illegal signatures, which can reduce computational resources. Besides, the proposed scheme is easier to be deployed in real world because of avoiding the problems of key escrow and certificate management. Finally, we conduct a comprehensive security analysis and performance evaluation regarding our scheme. We prove that our proposed scheme is secure under the random oracle model (ROM), and the experimental results illustrate that the proposed scheme has less computational cost and communication overhead as compared to the existing schemes.
وصف الملف: application/pdf
الإتاحة: https://doi.org/10.1109/JIOT.2023.3311800Test
https://orbit.dtu.dk/en/publications/0fdea88a-dc84-4754-b5e6-2a088c4ccab9Test
https://backend.orbit.dtu.dk/ws/files/337178683/Traceable_and_Privacy-Preserving_Authentication_Scheme_for_Energy_Trading_in_V2G_Networks.pdfTest -
8دورية أكاديمية
المؤلفون: Shen, Gang, Wang, Xiaolin, Yu, Jie, Bin, Yuejing, Zhong, Shan, Yang, Shengqi, Wang, Jianguo
المساهمون: Wuzhou University, University of Tasmania
المصدر: Environmental Science and Pollution Research ; ISSN 1614-7499
مصطلحات موضوعية: Health, Toxicology and Mutagenesis, Pollution, Environmental Chemistry, General Medicine
الوصف: The multitube design in the shell-and-tube type latent heat thermal energy storage (LHTES) system has received intensive attention due to its promising benefits in enhancing heat storage efficiency. In this paper, single and multi-tube shell LHTES systems were experimentally investigated. First, this study experimentally compared the thermal characteristics between a multiple-tube heat exchanger (MTHX) and a single-tube heat exchanger (STHX). The STHX’s geometrical parameters coincided with a virtual cylindrical domain in the MTHX, being similar to the single-tube model formulated by simplifying the numerical solution to investigate the MTHX. The experimental data was then used to validate the simplified numerical model commonly used in the literature that converted the multi-tube problem to a single-tube model by formulating a virtual cylindrical domain for each tube in the MTHX system. The results showed that there was a noticeable difference in the thermal characteristics between the actual STHX and the virtual cylindrical STHX domain in the MTHX system. The comparison indicated that the simplified numerical model could not accurately reflect the thermal performance of the MTHX system. An experimental study or three-dimensional numerical modelling was required for the thermal analysis of the multi-tube problems. Second, the effect of tube number in the MTHX was experimentally investigated. It was found that an increase in tube number boosted both charging and discharging rates without inhibiting the natural convection. The five-tube configuration decreased the total charging and discharging duration by 50% compared to the two-tube one. Finally, the effect of heat transfer fluid (HTF) operating parameters on the system performance was evaluated on the five-tube MTHX system. The results revealed that the adoption of higher HTF temperature considerably improved the charging performance. The charging time decreased by up to 41% with the HTF temperature increasing from 70 to 80 °C. Meanwhile, a variation ...
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9دورية أكاديمية
المؤلفون: Zhou, Jian-Guo, Yang, Jie, Wang, Haitao, Wong, Ada Hang-Heng, Tan, Fangya, Chen, Xiaofei, He, Si-Si, Shen, Gang, Wang, Yun-Jia, Frey, Benjamin, Fietkau, Rainer, Hecht, Markus, Zhong, Wenzhao, Ma, Hu, Gaipl, Udo
المساهمون: Youth Talent Project of Guizhou Provincial Department of Education, Chunhui program of the Chinese Ministry of Education, China Lung Cancer Immunotherapy Research Project, Natural Science Foundation of Guizhou Province, National Natural Science Foundation of China, Excellent Young Talent Cultivation Project of Zunyi City
المصدر: BMJ Oncology ; volume 3, issue 1, page e000128 ; ISSN 2752-7948
الوصف: Objective Fast progression (FP) represents a desperate situation for advanced non-small cell lung cancer (NSCLC) patients undergoing immune checkpoint inhibitor therapy. We aimed to develop a predictive framework based on machine learning (ML) methods to identify FP in advanced NSCLC patients using blood test biomarkers. Methods and analysis We extracted data of 1546 atezolizumab-treated patients from four multicentre clinical trials. In this study, patients from the OAK trial were taken for model training, whereas patients from the other trials were used for independent validations. The FP prediction model was developed using 21 pretreatment blood test variables in seven ML approaches. Prediction performance was evaluated by the receiver operating characteristic (ROC) curve. Results The prevalence of FP was 7.6% (118 of 1546) in all atezolizumab-treated patients. The most important variables for the prediction model were: C reactive protein, neutrophil count, lactate dehydrogenase and alanine transaminase. The Support Vector Machine (SVM) algorithm applied to these four blood test parameters demonstrated good performance: the area under the ROC curve obtained from the training cohort (OAK), validation cohort 1 (BIRCH) and cohort 2 (merged POPLAR and FIR) were 0.908, 0.666 and 0.776, respectively. In addition, the absolute difference in median survival between the SVM-predicted FP and non-FP groups was significant in both progression-free survival and overall survival (p<0.001). Conclusion SVM trained using a 4-biomarker panel has good performance in predicting the occurrence of FP regardless of programmed cell death ligand 1 expression, hence providing evidence for decision-making in single-agent atezolizumab immunotherapy for patients with advanced NSCLC.
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10دورية أكاديمية
المؤلفون: Huang, Yi, Chen, Zhijian, Shen, Gang, Fang, Shuogui, Zheng, Junjiong, Chi, Zepai, Zhang, Yuanfeng, Zou, Yitong, Gan, Qinghua, Liao, Chengxiao, Yao, Yuhui, Kong, Jianqiu, Fan, Xinxiang
المساهمون: National Natural Science Foundation of China, Science and Technology Planning Project of Guangdong Province, Guangzhou Municipal Basic Research Program Jointly Funded by City, University, and Enterprise Special Project
المصدر: Human Vaccines & Immunotherapeutics ; volume 20, issue 1 ; ISSN 2164-5515 2164-554X
النص الكامل