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Application of GNSS-PPP on Dynamic Deformation Monitoring of Offshore Platforms

China Ocean Engineering 2024年第2期38卷 352-361页

作者： yu li-na XIONG Kuan GAO Xi-feng li Zhi FAN li-long ZHANG Kai Institute of Ocean Energy and Intelligent Construction Tianjin University of TechnologyTianjin 300384China China Railway Construction Bridge Engineering Bureau Group Co.LTD Tianjin 300300China School of Civil Engineering Tianjin UniversityTianjin 300072China Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong KongChina State Key Laboratory of Precision Blasting Jianghan UniversityWuhan 430056China

The real-time dynamic deformation monitoring of offshore platforms under environmental excitation is crucial to their safe *** Global Navigation Satellite System-Precise Point Positioning(GNSS-PPP)has been considered for this purpose,its monitoring accuracy is relatively ***,the influence of background noise on the dynamic monitoring accuracy of GNSS-PPP remains ***,it is imperative to further validate the feasibility of GNSS-PPP for deformation monitoring of offshore *** address these concerns,vibration table tests with different amplitudes and frequencies are *** results demonstrate that GNSS-PPP can effectively monitor horizontal vibration displacement as low as±30 mm,which is consistent with ***,the spectral characteristic of background noise in GNSS-PPP is similar to that of GNSS-RTK(Real Time Kinematic).Building on this observation,an improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)has been proposed to de-noise the data and enhance the dynamic monitoring accuracy of *** monitoring application research is also undertaken,successfully extracting and analyzing the dynamic deformation of an offshore platform structure under environmental excitation using GNSS-PPP monitoring in conjunction with improved CEEMDAN *** comparing the de-noised dynamic deformation trajectories of the offshore platform during different periods,it is observed that the platform exhibits reversible alternating vibration responses under environmental excitation,with more pronounced displacement deformation in the direction of load *** research results confirm the feasibility and potential of GNSS-PPP for dynamic deformation monitoring of offshore platforms.

关键词： GNSS-PPP offshore platform dynamic deformation monitoring improved CEEMDAN de-noising

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Diophantine equations and Fermat's last theorem for multivariate(skew-)polynomials

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 159-173页

作者： PAN Jie JIA yu-ming li Fang School of Mathematical Sciences Zhejiang UniversityHangzhou 310058China Henan Experimental High School Zhengzhou 450003China

Fermat’s Last Theorem is a famous theorem in number theory which is diﬃcult to ***,it is known that the version of polynomials with one variable of Fermat’s Last Theorem over C can be proved very *** aim of this paper is to study the similar problems about Fermat’s Last Theorem for multivariate(skew)-polynomials with any characteristic.

关键词： Fermat's last theorem polynomial ring skew polynomial ring

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Multi-physical fields distribution in billet during helical electromagnetic stirring:A numerical simulation research

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China Foundry 2024年第1期21卷 51-59页

作者： Dong Pan Qing-tao Guo Kai-lun Zhang Fu-zhi yu yu-ying li yu-bao Xiao State Key Laboratory of Metal Materials for Marine Equipment and Application Anshan 114009LiaoningChina Ansteel Beijing Research Institute Co. Ltd.Beijing 102200China

Electromagnetic stirring is one of the widely applied techniques to modify the quality of casting *** from conventional rotate stirring,the helical stirring is more professional in assisting multi-dimensional flow of molten metal and eliminating solidification *** this study,the single-winding helical stirring(SWHS)was introduced,offering advantages such as smaller volume and lower electromagnetic shielding compared to traditional helical stirring *** a comprehensive numerical simulation,the stirring parameters of SWHS were adjusted to yoke inclination angle of 43°and frequency of 12.*** higher electromagnetic force and flow velocity in drawing direction,as well as the lower temperature gradient induced by the SWHS,are positive factors for homogeneous solidification of *** experimental results on Al-8%Si alloy and 0.4%C-1.1%Mn steel demonstrate that compared to rotate stirring,the SWHS process can induce better billet quality and is more effective in accelerating the equiaxed expansion and reducing element *** SWHS process can enhance the equiaxed ratio of the billet by 58.3%and reduce segregation degree of carbon element by 10.97%.Consequently,SWHS holds great promise as a potential approach for improving the quality of continuous casting billets.

关键词： billet electromagnetic stirring helical solidification element segregation numerical simulation

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Construction technology for deep tunnels crossing superhigh-temperature fault zones with high water surges

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Frontiers of Structural and Civil Engineering 2024年第8期18卷 1267-1280页

作者： Yong ZHAO Tingyu ZHU li yu Ming LU Sichuan–Xizang Railway Co. Ltd.Linzhi 860000China School of Civil Engineering Southwest Jiaotong UniversityChengdu 610036China

The harsh environment in tunnels with high geothermal temperatures and humidity can adversely impact machinery,personnel,and *** main causes of specific problems are the unknown mechanisms of local geothermal formation,inappropriate temperature control measures,and insufficient systematic *** this study,three work sections relating to a high geothermal tunnel are:the tunnel face,middle-of-tunnel section,and outside-oftunnel section.A cooling strategy is proposed to offer technical support in achieving comprehensive cooling,overall as well as for each of the ***,a comprehensive geological survey explores the mechanism and exact location of the heat ***,grouting and centralized drainage measures are used to control the heat release of hot *** ventilation,ice chillers and other applicable measures are used to control the ambient ***,a monitoring and early warning system is established to prevent *** cooling strategy has been applied in the field with good results.

关键词： high geothermal tunnels cooling strategy comprehensive cooling measures safety and security

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Hard carbon for sodium storage:Mechanism and performance optimization

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Nano Research 2024年第7期17卷 6038-6057页

作者： Yongxin Wang Meng li yu Zhang Naiqing Zhang State Key Laboratory of Urban Water Resource and Environment School of Chemistry and Chemical EngineeringHarbin Institute of TechnologyHarbin 150001China School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Due to the shortage of lithium resource reserves and the pressure of rising prices,sodium-ion batteries have regained the attention of the public,and shown great potential for application in the fields of grid energy storage and low-speed vehicles to achieve the purpose of complementing lithium-ion batteries,so it is imperative to promote the commercial application of sodiumion *** sodium-ion battery anode materials,hard carbon is the material most likely to be used ***,there is still much work to be done before its *** review provides a comprehensive overview of the current research status from the following three ***,the microstructure and sodium storage active sites of hard carbon are ***,the mechanism of sodium storage in hard carbon is investigated,which can be broadly categorized into four model,“insertion–filling”,“adsorption–insertion”,“adsorption–filling”,and“multistage”.Finally,from the perspective of improving the electrochemical performance of hard carbon,the performance improvement strategies proposed in recent years are *** with the performance of hard carbon commercial products of some enterprises,the future development goal of hard carbon is prospected,hoping that all sectors of society can work hard for this common goal.

关键词： sodium-ion battery hard carbon mechanism performance optimization

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Key processes of carbon cycle and sink enhancement paths in natural wetland ecosystems in China

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Science China Earth Sciences 2024年第8期67卷 2444-2459页

作者： Jinshuai li Tianxiang HAO Meng YANG Guirui yu Key Laboratory of Ecosystem Network Observation and Modeling Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

Wetland ecosystems have become one of the long-term solutions for mitigating global climate change due to their strong carbon sequestration ***,the key carbon cycle processes in wetland ecosystems still lack a systematic *** the context of wetland protection and restoration,there is still a lack of consensus on the technical pathways to realize carbon sink multiplication in wetland *** this paper,the key processes of carbon cycle,such as photosynthetic carbon uptake,microbial carbon decomposition and carbon deposition and burial,are sorted out and summarized in four major wetland types,namely,swamp and peat wetlands,river and riparian wetlands,lake and lakeshore wetlands,and estuarine and coastal *** on the key processes of carbon cycle,three technological pathways for carbon sink multiplication are proposed,including,vegetation carbon sequestration and sink enhancement technology,soil carbon emission reduction technology and carbon deposition and burial *** key technologies under each pathway are further *** the carbon sink effects of the carbon sink technologies in different wetland types are qualitatively ***,wetland protection and restoration methods in corresponding regions are given in the light of the regional characteristics of wetlands in *** will provide a scientific basis for the strategy of doubling the carbon sinks of China′s wetland ecosystems.

关键词： Wetlands Carbon cycle Carbon sinks Technology pathways Conservation and restoration

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A deep learning model enabled multi-event recognition for distributed optical fiber sensing

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Science China(Information Sciences) 2024年第3期67卷 291-307页

作者： yujiao li Xiaomin CAO Wenhao NI Kuanglu yu Institute of Information Science School of Computer and Information TechnologyBeijing Jiaotong University Beijing Key Laboratory of Advanced Information Science and Network Technology Beijing Jiaotong University

Fiber optic sensors that utilize backscattered light offer distributed real-time measurements and have been seen tremendous improvements in sensing distance and spatial resolution over the last ***, these improvements in sensor capabilities lead to a significant increase in the amount of data that needs to be processed. Traditional processing schemes are no longer adequate, so the development of novel signal processing methods is critical. Phase-sensitive optical time domain reflectometry(Φ-OTDR) is now applied in various applications for multi-event recognition, and it would usually be difficult, sometimes even unrealistic to label all the acquired samples due to its real-time and seamless monitoring nature. To fully take advantage of the information contained within the large number of unlabeled samples, which were formerly not utilized and hence wasted, we propose a semi-supervised model to boost the event classification performance of Φ-OTDR. The model extracts respectively the temporal features and the spatial bidirectional features together with a dual attention mechanism. Its classification accuracy has been improved up to 96.9%with only 12.0 labeled samples. In addition, our model shows significant advantages when the number of labeled samples is reduced. Importantly, our method improves the accuracy of multi-event classification without any modification to the optical setup.

关键词： $\Phi$-OTDR event recognition semi-supervised learning mean teacher MT-ACNN-SA-BiLSTM

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Developing ChatGPT for biology and medicine: a complete review of biomedical question answering

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Biophysics Reports 2024年第3期10卷 152-171页

作者： Qing li Lei li yu li Department of Computer Science and Engineering the Chinese University of Hong Kong

ChatGPT explores a strategic blueprint of question answering(QA) to deliver medical diagnoses, treatment recommendations, and other healthcare support. This is achieved through the increasing incorporation of medical domain data via natural language processing(NLP) and multimodal paradigms. By transitioning the distribution of text, images, videos, and other modalities from the general domain to the medical domain, these techniques have accelerated the progress of medical domain question answering(MDQA). They bridge the gap between human natural language and sophisticated medical domain knowledge or expert-provided manual annotations, handling large-scale, diverse, unbalanced, or even unlabeled data analysis scenarios in medical contexts. Central to our focus is the utilization of language models and multimodal paradigms for medical question answering, aiming to guide the research community in selecting appropriate mechanisms for their specific medical research *** tasks such as unimodal-related question answering, reading comprehension, reasoning, diagnosis, relation extraction, probability modeling, and others, as well as multimodal-related tasks like vision question answering, image captioning, cross-modal retrieval, report summarization, and generation, are discussed in detail. Each section delves into the intricate specifics of the respective method under consideration. This paper highlights the structures and advancements of medical domain explorations against general domain methods, emphasizing their applications across different tasks and datasets. It also outlines current challenges and opportunities for future medical domain research,paving the way for continued innovation and application in this rapidly evolving field. This comprehensive review serves not only as an academic resource but also delineates the course for future probes and utilization in the field of medical question answering.

关键词： ChatGPT Medical question answering Nature language processing Multimodal paradigms Large language models

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De-biased knowledge distillation framework based on knowledge infusion and label de-biasing techniques

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Journal of Electronic Science and Technology 2024年第3期22卷 57-68页

作者： Yan li Tai-Kang Tian Meng-yu Zhuang yu-Ting Sun School of Economics and Management University of Electronic Science and Technology of ChinaChengdu611731China School of Economics and Management Beijing University of Posts and TelecommunicationBeijing100876China School of Electrical Engineering and Computer Science The University of QueenslandBrisbane4072Australia

Knowledge distillation,as a pivotal technique in the field of model compression,has been widely applied across various ***,the problem of student model performance being limited due to inherent biases in the teacher model during the distillation process still *** address the inherent biases in knowledge distillation,we propose a de-biased knowledge distillation framework tailored for binary classification *** the pre-trained teacher model,biases in the soft labels are mitigated through knowledge infusion and label de-biasing *** on this,a de-biased distillation loss is introduced,allowing the de-biased labels to replace the soft labels as the fitting target for the student *** approach enables the student model to learn from the corrected model information,achieving high-performance deployment on lightweight student *** conducted on multiple real-world datasets demonstrate that deep learning models compressed under the de-biased knowledge distillation framework significantly outperform traditional response-based and feature-based knowledge distillation models across various evaluation metrics,highlighting the effectiveness and superiority of the de-biased knowledge distillation framework in model compression.

关键词： De-biasing Deep learning Knowledge distillation Model compression

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A comprehensive review on microchannel heat sinks for electronics cooling

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International Journal of Extreme Manufacturing 2024年第2期6卷 133-162页

作者： Zhi-Qiang yu Mo-Tong li Bing-Yang Cao Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

The heat generation of electronic devices is increasing dramatically,which causes a serious bottleneck in the thermal management of electronics,and overheating will result in performance deterioration and even device *** the development of micro-machining technologies,the microchannel heat sink(MCHS)has become one of the best ways to remove the considerable amount of heat generated by high-power *** has the advantages of large specific surface area,small size,coolant saving and high heat transfer *** paper comprehensively takes an overview of the research progress in MCHSs and generalizes the hotspots and bottlenecks of this *** heat transfer mechanisms and performances of different channel structures,coolants,channel materials and some other influencing factors are ***,this paper classifies the heat transfer enhancement technology and reviews the related studies on both the single-phase and phase-change flow and heat *** comprehensive review is expected to provide a theoretical reference and technical guidance for further research and application of MCHSs in the future.

关键词： microchannel heat sink thermal management of electronics microscale heat transfer heat transfer enhancement

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