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Numerical study on the optimal power distribution of server racks in a data center

Building Simulation 2023年第6期16卷 983-995页

作者： MengXuan Song Kai CHEN School of Energy and Materials Shanghai Key Laboratory of Engineering Materials Application and EvaluationShanghai Polytechnic UniversityShanghai201209China Shanghai Thermophysical Properties Big Data Professional Technical Service Platform Shanghai Engineering Research Center of Advanced Thermal Functional MaterialsShanghai201209China Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou510640China

Data centers,as the infrastructure of all information services,cost tremendous amount of energy.Reducing the hot spot temperature in the data center room is benefit to prevent overheating of devices,and to increase cooling system efficiency.In this paper,we study the problem of optimal power distribution among racks for minimal hot spot temperature.The temperature rise matrix(TRM)model is used for the purpose of fast estimation of the thermal environment.The accuracy of the model is evaluated by conducting numerical simulations of computational fluid dynamics(CFD).Using the TRM model,optimal distributing of heating power is converted into a linear programming problem,which can be solved by highly efficient algorithms,such as Simplex.Furthermore,with realistic constraints including rack idle power and power upper limit,an iteration method is proposed to calculate the optimal power distribution along with the optimal on/off states of the racks.Obtained solutions are discussed and validated by comparing with CFD simulations.Results show that the TRM model is acceptable in evaluating temperature rises in the forced-convection-dominated scenarios,and the proposed method is able to obtain optimal power distributions under various levels of total power demand.

关键词： data center numerical simulation temperature rising matrix power distribution optimization

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Spindle-E is essential for gametogenesis in the silkworm, Bombyx mori

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Insect Science 2023年第2期30卷 293-304页

作者： Kai CHEN Xu Yang Dehong Yang Yongping Huang Jiangsu Key Laboratory of Sericultural Biology and Biotechnology School of BiotechnologyJiangsu University of Science and TechnologyZhenjiangJiangsu ProvinceChina Key Laboratory of Insect Developmental and Evolutionary Biology Center for Excellence in Molecular Plant SciencesShanghai Institute of Plant Physiology and EcologyChinese Academy of SciencesShanghaiChina CAS Center for Excellence in Biotic Interactions University of the Chinese Academy of SciencesBejingChina

As a defense mechanism against transposable elements,the PIWI-interacting RNA(piRNA)pathway maintains genomic integrity and ensures proper gametogenesis in gonads.Numerous factors are orchestrated to ensure normal operation of the piRNA pathway.Spindle-E(Spn-E)gene was one of the first genes shown to participate in the piRNA pathway.In this study,we performed functional analysis of Spn-E in the model lepidopteran insect,Bombyx mori.Unlike the germline-specific expression pattern observed in Drosophila and mouse,BmSpn-E was ubiquitously expressed in all tissues tested,and it was highly expressed in gonads.Immunofluorescent staining showed that BmSpn-E was localized in both germ cells and somatic cells in ovary and was expressed in spermatocytes in testis.We used a binary transgenic CRISPR/Cas9 system to construct BmSpn-E mutants.Loss of BmSpn-E expression caused derepression of transposons in gonads.We also found that mutant gonads were much smaller than wild-type gonads and that the number of germ cells was considerably lower in mutant gonads.Quantitative real-time PCR analysis and TUNEL staining revealed that apoptosis was greatly enhanced in mutant gonads.Further,we found that the BmSpn-E mutation impacted gonadal development and gametogenesis at the early larval stage.In summary,our data provided the first evidence that BmSpn-E plays vital roles in gonadal development and gametogenesis in B.mori.

关键词： Bombyx mori gametogenesis piRNA pathway Spindle-E

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SkillSim:voice apps similarity detection

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Cybersecurity 2023年第4期6卷 33-49页

作者： Zhixiu Guo Ruigang Liang Guozhu Meng Kai CHEN SKLOIS Institute of Information EngineeringChinese Academy of SciencesBeijingChina School of Cyber Security University of Chinese Academy of SciencesBeijingChina

Virtual personal assistants(VPAs),such as Amazon Alexa and Google Assistant,are software agents designed to perform tasks or provide services to individuals in response to user commands.VPAs extend their functions through third-party voice apps,thereby attracting more users to use VPA-equipped products.Previous studies demonstrate vulnerabilities in the certification,installation,and usage of these third-party voice apps.However,these studies focus on individual apps.To the best of our knowledge,there is no prior research that explores the correlations among voice apps.Voice apps represent a new type of applications that interact with users mainly through a voice user interface instead of a graphical user interface,requiring a distinct approach to analysis.In this study,we present a novel voice app similarity analysis approach to analyze voice apps in the market from a new perspective.Our approach,called SkillSim,detects similarities among voice apps(i.***.skills)based on two dimensions:text similarity and structure similarity.SkillSim measures 30,000 voice apps in the Amazon skill market and reveals that more than 25.9%have at least one other skill with a text similarity greater than 70%.Our analysis identifies several factors that contribute to a high number of similar skills,including the assistant development platforms and their limited templates.Additionally,we observe interesting phenomena,such as developers or platforms creating multiple similar skills with different accounts for purposes such as advertising.Furthermore,we also find that some assistant development platforms develop multiple similar but non-compliant skills,such as requesting user privacy in a non-compliance way,which poses a security risk.Based on the similarity analysis results,we have a deeper understanding of voice apps in the mainstream market.

关键词： Voice app Similarity analysis Skills

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Jeu de mots paronomasia:a StackOverflow‑driven bug discovery approach

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网络空间安全科学与技术(英文) 2023年第3期6卷 57-73页

作者： Yi Yang Ying Li Kai CHEN Jinghua Liu SKLOIS Institute of Information EngineeringChinese Academy of SciencesBeijingChina School of Cyber Security University of Chinese Academy of SciencesBeijingChina

Locating bug code snippets(short for BugCode)has been a complex problem throughout the history of software security,mainly because the constraints that define BugCode are obscure and hard to summarize.Previously,security analysts attempted to define such constraints manually(e.g.,limiting buffer size to detect overflow),but were limited to the types of BugCode.Recent researchers address this problem by extracting constraints from program documentation,which shows the potential for API misuse.But for bugs beyond the scope of API misuse,such an approach becomes less effective since the corresponding constraints are not defined in documents,not to mention the programs without documentation In this paper,inspired by the fact that expert programmers often correct the BugCode on open forums such as StackOverflow,we design an approach to automatically extract knowledge from StackOverflow and leverage it to detect BugCode.As we all know,the contexts in StackOverflow come from ordinary developers.Their writing tends to be loosely organized and in various styles,which are more challenging to analyze than program documentation.To address the challenges,we design a custom tokenization approach to segment sentences and employ sentiment analysis to find the Controversial Sentences(CSs)that typically contain the constraints we need for code analysis.Then we use constituency parsing to extract knowledge from CSs,which helps locate Bug-Code.We evaluated our system on 41,144 comments from the questions tagged with Java and Android.The results show that our approach achieves 95.5%precision in discovering CSs.We have discovered 276 pieces of BugCode proved to be true through manual validation including an assigned CVE.89.3%of the discovered bugs remained in the current version of answers,which are unknown to users.

关键词： Bug detection Natural language processing Open forum

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Applying blockchain-based method to smart contract classification for CPS applications

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Digital Communications and Networks 2022年第6期8卷 964-975页

作者： Zigui Jiang Kai CHEN Hailin Wen Zibin Zheng School of Software Engineering Sun Yat-Sen UniversityChina School of Mathematics Sun Yat-Sen UniversityChina School of Computer Science and Engineering Sun Yat-Sen UniversityChina

Smart contract has been the core of blockchain systems and other blockchain-based systems since Blockchain 2.0.Various operations on blockchain are performed through the invocation and execution of smart contracts.This leads to extensive combinations between blockchain,smart contract,Internet of Things(IoT)and Cyber-Physical System(CPS)applications,and then many blockchain-based IoT or CPS applications emerge to provide multiple benefits to the economy and society.In this case,obtaining a better understanding of smart contracts will contribute to the easier operation,higher efficiency and stronger security of those blockchain-based systems and applications.Many existing studies on smart contract analysis are based on similarity calculation and smart contract classification.However,smart contract is a piece of code with special characteristics and most of smart contracts are stored without any category labels,which leads to difficulties of smart contract classification.As the back end of a blockchain-based Decentralized Application(DApp)is one or several smart contracts,DApps with labeled categories and open source codes are applied to achieve a supervised smart contract classification.A three-phase approach is proposed to categorize DApps based on various data features.In this approach,5,659 DApps with smart contract source codes and pre-tagged categories are first obtained based on massive collected DApps and smart contracts from Ethereum,State of the DApps and DappRadar.Then feature extraction and construction methods are designed to form multi-feature vectors that could present the major characteristics of DApps.Finally,a fused classification model consisting of KNN,XGBoost and random forests is applied to the multi-feature vectors of all DApps for performing DApp classification.The experimental results show that the method is effective.In addition,some positive correlations between feature variables and categories,as well as several user behavior patterns of DApp calls,are found in this paper.

关键词： Blockchain Blockchain-based application Smart contract DApP classification Solidity

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The known,unknown,and unknown unknowns of cell-cell communication in planarian regeneration

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动物学研究(英文) 2023年第5期44卷 981-992页

作者： Jia-Jia chen kai Lei School of Life Sciences Zhejiang UniversityHangzhouZhejiang 310058China Westlake Laboratory of Life Sciences and Biomedicine Key Laboratory of Growth Regulation and Translational Research of Zhejiang ProvinceSchool of Life SciencesWestlake UniversityHangzhouZhejiang 310030China Institute of Biology Westlake Institute for Advanced StudyHangzhouZhejiang 310024China

Planarians represent the most primitive bilateral triploblastic animals.Most planarian species exhibit mechanisms for whole-body regeneration,exemplified by the regeneration of their cephalic ganglion after complete excision.Given their robust whole-body regeneration capacity,planarians have been model organisms in regenerative research for more than 240 years.Advancements in research tools and techniques have progressively elucidated the mechanisms underlying planarian regeneration.Accurate cell-cell communication is recognized as a fundamental requirement for regeneration.In recent decades,mechanisms associated with such communication have been revealed at the cellular level.Notably,stem cells(neoblasts)have been identified as the source of all new cells during planarian homeostasis and regeneration.The interplay between neoblasts and somatic cells affects the identities and proportions of various tissues during homeostasis and regeneration.Here,this review outlines key discoveries regarding communication between stem cell compartments and other cell types in planarians,as well as the impact of communication on planarian regeneration.Additionally,this review discusses the challenges and potential directions of future planarian research,emphasizing the sustained impact of this field on our understanding of animal regeneration.

关键词： Planarians Stem cells Regeneration Cell communication

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MSSSA:a multi-strategy enhanced sparrow search algorithm for global optimization

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Frontiers of Information Technology & Electronic Engineering 2022年第12期23卷 1828-1847页

作者： kai MENG chen chen Bin XIN School of Automation Beijing Institute of TechnologyBeijing 100081China State Key Laboratory of Intelligent Control and Decision of Compler Systems Beijing 100081China

The sparrow search algorithm(SSA) is a recent meta-heuristic optimization approach with the advantages of simplicity and flexibility. However, SSA still faces challenges of premature convergence and imbalance between exploration and exploitation, especially when tackling multimodal optimization problems. Aiming to deal with the above problems, we propose an enhanced variant of SSA called the multi-strategy enhanced sparrow search algorithm(MSSSA) in this paper. First, a chaotic map is introduced to obtain a high-quality initial population for SSA, and the opposition-based learning strategy is employed to increase the population diversity. Then, an adaptive parameter control strategy is designed to accommodate an adequate balance between exploration and exploitation. Finally, a hybrid disturbance mechanism is embedded in the individual update stage to avoid falling into local optima. To validate the effectiveness of the proposed MSSSA, a large number of experiments are implemented, including 40 complex functions from the IEEE CEC2014 and IEEE CEC2019 test suites and 10 classical functions with different dimensions. Experimental results show that the MSSSA achieves competitive performance compared with several state-of-the-art optimization algorithms. The proposed MSSSA is also successfully applied to solve two engineering optimization problems. The results demonstrate the superiority of the MSSSA in addressing practical problems.

关键词： Swarm intelligence Sparrow search algorithm Adaptive parameter control strategy Hybrid disturbance mechanism Optimization problems

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Rapidly modifying microstructure and mechanical properties of AA7150 Al alloy processed with electropulsing treatment

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Journal of Materials Science & Technology 2021年第36期95卷 172-179页

作者： Kai CHEN Lihua Zhan Wenfang Yu College of Mechanical and Electrical Engineering of Central South University Changsha 410083China State Key Laboratory of High-Performance Complex Manufacturing Central South UniversityChangsha 410083China Light Alloy Research Institute of Central South University Changsha 410083China

Studies show that the proper solid solution treatment(SST)is a key step in the precipitation strengthening of AA7150 Al alloy.Despite the superior characteristics of the fully dissolved phase,it has major drawbacks,including high consumption of energy and low efficiency.Recently,electropulsing treatment(EPT)has been proposed to study dissolved precipitations and modify microstructures of AA7150 Al alloy faster than conventional SST.Experiments have been conducted in the present article,and the obtained results show that EPT can promote the rapid dissolution of theη’phase at relatively low temperatures in only 20 s.Meanwhile,the strength and ductility of electropulsed samples decrease drastically.Compared with conventional SST,EPT accelerates recrystallization and obtains relatively fine grains after 20 and 50 s electric pulses.Moreover,as the EPT time increases,the corresponding non-uniform local heating and the electron force promote dislocation generation and annihilation.

关键词： AA7150 Al alloy Electropulsing treatment Rapid dissolution Recrystallization Dislocation

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Numerical study on turbulent mixed convection in a vertical plane channel using hybrid RANS/LES and LES models

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Chinese Journal of Chemical Engineering 2020年第1期28卷 1-8页

作者： Puxian Ding Shuangfeng Wang Kai CHEN Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education School of Chemistry and Chemical EngineeringSouth China University of TechnologyGuangzhou 510640China

Two Delayed-Detached Eddy Simulation(DDES) models, and a Large-Eddy Simulation(LES) model are used to investigate the turbulent flows and mixed convection between a hot plate and a cold plate via the software FLUENT. The two DDES models include Production-limited DDES(PL-DDES) and Improved DDES(IDDES) models.The Wall-Adapting Local Eddy-Viscosity(WALE) model is the used LES model. The numerical computations are performed at Reynolds number Reb= 4494 and different Richardson numbers Ri = 0.025, 0.048, 0.1. The comparing data is from the Direct Numerical Simulation(DNS) at Reb= 4494 and Ri = 0.048. The comparison reveals that the two DDES models have better performance in predicting time-averaged parameters than the WALE model in the aiding flow. The best predicted time-averaged results are obtained by the PL-DDES model in the opposing flow. Furthermore, the results of different Ri obtained by the PL-DDES model agree well with the DNS data.

关键词： Turbulent mixed convection Hybrid RANS/LES model PL-DDES model WALE model Vertical plane channel

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Chronic Kidney Disease Induces Cognitive Impairment in the Early Stage

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Current Medical Science 2023年第5期43卷 988-997页

作者： Yu WANG Kai CHEN Zi-xuan QIAO Xiao-rong BAO Department of Nephrology Jinshan HospitalFudan UniversityShanghai 201508China

Objective Previous research indicates a link between cognitive impairment and chronic kidney disease(CKD),but the underlying factors are not fully understood.This study aimed to investigate the progression of CKD-induced cognitive impairment and the involvement of cognition-related proteins by developing early-and late-stage CKD models in Sprague-Dawley rats.Methods The Morris water maze test and the step-down passive avoidance task were performed to evaluate the cognitive abilities of the rats at 24 weeks after surgery.Histopathologic examinations were conducted to examine renal and hippocampal damage.Real-time PCR,Western blotting analysis,and immunohistochemical staining were carried out to determine the hippocampal expression of brain-derived neurotrophic factor(BDNF),choline acetyltransferase(ChAT),and synaptophysin(SYP).Results Compared with the control rats,the rats with early-stage CKD exhibited mild renal damage,while those with late-stage CKD showed significantly increased serum creatinine levels as well as apparent renal and brain damage.The rats with early-stage CKD also demonstrated significantly impaired learning abilities and memory compared with the control rats,with further deterioration observed in the rats with late-stage CKD.Additionally,we observed a significant downregulation of cognition-related proteins in the hippocampus of rats with early-stage CKD,which was further exacerbated with declining renal function as well as worsening brain and renal damage in rats with late-stage CKD.Conclusion These results suggest the importance of early screening to identify CKD-induced cognitive dysfunction promptly.In addition,the downregulation of cognition-related proteins may play a role in the progression of cognitive dysfunction.

关键词： chronic kidney disease cognitive impairment Morris water maze test brain-derived neurotrophic factor choline acetyltransferase synaptophysin

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