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NONMONOTONE LOCAL MINIMAX METHODS FOR FINDING MULTIPLE SADDLE POINTS

Journal of Computational Mathematics 2024年第3期42卷 851-884页

作者： Wei Liu Ziqing xie Wenfan Yi South China Research Center for Applied Mathematics and Interdisciplinary Studies South China Normal UniversityGuangzhou 510631China Key Laboratory of Computing and Stochastic Mathematics(Ministry of Education) Hunan Normal UniversityChangshaHunan 410081China Hunan Provincial Key Laboratory of Intelligent Information Processing and Applied Mathematics School of MathematicsHunan UniversityChangshaHunan 410082China

In this paper,by designing a normalized nonmonotone search strategy with the BarzilaiBorwein-type step-size,a novel local minimax method(LMM),which is a globally convergent iterative method,is proposed and analyzed to find multiple(unstable)saddle points of nonconvex functionals in Hilbert *** to traditional LMMs with monotone search strategies,this approach,which does not require strict decrease of the objective functional value at each iterative step,is observed to converge faster with less ***,based on a normalized iterative scheme coupled with a local peak selection that pulls the iterative point back onto the solution submanifold,by generalizing the Zhang-Hager(ZH)search strategy in the optimization theory to the LMM framework,a kind of normalized ZH-type nonmonotone step-size search strategy is introduced,and then a novel nonmonotone LMM is *** feasibility and global convergence results are rigorously carried out under the relaxation of the monotonicity for the functional at the iterative ***,in order to speed up the convergence of the nonmonotone LMM,a globally convergent Barzilai-Borwein-type LMM(GBBLMM)is presented by explicitly constructing the Barzilai-Borwein-type step-size as a trial step-size of the normalized ZH-type nonmonotone step-size search strategy in each ***,the GBBLMM algorithm is implemented to find multiple unstable solutions of two classes of semilinear elliptic boundary value problems with variational structures:one is the semilinear elliptic equations with the homogeneous Dirichlet boundary condition and another is the linear elliptic equations with semilinear Neumann boundary *** numerical results indicate that our approach is very effective and speeds up the LMMs significantly.

关键词： Multiple saddle points Local minimax method Barzilai-Borwein gradient method Normalized nonmonotone search strategy Global convergence

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IRE1α regulates the PTHrP-IHH feedback loop to orchestrate chondrocyte hypertrophy and cartilage mineralization

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Genes & Diseases 2024年第1期11卷 464-478页

作者： Mengtian Fan Nana Geng Xingyue Li Danyang Yin Yuyou Yang Rong Jiang Cheng Chen Naibo Feng Li Liang Xiaoli Li Fengtao Luo Huabing Qi Qiaoyan tan Yangli xie Fengjin Guo Laboratory of Developmental Biology Department of Cell Biology and GeneticsSchool of Basic Medical ScienceChongqing Medical UniversityChongqing 400016China Laboratory of Stem Cells and Tissue Engineering School of Basic Medical ScienceChongqing Medical UniversityChongqing 400016China Department of Orthopedics The 1st Affiliated Hospital of Chongqing Medical UniversityChongqing 400016China Department of Wound Repair and Rehabilitation Medicine State Key Laboratory of TraumaBurns and Combined InjuryTrauma CenterResearch Institute of SurgeryDaping HospitalArmy Medical UniversityChongqing 400042China

Cartilage development is controlled by the highly synergistic proliferation and differentiation of growth plate chondrocytes,in which the Indian hedgehog(IHH)and parathyroid hormone-related protein-parathyroid hormone-1 receptor(PTHrP-PTH1R)feedback loop is *** inositol-requiring enzyme 1a/X-box-binding protein-1 spliced(IRE1α/XBP1s)branch of the unfolded protein response(UPR)is essential for normal cartilage ***,the precise role of ER stress effector IRE1α,encoded by endoplasmic reticulum to nucleus signaling 1(ERN1),in skeletal development remains ***,we reported that loss of IRE1α accelerates chondrocyte hypertrophy and promotes endochondral bone ***1 acts as a negative regulator of chondrocyte proliferation and differentiation in postnatal growth *** deficiency interrupted PTHrP/PTH1R and IHH homeostasis leading to impaired chondrocyte hypertrophy and ***1s,produced by p-IRE1α-mediated splicing,binds and up-regulates PTH1R and IHH,which coordinate cartilage ***,ER stress cannot be activated normally in ERN1-deficient *** conclusion,ERN1 deficiency accelerates chondrocyte hypertrophy and cartilage mineralization by impairing the homeostasis of the IHH and PTHrP/PTH1R feedback loop and ER ***1 may have a potential role as a new target for cartilage growth and maturation.

关键词： Cartilage development ER stress ERN1 IHH PTHrP/PTH1R

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Why Are Arctic Sea Ice Concentration in September and Its Interannual Variability Well Predicted over the Barents–East Siberian Seas by CFSv2?

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Journal of Meteorological Research 2024年第1期38卷 53-68页

作者： Yifan xie Ke FAN Hongqing YANG School of Atmospheric Sciences Sun Yat-sen Universityand Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082

To further understand the prediction skill for the interannual variability of the sea ice concentration(SIC)in specific regions of the Arctic,this paper evaluates the NCEP Climate Forecast System version 2(CFSv2),in predicting the autumn SIC and its interannual variability over the Barents–East Siberian Seas(BES).It is found that CFSv2 presents much better prediction skill for the September SIC over BES than the Arctic as a whole at 1–6-month leads,and high prediction skill for the interannual variability of the SIC over BES is displayed at 1–2-month leads after removing the linear ***2 can reasonably reproduce the relationship between the SIC over BES in September and such factors as the surface air temperature(SAT),200-hPa geopotential height,sea surface temperature(SST),and North Atlantic *** addition,it is found that the prescribed SIC initial condition in August as an input to CFSv2 is also ***,the above atmospheric and oceanic factors,as well as an accurate initial condition of SIC,all contribute to a high prediction skill for SIC over BES in *** on a statistical prediction method,the contributions from individual predictability sources are further *** high prediction skill of CFSv2 for the interannual variability of SIC over BES is largely attributable to its accurate predictions of the SAT and SST,as well as a better initial condition of SIC.

关键词： sea ice concentration the Barents-East Siberian Seas Climate Forecast System version 2(CFSv2) prediction skill predictability source atmospheric and oceanic factors initial condition

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One more step to realistic CO_(2) reduction reactions——geometric structures evolutions at gas-solid interface

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Rare Metals 2024年第2期43卷 849-852页

作者： Ya-Qiang xie Xin Yu Ting Wang College of the Environment and Ecology Xiamen UniversityXiamen361102China

A rational design of copper(Cu)nanocatalyst is critical to the efficient carbon dioxide(CO_(2))conversion toward C1/C2 chemical ***,the lack of actual information on the vicinal Cu interfaces hinders the intrinsic activitystructure correlation *** with atomic-scale in situ characterizations(AP-STM and synchrotron-based AP-XPS),Park and co-workers study and identify the adsorbate-driven morphological evolution of Cu nanoclusters on the Cu(997)surface,providing real-space evidence for the critical role of vicinal structures on Cu *** observed surface roughening trends caused by dissociated atomic oxygen and CO adsorbates subsequently affect the result of successive catalytic reactions to produce critical intermediates,such as carbonate and formate,during the CO_(2)reduction reaction.

关键词： reaction critical rational

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A brief review on the recent development of phonon engineering and manipulation at nanoscales

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International Journal of Extreme Manufacturing 2024年第1期6卷 177-206页

作者： Siqi xie Hongxin Zhu Xing Zhang Haidong Wang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua UniversityBeijing 100084People’s Republic of China

Phonons are the quantum mechanical descriptions of vibrational modes that manifest themselves in many physical properties of condensed matter systems. As the size of electronic devices continues to decrease below mean free paths of acoustic phonons, the engineering of phonon spectra at the nanoscale becomes an important topic. Phonon manipulation allows for active control and management of heat fow, enabling functions such as regulated heat transport. At the same time, phonon transmission, as a novel signal transmission method, holds great potential to revolutionize modern industry like microelectronics technology, and boasts wide-ranging applications. Unlike fermions such as electrons, polarity regulation is difficult to act on phonons as bosons, making the development of effective phonon modulation methods a daunting *** work reviews the development of phonon engineering and strategies of phonon manipulation at different scales, reports the latest research progress of nanophononic devices such as thermal rectifiers, thermal transistors, thermal memories, and thermoelectric devices,and analyzes the phonon transport mechanisms involved. Lastly, we survey feasible perspectives and research directions of phonon engineering. Thermoelectric analogies, external field regulation, and acousto-optic co-optimization are expected to become future research hotspots.

关键词： phonon engineering phononic device nanoscale

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Tailoring MXene Thickness and Functionalization for Enhanced Room‑Temperature Trace NO_(2) Sensing

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Nano-Micro Letters 2024年第5期16卷 71-86页

作者： Muhammad Hilal Woochul Yang Yongha Hwang Wanfeng xie Department of Physics Dongguk UniversitySeoul 04620Republic of Korea Department of Control and Instrumentation Engineering Korea UniversitySejong 30019Republic of Korea School of Electronics&Information University‑Industry Joint Center for Ocean Observation and Broadband CommunicationQingdao UniversityQingdao 266071China

In this study,precise control over the thickness and termination of Ti3C2TX MXene flakes is achieved to enhance their electrical properties,environmental stability,and gas-sensing *** a hybrid method involving high-pressure processing,stirring,and immiscible solutions,sub-100 nm MXene flake thickness is achieved within the MXene film on the *** control is achieved by defunctionalizing MXene at 650℃ under vacuum and H2 gas in a CVD furnace,followed by refunctionalization with iodine and bromine vaporization from a bubbler attached to the ***,the introduction of iodine,which has a larger atomic size,lower electronegativity,reduce shielding effect,and lower hydrophilicity(contact angle:99°),profoundly affecting *** improves the surface area(36.2 cm^(2) g^(-1)),oxidation stability in aqueous/ambient environments(21 days/80 days),and film conductivity(749 S m^(-1)).Additionally,it significantly enhances the gas-sensing performance,including the sensitivity(0.1119Ωppm^(-1)),response(0.2% and 23%to 50 ppb and 200 ppm NO_(2)),and response/recovery times(90/100 s).The reduced shielding effect of the–I-terminals and the metallic characteristics of MXene enhance the selectivity of I-MXene toward *** approach paves the way for the development of stable and high-performance gas-sensing two-dimensional materials with promising prospects for future studies.

关键词： Controlled MXene thickness Gaseous functionalization approach Lower electronegativity functional groups Enhanced MXene stability Trace NO_(2)sensing

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Customer Joining Behavior and Regulation Strategy in Visible Multi-Server Queues with Synchronous Vacations of Partial Servers

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Journal of Systems Science & Complexity 2024年第3期37卷 1209-1232页

作者： SUN Wei WANG Hao xie Xumeng LI Shiyong School of Economics and Management Yanshan UniversityQinhuangdao 066004China

This paper studies customer joining behavior and system regulation strategy in nonexhaustive visible M/M/m queues with synchronous vacations of a part of the *** this part of the servers are idle,they take multiple vacations simultaneously(vacation period).Until there are customers waiting in the queue,they are reactivated and all servers are busy or idle(busy period).The authors call this part of the servers as“partial servers”.In view of the fully visible queue and the almost visible queue,the authors obtain customers’equilibrium joining threshold strategies and their socially optimal joining threshold strategies,respectively,and observe that customer joining behavior in equilibrium generally makes the system overcrowded,which makes the equilibrium social welfare lower than the optimal social *** regulation,interestingly,for optimizing social welfare,the system manager hopes not only customers arriving in vacation period pay attention to the number of partial servers,but also customers arriving in busy period should care about it rather than ***,arranging more servers for vacation does not necessarily lead to the decrease of social welfare on condition that the number of partial servers is close to *** for the information advantage of the fully visible case,it is not obvious for increasing social welfare and even unfavorable to servers’profit unless the number of partial servers is big ***,given the different composition of social welfare,there exists the optimal number of partial servers and the optimal arrival rate of customers for maximizing social welfare.

关键词： Customer behavior non-exhaustive service partial servers regulation strategy synchronous vacations visible queue

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In-situ powder mixing for laser-based directed energy deposition of functionally graded materials

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Advances in Manufacturing 2024年第1期12卷 150-166页

作者： Ji-Peng Chen Shou-Chun xie He Huang School of Mechanical and Electronic Engineering Nanjing Forestry UniversityNanjing210037People’s Republic of China Nanjing Huirui Photoelectric Technology Co. LtdNanjing211121People’s Republic of China

The mixing of powders is a highly relevant field under additive manufacturing,however,it has attracted limited interest to *** in-situ mixing of various powders remains a significant *** paper proposes a new method utilizing a static mixer for the in-situ mixing of multiple powders through the laser-based directed energy deposition(DED)of functionally graded ***,a powder-mixing experimental platform was established;WC and 316L powders were selected for the mixing ***,scanning electron microscopy,energy dispersive spectroscopy,and image processing were used to visually evaluate the homogeneity and proportion of the in-situ mixed ***,powder-mixing simulations were conducted to determine the powder-mixing *** the simulations,a powder carrier gas flow field and particle mixing were ***,a WC/316L metal matrix composite sample was produced using laser-based DED to verify the application potential of the static *** was found that the static mixer could adjust the powder ratio online,and a response time of 1–2 s should be considered when adjusting the ratio of the mixed powder.A feasible approach for in-situ powder mixing for laser-based DED was demonstrated and investigated,creating the basis for functionally graded materials.

关键词： Laser Deposition Static mixer Powder mixing Functionally graded materials

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Investigation on the influence of vortex generator on particle resuspension

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Particuology 2024年第3期86卷 126-136页

作者： Dongchi Yu Jun-Li Lin Jin-Han xie ASML 80W Tasman DrSan Jose95134CaliforniaUSA Department of Mechanics and Engineering Science at College of Engineering and State Key Laboratory for Turbulence and Complex Systems Peking UniversityBeijing100081China

The vortex generator(VG)and its well-known effect in flow optimization are widely studied and employed across different engineering ***,while the same working principles of VG may be well suited for the applications on surface-cleaning technologies,such promising potential is hardly,if any,explored in the published ***,in the present study,the influence on flow-induced particle resuspension brought by a rectangular vG in a channel flow is investigated with the help of highfidelity computational fluid dynamics *** increases of particle removal forces and resuspension rates are discovered in long,strip-like regions with reduced boundary-layer thickness resulted from the vG-induced vortices,and the enhancement effect is especially significant for configurations with the VG installed at a greater angle of *** is also shown that while the resuspension enhancements on the lower and the upper surfaces of the channel exhibit distinct statistical characteristics,having a VG in the channel improves the overall particle-removing capability of the channel flow by introducing higher surface-averaged removal forces and particle resuspension *** but not least,the increase of resuspension rate is especially significant for the smaller,micron-scale particles which are otherwise hardly disturbed by a VG-less channel flow,and such resuspension-enhancement effectgenerally subsides with increasing particle size.

关键词： Particle resuspension Vortexgenerator CFD Surface cleaning

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QoE oriented intelligent online learning evaluation technology in B5G scenario

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Digital Communications and Networks 2024年第1期10卷 7-15页

作者： Mingzi Chen Xin Wei Peizhong xie Zhe Zhang School of Communications and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing210003China Key Lab of Broadband Wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications) Ministry of EducationNanjing210003China Institute of Higher Education Nanjing University of Posts and TelecommunicationsNanjing210003China

Students'demand for online learning has exploded during the post-COvID-19 pandemic ***,due to their poor learning experience,students'dropout rate and learning performance of online learning are not always *** technical advantages of Beyond Fifth Generation(B5G)can guarantee a good multimedia Quality of Experience(QoE).As a special case of multimedia services,online learning takes into account both the usability of the service and the cognitive development of the *** that affect the Quality of Online Learning Experience(OL-QoE)become more *** get over this dilemma,we propose a systematic scheme by integrating big data,Machine Learning(ML)technologies,and educational psychology ***,we first formulate a general definition of OL-QoE by data analysis and experimental *** formula considers both the subjective and objective factors(i.e.,video watching ratio and test scores)that most affect ***,we induce an extended layer to the classic Broad Learning System(BLS)to construct an Extended Broad Learning System(EBLS)for the students'OL-QoE *** the extended layer can increase the width of the BLS model and reduce the redundant nodes of BLS,the proposed EBLS can achieve a trade-off between the prediction accuracy and computation ***,we provide a series of early intervention suggestions for different types of students according to their predicted OL-QoE *** timely interventions,their OL-QoE and learning performance can be *** results verify the effectiveness oftheproposed scheme.

关键词： B5G Online learning Quality of experience

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