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最小负载受限k-中位问题的近似方案

计算机学报 2024年第7期47卷 1595-1614页

作者：张震冯启龙徐雪松刘利枚杨俊丰石峰湖南工商大学前沿交叉学院长沙410205 湘江实验室长沙410205 中南大学计算机学院长沙410083

给定度量空间中的用户集合C和带有最小负载τ:F→(O,|C|]的设施集合F以及正整数k,最小负载受限k中位问题的一个可行解(H,σ)由满足|H|≤k的开设设施集合H⊆F和满足|σ^(-1)(f)|≥τ(f)∀(f)∈H的映射σ:C→H组成。(H,σ)的费用为∑_(c∈c... 详细信息

给定度量空间中的用户集合C和带有最小负载τ:F→(O,|C|]的设施集合F以及正整数k,最小负载受限k中位问题的一个可行解(H,σ)由满足|H|≤k的开设设施集合H⊆F和满足|σ^(-1)(f)|≥τ(f)∀(f)∈H的映射σ:C→H组成。(H,σ)的费用为∑_(c∈c)^(σ)(c,σ(c))其中,(σ)(c,σ(c)为c与σ(c)之间的距离.最小负载受限k-中位问题的目标是找到费用最低的可行解.本文以k作为固定参数研究最小负载受限k-中位问题的求解算法.本文首先利用D采样方法寻找与最优解中的开设设施较为接近的用户,然后围绕这些用户划分空间并选取开设设施.给定满足C∪F⊂R^(d)的实例(C,F,k,τ)和常数ε∈(0,1),本文结合上述思路和降维方法提出了时间复杂度为o(ndk+(kε-1)^(kε)^(-o(1)))n^(o(1)))的(1+ε)-近似算法,其中,n=|C∪F|.此前,人们在固定参数时间内得到的关于该问题的最好近似结果为3+ε;只有在设施可以被开设在欧几里得空间中的任意位置且所有设施最小负载都相等的实例中,存在固定参数时间的(1+ε)-近似算法.

关键词：固定参数算法近似算法设施选址 k-中位 D-采样

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“破五唯”背景下研究生学业水平多元化评价

教育教学论坛 2024年第12期 13-16页

作者：徐雪松张永贤华东交通大学电气与自动化工程学院江西南昌330013

研究生学业水平评价是研究生教育质量评价的重要组成部分,对教书和育人都具有较强的诊断性、导向性。就研究生学业水平多元化评价体系进行了探讨,通过改进结果评价、强化过程评价、探索增值评价,克服过去研究生学业评价中“重学术、轻... 详细信息

研究生学业水平评价是研究生教育质量评价的重要组成部分,对教书和育人都具有较强的诊断性、导向性。就研究生学业水平多元化评价体系进行了探讨,通过改进结果评价、强化过程评价、探索增值评价,克服过去研究生学业评价中“重学术、轻育人”,“重数量、轻质量”,“重结果、轻过程”的弊端,既有利于帮助学生明确自己的不足和努力的方向,促进学生进一步的发展;也可以为教学与管理提供反馈,推动教学和管理的改革与进步。

关键词：研究生学业水平多元化评价

Vertebral Artery Stenting for Acute Multiple Cerebral Infarctions Caused by Vertebral Artery Dissection After Massage:A Case Report

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Chinese Medical Sciences Journal 2024年第2期39卷 149-154页

作者： Ying-xue Cui Chuan-Jin song xue-Si Hou Gui-Lin Liu xu Ji Shao-song Wang Department of Neurology Beijing Hospital of Traditional Chinese MedicineCapital Medical UniversityBeijing 100010China

Vertebral artery dissection is a rare pathology that can cause ischemic stroke in young *** massage,especially improper pulling manipulation,is a cause of vertebral artery *** present a case of 32-year old woman who developed acute multiple posterior circulation ischemic cerebral infarctions as a result of left vertebral artery V4 segment dissection after receiving neck *** underwent emergency vertebral artery stent implantation at the site of the *** were relieved the day after *** patient recovered without adverse complications or endovascular restenosis in the following year.

关键词： vertebral artery dissection acute ischemic stroke stent implantation endovascular therapy

Acid-rock reaction kinetics in a two-scale model based on reaction order correction

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Petroleum Science 2024年第3期21卷 2089-2101页

作者： xue-song Li Ning Qi Ze-Hui Zhang Lian Liu Xia-Qing Li xu-Hang Su School of Petroleum Engineering China University of Petroleum(East China)Qingdao266580ShandongChina Key Lab of Unconventional Oil&Gas Development Ministry of EducationChina University of Petroleum(East China)Qingdao26650ShandongChina SINOPEC Northwest Oilfield Branch Company Urumqi830011XinjiangChina Petroleum Engineering Technology Research Institute SINOPEC Shengli Oilfield CompanyDongying257000ShandongChina

The reaction order plays a crucial role in evaluating the response rate of ***,the conventional two-scale model typically assumes that the reaction order is constant as one,which can lead to significant deviations from *** address this issue,this study proposes a novel multi-order dynamic model for acid-rock reaction by combining rotating disk experimental data with theoretical *** numerical simulations,this model allows for the investigation of the impact of acidification conditions on different orders of reaction,thereby providing valuable insights for on-site *** analysis reveals that higher response orders require higher optimal acid liquid flow rates,and lower optimal H+diffusion coefficients,and demonstrate no significant correlation with acid ***,it is recommended to increase the displacement and use high-viscosity acid for reservoirs with high calcite content,while reducing the displacement and using low-viscosity acid for reservoirs with high dolomite content.

关键词： Reaction order Two-scale model Wormhole propagation Carbonate rocks Numerical simulation

Heterostructured Pt-Ni_(3)Mo_(3)N formed via ammonia-containing polyoxometalates for highly efficient electrocatalytic hydrogen evolution in acid medium

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Journal of Energy Chemistry 2024年第5期92卷 698-704页

作者： Bianqing Ren xue Gong Jing Cao Dezheng Zhang Zizhun Wang Ping song Ce Han Weilin xu State Key Laboratory of Electroanalytical Chemistry Jilin Province Key Laboratory of Low Carbon Chemical PowerChangchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina School of Applied Chemistry and Engineering University of Science and Technology of ChinaHefei 230026AnhuiChina Key Laboratory of Automobile Materials MOE School of Materials Science&EngineeringJilin Provincial International Cooperation Key Laboratory of High-Efficiency Clean Energy MaterialsElectron Microscopy Centerand International Center of Future ScienceJilin UniversityChangchun 130012JilinChina

Constructing heterostructured nanohybrid is considered as a prominent route to fabricate alternative electrocatalysts to commercial Pt/C for hydrogen evolution reaction(HER).In this work,(NH_(4))_(4)[NiH_(6)Mo_(6)O_(4)]·5H_(2)O polyoxometalates(NiMo_(6))are adopted as the cluster precursors for simple fabrication of heterostructured Pt-Ni_(3)Mo_(3)N nanohybrids supported by carbon black(Pt-Ni_(3)Mo_(3)N/C)without using additional N *** improved porosity and enhanced electronic interaction of Pt-Ni_(3)Mo_(3)N/C should be attributed to the integration of Pt with NiMo_(6),which favors the mass transport,promotes the formation of exposed catalytic sites,and benefits the regulation of intrinsic ***,the as-obtained Pt-Ni_(3)Mo_(3)N/C exhibits impressive and durable HER performance as indicated by the low overpotential of 13.7 mV at the current density of 10 mA cm^(-2) and the stable overpotential during continuous working at 100 mA cm^(-2) for 100 *** work provides significant insights for the synthesis of new highly active heterostructured electrocatalysts for renewable energy devices.

关键词： Polyoxometalates Cluster precursors Heterostructured nanohybrids Hydrogen evolution reaction Electrocatalysis

Molecule aging induced by electron attacking

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Journal of Energy Chemistry 2024年第6期93卷 519-525,I0013页

作者： Ping song Yining Dong xue Gong Mingbo Ruan Baoxin Ni xuanhao Mei Kun Jiang Weilin xu State Key Laboratory of Electroanalytical Chemistry and Jilin Province Key Laboratory of Low Carbon Chemical Power Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022JilinChina School of Applied Chemistry and Engineering University of Science and Technology of Chin1Hefei 230026AnhuiChina Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Collaborative Innovation Center of Chemistry for Energy MaterialsDepartment of ChemistryFudan UniversityShanghai 200438China

Here we propose a new concept of"molecule aging":with some special treatment,a molecule could be"aged"by losing some unknown tiny particles or pieces from atoms in the molecule,Such"aging"or loss of unknown tiny particles does not change apparently its molecular structure or chemical composition,but some physicochemical properties could be changed *** further confirm such"molecule aging"via a long-term electron attacking to age water(H_(2)O)*** IR spectra show no structural difference between the fresh water and the aged one,while the NMR spectra show that the electron attacking can decrease the size of water *** facts indicate that the electron attacking indeed can"affect"the structure of water molecule slightly but without damaging to its basic molecule *** exploration reveals that the hydrogen evolution reaction(HER)activity of the aged water molecule is lower than the fresh water on the same Pt/C *** density functional theory calculations indicate that the shortened O-H bond in H_(2)O indeed can present lower HER activity,so the observed size decrease of water clusters from NMR probably could be attributed to the shortening of O-H bond in water *** results indicate significantly that the molecule aging can produce materials with new functions for new possible applications.

关键词： Aging of molecules Electron attacking Full width at half maxima Hydrogen evolution reaction

Linear Quadratic Optimal Control for Systems Governed by First-Order Hyperbolic Partial Differential Equations

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Journal of Systems Science & Complexity 2024年第1期37卷 230-252页

作者： xue Xiaomin xu Juanjuan ZHANG Huanshui School of Control Science and Engineering Shandong UniversityJinan 250061China College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266000China

This paper focuses on linear-quadratic(LQ)optimal control for a class of systems governed by first-order hyperbolic partial differential equations(PDEs).Different from most of the previous works,an approach of discretization-then-continuousization is proposed in this paper to cope with the infinite-dimensional nature of PDE *** contributions of this paper consist of the following aspects:(1)The differential Riccati equations and the solvability condition of the LQ optimal control problems are obtained via the discretization-then-continuousization method.(2)A numerical calculation way of the differential Riccati equations and a practical design way of the optimal controller are ***,the relationship between the optimal costate and the optimal state is established by solving a set of forward and backward partial difference equations(FBPDEs).(3)The correctness of the method used in this paper is verified by a complementary continuous method and the comparative analysis with the existing operator results is *** is shown that the proposed results not only contain the classic results of the standard LQ control problem of systems governed by ordinary differential equations as a special case,but also support the existing operator results and give a more convenient form of computation.

关键词： Discretization-then-continuousization method first-order hyperbolic partial differential equations forward and backward partial difference equations linear quadratic optimal control.

Multicolor emission from lanthanide ions doped lead-free Cs_(3)Sb_(2)Cl_(9) perovskite nanocrystals

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Journal of Rare Earths 2024年第5期42卷 940-946,I0005页

作者： He Shao Lifang Li Xiufeng Wu Lin xu Biao Dong Donglei Zhou xue Bai Hongwei song State Key Laboratory of Organic Electronics and Information Displays&Institute of Advanced Materials College of Materials Science and EngineeringNanjing University of Posts&TelecommunicationsNanjing210023China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin UniversityChangchun130012China

The toxicity of lead ions has become the severe challenge for the all-inorganic lead halide p erovskite materials,although some works have rep orted the lead-free perovskite nanocrystals(NCs),the photoluminescence quantum yield(PLQY)of these materials is still ***,because the halogen ions can be easily exchanged,the controllable multicolor emission in perovskite NCs is difficult to realize in current *** this work,we introduced lanthanide ions into lead-free Cs_(3)Sb_(2)Cl_(9) perovskite *** from the energy transfer between Cs_(3)Sb_(2)Cl_(9) perovskite NC host and lanthanide ions,the multicolor emission was *** on controlling the doping concentration of Tb^(3+)and Eu^(3+)ions,the white light emission under UV excitation would be turned easily in the Tb^(3+)/Eu^(3+)codoped *** addition,efficient energy transfer from perovskite NCs to Tb^(3+)or Eu^(3+)ions is beneficial to improving the optical properties of lead-free perovskite NCs,resulting in maximum PLQYs of red,green and white light emission of 22.6%,19.7%and 28.5%,***,a white light emitting device(WLED)was fabricated with a power efficiency of 18.5 lm/W,which presents the Commission Internationale de l'Eclairage(CIE)of(0.33,0.35).

关键词： Perovskite nanocrystals Lead free Lanthanide ions Energy transfer White light emitting device Rare earths

Combatting Pathogenic Bacteria with Synthetic Immunotherapeutics from Chitosan:Antibody Recruiting at Engineered Bacterial Surface with Peptidoglycan Analogs

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CCS Chemistry 2024年第6期6卷 1448-1457页

作者： Yuan xu Shihao song Hongwei Duan Yinyue Deng xue-Wei Liu School of Chemistry Chemical Engineering and BiotechnologyNanyang Technological UniversitySingapore 637371 Key Laboratory of Tropical Biological Resources of Ministry of Education School of Pharmaceutical SciencesHainan UniversityHaikou 570228 School of Pharmaceutical Sciences(Shenzhen) Shenzhen Campus of Sun Yat-sen UniversitySun Yat-sen UniversityShenzhen 518107

The emergence of microbial drug resistance,coupled with the paucity of new antibiotics poses an impending threat to public *** this work,we drew inspiration from synthetic peptidoglycan oligomers and successfully constructed antibody-recruiting peptidoglycan analogs,2a-d,with excellent safety profiles and high efficiencies in recruiting antibodies across different ***,we demonstrated that these peptidoglycan analogs could be readily incorporated into bacteria cell walls,whereby both simple monoclonal and pooled human serum antibodies effectively congregated to the surfaceengineered bacteria,leading to the complete extermination of the engineered bacterial cells both in vitro and in *** peptidoglycan analog agents for recruiting endogenous antibodies to combat pathogenic bacteria enable further development of promising broad-spectrum immunotherapeutics.

关键词： chitosan bacterial infection endogenous antibodies bacterial surface engineering peptidoglycan analogs