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AN EFFECTIVE CONTINUOUS ALGORITHM FOR APPROXIMATE SOLUTIONS OF LARGE SCALE MAX-CUT PROBLEMS

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Journal of Computational Mathematics 2006年第6期24卷 749-760页

作者： Cheng-xian Xu Xiao-liang Feng-min Xu Department of Mathematics Xi 'an Jiaotong University Xi ' an 710049 China

An effective continuous algorithm is proposed to find approximate solutions of NP-hard max-cut problems. The algorithm relaxes the max-cut problem into a continuous nonlinear programming problem by replacing n discrete constraints in the original problem with one single continuous constraint. A feasible direction method is designed to solve the resulting nonlinear programming problem. The method employs only the gradient evaluations of the objective function, and no any matrix calculations and no line searches are required. This greatly reduces the calculation cost of the method, and is suitable for the solution of large size max-cut problems. The convergence properties of the proposed method to KKT points of the nonlinear programming are analyzed. If the solution obtained by the proposed method is a global solution of the nonlinear programming problem, the solution will provide an upper bound on the max-cut value. Then an approximate solution to the max-cut problem is generated from the solution of the nonlinear programming and provides a lower bound on the max-cut value. Numerical experiments and comparisons on some max-cut test problems （small and large size） show that the proposed algorithm is efficient to get the exact solutions for all small test problems andwell satisfied solutions for most of the large size test problems with less calculation costs.

关键词： Max-cut problems Algorithm Feasible direction method Laplacian matrix,Eigenvectors.

湿地表层底泥溶解性有机质荧光组分特征及与真菌群落相关性

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光谱学与光谱分析 2025年第1期45卷 191-196页

作者：史传奇李艳孟令波胡钰金梁哈尔滨学院黑龙江省寒区湿地生态与环境研究重点实验室黑龙江哈尔滨150086 北京市农林科学院植物营养与资源环境研究所北京100097 东北农业大学资源与环境学院黑龙江哈尔滨150038

溶解性有机质(DOM)和微生物群落间具有紧密联系,DOM为微生物提供营养,微生物代谢可转化DOM,两者间相互作用共同影响着生态系统的物质循环与能量流动。采集北方寒区天然湿地(河流湿地,HL;湖泊湿地,HP)和人工湿地(水田,ST;鱼塘,YT)表层(0~... 详细信息

溶解性有机质(DOM)和微生物群落间具有紧密联系,DOM为微生物提供营养,微生物代谢可转化DOM,两者间相互作用共同影响着生态系统的物质循环与能量流动。采集北方寒区天然湿地(河流湿地,HL;湖泊湿地,HP)和人工湿地(水田,ST;鱼塘,YT)表层(0~15 cm)底泥样品,采用三维荧光光谱法和高通量测序技术,揭示不同类型湿地表层底泥DOM荧光光谱及真菌群落特征,并进一步分析其相关性。结果表明:表层底泥DOM荧光光谱共识别出4种荧光组分,包括类富里酸(C1)、类胡敏酸(C2)和类蛋白质(类色氨酸C3和类酪氨酸C4)。C1和C2成显著正相关,而与类蛋白质间相关性不显著。C1的相对浓度高于C2,C3和C4的相对浓度接近。YT中DOM浓度相对高于其余样品,HL和HP中C2和类蛋白质相对浓度具有显著差异,ST和YT中C1、C2和C3的相对浓度均具有显著差异。湿地表层底泥真菌群落优势门(除未分类类群)为子囊菌门(Ascomycota)、担子菌门(Basidiomycota)、罗兹菌门(Rozellomycota)。YT中真菌群落Chao1丰富度指数、Shannon多样性指数显著较低,而Simpson优势度指数显著较高,HP中Shannon多样性指数显著高于其余样品。C1、C2与真菌群落多样性显著相关,C2与真菌群落组成显著相关,而类蛋白质与真菌群落无显著相关性。C1、C2与子囊菌门均成显著正相关,C1与壶菌门(Chytridiomycota)和单毛壶菌门(Monoblepharomycota)成显著负相关,C2与担子菌门、罗兹菌门、壶菌门、单毛壶菌门均成显著负相关。因此,真菌群落对DOM相对大分子量荧光组分的相对浓度具有显著影响。针对北方寒区典型湿地表层底泥DOM荧光光谱特征及与真菌群落相关性进行分析,为湿地环境监测与评价提供基础数据,并为湿地合理利用提供理论参考。

关键词：三维荧光光谱溶解性有机质荧光组分真菌

Measurement of surface shear stress vector distribution using shear-sensitive liquid crystal coatings

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Acta Mechanica Sinica 2012年第5期28卷 1261-1270页

作者： Ji-Song Zhao Peter Scholz liang-xian Gu School of Astronautics Northwestern Polytechnical University Institute of Fluid Mechanics TU Braunschweig

The global wall shear stress measurement tech- nique using shear-sensitive liquid crystal （SSLC） is extended to wind tunnel measurements. Simple and common every- day equipment is used in the measurement; in particular a tungsten-halogen light bulb provides illumination and a saturation of SSLC coating color change with time is found. Spatial wall shear stress distributions of several typical flows are obtained using this technique, including wall-jet flow, vortex flow generated by a delta wing and junction flow behind a thin cylinder, although the magnitudes are not fully calibrated. The results demonstrate that SSLC technique can be extended to wind tunnel measurements with no complicated facilities used.

关键词： Shear-sensitive liquid crystal (SSLC) Surfaceshear stress measurement. Wall-jet. Vortex generator- Junc-tion flow

Solution of the Energy Level of Hydrogen-Like Atom for the Debye Shielding Potential

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Communications in Theoretical Physics 2002年第5期38卷 601-605页

作者： hu xian-Quan hu Wen-Jiang MA Yong Department of Physics Chongqing Normal University Chongqing 400047 China Department of Electronic Information Engineering Chongqing University of Post and Telecommunications Chongqing 400065 China Department of Physics Chongqing Normal University Chongqing 400047 China

The first-order revision and the approximation analytical formula of the energy levels for hydrogen-likeatoms under the condition of Debye shielding potential are achieved by means of the Rayleigh-Schrodinger perturbationtheory; meanwhile, the corresponding recurrence relations are obtained from the use of the solution of power series. Basedon the above solutions and with the use of energy consistent method the equivalent value of second-order reversion underthe condition of Debye shielding potential is produced as well and the result is compared with the data obtained by thenumerical method. Besides, the critical bond-state and corresponding cut-off conditions are discussed.

关键词： Debye potential, recurrence relations, energy consistent method, hydrogen-like atoms, criticalbond-state

Partial-TMR: A New Method for Protecting Register Files Against Soft Error Based on Lifetime Analysis

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Journal of Computer Science & Technology 2021年第5期36卷 1089-1101页

作者： xian-Geng liang Ying-Ke Gao Geng-Xin hua Beijing Institute of Control Engineering China Academy of Space TechnologyBeijing 100090China

High-energy particles in the space can easily cause soft error in register file(RF).As a critical structure in a processor,RF often stores data for long periods of time and is read frequently,resulting in a higher probability of spreading corrupted data to other parts of the *** triple modular redundancy(TMR)is a common and effective fault tolerance method that enables multi-bit error *** full TMR for all the registers could cause excessive area and power ***,some registers in RF have less impact on processor ***,there is no need to design TMR for *** paper designs an efficient strategy which can rate the registers in RF based on their *** on the proposed strategy,a new RF fault tolerance method named Partial-TMR formulates in this paper,which selectively protects more vulnerable registers against multi-bit error,and improves fault tolerance *** integer RF,Partial-TMR improves its soft error correction capability by 24.5%relative to the baseline system and 3%relative to ParShield,while for floating-point RF,the improvement comes to 5.17%and 0.58%*** soft error correction capability of Partial-TMR is slightly lower than that of full TMR by 1%to 3%,but Partial-TMR significantly cuts the area and power *** with full TMR,Partial-TMR decreases the area and power overheads by 71.6%and 64.9%,*** also has little impact on the ***-TMR is a more cost-effective fault tolerance method compared with ParShield and full TMR.

关键词： register file soft error lifetime analysis selective protection triple modular redundancy(TMR)

Solidification Behavior and Microstructures Characteristics of Ti-48Al-3Nb-1.5Ta Powder Produced by Supreme-Speed Plasma Rotating Electrode Process

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Acta Metallurgica Sinica(English Letters) 2023年第8期36卷 1221-1234页

作者： Zhenbo Zuo Rui hu xian Luo Qingxiang Wang Chenxi Li Zhen Zhu Jian Lan Shujin liang Hongkui Tang Kang Zhang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Sino-Euro Materials Technologies of Xi’an Co. Ltd.Xi’an710018China

In this study,the characteristics and solidification behavior of Ti-48Al-3Nb-1.5Ta powder produced by supreme-speed plasma rotating electrode process(SS-PREP®)were *** microstructure,phase and characteristics were analyzed by scanning electron microscopy,X-ray diffraction and other *** atomization mechanism is direct drop *** relationship between the particle size and cooling rate is vc=3.14×10^(-7)·d^(-2)+1.18×10^(-2)·d^(3/2),and the relationship between secondary dendrite arm space and the particle size isλ=0.028d+0.11,as well as the relationship between SDAS and cooling rate isλ=4.84×10^(-5)·T^(-1.43).With increase in particle size,the surface structure gradually changes from the featureless smooth structure to dendritic and cellular dendritic morphology,and the flow ability becomes *** carbides mainly exist within 5 nm of the surface and the oxidation layer is about 20 nm ***-48Al-3Nb-1.5Ta powder was mainly composed ofα2 phase andγ*** increase in particle size,the content ofγphase increases,and the hardness decreases *** 106–250μm particles are composed of multiple grains with the grain size of 70–80μ*** microstructure,phase composition and hardness of different TiAl powders with the same size are similar,but the elastic modulus is different.

关键词： Supreme-speed plasma rotating electrode process(SS-PREP) TiAl alloy Atomization Powder Microstructure

Tracking direct and indirect impact on technology and policy of transformative research via ego citation network

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Journal of Data and Information Science 2024年第3期9卷 65-87页

作者： xian Li Xiaojun hu College of Computer and Information Science Southwest UniversityChongqing 400037China Medical Information Center Zhejiang University School of MedicineHangzhou 310058China

Purpose:The disseminating of academic knowledge to nonacademic audiences partly relies on the transition of subsequent citing *** study aims to investigate direct and indirect impact on technology and policy originating from transformative research based on ego citation ***/methodology/approach:Key Nobel Prize-winning publications(NPs)in fields of gene engineering and astrophysics are regarded as a proxy for transformative *** this contribution,we introduce a network-structural indicator of citing patents to measure technological impact of a target article and use policy citations as a preliminary tool for policy ***:The results show that the impact on technology and policy of NPs are higher than that of their subsequent citation generations in gene engineering but not in *** limitations:The selection of Nobel Prizes is not balanced and the database used in this study,Dimensions,suffers from incompleteness and inaccuracy of citation *** implications:Our findings provide useful clues to better understand the characteristics of transformative research in technological and policy ***/value:This study proposes a new framework to explore the direct and indirect impact on technology and policy originating from transformative research.

关键词： Transformative research Nobel Prize winning articles Citation networks Technological impact Policy impact

Necessary conditions for Gabor frames

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Science China Mathematics 2007年第2期50卷 276-284页

作者： xian-liang SHI Fang CHEN LMAM College of Mathematics and Computer ScienceHunan Normal UniversityChangsha 410081China

The goal of this paper is to establish a set of necessary conditions for Gabor frames. These conditions are also sufficient for tight frames.

关键词： Gabor frame necessary condition 42C15 42C40

Risk factors and managements of hemorrhage associated with pancreatic fistula after pancreaticoduodenectomy

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Hepatobiliary & Pancreatic Diseases International 2017年第5期16卷 537-544页

作者： Xing liang Li-Gang Shi Jun Hao An-An Liu Dan-Lei Chen xian-Gui hu Cheng-Hao Shao Department of Pancreatic-biliary Surgery Changzheng Hospital Second Military Medical University Department of Pancreatic Surgery Changhai Hospital Second Military Medical University

BACKGROUND: Post-pancreaticoduodenectomy pancreatic fistula associated hemorrhage (PPFH) is one of the leading lethal complications. Our study was to analyze the risk factors and managements of hemorrhage associated with pancreatic fistula after pancreaticoduodenectomy, and to evaluate treatment options. METHOD: We analyzed 445 patients who underwent pancreaticoduodenectomy or pylorus-preserving pancreaticoduodenectomy and evaluated the relevance between clinical data and PPFH. RESULTS: The incidence of postoperative pancreatic fistula (POPF) was 27.42% (122/445), and the incidence of PPFH was 4.49% (20/445). Among the 20 patients with PPFH, 7 died and 13 were cured. Interventional angiographic therapy was performed for 10 patients and 5 were successfully treated. Relaparotomy was performed for 5 patients and 2 were successfully cured. Univariate logistic regression analysis indicated that several risk factors were related to PPFH: the nature of tumor (carcinoid/low-grade or high-grade malignancy), preoperative day 1. serum prealbumin, preoperative day 1 total bilirubin (TBIL), operative time, blood loss in the operation, operative method (vascular resection and revascularization), postoperative day 3 TBIL, biliary fistula, and the grade of POPF. The multivariate stepwise logistic regression analysis demonstrated that the nature of tumor and the grade of POPF were independently risk factors of PPFH. Receiver operating characteristic curve indicated that preoperative day 1 serum prealbumin level <173 mg/L and postoperative day 3 TBIL ***/L were the risk factors of PPFH. CONCLUSIONS; The risk of PPFH was found to be increased with high potential malignancy and high grade of POPE Angiography-embolization is one of the major and effective therapies for PPFH. Extraluminal-intraluminal PPFH is more serious and needs more aggressive treatments.

关键词： pancreatic neoplasms pancreaticoduodenectomy postoperative pancreatic fistula hemorrhage risk factors