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Decentralized output-feedback control of triangular large-scale nonlinear impulsive systems with time-varying delays: a gain scaling approach

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Science China(Information Sciences) 2023年第11期66卷 185-203页

作者： Debao FAN Xianfu ZHANG Weihao pan Hanfeng li School of Control Science and Engineering Shandong University

In this study, we investigate the decentralized output-feedback control problem for a class of triangular large-scale nonlinear impulsive systems(TLSNISs) with time-varying delays. Unlike existing design approaches in impulsive systems, a gain scaling approach is proposed for the first time to counteract the structural uncertainties of interconnected nonlinearities. Specifically, by fully exploiting the static gain, novel delay-independent impulsive observers are delicately constructed to estimate the unavailable states. Furthermore, the undesirable effects of time-varying delays and impulsive disturbances are eliminated using the comparison principle and average impulsive interval technique. The designed gain-scaling-based decentralized output-feedback controllers have concise linear-like forms and are independent of time delays. Moreover,by strengthening the gain scaling mechanism, we further develop an improved control scheme that endows the controllers with the capability to tolerate unknown external disturbances, thus improving its *** is shown that the system states converge exponentially to the origin in the disturbance-free case with the designed controllers(or to an adjustable neighborhood of the origin in the presence of disturbance). Finally,two examples, including an engineering system design example, are provided to demonstrate the effectiveness of the designed controllers for both lower TLSNISs and upper TLSNISs.

关键词： triangular large-scale systems nonlinear impulsive systems time-varying delay output feedback gain scaling approach

交联型聚乙烯醇纸张表面施胶剂的制备及其应用

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陕西科技大学学报 2025年第1期43卷 1-7页

作者：费贵强李实肖文娟杨晨榕解攀陕西科技大学化学与化工学院陕西省轻化工助剂重点实验室陕西西安710021 西安北方惠安化学工业有限公司陕西西安710302

为了改善聚乙烯醇、淀粉作为纸张表面施胶剂的应用性能,选用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)和硼砂(STB)为交联剂,交联改性淀粉(PS)和聚乙烯醇(PVA1799),制备出不同交联程度的纸张表面施胶剂(CPSn-PVA).通过傅里叶红外光谱(FT-I... 详细信息

为了改善聚乙烯醇、淀粉作为纸张表面施胶剂的应用性能,选用γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)和硼砂(STB)为交联剂,交联改性淀粉(PS)和聚乙烯醇(PVA1799),制备出不同交联程度的纸张表面施胶剂(CPSn-PVA).通过傅里叶红外光谱(FT-IR),扫描电镜(SEM)及稳定性测试对纸张表面施胶剂的性能进行了表征,探讨了KH560和STB的添加比例对纸张施胶剂的性能以及施胶后纸张物理性能的影响.实验结果表明,当STB添加量为0.1 g、KH560添加量为3 g时,纸张施胶剂膜拉伸强度可达25.6 MPa、断裂伸长率为326%.同时,与原纸相比,多重交联型纸张表面施胶剂表现出良好的应用性能,施胶后的纸张耐折次数、撕裂指数、接触角分别提升了6700%、65.04%、89.7%.

关键词：表面施胶剂改性淀粉聚乙烯醇硅烷偶联剂稳定性耐折度

Drag reduction of turbulent channel flows over an anisotropic porous wall with reduced spanwise permeability

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Applied Mathematics and Mechanics(English Edition) 2019年第7期40卷 1041-1052页

作者： Qingxiang li Ming pan Quan ZHOU Yuhong DONG Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University Shanghai 200072 China

The direct numerical simulation (DNS) is carried out for the incompressible viscous turbulent flows over an anisotropic porous wall. Effects of the anisotropic porous wall on turbulence modifications as well as on the turbulent drag reduction are investigated. The simulation is carried out at a friction Reynolds number of 180, which is based on the averaged friction velocity at the interface between the porous medium and the clear fluid domain. The depth of the porous layer ranges from 0.9 to 54 viscous units. The permeability in the spanwise direction is set to be lower than the other directions in the present simulation. The maximum drag reduction obtained is about 15.3% which occurs for a depth of 9 viscous units. The increasing of drag is addressed when the depth of the porous layer is more than 25 wall units. The thinner porous layer restricts the spanwise extension of the streamwise vortices which suppresses the bursting events near the wall. However, for the thicker porous layer, the wall-normal fluctuations are enhanced due to the weakening of the wall-blocking effect which can trigger strong turbulent structures near the wall.

关键词： direct numerical simulation (DNS) anisotropic porous medium drag reduction turbulent open channel flow

Effects of Y2O3 on the microstructure and mechanical properties ofspark plasma sintered fine-grained W-Ni-Mn alloy

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Journal of Rare Earths 2017年第11期35卷 1149-1155页

作者： Yanlin pan Lei Ding Hui li Daoping Xiang State Key Laboratory of Marine Resource Utilization in South China Sea Hainan University Haikou 570228 China Key Laboratory for Advanced Materials in Tropical Island Resources Ministry of Education Hainan University Haikou 570228 China

Fine-grained W-Ni-Mn-YOalloys were fabricated by mechanical alloying-assisted spark plasma sintering(SPS), and the effects of YOcontent on the microstructure and mechanical properties of the alloys were studied. Fine-grained 90 W-6 Ni-4 Mn-YOalloys with uniform microstructure and excellent properties were prepared by SPS at 1150 ℃. The addition of trace YOinhibited the sintering densification process and refined the W grain size. The average W grain size decreased from 5.5 μm to 2.1 μ*** fracture mode changed from W grain transgranular fracture and W-W interface fracture to W-W and W-Matrix phase interface fracture. The Rockwell hardness and bending strength of alloys initially increased and then decreased with increasing YOcontent. The optimum comprehensive mechanical properties(Rockwell hardness and bending strength) of the alloys were obtained at the same time when the mass fraction of YOwas 0.4%.

关键词： 90W-6Ni-4Mn alloys Y_2O_3 Spark plasma sintering Bending strength Fracture morphology

MULTI-GRANULARITY EVOLUTION ANALYSIS OF SOFTWARE USING COMPLEX NETWORK THEORY

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Journal of Systems Science & Complexity 2011年第6期24卷 1068-1082页

作者： Weifeng pan Bing li Yutao MA Jing liU State Key Laboratory of Software Engineering Wuhan University Wuhan 430072 China School of Computer Science and Information Engineering Zhejiang Gongshang University Hangzhou 310018 China School of Computer Wuhan University Wuhan 430072 China Complex Networks Research Center Wuhan University Wuhan 430072 China

Software systems are a typical kind of man-made complex systems. Understanding their evolutions can lead to better software engineering practices. In this paper, the authors use complex network theory as a tool to analyze the evolution of object-oriented （OO） software from a multi-granularity perspective. First, a multi-granularity software networks model is proposed to represent the topological structures of a multi-version software system from three levels of granularity. Then, some parameters widely used in complex network theory are applied to characterize the software networks. By tracing the parameters＇ values in consecutive software systems, we have a better understanding about software evolution. A case study is conducted on an open source OO project, Azureus, as an example to illustrate our approach, and some underlying evolution characteristics are uncovered. These results provide a different dimension to our understanding of software evolutions and also are very useful for the design and development of OO software systems.

关键词： Complex networks multi-granularity software evolution software system.

H_∞ Control for Nonlinear Stochastic Markov Systems with Time-Delay and Multiplicative Noise

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Journal of Systems Science & Complexity 2017年第6期30卷 1293-1315页

作者： WANG Yuhong pan Zhiteng li Yan ZHANG Weihai College of Information and Control Engineering China University of Petroleum (East China) College of Electrical Engineering and Automation Shandong University of Science and Technology

This paper is concerned with the H_∞ control problem for a class of nonlinear stochastic Markov jump systems with time-delay and system state-, control input-and external disturbancedependent noise. Firstly, by solving a set of Hamilton-Jacobi inequalities(HJIs), the exponential mean square H_∞ controller design of delayed nonlinear stochastic Markov systems is presented. Secondly,by using fuzzy T-S model approach, the H_∞ controller can be designed via solving a set of linear matrix inequalities(LMIs) instead of HJIs. Finally, two numerical examples are provided to show the effectiveness of the proposed design methods.

关键词： H∞ control Markov jump systems nonlinear stochastic systems time-delay (x,u,v)-dependent noise

Influence of pile-raft connection on lateral performance of combined pile-raft foundations adjacent to tunnelling

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Underground Space 2024年第2期15卷 176-187页

作者： Wenbo Gu liyuan Tong Huangsong pan Hongjiang li Institute of Geotechnical Engineering Southeast UniversityNanjing 211189China Department of Architecture and Architectural Engineering Kyoto UniversityKyoto 6158540Japan School of Architecture and Civil Engineering Xihua UniversityChengdu 610039China

The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft *** current engineering practices,the impact of these connections on the lateral performance of CPRFs is frequently overlooked,despite their *** address this issue,this study conducted three-dimensional finite element analyses to evaluate the contribution of pile-raft connections to the tunnelling-induced lateral performance of CPRFs in saturated *** the analysis,both passive and active loading at the pile head could be considered by varying the tunnel *** parameter studies,such as relative pile-raft modulus,pile embedded modulus,pile embedded depths,and pile shaft skin friction,were conducted to determine the optimal design parameters for *** results indicate that pile-raft connections significantly affect the tunnellinginduced deflections and bending moments of pile *** by the results,a simplified design method,the pile-raft connection coefficient Kc was ***,the pile-head restraint percentage was established to make a relationship with the pile-raft connection coefficient in order to assess the pile-raft connection and guide the pile-raft *** this paper,the recommended range value of Kc is 10–200 and the range value of pile-head restraint percentage is 24%–42%.

关键词： Combined pile-raft foundations Tunnelling Lateral performance Pile-raft connection

Abnormal thermal expansion coefficients in(Nd_(1−x)Dy_(x))_(2)Zr_(2)O_(7) pyrochlore:The effect of low-lying optical phonons

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Journal of Advanced Ceramics 2023年第5期12卷 1001-1014页

作者： Zesheng Yang Yi li Wei pan Chunlei Wan State Key Laboratory of New Ceramics&Fine Processing Tsinghua UniversityBeijing 100084China College of Mathematics and Physics Beijing University of Chemical TechnologyBeijing 100029China

Chemical doping is a normal strategy to tune thermal expansion coefficient(TEC)of ceramics in engineering applications,but the resultant TEC values usually follow Vegard’s law,as doping does not modify the nature of chemical bonding in ceramics and its *** this paper,we report abnormal TEC behavior in(Nd_(1−x)Dy_(x))_(2)Zr_(2)O_(7) ceramics,where the TEC values remarkably exceed the values predicted by Vegard’s law and even exceed the values obtained for two constituents Nd_(2)Zr_(2)O_(7) and Dy_(2)Zr_(2)O_(7).In addition to a reduction in lattice energy with an increasing molar fraction of Dy(x)value,we attribute the additional increase in the TEC to the high concentration of Dy dopants in a pyrochlore(P)region,which can soften low-lying optical phonon modes and induce strongly avoided crossing with acoustic phonon branches and enhanced *** believe that this finding can provide a new route to break through the restriction imposed by the conventional Vegard’s law on the TEC values and bring new opportunities for thermal barrier coatings(TBCs)or ceramic/metal composites towards realizing minimized thermal mismatch and prolonged service life during thermal cycling.

关键词： thermal barrier coating(TBC) thermal expansion first-principles calculations avoided crossing

Two-dimensional Stiefel-Whitney insulators in liganded Xenes

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npj Computational Materials 2022年第1期8卷 9-14页

作者： Mingxiang pan Dexin li Jiahao Fan Huaqing Huang School of Physics Peking University100871BeijingChina Collaborative Innovation Center of Quantum Matter 100871BeijingChina Center for High Energy Physics Peking University100871BeijingChina

Two-dimensional(2D)Stiefel-Whitney insulator(SWI),which is characterized by the second Stiefel-Whitney class,is a class of topological phases with zero Berry *** an intriguing topological state,it has been well studied in theory but seldom realized in realistic *** we propose that a large class of liganded Xenes,i.e.,hydrogenated and halogenated 2D group-IV honeycomb lattices,are 2D *** nontrivial topology of liganded Xenes is identified by the bulk topological invariant and the existence of protected corner ***,the large and tunable bandgap(up to 3.5 eV)of liganded Xenes will facilitate the experimental characterization of the 2D SWI *** findings not only provide abundant realistic material candidates that are experimentally feasible but also draw more fundamental research interest towards the topological physics associated with Stiefel-Whitney class in the absence of Berry curvature.

关键词： materials. topological Stiefel