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Day-ahead Voltage-stability-constrained Network topology Optimization with Uncertainties

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 730-741页

作者： Dingli Guo Lei Wang Ticao Jiao Ke Wu Wenjing Yang the School of Electrical and Electronic Engineering Shandong University of Technology

A day-ahead voltage-stability-constrained network topology optimization(DVNTO) problem is proposed to find the day-ahead topology schemes with the minimum number of operations(including line switching and bus-bar splitting) while ensuring the sufficient hourly voltage stability margin and the engineering operation requirement of power systems. The AC continuation power flow and the uncertainty from both renewable energy sources and loads are incorporated into the formulation. The proposed DVNTO problem is a stochastic, largescale, nonlinear integer programming problem. To solve it tractably, a tailored three-stage solution methodology, including a scenario generation and reduction stage, a dynamic period partition stage, and a topology identification stage, is presented. First, to address the challenges posed by uncertainties, a novel problem-specified scenario reduction process is proposed to obtain the representative scenarios. Then, to obtain the minimum number of necessary operations to alter the network topologies for the next 24-hour horizon, a dynamic period partition strategy is presented to partition the hours into several periods according to the hourly voltage information based on the voltage stability problem. Finally, a topology identification stage is performed to identify the final network topology scheme. The effectiveness and robustness of the proposed three-stage solution methodology under different loading conditions and the effectiveness of the proposed partition strategy are evaluated on the IEEE 118-bus and 3120-bus power systems.

关键词： Power system stability Switches Uncertainty Stability criteria Network topology topology Renewable energy sources

Probing phase transition of band topology via radiation topology

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Photonics Research 2024年第6期12卷 1150-1157页

作者： CHANG-YIN JI WENZE LAN PENG FU GANG WANG CHANGZHI GU YELIANG WANG JIAFANG LI YUGUI YAO BAOLI LIU Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE) Beijing Key Laboratory of Nanophotonics&Ultrafine Optoelectronic Systemsand School of PhysicsBeijing Institute of TechnologyBeijing 100081China School of Integrated Circuits and Electronics MIIT Key Laboratory for Low-Dimensional Quantum Structure and DevicesBeijing Institute of TechnologyBeijing 100081China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological Quantum Computation CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing 100190China

Topological photonics has received extensive attention from researchers because it provides brand new physical principles to manipulate *** topology is characterized using the Berry phase defined by Bloch *** now,the scheme for experimentally probing the topological phase transition of band topology has always been relatively lacking in topological ***,radiation topology can be aroused by the far-field polarization singularities of Bloch states,which is described by the Stokes *** such two types of topologies are both related to Bloch states on the band structures,it is rather surprising that their development is almost ***,in optical analogs of the quantum spin Hall effects(QSHEs)and Su-Schrieffer-Heeger model,we reveal the correlation between the phase transition of band topology and radiation topology and then demonstrate that the radiation topology can be employed to study the band topological *** experimentally demonstrate such an intriguing phenomenon in optical analogs of *** findings not only provide an insightful understanding of band topology and radiation topology,but also can serve as a route to manipulate light.

关键词： transition. topology topological

A topology framework for macromolecular complexes and condensates

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Nano Research 2022年第11期15卷 9809-9817页

作者： Maziar Heidari Duane Moes Otto Schullian Barbara Scalvini Alireza Mashaghi Medical Systems Biophysics and Bioengineering Leiden Academic Centre for Drug ResearchFaculty of ScienceLeiden UniversityLeiden 2333CCthe Netherlands Fachbereich Physik Freie Universität BerlinArnimallee 14Berlin 14195Germany Harvard Medical School Harvard University25 Shattuck StBoston MA 02115USA

Macromolecular assemblies such as protein complexes and protein/RNA condensates are involved in most fundamental cellular *** arrangement of subunits within these nano-assemblies is critical for their biological function and is determined by the topology of physical contacts within and between the subunits forming the *** the spatial arrangement of these interactions is of central importance to understand their functional and stability *** this concept article,we propose a circuit topology-based formalism to define the topology of a complex consisting of linear polymeric chains with interand intrachain *** apply our method to a system of model polymer chains as well as protein *** show that circuit topology can categorize different forms of chain *** multi-chain circuit topology should aid analysis and predictions of mechanistic and evolutionary principles in the design of macromolecular assemblies.

关键词： topology macromolecular complex protein evolution folding

Reconstruction of skin friction topology in complex separated flows

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ADVANCES IN AERODYNAMICS 2023年第1期5卷 1-35页

作者： Liu, Tianshu Western Michigan Univ Dept Mech & Aerosp Engn Kalamazoo MI 49008 USA

This paper describes a theoretical method for reconstruction of the skin friction topology in complex separated flows, which is developed based on the exact relation between skin friction and surface pressure through the boundary enstrophy flux (BEF). The key of this method is that a skin friction field is reconstructed from a surface pressure field as an inverse problem by applying a variational method. For applications, the approximate method is proposed, where the composite surface pressure field is given by a linear superposition of the base-flow surface pressure field and the surface pressure variation field and the base-flow BEF field is used as the first-order approximation. This approximate method is constructive in a mathematical sense since a complex skin friction field in separated flows can be reconstructed from some elemental skin friction structures (skin friction source/sink, vortex and their combinations) by a linear superposition of some simple surface pressure structures. The distinct topological features, such as critical points, separation lines and attachment lines, naturally occur as a result of such reconstruction. As examples, some elemental skin friction structures in separated flows are reconstructed in simulations, and the skin friction fields in shock-wave/boundary-layer interactions (SWBLIs) are reconstructed from pressure sensitive paint (PSP) images obtained in wind tunnel experiments.

关键词： Skin friction Surface pressure Boundary enstrophy flux Flow separation topology Inverse problem Variational method Euler-Lagrange equation Taylor-series-expansion solution Navier-Stokes equations Poincare-Bendixson index formula Shock-wave/boundary-layer interaction Pressure sensitive paint Aerodynamics BOUNDARY-LAYER 3-DIMENSIONAL SEPARATION SWEPT-SHOCK PHYSICS PRESSURE

Correlation,superconductivity and topology in graphene moirésuperlattice

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Frontiers of physics 2023年第4期18卷 199-207页

作者： Lingxiao Li Min Wu Xiaobo Lu International Centre for Quantum Materials Peking UniversityBeijing 100871China

Moirésuperlattices created by stacking different pieces of two-dimensional layered materials with a slight lattice mismatch have recently emerged as an exceptional platform for exploring emergent quantum *** stark contrast to the“parent”materials,the electronic band structures are significantly modified from moiréengineering due to the large-scale periodic moirépotential and interlayer *** this paper,we mainly focus on the recent progresses achieved in graphene-based moirésystems which have been a condensed-matter playground showing unprecedented abundance of quantum states such as strongly correlated states,superconductivity and novel band topologies.

关键词： twisted graphene moirésuperlattices correlation superconductivity topology

topology optimization of a 6-DOF spatial compliant mechanism based on Stewart propotype platform

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Acta Mechanica Sinica 2019年第5期35卷 1044-1059页

作者： Dachang Zhu Wanghu Zhan School of Mechanical and Electrical Engineering Guangzhou UniversityGuangzhou 510006China

To improve the global stiffness and conveniently build a model of a compliant mechanism with spatial multiple degrees of freedom(DOF),the topology optimization method,combined with the isomorphic mapping matrix,is proposed in this paper for structure synthesis of a 6-DOF spatial compliant *** using the differential approximation method,the Jacobian matrix of the Stewart prototype platform is calculated as the isomorphic mapping matrix,and its eigenvalues and eigenvectors are *** the isomorphic mapping matrix with the solid isotropic material with the penalization topology optimization method,the topological model of the 6-DOF spatial compliant mechanism is constructed,and a topological structure of the 6-DOF spatial compliant mechanism is derived which has the same differential kinematic characteristics as the Gough-Stewart prototype *** actuators are mounted inside the topological structure during the three-dimensional printing manufacturing process,and its driver directions are in accordance with the driver configuration directions of the Gough-Stewart prototype *** effectiveness of the proposed method for topological structure synthesis of the 6-DOF spatial compliant mechanism is demonstrated through several numerical examples and experimental studies.

关键词： 6-DOF spatial compliant mechanism Stewart prototype platform Isomorphic mapping Jacobian matrix topology optimization

topology optimization of joint load control with geometrical nonlinearity

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Chinese Journal of Aeronautics 2020年第1期33卷 372-382页

作者： Jie HOU Xiaojun GU Jihong ZHU Jie WANG Weihong ZHANG State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical University710072 Xi’anChina Institute of Intelligence Material and Structure Unmanned System TechnologiesNorthwestern Polytechnical University710072 Xi’anChina MIIT Lab of Metal Additive Manufacturing and Innovative Design Northwestern Polytechnical University710072 Xi’anChina

This paper presents an extended topology optimization approach considering joint load constraints with geo-metrical nonlinearity in design of assembled *** geometrical nonlinearity is firstly included to reflect the structural response and the joint load distribution under large *** avoid a failure of fastener joints,topology optimization is then carried out to minimize the structural end compliance in the equilibrium state while controlling joint loads intensities over *** nonlinear analysis and optimization,a novel implementation of adjoint vector sensitivity analysis along with super element condensation is introduced to address numerical instability *** degrees of freedom of weak regions are condensed so that their influences are excluded from the iterative Newton-Raphson(NR)*** examples are presented to validate the efficiency and robustness of the proposed *** effects of joint load constraints and geometrical nonlinearity are highlighted by comparing numerical optimization results.

关键词： Geometrical nonlinearity Joint load constraint Sensitivity analysis Super element condensation topology optimization

topology optimization of continuum structures considering damage based on independent continuous mapping method

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Acta Mechanica Sinica 2019年第2期35卷 433-444页

作者： Jiazheng Du Yunhang Guo Zuming Chen Yunkang Sui College of Mechanical Engineering and Applied Electronics Technology Beijing University of Technology Beijing 100124 China

A continuum topology optimization usually produces results similar to a skeleton structure. In addition, the material utilization in the optimized structure is greatly improved compared with the original structure. On the other hand, the redundancy of the structure is greatly reduced due to the removed material. A partial local failure in the optimized structure makes it more difficult for the entire structure to meet the strength/stiffness requirements. By using the independent continuous mapping (ICM) method, with minimal weight as the objective and both stress and displacement as the respective constraints, the continuum topology optimization models can be employed, which also consider damage. A dual-sequence quadratic programming (DSQP) algorithm is used to solve the topology optimization models. Numerical examples confirm the effectiveness and feasibility of the models. The results indicate that both a good load-path and weight reduction can be obtained. In addition, compared with the structure obtained using conventional topology optimization, redundancy is improved greatly, and the strength/stiffness requirements for the structure can be satisfied for each damage scenario. Furthermore, the results indicate that the strength/stiffness of the structure, after topology optimization, is slightly sensitive for local damage.

关键词： Damage Redundancy topology optimization ICM method

topology characteristics of three-dimensional grains in polycrystalline materials

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Science China(Technological Sciences) 2019年第2期62卷 263-268页

作者： WANG Hao XUE WeiHua KANG RenMu ZHANG YiFan LIU GuoQuan School of Materials Science and Engineering University of Science and Technology Beijing School of Materials Science and Engineering Liaoning Technical University Deyang Products Quality Supervision and Inspection Institute Collaborative Innovation Center of Steel Technology University of Science and Technology Beijing

The quantitative microstructural analysis in recrystallized pure iron is carried out by serial sectioning experiment coupled with three-dimensional(3-D) grain reconstruction technique. The full 3-D morphology of 16254 pure iron grains, which is the largest experimental 3-D grain dataset to date, is obtained. It is shown that the peak and the mean of the grain face number distribution were 10 and 13.5, respectively. For individual grains, the average trends that the highest and lowest face classes exhibited the highest affinity for mutual contact but the lowest affinity for contact with themselves are experimentally confirmed by 3-D pure iron grains. The pure iron grains are observed to have much more three-edged faces than Monte Carlo grains, resulting in relatively higher average dispersions of the grain edge distribution.

关键词： 3-D characterization serial sectioning Monte Carlo grain growth topology