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geometry and size optimization of stiffener layout for three-dimensional box structures with maximization of natural frequencies

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Chinese Journal of Aeronautics 2023年第1期36卷 324-341页

作者： Tiannan HU Xiaohong DING Heng ZHANG Lei SHEN Hao LI School of Mechanical Engineering University of Shanghai for Science and TechnologyShanghai 200093China Department of Mechanical Engineering and Science Kyoto UniversityKyoto 615-8540Japan

Based on the growth mechanism of natural biological branching systems and inspiration from the morphology of plant root tips,a bionic design method called Improved Adaptive Growth Method(IAGM)has been proposed in the authors’previous research and successfully applied to the reinforcement optimization of three-dimensional box structures with respect to natural ***,as a kind of ground structure methods,the final layout patterns of stiffeners obtained by using the IAGM are highly subjected to their ground structures,which restricts the optimization effect and freedom to further improve the dynamic performance of *** solve this problem,a novel post-processing geometry and size optimization approach is proposed in this *** method takes the former layout optimization result as start,and iteratively finds the optimal layout angles,locations,and lengths of stiffeners with a few design variables by optimizing the positions of some specific node lines called active node *** the same time,thick-nesses of stiffeners are also optimized to further improve natural frequencies of three-dimensional box *** this method,stiffeners can be successfully separated from their ground structures and further effectively improve natural frequencies of three-dimensional box structures with less material *** numerical examples are illustrated to validate the effectiveness and advantages of the suggested method.

关键词： Box structure geometry optimization Improved adaptive growth method Maximum natural frequency design Stiffener layout

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geometry optimizations of benzene clusters using a modified genetic algorithm

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Chinese Journal of Chemistry 2000年第4期18卷 475-481页

作者：蔡文生于芳邵学广潘忠孝 Department of Applied Chemistry University of Science and Technology of China Hefei 230026 Anhui China Department of Chemistry University of Science and Technology of China Hefei 230026 Anhui China

A modified genetic algorithm with real-number coding, non-uniform mutation and arithmetical crossover operators was described in this paper. A local minimization was used to improve the final solution obtained by the genetic algorithm. Using the exp-6–1 interatomic energy function, the modified genetic algorithm with local minimization (MGALM) was applied to the geometry optimization problem of small benzene clusters (C6H6)N(N = 2–7) to obtain the global minimum energy structures. MGALM is simple but the structures optimized are comparable to the published results obtained by parallel genetic algorithms.

关键词： geometry optimization genetic algorithms benzene clusters

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optimization of geometry at Hartree-Fock level Using the Generalized Simulated Annealing

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Applied Mathematics 2012年第10期3卷 1526-1531页

作者： Luiz Augusto Carvalho Malbouisson Antonio Moreira de Cerqueira Sobrinho Marco Antonio Chear Nascimento Miceal Dias de Andrade Instituto de Fisica Universidade Federal da BahiaSalvadorBrazil Instituto de Quimica Universidade Federal do Rio de JaneiroRio de JaneiroBrazil

This work presents a procedure to optimize the molecular geometry at the Hartree-Fock level, based on a global opti-mization method—the Generalized Simulated Annealing. The main characteristic of this methodology is that, at least in principle, it enables the mapping of the energy hypersurface as to guarantee the achievement of the absolute minimum. This method does not use expansions of the energy, nor of its derivates, in terms of the conformation variables. Distinctly, it performs a direct optimization of the total Hartree-Fock energy through a stochastic strategy. The algorithm was tested by determining the Hartree-Fock ground state and optimum geometries of the H2, LiH, BH, Li2, CH+, OH?, FH, CO, CH, NH, OH and O2 systems. The convergence of our algorithm is totally independent of the initial point and do not require any previous specification of the orbital occupancies.

关键词： geometry optimization Hartree-Fock Absolute Minimum Generalized Simulated Annealing

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Systematic assessment of various universal machine-learning interatomic potentials

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Materials Genome Engineering Advances 2024年第3期2卷 59-70页

作者： Haochen Yu Matteo Giantomassi Giuliana Materzanini Junjie Wang Gian-Marco Rignanese Institute of Condensed Matter and Nanosciences Universitécatholique de LouvainLouvain-la-NeuveBelgium State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'anShaanxiChina WEL Research Institute WavreBelgium

Machine-learning interatomic potentials have revolutionized materials modeling at the atomic *** to these,it is now indeed possible to perform simulations of ab initio quality over very large time and length *** recently,various universal machine-learning models have been proposed as an out-of-box approach avoiding the need to train and validate specific potentials for each particular material of *** this paper,we review and evaluate four different universal machine-learning interatomic potentials(uMLIPs),all based on graph neural network architectures which have demonstrated transferability from one chemical system to *** evaluation procedure relies on data both from a recent verification study of density-functional-theory implementations and from the Materials *** this comprehensive evaluation,we aim to provide guidance to materials scientists in selecting suitable models for their specific research problems,offer recommendations for model selection and optimization,and stimulate discussion on potential areas for improvement in current machinelearning methodologies in materials science.

关键词： formation energy geometry optimization machine learning phonons,universal machine-learning interatomic potentials verification

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Molecular simulation study on K^＋-Cl^- ion pair in geological fluids

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Acta Geochimica 2017年第1期36卷 1-8页

作者： Mengjia He Xiandong Liu Xiancai Lu Rucheng Wang State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing UniversityNanjing 210046 People's Republic of China

This paper reports a classical molecular dynamics study of the potential of mean forces(PMFs),association constants,microstructures K^+-Cl^- ion pair in supercritical *** constrained MD method is used to derive the PMFs of K^+-Cl^- ion pair from 673 to 1273 K in low-density water(0.10-0.60 g/cm).The PMF results show that the contact ion-pair(CIP) state is the one most energetically favored for a K^+-Cl^- ion *** association constants of the K^+-Cl^- ion pair are calculated from the PMFs,indicating that the K^+-Cl^- ion pair is thermodynamically *** gets more stable as T increases or water density *** microstructures of the K^+-Cl^- ion pair in the CIP and solvent-shared ion-pair states are characterized in ***,we explore the structures and stabilities of the KCl-Au(I)/Cu(I) complexes by using quantum mechanical *** results reveal that these complexes can remain stable for T up to1273 K,which indicates that KCl may act as a ligand complexing ore-forming metals in hydrothermal fluids.

关键词： Molecular dynamics KCl Potential of mean force Association constant geometry optimization

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Kinetics of Reduction of Thionine with Ribose and the Structural Properties of the Dye at Different pH Using DFT Method

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Chinese Journal of Chemistry 2011年第4期29卷 643-649页

作者： Ahmed, Khalid Azmat, Rafia Uddin, Fahim Fatmi, M. Qaiser Department of Chemistry University of Karachi Karachi 752 70 Pakistan Department of Chemistry Jinnah University for Women Nazimabad Karachi Pakistan Department of Chemistry University of California at Riverside California 92521 USA

The reaction between the thionine （Th） and the ribose was observed spectrophotometrically and changes in absorbance of Th were recorded at variable concentration of dye, reductant and pH. A pseudo first order rate of reaction was found to establish the reduction kinetics of the dye, studied at a pH range of 0.34 to 12.8. Absorption spectrum of Th at different pH, with ribose showed a pH （12.8） dependent introversion. The reduction most probably took place with enediol intermediate of the sugar at high pH. A full geometry optimization of predominant species of Th namely, mono-deprotonated, di-deprotonated Th, and LTh （leuco thionine） respectively, at low and high pH, was performed at B3LYP level of theory. The data obtained from the energy minimization were in excellent agreement with other experimental and theoretical observations. The calculated enthalpies of formation for both reduction reactions （mono-deprotonated Th＋H＋→leucothionine and di-deprotonated Th＋2H＋→leucothionine） provided evidences for maximum reduction of the dye at high pH.

关键词： thionine ribose pH enediol geometry optimization reduction

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Pose Estimation for Non-cooperative Spacecraft based on Deep Learning

Pose Estimation for Non-cooperative Spacecraft based on Deep...

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第三十九届中国控制会议

作者： Wenxiu Huan Mingmin Liu Qinglei Hu School of Automation Science and Electrical Engineering Beihang University Shanghai Aerospace Control Technology Institute Beijing Advanced Innovation Center for Big-Data Based Precision Medicine Beihang University

The pose estimation of non-cooperative space-borne object is of vital importance for on-orbit service and spacecraft approaching missions. Based on images taken by a monocular camera, an estimate algorithm is proposed to estimate the relative position and the relative attitude of non-cooperative spacecraft. The approach utilizes the off-the-shelf target detection network and key point regression network to predict 2D key points coordinates and combines the multiple view triangulation to reconstruct 3D model. Nonlinear least squares method is used to minimize 2D-3D corresponding coordinates to predict position and attitude. The proposed method effectively combines deep learning and geometric optimization algorithms, which is an innovative application of deep learning in the aerospace field. Finally, simulations are performed to prove the effectiveness of the theoretical results.

关键词： Non-cooperative Spacecraft Pose Estimation Convolution Neural Network geometry optimization

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A method for Quantum-Chemistry Study on Explosives with High-Precision and Low Time Consuming

A method for Quantum-Chemistry Study on Explosives with High...

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河南省化学会2016年学术年会

作者： Xiao Wang Li-Yuan Du Hong-Kun Zhu Zhi-Qiang Yu Da-Hu Yao Chang Lu School of Chemical Engineering and Pharmacy Henan University of Science and Technology

In order to acquire the structure information of explosive molecular with high-precision theoretical level and low time consuming, Nitroethane(NE), 1,1-diamino-2,2-dinitroethylene(FOX-7),Nitroguanidine(NQ), 2,4,6-trinitrotoluene(TNT) and 3-nitro-1,2,4-pyrrol-5-one(NTO) were choose as studying object, the geometry optimization of the five molecules were firstly performed with the Gaussian09 using density functional theory(DFT) at the m062x/6-31g+** level, then the quantum chemical information and single point energy calculation time of the five explosive molecules are calculated and compared with ORCA at m062x/aug-cc-pvdz, b2plyp-d3/aug-cc-pvdz,ri-b2plyp/aug-cc-pvdz,mp2/aug-cc-pvdz, ri-mp2/aug-cc-pvdz level respectively. The following results were achieved: DFT method only suitable for geometry pre-optimizing due to the worst precision but lowest time consuming;Double-hybrid functional method or two order perturbation method result in best precision but the most time consuming;Double-hybrid functional method or two order perturbation method with the resolution-of-the-identity(RI) approximation obtained a relatively high-precision result with an acceptable time, show great potential applications in quantum-chemistry study on explosive molecules.

关键词： explosive molecular potential function quantum chemistry geometry optimization resolution-of-the-identity approximation

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尿嘧啶与水分子间相互作用的DFT研究（英文）

尿嘧啶与水分子间相互作用的DFT研究（英文）

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中国化学会第四届有机化学学术会议

作者：方国勇胡新根徐丽娜李新华方盈盈温州大学化学与材料科学学院温州大学化学与材料科学学院温州大学化学与材料科学学院温州大学化学与材料科学学院温州大学化学与材料科学学院

＜正＞Four fully optimized geometries of uracil-water complexes have been obtained with density function theory （DFT） method at the B3LYP/6-311++G** level. The intermolecular interaction energy is calculated with zero point energy （ZPE） correction and basis set superposition error （BSSE） correction. The greatest corrected intermolecular interaction of the uracil-water complexes is -31.503KJ/mol. Natural bond orbital （NBO） analysis is performed to reveal the origin of the interaction. The strong hydrogen bonds contribute to the interaction energies dominantly. Frequency calculations are carried out on each optimized structure, and their IR spectra are discussed. Vibrational analysis show that there are large red-shifts for H-X （X=O, N and C） stretching vibrational frequencies in the uracil and water complexes. The changes of thermodynamic properties from the monomer to complexes with the temperature ranging from 200K to 800K have been obtained using the statistical thermodynamic method. It is found that four uracil-water complexes can be produced spontaneously from uracil and H,O at lower temperature.

关键词： uracil uracil-water complex Density functional theory Intermolecular interaction geometry optimization Natural bond orbital analysis IR spectra Thermodynamic property

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