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International Journal of Mining Science and Technology 2019年第3期29卷 399-408页

作者： Shahriyar Heidarzadeh Ali Saeidi Alain Rouleau Department of Applied Sciences University of Quebec at Chicoutimi

Stress-induced failure is among the most common causes of instability in Canadian deep underground mines.Open stoping is the most widely practiced underground excavation method in these mines,and creates large stopes which are subjected to stress-induced failure.The probability of failure(POF)depends on many factors,of which the geometry of an open stope is especially important.In this study,a methodology is proposed to assess the effect of stope geometrical parameters on the POF,using numerical modelling.Different ranges for each input parameter are defined according to previous surveys on open stope geometry in a number of Canadian underground mines.A Monte-Carlo simulation technique is combined with the finite difference code FLAC3D,to generate model realizations containing stopes with different geometrical features.The probability of failure(POF)for different categories of stope geometry,is calculated by considering two modes of failure;relaxation-related gravity driven(tensile)failure and rock mass brittle failure.The individual and interactive effects of stope geometrical parameters on the POF,are analyzed using a general multi-level factorial design.Finally,mathematical optimization techniques are employed to estimate the most stable stope conditions,by determining the optimal ranges for each stope’s geometrical parameter.

关键词： Stope stability Stope geometrical parameters Probability of failure General factorial design Numerical modeling Sublevel open stoping

Bending fracture behavior of freestanding (Gd0.9Yb0.1)2Zr2O7 coatings by using digital image correlation and FEM simulation with 3D geometrical reconstruction

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Journal of Advanced Ceramics 2019年第4期8卷 564-575页

作者： Weiguo MAO Yujie WANG Jun SHI Huiyu HUANG Yuncheng WANG Liang LV Haoyong YANG Chen ZOU Cuiying DAI Xiaolei ZHU Daining FANG School of Materials Science and Engineering Xiangtan UniversityXiangtan 411105China Department of Science and Technology Engineering AECC South Industry Co.Ltd.Xiangtan 412002China School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 210009China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

It is important to investigate the mechanical performances of (Gd0.9Yb0.1)2Zr2O7 (GYbZ) materials deposited on irregular substrates for improving new thermal barrier coatings. Three-point bending fracture characteristics of freestanding GYbZ coating prepared by supersonic plasma sprayed(SPS) technique were investigated with the help of digital image correlation technique. The cracking time, crack propagation path, and mechanical properties of GYbZ coating were obtained. Meanwhile, the X-ray computed tomography technique was introduced to scan the microstructure of freestanding GYbZ coatings, which are used to establish three-dimensional(3D) finite element model by using the Avizo software. The brittle cracking criterion was applied to describe the bending fracture process of GYbZ coatings. The critical cracking strain was estimated as 0.36%±0.03% by repeatedly comparing the difference between the experimental and simulated curves. The results would be extended to predict the dangerous region and failure mechanisms of GYbZ coatings deposited on irregular substrate during finite element simulations.

关键词： thermal barrier coating X-ray computed tomography bending fracture geometrical reconstruction cracking strain

Effects of geometrical and physical factors on light particles dispersion by agitation characteristic curve

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2313-2324页

作者： Meng Li Yangbo Tan Yufeng Liu Jianglong Sun De Xie Zeng Liu School of Naval Architecture and Ocean Engineering Huazhong University of Science and TechnologyWuhan 430074China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration(CISSE) Shanghai 200240China Hubei Key Laboratory of Naval Architecture and Ocean Engineering Hydrodynamics(HUST) Wuhan 430074China

In this study,the effects of geometrical and physical factors on light particles dispersion in stirred tank were investigated by agitation characteristic curve.The experiments and CFD simulations with discrete phase model(DPM)and volume of fluid model(VOF)were conducted in this paper.Five factors,which include four geometrical factors(submergence,impeller-to-tank ratio,number of impeller blades and baffling mode)and a physical factor(liquid viscosity)were considered.For each factor,the power consumption curve and agitation characteristic curve were drawn to compare the power consumption and mixing results in the stirred tank.Characteristics of the agitation characteristic curves were compared with the previous published literatures and theories.It is found that the agitation characteristic curves reflect the tendency of power consumption and particles distribution well in stirred tank.The good agreement indicates the applicability of the agitation characteristic curves for the study of light particles distribution in stirred tank.

关键词： Agitation characteristic curve geometrical and physical factors Light particles Solid–liquid mixing Stirred tank

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 structures.The geometrical nonlinearity is firstly included to reflect the structural response and the joint load distribution under large deformation.To 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 fasteners.During nonlinear analysis and optimization,a novel implementation of adjoint vector sensitivity analysis along with super element condensation is introduced to address numerical instability issues.The degrees of freedom of weak regions are condensed so that their influences are excluded from the iterative Newton-Raphson(NR)solution.Numerical examples are presented to validate the efficiency and robustness of the proposed method.The 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

The role of geometrical features in the architecturalstructural interaction:Some case studies of the Iranian ancient architecture

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Frontiers of Structural and Civil Engineering 2019年第3期13卷 716-724页

作者： Maryam ZANDIYEHVAKILI Isa HOJAT Mehdi MAHMUDI Faculty of Architecture and Urban Development Art University of IsfahanIsfahanIran Faculty of Architecture College of Fine ArtsUniversity of TehranTehranIran

This research aims to enhance the interaction between a structure and its architectural form.Having a qualitative approach,the present work discovers some successfully used geometrical features of the Iranian ancient architecture in terms of the architectural-structural interaction.We define four qualitative criteria for this assessment,i.e.,construction-ability,cost effectiveness,participation of the structure in fulfillment of the visual,and functional-semantic needs of the architectural form.For this purpose,two case studies including the Jame Mosque of Isfahan and the Soltaniyeh building are investigated.The outcomes of this research help designers to not only design efficient structures by adapting non-load bearing elements with the general form of the structure,but also meet concepts such as the unity or perfectionism in the structure.

关键词： architectural-structural interaction geometrical features structure architectural form Iranian ancient architecture

Light trajectory in geometrical optics and metric optics

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Science China Mathematics 1997年第7期40卷 755-760页

作者：朱莳通沈文达 Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800China Department of Physics Shanghai UniversityShanghai 201800China

The light trajectory in an inhomogeneous medium is studied by the variation of Lagrangians L and which correspond to Fermat’s principle in the geometrical optics and the null geodesic in the metric optics,respectively.The relation between the metric coefficients of the three-dimensional space and of the four-dimensional space-time is established.The physical meaning of the equivalence and difference of both the descriptions is revealed.It is shown that Fermat’s principle is a direct result of the null geodesic.

关键词： light trajectory geometrical optics metric optics Fermat’s principle null geodesic.

The geometrical properties of parity and time reversal operators in two dimensional spaces

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Applied Mathematics(A Journal of Chinese Universities) 2019年第2期34卷 173-183页

作者： HUANG Min-yi YANG Yu WU Jun-de CHO Min-Hyung School of Mathematical Science Zhejiang UniversityHangzhou 310027People’s Republic of China Department of Mathematics National University of SingaporeSingapore 119076Republic of Singapore Department of Applied Mathematics Kumoh National Institute of TechnologyKyungbuk39177Korea

The parity operator P and time reversal operator T are two important operators in the quantum theory, in particular, in the PT -symmetric quantum theory. By using the concrete forms of P and T , we discuss their geometrical properties in two dimensional spaces. It is showed that if T is given, then all P links with the quadric surfaces;if P is given, then all T links with the quadric curves. Moreover, we give out the generalized unbroken PT -symmetric condition of an operator. The unbroken PT -symmetry of a Hermitian operator is also showed in this way.

关键词： PT -symmetry geometrical property unbroken condition

A geometrical and physical nonlinear finite element model for spatial thin-walled beams with arbitrary section

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Science China(Technological Sciences) 2010年第3期53卷 829-838页

作者： YANG QingShan 1 &WANG XiaoFeng 2 1 School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China 2 College of Civil Engineering,Tongji University,Shanghai 200092,China School of Civil Engineering Beijing Jiaotong University Beijing China College of Civil Engineering Tongji University Shanghai China

Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all considered.Thereafter,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are formulated.Ideal plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of Prandtle-Reuss.Elastoplastic stiffness matrix is derived by numerical integration on the basis of the finite segment method.Examples show that the developed model is feasible in analysis of thin-walled structures with high accuracy.

关键词： Spatial beams thin-walled structures geometrical and physical nonlinearity finite element arbitrary section

Analytical study of the effect of the geometrical parameters during the interaction of regular wave-horizontal plate-current

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Acta Oceanologica Sinica 2019年第5期38卷 10-20页

作者： Smail Naasse Meriem Errifaiy Chakib Chahine Laboratory Physics of Polymers and Critical Phenomena Hassan Ⅱ University Casablanca

The present work is an analytical study of the influence of geometrical parameters, such as length, thickness and immersion of the plate, on the reflection coefficient of a regular wave for an immersed horizontal plate in the presence of a uniform current with the same direction as the propagation of the incident regular wave. This study was performed using the linearized potential theory with the evanescent modes while searching for complex roots to the dispersion equation that are neither pure real nor pure imaginary. The results show that the effects of the immersion and the relative length on the reflection coefficient of the plate are accentuated by the presence of the current, whereas the plate thickness practically does not have an effect if it is relatively small.

关键词： current regular wave evanescent modes reflection dispersion equation complex roots geometrical parameters

Numerical study on the influence of geometrical parameters on natural convection cooling effect of the crushed-rock revetment

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Science China(Technological Sciences) 2009年第2期52卷 539-545页

作者： ZHANG MingYi CHENG GuoDong LI ShuangYang State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhou 730000China

The crushed-rock revetment, considered as a highly porous medium, is often applied to embankment slope to protect the underlying permafrost and ensure the thermal stability of roadway in permafrost regions. In this paper, in order to increase and optimize the cooling capacity of crushed-rock revetment in cold regions roadway engineering, based on the thermal convection theories, the practical geometry and the temperature characteristics of in-situ crushed-rock revetment, convective pattern and cooling effect of crushed-rock revetment are numerically studied, with a thickness of 1.0 m under different geometrical parameters, e.g. sloped angle and aspect ratio. The results indicate that, with a thickness of 1.0 m and a temperature difference of 10.0 ℃ between top and bottom boundaries, due to the existence of natural convection, the effective thermal conductivity of crushed-rock revetment can be increased and the thermal "semi-conductor" characteristics are endowed. However, the convective pattern changes with the variation of the sloped angle, namely, with the increase of the sloped angle, the convection cell number decreases; furthermore, when the flow changes from various cells to a single cell at a sloped angle, the Nu number is the smallest and the cooling effect is the worst, therefore, the corresponding sloped angle is considered as the worst cooling sloped angle. Besides, with the increase of the aspect ratio, the worst cooling sloped angle increases and tends to 32°, also approaching to the in-situ crushed-rock revetment angle 33.7°. Therefore, when the crushed-rock revetment em-bankment is too high, that is to say, the aspect ratio of the sloped crushed-rock revetment is too large, some measures should be taken to enhance its cooling effect, which have been researched and discussed in this paper. It is hoped that some scientific references can be supplied to the design and maintenance of the crushed-rock revetment embankment in cold regions.

关键词： crushed-rock revetment geometrical parameter Nu number convection pattern cooling effect