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effect of near-fault earthquakes with forward directivity on telecommunication towers

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earthquake engineering and engineering Vibration 2011年第2期10卷 211-218页

作者： M.Yahyai b.Rezayibana e.Mohammadrezapour Department of Civil engineering K.N. Toosi University of Technology Islamic Azad University

In this paper, the effect of pulse-type motions caused by forward directivity that can release huge amounts of energy in a short time period is studied on a telecommunication tower. Since telecommunication towers have longer periods, they are not as affected by seismic forces. Nevertheless, near source earthquakes characterized by high velocity and velocity pulses can change the behavior of these structures. For this reason, a telecommunication tower located near active faults was selected in this study. Considering the probable earthquake magnitude at the site and the distance of the tower from adjacent faults, nine simulated pulses and three near-fault earthquake records with forward directivity are selected and applied to a 3D finite element model of the tower. The results of nonlinear dynamic analysis, i.e., displacements and damage in the tower, indicate that the maximum displacement and drift ratio of the tower under the pulses are obviously affected by the ratio of the structure period to pulse period. When this ratio is decreased and close to 1.0, the maximum displacement and drift ratio are sharply increased and cause large displacements in the tower.

关键词： near-fault earthquake velocity pulse nonlinear dynamic analysis drift ratio

enhancing economic sustainability in mature oil fields:Insights from the clustering approach to select candidate wells for extended shut-in

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Artificial Intelligence in Geosciences 2024年第1期5卷 173-188页

作者： b.Lobut e.Artun Istanbul Technical University Department of Petroleum and Natural Gas Eng.IstanbulTürkiye Sultan Qaboos University Department of Petroleum and Chemical Eng.MuscatOman

Fluctuations in oil prices adversely affect decision making situations in which performance forecasting must be combined with realistic price *** periods of significant price drops,companies may consider extended duration of well shut-ins(*** stopping oil production)for economic *** example,prices during the early days of the Covid-19 pandemic forced operators to consider shutting in all or some of their active *** the case of partial shut-in,selection of candidate wells may evolve as a challenging decision problem considering the uncertainties *** this study,a mature oil field with a long(50+years)production history with 170+wells is *** with similar conditions face many challenges related to economic sustainability such as frequent maintenance requirements and low production *** aimed to solve this decision-making problem through unsupervised machine *** reservoir characteristics at well locations,well production performance statistics and well locations are used as potential features that could characterize similarities and differences among *** reservoir characteristics are measured at well locations for the purpose of describing the subsurface reservoir,well performance consists of volumetric rates and pressures,which are frequently measured during oil *** a multivariate data analysis that explored correlations among parameters,clustering algorithms were used to identify groups of wells that are similar with respect to aforementioned *** the field’s reservoir simulation model,scenarios of shutting in different groups of wells were *** reservoir performance for three years was used for economic evaluation that assumed an oil price drop to$30/bbl for 6,12 or 18 *** of economic analysis were analyzed to identify which group(s)of wells should have been shut-in by also considering the sensitivity to different price *** was o

关键词： Unsupervised learning Clustering Mature oil fields extended shut-in Well classification

Refolding of reduced/denatured bovine pancreatic insulin with ion-exchange chromatography coupled with MALDI-TOF MS

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Chinese Chemical Letters 2009年第12期20卷 1487-1490页

作者： Cui e. Lin Quan b ai Institute of Modern Separation Science Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education Northwest University Xi'an 710069 China

The refolding of the reduced/denatured insulin from bovine pancreas as the model protein was investigated with weak anion exchange chromatography （WAX） coupled with MALDI-TOF MS. The results indicated that the disulfide bonds almost cannot be formed correctly with the common mobile phase by WAX. However, with the urea gradient elution and in the presence of GSSG/ Cyst as the ratio 1：6 in the mobile phase employed, the disulfide exchange of reduced/denatured insulin can be accelerated resulting in forming the correct three disulfide bonds. The protein refolding efficiency of reduced/denatured insulin can be increased from 3 % to 34%. The effects of urea gradient and the oxidant and reductant groups, such as GSSG/GSH, Cyst, and GSSG/Cyst, on the forming the disulfide bonds of reduced/denatured insulin were investigated in detail. The results were further tested by the separation of the WAX fraction of reduced/denatured insulin with RPLC and MALDI-TOF MS.

关键词： Protein refolding Liquid chromatography Reduced/denaturation Insulin MALDI-TOF MS

Seasonal variation of selected trace elements in rare endemic species Thuriferous Juniper growing in the Aurès Mountains of Algeria

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Journal of Forestry Research 2017年第2期28卷 249-254页

作者： M.e.bacha b.Nedjimi A.Ararem b.beladel Laboratory of exploration and Valorization of Steppe ecosystem Faculty of Science of Nature and LifeUniversity of DjelfaCite Ain ChihP.O.Box 3117Djelfa 17000Algeria Neutron Activation Analysis Department Nuclear Research Center of BirineP.O.Box 180Ain Oussera 17200Algeria

We used energy dispersive X-ray fluorescence（eDXRF） to determine the seasonal variation of selected trace elements（Cr, Mn, Zn, Cu, Se and Fe） and some potential toxic elements（Cd, Pb and br） in Juniperus thurifera subsp. africana Maire（Cupressaceae） a rare medicinal tree, growing indigenously in Aures Mountains of Algeria. The precision of the results was assessed by analyzing the certified reference material IPe44（WePAL）grass leaves. Results showed J. thurifera was characterized by high Cr and Mn contents. During autumn and winter mineral concentrations were higher in general. The levels of Cr, Se and Mn were higher during autumn and winter than during spring and summer. Zn contents were higher during summer than in other seasons. Cu content did not vary by season. The potential toxic elements in J. thurifera（Pb [ Cd [ br） were below the permissible limits recommended by the Joint WHO/FAO guidelines except for Pb in autumn and winter.

关键词： autumn winter seasonal certified eDXRF endemic subsp dispersive assessed medicinal

effects of nano-voids and nano-cracks on the elastic properties of a host medium: xfem modeling with level-set function and free surface energy

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Acta Mechanica Sinica 2019年第4期35卷 799-811页

作者： b.e. Hachi D. Hachi M. Haboussi Laboratoire de Développement en Mécanique et Matériaux (LDMM) Université de Djelfa PB 3117 Djelfa Algérie Laboratoire d’Automatique Appliquée et Diagnostics Industriels (LAADI) Université de Djelfa PB 3117 Djelfa Algérie Laboratoire des Sciences des Procédés et des Matériaux (LSPM) Université Paris 13 UPR 3407 CNRS Paris France

This work deals with the influences of nano-heterogeneities in the form of voids/cavities or cracks on the elastic (please confirm which word is correct. effective or elastic? According to the title of paper, I choose elastic.) properties of a host medium. With a relatively large ratio of apparent-surface to volume and particularly strong physical interactions with the surrounding medium at nano-scale, nano-heterogeneities can potentially affect the elastic(effective or elastic?) properties of the parent medium (matrix) containing them in a significant manner. This has been reported by various theoretical and experimental studies, some of them are discussed in the present paper. To describe the positive (reinforcement) or negative (degradation) effect of the nano-heterogeneities from the modeling perspective, it is necessary to take into account the energy of interfaces/surfaces between nano-heterogeneities and the matrix which, by the fact of the relatively large extent of their apparent surface and their strong physical interaction with their neighborhood, can no longer be neglected compared to those of the volume energy. Thus, to account for the effects of interfaces/surfaces in a nanostructured heterogeneous medium, the coherent interface model is considered in the present investigation within a periodic homogenization procedure. In this interface/surface model, the displacement vector is assumed to be continuous across the interface while the stress vector is considered to be discontinuous and satisfying the Laplace-Young equations. To solve these equations coupled to the classical mechanical equilibrium problem, a numerical simulation tool is developed in a two-dimensional (2D) context using the eXtended Finite element Method (XFeM) and the Level-Set functions. The developed numerical tool is then used to carry out a detailed analysis about the effect of nano-heterogeneities on the overall mechanical properties of a medium. The nano-heterogeneities are present

关键词： Interface/Surface energy XFeM Level-Set function Periodic homogenization Nano-voids/Nano-cavities Nano-cracks Nano-inclusions/Nano-heterogeneities

On q-n-gonal Klein Surfaces

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Acta Mathematica Sinica,english Series 2007年第10期23卷 1833-1844页

作者： b.eSTRADA R.A.HIDALGO e.MARTINeZ Departamento de Matemáticas Fundamentales UNEDPaseo Senda del Rey 928040 MadridSpain Departamento de Matemática Universidad Técnica Federico Santa MaríaCasilla 110-V ValparaisoChile

We consider proper Klein surfaces X of algebraic genus p ≥ 2, having an automorphism φ of prime order n with quotient space X/（φ） of algebraic genus q. These Klein surfaces axe called q-n-gonal surfaces and they are n-sheeted covers of surfaces of algebraic genus q. In this paper we extend the results of the already studied cases n ≤ 3 to this more general situation. Given p ≥ 2, we obtain, for each prime n, the （admissible） values q for which there exists a q-n-gonal surface of algebraic genus p. Furthermore, for each p and for each admissible q, it is possible to check all topological types of q-n-gonal surfaces with algebraic genus p. Several examples are given： q-pentagonal surfaces and q-n-gonal bordered surfaces with topological genus g = 0, 1.

关键词： Klein surfaces Riemann surfaces automorphism groups non-euclidean crystallographic groups

Microstructural Analysis of Ultrasonic Welded AA6061 by electron backscattered Diffraction

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稀有金属材料与工程 2009年第A03期38卷 147-151页

作者： Zhu Z Wynne b P Ghassemieh e Siddiq A Nanchang University Nanchang 330031 China University of Sheffield Sheffield S1 3JD UK IMMPeTUS Institute for Microstructural and Mechanical Process Engineering University of Sheffield Sheffield S 1 3JD UK

Ultrasonic welding can be used to join plastic and metal through high-frequency (more than 20 kHz) acoustic vibrations. Aluminium alloy is widely used in electronics, automotive and aerospace. The mechanical vibrations used during ultrasonic metal welding are introduced horizontally. During ultrasonic metal welding, a complex process is triggered involving static forces, oscillating shearing forces and a moderate temperature increase in the welding area. As the energy is introduced to the weld zone, there are three important phenomena occurring which are surface effect, volume effect and thermal effect. As it is known, microstructure is directly linked to the mechanical properties including fatigue resistance, fatigue life and fracture strength. So the microstructure analysis is important to evaluate the ultrasonically welded aluminium alloy’s properties. Also, mechanical properties of metal sheets, such as plastic anisotropy and formability, can be improved by a proper crystallographic texture control. That means the texture has great influence on the plastic anisotropy of the final recrystallized sheets. Optical microscopy (OM) can be used for showing the grain size and grain shape. However, to examine the relationship between mechanical behaviour and microstructure of the weldment, optical microscopy(OM) is not sufficient. OM cannot delineate a grain structure in the weld zone. The etched surface exhibited granularity at the micron level, but it was not clear if that reflected the grain structure. electron backscatter diffraction (ebSD) in an SeM has become the most widely used technique for determination of microtexture. In this research, high-resolution electron backscatter diffraction is used to study the effects of the vibration on the evolution of microstructure in AA6061. The orientation image maps (OIM), polar figures (PF), and orientation distribution functions (ODF) of the samples are obtained. The characteristics of the crystallographic orientation, the

关键词：超声波焊接塑料复合材料抗疲劳强度

CRYSTALLOGRAPHIC HOMOGeNIZATION FINITe eLeMeNT MeTHOD AND ITS APPLICATION ON SIMULATION OF eVOLUTION OF PLASTIC DeFORMATION INDUCeD TeXTURe

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Acta Mechanica Solida Sinica 2010年第1期23卷 36-48页

作者： Yiping Chen W.b. Lee e. Nakamachi Department of Mechanics Huazhong University of Science and Technology Wuhan 430074 China State Key Laboratory for Forming Simulation and Die and Mould Technology Huazhong University of Science and Technology Wuhan 430074 China Department of Industrial and Systems engineering The Hong Kong Polytechnic University Hong Kong China Department of Mechanical engineering Osaka Institute of Technology Osaka Japan

A crystallographic homogenization method is proposed and implemented to predict the evolution of plastic deformation induced texture and plastic anisotropy （earring） in the stamping of polycrystalline sheet metals. The microscopic inhomogeneity of crystal aggregate has been taken into account with the microstructure made up of a representative aggregate of single crystal grains. Multi-scale analysis is performed by coupling the microscopic crystal plasticity with the macroscopic continuum response through the present homogenization procedure. The macroscopic stress is defined as the volume average of the corresponding microscopic crystal aggregations, which simultaneously satisfies the equation of motion in both micro- and macro-states. The proposed numerical implementation is based on a finite element discretization of the macrocontinuum, which is locally coupled at each Gaussian point with a finite element discretization of the attached micro-structure. The solution strategy for the macro-continuum and the pointwiseattached micro-structure is implemented by the simultaneous employment of dynamic explicit Fe formulation. The rate-dependent crystal plasticity model is used for the constitutive description of the constituent single crystal grains. It has been confirmed that Taylor＇s constant strain homogenization assumption yields an undue concentration of the preferred crystal orientation compared with the present homogenization in the prediction of texture evolution, with the latter having relaxed the constraints on the crystal grains. Two kinds of numerical examples are presented to demonstrate the capability of the developed code： 1） The texture evolution of three representative deformation modes, and 2） Plastic anisotropy （earring） prediction in the hemispherical cup deep drawing process of aluminum alloy A5052 with initial texture. by comparison of simulation results with those obtained employing direct crystal plasticity calculation adopting Taylor assumption,

关键词： homogenization crystal plasticity texture microstructure earring

energy of Grain boundaries of Different Type in fcc Solid Solutions,Ordered Alloys and Intermetallics with L1_2 Superstructure

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Journal of Materials Science & Technology 2003年第6期19卷 593-596页

作者： O.b.Perevalova e.V.Konovalova N.A.Koneva e.V.Kozlov Institute of Strength Physics and Materials Science Russian Academy of Science Siberian Branch Russia TomskState University of Architecture and Building Russia TomskState University of Architecture and Building Russia TomskState University of Architecture and Building Russia Tomsk

The study of the triple junctions of the grain boundaries in some fee solid solutions, ordered alloys and intermetallics with L12 has been carried out using the optical metallography and TeM methods. Two-types of the triple junctions were found in the alloys investigated (1), consisting of the boundaries of the random (RT), and (2), consisting of the RT boundary and the special boundaries (ST). The relative values of the RT and ST boundary energy were determined on the basis of the measurements of the angles between the grain boundary planes. It has been shown that the energy of ST boundaries increases with the increase of the stacking fault (SF) energy. The energy of the RT boundaries does not depend on the SF energy.

关键词： Alloys Grain boundary energy Stacking fault Anti-phase-boundary