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Transient vibration of thin viscoelastic orthotropic plates

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Acta Mechanica Sinica 2011年第1期27卷 98-107页

作者： j.Soukup F.Vale j.Volek j.Skoilas jan Evangelista Purkyně University in ústí nad Labem Faculty of Production Technology and Management Department of Machinery and Mechanics Centre of Material Diagnostics Institute of Thermomechanics AS CR v.v.i Academy of Sciences Czech Republic

This article deals with solutions of transient vibration of a rectangular viscoelastic orthotropic thin 2D plate for particular deformation models according to Flu¨gge and *** linear model,a general standard viscoelastic body,of the rheologic properties of a viscoelastic material was *** time and coordinate curves of the basic quantities displacement,rotation,velocity,stress and deformation are *** results obtained by an approximate analytic method are compared with numerical results for 3D plate generated by FEM application and with experimental investigation.

关键词： Transient vibration thin plate Orthotropic General viscoelastic standard solid.

Development of mathematical model with a genetic algorithm for automatic arc welding process

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Acta Metallurgica Sinica(English Letters) 2010年第3期23卷 230-240页

作者： D.T.Thao I.S.Kim j.W.jeong j.H.Lee j.Y.Shim H.H.Kim Department of Mechanical Engineering Mokpo National University

This paper is to represent new algorithms to predict process parameters on top-bead width in robotic gas metal arc（GMA） welding *** models have been developed：linear, curvilinear and intelligent model based on full factorial design with two *** analysis was employed for optimization of the coefficients of linear and curvilinear models, while genetic algorithm（ga） was utilized to estimate the coefficients of an intelligent *** only the fitting of these models were checked and compared by using a variance test（ANOVA）, but also the prediction on top-bead width using the developed models were carried out based on the additional *** developed models were employed to investigate the characteristic between process parameters and top-bead *** solutions and graphical representation showed that the intelligent model developed can be employed for prediction of bead geometry in GMA welding process.

关键词： Top-bead width Genetic algorithm Multiple regression Robotic arc welding GMA welding

3d-visualization of magnesium strengthening mechanisms for a description of experimentally obtained data of alloying effect in Mg-ga system

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journal of Magnesium and Alloys 2020年第2期8卷 546-551页

作者： j.A.Khokhlova M.A.Khokhlov Paton Electric Welding Institute of National Academy of Sciences of Ukraine KyivUkraine

Based on laws of theory of materials strengthening were discribed the experimentally obtained alloying effect in Mg-ga system and shown using program for 3d atomic *** known from our experiments a homogeneous"wavy"microstructure of the diffusion zone forms as result of mass-transfer of molten gallium into the volume of magnesium *** chemical composition shows Mg 65%*** ga 35%*** X-ray spectra diffraction data-Mg5ga2 intermetallic phase *** intermetallic diffusion zone provides the significant strengthening effect of microstructure which was determined experimentally by the indentation *** 3-d visualization shows the reaction and changing of an original crystal structure of magnesium atomic lattice upon diffusion doping with foreign atoms of gallium and then is shown the coalescence of Mg5ga2 intermetallic crystal with crystals surfaces of ***,investigated Mg-alloy strengthening at alloying with ga explained by two main *** first is the formation of intermetallic phases with the ordering and consolidation of the crystal structure of the matrix by the ligature atoms,which is the key factor of the strengthening mechanism fixed ***,when hexagonal and orthorhombic atomic structures growth according to their spatial type,a significant disorientation of structural fragments occurs,an increase in the density of the amorphous transition layer,a twinning of the structure in the interphase boundaries,which leads to the formation of intrinsic mutual deformation and a high level of internal stresses.

关键词： Magnesium gallium Alloying Strengthening Atom 3d

MANY-SERVER QUEUES WITH CUSTOMER ABANDONMENT:A SURVEY OF DIFFUSION AND FLUID APPROXIMATIONS

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journal of Systems Science and Systems Engineering 2012年第1期21卷 1-36页

作者： j. G. DAI Shuangchi HE H. Milton Stewart School of Industrial and Systems Engineering Georgia Institute of Technology Atlanta GA 30332 USA. Department of Industrial and Systems Engineering National University of Singapore Singapore 11757

The performance of a call center is sensitive to customer abandonment. In this survey paper, we focus on G/GI/n ＋ GI parallel-server queues that serve as a building block to model call center operations. Such a queue has a general arrival process （the G ）, independent and identically distributed （iid） service times with a general distribution （the first G1 ）, and iid patience times with a general distribution （the ＋GI）. Following the square-root safety staffing rule, this queue can be operated in the quality- and efficiency-driven （QED） regime, which is characterized by large customer volume, the waiting times being a fraction of the service times, only a small fraction of customers abandoning the system, and high server utilization. Operational efficiency is the central target in a system whose staffing costs dominate other expenses. If a moderate fraction of customer abandonment is allowed, such a system should be operated in an overloaded regime known as the efficiency-driven （ED） regime. We survey recent results on the many-server queues that are operated in the QED and ED regimes. These results include the performance insensitivity to patience time distributions and diffusion and fluid approximate models as practical tools for performance analysis.

关键词： Heavy traffic square-root safety staffing quality- and efficiency-driven regime efficiency-driven regime piecewise OU process

Power Factor Estimation of Distributed Energy Resources Using Voltage Magnitude Measurements

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journal of Modern Power Systems and Clean Energy 2021年第4期9卷 859-869页

作者： Samuel Talkington Santiago Grijalva Matthew j.Reno School of Electrical and Computer Engineering Georgia Institute of TechnologyAtlantaGA 30318USA Electric Power Systems Research Department Sandia National LaboratoriesAlbuquerqueNM 87123USA

This paper presents a new method for the estimation of the injection state and power factor of distributed energy resources (DERs) using voltage magnitude measurements only. A physics-based linear model is used to develop estimation heuristics for net injections of real and reactive power at a set of buses under study, allowing a distribution engineer to form a robust estimate for the operating state and the power factor of the DER at those buses. The method demonstrates and exploits a mathematical distinction between the voltage sensitivity signatures of real and reactive power injections for a fixed power system model. Case studies on various test feeders for a model of the distribution circuit and statistical analyses are presented to demonstrate the validity of the estimation method. The results of this paper can be used to improve the limited information about inverter parameters and operating state during renewable planning, which helps mitigate the uncertainty inherent in their integration.

关键词： Decentralized power system control detection and estimation power factor sparse approximation

Capsule endoscopy in suspected small bowel Crohn's disease:Economic impact of disease diagnosis and treatment

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World journal of gastroenterology 2009年第45期15卷 5685-5692页

作者： jonathan A Leighton Ian M Gralnek Randel E Richner Michael j Lacey Frank j Papatheofanis Division of gastroenterology and Hepatology Mayo Clinic ScottsdaleAZ 85259United States Rappaport Faculty of Medicine Technion-Israel Institute of Technology GI Outcomes Unit Departments of Gastroenterology and Ambulatory Care Services Rambam Health Care Campus The Neocure Group SherbornMA 01770 United States Division of Health Policy Departments of Radiology and Economics University of California San DiegoSan Diego CA 92103United States

AIM: To model clinical and economic benef its of capsule endoscopy (CE) compared to ileo-colonoscopy and small bowel follow-through (SBFT) for evaluation of suspected Crohn’s disease (CD). METHODS: Using decision analytic modeling, total and yearly costs of diagnostic work-up for suspected CD were calculated, including procedure-related adverse events, hospitalizations, off ice visits, and medications. The model compared CE to SBFT following ileo-colonoscopy and secondarily compared CE to SBFT for initial evaluation. RESULTS: Aggregate charges for newly diagnosed, medically managed patients are approximately $8295. Patients requiring aggressive medical management costs are $29 508; requiring hospitalization, $49 074. At sensitivity > 98.7% and specifi city of > 86.4%, CE is less costly than SBFT. CONCLUSION: Costs of CE for diagnostic evaluationof suspected CD is comparable to SBFT and may be used immediately following ileo-colonoscopy.

关键词： Capsule endoscopy Costs Crohn's disease Disease management

微/纳米ZnO绒球的制备及光催化降解有机染料

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功能材料 2015年第6期46卷 6020-6025页

作者：佟拉嘎欧阳萍马小丽荣华北京石油化工学院化学工程学院北京102617

以谷氨酸G氟硼酸（GluBF4）离子液体水溶液为反应介质,以物质的量比为1∶6的二水合醋酸锌[Zn（Ac）2？？2H2O]和NaOH为原料,室温下制备前驱体,再微波辅助加热制备了微/纳米ZnO粉体,获得了单一形貌较高比表面积微/纳米ZnO绒球.利用扫描... 详细信息

以谷氨酸G氟硼酸（GluBF4）离子液体水溶液为反应介质,以物质的量比为1∶6的二水合醋酸锌[Zn（Ac）2？？2H2O]和NaOH为原料,室温下制备前驱体,再微波辅助加热制备了微/纳米ZnO粉体,获得了单一形貌较高比表面积微/纳米ZnO绒球.利用扫描电镜（SEM）、X射线衍射（XRD）、比表面（BET）、能谱（EDS）等对产物进行了结构与性能表征.所得产物为六方晶系纤锌矿结构,绒球直径在1.6-3.0μm之间,粒径平均尺寸20.4nm,绒球比表面积为28.3m^2/g,产物纯度高,收率95.6%.该纳米材料在自然光下表现出较高的光催化活性和形态稳定性.分别配制浓度为10mg/L的100mL甲基橙（methyl orange,MO）、溴甲酚绿（bromocresol green,BG）水溶液,30mg纳米ZnO为光降解催化剂,太阳光激发下5h脱色率分别达74.3%和86.4%,重复利用5次,催化剂形貌不变、重量未发生变化。

关键词：离子液体微波辅助加热微/纳米ZnO 光催化降解

Microstructure,magnetism and nanomechanical properties of Ni50Mn25ga20Gd5 magnetic shape memory alloy before and after heat treatment

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journal of Rare Earths 2019年第11期37卷 1224-1229页

作者： A.Laszcz M.Hasiak j.Kaleta Wroclaw University of Science and Technology Department of MechanicsMaterials Science and Engineering

Polycrystalline Ni50Mn25ga20Gd5(at%)magnetic shape memory alloy was investigated in the asprepared state and after annealing at 1430 K for 3 *** analysis reveals dual-phase nature of the material with substantial distinction between Gd-rich and Gd-poor *** measurements performed in wide range of temperatures confirm reversible martensitic transformation in the annealed sample undergoing close to the room *** it comes to the magnetic transition,the Curie temperature of the investigated alloy remains approximately unchanged at 370 *** investigations conducted on the atomic force microscope in contact mode allow to measure 8 mm difference between minimum and maximum point of the martensite *** results from a series of nanoindentation tests show that hardness of the Gd-rich phase is 23%-35%higher than hardness of the Gd-poor phase,depending on the annealing state.

关键词： NiMnga Magnetic shape memory alloys Reversible martensitic transition Gd-doped alloys Rare earths

Modelling Impact of Dredging and Dumping in Ebb-Flood Channel Systems

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Transactions of Tianjin University 2008年第4期14卷 271-281页

作者： HIBMA A WANG Z B STIVE M j F Vriend H j de Delft University of Technology P O Box 5048 2600 GA Delft the Netherlands

For a channel-shoal system in a funnel-shaped basin the impact of dredging and dumping is investigated using a complex process-based model. First, the residual flow and sediment transport circulations are analysed for the channel-shoal pattern, which has emerged after a longterm model simulation. Results are compared to the Western Scheldt estuary, which forms the inspiration for this study. Subsequently, different dredge and dump scenarios are modelled, according to a conceptual model, in which ebb- and flood-channels and enclosed shoals form morphodynamic units (cells) with their own sediment circulation. Model results show that dumping sediment in a channel further reduces the channel depth and induces erosion in the opposite channel, which enhances tilting of the cross-section of the cell and eventually can lead to the degeneration of a multiple channel system into a single channel. The impact of different dredging and dumping cases agrees with results from a stability analysis. This means that this type of model applied to a realistic geometry can potentially be used for better prediction of the impact of human interventions.

关键词： estuaries morphology numerical model channel shoal dredging dumping