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Novel decoupled framework for reliability-based design optimization of structures using a robust shifting technique

Frontiers of Structural and Civil Engineering 2019年第4期13卷 800-820页

作者： Mohammad Reza GHASEMI Charles V. CAMP babak DIZANGIAN Department of Civil Engineering University of Sistan and Baluchestan Zahedan *** Iran Department of Civil Engineering The University of Memphis Memphis TN 38152 USA Department of Civil Engineering Velayat University Iranshahr *** Iran

In a reliability-based design optimization (RBDO), computation of the failure probability (Pf) at all design points through the process may suitably be avoided at the early stages. Thus, to reduce extensive computations of RBDO, one could decouple the optimization and reliability analysis. The present work proposes a new methodology for such a decoupled approach that separates optimization and reliability analysis into two procedures which significantly improve the computational efficiency of the RBDO. This technique is based on the probabilistic sensitivity approach (PSA) on the shifted probability density function. Stochastic variables are separated into two groups of desired and non-desired variables. The three-phase procedure may be summarized as: Phase 1, apply deterministic design optimization based on mean values of random variables;Phase 2, move designs toward a reliable space using PSA and finding a primary reliable optimum point;Phase 3, applying an intelligent self-adaptive procedure based on cubic B-spline interpolation functions until the targeted failure probability is reached. An improved response surface method is used for computation of failure probability. The proposed RBDO approach could significantly reduce the number of analyses required to less than 10% of conventional methods. The computational efficacy of this approach is demonstrated by solving four benchmark truss design problems published in the structural optimization literature.

关键词： reliability-based design optimization trusses sensitivity analysis shifting technique cubic B-splines response surface method

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Formation mechanism of Al2O3/MoS2 nanocomposite coating by plasma electrolytic oxidation(PEO)

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Plasma Science and Technology 2020年第6期22卷 144-155页

作者： babak GHORBANIAN Mohammad TAJALLY Seyed Mohammad MOUSAVI KHOIE Hossein TAVAKOLI Faculty of Materials and Metallurgical Engineering Semnan UniversityPO Box 35131-19111SemnanIran Faculty of Mining and Metallurgical Engineering Amirkabir University of TechnologyPO Box 15875-4413 TehranIran

In this study,an Al2O3/MoS2 nanocomposite coating was created on an aluminum 1050 substrate using the plasma electrolytic oxidation *** zeta potential measurements showed that small MoS2 particles have negative potential and move toward the anode *** nanoparticles of MoS2 were found to have a zeta potential of-25 mV,which prevents suspension in the ***,to produce an Al2O3/MoS2 nanocomposite,one has to use the microparticles of *** X-ray diffraction analyses showed that the produced coatings containedα-Al2O3,γ-Al2O3,and MoS2,and that the size of MoS2 particles can be reduced to 30 *** was observed that prolonged suspension in the electrolyte results in an enhanced formation of an Al2O3/MoS2 *** the results,it was hypothesized that the mechanism of the formation of the Al2O3/MoS2 nanocomposite coating on the aluminum 1050 substrate is based on electrical energy discharge.

关键词： plasma electrolytic oxidation corrosion Al2O3/MoS2 nanocomposite tribology

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Ab initio prediction of fast non-equilibrium transport of nascent polarons in SrI2: a key to high-performance scintillation

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npj Computational Materials 2016年第1期2卷 77-83页

作者： Fei Zhou babak Sadigh Paul Erhart Daniel Åberg Physical and Life Sciences Directorate Lawrence Livermore National LaboratoryLivermoreCAUSA Department of Physics Chalmers University of TechnologyGothenburgSweden

The excellent light yield proportionality of europium-doped strontium iodide(SrI2:Eu)has resulted in state-of-the-artγ-ray detectors with remarkably high-energy resolution,far exceeding that of most halide *** this class of materials,the formation of self-trapped hole polarons is very ***,polaron formation is usually expected to limit carrier mobilities and has been associated with poor scintillator light-yield proportionality and *** using a recently developed first-principles method,we perform an unprecedented study of polaron transport in SrI2,both for equilibrium polarons,as well as nascent polarons immediately following a self-trapping *** propose a rationale for the unexpected high-energy resolution of *** identify nine stable hole polaron configurations,which consist of dimerised iodine pairs with polaron-binding energies of up to 0.5 *** are connected by a complex potential energy landscape that comprises 66 unique nearest-neighbour migration *** initio molecular dynamics simulations reveal that a large fraction of polarons is born into configurations that migrate practically barrier free at room ***,carriers created duringγ-irradiation can quickly diffuse away reducing the chance for nonlinear recombination,the primary culprit for non-proportionality and resolution *** conclude that the flat,albeit complex,landscape for polaron migration in SrI2 is a key for understanding its outstanding *** insight provides important guidance not only for the future development of high-performance scintillators but also of other materials,for which large polaron mobilities are crucial such as batteries and solid-state ionic conductors.

关键词： polaron equilibrium iodine

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Effect of Ocean Iron Fertilization on the Phytoplankton Biological Carbon Pump

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Advances in Applied Mathematics and Mechanics 2011年第1期3卷 52-64页

作者： Adam Pan babak Pourziaei Huaxiong Huang Department of Mathematics and Statistics York UniversityTorontoOntarioCanada M3J 1P3 Program of Engineering Science University of TorontoTorontoOntarioCanada M5S 1A1

It has been proposed that photosynthetic plankton can be used as a biological carbon pump tp absorb and sequester carbon dioxide in the *** this paper,plankton population dynamics are simulated in a single stratified water column to predict carbon dioxide sequestering due to surface iron fertilization in deep *** a predator-prey model and realistic parameter values,iron fertilization was found to only cause temporary blooms up to 5 months in duration,and relatively small increases in adsorption of atmospheric CO_(2).

关键词： Phytoplankton carbon dioxide iron fertilization carbon pump

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Comparison of the effects of acute and chronic psychological stress on metabolic features in rats

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2012年第11期13卷 904-912页

作者： Fatemeh ROSTAMKHANI Homeira ZARDOOZ Saleh ZAHEDIASL babak FARROKHI Neuroscience Research Center Shahid Beheshti University of Medical SciencesTehranIran Department of Biology Shahre-Rey BranchIslamic Azad UniversityTehranIran Department of Physiology Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran Endocrine Research Center Research Institute for Endocrine SciencesShahid Beheshti University of Medical SciencesTehranIran Department of Immunology Faculty of MedicineShahid Beheshti University of Medical SciencesTehranIran

This study was aimed to compare the effects of acute and chronic psychological stress on metabolic factors. Forty-two male Wistar rats were divided into control and stressed groups. Stress was applied by a communication box acutely (1 d) and chronically (15 and 30 d). Blood sampling was carried out by retro-orbital-puncture method. The plasma levels of glucose, cholesterol, triglyceride, insulin, and corticosterone were measured. In addition, feed and water intake, latency to eat and drink, adrenal and body weights were determined. Acute and chronic psychological stress did not significantly change basal plasma corticosterone levels. However, immediately (1 min) after acute exposure to stress, plasma corticosterone level increased compared to that before stress exposure. Acute stress increased plasma insulin levels significantly. Fifteen days of stress exposure resulted in plasma glucose increase. Chronic stress significantly increased feed intake, latency to eat, and adrenal weight compared to acute stress. The body weights of both control and stressed groups increased markedly during the experiment. Homeostasis model assessment of insulin resistance (HOMA-IR) index did not change significantly in the stressed group. In conclusion, application of acute and chronic psychological stress leads to different metabolic and/or behavioral changes but the metabolic changes resulting from acute exposure to stress seem to be more pronounced.

关键词： Psychological stress Corticosterone Insulin Glucose Cholesterol Triglyceride

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Phosphine-free conversion of alcohols into alkyl thiocyanates using trichloroisocyanuric acid/NH_4SCN

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Chinese Chemical Letters 2012年第1期23卷 77-80页

作者： Roya Azadi babak Mokhtari Mohamad-Ali Makaremi Department of Chemistry College of ScienceShahid Chamran UniversityAhvaz 61357-43337Iran

A convenient and efficient phosphine-free procedure for the one-pot conversion of primary,secondary and tertiary alcohols into the corresponding alkyl thiocyanates or alkyl isothiocyanates is described using trichloro... 详细信息

关键词： Phosphine-free Alcohol Thiocyanate Trichloroisocyanuric acid Thiocyanation

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Heavy metals and their source identification in particulate matter(PM_(2.5)) in Isfahan City, Iran

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Journal of Environmental Sciences 2018年第10期30卷 166-175页

作者： Mohsen Soleimani Nasibeh Amini babak Sadeghian Dongsheng Wang Liping Fang Department of Natural Resources Isfahan University of Technology Isfahan's Department of Environment Division of Environmental Monitoring State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Faculty of Material Science and Chemistry China University of Geosciences

The presence of heavy metals（HMs） in particulate matters（PMs） particularly fine particles such as PM2.5 poses potential risk to the health of human being. The purpose of this study was to analyze the contents of HMs in PM2.5 in the atmospheric monitoring stations in Isfahan city,Iran, in different seasons between March 2014 and March 2015 and their source identification using principle component analysis（PCA）. The samples of PM2.5 were taken using a high volume sampler in 7 monitoring stations located throughout the city and industrial zones since March 2014 to March 2015. The HMs content of the samples was measured using *** results showed that the concentrations of As, Cd and Ni were in a range of 23–36, 1–12,and 5–76 ng/m3 at all the stations which exceeded the US-EPA standards. Furthermore,the concentrations of Cr and Cu reached to 153 and 167 ng/m3 in some stations which were also higher than the standard levels. Depending on the potential sources of HMs, their concentration in PM2.5 through the various seasons was different. PCA illustrated that the different potential sources of HMs in the atmosphere, showing that the most important sources of HMs originated from fossil fuel combustion, abrasion of vehicle tires, industrial activities（e.g., iron and steel industries） and dust storms. Management and control of air pollution of industrial plants and vehicles are suggested for decreasing the risk of the HMs in the region.

关键词： Air pollution Heavy metals Particulate matters Principle component analysis

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In Situ Mineralization of Biomass-Derived Hydrogels Boosts Capacitive Electrochemical Energy Storage in Free-Standing 3D Carbon Aerogels

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Energy & Environmental Materials 2024年第2期7卷 359-371页

作者： Anjali Achazhiyath Edathil babak Rezaei Kristoffer Almdal Stephan Sylνest Keller National Centre for Nano Fabrication and Characterization DTU NanolabTechnical University of Denmark2800LyngbyDenmark DTU Chemistry Technical University of Denmark2800LyngbyDenmark

Here,a novel fabrication method for making free-standing 3D hierarchical porous carbon aerogels from molecularly engineered biomass-derived hydrogels is *** situ formed flower-like CaCO_(3)molecularly embedded within the hydrogel network regulated the pore structure during in situ mineralization assisted one-step activation graphitization(iMAG),while the intrinsic structural integrity of the carbon aerogels was *** homogenously distributed minerals simultaneously acted as a hard template,activating agent,and graphitization *** decomposition of the homogenously distributed CaCO_(3)during iMAG followed by the etching of residual CaO through a mild acid washing endowed a robust carbon aerogel with high porosity and excellent electrochemical *** 0.5 mA cm^(-2),the gravimetric capacitance increased from 0.01 F g^(-1)without mineralization to 322 F g^(-1)with iMAG,which exceeds values reported for any other free-standing or powder-based biomass-derived carbon *** outstanding cycling stability of~104%after 1000 cycles in 1 M HClO4 was *** assembled symmetric supercapacitor device delivered a high specific capacitance of 376 F g^(-1)and a high energy density of 26 W h kg^(-1)at a power density of 4000 W kg^(-1),with excellent cycling performance(98.5%retention after 2000 cycles).In combination with the proposed 3D printed mold-assisted solution casting(3DMASC),iMAG allows for the generation of free-standing carbon aerogel architectures with arbitrary ***,the novel method introduces flexibility in constructing free-standing carbon aerogels from any ionically cross-linkable biopolymer while maintaining the ability to tailor the design,dimensions,and pore size distribution for specific energy storage applications.

关键词： biomass carbon aerogel sustainable energy materials free-standing supercapacitors

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Application of N-thiocyanatosuccinimide as a reagent for the facile conversion of epoxides into thiocyanohydrines

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Chinese Chemical Letters 2011年第1期22卷 21-24页

作者： babak Mokhtari Roya Azadi Samira Rahmani-Nezhad Department of Chemistry College of ScienceShahid Chamran UniversityAhvaz 61357-43337Iran

The use of in situ generated N-thiocyanatosuccinimide with NH4SCN offers an efficient reagent system for the conversion of epoxides into their corresponding thiocyanohydrines in good to high yields. The major advantages of this method are as follows： use of cheap reagent, high regioselectivity, simple availability of reagent, ease of workup of the reaction.

关键词： N-Thiocyanatosuccinimide Ring opening Epoxide Thiocyanohydrin

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The effect of nanoparticles on wettability alteration for enhanced oil recovery: micromodel experimental studies and CFD simulation

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Petroleum Science 2019年第4期16卷 859-873页

作者： Peyman Rostami Mohammad Shari babak Aminshahidy Jalal Fahimpour Department of Petroleum Engineering Amirkabir University of Technology

The applications of nanotechnology in oilfields have attracted the attention of researchers to nanofluid injection as a novel approach for enhanced oil recovery. To better understand the prevailing mechanisms in such new displacement scenarios,micromodel experiments provide powerful tools to visually observe the way that nanoparticles may mobilize the trapped *** this work, the e ect of silicon oxide nanoparticles on the alteration of wettability of glass micromodels was investigated in both experimental and numerical simulation approaches. The displacement experiments were performed on the original water-wet and imposed oil-wet(after aging in stearic acid/n-heptane solution) glass micromodels. The results of injection of nanofluids into the oil-saturated micromodels were then compared with those of the water injection scenarios. The flooding scenarios in the micromodels were also simulated numerically with the computational fluid dynamics(CFD) method. A good agreement between the experimental and simulation results was observed. An increase of 9% and 13% in the oil recovery was obtained by nanofluid flooding in experimental tests and CFD calculations, respectively.

关键词： Nanoparticles Micromodel Wettability alteration Oil recovery CFD calculation

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