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Geochronology and petrogenesis of the mafic dykes from the Purang ophiolite:Implications for evolution of the western Yarlung-Tsangpo suture zone,southwestern Tibet

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Geoscience Frontiers 2020年第1期11卷 277-292页

作者： Fahui Xiong Yuanku Meng Jingsui Yang Zhao Liu Xiangzhen Xu alireza eslami Ran Zhang Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals College of Earth Science and EngineeringShandong University of Science and TechnologyQingdao 266590China Center for Advanced Research on the Mantle(CARMA) Key Laboratory of Deep-Earth Dynamics of Ministry of Land and ResourcesInstitute of GeologyChinese Academy of Geological SciencesBeijing 100037China Institute of Mineral Resources Chinese Academy of Geological SciencesBeijing 100037China School of Geology College of ScienceUniversity of TehranTehran ***Iran

The>2000 km Indus-Yarlung Tsangpo suture zone(IYSZ)is composed of the Neo-tethys oceanic remnants,flysch units and related continental rocks,which has been regarded as the boundary between the Eurasian and Indian *** the ophiolitic complexes,the Purang ophiolite is the biggest massif in the IYSZ,and many studies have been conducted on this ***,previous studies have mainly focused on harzburgite,clinopyroxenite and *** observations show that mafic dykes were emplaced within the Purang ***,petrogenetic evolutions of those mafic dykes are poorly *** this study,we present new LA-ICP-MS zircon U-Pb dating results,whole-rock geochemistry and Sr-Nd-Hf isotope analyses for microgabbro,gabbro and dolerite dykes from the Purang ophiolite of the southwestern IYSZ,*** samples yielded zircon U-Pb ages of144.2±2.1 Ma.127.9±2.3 Ma and 126.5±0.42 Ma,suggesting two different phases of magmatic activities ***-rock geochemical results suggest that the gabbro samples show alkaline features marked by enrichments of light rare earth elements(LREE)and large-ion lithophile elements(LILE),as well as Nb-Ta elements,suggesting an oceanic island basalt-like(OIB-like)geochemical ***,the dolerite and microgabbro samples demonstrate sub-alkaline characteristics with normal mid-oceanic ridge basalt-like(N-MORB-like)geochemical *** distinct mafic dykes show significant Rb element *** geochemical data and Sr-Nd-Hf isotopic features suggest that the microgabbro and gabbro rocks were derived from a depleted mantle that had been metasomatized by partial melts of sediments and enriched slab-derived *** dolerite was also originated from a depleted mantle marked by significantly depleted Sr-Nd-Hf compositions,which was not influenced by enriched slab-derived fluids and sediments contamination during subsequent *** isotope and geochemical data and tectonic diagrams sugges

关键词： Isotope geochemistry Mafic rocks Purang ophiolite Yarlung Tsangpo suture zone

Effect of thinning on growth of Acer velutinum Boiss. in northern forests of Iran

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Forestry Studies in China 2013年第4期15卷 320-324页

作者： alireza eslami M.R.JAHANARA S.A.HASHEMI Department of Agriculture Rasht Branch Islamic Azad University Natural Racecourses Organization Department of Forestry Lahijan Branch Islamic Azad University

It has become necessary to develop stands of fast growing endemic species in the Caspian forests because of their reduction in area and the domestic demand of timber processing industries in Iran. Acer velutinum, an endemic species in Iran, is often planted in monocultures or in a mixture with other endemic species. Our study was conducted on A. velutinum planted in Berenjestanak(control plots) and Chaibagh(thinned plots) in northern Iran in 1991. A randomized sampling method with circular sampling plots of 100 m2was used to measure diameter and height of trees. The results show that the diameter of trees in thinned stands was 19.98 cm and in the control stands 13.84 cm, while the mean heights were 18.33 and 17.46 m, respectively. The mean basal area in thinned stands was 30.74 m2and in the control 15.70 m2per ha. The results of Student’s t tests indicate that there are significant differences at a probability level of 99.9% between the two variously treated stands in diameter(d), height(h), basal area, volume growth and the stability coefficient. We conclude that tending operations with suitable intensity in different time periods are recommended to obtain stable stands.

关键词： Acer velutinum thinning operation afrorestation northern Iran

Metallogeny of Serpentinite-hosted Magnetite Deposits: Hydrothermal Overgrowth on Chromite or Metamorphic Transformation of Chromite?

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Acta Geologica Sinica(English Edition) 2020年第S01期94卷 5-5页

作者： alireza eslami Ali KANANIAN Giovanni GRIECO G.Diego GATTA Nicola ROTIROTI School of Geology College of ScienceUniversity of TehranTehran***Iran ISTerre Maison des GéosciencesUniversitéde Grenoble-AlpsCNRSF-38041 GrenobleFrance Dipartimento di Scienze della Terra Universitàdegli Studi di Milanovia Botticelli 2320133MilanItaly

Peculiar and rare occurrences of serpentinite-hosted magnetite deposits with mineable sizes are found in the Mesozoic ophiolites of Greece(Skyros), Iran(Nain and Sabzevar) and Oman(Aniba). These deposits have diverse thickness(from a few centimeters up to 50 m) and length(2 to >500 m). Magnetite ores show variable textures, including massive, nodular and banded ores, veins, net and fine-grained disseminations in serpentinites. Intriguingly, the investigated magnetite deposits can be mistaken for chromitite pods. Serpentinite-hosted magnetite deposits show three modes of occurrences including:(i) boulders strewn across the serpentinites(i.e. Skyros Island);(ii) ore bodies along the nonconformity contacts between serpentinites and limestones(i.e. Aniba);(iii) irregular and discontinuous trails of massive and semi-massive ore bodies within highly sheared serpentinite masses(i.e. Nain;Sabzevar). In all of these magnetite ore bodies, relicts of chromian spinel grains are occasionally enclosed in magnetite crystals. The chemistry of Cr-spinel relics found in these magnetite bodies are comparable to those of accessory Crspinels in the surrounding serpentinized peridotites. BSE images and elemental mapping revealed that magnetite occurs as a nucleation on chromian spinels but not being involved in reaction either with chromite or ferritchromite. Low-grade metamorphic transformation of chromite into Fe-chromite is documented along the cracks and fractures of a few chromite grains. Generally, magnetite has typical hydrothermal compositions, characterized by low Cr, V and Ti and high Mg and Mn. It is crucial to note that a few magnetite grains with metamorphic origin are characterized by high Cr and low Ti and Ni. The potential source of iron is essentially the Fe-rich olivine. We believe that multi-episodic serpentinization of peridotite systems at high fluid-rock ratios is the main process responsible for precipitation of magnetite at ore levels whereas low-grade metamorphic

关键词： serpentinite-hosted magnetite deposit multi-episodic serpentinization metamorphic transformation

Investigation of sensitivity and threshold voltage shift of commercial MOSFETs in gamma irradiation

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Nuclear Science and Techniques 2016年第6期27卷 166-171页

作者： Saleh Ashrafi Baharak eslami Faculty of Physics University of Tabriz Department of Physics Payame Noor University

This article is about the absorbed-dose-dependent threshold voltage shift of the MOSFET *** of the MOSFETs has been tested in different gate *** of the transistors for 662 ke V gamma ray is studied in 1–5 Gy dose *** was found that for transistors irradiated in biased mode,significant changes in the threshold voltage occurred,and the sensitivity to gamma rays increased with the bias voltage.

关键词：阈值电压漂移 MOSFET γ射线照射敏感性商业吸收剂量偏置电压晶体管

A New Approach to Plane Failure of Rock Slope Stability Based on Water Flow Velocity in Discontinuities for the Latian Dam Reservoir Landslide

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Journal of Mountain Science 2011年第2期8卷 124-130页

作者： Morteza AHMADI Majid eslami Department of Mining Engineering Tarbiat Modares University Ghaem Consulting Engineers

The stability of slopes is always of great concern in the field of rock engineering. The geometry and orientation of pre-existing discontinuities show a larger impact on the behavior of slopes that is often used to describe the measurement of the steepness, incline, gradient, or grade of a straight line. One of the structurally controlled modes of failure in jointed rock slopes is plane failure. There are numerous analytical methods for the rock slope stability including limit equilibrium, stress analysis and stereographic methods. The limiting equilibrium methods for slopes under various conditions against plane failure have been previously proposed by several investigators. However, these methods do not involve water pressure on sliding surfaces assessments due to water velocity and have not yet been validated by case study results. This paper has tried to explore the effects of forces due to water pressure on discontinuity surfaces in plane failure through applying the improved equations. It has studied the effect of water flow velocity on sliding surfaces in safety factor, as well. New equations for considering water velocity (fluid dynamics) are presented. To check the validity of the suggested equations, safety factor for a case study has been determined. Results show that velocity of water flow had significant effect on the amount of safety factor. Also, the suggested equations have higher validity rate compared to the current equations.

关键词： Plane Failure Limit Equilibrium Safety Factor Water Velocity

Comparison of deep convolutional neural network classifiers and the effect of scale encoding for automated pavement assessment

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第2期10卷 258-275页

作者： Elham eslami Hae-Bum Yun Department of Civil Environmental and Construction EngineeringUniversity of Central FloridaOrlandoFL 32816USA

Deep learning has received a growing interest in recent years for detecting different types of pavement distresses and automating pavement condition assessment.A proper choice of deep learning models is key for successful pavement assessment *** this study,we first present a comprehensive experimental comparison of state-of-the-art image classification models to evaluate their performances on 11 pavement objects *** experiments are conducted in different dimensions of comparison,including deep classifier architecture,effects of network depth,and computational *** convolutional neural network(CNN)classifiers widely used in transportation applications,including VGG16,VGG19,ResNet50,DenseNet121,and a generic CNN(as the control model),are tested with a comprehensive pixel-level annotated dataset for 11 different distress and non-distress classes(UCF-PAVE 2017).In addition,we investigate a simple yet effective approach of encoding contextual information with multi-scale input tiles to classify highly random pavement objects in size,shape,intensity,texture,and *** comparison results show that the multi-scale approach significantly improves the classification accuracy for all compared deep classifiers at a negligible extra computational ***,we provide recommendations of how to improve the classification performance of deep CNNs for automated pavement condition assessment based on the comparison results.

关键词： Road damage detection Automated pavement condition assessment Convolutional neural networks Deep learning Multi-class classification

Design adaptations in a large and deep urban excavation: Case study

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Journal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 389-399页

作者： Amir Alipour Abolfazl eslami Department of Civil and Environmental Engineering Amirkabir University of Technology

In this paper, design, re-design, and performance of a long-standing very deep excavation, which was originally planned to depth of 38 m, are presented. Over-digging was not planned in the original design,thus the reassessment was performed. Two main topics were followed: deepening to increase the maximum depth of an existent excavation from 38 m to 42.5 m, and feasibility for upgrading a predesigned support system from temporary to permanent support system. The geological investigations in the project site illustrated a type of stiff and cemented coarse-grained alluvium. An observational approach with additional geotechnical investigations and in situ tests was applied. Back analyses of stability of an unsupported access ramp, as well as deformation monitoring of walls, were used in order to review geotechnical design parameters that represent the full-scale behavior of the ground. Additional nails and soldier piles together with building mat foundation were implemented as a complementary lateral support in the retaining system. From an engineering point of view, by assuming a corrosion rate of 0.065 mm/a for existent rebars, according to chemical and electrical resistivity tests, the long-term performance of the revised retaining system was verified by static and pseudo-dynamic ultimate limit state analyses. Performance monitoring during the construction shows that the measured deformation is in the lower limit of the prediction.

关键词： Deep excavation Field observations In situ tests Support system Adaptive design Inverse analysis

A new approach for correlating of H_(2)S solubility in[emim][Lac],[bmim][ac]and[emim][pro]ionic liquids using two-parts combined models

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Chinese Journal of Chemical Engineering 2022年第4期35卷 521-527页

作者： alireza Afsharpour Faculty of Chemical and Materials Engineering Shahrood University of TechnologyShahroodIran

Two bi-part combined models containing reaction equilibrium thermodynamic model and an equation of state(EoS)including cubic plus association(CPA)or modified Soave-Redlich-Kwong(SRK),were employed to correlate H_(2)S solubility in ionic liquids[emim][Lac],[bmim][Ac]and[emim][Pro].RETM and CPA/mSRK are responsible for chemical and phase equilibria calculations,*** RETM defines a complex formation reaction between an H_(2)S and two IL molecules into the liquid phase so that a complex in the form of H_(2)S(IL)_(2)is probable to *** the other side,CPA/mSRK EoSs perform phase equilibria computations to find pressure and vapor phase *** the case of CPA,both of H_(2)S and the ionic liquids were considered as self-associating components which pursue 4 C and 2 B schemes,*** model computes the pure IL parameters using experimental density *** this work,critical properties were estimated through the modified Lydersen-Joback-Reid method,Eotvos and Guggenheim ***,the binary systems were investigated by applying *** presents average absolute deviations(AADs)equal to 2.41%,13.42%and 3.52%for[emim][Lac],[bmim][Ac],and[emim][Pro],***,the AADs obtained by mSRK are 3.75%,5.07%,and 6.06%,*** it is evident from the results,the combination of RETM with both CPA and m SRK EoSs will result in good correlation accuracy.

关键词： Solubility Thermodynamics Ionic liquids CPA RETM mSRK

Simultaneous Employment of Generation Rescheduling and Incentive-based Demand Response Programs for Congestion Management in Case of Contingency

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Journal of Modern Power Systems and Clean Energy 2022年第4期10卷 902-912页

作者： Seyed Erfan Hosseini Alimorad Khajehzadeh Mahdiyeh eslami Department of Electrical Engineering Kerman branchIslamic Azad UniversityKermanIran

Relieving congestion significantly influences the operation and security of the transmission ***,the congestion alleviation of transmission network in all power systems is ***,it could prevent price spikes and/or involuntary load shedding and impose high expenses on the transimission network,especially in case of ***,the increasing or decreasing generation rescheduling has been used as one of the most imperative approaches for correctional congestion management when a contingency ***,demand response programs(DRPs)could also be a vital tool for managing the ***,the simultaneous employment of generation rescheduling and DRPs is proposed for congestion management in case of *** objective is to reschedule the generation of power plants and to employ DRPs in such a way so as to lessen the cost of *** crow search algorithm is employed to determine the *** accuracy and efficiency of the proposed approach are assessed through the tests conducted on IEEE 30-bus and 57-bus test *** results of various case studies indicate the better performance of the proposed approach in comparison with different approaches presented in the literature.

关键词： Congestion management demand response generation rescheduling transmission economy transmission lines