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Stresses induced by post-tensioned anchor in jointed rock mass

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Journal of Central South University 2015年第4期22卷 1463-1476页

作者： Alan Showkati parviz Maarefvand Hossein Hassani Faculty of Mining and Metallurgical Engineering Amirkabir University of Technology

A new analytical study on stresses around a post-tensioned anchor in rocks with two perpendicular joint sets is presented. The assumptions of orthotropic elastic rock with plane strain conditions are made in derivation of the formulations. A tri-linear bond-slip constitutive law is used for modeling the tendon-grout interface behavior and debonding of this interface. The bearing plate width is also considered in the analysis. The obtained solutions are in the integral forms and numerical techniques that have been used for evaluation. In the illustrative example given, the major principal stress is compressive in the anchor free zone and compressive stress concentrations of 815 k Pa and 727 k Pa(for the anchor load of 300 k N) are observed under the bearing plate and the bond length proximal end, respectively. However, large values of tensile stresses with the maximum of-434 k Pa are formed at the bond length distal end. The results obtained using the proposed solution are compared very those of numerical method(FEM).

关键词： post-tensioned anchor jointed rock stress distribution analytical solution tri-linear bond-slip model bond length bearing plate

Evaluation of Feasible Interlinking Converters in a Bipolar Hybrid Microgrid

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Journal of Modern Power Systems and Clean Energy 2020年第2期8卷 305-314页

作者： parviz Najafi Abbas Houshmand Viki Mahdi Shahparasti the Department of Electrical Engineering K.N.Toosi University of TechnologyTehranIran the Department of Electrical Engineering Polytechnic University of CataloniaBarcelonaSpain

A bipolar hybrid microgrid is a new topology which benefits from the advantages of both alternating current(AC)and direct current(DC)*** AC/DC converter is the key of this topology which has the following characteristics:being able to provide two equal pole voltages in DC side;complying with the standards of current quality at AC side;being able to control active and reactive power independently in AC side,and transmitting bidirectional *** this paper,two categories of power converters including single-stage and two-stage converters are proposed for this topology.A new cost-effective control strategy is added to the control of general grid-connected converter for each interlinking converter,and the control of autonomous DC-link pole voltage for both candidates is *** simulations based on the designed control strategies are conducted to validate the function of control strategies under the operation conditions of different DC *** performances of two selected interlinking converters with balanced and unbalanced DC loads are *** power quality of microgrid and total harmonic distortion(THD)analysis are demonstrated in grid-tied and islanded ***,semiconductor power loss simulations based on a closed-loop thermal network simulation are ***,the mutual effects of power loss and initial junction temperature are investigated.

关键词： Bipolar hybrid microgrid interlinking converter DC-link voltage balancing power loss distribution

Evaluation of airlift pump performance for vertical conveying of coal particles

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International Journal of Coal Science & Technology 2023年第3期10卷 155-166页

作者： parviz Enany Oleksandr Shevchenko Carsten Drebenshtedt Faculty of Mining and Special Civil Engineering Technische Universitat BergakademieGustav-Zeuner StraBe 1A09599 FreibergGermany UTF GmbH ErzstraBe 1509618 Brand-ErbisdorfGermany

One of the crucial aspects of reducing air consumption when conveying particles with an airlift pump is to know the factors that affect the process of particle motion at an initial velocity of *** determine the influence of submer-gence ratio and physical properties of particles(such as size,shape,and mass)on the onset of vertical particle motion,the airlift pump was taken as the research object,and spherical glass together with irregular shaped coal were used as experimental test *** results show that unlike the water-solid environment,the start of particle motion in the water-air mixture does not always occur at a certain value of superficial water velocity and this value also increases with increasing submergence *** the parameters considered,the role of submergence ratio is much more effective than the dimensions and the shape of the particle,because by increasing submergence from 0.3 to 0.8,it is possible to reduce air consumption by up to 8 *** on this study the corresponding theoretical model derived by Fujimoto et *** optimized,wherein the overall agreement between the modified theory and present experimental data is particularly *** to Fujimoto,the minimum superficial water velocity for lifting solids in the air-water mixture is not always smaller than water ambient which indicates on optimum submergence ratio higher than ***,a new criterion was introduced to describe the moment of onset of the particle motion as a function of the superficial fluid velocity ratio for each submergence value.

关键词： Air-water-solid flow Slurry- Coal Submergence ratio Taylor bubble Superficial velocity

Gold anomaly ranking based on stream sediment geochemistry in the Fariman–Kashmar axis, NE Iran

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Acta Geochimica 2021年第2期40卷 135-149页

作者： Hassan Azmi parviz Moarefvand Abbas Maghsoudi Department of Mining and Metallurgical Engineering Amir Kabir University of TechnologyTehranIran Geological Survey of Iran Northeast TerritoryMashhadIran

One of the essential tasks accelerate the decision-making process in mineral exploration projects is ranking anomalous *** this study,we used fourteen geologic maps(at scale 1:100,000)in areas where systematic geochemical explorations were conducted in the Fariman-Kashmar axis in northeast Iran to conduct the anomaly *** all these maps,samples were consistently prepared to be analyzed through statistical and geostatistical *** first,anomaly separation was carried out by fractal methods that resulted in the detection of 308 anomalous samples in 128 *** samples were classified into three groups of first,second,and thirdorder anomalies,whose number of anomalous samples were calculated based on this ranking *** factors,including the average concentration of each anomaly,its surface area,and the number of its samples,were used to rank the *** to this technique,the maximum anomaly score obtained was 172 for the Taknar area,and the minimum score was 3 for several *** validate the ranking results,some exploration operations were carried out in some of these anomalous areas in which mining operations started *** significant gold anomalous areas were introduced,which is considered an important result of this study.

关键词： Anomaly ranking Fractal model Exploration decision Gold exploration Geochemistry exploration

Preparation of hydrophobic flat sheet membranes from PVDF-HFP copolymer for enhancing the oxygen permeance in nitrogen/oxygen gas mixture

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1566-1581页

作者： Bahador Akbari Asghar Lashanizadegan parviz Darvishi Abdolrasoul Pouranfard Department of Chemical Engineering School of EngineeringYasouj UniversityYasoujIran

In this study, poly(vinilydene fluoride-co-hexafluoropropylene)(PVDF-HFP) was used for preparation of hydrophobic membranes using non-solvent induced phase inversion(NIPS) technique. PVDF-HFP copolymer with concentrations of 10 wt% and 12 wt% was prepared to investigate the effect of polymer concentration on pore structure,morphology, hydrophobicity and performance of prepared membranes. Besides, the use of two coagulation baths with the effects of parameters such as coagulant time, polymer type and concentration, and the amount of nonsolvent were studied. The performance of prepared membranes was evaluated based on the permeability and selectivity of oxygen and nitrogen from a gas mixture of nitrogen/oxygen under operating conditions of feed flow rate(1–5 L·min-1), inlet pressure to membrane module(0.1–0.5 MPa) and temperatures between 25 and 45 °C. The results showed that the use of two coagulation baths with different compositions of distillated water and isopropanol,coagulant time, polymer type and concentration, and the amount of non-solvent additive have the most effect on pore structure, morphology, thickness, roughness and crystallinity of fabricated membranes. Porosity ranges for the three fabricated membranes were determined, where the maximum porosity was 73.889% and the minimum value was 56.837%. Also, the maximum and minimum average thicknesses of membrane were 320.85 μm and115 μm. Besides, the values of 4.7504 × 10-7 mol· m-2· s-1· Pa-1, 0.525 and 902.126 nm were achieved for maximum oxygen permeance, O2/N2 selectivity and roughness, respectively.

关键词： Oxygen-enriched air Hydrophobic flat sheet membrane PVDF-HFP copolymer Enhancing oxygen permeance Pore structure

Partial Relief of Drought-Stressed Fennel(Foeniculum vulgare Mill.) in Response to Foliar-Applied Zinc

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Pedosphere 2019年第6期29卷 752-763页

作者： Ahmad RAJABI parviz EHSANZADEH Jamshid RAZMJOO Department of Agronomy and Plant Breeding College of Agriculture Isfahan University of Technology

Few attempts have been made to explore the effect of Zn fertilization on the performance of medicinal plants in general and fennel in particular, under adverse conditions. This study was conducted to examine the efficacy of zinc (Zn) in correcting physiological responses of fennel to water deficit. Twelve field-grown fennel genotypes were subjected to two levels of irrigation (irrigation after 25%–35% and 75%–85% depletion of available soil water) and two levels of foliar-applied Zn (0 and 4 g kg −1 ). Water deprivation had significant effects on all characteristics;i.e., in contrast to seed essential oil concentration, harvest index, and superoxide dismutase (SOD) and catalase activities, it led to decreases in the rest of the attributes. Varietal differences in response to drought were meaningful for most of the traits. Genotypic variations for dry mass and seed yield were consistent with differences among the genotypes in leaf water potential, relative water content, proline concentration, and chlorophyll concentrations. Zinc led to significant increases in all physiological attributes, including activation of antioxidant defense responses manifested in ascorbate peroxidase and SOD activities and carotenoid concentration. The Zn-effect tended to be more notable in drought-stricken fennel plants in a majority of the traits. Based on our findings, Zn could be considered an effective micronutrient for ameliorating, at least in part, the stressful effects of water deficit on fennel.

关键词： Antioxidant defense Drought tolerance Medicinal plant Micronutrient Physilogical attributes Water deficit Zn fertilization

Numerical Simulation of Mixing in a Micro-well Scale Bioreactor by Computational Fluid Dynamics

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Chemical Research in Chinese Universities 2002年第2期18卷 113-116页

作者： Hu Zhang Sally Lamping parviz Ayazi Shamlou Advanced Biochemical Engineering Centre University College LondonTorrington PlaceLondonWC1E 7JE

The introduction of the multi well plate miniaturisation technology with its associated automated dispensers, readers and integrated systems coupled with advances in life sciences has a propelling effect on the rate at which new potential drug molecules are discovered. The translation of these discoveries to real outcome now demands parallel approaches which allow large numbers of process options to be rapidly assessed. The engineering challenges in achieving this provide the motivation for the proposed work. In this work we used computational fluid dynamics(CFD) analysis to study flow conditions in a gas liquid contactor which has the potential to be used as a fermenter on a multi well format. The bioreactor had a working volume of 6 5 mL with the major dimensions equal to those of a single well of a 24 well plate. The 6 5 mL bioreactor was mechanically agitated and aerated by a single sparger placed beneath the bottom impeller. Detailed numerical procedure for solving the governing flow equations is given. The CFD results are combined with population balance equations to establish the size of the bubbles and their distribution in the bioreactor. Power curves with and without aeration are provided based on the simulated results.

关键词： CFD Numerical simulation Fermenter Snapshot method Two fluid Population balance

Energy budget and economic analysis in conventional and organic rice production systems and organic scenarios in the transition period in Iran

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Frontiers in Energy 2012年第4期6卷 341-350页

作者： Hamed MANSOORI parviz Rezvani MOGHADDAM Rooholla MORADI Department of Agronomy Faculty of AgricultureFerdowsi University of MashhadMashhad 91779-4897Iran

Compared to conventional agriculture, organic agriculture is reported to be more efficient and effective in reducing water and soil pollution, greenhouse gases （GHGs） emission and risk of human health. In additional, field management under organic condition can be useful for increasing energy efficiency. Rice is one of the important crops which are cultivated in two forms, organic and conventional, in Iran. In order to compare the energy efficiency and economic analysis of rice production in organic and conventional systems in Iran, needed informa- tion was collected by face-to-face questionnaire in 2011 and three scenarios were designed to predict the changes of energy budget and economic analysis in the transition period that included： 25%, 50% and 75% organic management in rice production. The results showed that all energy indexes were improved in organic rice production compared to conventional condition. Higher values of benefit to cost ratio, gross and net return and lower value of total cost of production were obtained from organic rice production which indicated that the organic management of farm improved economically in compar- ison with the conventional rice production system. The shares of direct and renewable energies were increased by approach to organic management. Increase in energy efficiency and productivity was predicted for the transition period but decrease trend in economic indexes was projected for this period in all scenarios. The main reason for decreasing economic indexes in organic scenarios was that the market price of organic rice was the same as that of conventional rice in the transition period.

关键词： energy efficiency specific energy net return,Cobb-Douglas function

Optimizing and slope determination of final wall for Maiduk Mine with consideration of destabilizer factors

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International Journal of Mining Science and Technology 2016年第3期26卷 501-509页

作者： Shamsoddin Saeed Masoud Maarefvand parviz Yaaghubi Ebrahim Geotechnical Engineer Mahyar Haffar Karmania Company Department Mining & Metallurgy Amirkabir University of Technology

In this research, determination of final slope for Maiduk copper mine of Kerman is investigated according to destabilizing factors of the mine. The development of the Maiduk Mine caused the extension of the mine area and also withdrawal of its wall. So, optimizing possibility of mine slope is essential. Finally,the magnitude of optimized slopes for different walls of the mine in association with executive commands with better factors of safety is provided. The results show that the most important destabilizer factors are the presence of water and pore pressure in the faults and the main joints. With the omission of pore pressure, mine wall for the designed depth is quite stable. This requires a drainage pattern in the lifetime of the mine. In an optimistic point of view, the minimum factor of safety of the wall will be 2.81 even without drainage. This conclusion allows optimizing the slope to its maximum magnitude of 51 degree. With the pessimistic engineering judgment and with the higher SF, the magnitude of the slope is optimized to 47 degree.

关键词： Optimizing Destabilizer factors Final slope Maiduk copper mine