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Classification and assessment of rock mass parameters in Choghart iron mine using P-wave velocity

Journal of Rock Mechanics and Geotechnical Engineering 2017年第2期9卷 318-328页

作者： Mohammadreza Hemmati Nourani Mohsen taheri Moghadder Mohsen Safari Department of Mining and Metallurgy Yazd UniversityYazdIran Department of Mining Engineering Shahid Bahonar University of KermanKermanIran Department of Mining Engineering Birjand University of TechnologyBirjandIran

Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock *** basic data required may be obtained from visual observation and laboratory or field ***,owing to the discontinuous and variable nature of rock masses,it is difficult for rock engineers to directly obtain the specific design parameters *** an alternative,the use of geophysical methods in geomechanics such as seismography may largely address this *** this study,25 seismic profiles with the total length of 543 m have been scanned to determine the geomechanical properties of the rock mass in blocks Ⅰ,Ⅲ and Ⅳ-2 of the Choghart iron ***,rock joint measurements and sampling for laboratory tests were *** results show that the rock mass rating（RMR） and Q values have a close relation with P-wave velocity parameters,including P-wave velocity in field(V;).P-wave velocity in the laboratory(V;) and the ratio of V;V;(i.e.K;= V;/V;.However,Q value,totally,has greater correlation coefficient and less error than the RMR,In addition,rock mass parameters including rock quality designation（RQD）,uniaxial compressive strength（UCS）,joint roughness coefficient（JRC） and Schmidt number（RN） show close relationship with P-wave *** equation based on these parameters was obtained to estimate the P-wave velocity in the rock mass with a correlation coefficient of 91%.The velocities in two orthogonal directions and the results of joint study show that the wave velocity anisotropy in rock mass may be used as an efficient tool to assess the strong and weak directions in rock mass.

关键词： Rock mass classification P-wave velocity Q system Rock mass rating(RMR) Geophysical methods

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Costate mapping for indirect trajectory optimization

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Astrodynamics 2021年第4期5卷 359-371页

作者： Ehsan taheri Vishala Arya John L.Junkins Department of Aerospace Engineering Auburn UniversityAuburnAL 36849USA Department of Aerospace Engineering Texas A&M UniversityCollege StationTX 77843-3141USA

Numerical solutions of optimal control problems are influenced by the appropriate choice of *** proposed method based on the variational approach to map costates between sets of coordinates and/or elements is suitable for solving optimal control problems using the indirect formalism of optimal control *** Jacobian of the nonlinear map between any two sets of coordinates and elements is a key component of costate vector mapping theory.A new solution for the class of planar,free-terminal-time,minimum-time,orbit rendezvous maneuvers is also *** accuracy of the costate mapping is verified,and its utility is demonstrated by solving minimum-time and minimum-fuel spacecraft trajectory optimization problems.

关键词： indirect optimization spacecraft trajectory optimization optimal control theory minimum time minimum fuel interplanetary Earth-centered low thrust

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Optimization of the gas separation performance of polyurethane–zeolite 3A and ZSM-5 mixed matrix membranes using response surface methodology

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Chinese Journal of Chemical Engineering 2019年第1期27卷 110-129页

作者： Hajar taheri Afarani Morteza Sadeghi Ahmad Moheb Ebrahim Nasr Esfahani Department of Chemical Engineering Tennessee Technological University Department of Chemical Engineering Isfahan University of Technology

In the present work, the response surface method software was used with five measurement levels with three *** were applied for the optimization of operating parameters that affected gas separation performance of polyurethane–zeolite 3A, ZSM-5 mixed matrix *** basis of the experiments was a rotatable central composite design(CCD).The three independent variables studied were: zeolite content(0–24 wt%), operating temperature(25–45 ℃) and operating pressure(0.2–0.1 MPa).The effects of these three variables on the selectivity and permeability membranes were studied by the analysis of variance(ANOVA).Optimal conditions for the enhancement of gas separation performances of polyurethane–3A zeolite were found to be 18 wt%, 30 ℃ and 0.8 MPa *** these conditions, the permeabilities of carbon dioxide, methane, oxygen and nitrogen gases were measured at 138.4, 22.9, 15.7 and 6.4 Barrer respectively while the CO_2/CH_4, CO_2/N_2 and O_2/N_2 selectivities were 5.8, 22.5 and 2.5, ***, the optimal conditions for improvement of the gas separation performance of polyurethane–ZSM 5 were found to be 15.64 wt%, 30 ℃ and 4 *** permeabilities of these four gases(*** dioxide, methane, oxygen and nitrogen) were 164.7, 21.2, 21.5 and 8.1 Barrer while the CO_2/CH_4, CO_2/N_2 and O_2/N_2 selectivities were 7.8, 20.6 and 2.7 respectively.

关键词： Response surface method (RSM) Mixed matrix membranes Analysis of variance (ANOVA) Optimum conditions

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Characterizations of dissimilar S32205/316L welds using austenitic, super-austenitic and super-duplex filler metals

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International Journal of Minerals,Metallurgy and Materials 2020年第1期27卷 119-127页

作者： A.taheri B.Beidokhti B.Shayegh Boroujeny A.Valizadeh Department of Materials Engineering Najafabad BranchIslamic Azad UniversityIsfahan ***Iran Materials and Metallurgical Engineering Department Faculty of EngineeringFerdowsi University of MashhadMashhad ***Iran Department of Engineering Shahrekord UniversityShahrekord 88186-34141Iran Brunel Centre for Advanced Solidification Technology(BCAST) Brunel UniversityUxbridge UB83PHUK

UNS S32205 duplex stainless steel plates were welded to AISI 316 L stainless steel using the pulsed gas tungsten arc welding process with three different filler metals: ER2594, ER312, and ER385. The microstructures of the welds were characterized using optical and scanning electron microscopy, and all of the specimens were evaluated by ferrite measurements. The mechanical properties were studied through hardness,tensile, and impact tests. In addition, the pitting resistance equivalent number was calculated and cyclic polarization tests were performed to evaluate the corrosion resistance of the weld metal. The results showed that chromium nitride was formed in the heat-affected zone of the duplex side,whereas no sigma phase was detected in any of the specimens. The ferrite number increased from the root pass to the final pass. The absorbed energies of the impact test decreased with increasing ferrite number, whereas the tensile strength was enhanced. The fully austenitic microstructure of the specimen welded with ER385 exhibited the highest resistance to pitting corrosion at 25°C, and the super-duplex weld metal presented superior corrosion resistance at 50°C.

关键词： stainless steel mechanical properties microstructure welding

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Germanium separation and purification by leaching and precipitation

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Journal of Central South University 2016年第9期23卷 2214-2222页

作者： Saeid Bayat Sajjad Aghazadeh Mohammad Noaparast Mahdi Gharabaghi Behrooz taheri School of Mining Engineering College of Engineering University of Tehran

In this research work, extraction and purification of germanium from zinc leach residues(ZLR) were investigated. The results of ICP, XRF, and atomic adsorption spectroscopy(AAS) tests show that contents of germanium, iron, lead, and zinc within the leaching residue were 105×10^(-6), 3.53%, 10.35%, and 8.8%, respectively. XRD results indicate that the main minerals were in different forms of sulfates(CaSO_4·2H_2O, PbSO_4 and ZnSO_4·6H__2O), silicate(SiO_2), and oxide(Fe_2O_3). Dissolution of leaching filter cake was carried out using 5 parameters and each in 4 levels(acid concentration, temperature, time, liquid-to-solid ratio, and stirring speed) by Taguchi method(L_(16)), and then optimization of the effective parameters by response surface method. Under optimum conditions, zinc and germanium dissolution efficiencies were 88.71% and 8%, respectively. Leaching tests with sulfuric acid(added di-ammonium oxalate monohydrate) and hydrochloric acid(HCl) on the residues obtained from previous-stage sulfuric acid dissolution, yielded germanium and iron recoveries of 83%, 88%, 40%, and 90%, respectively. Thus, leaching experiment with sulfuric acid(added di-ammonium oxalate monohydrate) was superior to that with hydrochloric acid due to high and low extraction amounts of germanium and iron, respectively. Precipitation experiments revealed that germanium purification with tannic acid presented a better result compared to sodium hydroxide and ammonia. Under optimum conditions, contents of germanium and iron in the solution after precipitation were 0.1505% and 14.7% with precipitation yields of 91% and 52%, respectively.

关键词： experimental design di-ammonium oxalate monohydrate germanium leaching, tannic acid

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Regenerating historical districts through tactical urbanism:A case study of Sarpol neighborhood in Isfahan Province,Iran

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Frontiers of Architectural Research 2023年第6期12卷 1234-1245页

作者： Mohammad Salehi Shima taheri Amirhosein Shabani Department of Urban Planning Najafabad BranchIslamic Azad UniversityNajafabadIran Department of Architecture Isfahan(Khorasgan)BranchIslamic Azad UniversityIsfahanIran Department of Architecture Faculty of EngineeringShahid Ashrafi Esfahani UniversityIsfahanIran Advancement in Architecture and Urban Planning Research Center Najafabad BranchIslamic Azad UniversityNajafabadIran

This paper examines historical urban fabrics’challenges regarding quality of life and visual disturbances despite their cultural and identity *** and socialoriented approaches considering social,economic,and cultural dimensions preserve and enhance these valuable *** urbanism,with its people-oriented approach,can address these *** study focused on Sarpol in Khomeinishahr County,Isfahan Province of *** city’s urban structure divides into two parts:despite its active social structure and valuable spaces,Sarpol is a historic neighborhood with significant *** followed Corbin and Strauss’s version of Grounded Theory in the qualitative research *** and snowball sampling methods were employed to select 21 participants from the Sarpol neighborhood for semi-structured *** analysis involved three stages of coding:open,axial,and *** themes included religious participation,identity,sustainable social bonds,indigenous dependence,and low environmental *** central issue identified was the crucial role of religious and cultural values as a driving force for tactical urbanism,which emerged as the most critical semantic domain related to the research problem.

关键词： Tactical urbanism Urban regeneration Historical fabrics Neighborhood Grounded theory Social-oriented approaches

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Effects of Increased Salinity on Growth, Development and Survival in Early Life Stages of the Green Toad Bufotes variabilis (Anura: Bufonidae)

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Asian Herpetological Research 2018年第2期9卷 129-134页

作者： Soheyla YAGHOBI Somaye VAISSI Zeynab taheri KHAS Mozafar SHARIFI Razi University Centre for Environmental Studies Department of Biology

This study examined the effects of increased salinity on growth, development and survival of the Green toad, Bufotes variabilis during embryonic, hatching and early larval periods. Eggs from a single cohort of B. variabilis were subjected to acute and chronic toxicity tests for water salinity ranging from 0.20 to 10 g of salt per liter. Results obtained from this study showed that salinity over 3.70 g/l increased embryonic mortality and reduced percentage of hatching and survival rate of larvae. As larvae tolerated salinity 0.20 to 3.70 g/l with highest survival, but salinity of 10 g/l caused mortality of all individuals within 12 h, 7.70-8.70 （g/l） within 4.5 days, 5.70-6.70 g/l within 10 days and 4.70 （g/l） were tolerated within 14 days. Salinity less than 0.70 g/l did not affect survival and hatching success of the embryos. After a 3-week experiment, size of larvae exposed to salinities over 0.70 g/l was lower compared to larvae reared at lower salinity levels. Meanwhile increases in salinity more than 3.70 g/l caused extension in the hatching period. Larvae reared at salinity of 3.70 to 4.70 g/l had morphological abnormalities, such as distortion of tail.

关键词： acute toxicity Bufotes variabilis hatching rate road salt salinization survival

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The efficient synthesis of 14-alkyl or aryl 14H-dibenzo[a,j] xanthenes catalyzed by bismuth(Ⅲ)chloride under solvent-free conditions

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Chinese Chemical Letters 2011年第8期22卷 927-930页

作者： Ebrahim Soleimani Mohammad Mehdi Khodaei Afsaneh taheri Kal Koshvandi Department of Chemistry Razi UniversityKermanshah 67149Iran

An efficient method for the synthesis of 14-alkyl or aryl 14H-dibenzo[a,j]xanthene derivatives by the reaction of β-naphthol,and aldehydes in the presence of a catalytic amount of bismuth（Ⅲ） chloride（BiCl_3） under solvent-free conditions at 110℃is *** and aromatic aldehydes were used in the reaction and in all cases the desired products were synthesized *** reaction was studied under different temperatures;the maximum yield was obtained in a short reaction period at 110℃.The method offers the advantages of high yields,short reaction times,simplicity and easy workup compared to the conventional method of syntheses.

关键词： Bismuth(Ⅲ) chloride 14H-Dibenzo[a j]xanthenes β-Naphthol

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Intermittent swelling and shrinkage of a highly expansive soil treated with polyacrylamide

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第1期14卷 252-261页

作者： Amin Soltani An Deng Abbas taheri Brendan C.O’Kelly School of Engineering Information Technology and Physical SciencesFederation UniversityChurchillVIC3842Australia School of Civil Environmental and Mining EngineeringThe University of AdelaideAdelaideSA5005Australia Department of Civil Structural and Environmental EngineeringTrinity College DublinDublinD02 PN40Ireland

This laboratory study examines the potential use of an anionic polyacrylamide(PAM)-based material as an environmentally sustainable additive for the stabilization of an expansive soil from South *** experimental program consisted of consistency limits,sediment volume,compaction and oedometer cyclic swell-shrink tests,performed using distilled water and four different PAM-to-water solutions of P_(D)=0.1 g/L,0.2 g/L,0.4 g/L and 0.6 g/L as the mixing ***,the relative swelling and shrinkage strains were found to decrease with increasing number of applied swell-shrink cycles,with an‘elastic equilibrium’condition achieved on the conclusion of four *** propensity for swelling/shrinkage potential reduction(for any given cycle)was found to be in favor of increasing the PAM dosage up to P_(D)=0.2 g/L,beyond which the excess PAM molecules self-associate as aggregates,thereby functioning as a lubricant instead of a flocculant;this critical dosage was termed‘maximum flocculation dosage’(MFD).The MFD assertion was discussed and validated using the consistency limits and sediment volume properties,both exhibiting only marginal variations beyond the identified MFD of P_(D)=0.2 g/*** accumulated axial strain progressively transitioned from‘expansive’for the unamended soil to an ideal‘neutral’state at the MFD,while higher dosages demonstrated undesirable‘contractive’states.

关键词： Expansive soil Polyacrylamide(PAM) Consistency limits Sediment volume Swell-shrink cycles Swelling and shrinkage strains Accumulated axial strain

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Improving TC drill bit's efficiency and resistance to wear by graphene coating

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Petroleum Research 2022年第4期7卷 430-436页

作者： Reza taheri Mohsen Jalali Ahmed Al-Yaseri George Yabesh Petroleum Engineering Department University of WyomingWYUSA Petroleum Engineering Department Tehran Azad UniversityTehranIran Petroleum Engineering Discipline Engineering SchoolEdith Cowan UniversityAustralia

Displaying a two-dimensional pure crystal carbon structure,Graphene is the strongest,yet thinnest substance discovered by *** tungsten carbide(TC)drill bits with graphene to evaluate the effect of graphene on the wear,as well as the rate of penetration of the drilling bit was examined in this *** evaluation approaches were employed:one with employing ANSYS Software and the second by employing atomic pressure chemical vapor deposition(APCVD synthesis)in the laboratory to produce a monolayer graphene *** simultaneous software-based and lab-based testing were performed to increase the credibility of the results and minimize the potential *** the simulation using ANSYS,the maximum shear elastic strain,equivalent elastic strain,equivalent(von mises)stress,total deformation and maximum shear stress were investigated prior and after the gra-phene coating was applied on TC simulated *** deformation was only slightly increased,while the maximum shear elastic strain was almost doubled,reflecting that the bit's wear was significantly reduced after the ***-based APCVD synthesis results showed 34%increase in compressive strength of the coated bit,in comparison to the uncoated *** failure occurred for uncoated bit at 35 MPa,where the coated bit experienced failure at 46.9 *** Von Mises stress test conducted on the coated and uncoated samples also indicated that this stress was 41%less for the coated bit,in comparison to the uncoated ***,two small-scale drilling operations,one using a 1inch graphene-coated TC bit and the other using a 1inch non-coated TC bit,were performed on a granite block,to evaluate the performance of the graphene-coated bit in *** a chosen 120-min time frame,27 consecutive holes could be drilled by the graphene-coated TC bit,while 19 consecutive holes could be drilled by the uncoated TC bit,in identical drilling *** implies a 42%increase in ROP.

关键词： Drill bit's efficiency Graphene-coated ANSYS APCVD Wear reduction Penetration rate

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