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Numerical simulation of fatigue crack propagation in heterogeneous geomaterials under varied loads using displacement discontinuity method

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第3期15卷 702-716页

作者： rezvan alizadeh Mohammad Fatehi Marji Abolfazl Abdollahipour Mehdi Pourghasemi Sagand Department of Mining and Metallurgical Engineering Faculty of EngineeringYazd UniversityYazdIran School of Mining Engineering College of EngineeringUniversity of TehranTehranIran

Heterogeneous brittle geomaterials are highly susceptible to cyclic *** contain inherent flaws and cracks that grow under fatigue loads and lead to *** study presents a numerical model for analyzing fatigue in these materials based on the two-dimensional(2D)boundary element method and linear elastic fracture *** process is formulated by coupling the displacement discontinuity method with the incorporation technique of dissimilar regions and the governing equations of *** heterogeneous media are assumed to consist of materials with different properties,and the interfaces are assumed to be completely *** addition,the domains include multiple cracks exposed to constant and variable amplitude cyclic *** stress intensity factor is a crucial parameter in fatigue analysis,which is determined using the displacement field around crack *** incremental crack growth scheme is applied to calculating the fatigue *** growth rate values are employed to estimate the length of crack extension when there are multiple *** interaction between cracks is considered,which also includes the coalescence ***,various structures under different cyclic loads are examined to evaluate the accuracy of this *** results demonstrate the efficiency of the proposed approach in modeling fatigue crack growth and life *** behavior of life curves for the heterogeneous domain was as *** curves illustrate the breakpoints caused by utilizing discrete incremental life *** these points,the trend of the curves changed with the material properties and fatigue characteristics of the new material around the crack tips.

关键词： Fatigue life Crack coalescence Interface Incorporation technique Variable amplitude loading

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Distinct element modelling of fracture plan control in continuum and jointed rock mass in presplitting method of surface mining

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International Journal of Mining Science and Technology 2014年第6期24卷 871-881页

作者： Sharafisafa Mansour Aliabadian Zeinab alizadeh rezvan Mortazavi Ali Department of Mining Metallurgy and Petroleum Engineering Amirkabir University of Technology Department of Mining Engineering Sahand University of Technology

Controlled blasting techniques are used to control overbreak and to aid in the stability of the remaining rock formation. Presplitting is one of the most common methods which is used in many open pit mining and surface blast design. The purpose of presplitting is to form a fracture plane across which the radial cracks from the production blast cannot travel. The purpose of this study is to investigate of effect of presplitting on the generation of a smooth wall in continuum and jointed rock mass. The 2D distinct element code was used to simulate the presplitting in a rock slope. The blast load history as a function of time was applied to the inner wall of each blasthole. Important parameters that were considered in the analysis were stress tensor and fracturing pattern. The blast loading magnitude and blasthole spacing and jointing pattern were found to be very significant in the final results.

关键词：计划控制岩体裂隙预裂露天采矿元模型控制爆破技术炮眼间距爆炸载荷

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Engineering Nano/Microscale Chiral Self‑Assembly in 3D Printed Constructs

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Nano-Micro Letters 2024年第3期16卷 313-332页

作者： Mohsen Esmaeili Ehsan Akbari Kyle George Gelareh rezvan Nader Taheri‑Qazvini Monirosadat Sadati Department of Chemical Engineering University of South CarolinaColumbiaSC 29208USA TA Instruments Waters LLCNew CastleDE 19720USA Biomedical Engineering Program University of South CarolinaColumbiaSC 29208USA

Helical hierarchy found in biomolecules like cellulose,chitin,and collagen underpins the remarkable mechanical strength and vibrant colors observed in living *** study advances the integration of helical/chiral assembly and 3D printing technology,providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate *** designed reactive chiral inks based on cellulose nanocrystal(CNC)suspensions and acrylamide monomers,enabling the chiral assembly at nano/microscale,beyond the resolution seen in printed *** employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate *** techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks,and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates,as well as their post-flow ***,we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting *** insights into the interplay between the chiral inks self-assembly dynamics,3D printing flow kinematics and photopolymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments,ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length,as well as random orientation of chiral *** biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs.

关键词： Directed chiral self-assembly Cellulose nanocrystals Bioinspired nanocomposite 3D printing Rheology

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The Impact of Nitrogen-Fixing Bacteria, Iron, and Zinc Foliar Application on Dry Land Yellow Mustard (Brassica juncea) Grain and Oil Production

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Agricultural Sciences 2024年第7期15卷 719-728页

作者： Saeid Zehtab Salmasi Haleh Nasiri rezvan Heshmati Mohammad Reza Sarikhani Yagoub Raei Sustainable Agriculture Science Center Department of Plant and Environmental Sciences New Mexico State University Alcalde New Mexico USA Department of Plant Ecophysiology University of Tabriz Tabriz Iran Department of Soil Science University of Tabriz Tabriz Iran

The study, conducted at the Research Farm of the College of Agriculture, University of Tabriz in 2021, focused on the effects of various nitrogen-fixing bacterial isolates, biofertilizers containing nitrogen and phosphorus, as well as iron and zinc foliar applications on mustard growth under rainfed conditions. The results indicated that biofertilizers, whether used alone or in combination with chemical fertilizers, produced comparable grain and oil outputs compared to chemical fertilizers alone. Additionally, the application of iron and zinc through foliar spraying significantly enhanced both grain and oil production. These findings suggest that integrating nitrogen-fixing bacteria and biofertilizers could reduce reliance on chemical nitrogenous fertilizers, leading to decreased production expenses, improved product quality, and minimized environmental impact. This study highlights the potential for sustainable agricultural practices in dry land farming as a viable alternative to traditional chemical-intensive methods. Substituting chemical nitrogenous fertilizers with nitrogen-fixing bacteria or biofertilizers could result in cost savings in mustard grain and oil production while promoting environmental sustainability.

关键词： Nitrogen Fixing Bacteria Yellow Mustard Dry Land Farming Iron Zinc Foliar Application

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自复位学校建筑抗震韧性区域评估用数字孪生模型

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同济大学学报（自然科学版） 2023年第12期51卷 1879-1899页

作者： rezvan Pooya 张云峰马里兰大学土木与环境工程系公园市20742

在区域层面上对具有自复位模块结构的学校建筑进行抗震损伤和恢复力评估研究,建立了一个基于Python语言的从结构非线性分析到损伤程度可视化演示用的数字孪生模型。Python语言也是目前通用于机器学习模型训练的编程语言,方便在该数字孪... 详细信息

在区域层面上对具有自复位模块结构的学校建筑进行抗震损伤和恢复力评估研究,建立了一个基于Python语言的从结构非线性分析到损伤程度可视化演示用的数字孪生模型。Python语言也是目前通用于机器学习模型训练的编程语言,方便在该数字孪生模型中引入人工智能模型来代替结构仿真计算,通过使用实时监测地震动和结构响应数据结合人工智能模型进行区域灾害响应和功能恢复快速评估。结构损伤和恢复力分析结果(如不同地震下修复成本、修复时间、不可修复的概率等指标)通过生成shapefile在地理信息系统(GIS)软件中进行三维可视化,从而对采用自复位模块结构的学校建筑结构群在区域范围上进行抗震韧性定量评估。该模型的计算模块包括区域建筑结构清单生成、简化数值模型建立、地震响应非线性分析、结构响应参数生成、建筑结构易损部件定义、地震损失概率模型评估以及区域灾害损失的结果输出。这里的基于概率模型的学校建筑结构地震损失评估采用了FEMA P-58方法,并使用了Pelicun软件包进行计算。以旧金山湾区近2000栋学校建筑作为案例,对假定使用偏心支撑框架自复位结构作为抗震结构体系的学校建筑群进行了抗震韧性评估,研究了通过采用数字孪生模型对新型结构模块系统在学校建筑群区域灾害响应和功能恢复的影响。研究中使用了简化结构模型来缩短震后损伤和功能恢复仿真运算时间,同时提出了通过采用人工智能模型来实现强震后实时预测建筑群震后损失,并通过研究偏心支撑框架自复位结构体系的能量耗散比这一参数变化对学校建筑结构恢复力指标的影响,演示了采用不同的结构设计对建筑结构群在区域层面上的抗震损伤和恢复力的影响。

关键词：自复位结构区域地震灾害评估概率损伤评定数字孪生模型防灾减灾

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The antioxidant effects of hydroalcoholic extract of Ashrasi date palm on sperm parameters and DNA fragmentation in diabetic rats

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Animal Models and Experimental Medicine 2022年第3期5卷 281-287页

作者： Morteza Hosseinipour rezvan Asgari Javid Kermani Nader Goodarzi Mitra Bakhtiari Faculty of Veterinary Medicine Razi UniverstiyKermanshahIran Medical Biology Research Center Health Technology InstituteKermanshah University of Medical SciencesKermanshahIran Department of Basic and Pathobiological Sciences Faculty of Veterinary MedicineRazi UniverstiyKermanshahIran Fertility and Infertility Research Center Health Technology InstituteKermanshah University of Medical SciencesKermanshahIran

Background : Diabetes-induced oxidative stress can have adverse effects on sperm and its DNA integrity. The Ashrasi date palm(ADP) has potent antioxidant *** aim of this study was to evaluate the antioxidant effect of ADP hydroalcoholic extract on sperm parameters and sperm DNA fragmentation in diabetic *** : Forty male rats were randomly divided into five groups( n = 7): 1, control;2, diabetic;3– 5, diabetic + ADP(30, 90 and 270 mg/kg for groups 3, 4 and 5, respectively). After preparation of ADP extract and its phytochemical screening, it was administered orally to rats, once a day for 5 weeks. At the end of the study, sperm parameters and sperm DNA fragmentation in all groups were *** : At doses of 90 and 270 mg/kg, ADP extract significantly increased the sperm viability compared to diabetic group 2( p = 0.04 and p = 0.03, respectively)and resulted in a significant decrease in immotile sperm( p = 0.002 and p = 0.006,respectively). At a dose of 270 mg/kg, a considerable enhancement of forward sperm motility was observed( p = 0.04) and there was a significant decrease in sperm DNA fragmentation( p = 0.04).Conclusions : The findings of the present study show for the first time that the hydroalcoholic extract of ADP has protective and antioxidant effects against diabetesinduced oxidative stress and can improve sperm parameters and protect sperm DNA integrity.

关键词： antioxidant Ashrasi date palm diabetes oxidative stress

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Evaluation of rutting performance of stone matrix asphalt mixtures containing warm mix additives

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Journal of Central South University 2017年第2期24卷 360-373页

作者： rezvan Babagoli Hassan Ziari Department of Civil Engineering Faculty of Engineering Pardis Branch Islamic Azad University School of Civil Engineering Iran University of Science and Technology

Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures and thus a great deal of research has been focused on the development of a rheological parameter that would address the rutting susceptibility of both unmodified and modified bituminous binders. In this research, three warm mix additives(Sasobit, Rheofalt and Zycotherm) were used to modify 60-70 penetration grade base binder. The rutting potential of both modified and unmodified binders were evaluated through the multiple stress creep recovery(MSCR)-based parameter, nonrecoverable compliance(Jnr) and recovery parameter(R). Several performance tests carried on stone matrix asphalt(SMA) mixtures comprising different nominal maximum aggregate sizes(NMASs, 9.5, 12.5 and 19 mm), like Marshall stability, dynamic and static creep and Hamburg wheel tracking tests to evaluate their rutting performance. The objective of this work is to correlate MSCR test results to performance. Results indicate that for the range of the gradations investigated in this work, increasing the nominal maximum aggregate size of the gradation would increase the permanent deformation resistance of the SMA mixture. Addition of 3% sasobit to base binder leads an increase in Jnr100 about 82%. Addition of 2% rheofalt to base binder leads an recovery increase of about 9.76 % and 27.44% in stress levels of 100 and 3200 Pa, respectively. The results reveal that rutting resistance of mixtures improves as Jnr decreases. The use of the MSCR test in the rutting characterization of bituminous binders is highly recommended based on the results of this work.

关键词：抗车辙性能沥青混合料性能评价外加剂 SMA混合料改性沥青性能测试热拌

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Influence of N^+implantation on structure,morphology,and corrosion behavior of Al in NaCl solution

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Chinese Physics B 2020年第5期29卷 516-524页

作者： Hadi Savaloni rezvan Karami Helma Sadat Bahari Fateme Abdi School of Physics College of ScienceUniversity of TehranTehranIran

Structural and morphological changes as well as corrosion behavior of N+implanted Al in 0.6 M NaCl solution as function of N+fluence are *** x-ray diffraction results confirmed AlN *** atomic force microscope(AFM)images showed larger grains on the surface of Al with increasing N+*** can be due to the increased number of impacts of N+with Al atoms and energy conversion to heat,which increases the diffusion rate of the incident ions in the ***,the number of the grain boundaries is reduced,resulting in corrosion resistance *** impedance spectroscopy(EIS)and polarization results showed the increase of corrosion resistance of Al with increasing N+*** data was used to simulate equivalent electric circuits(EC)for the *** dependence of the surface morphology on the EC elements was *** scanning electron microscope(SEM)analysis of the samples after corrosion test also showed that the surfaces of the implanted Al samples remain more intact relative to the untreated Al sample,consistent with the EIS and polarization results.

关键词： aluminium ion implantation surface morphology corrosion electrochemical impedance spectroscopy polarization

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波斯语背景学生习得汉语常用时体的偏误分析

波斯语背景学生习得汉语常用时体的偏误分析

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作者： Zeynali rezvan（李织凡）郑州大学

学位级别：硕士

时体范畴广泛存在于人类各语言当中,一般可以通过词汇本身、语法表达和句法手段等多种方式来实现。语言不同,时体范畴实现的方式也存在差异。由于汉语和波斯语分属不同的语言体系(分别为汉藏语系和印欧语系)这两种语言在语法上,特别是... 详细信息

时体范畴广泛存在于人类各语言当中,一般可以通过词汇本身、语法表达和句法手段等多种方式来实现。语言不同,时体范畴实现的方式也存在差异。由于汉语和波斯语分属不同的语言体系(分别为汉藏语系和印欧语系)这两种语言在语法上,特别是动词时体上有着比较大的差别。在波斯语中,动词往往是整个语句的中心,它除了表达词汇意义之外,还用来表示整个句子的时体、式、数以及人称等功能。与波斯语不同,汉语的时体、人称、式和数不以动词本身来体现,而是通过句中专门用来表达时间的词汇配合主语和谓语体现的。由于波斯语中没有诸如汉语中的这类词汇,因此波斯语背景学生在学习汉语时体时会对汉语时体进行过度推测,导致在使用汉语助词或副词时常常出现偏误。笔者来中国留学后发现,虽然动词时体是汉语学习的一个很重要的语法点,但是目前还没有学者关注到两种语言的时体差异以及波斯语背景学生习得汉语时体的研究。笔者认为有必要对汉波两种语言的时体表达方式、波斯语背景学生习得汉语时体时出现的偏误情况进行介绍,并在分析偏误原因的情况下对症下药地提出解决的策略。本文通过问卷调查研究法获得波斯语背景学生习得汉语时体时的偏误语料,并对搜集到的语料进行分类归纳,然后分析波斯语背景学生习得汉语时体时经常出现的偏误类型,进而从母语的负迁移、汉波对比研究的缺乏、教师和教学和学习者自身因素等角度剖析出现偏误的原因,最后从教师角度、学生角度以及教学法方面提出相应的对策,以期对伊朗学生习得汉语时体范畴提供有益的指导。

关键词：汉语波斯语波斯语背景学生时体偏误

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Kinetics of gadolinium extraction with D2EHPA and Cyanex301 using single drop column

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Rare Metals 2016年第6期35卷 487-494页

作者： rezvan Torkaman Meisam Torab-Mostaedi Jaber Safdari Mohammad Ali Moosavian School of Chemical Engineering College of EngineeringUniversity of Tehran Nuclear Fuel Cycle Research School Nuclear Science and Technology Research Institute

The extraction kinetics of Gd（III） from the nitric acid medium using bis（2,4,4-trimethylpentyl） dithio- phosphinic acid （Cyanex301） and 2-ethylhexyl phosphoric acid （D2EHPA） in kerosene solution were measured by the single drop technique. The influences of hydrogen ion concentration, gadolinium ion concentration, extractant concentration, column height, and nozzle diameter on the extraction rate were investigated. The forward rate equations for the gadolinium extraction with D2EHPA and Cyanex301 were obtained. Based on the experimental results, the forward extraction rate constant was calculated. With the increase of D2EHPA or Cyanex301 concentration, the drop rising diameter and the value of interfacial tension decrease in the studied system, which shows that D2EHPA or Cyanex301 has interfacial activity as a kind of surfactant. Also, the droplet diameter and interfacial tension decrease with the increase of aqueous solution acidity. The experimental results show that the D2EHPA extractant provides faster extraction rate in comparison with Cyanex301 extractant, and it would be useful in industrial continuous extraction process.

关键词： Reaction kinetics Solvent extraction Single drop column Gadolinium Rare earths

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