检索结果-南通市图书馆

Mechanical Properties of All MoS_(2) Monolayer Heterostructures:Crack Propagation and Existing Notch Study

Computers, Materials & Continua 2022年第3期70卷 4635-4655页

作者： reza khademi zahedi Naif Alajlan Hooman khademi zahedi Timon Rabczuk Institiute of Structural Mechanics Bauhaus-Universit鋞WeimarWeimar99423Germany Department of Computer Engineering King Saud UniversityRiyadhSaudi Arabia Mechanical Engineering Department Islamic Azad UniversityNorth Tehran BranchIran

The outstanding thermal,optical,electrical and mechanical properties of molybdenum disolphide(MoS_(2))heterostructures make them exceptional candidates for an extensive area of applications.Nevertheless,despite considerable technological and academic interest,there is presently a fewinformation regarding the mechanical properties of these novel two-dimensional(2D)materials in the presence of the defects.In thismanuscript,we performed extensive molecular dynamics simulations on pre-cracked and pre-notched all-molybdenum disolphide(MoS_(2))heterostructure systems using ReaxFF force field.Therefore,we study the influence of several central-crack lengths and notch diameters on the mechanical response of 2H phase,1T phase and composite 2H/1T MoS_(2) monolayers with different concentrations of 1T phase in 2H phase,under uniaxial tensile loading at room temperature.Our ReaxFF models reveal that larger cracks and notches decrease the strength of all 2D MoS_(2) single-layer heterostructures.Additionally,for all studied crack and notch sizes,2H phase of MoS_(2) films exhibits the largest strength.Maximum tensile stress of composite 2H/1T MoS_(2) nanosheet with different concentrations are higher than those for the equivalent 1T phase,which implies that the pre-cracked composite structure is remarkably stronger than the equivalent 1T phase.The comparison of the results for cracked and notched all-MoS_(2) nanosheet heterostructures reveal that the load bearing capacity of the notched samples of monolayerMoS_(2) are higher than the cracked ones.

关键词： Molybdenum disulphide(MoS_(2)) molecular dynamics simulations uniaxial tension cracks notches

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Finite element model updating of a large structure using multi-setup stochastic subspace identification method and bees optimization algorithm

引用

Frontiers of Structural and Civil Engineering 2019年第4期13卷 965-980页

作者： reza khademi-zahedi Pouyan ALIMOURI Institute of Structural Mechanics Bauhaus-Universitat WeimarWeimar 99423Germany Mechanical Engineering Department Shahid Chamran University of AhvazAhvazIran

In the present contribution, operational modal analysis in conjunction with bees optimization algorithm are utilized to update the finite element model of a solar power plant structure. The physical parameters which required to be updated are uncertain parameters including geometry, material properties and boundary conditions of the aforementioned structure. To determine these uncertain parameters, local and global sensitivity analyses are performed to increase the solution accuracy. An objective function is determined using the sum of the squared errors between the natural frequencies calculated by finite element method and operational modal analysis, which is optimized using bees optimization algorithm. The natural frequencies of the solar power plant structure are estimated by multi-setup stochastic subspace identification method which is considered as a strong and efficient method in operational modal analysis. The proposed algorithm is efficiently implemented on the solar power plant structure located in Shahid Chamran university of Ahvaz, Iran, to update parameters of its finite element model. Moreover, computed natural frequencies by numerical method are compared with those of the operational modal analysis. The results indicate that, bees optimization algorithm leads accurate results with fast convergence.

关键词： operational modal analysis solar power plant structure multi-setup stochastic subspace bees optimization algorithm sensitivity analysis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Investigating peak stresses in fitting and repair patches of buried polyethylene gas pipes

引用

Frontiers of Structural and Civil Engineering 2020年第1期14卷 147-168页

作者： reza khademi zahedi Pouyan ALIMOURI Hooman khademi zahedi Mohammad SHISHESAZ Institute of Structural Mechanics Bauhaus-Universitat WeimarMariensrtaβe 15Weimar 99423Germany Mechanical Engineering Department Shahid Chamran University of AhvazAhvazIran Mechanical Engineering Department Islamic Azad UniversityNorth Tehran BranchIran

Nowadays,polyethylene composes a large number of natural gas distribution pipelines installed under the ground.The focus of the present contribution is two fold.One of the objectives is to investigate the applicability of polyethylene fittings in joining polyethylene gas pipes which are electrofused onto the pipe ends and buried under the ground,by estimating stress distribution using finite element method.The second objective is to study the effectiveness of polyethylene repair patches which are used to mend the defected pipelines by performing a finite element analysis to calculate peak stress values.Buried polyethylene pipelines in the natural gas industry,can be imposed by sever loadings including the soil-structure interaction,traffic load,soil’s column weight,internal pressure,and thermal loads resulting from daily and/or seasonal temperature changes.Additionally,due to the application of pipe joints,and repair patches local stresses superimposed on the aforementioned loading effects.The pipe is assumed to be made of PE80 resin and its jointing socket,and the repair patch is PE100 material.The computational analysis of stresses and the computer simulations are performed using ANSYS commercial software.According to the results,the peak stress values take place in the middle of the fitting and at its internal surface.The maximum stress values in fitting and pipe are below the allowable stresses which shows the proper use of introduced fitting is applicable even in hot climate areas of Ahvaz,Iran.Although the buried pipe is imposed to the maximum values of stresses,the PE100 socket is more sensitive to a temperature drop.Furthermore,all four studied patch arrangements show significant reinforcing effects on the defected section of the buried PE gas pipe to transfer applied loads.Meanwhile,the defected buried medium density polyethylene gas pipe and its saddle fused patch can resist the imposed mechanical and thermal loads of 22℃ temperature increase.Moreover,increasing the saddle fusion patch length to 12 inch

关键词： Ansys software polyethylene buried pipelines polyethylene joints polyethylene patches peak von Mises stress soil-pipe interaction temperature variation

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nonlinear phenomena in vibrations of embedded carbon nanotubes conveying viscous fluid

引用

Nanotechnology and Precision Engineering 2024年第1期7卷 44-54页

作者： reza Ebrahimi Mechanical Engineering Faculty of EngineeringYasouj UniversityYasouj 75918-74831Iran

Various nonlinear phenomena such as bifurcations and chaos in the responses of carbon nanotubes(CNTs)are recognized as being major contributors to the inaccuracy and instability of nanoscale mechanical systems.Therefore,the main purpose of this paper is to predict the nonlinear dynamic behavior of a CNT conveying viscousﬂuid and supported on a nonlinear elastic foundation.The proposed model is based on nonlocal Euler–Bernoulli beam theory.The Galerkin method and perturbation analysis are used to discretize the partial differential equation of motion and obtain the frequency-response equation,respectively.A detailed parametric study is reported into how the nonlocal parameter,foundation coefﬁcients,ﬂuid viscosity,and amplitude and frequency of the external force inﬂuence the nonlinear dynamics of the system.Subharmonic,quasi-periodic,and chaotic behaviors and hardening nonlinearity are revealed by means of the vibration time histories,frequency-response curves,bifurcation diagrams,phase portraits,power spectra,and Poincarémaps.Also,the results show that it is possible to eliminate irregular motion in the whole range of external force amplitude by selecting appropriate parameters.

关键词： Nonlinear vibration Carbon nanotubes Nonlocal effect Viscousﬂuid Nonlinear elastic medium

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Resilence Control of DC Microgrid Integrated with Multi-Nanogrids Considering Connected-Islanded States

引用

CSEE Journal of Power and Energy Systems 2024年第2期10卷 786-796页

作者： Hossien Faraji reza Hemmati Pierluigi Siano Department of Electrical Engineering Amirkabir University of TechnologyTehranIran Department of Electrical Engineering Kermanshah University of TechnologyKermanshahIran Department of Management&Innovation Systems University of Salernoand also with the Department of Electrical and Electronic Engineering ScienceUniversity of JohannesburgJohannesburg 2006South Africa

In this paper, a DC microgrid (DCMG) integrated with a set of nano-grids (NG) is studied. DCMG exchanges predetermined active and reactive power with the upstream network. DCMG and NGs are coordinately controlled and managed in such a way the exchanged P-Q power with external grid are kept on scheduled level following all events and operating conditions. The proposed control system, in addition to the ability of mutual support between DCMG and NGs, makes NGs support each other in critical situations. On the other hand, in all operating conditions, DCMG not only feeds three-phase loads with time-varying active and reactive power on the grid side but also injects constant active power into the grid. During events, NGs support each other, NGs support DCMG, and DCMG supports NGs. Such control strategies are realized by the proposed control method to increase resilience of the system. For these purposes, all resources and loads in DCMG and NGs are equipped with individual controllers. Then, a central control unit analyzes, monitors, and regularizes performance of individual controllers in DCMG and NGs. Nonlinear simulations show the proposed model can effectively control DCMG and NGs under normal and critical conditions.

关键词： Control system DC microgrid nanogrid resilience

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Numerical investigation of supercontinuum generation and optical frequency combs in Si N-based PCF with high nonlinear coefficient

引用

Optoelectronics Letters 2024年第3期20卷 163-170页

作者： Mohammad reza Alizadeh Mahmood Seifouri Saeed Olyaee Faculty of Electrical Engineering Shahid Rajaee Teacher Training UniversityTehranIran Nano-photonics and Optoelectronics Research Laboratory(NORLab) Shahid Rajaee Teacher Training UniversityTehranIran

In this paper, a photonic crystal fiber(PCF) with a dispersion-engineered and high nonlinear coefficient has been designed for supercontinuum generation(SCG) and frequency comb generation(FCG). The proposed PCF has a Si_(3)N_(4) rod in the core. This rod provides more optical confinement in the core by increasing the refractive index of the core. This high confinement reduces the effective mode area of PCF and thus increases the nonlinear coefficient.

关键词： optical fiber nonlinear

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Movement Trend Alterations in the Periaqueductal Gray(PAG)-Employed Ratbot Navigation Are Correlated with Stimulation Parameters

引用

Journal of Bionic Engineering 2024年第2期21卷 866-876页

作者： Sina Khajei Abed Khorasani Mohammad reza Afarinesh Vahid Sheibani Neuroscience Research Center Institute of NeuropharmacologyKerman University of Medical SciencesKerman***Iran Cognitive Neuroscience Research Center Institute of NeuropharmacologyKerman University of Medical SciencesKerman***Iran

In previous studies,Periaqueductal Gray(PAG)stimulation was used to stop ratbots from moving.Due to the homology between the PAG and the intercollicular nucleus,which has been used for forward movement in birds,we investigated the possibility of PAG application to induce forward locomotion for the first time.Using a corridor maze,the traveled distances via PAG electrical stimulation were examined in nine Wistar male rats during three sessions.A custom-designed stimulator was developed to apply the stimulation.The results showed reductions in responses to stimulation over time.Accordingly,the traveled distances had negative slopes during the consecutive trials(in 8 out of the 9 rats),and the slope mean was significantly different from zero.There was a strong correlation between the stimulation parameters(electric Charge per Phase(CPP)and the Number of Pulses(NP))and the observed slopes.The negative Movement Slopes(MS)were highly correlated with the CPP and the NP,as the Pearson's linear correlation coefficients were−0.87 and−0.79,respectively.The MS-CPP coefficients of determination(R-squared)were also between 0.76 and 0.95.In addition,the MS-NP coefficients of determination were between 0.63 and 0.87.Thus,it is concluded that the electrical stimulation parameters influence the behavioral outcomes directly.Furthermore,the PAG area may be considered a suitable candidate for forward locomotion control in the future if the area is harnessed effectively to prevent undesirable chaotic behaviors.

关键词： Periaqueductal Gray(PAG) Navigation Ratbot Animal-robot Forward locomotion Movement slope

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cancer cell cycle heterogeneity as a critical determinant of therapeutic resistance

引用

Genes & Diseases 2024年第1期11卷 189-204页

作者： Ebrahim H.Maleki Ahmad reza Bahrami Maryam M.Matin Department of Biology Faculty of ScienceFerdowsi University of Mashhad*** MashhadIran Jagiellonian Centre for Experimental Therapeutics(JCET) Jagiellonian University31-007 KrakowPoland Doctoral School of Exact and Natural Sciences Jagiellonian University30-348 KrakowPoland Industrial Biotechnology Research Group Institute of BiotechnologyFerdowsi University of Mashhad*** MashhadIran Novel Diagnostics and Therapeutics Research Group Institute of BiotechnologyFerdowsi University of Mashhad***MashhadIran Stem Cell and Regenerative Medicine Research Group Iranian Academic Center for EducationCulture and Research(ACECR)Khorasan Razavi Branch917751376 MashhadIran

Intra-tumor heterogeneity is now arguably one of the most-studied topics in tumor biology,as it represents a major obstacle to effective cancer treatment.Since tumor cells are highly diverse at genetic,epigenetic,and phenotypic levels,intra-tumor heterogeneity can be assumed as an important contributing factor to the nullification of chemotherapeutic effects,and recurrence of the tumor.Based on the role of heterogeneous subpopulations of cancer cells with varying cell-cycle dynamics and behavior during cancer progression and treatment;herein,we aim to establish a comprehensive definition for adaptation of neoplastic cells against therapy.We discuss two parallel and yet distinct subpopulations of tumor cells that play pivotal roles in reducing the effects of chemotherapy:"resistant"and"tolerant"popula-tions.Furthermore,this review also highlights the impact of the quiescent phase of the cell cycle as a survival mechanism for cancer cells.Beyond understanding the mechanisms under-lying the quiescence,it provides an insightful perspective on cancer stem cells(CsCs)and their dual and intertwined functions based on their cell cycle state in response to treatment.More-over,CSCs,epithelial-mesenchymal transformed cells,circulating tumor cells(CTCs),and disseminated tumor cells(DTCs),which are mostly in a quiescent state of the cell cycle are proved to have multiple biological links and can be implicated in our viewpoint of cell cycle heterogeneity in tumors.Overall,increasing our knowledge of cell cycle heterogeneity is a key to identifying new therapeutic solutions,and this emerging concept may provide us with new opportunities to prevent the dreadful cancer recurrence.

关键词： Cancer stem cells(CSCs) Carcinoma Cell cycle heterogeneity Quiescence Therapy resistance Therapy tolerance Tumor dormancy

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Characteristics of turbulent flow in 3-D pools in the presence of submerged rigid vegetation in channel bed

引用

Journal of Hydrodynamics 2024年第1期36卷 158-169页

作者： Kourosh Nosrati Hossein Afzalimehr Jueyi Sui Hamid reza Reisifar Natural Disasters Prevention Research Center Faculty of Civil EngineeringIran University of Science and TechnologyTehranIran School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

In this study,the interaction between 3-D bedforms and submerged rigid vegetation has been investigated.Various laboratory experiments were conducted to study the distribution of flow velocity,Reynolds shear stress,turbulent kinetic energy,and skewness coefficients for a constant density of vegetation.Results showed that the velocity profile in the pool section deviates from those in the upstream section of the pool.It has been found that the dip parameter varied between 0.6H and 0.9H depending on various factors including bed roughness,vegetation distribution,and pool entrance/exit slopes.However,scattered vegetation in the pool and differences in slopes created non-uniform flow conditions.Also,in the wake region behind each vegetated element,flow velocity reduced significantly,and small-scale eddies are formed,causing increased perturbations.By decreasing the entrance slope and bed roughness,relatively uniform flow and weaker turbulence was resulted,but the random distribution of vegetated elements counteracted this balance and intensified turbulence.With the decrease in the pool entrance slope,the contribution of sweep event decreased and the contribution of ejection event increased.

关键词： Submerged rigid vegetation 3-D pool Reynolds shear stress skewness coefficients

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Efficiency improvement by using metal–insulator‑semiconductor structure in InGaN/GaN micro‑light‑emitting diodes

引用

Frontiers of Optoelectronics 2024年第1期17卷 77-84页

作者： Jian Yin David Hwang Hossein Zamani Siboni Ehsanollah Fathi reza Chaji Dayan Ban Department of Electrical and Computer Engineering Waterloo Institute NanotechnologyUniversity of WaterlooWaterlooON N2L 3G1Canada Vuereal InC. 440 Philip StreetUnit 100WaterlooON N2L 5R9Canada

InGaN/GaN micro-light-emitting diodes(micro-LEDs)with a metal–insulator-semiconductor(MIS)structure on the sidewall are proposed to improve efficiency.In this MIS structure,a sidewall electrode is deposited on the insulating layer-coated sidewall of the device mesa between a cathode on the bottom and an anode on the top.Electroluminescence(EL)measurements of fabricated devices with a mesa diameter of 10μm show that the application of negative biases on the sidewall electrode can increase the device external quantum efficiency(EQE).In contrast,the application of positive biases can decrease the EQE.The band structure analysis reveals that the EQE is impacted because the application of sidewall electric fields manipulates the local surface electron density along the mesa sidewall and thus controls surface Shockley–Read–Hall(SRH)recombination.Two suggested strategies,reducing insulator layer thickness and exploring alternative materials,can be implemented to further improve the EQE of MIS micro-LEDs in future fabrication.

关键词： Micro-LED GaN EQE improvement Micro-fabrication

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：