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Coal pillar mechanics of violent failure in U.S. Mines

International Journal of Mining Science and Technology 2017年第3期27卷 387-392页

作者： maleki hamid maleki Technologies Inc. Spokane WA 99223 USA

This paper seeks to enhance the understanding that the horizontal stresses build up and release during coal pillar loading and unloading(post-failure) drawing upon three decades of observations, geomechanical monitoring and numerical modeling in bump-prone U.S. mines. The focus is on induced horizontal stress in mine pillars and surrounding strata as highly stressed pillars punch into the roof and floor, causing shear failure and buckling of strata; under stiff stratigraphic units of some western US mines, these events could be accompanied by violent failure of pillar cores. Pillar punching eventually results in tensile stresses at the base of the pillar, facilitating transition into the post-failure regime; this transition will be nonviolent if certain conditions are met, notably the presence of interbedded mudstones with low shear strength properties and proper mine designs for controlling seismicity and dynamic loads. The study clearly shows high confining stress build-up in coal pillars resulting in up to twice higher peak vertical stress and high strain energy accumulations in some western US mines in comparison with peak stresses predicted using common empirical pillar design methods. It is the unstable release of this strain energy that can cause significant damage resulting from pillar dilation and ground movements. These forces are much greater than the capacity of most common internal support systems, resulting in horizontal stressinduced roof falls locally, in mines under unremarkable far-field horizontal stress. Attention should be placed on pillar designs as increasing support density may prove to be ineffective. This mechanism is analyzed using field measurements and generic finite-difference stress analyses. The study confirms the higher load carrying capacity of confinement-controlled coal seams in comparison with structurally controlled coal seams. Such significant differences in confining stresses are not taken into account when estimating peak pil

关键词：煤柱应力美国西部煤矿水平应力力学地层单位设计控制能量积累

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Improving shipboard electronics cooling system by optimizing the heat sinks configuration

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Journal of Ocean Engineering and Science 2022年第5期7卷 498-508页

作者： hamid maleki Mohammad Reza Safaei Arturo S.Leon Taseer Muhammad Truong Khang Nguyen Department of Mechanical Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Department of Mechanical Engineering Florida International UniversityMiamiFL 33174USA Department of Medical Research China Medical University HospitalChina Medical UniversityTaichungTaiwan Mechanical Engineering Department Faculty of EngineeringKing Abdulaziz UniversityJeddahSaudi Arabia Department of Civil and Environmental Engineering Florida International UniversityMiamiFL 33174USA Department of Mathematics College of SciencesKing Khalid UniversityAbha 61413Saudi Arabia Division of Computational Physics Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Electrical and Electronics Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam

With the increase of high-power electrical components in modern ships,especially fully electric ships with electric propulsion drive(EPD),the cooling of EPD electrical components has become particularly *** optimal configurations for heat sinks with high thermal efficiency plays an essential role in this regard.A new technique for improving the efficiency of heat sinks is the utilization of perforated *** study examined the effects of perforation geometry(shape and size)on laminar airflow flow and heat transfer characteristics over a perforated plate-fin heat ***-dimensional simulations were conducted using the finite-volume scheme based on the SIMPLE *** this research,the effects of perforation shape and size on various parameters,e.g.,total drag force,average Nusselt number,perforated fin efficiency(PFE),heat transfer performance enhancement(HTPE),and fin optimization factor(η)were *** results confirmed that at a specific heat transfer surface area for perforated fins,the highest efficiency is achieved by circular *** contrast,the square perforations due to geometric similarity to rectangular fins could reach the maximum ***,fins with square perforations could achieve the most optimal ***,results showed that for a constant perforations size,change in perforations shape improves HTPE,PFE,andηby more than 40%,45%,and 110%,***,by modifying perforations size for a specified shape,an increment of more than 35%,40%,and 150%is observed in HTPE,PFE,andη,respectively.

关键词： Forced convection Laminar flow Perforated fin Plate-fin heat sink Nusselt number

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Towards the development of integrated monitoring system for retreat mining operations

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Journal of Coal Science & Engineering(China) 2008年第3期14卷 477-484页

作者： hamid maleki maleki Technologies Inc.Spokane WA 99201USA

Through cooperative research between the government,the private sector, mining companies and equipment manufacturers,considerable progress had been made during the last decade in studying the mechanics of strata failure and acquiring the know- ledge needed to develop an integrated monitoring system for assessing local roof stability. Because of higher geotechnical risks in retreat mining operations,it was both important to develop panel layout designs that control convergence and stress and to monitor ground response during operations to verify designs and provide warning of impending stability *** detecting both localized roof stability problems and global overburden col- lapse mechanisms,the proposes an integrated panel-wide monitoring system which com- bines the capabilities of load rate monitoring of mobile roof supports (MRSs) with deforma- tion measurements using an extensive array of sensors located near the mining face and throughout the *** monitoring methods for the detection of localized roof stability problems have been evaluated on the basis of mine measurements and numerical model- ing *** are load rate monitoring of the hydraulic cylinders of mobile roof support (MRS) and re mote monitoring of roof *** of field data in retreat sections show that roof instabilities are influenced by: (1) pillar failure,(2) pillar yielding,(3) mine seismicity (bumps),(4) geologic structures,and (5) panel layout designs and practice. Pillar yielding and unloading can be conveniently monitored by the load rate monitoring device,but to detect impending localized roof falls,additional ground deformation meas- urements are needed near the mining *** increasing the number of deformation measurements in the entire panel,additional safeguards can be achieved for detecting overburden collapse mechanisms while continuously monitoring local roof stability close to the retreat line.

关键词：监控系统采煤监控煤炭开采支撑系统

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Correlation between critical thinking and emotional intelligence:a national crosssectional study on operating room nursing students in Iran

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Frontiers of Nursing 2024年第1期11卷 99-104页

作者： Armin Fereidouni Esmaeil Teymoori Tayebeh Bahmani hamid Reza Sabet Zahra maleki Mina Gharibi Department of Operating Room Technology Community Based Psychiatric Care Research CenterSchool of Nursing and MidwiferyShiraz University of Medical SciencesShirazIran Department of Operating Room Technology School of Paramedical SciencesAJA University of Medical SciencesTehranIran Department of Operating Room School of Allied Medical ScienceFasa University of Medical SciencesFasaIran Clinical Education Research Center Shiraz University of Medical SciencesShirazIran Medical Journalism Department School of Paramedical SciencesShiraz University of Medical SciencesShirazIran Department of Epidemiology Student Research CommitteeShiraz University of Medical SciencesShirazIran

Objective:According to the World Federation of Medical Education,critical thinking should be part of the training of medical and paramedical *** can improve the quality of care of patients after surgery by having or acquiring this skill in health ***,Emotional intelligence is introduced as an impor tant and effective factor on the professional performance and mental health of healthcare ***,the present study was designed and implemented to determine the relationship between emotional intelligence and critical thinking among operating room nursing students of medical sciences universities in ***:This cross-sectional study was done on 420 operating room students in 10 top medical sciences universities of Iran in *** sampling method in this research was multistage *** data collection instruments included demographic characteristics,Rickett's critical thinking,and Bradberry-Greaves'emotional intelligence *** receiving the ethics code,data collection was done for 2 *** data analysis,descriptive and inferential analyses including independent t-tests,analysis of variance,and Pearson correlation were *** collected data were analyzed by SPSS 18(IBM Corporation,Armonk,New York,United States).P-value<0.05 was considered ***:The mean age of the students participating in this study was 23.02±3.70 years,with women constituting 67.4%of *** results of data analysis indicated that the mean total score of critical thinking and emotional intelligence was 124.10±37.52 and 114.12±43.63,respectively.A direct significant correlation between critical thinking and emotional intelligence(r=0.459,P-value<0.001)and a significant relationship between gender and emotional intelligence(P-value=0.028)were ***:Based on the present study results,educational managers in the Ministry of Health are suggested to consider suitable educational programs for improving critical think

关键词： critical thinking emotional intelligence operating room students operating room nurses

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The concept of capital before and after industrial revolution： Islamic versus market economy

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Chinese Business Review 2009年第9期8卷 44-48,64页

作者： Farhang Mossavar-Rahmani hamid maleki School of Business and Management National University La Jolla CA 92037 USA

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辐射滑移边界条件下多孔板上的传热与纳米流体流动（英文）

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Journal of Central South University 2019年第5期26卷 1099-1115页

作者： hamid maleki Jalal ALSARRAF Abbas MOGHANIZADEH Hassan HAJABDOLLAHI Mohammad Reza SAFAEI Department of Mechanical Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran Department of Automotive and Marine Engineering Technology College of Technological StudiesThe Public Authority for Applied Education and TrainingKuwait Biomaterial Research Group Department of Materials EngineeringIsfahan University of TechnologyIsfahan 84156-83111Iran Department of Mechanical Engineering Vali-e-Asr University of RafsanjanRafsanjanIran Division of Computational Physics Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Electrical and Electronics Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam

考虑多孔表面上的纳米流体在不同时期不同值下可能会发生热性能变化。本研究的目的是研究纳米粒子的体积分数、纳米粒子的种类、吸入或注入、热的产生或吸收、Eckert数、热和速度滑移参数以及辐射对多孔平板上流体流动和传热的影响。研... 详细信息

考虑多孔表面上的纳米流体在不同时期不同值下可能会发生热性能变化。本研究的目的是研究纳米粒子的体积分数、纳米粒子的种类、吸入或注入、热的产生或吸收、Eckert数、热和速度滑移参数以及辐射对多孔平板上流体流动和传热的影响。研究了4种不同类型的纳米粒子,Cu纳米颗粒、Al2O3纳米粒子和碳基纳米材料(MWCNTs和SWCNTs),分散在水中的情况。利用相似解将控制方程转化为常微分方程,并用RKF45算法进行数值求解。模拟结果与其他研究人员的结果相矛盾,其他研究人员认为,使用具有高导热系数的高体积分数的纳米粒子可提高纳米流体的传热速率;本研究证明,当辐射、热产生和粘滞耗散等参数值发生显著变化时,提高纳米粒子的体积分数可能会降低传热速率。

关键词：辐射滑移条件多孔表面热产生/吸收黏性耗散纳米流体

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Islamic economics versus market economics： The concept of taxations

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Chinese Business Review 2009年第12期8卷 27-35页

作者： Farhang Mossavar-Rahmani hamid maleki School of Business and Management National University San Diego CA-18047 USA

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An investigation on the strain accumulation of the lightly EICP-cemented sands under cyclic traffic loads

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Journal of Road Engineering 2023年第2期3卷 203-217页

作者： Emad maleki Tabrizi hamid Reza Tohidvand Masoud Hajialilue-Bonab Elham Mousavi Saba Ghassemi Department of Civil Engineering University of TabrizTabriz 51666-16471Iran

Industrial production of chemical cement leads to extreme emissions of greenhouse *** or bioinspired sustainable materials for soil treatment projects can be employed instead of chemical cement to heal the carbon cycle in the *** enzyme-induced calcite precipitation(EICP)method is one of the novel bio-inspired technologies that can be employed in soil treatment projects to increase desired properties of *** the monotonic and cyclic behavior of the enzymatically treated sands has been investigated comprehensively,the strain accumulation pattern in these improved soils under cyclic traffic loads has not been evaluated *** this paper,confined and unconfined cyclic compression tests are applied to the enzymatically lightly cemented sands,and the effects of the different parameters on their strain accumulation pattern are investigated for the first time in the *** study uses two types of specimens with unconfined compression strengths(UCS)equal to 42 kPa and 266 *** is shown that the treated specimens have a rate-dependent behavior where cyclic loads with low frequencies lead to more resilient and plastic strains in the *** results show that by approaching the maximum applied stresses to the UCS of the specimens(by breaking more calcite bonds between sand particles),the rate dependency behavior of specimens will *** of the effects of the cementation level demonstrated that by increasing the amount of the precipitated calcite from 0.38%to 0.83%,accumulated plastic strains are reduced almost 95%under the same loading *** of the initial static loads,confining pressures,the number of cycles,and amplitudes of the cyclic loads are also evaluated.

关键词： Traffic load EICP method Bio-inspired treatment Unconfined compression Confined compression

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间隙尺寸和循环热冲击处理对瞬时液相扩散连接IN-738LC高温合金力学性能的影响（英文）

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Transactions of Nonferrous Metals Society of China 2018年第5期28卷 920-930页

作者： Vahid maleki hamid OMIDVAR Mohammad-Reza RAHIMIPOUR Department of Mining and Metallurgical Engineering Amirkabir University of Technology (Tehran Polytechnic) Department of Ceramic Materials and Energy Research Center

研究间隙尺寸和循环热冲击处理对瞬时液相扩散连接IN-738LC高温合金力学性能的影响。用粉末状AMS 4777作为焊料在真空炉中对IN-738LC高温合金进行瞬时液相扩散连接试验。结果表明,等温凝固区由Ni固溶体组成,且合金化元素分布均匀。间隙... 详细信息

研究间隙尺寸和循环热冲击处理对瞬时液相扩散连接IN-738LC高温合金力学性能的影响。用粉末状AMS 4777作为焊料在真空炉中对IN-738LC高温合金进行瞬时液相扩散连接试验。结果表明,等温凝固区由Ni固溶体组成,且合金化元素分布均匀。间隙尺寸为40μm的样品具有HV409的高硬度和506 MPa的高强度。在等温凝固区,合金化元素形成γ′析出相及Ni固溶体。合金连接处的硬度和强度随间隙尺寸(40~120μm)的增大而降低。完全等温凝固连接处的断裂表面呈韧窝断裂;非热凝固连接处呈解理断裂。对间隙尺寸为80μm的样品分别进行10、20、30和40次循环热冲击试验。经过40次循环热冲击后,合金连接处的剪切强度为268 MPa。当循环热冲击次数为45时,由于接合面上的裂纹形核,间隙尺寸为80μm的合金样品发生断裂。由于受到循环热冲击,在水浴中对合金样品进行水淬后样品脆性增强。

关键词： IN-738高温合金瞬时液相扩散连接力学性能循环热冲击处理剪切强度

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间隙大小对瞬时液相连接IN-738LC高温合金显微组织的影响（英文）

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Transactions of Nonferrous Metals Society of China 2016年第2期26卷 437-447页

作者： Vahid maleki hamid OMIDVAR Mohammad-reza RAHIMIPOUR Department of Mining and Metallurgical Engineering Amirkabir University of Technology (Tehran Polytechnic) Department of Ceramic Materials and Energy Research Center

以AMS 4777粉末为填料,研究瞬时液相连接IN-738LC高温合金的显微组织演变,获得完全等温凝固时间。研究间隙大小和连接时间对接头组织的影响。当间隙大小为40μm时,完全等温凝固时间为45 min。在不完全等温凝固的情况下,连接区的残余液... 详细信息

以AMS 4777粉末为填料,研究瞬时液相连接IN-738LC高温合金的显微组织演变,获得完全等温凝固时间。研究间隙大小和连接时间对接头组织的影响。当间隙大小为40μm时,完全等温凝固时间为45 min。在不完全等温凝固的情况下,连接区的残余液相在非平衡条件下冷却,形成γ-γ共晶相。间隙大小与时间存在非线性关系。随着间隙增大,共晶相变宽。在扩散影响区,发现大量合金元素,其浓度达到峰值,这是由于形成了硼化物和硅化物等金属间化合物。随着间隙增加,所需连接时间增加,合金元素有更多的时间进行扩散和分布至更大区域。因此,合金元素浓度随间隙增加缓慢降低。已有双相模型不能准确预测IN-738LC-AMS 4777-IN738LC瞬时液相连接系统的完全等温凝固时间。

关键词： IN-738LC高温合金瞬时液相连接间隙大小完全等温凝固

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