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A laboratory study of stress arching around an inclusion due to pore pressure changes

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第4期10卷 678-693页

作者： Hani Asaei mahdi moosavi Mohammad Ali Aghighi University of Tehran TehranIran

When the pore pressure in a porous rock changes, stress arching will occur within the rock and the surrounding region. Stress arching ratio is defined as the total stress changes in the porous rock to the pore pressure change in the region. The region may have the same or different elastic moduli with the surrounding rock, which is usually referred to as inclusion or inhomogeneity. Stress arching is responsible for many geomechanical problems encountered during production or injection; in addition, it is a crucial parameter in stress estimation during field development. This paper aims to present laboratory measurements of vertical stress arching ratio in a material surrounding the inclusion(inhomogeneity).To the authors’ knowledge, few laboratory experiments have been reported on direct measurement of stress arching. The inclusion is a cylindrical sandstone(44 mm in diameter and 50 mm in height)embedded in a larger cylindrical sandstone(150 mm in diameter and 154 mm in height), both of which are made synthetically. These two parts are separated and sealed by a internal polyurethane *** stress changes are recorded by a mini hydraulic sensor embedded in surrounding rock. Laboratory results are compared to those obtained by numerical models. These models are checked with analytical formulations. The results of numerical models show a good agreement with laboratory *** numerical results also indicate that the sensor response is affected by elastic properties of the internal sleeve. According to the sensitivity analysis performed, in the absence of the internal sleeve,properties of the inclusion have significant effects on the surrounding stress arching induced.

关键词： Stress arching Laboratory test Large-scale sample Synthetic sandstone

INVESTIGATION ON CREEP BEHAVIOR OF SALT ROCK UNDER HIGH TEMPERATURE WITH IMPRESSION TECHNIQUE Paper No.173

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INVESTIGATION ON CREEP BEHAVIOR OF SALT ROCK UNDER HIGH TEMP...

Initial estimation of hydrate formation temperature of sweet natural gases based on new empirical correlation

ISRM-Sponsored International Symposium on Rock Mechanics:"Rock Characterisation,Modelling and Engineering Design Methods"(SINOROCK2009)

作者： mahdi moosavi Mohammadamin Jafari Fatemeh Sadat Rassouli University of Tehran

ISBN: (纸本)9789628014170

Conventional creep testing requires many samples to study the time-dependent behavior of rocks which makes it time consuming and *** models and studying mechanisms is also difficult when there are sample-to-sample variations in the ***,a localized creep testing technique is *** methods such as indentations creep test have been used for measuring creep parameters in metals and alloys,glasses,ceramics and ***,indentation creep tests using a conical,pyramidal or spherical indenter do not show a steady state at constant *** turned out that a cylindrical indenter with a flat end gives a steady state penetration velocity at constant *** special kind of indentation creep is called 'impression creep'.One of the attractive features of the impression creep test is its ability to establish steady-state creep behavior within a very short time. For investigation on creep behavior of salt rock,several impression creep tests were performed which were carried out under constant stress(in the range of 30- 65 MPa).The temperature is an important factor that should be considered in all of the creep tests;therefore,some tests were implemented in different temperatures in the range of 250 -350°c and diversity of them was *** new creep test can be applied successfully on this soft *** a power law relation between the creep rate and applied stress,values of 3.28 and 4.72 are obtained for stress exponent (n) at low and high temperatures whereas the range for Q value(activation energy) was obtained as 40.7 and 27.0 kJ/mol again at low and high temperature.

关键词： Impression creep test salt rock time dependent behavior high temperature

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Journal of Natural Gas Chemistry 2012年第5期21卷 508-512页

作者： Mohammad mahdi Ghiasi Petroleum University of Technology Ahwaz Faculty of PetroleumPost Box:63431AhwazIran

Production,processing and transportation of natural gases can be significantly affected by clathrate *** the gas analysis is crucial to predict the right conditions for hydrate ***,Katz gas gravity method can be used for initial estimation of hydrate formation temperature （HFT） under the circumstances of indeterminate gas *** far several correlations have been proposed for gas gravity method,in which the most accurate and reliable one has belonged to Bahadori and *** main objective of this study is to present a simple and yet accurate correlation for fast prediction of sweet natural gases HFT based on the fit to Katz gravity *** reviewing the error analysis results,one can discover that the new proposed correlation has the best estimation capability among the widely accepted existing correlations within the investigated range.

关键词： natural gas hydrates hydrate formation temperature gas gravity method empirical correlation

Effective Controlled Islanding Method for Power Grids Solving a Sequence of Optimization Problems

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CSEE Journal of Power and Energy Systems 2022年第4期8卷 1004-1012页

作者： mahdi Amini Haidar Samet Ali Reza Seifi mahdi Davarpanah School of Electrical and Computer Engineering Shiraz UniversityShirazIran Department of Electrical Engineering Eindhoven University of TechnologyEindhoventhe Netherlands the Electrical and Computer Engineering School College of EngineeringUniversity of TehranTehranIran

Controlled islanding is an important approach to prevent instability in power *** this paper,a novel approach is proposed for power system separation,which consists of two steps:1)Finding multiple islanding scenarios;2)Choosing the best option to obtain the most desirable *** the first step,different islanding solutions are determined by a proposed hierarchical clustering *** this algorithm,which is based on a minimum active power flow disruption objective function,the generator coherency constraints are considered in the clustering *** the second step,the best separation scenario is chosen based on an arbitrary objective ***,in this paper,the amount of load shedding and the voltage profile deviation after separation are considered as the final criteria to select the best solution among available *** so doing,the degree of load importance is also taken into *** proposed two-step method is applied on an IEEE 9-bus test system and it is also evaluated on an IEEE 39-bus *** simulation results on the IEEE 39-bus grid and the comparative analysis with a state-of-the-art method confirm that the final islanding solution is more optimized based on the secondary criteria,which have not been addressed in the existing ***,the proposed method is computationally efficient and can be employed in real-scale power grids.

关键词： Graph theory hierarchical spectral clustering power system separation power system instability two-step approach.

Vanadium oxide nanotubes for selective catalytic reduction of NO_x with NH_3

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Chinese Journal of Chemical Engineering 2016年第7期24卷 914-919页

作者： Seyed mahdi Mousavi Faculty of Chemistry University of Kashan

Vanadium oxide （VOx） nanostructures, synthesized by hydrothermal treatment using dodecylamine as template, were evaluated for the selective catalytic reduction of NOx with ammonia （NH3-SCR）, The effect of solvent type in the reaction mixture （EtOH/（EtOH ＋ H20）） and time of hydrolysis was studied. The obtained materials were characterized by XRD, SEM, TEM and BET, The VOx nanorods （80-120 nm diameter and 1-4 μm length） were synthesized in 25 vol% EtOH/（EtOH ＋ H20） and the open-ended multiwalled VOx nanotube （50-100 nm inner diameter, 110-180 nm outer diameter and 0,5-2 pm length） synthesized in 50 vol% EtOH/（EtOH ＋ H20）. VOx nanotuhes performed the superior NH3-SCR activity under a gas hourly space velocity of 12,000 h-1 at low temperature of 250 ~C （NOx conversion of 893g ＆ N2 selectivity of 100%）, while most of the developed Vanadia base catalysts are active at high temperature （〉350 ℃）. The superior NH3-SCR activity ofVOx nanotubes at low tem- perature is related to nanocrystalline structure, special nanotube morphology as well as high specific surface area.

关键词： Hydrothermal Nanotubes NOx Pollution SCR

Uncertainty propagation in dynamics of composite plates: A semi-analytical non-sampling-based approach

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Frontiers of Structural and Civil Engineering 2020年第6期14卷 1359-1371页

作者： mahdi FAKOOR Hadi PARVIZ Faculty of New Sciences and Technologies University o f TehranTehran 14395-1561Iran

In this study,the influences of spatially varying stochastic properties on free vibration analysis of composite plates were investigated via development of a new approach named the deterministic-stochastic Galerkin-based semi-analytical *** material properties including tensile modulus,shear modulus,and density of the plate were assumed to be spatially varying and *** fields with first-order Markov kernels were utilized to define the aforementioned material *** stochastic fields were decomposed via application of the K arhunen-Loeve theorem.A first-order shear deformation theory was assumed,following which the displacement field was defined using admissible trigonometric modes to derive the potential and kinetic *** stochastic equations of motion of the plate were obtained using the variational *** deterministic-stochastic Galerkin-based method was utilized to find the probability space of natural frequencies,and the corresponding mode shapes of the plate were determined using a polynomial chaos *** proposed method significantly reduced the size of the mathematical models of the structure,which is very useful for enhancing the computational efficiency of stochastic *** methodology was verifed using a stochastic finite element method and the available results in *** sensitivity of natural frequencies and corresponding mode shapes due to the uncertainty of material properties was investigated,and the results indicated that the higher-order modes are more sensitive to uncertainty propagation in spatially varying properties.

关键词： composite plate spatially varying stochastic properties Galerkin method polynomial chaos approach semi-analytical approach

Shear wall layout optimization of tall buildings using Quantum Charged System Search

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Frontiers of Structural and Civil Engineering 2020年第5期14卷 1131-1151页

作者： Siamak TALATAHARI mahdi RABIEI Department of Civil Engineering University of TabrizTabriz ***Iran Engineering Faculty Near East UniversityNicosia 99138Turkey

This paper presents a developed meta-heuristic algorithm to optimize the shear walls of tall reinforced concrete *** types of walls are considered as lateral resistant *** this paper,Quantum Charged System Search(QCSS)algorithm is presented as a new optimization method and used to improve the convergence capability of the original Charged System *** cost of tall building is taken as the objective *** the design of the lateral system plays a major role in the performance of the tall buildings,this paper proposes a unique computational technique that,unlike available works,focuses on structural efficiency or architectural *** technique considers both structural and architectural requirements such as minimum structural costs,torsional effects,flexural and shear resistance,lateral deflection,openings and *** robustness of the new algorithm is demonstrated by comparing the outcomes of the QCSS with those of its standard algorithm.

关键词： Quantum Charged System Search shear wall layout optimization tall buildings

Feasibility of crack free reinforced concrete bridge deck from materials composition perspective： a state of the art review

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Frontiers of Structural and Civil Engineering 2015年第1期9卷 91-103页

作者： mahdi AREZOUMANDI Department of Civil Architectural and Environmental Engineering Missouri University of Science and Technology 212 ButlerCarlton Hall 1401 N. Pine Street Rolla MO 65409 USA

Early age cracking on bridge deck has been the subject of many studies for years. Cracking is a major concern because it leads to premature deterioration of structures. Millions of dollars spent to repair the cracked bridge decks each year. To design an appropriate mixture for crack free bridge deck, it is important to study previous researches. This paper presents a comprehensive literature review of the performance of different materials compositions as well as methods have been used to reduce and control bridge deck cracks. Different material compositions and methods are discussed in terms of their performances as well as advantages and disadvantages.

关键词： bridge deck crack fiber shrinkage shrinkage reducing admixture

SYNTHESIS AND APPLICATIONS OF CROSS-LINKED POLY(DIALLYLDIMETHYL AMMONIUM CHLORIDE) AND ITS DERIVATIVE COPOLYMERS AS EFFICIENT PHASE TRANSFER CATALYST FOR NUCLEOPHILIC SUBSTITUTION REACTIONS

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Chinese Journal of Polymer Science 2011年第2期29卷 165-172页

作者： Hossein Mahdavi mahdi Mahmoudian School of Chemistry University College of ScienceUniversity of TehranTehranIran

Cross-linked poly（diallyldimethylammonium chloride） and its derivative copolymers were synthesized and used as phase transfer catalyst in the nucleophilic substitution reaction especially halogen exchange *** additi... 详细信息

关键词： Poly(diallyldimethylammonium chloride) Phase transfer catalyst Nucleophilic substitution reaction Halogen exchange reaction