Loading...
Search for:
jafarzadeh--s
0.147 seconds
Total 10434 records
Effect of specimen's age on mechanical properties of plastic concrete walls in dam foundations
, Article Electronic Journal of Geotechnical Engineering ; Volume 17 D , 2012 , Pages 473-482 ; 10893032 (ISSN) ; Mousavi, S. H ; Sharif University of Technology
2012
Abstract
According to available information and references, water leakage and internal erosion in bodies and foundations of embankment dams are the main reasons of many problems and failures. To reduce this risk in foundation, plastic cut off walls is one of the most reliable solutions. In this research the effect of specimen's age on the mechanical properties of plastic concrete was studied. This paper summarizes the test results which were conducted in unconfined and triaxial state. Plastic concrete specimens were prepared in the laboratory condition using the materials provided from the Silve dam site. Test results have shown that the time and confining pressure extremely affect the mechanical...
A new method for multi-objective optimal design of milling parameters by considering chatter vibrations
, Article 2019 SAE Automotive Technical Papers, WONLYAUTO 2019, 1 January 2019 through 1 January 2019 ; Volume 2019-January, Issue January , 2019 ; 01487191 (ISSN) ; Khodaygan, S ; Sohani, A ; Sharif University of Technology
SAE International
2019
Abstract
The desired milling process with high material removal rate (MRR) and low surface roughness of the product can be achieved only if machining chatter is absent. Incorporating chatter into the optimal selection of the machining parameters leads to a complex problem. Therefore, the approach of selecting conservative intervals for the machining parameters is usually employed instead. In this paper, a practical approach is proposed to specify the optimal machining parameters (depth of cut and spindle speed) in order to maximize MRR and minimize forced vibrations by considering machining chatter. Firstly, the worst-case scenario-based optimization problem in terms of the surface quality is solved...
Low energy yet reliable data communication scheme for network-on-chip
, Article IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems ; Volume 34, Issue 12 , 2015 , Pages 1892-1904 ; 02780070 (ISSN) ; Palesi, M ; Eskandari, S ; Hessabi, S ; Afzali-Kusha, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
In this paper, a low energy yet reliable communication scheme for network-on-chip is suggested. To reduce the communication energy consumption, we invoke low-swing signals for transmitting data, as well as data encoding techniques, for minimizing both self and coupling switching capacitance activity factors. To maintain the communication reliability of communication at low-voltage swing, an error control coding (ECC) technique is exploited. The decision about end-To-end or hop-To-hop ECC schemes and the proper number of detectable errors are determined through high-level mathematical analysis on the energy and reliability characteristics of the techniques. Based on the analysis, the extended...
Comparison on usefulness of two buried pipeline retrofitting methods in earthquake induced landslides with numerical modeling
, Article Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014, 22 September 2014 through 25 September 2014 ; September , 2015 , Pages 1071-1076 ; 9781138001480 (ISBN) ; Yoosefi, S ; Farahi Jahromi, H ; Samadiyan, M ; Sharif University of Technology
Taylor and Francis - Balkema
2015
Abstract
Landslides have disastrous influence on buried pipeline operation. In order to overcome this phenomenon, many retrofitting solutions have been proposed in literature and practice. This paper concentrates on the solutions which deal with pipe thickness change and rerouting method. As an answer to this,ABAQUS FE program has been used for numerical modeling. Soil-pipe interaction was modeled as hard and frictional contact in normal and tangential directions respectively. Typical geotechnical parameters of Tehran soil and predicted acceleration time history, compatible with Tehran geological condition, have been introduced to program for numerical calculations. Usefulness of two basic proposed...
Prediction of machining chatter in milling based on dynamic FEM simulations of chip formation
, Article Advances in Manufacturing ; Volume 6, Issue 3 , 2018 , Pages 334-344 ; 20953127 (ISSN) ; Movahhedy, M. R ; Khodaygan, S ; Ghorbani, M ; Sharif University of Technology
Shanghai University Press
2018
Abstract
Chatter vibration is a major obstacle in achieveing increased machining performance. In this research, a finite element model of chip formation in a 2D milling process is used to predict the occurrence of chatter vibrations, and to investigate the effects of various machining parameters on this phenomenon. The dynamic properties of the machine tool at the tool tip are obtained based on experimental modal analysis, and are used in the model as the cutter dynamics. The model allows for the natural development of vibration as the result of the chip-tool engagement, and accounts for various phenomena that occur at the chip-tool interface ultimately leading to stable or unstable cutting. The...
Dynamic compaction method in physical model tests
, Article Scientia Iranica ; Volume 13, Issue 2 , 2006 , Pages 187-192 ; 10263098 (ISSN) ; Sharif University of Technology
Sharif University of Technology
2006
Abstract
In this paper, physical modeling tests are conducted to study some aspects of the dynamic compaction method. The loose models are prepared with dry sand. Four cylindrical tampers with different weight and cross section areas are used for compaction of the models and dropped from various heights. Strain gage type total stress measuring sensors are placed at different levels inside the model to measure the transferred vertical stresses due to collision of the tamper with the surface of the models. The typical stress time histories are presented. Improvement depth and crater depth and diameter created on the model surface are studied, among the various parameters affecting the phenomena. Using...
3D response of the Masjed-Soleyman rockfill dam during strong motions
, Article International Journal on Hydropower and Dams ; Volume 12, Issue 2 , 2005 , Pages 84- ; 13522523 (ISSN) ; Sharif University of Technology
2005
Vibration isolation of foundations subjected to impact loads by open trenches using physical models
, Article 16th International Conference on Soil Mechanics and Geotechnical Engineering: Geotechnology in Harmony with the Global Environment, ICSMGE 2005, Osaka, 12 September 2005 through 16 September 2005 ; Volume 3 , 2005 , Pages 1497-1500 ; 9059660285 (ISBN); 9789059660281 (ISBN) ; Sharif University of Technology
2005
Abstract
Surface waves generated during vibration of machine foundations are sometimes troublemaking and cause some damages to the nearby sensitive structures or people. Considering the function of the machines located on the foundations the dynamic loading could be harmonic or impact type. The main part of the generated energy is transferred to the ground by Rayleigh surface waves. One of the most reliable and economic methods for reduction of the effects of these generated waves is using open trenches around the dynamic sources, so called active isolation in literature. In this paper applicability and affecting parameters of the open trenches around the impact dynamic source is studied using...
Metabolomics fingerprinting of the human seminal plasma of asthenozoospermic patients
, Article Molecular Reproduction and Development ; Vol. 81, Issue. 1 , 2014 , pp. 84-86 ; ISSN: 1098-2795 ; Moazeni-Pourasil, R. S ; Jafarzadeh, N ; Savadi-Shiraz, E ; Sharif University of Technology
2014
Abstract
It is estimated that 20% of couples are infertile, and half of these infertility cases are linked to men. One of conditions that can affect male fertility is asthenozoospermia. We applied Raman spectroscopy to the analysis of the metabolome of the human seminal plasma, and used chemometrics on the patterns of Raman spectra obtained. Significant changes were observed in the metabolome of the human seminal plasma of asthenozoospermic patients
Dynamic Parameters of Saturated and Unsaturated Sand at Different Range of Shear Strain Levels in Cyclic Simple Shear Test
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
In this investigation, a series of cyclic simple shear tests were carried out in order to evaluate dynamic parameters of Babolsar and Toyoura sand at levels of saturation 25, 50, 75 and 100%. 96 tests were conducted using SGI type cyclic simple shear device. The specimens were cylindrical, with 7cm diameter and 2.2 cm height. The tests were performed under both drained condition (constant-load) at levels of saturation 25, 50%, and undrained condition at levels of saturation 75, 100%. All tests were performed under vertical consolidation stress of 50 and 150 kPa, relative density of 30 and 70% and cyclic shear strain of 0.5, 5 and 10%. The tests were shear strain-controlled with an...
Evaluation of Dynamic Properties of Plastic Concrete Using Bending Disk Tests in Small Strain Range
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
Evaluation of the compression wave velocity (Vp ) and small strains elastic modulii of various types of plastic concrete specimens in unconfined and triaxial compression tests using piezoelectric transducers was performed in this study. Plastic concrete consists of aggregates, cement, water and bentonite, mixed at a high water cement ratio, to produce a ductile material. It is used for creating an impermeable cut-off wall for seepage control in highly permeable dam foundations. A plastic concrete cut-off wall acts essentially as a barrier to stop or reduce the groundwater flow. In this study the effect of specimen age, water-cement ratio, bentonite-cement ratio, confining pressure, wave...
Evaluation of Strength Parameters of Plastic Concrete by Triaxial Tests
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
This research are divided into the two main parts. In the first part, effective parameters for prediction of 28 days strength of plastic concrete have been determined. In this part, data mining operation was done on some informations which was sent from Silveh Dam construction site. In dam construction site, for quality control of plastic concrete which used in building of cut off wall some tests are done regurlarly in 7 and 28 days of concrecte production. In first part we used artificial neural network for predicting of relation between 28 days strength parameter and varios parameters of dam mixture content. The results has shown that the most effective parametes on 28 days strength...
Investigation of Dynamic Response of Shallow Foundations on Layered Soil Medium by Physical Modeling
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
Dynamic impedance functions method is most recent approach in the analysis of soil-foundation dynamic interaction, and presented for massless rigid foundations. Impedance functions are frequency dependent functions, and used to obtain dynamic response of foundation with arbitrary mass subjected to dynamic loading of any frequency and magnitude. The important assumptions for appropriate useof mentioned method are rigidity of foundation and visco-elastic behavior of the soil beneath the foundation. In this study, experimental vertical impedance functions of square and circular foundations have been investigated,using physical modeling tests. A granular soil layer with finite thickness...
Investigation of Dynamic Response of Shallow Foundations on Sandy Soil to Horizontal Harmonic Loading by Physical Model Tests
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
The most important step in current dynamic analysis of machine foundations is determining dynamic impedance functions. Impedance functions are defined as ratios of applied force or moment to induced displacement or rotation angle of foundation. In this research, horizontal dynamic response of foundation on homogeneous halfspace was investigated using physical modeling. Soil medium was built in a 1mx1mx0.8m steel box whose interior walls were covered by 0.1m of sawdust (a material with high damping). In order to prevent possible reflection of waves, this cover was extended to the box bottom with 0.2 m thickness. Sand raining method was used to build soil medium. In this method, with...
Electrochemical Preparation and Study of Transitional Metal Mixed Oxides as Supercapacitor Electrodes
, Ph.D. Dissertation Sharif University of Technology ; Gobal, Fereydoon (Supervisor)
Abstract
In this thesis, the improving effects of deposited metal oxides onto or next to each other and the advantages of every metal oxide were considered. In the next step, the substrate improvement was studied and the porous metal oxides with ideal supercapacitive properties with porosity increase of substrate were obtained.CoFeO2 supercapacitor was prepared by chronoamperometric ethod.CoFeO2waselectrodeposited at room temperature and presents wide potential window and good capacitive properties in comparison with other metal oxides.Layers of cobalt and manganese oxides were co-deposited or deposited on top of each other or next to each other by chronometric method onto stainless steel substrate....
Survey the Change of Phreatic Line Position in the First Filling of Earth Dams until Steady State Seepage
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
Since seepage-related problems account for the cause of more than forty percent of dam failure seepage analysis serves as one of the most significant stage in the design process of an embankment dam. Currently a steady seepage analysis in a typical or maximum cross section of the dam is formed instead of transient seepage analysis for simplicity. In this way, for the change of condition (unsaturated to saturated) in the first filling of dams and it’s effects on behavior and reaction of dams until the steady seepage condition established; the results of steady seepage analysis cannot be satisfactory. In this thesis, based on finite element method and with assumption of saturated-unsaturated...
Comparison of Slopes' Pgds Derived From Newmark Rigid Block Theory With 1g Shaking Table Model Tests
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
Moderate to large magnitude earthquakes trigger hundreds to thousands of slope stability failures and landslides in coherent masses. In many earthquakes, landslides have been responsible for as much or more damage than all other seismic hazards combined. Earthquake-induced landslides have a detrimental impact on the serviceability of slopes by damaging nearby structures, roadways, utilities, power lines and communication networks. In this research large-scale shaking table model tests were conducted to study slope behavior under earthquake conditions on Sharif University shaking table. The model slopes were installed into a model box with a length of 3 m, width of 1 m, and height of 1.5 m. A...
Investigation of Dynamic Response of Shallow Foundations on Layered Soils to Horizontal Harmonic Loading by Physical Model Tests
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
Increasing requirements of industries and research institutes to analytical results of interaction soil-foundation related systems, reveals the importance of the dynamic impedance functions than ever before. The dynamic impedance function relations are presented for massless rigid foundations which is possible to obtain dynamic response of foundations for different frequencies and masses accordingly. In this study, the dynamic impedance functions were investigated using physical modeling tests on sandy soil with finite thickness soil stratum over bedrock. The tests were carried out inside a steel container of dimensions 110.8m in length, width and height respectively which was filled into...
Determination of Mechanical and Fracture Properties of Nanostructure of Severe Shot Peened A356.0 at Room Temperature
,
M.Sc. Thesis
Sharif University of Technology
;
Farrahi, Gholamhossein
(Supervisor)
Abstract
The most failures caused by wear, fatigue and corrosion are very sensitive to surface of material. Since the most failures starts or occurs at the surface of material, so control and improvement of the surface properties can have a significant effect on increasing the service life and improve the overall behavior of the material. Reforming of the structure and grain size is one of the methods to improve elastic properties, hardness, softness, toughness, etc. Also the macroscopic residual stresses in fracture toughness test specimens, can have tremendous effect on fracture toughness measurements. Many methods are used to modify the surface structure and to create a compressive residual stress...
Investigation of Dynamic Response of Buried Pipelines under Earthquake-Induced Landslide using Physical Model Tests
, M.Sc. Thesis Sharif University of Technology ; Jafarzadeh, Fardin (Supervisor)
Abstract
The purpose of this dissertation is investigation of dynamic behavior of buried pipelines in slopes in landslide. For this purpose four physical models were made on shaking table of Sharif University of Technology. In each of the models some pipes were buried in slope. In these models the pipes were placed in different angles regarding to slope direction. Simulation laws suggested by Iai (1989) were used in these models. Babolsar sand was used for modeling the slopes. Aluminium pipes with outside diameter of 16 millimeters and thickness of 1 millimeter were implemented to model steel pipelines. In this investigation simple supports were used at the end of the pipes, considering the...