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Observation of cosmic rays by Alborz -1 array
, Article Iranian Journal of Physics Research ; Volume 17, Issue 3 , 2017 , Pages 473-484 ; 16826957 (ISSN) ; Sharif University of Technology
Isfahan University of Technology
2017
Abstract
The first phase of the Alborz Observatory Array (Alborz-1) consists of 20 plastic scintillation detectors each one with surface area of 0.25 m2 spread over an area of 40×40 m2 realized to the study of Extensive Air Showers around the knee at the Sharif University of Technology campus. The first stage of the project including construction and operation of a prototype system has now been completed and the electronics that will be used in the array instrument has been tested under field conditions. In order to achieve a realistic estimate of the array performance, a large number of simulated CORSIKA showers have been used. In the present work, theoretical results obtained in the study of...
Microstructure, mechanical properties, corrosion behavior and cytotoxicity of Mg-Zn-Al-Ca alloys as biodegradable materials
, Article Journal of Alloys and Compounds ; Vol. 607 , 2014 , Pages 1-10 ; ISSN: 09258388 ; Afshar, A ; Sharif University of Technology
2014
Abstract
Recently, considerable attentions have been paid to alloy Mg-4Zn-0.2Ca for biomedical applications due to its suitable biocompatibility and acceptable mechanical properties. In this work, the effects of the addition of different amounts of Al on microstructure, mechanical properties, degradation behavior, and biocompatibility of this alloy were investigated. The corrosion behaviors of the alloys were investigated through polarization tests, chronoamperometry analysis, immersion tests, and EIS experiments. The mechanical properties were analyzed by using tensile tests and compression tests. The results showed that the addition of Al up to 3 wt.% considerably modifies the degradation behaviors...
Surveying The Biodegradation Behavior, Biocompatibility and Mechanical Properties of Mg-4Zn-xAl-0.2Ca Alloys
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
Due to their favorable biodegradability, Magnesium and its alloys have always attracted such a lot of research interests for making temporary implants. With the same direction, Mg-4Zn-0.2Ca has recently absorbed lots of research interests, due to its excellent biocompatibility. As the most regarded draw back concerned with this alloy, poor corrosion resistance is frequently discussed. Accordingly, in the present work it has been tried to come over this problem by addition different amount of aluminum, including 1, 3, 5, 7.5, and 10 percent, to this alloy; without causing any negative effect on its biocompatibility, and to present a new alloy composition with modified degradation behavior....
A comprehensive evaluation between the efficiency of different treatments in modifying the properties and behavior of magnesium alloys as degradable biomaterials
, Article Materials and Corrosion ; Volume 68, Issue 9 , 2017 , Pages 995-1003 ; 09475117 (ISSN) ; Afshar, A ; Sharif University of Technology
2017
Abstract
The addition of alloying elements to magnesium leads to microstructural refinement and improves its properties. However, this strategy is accompanied by another concurrent phenomenon − that is − intergranular segregation and the formation of secondary phases in grain boundaries, deteriorating the properties. In this work, the efficacy of two main factors on modifying the mechanical properties and corrosion behavior of Mg-4Zn-1Al-0.2Ca alloy was investigated separately: 1) dissolution of secondary phases; and 2) grain refinement. Based on the results, heat treatment of the as-cast alloy can increase the UTS from 174.4 to 213.2 MPa, decrease the corrosion current density from 81 to 49 μA/cm2,...
Robot control using an inexpensive P300 based BCI
, Article 26th National and 4th International Iranian Conference on Biomedical Engineering, ICBME 2019, 27 November 2019 through 28 November 2019 ; 2019 , Pages 204-207 ; 9781728156637 (ISBN) ; Shamsollahi, M. B ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Brain Computer Interfaces (BCI) are an important concept of biomedical engineering because of their ability to improve life conditions for people with different disabilities. Lots of studies have worked on important characteristics of BCI systems, such as speed and accuracy, whereas price is an important aspect too. Thus, a low cost BCI system with high accuracy clearly can help more people. Our purpose in this study is to design a P300 based BCI system using a low-priced EEG headset which has an acceptable accuracy. Our final design got a mean real-time accuracy of 93.3% which is comparable to systems with much more expensive hardware. © 2019 IEEE
Multi-Directional Seismic Analysis and using ET Method in Estimation of the Results
,
M.Sc. Thesis
Sharif University of Technology
;
Esmaeil Pourestekanchi, Homayun
(Supervisor)
Abstract
Exact and safe structural analysis and design under various loadings is an important issue, which have engaged engineers for a long time. Till now, building design codes have suggested three main methods for seismic analysis of structures, which consist of: Static analysis, Pseudo-dynamic response spectrum analysis and Time history analysis. The first two methods are too approximate, especially in irregular structures which demand exact 3d analyses. The most reliable method is Time history method. With advance of computational tools, engineers tend toward using more reliable analysis methods and using old fashioned rough methods is becoming less popular. One of the issues, which is important...
The Effect of Earthquake Vertical Component on Nonlinear Analysis of Concrete Gravity Dams Using Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
Study of dams' behavior and their safety against earthquakes has been interesting due to the high rate of failure. In the past, this study was just about linear analysis of dams. However, the weakness of concrete in tensile strength results in cracks in body of dams. Therefore, the nonlinear analysis of these huge structures seems to be so important. Many researches have been done in this field to model dam-reservoir-foundation with effects of concrete nonlinearity. In spite of the fact that gravity dams' safety depends on cracking status and consequently on nonlinear behavior of concrete, we cannot reach accurate and suitable results for dynamic behavior of concrete dams because these...
Investigation of Endurance Time Method in Seismic Analysis of Vertically Irregular Elastic Steel Frames
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
Recent studies show that irregular structures have been damaged more than regular ones during earthquakes. This proves importance of seismic response determination of this type of structures. Today, Codes define irregularity in structures and restrict seismic analysis and design of these types of structures. The Endurance Time (ET) method is a time-history based dynamic pushover procedure for seismic analysis and design of structures that has been recently proposed in Sharif University. This thesis illustrates ET capability in analysis and design of vertically irregular frames. Irregular frames with three, seven and twelve story high were designed with two types of mass and stiffness...
Application of Endurance Time Method in Seismic Analysis of Bridges
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
In this research the appilication of a new method named Endurance Time (ET) analysis in seismic analysis of multi span bridges in linear and nonlinear ranges is investigated. Endurance Time is a time history based method of seismic analysis. In this method structure is subjected to an intensifying predefined acceleration function and different damage indices of the structure are evaluated through analysis time. The Endurance Time criterion and the Endurance Time acceleration functions have been generated in previous researchs of ET group. Using 7 earthquake records which are selected from hundred ones of PEER database based on FEMA p695 recommendations, several scaling methods are used to...
Three Dimensional Non-Linear Seismic Analyses of Buildings, Using Endurance Time Method
, Ph.D. Dissertation Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
Endurance Time Method (ET) is a type of dynamic pushover procedure in which the structure is analyzed under special series of accelerograms, called ET acceleration Functions (ETAF) and the response of structure is sketched versus time until the collapse state. With evaluating response curve and the time which damage in structure reach the expected value, the final assessment of structure can be made. In this dissertation, the application of ET method for Non-linear 3 dimensional seismic analysis of steel moment frames under earthquake multicomponent excitation is investigated. For this purpose, various patterns of ET loading are investigated and the most appropriate algorithm in...
Nonlinear Analysis of 3D Irregular concrete Structures by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
The structure performances during past earthquakes indicate the importance of predicting behaviors of irregular structures under earthquakes. If the irregularity exceeds an expected limit, a seismic analysis should be carried out by a dynamic analysis method. The Endurance Time (ET) is a time-history method, base on dynamic analysis for seismic analyzing and designing the structures, in which structures are subjected to intensifying accelerogram functions and their Endurance Time is measured. One of the most applicable methods for RCF analysis is the Concentrated Hinge Model which is used in this research too. The needed parameters for modeling plasticity in concentrated hinge are achieved...
Collapse Analysis of Steel Moment Frames Using Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
In Endurance Time method structures are subjected a set of predesigned intensifying excitations. These excitations are produced in a way that their response spectrum, while complying with a specified spectrum, intensifies with time. So they can be used approximately to simulate the average effects of several ground motions scaled to different intensities. In this study applicability of Endurance Time method for evaluating collapse potential of buildings is investigated. A set of steel moment frames is used for collapse assessment. The process of using Endurance Time method in collapse evaluation is explained with consideration of uncertainty effects. collapse fragility curves and collapse...
Application of Endurance Time Method in Performance-based Design
, M.Sc. Thesis Sharif University of Technology ; Esmaeilpour Estekanchi, Homayun (Supervisor)
Abstract
Endurance Time (ET) method is a dynamic analysis method in which the structure is subjected to an intensifying accelerogram and its response is recorded at different times.On the other hand a new method for designing earthquake resistant structures is Performance-Based Design (P-BD) method. P-BD is a methodology in which structural design criteria are expressed in terms of achieving a set of different performance objectives. In this research the application of ET method and target curve (which is defined based on ET method concepts) in the performance-based design has been studied.Correlating time in ET method and earthquake return period, the design,assessment and retrofitting of different...
Comparison Of Operation Of Metal Dampers In Steel Structures Based On Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
Based on special properties of metal dampers such as high energy dissipation, stable hysteric cycles and simple application, low cost, insensitivity to changes of temperature and ability to be substituted after occurring of earthquakes, they are being used for structures control. ADAS and SSD are two kinds of metal dampers which are connected to top of the chevron braces and under the middle of beams. When shear forces are applied, these dampers yield and enter the plastic zone. In Endurance Time (ET) method gradually intensifying acceleration functions are created in a manner that the linear and nonlinear response spectra of them, while being proportional to average of real earthquakes...
Valuation of Semi Rigid Steel Frame Connection with Torsional Plate and Its Optimal Placement
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanch, Homayun (Supervisor)
Abstract
Beam to column connections affect on the performance of the steel frames. Connections are assumed pin, semi rigid or rigid based on rigidity. Previously most steel structures designed as pin or rigid connections but lately many studies have been done on structures with semi rigid connections and these studies show that semi rigid connections have excellent properties that makes this connection a superior response such as less base shear, more economic, ability to absorb more energy and etc. In this study semi rigid connection with torsional plate has been studied. In addition to previous characteristics, this connection has special properties such as simple implementation, Dimension...
Life Cycle Cost Analysis and Value Based Seismic Design of Steel Structures
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanch, Homayun (Supervisor)
Abstract
Life-cycle cost analysis (LCCA) is an assessment tool for studying the performance of systems in many fields of engineering. In earthquake engineering LCCA demands the calculation of the cost components that are related to the performance of the structure in multiple earthquake hazard levels. In this work structural performance required for LCC estimation is achieved by performing ET analysis, while Incremental static and dynamic analyses are two procedures that can be traditionally used for estimating the seismic capacity of structural systems. In this method the structure is subjected to an increasing accelerogram which its time represents ascending earthquake intensities corresponding to...
Value Based Seismic Design of Concrete Structures by Endurance Time Method
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
The aim of this research is value based optimum design of structures to minimize the costs imposing on them during lifetime. For this purpose, an optimization procedure is used to get optimum solutions. Therefore, in this optimization problem, total costs are objective functions and required limits of codes are as the constraints. The costs include initial costs of constructing and life cycle costs. The weight of structural components and seismic consequences during the lifetime of structure are used as a criterion to assess initial costs and life cycle costs, respectively. In this research, seismic losses are determined based on the probabilistic seismic assessment framework, which depends...
Value-Based Seismic Design of Framed Tube System of Tall Steel Buildings
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayun (Supervisor)
Abstract
The objective of this research is to evaluate the concept of a new design methodology based on the total value of the structure namely Value Based Design of structures (VBD) by the use of potential benefits of the ET method. While prescriptive and also performance based approaches of seismic design commonly try to find a structure with lower initial cost satisfying a number of requirements under seismic actions, a new design approach to incorporate directly the concept of value in design procedure have been formulated here to achieve an economical design with lower total cost in its life time. In this method the design sections of structural elements are considered as optimization parameters...
Performance Evaluation of Membrane Bioreactors in Treating Municipal Wastewater
, M.Sc. Thesis Sharif University of Technology ; Torkian, Ayoub (Supervisor)
Abstract
Membrane bioreactors can replace the activated sludge process and the final clarification step in municipal wastewater treatment. The combination of bioreactor and crossflow microfiltration allows for a high chemical oxygen demand (COD) reduction of synthetic wastewater. In this study, experimental data from a laboratory scale membrane bioreactor are presented. In order to investigate the influence of various operating parameters such as hydraulic retention time (HRT), biomass concentration and organic loading rate on organic pollutant removal, the pilot scale submerged membrane bioreactor (SMBR) with a Polyvinylidene Fluoride (PVDF) hollow fiber membrane module was conducted using synthetic...
Evaluation of Seismic Behavior of Anchored and Unanchored Tanks By Using Endurance Time Method
,
M.Sc. Thesis
Sharif University of Technology
;
Esmaeilpour Estekanchi, Homayun
(Supervisor)
Abstract
Endurance Time (ET) method is a relatively general analysis method based on time history analysis for evaluation of structure systems under dynamic excitations resulted from earthquakes. Assessment criterion in this method is based on time of endurance of structure versus applied acceleration function and don't use parameters such as stiffness, lateral strength, period of structure and other dynamic characteristics straightly. Upper time of endurance means better operation. In this method, if assumed damage index stays under allowable limit until determined time of endurance then the structure assumed acceptable. In this study, nonlinear analysis of anchored and unanchored (on rigid base)...