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Studying Parameters Affecting the Quality of Sponge Iron Produced by Hoganas Process

, M.Sc. Thesis Sharif University of Technology Asadi Karam, Amir (Author) ; Halali, Mohammad (Supervisor)

Abstract

Hoganas is a gas based process which is more than a hundred years old. In this research, studying parameters affecting the quality of sponge iron like temperature, time, particle size, type of reductant, type and dimension of crucible were discussed. Groups of particle size was 0-150,150-500,500-1000microns and temperature range was 900, 950, 1000, 1100, 1150°C. Time of tests was between 2 to 30 hours.at 1000 °C and 10 hours maximum metallization degree was 94.76.while at 1100 °C and 5hours better metallization degree was achieved. at 1000 °C and 5 h, particles with 500-1000micron size had better result than other groups.at higher temperature effect of particle size was gradually decreased...

Modeling and Analysis of the Factors Influencing the Crash-injury Severities in Iran

, M.Sc. Thesis Sharif University of Technology Asadi, Roksana (Author) ; Samimi, Amir (Supervisor)

Abstract

Traffic safety is one of the fundamental part of the transportation planning which is led to lowest the number of crashes and its following consequences by in-depth studying. Thus, determining the severity of accidents, including damage, injury and fatal injury is very important. The aim of this study is analysis of the accident-injury severities in single-vehicle and multi-vehicle crashes and providing the policies in Iran. The approach used in this study to select the most effective parameters of the injury-severity is based on the data gathered in Iran Road Maintenance and Transportation Organization during the year 2011. Accident probabilistic model based on analysis of relations among...

Numerical and Experimental Investigation of Swirl and Preheat Effects in a Double-Swirl Gas Turbine Model Combustor

, M.Sc. Thesis Sharif University of Technology Asadi, Benyamin (Author) ; Mardani, Amir (Supervisor)

Abstract

High swirl combustors with circulative structures in the flow field, have a highly flame stability with a wide range of operating conditions. In this study, Sharif Gas Turbine Model Combustor (SGTMC) which is a double high swirl burner, was investigated experimentally and numerically. In experimental studies, SGTMC with different settings of swirlers is investigated in terms of flame lean blow-out(LBO), wall temperature, the exhaust gas composition and pollutant and also flame geometry parameters. Setting of burner are changed by variations in air fraction between inner and outer air inlets or swirlers’ vanes degrees and flow rotation directions. The results indicate that the concentrations...

Improving Performance and Endurance of Solid-State Disk Drives in Data Centers Using Input/Output Scheduling

, M.Sc. Thesis Sharif University of Technology Mirabi, Amir Ali (Author) ; Asadi, Hossein (Supervisor)

Abstract

With prominent features such as lower power consumption, shock resistance, and smaller size, SSDs are widely being used in portable applications. In addition, SSDs are becoming more popular in data storage systems and servers due to their even access and fast response time. Several efforts have been made in the past few years to improve the performance of SSDs. One common technique to improve performance is designing an Input/Output (IO) scheduler based on SSD organization.
In this thesis, we propose an IO scheduling algorithm to improve both performance and endurance of SSDs. Since in-place update is not allowed in flash chips, erasure before any data overwriting is required. As...

Modeling of Cohesive Crack Propagation with Energy Method using XFEM

, M.Sc. Thesis Sharif University of Technology Asadi, Mansure (Author) ; Khoei, Amir Reza (Supervisor)

Abstract

Crack propagation in materials is an attractive problem in engineering because of the impact on the safety as well as economic issues. Much research studies have been done on the crack initiation, crack propagation criteria and path in the materials with different characteristics and conditions. Crack modeling depending on the material properties in brittle and quasi-brittle materials is done as Linear Elastic Fracture Mechanics (LEFM) and cohesive crack, respectively. The aim of this thesis is the modeling of crack propagation using energy method and comparing it with the cohesive crack. In order to model this problem, it is necessary to solve the governing equilibrium equation of the...

Flash Translation Layer Optimization for Zoned Namespace Solid State Drives based on I/O Cache

, M.Sc. Thesis Sharif University of Technology Binesh, Amir Hossein (Author) ; Asadi, Hossein (Supervisor)

Abstract

In recent years, with the rise of data-driven applications, ensuring performance has become a major challenge in the design of storage systems. One of the main reasons for the lack of performance guarantees is the presence of the Flash Translation Layer (FTL) in solid-state drives (SSDs). Recently, Zoned Namespace SSDs (ZNS SSDs) have been commercially introduced. In these drives, FTL tasks such as data placement and garbage collection are delegated to the operating system. Many research efforts on these devices have explored their potential as application-specific storage stacks. However, a review of prior studies shows that none have examined the performance issues caused by the FTL on...

Designing and Evaluation of Hardware Backdoors In a Typical Processor

, M.Sc. Thesis Sharif University of Technology Asadi, Mohammad Reza (Author) ; Jahangir, Amir Hossein (Supervisor)

Abstract

Recently, security of integrated circuits has received more attention as ICs have become more complex and their usage has increased in safety critical systems. Many orgeniaztions use the ICs that made by third party companies. This is due to the high costs to build and maintain state-of-the-art semiconductor factories. This subject puts the trustworthiness of the ICs under the question. The chips might be maliciously modified in each stage of the manufacturing chain. This threat is called hardware backdoor in scientific community. The aim of this project is to assess the features embedded in a microprocessor and evaluate the side channel effect of various hardware backdoors. hardware...

An I/O Cache Architecture in Open-Channel Solid-State Drives

, M.Sc. Thesis Sharif University of Technology Bazkhaneh, Amir Hossein (Author) ; Asadi, Hossein (Supervisor) ; Sarbazi Azad, Hamid (Supervisor)

Abstract

Despite low time intervals between requests in many real-world workloads, the flash chip utilization remains very low, leaving the storage device mostly idle. This affects the performance of flash chips in Solid-State Drives (SSDs) and directly correlates with the diminished operational efficiency of these storage devices. Recent studies involve statistical analyses and workload behaviour modelling to maintain the operational efficiency of SSDs. However, due to the unavailability and non-disclosure of the internal control unit structure of conventional SSDs, namely Flash Translation Layer (FTL), the underlying assumptions of these methodologies are deviating from practical realities....

Experimental Investigation of Velocity Field Due to Liquid Droplet Impingement Onto the Surface af a Molten Phase Change Material

, M.Sc. Thesis Sharif University of Technology Asadi, Mohammad Reza (Author) ; Shafii, Mohammad Behshad (Supervisor) ; Ghahremani, Amir Reza (Co-Supervisor)

Abstract

The impact of droplets is a widely used method for creating direct heat transfer between two fluids. This method enhances heat transfer between the working fluid and the phase change material (PCM). Therefore, a thorough investigation has been carried out on the impact of an acetone droplet on the surface of a pool of molten paraffin, which leads to the simultaneous boiling of the acetone droplet and solidifying part of the paraffin in contact with the acetone. The dynamics of impact, the depth and width of the crater, the jet, and the crown formed as a result of the impact have been reported with varying Weber numbers (ranging from 74 to 375), and the temperature of the pool surface of the...

Investigation and Optimization of Ni-P-Zn Electroless Alloy Coatings

, M.Sc. Thesis Sharif University of Technology Kordijazi, Amir (Author) ; karam, SaeedAllah (Supervisor) ; Dolati, Abolghasem (Supervisor)

Abstract

An optimization condition for obtaining Ni-Zn-P electroless alloy coating has been developed. The sulphate bath with sodium hypophosphate as a reducer and sodium citrate and ammonium chloride as complexing agents were used. The effect of variation in the pH level , temperature , time of deposition and reactants concentration on stability of bath, coating composition, microstructure, microhardness and corrosion resistance of coatings was investigated. The composition of coatings was obtained by using the EDAX analysis. To investigate coating morphology, SEM images were taken and to study the corrosion behavior of coatings potentidynamic polarization, Electrochemical Impedance Spectroscopy...

A general model for I/O system theory, Proceedings of AIMC31 [electronic resource]

, Article Iranian Journal of Fuzzy Systems ; 2006, Volume 3, Issue 2, Page 1-19 Daneshgar, A. (Amir) ; Hashem, Amir ; Sharif University of Technology

Phase behavior and rheology of emulsions in an alkaline/cosolvent/crude oil/brine system

, Article Petroleum Science and Technology ; Volume 34, Issue 3 , 2016 , Pages 207-215 ; 10916466 (ISSN) Bahman Abadi, H ; Hemmati, M ; Shariat Panahi, H ; Masihi, M ; Karam Beigi, M. S ; Sharif University of Technology

Taylor and Francis Inc 2016

Abstract

Phase behavior of active crude oil/alkaline was systematically studied in the presence of cosolvents. For this purpose, several factors have been considered: alkaline concentration, oil concentration, and type of brine. The best composition was used to generate emulsion for rheology and displacement tests. Furthermore, precipitation of alkaline was eliminated by its synergy with EDTA. Next, rheology of emulsion was analyzed by which a Power law model was developed that indicates non-Newtonian behavior of emulsion. Moreover, the viscosity of emulsion was reduced by the addition of cosolvent as well as by the increase of alkaline concentration. Finally, the best formulation (containing...

A uniquely 3-list colorable, planar and k4-free graph

, Article Journal of Combinatorial Mathematics and Combinatorial Computing ; Volume 72 , 2010 , Pages 115-120 ; 08353026 (ISSN) Asadi, S. A ; Sharif University of Technology

2010

Abstract

Let G be a graph with v vertices. If there exists a collection of list of colors S1, S1,..., Sv on its vertices, each of size k, such that there exists a unique proper coloring for G from this list of colors, then G is called a uniquely k-list colorable graph. In this note we present a uniquely 3-list colorable, planar and K4-free Graph. It is a counterexample for a conjecture by Ch. Eslahchi, M. Ghebleh and H. Hajiabolhassan [3]

Evaluating Reliability of SSDs Against Power Outage

, M.Sc. Thesis Sharif University of Technology (Author) ; Asadi, Hossein (Supervisor)

Abstract

Solid-State Drives (SSDs) provide high performance, low power consumption, and hence are widely used in the I/O cache of enterprise storage systems and high performance servers. Although employing high performance SSDs in the I/O cache of storage systems significantly improves system performance, it comes with significant reliability threats for write operations upon power failures. In order to provide high level of reliability, storage architectures employ SSDs in I/O cache with RAID-1 configuration, however, such configuration only partially mitigates the reliability issues of the SSDs. In this thesis, we analyze the reliability of SSD-based I/O caches against power outage and high...

Power Management of a Combined Humidifier-Dehumidifier and Reverse Osmosis (RO-HDH) Desalination Cycle Using Renewable Energy

, M.Sc. Thesis Sharif University of Technology Asgharzadeh Karam Shahlu, Alireza (Author) ; Saeedi, Mohammad Hassan (Supervisor) ; Aryanpour, Masoud (Co-Supervisor)

Abstract

Desalination systems play a crucial role in providing drinking water in arid and semi-arid regions. Among them, combined dehumidifier-humidity absorber and reverse osmosis desalination systems are of particular importance due to their high efficiency and adaptability to renewable energy sources. The combined dehumidifier-humidity absorber and reverse osmosis desalination system, as an innovative technology, simultaneously uses the processes of moisture absorption and release to extract water from the air, along with reverse osmosis for desalting seawater. These systems can operate sustainably and efficiently by utilizing renewable energy sources such as solar or wind energy. Additionally,...

Multi directional forging of 2024 Al alloy after different heat treatments: Microstructural and mechanical behavior

, Article Transactions of the Indian Institute of Metals ; 2016 , Pages 1-13 ; 09722815 (ISSN) Asadi, S ; Kazeminezhad, M ; Sharif University of Technology

Springer India 2016

Abstract

Improvement of mechanical properties and microstructure of 2024 aluminum alloy by performing a severe plastic deformation method, called multidirectional forging (MDF), and heat treatment was the aim of this research. In this work, the effects of different heat treatments such as annealing, solid solution, peak ageing and over ageing before MDF on mechanical properties and microstructure of the alloy were studied. Microstructure evolution during severe plastic deformation was considerably affected by the precipitates and non-shearable particles. On the other hand, the severe plastic deformation had different effects on precipitates in the microstructure. Fragmentation, scattering and...

Utilizing mixed methods research in analyzing Iranian researchers' informarion search behaviour in the web and presenting the current pattern

, Article Iranian Journal of Information Processing Management ; Volume 31, Issue 1 , 2015 , Pages 27-57 ; 22518223 (ISSN) Asadi, M ; Hariri, N ; Sharif University of Technology

Iranian Research Institute for Scientific Information and Documentation 2015

Abstract

Using mixed method research the current study has analyzed Iranian researchers' information searching behavior on the Web. Based on extracted concepts, the model of their information searching behavior was revealed. Forty-four participants, including academic staff from universities and research centers were recruited for this study selected by purposive sampling. Data were gathered from questionnaires including ten questions and semi-structured interview. Each participant's memos were analyzed using grounded theory methods adapted from Strauss & Corbin (1998). Results showed that the main objectives of subjects were doing a research, writing a paper, studying, doing assignments, downloading...

The relationship between the research activity of Iranian medical universities and their web impact factor

, Article Electronic Library ; Volume 27, Issue 6 , 2009 , Pages 1026-1043 ; 02640473 (ISSN) Asadi, M ; Shekofteh, M ; Sharif University of Technology

2009

Abstract

Purpose - The aim of this paper is to look at the relationship between research in Iranian medical universities, together with their Web Impact Factor (WIF). Design/methodology/approach - The Altavista search engine was chosen because of its advanced search facilities for counting links and having a wider scope of academic web sites than other search engines. It was searched for determining the number of pages, in-links and self-links of 42 web sites of Iranian medical universities. The Web Impact Factor (WIF) was calculated by two formulas and the relationship between the two grades of universities (WIF and ISI) was calculated by using the Spearman's correlation coefficient. Findings -...

Multi directional forging of 2024 Al alloy after different heat treatments: microstructural and mechanical behavior

, Article Transactions of the Indian Institute of Metals ; Volume 70, Issue 7 , 2017 , Pages 1707-1719 ; 09722815 (ISSN) Asadi, S ; Kazeminezhad, M ; Sharif University of Technology

2017

Abstract

Improvement of mechanical properties and microstructure of 2024 aluminum alloy by performing a severe plastic deformation method, called multidirectional forging (MDF), and heat treatment was the aim of this research. In this work, the effects of different heat treatments such as annealing, solid solution, peak ageing and over ageing before MDF on mechanical properties and microstructure of the alloy were studied. Microstructure evolution during severe plastic deformation was considerably affected by the precipitates and non-shearable particles. On the other hand, the severe plastic deformation had different effects on precipitates in the microstructure. Fragmentation, scattering and...

Marker-less versus marker-based driven musculoskeletal models of the spine during static load-handling activities

, Article Journal of Biomechanics ; Volume 112 , 2020 Asadi, F ; Arjmand, N ; Sharif University of Technology

Elsevier Ltd 2020

Abstract

Evaluation of workers’ body posture in workstations is a prerequisite to estimate spinal loads and assess risk of injury for the subsequent design of preventive interventions. The Microsoft Kinect™ sensor is, in this regard, advantageous over the traditional skin-marker-based optical motion capture systems for being marker-less, portable, cost-effective, and easy-to-use in real workplaces. While several studies have demonstrated the validity/reliability of the Kinect for posture measurements especially during gait trials, its capability to adequately drive a detailed spine musculoskeletal model for injury risk assessments remains to be investigated. Lumbosacral (L5-S1) load predictions of a...