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Effect of Mullite Content on HAp-Mullite Composite for Hard Tissue Application
,
M.Sc. Thesis
Sharif University of Technology
;
Faghihi Sani, Mohammad Ali
(Supervisor)
;
Solati Hashjin, Mehran
(Supervisor)
Abstract
In this study effect of various mullite contents, as reinforcement phase, on phase combination, fracture surface and mechanical propertiese of hydroxyapatite- mullite composite has been investigated.
The used hydroxyapatite powder was synthesized through acid- base route and further calcination. XRD results demonstrated partially decomposition of HA in to β- TCP and CaO during the calcination. SEM image of the prepared HA powder showed that they were spherical and agglomarated.
The mixed HA with various amounts of the ball- milled mullite (10- 40 wt%)were pressed and sintered at 1350°C for 2h. Dominant phase in all composite samplese after sintering was Ca9Al(PO4)7.
Phase...
The used hydroxyapatite powder was synthesized through acid- base route and further calcination. XRD results demonstrated partially decomposition of HA in to β- TCP and CaO during the calcination. SEM image of the prepared HA powder showed that they were spherical and agglomarated.
The mixed HA with various amounts of the ball- milled mullite (10- 40 wt%)were pressed and sintered at 1350°C for 2h. Dominant phase in all composite samplese after sintering was Ca9Al(PO4)7.
Phase...
Synthesis and characterization of co-doped TiO2 thin films on glass-ceramic
, Article Materials Science in Semiconductor Processing ; Vol. 26, Issue 1 , October , 2014 , pp. 41-48 ; ISSN: 13698001 ; Nemati, A ; Solati-Hashjin, M ; Sharif University of Technology
2014
Abstract
In this research, an attempt was made to improve TiO2 photo-catalyst properties, thus pure, N-Ce co-doped TiO2 thin films were prepared on glass-ceramic substrate using a sol-gel dip-coating technique. The samples were calcinated in air at 475 °C, 550°C, and 650°C for 2 h. The result of simultaneous thermal analysis (STA) and X-ray diffraction (XRD) showed that the presence of Ce in TiO2 could inhibit the phase transformation from anatase to rutile and enhance the thermal stability, and anatase was the dominant phase in N-Ce co-doped TiO2 samples. Also based on the results, the doping results in decreasing the size of TiO 2 crystallite. The results of ultra violet-visible light diffuse...
Enhancing glass ionomer cement features by using the HA/YSZ nanocomposite: A feed forward neural network modelling
, Article Journal of the Mechanical Behavior of Biomedical Materials ; Vol. 29 , January , 2014 , pp. 317-327 ; ISSN: 17516161 ; Salehi, S ; Nemati, A ; Tavakoli, R ; Solati Hashjin, M ; Sharif University of Technology
2014
Abstract
Despite brilliant properties of glass ionomer cement (GIC), its weak mechanical property poses an obstacle for its use in medical applications. The present research aims to formulate hydroxyapatite/yttria-stabilized zirconia (HA/YSZ) in the composition of GIC to enhance mechanical properties and to improve fluoride release of GIC. HA/YSZ was synthesized via a sol-gel method and characterized by applying X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photo-emission spectroscopy (XPS) and simultaneous thermal analysis (STA) along with transmission electron microscopy (TEM) methods. The synthesized nanocomposite was mixed with GIC at a fixed composition of 5....
Data-driven Technologies in Dynamic Regulation; Case of Tehran Municipality for Effective Car Taxation
, M.Sc. Thesis Sharif University of Technology ; Mirnezami, Reza (Supervisor)
Abstract
The common experience of the citizens in metropolitan areas is facing a large volume of private car traffic. Accordingly, the discussion of managing the demand for intra-city travel by private cars has become widespread. Factors influencing the demand and decision of citizens to travel by car, like the demand for any other product, are divided into several groups, including commodity price, related goods price, income, and advertisement. One of the most critical and generalized variables that affect the final price of goods and subsequently affects demand is the costs incurred in the decision and demand for goods. The demand for trips with private cars is associated with the following two...
Optimal integration of small scale hybrid solar wind RO-MSF desalination system
, Article Renewable Energy Focus ; Volume 27 , 2018 , Pages 120-134 ; 17550084 (ISSN) ; Tavakoli Hashjin, T ; Ghobadian, B ; Roshandel, R ; Sharif University of Technology
2018
Abstract
Solar and wind are two main resources of renewable energies that can supply the energy requirement in the most of world's regions. Iran has desirable condition in terms of solar and wind energy and also is faced with shortage of fresh water resources. Hybrid solar wind RO-MSF desalination system that works with two clean and renewable energy resources of solar and wind, could be a sustainable energy resource for water desalination. Hence, in this paper for evaluating the performance of salty water desalination by hybrid RO-MSF desalination plants, a hybrid system is designed and optimized. Different models of solar wind RO-MSF was considered and analyzed technically and economically. Finally...
Film Cooling Computational Simulation of the Trailing Edge a Gas Turbine Blade, Using Quasi-Radial Jets–Impact of Jet Height
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Javadi, Khodayar (Supervisor)
Abstract
The limitations of metals in tolerating thermal stresses is one of the main obstacles in increasing temperature of combustion products. In addition, strong desires to use higher temperatures than are allowed for metals, have led to use of different cooling methods for protecting surfaces adjacent to hot gases. Previous valid studies show that more than 25% of research in the field of gas turbine is related to their blades cooling. On the other hand, one of the very important methods of cooling such surfaces is film cooling. The results of this and previous researches conducted by the team of this thesis’ supervisors can for instance help designers to predict more suitable positions for...
Protection of titanium metal by nanohydroxyapatite coating with zirconia and alumina second phases
, Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 48, Issue 6 , 2012 , Pages 688-691 ; 20702051 (ISSN) ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif Universty of Technology
2012
Abstract
In this study hydroxyapatite (HA)/zirconia/alumina composite coatings on titanium metal was carried out using Sol-Gel dip coating and calcination process. Hydroxyapatite-Alumina-Zirconia sol, coated samples in three processes by changing final sol stirring time, aging time, calcination temperature of synthesized powder and prepared coating and rate of coating. Some parts of prepared sol were also synthesized and became powder in all three processes. Scanning electron microscopy was used to estimate the particle size of the surface and for morphological analysis. The functional group and crystallization characteristics of the powders were analyzed using (FTIR) and X-Ray diffraction (XRD)....
Surface modification for titanium implants by hydroxyapatite nanocomposite
, Article Caspian Journal of Internal Medicine ; Volume 3, Issue 3 , 2012 , Pages 460-465 ; 20086164 (ISSN) ; Solati Hashjin, M ; Nik, S. N ; Nemati, A ; Sharif University of Technology
2012
Abstract
Background: Titanium (Ti) implants are commonly coated with hydroxyapatite (HA). However, HA has some disadvantages such as brittleness, low tensile strength and fracture toughness. It is desirable to combine the excellent mechanical properties of ZrO 2 and the chemical inertness of Al 2O 3 with respect to the purpose of this project which was coating Ti implants with HA-ZrO 2-Al 2O 3 to modify the surface of these implants by adding ZrO 2 and Al 2O 3 to HA. The purpose of this study was to evaluate the efficacy of hydroxyapatite coating nonocomposite. Methods: From September 2009 to January2011, functionally graded HA-Al 2O 3-ZrO 2 and HA coatings were applied on Ti samples. HA-Al 2O 3-ZrO...
Modeling Propagation of Cardiac Action Potential at Cellular Level
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Heartbeat is the result of contractions of over 10 billion cardiac cells. These cells’ cytoplasms are connected to each other by gap junctions which are arrays of intercellular protein channels. Thus action potential can propagate from one cell to another and cause its contraction. In core-conductor model, one-dimensional microscopic representation of cardiac tissue, cells are attached to each other to form a ladder network. The parallel elements are connected to each other by series resistors which represent gap junctions. These resistors are nearly always considered as static elements. In this thesis I have investigated the effects of incorporating the dynamicity of gap junction resistors...
Distributed Cardiovascular System Modeling
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Simulation of cardiovascular system functionality during various physiological conditions is essential at different diagnostic and clinical levels. A first step in studying the roots of cardiovascular diseases and abnormal activity is to study a practical yet complete model of the cardiovascular system. In this thesis we introduced a new approach for defining the distributed model of the cardiovascular system. Initially, we chose an appropriate subsystem, namely Arch of Aorta, and proposed a distributed model for it. The elements of the proposed model were nonlinear RLC elements that simulate resistance, blood viscosity and vessel elasticity respectively. To minimize the system complexity,...
Risk Breakdown Structure (RBS) Identification and Designing for projects
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
To actualize and making the outputs of a project effectual, it is necessary to conduct an effective management during a project. This case may not be possible without accurately planning for activities, management and controlling all phases of a project ignoring the risk management of that project. If risks of a project cannot be detected before conducting a project, it is possible to challenge the performance and even effectiveness of the project. In current conditions, the most important problem of managers and executives of construction projects through the country is risk management of projects, not acknowledging with definitions of risk, models of risk management and lack of a model for...
Introducing a suitable Controller for Rowing Activity in Patients with Spinal CordInjuries using FES
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Disconnections in neural paths from the central nervous system to the muscles or vice versa cause different neuropathies, thus paralysis in different limbs may occur. As a result of the lack of muscular activity and the decrease in blood perfusion in paralyzed limbs, problems like osteoporosis, increase in the risk of breaking, decline in muscle size, cardiovascular diseases, renal dysfunction, bedsores, etc may happen. In order to induce movement in paralyzed limbs, thus preventingmentioned problems, rowing exercise through Functional Electrical Stimulation (FES) may be utilized. In FES, electrical Stimulation using current stimulating pulses is applied to contracting and relaxing muscles,...
Performance Management of HSE Management System based on BSC Framework-the Case Study of Mapna Corporation
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
A Balanced Scorecard (BSC) model is proposed to evaluate performance of Health, Safety and Environment (HSE) management systems. This model includes key performance indicators at three integrated levels. It has been tested and verified in a project-based organization in Iran, active in the area of power and energy. Results show that the company has done well in implementing HSE management processes, but no so well in growth and learning. This model may be used as a basis for comparing different companies and various proposed programs in the field of HSE management systems. The model includes indicators and sub-indicators in each category particularly related to stakeholders, processes, and...
Functional Modeling of Normal and CHF Heart and Control of Total Artificial Heart- An Optimizing Approach
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
World-wide, Congestive Heart Failure (CHF) takes hundreds of thousands of lives each year. This chronic heart disease causes poor performance of the heart and insufficient blood pumping to the organs. A significant percentage of patients with CHF require heart transplants for their survival. The high cost of heart transplant, shortage of donor hearts and possibility of its rejection by recipients are serious problems of this type of treatment. Therefore a large number of heart patients are potential beneficiaries of artificial blood pumps such as Ventricular Assist Device (VAD) and Total Artificial Heart (TAH). Performance of these systems must be compliant and complementary to the existing...
Identifying Affecting HR Factors on Unsuccessful Reengineering Projects
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
In this study, factors which lead in failures in reengineering processes in project based companies have been investigated. The research used qualitative methods, and finally using theme analysis to identify the main factors.Consequently, the main causes of failure of re-engineering projects have been identified and classified in six basic categories including: organizational leadership, planning, human resources management, mental models causing resistance, culture and organizational climate and communication. That each of these themes includes some subset of the agents it represents. In this study, a suitable pattern for organizations which intend to perform reengineering has been...
Applying Tandem CONWIP Policy to Assembly Supply Chain
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
Supply chain management has been developed extensively in second half of last century and the development has been continued up to present century. Nowadays Development and conformity of production and inventory control methods with JIT philosophy in production line level is one of the topics that received much attention from researchers. An increasing interest in the scope of JIT philosophy is on the extension and adaptation of Pull policies such as Kanban and CONWIP for materials and production control. In a real-life environment, companies are subjected to various types of uncertainties such as stochastic processing times and variable demand. This uncertain environment could cause lots...
Joint Segmentation and Motion Estimation of Cardiac Cine MR Image Sequences
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
In this study a variational framework for joint segmentation and motion estimation is provided for inspecting heart in Cine MRI sequences. In the first work, a functional including Mumford-Shah segmentation and optical flow based dense motion estimation is proposed. However, the motion estimation technique is replaced with warping estimation in the second work to reach in more regular and smooth motion field based on tracking of cardiac boundaries. Both of these functionals are then approximated by using the phase-field method to make them suitable for extracting Euler-Lagrange equations. Numerical solution to the optimization problem, when the time and image spaces are discretized by finite...
Dynamics and Control of Needle Movement in Percutaneous Interaction with Prostate Tissue
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
In many modern medical procedures, needle insertion is an inevitable part of the diagnosis or treatment protocols. The accuracy of the needle insertion is adversely affected by a number of factors. A needle, frequently assumed to be flexible, is inserted into a soft tissue and induces complex mechanical interactions that may result in considerable uncertainties. Tissue intrinsic characteristics as well as its deformation and rotation may cause dramatic complexities. This work considers the needle movement inside the tissue from the dynamics and control point of view. The proposed approach can be regarded as an initial step towards automation of needle insertion procedures; it can also be...
Needle Steering in Soft Tissue
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Medical needle interventions are a common technique for accessing tissue structures.In these procedures, needles are used, for example, to extract biopsy samples, brachytherapy, and to insert drugs. In TRUS guided prostate brachytherapy application, Physicians used ulterasound imaging to steer the needle and insert radioactive seeds into cancerous tumors to irradiate surrounding tissue over several months. Prostate rotation, deformation, and unavailability of imaging data during part of the insertion path result in misplaced seeds. To overcome these problems, in this research, we modeled the prostate, its membrane and the surrounding fatty tissue as linearly elastic homogenous material, and...
Considering Lessons Learned and Ascertaining Their Roadmap in Project Management (Case Study: Sepanir Company)
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
Evolutions in the economy, society and politics has raised knowledge as a key element in the development and competitiveness and knowledge management is considered one of the essential elements in this field. By taking temporary nature of the project into account, dynamics and competition in the project-oriented organizations business world makes the preservation and management of knowledge in project-based organizations more important. Lesson learned system is one of the knowledge management tools that can propose strategic solutions which avoid wasting of time and money and make perfect use of knowledge management accomplishments.In this study, by using literature review, interview and...