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Modified carrageenan. 5. Preparation, swelling behavior, salt- and pH-sensitivity of partially hydrolyzed crosslinked carrageenan-graft-polymethacrylamide superabsorbent hydrogel [electronic resource]
, Article Polymers for Advanced Technologies ; Volume 15, Issue 11, pages 645–653, November 2004 ; Sadeghi, M ; Hosseinzadeh, H
Abstract
The polysaccharide, kappa-carrageenan (κC) was chemically modified to achieve a novel superabsorbent hydrogel via graft copolymerization of methacrylamide (MAM) onto the substrate followed by alkaline hydrolysis. Ammonium persulfate (APS) and N,N′-methylene bisacrylamide (MBA) were used as a free-radical initiator and a crosslinker, respectively. The saponification reaction was carried out using sodium hydroxide aqueous solution. Either κC-g-PMAM or hydrolyzed κC-g-PMAM (PMAM: polymethacrylamide) was characterized by FT-IR spectroscopy. The effect of grafting variables (i.e. concentration of MBA, MAM, and APS) and alkaline hydrolysis conditions (i.e. NaOH concentration, hydrolysis time and...
Modified carrageenan. 4. Synthesis and swelling behavior of crosslinked kappa C-g-AMPS superabsorbent hydrogel with antisalt and pH-responsiveness properties [electronic resource]
, Article Journal of Applied Polymer Science ; Vol.98, No.1, 255-263, 2005 ; Hosseinzadeh, H ; Mazidi, R
Abstract
To synthesize a novel biopolymer-based superabsorbent hydrogel, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) was grafted onto kappa-carrageenan (KC) backbones. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator, N,N,N',N'-tetramethyl ethylenediamine (TMEDA) as an accelerator, and N,N'-methylene bisacrylamide (MBA) as a crosslinker. A proposed mechanism for KC-g-AMPS formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The affecting variables on swelling capacity, i.e., the initiator, the crosslinker, and the monomer concentration, as well as reaction temperature,...
Partially hydrolyzed crosslinked alginate-graft-polymethacrylamide as a novel biopolymer-based superabsorbent hydrogel having pH-responsive Properties [electronic resource]
, Article Macromolecular Research ; January 2005, Volume 13, Issue 1, pp 45-53 ; Aminfazl, M. S ; Hosseinzadeh, H
Abstract
In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacrylamide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator andN,N′-methylenebisacrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g-PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-polymethacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the...
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...
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,...
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...
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...
Heat Transfer Modeling of Ultrasounic Hyperthermia
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Ultrasound hyperthermia is a commonly used noninvasive approach to destroy cancer tumors. High Intensity Focused Ultrasound (HIFU) is a technique based on hyperthermia. It creates short and local elevations of temperature at a focus site within the tissue of interest. The main goal of HIFU is to maintain the temperature between 50 and 100 °C for a few seconds (typically less than 10 s), in order to cause tissue necrosis. In order to predict the effects of hyperthermia, accurate and effective modeling is needed. This study considers a 3D simulation of the hyperthermia based on HIFU method in the liver tissue. Temperature distribution and lesion volume changes, with a temperature of above...
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...
Hand Posture Recognition through Stereo Vision System
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
The mankind has always utilized vision as the most essential tool in evaluating his environment. Currently, one of the most important research areas in computer vision is to characterize a three dimensional object through its features in a natural scene. This task may be conducted through a stereo vision system. The objective of this study is to introduce a quantitative measure in order to evaluate the operation of an automatic recognition system for selected hand postures. A key application of our proposed system is to train a prosthetic hand through surface electromyogram (sEMG) signals. At the onset of this process, the patient conducts a certain posture through application of sEMG...
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...
Automatic Hand and Wrist Motion Tracking and Assessment Using Stereo Vision and Video Processing
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Gesture and motion evaluation are needed for a variety of applications. The use of human hand motions as a natural interface tool has motivated researchers to conduct research in the modeling, analysis and evaluation of various hand movements. In particular, human-computer intelligent interaction has been a focus of research in vision-based gesture recognition. In this work, we introduce a 3-D hand model evaluation method that offers flexible and elaborate representation of hand motion. We used landmarked points on tips and joints of the fingers and calculated the 3-D coordinates of these points through a stereo vision system followed by an HMM (Hidden Markov Model) to recognize hand...
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,...
Pathology Analysis and Multi-Class Discrimination for Laryngeal Disorders
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Ability to speak lucidly plays a key role in social relations. Consequently the role of larynx is quite important and timely diagnosis of laryngeal diseases has proved to be crucial. Since conventional diagnostic methods of the larynx are usually expensive or bothersome, the aim of this project is to analyze and classify diseases of the larynx with the aid of signal processing which tend to be faster and easier to implement and quite economical. This study utilizes the vowel sound /a/ and a well referenced database, namely MEEI (Massachusetts Eye and Ear Infirmary) which includes 53 normal and 213 abnormal voices in 7 classified diseases. In this work, using existing signal modeling and...
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...
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...
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...
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...
Control of Exoskeletal System in Coordination with Upper Extremity System
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
With technological advances in fabrication and control of prosthesis and assistive devices the importance of such systems has increased drastically. On the other hand the appropriate coupling of these devices, especially the exoskeletal systems with the upper or lower extremities is of immense importance as it is an integral part of the control system. In particular, the control strategy and its ability to adapt the exoskeletal system with the existing and physiological functionality of the user, is an integral part of the system requirement. In the controller implementation, a number of methods are proposed including using the excitation signal, similar to the existing neuromuscular system....