Sharif Digital Repository

Due to unusual response of structures of buildings with irregularity in their architecture to dynamic excitations, to have a comprehensive knowledge of their behavior during earthquakes is of utmost importance. Building irregularities are in general divided into two major categories, namely Irregularity in Plane and Irregularity in Elevation, and one of the forms of the latter is where there is a split in the levels of the building. In this work, through a series of case studies, the effects of P- phenomenon on the behavior of steel split-level building structures were studied. 5, 10 and 15 story buildings with 5 and 6 bays, and level splitting of 30, 60, 90, 120 and 150 cm were studied. All... 

Since, seepage- related problems account for more than forty percents of earth dams’ failure, seepage analysis is one of the most important stages in designing of embankment dams. The most usual method of making a seepage analysis is doing a two dimensional one in the maximum cross- section and generalizing its results to the third dimension. As a natural consequence of this kind of seepage analysis, the effect of valley shape and material properties’ changes along the third dimension are ignored and so, in narrow valleys where the cross-section changes along longitude profile or in the specific cases of nonhomogeneity, using this kind of analysis can make false results. Besides, because of... 

This research study presents an experimental investigation on forced convection heat transfer of an aqueous ferrofluid flow passing through a circular copper tube in the presence of a magnetic field. Both constant magnetic field and alternating magnetic field was examined. Moreover magnetic field layout and strength and modes of alternating magnetic field was investigated. The flow passes through the tube under a uniform heat flux and laminar flow conditions. The primary objective was to intensify the particle migration and disturbance of the boundary layer by utilizing the magnetic field effect on the nanoparticles for more heat transfer enhancement. Complicated convection regimes caused by... 

The inflation paradigm solves the so-called flatness problem of the standard cosmo- logical model and explains the homogeneity of the Universe by adding a period of exponential expansion at early times to the standard scenario. Moreover, it provides a mechanism for generating density perturbations, serving as the seed of large-scale structures. One of the successes of inflation is predicting primordial scale-invariant perturbations that agree with the observations of cosmic background radiation. Nev- ertheless, there will be a cold, matter-free universe after exponential expansion, so one needs a process that leads to a hot cosmos containing standard particles after the end of inflation, the... 

Plasma Electrolytic Oxidation (PEO) method was used for the preparation of ceramic coatings on Aluminum 5052 substrate in a silicate-based electrolyte containing different concentrations of ZrO2 nanoparticles. Before the addition of nanoparticles into the electrolyte, determining process parameters including current density, coating time, and frequency were examined carefully. After studying corrosion behavior, thickness, and coating morphology in different circumstances, the frequency of 50Hz, the current density of 150mA/cm2, and the coating time of 20 minutes were chosen as the optimum parameters. After that and with the usage of those parameters, ZrO2 nanoparticles were added to the... 

Cardiovascular signals are used to check the performance of the cardiovascular system. Researchers have always been interested in processing cardiovascular signals to achieve goals like diagnosing arrhythmias and heart diseases. The presence of causal or non-causal relationships between these signals can be used to evaluate the cardiovascular system's performance. Cardiovascular signals, such as ECG signal, RR series and systolic arterial blood pressure, chest volume or respiratory force, and blood oxygen concentration signals are used to estimate cardiovascular connectivities. There are different approaches to assessing causal relationships; among these approaches, methods based on Granger... 

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... 

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,... 

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... 

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,... 

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... 

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... 

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... 

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... 

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... 

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... 

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... 

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... 

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...