Sharif Digital Repository

Spine column is the most important musculoskeletal structures. One of the serious health problems in societies, especially among aged population is osteoporosis. Loss of bone density in bone structures is called osteoporosis which increases the risk of fracture due to a decrease of bone stiffness and bone strength. Spine is the most common sites for osteoporosis-related fractures. Current assessment of osteoporosis status is based on bone densitometry tools like QCT (Quantitative Computed Tomography) or DEXA (Dual Energy X-ray absorptiometry). With these methods it is only possible to estimate density without any consideration the morphology of trabecular making parts like rods and plates.... 

Scientists want to know how they can control fluids motion. They use electric fields for controlling the fluids in different dimensions. In small size, application of electric fields is very important because of biological applications. We use electric current and field for rotating freely suspended films. Here, we study soap, polar and non-polar liquids, MBBA liquid crystal and ferrofluids films. We show that the surface charge plays the crucial role in rotating the films.We study the correlation between rotation of a film and different physical quantities.Our experiments confirm that dipole moments of fluid molecules do not show a clear effect on the rotation. Increasing the dipole moment... 

The fascinating size-dependent properties of noble metal nanop articles have created a great promise for their use in a different applications specially chemical sensing. Gold nanorods (GNRs), specifically, have received a great deal of attention due to their unusual optical properties. The nanoscale confinement of electrons on the surface of gold nanorods grants them aspect ratio-dependent properties not seen in larger particles. Due to the intriguing properties of GNRs, significant work has gone into the application of nanorods for sensing and detection of various an alytes in biological and other systems. The major modalities which have been developed for... 

There is a growing interest in developing high-performance sensors monitoring organophosphate pesticides, primarily due to their broad usage and harmful effects on mammals. In the first part of this research, by introducing conditional sensor elements (CSE), a colorimetric sensor array has been proposed for the detection and discrimination of several organophosphate pesticides (OPs). citrate-capped 13 nm gold nanoparticles (AuNPs) at nine different pH/ionic strengths were employed as simple plasmonic sensing elements in the development of a colorimetric sensor array for the detection and discrimination of five organophosphate pesticides, including azinphos-methyl (AM), chlorpyrifos (CP),... 

Introduction: Today, backward and forward scattering tomography of dispersive medium is of great interest because of its broad applications, especially in medical imaging, of breast cancer, Distinguishing different tissues of the body from each other is one of the necessities. Increasing the quality of the image by just a few percents has great improvement on the tomography resolution.
Materials and Methods: In this project we made phantom of the tissue and tumor from Intralipid 10% plus Agarose and Indian ink for soft tissue and plastic fibers as tumor having birefringence factor of 0.001.After putting the plastic tumor in soft tissue phantom, the polarized white light and a digital... 

Investigation of electrohydrodynamic behavior of fluids under electric fields is a challenging and impressive matter in condensed matter physics. In this thesis, inspired from previous works on liquid film motor, a new phenomenon has been observed and its properties has been investigated.Here by making a new device named “Liquid Film Electric Generator” we produced potential difference on the rotating suspended liquid film under electric field. The power conducted by electrodes has been generated on the surfaces of the film. By this method, under electric field of 1000 V/cm, micro-watt electric power can be achieved on a liquid film of diameter of about 1 cm.We explained this phenomenon on... 

Reduced mechanisms are widely used in the numerical simulation of turbulent combustion, motivated by the need to reduce computational costs. Tabulation is widely used in turbulent and reacting flow simulations. Still, the need for a huge memory, the high cost of searching and interpolating among the data, and the development of artificial neural networks have created a situation for combining these two sciences. In this research, to model the chemistry of a methane premixed flame, we produced several training databases using the flamelet generated manifold, the best of which is the database with five degrees of freedom. We used these data to train individual neural networks for the... 

This study investigates the factors influencing the acceptance of digital health technologies in Iran by employing a modified version of the Unified Theory of Acceptance and Use of Technology (UTAUT2). The significance of understanding user acceptance is underscored within the context of digital health ecosystems, which consist of various stakeholders, including healthcare providers, technology companies, and patients. These platforms serve as vital interfaces that connect these stakeholders, facilitating access to healthcare services and enhancing health outcomes. The literature review reveals that while traditional models like TAM and UTAUT2 have been widely applied, they often overlook... 

The Architecture, Engineering, and Construction (AEC) industry worldwide has increasingly turned its attention to the application of Building Information Modeling (BIM) due to its numerous advantages. Educational institutions have been urged to integrate this technology into their curricula so that new graduates can acquire the necessary competencies and expertise to keep pace with industry developments and take full advantage of BIM. Building Information Modeling involves automated processes that significantly reduce discrepancies between planned and constructed models, save time and cost, prevent errors, and mitigate risks. The process of introducing this technology into universities has... 

Analysis of performance of fetal heart is very important for monitoring its health. In recent years a lot of research is performed on recording electronic signals from mother abdomen which consist of combination of maternal ECG and fetal ECG. Purpose of this thesis is investigating methods. For evaluation of different methods simulated ECG dataset and Dalsy dataset as real data were used. In this thesis Wavelet and EMD denoising as single channel methods and ICA, PiCA and deflation as multichannel methods are used. At last novel combinations of these methods is proposed which outperforms existing methods  

The purpose of this study is to provide a framework to demonstrate the organizational capabilities of chemical knowledge-based firms and analyze the relationship between these capabilities and exports. For this purpose, by combining 18 different output-based indicators, a model that includes six technological, manufacturing, research and development, marketing, organization and finance capabilities, was designed. Finally, in addition to analyzing the relationship between exports and the level of capabilities of knowledge-based firms, a comparison between the two groups of export and non-export firms and the analysis of these firms' current export situation was made in the period 2015-2018.... 

The purpose of this study is to present a suitable model for calculating the costs imposed on society due to deaths and injuries due to infrastructure failure due to earthquakes, which is used in the analysis of community resilience. Much research has been done to date to calculate the economic costs of infrastructure failure. However, no suitable analytical framework has been provided to quantify the costs of deaths and injuries to people due to earthquake failure. Previous research has provided methods such as the value of statistical life to quantify the social costs caused by accidents and environmental pollution. However, the literature review results in the field of seismic resilience... 

This study investigates the possibility of knowledge transfer from military industries, with a focus on the missile industry, to other sectors in the country, particularly the automotive industry, from the perspective of technological capabilities. The objective of this research is to conduct a comparative analysis of the technological capabilities of these two industries and to evaluate the potential and challenges associated with the process of knowledge and technology transfer. The research methodology involves qualitative analysis through interviews with experts and the review of relevant documents and records. The conceptual framework has been developed based on existing models of... 

High-quality online services demand reliable and fast packet delivery at the network layer. However, clear evidence documents the existence of compromised routers in the ISP and enterprise networks, threatening network availability and reliability. A compromised router can stealthily drop, modify, inject, or delay packets in the forwarding path to launch Denial-of-Service, surveillance, man-in-the-middle attacks, etc. So researches tried to create intrusion detection methods to identify adversarial routers and switches. To this end, data-plane fault localization (FL) aims to identify faulty links and is an effective means of achieving high network availability. FL protocols use... 

Confining nematic liquid crystal between two curved boundary conditions while the nematic molecules have a degenerate planar anchoring leads to complex and beautiful textures of molecular disparagement(defect) in the bulk and on the surfaces. Such the liquid crystal shells are made with double-emulsion techniques in microfluidic devices have provided applications for micro-scale colloidal linkers.In this work, we have numerically minimized the elastic energy in one-constant approximation in present of Fournier’s degenerate surface potential with finite element method. The nematic shell is confined between two spherical surfaces that we have studied the final energies and their related... 

In this project, polarization properties, intensity of reflected light, by one layer tissue that has specified optical properties has been investigated by means of Monte Carlo simulation. Fresnel's coefficients were considered in this simulation too. The incident beam was assumed very thin with specified wave length and linear polarization parallel to plane of incidence.This beam was radiated from origin to the tissue vertically. The layer consists of homogenous particles with defined radius. Concentration of particles was constant. 10000 photons with specified weight were launched to tissue in each simulation. The results of reflected light from tissue showed that variation of the size and... 

The tissue characteristics are important for all kinds of medical laser applications in order to understand the interaction mechanisms between light and tissue. Knowledge about light transport in tissue is essential for cancer treatment and cancer diagnostic techniques. By having the diffused reflectance of a tissue we can determine its optical characteristics. In this thesis we have solved the inverse process. That is, we compute the diffused reflectance of a turbid media with pre-determined optical parameters. This problem can be solved using two methods: Monte Carlo simulation and diffusion method. Since Monte Carlo simulation is computationally very expensive, it is not used in medical...