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    Attenuation and Scatter Correction in Whole Body Positron Emission Tomography Images using Neural Networks

    , M.Sc. Thesis Sharif University of Technology Adeli, Zahra (Author) ; Hosseini, Abolfazl (Supervisor) ; Sheikhzadeh, Peyman (Co-Supervisor)
    Abstract
    Objective: Accurate quantification in PET imaging is essential for proper evaluation and requires attenuation and scatter correction. Typically, this correction is performed using CT; however, the propagation of CT image errors to PET, the additional radiation dose in PET/CT, especially in pediatric cases and repeated scans, as well as challenges associated with standalone PET and PET/MRI, highlight the need for alternative approaches. This study investigates the capability of deep learning in jointly correcting attenuation and scatter for PET images with different radiotracers. Methods: Various neural network models, including ResNet, U-Net, and swin UNETR, were trained for direct... 

    Using Compartment Modeling for the Non-Invasive Diagnosis of Malignant Tumors, as Well as Determining the Active Volume and Total Glycolysis of Malignant Tumors in PET/CT Imaging with FDG Radiation

    , Ph.D. Dissertation Sharif University of Technology Reshtebar Sofla, Niloufar (Author) ; Hosseini, Abolfazl (Supervisor) ; Sheikhzadeh, Peyman (Co-Supervisor)
    Abstract
    In static PET/CT imaging, the Standardized Uptake Value (SUV) parameter is used to evaluate diseases. The use of this parameter provides valuable information to physicians in many cases. However, this parameter has limitations and is not suitable for certain clinical applications, such as assessing treatment response and differentiating between benign and malignant tumors. In contrast, utilizing dynamic imaging systems can yield significant information through the extraction of kinetic features and quantitative analysis based on temporal data. However, the use of dynamic PET imaging in a clinical setting can be challenging due to factors such as prolonged scan times (> 60 minutes),... 

    Scattering Correction in PET Device using Deep Learning

    , M.Sc. Thesis Sharif University of Technology Kamalizadeh, Zeynab (Author) ; Vosoghi, Naser (Supervisor) ; Ghaffarian, Pardis (Co-Supervisor) ; Sheikhzadeh, Peyman (Co-Supervisor)
    Abstract
    Positron Emission Tomography (PET) imaging is a modern sectional imaging technique widely used due to its advantages in visualizing the physiological functions of body tissues. In this method, a radiotracer is injected into the body, concentrating in the area of interest. As the positron-emitting radionuclide decays, positron annihilation occurs, resulting in the emission of two gamma rays in opposite directions. The PET scanner detects these gamma rays; however, scattering may occur during their journey from the patient’s body to the detector, which can introduce errors in tumor localization. To reconstruct images and correct for these scatter effects, various techniques such as iterative... 

    Product bundling: Impacts of product heterogeneity and risk considerations

    , Article International Journal of Production Economics ; Volume 144, Issue 1 , July , 2013 , Pages 209-222 ; 09255273 (ISSN) Sheikhzadeh, M ; Elahi, E ; Sharif University of Technology
    2013
    Abstract
    Bundling has been extensively studied in the literature and its benefits have been manifested through three perspectives of achieving better price discrimination, helping to save costs, and preserving the power for deterring a potential entrant. In this study, we examine two aspects of bundling which have not been studied before. We examine the impact of product heterogeneity on bundling decisions. We also address risk considerations in a bundling problem. Specifically, we consider a retailer who has the option of selling a bundle of two products (pure bundling policy), or selling the products separately (no-bundling policy). The retailer could also face a product selection problem for which... 

    Performance Ehancement of Congestion Control Algorithm Through Traffic Flow Istinction

    , M.Sc. Thesis Sharif University of Technology Peyman, Zakariaei (Author) ; Jahangir, Amir Hossein (Supervisor)
    Abstract
    Congestion is an important issue in the network environment. To keep stable the perfor-mance of the network, congestion control algorithms have been extensively studied. Queue management method employed by the routers is one of the important issues in the congestion control study. Active Queue Management (AQM) has been proposed for early detection of congestion inside the network. AQM mechanisms control the queue length in a router by dropping arriving packets. The Random Early Detection (RED) is the most popular AQM mechanism used in routers on the Intenet to allow network users to simultaneously achieve high throughput and low average delay. The RED algorithm may cause heavy oscillation of... 

    A Realistic Urban Mobility Model for Mobile Ad Hoc Network

    , M.Sc. Thesis Sharif University of Technology Peyman, Sina (Author) ; Manzuri, Mohammad Taghi (Supervisor)
    Abstract
    A Mobile Ad hoc NETwork (MANET) is a set of wireless mobile nodes that form a self configured network. MANETs do not have infrastructure and are not currently deployed on large scales. So research in this area is simulation based. Mobility model in a mobile ad hoc network explains the movement pattern of mobile users and is designed to describe the change of their location, velocity and acceleration over time. One of the challenges in this field is the definition of a common mobility model that provides an accurate and realistic movement description of mobile nodes. In this thesis we want to study the mobility pattern of vehicles on Kish Island and compare it with different kinds of... 

    Optimal Pricing of “Software as a Service” with Risk Considerations

    , M.Sc. Thesis Sharif University of Technology Damangir, Sina (Author) ; Sheikhzadeh, Mahdi (Supervisor)
    Abstract
    The recent advances in communications and processing technologies have paved the way for a new business model in IT industry. In this new model, frequently called “software as a service” or in short SAAS, software is hosted on servers operated by a software vendor instead of customers and all required transactions take place through the network, especially through World Wide Web. There are several differences between traditional business models and SAAS, including pricing and revenue model. Given the fact that vendor’s can monitor the customer usage, new and more complicated price structures such as usage-based pricing is possible, In this new business model. Although this pricing structure... 

    Value-Based Method in Selecting and Purchasing High-Tech Products

    , M.Sc. Thesis Sharif University of Technology Meskin, Mahdi (Author) ; SheikhZadeh, Mahdi (Supervisor)
    Abstract
    People often conduct extensive searches in Internet, when they are involved in purchasing process of digital products. One primary challenge with the method of such searches is this fact that they heavily rely on a wide variety of technical characteristics, while buyers not being well familiar with such attributes. As such, they frequently fail to identify and purchase the right product. To address this issue, value-based approach is proposed by which the decision process is expected to be facilitated and become more efficient since it is based upon direct comparison of values gained by each product. In this thesis, as a case study for digital products, value attributes of mobile products... 

    Developing an Integrated Framework for Outsourcing in the Auto Industry

    , M.Sc. Thesis Sharif University of Technology Motamedi, Sadegh (Author) ; Sheikhzadeh, Mehdi (Supervisor)
    Abstract
    Outsourcing is currently a challenging issue in the auto industry. On one hand, outsourcing has be-come a competitive imperative for automakers due to its significant benefits. On the other hand, it involves many aspects of risks that could potentially hurt core competencies of a firm. As such, in the auto industry, it is highly critical to make optimal outsourcing decisions for which an integrated framework offering a holistic view seems quite necessary. In this thesis, based on four fundamental research questions of “Who?”, “What?”, “Whom?” and “How?”, an integrated framework for outsourcing in the auto industry is developed in order to identify effective outsourcing factors and associated... 

    A Framework for Price Negotiations in Presence of Alternative Options

    , M.Sc. Thesis Sharif University of Technology Purmehdi, Mostafa (Author) ; Sheikhzadeh, Mehdi (Supervisor)
    Abstract
    The present research investigates the conjunction of two areas of pricing and negotiation techniques to find a relationship between price and other key factors such as quality, quantity, time, etc. and observe the overall effect of these factors on how to design and implement negotiations over price in B2B environment. The research presents a model to describe the process of negotiation and applies quantitative methods to rank negotiable scenarios. This set of scenarios, then is sorted in a triangular model of negotiation strategy and is used as a roadmap for negotiation. Furthermore, researcher evaluates effective tactics and their implementation to drive negotiation sessions based on... 

    Capability and recruitment patterns of trunk during isometric uniaxial and biaxial upright exertion

    , Article Clinical Biomechanics ; Volume 23, Issue 5 , 2008 , Pages 527-535 ; 02680033 (ISSN) Sheikhzadeh, A ; Parnianpour, M ; Nordin, M ; Sharif University of Technology
    2008
    Abstract
    Background: Work-related risk factors of low back disorders have been identified to be external moments, awkward postures, and asymmetrical dynamic lifting amongst others. The distinct role of asymmetry of load versus posture is hard to discern from the literature. Hence, the aim of this study is to measure isometric trunk exertions at upright standing posture at different exertion level and degree of asymmetry to further delineate the effects of exertion level and asymmetry on neuromuscular capability response. Methods: Fifteen healthy volunteers randomly performed trunk exertions at three levels (30%, 60%, and 100% of maximum voluntary exertion and five different angles (0°, 45°, 90°,... 

    Syllable duration prediction for Farsi text-to-speech systems

    , Article Scientia Iranica ; Volume 11, Issue 3 , 2004 , Pages 225-233 ; 10263098 (ISSN) Nazari, B ; Nayebi, K ; Sheikhzadeh, H ; Sharif University of Technology
    Sharif University of Technology  2004
    Abstract
    In this paper, two different statistical approaches are used for duration prediction of the Farsi language. These two statistical models are Neural Networks (NN) and Classification And Regression Trees (CART). The first step in this work was to create a database and develop a flexible feature extraction and selection module. In the next step, the output of the feature selection module was used to train both models. The results of the trained models are further studied to determine the most important parameters affecting the syllable duration in Farsi, The model accuracy is evaluated by using separate training and test data. In the third step of this work, ah automatic rule generator module... 

    A Study on the Effect of Multi-domain Mental Conceptual Network on Metaphorical Creativity

    , M.Sc. Thesis Sharif University of Technology Sheikhzadeh, Maral (Author) ; Khosravizadeh, Parvaneh (Supervisor)
    Abstract
    This thesis was an attempt to find the effect of having multi-domain conceptual network on metaphorical creativity. The purpose of this research was to answer the following question: By extending and expanding the mental conceptual network, could one increase their potential creativity; In other words, is expansion of the mental conceptual network one of the parameters of creativity or not.To answer this question, a questionnaire and a test were developped. Through the questionnaire, we divided the sample group into the test and control groups. And the test indicated how creative each individual is.There were three different ways the sample group was divided. The criteria for dividing the... 

    Toward an Integrated Framework for Supply Chain Performance Measurement

    , M.Sc. Thesis Sharif University of Technology Eslamifar, Gholamreza (Author) ; Sheikhzadeh, Mehdi (Supervisor)
    Abstract
    Proficient management of Supply Chain (SC) necessitates an efficient evaluation of SC performance. This highlights cardinal role of performance measurement in management of SC. However, SC has multidisciplinary nature in its wide spectrum of activities including planning, control and coordination of intra- and inter-firm players from upstream suppliers to downstream customers. As such, performance measurement of SC is a quite complex task and an effective assessment can significantly help enterprises in achieving their business goals. Objective of this study is to provide a comprehensive structural framework to facilitate assessment of various aspects contributing on SC performance.... 

    Analysis of Success Factors in Technological Cooperations in Nanotech Industry-a Multiple Case Study

    , M.Sc. Thesis Sharif University of Technology Malekifar, Mehdi (Author) ; Sheikhzadeh, Mehdi (Supervisor)
    Abstract
    Innovative small tech companies are required to often have cooperation with large companies in order to scale-up and commercialize their products. Such cooperation is referred as “Technological Cooperation” since it relies on development and commercialization of technology. In this research, as a multiple-case study in the arena of nanotechnology, five cases of technological cooperation are analyzed and key successful factors are identified. In this endeavor, 15 comprehensive interviews were conducted with both small tech companies and technology applicant companies, including experts of Nanotechnology Innovative Council (INIC) – playing the role of a mediator. Due to lack of a comprehensive... 

    Calculating Runoff Coefficient of Urmia Lake Basin by Empirical Models and Remot Sensing (RS) Technology

    , M.Sc. Thesis Sharif University of Technology Akbari, Mahdi (Author) ; Tajrishy, Masoud (Supervisor) ; Arasteh, Peyman (Co-Advisor)
    Abstract
    Estimation of runoff in the ungauged basins is a challenge for hydrologists. The main objective of this research is to produce runoff coefficient map using SCS-CN (1972) and Kennessey (1930) as empirical models to for Urmia Lake basin between for 2006-2011.Both SCS-CN and Kennessey methods use slope, land use, and soil permeability data to estimate surface runoff. Accuracy of each model is tested along with the observed runoff using the Root Mean Square Error (RMSE).Urmia Lake basin includes about 400,000 hectares irrigated land, which constitutes around 10 percent of the entire basin area. To exclude the anthropological activities from the estimations, methods were applied only for 28... 

    Pricing of Service Advance Sale System with Risk Consideration

    , M.Sc. Thesis Sharif University of Technology Khodakarami Mamaghani, Farnoosh (Author) ; Sheikhzadeh, Mehdi (Supervisor)
    Abstract
    Today service sector is an important part of economy in many countries and it accounts for a great portion of GDP in developed countries. The importance of the service sector has led to an expansion in research worldwide on services. Service has some unique specifications that make it different from product and research in this field is more challenging than production field. Pricing is one of the great challenges in service sector. Due to its intangibility and perishability, managing and pricing of service is complicated and ervice firms consistently seek for method and approaches to better manage their demand, capacity and prices. Advance sale is an effective approach which is commonly... 

    Produce of Antibacterial Composite Coating of PTFE+Ag+TiO2 On 316SS and Study Its Properties

    , M.Sc. Thesis Sharif University of Technology Sheikhzadeh, Mohammad Sajjad (Author) ; Afshar, Abdollah (Supervisor)
    Abstract
    This research investigated the corrosion and antibacterial properties of PTFE+TiO2/Ag coating and its adhesion to 316L stainless steel. To increase adhesion, polydopamine coating was created as an intermediate layer by chemical deposition method on stainless steel, then PTFE + TiO2 coating was created on the sample by immersion method, and then silver nanoparticles were applied as the third layer by chemical deposition method. According to the polarization curves, the most corrosion-resistant coatings with corrosion current density of 3.34×10-5 and 3.25×10-4 μA are coatings PTFE+TiO2 and PTFE/PTFE+TiO2/Ag respectively. In terms of antibacterial activity, according to the non-growth halo... 

    A textural approach for recognizing architectural distortion in mammograms

    , Article Iranian Conference on Machine Vision and Image Processing, MVIP ; September , 2013 , Pages 136-140 ; 21666776 (ISSN) ; 9781467361842 (ISBN) Mohammadi, E ; Fatemizadeh, E ; Sheikhzadeh, H ; Khoubani, S ; Sharif University of Technology
    IEEE Computer Society  2013
    Abstract
    Breast cancer is considered as the most important cause of death among women. Architectural distortions are very important signs of breast cancer and early detection of them is a rewarding work. In this paper we propose a method to recognize architectural distortion from normal parenchyma. In our proposed method, appropriate features are extracted by the analysis of oriented textures with the application of orientation component of recent the state-of-the-art local texture descriptor called Monogenic Binary Coding (MBC). In addition, we transform Region of Interests (ROIs) to polar coordinates in order to highlight some specific patterns in mammograms. Various classifiers are used over a set... 

    Analysis of Launch Time in New Product Development With Risk Considerations

    , M.Sc. Thesis Sharif University of Technology Sadat Sharifonnasabi, Zahra (Author) ; Sheikhzadeh, Mehdi (Supervisor)
    Abstract
    The importance of New Product Development (NPD) projects has been realized more and more in recent years. Among different decisions to be made in NPD process, one of the most critical decisions is about the best time to launch new product(s). Due to existence of many internal and external influential factors, determining the optimal launch time is often too complicated and it is quite hard to systematically analyze it. Despite risky nature of NPD, risk considerations in determining the optimal launch time have not been addressed in literature due to the mentioned complexity. In this research, we developed a model that takes in to account risk considerations while systematically determining...