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    Some improvements on the unfolding inverse finite element method for simulation of deep drawing process

    , Article International Journal of Advanced Manufacturing Technology ; Vol. 72, issue. 1-4 , 2014 , pp. 447-456 ; ISSN: 02683768 Bostan Shirin, M ; Assempour, A ; Sharif University of Technology
    2014
    Abstract
    The linear unfolding inverse finite element method (IFEM) has been modified and enhanced by implementing large deformation relations. The method is helpful to predict forming severity of the part that should be deep drawn as well as its blank shape and strain distribution in preliminary design stage. The approach deals with minimization of potential energy and large deformation relations with membrane elements. To reduce the computation time, the part is unfolded properly on the flat sheet and treated as 2D problem. Moreover, the nonlinear stress-strain relationship of plastic material properties has been considered to increase the accuracy of the results. An experiment set up has been... 

    Analysis of deep drawing process to predict the forming severity considering inverse finite element and extended strain-based forming limit diagram

    , Article Journal of Computational and Applied Research in Mechanical Engineering ; Volume 8, Issue 1 , 2018 , Pages 39-48 ; 22287922 (ISSN) Bostan Shirin, M ; Hashemi, R ; Assempour, A ; Sharif University of Technology
    Shahid Rajaee Teacher Tarining University (SRTTU)  2018
    Abstract
    An enhanced unfolding inverse finite element method (IFEM) is used together with an extended strain-based forming limit diagram (EFLD) to develop a fast and reliable approach to predict the feasibility of the deep drawing process of a part and determining where the failure or defects can occur. In the developed unfolding IFEM, the meshed part is properly fold out on the flat sheet and treated as a 2D problem to reduce the computation time. The large deformation relations, nonlinear material behavior and friction conditions in the blank holder zone are also considered to improve the accuracy and capability of the proposed IFEM. The extended strain-based forming limit diagram based on the... 

    Optimum design of middle stage tool geometry and addendum surfaces in sheet metal stamping processes using a new isogeometric-based framework

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; 2021 ; 09544054 (ISSN) Shamloofard, M ; Isazadeh, A. R ; Bostan Shirin, M ; Assempour, A ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Abstract
    An efficient isogeometric-based framework is presented to integrate optimum design and formability analysis of sheet metal forming processes. To assess the quality of the formed parts, several objective functions such as fracture, wrinkling, thickness variation, and stretching are studied. In this framework, geometric parameters of addendum surfaces and middle tools are considered as design variables, the objective functions are calculated using the recently developed one-step and multi-step inverse isogeometric methods, and the optimum design variables are obtained using the genetic global optimization algorithm. The major advantage of employing the inverse methods is to analyze the... 

    Implementation of optical tracker system for marker-based human motion tracking

    , Article 15th IASTED International Conference on Applied Simulation and Modelling, Rhodes, 26 June 2006 through 28 June 2006 ; Volume 2006 , 2006 , Pages 252-257 ; 0889865612 (ISBN); 9780889865617 (ISBN) Colahi, A ; Hoviatalab, M ; Rezaeian, T ; Alizadeh, M ; Bostan, M ; Sharif University of Technology
    2006
    Abstract
    In this paper a complete design of a high speed optical human motion tracking system has been described for biomechanical human motion analysis and animation craft applications. The main core of the image processing unit that is implemented by the differential algorithm procedure and some intelligent and conservative procedures that facilitate the search algorithm have also been proposed and implemented for the processing of human motions tracking images. In the next step an optimized modified direct linear transformation (MDLT) method has been used to reconstruct 3D locations of markers as an input data for animation unit. The low computational cost and the high precision in detecting and... 

    A new mapping technique to consider intermediate stages in multistep deep drawing

    , Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 228, Issue 9 , June , 2014 , Pages 1557-1569 ; ISSN: 09544062 Shirin, M. B ; Assempour, A ; Sharif University of Technology
    2014
    Abstract
    The inverse solution is helpful to determine the drawability of a part and drawing parameters at the initial design stage. The usual inverse algorithms consider the drawing process that occurs in one step and therefore they are not able to analyze the processes which need more than one drawing step. Therefore, multistep inverse solution has been used for such problems. The multistep inverse solution deals with finding the initial guesses of nodal positions on intermediate stages and solving inverse equations between two consecutive steps. In this paper, a new mapping method has been developed to find the initial nodal positions on intermediate stages and the unfolding technique has been... 

    Design of a marker-based human motion tracking system

    , Article Biomedical Signal Processing and Control ; Volume 2, Issue 1 , 2007 , Pages 59-67 ; 17468094 (ISSN) Kolahi, A ; Hoviattalab, M ; Rezaeian, T ; Alizadeh, M ; Bostan, M ; Mokhtarzadeh, H ; Sharif University of Technology
    2007
    Abstract
    In this paper a complete design of a high speed optical motion analyzer system has been described. The main core of the image processing unit has been implemented by the differential algorithm procedure. Some intelligent and conservative procedures that facilitate the search algorithm have also been proposed and implemented for the processing of human motions. Moreover, an optimized modified direct linear transformation (MDLT) method has been used to reconstruct 3D markers positions which are used for deriving kinematic characteristics of the motion. Consequently, a set of complete tests using some simple mechanical devices were conducted to verify the system outputs. Considering the system... 

    Development of an inverse finite element method with an initial guess of linear unfolding

    , Article Finite Elements in Analysis and Design ; Vol. 79, issue , 2014 , p. 1-8 Kankarani Farahani, M ; Bostan Shirin, M ; Assempour, A ; Sharif University of Technology
    2014
    Abstract
    An inverse finite element method (IFEM) has been developed for estimation of the blank size and prediction of the strain distribution in sheet metal forming. In the inverse method the nodal coordinates in the final shape are known and their corresponding positions on the initial blank should be determined. The developed method deals with logarithmic large strains of membrane triangular elements, virtual work principle and a new approach for friction modeling. This method leads to a system of nonlinear equations which is highly sensitive to the initial guess. In order to avoid the converging problems, especially in the quasi-vertical walls, an appropriate initial guess is introduced. The... 

    On the Performance Assessment and Parametric Study of Pre-stressed Concrete Doms Behavior

    , M.Sc. Thesis Sharif University of Technology Modarres Bostan Abad, Soheil (Author) ; Mofid, Masoud (Supervisor)
    Abstract
    Today, with the replacement of the old method of force-based design by the new method of performance-based design in structural and earthquake engineering, many structural and earthquake researchers have focused in their studies on this area. The performance-based design aims at enabling engineers to design structures with predictable performance. Designing space structures has particular complexities. In space structures, the failure of a structural member does not necessarily mean the failure of the entire structure, because the redistribution of power will occur between the adjacent members after the failure of a member and the structure can thus have further support capacity. Similarly,... 

    Tracking Consumers Throughout Their Purchase Journey: Using Deep Learning Methods

    , M.Sc. Thesis Sharif University of Technology Hayati, Danial (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    Over the past two decades, the interest in exploring consumers' behavior has risen to popularity. Nowadays, it is necessary for marketers to reach out to the right consumers at the right time and with the right message. Even though the positive impact of tracking consumers throughout their purchase journey and its managerial implications have been emphasized several times by academics, There is still a lack of practical research on how to discern the consumers' stage in the purchase journey from a holistic point of view. In this study, we develop several machine learning models, including RNNs (GRU and LSTM), Transformers, and XGBoost, by utilizing historical data of Yektanet (the leading... 

    A Study on Strategic Behavior of Drivers on Ride-hailing Platforms

    , M.Sc. Thesis Sharif University of Technology Tavassoli, Parto (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    Recently, the advent of online platforms as an intermediary tool has provided an opportunity for service providers and manufacturers to offer their services/products to consumers. Ride-hailing platforms are an example of these businesses where independent drivers and passengers are matched via an online platform. One of the most significant challenges faced by these companies is the emergence of strategic behaviors on both the demand and the supply side, which might affect the performance and profitability of the platform.In this thesis, we study the strategic behavior of drivers and its impact on their performance, using the data of one of the largest ride-hailing companies in Iran. We use... 

    Supply Chain Risk Study for Downstream Projects of Oil and Gas Industry in Iran

    , M.Sc. Thesis Sharif University of Technology Hosseini, Alireza (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    There are always some unpredictable phenomena happen in the process of constructing of a downstream petrochemichal plant resulting to delays that increase the cost compared with the benefits or sometimes cancelation of the projects that abodones the investors from the returns at all. On of the reasons that these issues can dwibdles the benefits is that most of Iranian’s downstream companies do not prepare suitable and sufficient capabilitities to cope with such a risks. In this thesis, at first, influensive risks on the downstream oil and gas projects in Iran have been studied based on a comprehensive litreture review, secondly using a questionnaire, these extracted risks have been assessed... 

    E-WOM and Customer Satisfaction in Robotic vs Traditional Hotels: A Topic Modeling Analysis

    , M.Sc. Thesis Sharif University of Technology Ahmadi, Ali (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    This research examines the attributes, themes, and topics discussed in electronic word-of-mouth (e-WOM) generated in TripAdvisor for robotic hotels in comparison to traditional ones. The first objective is to explore the themes and topics within TripAdvisor negative e-WOMs for both types of hotels and analyze how these topics differ between the two types of hotels, using the Latent Dirichlet Allocation (LDA) method. The research shows that which topics are mostly discussed in TripAdvisor negative e-WOMs for both types of hotels. Additionally, the research explores whether different themes, topics, and attributes have varying effects on user ratings in traditional hotels versus robotic ones,... 

    A Comparative Analysis of Positive eWOM Topics in Robotic and Conventional Hotels: Insights from TripAdvisor Reviews

    , M.Sc. Thesis Sharif University of Technology Einlou, Zahra (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    This study explores topics discussed in positive eWOM of robotic and conventional hotels through a comprehensive analysis of online reviews using Latent Dirichlet Allocation (LDA). LDA is an advanced topic modeling technique. To uncover topics discussed in eWOM of robotic hotels and conventional hotels, and then compare them to see if there are any meaningful statistical differences between them, three separate LDA models were implemented on reviews of robotic hotels, conventional hotels, and the overall rereviews of all hotels, respectively. The results reveal that “service quality and overall atmosphere” is the most common topic discussed considering both hotel types, with key themes... 

    Sentiment-Based Topic Analysis on Product Demand Prediction: Pre-Release and Post-Release Study

    , M.Sc. Thesis Sharif University of Technology Behrad, Hossein (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    This thesis examines the impact of electronic word-of-mouth (e-WOM) on product demand forecasting, specifically in the context of video game consoles. This study examines the importance of emotion-based topics and their impact on demand forecasting at two stages of the product life cycle: pre-launch and post-launch. Using sentiment analysis and topic modeling, this study uncovers product sales drivers and captures evolving consumer sentiment throughout the product lifecycle. By integrating insights from diffusion theory and consumer information search theory, this research contributes to the field of demand forecasting using social media data. This research shows that by using the topics... 

    Mining the Tenant Experience: Uncovering the Determinants of Residential Satisfaction through Topic Modelling of Online Rental Apartment Reviews

    , M.Sc. Thesis Sharif University of Technology Ghasemi, Azin (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    Residential satisfaction plays a pivotal role in shaping liveable cities, profoundly influencing individuals' health and well-being. In contrast, dissatisfaction in living environments often triggers relocation intentions, leading to significant vacancy costs for landlords and property managers. While previous studies predominantly relied on traditional methods like surveys and interviews, our research adopts a novel, bottom-up approach, analysing this phenomenon through the lens of residents themselves. Leveraging a custom-developed Python-based web scraper, we meticulously gathered 195,000 online reviews from apartments.com. This comprehensive dataset spans the most populous cities and... 

    Optimum design of middle stage tool geometry and addendum surfaces in sheet metal stamping processes using a new isogeometric-based framework

    , Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Volume 236, Issue 6-7 , 2022 , Pages 741-757 ; 09544054 (ISSN) Shamloofard, M ; Isazadeh, A. R ; Shirin, M. B ; Assempour, A ; Sharif University of Technology
    SAGE Publications Ltd  2022
    Abstract
    An efficient isogeometric-based framework is presented to integrate optimum design and formability analysis of sheet metal forming processes. To assess the quality of the formed parts, several objective functions such as fracture, wrinkling, thickness variation, and stretching are studied. In this framework, geometric parameters of addendum surfaces and middle tools are considered as design variables, the objective functions are calculated using the recently developed one-step and multi-step inverse isogeometric methods, and the optimum design variables are obtained using the genetic global optimization algorithm. The major advantage of employing the inverse methods is to analyze the... 

    Diagnosing anterior cruciate ligament injuries using a knee arthrometer: Design, fabrication, and clinical evaluation

    , Article Biomedical Engineering - Applications, Basis and Communications ; Volume 23, Issue 3 , April , 2011 , Pages 181-192 ; 10162372 (ISSN) Soudbakhsh, D ; Sahraei, E ; Shirin, M. B ; Farahmand, F ; Tahmasebi, M. N ; Parnianpour, M ; Sharif University of Technology
    2011
    Abstract
    Every year many people suffer from knee injuries. Previous studies on patients with knee injuries have shown that about 40% of knee injuries are Ligament injuries, and about 50% of the ligament injuries are the Anterior Cruciate Ligament (ACL) injuries. Along with other methods, knee arthrometers are widely used to diagnose ACL injuries. In the current research, a knee arthrometer was designed and developed to provide a reliable and repeatable measurement of knee laxity under anteriorposterior applied loads. Testretest configurations to examine repeatability of the device resulted in less than 1.5-mm difference for more than 97% of tests under applied loads of up to 90 N. These tests... 

    Examining Customer Behavior In Regarding OBA

    , M.Sc. Thesis Sharif University of Technology Zolfagharinasab, Mehdi (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    In recent years, Internet advertising has become increasingly customized to individual users. As advertising carry on refining its capacities, it is more likely to be seen as insightful and useful by everyone. Consumers, particularly Gen Y and older members of Gen Z, are becoming more accepting of relevant advertising as digital acquaintance. Consumers now welcome active advertising that responds and reflects social activity, location, and brand and product preferences in real-time. This ability to be agile within the consumer’s connected experience is an emerging revenue driver and will continue to grow as ad platforms and ad presentations become smarter. But more personalization results in... 

    Investigation on the Effect of Product Involvement in Online Targeted Advertising

    , M.Sc. Thesis Sharif University of Technology Sharifpour, Parisa (Author) ; Aslani, Shirin (Supervisor)
    Abstract
    Nowadays, one of the most popular methods of advertising is online advertising, which is commonly used by many businesses. In the meantime, targeting the right person at the right moment to show an advertisement is always a major concern of advertisers and other players in this field. One of the areas of study in the literature in this field is the investigation of factors affecting the effectiveness of targeted advertising. The purpose of the upcoming research is to investigate the impact of the advertised product involvement in targeted online advertising. This level of effectiveness is measured by considering click intention as a measure of effectiveness and examining the impact of... 

    Experimental investigation of paraffin nano-encapsulated phase change material on heat transfer enhancement of pulsating heat pipe

    , Article Journal of Thermal Analysis and Calorimetry ; Volume 137, Issue 5 , 2019 , Pages 1603-1613 ; 13886150 (ISSN) Heydarian, R ; Shafii, M. B ; Rezaee Shirin Abadi, A ; Ghasempour, R ; Alhuyi Nazari, M ; Sharif University of Technology
    Springer Netherlands  2019
    Abstract
    In this study, a mixture of nano-encapsulated phase change materials in water has been used as the working fluid in a pulsating heat pipe in order to investigate its thermal performance. The results of the experiments showed that using the nano-encapsulated paraffin dispersed in water as working fluid improves heat transfer and decreases the thermal resistance of the pulsating heat pipe. On the other hand, among the tested concentrations for nano-encapsulated paraffin, there is an optimal value in which increasing the concentration causes an increase in the thermal resistance of the pulsating heat pipe due to the increased dynamic viscosity of the fluid. Enhancement in the thermal...