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    Simulation-Based Optimization for IoT-Enabled Epidemic Patients Care Systems

    , M.Sc. Thesis Sharif University of Technology Bisheh Niasar, Mohammad Amir (Author) ; Hassan Nayebi, Erfan (Supervisor)
    Abstract
    This research focuses on examining and improving healthcare systems, particularly during crises and pandemics. Following disasters such as natural calamities and pandemics like COVID-19, healthcare systems face significant challenges due to the increased demand for medical services, creating a substantial threat to the population in the affected regions. This study emphasizes the importance of utilizing modern technologies such as the Internet of Things (IoT) and telemedicine systems in alleviating the pressure on healthcare systems. A combined approach of prediction and multi-objective optimization based on simulation is proposed in this study to improve resource allocation and demand... 

    Analyzing the productivity of maintenance systems using system dynamics modeling method

    , Article International Journal of Systems Assurance Engineering and Management ; Volume 10, Issue 2 , 2019 , Pages 201-211 ; 09756809 (ISSN) Esmaeili, E ; Karimian, H ; Najjartabar Bisheh, M ; Sharif University of Technology
    Springer  2019
    Abstract
    Achievement of industries in production and offering products depends on different factors like having an appropriate maintenance system. This issue should be reached through the most appropriate and practical methods. In this study, based on how the external parameters would influence the productivity of a maintenance system the researcher aims at designing a dynamic system model to analyze the productivity of a maintenance system using acquired information from a car device company by determination of the percentage of parameters and indexes and their influence on maintenance system productivity. The proposed model is simulated for a system with parameters of precise value according to... 

    Assessment of nitrate contamination in unsaturated zone of urban areas: the case study of Tehran, Iran

    , Article Environmental Geology ; Volume 57, Issue 8 , 2009 , Pages 1785-1798 ; 09430105 (ISSN) Joekar Niasar, V ; Ataie Ashtiani, B ; Sharif University of Technology
    2009
    Abstract
    Modeling fate of nitrogen in unsaturated and saturated zone is a complex process, which requires detailed geochemical data. Complexities of the process as well as data insufficiencies are two major issues, which make quantitative assessment of the problem more complicated. In this work, a lumped-parameter model (LPM) is proposed that has been evaluated for a data-limited case to study temporal and steady-state behavior of Nitrate and Ammonium in unsaturated zone. The concentration of components in the model are assumed as the depth-averaged concentrations, and dispersive fluxes have been neglected. The case study area is Tehran City aquifer, which is highly contaminated by domestic... 

    The impact of the electrical behavior of oil-brine-rock interfaces on the ionic transport rate in a thin film, hydrodynamic pressure, and low salinity waterflooding effect

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 620 , 2021 ; 09277757 (ISSN) Pourakaberian, A ; Mahani, H ; Niasar, V ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    Wettability alteration is the principal low-salinity-effect (LSE) in many oil-brine-rock (OBR) systems. Our recent experimental results have demonstrated that wettability alteration by low salinity is slow. It is expected that the electrical behavior of oil/brine and rock/brine interfaces and the water film geometry control both the transient hydrodynamic pressure, and the time-scale of ionic transport in the film, thus the kinetics and degree of wettability alteration. In this paper, the electro-diffusion process induced by the imposed ionic strength gradient is simulated by solving Poisson-Nernst-Planck equations in a water film bound between two charged surfaces, using a finite... 

    Ultimate strength analysis of jacket type offshore platforms due to wave, current and wind loading

    , Article Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, 15 June 2008 through 20 June 2008, Berlin ; Volume 1 , 2008 , Pages 779-786 ; 9780791848234 (ISBN) Mirzadeh Niasar, J ; Aghakouchak, A. A ; Samadani, S ; Aghakouchak, A
    2008
    Abstract
    As the result of safety factors considered in load and resistant values for the design of new offshore platforms, a higher resistance compared to the 100 year return period environmental loading, is achieved in the structure. This type of design is usually performed using linear methods of structural analysis. In this case the structure practically has a high reserve capacity which is disregarded in the design phase but may be considered in special cases. One of these important cases is when an existing structure is assessed and evaluated after elapse of its structural life. In this case using the platforms reserve capacity, through a non-linear analysis such as push-over, would be logical... 

    Dynamics of electrostatic interaction and electrodiffusion in a charged thin film with nanoscale physicochemical heterogeneity: Implications for low-salinity waterflooding

    , Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 650 , 2022 ; 09277757 (ISSN) Pourakaberian, A ; Mahani, H ; Niasar, V ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    The slow kinetics of wettability alteration toward a more water-wetting state by low-salinity waterflooding (LSWF) in oil-brine-rock (OBR) systems is conjectured to be pertinent to the electrokinetic phenomena in the thin brine film. We hypothesize that the nanoscale physicochemical heterogeneities such as surface roughness and surface charge heterogeneity at the rock/brine interface control further the dynamics of electrodiffusion and electrostatic disjoining pressure (Πel), thus the time-scale and the magnitude of the low salinity effect (LSE). In this regard, film-scale computational fluid dynamics (CFD) simulations were performed. The coupled Poisson-Nernst-Planck (PNP) equations were... 

    Online Monitoring of PD in Power Transformers

    , M.Sc. Thesis Sharif University of Technology Ghaffarian Niasar, Mohamad (Author) ; Vakilian, Mehdi (Supervisor)
    Abstract
    PD detection can be done using on-line or off-line methods. Online PD detection methods have several advantages; such as: increasing system reliability, outage time reduction and higher safety. This method doesn’t need any special high voltage source. When on line monitoring is carried out for PD measurement, the noises in the environment and the electromagnetic interference (EMI) make it difficult to detect the PD signal. Therefore de-noising should be employed to filter out the interferences involved in the detected signal. In this thesis wavelet transform is introduced for this purpose. In this method, the background noise in the site of measurement is recorded as a reference noise to be... 

    Driving Behavior Estimation with Smartphone Data

    , M.Sc. Thesis Sharif University of Technology Mohammad Beygi, Mohammad Sadegh (Author) ; Samimi, Amir (Supervisor)
    Abstract
    Identifying driving behaviors and building an efficient and accurate driving behavior recognition model is of paramount importance for improving driving safety. Nowadays, with the ubiquity of smartphone sensors, many researchers are using smartphone sensory data to create models which forecast driving behaviors. This research introduces a logit model that predicts nine types of driving events using accelerometer and gyroscope sensors with an accuracy of 76 percent  

    Development of a 2D Quasi-Physical model for Predicting Fire Spread in Grasslands

    , Ph.D. Dissertation Sharif University of Technology Mohammadian Bisheh, Esmaeil (Author) ; Farhanieh, Bijan (Supervisor) ; Afshin, Hossein (Co-Supervisor)
    Abstract
    Fire behavior analysis and fire dynamics simulations, especially Wildfire, is of great importance due to all the necessities. The development and application of fire dynamics models, especially in complex geometric spaces, has become one of the priorities of the firefighting and environmental organizations of countries and international unions at the international level today. Analytical methods are not suitable for complex geometries due to the complexity of fire dynamics equations. Experimental methods are a desirable method for investigating complex geometries, but the fire phenomenon requires a high experimental study cost; Because fire causes severe damage or even destruction of a... 

    Thermal Simulation of Sponge Iron Production by Höganäs Method

    , M.Sc. Thesis Sharif University of Technology Akbarian, Amir Hassan (Author) ; Halali, Mohammad (Supervisor)
    Abstract
    Sponge Iron production is conducted in various methods that one of them is using coal as a reduction agent. Hoganas process is a different coal-based method that has not been investigated in details. Therefore, the heat transfer method in the system is one of the basic steps to a better recognition of this process (with special Hoganas charging). The present paper investigates the temperature distribution method in the Hoganas cylinder through a numerical model using finite elements. The effects of different parameters, namely preheating and porosity were studied on ceramic crucible made from silicon carbide and it was observed that the consumption energy decreases with the increase of... 

    Consequence Modelling and Probabilistic Risk Assessment of Oil Spills in the Marine Waters

    , Ph.D. Dissertation Sharif University of Technology Amir Heidari, Payam (Author) ; Raie, Mohammad (Supervisor)
    Abstract
    Different causes in the exploration, production and transport of oil in the marine environment result in oil spill events. Since elimination of the probability of occurrence of spills is not possible, it is important to have a plan to control the risk of oil spills by optimal response. In this research, a general stucture is presented for the DSS required for oil spill response planning. This system can be used for evaluation of the effectiveness of response drills, and risk-based ranking of receptor areas and spill sources. Ranking based on risk is realized through probabilistic or stochastic risk assessment. The applicability of the proposed system is examined in differnet case studies in... 

    Impact of oil polarity on the mixing time at the pore scale in low salinity waterflooding

    , Article Energy and Fuels ; Volume 34, Issue 10 , 16 September , 2020 , Pages 12247-12259 Mohammadi, S ; Mahani, H ; Ayatollahi, S ; Niasar, V ; Sharif University of Technology
    American Chemical Society  2020
    Abstract
    The efficiency of low salinity waterflooding, particularly during tertiary mode injection, is highly controlled by in situ mixing between the stagnant regions holding high salinity water (HSW) and the flowing regions containing low salinity water (LSW) because it impacts directly the electrokinetics of wettability alteration and the time scale of the low salinity effect. This study aims to address the effects of oil polarity and charged rock surfaces on the time scale of mixing and transport under two-phase flow conditions. A systematic series of micromodel experiments were performed. The micromodels were first saturated with high salinity formation brine and oil (both model and crude oil);... 

    Large scale modeling of nitrogen transformation in the unsaturated zone—a case study of Tehran city, Iran

    , Article Groundwater for Sustainable Development: Problems, Perspectives and Challenges ; 2008 , Pages 169-179 ; 9780203894569 (ISBN); 9780415407762 (ISBN) Joekar Niasar, V ; Ataie Ashtiani, B ; Sattari, Z ; Sharif University of Technology
    CRC Press  2008
    Abstract
    Since most of models for estimation of groundwater contamination are developed for agricultural applications and they are often sophisticated, in this paper a combined approach based on analytical methods that need limited input data has been developed. To estimate nitrate contamination of unsaturated zone in large areas, a Lumped Parameter Model (LPM) and the mass balance approach have been used together. In the case study, model results show an acceptable correlation with field measurements. In addition, the fate of nitrogen in the unsaturated zone is simply defined. © 2008 Taylor & Francis Group, London, UK  

    Optimization of amins mixture's formulation by neural networks in gas sweeting

    , Article 2006 AIChE Spring National Meeting, Orlando, FL, 23 April 2006 through 27 April 2006 ; 2006 ; 0816910057 (ISBN); 9780816910052 (ISBN) Farasat, I ; Giri, M. S ; Niasar, M. S ; Sharif University of Technology
    2006
    Abstract
    The use of neural networks for the optimization of amine mixtures formulations in gas sweetening is presented. This is an abstract of a paper presented at the AIChE Spring National Meeting (Orlando, FL 4/24-26/2006)  

    Kinetics of wettability alteration and droplet detachment from a solid surface by low-salinity: A lattice-Boltzmann method

    , Article Fuel ; Volume 329 , 2022 ; 00162361 (ISSN) An, S ; Zhan, Y ; Mahani, H ; Niasar, V ; Sharif University of Technology
    Elsevier Ltd  2022
    Abstract
    The dynamics of droplet detachment from a surface is a fundamental topic studied in coating engineering, fluid mechanics, and subsurface engineering applications. This topic has direct relevance to wettability alteration using the modified ionic composition of water in contact with oil droplet, low salinity waterflooding (LSWF). Previous experimental studies of LSWF have shown a very long timescale in wettability alteration which cannot be explained using bulk diffusion coefficient. In the present study, we address both the time scale of detachment, as well as the impact of buoyancy and interfacial forces (referred to as Bond number) on droplet detachment by proposing an advanced... 

    Investigating Effects of Urban Freight Companies' Scale on their Transport Efficiency and Developing a Tool for Integration of Freight Companies

    , M.Sc. Thesis Sharif University of Technology Dashti, Mohammad Mahdi (Author) ; Samimi, Amir (Supervisor) ; Kermanshah, Amir Hassan (Supervisor)
    Abstract
    In this research, a dashboard has been developed to support decision-making in the integration of freight companies. Freight companies usually consist of a limited number of vehicles due to the high cost of vehicles, while the fixed costs of a freight company constitute a significant part of that company's total cost. Therefore, if these companies are merged, their total cost will be substantially decreased. Moreover, under particular demand levels, the integration of freight companies reduces the mileage, travel time, and the number of required cars. Therefore, the integration of freight companies not only reduces fixed costs but also reduces other costs including greenhouse gas costs by... 

    Climatic Map of Atmospheric Corrosion of Iran

    , M.Sc. Thesis Sharif University of Technology Amir Ahmadi, Sam (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Atmospheric corrosion as one of the most principal factors of destruction is not Climatic map of atmospheric corrosion is closely related to air and atmospheric factors among which we can point out to different types of atmospheric pollutions such as NOX, SOX gases and pendant materials as well as the rate of humidity and rain and even the rate of sun radiation. The effects of these factors beside each other cause the speed of corrosion from a climate to another climate to be changed, which is presentable in form of a map. There is a 2 method to provide this map. First build up a station to measure the corrosion data and collect them in a long period of time. This method are time consuming... 

    Reconfigurable Architecture For Cryptanalysis Applications

    , M.Sc. Thesis Sharif University of Technology Noshadravan, Mohammad Reza (Author) ; Jahangir, Amir Hossein (Supervisor)
    Abstract
    Nowadays, the significance of securing data and information is undeniable. Cryptography is being used to provide data security. In addition, cryptanalysis is required to evaluate the effectiveness of cryptography methods, and hence, it is an essential concept for securing data. In general, the cryptography functions shall be designed in a way to impose a high load of time-intensive operations to prevent an adversary from accessing the main data from the encrypted data. As a result, cryptography and cryptanalysis algorithms need high performance computations. So far, a number of methods have been proposed to support the required performance. These methods include: distributed computing and... 

    Regularization from the Machine Learning Point of View

    , M.Sc. Thesis Sharif University of Technology Ghaemi, Mohammad Sajjad (Author) ; Daneshgar, Amir (Supervisor)
    Abstract
    In traditional machine learning approaches to classification, one uses only a labeled set to train the classifier. Labeled instances however are often difficult, expensive, or time consuming to obtain, as they require the efforts of experienced human annotators. Meanwhile unlabeled data may be relatively easy to collect, but there has been few ways to use them. Semi-supervised learning addresses this problem by using large amount of unlabeled data, together with the labeled data, to build better classifiers. Because semi-supervised learning requires less human effort and gives higher accuracy.Formally, this intuition corresponds to estimating a label function f on the graph so that it... 

    On the Density Matrix of Graphs

    , M.Sc. Thesis Sharif University of Technology Kazemi, Mohammad Reza (Author) ; Daneshgar, Amir (Supervisor)
    Abstract
    Density matrix of graphs as defined -for the first time- in [S. Braunstein and et al. The laplacian of a graph as a density matrix, Annals of Combinatorics, (2006)], is obtained through dividing the Laplacian matrix by the degree sum. This matrix is also semi-positive and trace one. Therefore one may talk about the Von Neumann entropy of this matrix. In [F. Passerini, S. Severini. Quantifying complexity in networks: The Von Neumann entropy. IJATS, (2009)], authors have claimed that this quantity can be consisered as a measure of regularity. Here, using a geometric interpretation of Von Neumann entropy, expresed in [G. Mitchison, R. Jozsa, Towards a geometrical interpretation of quantum...