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A data analytics framework for reliable bus arrival time prediction using artificial neural networks
, Article International Journal of Data Science and Analytics ; 2023 ; 2364415X (ISSN) ; Farjad, A ; Azadnia, A ; Javidi, M ; Chunduri, R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2023
Abstract
The analysis of extensive vehicle location data in an urban bus system requires an efficient data-driven method so that its output can be used to improve both the information and operational reliabilities of the bus transit services. This research aims to design and implement an integrated model for forecasting bus arrival times using artificial intelligence techniques. The novelty of the research lies in developing an integrated predictive model based on a neural network computing framework to improve the results of fleet arrival forecasting models based on the estimation of travel time reliability. To validate the prediction model, extensive experiments are conducted to compare the...
Quantitative Rsk Assessment and Accident Frequency Determination Based on Fuzzy Logic with Shazand Oil Refinery Accident Case Study
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davoud (Supervisor)
Abstract
Today, Quantitative Risk Assessment (QRA) has become an efficient tool in decision making for safety and process experts. To assess the risk of any accident scenario, it is necessary that the probability of that event be determined in addition to estimating the probable consequences. Event tree and fault tree analysis are known to be the standard tools for calculating the frequency of incident outcomes.
In this research, a new method based on Markov chin and Fuzzy theory is presented to estimate the occurrence probability of events. A one of important parameter which has sufficient effect on probability of incident frequency, is inspection and maintenance interval. in this research...
In this research, a new method based on Markov chin and Fuzzy theory is presented to estimate the occurrence probability of events. A one of important parameter which has sufficient effect on probability of incident frequency, is inspection and maintenance interval. in this research...
Short-Circuit Failure Detection in Series-Connected IGBTs for Reliability Improvements
, M.Sc. Thesis Sharif University of Technology ; Kaboli, Shahriyar (Supervisor)
Abstract
In high-voltage power electronics systems where the supply voltage exceeds the maximum voltage these devices can withstand, series-connected IGBTs with TO-247 packaging and simultaneous gate command circuitry are used to create a high-voltage switch with an on and off time equivalent to a single IGBT. By considering voltage protection circuits for the series IGBTs, the large supply voltage is approximately evenly divided among the series switches. The resulting high-voltage switch has smaller conduction and switching losses compared to single high-voltage switches, has a lower finished price, and its turn-on time is much shorter due to their smaller gate-emitter junction capacitance...
Inherently safe and economically optimal design using multi-objective optimization: The case of a refrigeration cycle
, Article Process Safety and Environmental Protection ; Volume 104 , 2016 , Pages 254-267 ; 09575820 (ISSN) ; Shahhosseini, H. R ; Javidi, M ; Sharifzadeh, M ; Rashtchian, D ; Sharif University of Technology
Institution of Chemical Engineers
2016
Abstract
The economic viability of industrial processes strongly depends on their safe and reliable operation. The method of inherent safe process design enables systematic consideration of safety measures in order to ensure process safe operation at the early stages of process design. The challenge is that the economic measures that are often considered for the design of industrial processes are often incommensurable with the safety measures. In the present research, a novel framework is proposed in which the safety criteria are quantified based on consequence modeling and aggregated with the economic performance using multi-objective optimization programming. The developed methodology was applied...
Dielectrophoretic interaction of two particles in a uniform electric field
, Article Microsystem Technologies ; Volume 25, Issue 7 , 2019 , Pages 2699-2711 ; 09467076 (ISSN) ; Moghimi Zand, M ; Dastani, K ; Sharif University of Technology
Springer Verlag
2019
Abstract
The local electric field distorsion induced by a dielectric particle leads to particle–particle interactions and assembly which is very interesting for their useful applications on microfluidic devices. Particles behavior becomes more complicated if several particles interact at the same time. This paper presents a comprehensive numerical analysis of the assembly and particle–particle interactions for two similar and dissimilar dielectric particles immersed in a dielectric fluid using the immersed interface method based on two-dimensional direct-current dielectrophoresis. The immersed interface method is a finite-difference (or finite element) based numerical method which its key advantage...
Effect of input voltage frequency on the distribution of electrical stresses on the cell surface based on single-cell dielectrophoresis analysis
, Article Scientific Reports ; Volume 10, Issue 1 , 2020 ; Moghimi Zand, M ; Kavand, H ; Javidi, R ; Hadi, A ; Valadkhani, Z ; Renaud, P ; Sharif University of Technology
Nature Research
2020
Abstract
Electroporation is defined as cell membrane permeabilization under the application of electric fields. The mechanism of hydrophilic pore formation is not yet well understood. When cells are exposed to electric fields, electrical stresses act on their surfaces. These electrical stresses play a crucial role in cell membrane structural changes, which lead to cell permeabilization. These electrical stresses depend on the dielectric properties of the cell, buffer solution, and the applied electric field characteristics. In the current study, the effect of electric field frequency on the electrical stresses distribution on the cell surface and cell deformation is numerically and experimentally...
A multivariable model for estimation of vapor cloud explosion occurrence possibility based on a Fuzzy logic approach for flammable materials
, Article Journal of Loss Prevention in the Process Industries ; Volume 33 , January , 2015 , Pages 140-150 ; 09504230 (ISSN) ; Abdolhamidzadeh, B ; Reniers, G ; Rashtchian, D ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
In this paper, a new method based on Fuzzy theory is presented to estimate the occurrence possibility of vapor cloud explosion (VCE) of flammable materials. This new method helps the analyst to overcome some uncertainties associated with estimating VCE possibility with the Event Tree (ET) technique. In this multi-variable model, the physical properties of the released material and the characteristics of the surrounding environment are used as the parameters specifying the occurrence possibility of intermediate events leading to a VCE. Factors such as area classification, degree of congestion of a plant and release rate are notably affecting the output results. Moreover, the proposed method...
A fast optimization method for extension of depth-of-field in three-dimensional task-specific imaging systems
, Article IEEE/OSA Journal of Display Technology ; Volume 6, Issue 10 , August , 2010 , Pages 412-421 ; 1551319X (ISSN) ; Kavehvash, Z ; Mehrany, K ; Javidi, B ; Sharif University of Technology
2010
Abstract
In this paper, we present a novel approach to generate images of extended depth-of-field (DOF) to support realization of three-dimensional (3D) imaging systems such as integral imaging. In our approach in extending the DOF, we take advantage of the spatial frequency spectrum of the object specific to the task in hand. The pupil function is thus engineered in such a fashion that the modulation transfer function (MTF) is maximized only in these selected spatial frequencies. We extract these high energy spatial frequencies using the principal component analysis (PCA) method. Moreover, given the need for many pupil function engineering steps in 3D imaging systems, we have constructed an...
Design and Implementation of a Distributed System for Energy Management in a Hybrid-Energy Building
, M.Sc. Thesis Sharif University of Technology ; Goudarzi, Maziar (Supervisor)
Abstract
Solar panels are still rather expensive equipments. At current electricity prices, it takes several years to return the investment made to install them in a household. Smarter use of their produced energy can help reduce this break-even time, and hence, would motivate more households to be willing to install and use them which would finally result in a more sustainable society with less reliance on fossil fuels. Electricity prices usually differ at different times of day with the common, but unfortunate, property that the price is maximized at evenings when the solar energy production is minimal or non-existent while at the peak production of the solar panels, i.e., around noon, the price is...
, M.Sc. Thesis Sharif University of Technology ; Ramezani Saadat, Ahmad (Supervisor)
Abstract
Polymer flooding can yield considerable increase in percentage recovery. However, there are limitations with the existing polymer flooding technology, such as thermal, mechanical, bacterial degradation, surface absorption and undesirable plugging. A novel nanocore shell structure of polyacrylamide and polystyrene designed and prepared to intellectually control mobility ratio in oil reservoirs and overcome weakness and limitations of classical polymer flooding. Polyacrylamide particles have been obtained using spray drying of dilute solution of polyacrylamide. Then, polystyrene shell has been produced on polyacryamide particles by in-situ polymerization of styrene monomer in hydrophobic...
Preparation and characterization of self-stimuli conductive nerve regeneration conduit using co-electrospun nanofibers filled with gelatin-chitosan hydrogels containing polyaniline-graphene-ZnO nanoparticles
, Article International Journal of Polymeric Materials and Polymeric Biomaterials ; Volume 73, Issue 3 , 2024 , Pages 165-175 ; 00914037 (ISSN) ; Ramazani Saadatabadi, A ; Sadrnezhaad, K ; Najmoddin, N ; Sharif University of Technology
2024
Abstract
The core-shell structure conduit with conductive, antibacterial, and highly piezoelectric properties was designed and fabricated by a multi-step process. First, the shell structure was fabricated by rolling the co-electrospun mats of polycaprolactone/polyvinylidene fluoride and gelatin incorporated with polyaniline/graphene (PAG) nanocomposites. Then, the fabricated mats were filled with gelatin/chitosan hydrogels containing PAG and zinc oxide nanoparticles. Characterization of the intermediate materials and the final conduit revealed high electrical conductivity and remarkable output voltage for shell and core materials. MTT assay and antibacterial tests confirmed bioactivity and...
Conductive nerve conduit with piezoelectric properties for enhanced PC12 differentiation
, Article Scientific Reports ; Volume 13, Issue 1 , 2023 ; 20452322 (ISSN) ; Ramazani Saadatabadi, A ; Sadrnezhaad, S. K ; Najmoddin, N ; Sharif University of Technology
Nature Research
2023
Abstract
Restoration of nerve tissue remains highly challenging, mainly due to the limited regeneration capacity of the nervous system and the development of fibrosis. This limitation necessitates designing new nerve guidance channel to promote nerve repairing. In this study, we developed a novel core/shell conduit to induce PC12 differentiation. Co-electrospinning method was utilized to produce a fibrous shell containing polycaprolactone/polyvinylidene fluoride PCL/PVDF, gelatin and polyaniline/graphene (PAG) nanocomposite. The core section of the conduit was filled with chitosan–gelatin hydrogel containing PAG and ZnO nanoparticles. Such conduit shows antibacterial activity, electrical conductivity...
An energy-efficient multi-sensor scheduling mechanism with QoS support for WBANs
, Article IEEE Wireless Communications and Networking Conference, WCNC ; 2014 , pp. 1703-1708 ; ISSN: 15253511 ; Ashtiani, F ; Javidi, T ; Nasiri-Kenari, M ; Vahdat, B. V ; Sharif University of Technology
2014
Abstract
In wireless body area networks (WBANs) it is necessary to devise an energy-efficient MAC scheduling mechanism which is capable of meeting strict QoS requirements. In this paper, special characteristics of WBAN channels, namely, the slow fading, the periodicity of fading, and the correlation among the channels have been exploited to formulate the sensor scheduling problem as a partially observable Markov decision problem (POMDP). Specific algorithms based on value iteration and pruning have been proposed in order to reduce the computational burden associated with the corresponding POMDP. The proposed scheduling mechanism is compared against a TDMA scheduling for a three-sensor network, and an...
Extension of depth of field using amplitude modulation of the pupil function for bio-imaging
, Article Proceedings of SPIE - The International Society for Optical Engineering, 6 April 2010 through 8 April 2010 ; Volume 7690 , May , 2010 ; 0277786X (ISSN) ; 9780819481542 (ISBN) ; Bagheri, S ; Mehrany, K ; Javidi, B ; Sanchez, E ; Martinez Corral, M ; Sharif University of Technology
2010
Abstract
In this paper we present a novel approach to generate images of extended depth of field (DOF) without compromising the lateral resolution to support realization of three-dimensional imaging systems such as integral imaging. In our approach in extending DOF, we take advantage of the spatial frequency spectrum of the object specific to the task in hand. The pupil function is thus engineered in such a fashion that the modulation transfer function (MTF) is maximized only in these selected spatial frequencies. We extract these high energy spatial frequencies using PCA method. The advantage of our approach is illustrated using an amplitude modulation and a phase modulation example. In these...
Metabolic profiling of seminal plasma from teratozoospermia patients
, Article Journal of Pharmaceutical and Biomedical Analysis ; Volume 178 , January , 2020 ; Chashmniam, S ; Nobakht, F ; Amini, M ; Javidi, A ; Minai Tehrani, A ; Arjmand, B ; Gilany, K ; Sharif University of Technology
Elsevier B. V
2020
Abstract
Teratozoospermia is one of conditions that can cause male infertility. The mechanism of teratozoospermia remains unclear. The knowledge of the metabolites in human seminal plasma (HSP) is meaningful for the pathological study of teratozoospermia. Analysis of changed metabolites in HSP can help understand the cellular mechanism, find the novel biomarkers and subsequently design a diagnosis test. In this study, the analysis of samples performed by proton nuclear magnetic resonance spectroscopy (1H NMR spectroscopy) to identify the various metabolites, with the aim of finding metabolic profiles and biomarkers related to male infertility. Eighteen de-regulated metabolites were identified in...
Hyaluronic acid-based wound dressings
, Article Iranian Journal of Polymer Science and Technology ; Volume 37, Issue 1 , 2024 , Pages 27-46 ; 10163255 (ISSN) ; Alizadeh, M ; Mouraki, A ; Tavakolizadeh, M ; Samadi, K ; Radpour, M ; Amirian, A ; Javidi, A ; Ghermezgoli, Z. M ; Daemi, H ; Sharif University of Technology
2024
Abstract
The growing world's population and the increase of underlying diseases such as diabetes have caused an increasing trend of skin damage and imposed high costs on the healthcare system. The complex and multi-step nature of wound healing highlights the importance of introducing efficient products for effective treatment of skin injuries. Therefore, it is necessary to introduce new wound healing products to treat these types of injuries effectively. The modern wound dressings have received much attention in recent years. These dressings facilitate skin regeneration by providing suitable physical and biological conditions. Wound dressings are produced in sponge, fibrous, hydrogel, film, and...
Network vulnerability analysis through vulnerability take-grant model (VTG)
, Article 7th International Conference on Information and Communications Security, ICICS 2005, Beijing, 10 December 2005 through 13 December 2005 ; Volume 3783 LNCS , 2005 , Pages 256-268 ; 03029743 (ISSN); 3540309349 (ISBN); 9783540309345 (ISBN) ; Sadoddin, R ; Jalili, R ; Zakeri, R ; Omidian, A. R ; Sharif University of Technology
2005
Abstract
Modeling and analysis of information system vulnerabilities helps us to predict possible attacks to networks using the network configuration and vulnerabilities information. As a fact, exploiting most of vulnerabilities result in access rights alteration. In this paper, we propose a new vulnerability analysis method based on the Take-Grant protection model. We extend the initial Take-Grant model to address the notion of vulnerabilities and introduce the vulnerabilities rewriting rules to specify how the protection state of the system can be changed by exploiting vulnerabilities. Our analysis is based on a bounded polynomial algorithm, which generates the closure of the Take-Grant graph...
Sequence dependence of the binding energy in chaperone-driven polymer translocation through a nanopore
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 1 , January , 2011 ; 15393755 (ISSN) ; Ejtehadi, M. R ; Metzler, R ; Sharif University of Technology
2011
Abstract
We study the translocation of stiff polymers through a nanopore, driven by the chemical-potential gradient exerted by binding proteins (chaperones) on the trans side of the pore. Bound chaperones prevent backsliding through the pore and, therefore, partially rectify the polymer passage. We show that the sequence of chain monomers with different binding affinity for the chaperones significantly affects the translocation dynamics. In particular, we investigate the effect of the nearest-neighbor adjacency probability of the two monomer types. Depending on the magnitude of the involved binding energies, the translocation speed may either increase or decrease with the adjacency probability. We...
First passage time distribution of chaperone driven polymer translocation through a nanopore: Homopolymer and heteropolymer cases
, Article Journal of Chemical Physics ; Volume 135, Issue 24 , 2011 ; 00219606 (ISSN) ; Metzler, R ; Ejtehadi, M. R ; Sharif University of Technology
2011
Abstract
Combining the advection-diffusion equation approach with Monte Carlo simulations we study chaperone driven polymer translocation of a stiff polymer through a nanopore. We demonstrate that the probability density function of first passage times across the pore depends solely on the Péclet number, a dimensionless parameter comparing drift strength and diffusivity. Moreover it is shown that the characteristic exponent in the power-law dependence of the translocation time on the chain length, a function of the chaperone-polymer binding energy, the chaperone concentration, and the chain length, is also effectively determined by the Péclet number. We investigate the effect of the chaperone size on...
Reply: Abedpour, asgari, and tabar
, Article Physical Review Letters ; Volume 106, Issue 20 , 2011 ; 00319007 (ISSN) ; Asgari, R ; Tabar, M. R. R ; Sharif University of Technology
2011