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tavakoli-kashi--motahareh
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Trajectory design for cooperative combat missions
, Article 2008 IEEE Aerospace Conference, AC, Big Sky, MT, 1 March 2008 through 8 March 2008 ; 2008 ; 1095323X (ISSN) ; 1424414881 (ISBN); 9781424414888 (ISBN) ; Sharif University of Technology
2008
Abstract
In this paper, a hierarchical method for trajectory design for cooperative combat missions (CCM) is presented. In a military environment, in addition to physical constraints (aircraft dynamics and mountains) there are threats made by Radars or Artillery. So an important constraint, "Avoid Threats", is added to physical constraints. Major steps in trajectory design are: "Target Assignment", "Path Planning", "Path Smoothing and Trajectory Design". The most important points and a brief algorithm for each step is presented in this paper. Finally the method is applied to special case and the results presented. ©2008 IEEE
Planning And Scheduling Operating Rooms by Using Modified Block Scheduling Strategy with Considering the Surgical Team and post- Operative Units Constraints
, M.Sc. Thesis Sharif University of Technology ; Salmasi, Naser (Supervisor)
Abstract
provide about 67% of a hospital’s profit. Hospital managers are interested in decreasing the costs as well as increasing the customers’ satisfaction level. In this Thesis, four Mixed- Integer Programming models for planning and scheduling operating rooms are proposed. In the main, the problem is presented in two phases. In The first phase, model assigns the date and the room to each surgical and in second phase the model determines the sequencing of the assigned operation cases. The effects of using three different scheduling strategies (Block and Open and modified block) for assigning operating rooms to surgeons on the planning of surgical cases is studied. Then we proposed one phase model...
Relativistic Magnetohydrodynamics of a Spinful and Vortical Fluid: Entropy Current Analysis and Transport Coefficients
, M.Sc. Thesis Sharif University of Technology ; Sadooghi, Neda (Supervisor) ; Kiamari, Motahareh (Co-Supervisor)
Abstract
Fluid Mechanics can be considered as an effective method for studying many-body effects in classical and quantum systems. In recent years, relativistic hydrodynamics has found different applications in different branches of physics. One of these applications is the quantitative description of the experimental behavior of relativistic heavy-ion collisions. More specifically, studying fluid mechanics in the presence of magnetic fields (magnetohydrodynamics) and vorticity is of great importance in heavy-ion collision experiments. In this framework, on the one hand, the interaction between spin and magnetic field, and on the other hand, the interaction between spin and angular momentum of the...
Supercritical Carbon Dioxide Extraction of Catechins from Green Tea Leaves
, M.Sc. Thesis Sharif University of Technology ; Goodarznia, Iraj (Supervisor)
Abstract
Green tea has been receiving significant attention in recent years due to its high content of catechins; Epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and especially epigallocatechin gallate (EGCG). As powerful antioxidants, these compounds are believed to have several health benefits. In this study, we used supercritical CO2 with ethanol as co-solvent to extract catechin derivatives from green tea and we investigated the effects of experiment parameters on the extraction. Experiments, designed according to Taguchi algorithm, were conducted with green tea particles of four average diameters of 1500, 855, 605 and 427.5 µm, in an interval of 35- 55 ̊C for temperature and...
Design of Wired/Wireless Hybrid 3D NoC for Radio Components and 3D Digital Structure Compliance
, M.Sc. Thesis Sharif University of Technology ; Hessabi, Shaahin (Supervisor)
Abstract
According to recent advancements in digital circuit technology and new constraints for digital systems, scholars have researched to find a replacement for traditional copper links that is used to connect the embedded processing elements in a chip. Optic NoCs and wireless NoCs are two promising solutions to overcome challenges in traditional NoCs.
In this thesis, an innovative 3D NoC architecture is proposed which consists of four 2D mesh-based networks and they are connected via four wireless sub-networks as backbones. It is estimated that, the proposed architecture shrinks the power consumption at least 35 percent relatively due to the gate-level simulations. Thus, a better scaling and...
In this thesis, an innovative 3D NoC architecture is proposed which consists of four 2D mesh-based networks and they are connected via four wireless sub-networks as backbones. It is estimated that, the proposed architecture shrinks the power consumption at least 35 percent relatively due to the gate-level simulations. Thus, a better scaling and...
Temperature gradient and wind profile effects on heavy gas dispersion in build up area
, Article Journal of Applied Sciences Research ; Volume 6, Issue 12 , 2010 , Pages 6010-6020 ; 1816157X (ISSN) ; Shahraki, F ; Rashtchian, D ; Behzadmehr, A ; Sharif University of Technology
2010
Abstract
Dispersion of heavy gases is considered to be more hazardous than the passive ones. This is because it takes place more slowly. In this paper, based on the extensive experimental work of Hanna and Chang, the CFD model (Ansys-CFX) was tested compared with Kit Fox experiments. In order to accomplish this validation, the multiphase approach was employed as a new method in this area. In addition, the temperature gradient effects were investigated. The survey of wind speed was done taking factors such as time, height and direction into the consideration. To reduce the number of elements in computational domain, a combination of 2D and 3D geometries were utilized. Results showed that the wind...
Temperature gradient and wind profile effects on heavy gas dispersion in build up area
, Article Australian Journal of Basic and Applied Sciences ; Volume 4, Issue 12 , 2010 , Pages 6010-6020 ; 19918178 (ISSN) ; Shahraki, F ; Rashtchian, D ; Behzadmehr, A ; Sharif University of Technology
2010
Abstract
Dispersion of heavy gases is considered to be more hazardous than the passive ones. This is because it takes place more slowly. In this paper, based on the extensive experimental work of Hanna and Chang, the CFD model (Ansys-CFX) was tested compared with Kit Fox experiments. In order to accomplish this validation, the multiphase approach was employed as a new method in this area. In addition, the temperature gradient effects were investigated. The survey of wind speed was done taking factors such as time, height and direction into the consideration. To reduce the number of elements in computational domain, a combination of 2D and 3D geometries were utilized. Results showed that the wind...
SHTV, as a technique for core calculation using spatial homogenization and temperature variation
, Article Annals of Nuclear Energy ; Volume 37, Issue 9 , 2010 , Pages 1129-1138 ; 03064549 (ISSN) ; Zahedinejad, E ; Kashi, S ; Davilu, H ; Sharif University of Technology
2010
Abstract
The accuracy of static neutronic parameters in the nuclear reactors depends upon the determination of group constants of the diffusion equation in the desired geometry. Although several methods have been proposed for calculating these parameters, there is still the need for more reliable methods. In this paper a powerful and innovative method based on Spatial Homogenization and Temperature Variation (SHTV) of physical properties of a WWER-1000 nuclear reactor core for calculating the relative power distribution of Fuel Assemblies (FA) and the hot fuel rod, is presented. The method is based on replacing the heterogeneous lattices of materials with different properties by an equivalent...
Organic halides and nanocone plastic structures enhance the energy conversion efficiency and self-cleaning ability of colloidal quantum dot photovoltaic devices
, Article Journal of Physical Chemistry C ; Volume 121, Issue 18 , 2017 , Pages 9757-9765 ; 19327447 (ISSN) ; Simchi, A ; Tavakoli, R ; Fan, Z ; Sharif University of Technology
American Chemical Society
2017
Abstract
This paper presents solid-state ligand exchange of spin-coated colloidal lead sulfide quantum dot (PbS QD) films by methylammonium iodide (MAI) and integration of them in depleted heterojunction solar (DHS) devices having an antireflecting (AR) nanocone plastic structure. Time-resolved photoluminescence measurements determine a shorter lifetime of the charge carries on a semiconductor (TiO2) electron transfer layer for the MAI-passivated QD films as compared with those with long-chain aliphatic or short thiol ligands. Consequently, the DHS device yields improved power conversion efficiency (>125%) relative to oleic-acid-passivated PbS QD films. Using anodized aluminum oxide templates, an...
Surface engineering of TiO2 ETL for highly efficient and hysteresis-less planar perovskite solar cell (21.4%) with enhanced open-circuit voltage and stability
, Article Advanced Energy Materials ; Volume 8, Issue 23 , 2018 ; 16146832 (ISSN) ; Yadav, P ; Tavakoli, R ; Kong, J ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high-performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO2 (a-SnO2) between the TiO2 ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double-layer structure of TiO2 compact layer (c-TiO2) and a-SnO2 ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a-SnO2/c-TiO2 ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c-TiO2 based device....
Efficient, hysteresis-free, and flexible inverted perovskite solar cells using all-vacuum processing.Efficient, hysteresis-free, and flexible inverted perovskite solar cells using all-vacuum processing
, Article Solar RRL ; 2020 ; Yadav, P ; Prochowicz, D ; Tavakoli, R ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
The fabrication of efficient perovskite solar cells (PSCs) using all-vacuum processing is still challenging due to the limitations in the vacuum deposition of the hole transporting layer (HTL). Herein, inverted PSCs using copper (II) phthalocyanine (CuPC) as an ideal alternative HTL for vacuum processing are fabricated. After proper optimization, a PSC with a power conversion efficiency (PCE) of 20.3% is achieved, which is much better than the PCEs (16.8%) of devices with solution-based CuPC. As it takes a long time to dissolve CuPC in the solution-based device, the evaporation approach has better advantage in terms of fast processing. In addition, the device with the evaporated CuPC HTL...
Efficient perovskite solar cells based on Cdse/Zns quantum dots electron transporting layer with superior UV stability
, Article Physica Status Solidi - Rapid Research Letters ; Volume 14, Issue 6 , 2020 ; Prochowicz, D ; Yadav, P ; Tavakoli, R ; Sharif University of Technology
Wiley-VCH Verlag
2020
Abstract
Stability is the main challenge in the field of perovskite solar cells (PSCs). Finding new strategies is required to protect the PSCs from deteriorating agents such as humidity, heating, and illumination. Herein, a new electron transporting layer (ETL), i.e., CdSe/ZnS quantum dots (QDs), is proposed for the fabrication of efficient and stable PSCs. CdSe/ZnS QDs layer not only works as an ETL but also has downshifting property, which can improve both efficiency and stability of the PSCs. Using CdSe/ZnS QDs ETL with green emission, a PSC with maximum power conversion efficiency (PCE) of 18% is achieved. More importantly, the device shows great UV stability, much better than the device with...
Using machine learning to predict mortality for covid-19 patients on day 0 in the ICU
, Article Frontiers in Digital Health ; Volume 3 , 2022 ; 2673253X (ISSN) ; Asgary, A ; Tavakoli, N ; Zali, A ; Setareh, S ; Esmaily, H ; Jamaldini, S. H ; Daaee, A ; Babajani, A ; Sendani Kashi, M. A ; Jamshidi, M ; Jamal Rahi, S ; Mansouri, N ; Sharif University of Technology
Frontiers Media S.A
2022
Abstract
Rationale: Given the expanding number of COVID-19 cases and the potential for new waves of infection, there is an urgent need for early prediction of the severity of the disease in intensive care unit (ICU) patients to optimize treatment strategies. Objectives: Early prediction of mortality using machine learning based on typical laboratory results and clinical data registered on the day of ICU admission. Methods: We retrospectively studied 797 patients diagnosed with COVID-19 in Iran and the United Kingdom (U.K.). To find parameters with the highest predictive values, Kolmogorov-Smirnov and Pearson chi-squared tests were used. Several machine learning algorithms, including Random Forest...
Room temperature selective sensing of aligned Ni nanowires using impedance spectroscopy
, Article Materials Research Express ; Volume 7, Issue 2 , 24 February , 2020 ; Fardindoost, S ; Iraji Zad, A ; Almasi Kashi, M ; Sharif University of Technology
Institute of Physics Publishing
2020
Abstract
Room temperature gas sensing behavior of arrayed one-dimensional (1D) nickel nanowires (Ni NWs) are investigated using impedance spectroscopy. Ni nanowires synthesized via electrochemical deposition method based on anodic aluminum oxide (AAO) templates. Their structural characterization verified by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analysis. Impedance spectroscopy as an essential technique utilized to understand the mechanism of gas interaction with the wires through the changes in their electronic behavior. Bode and Nyquist plots with the real and imaginary impedances are plotted versus frequency range of 500 Hz...
Causes of Differences Between the Design and Implementation from the Quality Point of View in the Private Sector in Tehran, and Finding Solutions for Reducing or Eliminating this Problem
, M.Sc. Thesis Sharif University of Technology ; Mortaheb, Mohammad Mehdi (Supervisor) ; Ghaemian, Mohsen (Supervisor)
Abstract
In a macro view point, it can be said that housing demand in recent years is making the construction industry one of the main sectors of Iran’s economy. On the other hand, analysis of seismic risk in the country with regard to the geological conditions, the faults, and the seismic records of mega city of Tehran is depicting the delicate location of the Iranian capital. This city is selected as a case study in this thesis that has a high probability for the event; where this event has also been classified as a devastating earthquake ever. Due to the involvement of private sector in construction industry, the need for establishing a system of strict control on quality of construction of the...
Multimaterial topology optimization by volume constrained Allen-Cahn system and regularized projected steepest descent method
, Article Computer Methods in Applied Mechanics and Engineering ; Vol. 276 , 2014 , pp. 534-565 ; ISSN: 00457825 ; Sharif University of Technology
2014
Abstract
A new computational algorithm is introduced in the present study to solve multimaterial topology optimization problems. It is based on the penalization of the objective functional by the multiphase volume constrained Ginzburg-Landau energy functional. The update procedure is based on the gradient flow of the objective functional by a fractional step projected steepest descent method. In the first step, the new design is found based on the projected steepest descent method to ensure the reduction in the objective functional, simultaneously satisfying the control constraints. In the second step, regularization step, an H1 regularity of the solution is ensured while keeping the feasibility of...
On the prediction of shrinkage defects by thermal criterion functions
, Article International Journal of Advanced Manufacturing Technology ; Vol. 74, issue. 1-4 , Jun , 2014 , p. 569-579 ; Sharif University of Technology
2014
Abstract
The goal of the present study is to predict the formation of solidification induced defects in castings by thermal criteria functions. In a criterion function method, the heat transfer equation is firstly solved, and then the susceptibility of defect formation at every point in the casting is predicted by computing a local function, criterion function, using results of the thermal analysis. In the first part of the paper, some famous criteria functions, in particular, the Pellini and Niyama criteria, are analyzed and their shortcomings are discussed in details. Then, a new criterion function is suggested to decrease the shape-dependency issue of the former criteria. The feasibility of the...
Computationally efficient approach for the minimization of volume constrained vector-valued Ginzburg-Landau energy functional
, Article Journal of Computational Physics ; Volume 295 , August , 2015 , Pages 355-378 ; 00219991 (ISSN) ; Sharif University of Technology
Academic Press Inc
2015
Abstract
The minimization of volume constrained vector-valued Ginzburg-Landau energy functional is considered in the present study. It has many applications in computational science and engineering, like the conservative phase separation in multiphase systems (such as the spinodal decomposition), phase coarsening in multiphase systems, color image segmentation and optimal space partitioning. A computationally efficient algorithm is presented to solve the space discretized form of the original optimization problem. The algorithm is based on the constrained nonmonotone L2 gradient flow of Ginzburg-Landau functional followed by a regularization step, which is resulted from the Tikhonov regularization...
Unconditionally energy stable time stepping scheme for Cahn-Morral equation: Application to multi-component spinodal decomposition and optimal space tiling
, Article Journal of Computational Physics ; Volume 304 , 2016 , Pages 441-464 ; 00219991 (ISSN) ; Sharif University of Technology
Academic Press Inc
2016
Abstract
An unconditionally energy stable time stepping scheme is introduced to solve Cahn-Morral-like equations in the present study. It is constructed based on the combination of David Eyre's time stepping scheme and Schur complement approach. Although the presented method is general and independent of the choice of homogeneous free energy density function term, logarithmic and polynomial energy functions are specifically considered in this paper. The method is applied to study the spinodal decomposition in multi-component systems and optimal space tiling problems. A penalization strategy is developed, in the case of later problem, to avoid trivial solutions. Extensive numerical experiments...
Optimal design of multiphase composites under elastodynamic loading
, Article Computer Methods in Applied Mechanics and Engineering ; Volume 300 , 2016 , Pages 265-293 ; 00457825 (ISSN) ; Sharif University of Technology
Elsevier
2016
Abstract
An algorithm is proposed to optimize the performance of multiphase structures (composites) under elastodynamic loading conditions. The goal is to determine the distribution of material in the structure such that the time-averaged total stored energy of structure is minimized. A penalization strategy is suggested to avoid the checkerboard instability, simultaneously to generate near 0-1 topologies. As a result of this strategy, the solutions of presented algorithm are sufficiently smooth and possess the regularity of H1 function space. A simple method for the continuum adjoint sensitivity analysis of the corresponding PDE-constrained optimization problem is presented. It is general and can be...