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How particle shape affects the flow through granular materials
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 85, Issue 3 , 2012 ; 15393755 (ISSN) ; Ahmadi, M. M ; Mohammadi, S
2012
Abstract
Flow through the pores of granular materials has many instances in practice. Therefore, it is interesting to realize how some parameters, such as the shape of the particles affect the passing flow. Following the recent mathematical theory proposed by the authors, this paper deals with the issue of how tortuosity and permeability are influenced by the particle shape. Comparison of the results with the experimental data reveals the competency of the theory in predicting the impact of particle geometry
Some Applications of Graph Theory Inarchitectural Design
, M.Sc. Thesis Sharif University of Technology ; Mahmoodian, Ebadollah (Supervisor)
Abstract
One of the fields, in which graph theory and computer science have been appleid,is architectural design. Some of these applications are presented in this thesis. This thesis has two parts, the first part peresents a systematic pathway for design of a floor plan when given the list of cells, the required dimensions of each cell and the matrix of required adjacencies between the cells. (Based on the article by Hashimshony(1988)) The second part is about the application of Evolutionary Algorithm (EA) in ar-chitucture. The architectural layout design problems, which is concerned with the finding of the best adjacencies between functional spaces among many possible ones under given constraints,...
Tracking Consumers Throughout Their Purchase Journey: Using Deep Learning Methods
, M.Sc. Thesis Sharif University of Technology ; 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...
The Role of Oil Price Shocks in Bussiness Cycles of an Oil-Exporting Country: Facts from Iran with a General Equillibrium Approach
, M.Sc. Thesis Sharif University of Technology ; Madanizadeh, Ali (Supervisor)
Abstract
In this research, we develop a Real Business Cycle model for Iran, as Small Open Economy. In this model, which is designed to measure the role of oil price shocks in Iran’s business cycles, the positive oil price shocks, as well as increasing the revenue of exporting oil, raises the price of oil-based tradable goods. Additionally, it causes the fiscal policy variables (taxes and government expenditures) to change. Also the productivity of this economy is fluctuated by oil price fluctuations. The model is estimated via Impulse Response Function Matching method using a SVAR model as the auxiliary model. The results from the theoretical model show that near 50 percent of non-oil GDP cycles and...
ChemInform abstract: microwave-assisted rapid ketalization/acetalization of aromatic aldehydes and ketones in aqueous media [electronic resource]
, Article Journal of Chemical Research ; September 1999, Volume -, Number 9; Page(s) 562 to 563 ; Mirjalili, Bibi Fatemeh ; Sharif University of Technology
Abstract
Aromatic aldehydes and ketones are readily acetalized or ketalized under microwave irradiation in the presence of water as a solvent
Synthesis and characterization of poly(methacrylates) containing spiroacetal and norbornene moieties in side chain [electronic resource]
, Article Journal of Applied Polymer Science ; Volume 77, Issue 1, pages 30–38, 5 July 2000 ; Mirjalili, Bibi Fatemeh ; Sharif University of Technology
Abstract
A four-step synthetic strategy was applied to achieve novel methacrylic monomers. 5-Norbornene-2,2-dimethanol was prepared from a Diels–Alder reaction of cyclopentadiene and acrolein, followed by the treatment of the adduct with an HCHO/KOH/MeOH solution. The resulting 1,3-diol (1) was then acetalized with different aromatic aldehydes having OH groups on the ring to produce four spiroacetal derivatives. The reaction of methacryloyl chloride with the phenolic derivatives led to four new methacrylic monomers that were identified spectrochemically (mass, FTIR, 1H-NMR, and 13C-NMR spectroscopy). Free radical solution polymerization was used to prepare novel spiroacetal–norbornene containing...
Prediction of DNA/RNA Sequence Binding Site to Protein with the Ability to Implement on GPU
, M.Sc. Thesis Sharif University of Technology ; Koohi, Sommaye (Supervisor)
Abstract
Based on the importance of DNA/RNA binding proteins in different cellular processes, finding binding sites of them play crucial role in many applications, like designing drug/vaccine, designing protein, and cancer control. Many studies target this issue and try to improve the prediction accuracy with three strategies: complex neural-network structures, various types of inputs, and ML methods to extract input features. But due to the growing volume of sequences, these methods face serious processing challenges. So, this paper presents KDeep, based on CNN-LSTM and the primary form of DNA/RNA sequences as input. As the key feature improving the prediction accuracy, we propose a new encoding...
Cloning and Production of the Flavin Reductase Enzyme in Order to Perform Organic Reaction and Synthesis of Cation Exchange Column for Protein Purification
, M.Sc. Thesis Sharif University of Technology ; Kalhor, Hamid Reza (Supervisor)
Abstract
The reductase enzymes perform an important function in the cell. These enzymes are usually coupled with other enzymes and participate in reactions such as halogenation, reduction of alkene, and carboxylic acids. These reactions are carried out by reproducing cofactors such as FADH2 and NAD+; however, there is no evidence that this enzyme alone can perform an organic reaction. In this work, we aim to examine whether recombinant flavin reductase can carry out organic reactions. In order to amplify the flavin reductase enzyme gene from the E. coli genome by PCR (Polymerase Chain Reaction) method, two synthetic primers were designed; The forward primer of the gene contained a cleavage site for...
Energy-efficient relay selection and power allocation for multi-source multicast network-coded D2D communications
, Article AEU - International Journal of Electronics and Communications ; Volume 128 , 2021 ; 14348411 (ISSN) ; Kalbkhani, H ; Shayesteh, M. G ; Sharif University of Technology
Elsevier GmbH
2021
Abstract
Device-to-device (D2D) communication improves spectrum efficiency (SE) and increases system capacity. Heterogeneous networks comprise macrocell and several small cells, such as picocells and femtocells, where femtocells are more efficient. In cooperative communications, one or several additional nodes help to send data from source to destination to improve the quality of service (QoS). Network coding (NC) in cooperative networks can extend data rate and coverage area of D2D communication. The purpose of this article is to minimize power consumption of transmitting nodes during network-coded cooperative D2D transmission to reduce the interference on co-channel transmissions. In this study, we...
Developing and enhancing promiscuous activity for NAD(P)H-dependent flavin reductase via elimination of cofactor
, Article Heliyon ; Volume 9, Issue 9 , 2023 ; 24058440 (ISSN) ; Kalhor, H. R ; Hayati, F ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
Promiscuous enzymes have shown their synthetic abilities in generating various organic compounds with high selectively and efficiency under mild conditions. Therefore, the design and development of conditions to raise promiscuity to the enzymes have been under the spotlight in recent years. Flavin reductase, that reduces flavins by using NADH as a cofactor, has not been studied in promiscuous reactions. In the present study, it was aimed to develop a catalytic promiscuous activity in the recombinant E. coli flavin reductase by removing its cofactor. The flavin reductase demonstrated a promiscuous activity for Knoevenagel condensation and Michael addition reactions individually. The...
Optimization Models for Financial Portfolio Problem
, M.Sc. Thesis Sharif University of Technology ; Mahdavi Amiri, Nezameddin (Supervisor)
Abstract
In financial portfolio problem, optimization models with uncertainty has been considered. The multi-stage stochastic programming methodology has been used as a solution method for these problems. In this study, we use multi-stage programming with uncertainity to evaluate the asset allocation problem. Some general models have been introduced for problem solving. Non-anticipativity and parent-child models are implemented and solved by both simplex and interior-point methods and the results are compared. The results show the parent-child model to have a better performance. Also, the interior-point method appears to need less computing time than the simplex method
Cross-Lingual Speaker Adaptation for Statistical Parametric Speech Synthesis
, M.Sc. Thesis Sharif University of Technology ; Sameti, Hossein (Supervisor)
Abstract
Speech synthesis and its applications have been very attractive recently. The main purpose of this technique is to produce a speech signal with natural characteristics of human speech like prosody and emotion. Among all existing methods for speech synthesis, statistical parametric speech synthesis methods are more promising because ofhigher flexibility in comparison to other methods. One of the applications of speech synthesis is speech to speech translation. In these systems, the generated voice in target language should have the same characteristics as the input voice in source language. The main purpose of this research is to review and evaluate the cross lingual speaker adaptation...
Hydroelastic Analysis of Surface Piercing Propeller
, M.Sc. Thesis Sharif University of Technology ; Seif, Mohamad Saeed (Supervisor)
Abstract
Surface piercing propellers are particular type of supercavitating propellers that are commonly used for High-speed vessels. Most studies on this type of propellers has been investigating the hydrodynamic forces. But in recent years with increase in SPPs diameter used in vessels, structural analysis of this type of propellers is considered. For this purpose, studies on the stresses exerted on the propeller structures under load is done with the help of Hydro elastic methods. In this type of analysis, structura of propeller is intended to be flexible and Displacements under pressure checked and Tensions resulting from it are studied.
The present Thesis using ANSYS software to analyze a...
The present Thesis using ANSYS software to analyze a...
Data-Driven Pricing Based on Demand Prediction Using Machine Learning Methods
, M.Sc. Thesis Sharif University of Technology ; Sedghi, Nafiseh (Supervisor)
Abstract
Pricing plays an important and essential role in the profit and income of companies. The importance of pricing is not only related to its role in the company's profitability, but it also changes the customer's understanding and loyalty towards the company and can create the company's reputation or destroy it. Determining the right price will increase product sales and increase customer loyalty and create a competitive advantage for the company. One of the most important and influential variables in product pricing is the amount of demand. The main challenge of companies for product pricing is the uncertainty in their demand. In order to deal with this problem, data-driven pricing is used....
Design of Low-Power Zero Temperature Coefficient (ZTC) CMOS Oscillators
, M.Sc. Thesis Sharif University of Technology ; Akbar, Fatemeh (Supervisor)
Abstract
The increasing demand for autonomous vehicles and reliable communication protocols and hardware interfaces, such as CAN bus and USB, underscores the necessity for stable clock sources that maintain a low temperature coefficient (TC) over wide temperature ranges. This demand is particularly emphasized in applications such as wearables, network sensors, downhole devices, WSNs, and IoT, where long-lasting battery life and frequency-stable clock sources over a broad temperature range (e.g. -20 °C to 100 °C) are crucial. Traditionally, variations in frequency caused by temperature have been mitigated by employing off-chip components like crystals or ceramic based oscillators, but this approach...
Design of Low Power Harmonic Rejection Mixer for Wideband Application
, M.Sc. Thesis Sharif University of Technology ; Akbar, Fatemeh (Supervisor)
Abstract
The increasing demand for communication bandwidth and limited spectrum availability have heightened the complexity of radio front-end circuits in IoT applications. Achieving spectral efficiency is a key challenge, particularly for IoT devices operating at specific frequency bands such as 315 MHz, 433 MHz, 868 MHz, and 915 MHz.Due to the limited linearity of the transmit path, harmonic distortion components, known as counter intermodulation (CIM) products, are generated. These CIM products can directly fall into the receiver (RX) band or enter it via cross-modulation, thereby degrading the frequency division performance. Additionally, CIM products can interfere with protected bands, violating...
Analytical derivation of tortuosity and permeability of monosized spheres: A volume averaging approach
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 2 , February , 2011 ; 15393755 (ISSN) ; Mohammadi, S ; Hayati, A. N ; Sharif University of Technology
2011
Abstract
Macroscopic properties of granular materials are important in modeling a variety of flow and transport phenomena in many fields of science. Determination of these parameters has always been an issue among both researchers and engineers, mainly in view of tortuosity and permeability. This paper presents analytical functions for the tortuosity and permeability of monosized sphere arrays based on a volume averaging approach and eliminates some ambiguities by modification of the original representative elementary volume model. Veracity of the proposed formulations has been illustrated through comparisons with the latest available results on the subject. Good agreement is found
Analytical Solution for Isothermal Flow in a Shock Tube Containing Rigid Granular Material
, Article Transport in Porous Media ; Volume 93, Issue 1 , 2012 , Pages 13-27 ; 01693913 (ISSN) ; Ahmadi, M. M ; Mohammadi, S ; Sharif University of Technology
2012
Abstract
Analytical solution of shock wave propagation in pure gas in a shock tube is usually addressed in gas dynamics. However, such a solution for granular media is complex due to the inclusion of parameters relating to particles configuration within the medium, which affect the balance equations. In this article, an analytical solution for isothermal shock wave propagation in an isotropic homogenous rigid granular material is presented, and a closed-form solution is obtained for the case of weak shock waves. Fluid mass and momentum equations are first written in wave and (mathematical) non-conservation forms. Afterwards by redefining the sound speed of the gas flowing inside the pores, an...
Silica chloride/wet SiO2 as a novel heterogeneous system for the deprotection of acetals under mild conditions [electronic resource]
, Article Phosphorus, Sulfur, and Silicon and the Related Elements ; Volume 178:2667-2670, Issue 12, 2003 ; Pourjavadi, Ali ; Zolfigol, Mohammad Ali ; Bamoniri, Abdolhamid
Abstract
A combination of silica chloride and wet SiO2 was used as an effective deacetalizating agent for the conversion of acetals to their corresponding carbonyl derivatives under mild and heterogeneous condition
Simulation of a 10000 bbl/day G.T.L. plant
, Article 18th International Congress of Chemical and Process Engineering, CHISA 2008, Prague, 24 August 2008 through 28 August 2008 ; 2008 ; Gholamtamimi, M ; Hayati, R ; Sobati, M. A ; Sharif University of Technology
2008
Abstract
Gas-to-Liquid (GTL) is a multi-staged process in which natural gas is converted to liquid fuels. The stages of GTL process are discussed. A GTL plant with 10,000 bpd capacity and have similar specifications with the SASOL process was simulated using the Aspen-Plus software and the simulation results were compared with the SASOL process data. This is an abstract of a paper presented at the 18th International Congress of Chemical and Process Engineering (Prague, Czech Republic 8/24-28/2008)