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    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 Pourdjavadi, A. (Ali) ; 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 Pourdjavadi, A. (Ali) ; 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 Fatemeh Tabatabaei (Author) ; 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... 

    Studying wave optics in the light curves of exoplanet microlensing

    , Article Monthly Notices of the Royal Astronomical Society ; Volume 431, Issue 2 , 2013 , Pages 1264-1274 ; 00358711 (ISSN) Mehrabi, A ; Rahvar, S ; Sharif University of Technology
    2013
    Abstract
    We study the wave optics features of gravitational microlensing by a binary lens composed of a planet and a parent star. In this system, the source star near the caustic line produces a pair of images in which they can play the role of secondary sources for the observer. This optical system is similar to the Young double-slit experiment. The coherent wavefronts from a source on the lens plane can form a diffraction pattern on the observer plane. This diffraction pattern has two modes from the close- and wide-pair images. From the observational point of view, we study the possibility of detecting this effect through the Square Kilometre Array (SKA) project in the resonance and... 

    Investigation of Fracture Toughness of Epoxy Resins by Addition of CNT and Rubber Microparticles

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Fatemeh (Author) ; Bagheri, Reza (Supervisor)
    Abstract
    Epoxy resins are relatively brittle and have low resistance to crack propagation. It is common to add rubber particles to improve crack resistance in epoxies, although these particles may deteriorate the strength of the matrix. Different nanomaterials are used to overcome the inherent brittleness of epoxies and to keep the mechanical properties. Among them, carbon nanotubes has been attracted many attentions. Fractue behavior and mechanical properties of two kind of novel nanocomposites, i.e, epoxy/carbon nanotube and epoxy/rubber/carbon nanotube are investigated in current study. Electron microscopy investigations were done to assure the CNTs distribution and fracture mechanisms as well.... 

    Performance Evaluation of Machine Learning and Statistical Approaches for Wildfire Modeling and Prediction

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Majid (Author) ; Moghim, Sanaz (Supervisor)
    Abstract
    Wildfires are complex phenomena with many indeterminate and highly unpredictable driving factors that have remained unresolved. During the last decade, machine learning methods have successfully excelled in wildfire prediction as an alternative to traditional field research methods by elucidating the relationship between historical wildfire events and various important variables. The main purpose of this research is to evaluate the random forest machine learning approach and the logistic regression statistical approach to prepare a wildfire susceptibility map using data related to historical wildfires and effective variables in the Okanogan region in Washington province of the United States... 

    Numerical Fatigue Investigation of Composites Honeycomb Structures Using Four Point Bending Loading Specimen

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Hadi (Author) ; Adibnazari, Saeed (Supervisor)
    Abstract
    In this thesis, design and analyses of honeycomb structures are investigated. Primary goal is to develop an equivalent orthotropic material model that is a good substitute for the actual honeycomb core. By replacing the actual honeycomb structure with the orthotropic model, during the finite element analyses, substantial advantages can be obtained with regard to ease of modeling and model modification, solution time and hardware resources . To figure out the best equivalent model among the approximate analytical models that can be found in the literature, a comparison is made. First sandwich beams with four different honeycomb cores are modeled in detail and these are accepted as reference... 

    Cooperative Data Aggregation in Wireless Sensor Networks

    , M.Sc. Thesis Sharif University of Technology Mehrabi Koushki, Masoud (Author) ; Movaghar, Ali (Supervisor)
    Abstract
    Minimizing energy consumption is the most important concern in wireless sensor networks (WSNs). Cooperative multiple-input multiple-output (MIMO) and data aggregation are two promising techniques to conserve energy in network nodes by coordinating their transmissions through cooperative communications along with eliminating the inherent redundancy of raw data for transmissions. In this thesis, with the goal of reducing energy consumption, we present a dynamic clustering framework for combined used of cooperative MIMO and data aggregation in cluster-based WSNs. We derive a new and more general energy model for computing energy consumption of cooperative data aggregation in wireless sensor... 

    Post-consumer recycled high density polyethylene/polypropylene blend with improved overall performance through modification by impact polypropylene copolymer: morphology, properties and fracture resistance

    , Article Polymer International ; Volume 70, Issue 12 , 2021 , Pages 1701-1716 ; 09598103 (ISSN) Mehrabi Mazidi, M ; Sharifi, H ; Sharif University of Technology
    John Wiley and Sons Ltd  2021
    Abstract
    The effect of an impact polypropylene copolymer (IPC) having excellent stiffness–toughness balance on the microstructure and properties of a blend comprising 80 wt% recycled high density polyethylene (rHDPE) and 20 wt% recycled isotactic polypropylene (rPP) was studied. Morphological observations revealed improved interfacial interactions, a finer dispersion state and a more homogeneous phase morphology upon IPC incorporation into the blend up to 20 wt%. Flexural modulus, flexural strength, tensile strength and tensile ductility were steadily increased with IPC loading, and exhibited 13%, 14%, 35% and 520% improvement at 20 wt% IPC. A monotonic rise in Izod impact energy, accompanied by a... 

    Cross-Lingual Speaker Adaptation for Statistical Parametric Speech Synthesis

    , M.Sc. Thesis Sharif University of Technology Saleh, Fatemeh Sadat (Author) ; 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 Fatemeh, Shahreki (Author) ; 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... 

    Design of Low-Power Zero Temperature Coefficient (ZTC) CMOS Oscillators

    , M.Sc. Thesis Sharif University of Technology Shahidani, Mohammad Aref (Author) ; 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... 

    Data-Driven Pricing Based on Demand Prediction Using Machine Learning Methods

    , M.Sc. Thesis Sharif University of Technology Khosroshahi, Fatemeh Zahra (Author) ; 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.... 

    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 Mirjalili, B. F. (BiBi Fatemeh) ; 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  

    Wave Optics Effects in Microlensing of a Binary Lenses

    , Ph.D. Dissertation Sharif University of Technology Mehrabi Rahmanpour, Ahmad (Author) ; Rahvar, Sohrab (Supervisor)
    Abstract
    In this thesis, we investigate two subjects in gravitational microlensing. In first part we study wave optics effect in light curve of a binary system. Gravitational lensing occurs when light deflects in a gravitational field. This deflection produces multi-images from real one. In microlensing regime, images can not be detected separately and gravitational lensing appears as magnifying source’s flux . Microlensing has been studied mostly in geometric optics regime. At larger wavelengths, mostly at radio wavelengths, we expect to see the effects of wave optics in microlensing. Stars at radio wave are faint and to detect them we need a powerful radio telescope. In the near future, SKA (Square... 

    Numerical Simulation of Magneto Mercury Reciprocating Micropump

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Ali (Author) ; Shafii, Mohammad Behshad (Supervisor)
    Abstract
    In this investigation Magneto Mercury Reciprocating Micrpump (MMRM) the combination of Magneto-Hydrodynamic and Reciprocating micropumps has been analyzed. To achieve the analytical and numerical solution of one-tank and three-tank MMRM, the momentum, continuity, volume fraction and magnetohydrodynamic equations have been presented. The dimensionless analytical solution of one-phase and two-phase three dimensional MHD flow in the condition of using constant current and potential electrical source, has been offered.
    The boundary between mercury and air has been tracked via VOF method in OpenFOAM software. VOF equation has been solved by explicit method with variable time step and maximum... 

    Development of a Conceptual Model for Heat Recovery from Exhaust Gases of Electric Arc Furnace

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Mohammad Reza (Author) ; Saboohi, Yadollah (Supervisor)
    Abstract
    Steel in Iran is mainly produced by EAFs. One of the most fundamental issues in the field of electric arc furnace is to foresight methods to reduce energy consumption and emissions. A model is presented in the present research work that avails itself to analysis of mass and energy recovery simultaneously. The proposed model includes three major elements: scrap pre-heating, sponge iron pre-heating and inert gases pre-heating. An important feature of this approach is to preheat sponge iron. Mathematical model for preheating scrap has been developed on the basis of CONSTEEL technology. Also the model for sponge iron and inert gases preheating has been formulated based on the literature review.... 

    Theoretical and Numerical Simulation of a Solar Collector for Direct Steam Generation

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Pouria (Author) ; Morad, Mohammad Reza (Supervisor)
    Abstract
    Direct steam generation (DSG) process using linear FRESNEL collectors has been developed widely in recent years and is one of the most promising solar technologies for thermal power generation, Industrial processes and domestic usage. In this process water as heat transfer fluid (HTF) is heated through a solar field. Continuous breakthroughs are being achieved on improvement of these collectors. A multi-phase CFD model is developed to calculate the wall temperature of linear Fresnel absorber tubes and fluid properties including temperature, velocity, and pressure. In order to design the collector field and identify the critical condition such as overheating of the absorber tubes, modeling of... 

    Design and Construction of a Single Axis Stable Platform Using the Model-Based Design Approach

    , M.Sc. Thesis Sharif University of Technology Mehrabi, Mohammad Hossein (Author) ; Nobahari, Hadi (Supervisor)
    Abstract
    The perpuse of this thesis is to design and fabricate a laboratory one degree of freedom stable platform under turbulences by model-based design method. To do this, different parts of the system were first modeled in the Solidworks software and then fabricated with various tools. With proper assembly of electronic and mechanical components, the original body of the system was created. Then, the controller motor with a stable platform which is attached to it was modeled and simulated in MATLAB software. Then, the parameters of the equations were calculated using standard identification tests and TCACS optimization algorithm. One of the challenges of this thesis is the malfunction of the... 

    Providing an Order-Inventory Planning Model using Heuristics or Meta Heuristics Algorithm (case study: khorasan Petrochemical Co.)

    , M.Sc. Thesis Sharif University of Technology Mehrabi Nasab, Mohammad (Author) ; Hajji, Alireza (Supervisor)
    Abstract
    Planning orders and inventory is one of the most important issues in the planning of petrochemical production. Considering the customization of this industry, orders planning includes a large part of it. Also, in order to reduce the great cost of inventory storage, planning to reduce inventory must be considered. In this regard, we intend to present a model with simultaneous consideration of orders and inventory planning in this research, the ability to decide on acceptance of orders and determine the level of production of products in conditions of uncertainty of demand with random trapezoidal demand in each period can be assumed. This model will practically play a key role in improving...