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    Experimental Study of Low Swirl Burners Interferences

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Mohammad (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    One of the problems associated with lean premixed combustion is their stability. Low swirl flame is a modern technology for reducing NOx emissions and increasing stability.In this thesis, first, the effect of geometric parameters on the flame stability was investigated. This study was carried out in high fuel and oxidizer mixture flow rate. Having find, the most stable burner, two other burners with the same geometrical parameters were built. Stability of these three burners were analyzed. Second, they were located in a ring together in three different relative positions. In each configuration stability and NOx emissions of the burners were determined.The study shows that NOx and CO... 

    Speech Activity Detection Using Deep Networks

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Sajad (Author) ; Sameti, Hossein (Supervisor)
    Abstract
    In this paper, we introduce a new dataset for SAD and evaluate certain common methods such as GMM, ANN, and RNN on it. We have collected our dataset in a semi-supervised approach, using subtitled movies, with a labeling accuracy of 95%. This semi-automatic method can help us collect huge amounts of labeled audio data with very high diversity in language, speaker, and channel. We model the problem of SAD as a classification task to two classes of speech and non-speech. When using GMM for this problem, we use two separate mixtures to model speech and non-speech. In the case of neural networks, we use a softmax layer at the end of the network, with two neurons which represent speech and... 

    Large eddy simulation of low swirl flames under external flow excitations

    , Article Flow, Turbulence and Combustion ; Volume 100, Issue 1 , 2018 , Pages 249-269 ; 13866184 (ISSN) Shahsavari, M ; Farshchi, M ; Sharif University of Technology
    Springer Netherlands  2018
    Abstract
    Low swirl flame characteristics under external flow excitations are numerically investigated using large eddy simulations with a dynamically thickened flame combustion model. A finite volume scheme on a Cartesian grid with a dynamic one equation eddy viscosity subgrid scale model is used for large eddy simulations. The excitations are imposed on inlet velocity profiles by a sinusoidal forcing function over a wide range of amplitudes and frequencies. Present investigation shows that although, the swirling motion of the low swirl flame is not intense enough to induce a recirculation zone in ensemble averaged results, external flow excitations increase the local swirl number upstream of the... 

    Low Swirl Flame Dynamic under Vortical Flow Disturbances

    , Ph.D. Dissertation Sharif University of Technology Shahsavari, Mohammad (Author) ; Farshchi, Mohammad (Supervisor)
    Abstract
    Lean premixed combustion is highly susceptible to thermoacoustic instabilities. Such instabilities are compounded in low swirl flames by the fact that low swirl flames are stabilized aerodynamically at a relatively considerable distance downstream of the burner rim, such stabilization mechanism makes the flame more prone to both vertical and acoustic perturbations. The main objective of the present thesis is to evaluate effects of acoustic and hydrodynamic perturbations on low swirl flame features. To such aim, first, low swirl flame characteristics and stabilization mechanism are studied using large eddy simulations along with thickened flame combustion model. The obtained results show that... 

    Dynamics and Heat transfer of Two-phase Non-Newtonian Fluids in Superhydrophobic Channels

    , M.Sc. Thesis Sharif University of Technology Shahsavari, Arghavan (Author) ; Moosavi, Ali (Supervisor)
    Abstract
    When the fluid passes through the microchannel, some energy is lost due to drag force and pressure drop. One of the methods used in the last few decades to optimize energy consumption is creating superhydrophobic surfaces in microchannels. These surfaces, with their features such as increasing the contact angle and reducing the contact angle hysteresis, can reduce energy loss, which is due to the presence of unevenness on the surface, and by trapping air and creating a two-phase flow, they reduce the drag force. On the other hand, the air trapped inside these irregularities will also affect the heat transfer of the passing fluid in the microchannel, which by creating resistance in the... 

    Greenhouse gas emission measurement and economic analysis of Iran natural gas fired power plants

    , Article Energy Policy ; Volume 60 , 2013 , Pages 200-207 ; 03014215 (ISSN) Shahsavari Alavijeh, H ; Kiyoumarsioskouei, A ; Asheri, M. H ; Naemi, S ; Shahsavari Alavije, H ; Basirat Tabrizi, H ; Sharif University of Technology
    2013
    Abstract
    This study attempts to examine the natural gas fired power plants in Iran. The required data from natural gas fired power plants were gathered during 2008. The characteristics of thirty two gas turbine power plants and twenty steam power plants have been measured. Their emission factor values were then compared with the standards of Energy Protection Agency, Euro Union and World Bank. Emission factors of gas turbine and steam power plants show that gas turbine power plants have a better performance than steam power plants. For economic analysis, fuel consumption and environmental damages caused by the emitted pollutants are considered as cost functions; and electricity sales revenue are... 

    Material Ordering in a Deterministic Time-Phased Demand Environment with All-Units Discount in Purchasing

    , Ph.D. Dissertation Sharif University of Technology Mirmohammadi, Hamid (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    More than 60% of sales account for materials, and so the roles and responsibilities of the material managers have been recognized as more important within a firm or in a large scale project than before. However, in many purchasing situations, different considerations conflict with one another. In these situations material planning plays an essential role in the total cost minimization process. Here, the optimal material ordering policy for an item in a deterministic time-phased demand environment with all-units discount in purchasing is considered. Based on proven properties of the optimal order policy, a tree search procedure is designed to construct sequences of orders in the optimal... 

    Design of Business Processes for a Company that Offers IT Products and Services

    , M.Sc. Thesis Sharif University of Technology Salehi, Javad (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    Small and medium companies generally start with a technical idea and usually without any specific strategy and mission . Commonly at this time short-term goals determine activities and current processes of company. As the time after time that the company grows it faces great problems because of the lack of strategy and long-term goals and also lack of correct definition of business processes. In this thesis with selecting one of these companies that provides products and services in information technology fields, after investigating current situation and problems we will redefine the mission and objectives with strategic approach. Then we offer a suitable business model that fits company... 

    Feasibility study of Foam Concrete production

    , M.Sc. Thesis Sharif University of Technology Koohestani, Mostafa (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    Foam concrete is a new covering layer that can be used for several purposes in civil constructions and because of its unique physical specifications, produces a light concrete in which is isolated against thermal conductivity ,with required strength and favorite quality.This cover is made of cement , sand ,water and foam(chemical substance that produces foam) . The foam is mixed with water in a special machine (mixer) with a high speed centrifugal rotation and produces very small stable bubbles called foam. While cement and sand are mixed in special mixer, makes a fluent concrete that can be used in place, metallic or plastic molds. After dehydration, in accordance with percentage of... 

    Optimization Shop Area in Construction Projrect

    , M.Sc. Thesis Sharif University of Technology Raissi, Asghar (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    Resource investment problem is one of problems in project scheduling which concerns with gaining minimum cost for accomplishing a project in a given time. Tardiness permitted with penalty cost makes this problem close to real world. This dissertation studied constraint of resources by restricted resources and tried to gain optimal level of restricted resource and middle resources start and finish time. This problem also permits tardiness with penalty cost. In construction projects, beside renewable and Non-renewable resources, there are workshops in which part of the work to carry out an activity, is done. These workshops include welding workshops and forming workshops in piping projects,... 

    Scheduling on Parallel Machines with Preemption and Transportation Delays using a Particle Swarm Optimization (PSO)-Based Algorithm

    , M.Sc. Thesis Sharif University of Technology Shams, Hesam (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    This research deals with the problem of scheduling independent preemptive jobs on identical parallel machines, to minimize the total completion time (makespan). The transportation of an interrupted job from a machine to another machine requires considering a constant transportation delay i.e., Pm|prmp(delay)| Cmax. This delay is called transportation delay. We propose a Mixed Integer Linear Programming formulation for the research problem in case of two machines i.e., P2|prmp(delay)| Cmax. Since the research problem is shown to be NP-hard, a particle swarm optimization (PSO) algorithm is applied to solve the problem approximately. Based on the frequency of using local search procedure, three... 

    A Project Portfolio Selection Method for Iranian Private Construction Companies

    , M.Sc. Thesis Sharif University of Technology Hamdieh, Hosna (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    The construction industry is one of the main industries in Iran, and plays a fundamental role in Iran’s economy, because construction has impact on most of other industries by its vast value chain. Selecting right sets of projects is considerably crucial for construction organizations to successfully achieve their competitive advantages and corporate strategies. Due to limited resources and dynamic changes in Iran’s construction business environment, this kind of selection is quite challenging for construction organizations. Beside’s over hundreds of selection tools, techniques, and complex selection frameworks were developed or recommended by academics and practitioners to smooth the... 

    Exact and Metaheuristic Solution of Multi-skilled Project Scheduling Problem Considering Learning and Forgetting Effects on the Performance of Project Members

    , M.Sc. Thesis Sharif University of Technology Mehmanchi, Erfan (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    The multi-mode resource-constrained project scheduling problem is one of the most complex and most widely used problems in the project scheduling knowledge area and operations research science. Recently, a new type of this problem which is called multi-skilled project scheduling problem has been introduced in the literature. The aim of MSPSP is to schedule the activities regarding the precedence relationships and multi-skilled human resource constraints in such a way that the need of each activity to a subset of skills should be met by the qualified employees. In this thesis, in addition to taking the constraints of the standard problem into account, we consider a state in which the... 

    Identify and Assessment of Project's Risks Based on PMBOK's Standard - Case Study: Construct an Aquaculture Site in Abadan

    , M.Sc. Thesis Sharif University of Technology Kamaei, Amin (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    Risk is an uncertain event or condition that, if it occurs, has a positive or negative effect on a project’s objectives. Identification and assessment of risk in a measurable way are so important for project managers to decide better. This thesis studies how to identify and assess the project’s risks in Fishery industry based on the Project management body of knowledge (PMBOK 2008) as a global standard. Constructing an aquaculture site in Abadan city has some risks which are identified in the first steps of the study and in the following steps these risks will be prioritized by the use of qualitative analysis and figured out which risks have major effects on projects objectives. In last step... 

    Optimization of Process Plant Layout and Pipe Routing

    , M.Sc. Thesis Sharif University of Technology Mehrizi, Rahil (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    Process plants such as refineries and petrochemical plants are complex facilities consisting of equipment, piping systems, instruments, electrical systems, computers, and control systems. Process units design is mostly based on designer`s experience and design general criteria and standards. Using mathematical methods to optimize the design may have an effective role in cost reduction and it would give the designer some general view in case that the exact design is not applicable.
    Optimization of Process units is described in this study. This optimization includes the exact location of each equipment, nozzle, pipe rack and also pipe route layouts. Mixed integer linear programming (MILP)... 

    Presentation of a Model and Solving the Problem of Project Portfolio Selection Based on Project Scheduling using Two-Level NSGAII

    , M.Sc. Thesis Sharif University of Technology Jafari, Hossein (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    This project aims to study a situation in which several projects must be selected. The decision makers should select a subset of these projects taking into account the limitation of resources and scheduling. Project selection models generally do not consider schedule of project activities as part of selection process. On the other hand, except the cases where only one project is under process in each period, prioritizing the selected projects is not optimal not considering their scheduling. Projects scheduling in project activities level may increase the complexity of decision making for portfolio selection and expand the area of search for selection of projects portfolio. Therefore, all the... 

    Designing an Algorithm for the Resource Investment Problem Considering Calendar

    , M.Sc. Thesis Sharif University of Technology Parvizi, Saeed (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    Project scheduling problems can be divided into different categories which one of the most important of them is resource investment problem. In this problem we are faced with a time limit for completion but resources are available unlimitedly and can be allocated to the project by specific cost. One of the most important constraints in real problems is the times that resources are available. In this research, resource investment problem considering calendar for resources has been investigated. Since resource investment problem is NP-Hard, after a brief overview of the different solutions, we used genetic algorithm to solve this problem. For this purpose, after determining chromosome... 

    Reflection Cryptanalysis of GOST Block Cipher

    , M.Sc. Thesis Sharif University of Technology Oraei, Hossein (Author) ; khazaei, Shahram (Supervisor)
    Abstract
    Block ciphers are the central tool in the design of security protocols. GOST is a block cipher that several attacks have been published on it during the past 20 years. One of them is the reflection attack that was first introduced in 2007. This attack utilizes similarities of some round functions of both encryption and decryption processes. In addition, there are approaches that combines techniques of the reflection attack and variants of the meet-in-the-middle attack. In this thesis, we study reflection-based attacks on GOST. We first describe the GOST block cipher and the reflection attack. Then, we review previous reflectionbased attacks such as reflection-meet-in-the-middle attack and... 

    Risk Assessment of Power Plant Projects with Fuzzy Approach (Case study: Shirkooh Yazd Combined Cycle Power Plant)

    , M.Sc. Thesis Sharif University of Technology Pourmohammadi, Sahar (Author) ; Shadrokh, Shahram (Supervisor)
    Abstract
    In this research, the risks of power plant projects are assessed with fuzzy approach. For this purpose, "Shirkooh Yazd combined cycle power plant" is chosen as the case study. First, the risks of power plant projects before the contract and during project execution are identified. Then these risks are categorized in a hierarchical breakdown structure. Subsequently, required information is collected from experienced professionals using questionnaires that used as the input data for risk qualitative analysis. In qualitative analysis, the risk probability and its impacts (containing time, cost and quality) are described by qualitative terms. After scaling them, the amount of each risk is... 

    Linear-Differential Cryptanalysis of Word-Reduced Variants of Cubehash

    , M.Sc. Thesis Sharif University of Technology Javid, Sahand (Author) ; Khazaei, Shahram (Supervisor)
    Abstract
    In this thesis, first we will have a brief review on hash functions and related concepts.Then, we will descibe the hash function, Cubehash, which is one of the competitors in the competition held by NIST for selecting SHA-3 standard. Next, we will describe an attack based on linearization of differential paths in hash functions and apply this attack on Cubehash. At the end, we will discuss the results of this attack on Cubehash