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mahmood-tohidi--shayan
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Total 130 records
Modeling and Solving the Multi-Player Competitive Location Problem in a Continuous Facility Layout
, M.Sc. Thesis Sharif University of Technology ; Eshghi, Kourosh (Supervisor)
Abstract
As time has passed, the cost of maintaining expert human resources has been increasing worldwide; as a result, factories and stakeholder has sought ways to exploit the expertise of their human resources as much as possible so they can reduce their costs and, of course, raise their profits. To achieve this, managers decided to assign their human resources to tasks that demands their expertise and knowledge and therefore provides added value for their companies; nevertheless, this decision needs proper alternatives to do routine and predetermined jobs as substitutions for expert human resources.As the technology and the science has been growing day by day, the use of robots has been extremely...
Aerodynamic Design of 100 kW Transonic Ducted Fan
, M.Sc. Thesis Sharif University of Technology ; Ghorbanian, Kaveh (Supervisor)
Abstract
The purpose of this research is the aerodynamic design of a 100 kW transonic ducted fan. Today, the aviation industry is moving towards the design of electric driven aircraft propulsion. Transonic ducted fans are one of the viable options that have been used in medium and heavy aircrafts due to their high specific power. In this research, the meanline model has been used for the initial design. By applying the design constraints, design limitations, design and functional parameters, the initial design point is found and then a sensitivity analysis is performed with respect to the effective design parameters to obtain the optimal design point. For the initial design of the transonic ducted...
Techno-Economic Comparison of Different Gas Turbine Inlet Cooling Techniques
, M.Sc. Thesis Sharif University of Technology ; Hakkaki Fard, Ali (Supervisor)
Abstract
Inlet air cooling is a simple and economical method to increase the power output of gas turbines. High-pressure fogging systems and mechanical chillers are two common methods. High water consumption, damage to compressor blades by water droplets, and inefficiency in humid climates are disadvantages of high-pressure fogging systems. Mechanical chillers have high electricity consumption and initial costs. In this research, an earth-to-air heat exchanger (EAHE) is introduced as a new method for inlet air cooling of gas turbines and is technically and economically compared with the two common methods in the long term in the climate of Tehran city. Temperature distribution in the ground is...
Design and Optimization of Carbon Capture System from Exhaust Gases in the Process Industries
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Seif, Shayan (Co-Supervisor)
Abstract
Carbon dioxide is one of the main geenhouse gases emitted from factories as well as transportation vehicles that adversely affect the atmosphere and cause global warming. Among the proposed solutions to reduce carbon dioxide in the atmosphere, carbon dioxide separation would be the most viable medium-term approach. However, the high cost of carbon dioxide separation prevents the development of carbon dioxide absorption technologies. Therefore, it seems that integrating separation and production processes is the most efficient way to save energy and reduce carbon emissions. This method decrease a high proportion of the energy consumption in upstream operations (carbon dioxide removal,...
Investigating Wind-Induced Currents in Sloped Aquatic Canopy Areas
, M.Sc. Thesis Sharif University of Technology ; Jamali, Mirmosadegh (Supervisor)
Abstract
Aquatic canopy zones play an important role in maintenance of ecosystems. These areas are ubiquitous near rivers, lakes, lagoons, estuaries and shore lines. Governing dynamical systems through these areas have direct influence on, how nutrients and other vital materials for living things disperse. Also, they can control the amount of dissolved oxygen within the body of water in these regions. Nowadays, investigating the effects of vegetation grabbed the attention of many scientists and is a very important burgeoning field. In this study, the effects of surface cooling which resulting from mild wind blow have been investigated. In fact, two type of different currents form when wind blows...
Influence of model simplifications and parameters on dynamic performance of grid connected fixed speed wind turbines
, Article 19th International Conference on Electrical Machines, ICEM 2010, 6 September 2010 through 8 September 2010, Rome ; 2010 ; 9781424441754 (ISBN) ; Rabiee, A ; Parniani, M ; Sharif University of Technology
2010
Abstract
With the rising penetration of wind power into electric power systems, more accurate and comprehensive studies are required to identify the interaction between wind farm(s) and power system. This requires accurate models of different types of wind turbine-generators. This paper describes modeling and small signal analysis of a grid connected fixed speed wind turbine generator (FSWTG). A complete model of FSWTG is derived and some reduced-order models are deduced. Eigenvalues and participation factors of the system for these models are calculated. Then, using the eigen analysis results, the models are compared and the simplifying assumptions which have been considered in the literatures are...
Antenna and pulse selection for colocated MIMO radar
, Article 51st Asilomar Conference on Signals, Systems and Computers, ACSSC 2017, 29 October 2017 through 1 November 2017 ; Volume 2017-October , 2018 , Pages 563-567 ; 9781538618233 (ISBN) ; Behroozi, H ; Leus, G ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Multiple input multiple output (MIMO) radar is known for its superiority over conventional radar due to its antenna and waveform diversity. However, the increased hardware cost (due to multiple transmitters and receivers), power consumption (due to multiple transmitters and pulses), and computational complexity (due to numerous pulses) form the drawbacks of MIMO radar. On one hand, a higher estimation accuracy is required, but on the other hand, a lower number of active antennas/pulses is desirable. Therefore, in this paper, by proposing a convex optimization approach for the general case of transmitter-receiver-pulse selection, we will minimize the total number of active antennas/pulses in...
Optimum Unit Size in Generation Expansion Planning Based on Reliability Criteria
,
M.Sc. Thesis
Sharif University of Technology
;
Fotuhi Firouzabad, Mahmud
(Supervisor)
Abstract
Increasing demand in power systems necessitates the Generation Expansion Planning (GEP) which is to determine the type, size, and location of new generating units in a planning horizon. The final solution of GEP is based on the minimum cost and/or optimum reliability taking into account various constraints such as capacity of units and lines, operating constraints, and budget restrictions. This paper presents a model based on scenarios for generation expansion planning and units retirement decision. The proposed model could be used by vertically integrated utilities as well as the ISOs in electricity markets to obtain generation expansion schemes. In this approach, uncertainty of units are...
Beamforming Through Array Thinning
, M.Sc. Thesis Sharif University of Technology ; Nayebi, Mohammad Mahdi (Supervisor)
Abstract
Modern communication and space systems such as satellite communication devices, radars, SAR and radio astronomy interferometers are realized with large antenna arrays since this kind of radiating systems are able to generate radiation patterns with high directivity and resolution. In such a framework, conventional arrays with uniform inter-element spacing could be not satisfactory in terms of costs and dimensions. An interesting alternative is to reduce the array elements obtaining the so called ‘ thinned arrays’. Large thinned arrays have been exploited because of their advantages in terms of weight,consumption, hardware complexity, and cost over the...
Parametric Analysis of Interaction Between Crossing Tunnels at Different Level
, M.Sc. Thesis Sharif University of Technology ; Sadagiani, Mohammad Hossein (Supervisor)
Abstract
Sensibility of parameters that influence the Interaction between crossing tunnel at different level such as Soil charactristic, Construction procedure,Method of excavation,Rigidity of lining,Distance between tunnels and angle of intersection is studied. For comparison above parameters the surface settlement and bending moment during the excavation is measured .In order to simulate the Interaction between Crossing tunnels, use 3D finite element model with Abaqus program. The soil govern elasto-plastic mohr-coloumb constitutive equation.Parametric Analysis shows the great and different influence of each parameter that we can able to minimize this interaction with correct choose of this...
Analysis of Resonant Mode Distributions and Suppression of Undesired Modes at Strongly Coupled Oscillator Arrays
, M.Sc. Thesis Sharif University of Technology ; Banai, Ali (Supervisor)
Abstract
Mutually coupled oscillator arrays may be used for power combining at the millimeter-wave region. In addition, these arrays have the capability of beam steering without the use of any phase shifter. Using the strong coupling method is inevitable to obtain synchronization between all elements in the large arrays. One of the challenges in strongly coupled oscillators is the multi-moding problem or oscillation at undesired frequencies. In this thesis, we obtain mode distributions in a one-dimensional and a two-dimensional array with rectangular boundary, using a method based on circuit equations in the frequency domain. Then, we compared the results with the previous works and also verified...
A Hybrid BIM and BN-based Model to Improve the Resiliency of Hospitals' Utility Systems in Disasters
, M.Sc. Thesis Sharif University of Technology ; Alvanchi, Amin (Supervisor)
Abstract
The growing number of disasters in recent years has become a significant threat to hospital buildings' resilience and preparedness. Besides, the stochastic nature of these disasters and the complexity of the hospital building systems exacerbate the difficulty of making appropriate decisions during and after disasters. To address the issue, this research proposes a novel model that utilizes the capabilities of Bayesian Networks (BNs) and Building Information Modeling (BIM). This model helps decision-makers in hospitals and medical centers measure various effects of disasters on utility systems and analyze the consequences of their decisions. The capabilities of the proposed model are tested...
Conductive, injectable, and self-healing collagen-hyaluronic acid hydrogels loaded with bacterial cellulose and gold nanoparticles for heart tissue engineering
, Article International Journal of Biological Macromolecules ; Volume 280 , 2024 ; 01418130 (ISSN) ; Maleki, N ; Simchi, A ; Sharif University of Technology
2024
Abstract
The increasing demand for advanced biomaterials in nerve tissue engineering presents numerous challenges due to the complexity of nerve tissues and the need for materials that can accurately replicate their intricate structure and function. In response, this study introduces a novel injectable hydrogel that is thermosensitive, self-healing, and conductive, offering promising potential for heart and nerve tissue engineering applications. The hydrogel is based on collagen and hyaluronic acid functionalized with 3-aminopropyl-triethoxysilane (APTES)-grafted oxidized bacterial cellulose and gold nanoparticles (~50 nm). Rheological analysis reveals a substantial enhancement in the elastic modulus...
Controlling Local Scour Due to Hydraulic Jump Using Oblique Buried Plates
,
M.Sc. Thesis
Sharif University of Technology
;
Borghei, Mahmood
(Supervisor)
Abstract
Local scouring at the downstream of sluice gates in the erosive beds is one of the main concerns of hydraulic engineers because of the significant damage that it can cause to the hydraulic structures. It is important to control the local scour depth at downstream of hydraulic structures to ensure safety operation of these systems. Many researchers have conducted various studies to predict the maximum depth and diameter of scour hole and develop new methods in order to control this phenomenon. One way to overcome this problem is the use of apron, or non-erosive bed. In order to shorten the apron length or decrease the effect of the...
Experimental Study of Pressure Fluctuation in Two Phase Slug Flow In a Tunnel with Rectangular Cross Section with an Expansion Transition and Horizontal Slope
, M.Sc. Thesis Sharif University of Technology ; Borghie, Mahmood (Supervisor)
Abstract
Air enterance in to flowing water is something that is commonly seen in the water conveyance systems. The mixture of Air and water that flow together create a kind of flow that is called two phase flow. This kind of flow is often seen in culverts and water conveyance systems. There are different flow patterns in two phase flow. Considering pressure fluctuation, pressure drop and pressure recovery, slug flow pattern is the most complicated pattern among all.
Sometimes a singularity is used in a tunnel; one of the singularities that are frequently used in water conveyance system is expansion transition. In this study an experimental setup is used to model two phase slug flow, which passes...
Sometimes a singularity is used in a tunnel; one of the singularities that are frequently used in water conveyance system is expansion transition. In this study an experimental setup is used to model two phase slug flow, which passes...
Performance Analysis and Optimization of Optically Steered Arrayed Antennas with Gratings
, Ph.D. Dissertation Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
It is well known that arrays of antennas make it possible to steer the radiation pattern without steering a physical structure. For the past few decades this has been considered for many civil and military communication systems. Recently, ultra-short pulses are considered for high resolution radars and ultra-wideband communication systems. Systems with short pulses and large antenna arrays may benefit from high resolution in both temporal and spatial domains. But the implementation of the ultra-wideband feeding circuits for such antenna arrays is a hard job even with state of the art electronics. Optical technology has been applied, successfully, to a number of radio applications such as...
Laboratory Investigation For Unsymmetric Rectangular Weir
, M.Sc. Thesis Sharif University of Technology ; Borghei, Mahmood (Supervisor)
Abstract
Sharp crested weirs are one of the main and oldest means of measuring discharge in water conveyance systems. Many studies have been done on sharp rectangular weirs and have provided many relationships regarding the effect of geometric parameters and various factors on discharge coefficient of the weirs.In some places, due to existence of obstacles or barriers in the channel, it is impossible to create a symmetrical continuous weir some other cases,multiple or asymmetric weirs should be used, which is the main concept of this project.Since it seems unlikely that a purely mathematical model can review the impact of the multiplicity and asymmetry of these weirs without using empirical...
Optimization of Maximum Frequency and Power, Extraction of Parameter Data and Final Publication Design of High Power Microwave Pulse Generation Using nonlinear Transmission Line with the Periodic Structure of the Gas Switch
, M.Sc. Thesis Sharif University of Technology ; Akbari, Mahmood (Supervisor)
Abstract
High-power (108 – 109 W) RF pulses with a carrier frequency of C band and a duration of several oscillation periods can be produced through direct energy conversion of a travelling high-voltage pulse with the use of nonlinear elements.
Nonlinear transmission lines consist either of lumped nonlinear elements and provide spatial dispersion of excited oscillations or of elements uniformly distributed on a certain line segment. The first type of NLTL’s can be referred to NLTL’s with spatial dispersion. The second type of NLTL’s is ensemble of nonlinear oscillators with a characteristic natural frequency and temporal dispersion. In the first case, the duration of electromagnetic pulses is...
Nonlinear transmission lines consist either of lumped nonlinear elements and provide spatial dispersion of excited oscillations or of elements uniformly distributed on a certain line segment. The first type of NLTL’s can be referred to NLTL’s with spatial dispersion. The second type of NLTL’s is ensemble of nonlinear oscillators with a characteristic natural frequency and temporal dispersion. In the first case, the duration of electromagnetic pulses is...
An Estimation Model for Computation and Control of Trajectory Coverage Error in Additive Manufacturing
, M.Sc. Thesis Sharif University of Technology ; Houshmand, Mahmood (Supervisor)
Abstract
During 1980s Additive Manufacturing technologies for the purpose of prototyping with fast and less expensive, under the name of Rapid Prototyping was invented. But nowadays under the vast progress made in this field, it possesses a notable place in different industries such as automobile manufacturing, aerospace, architecture, medicine and so on for part manufacturing. In all AM machines, the CAD model design part is manufactured by adding layered to each other. In this research, at first by explaining manufacturing process and current different technologies, the place of this manufacturing process in today and future industry, is analyzed. For discussing replacement of this method instead...