Examination of a solar desalination system equipped with an air bubble column humidifier, evacuated tube collectors and thermosyphon heat pipes

, Article Desalination ; Volume 397 , 2016 , Pages 30-37 ; 00119164 (ISSN) Behnam, P ; Behshad Shafii, M ; Sharif University of Technology

Elsevier 2016

Abstract

In this paper, the performance of a novel HDH solar desalination system equipped with a combination of heat pipe (HP), evacuated tube collector (ETC) and air bubble column humidifier is experimentally investigated. This novel HDH system uses advantages of ETC-HP as a highly efficient thermal absorption and conductor device, and at the same time employs the advantages of an air bubble column humidifier, i.e. high interface area and effective mixing in order to heat the water and humidify the air, respectively. The effects of various parameters including incoming air flow rate into the humidifier, initial depth of water in the humidifier, and adding fluids such as oil and water in the space...

MRI-PET image fusion based on NSCT transform using local energy and local variance fusion rules

, Article Journal of Medical Engineering and Technology ; Vol. 38, issue. 4 , 2014 , p. 211-219 Amini, N ; Fatemizadeh, E ; Behnam, H ; Sharif University of Technology

2014

Abstract

Image fusion means to integrate information from one image to another image. Medical images according to the nature of the images are divided into structural (such as CT and MRI) and functional (such as SPECT, PET). This article fused MRI and PET images and the purpose is adding structural information from MRI to functional information of PET images. The images decomposed with Nonsubsampled Contourlet Transform and then two images were fused with applying fusion rules. The coefficients of the low frequency band are combined by a maximal energy rule and coefficients of the high frequency bands are combined by a maximal variance rule. Finally, visual and quantitative criteria were used to...

A robust dual source level set method for three-dimensional echocardiography image segmentation

, Article Journal of Theoretical and Applied Information Technology ; Volume 95, Issue 21 , 2017 , Pages 5701-5710 ; 19928645 (ISSN) Sahba, N ; Fatemizadeh, E ; Behnam, H ; Sharif University of Technology

2017

Abstract

Echocardiography as a common place device has been widely used for diagnosis. Segmentation of left ventricle just using the standard level set formulation based on the magnitude of intensity cannot restrict the contour evolution completely due to the lack of sharp edges. This paper aims to introduce a robust method for segmentation of three-dimensional echocardiography images based on two boundary maps namely distance map and probabilistic map as stopping criteria of contour evolution which are extracted using two different approaches. The distance map is extracted by applying Free Form Deformation (FFD) method on manually determined landmarks of initial spherical volume to register the...

An optimized probabilistic edge based level set method for left ventricle segmentation in echocardiography images

, Article Biomedical Research (India) ; Volume 28, Issue 8 , 2017 , Pages 3788-3793 ; 0970938X (ISSN) Sahba, N ; Fatemizadeh, E ; Behnam, H ; Sharif University of Technology

Scientific Publishers of India 2017

Abstract

In this paper, an efficient approach for ultrasonic object segmentation with special application for left ventricle segmentation in echocardiography images is proposed. At first, an efficient hybrid trend for ultrasonic image edge detection is suggested. Then, a modified level set approach is introduced based on the extracted edges and the computed probabilistic map as the stopping criteria for the contour evolution. Both synthetic and clinical images are utilized as validation measures with respect to the prior techniques which indicate outperform results quantitatively and qualitatively. Left ventricle segmentation using proposed method illustrates expert-approved performance, providing a...

A review on state-of-the-art applications of data-driven methods in desalination systems

, Article Desalination ; Volume 532 , 2022 ; 00119164 (ISSN) Behnam, P ; Faegh, M ; Khiadani, M ; Sharif University of Technology

Elsevier B.V 2022

Abstract

The substitution of conventional mathematical models with fast and accurate modeling tools can result in the further development of desalination technologies and tackling the need for freshwater. Due to the great capability of data-driven methods in analyzing complex systems, several attempts have been made to study various desalination systems using data-driven approaches. In this state-of-the-art review, the application of various artificial intelligence and design of experiment data-driven methods for analyzing different desalination technologies have been thoroughly investigated. According to the applications of data-driven methods in the field of desalination, the reviewed...

Free-edge stresses in general cross-ply laminates

, Article Scientia Iranica ; Vol. 21, issue. 2 , April , 2014 , p. 387-402 Yazdani Sarvestani, H ; Sharif University of Technology

2014

Abstract

Within elasticity theory, the reduced form of a displacement field is obtained for general cross-ply composite laminates subjected to a bending moment. The firstorder shear deformation theory of plates and Reddy's layerwise theory are then utilized to determine the global deformation parameters and the local deformation parameters appearing in the displacement fields, respectively. For a special set of boundary conditions an elasticity solution is developed to verify the validity and accuracy of the layerwise theory. Finally, various numerical results are presented within the layerwise theory for edge-effect problems of several cross-ply laminates under the bending moment. The results...

Automatic segmentation of brain MRI in high-dimensional local and non-local feature space based on sparse representation

, Article Magnetic Resonance Imaging ; Volume 31, Issue 5 , 2013 , Pages 733-741 ; 0730725X (ISSN) Khalilzadeh, M. M ; Fatemizadeh, E ; Behnam, H ; Sharif University of Technology

2013

Abstract

Automatic extraction of the varying regions of magnetic resonance images is required as a prior step in a diagnostic intelligent system. The sparsest representation and high-dimensional feature are provided based on learned dictionary. The classification is done by employing the technique that computes the reconstruction error locally and non-locally of each pixel. The acquired results from the real and simulated images are superior to the best MRI segmentation method with regard to the stability advantages. In addition, it is segmented exactly through a formula taken from the distance and sparse factors. Also, it is done automatically taking sparse factor in unsupervised clustering methods...

Adaptive sparse representation for MRI noise removal

, Article Biomedical Engineering - Applications, Basis and Communications ; Volume 24, Issue 5 , October , 2012 , Pages 383-394 ; 10162372 (ISSN) Khalilzadeh, M. M ; Fatemizadeh, E ; Behnam, H ; Sharif University of Technology

World Scientific 2012

Abstract

Sparse representation is a powerful tool for image processing, including noise removal. It is an effective method for Gaussian noise removal by taking advantage of a fixed and learned dictionary. In this study, the variable distribution of Rician noise is reduced in magnetic resonance (MR) images by sparse representation based on reconstruction error sets. Standard deviation of Gaussian noise is used to find these errors locally. The proposed method represents two formulas for local error calculation using standard deviation of noise. The acquired results from the real and simulated images are comparable, and in some cases, better than the best Rician noise removal method due to the...

Thermodynamic analysis of a novel combined power and refrigeration cycle comprising of EKalina and ejector refrigeration cycles

, Article International Journal of Refrigeration ; Volume 104 , 2019 , Pages 291-301 ; 01407007 (ISSN) Behnam, P ; Faegh, M ; Shafii, M. B ; Sharif University of Technology

Elsevier Ltd 2019

Abstract

A novel combined power and refrigeration cycle is introduced and analyzed from the thermodynamic standpoint. The proposed cycle is an integration of a Kalina cycle equipped with an ejector (EKalina) and an ejector refrigeration cycle (ERC). In order to enhance the overall cycle performance, the possibility of employing two-phase ejectors in combined power and refrigeration cycles is studied. A parametric analysis is conducted to investigate the effects of the key thermodynamic parameters namely turbine inlet pressure, split ratio, basic ammonia concentration, heat source and evaporator temperatures on the cycle performance. The developed model is also verified with available data and it is...

Effect of cooling rate on microstructure and mechanical properties of gray cast iron

, Article Materials Science and Engineering A ; Volume 528, Issue 2 , 2010 , Pages 583-588 ; 09215093 (ISSN) Jabbari Behnam, M. M ; Davami, P ; Varahram, N ; Sharif University of Technology

2010

Abstract

This paper presents the results obtained and the deductions made from a series of microstructural studies and mechanical tests involving gray cast iron which was sand cast using a variety of modules. The effect of cooling rate on the primary dendrite arm spacing (DAS), secondary dendrite arm spacing (SDAS), thickness of ferrite-cementite layer (λe) and the hardness (HB) were evaluated. Results show that the both DAS and SDAS and also λe are highly dependent on the cooling rate, and they decreases as the cooling rate increases. More attempts were also done to correlate the HB with DAS, SDAS and λe. It was found that HB increases as DAS, SDAS and λe decreases

Feasibility Study of Offering Generalized Equivalent Model for Drag Polar in Formation Flight

, M.Sc. Thesis Sharif University of Technology Behnam Nia, Fahimeh (Author) ; Malaek, Mohammad Bagher (Supervisor)

Abstract

The increasing demand for air transportation, along with air traffic limitations and environmental pollution concerns, necessitate a comprehensive study in the field of airspace-management. In this regard, one of the promising alternatives is flying smarter via “Formations”. In fact, many works have discussed the benefits of “Commercial Formation Flights”; however, none have discussed a practical way to manage such formations for long-distance cruise. This paper discusses a new approach to manage the “Geometrical Arrangement” of such flights in an efficient manner. In fact, with the help of the so called “Game Theory” and without complex computations we are able to guide each individual...

Exergetic and thermoeconomic analysis of a trigeneration system producing electricity, hot water, and fresh water driven by low-temperature geothermal sources

, Article Energy Conversion and Management ; Volume 157 , 2018 , Pages 266-276 ; 01968904 (ISSN) Behnam, P ; Arefi, A. R ; Shafii, M. B ; Sharif University of Technology

Elsevier Ltd 2018

Abstract

Performance of a small-scale trigeneration system driven by low-temperature geothermal sources for producing fresh water, heating (hot water) and electricity is investigated from thermodynamic and economic standpoints. This system, utilizing a single stage absorption heat transformer leads to an increase in heat source temperature to be used in single stage evaporation desalination process and also providing water heating. Furthermore, an organic Rankine cycle is used for electric power generation. The developed model is validated with available data and effects of decision variables namely geothermal source, absorber and condenser temperatures on energy and exergy efficiencies of the...

Multicast Routing on Wireless Mesh Networks

, M.Sc. Thesis Sharif University of Technology Abbasi, Reza (Author) ; Yazdani, Naser (Supervisor)

Abstract

Wireless mesh networks (WMN) appeared as popular communication networks supporting high speed and high throughput applications. They consist of mesh routers and mesh clients and they have unique characteristics like self organizing and self configuring of the mesh nodes that bring a great deal of efficiency, reliability and robustness to networks and decreases networks maintenance cost notably. Also WMNs provide an integration of different types of wireless networks by exploiting the gateway involvement. One of the important group communication technologies that offers high level of bandwidth conservation and efficiency is multicasting. It also decreases the cost of communication compared to...

Experimental Study of Pendulum Grinding of Superalloys

, M.Sc. Thesis Sharif University of Technology Yazdani, Majid (Author) ; Akbari, Javad (Supervisor)

Abstract

Superalloys are widely used in aerospace and power industries due to the good performance at high temperatures for examples gas turbines, steam turbines and aircraft components. In addition to the turbines cobalt-base superalloys are used in medical implants such as knee and hip joints. The main strengths of the superalloys are heat-resistant, retaining their high mechanical and chemical properties at high temperatures, high melting temperatures, high corrosion resistance, resistance to thermal fatigue, thermal shock, creep, and erosion. Because of difficult to machine properties of superalloys, grinding is one of the effective methods for machining superalloys. The surface integrity of the...

Feyerabend’s Point of View on Scientific Progress

, M.Sc. Thesis Sharif University of Technology Yazdani, Homa (Author) ; Taghavi, Mostafa (Supervisor)

Abstract

Feyarabend’s philosophy of science is against method and rule such that he believes that “anything goes”. However, he sometimes applies the term “progress”. Reviewing his publications shows that from his point of view, progress is qualitative and relative. So, unlike other philosophers of science Feyarabend ignores the clarification of the concept; subsequently, his applications of the term “progress” are somewhat ambiguous. However, by studying his philosophy, one may realize what should be done to achieve progress in any sense. The affirmative aspect of Feyerabend’s philosophy, while highlights the social and ethical elements, considering his humanitarian outlook as well as his special...

Aeroacoustic Simulation of Rod-Airfoil Noise

, M.Sc. Thesis Sharif University of Technology Yazdani, Mostafa (Author) ; Farshchi, Mohammad (Supervisor)

Abstract

Wall systems are an essential part of the buildings and their capacity should be properly considered in their design. However, the seismic behavior of building systems with in-filled walls and their interaction is a very complex issue, yet to be understood. Using the in-filled walls in the buildings without including them in the design process changes the whole behavior of the structural system as well as their failure mechanism under earthquake excitations. On the other hand, there have been extensive researches on rehabilitation of the structures with in-filled walls or designing them as the main or one of the lateral load carrying systems against seismic input. In this research, first the...

Design and Implementation of High Efficient Charger for Plug-in Hybrid Vehicles with Power Factor Correction Feature

, M.Sc. Thesis Sharif University of Technology Yazdani, Farzad (Author) ; Tahami, Farzad (Supervisor)

Abstract

In this project the novel zero-voltage-switching topology for power factor correction bridgeless boost rectifier is proposed. By employing an improved ZVS pulse-width-modulation (PWM) switch cell, ZVS of all the main switches is achieved without additional current or voltage stress of main switches. Also for the auxiliary switch the zero-current-switching is provided. In all modes of opretion of this converter, the power path is provided by maximum two semiconductor so the conduction loss of converter is low as in conventional converter. With this features the efficiency of proposed converter is very high

Dynamic Model Identification of a 4th Generation Turbojet Engine’s FCU Using Parametric Frequency Response Analysis

, M.Sc. Thesis Sharif University of Technology Yazdani, Amin (Author) ; Banazadeh, Afshin (Supervisor)

Abstract

In this thesis, dynamics of a turbojet’s fuel control unit is studied for the nature and the range of its inputs and outputs. Then, inputs and outputs involved in the system identification process are determined. Tools needed for the application of the input and the signal data sampling are recognized, and henceforth, with the appropriate input applied and the frequency-domain system identification process carried out, desired linear transformation functions representing dynamics of the fuel control unit are found. Using these transformation functions, the fuel control unit is simulated to be converted to an electronic control unit

Higher-order four-wave mixing modeling in DWDM networks

, Article Physica Scripta, Belgrade ; Volume T157 , 15 November , 2013 ; 02811847 (ISSN) Yazdani, A ; Noshad, M ; Sharif University of Technology

2013

Abstract

In this paper, we derive a theoretical model for the higher-order four-wave mixing (FWM) power in wavelength division multiplexing networks with non-zero dispersion shifted fibers for the first time. We have investigated the higher-order FWM power theoretically and by numerical simulations. Dividing the fiber into a finite number of elements and applying the boundary conditions allow us to derive an expression for the second-order power penalty. At the end of each element, we derive the first-order FWM power for all wavelengths and use these values to calculate the second-order FWM power in the next element. Consequently, for each channel we can compute the total second-order FWM power...

On the existence of periodic solutions in time-invariant fractional order systems

, Article Automatica ; Volume 47, Issue 8 , 2011 , Pages 1834-1837 ; 00051098 (ISSN) Yazdani, M ; Salarieh, H ; Sharif University of Technology

2011

Abstract

Periodic solutions and their existence are one of the most important subjects in dynamical systems. Fractional order systems like integer ones are no exception to this rule. Tavazoei and Haeri (2009) have shown that a time-invariant fractional order system does not have any periodic solution. In this article, this claim has been investigated and it is shown that although in any finite interval of time the solutions do not show any periodic behavior, when the steady state responses of fractional order systems are considered, periodic orbits can be detected