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Jahn-Teller Effect in Diamond Vacancy Under Stress
, M.Sc. Thesis Sharif University of Technology ; Vesaghi, M. A (Supervisor) ; Babamoradi, M (Co-Advisor)
Abstract
Electron states of diamond vacancy under stress were studied theoretically. The generalized Hubbard model is used to calculate the electrons energy levels. The results shows that the degeneracy of some levels (T, with triple space degeneracy) reduced to levels with lower degeneracy (E, with double space degeneracy and A, without degeneracy). Besides this spiting of degeneracy the energy of all states changed and therefore the transition energy between these states changed too. Jahn-Teller effect was observed
, M.Sc. Thesis Sharif University of Technology ; Golshani, M (Supervisor)
Abstract
Most of local thinkers ,who were influenced by Western philosophers of science, and have spoken about religious knowledge, have selected experimental science as standard science and Have tried to find a way trough cultural and other non-scientific channels of science to influence the field of human knowledge by religious teaching's .This expert's are generally opposed to positivist’s models of science, but because of the nature of the Western atmosphere that they breathe, consider the experimental science as the main model of knowledge and the experience as the main method of Acquisition of knowledge. Paya is also one of this thinkers who is influenced by Karl Popper's ideas about the...
Light Duty Vehicles' Emission Reduction Potentials in Megacities
Using New Powertrain Technologies (Case Study: Tehran)
,
M.Sc. Thesis
Sharif University of Technology
;
Erhami, M. (Mohammad)
(Supervisor)
;
Pourzahedi, H. (Hossein)
(Supervisor)
Abstract
Tehran is one of the most polluted megacities in the world, and based on different studies, vehicular sources are responsible for most of the criteria pollutant emissions in this city. The number of vehicles on the streets has been increased drastically leading to growing amount of emission and this trend is continuing. In order to reduce the amount of vehicular emission, it is vital to investigate the factors affecting vehicles emission in this city. This could help to find efficient solutions to improve the situation. Hence, a low-cost methodology to estimate the vehicular emissions is developed. In this...
Energy Optimization of an Arm with Seven Degrees of Freedom Using Imperialistic Competitive Algorithm (ICA) and Designing an Artificial Neural Network
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, M.T (Supervisor) ; Asghari, M (Supervisor)
Abstract
In recent years, great attention has been devoted to the design of artificial arms. The most crucial problem in such a design is the trajectory of movement. In this paper, a seven degree of freedom arm is modeled and simulated. Also, the optimization method named “Imperialistic Competitive Algorithm” has been modified and better performance of the new version is presented. Energy optimization is performed based on trajectory of the arm with angular velocity, angular acceleration and joint angles using modified imperialistic competitive algorithm (ICA). Considering ICA as a fast optimization algorithm, it would be reasonable to use this algorithm for robotic purposes for online answering. The...
Real-Time Fusion of Asynchronous Data in Distributed Sensor Networks
,
Ph.D. Dissertation
Sharif University of Technology
;
Hemmatyar, A. M. Afshin
(Supervisor)
Abstract
Real-time asynchronous data fusion for high-speed phenomena is an important and challenging task in the sensor networks. Examples of data fusion applications in sensor networks are: managing the traffic of maneuvering airplanes and ground vehicles in airside areas of an airport, traffic management in streets and roads, Driver Assistance Systems, guidance of antiaircraft and antimissile missiles. In all the data fusion applications the estimation of the required variables is necessary.
In this research two methods are introduced for real-time asynchronous data fusion, especially for track-to-track fusion of high-speed phenomena in sensor networks. The effectiveness and usability of these...
In this research two methods are introduced for real-time asynchronous data fusion, especially for track-to-track fusion of high-speed phenomena in sensor networks. The effectiveness and usability of these...
Fabrication of Al Based Nanocomposite with Al2O3 and Al3Ti Reinforcements by Mechanical Milling and Press and Sintering (In situ method) and Investigation of Its Wear Behavior
, M.Sc. Thesis Sharif University of Technology ; Seyed Reihani, M (Supervisor)
Abstract
In this study, Aluminium based nanocomposite with Al3Ti and Al2O3 nanoparticles have been elaborated by mechanical alloying. For this purpose, Al and TiO2 powders have been blended with weight ratios of 10, 20 and 30 percents and were milled using a planetary mill. Morphological variations in different timing periods of mechanical milling process was investigated by Scaning Electron Microscopy (SEM) and The optimal times for alloying were determined for each combination. The pure Aluminium and the powder with 10, 20 and 30%wt reinforcement had coax morphology after respectively for 44, 30, 24 and 14 hours. after studing phase transformations by XRD analysis, the final powders were cold...
Designing a Reward-Penalty Scheme to Improve Technical Performance of Distribution System Employing Distributed Generation (DG) Resources
, M.Sc. Thesis Sharif University of Technology ; Abbaspour Tehranifard, Ali (Supervisor) ; Fotuhi Firuzabad, Mahmud (Supervisor)
Abstract
Reward-penalty schemes are known as the most effective tools to regulate the service quality. This thesis tries to design a comprehensive reward-penalty scheme to properly motivate electricity distribution companies (DisCos) to improve the reliability and reduce the energy losses in their networks using Distributed Generation (DG) Resources. So, as the first step, the designing methods of reward-penalty scheme (RPS) and their advantage and disadvantages are introduced, and also a method based on concept of the Yaredestic theory is proposed. The proposed method uses the Fuzzy clustering and is able to set the parameters of RPS in a fair and efficient way. The proposed RPS is implemented on...
Electricity Distribution System Planning Considering Incentive Reliability Regulations
, Ph.D. Dissertation Sharif University of Technology ; Abbaspour Tehranifard, Ali (Supervisor) ; Lehtonen, Matti (Co-Supervisor) ; Fotuhi Firuzabad, Mahmoud (Co-Supervisor)
Abstract
Electricity distribution systems are dynamically expanded in anticipation of new demands. Cost and reliability are the most important factors in finding the optimal plans for network expansion. Recently, implementation of incentive reliability regulations has accentuated the role of reliability considerations in distribution systems studies. This is because such incentive schemes create a direct link between distribution companies' revenues and their service reliability. Thus, these schemes have changed the role of reliability from a technical constraint to an economic factor. In this occasion, distribution companies require new techniques to incorporate the effects of incentive reliability...
Sustainable Analysis of Unions Uses Axiomatic Design Theory with Focus on European Union
, M.Sc. Thesis Sharif University of Technology ; Malaek, S. M (Supervisor)
Abstract
In this project, we examine the stability or sustainability issue in unions, in other words we want to know whether integration in European Union is stable? Countries have positive attitude toward unions and being member in unions is at special priorities. The main reason for countires is improve economy and national Security.
The main question in this research is modeling European Union with Axiomatic Design Theory and analysis of sustainability based on this theory. This study has attempted to push Axiomatic Design Theroy in the new field of Systems Engineering and also it gives a new and differnet approach to stability.
The main question in this research is modeling European Union with Axiomatic Design Theory and analysis of sustainability based on this theory. This study has attempted to push Axiomatic Design Theroy in the new field of Systems Engineering and also it gives a new and differnet approach to stability.
Surface micromorphology and fractal geometry of Co/CP/X (X = Cu, Ti, SM and Ni) nanoflake electrocatalysts
, Article RSC Advances ; Volume 6, Issue 32 , 2016 , Pages 27228-27234 ; 20462069 (ISSN) ; Solaymani, S ; Bramowicz, M ; Naseri, N ; Kulesza, S ; Ghaderi, A ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
This paper analyses the three-dimensional (3-D) surface texture of Co/CP/X (X = Cu, Ti, SM and Ni, CP: carbonaceous paste) nanoflakes prepared electrochemically using a conventional three electrode system. The surface chemical composition of the samples was investigated by X-ray photoelectron spectroscopy (XPS). Surface images were recorded using scanning electron microscopy (SEM) and analyzed by means of the fractal geometry. Statistical, fractal and functional surface properties of the prepared samples were computed. The statistical functions applied to the SEM data were employed in order to characterise the surfaces topographically (in amplitude, spatial distribution and pattern of...
Stereometric and fractal analysis of sputtered Ag-Cu thin films
, Article Surfaces and Interfaces ; Volume 21 , 2020 ; Matos, R. S ; Pinto, E. P ; Rezaee, S ; Mardani, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this paper, we have successfully deposited Ag-Cu thin films. Nanoscale morphology and nanotexture were studied using atomic force microscopy (AFM) through fractal and stereometric parameters. Additional algorithms have been developed to study new fractal parameters such as surface entropy, fractal succolarity, and fractal lacunarity. The results revealed that as the deposition time increased, films exposed isotropies between ~65 and 82%, which were correlated to the fractal patterns, where from #3 to #5 there were greater spatial complexities. Moreover, surface roughness increased from #1 to #3, which was observed for both Sq and Sa. Similar behavior was exhibited by the other height...
Markdown budgets for retail buyers: help or hindrance?
, Article Production and Operations Management ; Volume 26, Issue 10 , 2017 , Pages 1875-1892 ; 10591478 (ISSN) ; Talebian, M ; Sharif University of Technology
2017
Abstract
For many retailers, markdown decisions are taken by retail buyers whose compensation is based on sales revenue so their objective is to maximize it through the season. This implies that the buyers' objectives are not perfectly aligned with the overall profitability the firm. Many retailers set markdown budgets prior to the season to control margin erosion and increase profitability. Markdown budget constrains the buyers on the amount of discounts that they can apply on a given inventory of merchandise and sets a limit on the dollar value of markdowns for the season. While markdown budgets may be useful in preventing excessive discounts, they can have a detrimental effect on the buyers'...
Protein folding rates correlate with heterogeneity of folding mechanism
, Article Physical Review Letters ; Volume 93, Issue 20 , 2004 , Pages 208105-1-208105-4 ; 00319007 (ISSN) ; Ejtehadi, M. R ; Plotkin, S. S ; Sharif University of Technology
American Physical Society
2004
Abstract
The folding rates of protein were shown to correlate with the degree of heterogeneity in the formation of native contacts. It was shown that both experimental rates and simulated free energy barriers for 2-state proteins depend on the degree of heterogeneity present in the folding process. Heterogeneity due to variance in the distribution of native loop lengths, and variance in the distribution of φ values, were observed to increase folding rates and reduce folding barriers. The observed effect due to φ variance was found to be the most statistically significant, because φ variance captures both heterogeneity arising from native topology and that arising from energetics
A study of structural, magnetic and various dielectric parameters of Ca-Substituted W-Type hexaferrites for applications at 1–6 GHz frequencies
, Article Journal of Electronic Materials ; Volume 48, Issue 11 , 2019 , Pages 7149-7161 ; 03615235 (ISSN) ; Shaukat, S. F ; Akhtar, M. N ; Ahmad, M ; Sharif University of Technology
Springer New York LLC
2019
Abstract
Single phase Ca-substituted W-type hexaferrites Sr1-xCaxZn2Fe16O27(x = 0.00(0.25)1.00) have successfully been synthesized by using sol–gel self-combustion at 1300°C. These hexaferrites are investigated by x-ray difrractometry (XRD), scanning electron microscopy, energy dispersive x-ray spectroscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry, and vector network analysis. XRD analysis confirms the formation of a single W-type hexaferrites phase. The DC electrical resistivity increases with incrementing Ca contents. The morphology of all the hexaferrites shows hexagonal platelet-like structure. The prepared ferrites depict soft magnetic nature with high saturation...
Facility and hub location model based on gravity rule
, Article Computers and Industrial Engineering ; Volume 109 , 2017 , Pages 28-38 ; 03608352 (ISSN) ; Akbari Jokar, M. R ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
This paper presents a model for “Domestic Facility and Hub Location” in transportation network. Number of hubs and facilities are unknown and the objective is to minimize the transportation cost, lost demand penalty and facility set up costs. Also the distribution of demand among domestic facilities and hubs adheres to gravity rule. To solve the problem, sequential and integrated approaches were undertaken. In the sequential approach, domestic facilities were allocated and hubs were selected afterwards. However the integrated approach deals with both concurrently, with a more sophisticated steps reaching to the solution. This is mainly because the demand itself is highly dependent to where...
Facile electrochemical detection of morpholine in boiler water with carbon nanostructures: a comparative study of graphene and carbon nanotubes
, Article Bulletin of Materials Science ; Volume 45, Issue 2 , 2022 ; 02504707 (ISSN) ; dos Santos Castro Assis, K. L ; Paiva, V. M ; Hashempour, M ; Bestetti, M ; de Araújo, J. R ; D’Elia, E ; Sharif University of Technology
Springer
2022
Abstract
Two electrochemical sensors based on modified glassy carbon electrodes with carbon nanostructures as graphene (GCE–EG) and carbon nanotubes (GCE–CNT) were evaluated for morpholine analysis. The carbon nanostructures were obtained and characterized using X-ray photoelectron spectroscopy, Raman spectroscopy, X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy and cyclic voltammetry. All spectroscopic and microscopic techniques confirmed the procurement of graphene and CNT. The electrochemical studies proved the efficient behaviour of both electrodes GCE–EG and GCE–CNT in sensing and detection of morpholine via differential pulse voltammetry....
Microstructure, fractography, and mechanical properties of hardox 500 steel tig-welded joints by using different filler weld wires
, Article Materials ; Volume 15, Issue 22 , 2022 ; 19961944 (ISSN) ; Haowei, M ; Yarigarravesh, M ; Assari, A. H ; Tayyebi, M ; Tayebi, M ; Hamawandi, B ; Sharif University of Technology
MDPI
2022
Abstract
This paper deals with the effects of three low-carbon steel filler metals consisting of ferritic and austenitic phases on the weld joints of the tungsten inert gas (TIG) welding of Hardox 500 steel. The correlation between the microstructure and mechanical properties of the weld joints was investigated. For this purpose, macro and microstructure were examined, and then microhardness, tensile, impact, and fracture toughness tests were carried out to analyze the mechanical properties of joints. The results of optical microscopy (OM) images showed that the weld zones (WZ) of all three welds were composed of different ferritic morphologies, including allotriomorphic ferrite, Widmanstätten...
The confinement tensor model improves characterization of diffusion-weighted magnetic resonance data with varied timing parameters
, Article Proceedings - International Symposium on Biomedical Imaging, 13 April 2016 through 16 April 2016 ; Volume 2016-June , 2016 , Pages 1093-1096 ; 19457928 (ISSN) ; 9781479923502 (ISBN) ; Afzali, M ; Yolcu, C ; Westin, C. F ; Menegaz, G ; Ozarslan, E ; Sharif University of Technology
IEEE Computer Society
2016
Abstract
Diffusion imaging with confinement tensor (DICT) is a new model that employs a tensorial representation of the geometry confining the movements of water molecules. The model differs substantially from the commonly employed diffusion tensor imaging (DTI) technique even at small diffusion weightings when the dependence of the signal on the timing parameters of the pulse sequence is concerned. In this work, we assess the accuracy of the two models on a data set acquired from an excised monkey brain. The publicly available data set features differing values for diffusion pulse duration and separation. Our results indicate that the normalized mean squared error is reduced in an overwhelming...
Magnetic anisotropies in FeCo fine particles
, Article Journal of Magnetism and Magnetic Materials ; Volume 300, Issue 2 , 2006 , Pages 525-531 ; 03048853 (ISSN) ; Azarkharman, F ; Sebt, S. A ; Akhavan, M ; Sharif University of Technology
2006
Abstract
The single-domain particles, especially FeCo fine particles have many applications in magnetic information technology. We have prepared Fe 1-xCox fine particles for different x by borohydride method and measured the magnetic and structural properties of the samples. We have then determined the variations of coercivity and anisotropy energy versus x in Fe1-xCox fine particles. The obtained results have been analyzed on the basis of various magnetic anisotropies. Magnetic anisotropies affect the coercivity of the medium for each x as follows: shape and crystal anisotropies for x=0, surface and crystal anisotropies for x=1, shape, induced and crystal anisotropies for x=0.3 and 0.5, and shape...
Magnetic viscosity-coercivity relation for Fe1-xCox fine particles
, Article Physica B: Condensed Matter ; Volume 403, Issue 1 , 2008 , Pages 12-15 ; 09214526 (ISSN) ; Sebt, S. A ; Akhavan, M ; Sharif University of Technology
2008
Abstract
The variation of the applied field results in a subsequent change of magnetization with time. There is a relationship between the coercivity (Hc), as the equilibrium characteristic of the system, and its magnetic stability (1/S), as a parameter characterizing the time dependence. 1/S as a function of Hc has been measured and studied for different Fe1-xCox samples. We synthesized several samples with different values of x by applying various magnetic fields during the grains' growth, and observed a linear relationship between 1/S and Hc. © 2007 Elsevier B.V. All rights reserved