Loading...
Search for:
weighing
0.006 seconds
Total 33 records
Design and Fabrication of Weigh in Motion System for Railway Vehicles
, M.Sc. Thesis Sharif University of Technology ; Saadat Foumani, Mahmud (Supervisor)
Abstract
Railroads should be well maintained for safe and efficient operation. The most important reason for the failure of railways is overload and asymmetric load on them. Also, the proper interval for repairs should be adjusted to fit the load crossed over. In order to carry out all these tasks, a constant observation of the weight on the rails must take place. Current dynamic weighing systems are costly. In addition, the installation of these systems is time-consuming and causes permanent damage to the rails. On the other hand, some of the cheaper models of weighing systems require full stop and static weighing, which practically does not work at all, especially on busy rails due to delays. The...
Evaluation of the Hydrodynamic Performance of A Special Submarine Rescue System
, M.Sc. Thesis Sharif University of Technology ; Abbaspour, Madjid (Supervisor)
Abstract
The increasing growth of marine tourism has strengthened the activities related to this industry. One of the most profitable of these activities is recreational submarines. A traction recreational submarine is an idea in this field, in order to reduce costs, the propulsion force is removed and the submarine is towed by the mother ship. The most important reason for using the traction system and removing the independent drive is to prevent vibration and noise caused by the rotation of the propeller to prevent the escape of aquatic animals and to create a beautiful view from under the sea to watch underwater wonders. Searching for safety and saving people's lives in emergency situations is an...
Studying the Effect of Zirconia & GNP on Mechanical, Tribological & Biological Properties of UHMWPE-HAp Nanocomposites used in Total Hip Joint Replacement
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Reza (Supervisor) ; Faghihi Sani, Mohammad Ali (Supervisor)
Abstract
Medical engineering advances in total joint replacements and society’s rising demand for long lasting materials, have proven it essential to manufacture materials that are more similar to the original tissue in the fields of mechanical, tribological and biological properties. Ultra High Molecular Weight Polyethylene(UHMWPE), is a polymer widely used in arthroplasty applications due to its biocompatibility, chemical stability and proper mechanical properties. In this study, UHMWPE-HAp nanocomposites reinforced with Zirconia and Graphene were manufactured aiming to reach a structure that is more compatible with bone tissue and also to improve overall properties. First, using ultrasonication...
Experimental Investigation of Biodiesel Production from Oils by Transesterification Method Catalyzed by Nano-heterogeneous Catalysts
, M.Sc. Thesis Sharif University of Technology ;
Abstract
Today polyolefin definitely is one of the most applicable polymers in the world. One of these polymers is ultra-high molecular weight polyethylene. Being applicable in a number of high-tech industries such as military service, battery separators, and other areas, expands the usage of these polymers. Electrospinning is one of the molding methods in order to synthesize fiber polymers. Using this method, a great deal of polymer fibers have been prepared. It is worth noting that the device used for olefins should have temperature control and temperature increase ability. The electrospinning device with the temperature control has not been built in the country; therefore, this device has been...
Preparation and Investigation the Properties of UHMWPE/Graphene Nanocomposites Via in Situ Polymerization Using Ziegler Natta Catalyst
, Ph.D. Dissertation Sharif University of Technology ; Ramezani Saadat Abadi, Ahmad (Supervisor)
Abstract
The main object of the presented thesis is manufacturing ultra high molecular weight polyethylene(UHMWPE)/Graphene nanocomposites by insitu polymerization using Ziegler Natta catalysts. In this study, three types of Ziegler Natta Catalysts such as Magnesium ethoxide supported, single-supported and bi-supported have been studied. Experimental conditions are optimized (from point of productivity and molecular weight) by Design expert software with response surface methodology (Box-Behnken design). Effect of process parameters like temperature, pressure and [Al]/[Ti] molar ratio on productivity and Molecular weight are investigated. Also, the effect of hydrogen presence and type of cocatalyst...
Localized Multiple Kernel Learning for Image Classification
, Ph.D. Dissertation Sharif University of Technology ; Jamzad, Mansour (Supervisor)
Abstract
It is not possible to compute a linear classifier to classify real world images, which are the focus of this thesis. Therefore, the space of such images is considered as a complex. In such cases, kernel trick in which data samples are implicitly mapped to a higher dimension space, leads to a more accurate classifier in such spaces. In kernel learning methods, the best kernel is trained for the classification problem in hand. Multiple Kernel Learning is a framework which uses weighted sum of multiple kernels. This framework achieves good accuracy in image classification since it allows describing images via various features. In the image input space which is composed of different extracted...
Preparation and Investigation of Ziegler-natta Catalyst with Nano MoS2 Support in UHMWPE Synthesis
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadat Abad, Ahmad (Supervisor)
Abstract
Ultra high molecular weight polyethylene has attracted the attention of numerous researchers and industries. This polymer due to its strong properties can be used in advanced military industries, medical engineering and cases in which high strength and high abrasion resistance is required. Present study aims to fabricate UHMWPE/Molybdenum disulfide composites, using in-situ polymerization. Before carrying out the polymerization process, nanoparticles of molybdenum disulfide underwent various processes such as oxidation, pickling, ultrasonic and thermal shock, in order to increase the interlayer distance and creating functional groups on the surface, then various analyzes, such as XRD, FESEM,...
Viscoelastic dynamics and static responses of a graphene nanoplatelets-reinforced composite cylindrical microshell
, Article Mechanics Based Design of Structures and Machines ; 2020 ; Ghabussi, A ; Ebrahimi, F ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Taylor and Francis Inc
2020
Abstract
In this study, a cylindrical microshell stability reinforced by graphene nanoplatelets is investigated while an axial load is applied uniformly. In addition, viscoelastic foundation covers the composite nanostructure. Therefore, the impacts of the small scale parameter are studied while nonlocal strain gradient theory (NSGT) is considered. The present research deals for the first time with the consideration of viscoelastic, strain–stress size-dependent parameters along with taking into account of various boundary conditions (BCs), especially C-F ones put into effect on the proposed theory. The governing equations (G.Eqs) and BCs have been obtained utilizing energy method and solved with...
Viscoelastic dynamics and static responses of a graphene nanoplatelets-reinforced composite cylindrical microshell
, Article Mechanics Based Design of Structures and Machines ; Volume 50, Issue 2 , 2022 , Pages 509-536 ; 15397734 (ISSN) ; Ghabussi, A ; Ebrahimi, F ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Taylor and Francis Ltd
2022
Abstract
In this study, a cylindrical microshell stability reinforced by graphene nanoplatelets is investigated while an axial load is applied uniformly. In addition, viscoelastic foundation covers the composite nanostructure. Therefore, the impacts of the small scale parameter are studied while nonlocal strain gradient theory (NSGT) is considered. The present research deals for the first time with the consideration of viscoelastic, strain–stress size-dependent parameters along with taking into account of various boundary conditions (BCs), especially C-F ones put into effect on the proposed theory. The governing equations (G.Eqs) and BCs have been obtained utilizing energy method and solved with...
The critical voltage of a GPL-reinforced composite microdisk covered with piezoelectric layer
, Article Engineering with Computers ; 2020 ; Ebrahimi, F ; Elianddy Bin Supeni, E ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Springer
2020
Abstract
In this research, electrically characteristics of a graphene nanoplatelet (GPL)-reinforced composite (GPLRC) microdisk are explored using generalized differential quadrature method. Also, the current microstructure is coupled with a piezoelectric actuator (PIAC). The extended form of Halpin–Tsai micromechanics is used to acquire the elasticity of the structure, whereas the variation of thermal expansion, Poisson’s ratio, and density through the thickness direction is determined by the rule of mixtures. Hamilton’s principle is implemented to establish governing equations and associated boundary conditions of the GPLRC microdisk joint with PIAC. The compatibility conditions are satisfied by...
The critical voltage of a GPL-reinforced composite microdisk covered with piezoelectric layer
, Article Engineering with Computers ; Volume 37, Issue 4 , 2021 , Pages 3489-3508 ; 01770667 (ISSN) ; Ebrahimi, F ; Elianddy Bin Supeni, E ; Habibi, M ; Safarpour, H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
In this research, electrically characteristics of a graphene nanoplatelet (GPL)-reinforced composite (GPLRC) microdisk are explored using generalized differential quadrature method. Also, the current microstructure is coupled with a piezoelectric actuator (PIAC). The extended form of Halpin–Tsai micromechanics is used to acquire the elasticity of the structure, whereas the variation of thermal expansion, Poisson’s ratio, and density through the thickness direction is determined by the rule of mixtures. Hamilton’s principle is implemented to establish governing equations and associated boundary conditions of the GPLRC microdisk joint with PIAC. The compatibility conditions are satisfied by...
A robust keypoint extraction and matching algorithm based on wavelet transform and information theory for point-based registration in endoscopic sinus cavity data
, Article Signal, Image and Video Processing ; 2015 , Pages 1-9 ; 18631703 (ISSN) ; Ahmadian, A ; Kasaei, S ; Sadrehosseini, S. M ; Farnia, P ; Sharif University of Technology
Springer-Verlag London Ltd
2015
Abstract
Feature extraction is one of the most important steps in processing endoscopic data. The extracted features should be invariant to image scale and rotation to provide a robust matching across a substantial range of affine distortions and changes in 3D space. In this study, a method is proposed on the basis of the dual-tree complex wavelet transform. First, a map is estimated for each scale, and then a Gaussian weighted additive function (GWAF) is determined. Keypoints are selected from local peaks of GWAF. The matching and registration are performed by applying normalized mutual information and our modified iterative closest point. Results are reported in terms of robustness to rotation,...
Detecting matrices for random CDMA systems
, Article 2013 20th International Conference on Telecommunications, ICT 2013 ; 2013 ; Bateni, F ; Marvasti, F ; Sharif University of Technology
IEEE Computer Society
2013
Abstract
This paper studies detecting matrices in random dense and sparse Code Division Multiple Access (CDMA) systems. Detecting matrices were originally introduced in the coin weighing problem. Such matrices can be used in CDMA systems in over-loaded scheme where the number of users is greater than the number of chips. We drive some conditions in the large system limit for binary and bipolar random CDMA systems to ensure that any random matrix is a detecting matrix. Furthermore, we extend our results to sparse random ternary matrices that have been using in the sparse CDMA literature. Finally, a construction method for the sparse detecting matrices is introduced
On optimum asymptotic multiuser efficiency of randomly spread CDMA
, Article IEEE Transactions on Information Theory ; Volume 61, Issue 12 , 2015 , Pages 6635-6642 ; 00189448 (ISSN) ; Müller, R. R ; Marvasti, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
We extend the result by Tse and Verdú on the optimum asymptotic multiuser efficiency of randomly spread code division multiple access (CDMA) with binary phase shift keying input. Random Gaussian and random binary antipodal spreading are considered. We obtain the optimum asymptotic multiuser efficiency of a K-user system with spreading gain N when K and N → ∞ and the loading factor, (K/N) , grows logarithmically with K under some conditions. It is shown that the optimum detector in a Gaussian randomly spread CDMA system has a performance close to the single user system at high signal-to-noise ratio when K and N → ∞ and the loading factor, (K/N), is kept less than (log3 K/2). Random binary...
The impact of CO2 injection and pressure changes on asphaltene molecular weight distribution in a heavy crude oil: An experimental study
, Article Petroleum Science and Technology ; Volume 28, Issue 17 , 2010 , Pages 1728-1739 ; 10916466 (ISSN) ; Firoozinia, H ; Kharrat, R ; Ghazanfari, M. H ; Sharif University of Technology
Abstract
This work concerns observing the pressure as well as CO2 mole percentage effects on asphaltene molecular weight distributions at reservoir conditions. A high-pressure, high-temperature asphaltene measurement setup was applied, and the amount of precipitated asphaltene at different pressures as well as CO2 mole percentage in an Iranian heavy crude oil was measured. Moreover, the asphaltene molecular weight distributions during titration of crude oil with different n-alkanes were investigated. The gel permeation chromatography (GPC) apparatus was used for characterization of asphaltene molecular weight under different conditions. It has been observed that some thermodynamic changes such as...
Graphic: Graph-based hierarchical clustering for single-molecule localization microscopy
, Article 18th IEEE International Symposium on Biomedical Imaging, ISBI 2021, 13 April 2021 through 16 April 2021 ; Volume 2021-April , 2021 , Pages 1892-1896 ; 19457928 (ISSN); 9781665412469 (ISBN) ; Aziznejad, S ; Unser, M ; Sage, D ; Sharif University of Technology
IEEE Computer Society
2021
Abstract
We propose a novel method for the clustering of point-cloud data that originate from single-molecule localization microscopy (SMLM). Our scheme has the ability to infer a hierarchical structure from the data. It takes a particular relevance when quantitatively analyzing the biological particles of interest at different scales. It assumes a prior neither on the shape of particles nor on the background noise. Our multiscale clustering pipeline is built upon graph theory. At each scale, we first construct a weighted graph that represents the SMLM data. Next, we find clusters using spectral clustering. We then use the output of this clustering algorithm to build the graph in the next scale; in...
The effect of multiple surface treatments on biological properties of Ti-6Al-4V alloy
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 10 , 2014 , p. 4588-4593 ; Amini, P ; Asgari, S ; Sharif University of Technology
Abstract
In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface...
Statistical evaluation of using the new generation of wind turbines in South Africa
, Article Energy Reports ; Volume 6 , November , 2020 , Pages 2816-2827 ; Jahangiri, M ; Haghani, A ; Hosseini Dehshiri, S. J ; Hosseini Dehshiri, S. S ; Sedaghat, A ; Saghaei, H ; Akinlabi, E. T ; Sichilalu, S. M ; Chowdhury, S ; Techato, K ; Issakhov, A
Elsevier Ltd
2020
Abstract
In the view of the latest status and the potential of developing wind energy in South Africa, the present study aims to perform technical–economic–environmental analysis on a wind turbine system with HOMER software using the 20-years average data of the wind speed obtained from NASA's database, for providing the electricity to residential buildings. The results showed that the Port Elizabeth station, had the lowest levelized cost of electricity (LCOE) with the value of -0.363 $/kWh when using the EOLO wind turbine, and the Bloemfontein station had the highest LCOE with the value of 1.601 $/kWh when using the Turby wind turbine. The results from the step-wise assessment ratio analysis...
HTS transformer windings design using distributive ratios for minimization of short circuit forces
, Article Journal of Superconductivity and Novel Magnetism ; 2018 ; 15571939 (ISSN) ; Vakilian, M ; Hekmati, A ; Fardmanesh, M ; Sharif University of Technology
Springer New York LLC
2018
Abstract
High-temperature superconducting (HTS) transformers have a promising feature in reduction of total weight, total size, and the losses of large-scale distribution transformers. However, the lower leakage reactance of HTS transformers results in a higher short-circuit fault currents and electromagnetic forces. Therefore, optimization of short-circuit electromagnetic forces is one of the crucial aspects in the design of HTS transformers. In this paper, a novel analytical method is proposed for determination of optimum distributive ratios resulting in minimization of these forces for asymmetrical multi-segment windings of an HTS transformer. Employing these distributive ratios, radial and axial...
HTS transformer windings design using distributive ratios for minimization of short circuit forces
, Article Journal of Superconductivity and Novel Magnetism ; Volume 32, Issue 2 , 2019 , Pages 151-158 ; 15571939 (ISSN) ; Vakilian, M ; Hekmati, A ; Fardmanesh, M ; Sharif University of Technology
Springer New York LLC
2019
Abstract
High-temperature superconducting (HTS) transformers have a promising feature in reduction of total weight, total size, and the losses of large-scale distribution transformers. However, the lower leakage reactance of HTS transformers results in a higher short-circuit fault currents and electromagnetic forces. Therefore, optimization of short-circuit electromagnetic forces is one of the crucial aspects in the design of HTS transformers. In this paper, a novel analytical method is proposed for determination of optimum distributive ratios resulting in minimization of these forces for asymmetrical multi-segment windings of an HTS transformer. Employing these distributive ratios, radial and axial...