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Benign and malignant breast tumors classification based on region growing and CNN segmentation
, Article Expert Systems with Applications ; Volume 42, Issue 3 , February , 2014 , Pages 990-1002 ; 09574174 (ISSN) ; Jafari, M ; Kasaei, S ; Keshavarzian, P ; Sharif University of Technology
Elsevier Ltd
2014
Abstract
Breast cancer is regarded as one of the most frequent mortality causes among women. As early detection of breast cancer increases the survival chance, creation of a system to diagnose suspicious masses in mammograms is important. In this paper, two automated methods are presented to diagnose mass types of benign and malignant in mammograms. In the first proposed method, segmentation is done using an automated region growing whose threshold is obtained by a trained artificial neural network (ANN). In the second proposed method, segmentation is performed by a cellular neural network (CNN) whose parameters are determined by a genetic algorithm (GA). Intensity, textural, and shape features are...
Early post-operative performance of an anatomically designed hybrid thread interference screw for ACL reconstruction: A comparative study
, Article Journal of Biomechanics ; Volume 135 , 2022 ; 00219290 (ISSN) ; Chizari, M ; Javad Mortazavi, S. M ; Rouhi, G ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Although the anterior cruciate ligament (ACL) reconstruction using interference screw is a well-accepted surgical procedure, patients still suffer graft failure in the initial rehabilitation phase. Graft fixation stability of a newly designed anatomical hybrid thread tapered interference screw (AHTTIS) was compared with a conventional standard one (CSIS) by conducting in-vitro mechanical tests. According to the CSIS manufacturer's instruction, eight tapered bone tunnels, matching AHTTIS geometry, and eight straight cylindrical tunnels were drilled in artificial bone blocks. Bovine tendon grafts were fixed using AHTTIS and CSIS in their corresponding bone tunnels. Each graft was subjected to...
Stimulation of spinal cord according to recorded theta hippocampal rhythm during rat move on treadmill
, Article Biomedizinische Technik ; Volume 68, Issue 4 , 2023 , Pages 351-360 ; 00135585 (ISSN) ; Rahmani, S ; Shanesazzadeh, F ; Ahmadvand, T ; Namazi, M ; Fardmanesh, M ; Kiani, S ; Sharif University of Technology
De Gruyter Open Ltd
2023
Abstract
Objectives: Several studies have revealed that after spinal cord injury (SCI), in acute and sub-acute phase the spinal cord neurons below the injury are alive and could stimulate by use of electrical pulses. Spinal cord electrical stimulation could generate movement for paralyzed limbs and is a rehabilitation strategy for paralyzed patients. An innovative idea for controlling spinal cord electrical stimulation onset time is presented in current study. Methods: In our method, the time of applying electrical pulse on the spinal cord is according to rat behavioral movement and two movements behaviors are recognized only based on rat EEG theta rhythm on the treadmill line. Briefly, 5 rats were...
Implementation and Evaluation of P3M3 and Wysocki Maturity Models in the South Pars Projects and Presenting Improvement Projects
, M.Sc. Thesis Sharif University of Technology ; Shadrokh, Shahram (Supervisor)
Abstract
This thesis represents results of research about portfolio, program and project management maturity level in South Pars Projects’ contractor organizations. The purpose is to develop an understanding of management maturity regarding these three levels and especially project management in these organizations. Since oil and gas projects have major role in our economy, doing such appraisals cause cost deduction and increasing productivity in these organizations. In this research, contractor organizations and samples from South Pars Projects have been chosen, and then based on P3M3 and Wysocki Maturity Models, which is based on PMBOK standard, and by using their questionnaires appraisal has been...
Solid Phase Dynamic Extraction Based on Polypyrrole Fiber for Determination Trace Amount of Atrazine in Aqueous Samples with GC-MS
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
This research is a bout a novel sample prepration procedure that used polypyrrole film into a stainless steel needle as a fiber coating for solid phase dynamic extraction(SPDE) with using a home-made SPDE devise and gas chromatography – mass spectroscopy for the extraction and detectionof Atrazine from the aqueous sample in direct mode of SPDE. Polypyrrole film was directly electrodeposited into the needle in a aqueous sodium dodecyl sulfonate solution with pecial set up in optimom condition of potential, time and concentration of polypyrrole. To enhance the sensitivity of the SPDE , variables affecting adsorption and desorption steps such as temperature,time,PH, flowrate and ionic strength...
Using a truss-inspired model with the uniform strength optimization theory to predict spongy bone geometry in proximal femur
, Article American Journal of Applied Sciences ; Volume 6, Issue 3 , 2009 , Pages 449-455 ; 15469239 (ISSN) ; Farahmand, F ; Rouhi, G. R ; Sharif University of Technology
2009
Abstract
This paper presents a new naïve approach for simulating bone remodeling process. It is based on the uniform strength theory of optimization and employs a truss-like model for bone. The truss was subjected to external loads including 5 point loads simulating the hip joint contact forces and 3 muscular forces at the attachment sites of the muscles to the bone and the rest are reactions of ligaments. The strain in the links was calculated and the links with high strains were identified. The initial truss is modified by introducing new links wherever the strain exceeds a prescribed or critical value. The critical value was assumed to be equal to an average of the absolute value of strains in the...
Can the body slope of interference screw affect initial stability of reconstructed anterior cruciate ligament?: An in-vitro investigation
, Article BMC Musculoskeletal Disorders ; Volume 22, Issue 1 , 2021 ; 14712474 (ISSN) ; Chizari, M ; Mortazavi, J ; Rouhi, G ; Sharif University of Technology
BioMed Central Ltd
2021
Abstract
Background: Superior biomechanical performance of tapered interference screws, compared with non-tapered screws, with reference to the anterior cruciate ligament (ACL) reconstruction process, has been reported in the literature. However, the effect of tapered interference screw’s body slope on the initial stability of ACL is poorly understood. Thus, the main goal of this study was to investigate the effect of the interference screw’s body slope on the initial stability of the reconstructed ACL. Methods: Based on the best screw-bone tunnel diameter ratios in non-tapered screws, two different tapered interference screws were designed and fabricated. The diameters of both screws were equal to...
The corrosion investigation of rebar embedded in the fibers reinforced concrete
, Article Construction and Building Materials ; Volume 35 , October , 2012 , Pages 564-570 ; 09500618 (ISSN) ; Akil, H. M ; Dolati, A ; Rouhi, J ; Sharif University of Technology
Elsevier
2012
Abstract
One effective method for preventing corrosion of steel reinforcement and improving the mechanical properties of concrete is changing the physical nature of concrete by adding different materials. In this study, we have used polypropylene fibers as an additional material. We have compared the corrosion rate of rebar using different volume ratios and sizes of polypropylene fibers. Reinforcement potential increased as the amount of fibers increased from 0 to 2 kg m -3. The polypropylene fibers delay the initial corrosion process by preventing cracking, thereby decreasing permeability of the concrete. In addition, the corrosion rate of concrete samples made with Kish Island coral aggregate was...
Prediction of shape and internal structure of the proximal femur using a modified level set method for structural topology optimisation
, Article Computer Methods in Biomechanics and Biomedical Engineering ; Volume 15, Issue 8 , 2012 , Pages 835-844 ; 10255842 (ISSN) ; Farahmand, F ; Rouhi, G ; Movahhedy, M. R ; Sharif University of Technology
2012
Abstract
A computational framework was developed to simulate the bone remodelling process as a structural topology optimisation problem. The mathematical formulation of the Level Set technique was extended and then implemented into a coronal plane model of the proximal femur to simulate the remodelling of internal structure and external geometry of bone into the optimal state. Results indicated that the proposed approach could reasonably mimic the major geometrical and material features of the natural bone. Simulation of the internal bone remodelling on the typical gross shape of the proximal femur, resulted in a density distribution pattern with good consistency with that of the natural bone. When...
Modeling the size dependent pull-in instability of cantilever nano-switch immersed in ionic liquid electrolytes using strain gradient theory
, Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 976-989 ; 10263098 (ISSN) ; Koochi, A ; Farahani, M ; Rouhi, E ; Abadyan, M ; Sharif University of Technology
Sharif University of Technology
2016
Abstract
It is well recognized that size-effect often plays a significant role in the mechanical performance of nano-structures. Herein, strain gradient continuum elasticity is employed to investigate the size dependent pull-in instability of the cantilever nanoactuators immersed in ionic liquid electrolyte. The presence of dispersion forces, i.e. Casimir and van der Waals field, is considered in the theoretical model as well as the double-layer electrochemical attraction. To solve the non-linear constitutive equation of the system, two approaches, i.e. the Rayleigh Ritz Method (RRM) and the numerical solution method, are employed. Impact of the size dependency and dispersion forces on the...
2-D Bone Structure Prediction of Proximal Femur and Dominant Joint Load Estimation using Level Set Method and Bone RemodelingTheories
, M.Sc. Thesis Sharif University of Technology ; Farahmand, Farzam (Supervisor) ; Movahhedy, Mohammad Reza (Supervisor) ; Rouhi, Gholamreza (Co-Advisor)
Abstract
Bones adapt their form and structure to make an efficient use of their mass against the applied mechanical loads. So, it is not surprising to assume that the geometry and density distribution of a bone contains information about its loading history. The objective of this work was to develop a framework to simulate the bone remodeling procedure as a topology optimization process and then use this framework to develop a simple technique for estimating the dominant joint loads based on the bone’s density distribution.
At first, the remodeling equation was derived from the structural optimization task of minimizing the strain energy in each time step, using the level set method. Employment...
At first, the remodeling equation was derived from the structural optimization task of minimizing the strain energy in each time step, using the level set method. Employment...
The relationship between an EFL teacher's gender and students' willingness to communicate
, Article International Journal of Communication and Linguistic Studies ; Volume 10, Issue 4 , 2013 , Pages 17-29 ; 23277882 (ISSN) ; Pakzadian, S. S
Common Ground Publishing
2013
Abstract
Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's...
An automated simple algorithm for realistic pore network extraction from micro-tomography images
, Article Journal of Petroleum Science and Engineering ; Vol. 123, issue , 2014 , pp. 164-171 ; ISSN: 09204105 ; Jamshidi, S ; Salehi, S
2014
Abstract
Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images...
Discrimination of heart arrhythmias using novel features in heart rate phase space
, Article Computing in Cardiology ; Volume 40 , Sept , 2013 , Pages 1035-1038 ; 23258861 (ISSN); 9781479908844 (ISBN) ; Rezaei, S ; Salavatian, S
2013
Abstract
In this paper, we try to recognize and distinguish different groups of arrhythmia using novel features which have been obtained from the heart rate's phase space in recent years. For this purpose, we used Triangular Phase Space Mapping (TPSM) and Parabolic Phase Space Mapping (PPSM). For recognition, we used three groups of 15 subjects using the Physionet database (Arrhythmia, Congestive Heart Failure (CHF), and Atrial Fibrillation (AF)) with Normal Sinus Rhythm (NSR). The obtained features discriminate arrhythmia from NSR by p
An intelligent hybrid classification algorithm integrating fuzzy rule-based extraction and harmony search optimization: Medical diagnosis applications
, Article Knowledge-Based Systems ; Volume 220 , 2021 ; 09507051 (ISSN) ; Abdullah, S ; Akhavan Niaki, S. T ; Banihashemi, S ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Uncertainty is a critical factor in medical datasets needed to be overcome for increasing diagnosis efficiency. This paper proposes an intelligent classification algorithm comprising a fuzzy rule-based approach, a harmony search (HS) algorithm, and a heuristic algorithm to classify medical datasets intelligently. Two fuzzy approaches, as well as orthogonal and triangular fuzzy sets, are first utilized to define the attributes of data. Then, an HS algorithm is integrated with a heuristic to generate fuzzy rules to select the best rules in the fuzzy rule-based systems. Moreover, to improve the performance of the proposed classification approach, a three-phase parameter tuning approach is...
Performance evaluation of shared hosting security methods
, Article Proc. of the 11th IEEE Int. Conference on Trust, Security and Privacy in Computing and Communications, TrustCom-2012 - 11th IEEE Int. Conference on Ubiquitous Computing and Communications ; 2012 , Pages 1310-1315 ; 9780769547459 (ISBN) ; Arshad, S ; Khoshkdahan, S ; Sharif University of Technology
2012
Abstract
Shared hosting is a kind of web hosting in which multiple websites reside on one webserver. It is cost-effective and makes the administration easier for websites' owners. However, shared hosting has some performance and security issues. In default shared hosting configuration, all websites' scripts are executed under the webserver's user account regardless of their owners. Therefore, a website is able to access other websites' resources. This security problem arises from lack of proper isolation between different websites hosted on the same webserver. In this survey, we have examined different methods for handling mentioned security issue. Also we evaluated the performance of mentioned...
The behaviour of an artificially cemented sandy gravel
, Article Geotechnical and Geological Engineering ; Volume 23, Issue 5 , 2005 , Pages 537-560 ; 09603182 (ISSN) ; Hosseini, S. M ; Toll, D. G ; Yasrebi, S. S ; Sharif University of Technology
2005
Abstract
The major section of the city of Tehran, Iran has been developed on cemented coarse-grained alluvium. This deposit consists of gravely sand to sandy gravel with some cobbles and is dominantly cemented by carbonaceous materials. In order to understand the mechanical behaviour of this soil, a series of undrained triaxial compression tests and unconfined compression tests were performed on uncemented and artificially cemented samples. Portland cement type I was used as the cementation agent for preparing artificially cemented samples. Uncemented samples and lightly cemented samples (1.5% cement) tested at high confining pressure showed contractive behaviour accompanied with positive excess pore...
An imperialist competitive algorithm approach for multi-objective optimization of direct coupling photovoltaic-electrolyzer systems
, Article International Journal of Hydrogen Energy ; Vol. 39, Issue 33 , 11 November , 2014 , pp. 18743-18757 ; ISSN: 03603199 ; Sayedin, F ; Khavas, S. S
2014
Abstract
In the context of sustainable clean hydrogen production pathways, photovoltaic-electrolyzer systems are one of the most promising alternatives for acquiring hydrogen from renewable energy sources. In fact, determining the optimal set of design and operating variables are always a key issue while coupling directly renewable electricity sources to PEM electrolyzers. Few previous studies have attempted to find the optimal size and operational condition of directly coupled photovoltaic-electrolyzer (PV/El) systems in order to maximize the hydrogen production or to minimize energy transfer loss between photovoltaic devices and the electrolyzer. Nevertheless an easy and efficient approach still...
Kalman filter based packet loss replacement in presence of additive noise
, Article 2012 25th IEEE Canadian Conference on Electrical and Computer Engineering: Vision for a Greener Future, CCECE 2012 ; 2012 ; 9781467314336 (ISBN) ; Ghorshi, S ; Tahaei, A
2012
Abstract
A major problem in real-time packet-based communication systems, is misrouted or delayed packets which results in degraded perceived voice quality. If packets are not available on time, the packets are considered as lost. The easiest solution in a network terminal receiver is to replace silence for the duration of lost speech segments. In a high quality communication system, to avoid degradation in speech quality due to packet loss, a suitable method or algorithm is needed to replace the missing segments of speech. In this paper, we introduce an adaptive filter for replacement of lost speech segment. In this method Kalman filter as a state-space based method will be used to predict the...
Investigation of Mesh Sensitivity Influence to Determine Crack Characteristic by Finite Element Methods
, Article Journal of Failure Analysis and Prevention ; Volume 16, Issue 3 , 2016 , Pages 506-512 ; 15477029 (ISSN) ; Mirjavadi, S. S ; Asli, S. A ; Sharif University of Technology
Springer New York LLC
2016
Abstract
In this research, an extended finite element model has been investigated. Investigation of opening and closure stress always has been one of the difficult parameters to analysis of results; therefore, the utilization of finite element methods would be a good and logical alternative for this purpose. In addition, linear elastic fracture criteria are used for validation of numerical results from the simulation. In this work, a detailed analysis of the influence of different parameters in the results of a specific specimen with a semi-elliptical tooling groove in terms of closure and opening stress is presented, and the impact of optimum element size in fracture characteristic in various load...