Loading...
Search for:
precision
0.007 seconds
Total 126 records
Joint time difference of arrival/angle of arrival position finding in passive radar
, Article IET Radar, Sonar and Navigation ; Volume 3, Issue 2 , 2009 , Pages 167-176 ; 17518784 (ISSN) ; Derakhshani, M ; Sharif University of Technology
2009
Abstract
Several target position finding methods are proposed in various papers mainly regarding sensor networks. However, the problem of position finding in passive radar systems is somewhat different from the general case of sensor networks. Generally, in a passive radar system, there are few receivers located at short distances when compared with the it distance from the target. In this case, a problem known as geometric dilution of precision (GDP) occurs, which considerably increases the error of many proposed methods. This phenomenon can even make the position finding equations non-solvable. Regarding this fact, we have developed a least mean square error (LMSE) based method, which uses both the...
Application of the extended kantorovich method to the static deflection of electrically actuated microplates
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 13, Issue PART A , 2009 , Pages 325-331 ; 9780791848746 (ISBN) ; Moeenfard, H ; Pirbodaghi, T ; Sharif University of Technology
2009
Abstract
The aim of this paper is to present an Extended Kantorovich approach to simulate the static deflection of microplates under electrostatic voltage. The model accounts for the electric force nonlinearity of the excitation. Starting from a one term Galerkin approximation and following the Extended Kantorovich procedure, the equations governing the microplate deflection are obtained. These equations are then solved iteratively with a rapid convergence procedure to yield the desired solution. The results are validated, comparing them with other theoretical results and experimental findings, reported in the literature. It is shown that rapid convergence, high precision and independency of initial...
Persian sentiment lexicon expansion using unsupervised learning methods
, Article 9th International Conference on Computer and Knowledge Engineering, ICCKE 2019, 24 October 2019 through 25 October 2019 ; 2019 , Pages 461-465 ; 9781728150758 (ISBN) ; Hashemi Devin, K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Sentiment analysis, is a subfield of natural language processing that aims at opinion mining to analyze thoughts, orientation and, evaluation of users within some texts. The solution to this problem includes two main steps: extracting aspects and determining users' positive or negative sentiments with respect to the aspects. Two main challenges of sentiment analysis in the Persian language are lack of comprehensive tagged data sets and use of colloquial language in texts. In this paper we propose, a system to specify and extract sentiment words using unsupervised methods in the Persian language that also support colloquial words. Additionally, we also proposed and implemented a state-of-art...
Phase-I monitoring of log-linear model-based processes (a case study in health care: Kidney patients)
, Article Quality and Reliability Engineering International ; Volume 35, Issue 6 , 2019 , Pages 1766-1788 ; 07488017 (ISSN) ; Amiri, A ; Akhavan Niaki, S. T ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
Processes with multiple correlated categorical quality characteristics are called multivariate categorical processes. These processes are usually shown by contingency tables and are characterized by log-linear models. In this paper, two monitoring approaches including likelihood ratio test (LRT) and F test are developed to monitor multivariate categorical processes based on the contingency table in Phase I. In addition, a change point estimator for multivariate categorical processes is developed in Phase I. The performances of the two proposed approaches are evaluated in terms of probability of signal, while the performance of the proposed change point estimator is evaluated in terms of...
Design, analysis, and fabrication of a direct drive permanent NdFeB magnet synchronous motor for precision position control
, Article IET Electric Power Applications ; Volume 14, Issue 8 , 2020 , Pages 1438-1445 ; Damaki Aliabad, A. A ; Ghafarzadeh, M ; Shamlou, S ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Direct drive motors have the excellent ability for precision position control due to their direct connection to load and elimination of the gearbox and pulley backlash. Among the direct drive motors, permanent NdFeB magnet synchronous motors (PMSMs) are the best choice for control systems due to their high efficiency, high power density, good dynamic behaviour, and excellent controllability. This study deals with the design, analysis, and fabrication of a direct drive PMSM for precision position control. To reach this aim, the designed motor should have very low cogging torque and torque ripple to avoid the motor deviation at the target point. To achieve these purposes, at first, a suitable...
Taxonomy learning using compound similarity measure
, Article IEEE/WIC/ACM International Conference on Web Intelligence, WI 2007, Silicon Valley, CA, 2 November 2007 through 5 November 2007 ; January , 2007 , Pages 487-490 ; 0769530265 (ISBN); 9780769530260 (ISBN) ; Alijamaat, A ; Abolhassani, H ; Rahimi, A ; Hoseini, M ; Sharif University of Technology
2007
Abstract
Taxonomy learning is one of the major steps in ontology learning process. Manual construction of taxonomies is a time-consuming and cumbersome task. Recently many researchers have focused on automatic taxonomy learning, but still quality of generated taxonomies is not satisfactory. In this paper we have proposed a new compound similarity measure. This measure is based on both knowledge poor and knowledge rich approaches to find word similarity. We also used Machine Learning Technique (Neural Network model) for combination of several similarity methods. We have compared our method with simple syntactic similarity measure. Our measure considerably improves the precision and recall of automatic...
Fuzzy Adaptive Resonance Theory for content-based data retrieval
, Article 2006 Innovations in Information Technology, IIT, Dubai, 19 November 2006 through 21 November 2006 ; 2006 ; 1424406749 (ISBN); 9781424406746 (ISBN) ; Akbari, H ; Akbarzadeh-T., M. R ; Sharif University of Technology
2006
Abstract
In this paper we propose a content-based text and image retrieval architecture using Fuzzy Adaptive Resonance Theory neural network. This method is equipped with an unsupervised mechanism for dynamic data clustering to deal with incremental information without metadata such as in web environment. Results show noticeable average precision and recall over search results. © 2006 IEEE
Inductance calculation of HTS transformers with multi-segment windings considering insulation constraints
, Article Journal of Superconductivity and Novel Magnetism ; Volume 34, Issue 5 , 2021 , Pages 1329-1339 ; 15571939 (ISSN) ; Vakilian, M ; Hekmati, A ; Fardmanesh, M ; Sharif University of Technology
Springer
2021
Abstract
High-temperature superconducting (HTS) transformers with multi-segment windings have been proposed in earlier literatures for the hysteresis loss reduction and short circuit electromagnetic force mitigation. The optimum distributive ratios for these multi-segment windings have been determined in earlier literatures. Asymmetrical seven segment winding with its optimum distributive ratio (k = 1/12) results in minimization of short circuit electromagnetic forces under normal tap and any adjusted tap. However, insulation design and leakage inductance calculation for the multi-segment winding of an HTS transformer have not been addressed in past literatures. Insulation design is one of the most...
A cordic-based processor extension for scalar and vector processing
, Article 19th IEEE International Parallel and Distributed Processing Symposium, IPDPS 2005, Denver, CO, 4 April 2005 through 8 April 2005 ; Volume 2005 , 2005 ; 0769523129 (ISBN); 0769523129 (ISBN); 9780769523125 (ISBN) ; Fazeli, M ; Sarbazi Azad, H ; Sharif University of Technology
2005
Abstract
Trigonometric calculations play a significant role in scientific and multimedia applications. Such applications usually use vectors of data, thus it is essential to use SIMD-based computing for them. State of the art processors such as Pentium family processors have SIMD capabilities, MMX, SSE and SSE2 to name a few. But these extensions usually come short of performing trigonometric functions calculation. This paper presents a CORDIC-based vector processor extension to accelerate trigonometric calculations. The suggested architecture works with a vector of data, as well as scalar data. This architecture has been Synthesized both for FPGA and ASIC and the results have shown a significant...
Evaluation of some exponential random number generators implemented by FPGA
, Article IASTED International Conference on Parallel and Distributed Computing and Networks, as part of the 23rd IASTED International Multi-Conference on Applied Informatics, Innsbruck, 15 February 2005 through 17 February 2005 ; 2005 , Pages 578-583 ; 10272666 (ISSN) ; Miremadi, S. G ; Ejlali, A. R ; Fahringer T ; Hamza M. H ; Sharif University of Technology
2005
Abstract
Normally, random number generators produce uniformly distributed values. In some cases, such as Monte Carlo simulation, non-uniform distributed values (e.g. exponential distribution and weibull distribution) are required. One way of producing non-uniformly distributed random values, is to add an extra hardware to a uniformly distributed random number generator. In this paper, three different methods are studied to generate exponential random values. These methods are based oft three algorithm of logarithm evaluating namely: CORDIC, Interpolation and Piecewise lookup table. The study is based on an experimental evaluation of the above methods, using FPGA chips, to compare the speed, hardware...
Generalized equivalent circuit model for analysis of graphene/metal-based plasmonic metasurfaces using Floquet expansion
, Article Optics Express ; Volume 30, Issue 20 , 2022 , Pages 35486-35499 ; 10944087 (ISSN) ; Memarian, M ; Khavasi, A ; Sharif University of Technology
Optica Publishing Group (formerly OSA)
2022
Abstract
Due to the wide range of applications of metal/graphene-based plasmonic metasurfaces (sensors, absorbers, polarizers), it has become essential to provide an analytical method for modeling these structures. An analytical solution simplified into a circuit model, in addition to greatly reducing the simulation time, can become an essential tool for designing and predicting the behaviors of these structures. This paper presents a high-precision equivalent circuit model to study these structures in one-dimensional and two-dimensional periodic arrays. In the developed model, metallic patches similar to graphene patches are modeled as surface conductivity and with the help of current modes induced...
Precision measurement of a brown dwarf mass in a binary system in the microlensing event: OGLE-2019-BLG-0033/MOA-2019-BLG-035
, Article Astronomy and Astrophysics ; Volume 663 , 2022 ; 00046361 (ISSN) ; Udalski, A ; Bozza, V ; Rota, P ; Bond, I. A ; Yee, J. C ; Sajadian, S ; Mróz, P ; Poleski, R ; Skowron, J ; Szymanski, M. K ; Soszynski, I ; Pietrukowicz, P ; Kozlowski, S ; Ulaczyk, K ; Rybicki, K. A ; Iwanek, P ; Wrona, M ; Gromadzki, M ; Abe, F ; Barry, R ; Bennett, D. P ; Bhattacharya, A ; Fukui, A ; Fujii, H ; Hirao, Y ; Itow, Y ; Kirikawa, R ; Kondo, I ; Koshimoto, N ; Matsubara, Y ; Matsumoto, S ; Miyazaki, S ; Muraki, Y ; Olmschenk, G ; Ranc, C ; Okamura, A ; Rattenbury, N. J ; Satoh, Y ; Sumi, T ; Suzuki, D ; Silva, S. I ; Toda, T ; Tristram, P. J ; Vandorou, A ; Yama, H ; Beichman, C. A ; Bryden, G ; Novati, S. C ; Carey, S ; Gaudi, B. S ; Gould, A ; Henderson, C. B ; Johnson, S ; Shvartzvald, Y ; Zhu, W ; Dominik, M ; Hundertmark, M ; Jørgensen, U. G ; Longa-Peña, P ; Skottfelt, J ; Tregloan-Reed, J ; Bach-Møller, N ; Burgdorf, M ; D'Ago, G ; Haikala, L ; Hitchcock, J ; Khalouei, E ; Peixinho, N ; Rahvar, S ; Snodgrass, C ; Southworth, J ; Spyratos, P ; Zang, W ; Yang, H ; Mao, S ; Bachelet, E ; Maoz, D ; Street, R. A ; Tsapras, Y ; Christie, G. W ; Cooper, T ; De Almeida, L ; Do Nascimento, J.-D ; Green, J ; Han, C ; Hennerley, S ; Marmont, A ; McCormick, J ; Monard, L. A. G ; Natusch, T ; Pogge, R ; Sharif University of Technology
EDP Sciences
2022
Abstract
Context. Brown dwarfs are transition objects between stars and planets that are still poorly understood, for which several competing mechanisms have been proposed to describe their formation. Mass measurements are generally difficult to carry out for isolated objects as well as for brown dwarfs orbiting low-mass stars, which are often too faint for a spectroscopic follow-up. Aims. Microlensing provides an alternative tool for the discovery and investigation of such faint systems. Here, we present an analysis of the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035, which is caused by a binary system composed of a brown dwarf orbiting a red dwarf. Methods. Thanks to extensive ground...
3D simulation of solutes concentration in urinary concentration mechanism in rat renal medulla
, Article Mathematical Biosciences ; Volume 308 , 2019 , Pages 59-69 ; 00255564 (ISSN) ; Abdekhodaie, M. J ; Farhadi, F ; Shafiee, M. A ; Sharif University of Technology
Elsevier Inc
2019
Abstract
In this work, a mathematical model was developed to simulate the urinary concentration mechanism. A 3-D geometry was derived based on the detail physiological pictures of rat kidney. The approximate region of each tubule was obtained from the volume distribution of structures based on Walter Pfaller's monograph and Layton's region-based model. Mass and momentum balances were applied to solve for the change in solutes concentration and osmolality. The osmolality of short and long descending nephrons at the end of the outer medulla was obtained to be 530 mOsmol/kgH2O and 802 mOsmol/kgH2O, respectively, which were in acceptable agreement with experimental data. The fluid osmolality of the short...
Investigation of Quantum States of Light (Generation and Utilization Their Special Properties) in Quantum Information Science and Precision Measurements
, M.Sc. Thesis Sharif University of Technology ; Karimipour, Vahid (Supervisor)
Abstract
Quantum entanglement and superposition are wonderful and mysterious phenomena of quantum mechanics. By means of quantum entanglement, two or more systems become partner in state of each other . As a result, measurements on each of these systems affect the status of other systems. Quantum superposition allows a system inhabits several of its possible quantum states simultaneously. These two features are applicable in many technologies in present age. Photons, as an quantum unit of light, are appropriate candidate for utilization these properties. Because they are robust to decoherence and for their preparation exist various methods. Hence, we interested to generation of quantum states of...
An investigation on the dynamic response of the shaking table steel deck using finite element
, Article 11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014 ; 2014 , pp. 1330-1340 ; ISBN: 9788494284472 ; Farzanian, K ; Taheri, E ; Sharif University of Technology
Abstract
This paper presents the results of an analytical study on the dynamic characteristics of the Shaking Table facilities at Sharif University. This 3 degree of freedom shaking table is driven by 3 servo-control hydraulic actuators, and consists of a 12 ton, 4m×4m×0.6m steel deck. The main objective of this investigation is to identify the degree of flexibility of the deck, and its adverse effects in causing errors in the simulation of seismic effects on different structural specimens. Many frame specimens of different weights and configurations are subjected to seismic motions, and their responses are calculated using FE models. Some of these models were designed to account for eccentric...
Using a classifier pool in accuracy based tracking of recurring concepts in data stream classification
, Article Evolving Systems ; Volume 4, Issue 1 , 2013 , Pages 43-60 ; 18686478 (ISSN) ; Ahmadi, Z ; Beigy, H ; Sharif University of Technology
2013
Abstract
Data streams have some unique properties which make them applicable in precise modeling of many real data mining applications. The most challenging property of data streams is the occurrence of "concept drift". Recurring concepts is a type of concept drift which can be seen in most of real world problems. Detecting recurring concepts makes it possible to exploit previous knowledge obtained in the learning process. This leads to quick adaptation of the learner whenever a concept reappears. In this paper, we propose a learning algorithm called Pool and Accuracy based Stream Classification with some variations, which takes the advantage of maintaining a pool of classifiers to track recurring...
Solution of population balance equations in emulsion polymerization using method of moments
, Article Chemical Engineering Communications ; Volume 200, Issue 1 , 2013 , Pages 20-49 ; 00986445 (ISSN) ; Shahrokhi, M ; Abedini, H ; Sharif University of Technology
2013
Abstract
In this work, the method of moments is used for solution of population balance equations appearing in modeling of emulsion polymerization (EP). The zero-one model without coagulation effect and the pseudo-bulk model including coagulation effect are investigated as two common approaches for modeling EP processes. The fixed quadrature method is used to close the set of moment equations, and the maximum entropy approach is applied to reconstruct the particle size distribution from a finite number of its moments. Comparing the results with those obtained by the high-precision finite volume technique indicates that, despite the low computational load of the moment method, it has an acceptable...
Investigation of ultrasonic-assisted drilling of Al/SiC metal matrix composite with Taguchi method
, Article Key Engineering Materials ; Volume 523-524 , 2012 , Pages 215-219 ; 10139826 (ISSN) ; 9783037855096 (ISBN) ; Akbari, J ; Yousefi, R ; Sharif University of Technology
2012
Abstract
Burr in drilling plays an important role on product quality, so analysis the burr height is essential at the final production. This paper presents the application of Taguchi method for survey the burr height by adding ultrasonic vibration to the process. In this paper L18 orthogonal array based on Taguchi techniques was used in the design of experiments. Analysis of Variance (ANOVA) was used to determination the effect of drilling parameter on burr formation. Influence of spindle speed, feed rate and percentage of SiC particle was investigated in with and without ultrasonic assisted drilling. In this paper drilling of Al/SiCp MMCs with 5, 15 and 20 wt% of particulate SiC in dry drilling...
Reduced memory requirement in hardware implementation of SVM classifiers
, Article ICEE 2012 - 20th Iranian Conference on Electrical Engineering, 15 May 2012 through 17 May 2012 ; May , 2012 , Pages 46-50 ; 9781467311489 (ISBN) ; Gholampour, I ; Sharif University of Technology
2012
Abstract
Support Vector Machine (SVM) is a powerful machine-learning tool for pattern recognition, decision making and classification. SVM classifiers outperform other classification technologies in many applications. In this paper, two implementations of SVM classifiers are presented using Logarithmic Number System. In the basic classifier all operations (multiplication, addition and ...) are performed using logarithmic numbers. In the logarithmic domain, multiplication and division can be simply treated as addition or subtraction respectively. The main disadvantage of LNS is the large memory requirement for high precision addition and subtraction. In the improved classifier, multiplication...
An analytical 3-D model for calculating eddy-current damping force for a magnetic levitation system with permanent magnet
, Article IEEE Transactions on Magnetics ; Volume 48, Issue 9 , Sept , 2012 , Pages 2472-2478 ; 00189464 (ISSN) ; Khodabakhsh, M ; Vossoughi, G ; Sharif University of Technology
IEEE
2012
Abstract
An analytical solution for obtaining steady-state eddy-current-based force on a levitated permanent magnet above a plate with linear conductivity in the field of an electromagnet having cylindrical symmetry is presented in this paper. In literature, the force due to eddy current in this levitation system have been used for high precision positioning of a levitated permanent magnet without providing an explicit analytical model. In this system, a change in the coil's current and also the motion of the levitated permanent magnet in 3-D space generate eddy current in the plate. A novel explicit solution for obtaining damping forces due to these eddy currents is obtained as a function of...