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Locomotion modes of a novel piezo-driven microrobot: Analytical modeling and performance evaluation
, Article Mechanism and Machine Theory ; Volume 52 , 2012 , Pages 248-266 ; 0094114X (ISSN) ; Vossoughi, G. R ; Sharif University of Technology
2012
Abstract
This paper presents a novel, sliding, A-shaped microrobot with nanometric resolution for precision positioning applications. The microrobot is actuated near its natural frequency using a piezoelectric stack actuator to produce translational motion. The dynamic modeling of the mechanism is based on the assumptions of the linear piezoelectric behavior and the Coulomb friction model. Using this model the required condition for generating net motion is found. The suitability of three simple, friction-based locomotion modes for implementation on the proposed device is addressed. Influences of some important configuration parameters on the behavior of the microrobot, based on defined criteria, are...
HBIR: Hypercube-based image retrieval
, Article Journal of Computer Science and Technology ; Volume 27, Issue 1 , January , 2012 , Pages 147-162 ; 10009000 (ISSN) ; Lakdashti, A ; Sharif University of Technology
Abstract
In this paper, we propose a mapping from low level feature space to the semantic space drawn by the users through relevance feedback to enhance the performance of current content based image retrieval (CBIR) systems. The proposed approach makes a rule base for its inference and configures it using the feedbacks gathered from users during the life cycle of the system. Each rule makes a hypercube (HC) in the feature space corresponding to a semantic concept in the semantic space. Both short and long term strategies are taken to improve the accuracy of the system in response to each feedback of the user and gradually bridge the semantic gap. A scoring paradigm is designed to determine the...
Matrix analysis of nonlinear trusses using Prandtl-2 neural networks
, Article Journal of Sound and Vibration ; Volume 330, Issue 20 , 2011 , Pages 4813-4826 ; 0022460X (ISSN) ; Farrokh, M ; Sharif University of Technology
2011
Abstract
A new method, based on the concepts of matrix analysis as well as the learning capabilities of neural networks, for the analysis of nonlinear trusses under dynamic loading is presented. The method can be applied to static trusses too. While there have been attempts in the past to use neural networks to identify and model different structures based on data measured on structural response directly, the main feature and advantage of this new method is in its capability to model a nonlinear truss by assembling the data collected on the response of its members. The basics of the method are: (1) for each truss member, a neural network is trained to learn and simulate its loadresponse behavior, (2)...
A much lower density for the transiting extrasolar planet WASP-7: (Research Note)
, Article Astronomy and Astrophysics ; Volume 527, Issue 1 , 2011 ; 00046361 (ISSN) ; Dominik, M ; Jørgensen, U. G ; Rahvar, S ; Snodgrass, C ; Alsubai, K ; Bozza, V ; Browne, P ; Burgdorf, M ; Novati, S. C ; Dodds, P ; Dreizler, S ; Finet, F ; Gerner, T ; Hardis, S ; Harpsøe, K ; Hellier, C ; Hinse, T. C ; Hundertmark, M ; Kains, N ; Kerins, E ; Liebig, C ; Mancini, L ; Mathiasen, M ; Penny, M.T ; Proft, S ; Ricci, D ; Sahu, K ; Scarpetta, G ; Schäfer, S ; SchOnebeck, F ; Surdej, J ; Sharif University of Technology
Abstract
We present the first high-precision photometry of the transiting extrasolar planetary system WASP-7, obtained using telescope defocussing techniques and reaching a scatter of 0.68 mmag per point. We find that the transit depth is greater and that the host star is more evolved than previously thought. The planet has a significantly larger radius (1.330 ± 0.093 RJup versus 0.915+0.046 -0.040 RJup) and much lower density (0.41 ± 0.10 pJup versus 1.26+0.25 -0.21 pJup) and surface gravity (13.4 ± 2.6ms-2 versus 26.4+4.4 -4.0 ms-2) than previous measurements showed. Based on the revised properties it is no longer an outlier in planetary mass-radius and period-gravity diagrams. We also obtain a...
An intelligent modeling approach for prediction of thermal conductivity of CO2
, Article Journal of Natural Gas Science and Engineering ; Volume 27 , November , 2015 , Pages 138-150 ; 18755100 (ISSN) ; Esmaili, S ; Rashid, S ; Suleymani, M ; Sharif University of Technology
Elsevier
2015
Abstract
In the design of a carbon dioxide capture and storage (CCS) process, the thermal conductivity of carbon dioxide is of special concern. Hence, it is quite important to search for a quick and accurate determination of thermal conductivity of CO2 for precise modeling and evaluation of such a process. To achieve this aim, a robust computing methodology, entitled least square support vector machine (LSSVM) modeling, which is coupled with an optimization approach, was used to model this transport property. The model was constructed and evaluated employing a comprehensive data bank (more than 550 data series) covering wide ranges of pressures and temperatures. Before constructing the model, outlier...
Challenges of fluid phase behavior modeling in Iranian retrograde gas condensate reservoirs
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 37, Issue 6 , Feb , 2015 , Pages 663-669 ; 15567036 (ISSN) ; Asadi, E ; Nasiri, M ; Khajenoori, L ; Masihi, M ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Production from gas condensate reservoirs requires precise determination of reservoir fluid properties along with their positive impact on real reservoir performance evaluation and fluid in place volume calculation. This fact is particularly important because liquid drop out phenomena occurs as a result of pressure drop due to fluid production and condensate remains in reservoir [Mohebzadeh, 2005. In this study the challenges and problems of fluid phase behavior simulation in southern Iranian retrograde gas condensate reservoirs is discussed. Most of the problems and challenges are inaccuracy of equation of states near the critical point, special conditions and produced fluid flow...
Bug localization using revision log analysis and open bug repository text categorization
, Article 6th International IFIP WG 2.13 Conference on Open Source Systems, OSS 2010, Notre Dame, IN, 30 May 2010 through 2 June 2010 ; Volume 319 AICT , 2010 , Pages 188-199 ; 18684238 (ISSN) ; 9783642132438 (ISBN) ; Khansari, M ; Sharif University of Technology
2010
Abstract
In this paper, we present a new approach to localize a bug in the software source file hierarchy. The proposed approach uses log files of the revision control system and bug reports information in open bug repository of open source projects to train a Support Vector Machine (SVM) classifier. Our approach employs textual information in summary and description of bugs reported to the bug repository, in order to form machine learning features. The class labels are revision paths of fixed issues, as recorded in the log file of the revision control system. Given an unseen bug instance, the trained classifier can predict which part of the software source file hierarchy (revision path) is more...
Air pressure dependence of natural-convection heat transfer
, Article World Congress on Engineering 2010, WCE 2010, London, 30 June 2010 through 2 July 2010 ; Volume 2 , 2010 , Pages 1444-1447 ; 9789881821072 (ISBN) ; Abardeh, R. H ; Sharif University of Technology
2010
Abstract
Heat transfer is one of the prevalent concepts with many usages in different fields of science, industry and so on. In different applications we need more or less to know about this phenomenon. Control of this phenomenon is too important in some cases and we should be aware how to control it. The importance of heat transfer rate and effect of various parameters on it, is a reason of performing this research. Because of changes of air pressure in different applications, we need to know how heat transfer affected by air pressure. In different places air pressure is higher or lower than atmospheric pressure and we can't use more of experimental equations (e.g. Morgan or Churchill-Chu for a...
Lexical pattern generalization for ontology learning and population: A survey
, Article Proceedings of the International MultiConference of Engineers and Computer Scientists 2010, IMECS 2010, 17 March 2010 through 19 March 2010 ; 2010 , Pages 551-554 ; 9789881701282 (ISBN) ; Sayadiharikandeh, M ; Zibanezhad, B ; Sharif University of Technology
Abstract
Information extraction and refinement systems rely on a set of extraction patterns in pattern based approaches in order to construct taxonomies and finding instances of concepts in a corpus. Pattern based methods have high precision and suffer from low recall. Pattern generalization and modeling techniques can increase matching power and decrease GAP between training and test data
Investigation on train derailment using a new criterion
, Article Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference 2009, DETC2009, 30 August 2009 through 2 September 2009 ; Volume 4, Issue PART C , September , 2010 , Pages 1837-1842 ; 9780791849019 (ISBN) ; Jalili, M. M ; Sharif University of Technology
2010
Abstract
A new criterion for prediction of train derailment is presented in this paper. A 2 DOF wheel-set model is used to identify the main dynamic parameters that affect wheel-set derailment. Using these parameters and conventional definition of derailment coefficient, a new criterion for prediction of wheelset derailment is introduced. The proposed criterion, in addition to providing the required precision in prediction of wheelset derailment, it requires measurements which are easy to perform. To evaluate the capability of the new criterion in prediction of derailment, a full wagon model with 48 DOF was used. The wagon model is a 3-D, non-linear model of a train passenger car. The model includes...
Robust velocity control for an A-shaped micro-robot with stick-slip locomotion
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 230, Issue 14 , 2016 , Pages 2413-2426 ; 09544062 (ISSN) ; Vossoughi, G. R ; Sharif University of Technology
SAGE Publications Ltd
Abstract
In this paper, the problem of velocity control of a micro-robot's locomotion with nanometric resolution has been investigated. A sliding, A-shaped micro-robot, used in precision positioning applications is analyzed. This micro-robot is actuated by means of a piezoelectric stack actuator in order to produce translational and periodic motion. A dynamic model of the robot is proposed assuming linear behavior for the piezoelectric stack and Coulomb friction model. Then, in order to control the velocity of micro-robot, first a robust sliding mode control is used so that the relative angle between the legs in the micro-robot tracks a periodic reference signal. The velocity tracking for the...
A new brushless synchro with look-up table error compensation
, Article International Journal of Numerical Modelling: Electronic Networks, Devices and Fields ; Volume 29, Issue 4 , 2016 , Pages 577-591 ; 08943370 (ISSN) ; Kamali, A ; Damaki Aliabad, A ; Abedini, R ; Tajeddini, M. A ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
In synchros and resolvers, brushes, and slip-rings produce a lot of noise in the output signal. Compared to encoders, the application of such position sensors in precision control systems is restricted because of their low accuracy. In this paper, a novel scheme of a brushless synchro is introduced. In this scheme, the primary and secondary windings are mounted on the stator, and the stator magnetic flux passes a certain path in the rotor with inducing voltage in the secondary winding. In this paper, a software method based on simple look-up table is used to enhance accuracy and reliability of the output signal of the proposed synchro. The operation principle of the brushless synchro is...
A novel architecture of pseudorandom dithered MASH digital delta-sigma modulator with lower spur
, Article Journal of Circuits, Systems and Computers ; Volume 25, Issue 7 , 2016 ; 02181266 (ISSN) ; Frashidi, E ; Sadughi, S ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
Abstract
A Digital Delta Sigma Modulator (DDSM) is a Finite State Machine (FSM); it is implemented using finite precision arithmetic units and the number of available states is finite. The DDSM always produces a periodic output signal when the input is constant. This paper proposes a novel method of applying periodic dither to a DDSM in order to obtain minimized spurious tones. The effects of adding the pseudorandom dither signal in different stages within the proposed Multi-Stage noise Shaping (MASH) modulator are expressed in the equations, and the results are compared. We present results regarding the periodicity of the quantization noise produced by a MASH modulator with a constant input and a...
Investigation on train derailment using a new criterion
, Article Proceedings of the ASME Design Engineering Technical Conference, 30 August 2009 through 2 September 2009, San Diego, CA ; Volume 4, Issue PARTS A, B AND C , 2009 , Pages 1837-1842 ; 9780791849019 (ISBN) ; Jalili, M. M ; Sharif University of Technology
Abstract
A new criterion for prediction of train derailment is presented in this paper. A 2 DOF wheel-set model is used to identify the main dynamic parameters that affect wheel-set derailment. Using these parameters and conventional definition of derailment coefficient, a new criterion for prediction of wheelset derailment is introduced. The proposed criterion, in addition to providing the required precision in prediction of wheelset derailment, it requires measurements which are easy to perform. To evaluate the capability of the new criterion in prediction of derailment, a full wagon model with 48 DOF was used. The wagon model is a 3-D, non-linear model of a train passenger car. The model includes...
Semi-reversible quantization based data hiding using missing samples recovery technique
, Article 16th International Conference on Telecommunications, ICT 2009, 25 May 2009 through 27 May 2009 ; 2009 , Pages 298-302 ; 9781424429370 (ISBN) ; Saberian, M. J ; Akhaee, M. A ; Marvasti, F ; Sharif University of Technology
Abstract
A blind semi-invertible quantization based data hiding scheme, which reconstructs the original signal with high precision has been proposed. In order to produce correlated quantization yielding reversibility of the quantization based approach, a new transform domain has been introduced. In decoder, by compensating the quantization error and using the iterative technique, the original signal is recovered; then the watermarked signal is compared with the reconstructed original signal and hidden data is retrieved. Simulation results show that the proposed method in comparison with other reversible methods imposes less distortion and thus a higher Signal to Noise Ratio (SNR) is achieved. © 2009...
Application of MLP-ANN strategy to predict higher heating value of biomass in terms of proximate analysis
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 39, Issue 22 , 2017 , Pages 2105-2111 ; 15567036 (ISSN) ; Zanbouri, H ; Bemani, A ; Hamule, T ; Sharif University of Technology
Abstract
One of the important parameters in development of bioenergy industry and economical investigation of fuels is higher heating value (HHV) of biomass in the present study; multi-layer perceptron (MLP) artificial neural network was applied to predict HHV of biomass in terms of volatile matters (VMs), fixed carbon (FC), and ash content (ASH). The purposed algorithm was trained and tested by utilizing 350 experimental data points which extracted from literature. Based on results, the MLP-ANN has great ability to estimate HHV for biomass. This method can be developed as a user-friendly software for prediction of HHV of the fuel in terms of proximate analysis. The predicting software can be wide...
Video event recognition leveraging hierarchy of semantic concepts
, Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 1549-1553 ; 9781509059638 (ISBN) ; Ghaemmaghami, S ; Sharif University of Technology
Abstract
A new method for exploiting the semantic hierarchical structure of visual concepts in video event recognition task is proposed in this paper. The visual concepts are detected using the readily available Convolutional Neural Network (CNN) structures which make the recognition system extremely efficient in cases with limited hardware resources. The employed CNNs assign scores to each of the predetermined visual concepts in each video frame and the resulting concept scores are fed to the proposed hierarchical post-processing scheme. Our post-processing module takes advantage of the semantic hierarchy of the concepts to enhance the recognition accuracy of event recognition. The hierarchical...
A high-voltage pulse generator with continuously variable pulsewidth based on a modified PFN
, Article IEEE Transactions on Plasma Science ; Volume 45, Issue 5 , 2017 , Pages 849-858 ; 00933813 (ISSN) ; Zarghany, M ; Aghaei, M ; Kaboli, S ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
The amount of stored energy is an important issue in the low-droop and high-precision pulse generation. Pulse forming network (PFN) simulating an open-ended transmission line seems to be useful due to its minimum stored energy. The drawbacks of the PFN include low-output pulse quality and constant pulsewidth, which limit their applications. Another limitation of generating rectangular pulses using PFN is that half of the charged voltage appears in the output when delivering the entire stored energy to the matched load. This paper proposes a structure of PFN-based pulse generator that overcomes the above-mentioned limitations. For continuous pulsewidth adjustment, a lossless scheme is...
Evaluation of planing craft maneuverability using mathematical modeling under the action of the rudder
, Article Scientia Iranica ; Volume 24, Issue 1 , 2017 , Pages 293-301 ; 10263098 (ISSN) ; Seif, M. S ; Mehdigholi, H ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
In the recent years, different mathematical models have been suggested for maneuvering of displacement vessels, which are capable to estimate maneuvering of the vessel with acceptable precision. But, simulation of planing craft maneuverability through a mathematical model has not been developed yet. In this paper, a mathematical model is developed for maneuvering of the planing craft by including the rudder forces and moments. Different maneuvers, such as straight-line stability, course keeping, and turning circle, are executed through the mathematical model. Simulation results are validated with the published experimental results and it is shown that they are in good agreement. Finally, the...
Detection of ammonia gas by knudsen thermal force in micro gas actuator
, Article Case Studies in Thermal Engineering ; Volume 12 , 2018 , Pages 276-284 ; 2214157X (ISSN) ; Barzegar Gerdroodbary, M ; Mosavat, M ; Ganji, D. D ; Sharif University of Technology
Abstract
Direct Simulation Monte Carlo (DSMC) method is applied to evaluate the performance of a new micro gas sensor (MIKRA) for mass analysis of ammonia in the rarefied gas. In order to simulate a rarefied gas inside the micro gas detector, Boltzmann equation is applied to obtain high precision results. This study performed comprehensive studies to reveal the main mechanism of force generation and applied this for the analysis of the gas mixture. Our findings show that value of generated Knudsen force significantly varies when the percentage of the NH3 varies in the mixture. According to obtained results, the maximum Knudsen force increases when the fraction of the ammonia decreases. Our findings...