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sensitivity-analysis
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Neural network and neuro-fuzzy assessments for scour depth around bridge piers
, Article Engineering Applications of Artificial Intelligence ; Volume 20, Issue 3 , 2007 , Pages 401-414 ; 09521976 (ISSN) ; Borghei, S. M ; Jeng, D. S ; Sharif University of Technology
2007
Abstract
The mechanism of flow around a pier structure is so complicated that it is difficult to establish a general empirical model to provide accurate estimation for scour. Interestingly, each of the proposed empirical formula yields good results for a particular data set. Hence, in this study, alternative approaches, artificial neural networks (ANNs) and adaptive neuro-fuzzy inference system (ANFIS), are proposed to estimate the equilibrium and time-dependent scour depth with numerous reliable data base. Two ANN models, multi-layer perception using back-propagation algorithm (MLP/BP) and radial basis using orthogonal least-squares algorithm (RBF/OLS), were used. The equilibrium scour depth was...
Oxygen sensing based on the oxidation process in resorufin dye
, Article Sensors and Actuators, B: Chemical ; Volume 122, Issue 1 , 2007 , Pages 109-117 ; 09254005 (ISSN) ; Razani, M ; Sharif University of Technology
2007
Abstract
By using the planar laser induced florescence experiment (PLIF), a resorufin (RSRF) dye solution was tested as an oxygen probe. The photoreaction of RSRF dye was investigated and the oxidation process of this fluorescent probe molecule was demonstrated. The effect of the oxygen bubbles on tracing dissolved oxygen was also investigated in this study. Results obtained for this sensitive molecular probe dye are very interesting and verify that such an agent can be used effectively for investigating different interesting phenomena affecting the fluorescence. The temporal and spatial behaviors of the oxidation and fluorescence processes were described in this report. For a delay time of 4500 ms...
Effect of geometry and foundation conditions on the accuracy of the steady state seepage analysis results for rockfill dams
, Article Scientia Iranica ; Volume 14, Issue 3 , 2007 , Pages 212-220 ; 10263098 (ISSN) ; Soleimanbeigi, A ; Sharif University of Technology
Sharif University of Technology
2007
Abstract
One of the most important concerns in designing an embankment dam is seepage analysis. Conventional seepage analyses of embankment dams are performed in two-dimensional (2D) space, in which the impacts of water flow lines seeping from the side abutments are ignored. This fact is especially important if the dam is constructed in a narrow valley. In addition, if the effects of existing underlain faults in the reservoir water discharge rate, under different loading conditions, are to be scrutinized, three-dimensional (3D) modeling of the dam for seepage analysis is inevitable. In this paper, the significance of three-dimensional seepage analyses is emphasized by making a 3D model of a real dam...
Optimization of a mcpherson suspension system using the design of experiments method
, Article SAE Automotive Dynamics, Stability and Controls Conference and Exhibition, Novi, MI, 14 February 2006 through 16 February 2006 ; 2006 ; 01487191 (ISSN) ; Mirzadeh, O ; Azadi, S ; Sharif University of Technology
SAE International
2006
Abstract
In this research, the handling behavior of an intermediate class passenger car has been optimized by altering its front suspension parameters. For this purpose, a validated virtual model of the car, constructed by Adams/Car software, has been used. The utilized objective function is a combination of eight criteria indicating handling characteristics of the car. To reduce the amount of optimization parameters, a sensitivity analysis has been done by implementing the Design of Experiments method capabilities. Optimization has been done using the Response Surface Method. The obtained optimization results show a considerable improvement in the system response. Copyright © 2006 SAE International
Fuzzy edge preserving smoothing filter using robust region growing
, Article 2006 IEEE International Conference on Fuzzy Systems, Vancouver, BC, 16 July 2006 through 21 July 2006 ; 2006 , Pages 1748-1755 ; 10987584 (ISSN); 0780394887 (ISBN); 9780780394889 (ISBN) ; Vahdat, S ; Soltanian Zadeh, H ; Sharif University of Technology
2006
Abstract
Smoothing, while preserving edges, has always been a major challenge in image processing. In this paper, we propose a new approach that uses segmentation in order to avoid inter-region smoothing thus preserving the edges. It is common to smooth the image prior to region growing. The opposite procedure does not work properly in the presence of noise since region growing is very noise sensitive. To overcome this difficulty we adapted a robust region growing algorithm. Since region growing is very resource consuming, we do not perform it for every pixel. Instead, we divide the image into a number of overlapping blocks for which we carry out the segmentation. Then, we use the results for some of...
ECG denoising with adaptive bionic wavelet transform
, Article 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'06, New York, NY, 30 August 2006 through 3 September 2006 ; 2006 , Pages 6597-6600 ; 05891019 (ISSN); 1424400325 (ISBN); 9781424400324 (ISBN) ; Shamsollahi, M. B ; Sharif University of Technology
2006
Abstract
In this paper a new ECG denoising scheme is proposed using a novel adaptive wavelet transform, named bionic wavelet transform (BWT), which had been first developed based on a model of the active auditory system. There has been some outstanding features with the BWT such as nonlinearity, high sensitivity and frequency selectivity, concentrated energy distribution and its ability to reconstruct signal via inverse transform but the most distinguishing characteristic of BWT is that its resolution in the time-frequency domain can be adaptively adjusted not only by the signal frequency but also by the signal instantaneous amplitude and its first-order differential. Besides by optimizing the BWT...
Approach to analytic solution of navier-stokes equation utilizing adomian decomposition method, jet impinging flow application
, Article WSEAS Transactions on Mathematics ; Volume 5, Issue 5 , 2006 , Pages 507-514 ; 11092769 (ISSN) ; Taeibi Rahni, M ; Javadi, K. H ; Hosseinzadeh, S. F ; Sharif University of Technology
2006
Abstract
Adomian decomposition method was employed to obtain an approximate solution to two-dimensional and axisymmetric jet impinging flows in this work. Assumptions have been made to reduce the related full Navier-Stokes equations to a non-linear ordinary differential equation. A trial and error strategy has been used to obtain the constant coefficient in the approximated solution. Velocity Profiles, Shear stresses and displacement thickness were chosen to be compared with accurate numerical data. Sensitivity of the results to the number of terms have been discussed. The results showed for open boundary problems having at least one boundary condition at infinity, the applicable range of the...
Surface pressure variation on an airfoil in plunging and pitching motions
, Article 25th Congress of the International Council of the Aeronautical Sciences 2006, Hamburg, 3 September 2006 through 8 September 2006 ; Volume 2 , 2006 , Pages 962-971 ; 9781604232271 (ISBN) ; Rasi Marzabadi, F ; Seddighi, M ; Sharif University of Technology
2006
Abstract
Unsteady aerodynamic experiments were conducted on an oscillating airfoil in a subsonic wind tunnel. The model was oscillated in two types of motion, pitch and plunge, at a range of reduced frequencies, k=0.029-0.1. In addition, steady data were acquired and examined to furnish a baseline for analysis and comparison. The unsteady surface pressure is measured along the chord for both upper and lower surfaces of the model. Particular emphases were placed on the effects of different types of motion on the unsteady pressure distribution of the airfoil at pre-stall, near stall, and post stall conditions. It was found that the variations of the pressure distribution with angle of attack have...
Comparison and reduction of the chemical kinetic mechanisms proposed for thermal partial oxidation of methane (TPOX) in porous media
, Article International Journal of Hydrogen Energy ; Volume 46, Issue 37 , 2021 , Pages 19312-19322 ; 03603199 (ISSN) ; Rahimpour, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The effectiveness and reducibility of the methane combustion kinetic mechanisms were examined for the TPOX process in a porous medium. To this end, TPOX was successfully simulated using ANSYS CHEMKIN-Pro through a reactor network model composed of perfectly stirred and honeycomb-monolith reactors. The efficacy of six chemical kinetic mechanisms was compared for the equivalence ratios (ERs) ranging from 2.4 to 2.6 with a constant thermal load of 1540 kW/m2. This comparison revealed that Konnov was the most successful mechanism in the prediction of the H2 and CO mole fractions. This mechanism along with the GRI-3.0 and USC-Mech 2.0 mechanisms were then reduced by the direct relation graph with...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PLoS ONE ; Volume 16, Issue 1 January 2021 , 2021 ; 19326203 (ISSN) ; Dijujin, N. H ; Koohi, S ; Sharif University of Technology
Public Library of Science
2021
Abstract
In this study, optical technology is considered as SA issues’ solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Optical pattern generator for efficient bio-data encoding in a photonic sequence comparison architecture
, Article PLoS ONE ; Volume 16, Issue 1 , 2021 ; 19326203 (ISSN) ; Dijujin, N. H ; Koohi, S ; Sharif University of Technology
Public Library of Science
2021
Abstract
In this study, optical technology is considered as SA issues’ solution with the potential ability to increase the speed, overcome memory-limitation, reduce power consumption, and increase output accuracy. So we examine the effect of bio-data encoding and the creation of input images on the pattern-recognition error-rate at the output of optical Vander-lugt correlator. Moreover, we present a genetic algorithm-based coding approach, named as GAC, to minimize output noises of cross-correlating data. As a case study, we adopt the proposed coding approach within a correlation-based optical architecture for counting k-mers in a DNA string. As verified by the simulations on Salmonella whole-genome,...
Simulating sustainable transport using a predator-prey model
, Article International Journal of Modelling and Simulation ; Volume 25, Issue 3 , 2005 , Pages 147-155 ; 02286203 (ISSN) ; Vaziri, M ; Poorzahedy, H ; Sharif University of Technology
Int. Assoc. of Science and Technology for Development
2005
Abstract
A new generation of sustainable development research uses mathematical models. This article proposes a heuristic approach to analyze sustainability in a society utilizing a mathematical model. First, an alternative definition of sustainable development has been proposed. Second, the interactions between transport and the other major components of a society have been simulated by a system of differential equations in the form of Lotka-Volterra type predator-prey model. Some of the model parameters have been considered as control parameters in order to reflect the impact of strategies of reducing transport and economic levels of activities in favour of the environment on the one hand, and...
Acoustical identification of passenger cabin of vehicles
, Article Third International Conference on Modelling and Experimental Measurements in Acoustics, Acoustics III, Cadiz, 16 June 2003 through 18 June 2003 ; Volume 9 , 2003 , Pages 339-348 ; 1853129755 (ISBN) ; Abedi, M ; Sharif University of Technology
2003
Abstract
The acoustical system of car was analyzed using finite element method (FEM) and identification of the system. The acoustical model of a vehicle was proposed and by using FEM modal analysis, acoustic modal analysis, structural modal analysis, and coupling modal analysis was performed successfully. The influence of the acoustic system on the driver ears to understand these effects were also shown. The methods and results can be applied to a vehicle design procedure for conformability of the human being when riding
Optimization of torsion beam cross section using a combined FEM-dynamic simulation
, Article SAE Technical Papers ; 2003 ; 01487191 (ISSN) ; Behravesh, B ; Sharif University of Technology
SAE International
2003
Abstract
The compound axle is a space saving suspension component that is relatively inexpensive and easy to install. Therefore it is used in rear suspension system of most front wheel drive passenger cars. This article present an optimum design algorithm for this component. A typical cross section for this the torsion beam of the axle is selected as a basis design. Using finite element methods, kinematics and elasto-kinematics behaviors of the section in vehicle normal maneuvers have been calculated. The acquired dynamic characteristics of the member was entered into a dynamic simulation program and the effect of geometrical parameters of torsion beam on the vehicle handling was studied. Using DOE...
Acoustical identification of passenger cabin of vehicles
, Article WIT Transactions on the Built Environment ; Volume 69 , 2003 , Pages 339-348 ; 17433509 (ISSN) ; Abedi, M ; Sharif University of Technology
WITPress
2003
Abstract
Sound in the interior cabin of cars has been of the great importance nowadays. The automotive industry has long been fiercely competitive with different vendors attempting to produce vehicles with better performance, handling and fuel efficiency. The competition of the automotive industries today is directed on the reduction of noise in the cars cabin. This paper proposes a new method for noise studies in the cabin, which frequencies of excitation are lower than 200 Hz. The topics, which are covered in the paper, include the computation of the structural and acoustic mode shapes, resonant frequencies of the passenger compartment, coupling between structure and acoustic effects, and forced...
Unpacking the modelling process via sensitivity auditing
, Article Futures ; Volume 144 , 2022 ; 00163287 (ISSN) ; Sheikholeslami, R ; Puy, A ; Saltelli, A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Acknowledging the conditionality of model-based evidence facilitates the dialogue between model developers and model users, especially when models are used to guide decisions at the science-policy interface. In general, model users have limited access to verify the realism of a model, being only exposed to model plausibility and trustworthiness; instead, modellers have an an array of validation and verification techniques available. In the end, model credibility is what both developers and users aim for, also in the interest of shielding from the possible pitfall of over-interpreting the model results. To this end, in this contribution we discuss sensitivity auditing, an extension of...
Dynamic analysis of an n-revolute planar serial manipulator and sensitivity analysis based on Sobol's method
, Article International Conference on Robotics and Mechatronics, ICROM 2015, 7 October 2015 through 9 October 2015 ; 2015 , Pages 569-574 ; 9781467372343 (ISBN) ; Mohammadi, M ; Masouleh, M. T ; Sharif University of Technology
2015
Abstract
In this paper, dynamic modeling and dynamic sensitivity analysis of an n-revolute planar serial robot are investigated. First, a dynamic modeling algorithm is proposed which is based on the concept of the so-called Natural Orthogonal Complement. The main goal of this algorithm consists in deriving the corresponding dynamic equations of a planar serial manipulator systematically. As a comparison study, 3-DOF a planar serial manipulator is modeled and the results of the proposed algorithm is compared with other methods, i.e., Newton-Euler, Lagrange-Euler, Adams software and an Open Dynamics Engine, the so-called MatODE. Then, in order to develop a dynamic sensitivity analysis scheme, Sobol's...
Polynomial chaos expansions for uncertainty propagation and moment independent sensitivity analysis of seawater intrusion simulations
, Article Journal of Hydrology ; Volume 520 , January , 2015 , Pages 101-122 ; 00221694 (ISSN) ; Ataie Ashtiani, B ; Simmons, C. T ; Sharif University of Technology
Elsevier
2015
Abstract
Real world models of seawater intrusion (SWI) require high computational efforts. This creates computational difficulties for the uncertainty propagation (UP) analysis of these models due the need for repeated numerical simulations in order to adequately capture the underlying statistics that describe the uncertainty in model outputs. Moreover, despite the obvious advantages of moment-independent global sensitivity analysis (SA) methods, these methods have rarely been employed for SWI and other complex groundwater models. The reason is that moment-independent global SA methods involve repeated UP analysis which further becomes computationally demanding. This study proposes the use of...
Multi-parameter sensitivity analysis for guided needle insertion through soft tissue
, Article Proceedings of 2010 IEEE EMBS Conference on Biomedical Engineering and Sciences, IECBES 2010, 30 November 2010 through 2 December 2010, Kuala Lumpur ; 2010 , Pages 97-100 ; 9781424476008 (ISBN) ; Jahed, M ; Sharif University of Technology
2010
Abstract
Soft tissue needle insertion characterization has been a focus of many medical and biomedical recent studies. In this study the constrained prostate soft tissue deformation through a finite element model is evaluated. The study considers a sensitivity analysis of the target reaching error with respect to the mechanical, insertion and anatomical parameters in presence of the kinematics constraint on the tissue. The needle insertion into the soft tissue is simulated using the proposed Finite Element Method (FEM). Based on acquired results, the insertion of needle induces a considerable rotation of the prostate tissue due to its specific kinematics and support structure. Such rotation can...
3D wind buckling analysis of long steel corrugated silos with vertical stiffeners
, Article Engineering Failure Analysis ; Volume 90 , 2018 , Pages 156-167 ; 13506307 (ISSN) ; Moazezi Mehretehran, A ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Thin-walled cylindrical steel silos are susceptible to instability under wind pressure when they are empty or only partially filled. This paper investigates numerically the wind buckling behavior of a real steel corrugated silo with 8.02 m diameter and 17.62 m height, strengthened by open-section vertical stiffeners. Accordingly, comprehensive 3D finite element models were used and detailed linear and non-linear buckling analyses were conducted. The effects of sinusoidal corrugated sheet profile dimensions on this issue were specially explored. Wind load vertical and circumferential distributions were adopted from Eurocode. Two proposed circumferential pressure distributions for an isolated...