Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Airline Alliances Partner Selection in Uncertain Environment: A Fuzzy Hybrid Evaluation Model Based on BSC
1
10
EN
Gholam Ali
Montazer
Corresponding Author, Associate Prof. of IT Eng., School of Engineering, Tarbiat Modares University, P.O. Box:14115-179, Tehran, IRAN,
(e-mail: montazer@modares.ac.ir Phone: +982182883990, Fax: +982182883990)
montazer@modares.ac.ir
Hossein
Ebrahimian
Corresponding Author, Associate Prof. of IT Eng., School of Engineering, Tarbiat Modares University, P.O. Box:14115-179, Tehran, IRAN,
(e-mail: montazer@modares.ac.ir Phone: +982182883990, Fax: +982182883990)
ebrahimian@modares.ac.ir
10.22060/miscj.2011.158
With respect to the importance of commercial alliances in airline hypercompetitive environment, partner performance evaluation is a critical matter before making any decision about partnership. In this article, utilizing Fuzzy theory, a hybrid airline evaluation model is developed in a way that all airline performance strategic dimensions are considered, as well as, it can deal with qualitative and imprecise criteria and measures. In this way, the Balanced Score Card (BSC) methodology is employed to determine main criteria, beside considering passengers’ and experts’ viewpoints simultaneously. Since the used indicators are ambiguous and imprecise and respondents are facing them through linguistic vagueness, Fuzzy theory has been used to model the uncertainty. In the next step, a real problem based on partner selection in the Airline of the Islamic Republic of Iran is considered and three airlines’ characteristics were analyzed through developing hierarchical decision tree. The Fuzzy Analytic Hierarchy Process (FAHP) method is used for computing weight factors and relative importance of main criteria and their measures, and the performance of three airlines are analyzed and then the ranked using Fuzzy TOPSIS. Finally, the proposed model is revalidated based on total agreement of experts.
Fuzzy sets,Airline alliances,Fuzzy AHP,Fuzzy TOPSIS,Balanced Score Card
http://miscj.aut.ac.ir/article_158.html
http://miscj.aut.ac.ir/article_158_862e282fd232471f34a1abbd7118bd40.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Using Context-based Statistical Models to Promote the Quality of Voice Conversion Systems
11
17
EN
M.
Eslami
Corresponding Author, Department of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran (e-mail: ee35as@aut.ac.ir).
A.
Sayadianii
Department of Product and Services, Tamin Telecom Co.(3G mobile operator), Tehran, Iran (e-mail: m.eslami@tamintelecom.ir)
10.22060/miscj.2011.160
This article aims to examine methods of optimizing GMM-based voice conversion systems performance in which GMM method is introduced as the basic method for improvement of voice conversion systems performance. In the current methods, due to using a single conversion function to convert all speech units and subsequent spectral smoothing arising from statistical averaging, we will observe quality reduction. In this paper, after introducing GMM2 method, several GMM models will be used to model each phoneme. Furthermore, in the stage of corresponding the clusters of each state, before applying Dynamic Time Warping algorithm, we use a LMR conversion for further correspondence among the parameters of two corresponding states of two speakers. Another reason for quality reduction in voice conversion system is that the precision of speech signal parameters was underestimated. In order to overcome such a problem, Generalized Harmonic Model is introduced which is replaced by sinusoid harmonic model applied in GMM2 giving another method called GMM3. Finally, we will present GMM4 method, the objective of which is to promote the system performance with limited data and a restricted number of demi-syllables to train conversion functions.
High quality voice conversion,Gaussian mixed model (GMM),Generalized Harmonic Model (GHM),spectral conversion
http://miscj.aut.ac.ir/article_160.html
http://miscj.aut.ac.ir/article_160_85eacb5c2ac642fc5893da73a9bf8b44.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
09
23
The Development of Maximum Likelihood Estimation Approaches for Adaptive Estimation of Free Speed and Critical Density in Vehicle Freeways
55
66
EN
Amin
Ramezani
Tehran
aminramezani@ut.ac.ir
Behzad
Moshiri
moshiri@ut.ac.ir
Ashkan
Rahimi Kian
arkian@ut.ac.ir
10.22060/miscj.2011.494
The performance of many traffic control strategies depends on how much the traffic flow models have been accurately calibrated. One of the most applicable traffic flow model in traffic control and management is LWR or METANET model. Practically, key parameters in LWR model, including free flow speed and critical density, are parameterized using flow and speed measurements gathered by inductive loop detectors and Closed-Circuit TV. The challenging problem here is continuous changes in these parameters due to traffic conditions (traffic composition, incidents) and environmental factors (dense fog, strong wind, snow) and missing data. Here, Maximum Likelihood approaches have been developed to LWR model identification while inaccurate observations are available at the traffic control center. Maximum Likelihood method has been accomplished via the employment of an Expectation Maximization algorithm. To approximate first and second derivative of optimal filter without sticking in analytical complexities, here EM algorithm has been implemented based on particle filters and smoothers. Two convincing simulation results for two set of field traffic data have been used to demonstrate the effectiveness of the proposed approaches.
Maximum Likelihood Estimation,Free Speed,Critical Density,Expectation Maximization Algorithm
http://miscj.aut.ac.ir/article_494.html
http://miscj.aut.ac.ir/article_494_d41d8cd98f00b204e9800998ecf8427e.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Use of Stochastic Turbulence Models in Jet Acoustics
19
25
EN
A.
Ahmadzadegan
Corresponding Author, Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran.
Center of Excellence in Computational Aerospace Engineering (AeroExcel)
(e-mail: mtadjfar@aut.ac.ir)
M.
Tadjfari
Corresponding Author, Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran.
Center of Excellence in Computational Aerospace Engineering (AeroExcel)
(e-mail: mtadjfar@aut.ac.ir)
M.
Bayati
Corresponding Author, Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, Iran.
Center of Excellence in Computational Aerospace Engineering (AeroExcel)
(e-mail: mtadjfar@aut.ac.ir)
10.22060/miscj.2011.161
There are many approaches to determine the sound propagated from turbulent flows. In hybrid methods, the turbulent noise source field is computed or modeled separately from the far-field calculations. To have an initial and quick estimation of the sound propagation, less computationally intensive methods can be developed using stochastic models of the turbulent fluctuations. In this paper, turbulent mean flow of a two dimensional, compressible, cold-jet at Mach 0.56 is computed using RANS with 2 equation k-ε RNG model. The above mean-flow quantities are then used in a stochastic model to generate the details of the turbulent velocity fluctuations. This method is based on the use of classical Langevin equation to model the details of fluctuating flow field superimposed on the averaged computed quantities. The resulting sound field due to the generated unsteady flow is then evaluated using Lighthill's acoustic analogy. Our results are validated by comparing the directivity and the overall sound pressure level (OASPL) magnitudes with the available experimental data. Numerical results show reasonable agreement with the experiments, both in maximum directivity and the magnitude of the OASPL.
Aeroacoustics,Stochastic Modeling,Lighthill Volume Integral,Hybrid methods,Jet Acoustics
http://miscj.aut.ac.ir/article_161.html
http://miscj.aut.ac.ir/article_161_8a7e96be349e187e4996a0e71d32e43d.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Nonlinear Parametric Identification of an IPMC Actuator Model
27
31
EN
M.
Vahabi
M.
Kabganianii
10.22060/miscj.2011.163
Ionic polymer metal composite is a class of electro-active polymers which are very attractive smart actuators due to its large bending deflection, high mechanical flexibility, low excitation voltage, low density, and ease of fabrication. These properties make IPMC a proper candidate for many applications in various fields such as robotics, aerospace, biomedicine, etc. Although the actuation behaviors of this material are recently investigated, it is still a challenging problem to develop a promising model which covers all the physical properties associated with it. Further, nonlinear identification methods for IPMC nonlinear actuation model have not yet been applied. In this paper, Bonomo’s nonlinear model is used to formulate IPMC. In the following, the parameters of this model are identified through compromising nonlinear and linear least squares methods. According to the input type, the identification process for the electrical part is decoupled into two groups: nonlinear and linear. This technique resulted in reducing the number of parameters and more accurate identification. The identification method is validated using proper inputs. The generated results show that convergence of the identified parameters is guaranteed by the proposed method.
Ionic Polymer Metal Composite,Identification,Actuator,Nonlinear least squares
http://miscj.aut.ac.ir/article_163.html
http://miscj.aut.ac.ir/article_163_e188f84a20dc34fc204e5a1ccb3b9b66.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Vehicle Stabilization via a Self-Tuning Optimal Controller
33
41
EN
M.
Bayani
R.
Kazemi
Sh.
Azadiiii
10.22060/miscj.2011.167
Nowadays, using advanced vehicle control and safety systems in vehicles is growing rapidly. In this regard, in recent years new control systems, called VDC, have been introduced. These systems stabilize vehicle yaw motion, by yaw moment resulted from tire controlling forces. In this paper, an adaptive optimal controller applied to a vehicle to obtain a satisfactory lateral and yaw stability. To derive the control law, we use LQR method. Considering that various parameters are included in the controller structure, which their measurement is either expensive or practically impossible, a least squared estimator with variable forgetting factor is proposed to estimate them. To optimize the system and in order to exert the control yaw moment, an ABS brake system is implemented in a new architecture to distribute brake forces on wheels. The controller rules are derived based on the bicycle model and the estimator is designed based on the 7 DOE model of the vehicle. To simulate and evaluate the performance of the proposed controller the full vehicle model of the reference car in ADAMS/Car, with 214 DOE, is also implemented. Finally, the results of the vehicle response, equipped with the controller system, in a standard maneuver are presented.
Vehicle Dynamic Control,ABS,Adaptive Optimal Control,Tire Force Estimation,ADAMS Model
http://miscj.aut.ac.ir/article_167.html
http://miscj.aut.ac.ir/article_167_33f58e2dce0331466b6eb1ccee27787c.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Optimizing Disparity Candidates Space in Dense Stereo Matching
43
51
EN
Ali M
. Fotouhi
Abolghasem A.
Raieii
10.22060/miscj.2011.170
In this paper, a new approach for optimizing disparity candidates space is proposed for the solution of dense stereo matching problem. The main objectives of this approachare the reduction of average number of disparity candidates per pixel with low computational cost and high assurance of retaining the correct answer. These can be realized due to the effective use of multiple radial windows, intensity information, and some usual and new constraints, in a reasonable manner. The new space improved by the new idea validation and correction retains those candidates, which satisfy more constraints and especially being more promising to satisfy the implied assumption in using support windows, i.e. the disparity consistency of the window pixels. To evaluate the proposed space, the weighted window is used to estimate dense disparity map in this space. The experimental results on the standard stereo images indicate an overall speedup factor of 11 and the improved disparity map.
Disparity Candidate – Radial Window – Validation and Correction – Weighted Window
http://miscj.aut.ac.ir/article_170.html
http://miscj.aut.ac.ir/article_170_036b9c064b51d0e9362360b430bcad43.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Design and Modeling of a New Type of Tactile Sensor Based on the Deformation of an Elastic Membrane
53
58
EN
Goldis
Darb Emamiehi
Siamak
Najarian
najarian@aut.ac.ir
Ali
Tavakoli Golpaygani
10.22060/miscj.2011.172
This paper presents the design and modeling of a flexible tactile sensor, capable of detecting the 2D surface texture image, contact-force estimation and stiffness of the sensed object. The sensor is made of polymer materials. It consists of a cylindrical chamber for pneumatic actuation and a membrane with a mesa structure. The inner radius of the cylindrical chamber is 2cm and its outer radius is 3cm. The sensing mechanism of the sensor is based on the contact deformation of the membrane. Determination of the contact-force and stiffness of sensed object is based on the amount and variations of out of plane deflections at the center of a circular membrane. The amount of deflection depends on the force or pressure applied. Furthermore, the size and shape can be easily tailored to the applications’ requirements. This versatility facilitates the use of the sensor in smart applications where tactile information is used to create system intelligence. The proposed sensor with the potential for further miniaturization is suitable for using in medical applications, especially in minimally invasive surgery (MIS).
Tactile Sensor,Stiffness,Contact Force,Membrane
http://miscj.aut.ac.ir/article_172.html
http://miscj.aut.ac.ir/article_172_f936580c47c435e63a47cc4de4357d11.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
A Mushy State Simulated Annealing
59
70
EN
K.
Shojaee G
H.
Shakouri G
M.B
. Menhaj
10.22060/miscj.2011.174
It is a long time that the Simulated Annealing (SA) procedure has been introduced as a model-free optimization for solving NP-hard problems. Improvements from the standard SA in the recent decade mostly concentrate on combining its original algorithm with some heuristic methods. These modifications are rarely happened to the initial condition selection methods from which the annealing schedules or the time schedule itself start. There are several parameters in the process of annealing, the adjustment of which affects the overall performance. This paper focuses on the importance of initial temperature and then proposes a lower temperature with low energy to speed up the process, using an auxiliary memory to buffer the best solution. Such an annealing indeed starts from a “mushy state” rather than a quite liquid molten material. The mushy state characteristics indeed depends upon the problems that SA is being applied to solve for. In this paper, the Mushy State Simulated Annealing (MSSA) is fully developed and then applied to the popular Traveling Salesman Problem (TSP). The mushy state may be obtained by some simple methods like crossover elimination. A very fast version of a Wise Traveling Salesman, who starts from a randomly chosen city and seeks for the nearest one as the next, is also applied to initiate SA by a low-energy, low-temperature state. This fast method results in quite accurate solutions compared to the methods recently cited in the literature.
Combinatorial Optimization,Traveling Salesman Problem,Simulated Annealing,Initial Condition
http://miscj.aut.ac.ir/article_174.html
http://miscj.aut.ac.ir/article_174_b3feae27fb8a7a4a4b5d1e33169b5a6c.pdf
Amirkabir University of Technology
AUT Journal of Modeling and Simulation
2588-2953
2588-2961
43
2
2011
11
01
Grinding Circuit at Mouteh Gold Mine
71
76
EN
M.A.
Babai Alamouti
B.
Rezai
M.
Noaparast
10.22060/miscj.2011.176
This study was conducted in Mouteh grinding circuit. Mouteh gold processing plant is located in Esfahan province,center of Iran, close to Mouteh open pit mine. One of the main problems in this circuit is low efficiency grinding operation. In this study, first grinding circuit and its performance parameters are evaluated. Laboratory and corrected operating Bond work index subsequently were calculated to be 16.8 and 21.47 (kwh/t), respectively. Bond efficiency factor then estimated to be 78.24%. Low value of this index means that the grinding operation is inefficient. Finally, efficiency of hydrocyclones evaluated and its cut size was calculated to be 85 microns.
http://miscj.aut.ac.ir/article_176.html
http://miscj.aut.ac.ir/article_176_2d908a9332a5e26b5927bf16220b0f00.pdf