2017-11-19T01:12:07Z
http://miscj.aut.ac.ir/?_action=export&rf=summon&issue=25
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
The IUFP Algorithm for Generating Simulation Heart
Elham
Shadkam
Abdollah
Aghaie
In all systems simulation, random variates are considered as a main factor and based of simulation heart. Actually, randomization is inducted by random variates in the simulation. Due to the importance of such a problem, a new method for generation of random variates from continuous distributions is presented in this paper. The proposed algorithm, called uniform fractional part (UFP) is simpler and more efficient compared with other methods of random variates generation. Despite useful consequences, this algorithm has several shortcomings such as 1) being approximate, 2) not accessibility of the inverse of cumulative density function (CDF) for all distributions in order to determine the cut-off points and 3) truncating the tails of infinite distributions, which all of the aforementioned shortcomings reduce the precision and speed of the algorithm. The main goal of this research is proposing the improved version of this algorithm (IUFP) through recognizing its deficiencies.
Random Variates generation
Simulation
Uniform Fractional Part (UFP)
2012
11
01
1
10
http://miscj.aut.ac.ir/article_119_0f3b8a7d4d11f3196a784a90a3b185a9.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
AN Improved UTD Based Model For The Multiple Building Diffraction Of Plane Waves In Urban Environments By Using Higher Order Diffraction Coeficients
A.
Tajvidyi
A.
Ghorbanii
M.
Nasermoghaddasi
This paper describes an improved model for multiple building diffraction modeling based on the uniform theory of diffraction (UTD). A well-known problem in conventional uniform theory of diffraction (CUTD) is multiple-edge transition zone diffraction. Here, higher order diffracted fields are used in order to improve the result; hence, we use higher order diffraction coefficients to improve a hybrid physical optics (PO)-CUTD model, the results show that the new model corrects errors of the PO-CUTD model. Therefore, the proposed model can find application in the development of theoretical models to predict more realistic path loss in urban environments when multiple-building diffraction is considered.
Higher order diffraction coefficient
Multiple-edge Diffraction
UTD
2012
11
01
11
17
http://miscj.aut.ac.ir/article_121_706ed9bbe66fb8f64547f13ca1a2a14d.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
Genetic and Memetic Algorithms for Sequencing a New JIT Mixed-Model Assembly Line
R.
Tavakkoli-Moghaddam
Y.
Gholipour-Kanani
R.
Cheraghalizadeh
This paper presents a new mathematical programming model for the bi-criteria mixed-model assembly line balancing problem in a just-in-time (JIT) production system. There is a set of criteria to judge sequences of the product mix in terms of the effective utilization of the system. The primary goal of this model is to minimize the setup cost and the stoppage assembly line cost, simultaneously. Because of its complexity to be optimally solved in a reasonable time, we propose and develop two evolutionary meta-heuristics based on a genetic algorithm (GA) and a memetic algorithm (MA). The proposed heuristics are evaluated by the use of random iterations, and the related results obtained confirm their efficiency and effectiveness in order to provide good solutions for medium and large-scale problems.
JIT mixed-model assembly line balancing
Setup cost
Stoppage cost
Genetic Algorithm
Memetic algorithm
2012
11
01
17
28
http://miscj.aut.ac.ir/article_123_7395fc70b48d8853a38316cd26b9e83c.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
A Mushy State Simulated Annealing
Hamed
Shakouri G.
Kambiz
Shojaee
Mohammad B.
Menhaj
It is a long time that the Simulated Annealing (SA) procedure is 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 starts or the time schedule itself. 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 depends on 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
2012
09
22
1
8
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
Optimal Trajectory Study of a Small Size Waverider and Wing-Body Reentry Vehicle at Suborbital Entry Speed of Approximately 4 km/s with Dynamic Pressure and Heat Rate Constraint
S.
Tauqeer ul Islam Rizvi
He
Linshu
Tawfiqur
Rahman
A numerical trajectory optimization study of two types of lifting-entry reentry vehicle has been presented at low suborbital speed of 4.113 km/s and -15 degree entry angle. These orbital speeds are typical of medium range ballistic missile with ballistic range of approximately 2000 km at optimum burnout angle of approximately 41 degree for maximum ballistic range. A lifting reentry greatly enhances the reentry range which leads to a higher overall range of approximately 3000 km for the same ΔV. The optimum reentry angle of lifting reentry vehicle for medium range missiles under constrained g-load lies between -15 to -20 degree for limited g-load trajectories. These entry angles result in high decent rates and the vehicle quickly approaches the heat rate boundary. The heat rate problem is more severe for small size vehicle because of small nose-radius. Limiting the heat rate restricts the trajectory and lowers the downrange/cross-range performance of the reentry vehicle. A wing-body reentry vehicle has a larger nose radius as compared to a waverider which results in comparatively low heat rates during flight. This type of a vehicle has lower lift-to-drag ratio and therefore lesser range in comparison to a waverider type design. The performance of the two vehicle types is studied at various heat rate limits with the objective to calculate the optimum control deflections that would maximize the cross range. The results provide performance of the two designs vis-à-vis maximum heat rate constraint at the stagnation point along with the required control history. General pseudo-spectral optimal control software, GPOPS has been used for the optimal trajectory studies.
trajectory optimization
Optimal Control
Reentry Guidance
Lifting Reentry
Conceptual design
Ballistic Missiles
Radau Pseudospectral Method
2012
11
01
29
36
http://miscj.aut.ac.ir/article_126_acd09f2fa6fd34dab79d63cb0d4f8744.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
Modeling of Jitter Characteristics for the Second Order Bang-Bang CDR
Habib
Adrangi
Hossein
Miar Naimi
Bang-Bang clock and data recovery (BBCDR) circuits are hard nonlinear systems due to the nonlinearity introduced by the binary phase detector (BPD). The specification of the CDR frequency response is determined by jitter tolerance and jitter transfer. In this paper, jitter transfer and jitter tolerance of the second-order BBCDR are characterized by formulating the time domain waveforms. As a result, a new equation is presented to obtain corner frequency. Also, the jitter tolerance is expressed in closed form as a function of loop parameters. The proposed method is general enough to be used for designing BBCDR. The analysis is verified using behavioral simulations in MATLAB. Simulation results demonstrate the validity of the result obtained by analytical equations.
Clock and Data Recovery (CDR)
Bang-Bang Phase Detector (BPD)
Jitter Transfer and Jitter Tolerance
2012
11
01
37
45
http://miscj.aut.ac.ir/article_128_89941216c277ba785bcd3e1595dc72e9.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
Analysis of Vector Estimating Modulation Method to Eliminate Common Mode Voltage
N.
Rashidiradi
A.
Rahmati
A.
Abrishamifar
Abstract The problem of common mode voltage in inverters can be considered as a major issue which leads to motor bearing failures. To eliminate these voltages, proposing some methods seems to be necessary. This paper has a comparative study on estimating modulation methods of eliminating common mode voltage. The main idea of these methods is based on generation of reference vector with nearest vector/ vectors with zero common mode voltage. Depending on the number of delivering nearest vectors, there are two estimating methods. For the reference method, reference vector is synthesized only by the nearest vector. But for the proposed method, the reference vector is synthesized by more than one vector. Dwell time calculations of these vectors are based on the distance between the afore-mentioned vectors and the reference vector. In this paper, some characteristics such as linear relationships among output voltage and modulation index, and also total harmonic distortion of output voltage and stator current are considered. Finally, it is concluded that the new method has more advantages such as more linear relationships and lower THD of current with respect to the reference method.
Common Mode Voltage
Modulation
Harmonic Distortion
Modulation Index
2012
11
01
47
53
http://miscj.aut.ac.ir/article_131_e052d2abcc5c729b340528db123e406f.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
A Hybrid Framework for Building an Efficient Incremental Intrusion Detection System
Amin
Rasoulifard
Abbas
Ghaemi Bafghi
In this paper, a boosting-based incremental hybrid intrusion detection system is introduced. This system combines incremental misuse detection and incremental anomaly detection. We use boosting ensemble of weak classifiers to implement misuse intrusion detection system. It can identify new classes types of intrusions that do not exist in the training dataset for incremental misuse detection. As the framework has low computational complexity, it is suitable for real-time or on-line learning. We use incremental centroid-based “on-line k-Mean” clustering algorithm to implement anomaly detection system. Experimental evaluations on KDD Cup dataset have shown that the proposed framework has high clustering quality, relatively low computational complexity and fast convergence.
Intrusion Detection System
neural network
Incremental Learning
Boosting Ensemble Learning
Clustering
Weak Classifiers
Weak Learner
2012
11
01
55
67
http://miscj.aut.ac.ir/article_132_9ee2c5de87d42ce5668a8714e81d3423.pdf
AUT Journal of Modeling and Simulation
2588-2953
2588-2953
2012
44
2
Algorithms for Computing Limit distributions of Oscillating Systems with Finite Capacity
Mohammad
Taremi
We address the batch arrival systems with finite capacity under partial batch acceptance strategy where service times or rates oscillate between two forms according to the evolution of the number of customers in the system. Applying the theory of Markov regenerative processes and resorting to Markov chain embedding, we present a new algorithm for computing limit distributions of the number customers in the system. The numerical results are given in the paper for a clearer expression of the proposed computational methodologies.
Systems
Finite Capacity
Oscillating Systems
Acceptance Strategy
Batch Arrivals
2012
11
01
69
78
http://miscj.aut.ac.ir/article_133_ba76dff2000eb9c824527a95f41a3bb8.pdf