Search results for: Akbar Jafari
87 Experimental and Finite Element Study of Bending Fatigue Failure: A Case Study on Main Shaft of a Gyrator Crusher
Authors: Rahim Sotoudeh Bahreini, Alireza Foroughi Nematollahi, Akbar Jafari
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This study investigates the mechanism of a Gyratory crusher-located in Golgohar mining and industrial Co. specifically with a focus on stresses distribution and fatigue failure of its main shaft. At first step, the cross section of the fractured shaft is studied, and the crack growth is analyzed. Then, the rotational motion of the shaft and the oil temperature of oil circuit of equipment are monitored. Condition monitoring is used to help finding a better modification. Based on the results of this study, the main causes of shaft failure are identified, and corrective solution is offered to increase crusher performance, especially its main shaft life. To predict the efficiency of the proposed modification, finite element simulation is performed, and its results are compared with the similar modified cases. The comparison and interpretation of simulation results confirm the efficiency of proposed corrective method.
Keywords: Fatigue failure, finite element method, gyratory crusher, condition monitoring.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 162186 ANN Modeling for Cadmium Biosorption from Potable Water Using a Packed-Bed Column Process
Authors: Dariush Jafari, Seyed Ali Jafari
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The recommended limit for cadmium concentration in potable water is less than 0.005 mg/L. A continuous biosorption process using indigenous red seaweed, Gracilaria corticata, was performed to remove cadmium from the potable water. The process was conducted under fixed conditions and the breakthrough curves were achieved for three consecutive sorption-desorption cycles. A modeling based on Artificial Neural Network (ANN) was employed to fit the experimental breakthrough data. In addition, a simplified semi empirical model, Thomas, was employed for this purpose. It was found that ANN well described the experimental data (R2>0.99) while the Thomas prediction were a bit less successful with R2>0.97. The adjusted design parameters using the nonlinear form of Thomas model was in a good agreement with the experimentally obtained ones. The results approve the capability of ANN to predict the cadmium concentration in potable water.
Keywords: ANN, biosorption, cadmium, packed-bed, potable water.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 212085 Enhancing Predictive Accuracy in Pharmaceutical Sales Through an Ensemble Kernel Gaussian Process Regression Approach
Authors: Shahin Mirshekari, Mohammadreza Moradi, Hossein Jafari, Mehdi Jafari, Mohammad Ensaf
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This research employs Gaussian Process Regression (GPR) with an ensemble kernel, integrating Exponential Squared, Revised Matérn, and Rational Quadratic kernels to analyze pharmaceutical sales data. Bayesian optimization was used to identify optimal kernel weights: 0.76 for Exponential Squared, 0.21 for Revised Matérn, and 0.13 for Rational Quadratic. The ensemble kernel demonstrated superior performance in predictive accuracy, achieving an R² score near 1.0, and significantly lower values in MSE, MAE, and RMSE. These findings highlight the efficacy of ensemble kernels in GPR for predictive analytics in complex pharmaceutical sales datasets.
Keywords: Gaussian Process Regression, Ensemble Kernels, Bayesian Optimization, Pharmaceutical Sales Analysis, Time Series Forecasting, Data Analysis.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 8784 Reverse Impact of Temperature as Climate Factor on Milk Production in ChaharMahal and Bakhtiari
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When long-term changes in normal weather patterns happen in a certain area, it generally could be identified as climate change. Concentration of principal's greenhouse gases such as carbon dioxide, nitrous oxide, methane, ozone, and water vapor will cause climate change and perhaps climate variability. Main climate factors are temperature, precipitation, air pressure, and humidity. Extreme events may be the result of the changing of carbon dioxide concentration levels in the atmosphere which cause a change in temperature. Extreme events in some ways will affect the productivity of crop and dairy livestock. In this research, the correlation of milk production and temperature as the main climate factor in ChaharMahal and Bakhtiari province in Iran has been considered. The methodology employed for this study consists, collect reports and published national and provincial data, available recorded data on climate factors and analyzing collected data using statistical software. Milk production in ChaharMahal and Bakhtiari province is in the same pattern as national milk production in Iran. According to the current study results, there is a significant negative correlation between milk production in ChaharMahal and Bakhtiari provinces and temperature as the main climate change factor.Keywords: ChaharMahal and Bakhtiari, climate change, impacts, Iran, milk production.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 147083 Adaptive Car Safety System
Authors: Shahram Jafari, Mohammad-Ali Nikouei Mahani, Mohammad Arabnezhad, Mahdi Sharifi
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Car accident is one of the major causes of death in many countries. Many researchers have attempted to design and develop techniques to increase car safety in the past recent years. In spite of all the efforts, it is still challenging to design a system adaptive to the driver rather than the automotive characteristics. In this paper, the adaptive car safety system is explained which attempts to find a balance.
Keywords: Analog to Digital Converter (ADC), AdaptiveCar Safety System, Multi-Media Card (MMC).
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 187982 Acetalization of Carbonyl Compounds by Using Al2 (HPO4)3 under Green Condition Mg HPO4
Authors: Fariba Jafari, Samaneh Heydarian
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Al2(HPO4)3 was easily prepared and used as a solid acid in acetalization of carbonyl compounds at room temperature and under solvent-free conditions. The protection was done in short reaction times and in good to high isolated yields. The cheapness and availability of this reagent with easy procedure and work-up make this method attractive for the organic synthesis.Keywords: Acetalization, acid catalysis, carbonylcompounds, green condition, protection.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 132881 Analysis of a Secondary Autothermal Reformer Using a Thermodynamic POX Model
Authors: Akbar Zamaniyan, Alireza Behroozsarand, Hadi Ebrahimi
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Partial oxidation (POX) of light hydrocarbons (e.g. methane) is occurred in the first part of the autothermal reformer (ATR). The results of the detailed modeling of the reformer based on the thermodynamic model of the POX and 1D heterogeneous catalytic model for the fixed bed section are considered here. According to the results, the overall performance of the ATR can be improved by changing the important feed parameters.Keywords: Autothermal Reformer, Partial Oxidation, Mathematical Modeling, Process Simulation, Syngas.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 219280 Analysis of Sonographic Images of Breast
Authors: M. Bastanfard, S. Jafari, B.Jalaeian
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Ultrasound images are very useful diagnostic tool to distinguish benignant from malignant masses of the breast. However, there is a considerable overlap between benignancy and malignancy in ultrasonic images which makes it difficult to interpret. In this paper, a new noise removal algorithm was used to improve the images and classification process. The masses are classified by wavelet transform's coefficients, morphological and textural features as a novel feature set for this goal. The Bayesian estimation theory is used to classify the tissues in three classes according to their features.Keywords: Bayesian estimation theory, breast, ultrasound, wavelet.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 143579 CFD Modeling of Boiling in a Microchannel Based On Phase-Field Method
Authors: Rahim Jafari, Tuba Okutucu-Özyurt
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The hydrodynamics and heat transfer characteristics of a vaporized elongated bubble in a rectangular microchannel have been simulated based on Cahn-Hilliard phase-field method. In the simulations, the initially nucleated bubble starts growing as it comes in contact with superheated water. The growing shape of the bubble compared well with the available experimental data in the literature.
Keywords: Microchannel, boiling, Cahn-Hilliard method, Two-phase flow, Simulation.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 383578 Analysis of Complexes Pairing Performat Radical and Water
Authors: Sanaz Gharehzadeh Shirazi, Subira Gharehzadeh Shirazi, Fariba Jafari
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The present article comprises a theoretical study of structures Performat radical (HCO3) with H2O molecule. We make use of ab initio quantum chemical methods. Unrestricted Hartee-Fock (UHF) with the basis set6-311+g(2df,2p) and density functional theory (B3LYP) with the basis set 6-311+g(2df,2p) and also we done atoms in molecules (AIM) theory for them. We have found four stable geometries the PerformatRadical(HCO3) with H2O.Keywords: Hydrogen binding, Performat Radical, Water, Gaussian, Atoms in molecules (AIM) theory
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 143577 Solving a System of Nonlinear Functional Equations Using Revised New Iterative Method
Authors: Sachin Bhalekar, Varsha Daftardar-Gejji
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In the present paper, we present a modification of the New Iterative Method (NIM) proposed by Daftardar-Gejji and Jafari [J. Math. Anal. Appl. 2006;316:753–763] and use it for solving systems of nonlinear functional equations. This modification yields a series with faster convergence. Illustrative examples are presented to demonstrate the method.Keywords: Caputo fractional derivative, System of nonlinear functional equations, Revised new iterative method.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 232676 Optimal Control Problem, Quasi-Assignment Problem and Genetic Algorithm
Authors: Omid S. Fard, Akbar H. Borzabadi
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In this paper we apply one of approaches in category of heuristic methods as Genetic Algorithms for obtaining approximate solution of optimal control problems. The firs we convert optimal control problem to a quasi Assignment Problem by defining some usual characters as defined in Genetic algorithm applications. Then we obtain approximate optimal control function as an piecewise constant function. Finally the numerical examples are given.Keywords: Optimal control, Integer programming, Genetic algorithm, Discrete approximation, Linear programming.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 128475 Approximate Solution of Nonlinear Fredholm Integral Equations of the First Kind via Converting to Optimization Problems
Authors: Akbar H. Borzabadi, Omid S. Fard
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In this paper we introduce an approach via optimization methods to find approximate solutions for nonlinear Fredholm integral equations of the first kind. To this purpose, we consider two stages of approximation. First we convert the integral equation to a moment problem and then we modify the new problem to two classes of optimization problems, non-constraint optimization problems and optimal control problems. Finally numerical examples is proposed.Keywords: Fredholm integral equation, Optimization method, Optimal control, Nonlinear and linear programming
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 175874 Novel Mobile Climbing Robot Agent for Offshore Platforms
Authors: Akbar F. Moghaddam, Magnus Lange, Omid Mirmotahari, Mats Høvin
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To improve HSE standards, oil and gas industries are interested in using remotely controlled and autonomous robots instead of human workers on offshore platforms. In addition to earlier reason this strategy would increase potential revenue, efficient usage of work experts and even would allow operations in more remote areas. This article is the presentation of a custom climbing robot, called Walloid, designed for offshore platform topside automation. This 4 arms climbing robot with grippers is an ongoing project at University of Oslo.Keywords: Climbing Robots, Mobile Robots, Offshore Robotics, Offshore Platforms, Automation, Inspection, Monitoring.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 209573 Development Prospects of Education System in Modernization
Authors: Akbar Seraly, Kazbek Primbetov, Gulmira Abdiraiymova, Gulnapis Abdikerova
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the article analyzes the development prospects of education system in Kazakhstan. Education is among key sources of culture and social mobility. Modern education must become civic which means availability of high quality education to all people irrespective of their racial, ethnic, religious, social, gender and any other differences. Socially focused nature of modernization of Kazakhstan-s society is predicated upon formation of a civic education model in the future. Kazakhstan-s education system undergoes intensive reforms first of all intended to achieve international education standards and integration into the global educational and information space.Keywords: Education system, Kazakhstan , Modernization
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 179172 Characterization of Monoids by a Generalization of Flatness Property
Authors: Mahdiyeh Abbasi, Akbar Golchin
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It is well-known that, using principal weak flatness property, some important monoids are characterized, such as regular monoids, left almost regular monoids, and so on. In this article, we define a generalization of principal weak flatness called GP-Flatness, and will characterize monoids by this property of their right (Rees factor) acts. Also we investigate new classes of monoids called generally regular monoids and generally left almost regular monoids.Keywords: G-left stabilizing, GP-flatness, generally regular, principal weak flatness.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 216171 Learning FCM by Tabu Search
Authors: Somayeh Alizadeh, Mehdi Ghazanfari, Mostafa Jafari, Salman Hooshmand
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Fuzzy Cognitive Maps (FCMs) is a causal graph, which shows the relations between essential components in complex systems. Experts who are familiar with the system components and their relations can generate a related FCM. There is a big gap when human experts cannot produce FCM or even there is no expert to produce the related FCM. Therefore, a new mechanism must be used to bridge this gap. In this paper, a novel learning method is proposed to construct causal graph based on historical data and by using metaheuristic such Tabu Search (TS). The efficiency of the proposed method is shown via comparison of its results of some numerical examples with those of some other methods.
Keywords: Fuzzy Cognitive Map (FCM), Learning, Meta heuristic, Genetic Algorithm, Tabu search.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 185370 Energy and Exergy Analysis of Dual Purpose Solar Collector
Authors: I. Jafari, A. Ershadi, E. Najafpour, N. Hedayat
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Energy and exergy study of air-water combined solar collector which is called dual purpose solar collector (DPSC) is investigated. The method of ε - NTU is used. Analysis is performed for triangle channels. Parameters like the air flow rate and water inlet temperature are studied. Results are shown that DPSC has better energy and exergy efficiency than single collector. In addition, the triangle passage with water inlet temperature of 60O C has shown better exergy and energy efficiency.
Keywords: Efficiency, Exergy, Irreversibility, Solar collector.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 262069 Experimental Study of Different Types of Concrete in Uniaxial Compression Test
Authors: Khashayar Jafari, Mostafa Jafarian Abyaneh, Vahab Toufigh
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Polymer concrete (PC) is a distinct concrete with superior characteristics in comparison to ordinary cement concrete. It has become well-known for its applications in thin overlays, floors and precast components. In this investigation, the mechanical properties of PC with different epoxy resin contents, ordinary cement concrete (OCC) and lightweight concrete (LC) have been studied under uniaxial compression test. The study involves five types of concrete, with each type being tested four times. Their complete elastic-plastic behavior was compared with each other through the measurement of volumetric strain during the tests. According to the results, PC showed higher strength, ductility and energy absorption with respect to OCC and LC.
Keywords: Polymer concrete, ordinary cement concrete, lightweight concrete, uniaxial compression test, volumetric strain.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 115068 Studies on the Applicability of Artificial Neural Network (ANN) in Prediction of Thermodynamic Behavior of Sodium Chloride Aqueous System Containing a Non-Electrolytes
Authors: Dariush Jafari, S. Mostafa Nowee
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In this study a ternary system containing sodium chloride as solute, water as primary solvent and ethanol as the antisolvent was considered to investigate the application of artificial neural network (ANN) in prediction of sodium solubility in the mixture of water as the solvent and ethanol as the antisolvent. The system was previously studied using by Extended UNIQUAC model by the authors of this study. The comparison between the results of the two models shows an excellent agreement between them (R2=0.99), and also approves the capability of ANN to predict the thermodynamic behavior of ternary electrolyte systems which are difficult to model.
Keywords: Thermodynamic modeling, ANN, solubility, ternary electrolyte system.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 214767 Analysis of Sonogram Images of Thyroid Gland Based on Wavelet Transform
Authors: M. Bastanfard, B. Jalaeian, S. Jafari
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Sonogram images of normal and lymphocyte thyroid tissues have considerable overlap which makes it difficult to interpret and distinguish. Classification from sonogram images of thyroid gland is tackled in semiautomatic way. While making manual diagnosis from images, some relevant information need not to be recognized by human visual system. Quantitative image analysis could be helpful to manual diagnostic process so far done by physician. Two classes are considered: normal tissue and chronic lymphocyte thyroid (Hashimoto's Thyroid). Data structure is analyzed using K-nearest-neighbors classification. This paper is mentioned that unlike the wavelet sub bands' energy, histograms and Haralick features are not appropriate to distinguish between normal tissue and Hashimoto's thyroid.Keywords: Sonogram, thyroid, Haralick feature, wavelet.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 131166 Evaluation of Protein Digestibility in Canola Meals between Caecectomised and Intact Adult Cockerels
Authors: Ali Nouri Emamzadeh, Akbar Yaghobfar
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The experiment was conducted to evaluate digestibility quantities of protein in Canola Meals (CMs) between caecectomised and intact adult Rhode Island Red (RIR) cockerels with using conventional addition method (CAM) for 7 d: a 4-d adaptation and a 3-d experiment period on the basis of a completely randomized design with 4 replicates. Results indicated that caecectomy decreased (P<0.05) apparent and true digestibility quantities of protein for CMs, except for CMs 2 and 3. The mean apparent and true digestibility quantities for all CMs in caecectomised (80.5 and 81.4%, respectively) were (3.1 and 3.3%, respectively) less (P<0.05) than intact cockerels (83.6 and 84.7%, respectively). Therefore, the caecectomy method increases accuracy of the digestibility measurements of protein for this meal in bioassays based on excreta collection in adult cockerels.Keywords: Adult cockerels, caecectomy, canola meals, proteindigestibility.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 181565 Control of Underactuated Biped Robots Using Event Based Fuzzy Partial Feedback Linearization
Authors: Omid Heydarnia, Akbar Allahverdizadeh, Behnam Dadashzadeh, M. R. Sayyed Noorani
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Underactuated biped robots control is one of the interesting topics in robotics. The main difficulties are its highly nonlinear dynamics, open-loop instability, and discrete event at the end of the gait. One of the methods to control underactuated systems is the partial feedback linearization, but it is not robust against uncertainties and disturbances that restrict its performance to control biped walking and running. In this paper, fuzzy partial feedback linearization is presented to overcome its drawback. Numerical simulations verify the effectiveness of the proposed method to generate stable and robust biped walking and running gaits.Keywords: Underactuated system, biped robot, fuzzy control, partial feedback linearization.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 176364 Hydrothermal Alteration Zones Identification Based on Remote Sensing Data in the Mahin Area, West of Qazvin Province, Iran
Authors: R. Nouri, M.R. Jafari, M. Arain., F. Feizi
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The Mahin area is a part of Tarom- Hashtjin zone that located in west of Qazvin province in northwest of Iran. Many copper and base metals ore deposits are hosted by this zone. High potential localities identification in this area is very necessary. The objective of this research, is finding hydrothermal alteration zones by remote sensing methods and best processing technique of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data. Different methods such as band ratio, Principal Component Analysis (PCA), Minimum Noise Fraction (MNF) and Least Square Fit (LS-Fit) were used for mapping hydrothermal alteration zones.Keywords: Hydrothermal alteration, Iran, Mahin, Remote sensing
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 280963 Effects of Electric Potential on Thermo-Mechanical Behavior of Functionally Graded Piezoelectric Hollow Cylinder under Non-Axisymmetric Loads
Authors: Amir Atrian, Javad Jafari Fesharaki, Gh. Hossein Majzoobi, Mahsa Sheidaee
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The analytical solution of functionally graded piezoelectric hollow cylinder which is under radial electric potential and non-axisymmetric thermo-mechanical loads, are presented in this paper. Using complex Fourier series and estimation of power law for variations of material characterizations through the thickness, the electro thermo mechanical behavior of the FGPM cylinder is obtained. The stress and displacement distributions and the effect of electric potential field on the cylinder behavior are also presented and some applicable results are offered at the end of the paper.Keywords: Analytical, FGM, Fourier series, Non-axisymmetric, Piezoelectric, Thermo-elasticity
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 182862 A Direct Probabilistic Optimization Method for Constrained Optimal Control Problem
Authors: Akbar Banitalebi, Mohd Ismail Abd Aziz, Rohanin Ahmad
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A new stochastic algorithm called Probabilistic Global Search Johor (PGSJ) has recently been established for global optimization of nonconvex real valued problems on finite dimensional Euclidean space. In this paper we present convergence guarantee for this algorithm in probabilistic sense without imposing any more condition. Then, we jointly utilize this algorithm along with control parameterization technique for the solution of constrained optimal control problem. The numerical simulations are also included to illustrate the efficiency and effectiveness of the PGSJ algorithm in the solution of control problems.
Keywords: Optimal Control Problem, Constraints, Direct Methods, Stochastic Algorithm
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 168961 An Optimal Bayesian Maintenance Policy for a Partially Observable System Subject to Two Failure Modes
Authors: Akram Khaleghei Ghosheh Balagh, Viliam Makis, Leila Jafari
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In this paper, we present a new maintenance model for a partially observable system subject to two failure modes, namely a catastrophic failure and a failure due to the system degradation. The system is subject to condition monitoring and the degradation process is described by a hidden Markov model. A cost-optimal Bayesian control policy is developed for maintaining the system. The control problem is formulated in the semi-Markov decision process framework. An effective computational algorithm is developed, illustrated by a numerical example.
Keywords: Partially observable system, hidden Markov model, competing risks, multivariate Bayesian control.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 217960 Effect of Influent COD on Biological Ammonia Removal Efficiency
Authors: S. H. Mirhossaini, H. Godini, A. Jafari
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Biological Ammonia removal (nitrification), the oxidation of ammonia to nitrate catalyzed by bacteria, is a key part of global nitrogen cycling. In the first step of nitrification, chemolithoautotrophic ammonia oxidizer transform ammonia to nitrite, this subsequently oxidized to nitrate by nitrite oxidizing bacteria. This process can be affected by several factors. In this study the effect of influent COD on biological ammonia removal in a bench-scale biological reactor was investigated. Experiments were carried out using synthetic wastewater. The initial ammonium concentration was 25mgNH4 +-N L-1. The effect of COD between 247.55±1.8 and 601.08±3.24mgL-1 on biological ammonia removal was investigated by varying the COD loading supplied to reactor. From the results obtained in this study it could be concluded in the range of 247.55±1.8 to 351.35±2.05mgL-1, there is a direct relationship between amount of COD and ammonia removal. However more than 351.35±2.05 up to 601.08±3.24mgL-1 were found an indirect relationship between them.Keywords: Ammonia biological removal, Nitrification, InfluentCOD.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 386959 On the Oil Repellency of Nanotextured Aluminum Surface
Authors: G. Momen, R. Jafari, M. Farzaneh
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Two different superhydrophobic surfaces were elaborated and their oil repellency behavior was evaluated using several liquid with different surface tension. A silicone rubber/SiO2 nanocomposite coated (A) on aluminum substrate by “spin-coating" and the sample B was an anodized aluminum surface covered by Teflon-like coating. A high static contact angle about ∼162° was measured for two prepared surfaces on which the water droplet rolloff. Scanning electron microscopy (SEM) showed the presence of micro/nanostructures for both sample A and B similar to that of lotus leaf. However the sample A presented significantly different behaviour of wettability against the low surface tension liquid. Sample A has been wetted totally by oil (dodecan) droplet while sample B showed oleophobic behaviour. Oleophobic property of Teflon like coating can be contributed to the presence of CF2 and CF3 functional group which was shown by XPS analysis.Keywords: Oleophobic, Superhydrophobic, Aluminum surface, Nano-texture.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 224058 Optimal Production and Maintenance Policy for a Partially Observable Production System with Stochastic Demand
Authors: Leila Jafari, Viliam Makis
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In this paper, the joint optimization of the economic manufacturing quantity (EMQ), safety stock level, and condition-based maintenance (CBM) is presented for a partially observable, deteriorating system subject to random failure. The demand is stochastic and it is described by a Poisson process. The stochastic model is developed and the optimization problem is formulated in the semi-Markov decision process framework. A modification of the policy iteration algorithm is developed to find the optimal policy. A numerical example is presented to compare the optimal policy with the policy considering zero safety stock.Keywords: Condition-based maintenance, economic manufacturing quantity, safety stock, stochastic demand.
Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 817