Experimental and numerical results of dynamics behavior of a nonlinear piezoelectric beam

This article presents a numerical formulation and experimental implementation for the dynamics behavior verification of the nonlinear piezoelectric beam through harmonic excitation. The nonlinear piezoelectric beam dynamic analysis program is developed with MATLAB software. To verify the nonlinear piezoelectric beam dynamic analysis results, the experimental results are used for the vibration analysis of a piezoelectric beam to the harmonic excitation of the base of the beam. Then, the piezoelectric effect on the output voltage, velocity, acceleration values, and the time response are obtained. Afterwards, the effects of the excitation velocity and the position of concentrated mass on the output voltage are verified.     

Optimum lipid production using agro-industrial wastewater treated microalgae as biofuel substrate

Abundant wastewater discharges from palm oil industries in tropical nations being a valuable resource of biodiesel need proper exploration. Research hinted that such wastewater as economical nutrient source or substrate can support the cultivation of microalgae. In this experiment, we have tested the growth and lipid production of five different microalgal strains in palm oil mill effluent (POME). POME as a biofuel substrate is demonstrated to be lucrative for microalgae-assisted lipids production. POME is rich in macro- and micronutrients can be used as a growth medium for algal growth in order to reduce the growth medium cost and environmental pollutions. Among the five microalgal strains tested, Chlorella sorokiniana revealed optimum biomass and lipid production. The productivity was evaluated in terms of chlorophyll content, growth rate, biomass, and lipid content, which discerned to be 0.099/day, 8.0 mg/L day and 2.68 mg/mg cell dry weight (CDW). Furthermore, in this study, an optimization study was carried out to enhance the microalgae to produce high lipid content using carbon-to-nitrogen ratio and different light/dark periods. The presence of nitrogen combined glucose (with a carbon-to-nitrogen ratio 100:7) as an alternative source to carbon displayed higher lipid production of 2.68 (mg/mg CDW) by C. sorokiniana. This study confirms that 8:16 h light/dark condition at C:TN ratio of 100:7 supported to produce high lipid content of 17 mg lipid/mg CDW. The above results revealed that POME could be a suitable growth media for the alga C. sorokiniana to improve the maximum lipid yield for biofuels production.     

SIMULTANEOUS STATE ESTIMATION AND LEARNING IN REPEATED COURNOT GAMES

The aim of this article is to propose that an intelligent agent can be able to decide properly in an incomplete information repeated Cournot game. The market model and the competitors’ decision models are not known to the players. The proposed agent employs a combination of the k-nearest neighbor (KNN) method and the Bayes classifier to predict the next action of its rivals, using the market decision history. The agent takes the predicted actions as an estimate of its next state and learns the expected payoff of its state-action pairs interactively using the reinforcement learning (RL) algorithm. The results of the proposed agent's competition with two benchmark competitors in different simulated Cournot games are presented. The simulation results show that the proposed agent can significantly earn more payoffs in comparison with the two benchmark agents.     

Genetic programming based blind image deconvolution for surveillancesystems

Image acquisition, segmentation, object detection and tracking are essential parts of surveillance systems. Usually, image filtering approaches are employed as preprocessing step to reduce the effect of motion or out-of-focus blur problem. In this paper, we propose genetic programming (GP) based blind-image deconvolution filter. A GP based numerical expression is developed for image restoration which optimally combines and exploits dependencies among features of the blurred image. In order to develop such function, first, a set of feature vectors is formed by considering a small neighborhood around each pixel. At second stage, the estimator is trained and developed through GP process that automatically selects and combines the useful feature information under a fitness criterion. The developed function is then applied to estimate the image pixel intensity of the degraded images. The performance of filter function is estimated using various degraded image sequences. Our comparative analysis highlight the effectiveness of GP based proposed filter.     

The development of spectral indices for detecting built-up land areas and their relationship with land-surface temperature

ABSTRACT

Different spectral indices were provided for the classification of built-up lands using satellite images, but the importance of the blue band in the classification, fusion, and image enhancement prior to the calculation of spectral indices has received less attention so far. This study introduces a new index based on blue band and run it along with six other spectral indices. The method of study is as follows, after the selection of Landsat 7 and Landsat 8 images, the initial pre-processing was done on the images and in the second stage, the enhancement and the fusion were performed. In the third stage, the built-up lands were classified using spectral indices. Otsu’s thresholding method was used on all indices to separate built-up and non-built-up lands. To assess the accuracy, 3500 reference points were used. The results showed that when fusion and image enhancement were performed, overall accuracy (OA) increased by 3% to 6.71% for Landsat 7 images, and 2.14% to 6.71% for Landsat 8 images. The results also showed that after fusion and image enhancement, the visible blue band and first shortwave infrared index (VbSWIR1-BI) with an OA of 92.88% (Landsat 7) and 91.68% (Landsat 8) indicate the highest OA. The percentage of built-up lands changes according to spectral indices ranges from 6.38% to 25 .76% and the largest and lowest amount of built-up land on the basis of the VbSWIR1-BI index belonging to districts 12 and 22, respectively. The results of the spectral indicator show dispread growth during the 14 year period for Tehran. Finally, a significant relationship was observed between surface temperature and built-up land classified by spectral indices.     

Comparative Numerical Investigation on TiO2/Water Nanofluid Turbulent Flow by Implementation of Single Phase and Two Phase Approaches

In this article, turbulent TiO₂/water nanofluid flow and convective heat transfer in a horizontal tube is numerically investigated. Four computer codes were developed for each model (single phase, volume of fluid, mixture, and Eulerian) to simulate this problem. The Finite volume method is applied to solve the two-dimensional steady state governing equations. The results are compared with each other and an experimental work. A model with the most similar results to those of the experimental data and less amount of time for the CPU usage is chosen to develop two correlations for Nusselt number and friction factor based on dimensionless numbers.     

Effect of prepolymerization on propylene polymerization

Polymerization of propylene was performed using MgCl₂. EtOH.TiCl₄.ID.TEA.ED catalyst system in hexane, where internal donor (ID) was an organic diester and external donor (ED) was a silane compound and also triethyl aluminum (TEA) as activator. A new method called isothermal/nonisothermal method (INM), a combination of isothermal and nonisothermal methods, was applied to produce the spherical polymer particles. The effects of the INM method and prepolymerization temperature on the final polymer morphology, M_w, and catalyst activity were also investigated. The morphology of the polymers was evaluated through scanning electron microscopy (SEM) images. GPC results were used for molecular weight (M_w) evaluation. It was found that the polymers had a better morphology when they were prepared using INM method. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A goal programming-TOPSIS approach to multiple response optimization using the concepts of non-dominated solutions and prediction intervals

Multiple response problems include three stages: data gathering, modeling and optimization. Most approaches to multiple response optimization ignore the effects of the modeling stage; the model is taken as given and subjected to multi-objective optimization. Moreover, these approaches use subjective methods for the trade off between responses to obtain one or more solutions. In contradistinction, in this paper we use the Prediction Intervals (PIs) from the model building stage to trade off between responses in an objective manner. Our new method combines concepts from the goal programming approach with normalization based on negative and positive ideal solutions as well as the use of prediction intervals for obtaining a set of non-dominated and efficient solutions. Then, the non-dominated solutions (alternatives) are ranked by the TOPSIS (Technique for Order Preference by Similarity to the Ideal Solution) approach. Since some suggested settings of the input variables may not be possible in practice or may lead to unstable operating conditions, this ranking can be extremely helpful to Decision Makers (DMs). The consideration of statistical results together with the selection of the preferred solution among the efficient solutions by Multiple Attribute Decision Making (MADM) distinguishes our approach from others in the literature. We also show, through a numerical example, how the solutions of other methods can be obtained by modifying the relevant approach according to the DM’s requirements.     

Healing of double oxide film defects in A356 aluminium melt

The possibility of the bonding of the two layers of a double oxide film defect when held in liquid A356 Al alloy was investigated. The defect was modelled experimentally by maintaining two aluminium oxide layers in contact with each other and the atmosphere trapped between them in the A356 liquid alloy for varying lengths of time of between 30 s and 48 h. Any changes in the composition and morphology of these layers were studied by SEM, EDX and XRD. The results showed that the two layers of a double oxide film defect might bond to each other by two different mechanisms, one during the transformation of Al₂O₃ to MgAl₂O₄ spinel in relatively short holding times, which would cause the layers to bond at several points and the other during the gradual transformation of spinel to MgO in longer times, which would cause strong bonding between the layers. It was shown that any bonding can take place essentially only after the oxygen and nitrogen of the atmosphere within the defect are consumed.     

Significance of Soil Dilatancy in Slope Stability Analysis

A finite-element approach is used to analyze the slope stability problem and to examine the effect of soil dilatancy on the stability of slopes. It is found that soil dilatancy has a significant effect on the stability of slopes, and that higher values of dilation angle lead to larger stability numbers. Therefore, the stability numbers obtained from limit analyses (lower∕upper bound solutions) are not conservative for granular soils that exhibit a dilation angle smaller than a soil's friction angle.