A linear genetic programming approach for the prediction of solar global radiation

In this article, the linear genetic programming (LGP) is utilized to predict the solar global radiation. The solar radiation is formulated in terms of several climatological and meteorological parameters. Comprehensive databases containing monthly data collected for 6 years (1995–2000) in two nominal cities in Iran are used to develop LGP-based models. Separate models are established for each city. To verify the performance of the proposed models, they are applied to estimate the solar global radiation of test data of database. The contribution of the parameters affecting the solar radiation is evaluated through a sensitivity analysis. The results indicate that the LGP models give precise estimations of the solar global radiation and significantly outperform traditional angstrom’s model.     

A comparative study of efficient initialization methods for the k-means clustering algorithm

K-means is undoubtedly the most widely used partitional clustering algorithm. Unfortunately, due to its gradient descent nature, this algorithm is highly sensitive to the initial placement of the cluster centers. Numerous initialization methods have been proposed to address this problem. In this paper, we first present an overview of these methods with an emphasis on their computational efficiency. We then compare eight commonly used linear time complexity initialization methods on a large and diverse collection of data sets using various performance criteria. Finally, we analyze the experimental results using non-parametric statistical tests and provide recommendations for practitioners. We demonstrate that popular initialization methods often perform poorly and that there are in fact strong alternatives to these methods.     

Experimental Analysis and Prediction of Springback in V-bending Process of High-Tensile Strength Steels

Experimental setup has been designed, to study the effects of thickness, width, bend angle and machine tool parameters on the springback, in two high-tensile strength steel grades, namely JSC440 and JSC590, during the V-bending process. Relationship between the springback and the parameters are analyzed using plots. Optimal combination of parameters for the minimum springback is evaluated. Analysis of variance has been carried out to analyze the magnitude of influence of these parameters on the springback. Using the experimental results, analytical models for the prediction of springback for the combinations of blank thickness, width, bend angle and machine tool parameters have been developed. Results reveal that in V-bending of JSC440, thickness and width are the dominant factors influencing the springback, whereas in JSC590 steel, insignificant change in springback is observed with the change in width of blank and using the hydraulic press with holding. However, thickness of steel sheet and bend angle influence significantly the springback in JSC590 steels.

     

Transverse vibrations of elliptical plate of linearly varying thickness with half of the boundary clamped and the rest simply supported

The Rayleigh–Ritz method has been applied to study the problem of transverse vibrations of elliptical plate with half of the boundary clamped and the rest simply supported. The thickness of the plate is varying linearly in the space coordinates. For the same thickness variation, the tabulated results in case of mixed boundary conditions lies between those reported for the two extreme cases when the entire boundary is either clamped or simply supported. Convergence of the results is indicated by increasing the order of approximation. Some results for a circular plate of linearly varying thickness with half of the boundary clamped and the rest simply supported have been obtained as special case. Comparisons have been made with the known results. Three-dimensional mode shapes have been drawn for some selected cases.     

Development of a bio-physicochemical technique for arsenic removal from groundwater

Oxidation of ferrous ions by iron-oxidizing bacteria facilitates adsorption of arsenic on iron and subsequent co-precipitation. Based on this technique, a novel treatment process has been developed and tested under field conditions for simultaneous iron and arsenic removal from groundwater. In this study, a biological fixed bed reactor containing coconut husk and subsequent layers of iron matrix, charcoal and sand filter combined the biological and physicochemical treatment processes in a single system. Experimental results showed that arsenic could be efficiently treated from initial concentration of 500 μg L^− 1 to residual (effluent) concentrations lower than 15 μg L^− 1. Simultaneous significant iron removal efficiency (over 95%) was also achieved. Microbial water quality examination confirmed absence of any contamination in the treated water. Simple and inexpensive construction using locally available materials, considerable treatment performance as well as ease of operation and maintenance present the developed system as a promising one.     

Mechanisms of Drylng of Skin-Forming Materials; the Significance of Skin Formation and a Comparison Between Three Types of Material

ABSTRACT

Comparisons are drawn between the drying characteristics, and the mechanisms of skin formation on, three characteristic types of material. The significance of skin formation, which may be a major factor in valatiles retention in the drying of spray dried products, is discussed. The optimum drying conditions to achieve the highest volatiles retention for each type of skin-forming material are predicted. General comparisons are also drawn between the drvine of skin-formine i.e., materials which form a smooth flexible low- parosity skin at same slage, and normal crust-forming materials. The latter form only a rigid crust with a porosity which is system and drying-condition dependent.     

Preparation and evaluation of radioiodinated thermoresponsive polymer based on poly(N‐isopropyl acrylamide) for radiotherapy

A thermoresponsive polymer based on poly N‐isopropylacrylamide (PNIPAM) was synthesized and radioiodinated to explore its potential use in localized radiotherapy. The synthesized PNIPAM polymer was functionalized with L ‐tyrosinamide to facilitate radioiodination. The content of tyrosinamide groups in the polymer was assayed spectrophotometrically (λ = 275nm). The functionalized polymer showed a cloud point temperature of 29–31°C and phase separation at 35°C, as revealed by Differential Scanning Calorimetry (DSC) and Dynamic Light Scattering (DLS). The phase transition temperature is conducive for preferential localization of the polymer at the site of injection due to changes in the polymer conformation at body temperature. For in vivo demonstration, the biodistribution studies of radioiodinated polymer were carried out in Swiss mice bearing fibrosarcoma tumor. Biodistribution studies showed a retention of 30% of the injected labeled polymer, PNIPAM‐¹²⁵I‐tyrosinamide, in the solid tumor tissues after 2 h of intratumoral injection. Although the activity decreased with time, 3–4% of the injected dose (i.d) was found to be retained in the tumor on 5 d post injection. The results suggest the potential use of thermosensitive polymer based on poly N‐isopropylacrylamide for locoregional radionuclide therapy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 860‐868, 2013     

Linker-free chemical preparation of palladium nanoparticles on aluminum-doped zinc oxide electrodes for electrochemical water oxidation

Journal of Materials Science: Materials in Electronics - Despite the growing popularity and promising properties of aluminum-doped zinc oxide (AZO) among other transparent conducting oxides (TCOs),...     

ZnO nanoparticles and polyaniline blend as an active layer for bulk heterojunction solar cell applications

In this work, a facile and straightforward procedure was introduced to prepare a blend as an active layer for hybrid solar cell applications. The active layer consisting of a blend of ZnO nanoparticles (NPs) and polyaniline (PANI) dispersions was deposited by spin coating on ITO covered glasses. The current density–voltage characteristics were studied under AM1.5G standard illumination, without any encapsulation process. Also, the samples were studied using UV–Vis spectroscopy, energy dispersive X-ray spectroscopy (EDS) and field emission-scanning electron microscopy. The investigation is limited just to the active layer, so the cells were fabricated without any interlayer. The effect of various volume ratios of ZnO–NPs:PANI solutions, thickness and the annealing temperature of the active layer on the open circuit voltage and the short circuit current density of the cells were investigated. Moreover, the blending time of ZnO–NPs:PANI dispersions as a significant factor for achieving the optimum results were studied.     

Stability of Viscoelastic Fluid Flowing Through Porous Medium Down Non‐uniformly Heated Inclined Plane

The stability of a thin layer of viscoelastic fluid flowing through a porous medium down a non‐uniformly heated inclined plane with a constant temperature gradient along the plane is considered. The film flow system is influenced by gravity, mean surface tension, thermocapillary forces, viscoelastic forces, porosity, and permeability of porous medium. We seek a solution of the stability problem in a series in small wave numbers, and the obtained results, when the plane is heated in the downstream direction, show that the Marangoni, Galileo, and Biot numbers, porosity, and permeability of the porous medium have dual roles in the stability of the flow system, while the viscoelastic parameter and angle of inclination have stabilizing effects, and the Prandtl number has a destabilizing effect. The effects of these physical parameters are also discussed in the case when the plane is cooled in the downstream direction, and we found that their effects are opposite to those of the previous case. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21105