Effect of steam treatment on the activities of Pt/NH4-MOR catalysts for n-pentane hydroisomerization and hydrocracking

The rationale of this work is to study the effect of using Pt containing catalysts supported on NH₄-MOR zeolite, before or after steaming, to show how steam treatments affect the activities of catalysts used primarily for the hydroconversion of light naphtha to improve its octane rating. Hence, the reactions of the hydroisomerization and hydrocracking of n-pentane, were investigated at temperatures between 250 and 500 °C in a pulsed microcatalytic reactor using catalysts containing 0.25, 0.35 and 0.60 wt.% Pt supported on NH₄-MOR. The effect of steaming on the dispersion of Pt, acid sites strength distribution, intraparticle diffusion resistance and the catalytic activities were investigated. Steaming was found to enhance catalytic activity deterioration. This effect was significantly increased with increasing Pt content in the catalysts. The calculated activation energy and entropy values using the current catalysts were correlated with the activity levels for hydroisomerization and hydrocracking of n-pentane.     

Effect of strain rate and temperature on the tensile properties of MANET II steel

MANET II, a modified 12% Cr steel with the German designation DIN 1.4914, is a candidate structural material for the first wall and blanket in fusion reactors. In the present study, the tensile properties of this steel were investigated in the temperature range of 25 to 350 °C at strain rates of 5 x 10^-5 ,1.2 x 10^-4, and 1.2 x 10^-3s-1, Both microstructure and fracture surfaces were examined using optical and scanning electron microscopic (SEM) techniques. The results showed that the steel suffers dynamic strain aging, although no serrated flow was observed. Yield strength, ultimate strength, and elongation showed negative strain rate sensitivity. Dynamic strain aging also affected the strain hardening rate. Results are discussed with regard to the chemical composition and fracture surface morphology.     

Economic analysis of photovoltaic-powered solar domestic hot water systems in Kuwait

The present paper first presents a comparison between the photovoltaic four-parameter and five-parameter models. The comparison was performed using polycrystalline and amorphous silicon solar cells. The results showed that the four-parameter model can accurately determine the I–V characteristics of single- and polycrystalline solar cells. On the other hand, the five-parameter model can be used to accurately determine the I–V characteristics of amorphous solar cells in addition to its capability of predicting the I–V characteristics of single- and polycrystalline solar cells.Secondly, the economic feasibility of photovoltaic-powered solar water heating systems in Kuwait has been examined. The system includes photovoltaic arrays instead of solar collectors used in common solar water heating systems. The five-parameter model was used to simulate the performance of amorphous silicon modules used with the photovoltaic-powered solar water heating systems. Oil prices in the range of US$20–30 per barrel were studied. At the current prices of photovoltaic modules and a low oil price, photovoltaic-powered solar water heating systems were found to be economical. On the other hand, assuming a low oil price, the price of photovoltaic modules should be reduced to 50% of their current prices to make photovoltaic-powered solar water heating systems feasible in the Kuwaiti climate.     

Drivers and barriers to adopting EDI: a sector analysis of UK industry

This paper presents the results of research comparing the effects of Electronic Data Interchange (EDI) on seven UK industry sectors. The sectors investigated were retail, manufacturing, distribution, utilities, pharmaceutical, government and services. The analysis focuses in particular on similarities and differences in the implementation process and examines the difficulties experienced and benefits achieved by the various industry sectors. Further, the level of EDI integration with internal business processes is investigated. A framework is described which is based on a survey, a case study of successful EDI implementation and interviews with both service providers and users. It provides a potential tool for practitioners covering important aspects of EDI implementation and integration.     

Characterizing game dynamics in two-player strategy games using network motifs.

Many complex systems, whether biological, sociological, or physical ones, can be represented using networks. In these networks, a node represents an entity, and an arc represents a relationship/constraint between two entities. In discrete dynamics, one can construct a series of networks with each network representing a time snapshot of interaction among the different components in the system. Understanding these networks is a key to understand the dynamics of real and artificial systems. Network motifs are small graphs-usually three to four nodes-representing local structures. They have been widely used in studying complex systems and in characterizing features on the system level by analyzing locally how the substructures are formed. Frequencies of different network motifs have been shown in the literature to vary from one network to another, and conclusions hypothesized that these variations are due to the evolution/dynamics of the system. In this paper, we show for the first time that in strategy games, each game (i.e., type of dynamism) has its own signature of motifs and that this signature is maintained during the evolution of the game. We reveal that deterministic strategy games have unique footprints (motifs' count) that can be used to recognize and classify the game's type and that these footprints are consistent along the evolutionary path of the game. The findings of this paper have significance for a wide range of fields in cybernetics.     

Optic disc detection from normalized digital fundus images by means of a vessels' direction matched filter

Optic disc (OD) detection is a main step while developing automated screening systems for diabetic retinopathy. We present in this paper a method to automatically detect the position of the OD in digital retinal fundus images. The method starts by normalizing luminosity and contrast through out the image using illumination equalization and adaptive histogram equalization methods respectively. The OD detection algorithm is based on matching the expected directional pattern of the retinal blood vessels. Hence, a simple matched filter is proposed to roughly match the direction of the vessels at the OD vicinity. The retinal vessels are segmented using a simple and standard 2-D Gaussian matched filter. Consequently, a vessels direction map of the segmented retinal vessels is obtained using the same segmentation algorithm. The segmented vessels are then thinned, and filtered using local intensity, to represent finally the OD-center candidates. The difference between the proposed matched filter resized into four different sizes, and the vessels' directions at the surrounding area of each of the OD-center candidates is measured. The minimum difference provides an estimate of the OD-center coordinates. The proposed method was evaluated using a subset of the STARE project's dataset, containing 81 fundus images of both normal and diseased retinas, and initially used by literature OD detection methods. The OD-center was detected correctly in 80 out of the 81 images (98.77%). In addition, the OD-center was detected correctly in all of the 40 images (100%) using the publicly available DRIVE dataset.     

Characteristics and effect of thermal treatment on surface texture of ultrafine zirconia powders

Yttria-stabilized zirconia ultrafine powders were prepared by the hydrolysis of their hydroxide at 200° C. The powders obtained were investigated for their crystal structure and degree of fineness. The surface characteristics of the prepared powders were determined by nitrogen gas adsorption. The effect of calcination conditions on the powder characteristics were thoroughly investigated and the results discussed in relation to their surface textures and degree of crystallinity.