Modelling and parameter estimation of ultra-dispersed in situ catalytic upgrading experiments in a batch reactor

In situ catalytic upgrading of heavy oil and bitumen has been suggested and tested in the laboratory for utilization of heavy oil resources. Experimental observations have demonstrated potential, so this innovative recovery technique may have a role in the development of large resources of heavy oil and bitumen. Accurate analytical and numerical modelling is necessary in order to correctly interpret experimental measurements of the in situ upgrading, leading to a better understanding and design of field-scale processes. In this paper, we present modelling and parameter estimation for ultra-dispersed catalytic upgrading experiments conducted in a batch reactor. The Monte Carlo simulation technique was used to estimate the most appropriate reaction parameters. The combination of an analytical batch reactor model and the Monte Carlo simulation technique allows for the fast generation of a large number of upgrading experiment realizations. Comparisons of analytical modelling results with the experimental measurements of the upgrading experiments at different temperatures are in close agreement. Results reveal that ultra-dispersed catalytic upgrading in a batch reactor results in a fairly high residue conversion and can potentially increase the API gravity of the produced oil.     

Nodular structure of isotactic polypropylene crystallizes from the melt

This article highlights the melt crystallization behavior of different grades of isotactic polypropylene (iPP) using a hot‐stage polarizing optical microscopy. iPP samples were heated up at a heating rate of 10°C/min passing the melting temperature and then kept for 3 min at a temperature range of 175–200°C before they cooled rapidly at 40°C/min to crystallize isothermally at a range of 130–145°C. It has been found that the temperature at which the samples were kept has a strong effect on the crystallization mode; for samples heated up and kept at temperatures below 190°C, the crystallization started with thin and long rods or nodules, which grew in the circumferential direction only while their lengths remain unchanged as the time passed. The shape of the nodules can be straight, circular, branched, or entangled, and they can grow parallel to each other or they can be crossed or in a random way. This phenomenon disappeared completely for samples melted and kept at temperatures above 195°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Operations research/management science in the Arab world: historical development

This study aims to review the related literature on operations research (OR)/management science (MS) in the Arab world published during the last three decades. Owing to the nature of this study, an extensive survey of the related literature was conducted and inferences were drawn. The inferences drawn from the literature survey on OR/MS in the Arab world were first, there is a paucity of published real‐world applications of OR/MS. Second, there is a lack of published survey‐type studies in most Arab countries, except in Jordan, Lebanon, Palestine, Syria, and the United Arab Emirates. Third, the majority of published works on OR/MS were of a conceptual nature. A few papers concerned with OR/MS in the Arab world were published during the 1980s, with a special emphasis on conceptual issues rather than on applied or survey‐type studies. The 1990s witnessed an increased number of publications on both survey‐type and conceptual studies. Since 2000, the number of publications has increased substantially, mainly through conceptual studies. This study has a number of implications for both practitioners and researchers. Practitioners will be made aware of the applications of OR/MS in the Arab world and the type of problems that have been addressed. This, in turn, might motivate the decision makers and the managers to adopt OR/MS approaches in solving their organizations' problems. As a result, this might increase the usage of OR/MS in this part of the world. Researchers will be able to identify the OR/MS research areas that need more attention in the Arab world. The study mainly covers the studies that are written in English and indexed in non‐Arabic databases. Although the Arabic works were not surveyed exhaustively, the author reviewed and included some available OR/MS works written in Arabic. This study is considered as the first work of its type in surveying the scholarly publications pertaining to OR/MS in the Arab world since the 1980s.     

Application of ozone for enhancing the microbiological safety and quality of foods: a review.

Ozone (O3) is a strong antimicrobial agent with numerous potential applications in the food industry. High reactivity, penetrability, and spontaneous decomposition to a nontoxic product (i.e., O2) make ozone a viable disinfectant for ensuring the microbiological safety of food products. Ozone has been used for decades in many countries and recently, the generally recognized as safe (GRAS) status of this gas has been reaffirmed in the United States. Ozone, in the gaseous or aqueous phases, is effective against the majority of microorganisms tested by numerous research groups. Relatively low concentrations of ozone and short contact time are sufficient to inactivate bacteria, molds, yeasts, parasites, and viruses. However, rates of inactivation are greater in ozone demand-free systems than when the medium contains oxidizable organic substances. Susceptibility of microorganisms to ozone also varies with the physiological state of the culture, pH of the medium, temperature, humidity, and presence of additives (e.g., acids, surfactants, and sugars). Ozone applications in the food industry are mostly related to decontamination of product surface and water treatment. Ozone has been used with mixed success to inactivate contaminant microflora on meat, poultry, eggs, fish, fruits, vegetables, and dry foods. The gas also is useful in detoxification and elimination of mycotoxins and pesticide residues from some agricultural products. Excessive use of ozone, however, may cause oxidation of some ingredients on food surface. This usually results in discoloration and deterioration of food flavor. Additional research is needed to elucidate the kinetics and mechanisms of microbial inactivation by ozone and to optimize its use in food applications.     

Response to simulated typical daily outdoor irradiation conditions of thin-film silicon-based triple-band-gap,triple-junction solar cells

We studied the response to various realistic outdoor conditions of thin-film silicon-based triple-band-gap, triple-junction cells that were made in house. The triple-junction cells consist of a stack of proto-Si:H/proto-SiGe:H/nanocrystalline (nc)-Si:H cells in an n–i–p configuration, fabricated using hot-wire chemical vapour deposition (CVD). Current matching was determined for modeled spectra of four different days of the year that are typical for the northwestern European climate. Spectral modeling was based on measured irradiation data. The results showed that on a clear day in June, when the actual spectrum was closest to the reference AM1.5 spectrum, the matching was ideal. As the spectral shape varied during the course of the day with respect to the AM1.5 reference the matching became progressively worse. We found that the top cell (1.8 eV) and bottom cell (1.1 eV) are most sensitive to spectral changes, whereas the middle cell (1.5 eV) is less sensitive. Overall, it was evident that either cloudiness or seasonal variations led to an increase in current mismatch between the cells. If the sub-cells are closely matched, it may even occur that a cell designed to be current limiting no longer fulfills that role.     

Cyanoethylation of Hydroxyethyl Cellulose: Preparation and Characterization

Commercial hydroxyethyl cellulose (HEC) was cyanoethylated with acrylonitrile in nonaqueous medium in the presence of sodium hydroxide under a variety of conditions. Variables studied included the amount of acrylonitrile and the reaction temperature. The reaction was proved by NMR and its extent was measured by determining the nitrogen content. The physical properties of the obtained derivatives—i.e., the electric properties and the apparent viscosity at various rates of shear—were investigated. It was found that the extent of reaction was increased by increasing the amount of acrylonitrile as well as the reaction temperature. The products were water soluble and their apparent viscosity increased with increasing nitrogen content. The same holds true for the dielectric constant and dielectric loss.     

Ability of adaptive filters to track carrier offsets and channelnonstationarities

This paper studies the tracking performance of adaptive filters operating in the presence of two sources of nonstationarities: carrier frequency offsets and random channel variations. Both impairments are common in digital communications due to mismatches between transmitter and receiver carrier generators and channel fading. The paper derives expressions for the mean-square error and shows how filter performance is degraded under such nonstationary conditions. Selections of step sizes for optimal tracking performance are derived, different adaptive algorithms are compared, and supporting simulation results are provided     

Microstructure evolution of the full transition of bismuth metal to a bismuth oxide particulate

A morphological study is presented showing the evolution of a bismuth particle during its full oxidation and above its melting temperature at 873 K. The results are in good agreement with the theoretical data obtained by solving the Fick's equation relative to the steady diffusion of a reactant through an oxide layer.