Algorithm for converting a forest of quadtrees to a binary array

An algorithm for reconstructing a binary array of size N sx N from its forest of quadtree representation is presented. The algorithm traverses each tree of the forest in preorder and maps each ‘black’ node into the spatial domain. The time complexity in mapping is O(log N × B_n + B_p), where B_n is the number of black nodes in the forest and B_p is the number of black pixels in the N × N array. The algorithm has been implemented on an Apple II.     

Thermophysical studies on the binary system UO2(NO3)2·6H2O - Sr(NO3)2

Thermoanalytical (TG-DTA-EGA) and X-ray diffraction measurements have been used to study the reaction between uranyl nitrate hexahydrate and strontium nitrate. The results confirmed the absence of a direct interaction between the two compounds. The presence of strontium nitrate, however, ensured that the extent of hydrolysis and polymerisation of uranyl nitrate hexahydrate during its dehydration and decomposition to UO₃ is significantly reduced. DTA curves recorded in both heating and cooling modes gave evidence to the occurrence of a reaction between molten strontium nitrate and uranium trioxide to form nitrato-complexes of uranium and strontium. X-ray diffraction data on reaction residues obtained at different temperatures and cooled to room temperature also showed evidence for the formation of such complexes. The results obtained indicated an increase in thermal stability of these nitrato-complexes with increase in Sr/U ratio. The complex with an Sr/U ratio of 2.0 is stable up to 660 °C and the complex with Sr/U ratio of 4.0 is stable up to 680 °C. These complexes decompose at higher temperatures to give strontium uranates.     

Liquid-waste injection planning via goal programming

In this paper, applications of linear goal programming techniques to the analysis of design, management and operational problems in the deep-well injection industry are investigated. Deep-well injection is a method of hazardous waste disposal where liquid or liquefiable wastes are pumped under controlled rate and pressure into confined formations that have no other potential use. A typical liquid waste injection system is modeled as a linear goal program to study and resolve the effects of conflicting objectives such as cost, environmental regulations, equipment utilization and waste-water quality requirements before injection.

The model is validated using actual data obtained from a waste-water disposal complex in Odessa, Texas. The goal program is solved for the best disposal system design and operating policies that would not only enable the plant to meet the Environmental Protection Agency's standards, but best minimize capital investment, annual operating expense and deviations from the waste-water quality requirements before injection. Justification of the use of the model is presented by comparing the actual design and operating policies of the system with the optimal design obtained from the solution of the model. This comparison showed 40% savings in favor of the design predicted by the model.     

A Multiple Objective Nurse Scheduling Model

The authors present a model for the nurse scheduling problem which works in two phases. In the first phase, the nurses are assigned their day-on/day-off pattern for the two-week scheduling horizon by a goal programming model which allows for consideration of the multiple conflicting objectives inherent in scheduling a nursing staff. The second phase makes specific shift assignments through the use of a heuristic procedure. The two-phase approach results in considerable reductions in problem size, thus reducing the solution effort. Extensions to the basic model are also examined.     

Investigations on Forced Convection in Compact Passages With Surface Irregularities

Two-dimensional, fully developed, convective heat transfer in compact passages is investigated numerically, incorporating the effects of the surface irregularities, to analyze the influence of these irregularities on fluid flow and heat transfer. This analysis helps to bring out the differences in the performance evaluation if regular cross sections are assumed in analyzing compact and mini channels. Forced convection in compact passages with an apparent rectangular shape is analyzed using a finite-difference method. The calculation is validated experimentally using Michelson interferometry. The numerical results for the channel, incorporating surface irregularities, are compared with those assuming a regular cross-sectional geometry. The results indicate that the coefficient of friction and the Nusselt number calculated for channels, considering the irregular cross section, are less than those predicted using an assumption of regular geometry. The results provide some insight into the reasons for the observed deviations in the comparisons. The observations are attributed to the influence of the surface irregularities on the relative dominance of the surface area to the cross-sectional area, which gets pronounced in compact passages. The findings suggest that some of the observed deviations in the performance of compact passages, compared to theoretical results, may be due to the use of regular geometries to define domain shapes while performing theoretical analysis.     

Effect of heat pre-treatment temperature on isolation of hydrogen producing functional consortium from soil

A functional hydrogen producing consortium was isolated from soil by heat pre-treatment technique and hydrogen production at different substrate concentration was evaluated. The forest soil was heat pre-treated at 65, 80, 95, 105 and 120 °C temperature for 1 h. As revealed by PCR-DGGE analysis and hydrogen yield, the hydrogen producing microbial community changed with increase in heat pre-treatment temperatures giving potential hydrogen producing consortium at 95–105 °C soil pre-treatment. The maximum hydrogen production rate, hydrogen yield and cumulative hydrogen with 15–20 g glucose were 1390–1576 mL/L/day, 1.83–1.93 mol H₂/mol glucose, and 2966–3146 mL H₂/L, respectively. The metabolic pathways shifted from ethanol-type to acetate–formate type as soil pre-treatment temperature increased from 65 to 120 °C. The soil heat pre-treatment approach is effective for isolating hydrogen producing natural Clostridium consortium from the soil as enumerations of the functional strains need specific temperature range to florish.     

Phytosterols in Seaweeds: An Overview on Biosynthesis to Biomedical Applications

Seaweed extracts are considered effective therapeutic alternatives to synthetic anticancer, antioxidant, and antimicrobial agents, owing to their availability, low cost, greater efficacy, eco-friendliness, and non-toxic nature. Since the bioactive constituents of seaweed, in particular, phytosterols, possess plenty of medicinal benefits over other conventional pharmaceutical agents, they have been extensively evaluated for many years. Fortunately, recent advances in phytosterol-based research have begun to unravel the evidence concerning these important processes and to endow the field with the understanding and identification of the potential contributions of seaweed-steroidal molecules that can be used as chemotherapeutic drugs. Despite the myriad of research interests in phytosterols, there is an immense need to fill the void with an up-to-date literature survey elucidating their biosynthesis, pharmacological effects, and other biomedical applications. Hence, in the present review, we summarize studies dealing with several types of seaweed to provide a comprehensive overview of the structural determination of several phytosterol molecules, their properties, biosynthetic pathways, and mechanisms of action, along with their health benefits, which could significantly contribute to the development of novel drugs and functional foods.     

Improvements in Mechanical Properties of 319 Al Alloy Engine Blocks Through Cost-Effective Solution Heat Treatment

The use of Al engine blocks has increased significantly to improve vehicle fuel efficiency. However, the gray cast iron cylinder liners cause the development of large tensile residual stress along the cylinder bores which necessitates the optimization of mechanical properties in this region to prevent premature engine failure. This study compared the microstructure of T4-treated Al billet castings of varying cooling rate to that of the cylinder region of T4-treated (current production schedule) Al engine blocks. The aim of this study was to develop a cost-effective small scale heat treatment optimization method for engine block production. Comparisons in microstructure between the engine block and the billet castings were carried out using optical and scanning electron microscopy. The results suggest that the microstructure and hardness at the top, middle, and bottom of the cylinder were similar to those of each representative billet casting, indicating that heat treatment resulted in successful replication of the engine block locations. In addition, tensile testing revealed that the YS and UTS increased slightly following T4 treatment for all billet castings, which was also observed at the middle of the engine block cylinder bridge. As such, this method can be an effective forerunner for future heat treatment optimization in Al engine block production.