Nanotechnology‐based wastewater treatment

Water contamination is a global challenge impacting both the environment and human health with significant economic and social costs. The growing scarcity of usable water resources requires effective treatment of wastewater. In this context, developing cheaper, safer and more efficient wastewater treatment technologies are the need of the hour. One promising approach that several studies have reported success has been the usage of nanomaterials in water and waste water management. The rapid progress of research in nanomaterial sciences has shown their growing potential; however, there has not been a great amount of information available on their implementation. This review focuses on developments in nanotechnology that hold strong potential for wastewater treatment. The review covers key techniques in nanomaterial‐based water treatments including adsorption, filtration and photocatalysis with recent examples showing how to improve their properties and efficiencies according to the need.     

Heat Transfer Analysis for Gas-to-Liquids Transportation Through Trans Alaska Pipeline

Gas-to-liquids (GTL) technology involves the conversion of natural gas to liquid hydrocarbons. In this article, theoretical studies have been presented to determine the feasibility of transporting GTL products through the Trans-Alaska Pipeline System (TAPS). To successfully transport GTL through TAPS, heat loss along the route must be carefully determined. This study presents heat transfer and fluid dynamic calculations to evaluate this feasibility. Because of heat loss, the fluid temperature decreases in the direction of flow and this affects the fluid properties, which in turn influence convection coefficient and pumping power requirements. The temperature and heat loss distribution along the pipeline at different locations have been calculated. Fairly good agreement with measured oil temperatures is observed. The powers required to pump crude oil and GTL individually, against various losses have been calculated. Two GTL transportation modes have been considered; one as a pure stream of GTL and the second as a commingled mixture with crude oil. These results show that the pumping power and heat loss for GTL are less than that of the crude oil for the same volumetric flow rate. Therefore, GTL can be transported through TAPS using existing equipment at pump stations.     

Convergent and discriminant validity of selected assertiveness measures.

Used D. T. Campbell and D. W. Fiske's (see record 1976-20103-001) multitrait-multimethod design and D. N. Jackson's (see record 1976-00077-001) multimethod factor analysis to investigate the convergent and discriminant validity of selected assertiveness measures as compared with those of aggression and dominance. The selected assertiveness measures were the College Self-Expression Scale (J. P. Galassi et al; see record 1974-30156-001), the Wolpe-Lazarus Assertiveness Questionnaire (J. Wolpe and A. Lazarus, 1966), and global self-ratings of assertiveness. 159 undergraduates served as Ss. Results provide strong support for the convergent and discriminant validity of the assertiveness measures. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Game theory methodology for optimizing retailers’ pricing and shelf-space allocation decisions on competing substitutable products

This paper examines the influence of competition among supply chain partners on product demand. A power law demand function that depends on product pricing and shelf-space allocation (SSA) is used. The exponents in the power law are given by the elasticities of demand. In order to achieve the optimal pricing and SSA strategies in the presence of competition, game-theory-based methodologies—Cournot and Stackelberg games—are employed. For each type of game, a Nash equilibrium is achieved by optimizing the profit as a function of demand and price. A case study is presented to demonstrate the potential of this methodology. The results of this study indicate (1) how to achieve optimal pricing and SSA strategies, (2) how manufacturers can influence demand for a product, (3) that both prices and profits decrease using the Stackelberg game as compared with the Cournot game, and (4) that coordination beyond simple knowledge of price would be beneficial for improving overall profits.     

Degradation of chlorpyrifos contaminated soil by bioslurry reactor operated in sequencing batch mode: bioprocess monitoring

Bioslurry reactor (SS-SBR) was studied for the degradation of chlorpyrifos contaminated soil using native mixed microflora, by adopting sequencing batch mode (anoxic-aerobic-anoxic) operation. Reactor operation was monitored for a total cycle period of 72 h consisting of 3 h of FILL, 64 h REACT, 2 h of SETTLE, and 3 h of DECANT with chlorpyrifos concentrations of 3000 micrpg/g, 6000 microg/g and 12000 microg/g. At 3000 microg/g of chlorpyrifos concentration, 91% was degraded after 72 h of the cycle period, whereas in the case of 6000 microg/g of chlorpyrifos, 82.5% was degraded. However, for 12000 microg/g of chlorpyrifos, only 14.5% degradation was observed. The degradation rate was rapid at lower substrate concentration and 12000 microg/g of substrate concentration was found to be inhibitory. Chlorpyrifos removal rate was slow during the initial phase of the sequence operation. Half-life of chlorpyrifos degradation (t0.5) was estimated to be 6.3 h for 3000 microg/g of substrate, 17.5 h for 6000 microg/g and 732.2 h for 12000 microg/g. Process performance was assessed by monitoring chlorpyrifos concentration and biochemical process parameters viz., pH, oxidation and reduction potential (ORP), dissolved oxygen (DO), oxygen consumption rate (OCR) and microbial count (CFU) during sequence operation. From the experimental data obtained it can be concluded that the rate-limiting step with the bioslurry phase reactor in the process of chlorpyrifos degradation may be attributed to the concentration of substrate present in either soil or liquid phase. Periodic operations (SBR) by varying individual components of substrate with time in each process step place micro-organisms under nutritional changes from feast to famine and maintains a wide distribution in the population of micro-organisms resulting in high uptake of the substrate in the bioslurry reactor.     

Exploring optimization and caching for efficient collection operations

Many large programs operate on collection types. Extensive libraries are available in many programming languages, such as the C++ Standard Template Library, which make programming with collections convenient. Extending programming languages to provide collection queries as first class constructs in the language would not only allow programmers to write queries explicitly in their programs but it would also allow compilers to leverage the wealth of experience available from the database domain to optimize such queries. This paper describes an approach to reduce the run time of programs involving explicit collection queries by performing run time query optimization that is effective for single runs of a program. In addition, it also leverages a cache to store previously computed results. The proposed approach relies on histograms built from the data at run time to estimate the selectivity of joins and predicates in order to construct query plans. Information from earlier executions of the same query during run time is leveraged during the construction of the query plans, even when the data has changed between these executions. An effective cache policy is also determined for caching the results of join (sub) queries. The cache is maintained incrementally, when the underlying collections change, and use of the cache space is optimized by a cache replacement policy. Our approach has been implemented within the Java Query Language (JQL) framework using AspectJ. Our approach demonstrated that its run time query optimization in integration with caching sub query result significantly improves the run time of programs with explicit queries over equivalent programs performing collection operations by iterating over those collections. This paper evaluates our approach using synthetic as well as real world Robocode programs by comparing it to JQL as a benchmark. Experimental results show that our approach performs better than the JQL approach with respect to the program run time.     

Thermal Properties of Petroleum and Gas-to-liquid Products

There are many locations in the world where natural gas is abundant, but isolated from the transportation infrastructure. Research is currently underway to develop methods to convert the gas to liquid (GTL) and transport it to the market. For safe and efficient transportation of this GTL, researchers and engineers must know its properties. This article presents several correlations for viscosity, specific heat, and thermal conductivity of this GTL. Researchers are also considering transportation of GTL commingled with crude oil. Therefore, the properties of this commingled mixture are presented here as well. Data on how these properties vary with temperature is also presented in graphs; this information would be very useful for designing a method of transportation in extremely cold regions.     

Malware detection by pruning of parallel ensembles using harmony search

Detection of malware using data mining techniques has been explored extensively. Techniques used for detecting malware based on structural features rely on being able to identify anomalies in the structure of executable files. The structural attributes of an executable that can be extracted include byte ngrams, Portable Executable (PE) features, API call sequences and Strings. After a thorough analysis we have extracted various features from executable files and applied it on an ensemble of classifiers to efficiently detect malware. Ensemble methods combine several individual pattern classifiers in order to achieve better classification. The challenge is to choose the minimal number of classifiers that achieve the best performance. An ensemble that contains too many members might incur large storage requirements and even reduce the classification performance. Hence the goal of ensemble pruning is to identify a subset of ensemble members that performs at least as good as the original ensemble and discard any other members.     

Residence time in a single screw free helix extruder using a new solution to the biharmonic equation

A new analytical solution for the biharmonic equation was developed for single screw extrusion cross-channel fluid mechanical flow. This analysis led to a quantitative model for residence time distribution when combined with the historic solutions of the drag and pressure flow in the rectangular channel in the single-screw extruder. The focus of the theoretical and experimental investigation here was to examine how closely the new analytical solution correlated with experimental residence time data for a free-helix extruder. This new extrusion device was operated as both a conventional extruder and a more positive displacement device by using only helix rotation as the pump. The Moffatt eddies that occur in the quiescent corners of the rectangular channel with screw rotation were found to have a strong effect on the residence time of the extruder. Because there were no quiescent corners for the free-helix flow there was essentially no residence time tail for this mode of extruder displacement. The theoretical results for a sheet of dye spanning the screw channel width and dye “blobs” were compared with experimental results for both modes of operation. In all cases, the experiments and the theory predictions were essentially consistent.     

Synthesis of Metastable, Wurzite-Based Zinc Oxide-Cobalt(II) Oxide Solid Solutions by Spray Pyrolysis

Aqueous solutions of acetates and nitrates of zinc and cobalt have been spray decomposed to study the production of extended solid solutions in the ZnO–CoO system. Examination of the products of a variety of synthesis conditions indicates that up to 70% CoO may be retained in the solid solution in the wurzite phase, even though a comparison of the equilibrium solubility in the phase diagram might be expected to favor the formation of a rock-salt-based solid solution.