GAC adsorber design protocol for the removal of off-flavors

This paper investigates the effectiveness of granular activated carbon (GAC) for removing off-flavor compounds of water—geosmin and 2-methylisoborneol (MIB). More specifically, it focuses on the development of an appropriate modeling approach and experimental protocol for the design of fixed-bed GAC adsorbers. Adsorption equilibrium, rate and long-term mini-column studies were conducted on a bench-scale for geosmin and MIB to estimate the equilibrium and mass-transfer parameters required for adsorber modeling. The dispersed flow homogeneous surface diffusion model (DFHSDM) was used for the prediction/simulation of the adsorber dynamics. Scale-up procedures based on dimensional analysis and similitude were employed for the design of full-scale adsorbers from bench-scale adsorbers, and for performance forecasting of full-scale adsorbers under different operating conditions. More importantly, operation and maintenance (O & M) costs were estimated for full-scale adsorbers directed at the removal of off flavor compounds, based on carbon utilization rates and disposal costs. These estimates were obtained for different plant capacities and empty bed contact times (EBCTs).     

A university-timetabling problem and its solution using Benders’ partitioning—a case study

In this paper, we address a university-timetabling problem and present a methodology that relies on Benders’ partitioning for its solution. This partitioning results from the special nature of the underlying integer programming formulation for this problem. We have used our methodology to schedule courses offered by the College of Engineering as well as to those offered university-wide at Virginia Tech. The results clearly depict an improvement in the quality of course schedules obtained by our methodology over those currently used, when the performance of a timetable is measured by the total distance traveled by the faculty members from their offices in respective departments to the classrooms, where the courses are offered.     

Joint Estimation of Human Pose and Conversational Groups from Social Scenes

Despite many attempts in the last few years, automatic analysis of social scenes captured by wide-angle camera networks remains a very challenging task due to the low resolution of targets, background clutter and frequent and persistent occlusions. In this paper, we present a novel framework for jointly estimating (i) head, body orientations of targets and (ii) conversational groups called F-formations from social scenes. In contrast to prior works that have (a) exploited the limited range of head and body orientations to jointly learn both, or (b) employed the mutual head (but not body) pose of interactors for deducing F-formations, we propose a weakly-supervised learning algorithm for joint inference. Our algorithm employs body pose as the primary cue for F-formation estimation, and an alternating optimization strategy is proposed to iteratively refine F-formation and pose estimates. We demonstrate the increased efficacy of joint inference over the state-of-the-art via extensive experiments on three social datasets.     

Comparing top-k XML lists

Systems that produce ranked lists of results are abundant. For instance, Web search engines return ranked lists of Web pages. There has been work on distance measure for list permutations, like Kendall tau and Spearman's footrule, as well as extensions to handle top-k lists, which are more common in practice. In addition to ranking whole objects (e.g., Web pages), there is an increasing number of systems that provide keyword search on XML or other semistructured data, and produce ranked lists of XML sub-trees. Unfortunately, previous distance measures are not suitable for ranked lists of sub-trees since they do not account for the possible overlap between the returned sub-trees. That is, two sub-trees differing by a single node would be considered separate objects. In this paper, we present the first distance measures for ranked lists of sub-trees, and show under what conditions these measures are metrics. Furthermore, we present algorithms to efficiently compute these distance measures. Finally, we evaluate and compare the proposed measures on real data using three popular XML keyword proximity search systems.     

Differential evolution approach for optimal reactive power dispatch

Differential evolution based optimal reactive power dispatch for real power loss minimization in power system is presented in this paper. The proposed methodology determines control variable settings such as generator terminal voltages, tap positions and the number of shunts to be switched, for real power loss minimization in the transmission system. The problem is formulated as a mixed integer nonlinear optimization problem. A generic penalty function method, which does not require any penalty coefficient, is employed for constraint handling. The formulation also checks for the feasibility of the optimal control variable setting from a voltage security point of view by using a voltage collapse proximity indicator. The algorithm is tested on standard IEEE 14, IEEE 30, and IEEE 118-Bus test systems. To show the effectiveness of proposed method the results are compared with Particle Swarm Optimization and a conventional optimization technique – Sequential Quadratic Programming.     

Influence of wettability on the recovery of NAPLs from alluvium

The physicochemical characteristics of five nonaqueous phase liquids (NAPLs) recovered from contaminated alluvial aquifers are presented. The five include two chlorinated degreasing solvents, one chlorinated dry-cleaning solvent and two weathered fuel hydrocarbons. In addition to density, viscosity, and interfacial tensions, the equivalent alkane carbon number (EACN), spreading coefficients and Amott-Harvey and USBM wettability indices with respect to alluvial aquifer materials are used as a means to characterize three of these NAPLs. Experimentally measured spreading coefficients of four of these NAPLs illustrate that field NAPLs can have positive initial spreading coefficients. Furthermore, capillary desaturation curves for two NAPLs with alluvial aquifer material collected from the NAPL zone are presented as an additional and important means to infer the practical implications of the wetting characteristics on the efficacy of NAPL recovery. The results from the wettability and capillary desaturation experiments show that these NAPLs are mixed-wet to oil-wet when measured in the alluvium from their respective field sites. Furthermore, these results indicate that the displacement of NAPLs from soils by water is more difficult for mixed-wet or oil-wet soils than it is for water-wet or weakly water-wet soils. Finally experimental data indicate that adding anionic surfactants to the water shifts the wettability toward water-wet and makes the NAPL easier to displace and recover.     

An objective function for vertically partitioning relations in distributed databases and its analysis

Partitioning and allocation of relations is an important component of the distributed database design. Several approaches (and algorithms) have been proposed for clustering data for pattern classification and for partitioning relations in distributed databases. Most of the approaches used for classification use square-error criterion. In contrast, most of the approaches proposed for partitioning of relations are eitherad hoc solutions or solutions for special cases (e.g., binary vertical partitioning).In this paper, we first highlight the differences between the approaches taken for pattern classification and for distributed databases. Then an objective function for vertical partitioning of relations is derived using the square-error criterion commonly used in data clustering. The objective function derived generalizes and subsumes earlier work on vertical partitioning. Furthermore, the approach proposed in this paper is shown to be useful for comparing previously developed algorithms for vertical partitioning. The objective function has also been extended to include additional information, such as transaction types, different local and remote accessing costs and replication. Finally, we discuss the implementation of a distributed database design testbed. Recommended by: A. Sheth     

Photooxidation and biotrickling filtration for controlling industrial emissions of trichloroethylene and perchloroethylene

A two-stage process integrating ultraviolet oxidation and biotrickling filtration (UV-BTF) was developed for treatment of industrial air streams contaminated with trichloroethylene (TCE) and perchloroethylene (PCE). Laboratory-scale studies demonstrated that the UV-BTF system consistently achieved contaminant removal efficiencies of 99-100% under optimal conditions. The UV-BTF process employs an advanced oxidation process (AOP) such as UV photooxidation as pretreatment for alleviating biological toxicity attributed to high and/or fluctuating contaminant concentrations, and for transforming the contaminants to more easily biodegradable products. The UV-BTF process showed significantly better performance than the BTF process without UV photooxidation pretreatment. Free-radical reaction mechanisms, pathways, and product formations were proposed for the UV photolysis of TCE and PCE. The photooxidation was mediated by chlorine atom reactions, and the principal products for TCE were phosgene, dichloroacetyl chloride (DCAC), low levels of trichloroacetyl chloride (TCAC), carbon monoxide, and hydrochloric acid; while those for PCE were phosgene, TCAC, low levels of DCAC, carbon dioxide, and hydrochloric acid. These products were identified and quantified by a combination of techniques, namely, gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared (FTIR) spectroscopy. These photooxidation products were completely removed in the BTF stage of the UV-BTF process, as indicated by subsequent GC-MS analyses. The destruction of photolysis products in the BTF stage occurred by a combination of hydrolysis, adsorption and microbial degradation.     

Discrepancies between the NMR and X-ray structures of uncomplexed barstar: analysis suggests that packing densities of protein structures determined by NMR are unreliable

The crystal structure of the C82A mutant of barstar, the intracellular inhibitor of the Bacillus amyloliquefaciens ribonuclease barnase, has been solved to a resolution of 2.8 A. The molecule crystallizes in the space group I41 with a dimer in the asymmetric unit. An identical barstar dimer is also found in the crystal structure of the barnase-barstar complex. This structure of uncomplexed barstar is compared to the structure of barstar bound to barnase and also to the structure of barstar solved using NMR. The free structure is similar to the bound state, and there are no significant main-chain differences in the 27-44 region involved in barstar binding to barnase. The C82A structure shows significant differences from the average NMR structure, both overall and in the binding region. In contrast to the crystal structure, the NMR structure shows an unusually high packing value based on the occluded surface algorithm, indicating errors in the packing of the structure. We show that the NMR structures of homologous proteins generally show large differences in packing value, while the crystal structures of such proteins have very similar packing values, suggesting that protein packing density is not well determined by NMR.