Search

Service-oriented architectures have become increasingly prevalent in internet application design, leading to a proliferation of services. Managing and composing these web services pose a classic non-deterministic polynomial-time hard problem. The web service composition problem (WSCP) based on the input–output model (IOM) involves the automatic composition of services without relying on a pre-defined workflow. Multi-objective evolutionary algorithms offer a solution that goes beyond simple weighted average calculations for quality of service, catering to diverse user needs in service composition. This paper introduces a multi-objective heuristic algorithm based on the SPEA2 called MSPEA2+. Specific modifications are incorporated in MSPEA2+ to support the breeding, crossover, and mutation processes, tailored for IOM-based WSCP. Validating the algorithm performance through finding suitable combination results for each task in the WSC-08 dataset, our experiments showed that MSPEA2+ has better iterative efficiency than existing multi-objective methods and outperforms them in terms of quality of service. MSPEA2+ achieved the lowest IGD value across all seven tasks, an improvement of 81.7% IGD value compared with the SPEA2 algorithm in WSC-0804. [ABSTRACT FROM AUTHOR]

A novel wastewater treatment process, known as an alternating activated sludge reactor (AASR), is proposed to treat wastewater in full-scale operations. The AASR is a technical development based on the sequencing batch reactor (SBR) and cyclic activated sludge technology (CAST). The performance of AASR was evaluated in this study and found to be effective for the removal of pollutants. The average effluent NH4+-N, TN, TP, and COD concentrations were 0.5, 17, 0.8, and 40 mgL−1, respectively. The corresponding average removal efficiencies were 97%, 59%, 83%, and 83%, respectively, indicating that the AASR was also a successful operating system for the removal of organic matter. The AASR has many advantages, such as successive filling, high removal efficiency, high stability and reliability, low area requirement, no sludge circulation reflux, and low construction costs. The operation mode of the alternating anoxic, anaerobic, and aerobic conditions displayed a higher efficiency for nitrification than that of conventional SBR. The effective mode for denitrification was a step-feed. The control program of the AASR is highly flexible and can easily be modified by a plant manager to meet various loading requirements. [ABSTRACT FROM AUTHOR]

International service learning (ISL) programs seek to facilitate community inclusion, but such participation can prove elusive. For technical projects, such ventures can undermine local leadership, generate mistrust in communities, and even create an aversion to technological solutions. In this article, we document how social work and engineering students collaborated to bring clean water to rural Guatemala, and demonstrate how we employed social work principles to address the myriad issues encountered in the project. We contend that the inclusion of a social work perspective, with its emphasis on relationships, can help mitigate some of the challenges ISL projects tend to encounter. [ABSTRACT FROM AUTHOR]

This study evaluated the role of physical and biological filter characteristics on the reduction of MS2 bacteriophage in biosand filters (BSFs). Three full-scale concrete Version 10 BSFs, each with a 55 cm sand media depth and a 12 L charge volume, reached 4 log10 reduction of MS2 within 43 days of operation. A consistently high reduction of MS2 between 4 log10 and 7 log10 was demonstrated for up to 294 days. Further examining one of the filters revealed that an average of 2.8 log10 reduction of MS2 was achieved within the first 5 cm of the filter, and cumulative virus reduction reached an average of 5.6 log10 after 240 days. Core sand samples from this filter were taken for protein, carbohydrate, and genomic extraction. Higher reduction of MS2 in the top 5 cm of the sand media (0.56 log10 reduction per cm vs 0.06 log10 reduction per cm for the rest of the filter depth) coincided with greater diversity of microbial communities and increased concentrations of carbohydrates. In the upper layers, "Candidatus Nitrosopumilus maritimus" and "Ca. Nitrospira defluvii" were found as dominant populations, while significant amounts of Thiobacillus-related OTUs were detected in the lower layers. Proteolytic bacterial populations such as the classes Sphingobacteria and Clostridia were observed over the entire filter depth. Thus, this study provides the first insight into microbial community structures that may play a role in MS2 reduction in BSF ecosystems. Overall, besides media ripening and physical reduction mechanisms such as filter depth and long residence time (45 min vs 24 ± 8.5 h), the establishment of chemolithotrophs and proteolytic bacteria could greatly enhance the reduction of MS2.