Comparison of heuristic approaches for the multiple depot vehicle scheduling problem

Given a set of timetabled tasks, the multi-depot vehicle scheduling problemis a well-known problem that consists of determining least-cost schedulesfor vehicles assigned to several depots such that each task is accomplishedexactly once by a vehicle. In this paper, we propose to compare theperformance of five different heuristic approaches for this problem,namely, a heuristic \\mip solver, a Lagrangian heuristic, a columngeneration heuristic, a large neighborhood search heuristic using columngeneration for neighborhood evaluation, and a tabu search heuristic. Thefirst three methods are adaptations of existing methods, while the last twoare novel approaches for this problem. Computational results on randomlygenerated instances show that the column generation heuristic performs thebest when enough computational time is available and stability is required,while the large neighborhood search method is the best alternative whenlooking for a compromise between computational time and solution quality.tabu search;column generation;vehicle scheduling;heuristics;Lagrangian heuristic;large neighborhood search;multiple depot

Which Investments Improve Student Performance? The Impact of Extracurricular Activities, Paid Classes, and At-Home Internet Use on Student Performance in Secondary School

The importance of education is acknowledged by modern society. As more and more people are willing to invest in education to improve students’ performance, the question of which areas of investment contribute most strongly to better academic performance arises. Parents can choose to involve their children in extracurricular activities, or they can choose to pay for additional classes outside of regular schooling. In addition, the use of technology, or, more specifically, access to the Internet at home, is becoming more and more common, and its influence on student performance is a popular topic of study. In this paper, we use two experiments to uncover the factors that influence students’ performance in Math and Portuguese Language and to support strategies for investment in education

Impacts of interdisciplinary engineering education:A systematic review of the literature

With mono-disciplinary courses, students might have difficulties in understanding the role of the content and methods of multiple disciplines in solving complex problems, such as climate change and global health. Considering existing evidence that interdisciplinary learning environments contribute to student progress in e.g., learning, improving skills, a timely review on their impacts can serve as a comprehensive and convincing rationale for the development of these courses in higher engineering education. This systematic literature review aimed to examine peer-reviewed articles reporting on the impacts of interdisciplinary courses on students. The methods used for the review comprised of three phases: 1) search and inclusion of articles, 2) individual study review, and 3) a cross-study comparison. The key search terms identified to locate articles included “interdisciplinary” and “engineering”. The first phase ended with a screening to eliminate articles using the identified exclusion criteria. We completed the second phase that led to a rubric guided by our inclusion criteria (e.g., goals related to student outcomes, courses in engineering education). Part of the rubric included separate sections for student learning outcomes in the domains; knowledge/understanding, skills, and affect. The rubric then was finalized in the third phase following a cross-study comparison. The results can provide a conceptual basis for improving the current state of interdisciplinary courses in higher engineering education. Finally, researchers will be invited to think of new ways to improve the less positive outcomes that were identified, to assess these outcomes and to enhance interdisciplinary courses for online environments.</p

Rabies Surveillance Identifies Potential Risk Corridors and Enables Management Evaluation

Intensive efforts are being made to eliminate the raccoon variant of rabies virus (RABV) from the eastern United States and Canada. The United States Department of Agriculture (USDA) Wildlife Services National Rabies Management Program has implemented enhanced rabies surveillance (ERS) to improve case detection across the extent of the raccoon oral rabies vaccination (ORV) management area. We evaluated ERS and public health surveillance data from 2006 to 2017 in three northeastern USA states using a dynamic occupancy modeling approach. Our objectives were to examine potential risk corridors for RABV incursion from the U.S. into Canada, evaluate the effectiveness of ORV management strategies, and identify surveillance gaps. ORV management has resulted in a decrease in RABV cases over time within vaccination zones (from occupancy (ψ) of 0.60 standard error (SE) = 0.03 in the spring of 2006 to ψ of 0.33 SE = 0.10 in the spring 2017). RABV cases also reduced in the enzootic area (from ψ of 0.60 SE = 0.03 in the spring of 2006 to ψ of 0.45 SE = 0.05 in the spring 2017). Although RABV occurrence was related to habitat type, greater impacts were associated with ORV and trap–vaccinate–release (TVR) campaigns, in addition to seasonal and yearly trends. Reductions in RABV occupancy were more pronounced in areas treated with Ontario Rabies Vaccine Bait (ONRAB) compared to RABORAL V-RG®. Our approach tracked changes in RABV occurrence across space and time, identified risk corridors for potential incursions into Canada, and highlighted surveillance gaps, while evaluating the impacts of management actions. Using this approach, we are able to provide guidance for future RABV management

Comparison of heuristic approaches for the multiple depot vehicle scheduling problem

Given a set of timetabled tasks, the multi-depot vehicle scheduling problem is a well-known problem that consists of determining least-cost schedules for vehicles assigned to several depots such that each task is accomplished exactly once by a vehicle. In this paper, we propose to compare the performance of five different heuristic approaches for this problem, namely, a heuristic \\mip solver, a Lagrangian heuristic, a column generation heuristic, a large neighborhood search heuristic using column generation for neighborhood evaluation, and a tabu search heuristic. The first three methods are adaptations of existing methods, while the last two are novel approaches for this problem. Computational results on randomly generated instances show that the column generation heuristic performs the best when enough computational time is available and stability is required, while the large neighborhood search method is the best alternative when looking for a compromise between computational time and solution quality

A Comparison of Solar Wind and Estimated Solar System Xenon Abundances: A Test for Solid/ Gas Fractionation in the Solar Nebula

Significant fractionation of dust/gas from the original interstellar cloud during the formation of the solar system is a distinct possibility. Identification of such an effect would provide important clues to nebular processes. Fractionation of volatiles is not constrained by CI abundances and only for the most abundant ones by photospheric observations. The solar Xe elemental abundance is determined here via solar wind measurements from lunar ilmenites and normalized to Si by spacecraft data. The results are compared with estimated abundances assuming no fractionation, which are relatively well constrained for Xe by s-process calculations, odd-mass abundance interpolations, and odd-even abundance systematics. When corrected for solar wind/photospheric fractionation, the ^(130)Xe abundance given by surface layer oxidation of ilmenite from soil 71501, exposed within the last - 200 m.y., is 0.24 ± 0.09 normalized to Si = 10^6. This is indistinguishable from the estimates made assuming no solid/gas fractionation. A similar result was obtained for Kr by Wiens et al (1991). Results from breccia 79035 ilmenite, exposed at least ~1 Gy ago, indicate that the solar wind Xe flux may have been significantly higher relative to other noble gases, perhaps due to more efficient Xe ionization. If this is true, fluxes of C and S, which have similar first ionization potentials to Xe, should also be higher in the ancient solar wind from the same time period, though such variations have not been observed