A Constraint Programming Approach for Non-Preemptive Evacuation Scheduling

Large-scale controlled evacuations require emergency services to select evacuation routes, decide departure times, and mobilize resources to issue orders, all under strict time constraints. Existing algorithms almost always allow for preemptive evacuation schedules, which are less desirable in practice. This paper proposes, for the first time, a constraint-based scheduling model that optimizes the evacuation flow rate (number of vehicles sent at regular time intervals) and evacuation phasing of widely populated areas, while ensuring a nonpreemptive evacuation for each residential zone. Two optimization objectives are considered: (1) to maximize the number of evacuees reaching safety and (2) to minimize the overall duration of the evacuation. Preliminary results on a set of real-world instances show that the approach can produce, within a few seconds, a non-preemptive evacuation schedule which is either optimal or at most 6% away of the optimal preemptive solution.Comment: Submitted to the 21st International Conference on Principles and Practice of Constraint Programming (CP 2015). 15 pages + 1 reference pag

A Case Study of the Massachusetts Department of Early Education and Care - Executive Summary

On July 1, 2005, Massachusetts became the first state in the nation to launch an independent department with a primary focus on early education and care. This innovative governance structure was created to have equal standing with the state's Department of Education (DOE) and Board of Higher Education (BHE). In Massachusetts and nationally, the new Department of Early Education and Care (EEC) was greeted with excitement, high expectations and a keen sense of watchfulness. The newly consolidated Department was given oversight of early education and care providers and after-school programs for children ages 0-14 (and through age 16 for children with special needs). EEC was expected to improve upon the previous governance structure and forge new ground in early education through the development of a system of universal, high-quality prekindergarten (UPK) for every three-, four-, and five-year-old child in the Commonwealth. The creation of the Department was viewed as an opportunity for Massachusetts "to lead the way in providing coordinated, cost-effective, high quality early education and care." The creation of the consolidated Department was the culmination of several years of work by advocates and policymakers and was influenced by a growing focus statewide and nationally on the importance of early education. The primary impetus for the creation of the Department was the interest in developing a system that ensured access to UPK through a mix of private and public providers, which the existing governance structure was not capable of overseeing. Several additional factors contributed to a heightened focus on the needs of young children. Brain research over the past decade has directed increased attention to early education as it showed the long-term impact of early education and its potential return on investment. Specifically, research has demonstrated that low-income children who benefit from a high-quality early education are more likely to excel in school, stay off welfare and out of jail, and to later become good parents themselves. Economic research also showed a potential return on investment in high-quality early education for low-income children could lead to as much as a 16% return on every dollar invested. A final factor included national growth in the number of women engaged in the workforce; a number which is projected to continue to grow. This case study describes the evolution of EEC from its early conceptions to its impact over its first two and a half years. The goal is to provide a reference and resource for other state governments, advocacy groups and philanthropies seeking to develop a consolidated governance structure for early education and care. The case chronicles the purpose, history and evolution of EEC, articulates "lessons-learned" to date and identifies future opportunities and challenges for the agency as it strives to meet its statutory mandates

Human resource management of Indian call centre representatives.

This study examines how call centres adopt different types of human resource practices (involvement and control oriented) to manage frontline employees in Indian call centres. Data were collected from 250 call centre representatives to test the research hypotheses. The research model was analyzed using Mplus software. Findings showed that involvement and control oriented human resource practices resulted in more employee exhaustion and disengagement. Involvement oriented HRM had a positive impact on job satisfaction as well as, a positive relationship between employee exhaustion and disengagement. The findings suggest that, while involvement oriented HRM enhances job satisfaction, its implementation comes with a cost, that is, an increase in employee exhaustion and disengagement at work

A Combined XRD/XRF Instrument for Lunar Resource Assessment

Robotic surface missions to the Moon should be capable of measuring mineral as well as chemical abundances in regolith samples. Although much is already known about the lunar regolith, our data are far from comprehensive. Most of the regolith samples returned to Earth for analysis had lost the upper surface, or it was intermixed with deeper regolith. This upper surface is the part of the regolith most recently exposed to the solar wind; as such it will be important to resource assessment. In addition, it may be far easier to mine and process the uppermost few centimeters of regolith over a broad area than to engage in deep excavation of a smaller area. The most direct means of analyzing the regolith surface will be by studies in situ. In addition, the analysis of the impact-origin regolith surfaces, the Fe-rich glasses of mare pyroclastic deposits, are of resource interest, but are inadequately known; none of the extensive surface-exposed pyroclastic deposits of the Moon have been systematically sampled, although we know something about such deposits from the Apollo 17 site. Because of the potential importance of pyroclastic deposits, methods to quantify glass as well as mineral abundances will be important to resource evaluation. Combined x ray diffraction (XRD) and x ray fluorescence (XRF) analysis will address many resource characterization problems on the Moon. XRF methods are valuable for obtaining full major-element abundances with high precision. Such data, collected in parallel with quantitative mineralogy, permit unambiguous determination of both mineral and chemical abundances where concentrations are high enough to be of resource grade. Collection of both XRD and XRF data from a single sample provides simultaneous chemical and mineralogic information. These data can be used to correlate quantitative chemistry and mineralogy as a set of simultaneous linear equations, the solution of which can lead to full characterization of the sample. The use of Rietveld methods for XRD data analysis can provide a powerful tool for quantitative mineralogy and for obtaining crystallographic data on complex minerals

Modelling of dual-cycle strategy for container storage and vehicle scheduling problems at automated container terminals

This study proposes a new approach to determine the dispatching rules of AGVs and container storage locations, considering both unloading and loading processes simultaneously. We formulate this problem as a mixed integer programming model, aiming to minimise the ship’s berth time. Optimal solutions can be obtained in small sizes, however, large-sized problems are hard to solve optimally in a reasonable time. Therefore, a heuristic method, i.e. genetic algorithm is designed to solve the problem in large sizes. A series of numerical experiments are carried out to evaluate the effectiveness of the integration approach and algorithm

Mineralogy and chemistry of altered Icelandic basalts: Application to clay mineral detection and understanding aqueous environments on Mars

We used a suite of techniques, including those emulating compositional data sets obtained from Mars orbit and obtainable at the Mars surface, to examine aqueous alteration of basaltic rocks from Iceland as a mineralogic and geochemical analog for Noachian environments on Mars. A sample suite was collected for laboratory measurement of (1) whole-rock visible/near-infrared (VNIR) reflectance and thermal infrared (TIR) emission spectra; (2) VNIR and TIR reflectance spectra of particle-size separates derived from the bulk rock and from materials extracted from fractures/vesicles; (3) X-ray diffraction (XRD) patterns for determination of quantitative modal mineralogy; (4) major element chemistry using flux fusion of whole-rock powders; and (5) electron microprobe analyses of minerals in thin sections. Conclusions about aqueous alteration can be influenced by technique. For these basalts, whole-rock chemical data showed scant evidence for chemical fractionation, but TIR, VNIR, and XRD measurements identified distinctive assemblages of hydrous silicate minerals, differing by sample. XRD provided the most complete and accurate quantitative determination of sample mineralogy. However, VNIR spectroscopy was the technique most useful for determining composition of low-abundance smectite clays, and TIR spectroscopy was the most useful for recognizing hydrated silicates in thin surface coatings. High spatial resolution mineralogical and chemical data sets were useful for understanding the texture and distribution of alteration products and variations in fluid chemistry. No single approach provides a complete assessment of the environment of alteration, demonstrating the importance of employing multiple, synergistic mineralogical and geochemical techniques and instruments in exploration of rock strata from aqueous paleoenvironments on Mars

To Stack or Not to Stack: Spectral Energy Distribution Properties of Lya-Emitting Galaxies at z=2.1

We use the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) GOODS-S multi-wavelength catalog to identify counterparts for 20 Lya Emitting (LAE) galaxies at z=2.1. We build several types of stacked Spectral Energy Distributions (SEDs) of these objects. We combine photometry to form average and median flux-stacked SEDs, and postage stamp images to form average and median image-stacked SEDs. We also introduce scaled flux stacks that eliminate the influence of variation in overall brightness. We use the SED fitting code SpeedyMC to constrain the physical properties of individual objects and stacks. Our LAEs at z = 2.1 have stellar masses ranging from 2x10^7 Msun - 8x10^9 Msun (median = 3x10^8 Msun), ages ranging from 4 Myr to 500 Myr (median =100 Myr), and E(B-V) between 0.02 and 0.24 (median = 0.12). We do not observe strong correlations between Lya equivalent width (EW) and stellar mass, age, or E(B-V). The Lya radiative transfer (q) factors of our sample are predominantly close to one and do not correlate strongly with EW or E(B-V), implying that Lya radiative transfer prevents Lya photons from resonantly scattering in dusty regions. The SED parameters of the flux stacks match the average and median values of the individual objects, with the flux-scaled median SED performing best with reduced uncertainties. Median image-stacked SEDs provide a poor representation of the median individual object, and none of the stacking methods captures the large dispersion of LAE properties.Comment: 11 pages, 8 figures, 1 table, submitted to Ap

Sources of Sulfate Found in Mounds and Lakes at the Lewis Cliffs Ice Tongue, Transantarctic

Massive but highly localized Na-sulfate mounds (mirabilite, Na2SO4.10H2O) have been found at the terminal moraine of the Lewis Cliffs Ice Tongue (LCIT), Antarctica. (Sigma)34S and (Sigma)18O values of LCIT mirabilite range from +48.8 to +49.3% (CDT), and -16.6 to -17.1% (V-SMOW), respectively, while (Delta)17O average -0.37% (V-SMOW). LCIT mirabilite mounds are isotopically different from other mirabilite mounds found in coastal regions of Antarctica, which have isotope values close to seawater compositions. (Sigma)18O and (Delta)17O values suggest the incorporation of isotopically light glacial water. Data point to initial sulfate formation in an anoxic water body, either as a stratified anoxic deep lake on the surface, a sub-glacial water reservoir, or a sub-glacial lake. Several surface lakes of varying size are also present within this region of the LCIT, and in some cases are adjacent to the mirabilite mounds. O and D isotope compositions of surface lakes confirm they are derived from a mixture of glacial ice and snow that underwent moderate evaporation. (Sigma)18O and (Sigma)D (V-SMOW) values of snow, ice, and lake water range from -64.2 to -29.7%, and -456.0 to -231.7%, respectively. However, the isotope chemistry of these surface lakes is extremely different from the mounds. Dissolved SO4-2 (Sigma)34S and (Sigma)18O values range from +12.0 to +20.0% and -12.8 to -22.2% (the most negative (Sigma)18O of terrestrial sulfate ever reported), respectively, with sulfate (Delta)17O ranging from +0.93 to 2.24%. Ion chromatography data show that lake water is fresh to brackish in origin, with TDS less than 1500 ppm, and sulfate concentration less than 431 ppm. Isotope and chemical data suggest that these lakes are unlikely the source of the mirabilite mounds. We suggest that lake water sulfate is potentially composed of a mixture of atmospheric sulfate and minor components of sulfate of weathering origin, much like the sulfate in the polar plateau soils of the McMurdo Dry Valleys. A simple model explains mirabilite mound formation at the LCIT. Sulfur redox processes could occur sub-glacially as a result of liquid-water-based glacial conditions (Alpine style glacier), most likely formed by pressure melting of overlying ice (Aharon, GCA, 52, 2321-2331). We suggest that the aqueous base of the LCIT contains dissolved SO42- and is anoxic where sulfate reduction to H2S, HS-, or native sulfur takes place. Sulfide is removed by either precipitation as sulfide minerals or by escape of H2S (neither of which have been observed). Mirabilite precipitation is likely the result of evaporation or freezing of sulfate-rich brines as they reach the surface where they manifest themselves as mounds. Pressure from the overlying ice contributing to a pressure-melting scenario that creates the sub-glacial aqueous environment also contributes to the mechanism of upward transport of the sulfate-rich fluids. Further evidence to support this upward transport model comes from the nature of ice motion at the LCIT. Cassidy et al (Meteoritics, 27, 490-525, 1992) pointed out that it is the vertical ice motion in this area that creates the meteorite-stranding surface that could also account for upward transport of sulfate-rich fluids. Alternatively, mirabilite was deposited in a similar condition as present-day coastal Antarctica when the LCIT was wetter and warme