Climbing depth-bounded adjacent discrepancy search for solving hybrid flow shop scheduling problems with multiprocessor tasks

This paper considers multiprocessor task scheduling in a multistage hybrid flow-shop environment. The problem even in its simplest form is NP-hard in the strong sense. The great deal of interest for this problem, besides its theoretical complexity, is animated by needs of various manufacturing and computing systems. We propose a new approach based on limited discrepancy search to solve the problem. Our method is tested with reference to a proposed lower bound as well as the best-known solutions in literature. Computational results show that the developed approach is efficient in particular for large-size problems

Flexibility of Drinking water Systems: an Opportunity to reduce CO₂ Emissions

Drinking water systems (DWSs) are huge electricity consumers, mainly due to pumping operations. In these systems, electricity costs represent approximately one-third of the total operating costs. Because of the environmental impact of electricity generation worldwide (coal, gas, and diesel), water systems also implicitly contribute to global warming. However, these systems have flexibility thanks to water storage structures (tank and reservoirs) and variable speed pumps. The flexibility of DWSs is generally used to optimize energy costs. Furthermore, this flexibility can also be used to provide an environmental and operational service for the power system, by reducing peak power load and the volume of energy transactions on wholesale markets. Indeed, peak power reduction can be sold by water utilities on electricity markets, preventing the production of an equivalent amount of additional energy. In France, peak hours require a massive use of fossil energy sources, which makes electricity production at these periods extremely expensive, both economically and ecologically. Using a mathematical optimization model, we optimize the management of these peak periods by shifting load at off-peak hours and selling the reduced energy on the French wholesale energy market. In this paper, we explore the ecological benefits that water systems could provide through this optimization process. We evaluate the CO₂ emissions that can be effectively reduced on three real DWSs in France. For these three systems, avoided CO₂ emissions were estimated at 2,190 kg/day for the largest system and 194 kg/day for the smallest one, which is equivalent to the emission of 145–1620 cars during 10 km of driving. We also evaluate, based on some hypotheses, the potential for CO₂ reduction from water systems at the French scale.This work is carried out in the innovation research of the Suez company (France). The partners are Suez Smart Solutions (France) and Sorbonne Universités, Université de Technologie de Compiègne (France)

Results from the Mars Phoenix Lander Robotic Arm experiment

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95618/1/jgre2693.pd

Yearly and seasonal variations of low albedo surfaces on Mars in the OMEGA/MEx dataset: Constraints on aerosols properties and dust deposits

The time variations of spectral properties of dark martian surface features are investigated using the OMEGA near-IR dataset. The analyzed period covers two Mars years, spanning from early 2004 to early 2008 (includes the 2007 global dust event). Radiative transfer modeling indicates that the apparent albedo variations of low to mid-latitude dark regions are consistent with those produced by the varying optical depth of atmospheric dust as measured simultaneously from the ground by the Mars Exploration Rovers. We observe only a few significant albedo changes that can be attributed to surface phenomena. They are small-scaled and located at the boundaries between bright and dark regions. We then investigate the variations of the mean particle size of aerosols using the evolution of the observed dark region spectra between 1 and 2.5 {\mu}m. Overall, we find that the observed changes in the spectral slope are consistent with a mean particle size of aerosols varying with time between 1 and 2 {\mu}m. Observations with different solar zenith angles make it possible to characterize the aerosol layer at different altitudes, revealing a decrease of the particle size of aerosols as altitude increases

Iron mineralogy and aqueous alteration from Husband Hill through Home Plate at Gusev Crater, Mars: Results from the Mössbauer instrument on the Spirit Mars Exploration Rover

Spirit’s Mössbauer (MB) instrument determined the Fe mineralogy and oxidation state of 71 rocks and 43 soils during its exploration of the Gusev plains and the Columbia Hills (West Spur, Husband Hill, Haskin Ridge, northern Inner Basin, and Home Plate) on Mars. The plains are predominantly float rocks and soil derived from olivine basalts. Outcrops at West Spur and on Husband Hill have experienced pervasive aqueous alteration as indicated by the presence of goethite. Olivine-rich outcrops in a possible mafic/ultramafic horizon are present on Haskin Ridge. Relatively unaltered basalt and olivine basalt float rocks occur at isolated locations throughout the Columbia Hills. Basalt and olivine basalt outcrops are found at and near Home Plate, a putative hydrovolcanic structure. At least three pyroxene compositions are indicated by MB data. MB spectra of outcrops Barnhill and Torquas resemble palagonitic material and thus possible supergene aqueous alteration. Deposits of Fe3+-sulfate soil, located at Paso Robles, Arad, and Tyrone, are likely products of acid sulfate fumarolic and/or hydrothermal activity, possibly in connection with Home Plate volcanism. Hematite-rich outcrops between Home Plate and Tyrone (e.g., Montalva) may also be products of this aqueous activity. Low water-to-rock ratios (isochemical alteration) are implied during palagonite, goethite, and hematite formation because bulk chemical compositions are basaltic (SO3-free basis). High water-to-rock ratios (leaching) under acid sulfate conditions are implied for the high-SiO2 rock and soil in Eastern Valley and the float rock FuzzySmith, which has possible pyrite/marcasite as a hydrothermal alteration product

Improved calibration procedures for the EM27/SUN spectrometers of the COllaborative Carbon Column Observing Network (COCCON)

In this study, an extension on the previously reported status of the COllaborative Carbon Column Observing Network\u27s (COCCON) calibration procedures incorporating refined methods is presented. COCCON is a global network of portable Bruker EM27/SUN FTIR spectrometers for deriving column-averaged atmospheric abundances of greenhouse gases. The original laboratory open-path lamp measurements for deriving the instrumental line shape (ILS) of the spectrometer from water vapour lines have been refined and extended to the secondary detector channel incorporated in the EM27/SUN spectrometer for detection of carbon monoxide (CO). The refinements encompass improved spectroscopic line lists for the relevant water lines and a revision of the laboratory pressure measurements used for the analysis of the spectra. The new results are found to be in good agreement with those reported by Frey et al. (2019) and discussed in detail. In addition, a new calibration cell for ILS measurements was designed, constructed and put into service. Spectrometers calibrated since January 2020 were tested using both methods for ILS characterization, open-path (OP) and cell measurements. We demonstrate that both methods can detect the small variations in ILS characteristics between different spectrometers, but the results of the cell method indicate a systematic bias of the OP method. Finally, a revision and extension of the COCCON network instrument-to-instrument calibration factors for XCO2, XCO and XCH4 is presented, incorporating 47 new spectrometers (of 83 in total by now). This calibration is based on the reference EM27/SUN spectrometer operated by the Karlsruhe Institute of Technology (KIT) and spectra collected by the collocated TCCON station Karlsruhe. Variations in the instrumental characteristics of the reference EM27/SUN from 2014 to 2017 were detected, probably arising from realignment and the dual-channel upgrade performed in early 2018. These variations are considered in the evaluation of the instrument-specific calibration factors in order to keep all tabulated calibration results consistent

Influence of Snowmelt Timing on the Diet Quality of Pyrenean Rock Ptarmigan (Lagopus muta pyrenaica): Implications for Reproductive Success

The Pyrenean rock ptarmigan (Lagopus muta pyrenaica) is the southernmost subspecies of the species in Europe and is considered threatened as a consequence of changes in landscape, human pressure, climate change, and low genetic diversity. Previous studies have shown a relationship between the date of snowmelt and reproductive success in the Pyrenean ptarmigan. It is well established that birds laying early in the breeding season have higher reproductive success, but the specific mechanism for this relationship is debated. We present an explicative model of the relationship between snowmelt date and breeding success mediated by food quality for grouse in alpine environments. From microhistological analyses of 121 faecal samples collected during three years in the Canigou Massif (Eastern Pyrenees), and the assessment of the chemical composition of the main dietary components, we estimated the potential quality of individual diets. Potential dietary quality was correlated with free-urate faecal N, a proxy of the digestible protein content ingested by ptarmigan, and both were correlated with phenological stage of consumed plants, which in turn depends on snowmelt date. Our findings suggest that the average snowmelt date is subject to a strong interannual variability influencing laying date. In years of early snowmelt, hens benefit from a longer period of high quality food resources potentially leading to a higher breeding success. On the contrary, in years of late snowmelt, hens begin their breeding period in poorer nutrient condition because the peaks of protein content of their main food items are delayed with respect to laying date, hence reducing breeding performance. We discuss the possible mismatch between breeding and snowmelt timing

Les pelouses à Fétuque paniculée (Festuca paniculata(L.)SCHINZ et THELL.) : un enjeu pour les Alpes du Sud

Festuca paniculata meadows cover thousands of hectares between 1800 and 2200 m high in the main alpine massifs. Present in the southern Alps on slopes exposed to the south that used to be mowed, their current development is related to agricultural devalorization. This species is not highly feedant when the livestock comes in the mountain pastures, which leads to important loss of forage units. The objectives of these projects were to learn more about meadow dynamics and Festuca paniculata dynamics, particularly when affected by different practices in order to suggest a better valorization of these grazing highlands. / Les pelouses à Fétuque paniculée couvrent des milliers d'hectares entre 1800 et 2200 mètres d'altitude dans les principaux massifs alpins. Présentes dans les Alpes méridionales sur des pentes d'exposition Sud autrefois fauchées, leur développement actuel est lié à une forte déprise agricole. La Fétuque paniculée est déjà peu appétente à la date de montée des troupeaux sur les alpages ; cela entraîne une sous-exploitation et une perte importante d'unités fourragères. Ces travaux ont porté essentiellement sur la connaissance approfondie de la dynamique des pelouses et de la Fétuque paniculée en particulier, sous l'effet de différentes pratiques afin de proposer aux éleveurs une meilleure valorisation de ces pâturages d'altitude

An O(n²) algorithm for time-bound adjustments for the cumulative scheduling problem

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