23 research outputs found

    Decomposition techniques with mixed integer programming and heuristics for home healthcare planning

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    We tackle home healthcare planning scenarios in the UK using decomposition methods that incorporate mixed integer programming solvers and heuristics. Home healthcare planning is a difficult problem that integrates aspects from scheduling and routing. Solving real-world size instances of these problems still presents a significant challenge to modern exact optimization solvers. Nevertheless, we propose decomposition techniques to harness the power of such solvers while still offering a practical approach to produce high-quality solutions to real-world problem instances. We first decompose the problem into several smaller sub-problems. Next, mixed integer programming and/or heuristics are used to tackle the sub-problems. Finally, the sub-problem solutions are combined into a single valid solution for the whole problem. The different decomposition methods differ in the way in which subproblems are generated and the way in which conflicting assignments are tackled (i.e. avoided or repaired). We present the results obtained by the proposed decomposition methods and compare them to solutions obtained with other methods. In addition, we conduct a study that reveals how the different steps in the proposed method contribute to those results. The main contribution of this paper is a better understanding of effective ways to combine mixed integer programming within effective decomposition methods to solve real-world instances of home healthcare planning problems in practical computation time

    Systematic bioinformatics and experimental validation of yeast complexes reduces the rate of attrition during structural investigations.

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    For high-throughput structural studies of protein complexes of composition inferred from proteomics data, it is crucial that candidate complexes are selected accurately. Herein, we exemplify a procedure that combines a bioinformatics tool for complex selection with in vivo validation, to deliver structural results in a medium-throughout manner. We have selected a set of 20 yeast complexes, which were predicted to be feasible by either an automated bioinformatics algorithm, by manual inspection of primary data, or by literature searches. These complexes were validated with two straightforward and efficient biochemical assays, and heterologous expression technologies of complex components were then used to produce the complexes to assess their feasibility experimentally. Approximately one-half of the selected complexes were useful for structural studies, and we detail one particular success story. Our results underscore the importance of accurate target selection and validation in avoiding transient, unstable, or simply nonexistent complexes from the outset

    Efeito do óleo de arroz na ração sobre a produção e composição química do leite de ovelhas corriedale

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    Foi avaliada a influência da adição de óleo de arroz, sobre a produção e a composição química do leite de ovelhas Corriedale multíparas alimen- tadas com ração comercial sem e com adição de óleo de arroz contendo respectivamente 4,36% e 6,56% de extrato etéreo. A ordenha mecânica foi realizada uma vez por semana, pela manhã. Além da produção de leite foram avaliados: gordura, proteína, lactose e sólidos totais. A produção de leite, bem como dos componentes químicos lactose, proteína, gordura e sólidos totais, não foram influenciadas pelo aumento do extrato etéreo da ração com a adição de óleo de arroz.It was evaluated the influence of rice oil addition on the milk production and chemical composition, of Corriedale multiparous sheep fed commercial diet with and without rice oil addition, containing 4.36% and 6.56% of ether extract, respectively. The mechanical milking was done once a week in the morning. Besides milk production the following components were evaluated: fat, protein, lactose and total solids. The milk production, as well the chemical components as lactose, protein, fat and total solids, were not influenced by diet increase of ether extract through rice oil addition

    Variability of dissolved oxygen in the bottom layer of the southern Senegalese shelf

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    The observation station "Melax" was deployed in 2015 on the wide and shallow south Senegalese shelf to study the ocean dynamics, air‐sea interactions and dissolved oxygen (DO) cycle. Data from February 2015 to August 2016 were used to study the main physical processes affecting the variability of DO in the bottom layer (∼30 m depth) on time scales ranging from tidal to seasonal. Between November and May, wind‐driven upwelling provides phytoplankton enrichment of the surface layers and brings cold, salty and depleted DO on the shelf. Water properties at Melax vary depending on the source waters located at the shelf edge. The DO concentration changes between the shelf edge and Melax are broadly consistent with the inferred respiration rates estimated in previous studies. In contrast, the monsoon season (July‐October) is characterized by weak westerly winds and northward currents. Bottom waters are warmer, fresher and more oxygenated. The slower circulation in this period allows a stronger decoupling between the water properties of the waters observed at Melax and those of the source waters. Stratification strengthening near the bottom layer inhibits vertical mixing and induces strong high‐frequency variability in properties caused by internal tide‐generated waves. Intense upwelling events can deepen the mixed layer and intermittently transform the bottom layer waters (locally or remotely). Relaxation events associated with current reversals significantly modify their properties. Coastal trapped waves constitute a distant forcing that can act year‐round, impacting both shelf waters and source regions. Plain Language Summary Global warming and extra nutrient loads from agriculture and waste‐waters reduce the oxygen content in the ocean. Incidentally, oxygen‐depleted waters are encountered with increased frequency oceanwide and this trend is more pronounced in coastal environments. Temperature and oxygen impact the metabolism of marine organisms and their variations can be major sources of (natural or anthropogenic) stresses. We used here measurements made at a fixed monitoring buoy (Melax) located over the southern Senegalese mid‐shelf (35 m depth) to study the variability of bottom oxygen (the surface being well oxygenated). Its seasonality is constrained by the circulation and the wind regime. They induce the transport of deep, colder, saltier and less oxygenated waters from the shelf break onto the shelf during the upwelling season compared to the monsoon season. The properties of water masses on the shelf thus depend on those of the water masses drawn from the open ocean through the shelf break which can be modified by many processes acting over a wide range of scales from days to seasons and longer. On the shelf, respiration of organic matter reduces oxygen whereas diurnal wind variability and internal tides oxygenate bottom layers when the water column is stratified

    West African context call for rapid implementation of insect meal fir fishmeal substitution [résumé]

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    Insects to Feed the World, Québec, CAN, 12-/06/2022 - 16/06/2022In West Africa, numerous economies are dependent on fisheries resources; this sector can reach almost 10% of the national gross domestic product and represents a central sector for food security as the most important animal protein for human consumption and aquafeeds. Due to overexploitation, West African fish stocks are under serious threats and massive implantation of fishmeal factories has raised serious concerns about the sustainability of small pelagic fish resources. Although this situation is well understood by many political decision-makers, this trend is not about to be reversed. Concurrently, the government of Senegal seeks to increase the production of the Senegalese fish farming industry. To address these challenges, we are investigating the possibility of harnessing the ability of black soldier fly (BSF) larvae to replace fishmeal. Given the lack of formal institutional initiatives in Northwest Africa, we initiated in 2020 a collaborative program to establish a technical platform 'Art Sunu Gueej' to develop an inter-institutional insect production unit in a controlled environment. We have identified endemic BSF populations in local piggeries as well as agricultural surpluses including millet bran, rice bran, and mango waste that could serve as BSF feedstocks, to ultimately partially replace fishmeal for aquafeed formulations. We have established an Action Plan for awareness of political decision-makers, including a research plan to: (1) optimise and adapt BSF strains for West Africa production and, (2) test insect meals for aquaculture and poultry sectors. Based on these results, we will use our new platform for fundraising and foster collaborations to promote insect meals as fishmeal replacements for aquafeeds in West Africa

    West African context call for rapid implementation of insect meal fir fishmeal substitution [résumé]

    No full text
    Insects to Feed the World, Québec, CAN, 12-/06/2022 - 16/06/2022In West Africa, numerous economies are dependent on fisheries resources; this sector can reach almost 10% of the national gross domestic product and represents a central sector for food security as the most important animal protein for human consumption and aquafeeds. Due to overexploitation, West African fish stocks are under serious threats and massive implantation of fishmeal factories has raised serious concerns about the sustainability of small pelagic fish resources. Although this situation is well understood by many political decision-makers, this trend is not about to be reversed. Concurrently, the government of Senegal seeks to increase the production of the Senegalese fish farming industry. To address these challenges, we are investigating the possibility of harnessing the ability of black soldier fly (BSF) larvae to replace fishmeal. Given the lack of formal institutional initiatives in Northwest Africa, we initiated in 2020 a collaborative program to establish a technical platform 'Art Sunu Gueej' to develop an inter-institutional insect production unit in a controlled environment. We have identified endemic BSF populations in local piggeries as well as agricultural surpluses including millet bran, rice bran, and mango waste that could serve as BSF feedstocks, to ultimately partially replace fishmeal for aquafeed formulations. We have established an Action Plan for awareness of political decision-makers, including a research plan to: (1) optimise and adapt BSF strains for West Africa production and, (2) test insect meals for aquaculture and poultry sectors. Based on these results, we will use our new platform for fundraising and foster collaborations to promote insect meals as fishmeal replacements for aquafeeds in West Africa

    Platooning of Automated Ground Vehicles to Connect Port and Hinterland: A Multi-objective Optimization Approach

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    Automated ground vehicles (AGVs) are essential parts of container operations at many ports. Forming platoons—as conceptually established in trucking—may allow these vehicles to directly cater demand points such as dry ports in the hinterland. In this work, we aim to assess such AGV platoons in terms of operational efficiency and costs, considering the case of the Port of Rotterdam. We propose a multi-objective mixed-integer programming model that minimizes dwell and idle times, on the one hand, and the total cost of the system involving transportation, labor, and platoon formation costs, on the other hand. To achieve Pareto optimal solutions that capture the trade-offs between minimizing cost and time, we apply an augmented epsilon constraint method. The results indicate that all the containers are delivered by AGVs. This not only shortens the dwell time of the containers by decreasing loading/unloading processes and eliminating stacking but also leads to considerable cost savings.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
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