4,504 research outputs found
On the use of local max-ent shape functions for the simulation of forming processes
In this work we review the opportunities given by the use of local maximum-\ud
entropy approximants (LME) for the simulation of forming processes. This approximation can\ud
be considered as a meshless approximation scheme, and thus presents some appealing features\ud
for the numerical simulation of forming processes in a Galerkin framework.\ud
Especially the behavior of these shape functions at the boundary is interesting. At nodes\ud
on the boundary, the functions possess a weak Kronecker-delta property, hence simplifying the\ud
prescription of boundary conditions. Shape functions at the boundary do not overlap internal\ud
nodes, nor do internal shape functions overlap nodes at the boundary. Boundary integrals can be\ud
computed easily and efficiently compared to for instance moving least-squares approximations.\ud
Furthermore, LME shapes also present a controllable degree of smoothness.\ud
To test the performance of the LME shapes, an elastic and a elasto-plastic problem was\ud
analyzed. The results were compared with a meshless method based on a moving least-squares\ud
approximation
A framework for closed-loop supply chains of reusable articles
Reuse practices contribute to the environmental and economical sustainability of production and distribution systems. Surprisingly, reuse closed-loop supply chains (CLSC) have not been widely researched for the moment. In this paper, we explore the scientific literature on reuse and we propose a framework for reusable articles. This conceptual structure includes a typology integrating under the reusable articles term different categories of articles (transportation items, packaging materials, tools) and addresses the management issues that arise in reuse CLSC. We ground our results in a set of case studies developed in real industrial settings, which have also been contrasted with cases available in existing literature.reverse logistics;case studies;closed-loop supply chains;returns managment
González-Allende, Iker Epistolario de Pilar de Zubiaurre (1906- 1970). Woodbridge: Tamesis, 2014. 414 pp. (ISBN: 978-1-85566-276-6) [RESEÑA]
Detection of the Ammonium Ion in Space
We report on the detection of a narrow feature at 262816.73 MHz towards Orion
and the cold prestellar core B1-bS, that we attribute to the 1(0)-0(0) line of
the deuterated Ammonium ion, NH3D+. The observations were performed with the
IRAM 30m radio telescope. The carrier has to be a light molecular species as it
is the only feature detected over 3.6 GHz of bandwidth. The hyperfine structure
is not resolved indicating a very low value for the electric quadrupolar
coupling constant of Nitrogen which is expected for NH3D+ as the electric field
over the N nucleus is practically zero. Moreover, the feature is right at the
predicted frequency for the 1(0)-0(0) transition of the Ammonium ion, 262817(6)
MHz (3sigma), using rotational constants derived from new infrared data
obtained in our laboratory in Madrid. The estimated column density is
1.1(0.2)e12 cm-2. Assuming a deuterium enhancement similar to that of NH2D, we
derive N(NH4+) sim 2.6e13 cm-2, i.e., an abundance for Ammonium of a few
1e(-11).Comment: Accepted for publication in the Astrophysical Journal Letters 04 June
201
Modeling the Cost of International Trade in Global Supply Chains
In a global economy, international trade plays an important role of the economic development. This is especially relevant in emerging markets, where trade could contribute significantly to the economic growth of the country. Many studies have pointed out the relationship between logistics performance and the volume of bilateral trade. Limão and Venables (2001) analyze transport costs, Hummels (2001) analyzes transport time and Hausman et al. (2013) evaluate the impact of specific improvements in logistics performance in terms of time, cost and reliability (variability in time) on increased trade.
International Trade ads complexity as goods move across borders where are subject to import and export activities that increase lead times and variability on financial and physical flows (e.g. more documents per trade transaction, more signatures per trade transaction, export clearance, and customs inspection). Also, these global supply chains often involve more actors and agencies that support the trade process such as inspection agencies and custom brokers. Surveys aimed at calculating these costs suggest that they may range from 2% to 15% of the value of traded goods.
This paper provides a general framework to model the impact of international trade of a global supply chain. A cost function is proposed for the buyer, the seller and the upstream suppliers that explicitly refers to the additional elements of international trade. The model is applied to compare the impact of different Incoterms rules (see section 3.2.1) in an International Trade taking into account the total cost of the supply chain Blanco, E.E. and Ponce-Cueto, E. – MIT Center for Transportation & Logistics – March 2015 2 for the main actors, including the buyer (importer) and the seller (exporter).
The paper is organized as follows. Section 2 includes a succinct literature review of relevant papers in global trade management, and more specifically a review of those papers that focus on the total cost in global supply chains. Section 3 defines the global supply chain under study and presents the key events in a global trade. A total global trade function is formulated in Section 4, one function cost for buyers and another for upstream sellers. In section 5 the supply chain costs under various trade scenarios are presented and a numerical example is developed in order to illustrate the applicability of the model. Discussion and conclusion are included in section 6
Designing Sorting Facilities in Reverse Logistics Systems
The main aim of this paper is to propose a multi-waste mix integer lineal programming model for locating sorting facilities in a three-level (local, regional, and central) reverse logistic network. The objective of the model is to decide the location of the storage and sorting facilities across the network. The model was applied in end of life battery recycling network in Spain. As capacity is constrained, the optimal solution moves towards a combination of regional and local facilities for storage and a central facility for sorting
Propuesta de un marco conceptual para el análisis comparativo de las redes de distribución de dos supermercados online = Proposal of a conceptual framework for the comparative analysis of the distribution networks of two online supermarkets
In this article the network configuration for fulfillment and distribution of online orders of two British retailers is analyzed and compared. For this purpose, it is proposed a conceptual framework that consists of the key following aspects: network configuration, transportation management and location of demand. As a result is not obvious to determine the ideal centralization degree in each case. Finally, it is suggested the future development of an analytic tool that helps to choose the most appropriate model
Increasing Vegetable Intakes: An Updated Systematic Review of Published Interventions
Vegetable consumption is important for a variety of health reasons, yet intakes are typically lower than recommended. Interventions to improve fruit and vegetable consumption are available, but these interventions are typically more successful for fruit consumption, while vegetable intakes remain low. This chapter details the interventions currently available that focus specifically on improving vegetable intakes. A systematic review of the published literature was conducted in 2015, and this has been updated for this chapter. Databases - PubMed, PsychInfo and Medline were searched over all years of records until January 2017 using pre-specified terms. Our searches identified 119 studies, detailing 206 interventions. Interventions aimed to use or change hedonic factors, such as taste, liking and familiarity (n=103), use or change environmental factors (n=54), use or change cognitive factors (n=28), or a combination of strategies (n=21). Increased vegetable acceptance, selection and/or consumption were reported to some degree in 186 (90%) interventions. Greatest success appears to be achieved in interventions that improve education, change the environment or use multiple approaches, but long-term success and cost-effectiveness are rarely considered. A focus on long-term benefits and sustained behaviour change is required
Evaluación del impacto ambiental al extender la vida útil del teléfono móvil
El mercado de telefonía móvil ha experimentado un continuo crecimiento en la última década. Cada vez más, los teléfonos móviles son reemplazados por nuevos modelos con diseños más modernos y ampliación de funciones. Este estilo de vida está provocando incremento en la cantidad de residuos de aparatos electrónicos que no siempre reciben tratamiento. Por lo que, en este artículo, se presentan los resultados de la aplicación de la metodología de análisis de ciclo de vida (ACV) para calcular cuantitativamente el beneficio ambiental debido a la extensión de vida útil del teléfono móvil durante diferentes períodos. Tomando como unidad funcional el ciclo de vida promedio de 30 meses, se modelaron tres escenarios considerando cuatro etapas: adquisición de materias primas/producción, distribución, uso y fin de vida útil. Se utilizó el paquete SimaPro (2013), la base de datos Ecoinvent para configurar el inventario y las emisiones consideradas se asignaron en seis categorías de impacto según el método CML2000 del Centro para Estudios Medioambientales (CML). Se observó que al prolongar la vida útil del teléfono móvil y dar tratamiento cuando se convierte en residuo representa una ganancia ambiental no sólo porque se evita su disposición y consumo de uno nuevo, sino porque se ahorran recursos limitados y la energía necesaria para su extracción a través de la recuperación de materiales. Sin embargo, antes de reciclar es importante considerar su reutilización (extensión de su vida útil) ya que una cantidad sustancial de los móviles son dispuestos por razones de moda o estética mientras aún son funcionales.The mobile phone market has experienced continuous growth over the last decade. Increasingly, mobile phones are replaced by new models with more modern designs or expansion of functions. This lifestyle is causing increasing amount of electronic waste that do not always receive treatment. This article presents the results of the application
of the methodology for life-cycle assessment (LCA) to calculate quantitatively the
environmental benefit due to the extension of lifespan mobile phones during different
periods of time. Taking as a functional unit the life cycle of an average mobile phone
during 30 months and considering the stages of raw materials/production, distribution,
use and end of life, three scenarios were modeled. The SimaPro (2013) software was
used, the Ecoinvent database has been applied to configure the life cycle inventory,
and the emissions were allocated into six categories according to the impact CML2000
method. It was observed that to extend the mobile phone useful life and to provide
treatment when it becomes a waste, represents an environmental gain not only because
the provision and consumption of a new one is avoided, but because limited resources
and energy required for extraction are saved through recovery of materials. However,
before recycling it is important to consider reuse (extending lifespan) because a substantial
amount of the mobile phones are discarded for fashion or cosmetic reasons
while they are still functional
Breeding latitude predicts timing but not rate of spring migration in a widespread migratory bird in South America
Identifying the processes that determine avian migratory strategies in different environmental contexts is imperative to understanding the constraints to survival and reproduction faced by migratory birds across the planet. We compared the spring migration strategies of Fork‐tailed Flycatchers (Tyrannus s. savana) that breed at south‐temperate latitudes (i.e., austral migrants) vs. tropical latitudes (i.e., intratropical migrants) in South America. We hypothesized that austral migrant flycatchers are more time‐selected than intratropical migrants during spring migration. As such, we predicted that austral migrants, which migrate further than intratropical migrants, will migrate at a faster rate and that the rate of migration for austral migrants will be positively correlated with the onset of spring migration. We attached light‐level geolocators to Fork‐tailed Flycatchers at two tropical breeding sites in Brazil and at two south‐temperate breeding sites in Argentina and tracked their movements until the following breeding season. Of 286 geolocators that were deployed, 37 were recovered ~1 year later, of which 28 provided useable data. Rate of spring migration did not differ significantly between the two groups, and only at one site was there a significantly positive relationship between date of initiation of spring migration and arrival date. This represents the first comparison of individual migratory strategies among conspecific passerines breeding at tropical vs. temperate latitudes and suggests that austral migrant Fork‐tailed Flycatchers in South America are not more time‐selected on spring migration than intratropical migrant conspecifics. Low sample sizes could have diminished our power to detect differences (e.g., between sexes), such that further research into the mechanisms underpinning migratory strategies in this poorly understood system is necessary.Fil: Jahn, Alex. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Cereghetti, Joaquín. Universidad Nacional de La Pampa; ArgentinaFil: Cueto, Víctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; ArgentinaFil: Hallworth, Michael T.. Smithsonian Conservation Biology Institute; Estados UnidosFil: Levey, Douglas J.. National Science Foundation; Estados UnidosFil: Marini, Miguel Â.. Universidade do Brasília; BrasilFil: Masson, Diego. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Pizo, Marco A.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Sarasola, José Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Tuero, Diego Tomas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin
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