Search results for "Operations Research"
showing 10 items of 1297 documents
Science in space vs space science: The European utilisation of spacelab∗
1999
Abstract Spacelab is the conventional name given to a manned laboratory to be carried onboard NASA's Space Shuttle, which was built in Europe under the aegis of the European Space Agency (ESA). This paper deals with the initiatives undertaken in Europe to establish a utilisation programme for Spacelab, in particular for its first flight, planned as a joint ESA/NASA demonstration mission. Two main factors will be discussed, which prevented ESA from establishing a sizeable Spacelab utilisation effort. Firstly, owing to the cost escalation of the Spacelab development programme and to NASA's charging policy for access to the Shuttle system, which did not foressee any preferential treatment to E…
Peculiar and Unusual Drowning in Waste Oil from Motor Vehicles: Case Report
2016
Drowning is one of the most frequent causes of accidental or suicidal death, and more rarely it is associated with a homicide. Cases of drowning in water or in the sea are common. The authors report an unusual and peculiar case of drowning, that of a woman who accidentally fell inside a collection tank of waste oil of motor vehicles.
Bi-objective multi-layer location–allocation model for the immediate aftermath of sudden-onset disasters
2019
International audience; Locating distribution centers is critical for humanitarians in the immediate aftermath of a sudden-onset disaster. A major challenge lies in balancing the complexity and uncertainty of the problem with time and resource constraints. To address this problem, we propose a location–allocation model that divides the topography of affected areas into multiple layers; considers constrained number and capacity of facilities and fleets; and allows decision-makers to explore trade-offs between response time and logistics costs. To illustrate our theoretical work, we apply the model to a real dataset from the 2015 Nepal earthquake response. For this case, our method results in…
Managing in-country transportation risks in humanitarian supply chains by logistics service providers: Insights from the 2015 Nepal earthquake
2017
International audience; Humanitarian supply chains (HSCs) play a central role in effective and efficient disaster relief operations. Transportation has a critical share in HSCs and managing its risks helps to avoid further disruptions in relief operations. However, there is no common approach to or culture of risk management that its applicability has been studied through recent cases. This paper incorporates an empirical research design and makes a threefold contribution: first, it identifies in-country transportation risks during Nepal response. Second, we evaluate afore identified risks through an expert driven risk assessment grid. Third, we use our field data to study how some humanita…
Do Current Domestic Gigabit Wireless Technologies Fulfill User Requirements for Ultra High Definition Videos?
2017
We present the results from a measurement-based performance evaluation of wireless networks based on IEEE 802.11n and IEEE 802.11ac standards in an indoor environment, with the aim to analyze their performance under high definition streaming video applications. We focus our study on analyzing the highest performance of these standards using off-the-shelf equipment, both with synthetic TCP and UDP traffic to measure the saturation throughput as well as high definition video streams. The measurements have been conducted in the student labs of our university and show good performance for streaming purposes in high definition and also ultra-high definition from a subjective video quality point …
Capacity and Energy-Consumption Optimization for the Cluster-Tree Topology in IEEE 802.15.4
2011
International audience; 802.15.4 proposes to use a cluster-tree hierar- chy to organize the transmissions in Wireless Sensor Networks. In this letter, we propose a framework to analyze formally the capacity and the energy consumption of this structure. We derive a Mixed Integer Linear Programming (MILP) formulation to obtain a topology compliant with the standard. This formulation provides the optimal solution for the network capacity: this con- stitutes an upper bound for any distributed algorithms permitting to construct a cluster-tree. This framework can also be used to evaluate the capacity and to compare quantitatively different cluster-tree algorithms.
Assessment of the integrated urban water quality model complexity through identifiability analysis
2010
Urban sources of water pollution have often been cited as the primary cause of poor water quality in receiving water bodies (RWB), and recently many studies have been conducted to investigate both continuous sources, such as wastewater-treatment plant (WWTP) effluents, and intermittent sources, such as combined sewer overflows (CSOs). An urban drainage system must be considered jointly, i.e., by means of an integrated approach. However, although the benefits of an integrated approach have been widely demonstrated, several aspects have prevented its wide application, such as the scarcity of field data for not only the input and output variables but also parameters that govern intermediate st…
Enabling robotic adaptive behaviour capabilities for new industry 4.0 automated quality inspection paradigms
2020
The seamless integration of industrial robotic arms with server computers, sensors and actuators can revolutionise the way in which automated non-destructive testing (NDT) is performed and conceived. Achieving effective integration and realising the full potential of robotic systems presents significant challenges, since robots, sensors and end-effector tools are often not necessarily designed to be put together and form a holistic system. This paper presents recent breakthroughs, opening up new scenarios for the inspection of product quality in advanced manufacturing. Many years of research have brought to software platforms the ability to integrate external data acquisition instrumentatio…
Adapting to supply chain 4.0: an explorative study of multinational companies
2019
The aim of this paper is to examine how multinational companies from five industries can adapt to what we call Supply Chain 4.0; the supply chain created as a result of the new digital era brought ...
An AHP-based evaluation procedure for Innovative Educational Projects: A face-to-face vs. computer-mediated case study
2008
In this paper a procedure to evaluate proposals for Educational Innovation Projects is proposed. This methodology should help the Institute of Educational Sciences of the Politechnical University of Valencia to choose the best Educational Project, the final aim being to provide the Administration with a stringent evaluation methodology, since the current evaluation methodology was found to be neither sufficiently objective nor systematic. Since in the definition and evaluation of these Educational Projects diverse stakeholders are involved, the process has been approached as a MCDA carried out by a group of experts. Although a whole methodology is proposed, the paper has been focused on the…