A Many-to-Many 'Rural Hospital Theorem'

We show that the full version of the so-called ‘rural hospital theorem’ generalizes to many-to-many matching problems where agents on both sides of the problem have substitutable and weakly separable preferences. We reinforce our result by showing that when agents’ preferences satisfy substitutability, the domain of weakly separable preferences is also maximal for the rural hospital theorem to hold

Flood risk analysis for the river Scheldt estuary

This report gives an overview of the history of flood risk management along the Scheldt estuary. Thepurpose of this overview is twofold. It documents the results obtained in the first activity of the Task25 Pilot, being focused on flood risk analysis, both in historical perspective and with regard to currentpolicies. Secondly, it provides an introduction to the Scheldt estuary for other partners in theFLOODsite project which will use the Scheldt Pilot for their own tasks and activities.The Scheldt estuary is a clear example where integrated water management is required. Integratedmeans in this case: meeting the objectives for 3 major basic functions and values of the estuary: safety,accessibility (navigation) and ecology. Recently finalised and ongoing projects, such as Proses and theSIGMA plan show a highly multidisciplinary approach in order to fulfil these objectives.From the perspective of flood risk management we see a significant difference in approach betweenBelgium and the Netherlands. The Belgian New Sigma Plan has used an approach that is strikinglysimilar to the FLOODsite methodology, i.e. going through the three phases Risk Analysis, RiskAssessment and Flood Management Strategy formulation. In contrast, the Dutch flood riskmanagement was developed over a long historical period, with the Delta Plan as the final apotheosis.In the time the Delta Plan was formulated, there was hardly any attention and technology available todetermine flood probability and flood damage

Matching with couples: a Multidisciplinary Survey

This survey deals with two-sided matching markets where one set of agents (workers/residents) has to be matched with another set of agents (firms/hospitals). We first give a short overview of a selection of classical results. Then, we review recent contributions to a complex and representative case of matching with complementarities, namely matching markets with couples. We discuss contributions from computer scientists, economists, and game theorists. © 2013 World Scientific Publishing Company

Direct comparison between potential landscape and local density of states in a disordered two-dimensional electron system

The local density of states (LDOS) of the adsorbate induced two-dimensional electron system (2DES) on n-InAs(110) is studied by low-temperature scanning tunneling spectroscopy. The LDOS exhibits irregular structures with fluctuation lengths decreasing with increasing energy. Fourier transformation reveals that the k-values of the unperturbed 2DES dominate the LDOS, but additional lower k-values contribute significantly. To clarify the origin of the additional k-space intensity, we measure the potential landscape of the same 2DES area with the help of the tip induced quantum dot. This allows to calculate the expected LDOS from the single particle Schroedinger equation and to directly compare it with the measured one. Reasonable correspondance between calculated and measured LDOS is found.Comment: 7 pages, 4 figures, submitted to PR

Potential for Integrating Entry Guidance into the Multi-Disciplinary Entry Vehicle Optimization Environment

The state-of-the-art in vehicle design decouples flight feasible trajectory generation from the optimization process of an entry spacecraft shape. The disadvantage to this decoupled process is seen when a particular aeroshell does not meet in-flight requirements when integrated into Guidance, Navigation, and Control simulations. It is postulated that the integration of a guidance algorithm into the design process will provide a real-time, rapid trajectory generation technique to enhance the robustness of vehicle design solutions. The potential benefit of this integration is a reduction in design cycles (possible cost savings) and increased accuracy in the aerothermal environment (possible mass savings). This work examines two aspects: 1) the performance of a reference tracking guidance algorithm for five different geometries with the same reference trajectory and 2) the potential of mass savings from improved aerothermal predictions. An Apollo Derived Guidance (ADG) algorithm is used in this study. The baseline geometry and five test case geometries were flown using the same baseline trajectory. The guided trajectory results are compared to separate trajectories determined in a vehicle optimization study conducted for NASA's Mars Entry, Descent, and Landing System Analysis. This study revealed several aspects regarding the potential gains and required developments for integrating a guidance algorithm into the vehicle optimization environment. First, the generation of flight feasible trajectories is only as good as the robustness of the guidance algorithm. The set of dispersed geometries modelled aerodynamic dispersions that ranged from +/-1% to +/-17% and a single extreme case was modelled where the aerodynamics were approximately 80% less than the baseline geometry. The ADG, as expected, was able to guide the vehicle into the aeroshell separation box at the target location for dispersions up to 17%, but failed for the 80% dispersion cases. Finally, the results revealed that including flight feasible trajectories for a set of dispersed geometries has the potential to save mass up to 430 kg