44,926 research outputs found
Designing Exploration Contracts
No full textWe study a natural application of contract design in the context of sequential exploration problems. In our principal-agent setting, a search task is delegated to an agent. The agent performs a sequential exploration of n boxes, suffers the exploration cost for each inspected box, and selects the content (called the prize) of one inspected box as outcome. Agent and principal obtain an individual value based on the selected prize. To influence the search, the principal a-priori designs a contract with a non-negative payment to the agent for each potential prize. The goal of the principal is to maximize her expected reward, i.e., value minus payment. Interestingly, this natural contract scenario shares close relations with the Pandora’s Box problem.
We show how to compute optimal contracts for the principal in several scenarios. A popular and important subclass is that of linear contracts, and we show how to compute optimal linear contracts in polynomial time. For general contracts, we obtain optimal contracts under the standard assumption that the agent suffers cost but obtains value only from the transfers by the principal. More generally, for general contracts with non-zero agent values for outcomes we show how to compute an optimal contract in two cases: (1) when each box has only one prize with non-zero value for principal and agent, (2) for i.i.d. boxes with a single prize with positive value for the principal
Algorithms for Claims Trading
No full textThe recent banking crisis has again emphasized the importance of understanding and mitigating systemic risk in financial networks. In this paper, we study a market-driven approach to rescue a bank in distress based on the idea of claims trading, a notion defined in Chapter 11 of the U.S. Bankruptcy Code. We formalize the idea in the context of the seminal model of financial networks by Eisenberg and Noe [Eisenberg and Noe, 2001]. For two given banks v and w, we consider the operation that w takes over some claims of v and in return gives liquidity to v (or creditors of v) to ultimately rescue v (or mitigate contagion effects). We study the structural properties and computational complexity of decision and optimization problems for several variants of claims trading.
When trading incoming edges of v (i.e., claims for which v is the creditor), we show that there is no trade in which both banks v and w strictly improve their assets. We therefore consider creditor-positive trades, in which v profits strictly and w remains indifferent. For a given set C of incoming edges of v, we provide an efficient algorithm to compute payments by w that result in a creditor-positive trade and maximal assets of v. When the set C must also be chosen, the problem becomes weakly NP-hard. Our main result here is a bicriteria FPTAS to compute an approximate trade, which allows for slightly increased payments by w. The approximate trade results in nearly the optimal amount of assets of v in any exact trade. Our results extend to the case in which banks use general monotone payment functions to settle their debt and the emerging clearing state can be computed efficiently.
In contrast, for trading outgoing edges of v (i.e., claims for which v is the debtor), the goal is to maximize the increase in assets for the creditors of v. Notably, for these results the characteristics of the payment functions of the banks are essential. For payments ranking creditors one by one, we show NP-hardness of approximation within a factor polynomial in the network size, in both problem variants when the set of claims C is part of the input or not. Instead, for payments proportional to the value of each debt, our results indicate more favorable conditions
Application of the domain-integrated field relations method to the solution of large scale static and stationary magnetic field problems
No full textAuthor accepted manuscript of: “Application of the domain-integrated field relations method to the solution of large scale static and stationary magnetic field problems” IEEE Transactions on Magnetics, vol. 38, no. 2, pp. 465-468, Mar., 2002Electrical Engineering, Mathematics and Computer Scienc
Doelpuntdetectie met behulp van radartechnologie
No full textMaxad is een onlangs opgericht bedrijf dat begin 2009 op de markt zal komen met een systeem dat de reclameopbrengsten bij voetbalwedstrijden aanzienlijk zal verhogen. Het systeem is in staat om accuraat en snel doelpunten te detecteren. Bij de detectie van een doelpunt, worden alle elektronische reclameborden op elkaar afgestemd. Het op dat moment vertoonde item geniet dan exclusief alle aandacht. Derhalve wordt voor adverteerders een meerwaarde gecreëerd, met alle voordelen van dien. Het systeem combineert radartechnologie met beeldverwerking. De radars worden gebruikt om de positie van de bal te bepalen. Zodra de bal zich dicht bij het doel bevindt, zal een signaal worden afgeven aan het beeldverwerkingsysteem. Dit systeem zal bepalen of de bal de doellijn is gepasseerd. Maxad heeft onder andere het adviesbureau MaxRadar in het leven geroepen, dat als specialist in radartechnologie het radarsysteem zal ontwerpen. Overige adviesbureaus aangesteld door Maxad zijn MaxSoft en MaxImage, verantwoordelijk voor respectievelijk de software van het radarsysteem en het beeldverwerkingsysteem. In dit rapport zijn de verrichtingen weergegeven van MaxRadar. Er wordt beschreven hoe het ontwerp van de radaropstelling tot stand is gekomen. Tevens zijn de overwegingen weergegeven voor de bepalende onderdelen van een dergelijke opstelling. Het ontwerp van de verschillende onderdelen neemt veel tijd in beslag. Gezien de korte looptijd van het project, is de keuze gemaakt het ontwerpproces van één onderdeel specifiek uit te werken: de microstrip patch-antenne. In dit rapport wordt kort gekeken naar de verschillende methodes die beschikbaar zijn om de bal beter zichtbaar te maken voor de radar. Vervolgens wordt de evaluatie van het gebouwde prototype behandeld. Tot slot wordt een conclusie getrokken over het eindontwerp en er worden aanbevelingen gegeven voor verder onderzoek naar doelpuntendetectiesystemen met radartechnologie. Verschillende radaropstellingen zijn bedacht en geëvalueerd aan de hand van het programma van eisen. Uit de bestudering van de verscheidene opstellingen, is bepaald dat per doel drie radars nodig zijn, hetgeen het totaal aantal radars per stadion op zes brengt. Gekozen is voor de frequency modulated continuous wave (FMCW) radar. FMCW wordt hedendaags veel gebruikt en leent zich uitstekend voor afstandsbepaling met hoge resolutie. Bovendien is de productie van FMCW relatief goedkoop, omdat het ook volop wordt gebruikt in de auto-industrie. Voor de antenne zijn verschillende alternatieven beschikbaar. Deze antennes zijn beoordeeld aan de hand van een aantal specifieke eisen. De conclusie luidt dat microstrip patch-antennes het meest bruikbaar zijn. Deze antenne heeft de vereiste brede bundel. Bovendien zijn patch-antennes goedkoop, robuust en onderhoudsarm. Er zijn een aantal mogelijkheden om de bal beter zichtbaar te maken voor de radar. Een eerste mogelijkheid is om de bal inwendig te bekleden met reflectieverhogende materialen, zoals een laag aluminiumfolie. Uit metingen is gebleken dat deze methode de reflecties van de bal aanzienlijk vergroot. Door het materiaal een bepaald profiel te geven, kan de reflectiviteit nog verder worden verhoogd. Ook kan gebruik worden gemaakt van een verborgen eigenschap van golven, te weten de polarisatie. Tevens bestaat de optie om RFID technologie toe te passen.Electrical Engineering, Mathematics and Computer Scienc
ChildFinder Hardware: Technologiekeuzes, ontwerp en conceptdemonstratie
No full textThis bachelor thesis is written for the bachelorproject 'Where is my baby?'. This is one of the three thesis for the project, describing the technology choices, hardware design and concept demonstration of the ChildFinder. The ChildFinder is device that keeps an eye on children.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Emulation of a Photovoltaic System with Simulink
No full textNew research on the impact of home batteries, such as the Tesla Powerwall, on the electricity grid needs photovoltaic emulators, enabling to test independent of weather conditions. However, current PV emulators give little flexibility, are hard to implement, or very expensive. Current models are mostly focused on qualitative analysis, and not so much on quantitative analysis, for when one would like to simulate a full day. In this thesis, we describe how we have built a photovoltaic emulator that is digitally controlled by a Simulink model. The model contains the typical characteristics of a PV array and is optimized with Maximum Power Point Tracking (MPPT) and a Buck-Boost converter. The output signals of this model will communicate via the Modbus communication protocol to a programmable AC/DC-converter. This converter will provide a configurable power output to the household grid, simulating realistic day-to-day conditions of a typical PV panel. This enables a flexible and easy to use solution for future research topics like smart-grids and DC-grids.Electrical Engineering, Mathematics and Computer ScienceMicroelectronic
Efficient implementation of the domain-integrated field relations method for quasi-static magnetic fields
No full textAuthor accepted manuscript of the 17th Annual Review of Progress in Applied Computational Electromagnetics, Monterey, pp. 337-344, 19 Mar 2001 → 23 Mar 2001Electrical Engineering, Mathematics and Computer Scienc
The Time-Domain Optical Theorem in Antenna Theory
No full textA special form of the time-domain optical theorem related to a general receiving antenna system is rigorously derived. It is shown that the total energies dissipated in the antenna load and in the antenna system itself can be directly related to the electromagnetic energy of the scattered field and its time-domain far-fieldcharacteristics. A practical implication of the result in optimizing antenna scattering properties with regard to the maximum energy dissipated in the antenna loading is discussed.Accepted Author ManuscriptTera-Hertz Sensin
Signal Integrity in Pulse-train Excited Array Antennas in Time and Space - A Full TD Analysis
No full textSignal integrity in the far-field radiation from pulse-train excited array antennas is studied via full timedomain instruments. The disturbance in the received signal is related to the fidelity factor. At any point in our analysis, the disturbance is evaluated based on a reduced, well defined set of parameters: pulse parameters and pulse repetition rate – temporal dependence, and elementary radiator location – spatial dependence. Their effect is examined by means of illustrative numerical experiments. These results are expedient for enhancing the detectability of the signals radiated by pulse-train excited array antennas, as needed in wireless digital transfer.Accepted author manuscriptEEMS - GeneralTera-Hertz Sensin
A defence of Mr. Garrick, in answer to the letter-writer. With remarks upon plays and players, and the present state of the stage. By a dramatic author [electronic resource].
No full textThe letter-writer = H. W., i.e. Edward Purdon, author of 'A letter to David Garrick, Esq; on opening the Theatre' published 13 October, 1759.Price from imprint: price One-Shilling.Electronic reproduction.English Short Title Catalog,Reproduction of original from British Library
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