8,974 research outputs found
Comparative analyses of space-to-space central power stations
The technological and economical impact of a large central power station in Earth orbit on the performance and cost of future spacecraft and their orbital transfer systems are examined. It is shown that beaming power to remote users cannot be cost effective if the central power station uses the same power generation system that is readily available for provision of onboard power and microwave transmission and reception of power through space for use in space is not cost competitive with onboard power or propulsion systems. Laser and receivers are required to make central power stations feasible. Remote power transmission for propulsion of orbital transfer vehicles promises major cost benefits. Direct nuclear pumped or solar pumped laser power station concepts are attractive with laser thermal and laser electric propulsion systems. These power stations are also competitive, on a mass and cost basis, with a photovoltaic power station
Implanted QR Code Enabled Incentivized System for Container Reuse
Single use disposable containers are widely used for a variety of products. Reuse of the containers offers environmental benefits. This disclosure describes techniques to facilitate efficient reuse of commodity packaging via an incentivized system for tracking of purchases. During product manufacture, unique metallic QR codes are embedded into product containers marked with a sticker indicative of the amount due to the consumer for the returned container. The QR codes are registered in a central database and enable tracking of the containers. Upon completion of product use, consumers can place the container into repositories placed at suitable locations. A full-sphere X-ray is used to read multiple QR codes and provide immediate credit to the consumer while recording container details. Product use information associated with consumers can be determined based on the recovered containers. With user permission, purchase information of specific products can be utilized to determine the effectiveness of advertisements. A portion of advertising revenue can be shared with the consumer
Ready to trade? On budget-balanced efficient trade with uncertain arrival
This paper studies the design of e¢ cient mechanisms for repeated trade in settings where (i) tradersvalues and costs evolve randomly with time, and (ii) the traders become ready and available to participate in the mechanism at random times. Under a weak condition, analogous to the non-overlapping supports condition of Myerson and Satterthwaite (1983), e¢ cient trade is only feasible if the mechanism runs an expected budget decit. The smallest such decit is attainable by a sequence of static mechanisms
How do secondary school SENDCos and Career Leads perceive the successes and barriers to identifying and supporting those at risk of becoming NEET, and how might educational psychologists support in this area?
Investigation of the Electronic Properties of Organic Systems Using Electroabsorption Spectroscopy
The aim of this project is to investigate the effect of bulk structural modification on the electronic properties of fullerene systems as measured using electronic and Electroabsorption (EA) spectroscopy. The existence of a unique solid state feature in C60 is the first indication that the material’s electronic properties may be influenced by its crystalline environment and as such merits investigation. The nature and extent of these interactions in the solid state is still unclear, in particular whether the molecular electrons remain located on the individual molecules or whether they are delocalised across the solid. The extent of these interactions has major repercussions for any proposed electronic or optical applications for fullerenes e.g. in optical switches of luminescent displays. This work presents the effect of structurally altering fullerene films using systematic thermal treatments. A dramatic irreversible effect is observed in the absorption spectrum of C60 as the sample is annealed, indicating a reduction in the charge transfer (CT) processes associated with these transitions. This reduction can be attributed to a closer packing of the molecules in the solid state phase. Data obtained form EA spectroscopy confirms the reduction oscillator strength of the mode at 2.43eV normally associated with the off diagonal CT state again supporting the notion of a closer packed lattice. Analysis of C70 fullerene films also shows an associated increase in oscillator strength of the CT integrals as a result of the thermal treatment process, highlighting the importance of the material’s crystalline environment in determining the material’s electronic propertie
Dynamic Mechanism Design
We study the optimal mechanism in a dynamic sales relationship where the buyerÃs arrival date is uncertain, and where his value changes stochastically over time. The buyerÃs arrival date is the Örst date at which contracting is feasible and is his private information. To induce immediate participation, the buyer is granted positive expected rents even if his value at arrival is the lowest possible. The buyer is punished for arriving late; i.e., he expects to earn less of the surplus. Optimal allocations for a late arriver are also further distorted below Örst-best levels. Conditions are provided under which allocations converge to the e¢ cient ones long enough after contracting, and this convergence occurs irrespective of the time the contract is initially agreed (put di§erently, the so-called "principle of vanishing distortions" introduced by Battaglini (2005) continues to apply irrespective of the buyerÃs arrival date)
Dynamic Mechanism Design
We study the optimal mechanism in a dynamic sales relationship where the buyerÃs arrival date is uncertain, and where his value changes stochastically over time. The buyerÃs arrival date is the Örst date at which contracting is feasible and is his private information. To induce immediate participation, the buyer is granted positive expected rents even if his value at arrival is the lowest possible. The buyer is punished for arriving late; i.e., he expects to earn less of the surplus. Optimal allocations for a late arriver are also further distorted below Örst-best levels. Conditions are provided under which allocations converge to the e¢ cient ones long enough after contracting, and this convergence occurs irrespective of the time the contract is initially agreed (put di§erently, the so-called "principle of vanishing distortions" introduced by Battaglini (2005) continues to apply irrespective of the buyerÃs arrival date)
- …