This paper explores alternative options for future human spaceflight programs which meet the goals of the Vision for Space Exploration and the Augustine Commission, within achievable cost and time limits. Based on four decades of NASA experience in on-orbit operations, an architecture is developed that allows access throughout cislunar space, including the surface of the Moon, through the use o...

This study discusses how to adjust “monetary budget” to meet each user’s physical power demand or balance all individual utilities in a competitive “spectrum market” of a communication system. In the market, multiple users share a common frequency or tone band and each of them uses the budget to purchase its own transmit power spectra (taking others as given) in maximizing its Shannon utility o...

C R E D IT : P A U L R IV E N B E R G /M . P . M C N A L L Y The U.S. fusion program is in a bind. To remain at the cutting edge, U.S. fusion researchers must participate in the huge international experiment called ITER being built in Cadarache, France. But to pay for ITER— which aims to produce a self-sustaining fusion reaction, or “burning plasma,” and prove that fusion is a viable energy sou...

We estimate and map the impacts that alternative national and subnational economic incentive structures for reducing emissions from deforestation (REDD+) in Indonesia would have had on greenhouse gas emissions and national and local revenue if they had been in place from 2000 to 2005. The impact of carbon payments on deforestation is calibrated econometrically from the pattern of observed defor...

The proliferation of inexpensive video recording hardware and enormous storage capacity has enabled the collection of retail customer behavior at an unprecedented scale. The vast majority of this data is used for theft prevention and never used to better understand the customer. In what ways can this huge corpus be leveraged to improve the experience of customer and the performance of the store...

Abstract: On December 2010, the government of Iran ended the decades-long subsidy program for bread and energy products and launched the Targeted Subsidy Reform program that considerably raised prices of food products. The objective of the study was to measure welfare impacts of food price changes on Iranian urban households between two survey data of 2009/10 and 2011/12 which were taken from I...

This research deals with the single machine scheduling problem (SMSP) with uncertain job processing times. The single machine robust scheduling problem (SMRSP) aims to obtain robust job sequences with minimum worst-case total flow time. We describe uncertain processing times using intervals, and adopt an uncertainty set that incorporates a budget parameter to control the degree of conservatism....

The US Medicare program consumes an ever-rising share of the federal budget. Although this public spending can produce health and social benefits, raising taxes to finance it comes at the cost of slower economic growth. In this article we describe a model incorporating the benefits of public programs and the cost of tax financing. The model implies that the "one-size-fits-all" Medicare program,...

Many existing welfare programs (“work-first” programs) require participants to work, often in non-profit or public agencies, in exchange for cash benefits. Others (“job search-first” programs) emphasize private job-search and provide assistance in finding and retaining a durable employment. We study the optimal design of welfare programs when the principal/government cannot observe the agent’s ...