The Probability Of Mission Success /POMS/

Probability of mission success by trajectory optimization for translunar space flight

Energy issues in the developing world

In 1986 and 1987 the lower oil prices called into question many of the fundamental assumptions that were the stock in trade of energy experts during the previous ten years. This document is a collection of papers representing responses to concerns prepared by current and former World Bank staff. Although these papers raise a variety of different concerns, a common theme that runs throughout the paper is the need to continue the pursuit of efficiency goals in the energy sector. The developing world still needs large amounts of capital to meet its ever-expanding energy requirements. These capital requirements will be a significant part of most countries'total investment plan. Given the problems of debt and public revenues, the report concludes that the pursuit of efficiency is just as important under lower fuel prices as it is under rising fuel prices.Power&Energy Conversion,Urban Environment,Environmental Economics&Policies,Energy Demand,Energy and Environment

Agricultural Globalization in Developing Countries: Rules, Rationales and Results

This paper aims to provide a descriptive and analytical account of the extent to which agriculture in the developing economies has become integrated with external markets. For most developing economies (DEs), the 1980s were a time of crisis when liberal reforms, including domestic and external liberalization of agriculture, were also initiated. This was followed by the coming into force of the Agreement on Agriculture under WTO aegis. The evidence on trade flows does indicate increased agricultural globalization in developing economies (DEs) following these regime shifts. But increased trade flows have not been accompanied by relative price convergence as between the DEs and the advanced economies (AEs) suggesting both that the policy shifts have been asymmetric and that significant parts of agricultural trade between North and South remain complementary rather than, as is often assumed, competitive. Moreover, the “fallacy of composition”, implicit in any global imposition of trade liberalization and not confined to primary products as such, also seems to have been at work for most of the period. At the same time, the threat of higher consumer prices (especially for the poor and vulnerable in both importing and exporting DEs) looms large. Its impact will be felt as and when production and export subsidies in the AEs are dismantled. Meanwhile, the regime shifts seem to have induced, on the one hand, excessive faith in the efficacy of agricultural prices to produce agricultural supply response and, on the other, reduced fiscal and organizational capacities to provide public agricultural inputs and services. These conclusions are consonant with a structuralist understanding of global trade and production possibilities that DEs confront.

Aquaculture Productivity Convergence in India: A Spatial Econometric Perspective

This paper provides an illustration of evaluating productivity convergence using spatial econometric modelling framework for the aquaculture sector in India. Productivity has been measured using Total Factor Productivity (TFP). The b- and s-convergence concepts that are used to test the convergence hypothesis have been extended to examine the possible presence of spatial autocorrelation and spatial heterogeneity. The results have confirmed the productivity convergence hypothesis, the presence of spillover effects on TFP growth and the presence of spatial regimes in the TFP convergence process which have policy implications. The paper concludes by providing recommendations for further research.Agricultural and Food Policy,

Instant restore after a media failure

Media failures usually leave database systems unavailable for several hours until recovery is complete, especially in applications with large devices and high transaction volume. Previous work introduced a technique called single-pass restore, which increases restore bandwidth and thus substantially decreases time to repair. Instant restore goes further as it permits read/write access to any data on a device undergoing restore--even data not yet restored--by restoring individual data segments on demand. Thus, the restore process is guided primarily by the needs of applications, and the observed mean time to repair is effectively reduced from several hours to a few seconds. This paper presents an implementation and evaluation of instant restore. The technique is incrementally implemented on a system starting with the traditional ARIES design for logging and recovery. Experiments show that the transaction latency perceived after a media failure can be cut down to less than a second and that the overhead imposed by the technique on normal processing is minimal. The net effect is that a few "nines" of availability are added to the system using simple and low-overhead software techniques

Continuous quantum error correction

We describe new implementations of quantum error correction that are continuous in time, and thus described by continuous dynamical maps. We evaluate the performance of such schemes using numerical simulations, and comment on the effectiveness and applicability of continuous error correction for quantum computing.Comment: 6 pages, 3 figures. Presented at QCMC '04 (Univ. of Strathclyde, Glasgow, UK, July 25-29, 2004

Multi-keyword multi-click advertisement option contracts for sponsored search

In sponsored search, advertisement (abbreviated ad) slots are usually sold by a search engine to an advertiser through an auction mechanism in which advertisers bid on keywords. In theory, auction mechanisms have many desirable economic properties. However, keyword auctions have a number of limitations including: the uncertainty in payment prices for advertisers; the volatility in the search engine's revenue; and the weak loyalty between advertiser and search engine. In this paper we propose a special ad option that alleviates these problems. In our proposal, an advertiser can purchase an option from a search engine in advance by paying an upfront fee, known as the option price. He then has the right, but no obligation, to purchase among the pre-specified set of keywords at the fixed cost-per-clicks (CPCs) for a specified number of clicks in a specified period of time. The proposed option is closely related to a special exotic option in finance that contains multiple underlying assets (multi-keyword) and is also multi-exercisable (multi-click). This novel structure has many benefits: advertisers can have reduced uncertainty in advertising; the search engine can improve the advertisers' loyalty as well as obtain a stable and increased expected revenue over time. Since the proposed ad option can be implemented in conjunction with the existing keyword auctions, the option price and corresponding fixed CPCs must be set such that there is no arbitrage between the two markets. Option pricing methods are discussed and our experimental results validate the development. Compared to keyword auctions, a search engine can have an increased expected revenue by selling an ad option.Comment: Chen, Bowei and Wang, Jun and Cox, Ingemar J. and Kankanhalli, Mohan S. (2015) Multi-keyword multi-click advertisement option contracts for sponsored search. ACM Transactions on Intelligent Systems and Technology, 7 (1). pp. 1-29. ISSN: 2157-690

Fish Supply Projections by Production Environments and Species Types in India

The supply studies on the fisheries sector in India have been addressed at the disaggregated level by production environment and by species groups. These would be more imperative and useful for assessing the fish supply at the national level. The fish supply projections by species groups under different production environments have been obtained to a medium-term horizon, by the year 2015 under various technological scenarios. The study has concluded that the supply response to fish price changes has been stronger under aquaculture than marine environment in India. Price and technology have been reported as the important instruments to induce higher supply. The change in the relative prices of fish species would change the species-mix in the total supply. The fish production has been projected as 4.6-5.5 million tonnes of inland fish and 3.2-3.6 million tonnes of marine fish by the year 2015. More than 60 per cent of the additional fish production will be contributed by aquaculture and mainly by the Indian major carps.Agricultural and Food Policy,

High-Velocity Features in Type Ia Supernova Spectra

We use a sample of 58 low-redshift (z <= 0.03) Type Ia supernovae (SNe Ia) having well-sampled light curves and spectra near maximum light to examine the behaviour of high-velocity features (HVFs) in SN Ia spectra. We take advantage of the fact that Si II 6355 is free of HVFs at maximum light in all SNe Ia, allowing us to quantify the strength of HVFs by comparing the structure of these two lines. We find that the average HVF strength increases with decreasing light-curve decline rate, and rapidly declining SNe Ia (dm_15(B) >= 1.4 mag) show no HVFs in their maximum-light spectra. Comparison of HVF strength to the light-curve colour of the SNe Ia in our sample shows no evidence of correlation. We find a correlation of HVF strength with the velocity of Si II 6355 at maximum light (v_Si), such that SNe Ia with lower v_Si have stronger HVFs, while those SNe Ia firmly in the "high-velocity" (i.e., v_Si >= 12,000 km/s) subclass exhibit no HVFs in their maximum-light spectra. While v_Si and dm_15(B) show no correlation in the full sample of SNe Ia, we find a significant correlation between these quantities in the subset of SNe Ia having weak HVFs. In general, we find that slowly declining (low dm_15(B)) SNe Ia, which are more luminous and more energetic than average SNe Ia, tend to produce either high photospheric ejecta velocities (i.e., high v_Si) or strong HVFs at maximum light, but not both. Finally, we examine the evolution of HVF strength for a sample of SNe Ia having extensive pre-maximum spectroscopic coverage and find significant diversity of the pre-maximum HVF behaviour.Comment: Version accepted by MNRA