17,550 research outputs found
Studies of magnetostriction and spin polarized band structures of rare earth intermetallics
Anisotropic magnetostriction measurements of R6Fe23, R = (Tb, Dy, Ho, and Er) were carried out from 77 K to room temperature. Magnetic fields up to 2.1 Tesla were applied. All the compounds exhibited large magnetostrictions at 77 K, the largest effect being obtained for Tb6Fe23. Saturation magnetostriction values for the compounds were also determined for 77 K and room temperature. Results of the temperature dependence of magnetostriction for Er6Fe23 are in good agreement with Callen and Callen's single ion theory. Therefore, the main sources of magnetostriction in this compound is the Er ion. The spin-up and spin-down electronic energy bands, the density of states and the magnetic moments of YCo5, SmCo5, and GdCo5 were calculated by the spin polarized augmented plane wave technique. The calculations obtained show the origin of the moment, provide good estimates of its magnitude and variation, and the reasons for those variations. They also show the important role of partial charge transfer and of d-d electronic coupling. Calculations for LaNi5 and GdNi5 systems are discussed
Pre-emphasis determination for an S-band constant bandwidth FM/FM station
Telemetry bands are being reassigned to UHF at 1500 and 2200 MHz. Conversion primarily requires changes in equipment used in RF link, while many of same subcarrier oscillators, mixer amplifiers, and frequency discriminators can be used
Investigation of new radar-data-reduction techniques used to determine drag characteristics of a free-flight vehicle
An investigation was conducted of new techniques used to determine the complete transonic drag characteristics of a series of free-flight drop-test models using principally radar tracking data. The full capabilities of the radar tracking and meteorological measurement systems were utilized. In addition, preflight trajectory design, exact kinematic equations, and visual-analytical filtering procedures were employed. The results of this study were compared with the results obtained from analysis of the onboard, accelerometer and pressure sensor data of the only drop-test model that was instrumented. The accelerometer-pressure drag curve was approximated by the radar-data drag curve. However, a small amplitude oscillation on the latter curve precluded a precise definition of its drag rise
Cellulosic Biofuels Analysis: Economic Analysis of Alternative Technologies
The passage of U.S. laws mandating and subsidizing advanced cellulosic biofuels may spur the development of a commercial cellulosic biofuels industry. However, a cellulosic industry will only develop if the overall economics including government incentives render investment in the sector attractive to private investors.This study compares the profitability of three biofuel production types: grain based ethanol, cellulosic biochemical ethanol, and cellulosic thermochemical biofuels. In order to compare the current profitability of each of the production types, the Biofuels Comparison Model (BCM) was developed. The BCM is a spreadsheet model that estimates the net present value (NPV) for each production type given input and output prices, technical, and financial assumptions. The BCM can be updated to reflect the current profitability through embedded web price links. The study finds that grain, biochemical, and thermochemical production types are all currently unprofitable when subsidies and mandates are ignored. However, the grain based ethanol process is predicted to be the most profitable (lowest loss) compared to the cellulosic biofuels. When the 2008 Farm Bill subsidies are added to the BCM, all three production types are projected to be profitable. With the addition of the different subsidies, the cellulosic biofuels are estimated to have higher NPVâs than grain based ethanol. When compared on an energy equivalent basis, the estimated cost of producing grain ethanol is 141/bbl., and thermochemical gasoline $108/bbl.biofuels, cellulosic biofuels, corn ethanol, biofuel economics
A summary of the test procedures and operational details of an ocean dumping pollution monitoring experiment conducted 7 October 1976
A remote sensor experiment was conducted at a sewage sludge dump site off the Delaware/Maryland coast. Two aircraft serving as remote sensor platforms flew over the dump site during a sludge dump. One aircraft carried a multispectral scanner and the other aircraft carried a rapid scanning spectrometer. Data from sea-truth stations were collected concurrent with overpasses of the aircraft. All sensors were operational and produced good digital data
Development of an experimental space station model for structural dynamics research
Design, analysis, and testing of an experimental space station scale model is presented. The model contains hardware components with dynamic characteristics similar to those expected for other large space structures. Validation of analysis models is achieved through correlation with dynamic tests of hardware components and representative assembly configurations. A component mode synthesis analysis method is examined through comparisons with results from fully mated system models. Selection of input requirements for accurate component synthesis analysis predictions are assessed
Farm Income Stabilization: A Central Goal for American and European Policies
The central thesis developed in this paper is that snapshot views of the global measures of agricultural support mask what is really happening in U.S. and E.U. agricultural policies. We demonstrate that American and European farmers are effectively protected from market risk by these policies. The level of PSE is largely determined by the level of world price. Most economists do not pay much attention to the role of agricultural policies in income stability. Yet farm income stability is clearly a prime objective of government policy both in the E.U. and the U.S. and probably elsewhere. We need to turn out attention to this objective if we are to produce policy analysis relevant to real world policy decisions.agricultural policy, market risks, agricultural income, U.S., E.U., agricultural and natural resource economics, Agricultural and Food Policy,
Implications of the Biofuels Boom for the Global Livestock Industry: A Computable General Equilibrium Analysis
In this paper, we offer a general equilibrium analysis of the impacts of US and EU biofuel mandates for the global livestock sector. Our simulation boosts biofuel production in the US and EU from 2006 levels to mandated 2015 levels. We show that mandates will encourage crop production in both biofuel and non biofuel producing regions, while reducing livestock and livestock production in most regions of the world. The non-ruminant industry curtails its production more than other livestock industries. The numerical results suggest that the biofuel mandates reduce food production in most regions while they increase crude vegetable oils in almost all regions. Implementing biofuel mandates in the US and EU will increase croplands within the biofuel and non-biofuel producer regions. A large portion of this increase will be obtained from reduced grazing lands. The biofuel producing regions are expected to reduce their coarse grains exports and raise imports of oilseeds and vegetable oils. While all livestock industries use more biofuel byproducts in their animal feed rations, the dairy and other ruminant industry benefit most from the expansion of DDGS. We finally conclude that, while biofuel mandates have important consequences for the livestock industry, they do not harshly curtail these industries. This is largely due to the important role of byproducts in substituting for higher priced feedstuffs. In addition, with relatively inelastic food demands, producers are able to pass much of the price rise on to consumers. In general, US, EU, Meddle East & North Africa, and Russia will experience significant welfare loses due to the combined US and EU mandates, while Brazil, Japan, India, and East Asia are expected to get major gains.Biofuels, Livestock, Feed Ration, Biofuel Co-Product, Land Use, Livestock Production/Industries,
Biofuels for all? Understanding the Global Impacts of Multinational Mandates
The recent rise in world oil prices, coupled with heightened interest in the abatement of greenhouse gas emissions, has led to a sharp increase in domestic biofuels production around the world. Previous authors have devoted considerable attention to the impacts of these policies on a country-by-country basis. However, there are also strong interactions among these programs, as they compete in world markets for feedstocks and ultimately for a limited supply of global land. In this paper, we evaluate the interplay between two of the largest biofuels programs, namely the renewable fuel mandates in the US and the EU. We examine how the presence of each of these programs influences the other, and also how their combined impact influences global markets and land use around the world. We begin with an analysis of the origins of the recent bio-fuel boom, using the historical period from 2001-2006 for purposes of model validation. This was a period of rapidly rising oil prices, increased subsidies in the EU, and, in the US, there was a ban on the major competitor to ethanol for gasoline additives. Our analysis of this historical period permits us to evaluate the relative contribution of each of these factors to the global biofuel boom. We also use this historical simulation to establish a 2006 benchmark biofuel economy from which we conduct our analysis of future mandates. Our prospective analysis of the impacts of the biofuels boom on commodity markets focuses on the 2006-2015 time period, during which existing investments and new mandates in the US and EU are expected to substantially increase the share of agricultural products (e.g., corn in the US, oilseeds in the EU, and sugar in Brazil) utilized by the biofuels sector. In the US, this share could more than double from 2006 levels, while the share of oilseeds going to biodiesel in the EU could triple. Having established the baseline 2006-2015 scenario, we proceed to explore the interactions between the US and EU policies. This involves decomposing the contributions of each set of regional policies to the global changes in output and land use. The most dramatic interaction between the two sets of policies is for oilseed production in the US, where the sign of the output change is reversed in the presence of EU mandates (rising rather than falling). In other sectors, the interaction is more modest. However, when it comes to the impacts of these combined mandates on third economies, the two policies combine to have a much greater impact than just the US or just the EU policies alone.Resource /Energy Economics and Policy,
Pseudo-noise test set for communication system evaluation
A test set for communications systems is described which includes a pseudo noise sequence generator providing a test signal that is fed to a pair of signal channels. The first channel includes a spectrum shaping filter and a conditioning amplifier. The second channel includes a variable delay circuit, a spectrum shaping filter matched to the first filter, and an amplifier. The output of the first channel was applied to the system under test. The output of the system and the output of the second channel are compared to determine the degree of distortion suffered by the test signal due to the communications system
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