A Comparison of EAST Shock-Tube Radiation Measurements with a New Air Radiation Model

This paper presents a comparison between the recent EAST shock tube radiation measurements (Grinstead et al., AIAA 2008-1244) and the HARA radiation model. The equilibrium and nonequilibrium radiation measurements are studied for conditions relevant to lunar-return shock-layers; specifically shock velocities ranging from 9 to 11 kilometers per second at initial pressures of 0.1 and 0.3 Torr. The simulated shock-tube flow is assumed one-dimensional and is calculated using the LAURA code, while a detailed nonequilibrium radiation prediction is obtained in an uncoupled manner from the HARA code. The measured and predicted intensities are separated into several spectral ranges to isolate significant spectral features, mainly strong atomic line multiplets. The equations and physical data required for the prediction of these strong atomic lines are reviewed and their uncertainties identified. The 700-1020 nm wavelength range, which accounts for roughly 30% of the radiative flux to a peak-heating lunar return shock-layer, is studied in detail and the measurements and predictions are shown to agree within 15% in equilibrium. The plus or minus 1.5% uncertainty on the measured shock velocity is shown to cause up to a plus or minus 30% difference in the predicted radiation. This band of predictions contains the measured values in almost all cases. For the highly nonequilibrium 0.1 Torr cases, the nonequilibrium radiation peaks are under-predicted by about half. This under-prediction is considered acceptable when compared to the order-of-magnitude over-prediction obtained using a Boltzmann population of electronic states. The reasonable comparison in the nonequilibrium regions provides validation for both the non-Boltzmann modeling in HARA and the thermochemical nonequilibrium modeling in LAURA. The N2 (+)(1-) and N2(2+) molecular band systems are studied in the 290 480 nm wavelength range for both equilibrium and nonequilibrium regimes. The non-Boltzmann rate models for these systems, which have significant uncertainties, are tuned to improve the comparison with measurements

HD66051: the first eclipsing binary hosting an early-type magnetic star

Early-type magnetic stars are rarely found in close binary systems. No such objects were known in eclipsing binaries prior to this study. Here we investigated the eclipsing, spectroscopic double-lined binary HD66051, which exhibits out-of-eclipse photometric variations suggestive of surface brightness inhomogeneities typical of early-type magnetic stars. Using a new set of high-resolution spectropolarimetric observations, we discovered a weak magnetic field on the primary and found intrinsic, element-dependent variability in its spectral lines. The magnetic field structure of the primary is dominated by a nearly axisymmetric dipolar component with a polar field strength $B_{\rm d}\approx600$ G and an inclination with respect to the rotation axis of $\beta_{\rm d}=13^{\rm o}$. A weaker quadrupolar component is also likely to be present. We combined the radial velocity measurements derived from our spectra with archival optical photometry to determine fundamental masses (3.16 and 1.75 $M_\odot$) and radii (2.78 and 1.39 $R_\odot$) with a 1-3% precision. We also obtained a refined estimate of the effective temperatures (13000 and 9000 K) and studied chemical abundances for both components with the help of disentangled spectra. We demonstrate that the primary component of HD66051 is a typical late-B magnetic chemically peculiar star with a non-uniform surface chemical abundance distribution. It is not an HgMn-type star as suggested by recent studies. The secondary is a metallic-line star showing neither a strong, global magnetic field nor intrinsic spectral variability. Fundamental parameters provided by our work for this interesting system open unique possibilities for probing interior structure, studying atomic diffusion, and constraining binary star evolution.Comment: 14 pages, 15 figures; accepted for publication in MNRA

Applications of radio interferometry to navigation

Radio astronomy experiments have demonstrated the feasibility of making precise position measurements using interferometry techniques. The application of this method to navigation and marine geodesy is discussed, and comparisons are made with existing navigation systems. The very long baseline technique, with a master station, can use either an artificial satellite or natural sources as position references; a high-speed data link is required. A completely ship-borne system is shown to be feasible, at the cost of poorer sensitivity for natural sources. A comparison of Doppler, delay and phase-track modes of operating a very long baseline configuration is made, as that between instantaneous measurements and those where a source can be tracked from horizon to transit. Geometric limitations in latitude and longitude coverage are discussed. The characteristics of natural radio sources, their flux, distribution on the sky, and apparent size are shown to provide a limit on position measurements precision. The atmosphere and frequency standard used both contribute to position measurement uncertainty by affecting interferometric phase

Dominican Republic: the development of a tropical agrarian economy

Thesis (M.A.)--Boston UniversityThe islands and nations of the Caribbean are beset by numerous problems which retard economic development. Most critical of these problems are limited natural resources, a heavy dependence on monoculture, backward agricultural practices and high population densities. Although the Dominican Republic shares these problems with neighboring islands and countries, this nation has exerted considerable efforts toward strengthening its economy. This study examines the Dominican Republic geographically with particular emphasis on the nation's ability to develop its economy and to achieve a standard of living hitherto unknown among other tropical agrarian economies of the Caribbean. The Dominican Republic occupies the eastern two-thirds of the island of Hispaniola. This island lies at the convergence of two major cordillera axes of the West Indies and is the most rugged island of the Greater Antilles. In general, the mountains tend in an east to west direction with the Cordillera Central dominating the island and extending nearly the entire length of the country. Mountainous terrain covers approximately 60 per cent of the nation's area. Of remaining level lands the most important are the Cibao Valley north of the Cordillera Central and the South Coastal Plain which occupies the eastern two-thirds of the country south ot this cordillera. Easterly trade winds dominate the climate, which generally is warm and humid. Heaviest rainfall occurs in the northeast where a tropical rainforest is found. Southern and western sections of the country exhibit a savanna type of climate with maximum precipitation coming in the period of high insolation. The north coast also has a savanna climate, but maximum rainfall there comes in the winter months. The southwestern corner of the country, while basically having a savanna climate, is drier than other areas and certain sections are sub-humid. In spite of these climatic conditions of generally abundant rainfall and warm temperatures which favor agriculture, centuries of neglect, corruption, revolutions and wars hindered the development of a sound agricultural policy. When the Trujillo regime gained control of the country in 1930 measures were instituted to improve the farm economy. Irrigation projects in sub-humid western areas, agricultural colonies to settle these areas, and land distribution among hitherto landless peasants were the major aspects of the overall agricultural program. Principal aims of this program were the diversification of agricultural exports and a greater self-sufficiency in domestic foodstuffs. Attaimnent of these two goals has met with a fair degree of success. Heavy dependence on the export of sugar for national revenue has been reduced and this crop now is strongly supported by coffee and cacao. Although the country still imports large quantities of foodstuffs, the Republic's farms have reduced these imports from 27 per cent of all imports in 1929 to 10.5 per cent in 1954 without any reduction in domestic consumption. At the same time, exports of certain foodstuffs have been possible and the nation has the potential to become an important exporter of foodstuffs to neighboring Caribbean areas. This overall agricultural program has created a farm economy pattern. that is reflected in the nation's six major agricultural regions. These are the commercial sugar cane belt of the South Coastal Plain, the coffee and cacao belt of the eastern Cibao Valley, mixed commercial and subsistence agriculture of the central Cibao Valley , irrigated rice lands of the western Cibao Valley, mixed farming and grazing lands of the western interior valleys, and irrigated sugar cane of the Enlriquillo Basin. In conjunction with the program of agriculture there has been a policy of industrial expansion predicated on the development of industries utilizing the nation's natural resources. A general lack of minerals and fuels precluded heavy industry and the main emphasis has been on light industries engaged in processing the products of agriculture. Thus today the processing of agricultural products accounts for 80 per cent of sales in Dominican industry, with the crops of commercial agriculture contributing most heavily. Other significant categories of the Dominican industrial complex are textiles, the extraction and processing of metallic and non-metallic minerals, and chemicals. Although ranking far behind agricultural processing with respect to the national economy, these industries have a potential for future expansion. Perhaps the brightest prospect lies within the chemical industry. The nation possesses large reserves of salt which hardly have been exploited. A gradual development of chemical industries built around salt would appear to be a wise policy for the future. All told, the expansion of industry since 1936 has been impressive. The number of employees has increased by 300 per cent, the number of industrial establishments by 300 per cent; the invested capital by 250 per cent and the value of sales by 1,000 per cent. In spite of the progress made since 1930 in revitalizing the nation's economy, succeeding years will continue to be critical if the nation is to realize its economic potential. Although programs for agriculture have enhanced the farm economy, little has been done to aid the small farmer who comprises the bulk of the population. Even today, his methods of cultivation are crude and his awareness of modern agricultural practices is slight. In addition, dependence on sugar still is potentially dangerous. Markets for this crop are not dependable and when world demands drop the economic structure of the nation is severely effected. Industrial development will continue only through a sensible utilization of the nationts natural resources. Although there are modest reserves of iron ore it does not seem sensible to plan construction of a steel mill. This has been proposed, however, and prior to this a shipyard and munitions factory were built. Projects such as these can undo the benefits of less grandiose but more rational programs that have been carried out in the past quarter century. One detriment to economic development that existed in the past, under-population; no longer is present. Since 1900 population has expanded 500 per cent and the country appears headed for densities that now beset many other West Indian islands. Over population is a major factor contributing to the many economic ills that plague these islands. In order to accommodate the increasing numbers of people and still provide a decent standard of living, the Dominican Republic must effectively utilize all available farmland, strengthen the position of the small fanner, and continue the expansion of light industries that are natural to the country

Statistical considerations in a systematic review of proxy measures of clinical behaviour

Peer reviewedPublisher PD

Understanding Violent Adolescent Males: Implications for Post Release Recidivism

Simple assault is common among mid-adolescent males in Iowa and throughout the United States. The barriers and supports that exist for mid-adolescents when choosing nonviolence is well-documented in past research. Little is known about the choice of nonviolence for mid-adolescent males who have been labeled delinquent by juvenile courts.https://scholarworks.waldenu.edu/archivedposters/1079/thumbnail.jp