Fundamental study in low-density gas dynamics Progress report, 1 Nov. 1968 - 30 Jun. 1969

Theoretical and experimental study of rarefied gas viscoseals in continuum to free molecular density range and speeds up to 30,000 rp

Fundamental study in low-density gas dynamics Progress report, 1 Nov. 1967 - 1 Nov. 1968

Rarefied gas dynamics, nozzle flow, and filterin

Water Yields in Utah Developing a State Water Plan

Need and Importance of Study Utah\u27s problems of water use and water supply are becoming increasingly important. They are also becoming increasingly complex as competition for our water resources becomes more keen among various types of uses. In the formulation of plans for sound and efficient use of water it is essential to know the characteristics of occurrence and use of water supplies so that requirements can be balanced most effectively and economically against supply. This ordinarily requires basic hydrologic data to determine relations among climate, water losses, and water yield from watersheds. Such data are often unavailable - especially for the smaller basins and streams which characterize many parts of Utah. With greater emphasis on small watersheds and small project development, some way of estimating quantities and characteristics of streamflow which are vital to hydraulic design is essential. In spite of increased emphasis and expenditures for development of water, the expansion of basic data programs still lags behind actual development. At present, investigations and data gathering are not completely adequate to delineate the potential water resources nor to determine the extent of possible development. Without an expanded program of surface and underground water investigations, we cannot hope to outline our potentials completely. However, a broad picture of long-time average annual runoff, developed indirectly or from data at hand, should have considerable value in first stage planning on a statewide basis. The total hydrologic picture must be outlined to evaluate better the effect of individual project development on future regional development programs. Piecemeal development frequently does not fit into an ultimate patterns for most complete and efficient use of the water resource within a region or state. To avoid this kind of development, those responsible for formulating water programs and policies need all the hydrologic information they can get. Deficiencies of such information lend great emphasis to the need for developing dependable indirect methods and techniques to speed preliminary hydrologic surveys. This study was undertaken to develop techniques useful in making was undertaken to develop techniques useful in making rapid and economical estimates of water supplies. The study is restricted to the estimation of mean annual values. Much other information regarding extremes and variations is necessary for detailed project planning. The objective in this study, however, is to provide means of getting a broad perspective of the state\u27s water supply of sufficient accuracy for initial planning a regional nature

Northern Neck Regional Shallow Draft Channel Dredging Plan: Initial Phase

The purpose of this project is to develop a regional dredging program for the localities of the Northern Neck. This report encompasses Phase 1 of the project, which included creating a database of waterbodies in Lancaster, Northumberland, Richmond, and Westmoreland Counties and the Town of Colonial Beach along the Potomac and Rappahannock Rivers and Chesapeake Bay. Generally, these waterbodies can be categorized into three basic types of shallow draft channels: federally-authorized to include aids to navigation (ATONS), non-federal with ATONS, and non-federal without ATONs. Along the Northern Neck, presently identified, are 13 federal channels, 37 non-federal channels in creeks with ATONs, and 92 in creeks without defined channels or ATONs, for a total of 142 waterbodies. Additional non-federal creeks, coves, branches, and ponds (all are interchangeably identified as waterbodies in this report) occur in these localities, but the analysis was limited to waterbodies that had some residential or economic usage. These waterbodies occur in Lancaster (35 waterbodies), Northumberland (67 waterbodies), Richmond (4 waterbodies), and Westmoreland (31 waterbodies) counties. To avoid double counting of waterbodies, 5 additional waterbodies that are located on the boundaries of these counties were attributed to just one county for this report. These waterbodies have been grouped within one of their boundary counties bringing the number of waterbodies in Lancaster to 38 and Westmoreland to 33. Physical parameter data was collected or created for each of these waterbodies. These data included creek mouth morphology, amount of shoaling in the waterbody mouth, waterbody type (primary, secondary, etc.), water surface area, combined shoreline length, historical (1971- 2020) and current (2016-2020) SAV presence, private and public oyster lease presence and the amount of area they cover, number of remotely-sensed coastal structures such as piers, marinas, boat ramps, and verified economic facilities such as marinas and other mooring places, resource, seafood related, and transportation facilities that impact the locality’s economics. Utilizing the collected data, the steps that localities need to take for additional data collection to develop a dredging project were outlined, and recommendations were made for additional regional management considerations for use in Phases 2 and 3. Finally, next steps were suggested. By creating a regional program for dredging of shallow water, localities can save time, effort, and money. Such a program also provides ways for localities to plan for the utilization of dredge material to combat repetitive flooding and improve coastal resiliency

Metal-insulator transition in a doped semiconductor

Millikelvin measurements of the conductivity as a function of donor density and uniaxial stress in bulk samples of phosphorus-doped silicon establish that the transition from metal to insulator is continuous, but sharper than predicted by scaling theories of localization. The divergence of the dielectric susceptibility as the transition is approached from below also points out problems in current scaling theories. The temperature dependence of the conductivity and the magnetoresistance in the metal indicate the importance of Coulomb interactions in describing the behavior of disordered systems

Fe XI emission lines in a high resolution extreme ultraviolet spectrum obtained by SERTS

New calculations of radiative rates and electron impact excitation cross sections for Fe XI are used to derive emission line intensity ratios involving 3s^23p^4 - 3s^23p^33d transitions in the 180-223 A wavelength range. These ratios are subsequently compared with observations of a solar active region, obtained during the 1995 flight Solar EUV Research Telescope and Spectrograph (SERTS). The version of SERTS flown in 1995 incorporated a multilayer grating that enhanced the instrumental sensitivity for features in the 170 - 225 A wavelength range, observed in second-order between 340 and 450 A. This enhancement led to the detection of many emission lines not seen on previous SERTS flights, which were measured with the highest spectral resolution (0.03 A) ever achieved for spatially resolved active region spectra in this wavelength range. However, even at this high spectral resolution, several of the Fe XI lines are found to be blended, although the sources of the blends are identified in the majority of cases. The most useful Fe XI electron density diagnostic line intensity ratio is I(184.80 A)/I(188.21 A). This ratio involves lines close in wavelength and free from blends, and which varies by a factor of 11.7 between N_e = 10^9 and 10^11 cm^-3, yet shows little temperature sensitivity. An unknown line in the SERTS spectrum at 189.00 A is found to be due to Fe XI, the first time (to our knowledge) this feature has been identified in the solar spectrum. Similarly, there are new identifications of the Fe XI 192.88, 198.56 and 202.42 A features, although the latter two are blended with S VIII/Fe XII and Fe XIII, respectively.Comment: 21 pages, 9 gigures, accepted for publication in the Astrophysical Journa

Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature and density sensitive line ratios, Doppler shifted emission lines and nonthermal broadening, abundance measurements, differential emission measure profiles, and continuum temperatures and energetics, among others. In this paper I shall review some of the advances made in recent years using these techniques, focusing primarily on studies that have utilized data from Hinode/EIS and SDO/EVE, while also providing some historical background and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the Topical Issue on Solar and Stellar Flare

Emission lines of Fe XI in the 257--407 A wavelength region observed in solar spectra from EIS/Hinode and SERTS

Theoretical emission-line ratios involving Fe XI transitions in the 257-407 A wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross sections. These are subsequently compared with both long wavelength channel Extreme-Ultraviolet Imaging Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291 A), and first-order observations (235-449 A) obtained by the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS). The 266.39, 266.60 and 276.36 A lines of Fe XI are detected in two EIS spectra, confirming earlier identifications of these features, and 276.36 A is found to provide an electron density diagnostic when ratioed against the 257.55 A transition. Agreement between theory and observation is found to be generally good for the SERTS data sets, with discrepancies normally being due to known line blends, while the 257.55 A feature is detected for the first time in SERTS spectra. The most useful Fe XI electron density diagnostic is found to be the 308.54/352.67 intensity ratio, which varies by a factor of 8.4 between N_e = 10^8 and 10^11 cm^-3, while showing little temperature sensitivity. However, the 349.04/352.67 ratio potentially provides a superior diagnostic, as it involves lines which are closer in wavelength, and varies by a factor of 14.7 between N_e = 10^8 and 10^11 cm^-3. Unfortunately, the 349.04 A line is relatively weak, and also blended with the second-order Fe X 174.52 A feature, unless the first-order instrument response is enhanced.Comment: 9 pages, 5 figures, 13 tables; MNRAS in pres

Multi-label classification using ensembles of pruned sets

This paper presents a Pruned Sets method (PS) for multi-label classification. It is centred on the concept of treating sets of labels as single labels. This allows the classification process to inherently take into account correlations between labels. By pruning these sets, PS focuses only on the most important correlations, which reduces complexity and improves accuracy. By combining pruned sets in an ensemble scheme (EPS), new label sets can be formed to adapt to irregular or complex data. The results from experimental evaluation on a variety of multi-label datasets show that [E]PS can achieve better performance and train much faster than other multi-label methods