Hydrodynamic optimization of ship hull forms     

Scott Percival  Dane Hendrix  Francis Noblesse   《Applied Ocean Research》2001,23(6):1429

An extremely simple CFD tool is used to compare the calm-water drags of a series of hull forms and to define ‘optimized’ monohull ships for which the total (friction+wave) calm-water drag is minimized. The friction drag is estimated using the classical ITTC formula. The wave drag is predicted using the zeroth-order slender-ship approximation. Comparisons of theoretical predictions and experimental measurements for a series of eight hull forms show that—despite the extreme simplicity of the method that is used here to estimate the friction drag and the wave drag—the method is able to rank the drags of a series of hull forms roughly in accordance with experimental measurements. Thus, the method may be used, with appropriate caution, as a practical hull form design and optimization tool. For purposes of illustration, optimized hull forms that have the same displacement and waterplane transverse moment of inertia as the classical Wigley hull, taken as initial hull in the optimization process, are determined for three speeds and for a speed range.  相似文献   

Temperature dependence of large-scale water-retention curves: a case study     

Hui-Hai Liu  G. S. Bodvarsson  J. H. Dane 《Hydrogeology Journal》2006,14(8):1403-1408

A local-scale model for temperature-dependence of water-retention curves may be applicable to large scales. Consideration of this temperature dependence is important for modeling unsaturated flow and transport in the subsurface in numerous cases. Although significant progress has been made in understanding and modeling this temperature effect, almost all the previous studies have been limited to small scales (on the order of several centimeters). Numerical experiments were used to investigate the possibility of extending a local-scale model for the temperature-dependence of water retention curves to large scales (on the order of meters). Temperature effects on large-scale hydraulic properties are of interest in many practical applications. Numerical experiment results indicate that the local-scale model can indeed be applicable to large-scale problems for special porous media with high air entry values. A typical porous medium of this kind is the porous tuff matrix in the unsaturated zone of Yucca Mountain, Nevada, the proposed geologic disposal site for national high-level nuclear wastes. Whether this finding can approximately hold for general cases needs to be investigated in future studies.  相似文献   

Spatial–temporal variability and hydrologic connectivity of runoff generation areas in a North Alabama pasture—implications for phosphorus transport     

Sumit Sen  Puneet Srivastava  Jacob H. Dane  Kyung H. Yoo  Joey N. Shaw 《水文研究》2010,24(3):342-356

This study delineated spatially and temporally variable runoff generation areas in the Sand Mountain region pasture of North Alabama under natural rainfall conditions, and demonstrated that hydrologic connectivity is important for generating hillslope response when infiltration‐excess (IE) runoff mechanism dominates. Data from six rainfall events (13·7–32·3 mm) on an intensively instrumented pasture hillslope (0·12 ha) were analysed. Analysis of data from surface runoff sensors, tipping bucket rain gauge and HS‐flume demonstrated spatial and temporal variability in runoff generation areas. Results showed that the maximum runoff generation area, which contributed to runoff at the outlet of the hillslope, varied between 67 and 100%. Furthermore, because IE was the main runoff generation mechanism on the hillslope, the data showed that as the rainfall intensity changed during a rainfall event, the runoff generation areas expanded or contracted. During rainfall events with high‐intensity short‐ to medium‐duration, 4–8% of total rainfall was converted to runoff at the outlet. Rainfall events with medium‐ to low‐intensity, medium‐duration were found less likely to generate runoff at the outlet. In situ soil hydraulic conductivity (k) was measured across the hillslope, which confirmed its effect on hydrologic connectivity of runoff generation areas. Combined surface runoff sensor and k‐interpolated data clearly showed that during a rainfall event, lower k areas generate runoff first, and then, depending on rainfall intensity, runoff at the outlet is generated by hydrologically connected areas. It was concluded that in IE‐runoff‐dominated areas, rainfall intensity and k can explain hydrologic response. The study demonstrated that only connected areas of low k values generate surface runoff during high‐intensity rainfall events. Identification of these areas would serve as an important foundation for controlling nonpoint source pollutant transport, especially phosphorus. The best management practices can be developed and implemented to reduce transport of phosphorus from these hydrologically connected areas. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Book review     

W. E. Sharp  M. Dane Picard  Jean-Fran?ois Gaillard 《Mathematical Geology》1992,24(4):437-447

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Book review     

W. E. Sharp  M. Dane Picard  Jean-François Gaillard 《Mathematical Geosciences》1992,24(4):437-447

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Fourier contamination of a finite length of data in tidal analysis     

Dane Blair 《Geophysical Journal International》1979,59(3):523-528

Summary. The contamination effect when a discrete Fourier analysis is applied to a short length of data in order to estimate the main diurnal (O₁) and semi-diurnal (M₂) components of the solid body tide is estimated and it is shown that a moderate length of record (30 days) has distinct advantages over larger record lengths of less than 60 days or so.  相似文献   

Examination of the chlorate factor in electro-oxidation leaching of molybdenum concentrates using flow-through cells     

D.S. Barr  B.J. Scheiner  J.L. Hendrix 《International Journal of Mineral Processing》1977,4(2):83-88

A study was made of the United States Bureau of Mines' electro-oxidation process for the recovery of molybdenum from molybdenite. The investigation sought to determine operating conditions which would minimize by-product chlorate formation and the resulting loss in current efficiency. Such minimization would contribute to making the process economically attractive.It has been shown that a continuous flow-through graphite cell process produces less chlorate than either graphite or lead anode batch operations during the electro-oxidation of molybdenite at low temperatures, approximately 30°C.  相似文献   

The UV signature of carbon in the solar system          下载免费PDF全文

Amanda R. Hendrix  Faith Vilas  Jian‐Yang Li 《Meteoritics & planetary science》2016,51(1):105-115

Carbon compounds are ubiquitous in the solar system but are challenging to study using remote sensing due to the mostly bland spectral nature of these species in the traditional visible‐near‐infrared regime. In contrast, carbonaceous species are spectrally active in the ultraviolet (UV) but have largely not been considered for studies of solar system surfaces. We compile existing UV data of carbon compounds—well‐studied in contemplation of the ISM extinction “bump”—to review trends in UV spectral behavior. Thermal and/or irradiation processing of carbon species results in the loss of H and ultimately graphitization. Graphitization is shown to produce distinct spectral features in the UV, which are predicted to be more readily detected in the inner solar system, whereas outer solar system bodies are expected to be more dominated by less‐processed carbon compounds. Throughout the solar system, we can thus consider a “carbon continuum” where the more evolved carbons in the inner solar system exhibit a stronger UV absorption feature and associated far‐UV rise. We compare carbon spectral models with spacecraft data of two bodies from different points in the carbon continuum, Ceres and Iapetus. We find that the apparent strong far‐UV upturn in Ceres’ spectrum (in the 150–200 nm range) can be explained by an anthracite‐like species while Iapetus’ spectrum features a reflectance peak consistent with polycyclic aromatic hydrocarbons. We make generalized predictions for UV spectral characteristics in other regions of the solar system.  相似文献   

Europa’s disk-resolved ultraviolet spectra: Relationships with plasma flux and surface terrains     

Amanda R. Hendrix  Timothy A. Cassidy  Chris Paranicas 《Icarus》2011,212(2):736-743

The full set of high-resolution observations from the Galileo Ultraviolet Spectrometer (UVS) is analyzed to look for spectral trends across the surface of Europa. We provide the first disk-resolved map of the 280 nm SO₂ absorption feature and investigate its relationship with sulfur and electron flux distributions as well as with surface features and relative surface ages. Our results have implications for exogenic and endogenic sources. The large-scale pattern in SO₂ absorption band depth is again shown to be similar to the pattern of sulfur ion implantation, but with strong variations in band depth based on terrain. In particular, the young chaos units show stronger SO₂ absorption bands than expected from the average pattern of sulfur ion flux, suggesting a local source of SO₂ in those regions, or diapiric heating that leads to a sulfur-rich lag deposit.While the SO₂ absorption feature is confined to the trailing hemisphere, the near UV albedo (300-310 nm) has a global pattern with a minimum at the center of the trailing hemisphere and a maximum at the center of the leading hemisphere. The global nature of the albedo pattern is suggestive of an exogenic source, and several possibilities are discussed. Like the SO₂ absorption, the near UV albedo also has local variations that depend on terrain type and age.  相似文献   

Current approaches to MRV in South Africa: a scoping study     

Anya Boyd  Britta Rennkamp  Anthony James Dane  Harald Winkler 《Climate Policy》2013,13(3):397-416

It is shown that there are MRV-related activities underway in South Africa, particularly focusing on measuring electricity consumption and monitoring GHG emissions. Yet currently many of these activities happen in parallel systems within multi-polar governance structures. A bottom-up perspective of MRV in South Africa, informed by interviews, workshops, desktop research, and stakeholder consultations, is provided and the systems, data, methodologies, and the institutional environment relevant to a South African MRV system are examined. The development of the local monitoring and evaluation system, and its relevance within the international MRV context, is also discussed. Some recommendations are made: most importantly, there is a need for a coherent approach to be developed, one that is coordinated by government and built on existing MRV systems.  相似文献