A Study of the Reuse of Reused Water     

Edgar D. Smith  Robert M. Sweazy  George A. Whetstone  R. H. Ramsey 《Ground water》1979,17(4):366-374

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Electron paramagnetic resonance,optical absorption,and magnetic circular dichroism studies of the CO 3 − molecular-ion in irradiated natural beryl     

A. Edgar  E. R. Vance 《Physics and Chemistry of Minerals》1977,1(2):165-178

Room temperature X-irradiation of some natural beryls produced several new absorption lines in the electron paramagnetic resonance (EPR) spectrum, a known series of optical absorption lines in the 500–700 nm range, and a shift of the absorption edge to lower energies. Several of the new EPR lines and part of the irradiation-induced shift of the absorption edge disappeared after a few days at room temperature, and were not examined in detail. However, three of the paramagnetic centres responsible for the new EPR lines were stable at room temperature and two of these have previously been identified as atomic hydrogen and the methyl radical, CH₃. These species were stable to ～150 and ～450°C respectively. The third stable species, hitherto unreported, showed a single-line EPR spectrum of axial symmetry, with g∥=2.0051 and g⊥=2.0152. This spectrum was found to be intensity-correlated with the series of optical bands in the 500–700 nm range, after thermal bleaching at 175°C. The EPR and optical spectra are therefore assigned to the same species. It is argued that this species is the CO ₃ ^? molecular ion, located in the widest part of the structural channel and aligned with the plane of the molecule perpendicular to the c axis. The EPR spectrum is consistent with a ² A′₂ ground state of a CO ₃ ^? molecule with trigonal symmetry, and this requires that the optical transition has a ² A′₂ → ² E′ character. Most of the features in the optical spectrum can be assigned to coupling of a totally symmetric mode of frequency ～1020 cm^?1 onto a zero-phonon line at 14,490 cm^?1 and a second weaker line at 16,020 cm^?1. However, both of these two fundamental lines are structured, and the two components show strong temperature-dependent derivative-shaped magnetic circular dichroism (MCD). Furthermore, the overall sign of the MCD for the line at 16,020 cm^?1 is opposite to that at 14,490 cm^?1. The separation (～120 cm^?1) of the two components of the 14,490 cm^?1 line is much larger than that expected from spin-orbit interaction, and the origin of this splitting is not yet understood.  相似文献   

OPserver: interactive online computations of opacities and radiative accelerations     

C. Mendoza  M. J. Seaton  P. Buerger  A. Bellorín  M. Meléndez †  J. González  L. S. Rodríguez  F. Delahaye  E. Palacios  A. K. Pradhan  C. J. Zeippen 《Monthly notices of the Royal Astronomical Society》2007,378(3):1031-1035

Codes to compute mean opacities and radiative accelerations for arbitrary chemical mixtures using the Opacity Project recently revised data have been restructured in a client–server architecture and transcribed as a subroutine library. This implementation increases efficiency in stellar modelling where element stratification due to diffusion processes is depth dependent, and thus requires repeated fast opacity re-estimates. Three user modes are provided to fit different computing environments, namely, a web browser, a local workstation and a distributed grid.  相似文献   

An experimental self-motion study of the Ocean Explorer AUV incontrolled sea states     

Edgar  P. Smith  S.M. 《Oceanic Engineering, IEEE Journal of》1998,23(3):274-284

This paper describes a controlled self-motion study recently carried out using a small autonomous underwater vehicle (AUV) in a controlled environment in which regular and random waves can be generated accurately for various frequencies and heights. In this study, the AUV was one of the Florida Atlantic University's Ocean Explorer series vehicles, and the controlled environment was chosen to be the Maneuvering And Sea-Keeping (MASK) facilities located at the David Taylor Model Basin. During the entire study, 29 sets of experimental motion and wave data were collected under various wave frequencies and heights, vehicle alignment, and operating depths. Due to the wave tank constraint, the vehicle speed was restricted to be less than 1.5 m/s and the wave frequency higher than 0.3 Hz without significantly affecting the self-motion analysis. Time history and power spectral density results suggest that the roll-induced pitching response was considerably larger for the wave frequencies tested, as compared to the pitch-induced rolling response. Standard deviation results reveal that the existing OEX is capable of producing approximately 3° (peak-to-peak) pitch, 0.7° (peak-to-peak) roll, and 0.6° (peak-to-peak) yaw at 2-m depth in the head-sea condition when the encountering wave frequency is close to 0.4 Hz. However, at 1.5-m vehicle depth, significant surges were observed in pitching and rolling motion, suggesting that the OEX is currently unsuitable to maintain accurate depth-following within this range at sea-state 2 or higher. It is hoped that the results presented can provide better insights into how a small AUV with a nonideal body shape reacts to waves of different sea states, and how vehicle self-motion can be streamlined by choosing proper vehicle speed, heading, and depth, given that the wave characteristics are available  相似文献   

Pixel-based correction for Charge Transfer Inefficiency in the Hubble Space Telescope Advanced Camera for Surveys     

Richard Massey  Chris Stoughton  Alexie Leauthaud  Jason Rhodes  Anton Koekemoer  Richard Ellis  Edgar Shaghoulian 《Monthly notices of the Royal Astronomical Society》2010,401(1):371-384

Charge Transfer Inefficiency (CTI) due to radiation damage above the Earth's atmosphere creates spurious trailing in Hubble Space Telescope ( HST ) images. Radiation damage also creates unrelated warm pixels – but these happen to be perfect for measuring CTI. We model CTI in the Advanced Camera for Surveys (ACS)/Wide Field Channel and construct a physically motivated correction scheme. This operates on raw data, rather than secondary science products, by returning individual electrons to pixels from which they were unintentionally dragged during readout. We apply our correction to images from the HST Cosmic Evolution Survey (COSMOS), successfully reducing the CTI trails by a factor of ∼30 everywhere in the CCD and at all flux levels. We quantify changes in galaxy photometry, astrometry and shape. The remarkable 97 per cent level of correction is more than sufficient to enable a (forthcoming) reanalysis of downstream science products and the collection of larger surveys.  相似文献   

Molecular H₂O in armenite, BaCa₂Al₆Si₉O₃₀·2H₂O, and epididymite, Na₂Be₂Si₆O₁₅·H₂O: Heat capacity, entropy and local-bonding behavior of confined H₂O in microporous silicates     

Charles A. Geiger  Edgar Dachs  Gilberto Artioli 《Geochimica et cosmochimica acta》2010,74(18):5202-5215

Armenite, ideal formula BaCa₂Al₆Si₉O₃₀·2H₂O, and its dehydrated analog BaCa₂Al₆Si₉O₃₀ and epididymite, ideal formula Na₂Be₂Si₆O₁₅·H₂O, and its dehydrated analog Na₂Be₂Si₆O₁₅ were studied by low-temperature relaxation calorimetry between 5 and 300 K to determine the heat capacity, C_p, behavior of their confined H₂O. Differential thermal analysis and thermogravimetry measurements, FTIR spectroscopy, electron microprobe analysis and powder Rietveld refinements were undertaken to characterize the phases and the local environment around the H₂O molecule.The determined structural formula for armenite is Ba_0.88(0.01)Ca_1.99(0.02)Na_0.04(0.01)Al_5.89(0.03)Si_9.12(0.02)O₃₀·2H₂O and for epididymite Na_1.88(0.03)K_0.05(0.004)Na_0.01(0.004)Be_2.02(0.008)Si_6.00(0.01)O₁₅·H₂O. The infrared (IR) spectra give information on the nature of the H₂O molecules in the natural phases via their H₂O stretching and bending vibrations, which in the case of epididymite only could be assigned. The powder X-ray diffraction data show that armenite and its dehydrated analog have similar structures, whereas in the case of epididymite there are structural differences between the natural and dehydrated phases. This is also reflected in the lattice IR mode behavior, as observed for the natural phases and the H₂O-free phases. The standard entropy at 298 K for armenite is S° = 795.7 ± 6.2 J/mol K and its dehydrated analog is S° = 737.0 ± 6.2 J/mol K. For epididymite S° = 425.7 ± 4.1 J/mol K was obtained and its dehydrated analog has S° = 372.5 ± 5.0 J/mol K. The heat capacity and entropy of dehydration at 298 K are Δ = 3.4 J/mol K and ΔS^rxn = 319.1 J/mol K and Δ = −14.3 J/mol K and ΔS^rxn = 135.7 J/mol K for armenite and epididymite, respectively. The H₂O molecules in both phases appear to be ordered. They are held in place via an ion-dipole interaction between the H₂O molecule and a Ca cation in the case of armenite and a Na cation in epididymite and through hydrogen-bonding between the H₂O molecule and oxygen atoms of the respective silicate frameworks. Of the three different H₂O phases ice, liquid water and steam, the C_p behavior of confined H₂O in both armenite and epididymite is most similar to that of ice, but there are differences between the two silicates and from the C_p behavior of ice. Hydrogen-bonding behavior and its relation to the entropy of confined H₂O at 298 K is analyzed for various microporous silicates.The entropy of confined H₂O at 298 K in various silicates increases approximately linearly with increasing average wavenumber of the OH-stretching vibrations. The interpretation is that decreased hydrogen-bonding strength between a H₂O molecule and the silicate framework, as well as weak ion-dipole interactions, results in increased entropy of H₂O. This results in increased amplitudes of external H₂O vibrations, especially translations of the molecule, and they contribute strongly to the entropy of confined H₂O at T < 298 K.  相似文献   

Assessment of RegCM4 simulated inter-annual variability and daily-scale statistics of temperature and precipitation over Mexico     

Ramón Fuentes-Franco  Erika Coppola  Filippo Giorgi  Federico Graef  Edgar G. Pavia 《Climate Dynamics》2014,42(3-4):629-647

The skill of a regional climate model (RegCM4) in capturing the mean patterns, interannual variability and extreme statistics of daily-scale temperature and precipitation events over Mexico is assessed through a comparison of observations and a 27-year long simulation driven by reanalyses of observations covering the Central America CORDEX domain. The analysis also includes the simulation of tropical cyclones. It is found that RegCM4 reproduces adequately the mean spatial patterns of seasonal precipitation and temperature, along with the associated interannual variability characteristics. The main model bias is an overestimation of precipitation in mountainous regions. The 5 and 95 percentiles of daily temperature, as well as the maximum dry spell length are realistically simulated. The simulated distribution of precipitation events as well as the 95 percentile of precipitation shows a wet bias in topographically complex regions. Based on a simple detection method, the model produces realistic tropical cyclone distributions even at its relatively coarse resolution (dx = 50 km), although the number of cyclone days is underestimated over the Pacific and somewhat overestimated over the Atlantic and Caribbean basins. Overall, it is assessed that the performance of RegCM4 over Mexico is of sufficient quality to study not only mean precipitation and temperature patterns, but also higher order climate statistics.  相似文献   

Charles Lyell and the extraordinary publishing history of his works     

Stuart A. Baldwin 《Geology Today》1998,14(3):113-115

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Preface     

D. Graves  A. Edgar 《Mineralogy and Petrology》1994,51(2-4):111-112

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An Analysis of Polar Coronal Hole Evolution: Relations to Other Solar Phenomena and Heliospheric Consequences     

Maravilla  Dolores  Lara  Alejandro  Valdés galicia  José F.  Mendoza  Blanca 《Solar physics》2001,203(1):27-38

We use observations of the green corona low-brightness regions to construct a time series of a polar coronal hole area from 1939 to 1996, covering 5 solar cycles. We then perform a power-spectral analysis of the monthly data time series. Several persistent significant periodicities appear in the spectra, which are related with those found in solar magnetic flux emergence, geomagnetic storm sudden commencements and cosmic-ray flux at Earth. Of particular importance are the peak at around 1.6–1.8 yr recently found in cosmic-ray intensity fluctuations, and the peak at around 1 yr, also identified in coronal hole magnetic flux variations. Additional interesting features are the peaks close to 5 yr, 3 yr and the possible peak at around 30 yr, that were also found in other solar and interplanetary phenomena. Our results stress the physical connection between the solar magnetic flux emergence and the interplanetary medium dynamics, in particular the importance of coronal hole evolution in the structuring of the heliosphere.  相似文献