The origin of the Kuiper Belt high-inclination population     

Rodney S Gomes 《Icarus》2003,161(2):404-418

I simulate the orbital evolution of the four major planets and a massive primordial planetesimal disk composed of 10⁴ objects, which perturb the planets but not themselves. As Neptune migrates by energy and angular momentum exchange with the planetesimals, a large number of primordial Neptune-scattered objects are formed. These objects may experience secular, Kozai, and mean motion resonances that induce temporary decrease of their eccentricities. Because planets are migrating, some planetesimals can escape those resonances while in a low-eccentricity incursion, thus avoiding the return path to Neptune close encounter dynamics. In the end, this mechanism produces stable orbits with high inclination and moderate eccentricities. The population so formed together with the objects coming from the classical resonance sweeping process, originates a bimodal distribution for the Kuiper Belt orbits. The inclinations obtained by the simulations can attain values above 30° and their distribution resembles a debiased distribution for the high-inclination population coming from the real classical Kuiper Belt.  相似文献   

The H i detection of low column density clouds and galaxies     

Suzanne M. Linder  Robert F. Minchin  Jonathan I. Davies  Maarten Baes  Rhodri Evans  Sarah Roberts  Sabina Sabatini  Rodney Smith 《Monthly notices of the Royal Astronomical Society》2004,353(1):201-210

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THE FILTERING-DOWN PROCESS: INDUSTRIAL LOCATION IN A NONMETROPOLITAN AREA*     

Rodney A. Erickson 《The Professional geographer》1976,28(3):254-260

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The origin of TNO 2004 XR₁₉₀ as a primordial scattered object     

Rodney S. Gomes 《Icarus》2011,215(2):661-668

Numerical integrations of the equations of motion of the giant planets and scattering particles show that there is a possible orbital itinerary that a particle may follow from a scattering mode up to a stable position near the orbit of 2004 XR₁₉₀. This orbital evolution requires that the particle gets trapped in a mean motion resonance with Neptune coupled with the Kozai resonance. Imposing migration on Neptune while a particle is experiencing both resonances can entail an escape from resonance at a low particle’s eccentricity. This eccentricity and the associated inclination are always similar to those of 2004 XR₁₉₀. I conclude that 2004 XR₁₉₀ was most likely a scattered object that went through those resonance processes and was eventually deposited at its current position. By the same argument, it is expected that there must exist several other objects with similar semimajor axis, eccentricity and inclination as those of 2004 XR₁₉₀.  相似文献   

Some Characteristics of the Ionospheric Behavior During the Solar Cycle 23 – 24 Minimum     

Eduardo A. Araujo-Pradere  Rob Redmon  Mariangel Fedrizzi  Rodney Viereck  Tim J. Fuller-Rowell 《Solar physics》2011,274(1-2):439-456

The Solar Cycle 23?–?24 minimum has been considered unusually deep and complex. In this article we study the ionospheric behavior during this minimum, and we have found that, although observable, the ionosphere response is minor and marginally exceeds the range of normal geophysical variability of the system. Two main ionospheric parameters have been studied: vertical TEC (vTEC, total electron content) and NmF2 (peak concentration of the F region). While vTEC showed a consistent modest decrease of the mean value, NmF2 behavior was less clear, with instances where the mean value for the minimum 23?–?24 was even higher that for the minimum 22?–?23. More extensive work is required to gain a better understanding of the ionospheric behavior under conditions similar to those presented in the last minimum.  相似文献   

Extreme Ultraviolet Variability Experiment (EVE) on?the?Solar Dynamics Observatory (SDO): Overview?of?Science Objectives, Instrument Design, Data?Products, and Model Developments     

T. N. Woods  F. G. Eparvier  R. Hock  A. R. Jones  D. Woodraska  D. Judge  L. Didkovsky  J. Lean  J. Mariska  H. Warren  D. McMullin  P. Chamberlin  G. Berthiaume  S. Bailey  T. Fuller-Rowell  J. Sojka  W. K. Tobiska  R. Viereck 《Solar physics》2012,275(1-2):115-143

The highly variable solar extreme ultraviolet (EUV) radiation is the major energy input to the Earth’s upper atmosphere, strongly impacting the geospace environment, affecting satellite operations, communications, and navigation. The Extreme ultraviolet Variability Experiment (EVE) onboard the NASA Solar Dynamics Observatory (SDO) will measure the solar EUV irradiance from 0.1 to 105?nm with unprecedented spectral resolution (0.1?nm), temporal cadence (ten seconds), and accuracy (20%). EVE includes several irradiance instruments: The Multiple EUV Grating Spectrographs (MEGS)-A is a grazing-incidence spectrograph that measures the solar EUV irradiance in the 5 to 37?nm range with 0.1-nm resolution, and the MEGS-B is a normal-incidence, dual-pass spectrograph that measures the solar EUV irradiance in the 35 to 105?nm range with 0.1-nm resolution. To provide MEGS in-flight calibration, the EUV SpectroPhotometer (ESP) measures the solar EUV irradiance in broadbands between 0.1 and 39?nm, and a MEGS-Photometer measures the Sun’s bright hydrogen emission at 121.6?nm. The EVE data products include a near real-time space-weather product (Level?0C), which provides the solar EUV irradiance in specific bands and also spectra in 0.1-nm intervals with a cadence of one minute and with a time delay of less than 15?minutes. The EVE higher-level products are Level?2 with the solar EUV irradiance at higher time cadence (0.25?seconds for photometers and ten seconds for spectrographs) and Level?3 with averages of the solar irradiance over a day and over each one-hour period. The EVE team also plans to advance existing models of solar EUV irradiance and to operationally use the EVE measurements in models of Earth’s ionosphere and thermosphere. Improved understanding of the evolution of solar flares and extending the various models to incorporate solar flare events are high priorities for the EVE team.  相似文献   

A Large-Scale Retrospective Ground Water Monitoring Study for Metolachlor     

Paul H. Roux  K. Balu  Rodney Bennett 《Ground Water Monitoring & Remediation》1991,11(3):104-114

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ELA-ICP-MS U–Pb zircon geochronology of regional volcanism hosting the Bajo de la Alumbrera Cu–Au deposit: implications for porphyry-related mineralization     

Anthony?C.?HarrisEmail author  Charlotte?M.?Allen  Scott?E.?Bryan  Ian?H.?Campbell  Rodney?J.?Holcombe  J.?Michael?Palin 《Mineralium Deposita》2004,39(1):46-67

ELA-ICP-MS U–Pb zircon geochronology has been used to show that the porphyritic intrusions related to the formation of the Bajo de la Alumbrera porphyry Cu–Au deposit, NW Argentina, are cogenetic with stratigraphically well-constrained volcanic and volcaniclastic rocks of the Late Miocene Farallón Negro Volcanic Complex. Zircon geochronology for intrusions in this deposit and the host volcanic sequence show that multiple mineralized porphyries were emplaced in a volcanic complex that developed over 1.5 million years. Volcanism occurred in a multi-vent volcanic complex in a siliciclastic intermontane basin. The complex evolved from early mafic-intermediate effusive phases to a later silicic explosive phase associated with mafic intrusions. Zircons from the basal mafic-intermediate lavas have ages that range from 8.46±0.14 to 7.94±0.27 Ma. Regionally extensive silicic explosive volcanism occurred at ~8.0 Ma (8.05±0.13 and 7.96±0.11 Ma), which is co-temporal with intrusion of the earliest mineralized porphyries at Bajo de la Alumbrera (8.02±0.14 and 7.98±0.14 Ma). Regional uplift and erosion followed during which the magmatic-hydrothermal system was probably unroofed. Shortly thereafter, dacitic lava domes were extruded (7.95±0.17 Ma) and rhyolitic diatremes (7.79±0.13 Ma) deposited thick tuff blankets across the region. Emplacement of large intermediate composition stocks occurred at 7.37±0.22 Ma, shortly before renewed magmatism occurred at Bajo de la Alumbrera (7.10±0.07 Ma). The latest porphyry intrusive event is temporally associated with new ore-bearing magmatic-hydrothermal fluids. Other dacitic intrusions are associated with subeconomic deposits that formed synchronously with the mineralized porphyries at Bajo de la Alumbrera. However, their emplacement continued (from 7.10± 0.06 to 6.93±0.07 Ma) after the final intrusion at Bajo de al Alumbrera. Regional volcanism had ceased by 6.8 Ma (6.92±0.07 Ma). The brief history of the volcanic complex hosting the Bajo de la Alumbrera Cu–Au deposit differs from that of other Andean provinces hosting porphyry deposits. For example, at the El Salvador porphyry copper district in Chile, magmatism related to Cu mineralization was episodic in regional igneous activity that occurred over tens of millions of years. Bajo de la Alumbrera resulted from the superposition of multiple porphyry-related hydrothermal systems, temporally separated by a million years. It appears that the metal budget in porphyry ore deposits is not simply a function of their longevity and/or the superposition of multiple porphyry systems. Nor is it a function of the duration of the associated cycle of magmatism. Instead, the timing of processes operating in the parental magma body is the controlling factor in the formation of a fertile porphyry-related ore system.Electronic Supplementary Material Electronic supplementary material to this paper can be obtained by using the Springer Link server located at Editorial handling: N. White  相似文献   

The use of tracers to assess leakage from the sequestration of CO₂ in a depleted oil reservoir,New Mexico,USA     

Arthur W. Wells  J. Rodney Diehl  Grant Bromhal  Brian R. Strazisar  Thomas H. Wilson  Curt M. White 《Applied Geochemistry》2007

Geological sequestration of CO₂ in depleted oil reservoirs is a potentially useful strategy for greenhouse gas management and can be combined with enhanced oil recovery. Development of methods to estimate CO₂ leakage rates is essential to assure that storage objectives are being met at sequestration facilities. Perfluorocarbon tracers (PFTs) were added as three 12 h slugs at about one week intervals during the injection of 2090 tons of CO₂ into the West Pearl Queen (WPQ) depleted oil formation, sequestration pilot study site located in SE New Mexico. The CO₂ was injected into the Permian Queen Formation. Leakage was monitored in soil–gas using a matrix of 40 capillary adsorbent tubes (CATs) left in the soil for periods ranging from days to months. The tracers, perfluoro-1,2-dimethylcyclohexane (PDCH), perfluorotrimethylcyclohexane (PTCH) and perfluorodimethylcyclobutane (PDCB), were analyzed using thermal desorption, and gas chromatography with electron capture detection. Monitoring was designed to look for immediate leakage, such as at the injection well bore and at nearby wells, and to develop the technology to estimate overall CO₂ leak rates based on the use of PFTs. Tracers were detected in soil–gas at the monitoring sites 50 m from the injection well within days of injection. Tracers continued to escape over the following years. Leakage appears to have emanated from the vicinity of the injection well in a radial pattern to about 100 m and in directional patterns to 300 m. Leakage rates were estimated for the 3 tracers from each of the 4 sets of CATs in place following the start of CO₂ injection. Leakage was fairly uniform during this period. As a first approximation, the CO₂ leak rate was estimated at about 0.0085% of the total CO₂ sequestered per annum.  相似文献   

4D technology: where are we,and where are we going?     

Rodney Calvert 《Geophysical Prospecting》2005,53(2):161-171

4D reservoir monitoring is now becoming established as a normal part of business in some companies, in some regions such as the North Sea, and for some applications, such as thermally enhanced oil recovery. Some spectacular technical successes have been reported, mostly in monitoring water floods. We are beginning to understand how to acquire and process surveys to achieve good results. There is still, however, much to improve in how we use 4D technology to capture its potential value in field management and still some way to go in the tool itself, to make it faster, cheaper and more sensitive to small production effects.  相似文献