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1.
R. T. Schilizzi W. Aldrich B. Anderson A. Bos R. M. Campbell J. Canaris R. Cappallo J. L. Casse A. Cattani J. Goodman H. J. van Langevelde A. Maccafferri R. Millenaar R. G. Noble F. Olnon S. M. Parsley C. Phillips S. V. Pogrebenko D. Smythe A. Szomoru H. Verkouter A. R. Whitney 《Experimental Astronomy》2001,12(1):49-67
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A closed-form first-order perturbation solution for the attitude evolution of a triaxial space object in an elliptical orbit is presented. The solution, derived using the Lie–Deprit method, takes into account gravity-gradient torque and is facilitated by an assumption of fast rotation of the object. The formulation builds on the earlier implementation of Lara and Ferrer, which assumes a circular orbit. The previously presented work—which assumes spin about an object’s axis of maximum inertia—is further extended by the explicit presentation of the transformations required to apply the solution to an object spinning about its axis of minimum inertia. Additionally, several numerical analyses are presented to more completely assess the utility of the solution. These studies (1) validate the elliptical solution, (2) assess the impact of varying the small parameter of the perturbation procedure, (3) analyze the assumption of fast rotation, and (4) apply the solution to the common and important scenario of a tumbling rocket body. 相似文献
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The results of a research study of the carbon monoxide concentration from California to 90° S, Antarctica are presented. The data both extend and support other research studies of the latitudinal distribution of carbon monoxide in that higher concentrations are evident over the Northern Hemisphere than over the Southern Hemisphere. Carbon monoxide concentrations range between 50 to 60 ppb with a few peaks into the 60s in the latitudinal area south of the ITCZ and values of 80 ppb or higher at latitudes north of Hawaii. A comparison is also made of carbon monoxide and ozone concentrations along the flight tract between California and Antarctica, over the Ellsworth Mountains of Antarctica, and between 78° S and the South Pole. These ozone-carbon monoxide data show statistically significant negative correlations in the upper troposphere and lower stratosphere over Antarctica. It is believed that this is a good indication of mixing across the tropopause. 相似文献
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John Cushing Marla Daily Elmer Noble V. Louise Roth Adrian Wenner 《Quaternary Research》1984,21(3):376-384
Mammoth remains on Santa Cruz Island, one of the four Northern Channel Islands of California, are very sparse, in marked contrast to those reported from Santa Rosa and San Miguel Islands of the same island group. A probable major reason for this scarcity is that Quaternary deposits are greatly restricted on Santa Cruz Island. It is proposed, contrary to popular opinion, that fossils found on Santa Cruz Island were derived from animals which died on the island, and were not transported there by humans. Reasons for this conclusion are that the size and geological context of the fossils are similar to those of the largest mammoth fossils of Santa Rosa Island, and that, in spite of extensive investigations by many persons, mammoth remains have not been found in middens, either on the islands or on the adjacent mainland. 相似文献
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Effects of stem density upon sediment retention by salt marsh cord grass,Spartina alterniflora loisel 总被引:1,自引:0,他引:1
Mark L. Gleason Deborah A. Elmer Natalie C. Pien John S. Fisher 《Estuaries and Coasts》1979,2(4):271-273
A laboratory experiment was conducted to determine whether retention of waterborne sand by salt marsh cordgrass, Spartina alterniflora Loisel, is directly related to the number of stems per unit area. Waves generated in a trough washed over a sloping beach planted with S. alterniflora sprigs: a range of stem densities (0–108 stems/m2) was examined in separate trials. The amount of sand accumulated after 60 waves is a positive nonlinear function of stem density. The greatest accretion coincided with the highest stem density tested. Shape of the beach profile was also strongly influenced by the number of stems per m2. 相似文献
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Donald Charles Noble Edward Farrar Edwin John Cobbing 《Earth and Planetary Science Letters》1979,45(1):80-86
The Nazca Group, exposed east of Nazca, Peru, consists of a lower part composed of conglomerate and finer-grained clastic strata and an upper part made up of at least seven ash-flow sheets (cooling units or ignimbrites), collectively known as the Nazca Tuff. These tuffs were erupted between about 22 and 18 m.y. ago from a vent area in the vicinity of Pampa Galeras now marked by a collapse caldera. The early Miocene age of the Nazca Tuff provides additional evidence for a major pulse of largely pyroclastic felsic volcanism throughout the central Andes during the early Miocene. Recognition of the Pampa Galeras caldera supports the idea that many of these rocks were erupted from vent areas of the collapse-caldera type located near the eastern margin of the Coastal batholith.The Nazca Group overlies a major erosional surface cut on the Coastal batholith and its envelope that can be traced southward to the Chilean border. This surface is a continuation of the post-Incaic erosional surface to the north, which is overlain by conglomerate and radiometrically dated volcanic rock of late Eocene age. The post-Incaic surface therefore represents a major episode of regional uplift and pedimentation that followed early Tertiary orogeny. The absence of volcanic rocks of late Eocene/early Oligocene age overlying the Coastal batholith near Nazca and in southern Peru may reflect a general absence of post-Incaic volcanism in this portion of the Andes possibly related to differences in the angle of subduction and/or restriction of volcanic and volcaniclastic rocks of this age to depositional basins east of the batholith. 相似文献