Detection of dispersive signals using multitaper dual-frequency coherence     

Robert Mellors  Frank Vernon  & David Thomson 《Geophysical Journal International》1998,135(1):146-154

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The race is not to the swift     

Megan K Pickett  rew J Lim 《Astronomy& Geophysics》2004,45(1):1.12-1.17

Megan K Pickett and Andrew J Lim examine the role of spirals in protoplanetary disks and the formation of gas giant planets, and find that slower may be better than faster, if planets are to endure.  相似文献   

Estimating site-specific strong earthquake motions     

F. Heuze  R. Archuleta  F. Bonilla  S. Day  M. Doroudian  A. Elgamal  S. Gonzales  M. Hoehler  T. Lai  D. Lavallee  B. Lawrence  P. -C. Liu  A. Martin  L. Matesic  B. Minster  R. Mellors  D. Oglesby  S. Park  M. Riemer  J. Steidl  F. Vernon  M. Vucetic  J. Wagoner  Z. Yang 《Soil Dynamics and Earthquake Engineering》2004,24(3):199-223

The Campus Earthquake Program (CEP) of the University of California (UC) started in March 1996, and involved a partnership among seven campuses of the UC—Berkeley, Davis, Los Angeles, Riverside, San Diego, Santa Barbara, Santa Cruz—and the Lawrence Livermore National Laboratory (LLNL). The aim of the CEP was to provide University campuses with site-specific assessments of their earthquake strong motion exposure, to complement estimates they obtain from consultants according to the state-of-the-practice (SOP), i.e. Building Codes (UBC 97, IBC 2000), and Probabilistic Seismic Hazard Analysis (PSHA). The Building Codes are highly simplified tools, while the more sophisticated PSHA is still somewhat generic in its approach because it usually draws from many earthquakes not necessarily related to the faults threatening the site under study.Between 1996 and 2001, the site-specific studies focused on three campuses: Riverside, San Diego, and Santa Barbara. Each campus selected 1–3 sites to demonstrate the methods and procedures used by the CEP: Rivera Library and Parking Lots (PL) 13 and 16 at UCR, Thornton Hospital, the Cancer Center, and PL 601 at UCSD, and Engineering I building at UCSB. The project provided an estimate of strong ground motions at each selected site, for selected earthquake scenarios. These estimates were obtained by using an integrated geological, seismological, geophysical, and geotechnical approach, that brings together the capabilities of campus and laboratory personnel. Most of the site-specific results are also applicable to risk evaluation of other sites on the respective campuses.The CEP studies have provided a critical assessment of whether existing campus seismic design bases are appropriate. Generally speaking, the current assumptions are not acknowledging the severity of the majority of expected motions. Eventually, both the results from the SOP and from the CEP should be analyzed, to arrive at decisions concerning the design-basis for buildings on UC campuses.  相似文献   

The status of sea bass (Dicentrarchus labrax) stocks around England and Wales, derived using a separable catch-at-age model, and implications for fisheries management     

Pawson  Mike G.; Kupschus  Sven; Pickett  Graham D. 《ICES Journal of Marine Science》2007,64(2):346-356

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THE POTENTIAL IMPLEMENTATION OF BIOGEOCHEMICAL CYCLES IN BIOGEOGRAPHY     

Vernon Meentemeyer  Wallace Elton 《The Professional geographer》1977,29(3):266-271

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The teaching of geology in schools: Report of a discussion held on 5th April, 1946     

Vernon Wilson  Francis Jones  J.I. Platt  G. Van Praagh  A.E. Trueman  M.E. Tomlinson  M.M. Sweeting  S.G. Harries  F.E. Clegg  A.G. Lowndes  K.A. Joysey  F.J. North  H.E. Dudley  R.O. Jones  A.K. Wells  L.J. Chubb  W.B. West  H.J.W. Brown  A.H. Gunner 《Proceedings of the Geologists' Association. Geologists' Association》1947,58(1):1-44

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Statistical Insights Regarding Fully Softened Shear Strength     

Trinidad Gonz&#;lez  Yuderka  Schaefer  Vernon R.  Rollins  Derrick K. 《Geotechnical and Geological Engineering》2021,39(2):1155-1171

The fully softened shear strength (FSS) concept is a practical approximation of the mobilized drained shear strength of first-time slides in stiff-fissured clays. There has been a recent increase in interest in measurement and estimation of FSS secant friction angle (FSS-ϕ′sec) to develop correlations for preliminary design and cost approximation. However, such correlations do not help in understanding the cause and effect relationship between soil properties and FSS-ϕ′sec. In this study, a laboratory database containing FSS-ϕ′sec values (output) and soil properties (inputs) of several overconsolidated clays is used to develop a predictive model for FSS-ϕ′sec (output or response). The goal is to detect which inputs from the whole parameter space dominate the response while creating an accurate prediction tool to provide statistical insights regarding the FSS-ϕ′sec. The proposed methodology is used to assess and quantify the relationships among variables, estimate testing device effects on FSS-ϕ′sec, and analyze the danger of extrapolation due to model constraints. The applicability of the predicted FSS-ϕ′sec is also evaluated and compared. Recommendations regarding the studied prediction tools for slope stability design in stiff-fissured clays are provided.

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Review of Microstructural Evidence of Magmatic and Solid-State Flow   总被引：13，自引：0，他引：13  

R.H. Vernon 《Visual Geosciences》2000,5(2):1-23

Evidence of magmatic flow includes: (a) parallel to sub-parallel alignment of elongate euhedral crystals (e.g., of feldspar or hornblende) that are not internally deformed, (b) imbrication (‘tiling’) of elongate euhedral crystals that are not internally deformed, (c) insufficient solid-state strain in regions between aligned or imbricated crystals to accommodate phenocryst rotation, (d) elongation of microgranitoid enclaves without plastic deformation of the minerals, (e) magmatic flow foliations and elongate microgranitoid enclaves deflected around xenoliths, and (f) schlieren layering (if due to flow sorting) in the absence of plastic deformation of the minerals involved. These features are consistent with rotation of crystals in a much weaker medium, namely a melt phase, at a stage when the magma has become viscous enough to preserve the alignment.Evidence of solid-state flow includes: (a) internal deformation and recrystallization of grains, (b) recrystallized “tails,” (c) elongation of recrystallized aggregates (e.g. of quartz and mica), (d) grainsize reduction, (e) fine-grained folia anastomosing around less deformed relics, (f) microcline twinning, (g) myrmekite, (h) flame perthite, (i) boudinage of strong minerals, typically with recrystallized aggregates of weaker minerals (e.g. quartz and mica) between the boudins, (j) foliation passing through, rather than around enclaves, and (k) heterogeneous strain with local mylonitic zones.Several criteria suggest “submagmatic flow,” including recrystallized feldspar, inferred transitions from magmatic imbrication to solid-state S/C arrangements, evidence of c-slip in quartz, and especially evidence of migration of residual melt into lower-pressure sites.Recent experimental studies indicate that a change from grain-supported flow to suspension flow typically occurs in deforming magmas at melt contents of between 20% to 40%, and that large amounts of strain may accumulate in magmas without being recorded by the final fabric. At lower melt percentages, perhaps as low as a few percent, depending on the minerals and their shapes, strain may be accommodated by: (a) melt-assisted grain-boundary sliding, (b) contact-melting assisted grain-boundary migration, (c) strain partitioning into melt-rich zones, (d) intracrystalline plastic deformation (c-slip in quartz indicating plastic deformation at temperatures near the granite solidus), and (f) transfer of melt to sites of low mean stress. The only indication of strain in the absence of crystal plasticity may be an alignment of crystals. Moreover, magmatic flow microstructures may be destroyed by fracturing, crystal plasticity and recrystallization before the magma reaches its solidus.Many rocks show evidence of solid-state flow superimposed on magmatic flow. Evidence of magmatic flow is commonly preserved in deformed felsic metamorphic rocks: for example the alignment of rectangular K-feldspar megacrysts and of microgranitoid enclaves. However, absence of alignment does not preclude a magmatic origin for K-feldspar megacrysts in felsic gneisses, as magmatic flow may cease before the magma becomes viscous enough to preserve an alignment.  相似文献   

Correlation of the lower devonian rocks of australasia     

D. L. Strusz with contribution by M. R. Banks  G. Bischoff  B. J. Cooper  R. A. Cooper  P. G. Flood  E. D. Gill  J. S. Jell  J. W. Pickett  N. M. Savage  D. L. Sherwin  J. A. Talent  B. D. Webby & A. J. Wright 《Australian Journal of Earth Sciences》2013,60(4):427-455

Alkali basaltic rocks from the Southern Highlands, N.S.W., contain oxide phases of both high and low pressure origin. The two phases are readily distinguished using chemical and textural criteria.

Chemical data for low‐pressure Fe‐Ti oxides indicate that oxygen fugacities of the host lavas range from 10‐^12.8 to 10‐⁸ atm at 950° to 1110°C. In most cases, the oxygen fugacities of the individual lava flows appear to be principally a function of temperature and intrinsic chemical equilibria existing at the time of formation of the basaltic liquid. However, some relatively differentiated flows shows a high degree of oxidation due to volatile enrichment with fractionation. Rare glassy flows show dendritic crystallization of Fe‐Ti oxides. Most flows in which abundant olivine was the first phase to be precipitated also contain Cr‐rich spinels associated, and apparently coeval, with the earliest‐crystallizing olivine.  相似文献   

Polar observations of plasma waves in and near the dayside magnetopause/magnetosheath     

J.D. Menietti  J.S. Pickett  G.B. Hospodarsky  J.D. Scudder  D.A. Gurnett 《Planetary and Space Science》2004,52(14):1321-1337

The plasma wave instrument (PWI) on board the Polar spacecraft made numerous passages of the dayside magnetopause and several probable encounters with the magnetosheath during the years 1996 and 1997. During periods of relatively high density, the PWI antenna-receiver system is coupled to the plasma and oscillates. The oscillations have been shown (cf. Radio Sci. 36 (2001) 203) to be indicative of periods of higher plasma density and plasma flows, possibly associated with magnetic reconnection. We have studied the plasma waves observed on three distinct magnetopause passes distinguished by the presence of these oscillations of the PWI receivers, and we report on the data obtained near, but not during, the times of the oscillations and the possible role of these waves in magnetic reconnection. Sweep-frequency receiver and high-resolution waveform data for some of these times are presented. The plasma wave measurements on each of the passes are characterized by turbulence. The most stable waves are whistler mode emissions typically of several hundred hertz that are seen intermittently in these regions. The data indicate the presence of impulsive solitary-like wave structures with strong electric fields both parallel and perpendicular to the magnetic field near, but not always within, suspected reconnection sites. The solitary waves show the highest occurrence when observed with electrostatic electron cyclotron waves. These latter waves have been observed in the past in the cusp, polar magnetosphere, and auroral regions and therefore may represent excursions into the cusp, but also indicate the presence of low-energy electron beams. Turbulence near the lower hybrid frequency, low-frequency EM waves, and impulsive monopolar electrostatic pulses are seen throughout the magnetopause and particularly near regions of large decrease in the local magnetic field and enhanced field-aligned flows, the suspected reconnection sites. The absence of significant solitary wave signatures within suspected reconnection sites may require modifications to some reconnection models.  相似文献