Aerial Photography for Survey Purposes with a High Resolution, Small Format, Digital Camera     

J. P. Mills  I. Newton  & R. W. Graham 《The Photogrammetric Record》1996,15(88):575-587

This paper discusses the work carried out to obtain stereoscopic "photography" from airborne platforms with a Kodak DCS200 digital camera, as part of an investigation into the suitability of current digital camera technology for use in air survey. Details of the work, from the initial test flight in a Cessna light aircraft through to tests utilizing a Thruster microlight platform, are documented. The paper concludes with a summary of the present shortcomings in obtaining aerial photography for survey purposes with still video technology and discusses the future prospects.  相似文献   

Helium isotope geochemistry of mid-ocean ridge basalts from the South Atlantic     

David W. Graham  William J. Jenkins  Jean-Guy Schilling  Geoffrey Thompson  Mark D. Kurz  Susan E. Humphris 《Earth and Planetary Science Letters》1992,110(1-4):133-147

We report new helium isotope results for 49 basalt glass samples from the Mid-Atlantic Ridge between 1°N and 47°S.³He/⁴He in South Atlantic mid-ocean ridge basalts (MORB) varies between 6.5 and 9.0 R_A (R_A is the atmospheric ratio of1.39 × 10⁻⁶), encompassing the range of previously reported values for MORB erupted away from high³He/⁴He hotspots such as Iceland. He, Sr and Pb isotopes show systematic relationships along the ridge axis. The ridge axis is segmented with respect to geochemical variations, and local spike-like anomalies in³He/⁴He, Pb and Sr isotopes, and trace element ratios such as(La/Sm)_N are prevalent at the latitudes of the islands of St. Helena, Tristan da Cunha and Gough to the east of the ridge. The isotope systematics are consistent with injection beneath the ridge of mantle “blobs” enriched in radiogenic He, Pb and Sr, derived from off-axis hotspot sources. The variability in³He/⁴He along the ridge can be used to refine the hotspot source-migrating-ridge sink model.

MORB from the 2–7°S segment are systematically the least radiogenic samples found along the mid-ocean ridge system to date. Here the depleted mantle source is characterized by⁸⁷Sr/⁸⁶Sr of 0.7022, Pb isotopes close to the geochron and with²⁰⁶Pb/²⁰⁴Pb of 17.7, and³He/⁴He of 8.6–8.9 R_A. The “background contamination” of the subridge mantle, by radiogenic helium derived from off-ridge hotspots, displays a maximum between 20 and 24°S. The HePb and HeSr isotope relations along the ridge indicate that the³He/⁴He ratios are lower for the hotspot sources of St. Helena, Tristan da Cunha and Gough than for the MORB source, consistent with direct measurements of³He/⁴He ratios in the island lavas. Details of the HeSrPb isotope systematics between 12 and 22°S are consistent with early, widespread dispersion of the St. Helena plume into the asthenosphere, probably during flattening of the plume head beneath the thick lithosphere prior to continental breakup. The geographical variation in theHe/Pbratio deduced from the isotope systematics suggests only minor degassing of the plume during this stage. Subsequently, it appears that the plume component reaching the mid-Atlantic ridge was partially outgassed of He during off-ridge hotspot volcanism and related melting activity.

Overall, the similar behavior of He and Pb isotopes along the ridge indicates that the respective mantle sources have evolved under conditions which produced related He and Pb isotope variations.  相似文献   

Some rock magnetic properties of mid-Cretaceous basalts from Israel and India (Rajmahal traps), and their bearing on palaeointensity experiments     

Graham J. Sherwood 《Physics of the Earth and Planetary Interiors》1992,70(3-4):237-242

A wide range of rock magnetic properties have been determined from two collections of mid-Cretaceous basalts; one from Israel, the other from the Rajmahal traps in northeast India. Deuteric oxidation is rare in both collections, with titanium-rich titanomagnetite being the principal remanence carrier in most cases. There are a number of differences in rock magnetic properties between the two groups. Some of these seem to be primary, whereas others appear to be caused by hydrothermal alteration and weathering, which are more prevalent in the Indian rocks. These rocks are being used in palaeointensity experiments, from which it is hoped to determine the strength of the Earth's magnetic field during the long period of normal polarity in the mid-Cretaceous. Thellier palaeointensity experiments have been performed on two samples from each site. The degree of agreement between the two results is highly variable. The low blocking temperatures and the presence of secondary viscous components in many samples make Thellier palaeointensity experiments very difficult. A further problem is that of thermal alteration, two main types of which are observed. The first manifests itself as a large and sudden increase in partial thermoremanent magnetization (pTRM) capacity, and the second as a steady decrease in the size of pTRM with increasing temperature.  相似文献   

Helium isotopes in some historical lavas from Mount Vesuvius     

D.W. Graham  P. Allard  C.R.J. Kilburn  F.J. Spera  J.E. Lupton   《Journal of Volcanology and Geothermal Research》1993,58(1-4)

³He/⁴He ratios in lavas erupted during the last 360 years at Mt. Vesuvius are between 2.2 and 2.7 R_A (R_A = atmospheric ratio of 1.39 × 10⁻⁶), and are among the lowest values measured in young volcanic rocks. They are also identical to values measured in summit crater fumaroles sampled during 1987–1991. This agreement indicates that the ³He/⁴He ratio in the crater fumaroles faithfully tracks the magmatic value. The relatively low and uniform ³He/⁴He ratio in the lavas reflects either a mantle source enriched in (U + Th)/³He, or a mixture of magmatic and crustal components.  相似文献   

A design study of an energy-dissipating cladding system     

Julie Mark Cohen  Graham H. Powell 《地震工程与结构动力学》1993,22(7):617-632

A design study has been conducted to explore the use of structural cladding panels with energy-dissipating cladding-to-frame connections for seismic-resistant design. The study identifies several issues involved in the modelling and analysis of frames with energy-dissipating cladding-to-frame connections, establishes concepts for design, and provides a preliminary assessment of the force and deformation demands that are likely to be placed on panels and connections. Non-linear dynamic analyses indicate that the clad frames perform well, based on observations about maximum interstorey drifts, maximum plastic hinge rotations in the frames, and maximum ductility demands on the cladding-to-frame connections.  相似文献   

Glaciotectonic structures and their relation to topography at Dinas Dinlle,Arvon, northwest Wales     

Charles Harris  Peter J. Brabham  Graham D. Williams 《第四纪科学杂志》1995,10(4):397-397

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The opacity of some local Martian dust storms observed by the Viking IRTM     

Garry E. Hunt  Elizabeth A. Mitchell  Alan R. Peterfreund 《Icarus》1980,41(3):389-399

In this paper we analyze some Viking infrared thermal mapping (IRTM) measurements of local Martian dust storms observed in the southern tropical region of the planet between L_s=225 and 262°. The derived opacities of these storms show that in the most opaque regions of the cloud, the optical thickness may be ≈6. Away from the individual clouds, the opacity is ≈2, which is still about four times the background level of dustiness in the Martian atmosphere. We find considerable structure in the derived opacity which will create corresponding variations in the atmospheric heating, which in turn may have an important feedback upon the local winds.  相似文献   

THE METEORITICAL SOCIETY     

A.L. Graham 《Meteoritics & planetary science》1980,15(1):93-103

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Cryostorage of hepatic microsomes from two marine mammal species: effects on cytochrome P450-monooxygenase activities and content     

Tilley RE  Kemp GD  Hall AJ 《Marine pollution bulletin》2003,46(5):654-658

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Impacts of the Jessica oil spill: an introduction     

Edgar GJ  Snell HL  Lougheed LW 《Marine pollution bulletin》2003,47(7-8):273-275

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