Microstructures of High-grade Metamorpbic Rocks at Broken Hill, Australia     

VERNON  R. H. 《Journal of Petrology》1968,9(1):1-22

Frequency distributions of true interfacial angles in high-grade,regional metamorphic rocks from Broken Hill indicate that interfacialtension varies with relative crystallographic orientation incommon minerals. In some single-phase aggregates (e.g. quartz,feldspar, garnet, and calcite) the grains are equant and polygonal,anisotropy of interfacial tension having only a small effecton the appearance of such aggregates. This is also true of two-phaseaggregates of these phases, but their appearance is complicatedby the presence of inclusions, the relative proportions of ihephases, and the characteristic dihedral angle formed by a grainof one phase in contact with two grains of the other. In phases for which interfacial tension is more orientation-dependent,crystal forms exert some control on the appearance of the microstructure.For example, in hornblende and pyroxene aggregates, some interfacesare parallel to planes of the form {110}, although most areirrational. In still more anisotropic phases, low-energy forms(e.g. {001} of biotite and {110} of sillimanite) are very stable,giving rise to a predominance of planar, rational boundariesover curved, adjustment boundaries. Anisotropy of interfacial tension is expressed in the shapesof inclusions. However, even where strongly anisotropic mineralsare involved, inclusions with partly planar boundaries occuralongside inclusions with completely curved boundaries.  相似文献   

Canterbury Landscapes: a Study in Contrasts     

Jane M. Soons 《New Zealand geographer》1968,24(2):115-132

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GEOGRAPHIC ACTIVITIES OF THE DIVISION OF EARTH SCIENCES,NATIONAL RESEARCH COUNCIL     

Walter H. Bailey 《The Professional geographer》1968,20(4):272-275

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THE COMPUTATION OF SINGLE STRIPS IN PLAN     

E. H. Thompson 《The Photogrammetric Record》1967,5(29):385-396

This paper discusses a simple method of computing independent strips under certain reasonable approximations. It is shown that, if the method is regarded as if it were computation by polynomials, the order of the polynomial is decided by the nature of the control provided and not by the number of controlled models. This conclusion should throw some light on the vexed (and perennial) problem of the choice of orders for polynomials.  相似文献   

ANALYTICAL AERIAL TRIANGULATION BLOCK ADJUSTMENT; THE DIRECT HEIGHT SOLUTION INCORPORATING TIE-STRIPS     

A. D. N. Smith    M. J. Miles  P. Verrall 《The Photogrammetric Record》1967,5(29):327-350

The historical development of analytical aerial triangulation block adjustment is mentioned by way of introduction. The advantages of separating the plan and height adjustments are given and the observation equations of a typical adjustment section are analysed to show that this convenient practice is justified in normal circumstances. The principles of a direct solution of the normal equations suitable for a moderate-sized computer, are explained and developed in detail for the height adjustment. The advantages of tie-strips in the height adjustment are demonstrated and the difficulties which then arise are discussed. An approximate method which overcomes these difficulties is developed. Details of the computer programmes used are given in Appendix B.  相似文献   

Buchbesprechungen     

F. Steinhauser  W. Mörikofer  K. Cehak 《Theoretical and Applied Climatology》1967,15(3):313-328

Ohne Zusammenfassung  相似文献   

Buchbesprechungen     

F. Steinhauser  O. Burkard  W. Mörikofer  M. Toperczer 《Meteorology and Atmospheric Physics》1962,13(2):290-304

Ohne Zusammenfassung  相似文献   

On the basic principles of geophysical radioactive measurements     

P. Márton  L. Stegena 《Pure and Applied Geophysics》1962,53(1):55-64

Summary The process of radon diffusion in space and time through rocks is treated in detail from the point of view of radiometric prospecting for oil. Taking into account the depth and diffusivity conditions encountered in nature it is stated that vertical radon diffusion reaching from the oil deposits up to the surface cannot be expected. Time intervals as required for setting in of a stationary concentration state and decay conditions of the radon lead to the conclusion that the penetration of emanometric measurements seldom exceeds the depth of 5–10 m.  相似文献   

Magnetic pinch in relation to the lightning stroke     

W. H. Evans 《Pure and Applied Geophysics》1962,52(1):162-168

Summary The application of the snow plow approximation to the magnetic pinch effect in the return stroke of lightning is described. Results are presented for a constant electric field and for a measured stroke current. In general, the solutions indicate that the magnetic pinch effect is important for cases of high currents, small channel diameters, and low degrees of ionization.  相似文献   

Prediction of the field strength fading forms by means of weather situations     

M. A. Anastassiades  L. N. Carapiperis  N. K. Kariambas  P. G. Paraskevopoulos 《Pure and Applied Geophysics》1962,52(1):143-152

Summary In this study the different forms of the electromagnetic field strength recordings at the Thera-Crete microwave line of link are examined, in comparison with the corresponding weather situations prevailing over that area. According to the amplitude of fluctuations, the different forms of recordings have been classified in three basic typesA, B, C and the annual frequency of the appearance of these types has been observed. Finally, the influence of weather situations on radio wave propagation was examined and it has been found that in most cases a close relationship exists between weather situations and the different fading forms of the electromagnetic field so that a prediction of the fading form be possible by means of the weather forecast.This study was sponsored by a research grant from NATO's Scientific Committee.  相似文献