Detection of the Lower Boundary of Stellar Convective Envelopes from Seismic Data     

Mário J.P.F.G. Monteiro  Jørgen Christensen-Dalsgaard  Michael J. Thompson 《Astrophysics and Space Science》1998,261(1-4):41-42

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A simple model for the adjustment of velocity spectra in unstable conditions downstream of an abrupt change in roughness and heat flux   总被引：1，自引：3，他引：1  

Jørgen Højstrup 《Boundary-Layer Meteorology》1981,21(3):341-356

A simple model for the equilibrium spectra of velocity fluctuations in the unstable surface layer is developed. All three component spectra are written as a sum of two spectra For the horizontal spectra, the two parts scale with % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaacIcacaWGUb% GaamOEamaaBaaaleaacaWGPbaabeaakiaac+cacaWG1bGaaiilaiaa% dQhadaWgaaWcbaGaamyAaaqabaGccaGGVaGaamitaiaacMcaaaa!4232!\[(nz_i /u,z_i /L)\]and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaad6gacaWG6b% Gaai4laiaadwhaaaa!3B5E!\[nz/u\], respectively; the vertical spectrum can be written entirely as a function of % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaad6gacaWG6b% Gaai4laiaadwhaaaa!3B5E!\[nz/u\] and % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqaqpepeea0xe9qqVa0l% b9peea0lb9Lq-JfrVkFHe9peea0dXdarVe0Fb9pgea0xa9W8qr0-vr% 0-viWZqaceaabiGaciaacaqabeaadaqaaqaaaOqaaiaadQhacaGGVa% Gaamitaaaa!3A42!\[z/L\].The equilibrium spectra are utilized as part of a model describing the development of velocity spectra downwind of a change in surface roughness and heat flux.Results are shown for the streamwise component and compared with hotwire measurements from the RISØ 78 experiment. The model shows excellent agreement with the measurements.on leave of absence from RISØ National Laboratory Roskilde, Denmark.  相似文献   

Medium pressure crystallization of a monchiquitic magma — evidence from megacrysts of Drever''s block, Ubekendt Ejland, West Greenland     

Jrgen Gutzon Larsen 《Lithos》1981,14(4):241-262

Megacrysts and polymineralic fragments of extraordinary diversity from a Tertiary monchiquitic dyke of Ubekendt Ejland comprise three groups: (1) Cr-diopside-fassaitic diopside + olivine, Fo_90.5?81.5 + CrAl spinels. (II) Fassaitic salite-ferrisalite + KTi-pargasite-ferropargasite + apatite + AlTi-magnetite, (III) Scapolite + hyalophane + potassium feldspar + nepheline + analcime. By comparison with mineralogy and phase relations in the host rock and experimental data from alkaline rocks the megacrysts are related to a sequence of crystallization from primitive monchiquitic to potassic phonolitic magmas rich in H₂O and CO₂ at 5–11 kb. Group I megacrysts formed at temperatures of 1300-1150°C and group II between ? bar at the latter temperature. High P_co2 may have stabilized the scapolite in the more evolved liquid and K-feldspar and nepheline began to crystallize at ca. 800°C possibly together with the ferrisalite.  相似文献   

Bibliographia Cretacea 6     

Jürgen Schbel 《Cretaceous Research》1981,2(3-4)

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Diskussionsbeitrag zu: „Inhalt und Bedeutung fossiler Bodenkomplexe in Perm und Trias von Mitteleuropa“ von D. Ortlam,Geol. Rdsch.,63, S. 850–884     

Landesgeologe Dr. Hans Jürgen Konrad 《International Journal of Earth Sciences》1975,64(1):993-998

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Unterschiedliche Adaptionsfähigkeit der Fische an Eutrophierung     

Dr. Jürgen Hartmann 《Aquatic Sciences - Research Across Boundaries》1979,41(2):374-382

The succession of yield of fish species in European lakes undergoing cultural eutrophication is described. According to absence or occurrence of yield increase two groups of fishes are distinguished. In few species a stepwise yield increase and intensified yield fluctuations are observed. A decrease of the combinedCoregonus spp. is rarely found in deep lakes. In respect to adaptability to rapid eutrophication. three groups of fishes are distinguished: preadapted fishes, obviously adapting ones, and not obviously adapting ones.   相似文献   

Schallgeschwindigkeit und Impedanz des oberen Meeresbodens in Gebieten der Nordsee,des Skagerraks,des Kattegats und der Ostsee     

Dr. Florian Schirmer  Dr. Bernd Schmalfeldt  Dipl.-Phys. Jürgen Siebert 《Ocean Dynamics》1979,32(6):279-288

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Zur Bildung migmatitischer Schollenamphibolite aus dem Altkristallin des Aarmassivs (Haslital,Schweiz)     

Dr. Jürgen Abrecht 《International Journal of Earth Sciences》1980,69(3):695-725

Zusammenfassung Im Gebiet des Gruben- und des Aerlengletschers im Oberhasli (Zentrales Aarmassiv, Schweiz) ist ein präherzynischer Altkristallinkeil aufgeschlossen, der im N und S vom herzynischen Mittagfluhbzw. Zentralen Aaregranit begrenzt wird. Die Gesteine des zur Nördlichen Schieferhülle zu zählenden Altkristallins umfassen weitgehend Biotit-Plagioklas-Gneise meist migmatitischer Natur mit Amphibolit-Einlagerungen und jüngeren Aplitstöcken, die aber noch prä-aaregranitisches Alter haben. Die Amphibolite sind stark in Schollen zerlegt und von pegmatitischem Substrat umgeben, welches als Produkt von unter Stress mobilisierten Gneisanteilen angesehen wird, die in Zonen niedrigeren Druckes wieder rekristallisierten. Dabei reagierten Amphibolite und Mobilisate, was zur Biotitisierung der Amphibole führte. Der Chemismus der neu entstandenen Biotite widerspiegelt den Chemismus der umgewandelten Amphibole und unterscheidet sich von demjenigen der Biotite aus den umliegenden Gneisen. Die Plagioklase des pegmatitischen Neosoms sind durch die Zufuhr des bei der Biotitisierung der Amphibole freigewordenen Calciums etwas An-reicher geworden als diejenigen aus den Biotit-Plagioklas-Gneisen.Das Alter der Schollen- und Pegmatitbildung ist zumindest frühherzynisch.

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In the Gruben- and Aerlengletscher area in the Oberhasli region (Aar massif, Switzerland) a wedge-shaped zone of prehercynian rocks exists, bordered by the hercynian Mittagfluh granite in the N and the hercynian Aar granite in the S. The rocks of this zone consist of migmatitic biotite-plagioclase-gneisses with amphibolitic inclusions and younger aplitic intrusions of pre-granitic age. The amphibolites are broken, having an agmatite structure, and are surrounded by coarse-grained plagioclase-quartz material. From petrographic and geochemical evidences it is assumed that these pegmatites consist of material that has been solved under stress in the gneisses and has recrystallized in zones of lower pressure. By reaction between pegmatitic neosome and amphibolites the amphiboles were transformed into biotites, whose compositions depend on the composition of the amphiboles. These newly-formed biotites are also of a different composition than the biotites from the gneisses. By assimilation of the calcium that was released from the amphiboles by the biotitization, the neosome plagioclases are slightly richer in anorthite than the plagioclases in the gneisses.The migmatitization, e. g. the formation of pegmatitic neosome, is at least of early hercynian age.

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Résumé Dans la région du Grubengletscher et de l'Aerlengletscher dans la vallée de l'Oberhasli (massif de l'Aar, Suisse) un coin de cristallin ancien pré-hercynien est bordé par le granite du Mittagfluh au N et par le granite de l'Aar au S. Cette zone consiste surtout en gneiss à biotite-plagioclase de nature migmatitique avec des inclusions amphibolitiques et de petites intrusions aplitiques d'âge pré-granitique. Les amphibolites ont une structure agmatitique et sont entourées de néosome pegmatitique. Ces pegmatites sont probablement le produit du matériel mobilisé dans les gneiss sous pression et recristallisé dans des zones à pression réduite. Ce matériel a réagi avec les inclusions amphibolitiques dont les amphiboles ont été biotitisées. D'après les nombreuses analyses effectuées à la microsonde, la composition des biotites formées de cette manière reflète celle des amphiboles originelles et se différencie de celle des biotites des gneiss environnants. Ayant assimilé du calcium libéré par la biotitisation des amphiboles, les plagioclases des néosomes pegmatitiques ont une composition un peu plus basique que ceux provenant des gneiss. La formation des structures agmatitiques et des pegmatites date au moins du début de la métamorphose hercynienne.

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Oberhasli, ( , ) - , Mittagfluh, . - , - . - - , , , , . , . . — — , . , - , - .

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Risø 1978: Further investigations into the effects of local terrain irregularities on tower-measured wind profiles     

Ernest W. Peterson  Peter A. Taylor  Jørgen Højstrup  Niels Otto Jensen  Leif Kristensen  Erik L. Petersen 《Boundary-Layer Meteorology》1980,19(3):303-313

Observations of flow over complex terrain taken at Risø during June–July 1978 and numerical studies confirm earlier findings that small variations in surface elevation have significant effects on mean wind profiles. Measured shear stresses in the nonequilibrium region of the flow are consistent with theory but quite different from those obtained assuming simple flux-profile relationships. These findings imply that flux-profile relationships can be quite complicated over other than simple homogeneous terrain.  相似文献   

An effect of closure on the structure of principal components   总被引：2，自引：0，他引：2  

Felix Chayes  Jürgen Trochimczyk 《Mathematical Geology》1978,10(4):323-333

The principal components transformation generates, from any data array, a new set of variables—the scores of the components—characterized by a total variance exactly equal to that of the initial set. It is in this sense that the transformed variables are said to contain, preserve, or account for, the variance of the original set. The scores, however, are uncorrelated. In the course of the transformation, what becomes of the strong interdependence of variance and covariance so characteristic of closed arrays? The question seems to have attracted little attention; we are aware of no study of it in the earth sciences. Experimental work reported here shows quite clearly that the overall equivalence of variance and covariance imposed by closure, though absent from the component scores,may emerge in relations between the coefficientsof each of the lower-order components; if the raw data are complete rock analyses, the sum of all the covariances of the coefficients of such a component is negative, and is very nearly equal to the sum of all the variances in absolute value. (In all cases so far examined, the absolute value of the first sum is a little less than that of the second.) The principal components transformation provides an elegant escape from closure correlation if a petrographic problem can be restated entirely in terms of component scores, but not if a physical interpretation of the component vectors is required.  相似文献