Nonlinear adaptive regression predictors based on singular decomposition     

Jan John  Josef Štekl 《Studia Geophysica et Geodaetica》1990,34(4):369-378

Summary The paper deals with a non-linear regression model, linear in parameters. The least-squares adaptation method has been used to determine the model parameters. The conditionality problem in solving equations, which follows from the dependent predictors, has been suppressed by singular decomposition. This model is especially suitable for treating meteorological problems because non-linear processes, e.g. changes of air masses, changes of circulation patterns, etc., can be treated. The model has been tested in connection with the forecast of daily maximum and minimum temperatures. The RMS error lies in the range of 1–2°C, if the principal PPM is supposed.

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Резюме Оnuсывеamся мamемamuческuŭ annaрam нелuнеŭноŭ ре?rt;рессuонноŭ мо?rt;елu, лuнеŭноŭ оmнос umельно naрaмеmров. Для оnре?rt;еленuя naрaмеmров мо?rt;елu uсnользуеmся меmо?rt; нauменьщuх квa?rt;рamов. Плохaя обусловленносmь сuсmемы нauменьщuх квa?rt;рamов, коmорaя вызвaнa взauмноŭ зaвuсuмосmью nре?rt;uкmоров, всmрaняеmся nрu nомощu сuн?rt;улярноŭ ?rt;екомnозuцuu. Эma мо?rt;ель nо?rt;хо?rt;um ?rt;ля nрuмененuя в меmеороло?rt;uu, maк кaк онa nозволяеm рaбоmamь с нелuнеŭносmямu, кaк нanрuмер uзмененuе воз?rt;ущных мaсс, uзмененuе хaрaкmерa цuркуляцuu u m. n. Мо?rt;ель nроверяеmся нa nро?rt;нозе ?rt;невных мuнuмaльных u мaксuмaльных mемnерamур. Сре?rt;няя квa?rt;рamuческaя ошuбкa нaхо?rt;umся в uнmе?rt;рaле оm 1 ?rt;о 2° (uсnользовaн nрuнцun РРМ).

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On the kinetics of textural equilibration in forsterite marbles     

Marian B. Holness  M. J. Bickle  Colin M. Graham 《Contributions to Mineralogy and Petrology》1991,108(3):356-367

In the aureole of the Beinn an Dubhaich granite, Skye, the minimum observed median forsterite-calcite-calcite dihedral angle varies from 110° at the olivinein isograd to about 165° (the equilibrium value) at the granite-limestone contact. Laboratory experiments were performed to investigate the kinetics of this textural change. It was found that the rate of change of the forsterite-calcite-calcite dihedral angle followed approximately first-order kinetics with an activation energy of 48±4 kJ mol^-1 for fluid-present conditions, and 90 ±4 kJ mol^-1 for fluid-absent conditions. Scanning ion imaging demonstrated that, at least in the early stages of textural change, solution-reprecipitation of the calcite was the rate determining step in the fluid-present runs. The latter result and the value of the activation energy are both consistent with the activation energy found by previous authors for (albeit zeroth order) silicate-aqueous solution solution-reprecipitation reactions. The value of activation energy for the dry data does not correspond to those for either grain boundary or volume diffusion of oxygen or magnesium in forsterite. The mechanism for textural equilibration in the fluid-absent runs is uncertain. Application of the experimentally-derived rate equation to the Beinn an Dubhaich marbles gave activation energies higher than those obtained experimentally. It is concluded from consideration of grain growth effects that activation energies derived from the Beinn an Dubhaich marbles probably reflect textural equilibration under predominantly fluid-absent conditions.  相似文献   

Compositional changes of minerals associated with dynamic recrystallizatin     

Richard A. Yund  Jan Tullis 《Contributions to Mineralogy and Petrology》1991,108(3):346-355

The rate of compositional and isotopic exchange between minerals may be enhanced significantly if the rock is deformed simultaneously. The enhanced exchange rate may result from a reduction in grain size (shorter distance for volume diffusion), dissolution and growth of grains by diffusion creep (pressure solution), or the movement of high-angle grain boundaries through strained grains during recrystallization in the dislocation creep regime. The migration of high-angle grain boundaries provides high diffusivity paths for the rapid exchange of components during recrystallization. The operation of the latter process has been demonstrated by deforming aggregates consisting of two plagioclases (An₁ and An₇₉) at 900°C, 1 GPa confining pressure, and a strain rate of ∼2x10^-6s^-1. The polygonal, recrystallized grains were analyzed using an analytical transmission electron microscope and have a variable but often intermediate composition. At the conditions of these experiments, the volume interdiffusion rate of NaSi/CaAl is too slow to produce any observable chemical change, and microstructural-chemical relations indicate that the contribution from diffusion creep was insignificant except for initially fine-grained (2–10 μm) aggregates. These results indicate that strain-induced recrystallization can be an effective mechanism for enhancing the kinetics of metamorphic reactions and for resetting the isotope systematics of minerals such as feldspars, pyroxenes, and amphiboles.  相似文献   

Effects of the IMF pro- and anti-sectors in the winter midlatitude ionosphere     

Jan Laštovička  Reviewer L. Křívský 《Studia Geophysica et Geodaetica》1985,29(1):101-104

Summary On the basis of the 1966–73 data, the effect of the difference between pro- and anti-sectors of the IMF is found to be negligible in the winter midlatitude (Central Europe) ionosphere contrary to the dominant effect of this difference in the high-latitude ionosphere found earlier.

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a ¶rt;a a 1966–73. u¶rt;m u m amu ¶rt; pro- u anti- mau . na a u ¶rt;um (¶rt; na) u, , a naa a, naum um u.

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Increased levels of petroleum hydrocarbons in the surface sediments of Swedish coastal waters     

Jan Mattsson  Carola Lehtinen 《Marine pollution bulletin》1985,16(10):390-395

Petroleum hydrocarbons in the sediments of the Bothnian Bay, Baltic proper, Öresund, Kattegatt and Skagerrak were analysed in a survey of oil pollution along the Swedish coast in 1974 and 1975. Sixty-one of these sediment stations were revisited in 1982 and analysed with the methods used in the first survey. The mean content of petroleum hydrocarbons (paraffin-naphthene fraction) in the sediment surface showed a statistically significant increase from 199 to 252 μg g^?1 dry wt. The main increase had taken place in the coastal areas. Within 0–20 km distance of urbanized areas (>20 000 inhabitants) petroleum hydrocarbons had increased from 371 to 447 μg g^?1. Sediment levels increased from 76 to 117 μg g^?1, 20–50 km from urbanized areas. The increase in these areas was equivalent to 0.119 g m^?2 yr^?1.  相似文献   

H-chondrites: Trace element clues to their origin     

John W. Morgan  Marie-Josée Janssens  H. Takahashi  Jan Hertogen  Edward Anders 《Geochimica et cosmochimica acta》1985,49(1):247-259

We have analyzed 10 H-chondrites for 20 trace elements, using RNAA. The meteorites included 4 of petrologic type 4 and 2 each of types 3, 5 and 6.The data show that H-chondrites are not isochemical. H3's are depleted by some 10% not only in Fe (Dodd, 1976), but also in the siderophiles Os, Re, Ir, Ni, Pd, Au, and Ge. Moreover, the abundance pattern of siderophiles varies systematically with petrologic type. As similar fractionations of REE have been observed by Nakamura (1974), it appears that both the proportions and compositions of the main nebular condensates varied slightly during accretion of the H-chondrites. Thus the higher petrologic types are independent nebular products, not metamorphosed descendants of lower petrologic types.Abundances of highly volatile elements (Cs, Br, Bi, Tl, In, Cd, Ar³⁶) correlate with petrologic type, declining by ≤ 10^?3 from Type 3 to Type 6. The trends differ from those for artificially heated Type 3's (Ikramuddinet al., 1977b; Herzoget al., 1979), but agree passably with theoretical curves for nebular condensation. Apparently the low volatile contents of higher petrologic types are a primary feature, not the result of metamorphic loss.The mineralogy of chondrites suggests that they accreted between 405 K (absence of Fe₃O₄) and 560 K (presence of FeS), and the abundances of Tl, Bi, and In further restrict this interval to 420–500 K. Accretion at 1070 ± 100 K, as proposed by Hutchisonet al. (1979, 1980), leads to some extraordinary problems. Volatiles must be injected into the parent body after cooling, which requires permeation of the body by 10¹¹ times its volume of nebular gas. This process must also achieve a uniform distribution of the less volatile elements (Rb, Cu, Ag, Zn, Ga, Ge, Sn, Sb, Se, F), without freezeout in the colder outer layers.Factor analysis of our data shows 3 groupings: siderophiles (Os, Re, Ir, Ni, Pd, Au, and Ge), volatiles (Ag, Br, In, Cd, Bi, and Tl) and alkalis (Rb and Cs). The remaining 5 elements (U, Zn, Te, Se, and Sb) remain unassociated.  相似文献   

Microlaboratory study on magnetic,gravity and high-tension separation of hercynite and pleonaste from low-grade ilmenite concentrates     

Jan Drzymala  Andrzej łuszczkiewicz 《International Journal of Mineral Processing》1985,14(3):233-238

Some ilmenite concentrates obtained from oleate flotation of ilmenite ores from NE Poland contain less than the required 45% TiO₂ due to the presence of green spinels (hercynite and pleonaste). Such concentrates were further upgraded by different separation techniques. It was established at microlaboratory scale that magnetic, gravity and high-tension separations can provide qualified ilmenite concentrates with TiO₂ recovery in the order of 50 to 80%.  相似文献   

Aminostratigraphy of European marine interglacial deposits     

Gifford H. Miller  Jan Mangerud 《Quaternary Science Reviews》1985,4(4):215-278

Molluscan fossils collected from shallow water marine sediment across NW Europe and nearby Arctic regions have been analysed for the extent of isoleucine epimerization ( ratio) in indigenous protein residues. The ratios confirm that essentially all ‘classical’ Eemian sites from NW Europe are of the same age, and are correlative with the type locality near Amersfoort in the Netherlands; shells from interglacial marine sediment beneath the type Weichselian till in Poland also correlate with the type Eemian site. ratios in Holsteinian marine shells (0.29) are substantially higher than in their Eemian counterparts (0.17); ‘Late Cromerian’ shells yield even higher ratios (0.46). ratios in late glacial shells (0.06) and Middle Weichselian shells (0.09) permit differentiation from modern (0.01) and last interglacial material. Based on the position of the Matuyama-Brunhes boundary and the differences in ratios, the Eemian must correlate with isotope substage 5e, whereas the Holsteinian is most likely substage 7c, possibly stage 9 but certainly younger than stage 11. Intra-Saalian warm periods may be terrestrial equivalents of the younger substages of stage 7. Extensive pre-Eemian marine sediments along the SW coast of Denmark previously correlated with the Holsteinian are shown to be of ‘Late Cromerian’ age. The underlying till there is the first widespread evidence of a pre-Elsterian till in NW Europe. ratios in molluscs from last interglacial sites along the Arctic coast of the USSR, the Arctic Islands and eastern Greenland are substantially lower than in their European counterparts due to their low thermal histories. The combined mid- and high-latitude data are used to develop a predictive model for the expected ratio in any of several moderate epimerization-rate taxa for last interglacial sites with mean temperatures between −20 and +15°C.Not all sites could be unambiguously assigned to an established interglacial. The Fjøsanger (Norway) and Margareteberg (Sweden) sites previously thought to be Eemian, yield ratios higher than in secure nearby Eemian material. It is yet unresolved whether these are aberrant sites or if they predate the last interglacial. In situ shoreline deposits encountered in borings in SW Belgium and in exposures on the Belgium coastal plain contain molluscs that yield ratios intermediate between secure Eemian and Late Weichselian ratios, raising the possibility that a late stage 5 high-sea-level event attained near-modern levels in the southern North Sea basin. Resolution of these uncertainties is the focus of future work.  相似文献   

Magnetic susceptibility anisotropy of deformed rocks     

Aleš Kapička  Reviewer F. Janák 《Studia Geophysica et Geodaetica》1984,28(1):90-100

¶rt;au uu aum nuuumu u aumnuu ¶rt; aa aam n¶rt; am amuu u namuu ¶rt;au. amu uu aumnuu nuuumu, a amu ¶rt;au, m ¶rt;mu au ma nma aaumu m¶rt; ¶rt;a, m a amu uu aum m mnu n¶rt;u ¶rt; mm uaum amua n¶rt; ¶rt;au. u aumnuu nu a namu ¶rt;auu(<1%) a uuu m nuuumu _i uaum amua. u aumnuu ¶rt;mu uu uum aauuau ¶rt;ua am m uu, m, m ¶rt; u au namu ¶rt;auu.  相似文献   

Some possibilities of predicting radio wave absorption in the lower ionosphere     

Josef Boška  Jan Laštovička  Reviewer L. Křivský 《Studia Geophysica et Geodaetica》1986,30(1):87-92

Summary An attempt is made to show possible ways of predicting radio wave absorption in the midlatitude lower ionosphere using relations between absorption and the intensity of solar ionizing radiation and/or common solar activity indices, and between absorption and f₀F2.

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aa mu nuau nu a¶rt;u ¶rt;um u u a mu ¶rt; nu u umum uuu uu (uu uu u¶rt;au amumu) u ¶rt; nu u f₀F2.

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