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11.
12.
Helmut Moritz 《Journal of Geodesy》1987,61(1):21-40
The paper treats the problem of averaging two independent determinations of the same function (curve, surface, etc.). Starting from the simple arithmetic mean, the problem is successively generalized to scalar and vector functions, arriving at an integral equation of Wiener-Hopf type. Aspects of least-squares collocation are also included. Finally the problem of determining transformation parameters and other systematic deviations is treated, furnishing a simple example of continuous least-squares adjustment. 相似文献
13.
14.
Peter Baccini Erwin Grieder Ruth Stierli Sabine Goldberg 《Aquatic Sciences - Research Across Boundaries》1982,44(1):99-116
The adsorption characteristics of sediment particles from a prealpine Swiss lake were compared with those of γ-aluminum oxide.
Under lake water conditions, i.e. with particle concentration of 2–16 mg/1 and DOC concentrations of 1–4 mg/1 at pH=8, the
adsorption of copper, zinc and orthophosphate is reduced significantly by the presence of natural organic matter (NOM). It
is postulated that the binding sites of the natural mineral surfaces are occupied almost completely by NOM under natural conditions.
A simple ligand exchange model can explain the observed phenomena. 相似文献
15.
The location requirements for emergency callers outside urban areas can hardly be fulfilled without global navigation satellite
systems (GNSS). Consequently, interest in positioning techniques based on use of a GNSS such as GPS or on the cellular network
infrastructure itself is growing rapidly in the mobile-telephone community. Moreover, the increasing demand for commercial
location-based services (LBS) has driven cellular-phone and network manufacturers to focus on positioning solutions which
are even more accurate than the regulatory mandates for positioning of emergency callers. One example of these upcoming LBS
is our PARAMOUNT project, which aims at improving user-friendly info-mobility services for hikers and mountaineers by combining
wireless communications (GMTS), satellite navigation (GNSS) and geographic information systems (GIS), based on a mobile client/server
architecture. The availability of mobile phones or PDAs with combined GNSS and cellular network-based wireless communication
on a high integration level is one primary demand of such LBS applications. Based on this, we will give some initial answers
to the question of whether mobile handset architecture synergies exist for the combination of GNSS with wireless location
in CDMA cellular wireless networks. In order to identify synergies, we will outline similarities and differences between wireless
communication and satellite navigation. In this respect, we pay particular attention to the so-called RAKE receiver architecture
employed in mobile CDMA cellular handsets. Our initial investigations will show that the RAKE receiver architecture, on which
mobile CDMA cellular handsets are based, will most likely be the one most suitable for achieving synergies between the two
positioning techniques within the same mobile handset architecture. Consequently, several receiver components could be used
to handle both types of signals (navigation and communications), resulting in a reduction of manufacturing costs and in a
decrease in energy consumption.
Electronic Publication 相似文献
16.
Erwin Nickel 《Contributions to Mineralogy and Petrology》1947,1(1):117-120
Zusammenfassung Das Periklingesetz verlangt Spiegelsymmetrie in der Zone senkrecht [010]; die kristallographische Symmetrie wiederholt sich in der Lage der Indikatrizen. Die Einmessung zeigt aber, daß (trotz normaler Verwachsung nach dem rhombischen Schnitt) die Symmetrie der verzwillingten Indikatrizen verringert ist: die (theoretische)ZE fungiert nur als Halbierungsebene der korrespondierten Mittellinien, die volle Symmetrie wird nicht verwirklicht. In unserem Falle ist die eingelagerte Zwillingspartie in bezug auf dieZE korrekter orientiert als das Hauptindividuum. - Die Konstruktion derZE nachBEREK führt auch bei der verminderten Symmetrie der verzwillingten Indikatrizen zur Auffindung der morphologisch definierten Zwillingsachse. -Man wird eben nicht vergessen dürfen, daß die Zwillingsgesetze Idealformulierungen sind, denen die Wirklichkeit nicht immer gerecht wird. 相似文献
17.
Constraining the process by which volcanoes become unstable is difficult. Several models have been proposed to explain the
driving forces which cause volcanic edifices to catastrophically collapse. These include models for destabilisation of volcanic
flanks by wedging due to dyke intrusion and the weakening of mechanical properties by pressurisation of pore fluids. It is
not known which, if any, of the models are relevant to particular sector collapse events. Recent developments in the palaeomagnetic
estimation of emplacement temperatures of volcaniclastic rocks have shown that even relatively low emplacement temperatures
can be recorded by volcaniclastics with high fidelity. We have carried out a palaeomagnetic study of emplacement temperatures
to investigate the role of igneous activity in the initiation of the 9,500 b.p. Murimotu sector collapse of Mt Ruapehu, New Zealand. This debris avalanche deposit has three fades which are stratigraphically
superimposed, and the lowermost fades contains three lithological assemblages representing different segments of the edifice
which were transported with little internal mixing within the flow. We have determined that some of the dacite-bearing assemblage
1, fades 1 was hot (∼350 °C) during transport and emplacement, whereas none of the other lithological assemblages of fades
contained hot material. Our interpretation is that a dacite dome was active on the ancient Ruapehu edifice immediately prior
to the Murimotu sector collapse. The partially cooled carapace of the dome and material shed from this part was incorporated
into the avalanche deposit, along with cold lavas and volcaniclastics. We have not found evidence for incorporation of material
at or close to magmatic temperatures, at least in the sampled locations. Our palaeomagnetic work allows us to develop a comprehensive,
new palaeomagnetic classification of volcaniclastics.
Published online: 25 January 2003
Editorial responsibility: D. Dingwell 相似文献
18.
Florian Einsiedl Norbert Hertkorn Moritz Frommberger Boris P. Koch 《Geochimica et cosmochimica acta》2007,71(22):5474-5482
The study of molecular transformation processes of dissolved organic carbon (DOC) in the environment significantly contributes to a better understanding of the global biogeochemical organic matter cycle. In an oxic karst groundwater system, in which the most powerful abiotic DOC degradative reactions, photodegradation and metal-mediated redox chemistry, are at best marginal contributors, a near complete turnover of fulvic acids (FAs) has been observed within decades (∼60 years). Depletion of oxygen for a very extensive range of aliphatic and aromatic carbon chemical environments has been confirmed as well as the formation of novel classes of compounds, suggesting a major contribution from biotic processes. From these results we infer that FAs must be perceived as a rather active participant in the global carbon cycle. Molecular-level alterations of such magnitude and rapidity on such short-time scales ought to be considered as widespread in the processing of “refractory” DOC in the environment. 相似文献
19.
Forest conditions in Europe have been monitored over 20 years jointly by the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) and the European Union (EU). Maps for mean bulk SO4, NO3 and NH4 deposition at around 400 intensive monitoring plots in the years 1999–2001, as well as time trends for the period 1996–2001, are presented. Mean bulk SO4 deposition at 169 plots mostly located in central Europe decreased from 7.4 to 5.8 kgS ha−1 a−1. Mean NH4 bulk deposition decreased from 6.2 to 5.3 kgN ha−1 a−1. Nitrate bulk deposition fluctuated around 5 kgN ha−1 a−1. On average, throughfall deposition was considerably higher than bulk deposition. Time trends for mean tree crown defoliation as an overall indicator for forest condition show a peak in the mid 1990s for most of the monitored main tree species and a recent increase for the years 2003 and 2004. Multivariate linear regression analyses show some significant relations between deposition and defoliation. These relations depend on the tree species and site characteristics. Effects of deposition are moderated by the influence of biotic stress factors such as insects and fungi and by abiotic stress factors, such as weather. 相似文献
20.
The Chelopech deposit is one of the largest European gold deposits and is located 60 km east of Sofia, within the northern
part of the Panagyurishte mineral district. It lies within the Banat–Srednegorie metallogenic belt, which extends from Romania
through Serbia to Bulgaria. The magmatic rocks define a typical calc-alkaline suite. The magmatic rocks surrounding the Chelopech
deposit have been affected by propylitic, quartz–sericite, and advanced argillic alteration, but the igneous textures have
been preserved. Alteration processes have resulted in leaching of Na2O, CaO, P2O5, and Sr and enrichment in K2O and Rb. Trace element variation diagrams are typical of subduction-related volcanism, with negative anomalies in high field
strength elements (HFSE) and light element, lithophile elements. HFSE and rare earth elements were relatively immobile during
the hydrothermal alteration related to ore formation. Based on immobile element classification diagrams, the magmatic rocks
are andesitic to dacitic in compositions. Single zircon grains, from three different magmatic rocks spanning the time of the
Chelopech magmatism, were dated by high-precision U–Pb geochronology. Zircons of an altered andesitic body, which has been
thrust over the deposit, yield a concordant 206Pb/238U age of 92.21 ± 0.21 Ma. This age is interpreted as the crystallization age and the maximum age for magmatism at Chelopech.
Zircon analyses of a dacitic dome-like body, which crops out to the north of the Chelopech deposit, give a mean 206Pb/238U age of 91.95 ± 0.28 Ma. Zircons of the andesitic hypabyssal body hosting the high-sulfidation mineralization and overprinted
by hydrothermal alteration give a concordant 206Pb/238U age of 91.45 ± 0.15 Ma. This age is interpreted as the intrusion age of the andesite and as the maximum age of the Chelopech
epithermal high-sulfidation deposit. 176Hf/177Hf isotope ratios of zircons from the Chelopech magmatic rocks, together with published data on the Chelopech area and the
about 92-Ma-old Elatsite porphyry–Cu deposit, suggest two different magma sources in the Chelopech–Elatsite magmatic area.
Magmatic rocks associated with the Elatsite porphyry–Cu deposit and the dacitic dome-like body north of Chelopech are characterized
by zircons with ɛHfT90 values of ∼5, which suggest an important input of mantle-derived magma. Some zircons display lower ɛHfT90 values, as low as −6, and correlate with increasing 206Pb/238U ages up to about 350 Ma, suggesting assimilation of basement rocks during magmatism. In contrast, zircon grains in andesitic
rocks from Chelopech are characterized by homogeneous 176Hf/177Hf isotope ratios with ɛHfT90 values of ∼1 and suggest a homogeneous mixed crust–mantle magma source. We conclude that the Elatsite porphyry–Cu and the
Chelopech high-sulfidation epithermal deposits were formed within a very short time span and could be partly contemporaneous.
However, they are related to two distinct upper crustal magmatic reservoirs, and they cannot be considered as a genetically
paired porphyry–Cu and high-sulfidation epithermal related to a single magmatic–hydrothermal system centered on the same intrusion. 相似文献