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101.
A. A. Tretyakov K. E. Degtyarev E. B. Salnikova K. N. Shatagin A. B. Kotov I. V. Anisimova Yu. V. Plotkina 《Doklady Earth Sciences》2017,473(2):411-415
The crystallization age of Zhaunkar granites (829 ± 10 Ma) was determined by U–Pb zircon dating. Taking into account the data obtained earlier on the granite age (791 ± 7 Ma) in the Aktas Complex and the syenite age (673 ± 2 Ma) in the Karsakpai Complex, the Ulutau sialic massif is assumed to be composed of three igneous complexes formed during the Tonian–Cryogenian periods of the Neoproterozoic. 相似文献
102.
K. Salonen 《洁净——土壤、空气、水》1979,7(6):591-597
The rate of oxidation of different organic matters varied greatly at combustion temperatures lower than 800 °C. While some materials were oxidized rapidly, others produced peaks with extremely long tails which were difficult to integrate accurately. At 550 °C, where calcium carbonate still remained intact, the determination of carbon consumed much more time and yielded a poorer accuracy when compared with combustion at 950°C. Above 550 °C calcium carbonate decomposes and produces peaks which overlap with those of organic carbon. An accurate correction for carbonate in the results of organic carbon analysis cannot thus be established, in practice, and separate determinations of total and inorganic carbon should be carried out, organic carbon being obtained by subtraction. To achieve the most accurate results the use of 950… 1000°C is recommended for the determination of both total, and carbonate, carbon. 相似文献
103.
104.
K. Andrée 《International Journal of Earth Sciences》1921,11(5-6):235-249
Ohne Zusammenfassung 相似文献
105.
Monitoring litter interception of rainfall using leaf wetness sensor under controlled and field conditions 总被引:2,自引:0,他引:2 下载免费PDF全文
Leaf litter interception of water is an integral component of the water budget for some vegetated ecosystems. However, loss of rainfall to litter receives considerably less attention than canopy interception due to lack of suitable sensors to measure changes in litter water content. In this study, a commercially available leaf wetness sensor was calibrated to the gravimetric water content of eastern redcedar (Juniperus virginiana ) litter and used to estimate litter interception in a subhumid eastern redcedar woodland in north‐central Oklahoma. Under controlled laboratory conditions, a strong positive correlation between the leaf wetness sensor output voltage (mV) and measured gravimetric litter water content (? g) was determined: ? g = (.0009 × mV2) ? (0.14 × mV) ? 11.41 (R 2 = .94, p < .0001). This relationship was validated with field sampling and the output voltage (mV) accounted for 48% of the observed variance in the measured water content. The maximum and minimum interception storage capacity ranged between 1.16 and 12.04 and 1.12 and 9.62 mm, respectively. The maximum and minimum amount of intercepted rain was positively correlated to rainfall amount and intensity. The continuous field measurements demonstrated that eastern redcedar litter intercepted approximately 8% of the gross rainfall that fell between December 16, 2014 and May 31, 2015. Therefore, rainfall loss to litter can constitute a substantial component of the annual water budget. Long‐term in situ measurement of litter interception loss is necessary to gain a better estimate of water availability for streamflow and recharge. This is critical to manage water resources in the south‐central Great Plains, USA where grasslands are rapidly being transformed to woodland or woody dominated savanna. 相似文献
106.
K. Cehak 《Meteorology and Atmospheric Physics》1963,13(3-4):343-359
Zusammenfassung Es werden Gleichungen abgeleitet, mittels derer man aus dem Energiespektrum des Windes die Häufigkeit von Böen bestimmter Größe und bestimmter Mindestgröße, die Größe der häufigsten Böenspitze und einen mittleren Abstand zwischen zwei Böenstößen berechnen kann. Die Theorie wird an einem Beispiel erläutert.
Mit 4 Textabbildungen 相似文献
Summary Equations are derived which allow the calculation of frequencies of gusts with a velocity equal or larger than a given amount, of the velocity of the most frequent gust, and of a mean interval between two gusts out of the power-spectrum of wind. The theory is illustrated by an example.
Résumé L'auteur établit des formules permettant de calculer les grandeurs suivantes en partant du spectre énergétique du vent: Fréquence des rafales de force ou de force maximale déterminées, force des rafales les plus fréquentes ainsi que le temps moyen séparant deux rafales. Il démontre sa théorie par un exemple.
Mit 4 Textabbildungen 相似文献
107.
108.
The paper investigates the roles and nature of postgraduate education on the professionalization of the shipping industry. The recent growth of postgraduate education is marked by the massive expansion of professional programmes on disciplines which traditionally emphasized non-academic, apprentice-style learning approach, including shipping business and management. The reasons behind such growth of demands, however, have remained scarce and empirically under-researched. Understanding this deficiency, in this study, we have undertaken a questionnaire survey completed by students/graduates who are pursuing/have recently pursued masters' programmes in shipping-related business and management offered by six Asian and European universities. Specifically, we analyze student motivations, considerations, and sources of information before enrolling such programmes, the extent that the shipping industry or other forces act as driving forces towards such enrollment, as well as students' evaluation of the postgraduate programmes that they are pursing/have pursued. Integrated in these discussions are comparative analyses of the data provided by different student groups based on their professional experiences and cultural backgrounds. We believe that this study has provided the lacking empirical inputs essential for achieving the sustainable development of postgraduate education in shipping business and management. 相似文献
109.
110.
Range and range rate measurements play an important role in geodetic applications of electromagnetic waves (terrestrial as
well as from space, including Very Long Baseline Interferometry (VLBI)) Recent developments of measuring, techniques have
led to the situation that the measuring accuracy is no longer the limiting factor in the final accuracies of range and range
rate measurements. The main error stems now from the influence of the atmosphere and from assumptions and approximations in
context with the derivation of refractive index used to describe the wave propagation properties of the atmosphere. Only in
the case that the geometrical optics approximation holds is it possible to calculate or to measure range error for wave propagation
in the atmosphere of the earth (troposphereand ionosphere) from knowledge of the refractive index as a function of space (location) and time. Otherwise we have to consides
additionally scattering and/or diffraction effects.
A discussion of the formulae for the refractive indices in the troposphere and in the ionosphere is followed by a review of
the propagation of electromagnetic waves described by the geometrical optics approximation and on the limitations, of geometrical
optics. A comprehensive discussion of range errors in the non-ionized atmosphere (troposphere) and in the ionosphere follows.
For this purpose we use the elevation of the “ray” at a ground station for division into four domains: a) vertical incidence
(as a special case), b) elevation between 90° and 30°, c)elevation between 30° and 5°, d) elevation smaller than 5°. 相似文献