Definition of the normal gravity field including the constant part of tides     

Antonín Zeman  Reviewer Z. Šimon 《Studia Geophysica et Geodaetica》1987,31(2):113-120

Summary One alternative of solving the problem of eliminating the effect of external masses, generating the constant part of the tidal field, from the perturbing potential is presented. The solution is founded on a new definition of the normal gravity field which contains this part of the tidal field. It is proved that two material circles in the plane of the Earth's equator, whose radii are approximately equal to the mean distances of the Moon and Sun from the Earth, can be considered as the source of this field. The new normal gravity field is first derived in the spherical approximation, which enables one to prove simply that the value of the normal gravity potential on the reference surface does not change, and that the change in the definition of the heights is insignificant. The normal gravity field for the equipotential ellipsoid is derived in the same way according to [1].

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¶rt;mam ¶rt;a amamua u ¶rt;umua n uu uu u a, au nm am nuu n, u a nmuaa. u a a n¶rt;uu a n u mmu, m m am nuu n aam. aam, m am umua m n umam a ¶rt; m nmu ama, a¶rt;u m nuuum a ¶rt;u amu u a m u. ¶rt; ¶rt; a n u mmu u nuuuu, m nm nm ¶rt;aam, m au a nmuaa u mmu a nmu m u m uu n¶rt;u m aum. ¶rt;ua n (. [1]) ¶rt; a n u mmu ¶rt; unu¶rt;a.

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In-Situ strain measurement by photoelastic bar gages, 1. The method     

Anton Brown 《Tectonophysics》1973,19(4):383-397

A technique is described for measuring recoverable strain in situ using bridged photoelastic bar gages and a simple reflecting polariscope. Rosettes of 0.2 × 0.4 × 4-cm bars are bonded to the rock for 0.6 cm at each end. Change in strain is measured following overcoring with a 10-cm bit. Correction for strains in the order of 30 · 10^?6/°C, due to differential thermal expansion between rock and gage, are made by monitoring dummy gages mounted on free blocks. Bar gages have been satisfactorily tested against foil resistance gages. Rosettes mounted closely adjacent on a free granite block showed a reasonable homogeneity of response.  相似文献   

Secular changes of the geoid in the Fennoscandian land uplift region     

Antonín Zeman  Reviewer M. Pick 《Studia Geophysica et Geodaetica》1984,28(3):224-236

Summary Two alternative methods are presented of determining the secular changes of the geoid in the Fennoscandian uplift region. Both are based on the Airy-Heiskanen hypothesis of isostatic compensation. The first alternative is the usual Stokes integration of changes of free-air anomalies in the given region. Another alternative was derived, which is based on calculating the gravitational potential of the surface uplift layer and of the same layer at the depth of compensation. The calculated changes of the shape of the geoid were then compared with the results of Bjerhammar's geophysical interpretation of the expansion of the Earth's gravity potential (regional depression of the geoid in the Fennoscandian uplift region). Regression analysis indicates a strong correlation between the two quantities (r=0.88). The time required to level this depression of the geoid is estimated. A relation was derived for improving the accuracy of the observed values of Fennoscandian uplifts, which takes into account the elastic reaction of the Earth's body to the change of gravitational potential and perturbations, caused by the secular decrease of the depth of the northern part of the Baltic Sea.

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¶rt;ma ¶rt;a auama m¶rt;a n¶rt;u uuu¶rt;a amu n¶rt;a a¶rt;uu. a u¶rt;m uunm uamu nauu u-aa. auam — umuau ma uu aau ¶rt; ¶rt; ¶rt;a amu. ¶rt; m auam, a a uuuaumau nmuaa nm n¶rt;a, u a au nauu. am u uu u¶rt;a auam mamau aaa nuu umnmauu au nmuaa u mmu u (ua ¶rt;nuuu¶rt;a amu a¶rt;uauu). u aau aam a u au u uu (r=0,88). uam , ¶rt;u ¶rt; auau a ¶rt;nuuu¶rt;a. ¶rt; mu ¶rt; mu u au n¶rt; a¶rt;uauu, a n au u a uuaumau nmuaa u u, mau u uu amu amu .

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Quasi-satellite orbits in the general context of dynamics in the 1:1 mean motion resonance: perturbative treatment     

Vladislav V. Sidorenko  Anatoly I. Neishtadt  Anton V. Artemyev  Lev M. Zelenyi 《Celestial Mechanics and Dynamical Astronomy》2014,120(2):131-162

Our investigation is motivated by the recent discovery of asteroids orbiting the Sun and simultaneously staying near one of the Solar System planets for a long time. This regime of motion is usually called the quasi-satellite regime, since even at the times of the closest approaches the distance between the asteroid and the planet is significantly larger than the region of space (the Hill’s sphere) in which the planet can hold its satellites. We explore the properties of the quasi-satellite regimes in the context of the spatial restricted circular three-body problem “Sun–planet–asteroid”. Via double numerical averaging, we construct evolutionary equations which describe the long-term behaviour of the orbital elements of an asteroid. Special attention is paid to possible transitions between the motion in a quasi-satellite orbit and the one in another type of orbits available in the 1:1 resonance. A rough classification of the corresponding evolutionary paths is given for an asteroid’s motion with a sufficiently small eccentricity and inclination.  相似文献   

Disproportion among Cladocera (Crustacea) skeletal components in lake sediment taphocoenoses and significance with respect to two methods of sub-fossil enumeration     

Zharov  Anton A.  Tchabovsky  Andrey V.  Kotov  Alexey A. 《Journal of Paleolimnology》2022,67(2):101-113

Journal of Paleolimnology - Analysis of Cladocera (Crustacea: Branchiopoda) subfossil remains in lake sediments features prominently in paleolimnological studies. It is well known, however, that...  相似文献   

Threshold of tolerance model: strategy for international travel     

Deborah Meyer  Lisa Robyn Barnes  Anton Kriz 《GeoJournal》2014,79(5):557-563

The purpose of this research is to investigate what factors influence the management of International Business Air Travel (IBAT). The researchers interviewed 34 business travellers, travel organisers and executives involved in IBAT from ten organisations in differing industries, in Australia. It was found that there are a multitude of factors influencing IBAT management, including professionalism and job satisfaction of travellers and the achievement of organisational goals such as carrying out successful international ventures or operating effectively in international markets. From the findings a strategic model was developed called the Threshold of Tolerance Model—which illustrates the potential point where both organisational goals are most likely to be met and where IBAT is most likely to be well managed for both travellers and organisations.  相似文献   

The temperature variation in an epikarstic cave and its impact factors: a case from Velika Pasica Cave,Central Slovenia     

Wei Liu  Cuiying Zhou  Zhen Liu  Chen Yang  Anton Brancelj 《Arabian Journal of Geosciences》2017,10(1):2

In order to reveal the temperature variation mechanism of a small and relatively closed cave, the surface temperature, the cave air temperature and the drip water temperatures were monitored with high-resolution recorders for a 7-year period. The results indicated that the cave temperature is mainly affected by the external seasonal oscillations. The temperature curve of the inner cave area (with standard deviation between 0.59 and 0.87) was much smoother in comparison with that of the surface (with SD as high as 8.46). However, the cave reacted to the temperature drifts with some delay, for example, at VP3 in 2006, the internal temperature increased for additional 49 days after the surface temperature dropped colder than inside of the cave. This seasonal variation and delayed response of the internal temperature were mainly affected by conduction from the epikarst rock mass. Air convection also occurred in the cave, especially when the surface temperature dropped lower than that of the inside cave (during the winter time) and in the outer section (close to the entrance), which caused an abrupt and irregular variation of the outer section. In addition, the influence from the percolating water was ephemeral and depended on its supplementary amount and temperature difference, e.g., there were more apparent responses at VP1 and VP3 when the intensive rain fell. The percolating water temperature could be a good indicator for water flow in epikarst.  相似文献   

Diversity,composition and host-species relationships of epiphytic orchids and ferns in two forests in Nepal   总被引：1，自引：0，他引：1  

Yagya P. Adhikari  Anton Fischer  Hagen S. Fischer  Maan B. Rokaya  Prakash Bhattarai  Axel Gruppe 《山地科学学报》2017,14(6):1065-1075

Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observing the patterns of species richness, abundances and species composition of epiphytic orchids and ferns in two subtropical forests in Nepal. We also studied the relationship of host plants (Schima wallichii and Quercus lanata) and epiphyte species. Data were collected in Naudhara community forest (CF) and the national forest (NF) in Shivapuri Nagarjun National Park. The data were analyzed using univariate and multivariate tests. In total, we recorded 41 species of epiphytes (33 orchid and 8 fern species). Orchid species abundance is significantly higher in CF compared to NF. Orchid species richness and abundance increased with increasing southern aspect whereas it decreased with increasing canopy cover, and fern species richness increased with host bark roughness. Orchid abundance was positively correlated with increasing bark pH, stem size, tree age and tree height and negatively correlated with increasing steepness of the area. Likewise, fern abundances were high in places with high canopy cover, trees that were tall and big, but decreased with increasing altitude and southern aspect. The composition of the orchid and fern species was affected by altitude, aspect, canopy cover, DBH, number of forks and forest management types. We showed that the diversity of orchid and fern epiphytes is influenced by host characteristics as well as host types. The most important pre-requisite for a high epiphyte biodiversity is the presence of old respectively tall trees, independent of the recent protection status. This means: (i) for protection, e.g. in the frame of the national park declaration, such areas should be used which host such old tall trees; and (ii) also in managed forests and even in intensively used landscapes epiphytes can be protected by letting a certain number of trees be and by giving them space to grow old and tall.  相似文献