Evaluation of artificial heating sources for the thermoregulation of Aldabra giant tortoises ( Aldabrachelys gigantea ) in Zurich zoo

Zoo Biology ◽  
2018 ◽  
Vol 37 (6) ◽  
pp. 458-465
Author(s):  
Wilfredo Falcón ◽  
Samuel Furrer ◽  
Martin Bauert ◽  
Jean‐Michel Hatt ◽  
Dennis M. Hansen ◽  
...  
Keyword(s):  
Artificial Heating

Some Effects of Artificial Heating on Fluorite-Bearing Albite-Granite from St. Austell, Cornwall

1957 ◽  
Vol 94 (1) ◽  
pp. 69-80 ◽  
Author(s):  
J. H. Weymouth ◽  
W. O. Williamson
Keyword(s):  
Thermal Expansion ◽  
Alkali Feldspar ◽  
Artificial Heating ◽  
Albite Granite ◽  
High Quartz

AbstractThe granite consisted chiefly of albite, quartz, muscovite, microperthite, fluorite, and topaz; zircon was very rare. The low to high quartz transition enhanced thermal expansion and porosity. Heating was continued step-wise to 1,300°C. and caused an irreversible increase in porosity at all temperatures investigated. The changes undergone by the various minerals, separately or through interaction, were noted. Fluorite began to melt against muscovite or alkali-feldspar between 800° and 900°C. Muscovite developed brownish pleochroism at the lower, and was replaced by mullite at the higher, temperatures. The gradual melting of feldspar, the development of cleavages and cracks in quartz, and the invasion of these cracks by feldspathic glass resembled phenomena in certain xenoliths.The conditions that produced glass when powdered granite was heated unconfined or in a bomb are described.

Diffusion spreading of middle-latitude ionospheric plasma irregularities

1995 ◽  
Vol 13 (6) ◽  
pp. 617-626 ◽  
Author(s):  
N. Blaunstein
Keyword(s):  
Ionospheric Plasma ◽  
Three Dimensional ◽  
Middle Latitude ◽  
Approximate Model ◽  
Ionospheric Irregularities ◽  
Radio Waves ◽  
Plasma Irregularities ◽  
Relaxation Effects ◽  
Artificial Heating ◽  
Actual Height

Abstract. In contrast to the way that the spreading of irregularities in a plasma is usually considered, the diffusion spreading of irregularities stretched along the geomagnetic field B is examined using a three-dimensional rigorous numerical model of quasi-neutral diffusion in the presence of a magnetic field, in conjunction with the actual height variations of the diffusion and conductivity tensors in the ionosphere. A comparison with the earlier constructed approximate model of unipolar diffusion was made. As in the previous case, the same peculiarities of irregularity spreading in the inhomogeneous background ionospheric plasma were observed. The accuracy of the approximate model for describing the process of spreading of anisotropic ionospheric irregularities is established. Time relaxation effects of real heating-induced ionospheric irregularities on their scale transverse to B are presented using the approximate analytical model for the case of a quasi-homogeneous ionospheric plasma. The calculated results have a vivid physical meaning and can be directly compared with experimental data on the radiophysical observations of artificial heating-induced irregularities created by powerful radio waves in the ionosphere.

scholarly journals Simulations of resonant Alfvén waves generated by artificial HF heating of the auroral ionosphere

2004 ◽  
Vol 22 (8) ◽  
pp. 2943-2949 ◽  
Author(s):  
D. Pokhotelov ◽  
W. Lotko ◽  
A. V. Streltsov
Keyword(s):  
Plasma Temperature ◽  
Dispersion Analysis ◽  
Marginal Stability ◽  
Auroral Ionosphere ◽  
Linear Dispersion ◽  
High Latitude Ionosphere ◽  
Artificial Heating ◽  
E Region ◽  
Hf Heating ◽  
Favorable Conditions

Abstract. Numerical two-dimensional two-fluid MHD simulations of dynamic magnetosphere-ionosphere (MI) coupling have been performed to model the effects imposed on the auroral ionosphere by a powerful HF radio wave transmitter. The simulations demonstrate that modifications of the ionospheric plasma temperature and recombination due to artificial heating may trigger the ionospheric feedback instability when the coupled MI system is close to the state of marginal stability. The linear dispersion analysis of MI coupling has been performed to find the favorable conditions for marginal stability of the system. The development of the ionospheric feedback instability leads to the generation of shear waves which resonate in the magnetosphere between the heated ionospheric E-region and the strong gradient in the speed at altitudes of 1-2 RE. The application of the numerical results for the explanation of observations performed by low-orbiting satellites above the high-latitude ionosphere heated with a high power ground-based HF transmitter is discussed.

scholarly journals Modelling the influence of meteoric smoke particles on artificial heating in the D-region

2021 ◽  
Vol 39 (6) ◽  
pp. 1055-1068
Author(s):  
Margaretha Myrvang ◽  
Carsten Baumann ◽  
Ingrid Mann
Keyword(s):  
Electron Temperature ◽  
Radio Wave ◽  
Electron Density ◽  
Electron Attachment ◽  
Radio Waves ◽  
Night Time ◽  
Smoke Particles ◽  
D Region ◽  
Meteoric Smoke ◽  
Artificial Heating

Abstract. We investigate if the presence of meteoric smoke particles (MSPs) influences the electron temperature during artificial heating in the D-region. By transferring the energy of powerful high-frequency radio waves into thermal energy of electrons, artificial heating increases the electron temperature. Artificial heating depends on the height variation of electron density. The presence of MSPs can influence the electron density through charging of MSPs by electrons, which can reduce the number of free electrons and even result in height regions with strongly reduced electron density, so-called electron bite-outs. We simulate the influence of the artificial heating by calculating the intensity of the upward-propagating radio wave. The electron temperature at each height is derived from the balance of radio wave absorption and cooling through elastic and inelastic collisions with neutral species. The influence of MSPs is investigated by including results from a one-dimensional height-dependent ionospheric model that includes electrons, positively and negatively charged ions, neutral MSPs, singly positively and singly negatively charged MSPs, and photochemistry such as photoionization and photodetachment. We apply typical ionospheric conditions and find that MSPs can influence both the magnitude and the height profile of the heated electron temperature above 80 km; however, this depends on ionospheric conditions. During night, the presence of MSPs leads to more efficient heating and thus a higher electron temperature above altitudes of 80 km. We found differences of up to 1000 K in electron temperature for calculations with and without MSPs. When MSPs are present, the heated electron temperature decreases more slowly. The presence of MSPs does not much affect the heating below 80 km for night conditions. For day conditions, the difference between the heated electron temperature with MSPs and without MSPs is less than 25 K. We also investigate model runs using MSP number density profiles for autumn, summer and winter. The night-time electron temperature is expected to be 280 K hotter in autumn than during winter conditions, while the sunlit D-region is 8 K cooler for autumn MSP conditions than for the summer case, depending on altitude. Finally, an investigation of the electron attachment efficiency to MSPs shows a significant impact on the amount of chargeable dust and consequently on the electron temperature.

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