نتایج جستجو برای: planetary atmosphere
تعداد نتایج: 74273 فیلتر نتایج به سال:
The presence of an atmosphere over sufficiently long timescales is widely perceived as one of the most prominent criteria associated with planetary surface habitability. We address the crucial question of whether the seven Earth-sized planets transiting the recently discovered ultracool dwarf star TRAPPIST-1 are capable of retaining their atmospheres. To this effect, we carry out numerical simu...
High material penetration by neutrons allows for experiments using sophisticated sample environments providing complex conditions. Thus, neutron imaging holds potential for performing in situ nondestructive measurements on large samples or even full technological systems, which are not possible with any other technique. This paper presents a new sample environment for in situ high resolution ne...
Recent investigations on the central stars of planetary nebulae (CSPN) indicate that the masses based on model atmospheres can be much larger than the masses derived from theoretical mass-luminosity relations. Also, the dispersion in the relation between the modified wind momentum and the luminosity depends on the mass spread of the CSPN, and is larger than observed in massive hot stars. Since ...
Torrefaction is a pretreatment method for upgrading biomass as solid fuels. To provide flexible operations for effectively upgrading biomass at lower costs, the aim of this study was to investigate the properties of oil palm fiber and eucalyptus pretreated in nitrogen and air atmospheres at temperatures of 250-350°C for 1h. Based on energy and solid yield and introducing an energy-mass co-benef...
We show that atmospheres having a nonnegligible radiative support undergo a second order phase transition above a critical radiative ux. This ux is less than but of order of the ux that corresponds to the Eddington luminosity limit. The trivial exponentially decaying solution, namely, the horizontally uniform solution, is energetically preferred for uxes below the critical one. However, the pre...
We analyze twenty five nearby metal-rich G and late-F dwarfs in order to verify whether the spectroscopic equilibrium (LTE) of iron lines satisfy the observational constraints imposed by the Infrared Flux Method (angular diameters) and Hipparcos parallaxes. The atmospheric parameters derived from iron lines (assuming LTE and employing 1D Kurucz model atmospheres) do not satisfy simultaneously b...
Passive sampling is an approved and accurate method for the assessment of organic compound exposure over long sampling time. This method could be very convenient for the short-time exposure assessment, but passive samplers have to be validated for this use. In this article, the behaviour of two commercial passive samplers (GABIE and Perkin Elmer) under fluctuant concentration conditions is stud...
A high pressure system equipped with several small sample vessels was installed in the Biochemistry Laboratory at the Naval Submarine Medical Research Laboratory and successfully modified for conducting a variety of biological reactions. Various problems encountered in making modifications to the system and their solutions are described. The most successful experiments to date have utilized ery...
The evolution of Earth-like habitable planets is a complex process that depends on the geodynamical and geophysical environments. In particular, it is necessary that plate tectonics remain active over billions of years. These geophysically active environments are strongly coupled to a planet's host star parameters, such as mass, luminosity and activity, orbit location of the habitable zone, and...
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