hydrogen burning
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2021 ◽  
Vol 2 (6) ◽  
pp. 1-11
Author(s):  
Lucian Paunescu ◽  
Gheorghe Surugiu ◽  
Paul Dan Stanescu

Traditional Ghanaian furniture designs are known as an exhibition of the splendor and elegance of decorative objects or decorative ornaments that carry profound philosophical and sacred meanings.  The features found in Ghana’s traditional Ghanaian design can be considered as objects for international players, with their own identity and not found elsewhere.  This paper therefore seeks to identify and illuminate some of these Akan cultural objects in Ghana by referring to the Ashanti region. This paper also shows with examples how these design elements can be developed and maintained by integrating them into modern furniture and interior designs or as a straightforward or adaptive design.  


2021 ◽  
Vol 882 (1) ◽  
pp. 012033
Author(s):  
Eko Supriyanto ◽  
Nur Cahyo ◽  
Ruly Sitanggang ◽  
Rasgianti ◽  
Meiri Triani ◽  
...  

Abstract In a coal steam power plant, changes in coal quality significantly affect plant performance, especially in its boiler. A coal-fired power plant with a capacity of 400 MWe had been commissioned using coal with a calorific value of 5,242 kCal/kg. This study aims to determine the effect on unit performance and boiler efficiency due to changes in fuel use with the typical calorific value of 3,520 kCal/kg, 34,17% lower than the initial design. The performance tests were conducted using the heat loss method at loads: 50%, 65%, 75%, and 100%. The test result showed that using low-grade coal reduces boiler efficiency by 6.26%. There were four dominant boiler losses: heat loss due to moisture in dry flue gas, heat loss due to combustible in refuse, heat loss due to moisture in fuel, and heat loss due to hydrogen burning. Furthermore, the gross plant heat rate using low-grade coal was increased from 2,120 kCal/kWh to 2,718 kCal/kWh; however, the electric price becomes cheaper from 1.99 cent-USD/kWh becomes 1.31 cent-USD/kWh.


2021 ◽  
Author(s):  
Jianxing Chen ◽  
Francesco R. Ferraro ◽  
Mario Cadelano ◽  
Maurizio Salaris ◽  
Barbara Lanzoni ◽  
...  

2021 ◽  
Vol 136 (9) ◽  
Author(s):  
S. Palmerini ◽  
M. La Cognata ◽  
F. Hammache ◽  
L. Acosta ◽  
R. Alba ◽  
...  

AbstractThe $$^{27}\hbox {Al}(\hbox {p},\alpha )^{24}\hbox {Mg}$$ 27 Al ( p , α ) 24 Mg reaction, which drives the destruction of $$^{27}$$ 27 Al and the production of $$^{24}\hbox {Mg}$$ 24 Mg in stellar hydrogen burning, has been investigated via the Trojan Horse Method (THM), by measuring the $$^2\hbox {H}(^{27}\hbox {Al},\alpha ^{24}\hbox {Mg})\hbox {n}$$ 2 H ( 27 Al , α 24 Mg ) n three-body reaction. The experiment covered a broad energy range ($$E_\mathrm{c.m.}\le \,1.5\,\hbox {MeV}$$ E c . m . ≤ 1.5 MeV ), aiming to investigate those of interest for astrophysics. The results confirm the THM as a valuable technique for the experimental study of fusion reactions at very low energies and suggest the presence of a rich pattern of resonances in the energy region close to the Gamow window of stellar hydrogen burning (70–120 keV), with potential impact on astrophysics. To estimate such an impact a second run of the experiment is needed, since the background due the three-body reaction hampered to collect enough data to resolve the resonant structures and extract the reaction rate.


Author(s):  
N. Grieves ◽  
F. Bouchy ◽  
M. Lendl ◽  
T. Carmichael ◽  
I. Mireles ◽  
...  

2021 ◽  
Vol 143 (4) ◽  
pp. 46-51
Author(s):  
Lee S. Langston

Abstract The gas turbine industry took some unprecedented hits in 2020. And some sectors, such as the jet engine market, may take some time to recover. But new technologies, such as hydrogen burning turbines, give reason for hope.


Author(s):  
Joyce Ann Guzik

The NASA Kepler and follow-on K2 mission (2009–2018) left a legacy of data and discoveries, finding thousands of exoplanets, and also obtaining high-precision long time-series data for hundreds of thousands of stars, including many types of pulsating variables. Here we highlight a few of the ongoing discoveries from Kepler data on δ Scuti pulsating variables, which are core hydrogen-burning stars of about twice the mass of the Sun. We discuss many unsolved problems surrounding the properties of the variability in these stars, and the progress enabled by Kepler data in using pulsations to infer their interior structure, a field of research known as asteroseismology.


Author(s):  
A. N. Narozhnyi

The article discusses direct consequences of hydrogen regeneration mechanisms observed in galaxies when galactic nuclei are active. Previously, these mechanisms have been presented by describing the work of structures that form quasar jets. Based on evaluation of the findings obtained through observation of our Galaxy and intergalactic space, the present article gives direct evidence that the aforementioned processes exist. The adduced evidence is astronomical objects that have come into existence as a result of hydrogen ejected by jets together with plasma and dust. In terms of the Milky Way galaxy, this fact is emphasised by direct astronomical observation of its elements. There are also evidential findings among intergalactic astronomy observational data, whose origin is explained comprehensively in terms of the present approach. However, the provided findings are traditionally regarded from the prevailing Big Bang theory perspective. For instance, according to this theory, huge intergalactic hydrogen clouds are interpreted as residual hydrogen left from the primary explosion. The Milky Way observation results include data indicative of alleged contribution of the given processes to formation of some of its structural elements, including a number of satellite galaxies. There is a criterion whereby it is possible to distinguish galactic gas clouds and star clusters formed of galactic matter itself. This matter containing a great deal of regenerated hydrogen was ejected from a galactic nucleus during the period of its activity. Based on the example of a spiral galaxy, it is assumed that active galactic nuclei are possibly involved in the formation of its morphology. It is concluded that, when being active, a central supermassive object performs its primary function, which is to process waste produced during the life of stars. This process is the final link in the galactic life cycle, which consists of two reciprocal processes. The first one is about hydrogen burning continuously in stars, while the second one is about episodic activity of the galactic nucleus, which results in star waste that contributes to regeneration of hydrogen needed to maintain direct processes within the galaxy. The two specified processes are associated with one more process: stellar electromagnetic radiation energy extended beyond the galaxy partially returns to it. The process is completed due to a fragment of dark matter. The overarching conclusion can be drawn: as a functional system, the Universe is well-organised and self-sufficient to last forever.    


2021 ◽  
Vol 503 (4) ◽  
pp. 5965-5975
Author(s):  
N Yusof ◽  
H Abu Kassim ◽  
L G Garba ◽  
N S Ahmad

ABSTRACT We present a new overview of the life of very massive stars (VMS) in terms of neutrino emission from thermal processes: pair annihilation, plasmon decay, photoneutrino process, bremsstrahlung, and recombination processes in burning stages of selected VMS models. We use the realistic conditions of temperature, density, electron fraction, and nuclear isotropic composition of the VMS. Results are presented for a set of progenitor stars with mass of 150, 200, and 300 M⊙Z = 0.002 and 500 M⊙Z = 0.006 rotating models which are expected to explode as a pair instability supernova at the end of their life except the 300 M⊙ would end up as a black hole. It is found that for VMS, thermal neutrino emission occurs as early as towards the end of hydrogen burning stage due to the high initial temperature and density of these VMS. We calculate the total neutrino emissivity, Qν and luminosity, Lν using the structure profile of each burning stages of the models and observed the contribution of photoneutrino at early burning stages (H and He) and pair annihilation at the advanced stages. Pair annihilation and photoneutrino processes are the most dominant neutrino energy loss mechanisms throughout the evolutionary track of the VMS. At the O-burning stage, the neutrino luminosity ∼1047−48 erg s−1 depending on their initial mass and metallicity are slightly higher than the neutrino luminosity from massive stars. This could shed light on the possibility of using detection of neutrinos to locate the candidates for pair instability supernova in our local universe.


Author(s):  
F. Ferraro ◽  
G. F. Ciani ◽  
A. Boeltzig ◽  
F. Cavanna ◽  
S. Zavatarelli

The chemical evolution of the Universe and several phases of stellar life are regulated by minute nuclear reactions. The key point for each of these reactions is the value of cross-sections at the energies at which they take place in stellar environments. Direct cross-section measurements are mainly hampered by the very low counting rate and by cosmic background; nevertheless, they have become possible by combining the best experimental techniques with the cosmic silence of an underground laboratory. In the nineties, the LUNA (Laboratory for Underground Nuclear Astrophysics) collaboration opened the era of underground nuclear astrophysics, installing first a homemade 50 kV and, later on, a second 400 kV accelerator under the Gran Sasso mountain in Italy: in 25 years of experimental activity, important reactions responsible for hydrogen burning could have been studied down to the relevant energies thanks to the high current proton and helium beams provided by the machines. The interest in the next and warmer stages of star evolution (i.e., post-main sequence and helium and carbon burning) drove a new project based on an ion accelerator in the MV range called LUNA-MV, able to deliver proton, helium, and carbon beams. The present contribution is aimed to discuss the state of the art for some selected key processes of post-main sequence stellar phases: 12C(α,γ)16O and 12C+12C are fundamental for helium and carbon burning phases, and 13C(α,n)16O and 22Ne(α,n)25Mg are relevant to the synthesis of heavy elements in AGB stars. The perspectives opened by an underground MV facility will be highlighted.


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