scholarly journals Model of heat diffusion in the outer crust of bursting neutron stars

2020 ◽  
Vol 500 (4) ◽  
pp. 4491-4505
Author(s):  
D G Yakovlev ◽  
A D Kaminker ◽  
A Y Potekhin ◽  
P Haensel
Keyword(s):  
Neutron Stars ◽  
Spherical Layer ◽  
High Heat ◽  
Heat Propagation ◽  
Heat Diffusion ◽  
Heat Reservoir ◽  
High Heat Capacity ◽  
Self Similar ◽  
Outer Crust ◽  
Good Heat

ABSTRACT We study heat diffusion after an energy release in a deep spherical layer of the outer neutron star crust (107 ≲ ρ ≲ 4 × 1011 g cm−3). We demonstrate that this layer possesses specific heat-accumulating properties, absorbing heat and directing it mostly inside the star. It can absorb up to ∼1043–1044 erg due to its high heat capacity, until its temperature exceeds T ∼ 3 × 109 K and triggers a rapid neutrino cooling. A warm layer (T ∼ 108–3 × 109 K) can serve as a good heat reservoir, which is thermally decoupled from the inner crust and the stellar core for a few months. We present a toy model to explore the heat diffusion within the heat-accumulating layer, and we test this model using numerical simulations. We formulate some generic features of the heat propagation that can be useful, for instance, for the interpretation of superbursts in accreting neutron stars. We present a self-similar analysis of late afterglow after such superbursts, which can be helpful to estimate properties of bursting stars.

scholarly journals Converting neutron stars into strange stars: Instanton model

2014 ◽  
Vol 23 (09) ◽  
pp. 1450078
Author(s):  
Victor Ts. Gurovich ◽  
Leonid G. Fel
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
Detonation Wave ◽  
Neutron Stars ◽  
Quark Matter ◽  
Quantum Fluctuation ◽  
The Self ◽  
Quantum Field ◽  
Spherical Detonation ◽  
Self Similar

We calculate the quasiclassical probability to emerge the quantum fluctuation which gives rise to the quark-matter drop with interface propagating as the self-similar spherical detonation wave (DN) in the ambient nuclear matter. For this purpose, we make use of instanton method which is known in the quantum field theory.

Safety Issues Concerning Robotic Welding of Large Elements

2015 ◽  
Vol 220-221 ◽  
pp. 818-823 ◽  
Author(s):  
Wojciech J. Klimasara ◽  
Zbigniew Pilat ◽  
Marcin Słowikowski
Keyword(s):  
Risk Factors ◽  
Health Risks ◽  
Occupational Safety ◽  
High Heat ◽  
Robotic Welding ◽  
European Directives ◽  
Safety Issues ◽  
Safety Regulations ◽  
High Heat Capacity ◽  
Welding Processes

Robotic welding of large elements poses significant difficulties regarding the technological process, robot functions and the safety of the operator and other people. The health risks involved arise out of the weight of elements, high heat capacity, harmful gases and fumes. Under the Eureka project, the PIAP team is developing a model of a robotized cell designed mainly for welding large elements. Occupational safety is of paramount importance and hence is a constructive discussion on occupational health risk factors. The replacement of human workers with robots on assembly nests, especially in SMEs, eliminates the exposure of workers to hazard, but is focused on a reduction in employment rather than in significant improvements to the workplace. The paper analyzes and discusses European safety regulations contained in the European directives and applicable EN standards. Appropriate safety programs of diverse welding processes and materials to be implemented by designers and suppliers of robotic welding stations and lines, as well as by the users thereof, will be indicated.

scholarly journals Effects of sleep on a high-heat capacity mattress on sleep stages, EEG power spectra, cardiac interbeat intervals and body temperatures in healthy middle-aged men‡

SLEEP ◽  
2019 ◽  
Vol 43 (5) ◽  
Author(s):  
Sebastian Herberger ◽  
Kurt Kräuchi ◽  
Martin Glos ◽  
Katharina Lederer ◽  
Lisa Assmus ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heat Capacity ◽  
Body Temperature ◽  
Wave Energy ◽  
Sleep Stage ◽  
High Heat ◽  
Body Temperatures ◽  
High Heat Capacity ◽  
Eeg Power ◽  
Core Body

Abstract Study Objectives This study deals with the question whether a slow (non-disturbing) reduction of core body temperature (CBT) during sleep increases sleep stage N3 and EEG slow wave energy (SWE) and leads to a slowing of heart rate in humans. Participants Thirty-two healthy male subjects with a mean ± SD age 46 ± 4 years and body mass index 25.2 ± 1.8 kg/m2. Methods A high-heat capacity mattress (HM) was used to lower body temperatures in sleep and was compared to a conventional low-heat capacity mattress (LM) in a double-blinded fashion. Polysomnography was performed accompanied by measurements of skin-, core body- and mattress surface-temperatures, and heart rate. EEG power spectral analyses were carried out using Fast Fourier Transform. Interbeat intervals were derived from the electrocardiogram. Results The HM led to a larger decline in CBT, mediated through higher heat conduction from the core via the proximal back skin onto the mattress together with reduced heart rate. These effects occurred together with a significant increase in sleep stage N3 and standardized slow wave energy (sSWE, 0.791–4.297 Hz) accumulated in NREM sleep. In the 2nd half of the night sSWE increase was significantly correlated with body temperature changes, for example with CBT decline in the same phase. Conclusions A HM subtly decreases CBT, leading to an increased amount of sleep stage N3 and of sSWE, as well as a slowing of heart rate.

The Use of Ionic Liquids in Refrigeration

2006 ◽  
Author(s):  
Mihir Sen ◽  
Samuel Paolucci
Keyword(s):  
Ionic Liquids ◽  
Room Temperature ◽  
High Heat ◽  
The Other ◽  
Refrigeration Cycle ◽  
Absorption Refrigeration ◽  
Transfer Coefficients ◽  
High Solubility ◽  
High Heat Capacity ◽  
Thermal And Chemical Stability

Ionic liquids are salts, usually with organic cations and inorganic anions, that are liquid at room temperature. There are a wide variety of ionic liquids that can be synthesized with different properties for different applications. They are generally non-volatile, non-toxic, and non-flammable with high heat capacity, high density, high thermal and chemical stability. We propose its use as an absorbent in an absorption refrigeration cycle. The refrigerant in this case would be a gas such as carbon dioxide. The present work deals with the desirable properties of ionic liquids for this application. For example, the absorbent must have a high solubility, and the heat and mass transfer coefficients of the absorbent-refrigerant solution must be large. The viscosity of the mixture, on the other hand, should not be so large as to make its pumping difficult.

Sleep on a high heat capacity mattress increases conductive body heat loss and slow wave sleep

2018 ◽  
Vol 185 ◽  
pp. 23-30 ◽  
Author(s):  
Kurt Kräuchi ◽  
Elisa Fattori ◽  
Alessandra Giordano ◽  
Maria Falbo ◽  
Antonella Iadarola ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Heat Loss ◽  
Slow Wave ◽  
Slow Wave Sleep ◽  
High Heat ◽  
Conductive Body ◽  
High Heat Capacity ◽  
Body Heat

A Novel Design of Liquid Volumetric Plated Cavity Receiver for Central Tower Systems

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Om Singh ◽  
Kaustubh Bhatwadekar ◽  
N. G. Kartheek ◽  
Shireesh B. Kedare ◽  
Suneet Singh
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
High Heat ◽  
Heat Transfer Fluid ◽  
Solar Salt ◽  
Suitable Candidate ◽  
Storage Devices ◽  
Parallel Arrangement ◽  
High Heat Capacity ◽  
Novel Design

Abstract Previously reported studies have shown that the volumetric receivers have lower radiative and convective losses, leading to higher efficiency. However, the conventional volumetric receivers are difficult to use along with the thermal storage systems, owing to the use of air as the heat transfer fluid. Molten salt, having high heat capacity, emerges as a suitable candidate to be employed as the heat transfer fluid and for storing thermal energy in the storage devices. It is challenging to use the molten salt in the conventional volumetric receiver configuration; therefore, a novel design called Liquid Volumetric Plated Cavity Receiver is proposed, where the solar salt is used as heat transfer fluid. It consists of a parallel arrangement of hollow plates in an open cavity. Solar radiation concentrated by the heliostat field is absorbed on the outer surface of the hollow plates. The heat is then taken away by the molten salt flowing inside the hollow plates. The plates are arranged such that the molten salt gets heated up within the volume of the enclosure, effectively mimicking the heating performance of the volumetric receivers. Using an analytical model for heat losses, it is observed that the losses are very sensitive to the aspect ratio of the aperture and depth of the receiver. The effects of receiver inclination, plate orientations, radiation incident at the aperture, and surface emissivity have been investigated as well. The results show that a Liquid Volumetric Plated Cavity Receiver increases the efficiency (by ∼3%) as compared with that of the simple cubic receiver.

scholarly journals Development of core–sheath structured smart nanofibers by coaxial electrospinning for thermo-regulated textiles

RSC Advances ◽  
2019 ◽  
Vol 9 (38) ◽  
pp. 21844-21851 ◽  
Author(s):  
Liqiang Yi ◽  
Yan Wang ◽  
Yini Fang ◽  
Ming Zhang ◽  
Juming Yao ◽  
...  
Keyword(s):  
Heat Capacity ◽  
High Heat ◽  
Coaxial Electrospinning ◽  
High Heat Capacity

Fabrication of core–sheath structured smart nanofibers loaded with CsxWO3 by coaxial electrospinning which demonstrate high heat capacity and NIR absorbance.

Physical Properties of Selected Silicates for a Long-Term Heat Container

2018 ◽  
Vol 276 ◽  
pp. 154-159
Author(s):  
Stanislav Šťastník ◽  
Jiří Vala ◽  
František Šot
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
High Heat ◽  
Thermal Source ◽  
Temperature Changes ◽  
Measurement Methodology ◽  
Wire Method ◽  
High Heat Capacity ◽  
Basic Prerequisite

Implementation of high temperature solar reservoirs is associated with problems related to the physical properties of materials, especially with temperature resistance of the material at temperature changes, with high heat capacity, with high thermal conductivity and with material fire resistance. In the case of silicate materials, more specific materials with favourable physical properties are available, which can be used for the construction of high temperature containers. The basic prerequisite for designing such container is the knowledge of the physical properties of the heat storage core and the thermal insulation ability of container cladding layers.The paper deals with the problem of identification of material properties of silicates in the wide temperature range up to 800 °C, using the standard measurement methodology, improved by additional temperature recording at a defined distance from the thermal source during the dynamic thermal development of the linear thermal source, well-known as the hot wire method.

scholarly journals MAGNETIC FIELD DECAY DUE TO THE WAVE-PARTICLE RESONANCES IN THE OUTER CRUST OF NEUTRON STARS

2011 ◽  
Vol 728 (2) ◽  
pp. 151 ◽  
Author(s):  
Hiroyuki R. Takahashi ◽  
Kei Kotake ◽  
Nobutoshi Yasutake
Keyword(s):  
Magnetic Field ◽  
Neutron Stars ◽  
Field Decay ◽  
Outer Crust
Sign in / Sign up

Export Citation Format

Share Document