scholarly journals Direct Measurement of Mass-Temperature Distributions in the Core of Implosions on the National Ignition Facility

2020 ◽  
Author(s):  
D Thorn
Keyword(s):  
Direct Measurement ◽  
National Ignition Facility ◽  
The Core ◽  
Mass Temperature ◽  
Temperature Distributions

Transport of planktic foraminifera by ocean currents in the Uruguayan margin

2020 ◽  
Author(s):  
Anne Kruijt ◽  
Andrew Mair ◽  
Peter Nooteboom ◽  
Anna S. von der Heydt ◽  
Martin Ziegler ◽  
...  
Keyword(s):  
Biological Activity ◽  
General Circulation ◽  
Ocean Currents ◽  
Western Boundary ◽  
Planktic Foraminifera ◽  
The Core ◽  
Temperature Distributions ◽  
Species Analysis ◽  
Core Site ◽  
Ocean Conditions

<p><span>Fossils of planktic foraminifera are found in marine sediments and are widely used as a proxy for past ocean conditions. The habitat of these unicellular marine zooplankton ranges from tropical to polar regions and is mostly located in the upper mixed layer of the ocean. The foraminifera form a calcium carbonate ’shell’ around their cell during their lifespan. When they die, foraminifera lose their ability to control their buoyancy and their shells sink to the ocean floor. It is often assumed that the proxies which are derived from the shells in sediment cores represent ocean conditions above the location of deposition. However, foraminifera are transported by ocean currents, both during and after their lifespan. Hence, the paleoclimatic conditions recorded from their shells may originate far from the core site, generating large footprints in foraminifera-based paleoclimatic proxies.</span><span> </span></p><p><span>In this project, we quantify the influence of the transport by ocean currents on the proxy signal of foraminifera found at core sites in the Uruguayan margin of the Punta del Este basin. This is a region where two western boundary currents meet: The southward flowing Brazil current and the northward flowing Malvinas current. We use a high resolution (0.1° horizontally) ocean general circulation model to track virtual sinking particles and the local oceanic conditions along their pathways. These model results are compared to proxy- and species analysis from the core sites. We found that offsets in modelled proxy signals due to transport in the Uruguayan margin are strongly linked to the relative position of the core site to the Brazil-Malvinas confluence. These offsets are most pronounced in the tails of the temperature distributions where they can reach up to +/- 7°C at sites located in the confluence zone. Species analysis from core tops taken slightly north of this region show more cold water species than reflected by the modelled temperature distributions, suggesting biological activity and nutrient availability not taken into account in the model play an important additional role in the relative abundances of species. <br></span><span>Our model simulations have provided both a first order insight into the potential proxy-signal offsets in highly dynamic ocean regions and show that understanding of the interplay between transportation effects and the biological activity of foraminifera is crucial for the interpretation of these proxies.</span></p><p> </p>

Coupled Structural/Thermal Analysis of Cylindrical Part of Multilayered Composite Vessel

2012 ◽  
Vol 445 ◽  
pp. 589-594 ◽  
Author(s):  
A. Hocine ◽  
F.K. Achira ◽  
H. Ghouaouala
Keyword(s):  
Thermal Analysis ◽  
Analytical Model ◽  
Laminate Composite ◽  
Thermal Response ◽  
Layered Composite ◽  
Cylindrical Part ◽  
End Effect ◽  
The Core ◽  
Temperature Distributions ◽  
Composite Vessel

This paper focuses on the coupled structural/thermal response of a cylindrical part of multi-layered composite vessel. Uniform and parabolic temperature distributions are chosen for the structural loads. In this work, an analytical model is proposed in which the laminate composite is assumed to be an anisotropic purely elastic material. Assuming that the interface between the core and skin are perfectly bound, continuity conditions for the displacement and stress, the suggested analytical model provides an exact solution for stresses and strains on the cylindrical section of the vessel solution submitted hygrothermal loading coupled with internal pressure with end effect.

Measurements of the variation with depth of the main geomagnetic field

1951 ◽  
Vol 244 (878) ◽  
pp. 113-151 ◽  
Keyword(s):  
Direct Measurement ◽  
Geomagnetic Field ◽  
Fundamental Property ◽  
Main Field ◽  
The Core ◽  
The Earth ◽  
Core Theory ◽  
Whole Earth

The main geomagnetic field is attributable either to some deep-seated phenomena within the earth or to a fundamental property of rotating matter in which the source of the field would be distributed throughout the whole earth. The two types of explanation predict a different variation of the components of the main field with depth within the crust and can be tested by direct measurement in suitable localities. Measurements in five mines in northern England are presented and discussed, and they provide evidence in favour of the core theory.

scholarly journals Heat Transfer Characteristics of Rotating Ceramic Regenerators: Numerical Solution Using a Hybrid Finite Difference/Laplace Transform Scheme

1991 ◽  
Author(s):  
Keiji Kawasaki ◽  
Tadaaki Matsuhisa ◽  
Itsuro Sakai ◽  
Kunio Hijikata
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Laplace Transform ◽  
Gas Turbines ◽  
Initial Conditions ◽  
Working Fluids ◽  
The Core ◽  
Temperature Distributions ◽  
Steady State Operation ◽  
Ceramic Honeycomb

A hybrid numerical method, combining finite differences with respect to space and a Laplace transform with respect to time, is proposed to determine the heat transfer in a rotary heat exchanger used as a rotating ceramic regenerator for automotive gas turbines. The temperature distributions of the core and of the working fluids are solved for given boundary and initial conditions of a rotary regenerator using this method. An advantage of the present method is that it can be applied when the core and the working fluids have dissimilar temperature distributions. The temperature change in the ceramic honeycomb core was determined from start up to periodic steady state operation. The heat exchanger effectiveness was obtained for an extruded ceramic core used in automotive gas turbine applications.

scholarly journals Thermal evolution of the Earth's core during its formation taking into account heat release from the short-lived radioisotopes 26Al and 60Fe

LITOSFERA ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 256-261
Author(s):  
A. N. Antipin ◽  
M. G. Mindubaev
Keyword(s):  
Heat Release ◽  
Thermal Evolution ◽  
Carbonaceous Chondrites ◽  
Research Subject ◽  
The Core ◽  
Temperature Distributions ◽  
Mhd Dynamo ◽  
Dynamo Mechanism ◽  
Account Heat ◽  
Fractional Content

Research subject. Based on the two-stage mechanism of the Earth's heterogeneous accumulation, previously proposed by V.N. Anfilogov and Yu.V. Khachay, the thermal evolution of the core during its formation was studied. Account is taken of both the heat release from 26Al, the content of which was established with a fairly reliable accuracy, and that from 60Fe.Materials and methods. The methods of mathematical modelling were used. Calculations were carried out for three estimates of the fractional content of the radioisotope 60Fe to stable 56Fe at the time of CAI formation (Ca-Al-In- clusions, calcium- and aluminium-rich inclusions found in carbonaceous chondrites) based on the results of various authors.Results. As a result of numerical experiments, variants of the temperature and melting temperature distributions at different stages of the core formation for different 60Fe/56Fe ratios were obtained.Conclusions. The results show that the central region of the forming core can remain melted even by the end of its accumulation. As a consequence, in this region for this time, the conditions for free thermal convection and, accordingly, for the implementation of the MHD dynamo mechanism remain.

scholarly journals The stability of the internal cavities of steel casting

2019 ◽  
pp. 24-27
Author(s):  
I. B. Odarchenko ◽  
A. A. Sinitskij ◽  
I. N. Prusenko
Keyword(s):  
Geometric Shape ◽  
Temperature Fields ◽  
Mechanical Interaction ◽  
Casting And Solidification ◽  
The Core ◽  
Temperature Distributions ◽  
Internal Cavities ◽  
The Stability ◽  
Phase Stresses ◽  
Core Mixture

The mechanism and causes of the formation of casting defects, manifested in the deviation of the geometry of the internal cavities from the «cylindrical», are investigated. It is shown that the causes of distortion of the geometric shape are associated with deformation of the casting rod during thermal and mechanical interaction with the melt. Using the possibilities of computer simulation in the MAGMASOFT package, the temperature distributions of the metal in the casting body during the casting and solidification were analyzed. Areas of distortion of the geometric shape of the inner part of the casting correspond to the area of the rod subjected to the highest and longest thermal loads. The characteristics of the temperature fields in the respective zones indicate overheating of individual areas of the rod to temperatures causing phase stresses in the structure of the core mixture, sufficient for the occurrence of deformations in it. To eliminate the defect under consideration, two approaches were used to reduce the magnitude of phase stresses in the casting rod and to adjust the design of the rod tooling.

scholarly journals Frequency Stability of the Cooler Pulsating White Dwarfs

2000 ◽  
Vol 176 ◽  
pp. 523-524
Author(s):  
D. J. Sullivan
Keyword(s):  
Direct Measurement ◽  
White Dwarfs ◽  
Frequency Stability ◽  
Period Change ◽  
Time Base ◽  
Change Rate ◽  
The Core ◽  
Core Composition ◽  
Long Time ◽  
Geometrically Constrained

AbstractAlthough the frequencies of the pulsating white dwarfs are extremely stable, the evolutionary cooling of these geometrically constrained objects should lead to an observable period change over a sufficiently long time base. Direct measurement of a period change rate for the cooler white dwarfs should provide fundamental data on the core composition of these stellar remnants, and hence their cooling time scales. Progress on attempts to measure the period change rates of two white dwarfs is reported.

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