scholarly journals Compositional Variations of Spinels from Ultramafic Lamprophyres of the Chadobets Complex (Siberian Craton, Russia)

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 456
Author(s):  
Yazgul Nugumanova ◽  
Anna Doroshkevich ◽  
Ilya Prokopyev ◽  
Anastasiya Starikova
Keyword(s):  
Melt Inclusion ◽  
Mantle Peridotite ◽  
High Alumina ◽  
Temperature Changes ◽  
High Chromium ◽  
Chromium Spinel ◽  
Rapid Temperature ◽  
Spinel Composition ◽  
Compositional Variations ◽  
Primary Melt

Ultramafic lamprophyres (UMLs) are mantle rocks that provide important information about the composition of specific carbonate–silicate alkaline melts in the mantle as well as the processes contributing to their origin. Minerals of the spinel group typically occur in UMLs and have a unique “genetic memory.” Investigations of the spinel minerals from the UMLs of the Chadobets complex show the physicochemical and thermodynamic features of the alkaline rocks’ crystallization. The spinels of these UMLs have four stages of crystallization. The first spinel xenocrysts were found only in damtjernite pipes, formed from mantle peridotite, and were captured during the rising of the primary melt to the surface. The next stages of the spinel composition evolution are related to the high-chromium spinel crystallization, which changed to a high-alumina composition. The composition then changed to magnesian ulvöspinel–magnetites with strong decreases in the Al and Cr amounts caused by the release of carbon dioxide, rapid temperature changes, and crystallization of the main primary groundmass minerals such as phlogopite and carbonates. Melt inclusion analyses showed the predominance of aluminosilicate (phlogopite, clinopyroxene, and/or albite) and carbonate (calcite and dolomite) daughter phases in the inclusions that are consistent with the chemical evolution of the Cr-spinel trend. The further evolution of the spinels from magnesian ulvöspinel–magnetite to Ti-magnetite is accompanied by the formation of atoll structures caused by resorption of the spinel minerals.

A simple thermode for rapid temperature changes

1974 ◽  
Vol 349 (1) ◽  
pp. 83-85 ◽  
Author(s):  
H. Fruhstorfer ◽  
I. Detering
Keyword(s):  
Temperature Changes ◽  
Rapid Temperature

Measurement of Temperature and Heat Flux Changes During the Fixing Process in Electrophotographic Machines

1996 ◽  
Vol 118 (1) ◽  
pp. 150-154 ◽  
Author(s):  
T. Mitsuya ◽  
K. Masuda ◽  
Y. Hori
Keyword(s):  
Heat Flux ◽  
Print Quality ◽  
Two Dimensional ◽  
Temperature Changes ◽  
One Dimensional ◽  
Temperature Heat ◽  
Rapid Temperature ◽  
Pressure Changes ◽  
The Relationship ◽  
Electrophotographic Printing

Increasingly higher speeds of modern electrophotographic printing force examination of the problem of retaining sufficient fixing strength without deterioration of print quality. In the nip region between the two rollers where fixing occurs, the significant parameters are temperature, heat flux, and pressure changes. Their optimization is necessary to maintain both speed and print quality. Difficulty in analyzing the relationship among these parameters occurs because of the complexity of two-dimensional phenomena in a rotating field and the rapidity of changes. Experimental equipment to measure relative heat flux in the nip region during rapid temperature changes was designed. Two sensors are installed in the heat roller. An adiabatic piece is buried under sensor 1. Sensor 2, without an adiabatic piece, detects temperature. Sensor 1 is electrically heated and always at the same temperature as sensor 2. Heat flux changes are obtained by noting the electric power supplied to sensor 1. The equipment was fabricated and measurements were made. They indicate an intermittent two-dimensional heat flux. Because of this, temperature decreases rapidly before the entrance to the nip region. Estimates of two-dimensional effects are made and modified for a one-dimensional case. From them, the temperature field in the nip region for actual fixing conditions is calculated.

Shifting perceptions of rapid temperature changes’ effects on marine fisheries, 1945–2017

2019 ◽  
Vol 20 (6) ◽  
pp. 1111-1123
Author(s):  
Loren McClenachan ◽  
Jonathan H. Grabowski ◽  
Madison Marra ◽  
C. Seabird McKeon ◽  
Benjamin P. Neal ◽  
...  
Keyword(s):  
Marine Fisheries ◽  
Temperature Changes ◽  
Rapid Temperature

Failure Analysis on a De-NOx Catalyst of a Large Waste Burner

2005 ◽  
Vol 290 ◽  
pp. 78-85
Author(s):  
Jakob Kübler ◽  
R. Baechtold ◽  
Gurdial Blugan ◽  
K. Lemster ◽  
S. Fuso
Keyword(s):  
Failure Analysis ◽  
Microstructural Analysis ◽  
Chemical Properties ◽  
Exhaust Gas ◽  
Temperature Changes ◽  
Rapid Temperature ◽  
Cleaning Procedures ◽  
Different Depths ◽  
Processing Defects ◽  
Erosive Effect

Modern waste burners are equipped with catalysts to reduce NOX. During operation the catalysts and their performance are influenced by, for example rapid temperature changes, facility vibrations, cleaning procedures and unwashed exhaust gas (when the catalyst is installed before the washer). The catalyst discussed in this paper comprised over 2’500 extruded elements of 150 x 150 x 770 mm3. During commissioning the catalyst elements exhibited a tendency to spall off pieces, thus preventing acceptance of the plant. For the failure analysis, one element from the catalyst was removed and two spare elements were selected. The investigation comprised a visual check, fractography, measurement of the most important physical, mechanical and chemical properties, and a microstructural analysis. It could be shown that: − Processing defects, such as extrusion defects, were the source of cracks which led to pieces spalling off; − Hot steam, used for periodic cleaning, reduced the structural strength by half; − The elements were exposed to higher mechanical loads than expected during transport; − The cleaning process, in combination with particles transported by the exhaust gas, has an erosive effect on the catalyst material; − Blockages, caused by catalyst material among other things, could be found at different depths; − The chemical composition did not significantly differ between used and unused elements. In summary, the failure analysis led to an understanding of the failure mechanism and to a set of recommendations for improvements whose implementation ultimately led to the plant being cleared for operation.

Finite Element Analysis of a Pipe Junction With a Thermal Sleeve Subject to Thermal and Pressure Transient Events

2014 ◽  
Author(s):  
Alec Pattinson ◽  
James Dodds ◽  
Peter Hugill ◽  
Gary Reed
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Computational Fluid Dynamic ◽  
Pressure Vessel ◽  
Fluid Dynamic ◽  
Element Analysis ◽  
Temperature Changes ◽  
Rapid Temperature ◽  
Transient Events ◽  
Fracture Performance

This paper describes the results of a Finite Element Analysis (FEA) of a pipe junction consisting of a thermal sleeve subject to rapid temperature changes. The purpose of the analysis was to utilise derived Computational Fluid Dynamic (CFD) temperatures to calculate stresses on the pressure boundary and thermal sleeve of a pipe junction. Several transient events were modelled and analysed. Work was then carried out in accordance with the relevant articles of the ASME Boiler and Pressure Vessel Code, Section III, sub-section NB. Work included, design, hydrotest, Level A (including fatigue) and simplified elastic plastic assessments, however not presented within this paper. The likely fracture performance of the pressure boundary was also investigated, however are also not presented within this paper.

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