scholarly journals Controls on andesitic glaciovolcanism at ice-capped volcanoes from field and experimental studies

Geology ◽  
2021 ◽  
Author(s):  
R.P. Cole ◽  
J.D.L. White ◽  
T. Dürig ◽  
R. Büttner ◽  
B. Zimanowski ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Experimental Studies ◽  
Ice Sheets ◽  
Thermal Characteristics ◽  
Explosive Eruptions ◽  
Pyroclastic Deposits ◽  
Apparent Lack ◽  
Interaction Sites ◽  
Andesitic Lava ◽  
Field Evidence

Glaciovolcanic deposits at Tongariro and Ruapehu volcanoes, New Zealand, represent diverse styles of interaction between wet-based glaciers and andesitic lava. There are ice-confined lavas, and also hydroclastic breccia and subaqueous pyroclastic deposits that formed during effusive and explosive eruptions into meltwater beneath the glacier; they are rare among globally reported products of andesitic glaciovolcanism. The apparent lack of hydrovolcanically fragmented andesite at ice-capped volcanoes has been attributed to a lack of meltwater at the interaction sites because either the thermal characteristics of andesite limit meltwater production or meltwater drains out through leaky glaciers and down steep volcano slopes. We used published field evidence and novel, dynamic andesite-ice experiments to show that, in some cases, meltwater accumulates under glaciers on andesitic volcanoes and that meltwater production rates increase as andesite pushes against an ice wall. We concur with models for eruptions beneath ice sheets showing that the glacial conditions and pre-eruption edifice morphology are more important controls on the style of glaciovolcanism and its products than magma composition and the thermal properties of magmas. Glaciovolcanic products can be useful proxies for paleoenvironment, and the range of andesitic products and the hydrological environments in which andesite erupts are greater than hitherto appreciated.

scholarly journals Obsidian pyroclasts in the Yellowstone-Snake River Plain ignimbrites are dominantly juvenile in origin

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
L. R. Monnereau ◽  
B. S. Ellis ◽  
D. Szymanowski ◽  
O. Bachmann ◽  
M. Guillong
Keyword(s):  
Glass Composition ◽  
Snake River Plain ◽  
Explosive Eruptions ◽  
Snake River ◽  
Pyroclastic Deposits ◽  
Volcanic Conduit ◽  
Trace Elemental ◽  
Multiple Cycles ◽  
River Plain ◽  
Glass Compositions

AbstractDense, glassy pyroclasts found in products of explosive eruptions are commonly employed to investigate volcanic conduit processes through measurement of their volatile inventories. This approach rests upon the tacit assumption that the obsidian clasts are juvenile, that is, genetically related to the erupting magma. Pyroclastic deposits within the Yellowstone-Snake River Plain province almost without exception contain dense, glassy clasts, previously interpreted as hyaloclastite, while other lithologies, including crystallised rhyolite, are extremely rare. We investigate the origin of these dense, glassy clasts from a coupled geochemical and textural perspective combining literature data and case studies from Cougar Point Tuff XIII, Wolverine Creek Tuff, and Mesa Falls Tuff spanning 10 My of silicic volcanism. These results indicate that the trace elemental compositions of the dense glasses mostly overlap with the vesiculated component of each deposit, while being distinct from nearby units, thus indicating that dense glasses are juvenile. Textural complexity of the dense clasts varies across our examples. Cougar Point Tuff XIII contains a remarkable diversity of clast appearances with the same glass composition including obsidian-within-obsidian clasts. Mesa Falls Tuff contains clasts with the same glass compositions but with stark variations in phenocryst content (0 to 45%). Cumulatively, our results support a model where most dense, glassy clasts reflect conduit material that passed through multiple cycles of fracturing and sintering with concurrent mixing of glass and various crystal components. This is in contrast to previous interpretations of these clasts as entrained hyaloclastite and relaxes the requirement for water-magma interaction within the eruptive centres of the Yellowstone-Snake River Plain province.

scholarly journals Structural, elastic, electronic and thermal properties of InAs: A study of functional density

2017 ◽  
Vol 26 (46) ◽  
Author(s):  
Víctor Mendoza-Estrada ◽  
Melissa Romero-Baños ◽  
Viviana Dovale-Farelo ◽  
William López-Pérez ◽  
Álvaro González-García ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Density Functional ◽  
Experimental Studies ◽  
Debye Model ◽  
Band Gap Energy ◽  
Functional Theory ◽  
Zinc Blende ◽  
The Density Functional Theory ◽  
The Stability ◽  
Experimental Values

In this research, first-principles calculations were carried out within the density functional theory (DFT) framework, using LDA and GGA, in order to study the structural, elastic, electronic and thermal properties of InAs in the zinc-blende structure. The results of the structural properties (a, B0, ) agree with the theoretical and experimental results reported by other authors. Additionally, the elastic properties, the elastic constants (C11, C12 and C44), the anisotropy coefficient (A) and the predicted speeds of the sound ( , , and ) are in agreement with the results reported by other authors. In contrast, the shear modulus (G), the Young's modulus (Y) and the Poisson's ratio (v) show some discrepancy with respect to the experimental values, although, the values obtained are reasonable. On the other hand, it is evident the tendency of the LDA and GGA approaches to underestimate the value of the band-gap energy in semiconductors. The thermal properties (V, , θD yCV) of InAs, calculated using the quasi-harmonic Debye model, are slightly sensitive as the temperature increases. According to the stability criteria and the negative value of the enthalpy of formation, InAs is mechanically and thermodynamically stable. Therefore, this work can be used as a future reference for theoretical and experimental studies based on InAs.

Numerical and experimental studies on the thermal characteristics of the clutch hydraulic system with provision for oil flow

2019 ◽  
Vol 71 (6) ◽  
pp. 733-740 ◽  
Author(s):  
Biao Ma ◽  
Liang Yu ◽  
Man Chen ◽  
He Yan Li ◽  
Liang Jie Zheng
Keyword(s):  
Thermal Resistance ◽  
Network Model ◽  
Hydraulic System ◽  
Experimental Studies ◽  
Thermal Characteristics ◽  
Parameter Method ◽  
Content Type ◽  
Resistance Network ◽  
Oil Flow ◽  
Resistance Network Model

PurposeThis paper aims to investigate the thermal characteristics of the clutch hydraulic system under various oil flow conditions. Increasing the oil flow is one of the most important approaches to reduce the clutch temperature. However, the effect of the oil flow on the clutch temperature remains to be explored.Design/methodology/approachThe thermal resistance network model and the lumped parameter method are used to study the thermal characteristics of the clutch hydraulic system. The predicted temperature variations of the clutch and the oil are compared with experimental data.FindingsResults demonstrate that the larger the friction power is, the higher the temperatures of the clutch and the oil are. However, the temperature growth rates of the clutch and oil present different trends: the former decreases gradually and the latter increases constantly. Additionally, increasing the oil flow within a certain range gives rise to the decrease of clutch temperature and the increase of oil temperature; nevertheless, their variation trends are gradually weakening. When the oil flow is large enough, it brings a slight effect on the clutch temperature rise.Originality/valueThis paper extends the knowledge into the oil flow supply of the clutch hydraulic system. The conclusions can provide a theoretical guidance for the oil management of the transmission system. Additionally, the thermal resistance network model is also effective and efficient for other hydraulic equipment to predict the temperature variation.

scholarly journals A Study of the Mechanical and Thermal Characteristics of an Al-Si-Fe Alloy Fabricated by Rolling and Heat Treatment

Metals ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 9 ◽  
Author(s):  
Yu Guo ◽  
Ye Wang ◽  
Jieren Yang ◽  
Hongyu Xu ◽  
Maoliang Hu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Properties ◽  
Cast Alloy ◽  
Thermal Characteristics ◽  
Spherical Shape ◽  
Mean Free Path ◽  
Homogeneous Distribution ◽  
Mechanical And Thermal Properties ◽  
Obvious Effect ◽  
T6 Heat Treatment

The effects of a rolling process and heat treatment on the mechanical and thermal properties of an Al-Si-Fe alloy were studied. The achieved thermal conductivity of the as-rolled alloy treated by a T6 heat treatment was 188.22 W/(m·K), which is as good as that of the as-cast alloy treated by the T6 heat treatment directly, mostly because of changes in the silicon morphology. The results also revealed that the lower quantity of precipitated Al8Fe2Si and Mg2Si phases had no obvious effect on the thermal properties of the material because the interphase spaces between precipitated phases were larger than the mean free path of electrons. However, the precipitated second phases influenced the elongation. The best mechanical properties of the Al-Si-Fe alloy were obtained by rolling and T6 treatment. The corresponding best tensile strength, yield strength, and elongation were 244 MPa, 295 MPa, and 9.56%, respectively, which are attributed to the near-spherical shape, small size, homogeneous distribution of the Si particles, and the precipitation strengthening of Mg2Si.

Effect of Ventilation in Protected Escape Ways upon the Thermal Properties of these Spaces

2016 ◽  
Vol 861 ◽  
pp. 409-416
Author(s):  
Marie Rusinová ◽  
Markéta Sedláková ◽  
Miloš Kalousek
Keyword(s):  
Thermal Properties ◽  
Positive Pressure Ventilation ◽  
Thermal Characteristics ◽  
Positive Pressure ◽  
Escape Route

Protected escape routes enable the rescuing of persons to the outside of a building on fire. They are characterized, in particular, by strict requirements relating to the aeration of such spaces. However, the fulfilling of these limits may impact the monitored thermal characteristics of the respective internal areas. The outlined dilemma will be illustrated by way of an example of a protected escape route aerated by positive-pressure ventilation.

Experimental Determination of Thermal Characteristics of Wastewater Sludge for Design of Incineration Plants

2017 ◽  
Vol 21 (3) ◽  
pp. 32-35
Author(s):  
P.V. Khoreva ◽  
I.M. Bernadiner
Keyword(s):  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Experimental Studies ◽  
Thermal Characteristics ◽  
Wastewater Sludge ◽  
Municipal Wastewater Treatment ◽  
Water Problem ◽  
Discharge Regulation ◽  
Regulation Mechanisms ◽  
Municipal Wastewater Treatment Plants

Current trends of improving of wastewater discharge regulation mechanisms in centralized municipal systems of sewage disposal and in water bodies, the tightening of the requirements for the quality of wastewater, stimulate the development of technologies for their treatment. While improving the quality characteristics of the treated water, problem of formation and subsequent disposal of large source of waste – wastewater sludge (WS) – remains unresolved to date. There were presented information confirming the increase in the volumes of WS produced at municipal wastewater treatment plants. There were presented results of experimental studies on the effect of the thermal characteristics of sludge on the process of their incineration.

Pore Structure and Thermal Characteristics of Clay Bricks

2014 ◽  
Vol 982 ◽  
pp. 104-107 ◽  
Author(s):  
Monika Čáchová ◽  
Dana Koňáková ◽  
Eva Vejmelková ◽  
Martin Keppert ◽  
Kirill Polozhiy ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Structural Material ◽  
Physical Properties ◽  
Thermal Characteristics ◽  
Clay Brick ◽  
Pore System ◽  
Clay Bricks ◽  
Vacuum Saturation ◽  
The Difference ◽  
System Characteristics

Clay brick was perhaps to be the first artificial structural material. First bricks were dried by sun; later people had started to burn bricks by fire and in that time further enhancements appeared. This article deals with two kinds of fired clay bricks; basic physical properties, pore system characteristics and thermal properties are studied. The values of basic physical properties by water vacuum saturation vary slightly; bulk density shows values around 1880 kg/m3 and in the case of open porosity it is around 27%. Regarding thermal properties the difference is higher, obtained results of thermal conductivities in dried state vary by about 33%.

Influence of Moisture Content on the Thermal Properties of Concrete Containing Agricultural Waste Materials

2016 ◽  
Vol 677 ◽  
pp. 241-245
Author(s):  
Dana Koňáková ◽  
Monika Čáchová ◽  
Eva Vejmelková
Keyword(s):  
Thermal Properties ◽  
Moisture Content ◽  
Physical Properties ◽  
Agricultural Waste ◽  
Thermal Characteristics ◽  
Waste Materials ◽  
Experimental Measurements ◽  
Transport Parameters ◽  
Cement Replacement ◽  
Coir Pith

This article deals with concrete containing waste material originating in a coir fibres extraction from outer protective peel of a coconut. Coir pith is used as cement replacement in amount of 5% and 10%. The influence of moisture content on the thermal properties of studied concrete is determined by means of experimental measurements of basic physical properties, hygric transport parameters and thermal characteristics. From achieved results it can be concluded, that the higher amount of coir pith is used, the better values of thermal characteristics material show. But at the same time thermal characteristics are more influenced by moisture content.

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