Combinatorial evaluation system for thermal properties of glass materials using a vertical furnace with temperature gradient

In this study, three commercially available innerwears were collected from the market. Their air permeability and thermal properties were evaluated by Kawabata Evaluation System for Fabric (KES-F). Exerimental results revealed that the fibre content played an important role in affecting the air permeability and the thermal properties of the innerwears.

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Temperature Gradient of Concrete Pavement Slab Overlaid with Asphalt Surface Course

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1730-04 ◽

2000 ◽

Vol 1730 (1) ◽

pp. 25-33 ◽

Cited By ~ 1

Author(s):

Tatsuo Nishizawa ◽

Shigeru Shimeno ◽

Akinori Komatsubara ◽

Masashi Koyanagawa

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Thermal Stress ◽

Temperature Gradient ◽

Numerical Simulations ◽

Structural Design ◽

Concrete Slab ◽

Concrete Pavement ◽

Reduction Effect ◽

The Relationship

In the structural design of composite pavement with a concrete pavement slab overlaid with an asphalt surface course, it is very important to estimate the temperature gradient in the concrete slab. An asphalt surface course reduces the temperature gradient in an underlaid concrete slab, resulting in the reduction of thermal stress of the concrete slab. This effect was investigated by temperature measurement in model pavements and by thermal conductivity analysis. Thermal properties were estimated by a backanalysis by using measured temperatures over 1 year. From the numerical simulations varying the thickness of asphalt surface and concrete slab, the relationship between the reduction effect and the asphalt thickness was derived as a function of the thickness of asphalt surface course, which can be used in the structural design of the composite pavement.

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Metamorphism and thermal properties of fresh snow (study in the Moscow region)

Journal Ice and Snow ◽

10.15356/2076-6734-2016-2-199-206 ◽

2016 ◽

Vol 56 (2) ◽

pp. 199-206 ◽

Cited By ~ 1

Author(s):

R. A. Chernov

Keyword(s):

Thermal Conductivity ◽

Thermal Properties ◽

Temperature Gradient ◽

Negative Temperature ◽

Average Temperature ◽

The North ◽

Coefficient Of Thermal Conductivity ◽

European Part Of Russia ◽

Snow Conditions

As a result of laboratory tests were obtained values of the coefficient thermal conductivity (Keff) of new snow for different types of the solid precipitation: plates, needles, stellars, graupels. Snow samples were collected during a snowfall and placed in the freezer. For all types of sediment thermal conductivity of snow is equal to 0.03–0.04 W/m·°C. Transformation of new snow occurs within 10 days at average temperature −10 °C and the gradient temperature of 50–60 °C/m. Under these conditions, the metamorphism leads to an increase the density of snow, size of grains and rounded snow particles. At the beginning of the experiment, the thermal conductivity of snow is linearly increased in proportion to the density of the snow. However, after 3–5 days Keff stabilized at about 0.08–0.09 W/m·°C, although the density of the snow and size of grains continued to increase. This effect occurs with the appearance of faceted crystals and loosening of snow. In the future, while maintaining a negative temperature coefficient of thermal conductivity remained unchanged. Thus, the temperature gradient metamorphism affect to the thermal conductivity snow, which plays an important role in maintaining the thermal insulation properties of snow cover. The article describes the formula to calculate the thermal conductivity of the snow conditions in the temperature gradient metamorphism. Such conditions are characteristic of the vast expanses of the north and northeast of the European part of Russia. On the basis of long-term observations in Moscow shows the average minimum and maximum values for the density of the snow woods and fields on the basis of which can be calculated for the thermal properties of the snow.

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Primary and secondary dendrite spacing of Ni-based superalloy single crystals

Journal of the Serbian Chemical Society ◽

10.2298/jsc0901061k ◽

2009 ◽

Vol 74 (1) ◽

pp. 61-69 ◽

Cited By ~ 5

Author(s):

Slobodanka Kostic ◽

Aleksandar Golubovic ◽

Andreja Valcic

Keyword(s):

Crystal Growth ◽

Temperature Gradient ◽

Single Crystals ◽

Gradient Method ◽

Dendrite Spacing ◽

Published Data ◽

Bridgman Technique ◽

Spontaneous Nucleation ◽

Vertical Furnace ◽

Growth Experiments

Ni-based superalloy single crystals were grown by different methods (gradient method and Bridgman technique with spontaneous nucleation and with seed). In all crystal growth experiments using the Bridgman technique, the temperature gradient along the vertical furnace axes was constant (G = 33.5 ?C/cm). The obtained single crystals were cut, mechanical and chemical polished, and chemically etched. Using a metallographic microscope, the spacing of the primary and secondary dendrites was investigated. The dendrite arm spacing (DAS) was determined using a Quantimet 500 MC. The obtained results are discussed and compared with published data.

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An insight into thermal properties of BC3-graphene hetero-nanosheets: a molecular dynamics study

Scientific Reports ◽

10.1038/s41598-021-02576-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Maryam Zarghami Dehaghani ◽

Fatemeh Molaei ◽

Farrokh Yousefi ◽

S. Mohammad Sajadi ◽

Amin Esmaeili ◽

...

Keyword(s):

Thermal Properties ◽

Temperature Gradient ◽

Grain Boundary ◽

Thermal Resistance ◽

Grain Boundaries ◽

Defect Density ◽

Topological Defects ◽

Interfacial Thermal Resistance ◽

Effect Of Temperature ◽

Kapitza Resistance

AbstractSimulation of thermal properties of graphene hetero-nanosheets is a key step in understanding their performance in nano-electronics where thermal loads and shocks are highly likely. Herein we combine graphene and boron-carbide nanosheets (BC3N) heterogeneous structures to obtain BC3N-graphene hetero-nanosheet (BC3GrHs) as a model semiconductor with tunable properties. Poor thermal properties of such heterostructures would curb their long-term practice. BC3GrHs may be imperfect with grain boundaries comprising non-hexagonal rings, heptagons, and pentagons as topological defects. Therefore, a realistic picture of the thermal properties of BC3GrHs necessitates consideration of grain boundaries of heptagon-pentagon defect pairs. Herein thermal properties of BC3GrHs with various defects were evaluated applying molecular dynamic (MD) simulation. First, temperature profiles along BC3GrHs interface with symmetric and asymmetric pentagon-heptagon pairs at 300 K, ΔT = 40 K, and zero strain were compared. Next, the effect of temperature, strain, and temperature gradient (ΔT) on Kaptiza resistance (interfacial thermal resistance at the grain boundary) was visualized. It was found that Kapitza resistance increases upon an increase of defect density in the grain boundary. Besides, among symmetric grain boundaries, 5–7–6–6 and 5–7–5–7 defect pairs showed the lowest (2 × 10–10 m2 K W−1) and highest (4.9 × 10–10 m2 K W−1) values of Kapitza resistance, respectively. Regarding parameters affecting Kapitza resistance, increased temperature and strain caused the rise and drop in Kaptiza thermal resistance, respectively. However, lengthier nanosheets had lower Kapitza thermal resistance. Moreover, changes in temperature gradient had a negligible effect on the Kapitza resistance.

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Morphology, thermal properties and mechanical relaxations of metallocene syndiotactic polypropylenes

e-Polymers ◽

10.1515/epoly.2012.12.1.507 ◽

2012 ◽

Vol 12 (1) ◽

Author(s):

Ester López Moya ◽

José M. Gómez-Elvira ◽

Rosario Benavente ◽

Ernesto Pérez

Keyword(s):

Thermal Properties ◽

Temperature Gradient ◽

Small Proportion ◽

Molar Mass ◽

Processing Conditions ◽

Syndiotactic Polypropylene ◽

Relative Contribution ◽

Two Samples ◽

Concurrent Processes ◽

Crystallisation Rate

AbstractThe complex polymorphic behaviour of four syndiotactic polypropylene (sPP) samples have been analysed by means of DSC and WAXD techniques. Two samples (sPP1, sPP2) were synthesised via metallocene polymerization by using the ansa-zirconocene Ph2C(Cp)(9-Flu)ZrCl2 as catalyst. Finally, two additional specimens with different molar masses (sPP1-Fr1, sPP1-Fr2) were prepared from the most syndiotactic sPP1 sample by temperature gradient extraction. The WAXD analysis shows that together with the orthorhombic form I, form II can coexist in a variable but small proportion depending on both the chain features and the processing conditions. The relative contribution of the disordered and the ordered types of form I is also dictated by molar mass, configurational microstructure as well as processing conditions. The observed changes in the thermal properties as measured by DSC and in the mechanic-dynamical relaxations of the samples, on slowing the crystallisation rate down, can be rationalised in terms of two concurrent processes, namely the perfection undergone by the crystals and the segregation of the amorphous phase.

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