Effect of High Temperatures on Microstructure of Repair Mortars Containing Artificial Aggregate Based on Sintered Ash

2015 ◽  
Vol 1100 ◽  
pp. 147-151
Author(s):  
Jiří Bydžovský ◽  
Tomáš Melichar ◽  
Ámos Dufka ◽  
Michaela Fiedlerová
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Analytical Methods ◽  
Maximum Temperature ◽  
Cement Matrix ◽  
Lightweight Aggregates ◽  
Temperature Influence ◽  
Repair Materials ◽  
Repair Mortars

The research presented in this article is focused on analyzing of high temperature influence on behaviour and microstructure of polymeric-cement matrix based repair materials containing lightweight aggregates on the basis of sintered ash. Also admixtures and polymeric fibres were applied to obtain the required parameters. The study of microstructure and its changes was realized using SEM, XRD and DTA analytical methods. Maximum temperature of exposure environment of the tested mortars was 1000°C, while cooling of specimens was gradual.

The influence of pasture distribution and temperature on habitat selection by feral pigs in a semi-arid environment

1998 ◽  
Vol 25 (5) ◽  
pp. 547 ◽  
Author(s):  
Nick Dexter
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Radio Telemetry ◽  
Arid Environment ◽  
Food Distribution ◽  
Maximum Temperature ◽  
Feral Pigs ◽  
North West ◽  
Hot Weather ◽  
Two Parameters

The two parameters believed to influence habitat utilisation by feral pigs and wild boar (Sus scrofa) are protection from high temperatures and distribution of food. However, whether there is an interaction between these parameters is unknown. To examine the influence of high temperature on habitat utilisation, the use of four rangeland habitats (shrubland, woodland, riverine woodland, and ephemeral swamps) by feral pigs in north-west New South Wales, Australia, was measured by radio-telemetry during and after a drought. In each habitat, protection from high temperature was indexed once by vegetation cover, at three strata, while over the course of the study, food distribution was indexed by estimating pasture biomass in each habitat. Riverine woodland provided the most shelter from high temperature, followed by woodland, shrubland and ephemeral swamps. On average, ephemeral swamps had the highest pasture biomass, followed by riverine woodland, shrubland and woodland. The amount of pasture in each habitat increased after the drought but changed at different rates. During autumn, spring and summer feral pigs preferred riverine woodland but in winter shrubland was preferred. Multivariate regression indicated that habitat utilisation was significantly influenced by pasture biomass in shrubland and mean maximum temperature in the study area. The results suggest that feral pigs are restricted by high temperatures to more shady habitats during hot weather but when the constraint of high temperature is relaxed they distribute themselves more according to the availability of food.

scholarly journals Temperature Trend Analysis and Extreme High Temperature Prediction Based on Weighted Markov Model in Lanzhou

2021 ◽  
Author(s):  
Zhiqiang Pang ◽  
Zhaoxu Wang
Keyword(s):  
High Temperature ◽  
Markov Model ◽  
Prediction Model ◽  
Trend Analysis ◽  
High Temperatures ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Temperature Prediction ◽  
Real Situation ◽  
Change Trend

Abstract In this study, temporIn this study, temporal trend analysis was conducted on the annual and quarterly meteorological variables of Lanzhou from 1951 to 2016, and a weighted Markov model for extremely high-temperature prediction was constructed. Several non-parametric methods were used to analyze the time trend. Considering that sequence autocorrelation may affect the accuracy of the trend test, we performed an autocorrelation test and carried out trend analysis for sequences with autocorrelation after removing correlation. The results show that the maximum temperature, minimum temperature, and average temperature in Lanzhou have a significant rising trend and show different performances in each season. In detail, the maximum temperature in summer does not have a significant change trend, while the minimum temperature in winter is the most significant rising trend, which leads to more and more ”warm winter” phenomenon. Finally, we construct a weighted Markov prediction model for extremely high temperatures and obtain the conclusion that the prediction results by the model are consistent with the real situation. and show different performances in each season. In detail, the maximum temperature in summer does not have a significant change trend, while the minimum temperature in winter is the most significant rising trend, which leads to more and more ”warm winter” phenomenon. Finally, we construct a weighted Markov prediction model for extremely high temperatures and obtain the conclusion that the prediction results by the model are consistent with the real situation.

scholarly journals Growth Performance and Concentrations of Thyroid Hormones and Growth Hormone in Plasma of Broilers at High Temperatures

1987 ◽  
Vol 40 (4) ◽  
pp. 443 ◽  
Author(s):  
A P Sinurat ◽  
D Balnave ◽  
GH McDowell
Keyword(s):  
Growth Hormone ◽  
High Temperature ◽  
Plasma Concentration ◽  
High Temperatures ◽  
Broiler Chickens ◽  
High Ambient Temperature ◽  
Molar Ratio ◽  
Maximum Temperature ◽  
Food Conversion ◽  
Plasma Growth Hormone

Responses of broiler chickens to a high ambient temperature (35�C) were measured in two experiments. In one experiment temperatures were increased abruptly from 21�C to a daily range of 21-35�C whereas, in the other, temperatures were increased more gradually over 6 days. The high temperatures were maintained for 5 h/day. In' both experiments, birds exposed to the high temperatures ate less food and gained less liveweight than birds maintained at 21�C. Efficiency of food conversion to liveweight gain and body composition were not affected by high temperature but there was a tendency for thyroid weight to decrease. Overall, the plasma concentration of triiodothyronine (T 3) decreased and the plasma concentration of thyroxine (T4) increased, resulting in a decreased T/T4 molar ratio, during exposure to high temperature. The concentration of plasma growth hormone, but not plasma reverse T 3' was increased by high temperature. The initial responses to increased temperature were variable, with birds exposed more gradually adjusting relatively well until the maximum temperature was increased to 35�C. All heated birds readjusted quickly to the daily reduction in temperature to 21�C.

High-temperature survival is limited by food availability in first-instar locust nymphs

2010 ◽  
Vol 58 (5) ◽  
pp. 323 ◽  
Author(s):  
James D. Woodman
Keyword(s):  
High Temperature ◽  
Food Availability ◽  
High Temperatures ◽  
Water Loss ◽  
Local Population ◽  
Maximum Temperature ◽  
Upper Limit ◽  
First Instar ◽  
Low Humidity ◽  
Very High

The Australian plague locust, Chortoicetes terminifera (Walker), is often exposed to high temperature and low humidity in semiarid and arid environments. Early-instar survival under these conditions is an important prerequisite for the formation of high-density aggregations in summer and autumn generations. The present study investigates how first-instar C. terminifera respond to high temperature and low humidity using measures of total body water content, physiological and behavioural transitions during temperature increase, critical upper limit, and mortality relative to food availability. The critical upper limit for fed nymphs was very high at 53.3 ± 1.0°C, with death preceded by a clear progression of changes in behaviour, gas exchange, water loss and excretion. At more ecologically relevant high temperatures, food availability allowed nymphs to behaviourally respond to increased water loss, and the resulting physiological maintenance of water reserves provided cross-tolerance to heat relative to exposure duration and maximum temperature as well as the rate of warming. While very high mortality was recorded at ≥45°C in 6-h direct-exposure experiments, a highly exposed and very poorly vegetated summer environment would be required for local population failures from current high temperatures and low humidity alone.

scholarly journals Effect of Nano-SiO2 on the Microstructure and Mechanical Properties of Concrete under High Temperature Conditions

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 166
Author(s):  
Piotr Brzozowski ◽  
Jarosław Strzałkowski ◽  
Piotr Rychtowski ◽  
Rafał Wróbel ◽  
Beata Tryba ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Coarse Aggregate ◽  
Mechanical Performance ◽  
Mercury Porosimetry ◽  
Thermal Characteristics ◽  
Total Porosity ◽  
Cement Matrix ◽  
Cement Concrete ◽  
Structural Tests

The aim of the research was to determine how the admixture of nanosilica affects the structure and mechanical performance of cement concrete exposed to high temperatures (200, 400, 600, and 800 °C). The structural tests were carried out on the cement paste and concrete using the methods of thermogravimetric analysis, mercury porosimetry, and scanning electron microscopy. The results show that despite the growth of the cement matrix’s total porosity with an increasing amount of nanosilica, the resistance to high temperature improves. Such behavior is the result of not only the thermal characteristics of nanosilica itself but also of the porosity structure in the cement matrix and using the effective method of dispersing the nanostructures in concrete. The nanosilica densifies the structure of the concrete, limiting the number of the pores with diameters from 0.3 to 300 μm, which leads to limitation of the microcracks, particularly in the coarse aggregate-cement matrix contact zone. This phenomenon, in turn, diminishes the cracking of the specimens containing nanosilica at high temperatures and improves the mechanical strength.

scholarly journals Uniaxial Tensile Behavior, Flexural Properties, Empirical Calculation and Microstructure of Multi-Scale Fiber Reinforced Cement-Based Material at Elevated Temperature

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1827
Author(s):  
Li Li ◽  
Mehran Khan ◽  
Chengying Bai ◽  
Ke Shi
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Tensile Properties ◽  
High Temperatures ◽  
Cement Matrix ◽  
Uniaxial Tensile ◽  
Flexural Properties ◽  
Fiber Reinforced ◽  
Multi Scale ◽  
Reinforced Cement

Fire is one of the most unfavorable conditions that cement-based composites can face during their service lives. The uniaxial tensile and flexural tensile properties of the steel-polyvinyl alcohol fiber-calcium carbonate whisker (CW) multi-scale fiber reinforced cement matrix composites (MSFRCs) under high temperatures are studied, including strength, deformation capacity, energy dissipation capacity, and its ability to be assessed through the empirical calculation method. The study showed that with the increase of the treatment temperature, the MSFRC residual bending strength, bending toughness, and tensile strength decreased overall, but the decline was slow at 600 °C. The peak flexural deflection and peak tensile strain of MSFRC first reduced and then increased with the increase of the temperature. As the temperature increased, the nominal stiffness of MSFRC bending and straight gradually reduced, and the rate of decline was faster than that of its strength. However, the uniaxial tensile properties were more sensitive to the temperature and degraded more rapidly. A quantitative relationship was established between MSFRC residual bending, tensile strength, and temperature. A comparison with existing research results shows that MSFRC has achieved an ideal effect of high temperature resistance. The multi-scale hybrid fiber system significantly alleviates the deterioration of cement-based composite’s mechanical properties under high temperatures. With the help of an optical microscope and scanning electron microscope (SEM), the high temperature influence mechanism on the uniaxial tensile and flexural properties of MSFRC was revealed.

High Temperature n- and p-type Doped Microcrystalline Silicon Layers Grown by VHF PECVD Layer-by-Layer Deposition

2003 ◽  
Vol 762 ◽  
Author(s):  
A. Gordijn ◽  
J.K. Rath ◽  
R.E.I. Schropp
Keyword(s):  
Activation Energy ◽  
High Temperature ◽  
High Temperatures ◽  
Continuous Wave ◽  
Hydrogen Plasma ◽  
Silicon Layer ◽  
Dark Conductivity ◽  
High Deposition Rate ◽  
Layer By Layer ◽  
Microcrystalline Silicon

AbstractDue to the high temperatures used for high deposition rate microcrystalline (μc-Si:H) and polycrystalline silicon, there is a need for compact and temperature-stable doped layers. In this study we report on films grown by the layer-by-layer method (LbL) using VHF PECVD. Growth of an amorphous silicon layer is alternated by a hydrogen plasma treatment. In LbL, the surface reactions are separated time-wise from the nucleation in the bulk. We observed that it is possible to incorporate dopant atoms in the layer, without disturbing the nucleation. Even at high substrate temperatures (up to 400°C) doped layers can be made microcrystalline. At these temperatures, in the continuous wave case, crystallinity is hindered, which is generally attributed to the out-diffusion of hydrogen from the surface and the presence of impurities (dopants).We observe that the parameter window for the treatment time for p-layers is smaller compared to n-layers. Moreover we observe that for high temperatures, the nucleation of p-layers is more adversely affected than for n-layers. Thin, doped layers have been structurally, optically and electrically characterized. The best n-layer made at 400°C, with a thickness of only 31 nm, had an activation energy of 0.056 eV and a dark conductivity of 2.7 S/cm, while the best p-layer made at 350°C, with a thickness of 29 nm, had an activation energy of 0.11 V and a dark conductivity of 0.1 S/cm. The suitability of these high temperature n-layers has been demonstrated in an n-i-p microcrystalline silicon solar cell with an unoptimized μc-Si:H i-layer deposited at 250°C and without buffer. The Voc of the cell is 0.48 V and the fill factor is 70 %.

NICROFER 5520 Co

Alloy Digest ◽  
1995 ◽  
Vol 44 (3) ◽  
Keyword(s):  
High Temperature ◽  
Chemical Composition ◽  
Physical Properties ◽  
Tensile Properties ◽  
High Temperatures ◽  
Heat Treating ◽  
High Temperature Corrosion ◽  
Creep Properties ◽  
Nickel Chromium ◽  
Temperature Performance

Abstract NICROFER 5520 Co is a nickel-chromium-cobalt-molybdenum alloy with excellent strength and creep properties up to high temperatures. Due to its balanced chemical composition the alloy shows outstanding resistance to high temperature corrosion in the form of oxidation and carburization. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Ni-480. Producer or source: VDM Technologies Corporation.

CARLSON ALLOY C601

Alloy Digest ◽  
1994 ◽  
Vol 43 (7) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Stress Corrosion ◽  
Tensile Properties ◽  
High Temperatures ◽  
Stress Corrosion Cracking ◽  
Heat Treating ◽  
Resistance To Stress ◽  
Extended Exposure ◽  
Sulfur Containing

Abstract Carlson Alloy C601 is characterized by high tensile, yield and creep-rupture strengths for high temperature service. The alloy is not embrittled by extended exposure to high temperatures and has excellent resistance to stress-corrosion cracking, to carburizing, nitriding and sulfur containing environments. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming, heat treating, machining, and joining. Filing Code: Ni-458. Producer or source: G.O. Carlson Inc.

INCOTHERM TD

Alloy Digest ◽  
2005 ◽  
Vol 54 (11) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Tensile Properties ◽  
Oxidation Resistance ◽  
High Temperatures ◽  
Rare Earths ◽  
Temperature Performance

Abstract Incotherm TD is a thermocouple-sheathing alloy with elements of silicon and rare earths to enhance oxidation resistance at high temperatures. This datasheet provides information on composition, physical properties, and tensile properties as well as deformation. It also includes information on high temperature performance and corrosion resistance as well as forming. Filing Code: Ni-628. Producer or source: Special Metals Corporation.

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