scholarly journals EXPERIMENTAL INVESTIGATION AND NON-LOCAL MODELLING OF THE THERMOMECHANICAL BEHAVIOUR OF REFRACTORY CONCRETE

2021 ◽  
pp. 1-9
Author(s):  
Belgacem Mamen
Keyword(s):  
Experimental Investigation ◽  
Refractory Concrete ◽  
Thermomechanical Behaviour ◽  
Non Local

Mechanical and Fracture Characteristics of Refractory Concrete after the Action of Various Temperature Loading

2018 ◽  
Vol 760 ◽  
pp. 102-107
Author(s):  
Ondřej Holčapek
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Compressive Strength ◽  
Dynamic Modulus ◽  
Thermal Loading ◽  
Refractory Concrete ◽  
Fracture Characteristics ◽  
Residual Properties ◽  
Aluminous Cement ◽  
Refractory Composite

This article deals with the experimental investigation of residual mechanical properties of refractory composite after the action of various thermal loading. Specimens with dimension 40 × 40 × 160 mm were produced from composite containing basalt fibres and aggregate, aluminous cement and metakaolin. Different group of specimens were exposed to various temperatures 105 °C, 200 °C, 300 °C, 400 °C, 500 °C and 600 °C for three hours. Different temperature caused various changes in chemical composition of concrete that can result into decrease of mechanical properties. Bulk density, flexural strength, compressive strength, fracture energy and dynamic modulus of elasticity were investigated after each type of thermal loading. After the action of 600 °C all investigated residual properties achieved lowest values. Based on performed experiments we can conclude that the main decrease of mechanical properties take place after the action of 400 °C.

Texture of granular surface flows: experimental investigation and biphasic non-local model

2003 ◽  
Vol 4 (4) ◽  
pp. 183-190 ◽  
Author(s):  
D. Bonamy ◽  
F. Daviaud ◽  
L. Laurent ◽  
P. Mills
Keyword(s):  
Experimental Investigation ◽  
Local Model ◽  
Surface Flows ◽  
Non Local ◽  
Granular Surface

Toward High-Resolution Low-Voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 218-219
Author(s):  
Zhifeng Shao
Keyword(s):  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Limiting Factor ◽  
Operating Voltage ◽  
Probe Radius ◽  
Non Local ◽  
Electron Microscopes ◽  
Image Position ◽  
Scanning Electron Microscopes

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as

Chromatic aberration and low-voltage SEM

1987 ◽  
Vol 45 ◽  
pp. 546-547
Author(s):  
Zhifeng Shao ◽  
A.V. Crewe
Keyword(s):  
Electron Energy ◽  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Primary Electron ◽  
Probe Size ◽  
Non Local ◽  
Optical Treatment ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

For scanning electron microscopes, it is plausible that by lowering the primary electron energy, one can decrease the volume of interaction and improve resolution. As shown by Crewe /1/, at V0 =5kV a 10Å resolution (including non-local effects) is possible. To achieve this, we would need a probe size about 5Å. However, at low voltages, the chromatic aberration becomes the major concern even for field emission sources. In this case, δV/V = 0.1 V/5kV = 2x10-5. As a rough estimate, it has been shown that /2/ the chromatic aberration δC should be less than ⅓ of δ0 the probe size determined by diffraction and spherical aberration in order to neglect its effect. But this did not take into account the distribution of electron energy. We will show that by using a wave optical treatment, the tolerance on the chromatic aberration is much larger than we expected.

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