scholarly journals Basal Surface-Layer Properties in Flowing Snow

1983 ◽  
Vol 4 ◽  
pp. 158-162 ◽  
Author(s):  
T. E. Lang ◽  
J. D. Dent
Keyword(s):  
Surface Layer ◽  
Velocity Profile ◽  
Kinematic Viscosity ◽  
Granular Layer ◽  
Strong Dependence ◽  
Surface Hardness ◽  
Laboratory Simulation ◽  
Shear Locking ◽  
Low Velocity ◽  
Basal Surface

Experiments on the behavior of the active granular layer between flowing snow and sintered basal snow were performed by laboratory simulation of the layer. Layer thickness, its velocity profile, kinematic viscosity, and shear locking stress were estimated fron low-velocity tests. Variation in these parameters over a temperature range from -5 to -18°C, for overburden pressures of 1180 and 2360 N m−2, and for surface hardness in the range 0.4 to 4.0 N m−2 were evaluated. Results show strong dependence between surface hardness and layer viscosity, and near linear dependence between shear locking stress and overburden pressures.

scholarly journals Basal Surface-Layer Properties in Flowing Snow

1983 ◽  
Vol 4 ◽  
pp. 158-162 ◽  
Author(s):  
T. E. Lang ◽  
J. D. Dent
Keyword(s):  
Surface Layer ◽  
Velocity Profile ◽  
Kinematic Viscosity ◽  
Granular Layer ◽  
Strong Dependence ◽  
Surface Hardness ◽  
Laboratory Simulation ◽  
Shear Locking ◽  
Low Velocity ◽  
Basal Surface

Experiments on the behavior of the active granular layer between flowing snow and sintered basal snow were performed by laboratory simulation of the layer. Layer thickness, its velocity profile, kinematic viscosity, and shear locking stress were estimated fron low-velocity tests. Variation in these parameters over a temperature range from -5 to -18°C, for overburden pressures of 1180 and 2360 N m−2, and for surface hardness in the range 0.4 to 4.0 N m−2were evaluated. Results show strong dependence between surface hardness and layer viscosity, and near linear dependence between shear locking stress and overburden pressures.

Increasing Hardness of Surface Layer of Low-Carbon Steel by Account of Plasma Treatment of Coating Modification

2021 ◽  
Vol 316 ◽  
pp. 794-802
Author(s):  
Andrey E. Balanovsky ◽  
Van Trieu Nguyen
Keyword(s):  
Surface Layer ◽  
Thermal Treatment ◽  
Plasma Treatment ◽  
Plasma Heating ◽  
High Surface ◽  
Surface Hardness ◽  
High Hardness ◽  
Diffusion Region ◽  
Low Carbon ◽  
Wide Range

The Purpose of paper is to conduct studies to assess the possibility of increasing the hardness of the surface layer of steel St3 grade by plasma heating of the applied surface coating containing powder alloy PR-N80X13S2R. Mixtures of pasta were divided into 2 groups: for furnace chemical-thermal treatment and plasma surface melting. The study of the microstructure showed a difference in the depth of the saturated layer, depending on the processing method, during chemical-thermal treatment-1 mm, plasma fusion - 2 mm. The results of measuring the surface micro-hardness showed that, the obtained coating from a mixture of PR-N80X13S2R + Cr2O3 + NH4Cl has a uniform high surface hardness (31-64 HRC), from a mixture of only PR-N80X13S2R - the surface hardness varies in a wide range (15-60 HRC). The study of the microhardness of the cross section of the surface layer showed that, the diffusion region: from a mixture of powder PR-N80X13S2R + Cr2O3 + NH4Cl has uniform hardness (450-490 HV); from a mixture of PR-N80X13S2R - hardness increases in the depth of the molten region (from 300 to 600 HV), and sharply decreases in the heat affected zone (210-170 HV). The use of PR-N80X13S2R alloy powder as the main component in the composition of the paste deposited on the St3 surface during plasma treatment leads to the formation of a doped surface layer with high hardness.

scholarly journals The lift on a small sphere in a slow shear flow

1965 ◽  
Vol 22 (2) ◽  
pp. 385-400 ◽  
Author(s):  
P. G. Saffman
Keyword(s):  
Shear Flow ◽  
Velocity Profile ◽  
Kinematic Viscosity ◽  
Lift Force ◽  
Flow Direction ◽  
Functional Dependence ◽  
Small Sphere ◽  
Translation Velocity ◽  
Parabolic Velocity Profile ◽  
Direction Opposite

It is shown that a sphere moving through a very viscous liquid with velocity V relative to a uniform simple shear, the translation velocity being parallel to the streamlines and measured relative to the streamline through the centre, experiences a lift force 81·2μVa2k½/v½ + smaller terms perpendicular to the flow direction, which acts to deflect the particle towards the streamlines moving in the direction opposite to V. Here, a denotes the radius of the sphere, κ the magnitude of the velocity gradient, and μ and v the viscosity and kinematic viscosity, respectively. The relevance of the result to the observations by Segrée & Silberberg (1962) of small spheres in Poiseuille flow is discussed briefly. Comments are also made about the problem of a sphere in a parabolic velocity profile and the functional dependence of the lift upon the parameters is obtained.

P-wave velocity profile at very shallow depths in sand dunes

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. U129-U137
Author(s):  
Sherif M. Hanafy ◽  
Ammar El-Husseiny ◽  
Mohammed Benaafi ◽  
Abdullatif Al-Shuhail ◽  
Jack Dvorkin
Keyword(s):  
Velocity Profile ◽  
Wave Velocity ◽  
Sand Dunes ◽  
Seismic Signal ◽  
Compressional Wave ◽  
Dominant Frequency ◽  
P Wave ◽  
Beach Sand ◽  
Low Velocity ◽  
Measured Velocity

We have addressed the problem of measuring the compressional wave velocity at a very shallow depth in unconsolidated dune sand. Because the overburden stress is very small at shallow depths, the respective velocity is small and the seismic signal is weak. This is why such data are scarce, in the lab and in the field. Our approach is to stage a high-resolution seismic experiment with a dense geophone line with spacing varying between 10 and 25 cm, allowing us to produce a velocity-depth relation in the upper 1 m interval. These results are combined with another survey in which the geophone spacing is 2 m and the dominant frequency is an order of magnitude lower than in the first survey. The latter results give us the velocity profile in the deeper interval between 1 and 7 m, down to the base of the dune. The velocity rapidly increases from about 48 m/s in the first few centimeters to 231 m/s at 1 m depth and then gradually increases to 425 m/s at 7 m depth. This is the first time when such a low velocity has been recorded at extremely shallow depths in sand in situ. The velocity profile thus generated is statistically fitted with a simple analytical equation. Our velocity values are higher than those published previously for beach sand. We find that using replacement or tomogram velocities instead of an accurately measured velocity profile may result in 23%–44% error in the static correction.

scholarly journals Functionalized Surface Layer on Poplar Wood Fabricated by Fire Retardant and Thermal Densification. Part 1: Compression Recovery and Flammability

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 955 ◽  
Author(s):  
Demiao Chu ◽  
Jun Mu ◽  
Stavros Avramidis ◽  
Sohrab Rahimi ◽  
Shengquan Liu ◽  
...  
Keyword(s):  
Surface Layer ◽  
Combined Treatment ◽  
Surface Hardness ◽  
Treated Wood ◽  
Fire Retardant ◽  
Densified Wood ◽  
Fire Retardancy ◽  
Alternative Approach ◽  
Vertical Density ◽  
Functionalized Surface

To enhance compression stability and fire retardancy of densified wood, a new modification method i.e., combined nitrogen–phosphorus (NP) fire retardant pre-impregnation with surface thermo-mechanical densification is used to fabricate a certain thickness of functionalized surface layer on poplar. This combined treated wood is investigated via vertical density profile (VDP), and the compression stability is revealed by both soaking test and cone analysis. Results demonstrate that the combined treatment hardened the surface of wood and reformed the interface combination of the NP with the wood cell wall, thus making the surface tissue more close-grained. Fire retardancy was also enhanced; the total heat release and CO generation values decreased by 21.9% and 68.4%, respectively, when compared with that of solely NP-treated wood. Moreover, surface hardness increased by 15.8%, and the recovery of surface hardness and thickness were 56.8% and 77.2% lower than that of simply densified wood. It appears that this NP-involved thermal densification could be considered as an alternative approach to enhance both the compression stability and fire resistance of wood.

scholarly journals A Study Surface Layer and Hardness Produced by Induction Hardened S45C Steel

2014 ◽  
Vol 664 ◽  
pp. 43-47 ◽  
Author(s):  
Alain Kusmoko ◽  
Rosfian Arsyah Dahar ◽  
Hui Jun Li ◽  
Syamsul Hadi
Keyword(s):  
Surface Layer ◽  
Internal Stress ◽  
Induction Heating ◽  
Retained Austenite ◽  
Surface Hardness ◽  
Case Depth ◽  
Chemical Compositions ◽  
Different Temperatures ◽  
Significant Case ◽  
Cooling Speed

A cylinder of Carbon Steel S45C with a ferrite and pearlite structure was analysed to improve the hardness and surface layer as well as the toughness. Accordingly, it is important to undertake a heat treatment process for the hardness and surface layer of this steel. The heat teatment process was carried out using induction heating with five different temperatures of 800°C, 900°C, 1000°C, 1100°C and 1200 °C followed by water quenching with certain cooling speed. The chemical compositions and microstructures of these samples were characterized by spectrometer and optical microscopy. The microhardness of the samples was measured and the surface treatment of the samples was examined using an induction heating furnace. The results showed significant case depth and surface hardness as well as microstructure with martensite and retained austenite that is hard and brittle because of internal stress. Further, to reduce the amount of retained austenite and internal stress, it is necessary to carry out tempering of 300°C, 500°C and 700°C in order to produce toughness of the steel with slightly reduce in hardness.

Unconventional Short-Term Glow Discharge Nitriding of 316L Austenitic Steel

2010 ◽  
Vol 654-656 ◽  
pp. 366-369 ◽  
Author(s):  
Tadeusz Frączek ◽  
Michał Olejnik ◽  
Jarosław Jasiński
Keyword(s):  
Surface Layer ◽  
Glow Discharge ◽  
Austenitic Steel ◽  
Profile Analysis ◽  
Surface Hardness ◽  
Hardness Profile ◽  
Nitrogen Diffusion ◽  
Surface Layers ◽  
Hardness Tests ◽  
Layer Structures

The AISI 316L grade austenitic steel after glow discharge nitriding at a temperature of T = 598 K and for duration of  = 10,8 ks, for different variants of specimen arrangement in the glow-discharge chamber was investigated. In the first variant specimens were placed on the cathode and in the second variant specimens were positioned also on the cathode, but shielded with a booster screen. In order to assess the effectiveness of nitriding process variants a profile analysis examination of obtained surface layers, surface hardness tests and surface layer hardness profile examination, analysis of surface layer structures and corrosion resistance tests were carried out. It was found that application of a booster screen effects in a nitrogen diffusion depth increment into the 316L austenitic steel, resulting in a surface layer thickness escalation.

Flow partitioning in symmetric cascades of branches

1981 ◽  
Vol 51 (3) ◽  
pp. 598-606 ◽  
Author(s):  
B. Snyder ◽  
D. R. Dantzker ◽  
M. J. Jaeger
Keyword(s):  
Smooth Muscle ◽  
Velocity Profile ◽  
Kinematic Viscosity ◽  
Limited Range ◽  
Regional Ventilation ◽  
Bronchial Smooth Muscle ◽  
Flow Rates ◽  
Inlet Velocity ◽  
Resistance Model ◽  
Fine Tune

We have found markedly nonuniform partitioning of flow in idealized models of physiological cascades of branches. Liquids having viscosities of 0.8–7.0 cP were used to investigate this effect systematically in a regime characterizing a limited range of pulmonary flows, comprising inlet flow rates of 500–3,000 ml/min and branch diameters of 1.0 cm ID. Factors that affect the nonuniformity of inspiratory flow include inlet velocity profile and flow rate, cascade aspect (L/D) ratio, exit pressure distribution, and, to a lesser extent, kinematic viscosity (mu/rho). More qualitative observations using sinusoidally oscillating airflow revealed inspiratory and expiratory flow patterns to be quite dissimilar, emphasizing the inadequacy of a resistance model of flow partitioning based on Kirchhoff's law. These results might suggest, in part, why regional ventilation in man is flow or frequency dependent and how bronchial smooth muscle could fine tune regional ventilation.

THE EFFECT OF MICROWAVE ELECTROMAGNETIC FIELD ON THE HARDNESS OF CARBON FIBER-REINFORCED PLASTIC WITH LIGHTNING PROTECTION GRID DISTRIBUTED IN THE SURFACE LAYER

2020 ◽  
Vol 0 (4) ◽  
pp. 5-11
Author(s):  
I.V. ZLOBINA ◽  
Keyword(s):  
Electromagnetic Field ◽  
Surface Layer ◽  
Carbon Fiber ◽  
Surface Hardness ◽  
Lightning Protection ◽  
Fiber Reinforced ◽  
Short Term Exposure ◽  
Structural Density ◽  
Carbon Fiber Reinforced ◽  
The Impact

Based on the analysis of scientific and technical literature and trends in the development of multi-purpose aircrafts, we can see a steady extension of the use of polymer composite materials (PCM) in their design. The importance of lightning protection is noted for aircrafts, the skin of which consists mainly of the PCM, and it is shown that one of the common means is a lightning protection coating (LPC) in the form of a metal grid distributed in the PCM surface layer. Anisotropy of PCM properties and reduced fracture toughness in comparison with metals necessitates the improvement of PCM compositions and technologies of their formation as well as the development of methods for final hardening treatment in the cured state, which can be effectively performed under the effect of microwave electromagnetic field. Consideration is given to the influence of a short-term exposure to microwave electromagnetic field on the stability of carbon fiber-reinforced PCM with PLC against impact loads, as well as on the surface hardness. Our findings show a decrease in the damaged area of the impact zone by 40-60% and the absence of microcracking and delamination as well as an increase in hardness by 7.8%. Particular emphasis is placed on a 3-fold decrease in the spread of hardness values after the microwave exposure, this indicating a significant increase in the uniformity of this important characteristic for the component performance. As a mechanism of these modifications, it is proposed to reduce the pore size and porosity and to increase the number of points of contact interaction between matrix and fiber agglomerates that ensure an increase in the structural density.

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