Filter testing of broadly graded cohesionless tills

1984 ◽  
Vol 21 (4) ◽  
pp. 634-643 ◽  
Author(s):  
Jean Lafleur
Keyword(s):  
Grain Size ◽  
Preliminary Test ◽  
Internal Erosion ◽  
Earth Dam ◽  
Laboratory Simulation ◽  
Core Material ◽  
Test Results ◽  
Cohesionless Soils ◽  
Filtration Process ◽  
Margin Of Safety

Filter criteria have generally been checked experimentally with relatively uniform bases (protected soils). However, these criteria may not be applicable when nonuniform soils are used, especially broadly graded cohesionless tills with nonlinear grain size curves. Such soils were extensively used at the James Bay project as impervious core material, and a testing programme was undertaken to establish the margin of safety associated with the application of current filter criteria: the design was based on the arbitrarily defined portion of the base soil grain size curve. Also, a more general objective of the programme was to assess the role that self-filtration plays in the filtration process of such broadly graded cohesionless soils.This paper presents and discusses the factors that have been found relevant in the development of a representative laboratory simulation of the complex filtration phenomenon; namely, maximum particle size, density, saturation of the samples, direction of flow, intensity of the gradients, and development of hydraulic fracturing. Some preliminary test results are given for a till from the LG-3 dam that showed a marked bend in the grain size curve at [Formula: see text]. It is seen that particles coarser than this size do not significantly influence the self-filtration process. Finally, the test results demonstrate that the filters specified for the LG-3 project are more than adequate. Key words: earth dam, filtration, broadly graded cohesionless soils, internal erosion, laboratory tests, design.

Effects of the Pin-on-Disc Parameters on the Wear of Alumina

2010 ◽  
Vol 65 ◽  
pp. 39-44 ◽  
Author(s):  
Nadetsa R. Tedesco ◽  
Eliria M.J.A. Pallone ◽  
R. Tomasi
Keyword(s):  
Grain Size ◽  
Wear Resistance ◽  
Wear Test ◽  
Preliminary Test ◽  
Critical Parameters ◽  
High Wear Resistance ◽  
Test Results ◽  
Pin On Disc ◽  
The Many ◽  
Testing Condition

There is a growing interest in the application of ceramic as high wear resistance materials due to the unique properties. Although brittleness and low toughness, recent improvements in alumina processing have lessen this restrictions and suggest improvements in wear resistance which in turn have driven some research on this. Since a direct comparison between the many published works regarding this wear improvement is complicated due to the fact that wear resistance is a response of the microstructure, material and testing condition, the work herein presented aims to first do a literature review on the main parameters to be controlled in a pin-on-disc apparatus on the wear of alumina and then discuss preliminary test results and analyze the influence of critical parameters as load and sliding speed in a pin-on-disc wear test in a dense and sub micrometer grain size alumina.

Microstructural Control in Thick-Walled Nb-Ti-V Microalloyed Linepipe Steels

2004 ◽  
Vol 467-470 ◽  
pp. 223-228
Author(s):  
K.M. Banks
Keyword(s):  
Grain Size ◽  
Laboratory Simulation ◽  
Microalloyed Steels ◽  
Processing Parameter ◽  
Strip Rolling ◽  
Bearing Steels ◽  
Simulation Results ◽  
Linepipe Steels ◽  
Ferrite Grain Size ◽  
Microstructural Control

Various microstructure models for Nb-bearing steels were tested under industrial strip rolling conditions to establish a relationship between grain size and toughness in Ti-Nb-V microalloyed steels. For similar Nb contents, microstructure models for Nb steels were found to adequately describe recrystallisation kinetics in more complex Ti-Nb-V steels. For thick-walled linepipe (11.6mm), a minimum of 0.04%Nb is required to achieve adequate toughness. Retained strain was the dominant processing parameter factor affecting ferrite grain size. The predicted minimum amount of retained strain after the last pass required for sufficient grain refinement concurred with laboratory simulation results. For the rolling schedules investigated, metadynamic recrystallisation was predicted to occur during roughing, whilst static recrystallisation was predominant during finishing.

scholarly journals Flame Spraying of Aluminum Coatings Reinforced with Particles of Carbonaceous Materials as an Alternative for Laser Cladding Technologies

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3467 ◽  
Author(s):  
Artur Czupryński
Keyword(s):  
Laser Cladding ◽  
Carbon Materials ◽  
High Strength ◽  
Preliminary Test ◽  
Flame Spraying ◽  
Test Results ◽  
Carbonaceous Materials ◽  
Aluminum Coatings ◽  
Cylinder Liners ◽  
Near Future

The article presents results of the preliminary research of mechanical properties of flame-sprayed aluminum coatings reinforced with carbon materials made on the construction steel S235J0 substrate. For reinforcement the following carbon materials were used: carbon nanotubes Nanocyl NC 7000 (0.5 wt.% and 1 wt.%) and carburite (0.5 wt.%). The properties evaluation was made using metallographic macroscope and microscope, chemical composition, microhardness, abrasion and erosion resistance studies. The obtained results were compared with aluminum powder coatings (EN AW 1000 series). It was proved that the flame spraying of aluminum coatings reinforced with particles of carbonaceous materials can be an effective alternative for laser cladding technology. The preliminary test results will be successively extended by further experiments to contribute in the near future to develop innovative technologies, that can be implemented in the automotive industry for production of components with high strength, wear resistance, good thermal conductivity and low density, such as brake shoes, cylinder liners, piston rings and gears.

Effect of Wood Template on Magnetic Properties of Ni0.5Zn0.5Fe2-xCrxO4 Ceramics

2019 ◽  
Vol 956 ◽  
pp. 107-113
Author(s):  
Rui Li ◽  
Liang Cun Qian ◽  
Xue Feng Sun
Keyword(s):  
Grain Size ◽  
Saturation Magnetization ◽  
Spinel Structure ◽  
Single Phase ◽  
Sol Gel ◽  
Porous Ceramics ◽  
Nanocrystalline Powders ◽  
Test Results ◽  
Doping Amount ◽  
Wood Template

Porous Ni0.5Zn0.5Fe2-xCrxO4 (x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) ceramics were prepared by a sol-gel method using basswood as the mold. At the same time, Ni0.5Zn0.5Fe2-xCrxO4 nanocrystalline powders were obtained by sintering the gel in oxygen at high temperature. The result of the XRD test showed that all samples presented the single-phase of the cubic spinel structure. With the increase of doping amount x, both porous ceramics and nanopowders decreased their grain size; At the same doping amount, the grain size of powder ferrites was about twice as large as that of porous ceramics. The magnetic test results showed that with the increase of doping amount x, the coercivity values increased monotonously and the saturation magnetization values decreased monotonously for all samples. Under the same doping content, the saturation magnetization values were lower but the coercivity values were higher as compared to the powder ferrites.

scholarly journals Detection of Microaneurysms in Fundus Images Based on an Attention Mechanism

Genes ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 817
Author(s):  
Lizong Zhang ◽  
Shuxin Feng ◽  
Guiduo Duan ◽  
Ying Li ◽  
Guisong Liu
Keyword(s):  
Detection Method ◽  
Preliminary Test ◽  
Attention Mechanism ◽  
Fundus Images ◽  
Test Results ◽  
Average Accuracy ◽  
Multiple Feature ◽  
Retinal Fundus Images ◽  
Retinal Fundus

Microaneurysms (MAs) are the earliest detectable diabetic retinopathy (DR) lesions. Thus, the ability to automatically detect MAs is critical for the early diagnosis of DR. However, achieving the accurate and reliable detection of MAs remains a significant challenge due to the size and complexity of retinal fundus images. Therefore, this paper presents a novel MA detection method based on a deep neural network with a multilayer attention mechanism for retinal fundus images. First, a series of equalization operations are performed to improve the quality of the fundus images. Then, based on the attention mechanism, multiple feature layers with obvious target features are fused to achieve preliminary MA detection. Finally, the spatial relationships between MAs and blood vessels are utilized to perform a secondary screening of the preliminary test results to obtain the final MA detection results. We evaluated the method on the IDRiD_VOC dataset, which was collected from the open IDRiD dataset. The results show that our method effectively improves the average accuracy and sensitivity of MA detection.

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