scholarly journals Development of a New Method for the Quantitative Generation of an Artificial Joint Specimen with Specific Geometric Properties

2019 ◽  
Vol 11 (2) ◽  
pp. 373 ◽  
Author(s):  
Seungbeom Choi ◽  
Sudeuk Lee ◽  
Hoyoung Jeong ◽  
Seokwon Jeon
Keyword(s):  
Rock Mass ◽  
Rock Joint ◽  
Laser Scanner ◽  
Specimen Preparation ◽  
Void Space ◽  
Displacement Method ◽  
Simple Method ◽  
Joint Specimen ◽  
Target Values ◽  
Mechanical Aperture

A rock joint is a planar discontinuity that has significant influence on the mechanical and hydraulic characteristics of rock mass. Laboratory experiments are often conducted on a joint to investigate and provide fundamental information for rock mass analysis. Although joint roughness and mechanical aperture exert great effects on the experimental results, controlling them in quantitative manner is quite complicated and consumptive in terms of specimen preparation. A new and simple method for the quantitative generation of the joint specimen was proposed in this study. Based on random midpoint displacement method, a joint specimen with a void space inside was generated. Parametric studies for the roughness and mechanical aperture were carried out, and as a result, the two joint properties could be controlled by manipulating input parameters of random midpoint displacement method. In order to validate the proposed method, two joint specimens, which had different levels of roughness and aperture, were generated and printed. Surface coordinates of the specimens were obtained by a 3D laser scanner, and calculated to make a comparison between the target values and the estimated values. Results showed that the method was capable of generating joint specimens with satisfactory precision.

scholarly journals Experimental Study on Hydromechanical Behavior of an Artificial Rock Joint with Controlled Roughness

2019 ◽  
Vol 11 (4) ◽  
pp. 1014
Author(s):  
Seungbeom Choi ◽  
Byungkyu Jeon ◽  
Sudeuk Lee ◽  
Seokwon Jeon
Keyword(s):  
Rock Mass ◽  
Rock Joint ◽  
Great Influence ◽  
Rock Joints ◽  
In Situ Tests ◽  
Joint Roughness ◽  
Artificial Rock ◽  
Geometric Conditions ◽  
Bedding Planes ◽  
Hydraulic Aperture

Rock mass contains various discontinuities, such as faults, joints, and bedding planes. Among them, a joint is one of the most frequently encountered discontinuities in rock engineering applications. Generally, a joint exerts great influence on the mechanical and hydraulic behavior of rock mass, since it acts as a weak plane and as a fluid path in the rock mass. Therefore, an accurate understanding on joint characteristics is important in many projects. In-situ tests on joints are sometimes consumptive in terms of time and expenses so that the features are investigated by laboratory tests, providing fundamental properties for rock mass analyses. Although the behavior of a joint is affected by both mechanical and geometric conditions, the latter are often limited, since quantitative control on the conditions is quite complicated. In this study, artificial rock joints with various geometric conditions, i.e., joint roughness, were prepared in a quantitative manner and the hydromechanical characteristics were investigated by several laboratory experiments. Based on the results, a prediction model for hydraulic aperture was proposed in the form of ( e h / e m ) 3 = exp ( − 0.0462 c ) × ( 0.8864 ) J R C , which was a function of the mechanical aperture, joint roughness, and contact area. Relatively good agreement between the experimental results and predicted value indicated that the model is capable of estimating the hydraulic aperture properly.

Analyzing Boron in 9–12% Chromium Steels Using Atom Probe Tomography

2019 ◽  
Vol 25 (2) ◽  
pp. 462-469 ◽  
Author(s):  
Irina Fedorova ◽  
Flemming Bjerg Grumsen ◽  
John Hald ◽  
Hans-Olof Andrén ◽  
Fang Liu
Keyword(s):  
Grain Boundaries ◽  
Atom Probe Tomography ◽  
Atom Probe ◽  
Specimen Preparation ◽  
Accurate Analysis ◽  
Simple Method ◽  
Metal Borides ◽  
Boron Distribution ◽  
Cr Steels ◽  
Term Creep

AbstractSmall additions of boron can remarkably improve the long-term creep resistance of 9–12% Cr steels. The improvement has been attributed to boron segregation to grain boundaries during quenching, and subsequent boron incorporation into certain families of precipitates during tempering. However, the detailed mechanisms are not yet fully understood. Atom probe tomography (APT) is an excellent technique for gaining insights into boron distribution, however, in order to acquire accurate analysis of boron in 9–12% Cr steels using APT, there are several key challenges. In order to better understand and address these challenges, we developed a novel method for site-specific APT specimen preparation, which enables convenient preparation of specimens containing specifically selected grain boundaries positioned approximately perpendicular to the axis of the APT tip. Additionally, when analyzing boron at boundaries and in carbides (as diluted solute) and borides, a widening of the profile of boron distribution compared to other elements was repeatedly observed. This phenomenon is particularly analyzed and discussed in light of the evaporation field of different elements. Finally, the possible effects of detector dead-time on quantitative analysis of boron in metal borides are discussed. A simple method using 10B correction was used to obtain good quantification.

scholarly journals A Quick Method for the Texture Mapping of Meshes Acquired by Laser Scanner

2012 ◽  
Vol 9 ◽  
pp. 17-26 ◽  
Author(s):  
Francesco Gabellone ◽  
Ivan Ferrari ◽  
Francesco Giuri
Keyword(s):  
Laser Scanner ◽  
Morphological Characteristics ◽  
Texture Mapping ◽  
Operational Effectiveness ◽  
Quick Method ◽  
Simple Method ◽  
Infra Red ◽  
Different Types ◽  
Infra Red Images ◽  
False Colour

The methodology described in this article was developed in connection with two different projects and entails texture mapping by time-of-flight laser scanner. In order to verify its operational effectiveness and applicability to other contexts, sites with extremely different morphological characteristics were studied. The basic rationale of this simple method derives from the need to obtain different types of mapping – including RGB real colour images, infra-red images, false colour images from georadar scans, etc. – from the same scanned surface. To resolve this problem, we felt that the most appropriate step was to obtain a UVW mapping based on the high resolution real colour images and then use the samecoordinates to rapidly map the false colour images as well. Thus we fitted a device to the camera to determine its trajectory (similar to a gunsight); when scanned by the laser scanner in the same context as the monument, it makes it possible to know the exact coordinates of the viewpoint.

scholarly journals Reduced graphene oxide membrane as supporting film for high-resolution cryo-EM

2021 ◽  
Author(s):  
Nan Liu ◽  
Liming Zheng ◽  
Jie Xu ◽  
Jia Wang ◽  
Cuixia Hu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
High Resolution ◽  
Reduced Graphene Oxide ◽  
Interface Problem ◽  
Specimen Preparation ◽  
Simple Method ◽  
Reduced Graphene ◽  
Two Dimensional Materials ◽  
Air Water Interface ◽  
Oxide Membrane

AbstractAlthough single-particle cryogenic electron microscopy (cryo-EM) has been applied extensively for elucidating many crucial biological mechanisms at the molecular level, this technique still faces critical challenges, the major one of which is to prepare the high-quality cryo-EM specimen. Aiming to achieve a more reproducible and efficient cryo-EM specimen preparation, novel supporting films including graphene-based two-dimensional materials have been explored in recent years. Here we report a robust and simple method to fabricate EM grids coated with single- or few-layer reduced graphene oxide (RGO) membrane in large batch for high-resolution cryo-EM structural determination. The RGO membrane has decreased interlayer space and enhanced electrical conductivity in comparison to regular graphene oxide (GO) membrane. Moreover, we found that the RGO supporting film exhibited nice particle-absorption ability, thus avoiding the air-water interface problem. More importantly, we found that the RGO supporting film is particularly useful in cryo-EM reconstruction of sub-100 kDa biomolecules at near-atomic resolution, as exemplified by the study of RBD-ACE2 complex and other small protein molecules. We envision that the RGO membranes can be used as a robust graphene-based supporting film in cryo-EM specimen preparation.

scholarly journals BARRIER AND GUARDRAIL EXTRACTION AND CLASSIFICATION FROM POINT CLOUDS

2020 ◽  
Vol XLIII-B5-2020 ◽  
pp. 157-162
Author(s):  
M. Vidal ◽  
L. Díaz-Vilariño ◽  
P. Arias ◽  
J. Balado
Keyword(s):  
Traffic Safety ◽  
Autonomous Vehicles ◽  
Global Economy ◽  
Laser Scanner ◽  
Point Clouds ◽  
High Definition ◽  
Simple Method ◽  
Concrete Barriers ◽  
Parameter Dependent

Abstract. In the recent years, the modelling of infrastructures has been receiving increasingly attention due to the importance of transport infrastructures for global economy, traffic safety and for the generation of high definition maps, essential to autonomous vehicles. This paper presents a simple method for the segmentation and classification of concrete barriers and guardrails in road surroundings. First steps of the method are aimed to delimit the region of the point cloud outside the driving lanes in which barriers and guardrails are installed. The purpose is to significantly reduce the size of point clouds in order to improve further processing. Then, barrier segmentation and classification are designed as parameter-dependent processes because the geometric features of roads and barriers and guardrails are mostly regulated by norms and standards. Results show a good performance in terms of classification in comparison of other state of the art methods. Better results were obtained for guardrails than for concrete barriers. The method has been tested in a set of point clouds acquired with a Mobile Laser Scanner from conventional roads and highways.

scholarly journals A simple pressure-assisted method for cryo-EM specimen preparation

2019 ◽  
Author(s):  
J. Zhao ◽  
H. Xu ◽  
M. Carroni ◽  
H. Lebrette ◽  
K. Wallden ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Pressure Gradient ◽  
Structural Biology ◽  
Specimen Preparation ◽  
Single Particles ◽  
Simple Method ◽  
Cryo Electron Microscopy ◽  
Low Concentrations ◽  
Wide Range ◽  
Major Bottleneck

AbstractCryo-electron microscopy (cryo-EM) has made great impacts on structural biology. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing cryo-EM specimens, named Preassis, in which the excess liquid is removed by introducing a pressure gradient through the EM grid. We show the unique advantages of Preassis in handling samples with low concentrations of protein single particles and micro-crystals in a wide range of buffer conditions.

Rock joint detection from borehole imaging logs based on gray-level co-occurrence matrix and Canny edge detector

2021 ◽  
pp. qjegh2021-016
Author(s):  
Yunfeng Ge ◽  
Bin Du ◽  
Huiming Tang ◽  
Peng Zhong
Keyword(s):  
Rock Mass ◽  
Imaging System ◽  
Mechanical Design ◽  
Rock Joint ◽  
Joint Density ◽  
Rock Joints ◽  
Geometrical Parameters ◽  
Gray Level ◽  
Occurrence Matrix ◽  
Borehole Imaging

Rock joints play an important role in characterizing the rock mass quality for geo-mechanical design and stability analysis. An approach was developed to detect and characterize the rock joints from images collected by a borehole imaging system. A gray-level co-occurrence matrix was employed to locate the joint regions, allowing more focused and effective detection processing, followed by extractions of the upper and lower edges of rock using the Canny algorithm. Four basic geometrical parameters of rock joints－orientation, depth, aperture, and core length－were determined based on the fitting of sinusoids to joints’ edges. Furthermore, the joint density was determined based on the geometric parameters. To calibrate the proposed approach, a borehole in the Rumei hydropower station engineering at Lantsang River was selected as a case study. Orientation of rock joints with gentle dip angles, which was determined from borehole imaging logs, corresponded to the measurement in three horizontal tunnels. Additionally, both joint density and pressure-wave velocity revealed that jointed rock mass was observed in the depth from 100 m to 120 m, and intact rock mass was presented in the depth of 150 m to 170 m, indicating the good performance of the proposed method.

scholarly journals Spatially consistent imputations of forest data under a semivariogram model

2016 ◽  
Vol 46 (9) ◽  
pp. 1145-1156 ◽  
Author(s):  
Victor Felix Strîmbu ◽  
Liviu Teodor Ene ◽  
Erik Næsset
Keyword(s):  
Objective Function ◽  
Laser Scanner ◽  
Data Types ◽  
Semivariogram Model ◽  
Airborne Laser Scanner ◽  
Airborne Laser ◽  
Target Values ◽  
The Difference ◽  
Southern Norway

This study proposes a method to perform spatially consistent imputations of forest data to serve simulation studies where spatial autocorrelation is expected to have an effect (e.g., sampling simulations and forest scenario analysis). Starting with a nearest neighbour imputation, an optimization process brings the spatially comprehensive data to a desired state, controlled by a target semivariogram and a target histogram. The target values for both parameters may be approximated using empirical data and are combined in the objective function used by the optimization algorithm. Here, we demonstrate a case study using wall-to-wall airborne laser scanner data, satellite data, and field observations for an 852 ha forest area in southern Norway. Different combinations of data types and target parameters were tested, and the target values were reached in most cases. In some cases, with a more restrictive objective function, the semivariogram did not completely converge to its target values, yet still had a convergence of at least 93%, expressed by the difference reduction between initial and target values. The results recommend the proposed method as a practical means to generate spatially explicit forest data when a particular distribution and well-defined spatial dependence are required.

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