scholarly journals Application of a New Geophone and Geometry in Tunnel Seismic Detection

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1246 ◽  
Author(s):  
Yao Wang ◽  
Nengyi Fu ◽  
Xinglin Lu ◽  
Zhihong Fu
Keyword(s):  
Seismic Data ◽  
High Sensitivity ◽  
Forward Modeling ◽  
Mirror Image ◽  
Tunnel Construction ◽  
Two Dimensional ◽  
Geological Hazards ◽  
High Quality ◽  
Seismic Detection ◽  
Layout Geometry

Seismic imaging is the most effective geophysical method and has been extensively implemented to detect potential geological hazards in tunnels during construction. The coupling of geophones and the design of geometry in tunnels are the two major challenges. To ensure successful coupling, a high-sensitivity semi-automatic coupling geophone with a broadband was designed. In practice, this geophone is attached with a wheel and two springs. Once inserted into the borehole, an automatic coupling action occurs. This semi-automatic coupling design within the geophone not only guarantees good coupling, but reduces the time and costs usually required to install a traditional geophone. In the use of geophones for tunnel seismic detection, we propose two new two-dimensional (2D) seismic geometries based on the two commonly used geometries. A test to assess the effectiveness of the qualities of imaging from four geometries was completed by comparing the results of the forward modeling of sandwich models. The conclusion is that the larger the horizontal offset of the layout geometry, the higher the resolution of the imaging; the larger the vertical offset, the weaker the mirror image. The vertical offset is limited due to the narrow tunnel condition. Therefore, the mirror effect cannot be entirely eliminated; however, it can be further suppressed by constructing 2D geometry. The two newly proposed 2D geometries caused the imaging arc of the inter-layer, but suppressed the mirror image. The mirror image added a significant number of errors to the data, which could misguide tunnel construction; therefore the new 2D geometries are more reasonable than the two most commonly used. We applied one of the two new 2D geometries that was more practical to an actual project, the Chongqing Jinyunshan Tunnel in China, and acquired high-quality seismic data using two semi-automatic coupling geophones. The detection results were essentially consistent with the excavation conclusions.

scholarly journals Targeting nickel sulfide deposits from 3D seismicreflection data at Kambalda, Australia

Geophysics ◽  
2012 ◽  
Vol 77 (5) ◽  
pp. WC123-WC132 ◽  
Author(s):  
Milovan Urosevic ◽  
Ganesh Bhat ◽  
Marcos Hexsel Grochau
Keyword(s):  
High Resolution ◽  
Western Australia ◽  
Seismic Data ◽  
Nickel Sulfide ◽  
Forward Modeling ◽  
Geometric Constraints ◽  
3D Seismic ◽  
High Quality ◽  
Sulfide Deposits ◽  
3D Seismic Data

The greenstone belts of the Yilgarn Craton, Western Australia, host numerous Archaean gold, nickel, and iron ore deposits. These deposits typically are found in complex geologic structures hidden by a deep, heterogeneous, and often conductive regolith profile. This added complexity limits the depth of penetration for the potential field methods, but at the same time opens new revenue possibilities through the application of seismic methods. To explore this opportunity, we acquired high-resolution, experimental, 3D seismic data over Lake Lefroy in Kambalda, Western Australia. The main objective was to map exceptionally complex, deep structures associated with Kambalda dome. Survey design used 3D ray tracing to improve the distribution of the common reflection points across ultramafic-basalt contacts which host numerous small, high-grade nickel sulfide deposits. A combination of small explosive sources, high-shot/receiver density, and exceptionally good coupling over the ultrasalty lake surface produced seismic data of very high quality. Processing focused on computation of accurate static and dynamic corrections, whereas imaging was helped by the existing geologic model. Advanced volumetric interpretation supported by seismic forward modeling was used to guide mapping of the main lithological interfaces and structures. Forward modeling was carried out using rock properties obtained from ultrasonic measurements and one borehole, drilled in the proximity of the 3D seismic volume. Using this information, geometric constraints based on the typical size of ore bodies found in this mine and a simple window-based seismic attribute, several new targets were proposed. Three of these targets subsequently have been drilled and new zones of mineralization were intercepted. The case study presented demonstrates that high-quality, high-resolution, 3D seismic data combined with volumetric seismic interpretation could become a primary methodology for exploration of deep, small, massive sulfide deposits distributed across the Kambalda area.

Application of Imaging Plate to High-Voltage Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 168-169
Author(s):  
Seiji Isoda ◽  
Kimitsugu Saitoh ◽  
Sakumi Moriguchi ◽  
Takashi Kobayashi
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
High Sensitivity ◽  
Imaging Plate ◽  
High Quality ◽  
Electron Dose ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Recording Material

On the observation of structures by high resolution electron microscopy, recording materials with high sensitivity and high quality is awaited, especially for the study of radiation sensitive specimens. Such recording material should be easily combined with the minimum dose system and cryoprotection method. Recently a new recording material, imaging plate, comes to be widely used in X-ray radiography and also in electron microscopy, because of its high sensitivity, high quality and the easiness in handling the images with a computer. The properties of the imaging plate in 100 to 400 kV electron microscopes were already discussed and the effectiveness was revealed.It is demanded to study the applicability of the imaging plate to high voltage electron microscopy. The quality of the imaging plate was investigated using an imaging plate system (JEOL EM-HSR100) equipped in a new Kyoto 1000kV electron microscope. In the system both the imaging plate and films can be introduced together into the camera chamber. Figure 1 shows the effect of accelerating voltage on read-out signal intensities from the imaging plate. The characteristic of commercially available imaging plates is unfortunately optimized for 100 to 200 keV electrons and then for 600 to 1000 keV electrons the signal is reduced. In the electron dose range of 10−13 to 10−10 C/cm2, the signal increases linearly with logarithm of electron dose in all acceralating volatges.

scholarly journals High performance self-powered photodetector based on 1D Te-2D WS2 mixed-dimensional heterostructure

2021 ◽  
Author(s):  
Lixiang Han ◽  
Mengmeng Yang ◽  
Peiting Wen ◽  
Wei Gao ◽  
nengjie huo ◽  
...  
Keyword(s):  
High Performance ◽  
Van Der Waals ◽  
Sharp Interface ◽  
Two Dimensional ◽  
High Quality ◽  
One Dimensional ◽  
Self Powered

One dimensional (1D)-two dimensional (2D) van der Waals (vdWs) mixed-dimensional heterostructures with advantages of atomically sharp interface, high quality and good compatibility have attracted tremendous attention in recent years. The...

scholarly journals Investigation of the Heteroepitaxial Process Optimization of Ge Layers on Si (001) by RPCVD

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 928
Author(s):  
Yong Du ◽  
Zhenzhen Kong ◽  
Muhammet Toprak ◽  
Guilei Wang ◽  
Yuanhao Miao ◽  
...  
Keyword(s):  
High Temperature ◽  
Buffer Layer ◽  
Layer Thickness ◽  
Growth Temperature ◽  
Crystalline Quality ◽  
Initial Growth ◽  
Two Dimensional ◽  
High Quality ◽  
Reduced Pressure

This work presents the growth of high-quality Ge epilayers on Si (001) substrates using a reduced pressure chemical vapor deposition (RPCVD) chamber. Based on the initial nucleation, a low temperature high temperature (LT-HT) two-step approach, we systematically investigate the nucleation time and surface topography, influence of a LT-Ge buffer layer thickness, a HT-Ge growth temperature, layer thickness, and high temperature thermal treatment on the morphological and crystalline quality of the Ge epilayers. It is also a unique study in the initial growth of Ge epitaxy; the start point of the experiments includes Stranski–Krastanov mode in which the Ge wet layer is initially formed and later the growth is developed to form nuclides. Afterwards, a two-dimensional Ge layer is formed from the coalescing of the nuclides. The evolution of the strain from the beginning stage of the growth up to the full Ge layer has been investigated. Material characterization results show that Ge epilayer with 400 nm LT-Ge buffer layer features at least the root mean square (RMS) value and it’s threading dislocation density (TDD) decreases by a factor of 2. In view of the 400 nm LT-Ge buffer layer, the 1000 nm Ge epilayer with HT-Ge growth temperature of 650 °C showed the best material quality, which is conducive to the merging of the crystals into a connected structure eventually forming a continuous and two-dimensional film. After increasing the thickness of Ge layer from 900 nm to 2000 nm, Ge surface roughness decreased first and then increased slowly (the RMS value for 1400 nm Ge layer was 0.81 nm). Finally, a high-temperature annealing process was carried out and high-quality Ge layer was obtained (TDD=2.78 × 107 cm−2). In addition, room temperature strong photoluminescence (PL) peak intensity and narrow full width at half maximum (11 meV) spectra further confirm the high crystalline quality of the Ge layer manufactured by this optimized process. This work highlights the inducing, increasing, and relaxing of the strain in the Ge buffer and the signature of the defect formation.

scholarly journals Fabricating centimeter-scale high quality factor two-dimensional periodic photonic crystal slabs

2014 ◽  
Vol 22 (3) ◽  
pp. 3724 ◽  
Author(s):  
Jeongwon Lee ◽  
Bo Zhen ◽  
Song-Liang Chua ◽  
Ofer Shapira ◽  
Marin Soljačić
Keyword(s):  
Photonic Crystal ◽  
Quality Factor ◽  
High Quality Factor ◽  
Two Dimensional ◽  
High Quality ◽  
Photonic Crystal Slabs

RETRACTED: High quality N-polar GaN two-dimensional growth on c-plane sapphire by metalorganic vapor phase epitaxy

2013 ◽  
Vol 366 ◽  
pp. 35-38 ◽  
Author(s):  
Yuantao Zhang ◽  
Xin Dong ◽  
Guoxing Li ◽  
Wancheng Li ◽  
Baolin Zhang ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Metalorganic Vapor Phase Epitaxy ◽  
Vapor Phase Epitaxy ◽  
Two Dimensional ◽  
High Quality ◽  
Dimensional Growth

Nanopillar modified high-sensitivity asymmetric Graphene-GaN photodetector

Nanoscale ◽  
2021 ◽  
Author(s):  
Chang Liu ◽  
Xiaodong Li ◽  
Tiangui Hu ◽  
Wenkai Zhu ◽  
Faguang Yan ◽  
...  
Keyword(s):  
Electrical Properties ◽  
High Performance ◽  
2D Materials ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Optical And Electrical Properties ◽  
Two Dimensional

Integration of two dimensional (2D) materials with three dimensional (3D) semiconductors reveals intriguing optical and electrical properties that surpass those of the original materials. Here we report the high performance...

Synthesis of centimeter-scale high-quality polycrystalline hexagonal boron nitride films from the Fe flux

Nanoscale ◽  
2021 ◽  
Author(s):  
Yifei Li ◽  
Xin Wen ◽  
Changjie Tan ◽  
Ning Li ◽  
Ruijie Li ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Hexagonal Boron Nitride ◽  
Two Dimensional ◽  
High Quality ◽  
Boron Nitride Films

Owing to its irreplaceable roles in new functional devices, such as universal substrates and excellent layered insulators, high-quality hexagonal BN (hBN) crystals are exceedingly required in the field of two-dimensional...

Two-dimensional SnS2 materials as high-performance NO2 sensors with fast response and high sensitivity

2018 ◽  
Vol 255 ◽  
pp. 616-621 ◽  
Author(s):  
Young-Ho Kim ◽  
Duy-Thach Phan ◽  
Seungbae Ahn ◽  
Ki-Hun Nam ◽  
Cheol-Min Park ◽  
...  
Keyword(s):  
High Performance ◽  
High Sensitivity ◽  
Fast Response ◽  
Two Dimensional
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