Study of the Dynamic Fracturing Process and Stress Shadowing Effect in Granite Sample with Two Holes Based on SCDA Fracturing Method

2022 ◽  
Author(s):  
Luchao Wang ◽  
Kang Duan ◽  
Qiangyong Zhang ◽  
Xuejian Li ◽  
Rihua Jiang
Keyword(s):  
Granite Sample ◽  
Fracturing Process ◽  
Shadowing Effect ◽  
Dynamic Fracturing

Ultra high resolution SEM at high voltage images individual fab fragments applied as molecular label to cell surface receptors

1989 ◽  
Vol 47 ◽  
pp. 70-71
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Resolution ◽  
High Energy ◽  
Metal Coating ◽  
Beam Diameter ◽  
Surface Receptors ◽  
Surface Mobility ◽  
Metal Atoms ◽  
Shadowing Effect ◽  
Imaging Mode ◽  
Deposition Techniques

Topographic ultra high resolution can now routinely be established on bulk samples in cold field emission scanning electron microscopy with a second generation of microscopes (FSEM) designed to provide 0.5 nm probe diameters. If such small probes are used for high magnification imaging, topographic contrast is so high that remarkably fine details can be imaged on 2DMSO/osmium-impregnated specimens at ribosome surfaces even without a metal coating. On TCH/osmium-impregnated specimens topographic resolution can be increased further if the SE-I imaging mode is applied. This requires that beam diameter and metal coating thickness be made smaller than the SE range of ~1 nm and background signal contributions be reduced. Subnanometer small probes can be obtained (only) at high accelerating voltages. Subnanometer thin continuous metal films can be produced under the following conditions: self-shadowing effect between metal atoms must be reduced through appropriate deposition techniques and surface mobility of metal atoms must be diminished through high energy sputtering and/or specimen cooling.

Finding Fault with the Nexus Pipeline? Agency Capture and the Public Good

2017 ◽  
Vol 1 (1) ◽  
pp. 1-8
Author(s):  
Andrew R. Kear
Keyword(s):  
Natural Gas ◽  
Environmental Impact ◽  
Public Good ◽  
Health And Safety ◽  
Environmental Impact Statement ◽  
Gas Industry ◽  
The Public ◽  
Fracturing Process ◽  
Natural Gas Industry ◽  
Regulatory Commission

Natural gas is an increasingly vital U.S. energy source that is presently being tapped and transported across state and international boundaries. Controversy engulfs natural gas, from the hydraulic fracturing process used to liberate it from massive, gas-laden Appalachian shale deposits, to the permitting and construction of new interstate pipelines bringing it to markets. This case explores the controversy flowing from the proposed 256-mile-long interstate Nexus pipeline transecting northern Ohio, southeastern Michigan and terminating at the Dawn Hub in Ontario, Canada. As the lead agency regulating and permitting interstate pipelines, the Federal Energy Regulatory Commission is also tasked with mitigating environmental risks through the 1969 National Environmental Policy Act's Environmental Impact Statement process. Pipeline opponents assert that a captured federal agency ignores public and scientific input, inadequately addresses public health and safety risks, preempts local control, and wields eminent domain powers at the expense of landowners, cities, and everyone in the pipeline path. Proponents counter that pipelines are the safest means of transporting domestically abundant, cleaner burning, affordable gas to markets that will boost local and regional economies and serve the public good. Debates over what constitutes the public good are only one set in a long list of contentious issues including pipeline safety, proposed routes, property rights, public voice, and questions over the scientific and democratic validity of the Environmental Impact Statement process. The Nexus pipeline provides a sobering example that simple energy policy solutions and compromise are elusive—effectively fueling greater conflict as the natural gas industry booms.

ORGANIC COMPOUND CHARACTERIZATION OF HYDRAULIC FRACTURING FLOWBACK WATERS THROUGHOUT THE FRACTURING PROCESS

2016 ◽  
Author(s):  
Karl Oetjen ◽  
◽  
Simon Roberts ◽  
Tzahi Y. Cath ◽  
Chris Higgins
Keyword(s):  
Organic Compound ◽  
Hydraulic Fracturing ◽  
Fracturing Process

scholarly journals Surface Texturing of Si with Periodically Arrayed Oblique Nanopillars to Achieve Antireflection

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 380
Author(s):  
Jun-Hyun Kim ◽  
Sanghyun You ◽  
Chang-Koo Kim
Keyword(s):  
Aspect Ratio ◽  
Plasma Etching ◽  
Surface Texturing ◽  
Light Reflection ◽  
Si Substrate ◽  
Weighted Mean ◽  
Optical Reflectance ◽  
Si Substrates ◽  
Aspect Ratios ◽  
Shadowing Effect

Si surfaces were texturized with periodically arrayed oblique nanopillars using slanted plasma etching, and their optical reflectance was measured. The weighted mean reflectance (Rw) of the nanopillar-arrayed Si substrate decreased monotonically with increasing angles of the nanopillars. This may have resulted from the increase in the aspect ratio of the trenches between the nanopillars at oblique angles due to the shadowing effect. When the aspect ratios of the trenches between the nanopillars at 0° (vertical) and 40° (oblique) were equal, the Rw of the Si substrates arrayed with nanopillars at 40° was lower than that at 0°. This study suggests that surface texturing of Si with oblique nanopillars reduces light reflection compared to using a conventional array of vertical nanopillars.

scholarly journals Sequential bilateral Behçet’s neuroretinitis associated with prepapillary vitreous exudate: case report

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Imen Ksiaa ◽  
Safa Ben Aoun ◽  
Sourour Zina ◽  
Dhouha Nefzi ◽  
Sana Khochtali ◽  
...  
Keyword(s):  
Case Report ◽  
Single Case ◽  
Signal Loss ◽  
Fiber Layer ◽  
Swept Source ◽  
Single Case Report ◽  
Shadowing Effect ◽  
Eye Involvement ◽  
The Right ◽  
Inflammatory Changes

Abstract Objective To describe a case of Behçet disease (BD) uveitis manifesting with sequential bilateral neuroretinitis associated with prepapillary inflammatory vitreous exudate (PIVE). Material and methods A single case report documented with multimodal imaging. Results A 37-year-old man developed neuroretinitis with associated PIVE in the left eye. He was diagnosed with ocular toxoplasmosis and treated accordingly based on positive serologic testing and negative work-up for other entities, including BD. The disease course was favorable, but 1 year later a similar neuroretinitis developed in the right eye. Extraocular features of BD became evident only at the time of the second eye involvement, and the patient received corticosteroid and immunosuppressive therapy. Swept source (SS) OCT showed at the acute phase in both eyes a typical “mushroom-shaped” prepapillary hyperreflectivity of the PIVE. SS OCT angiography (OCTA) demonstrated a corresponding prepapillary hypointense area due to shadowing effect, decreasing in size while scanning deeper layers. It also detected peripapillary retinal hypervascularity in both eyes and a sectoral area of flow signal loss in the first involved left eye. Visual acuity improved following the resolution of the PIVE and associated acute inflammatory changes in both eyes. The left eye showed residual optic disc pallor and retinal nerve fiber layer defects. Conclusion Sequential bilateral neuroretinitis associated with PIVE may occur before other clinical features of BD become evident. SS OCT and OCTA can provide useful information for the diagnosis and management of this rare, but typical, ocular manifestation of BD uveitis.

scholarly journals Numerical simulation on the simultaneous stress interference of parallel multiple hydraulic fractures

2021 ◽  
pp. 014459872110019
Author(s):  
Weiyong Lu ◽  
Changchun He
Keyword(s):  
Principal Stress ◽  
Hydraulic Fracture ◽  
Stress Ratio ◽  
Fracture Network ◽  
Hydraulic Fractures ◽  
Fracture Spacing ◽  
Induced Stress ◽  
Minimum Principal Stress ◽  
Fracturing Process ◽  
Stress Ratios

During horizontal well staged fracturing, there is stress interference between multiple transverse fractures in the same perforation cluster. Theoretical analysis and numerical calculation methods are applied in this study. We analysed the mechanism of induced stress interference in a single fracture under different fracture spacings and principal stress ratios. We also investigated the hydraulic fracture morphology and synchronous expansion process under different fracture spacings and principal stress ratios. The results show that the essence of induced stress is the stress increment in the area around the hydraulic fracture. Induced stress had a dual role in the fracturing process. It created favourable ground stress conditions for the diversion of hydraulic fractures and the formation of complex fracture network systems, inhibited fracture expansion in local areas, stopped hydraulic fractures, and prevented the formation of effective fractures. The curves of the maximum principal stress, minimum principal stress, and induced principal stress difference with distance under different fracture lengths, different fracture spacings, and different principal stress ratios were consistent overall. With a small fracture spacing and a small principal stress ratio, intermediate hydraulic fractures were difficult to initiate or arrest soon after initiation, fractures did not expand easily, and the expansion speed of lateral hydraulic fractures was fast. Moreover, with a smaller fracture spacing and a smaller principal stress ratio, hydraulic fractures were more prone to steering, and even new fractures were produced in the minimum principal stress direction, which was beneficial to the fracture network communication in the reservoir. When the local stress and fracture spacing were appropriate, the intermediate fracture could expand normally, which could effectively increase the reservoir permeability.

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