scholarly journals Preliminary Study on High-Energy and Low-Energy Microfracture Event Evolution Characteristics in the Development Process of Rock Failure

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Guofeng Yu ◽  
Guanwen Cheng ◽  
Lianchong Li ◽  
Chunan Tang ◽  
Bo Ren ◽  
...  
Keyword(s):  
Bimodal Distribution ◽  
High Energy ◽  
Low Energy ◽  
Biaxial Compression ◽  
Crack Evolution ◽  
Root Cause ◽  
Working Face ◽  
Evolution Characteristics ◽  
Change Characteristics ◽  
Preliminary Study

The evolution characteristics of high-energy and low-energy microfracture events play an important role in the brittle failure mechanism of rock and reasonable microseismic (MS) monitoring and acoustic emission (AE) monitoring. The bimodal distribution (BMD) model is commonly used to observe the evolution characteristics of high-energy and low-energy MS events; however, its precise mechanism remains unclear. The evolution characteristics of high-energy and low-energy microfracture events are assessed in this study based on a BMD model. MS monitoring results from the No. 22517 working face of the Dongjiahe Coal Mine are studied, and AE monitoring results of a biaxial compression experiment of a granite specimen are analyzed. High-energy MS events in the No. 22517 working face are found to be generated by an increase in the failure scale of the overlying rock mass upon exiting the insufficient mining stage and entering the sufficient mining stage. The change characteristics of the high-energy AE hits are positively correlated with crack evolution characteristics in the granite specimen and negatively correlated with changes in the Gutenberg-Richter b value. A precise high-energy and low-energy AE hit evolution mechanism is analyzed based on the microscopic structure of the granite specimen. Similarities and differences between high-energy MS events and low-energy AE hits are determined based on these results. Both are found to have bimodal characteristics; an increase in the failure scale is identified as the root cause of the high-energy component. The bimodal distribution of AE hits is far less obvious than that of MS events.

scholarly journals A New Method for Controlling Rockbursts in the Mining Roadway of Ultrathick Coal Seams Based on the Dual Pressure Relief Method

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Guangyuan Yu ◽  
Jiong Wang ◽  
Zimin Ma ◽  
Wei Ming ◽  
Xingen Ma
Keyword(s):  
Energy Release ◽  
Abutment Pressure ◽  
Average Energy ◽  
Field Testing ◽  
High Energy ◽  
Low Energy ◽  
New Method ◽  
Coal Seams ◽  
Pressure Relief ◽  
Working Face

To control rockbursts in mining roadways in ultrathick coal seams, a new method for preventing rockbursts through dual pressure relief by roof cutting through cumulative blasting in medium-deep boreholes from the conveyor gateway and return airway was proposed. The mechanical characteristics of key overlying strata of the working face under the effect of dual pressure relief were theoretically investigated. Furthermore, a mathematical relationship between the roof-cutting depth and the advanced abutment pressure on the working face was established to reveal the mechanism of dual pressure relief in controlling rockbursts. Moreover, the effect of the dual pressure relief method on controlling rockbursts was validated through numerical simulation and field testing. Results showed that artificially increasing the caving height of gangues in goaf based on the dual pressure relief method can restrict the subsidence of key strata, thus reducing the advanced abutment pressure of the working face; the method influences a range of 20 m in front of the working face along the strike and areas 30 m away from the two roadways along the dip. The average energy density of coal in the side of the conveyor gateway is decreased by 15.4%, while that in the side of return airway is reduced by 13.8% within the range of influence. The field test results indicated that the average pressure on support declines by 21.4% within 30 m from the working face to the conveyor gateway, while it decreases by 20.5% within that region 25 m from the return airway by using the dual pressure relief method. After conducting dual pressure relief, the total number of microseismic (MS) events during mining of the working face is decreased by 25.4%. The number of MS events with energy release exceeding 103 J falls by 36.6%, while the number of events releasing less than 103 J is increased by 28.6%. The characteristics of MS energy release change from coexistence of low-energy events and a small number of high-energy events to the occurrence of numerous low-energy events. Results can verify the effectiveness of the dual pressure relief method in controlling rockbursts in the mining roadway of ultrathick coal seams.

scholarly journals Universal statistics of point vortex turbulence

2015 ◽  
Vol 779 ◽  
pp. 275-308 ◽  
Author(s):  
J. G. Esler ◽  
T. L. Ashbee
Keyword(s):  
Phase Transition ◽  
Probability Density ◽  
Vortex Motion ◽  
Point Vortex ◽  
Normal Modes ◽  
Bimodal Distribution ◽  
High Energy ◽  
Low Energy ◽  
Mean Flow ◽  
Energy States

A new methodology, based on the central limit theorem, is applied to describe the statistical mechanics of two-dimensional point vortex motion in a bounded container $\mathscr{D}$, as the number of vortices $N$ tends to infinity. The key to the approach is the identification of the normal modes of the system with the eigenfunction solutions of the so-called hydrodynamic eigenvalue problem of the Laplacian in $\mathscr{D}$. The statistics of the projection of the vorticity distribution onto these eigenfunctions (‘vorticity projections’) are then investigated. The statistics are used first to obtain the density-of-states function and caloric curve for the system, generalising previous results to arbitrary (neutral) distributions of vortex circulations. Explicit expressions are then obtained for the microcanonical (i.e. fixed energy) probability density functions of the vorticity projections in a form that can be compared directly with direct numerical simulations of the dynamics. The energy spectra of the resulting flows are predicted analytically. Ensembles of simulations with $N=100$, in several conformal domains, are used to make a comprehensive validation of the theory, with good agreement found across a broad range of energies. The probability density function of the leading vorticity projection is of particular interest because it has a unimodal distribution at low energy and a bimodal distribution at high energy. This behaviour is indicative of a phase transition, known as Onsager–Kraichnan condensation in the literature, between low-energy states with no mean flow in the domain and high-energy states with a coherent mean flow. The critical temperature for the phase transition, which depends on the shape but not the size of $\mathscr{D}$, and the associated critical energy are found. Finally the accuracy and the extent of the validity of the theory, at finite $N$, are explored using a Markov chain phase-space sampling method.

Low energy vs. high energy depositional settings and related sedimentary bodies in early Senenian rudist bearing carbonate shelves (central-southern Italy)

2001 ◽  
Vol 28 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Gabriele Carannante ◽  
A. Laviano ◽  
D. Ruberti ◽  
Lucia Simone ◽  
G. Sirna ◽  
...  
Keyword(s):  
Southern Italy ◽  
High Energy ◽  
Low Energy ◽  
Depositional Settings

Transportation: Fuel Energies

2017 ◽  
Author(s):  
Peter Rez
Keyword(s):  
Energy Density ◽  
Fossil Fuels ◽  
High Energy ◽  
Ease Of Use ◽  
Low Energy ◽  
High Energy Density ◽  
Nuclear Fuels ◽  
Liquid Hydrocarbons ◽  
Transportation Fuel ◽  
Journey Time

Transportation efficiency can be measured in terms of the energy needed to move a person or a tonne of freight over a given distance. For passengers, journey time is important, so an equally useful measure is the product of the energy used and the time taken for the journey. Transportation requires storage of energy. Rechargeable systems such as batteries have very low energy densities as compared to fossil fuels. The highest energy densities come from nuclear fuels, although, because of shielding requirements, these are not practical for most forms of transportation. Liquid hydrocarbons represent a nice compromise between high energy density and ease of use.

scholarly journals Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents

2021 ◽  
Vol 22 (15) ◽  
pp. 7879
Author(s):  
Yingxia Gao ◽  
Yi Zheng ◽  
Léon Sanche
Keyword(s):  
Condensed Phase ◽  
Genetic Material ◽  
High Energy ◽  
Dna Lesions ◽  
Low Energy ◽  
Experimental Investigations ◽  
Experimental Conditions ◽  
Strand Breaks ◽  
Sequence Of Events ◽  
Wide Range

The complex physical and chemical reactions between the large number of low-energy (0–30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.

Fabrication of the narrow size nano curcuminoids emulsion by combining phase inversion temperature and ultrasonication: preparation and bioactivity

2021 ◽  
Author(s):  
Quang Hieu Tran ◽  
Thuy Thanh Ho ◽  
Tu Thanh Nguyen
Keyword(s):  
Energy Method ◽  
Phase Inversion ◽  
Curcuma Longa ◽  
High Energy ◽  
Low Energy ◽  
Inversion Temperature ◽  
Comprehensive Study ◽  
Phase Inversion Temperature

A comprehensive study from Curcuma longa to powder nano curcuminoids has been carried out. Combining of both low energy method (Phase Inversion Temperature) and high-energy method (Ultrasonication), a series of...

scholarly journals The low-energy effective theory of axions and ALPs

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Martin Bauer ◽  
Matthias Neubert ◽  
Sophie Renner ◽  
Marvin Schnubel ◽  
Andrea Thamm
Keyword(s):  
High Energy ◽  
New Physics ◽  
Mass Scale ◽  
Low Energy ◽  
Effective Theory ◽  
Loop Order ◽  
Flavor Changing ◽  
Effective Lagrangian ◽  
Anomalous Dimensions ◽  
Pseudoscalar Mesons

Abstract Axions and axion-like particles (ALPs) are well-motivated low-energy relics of high-energy extensions of the Standard Model, which interact with the known particles through higher-dimensional operators suppressed by the mass scale Λ of the new-physics sector. Starting from the most general dimension-5 interactions, we discuss in detail the evolution of the ALP couplings from the new-physics scale to energies at and below the scale of electroweak symmetry breaking. We derive the relevant anomalous dimensions at two-loop order in gauge couplings and one-loop order in Yukawa interactions, carefully considering the treatment of a redundant operator involving an ALP coupling to the Higgs current. We account for one-loop (and partially two-loop) matching contributions at the weak scale, including in particular flavor-changing effects. The relations between different equivalent forms of the effective Lagrangian are discussed in detail. We also construct the effective chiral Lagrangian for an ALP interacting with photons and light pseudoscalar mesons, pointing out important differences with the corresponding Lagrangian for the QCD axion.

scholarly journals Combination of Dual-Energy X-ray Transmission and Variable Gas-Ejection for the In-Line Automatic Sorting of Many Types of Scrap in One Measurement

2021 ◽  
Vol 11 (10) ◽  
pp. 4349
Author(s):  
Tianzhong Xiong ◽  
Wenhua Ye ◽  
Xiang Xu
Keyword(s):  
High Efficiency ◽  
Nearest Neighbor ◽  
High Energy ◽  
Dual Energy ◽  
Center Of Gravity ◽  
Low Energy ◽  
Identification Accuracy ◽  
Flow Process ◽  
X Ray ◽  
Automatic Sorting

As an important part of pretreatment before recycling, sorting has a great impact on the quality, efficiency, cost and difficulty of recycling. In this paper, dual-energy X-ray transmission (DE-XRT) combined with variable gas-ejection is used to improve the quality and efficiency of in-line automatic sorting of waste non-ferrous metals. A method was proposed to judge the sorting ability, identify the types, and calculate the mass and center-of-gravity coordinates according to the shading of low-energy, the line scan direction coordinate and transparency natural logarithm ratio of low energy to high energy (R_value). The material identification was satisfied by the nearest neighbor algorithm of effective points in the material range to the R_value calibration surface. The flow-process of identification was also presented. Based on the thickness of the calibration surface, the material mass and center-of-gravity coordinates were calculated. The feasibility of controlling material falling points by variable gas-ejection was analyzed. The experimental verification of self-made materials showed that identification accuracy by count basis was 85%, mass and center-of-gravity coordinates calculation errors were both below 5%. The method proposed features high accuracy, high efficiency, and low operation cost and is of great application value even to other solid waste sorting, such as plastics, glass and ceramics.

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