Study on the Reoxidation Characteristics of Soaked and Air-Dried Coal

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Lulu Sun ◽  
Yanbo Zhang ◽  
Yue Wang ◽  
Qiqi Liu
Keyword(s):  
High Energy ◽  
Gas Generation ◽  
Cross Point ◽  
Point Temperature ◽  
Oxidation Stage ◽  
The Cross ◽  
Temperature Programmed ◽  
Residual Coal ◽  
Seam Mining ◽  
Index Gases

After coal seam mining, the residual coal is soaked with the accumulated water in goaf, and its spontaneous combustion characteristics were changed after air-dried. To study the reoxidation characteristics of soaked and air-dried coal, temperature-programmed experiments were carried out, and the cross point temperatures and index gases were investigated. Results showed that the cross point temperature of raw coal (146.3 °C) was reduced to 137.1 °C after it was pre-oxidized at 90 °C. The cross point temperature of water-soaked, and air-dried coal (96 h) was 122.5 °C, while the cross point temperature of water-soaked, air-dried (96 h) and pre-oxidized (90 °C) coal was 111.5 °C. Although CO was produced in the initial slow oxidation phase, it was found that C2H4 and C3H8 were not generated. In the rapid oxidation stage, different pretreatments affected the gas generation and the overall oxidative degree was consistent with the cross point temperature. The generation temperature and the concentration of C2H4 and C3H8 were decreased after the coal was water-soaked, air-dried, and pre-oxidized. Furthermore, the high-energy chemicals and functional groups were studied, which could be used to explain the physical experiment oxidation characteristics of different coals.

scholarly journals Total cross sections of eγ → $$ eX\overline{X} $$ processes with X = μ, γ, e via multiloop methods

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Roman N. Lee ◽  
Alexey A. Lyubyakin ◽  
Vyacheslav A. Stotsky
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Elliptic Integral ◽  
High Energy ◽  
Calculation Methods ◽  
Complete Elliptic Integral ◽  
Total Cross Sections ◽  
Multiloop Calculation ◽  
The Cross ◽  
Analytical Expressions

Abstract Using modern multiloop calculation methods, we derive the analytical expressions for the total cross sections of the processes e−γ →$$ {e}^{-}X\overline{X} $$ e − X X ¯ with X = μ, γ or e at arbitrary energies. For the first two processes our results are expressed via classical polylogarithms. The cross section of e−γ → e−e−e+ is represented as a one-fold integral of complete elliptic integral K and logarithms. Using our results, we calculate the threshold and high-energy asymptotics and compare them with available results.

Minimum Mould Exit Shell Thickness of Round Blooms for Peritectic Steel Casting

2011 ◽  
Vol 421 ◽  
pp. 179-183 ◽  
Author(s):  
Li Gen Sun ◽  
Hui Rong Li ◽  
Jia Quan Zhang
Keyword(s):  
Cross Section ◽  
Shell Thickness ◽  
Elevated Temperatures ◽  
Continuous Casting Machine ◽  
Casting Machine ◽  
Mathematic Model ◽  
Cross Point ◽  
Peritectic Steel ◽  
Support Roller ◽  
The Cross

The minimum mould exit shell thickness (MEST) is one of key factors to consider for continuous casting machine design and the strand cooling schemes. Based on the shell strength at elevated temperatures, a concept of shell integral average strength, from its very top surface to the solidus frontier, has been introduced to judge its bulging tendency under ferrostatic pressure. Considering the contribution to the shell stability, a mathematic model for the determination of the minimum MEST has been brought forward. It is shown that, the minimum MEST of the round bloom is decided by not only the cross section and the minimum roller spacing, but also the opening degree of the support roller and the support roller on the side. Taking a round bloom casting of plain carbon steel (grade Q235) as an example, there is the cross point with the curve of the minimum MEST by the minimum roller spacing and the minimum MEST by the fluting include angle of the support roller and the support roller on the side against the cross section, if its own geometry structure cannot hold the ferrostatic pressure, the minimum MEST on the left of the cross point can remain as the determined amount by the minimum roller spacing; but on the right, it is increased with the increasing width of cross section.

scholarly journals TACHYON DYNAMICS OF THE BLACK DISC LIMIT IN THE HARD SMALL x PROCESSES IN QCD

2006 ◽  
Vol 21 (07) ◽  
pp. 549-558 ◽  
Author(s):  
B. BLOK ◽  
L. FRANKFURT
Keyword(s):  
Cross Section ◽  
Impact Parameter ◽  
High Energy ◽  
Black Disk ◽  
Black Disc ◽  
Energy Behavior ◽  
Small X ◽  
The Cross ◽  
The Impact ◽  
Black Disc Limit

We investigate the effective field theory (EFT) which gives the approximate description of the scattering of two hard small dipoles in the small x processes in QCD near the black disc limit (BDL). We argue that the perturbative QCD approaches predict the existence of tachyon and visualize it in the approximation where α′P=0. We demonstrate that the high energy behavior of the cross-section depends strongly on the diffusion law in the impact parameter plane. On the other hand, almost threshold behavior of the cross section of the hard processes and multiplicities, i.e. fast increase of cross sections (color inflation), melting of ladders into color network and softening of the longitudinal distributions of hadrons are qualitatively insensitive to the value of diffusion in the impact parameter space. We evaluate α′P near the black disk limit and find significant α′P as the consequence of the probability conservation.

Composite Core Cross Tube Crushing Analysis

2020 ◽  
Author(s):  
Sean Jenson ◽  
Muhammad Ali ◽  
Khairul Alam
Keyword(s):  
Energy Absorption ◽  
Compressive Loading ◽  
Deformation Mode ◽  
High Energy ◽  
Absorption Capacity ◽  
Functionally Graded ◽  
Layer By Layer ◽  
Thin Walled ◽  
The Cross ◽  
Energy Absorbing

Abstract Thin walled axial members are typically used in automobiles’ side and front chassis to improve crashworthiness of vehicles. Extensive work has been done in exploring energy absorbing characteristics of thin walled structural members under axial compressive loading. The present study is a continuation of the work presented earlier on evaluating the effects of inclusion of functionally graded cellular structures in thin walled members under axial compressive loading. A compact functionally graded composite cellular core was introduced inside a cross tube with side length and wall thickness of 25.4 mm and 3.048 mm, respectively. The parameters governing the energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, plateau stress level, and energy curves, were evaluated. The results showed that the inclusion of composite graded cellular structure increased the energy absorption capacity of the cross tube significantly. The composite graded structure underwent progressive stepwise, layer by layer, crushing mode and provided lateral stability to the cross tube thus delaying local tube wall collapse and promoting large localized folds on the tube’s periphery as compared to highly localized and compact deformation modes that were observed in the empty cross tube under axial compressive loading. The variation in deformation mode resulted in enhanced stiffness of the composite structure, and therefore, high energy absorption by the structure. This aspect has a potential to be exploited to improve the crashworthiness of automobile structures.

scholarly journals Quasielastic Lepton Scattering off Two-Component Dark Matter in Hypercolor Model

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 708 ◽  
Author(s):  
Vitaly Beylin ◽  
Maxim Bezuglov ◽  
Vladimir Kuksa ◽  
Egor Tretiakov
Keyword(s):  
Dark Matter ◽  
Total Cross Section ◽  
Cross Section ◽  
Strong Dependence ◽  
Cosmic Ray ◽  
High Energy ◽  
Dominant Contribution ◽  
Quasielastic Scattering ◽  
Two Component ◽  
The Cross

The interaction of high-energy leptons with components of Dark Matter in a hypercolor model is considered. The possibility of detection, using IceCube secondary neutrinos produced by quasielastic scattering of cosmic ray electrons off hidden mass particles, is investigated. The dominant contribution to the cross section results from diagrams with scalar exchanges. A strong dependence of the total cross section on the Dark Matter components mass is also found.

DIFFRACTION AND VECTOR MESON PRODUCTION

2004 ◽  
Vol 19 (07) ◽  
pp. 1099-1110 ◽  
Author(s):  
Y. YAMAZAKI
Keyword(s):  
Vector Meson ◽  
Energy Dependence ◽  
Cross Sections ◽  
Meson Production ◽  
High Energy ◽  
Vector Meson Production ◽  
Diffractive Process ◽  
The Cross

A review is given of the measurements of the diffractive process in recent years from two high-energy colliders, the HERA ep collider and the Tevatron [Formula: see text] collider. The energy dependence of the cross sections and the factorisation properties of diffractive processes are discussed.

Temperature-Programmed Oxidation Experiments on Typical Bituminous Coal Under Inert Conditions

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Yansong Zhang ◽  
Houwang Wang ◽  
Wenzhou Du ◽  
Kuo Niu ◽  
Xiangrui Wei
Keyword(s):  
Bituminous Coal ◽  
Co2 Concentration ◽  
Inert Gases ◽  
Slow Heating ◽  
Fast Heating ◽  
Temperature Programmed Oxidation ◽  
Heating Stage ◽  
Temperature Programmed ◽  
Residual Coal ◽  
Two Stages

Abstract In this study, an experimental investigation was presented on the oxidation behaviors of bituminous coal for different inert gases (N2 and CO2) at different concentrations (oxygen concentration indexes 21%, 18.4%, 15.8%, and 13.1%) using a temperature-programmed experimental device. The purpose of this research was to examine the oxidation patterns of bituminous coal under different inert conditions. The results showed that: (1) the oxidative heating of the coal underwent two stages: an initial slow heating stage and a fast heating stage. The injection of both inert gases would result in a delay in the crossing point temperature (CPT) of the coal, but the injection of N2 resulted in greater delays in the CPT of the coal; (2) the injection of both N2 and CO2 inhibited the concentrations of CO and alkane/olefin gases produced from the oxidative heating of the coal, with CO2 displaying higher inhibition efficiencies than that of N2; (3) Under a non-inerting environment, the C2H4 and C2H6 generation temperatures were 110 °C and 100 °C. Under an inerting environment, when N2 was injected, the higher the N2 concentration, the higher the initial C2H4 and C2H6 generation temperatures; when CO2 was injected, the higher the CO2 concentration, the lower the initial C2H4 and C2H6 generation temperatures; and (4) under a non-inerting environment, the C3H8 generation temperature was 90 °C; and when an inert gas was injected, there was a hysteresis in the C3H8 generation temperature for all concentrations. The above research results can be used to predict the spontaneous combustion of residual coal in an inert environment and prevent fires.

scholarly journals Comparison of two ROC curve-based methods for determining the cross-point critting frequency in the diagnosis of EHM

2020 ◽  
Vol 19 ◽  
pp. 19-20
Author(s):  
A. Villaseñor-Todd ◽  
F.J. Bosques-Padilla ◽  
E. López-Soriano ◽  
C.A. Cortez-Hernandez ◽  
J.A. Hernández-Hernández ◽  
...  
Keyword(s):  
Roc Curve ◽  
Cross Point ◽  
The Cross

scholarly journals Modelling three-dimensional transport of solar energetic protons in a corotating interaction region generated with EUHFORIA

2019 ◽  
Vol 622 ◽  
pp. A28 ◽  
Author(s):  
N. Wijsen ◽  
A. Aran ◽  
J. Pomoell ◽  
S. Poedts
Keyword(s):  
Solar Wind ◽  
Interplanetary Space ◽  
High Energy ◽  
Interaction Region ◽  
Corotating Interaction Region ◽  
Fast Solar Wind ◽  
Transport Code ◽  
Field Diffusion ◽  
Forward Shock ◽  
The Cross

Aims. We introduce a new solar energetic particle (SEP) transport code that aims at studying the effects of different background solar wind configurations on SEP events. In this work, we focus on the influence of varying solar wind velocities on the adiabatic energy changes of SEPs and study how a non-Parker background solar wind can trap particles temporarily at small heliocentric radial distances (≲1.5 AU) thereby influencing the cross-field diffusion of SEPs in the interplanetary space. Methods. Our particle transport code computes particle distributions in the heliosphere by solving the focused transport equation (FTE) in a stochastic manner. Particles are propagated in a solar wind generated by the newly developed data-driven heliospheric model, EUHFORIA. In this work, we solve the FTE, including all solar wind effects, cross-field diffusion, and magnetic-field gradient and curvature drifts. As initial conditions, we assume a delta injection of 4 MeV protons, spread uniformly over a selected region at the inner boundary of the model. To verify the model, we first propagate particles in nominal undisturbed fast and slow solar winds. Thereafter, we simulate and analyse the propagation of particles in a solar wind containing a corotating interaction region (CIR). We study the particle intensities and anisotropies measured by a fleet of virtual observers located at different positions in the heliosphere, as well as the global distribution of particles in interplanetary space. Results. The differential intensity-time profiles obtained in the simulations using the nominal Parker solar wind solutions illustrate the considerable adiabatic deceleration undergone by SEPs, especially when propagating in a fast solar wind. In the case of the solar wind containing a CIR, we observe that particles adiabatically accelerate when propagating in the compression waves bounding the CIR at small radial distances. In addition, for r ≳ 1.5 AU, there are particles accelerated by the reverse shock as indicated by, for example, the anisotropies and pitch-angle distributions of the particles. Moreover, a decrease in high-energy particles at the stream interface (SI) inside the CIR is observed. The compression/shock waves and the magnetic configuration near the SI may also act as a magnetic mirror, producing long-lasting high intensities at small radial distances. We also illustrate how the efficiency of the cross-field diffusion in spreading particles in the heliosphere is enhanced due to compressed magnetic fields. Finally, the inclusion of cross-field diffusion enables some particles to cross both the forward compression wave at small radial distances and the forward shock at larger radial distances. This results in the formation of an accelerated particle population centred on the forward shock, despite the lack of magnetic connection between the particle injection region and this shock wave. Particles injected in the fast solar wind stream cannot reach the forward shock since the SI acts as a diffusion barrier.

Sign in / Sign up

Export Citation Format

Share Document