The loadingunloading process is represented as follows: 0 ... In cyclic loading process, the coal samples first exhibit the appearance of microcracks at the beginning stage. With the increase in the axial stress, the damage gradually accumulates and produces irreversible plastic deformation. When the peak load is reached, partial area of ...
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For unloading, cranes with grabs are the norm, although specialised equipment may be used for certain cargoes. When vessels unload using cranes and grabs, personnel and vehicles are often placed inside the holds to assist the process. Cargo is usually unloaded into hopper barges, then transferred by conveyor to silos or open storage.
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For example, in the loading and unloading process, much elastic energy accumulates in the coal and rock mass with increasing elastic deformation. Under unloading, elastic energy is released. In the test process, the total energy density and elastic energy density of the coal mass can be expressed as Formulas ( 2 ) and ( 3 ).
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In the cyclic loading and unloading process, the load ing and unloading elastic modulus of coal samples experi ences a rapid increase at the beginning stage of the cyclic
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As the coal body has a hysteresis effect during the unloading process, it cannot be unloaded to 0 when unloading, and the minimum unloading level was set for the four kinds of samples; that is, after unloading to 2% σ c, the loading was performed until the sample was destabilized.
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Experimental Device. The "gascontaining coal thermalfluidsolid coupling threeaxis servo seepage system" developed by Chongqing University (Fig. 2) was used to study the effect of variable confining pressure unloading rate on coal deformation and permeability characteristics during the alternate loading and unloading device has a maximum axial force of 1000 kN, a ...
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The residual strains has produced by the first loadingunloading of coal are 7 × 10 −5, × 10 −4, and × 10 −4, respectively. ... However, if the loadingunloading process was continued beyond this point, the residual strain reappeared. The occurrence of the nonresidual strain phenomenon was found to be directly related to the ...
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Fig. 3 presents the influences of gas pressure on coal permeability during gas loadingunloading processes at temperatures of 30 °C, 40 °C, 50 °C, 60 °C, and 70 °C, respectively. In the loading process, the coal permeability decreases gradually. As the pore pressure rises from MPa to MPa, the coal permeability decreases rapidly.
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The underground coal mining process is closely associated with frequent energy storage and consumption of coal mass with natural and induced fractures. Exploring the energy evolution characteristics of intact and fractured coal samples could be helpful for dynamic disaster control. In this study, laboratory true triaxial tests on the energy evolution characteristics of intact and fractured ...
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The cumulative AE energy and energy dissipation density are linearly correlated during the cyclic loadingunloading process, which indicates a possibility in estimating the damage evolution and the dynamic failure risk of coal via cumulative AE energy, under the cyclic loadingunloading condition.
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Scholars have examined the mechanical 22,23, the damage 24,25, and the energy characteristics 26,27 of coal under cyclic loading and unloading. In the process of cyclic loading, some scholars ...
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Coal is an important, widelyused source of energy and a chemical raw material, which is transported globally in large quantities; more than a billion tonnes of coal per year are transported by sea (IEA International Energy Agency, 2020). However, its carriage as a cargo is associated with a number of hazards and coal must be carried in ...
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Both coal mining and tunnel excavation exhibit significant unloading effects, with the process of confining pressure unloading causing damage to coal, thereby affecting coal impact characteristics and gas outburst characteristics. 1820 Based on their investigation, Ding et al. 21 performed a stability assessment study of deep mine dynamic ...
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The loading and unloading rate for uniaxial and cyclic fatigue load were mm/min. The Express8 AE monitoring system was adopted to continuously log the acoustic events/micro failure inside the coal samples during the whole loading process.
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in the study of the inuence of dierent loading and unloading rates on the coal body under the unloading path, it is often only considered to change the axial loading rate or only change the conning pressure unloading rate. The deformation and failure laws of coal under dierent loading and unloading rates are rarely systematically compared and
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In this study, coal fly ash was functionalized, using a simple onestep process (loading with Al3+ and sulfonation), to yield a solid acid catalyst (S/AlCFA) with strong acid sites. The catalyst was then used to produce furfural from xylose in a biphasic system (H2O(NaCl)/tetrahydrofuran). The furfural yield reached 82% at 180 °C60 min with catalyst/xylose ratio of : (w/w). With the ...
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Pollutants for Coal Storage, Loading, and Unloading in Ports A Case Study of Wharf in Tianjin Analysis of Dusting Links in Coal Storage, Loading, and Unloading The eld survey and literature review indicate main pollutants come from dust generated by agitation, dropping, or strong wind in the process of coal loading and unloading,
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This is the technology that used in power plant, while the coal is unload to the convayer belt
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As a result, the crack of saturated coal samples cannot keep stationary in the initial stage of loading and unloading and it slips throughout the loading and unloading process. A large number of macrotensile cracks appeared in the failed coal samples with pore water, as the pore pressure provides tensile force to the cracks and promotes the ...
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The repeated mining causes the unloading and loading of the caved zone, so that the pore structures of caved zone change accordingly, and thus affect the permeability value, which controls the gas migration in the caved zone. The main factors affecting the permeability of the unloading process are different from those controlling it during loading.
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To study the anisotropic mechanical properties and energy evolution of layered rock masses under the action of cyclic loading, uniaxial graded cyclic loading and unloading tests under different upper and lower stress limits were carried out on samples with different bedding angles (0°, °, 45°, °, and 90°) to explore the deformation and mechanical response characteristics of bedded ...
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During the loading/unloading process, the gas pressure in the coal sample is maintained constant through the ingenious structure design of the system. As shown in Fig. 2 b, the constantvolume chamber is connected to the sample by a gas tube, and the constantvolume pistons are connected to the axial indenter.
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Observing the whole unloading process, the unloading time is 133 s when the density of coal bulk is 1600 kg/m 3, the unloading time is s when the density is 1350 kg/m 3 and the unloading time is s when the density is 1100 kg/m 3, so the higher the particle density in the silo, the faster is the unloading speed.
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A material supplier from Belgium would like to produce limestone powder for his custome...
India is rich in various mineral resources and it is an important mineral processing market
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