933 results match your criteria: "China University of Mining and Technology- Beijing[Affiliation]"

Study on microstructure evolution and oxidation kinetics in Coal-Oil Symbiosis.

Sci Total Environ

November 2024

School of Emergency Management and Safety Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.

Article Synopsis
  • The study investigates how the characteristics of Coal-Oil Symbiosis (COS) affect safety management and ecological maintenance in coal mines, focusing on effects of different oil mass percentages.
  • Key findings indicate that as oil content increases, COS shows reduced oxygen absorption, lower ignition temperatures, and significant reductions in activation energy during pyrolysis and combustion, enhancing its combustion characteristics.
  • Additionally, COS has fewer macropores covered by oil, which limits oxygen access, while increasing active hydrocarbon groups, promoting spontaneous combustion, and providing insights for better disaster prevention and environmental protection in mining areas.
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The subsidence of the earth's surface in mining areas is characterized by fast speed and large gradients. Conventional small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) monitoring can significantly underestimate results, making it challenging to capture the surface's temporal subsidence features. In this context, this paper proposes a method for monitoring subsidence in mining areas.

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A suite of coal samples near a diabase dike was collected to investigate the structural and functional group evolution of a series of carbon materials prepared from thermally altered coals, explore the influence of thermal metamorphism distance on the structure of coal and its carbon material products, and divide the thermally altered zones. Using Fourier transform infrared and Raman studies, it was found that after demineralization, the aromatic parameters and of the coal structure slightly increase, while the aliphatic parameters CH/CH and oxidation parameter slightly decrease, and the degree of order of the coal structure increases. Graphitization can greatly improve aromatic parameters, eliminate aliphatic structures, and enhance orderliness.

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Wind-blow sand (WBS) is widely distributed in the "Desert Gobi" region. This study is aimed at exploring the mechanism of how different thicknesses of the WBS layer influence the slope movement of external dumps in open-pit mines. To achieve this aim, the slope of the external dump in the open-pit mining area of Panel 3 in Daliuta Coal Mine was taken as the research object.

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Existing studies have explored the impact of venture capital shareholding on the GEM-listed companies before and after listing from multiple perspectives. However, there has been limited research on the influence of venture capital shareholding on these companies' mergers and acquisitions(M&A) activities and performance. Additionally, two conflicting research findings have been presented in limited relevant studies.

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The maximum clique problem in graph theory is a well-known challenge that involves identifying the complete subgraph with the highest number of nodes in a given graph, which is a problem that is hard for nondeterministic polynomial time (NP-hard problem). While finding the exact application of the maximum clique problem in the real world is difficult, the relaxed clique model quasi-clique has emerged and is widely applied in fields such as bioinformatics and social network analysis. This study focuses on the maximum quasi-clique problem and introduces two algorithms, NF1 and NR1.

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Temporal vascular arcade angle in fundus image was associated with the rate of spherical equivalent refractive error and axial length changes in myopia children with young school age.

Photodiagnosis Photodyn Ther

October 2024

Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing. No. 1 Dongjiaominxiang Street, Dongcheng District, Beijing 100730, China. Electronic address:

Purpose: To evaluate temporal vascular arcade angle and its influencing factors in myopic children.

Methods: It was a retrospective study, we reviewed the records of 119 patients aged 6-10 years with myopia (spherical equivalent refractive error (SER) ≤ -0.05D) in the third year of follow-up in Beijing Hyperopia Reserve Research.

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Coal and gas outburst is the mechanical damage behavior of gas-containing coal in a complex environment. In this paper, the established experimental system is used to carry out hammer damage experiments on coal adsorption of different gases under different gas pressures and analyze the mass distribution and surface area distribution characteristics of coal samples in each particle size interval after the hammer damage of coal samples. The energy of the crushing process was analyzed by using the specific work of crushing, mass of newly generated particle size added per unit of energy, newly added surface area per unit of energy, and newly added specific surface area per unit of energy.

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Article Synopsis
  • Coal ash flow temperature is crucial for the efficiency of entrained flow bed gasification, but its relationship with chemical composition is unclear.
  • Machine learning models, particularly support vector regression, were developed to predict coal ash flow temperature, yielding a highly accurate model with minimal errors.
  • The new model outperformed existing software (FactSage) in accuracy, suggesting it has significant potential for use in coal chemical engineering.
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To non-destructively and rapidly monitor the chlorophyll content of winter wheat leaves under CO microleakage stress, and to establish the quantitative relationship between chlorophyll content and sensitive bands in the winter wheat growing season from 2023 to 2024, the leakage rate was set to 1 L/min, 3 L/min, 5 L/min, and 0 L/min through field experiments. The dimensional reduction was realized, fractional differential processing of a wheat canopy spectrum was carried out, a multiple linear regression (MLR) and partial least squares regression (PLSR) estimation model was constructed using a SPA selection band, and the model's accuracy was evaluated. The optimal model for hyperspectral estimation of wheat SPAD under CO microleakage stress was screened.

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This study presents a bidirectional flow tidal bioreactor designed to enhance H-driven CO biomethanation. The bioreactor alternated biofilms between immersion in nutrient solution and exposure to H/CO, creating alternating dry and wet states. This tidal operation minimized liquid film thickness during dry periods and ensured uniform nutrient distribution during wet periods.

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Arsenic (As), a toxic element, contaminates farmlands, rivers, and groundwater, posing severe environmental and health risks. Notably, As-containing materials in tailings are affected by temperature variations during long-term storage, and this considerably impact the oxidation and migration of elements in arsenopyrite.This study focused on arsenopyrite and investigated the process of its oxidative dissolution and release of arsenic under different temperature conditions by using in-situ XRD, in-situ XPS and electron paramagnetic resonance spectroscopy(EPR), The role of oxygen free radicals in the oxidation of arsenopyrite was elucidated.

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Oxygen reduction reaction (ORR) serves as the foundation for various electrochemical energy storage devices. Fe/NC catalysts are expected to replace commercial Pt/C as oxygen electrode catalysts based on the structural tunability at the atomic level, abundant iron ore reserves and excellent activity. Nevertheless, the lack of durability and low active site density impede its advancement.

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Objective: Health-promoting behaviors carry substantial significance for miners' overall health and well-being. This study aimed to examine the association between cumulative risk (CR) and miners' health-promoting behaviors and test the mediating role of health beliefs in this relationship.

Methods: Data were collected from a sequential survey conducted among 712 frontline miners (=41.

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To investigate the fractal characteristics of rock crack distributions during the loading process, discrete element method was used to make rock samples with joints and record the crack propagation. The Box-counting method was used to quantitatively analyze the fractal dimension of the crack distribution at each moment, and the relationship between the crack fractal dimension and strain ratio was established based on fractal theory. The results indicated that the relationship between the fractal dimension of the crack distribution and strain ratio showed a strong linear characteristic.

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Double-layer island working face main roadway coal pillars are affected by complex mining stress superposition, when different coal pillar width combinations, the surrounding rock stress field will produce different degrees of regional loading increase effect; the study of the surrounding rock stress field regional superposition loading increase law is meaningful to explaining the failure mode of the roadway and determining the critical control area. This study combines numerical simulation with on-site monitoring and other methods and draws the following conclusions: The superimposed loading increase law ("decreasing" → "increasing") of the abutment pressure and deviatoric stress in the lower coal seam of the double-layer island working face during the mining; the type of the principal stress deflection in the advance working face region; and by obtaining the three types of development morphology of the deviatoric stress peak zone of the roadway and its corresponding nine evolution modes (one type of circular tube → four types of inverse hyperbolic body → four types of hyperbolic body) in the double-layered island working face mining. Indicated the critical reinforcement area corresponding to the main roadway when at different combinations of coal pillar widths; determined the main track roadway protective coal pillars width for 40 m and the shape of the roadway peak deviatoric stress zone is the inverse class hyperbolic body mode; according to the evolution mode of the peak deviatoric stress zone, determined the synergistic failure control program for the asymmetric critical zone of the roadway surrounding rock which is a targeted scientific support method; after the feedback of on-site monitoring and, the support program is reasonable and effective.

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The impact of lenses on the seepage failure of tailings dam.

PLoS One

August 2024

China Academy of Safety Science and Technology, Beijing, China.

The presence of lenses such as tailings slurry, frozen soil, and saturated zones disrupts the continuity of tailings dams and their normal seepage patterns, elevating the seepage line of the dam body and significantly impacting local stability. This study, to investigate how lenses affect the stability and failure mechanisms of tailings dams, employs numerical simulation and physical models and constructs a model of the tailings dam, incorporating tailings clay lens and void lens, to investigate variations in hydraulic gradients, seepage velocities, seepage flow, pore water pressure, and the patterns of seepage failure. This research reveals that the tailings clay lens within the dam body increases the hydraulic gradient in its vicinity due to its low permeability and raises the phreatic line.

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Airborne microplastics (MPs) are important pollutants that have been present in the environment for many years and are characterized by their universality, persistence, and potential toxicity. This study investigated the effects of terrestrial and marine transport of MPs in the atmosphere of a coastal city and compared the difference between daytime and nighttime. Laser direct infrared imaging (LDIR) and polarized light microscopy were used to characterize the physical and chemical properties of MPs, including number concentration, chemical types, shape, and size.

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Coal fly ash has gained much attention as a potential alternative source for extracting critical metals such as Li, Ga, Nb, and lanthanides and yttrium (REY). This study investigates their distribution characteristics and modes of occurrence in alumina-rich fly ashes from the Togtoh Power Plant in Inner Mongolia, using various analytical methods. The objective was to provide a reference for the pre-enrichment of critical metals in fly ash.

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Pregabalin is a medication primarily used in the treatment of neuropathic pain and anxiety disorders, owing to its gabapentinoid properties. Pregabalin monotherapy faces limitations due to its variable efficacy and dose-dependent adverse reactions. In this study, we conducted a comprehensive investigation into the potentiation of pregabalin's analgesic effects by dexborneol, a neuroprotective bicyclic monoterpenoid compound.

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Landfill leachate-containing per- and polyfluoroalkyl substances (PFAS) is both an important 'sink' and a 'source' of secondary pollution, posing serious threaten to surrounding environments. To date, the pollution characteristics of PFAS in landfill leachate, and the coexistence and interaction between PFAS and other leachate contaminants, such as dissolved organic matter (DOM) and toxic metals remains unclear. Herein, our results showed that 17 target PFAS, with concentrations ranged from 1804 to 43309 ng/L, were detected in landfill leachates.

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Research on Internal Damage Identification of Wire Rope Based on Improved VGG Network.

Entropy (Basel)

June 2024

School of Mechanical, Electronic and Information Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.

In order to solve the problem of great difficulty in detecting the internal damage of wire rope, this paper proposes a method to improve the VGG model to identify the internal damage of wire rope. The short-time Fourier transform method is used to transform the wire rope damage signal into a time-frequency spectrogram as the model input, and then the traditional VGG model is improved from three aspects: firstly, the attention mechanism module is introduced to increase the effective feature weights, which effectively improves the recognition accuracy; and then, the batch normalization layer is added to carry out a uniform normalization of the data, so as to make the model easier to converge. At the same time, the pooling layer and the fully connected layer are improved to solve the redundancy problem of the traditional VGG network model, which makes the model structure more lightweight, greatly saves the computational cost, shortens the training time, and finally adopts the joint-sample uniformly distributed cross-entropy as the loss function to solve the overfitting problem and further improve the recognition rate.

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This study first draws inspiration from the dual biomimetic design of plant cell walls and honeycomb structures, drawing on their structural characteristics to design a flexible shell structure that can achieve significant deformation and withstand large loads. Based on the staggered bonding of this flexible shell structure, we propose a new design scheme for a large-load pneumatic soft arm and establish a mathematical model for its flexibility and load capacity. The extension and bending deformation of this new type of soft arm come from the geometric variability of flexible shell structures, which can be controlled through two switches, namely, deflation and inflation, to achieve extension or bending actions.

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Selective oxygen reduction reaction: mechanism understanding, catalyst design and practical application.

Chem Sci

July 2024

CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, University of Chinese Academy of Sciences Beijing 100190 P. R. China

The oxygen reduction reaction (ORR) is a key component for many clean energy technologies and other industrial processes. However, the low selectivity and the sluggish reaction kinetics of ORR catalysts have hampered the energy conversion efficiency and real application of these new technologies mentioned before. Recently, tremendous efforts have been made in mechanism understanding, electrocatalyst development and system design.

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Coal mining in regions characterized by high groundwater table markedly predisposes to surface subsidence and water accumulation, thereby engendering substantial harm to surface vegetation, soil, and hydrological resources. Developing effective methods to extract surface disturbance information aids in quantitatively assessing the comprehensive impacts of coal mining on land, ecology, and society. Due to the shortcomings of traditional indicators in reflecting mining disturbance, vegetation aboveground biomass (AGB) is introduced as the primary indicator for extracting the mining disturbance range.

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