scholarly journals Effect of Functional Groups in Coal on the Depth of Adsorption Potential Well

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Chen Wang ◽  
Zengchao Feng ◽  
Xing Wang
Keyword(s):  
Functional Groups ◽  
Structural Parameters ◽  
Chain Structure ◽  
Methane Adsorption ◽  
Potential Well ◽  
Adsorption Potential ◽  
Potential Wells ◽  
Factors Affecting ◽  
Different Depths ◽  
Natural Coal

Due to the complexity of the internal structure of natural coal and its characteristic of multicomponent, the depth of its methane adsorption potential well is nonuniform, which makes it difficult to accurately evaluate the adsorption capacity of coal. Besides, in order to find out the factors affecting the depth distribution of potential wells in natural coal, this paper calculated the depth and number of potential wells during methane adsorption in coal according to the Langmuir adsorption kinetics process. Coal samples with different metamorphic degrees were tested and analyzed by infrared spectroscopy diffraction technology. The relationship between the structural parameters of functional groups in coal samples with different metamorphic degrees and the distribution of different depths of adsorption potential wells in coal samples was studied. Some main conclusions are as follows: The number of adsorption potential wells at different depths in natural coal with different metamorphic degrees has multipeak distribution characteristics. With the increase of the metamorphic degree of coal sample, the structures such as aliphatic branched chain structure and oxygen-containing functional groups in coal structure break, fall off, and deoxygenate. The relative content of aliphatic hydrocarbons is significantly reduced and condensed into aromatic hydrocarbons and aromatic ring structures. The different types and quantities of functional groups on the surface of coal samples lead to different forces between coal molecules and methane gas molecules, thus affecting the distribution of different depths of adsorption potential wells in coal samples.

scholarly journals Variation law of adsorption heat of methane and coal with inhomogeneous potential well

2018 ◽  
Vol 36 (7-8) ◽  
pp. 1538-1549 ◽  
Author(s):  
Zeng-Chao Feng ◽  
Chen Wang ◽  
Dong Zhou ◽  
Dong Zhao
Keyword(s):  
Adsorption Process ◽  
Methane Adsorption ◽  
Adsorption Heat ◽  
Potential Well ◽  
Coal Surface ◽  
Isothermal Adsorption ◽  
Potential Wells ◽  
Preferential Adsorption ◽  
Coal Deposits ◽  
High Temperature Stage

The non-uniform structures of coal deposits make potential well distribution on the coal surface inhomogeneous. Deep potential wells adsorb methane molecules more easily than shallow potential wells. The methane adsorption heat release differs according to the depths of the potential wells. During isobaric adsorption, the adsorption heat in the high-temperature stage is significantly higher than that in the low-temperature stage. A lower adsorption pressure results in greater adsorption heat variation during a temperature increase. During the isothermal adsorption process, the adsorption heat is higher in the low-pressure stage, with the preferential adsorption characteristics of deep potential wells.

Dropstone deposition: Results of numerical process modeling of deformation structures, and implications for the reconstruction of the water depth in shallow lacustrine and marine successions

2021 ◽  
Vol 91 (5) ◽  
pp. 507-519
Author(s):  
Małgorzata Bronikowska ◽  
Małgorzata Pisarska-Jamroży ◽  
A.J. (Tom) van Loon
Keyword(s):  
Bottom Sediment ◽  
Water Depth ◽  
Dense Medium ◽  
Factors Affecting ◽  
Deformation Structures ◽  
Wide Range ◽  
Water Columns ◽  
Numerical Process ◽  
Different Depths ◽  
The Impact

ABSTRACT Dropstones in lacustrine and marine sediments show a wide range of sizes: from less than a millimeter to many meters. Their size and shape determine the velocity and the acceleration when they settle through the water column, and this, in turn, determines in principle the imprint that they make in the bottom sediment. Although these parameters are crucial for dropstone deposition, the unknown material (sediment) properties (like strength, porosity, pore-water content, viscosity, etc.) of the bottom sediment play a just as important role in this process as the water depth, which can physically be understood as the length of the pathway traveled vertically through a dense medium before the impact. Reconstruction of the principal environmental conditions at the time of dropstone fall and deposition consequently requires considering the variety of factors affecting the final imprint depth of a dropstone, the combination of several numerical methods. Here, we show the results of numerical modeling of dropstones with different sizes that settle through water columns with different depths. Our results show how environmental factors control the deformation structures formed at the sedimentary surface during the impact of a dropstone, and how deep the imprint caused by the settling dropstone will be.

Energy Analysis of Impact-Shear Interaction of Counter Flows of Ground Loose Material in Centrifugal Disintegrator

Mining Revue ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 30-39
Author(s):  
Volodymyr Nadutyi ◽  
Oleksandr Tytov ◽  
Dmytrii Kolosov ◽  
Vitalii Sukhariev ◽  
Taras Usatyi
Keyword(s):  
Power Consumption ◽  
Technological Process ◽  
Loose Material ◽  
Energy Analysis ◽  
Structural Parameters ◽  
Shear Deformations ◽  
Factors Affecting ◽  
Absolute Value ◽  
The Absolute ◽  
Distribution Of Power

Abstract The distribution of power consumption of centrifugal two-shaft disintegrator for impact and shear destruction of material as functions of its technological and structural parameters, as well as parameters of material being ground, has been substantiated. An analytical apparatus has been developed to determine the degree of influence of each factor. Factors affecting the absolute value of the consumed power of the disintegrator have also been established. The results of the work make it possible to optimize the technological process in order to reduce the yield of bream fragments of destruction, which is observed when the share of energy of shear deformations increases, in order to obtain cuboid fractions of disintegration products. They allow to create a methodology for determining the rational parameters of a centrifugal double-shaft disintegrator.

An Automatic Off-Line Signature Verification and Forgery Detection System

2008 ◽  
pp. 63-89 ◽  
Author(s):  
Vamsi Krishna Madasu ◽  
Brian C. Lovell
Keyword(s):  
Membership Function ◽  
Detection System ◽  
Structural Parameters ◽  
Grid Method ◽  
Fuzzy Modeling ◽  
Signature Verification ◽  
Forgery Detection ◽  
Large Database ◽  
Factors Affecting ◽  
Handwritten Signature

This chapter presents an off-line signature verification and forgery detection system based on fuzzy modeling. The various handwritten signature characteristics and features are first studied and encapsulated to devise a robust verification system. The verification of genuine signatures and detection of forgeries is achieved via angle features extracted using a grid method. The derived features are fuzzified by an exponential membership function, which is modified to include two structural parameters. The structural parameters are devised to take account of possible variations due to handwriting styles and to reflect other factors affecting the scripting of a signature. The efficacy of the proposed system is tested on a large database of signatures comprising more than 1,200 signature images obtained from 40 volunteers.

scholarly journals Sand Removal Mechanism of a High-Speed Roller Bit with Helical Sealing

2019 ◽  
Vol 9 (18) ◽  
pp. 3830
Author(s):  
Yi Zhou ◽  
Bin Tan ◽  
Yuxing Huang
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Oil And Gas ◽  
Structural Parameters ◽  
Working Life ◽  
Removal Mechanism ◽  
Drilling Tool ◽  
Rock Stratum ◽  
Factors Affecting ◽  
Simulation And Experiment

A roller bit is a drilling tool widely used in oil and gas exploitation. The roller bit is applied to cutting the rock stratum, and its working life and rotational speed are important factors affecting the drilling efficiency. Moreover, a bearing sealing affects the working life and rotational speed of a bit. This paper proposes a helical sealing structure that addresses the problems of severe sealing wear and a short working life. This structure has been used in many engineering fields but was first applied to the roller bit. This paper investigates the sand removal mechanism of helical sealing through simulation and experiment. Additionally, helical sealing parameters were optimized. The optimum structural parameters of helical sealing in a high-speed roller bit were obtained. It was shown that the helical sealing structure can be applied to a roller bit with good effects of sealing and sand removal.

scholarly journals Escape time from potential wells of strongly nonlinear oscillators with slowly varying parameters

2005 ◽  
Vol 2005 (3) ◽  
pp. 365-375 ◽  
Author(s):  
Jianping Cai ◽  
Y. P. Li ◽  
Xiaofeng Wu
Keyword(s):  
Elliptic Function ◽  
Nonlinear Oscillators ◽  
Oscillatory System ◽  
Escape Time ◽  
Potential Well ◽  
Jacobian Elliptic Function ◽  
Potential Wells ◽  
Varying Parameters ◽  
Strongly Nonlinear ◽  
Strongly Nonlinear Oscillators

The effect of negative damping to an oscillatory system is to force the amplitude to increase gradually and the motion will be out of the potential well of the oscillatory system eventually. In order to deduce the escape time from the potential well of quadratic or cubic nonlinear oscillator, the multiple scales method is firstly used to obtain the asymptotic solutions of strongly nonlinear oscillators with slowly varying parameters, and secondly the character of modulus of Jacobian elliptic function is applied to derive the equations governing the escape time. The approximate potential method, instead of Taylor series expansion, is used to approximate the potential of an oscillation system such that the asymptotic solution can be expressed in terms of Jacobian elliptic function. Numerical examples verify the efficiency of the present method.

The Escape of Particles from a Confining Potential well

1992 ◽  
Vol 290 ◽  
Author(s):  
James P. Lavine ◽  
Edmund K. Banghart ◽  
Joseph M. Pimbley
Keyword(s):  
Diffusion Coefficient ◽  
Chemical Reactions ◽  
Smoluchowski Equation ◽  
Escape Rate ◽  
Potential Well ◽  
Potential Wells ◽  
Confining Potential ◽  
Potential Shape ◽  
Well Depth ◽  
Electron Devices

AbstractMany electron devices and chemical reactions depend on the escape rate of particles confined by potential wells. When the diffusion coefficient of the particle is small, the carrier continuity or the Smoluchowski equation is used to study the escape rate. This equation includes diffusion and field-aided drift. In this work solutions to the Smoluchowski equation are probed to show how the escape rate depends on the potential well shape and well depth. It is found that the escape rate varies by up to two orders of magnitude when the potential shape differs for a fixed well depth.

Driving factors affecting spatial and temporal variations in the structure of phytoplankton functional groups in a temperate reservoir

2015 ◽  
Vol 44 (4) ◽  
Author(s):  
Miloš Ćirić ◽  
Bojan Gavrilović ◽  
Gordana Subakov Simić ◽  
Jelena Krizmanić ◽  
Milka Vidović ◽  
...  
Keyword(s):  
Functional Groups ◽  
Cyanobacterial Bloom ◽  
Temporal Variations ◽  
Driving Factors ◽  
Algal Community ◽  
Factors Affecting ◽  
P Limitation ◽  
Water Pumping ◽  
Phytoplankton Functional Groups ◽  
One Year

AbstractDuring the twenty-five years of existence, water quality has declined and severe blooms of cyanobacteria have occurred in the Grlište Reservoir. Changes in phytoplankton functional groups over time and along horizontal and vertical gradients were investigated in the course of a one-year study in this water-supply reservoir. We identified 19 dominant taxa, classified into 12 phytoplankton associations. The presence of the codons C, P, D and S1 differentiated the transitional from the lacustrine part of the reservoir. The nitrogen-fixing cyanobacteria Dolichospermum viguieri dominated the phytoplankton community in the epilimnion during August and September, when the reservoir showed P-limitation, but the bloom was not observed. The driving factors that accounted for the main variability in phytoplankton functional groups along the seasonal and vertical profile were identified using the direct gradient analysis (RDA). Our results revealed the importance of two bipolar factors. The first factor explained the variability in phytoplankton due to thermal stratification and physical mixing, each process affecting the algal community in contrasting ways. The second factor was interpreted as reduction vs. oxidation processes. Positive correlation between stratification and water pumping by a drinking water plant indicated that human activities were not severe enough to break down the thermal stability of the reservoir and to cause a cyanobacterial bloom.

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