Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2020

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 601 - 630 of 69184

Full-Text Articles in Entire DC Network

Spatial Distribution Of Forage Intake By Grazing Beef Cows On An Alpine Pasture In Japan, M. Nakano, Masato Yayota, R. Tamai, Shigeru Ohtani Dec 2020

Spatial Distribution Of Forage Intake By Grazing Beef Cows On An Alpine Pasture In Japan, M. Nakano, Masato Yayota, R. Tamai, Shigeru Ohtani

IGC Proceedings (1977-2023)

No abstract provided.

Go to article

Library Funding And Physically Challenged Students In Nigerian Universities, Adekoya Clement Ola Dec 2020

Library Funding And Physically Challenged Students In Nigerian Universities, Adekoya Clement Ola

Library Philosophy and Practice (e-journal)

One principal factor determining the provision of the required information resources and facilities that meet the needs of physically challenged students is funding. This study investigated library funding and physically challenged students in Nigerian universities, Descriptive survey research design was used for the study. The population of the study was 236 librarians in 17 public universities in South-west, Nigeria. Total enumeration sampling technique was used for the study. The instrument of data collection was questionnaire. Out of the 236 copies of the questionnaire administered, 171 copies were retrieved, representing 72.5% response rate. Data collected were analysed using percentage, frequency count …

Go to article

Using Instagram Museum Nasional As A Historical Education Media Through E-Publication To Engage Audiences, Fitria Ayuningtyas, Uljanatunnisa Uljanatunnisa, Vinta Sevilla Dec 2020

Using Instagram Museum Nasional As A Historical Education Media Through E-Publication To Engage Audiences, Fitria Ayuningtyas, Uljanatunnisa Uljanatunnisa, Vinta Sevilla

Library Philosophy and Practice (e-journal)

The museum as an institution devoted to cultural preservation began to utilize social media as a medium of communication to the public. Some museums around the world since the early 2000s have used social media to create a new face or rebrand in giving an update to the public. Generally, the term for museums that utilize technology in practice, is called Museum 2.0. In this research, researchers aimed to explore Instagram content as a medium of historical education through qualitative content analysis. The formulation of the problem in this research is to know how the contents of the National Museum …

Go to article

Numerical Simulation Of Nonlinear Vibrations Of Discrete Mass With Harmonic Force Perturbation, M. Yusupov, B. A. Akhmedov, Olga Karpova Dec 2020

Numerical Simulation Of Nonlinear Vibrations Of Discrete Mass With Harmonic Force Perturbation, M. Yusupov, B. A. Akhmedov, Olga Karpova

Acta of Turin Polytechnic University in Tashkent

The problem of vibration of a single-mass system under the force excitation of vibration associated with a fixed base by a weightless nonlinear viscoelastic spring is considered. To take into account the rheological properties of the spring material, the Boltzmann-Volterra principle was used. Mathematical models of the problem under consideration are obtained, which are described by integro-differential equations. A solution method based on the use of quadrature formulas has been developed and a computer program has been compiled on its basis, the results obtained are presented in the form of graphs. The influence of nonlinear and rheological properties of a …

Go to article

Analysis Of The Optical And Thermal Characteristics Of A Solar Parabolic Cylindrical Collector, O H. Otaqulov, S F. Ergashev, Y A. Yusupov Dec 2020

Analysis Of The Optical And Thermal Characteristics Of A Solar Parabolic Cylindrical Collector, O H. Otaqulov, S F. Ergashev, Y A. Yusupov

Scientific-technical journal

The article analyzes the optical and thermal characteristics of a solar parabolic-cylindrical collector (PCC). Effective parameters such as geometric concentration, aperture width, coverage angle, receiver diameter, and focal distance are considered. Simulation results are presented via Monte Carlo ray tracing (MCRT) method. The factors influencing the distribution of the heat flux at the receiver are revealed.

Go to article

The Synthesis Method Formal Description For The Physical Principles Of Operation Of Robotic Systems Mechatronic Modules, Kh N. Nazarov, T O. Rakhimov Dec 2020

The Synthesis Method Formal Description For The Physical Principles Of Operation Of Robotic Systems Mechatronic Modules, Kh N. Nazarov, T O. Rakhimov

Scientific-technical journal

The article is focused on a formal description of the method for synthesizing the physical principles of the operation of mechatronic modules of robotic systems. The method of synthesis of the physical principle of action of mechatronic modules is represented by a set of synthesis problems and a synthesis problem solver. At the same time, the structure of the method includes the output physical quantities of mechatronic modules of robotic systems, information about the nature and ranges of variation of the output quantities and other restrictions, input physical quantities or parameters of robotic systems.

Go to article

Modern Technology Enhanced Adaptive And Cognitive Learning In The Virtual Reality Environment, U E. Giyosov, Sandeep Bhargava, F M. Nuraliev Dec 2020

Modern Technology Enhanced Adaptive And Cognitive Learning In The Virtual Reality Environment, U E. Giyosov, Sandeep Bhargava, F M. Nuraliev

Scientific-technical journal

This text deals with the design of virtual reality systems. Infrastructure includes providing a powerful adaptive or cognitive learning to use the different levels of complexity that will be adapted for each student, empowering those who present more difficulties for learning. Smart devices and intelligent technologies create learning environments that respond to each learner’s profile and needs and offer conditions for realizing personalized and adaptive learning.

Go to article

Seismic Resistance Assessment Of The Secondary Schools Buildings And Recommendations For Ensuring Their Seismic Safety, H S. Sagdiev, A S. Yuvmitov, Z R. Teshaboev, V A. Galiaskarov, S U. Toshpulatov, B B. Uktamov Dec 2020

Seismic Resistance Assessment Of The Secondary Schools Buildings And Recommendations For Ensuring Their Seismic Safety, H S. Sagdiev, A S. Yuvmitov, Z R. Teshaboev, V A. Galiaskarov, S U. Toshpulatov, B B. Uktamov

Scientific-technical journal

In this article was given the results of the calculations of the selected secondary schools buildings for seismic effects, as well as some recommendations for their further safe operation.

Go to article

Salt Marsh Elevation Limit Determined After Subsidence From Hydrologic Change And Hydrocarbon Extraction, R. Eugene Turner, Yu Mo Dec 2020

Salt Marsh Elevation Limit Determined After Subsidence From Hydrologic Change And Hydrocarbon Extraction, R. Eugene Turner, Yu Mo

Faculty Publications

Levee construction aboveground and hydrocarbon removal from belowground in coastal wetlands can create hydrologic changes that increase plant stress through flooding. But the significance of the subsidence they cause individually or in combination is contested. This study untangled them to demonstrate elevational limits of salt marshes by studying dredged and natural waterways in two salt marshes in Louisiana, USA. The areas had a homogenous plant cover before drilling for oil and gas extraction peaked in the 1960s, and now are a mixed network of natural waterways and dredged canals used to drill wells with an average drill date of 1965.8 …

Go to article

The Application Of Ovt Domain Processing Technology In Deep Cbm Exploration In Qinshui Basin, Tian Zhongbin, Li Juan, Shen Youyi, Feng Ajian, Yang Xiaodong Dec 2020

The Application Of Ovt Domain Processing Technology In Deep Cbm Exploration In Qinshui Basin, Tian Zhongbin, Li Juan, Shen Youyi, Feng Ajian, Yang Xiaodong

Coal Geology & Exploration

The high concentration slurry is poured into the goaf to form filled piers. The bearing capacity of the piers to the superstructure are affected by the overlap size. In order to grasp the influence of the overlap size on the bearing capacity of the overlying rock layer, high concentration slurry was prepared which selected cement as the cementing material, standard sand as the aggregate. 3D printing technology was used to make the mold to produce the overlapped round table samples. The uniaxial compression test was carried out. Test results show that, when the top area and height of each single …

Go to article

Pulverized Coal-Controlling Method Based On Supermolecular Film In Cbm Well, Wu Ying, Li Xiaonan, Liu Zixiong, Liu Rumin Dec 2020

Pulverized Coal-Controlling Method Based On Supermolecular Film In Cbm Well, Wu Ying, Li Xiaonan, Liu Zixiong, Liu Rumin

Coal Geology & Exploration

Correctly understanding the micro-scale fracture characteristics of the Lower Cambrian shale and the evolution law of acoustic emission signals are of great reference value in the study of shale mechanical characteristics, fracture mechanism and shale gas development and utilization. In this paper, based on digital image processing technology, the non-uniform characterization of quartz-filled shale is carried out, and a numerical model is established using the real rock fracture analysis system RFPA2D-DIP to simulate the failure process of shale under different confining pressures. The test results show that under the micro-scale structure, the shale failure mode can be roughly …

Go to article

Analysis On The Cbm Extraction Effect Of The Horizontal Wells In The Coal Seam Roof In Luling Coal Mine In Huaibei, Fang Liangcai, Li Guihong, Li Dandan, Li Haozhe, Liu Jia Dec 2020

Analysis On The Cbm Extraction Effect Of The Horizontal Wells In The Coal Seam Roof In Luling Coal Mine In Huaibei, Fang Liangcai, Li Guihong, Li Dandan, Li Haozhe, Liu Jia

Coal Geology & Exploration

Aiming at the scientific evaluation of coaxial casing heat transfer of geothermal resources with medium burial depth(1 500-4 000 m), a rock-water coupled heat transfer model of a vertical single well was built based on the simulation platform of COMSOL Multiphysics software. Taking the stratigraphic and geothermal characteristics of Xi'an area as the simulation background, the heat transfer capacity of single well(3 500 m)casing under two different geothermal gradients(0.027℃/m and 0.030℃/m) and four flow velocities(0.25, 0.50, 0.75, 1.00 m/s) was calculated and analyzed. Meanwhile, the numerical models of group wells with five kinds of well spacing were established, and the …

Go to article

Construction And Transformation Technology Of Three-Dimensional Fine Model Of Mine Water Diversion Structure, Fan Juan, Hou Enke, Jin Dewu, Qiao Wei, Nan Shenghui Dec 2020

Construction And Transformation Technology Of Three-Dimensional Fine Model Of Mine Water Diversion Structure, Fan Juan, Hou Enke, Jin Dewu, Qiao Wei, Nan Shenghui

Coal Geology & Exploration

The development degree of natural fractures is the main factor affecting coalbed methane productivity. In order to accurately obtain the distribution position of the natural fractures in the a coalbed methane field in the southern Qinshui basin, 7 refracturing wells in the area were adopted by surface microseismic vector scanning to monitor the natural fractures. A certain amount of three-component geophones were deployed around the fracturing well to collect microseismic events in the surrounding reservoir during fracturing, and after Semblance superposition, the fracture energy slices at different times in the monitoring area were obtained to explain the natural fractures in …

Go to article

Research On The Fracture Mechanics Model Of Deep Hole Pre-Splitting For Forced Caving, Li Jinhua, Chen Wenxiao, Su Peili, Duan Dong, Song Yongjun Dec 2020

Research On The Fracture Mechanics Model Of Deep Hole Pre-Splitting For Forced Caving, Li Jinhua, Chen Wenxiao, Su Peili, Duan Dong, Song Yongjun

Coal Geology & Exploration

Tight radius drilling technology based on high pressure water jet is an important technical means to realize low-cost and efficient development of oil and gas resources. According to the research and application of tight radius drilling technology based on high pressure water jet, the equipment buildup, drilling theory, technical process and application effect of three tight radius drilling technologies and equipments(i.e., forging milling and reaming hydraulic type, forging milling and reaming jet thrust type and casing window type) are summarized systematically, and the advantages, disadvantages and adaptability of different technologies are included. From the point of view of increasing production …

Go to article

Freezing Temperature Field Characteristics Of Multi-Loop Pipers Under Different Working Conditions At The Interface Of Deep Thick Sand And Clay, Yang Qing, Rong Chuanxin, Li Mingjing, Yang Guobing Dec 2020

Freezing Temperature Field Characteristics Of Multi-Loop Pipers Under Different Working Conditions At The Interface Of Deep Thick Sand And Clay, Yang Qing, Rong Chuanxin, Li Mingjing, Yang Guobing

Coal Geology & Exploration

When drilling in a complex heterogeneous formation, due to the limitation of bit crown shape, the cutters of each part of the bit are subjected to non-uniform force, and the cutters at the local location are subjected to large impact load, which lead to the occurrence of bit vortex. In order to solve the problem, a “multi-level force balance” cutter circumferential arrangement scheme is proposed. By establishing the rock breaking finite element simulation model of the bit, the mechanical characteristics of the cutter and the bit under three circumferential cutter distribution modes(clockwise, counterclockwise and “multi-level force balance”) are analyzed. Simulation …

Go to article

Gas Drainage Technology And Practice Analysis Of Large Diameter High Position Directional Long Borehole, Hao Shijun, Duan Huijun, Mo Haitao, Peng Xu, Peng Dong Dec 2020

Gas Drainage Technology And Practice Analysis Of Large Diameter High Position Directional Long Borehole, Hao Shijun, Duan Huijun, Mo Haitao, Peng Xu, Peng Dong

Coal Geology & Exploration

In order to solve the problem of the high mud content and easy hydration and dispersion of the Cretaceous sedimentary strata in well Songke-2, the bit balling is prone to occur in the water-based drilling fluid environment, which affects the drill bit ROP and induces downhole adhesion stuck, the paper combined the core drilling technology of well Songke-2, systematically analyzed of the causes of bit balling generated by the drill bit in the mudstone and water-based drilling fluid environment, provided a basis for the design of the anti-balling of the drill bit and the formulation of the anti-ball in drilling …

Go to article

Interpretation Method Of High Density 3d Seismic Depth Domain Data In Coal Mining Districts, Meng Fanbin Dec 2020

Interpretation Method Of High Density 3d Seismic Depth Domain Data In Coal Mining Districts, Meng Fanbin

Coal Geology & Exploration

The development height of the water conducting fractured zone is one of the important technical parameters for mine water hazards prediction. In this paper, the combined well-surface microseismic monitoring technology was used to analyze the development characteristics of the water conducting fractured zone in working face 4103 in Wenjiapo coal mine. The results showed that for deep buried coal seams, the microseismic events occured in the advance mining face with advanced influence angle ranging from the minimum of 28° to the maximum of 35°. The stability of overburden decreased due to the faults. Thus, compared with normal bedrock, the overburden …

Go to article

Study On Multi-Dof Search And Salvage Robot In Shallow Water, Jun-Bing Qian, Nan Pan, Xiao-Jue Guo, Yi Liu Dec 2020

Study On Multi-Dof Search And Salvage Robot In Shallow Water, Jun-Bing Qian, Nan Pan, Xiao-Jue Guo, Yi Liu

Journal of Marine Science and Technology–Taiwan

For underwater robots working in a variety of risky, unpredictable, and complex underwater environments – with factors such as turbulence, vortex, wind, wave, and deep-water pressure – it is necessary to ensure good structural design and handling performance in the process of robot design. Based on the requirements of achieving the stability design, control system, and underwater vision system of the robot, this paper proposes the structural design of a police multipurpose underwater robot power system that realizes both stable and flexible movement. A 6-DOF driving method was designed and its motion analysis was performed. In the vision system, an …

Go to article

A Study On Hydrodynamic Forces Induced By Liquid Tank Of Lng Carrier In Waves Based On Experiment And Recurrent Neural Network, Van Minh Nguyen, Thi Thanh Diep Nguyen, Hyeon Kyu Yoon Dec 2020

A Study On Hydrodynamic Forces Induced By Liquid Tank Of Lng Carrier In Waves Based On Experiment And Recurrent Neural Network, Van Minh Nguyen, Thi Thanh Diep Nguyen, Hyeon Kyu Yoon

Journal of Marine Science and Technology–Taiwan

The sloshing of liquid in a partially filled tank is of great concern to aerospace vehicles, road vehicles and ships due to complex nonlinear motion involving the free surface of the liquid. Sloshing is a type of violent liquid motion that is created by forces such as an impact and breaking waves. Oscillation of the liquid in the vessel may threaten navigation safety. This paper attempts to predict the hydrodynamic forces induced by the motion of liquid inside a tank based on experiment and Recurrent Neural Network (RNN). The experiment of sloshing test is carried out using the Stewart platform …

Go to article

Collision Warning System For Small Maritime Autonomous Surface Ships, Won-Sik Kang, Young-Soo Park, Jeong-Bin Yim Dec 2020

Collision Warning System For Small Maritime Autonomous Surface Ships, Won-Sik Kang, Young-Soo Park, Jeong-Bin Yim

Journal of Marine Science and Technology–Taiwan

In this study, wireless communication technologies used in road and marine traffic are compared and analyzed to develop a collision warning system for small maritime autonomous surface ships based on sufficient testing and technologically advanced wireless access in vehicular environment (WAVE) communication technology. Outstanding communication technologies, such as WAVE, have been used as the core technology for the infrastructural development of an intelligent transport system (ITS) as well as autonomous vehicles in many countries and industries. In WAVE communication, information is transmitted in 100-ms intervals. Therefore, it is feasible to maintain control of ships by fully supplementing the update interval …

Go to article

Remote Sensing Analysis Of Cold Water Temporal And Spatial Variability In The East Sea, Suk Yoon, Hyun Yang Dec 2020

Remote Sensing Analysis Of Cold Water Temporal And Spatial Variability In The East Sea, Suk Yoon, Hyun Yang

Journal of Marine Science and Technology–Taiwan

In this study, we monitored temporal and spatial variability in summer cold water events in the East Sea of Korea. We defined cold water as seawater that is ≥ 5°C colder than the surrounding area. When cold water expands or changes in propagation direction, the National Institute of Fisheries Science (NIFS) of Korea issues a cold water upwelling warning to prevent aquafarm damage. To understand cold water effects, we analyzed the causes of continuous and strong cold water events, and propagation thereof, using satellite and in situ data for summer to autumn in the period 2011–2019. To investigate the cold …

Go to article

Seismic Attribute Recognition Technology Of Magmatic Rock Intrusive Coal Seam, Wu Bin, Meng Fanbin Dec 2020

Seismic Attribute Recognition Technology Of Magmatic Rock Intrusive Coal Seam, Wu Bin, Meng Fanbin

Coal Geology & Exploration

In order to increase the degree of production of CBM development blocks, when the production of a single well enters a decline period, the development plan needs to be adjusted, and the production increase and stability can be achieved through the measures such as layer adjustment or layer compensation. In terms of time, it is believed that the main coal seam should be developed first when it is put into production. After the decline period, the secondary main coal seam should be supplemented and combined; in space, combined with the development dynamics, the analytic hierarchy process is used to determine …

Go to article

Technology And Application Of High Efficiency Gas Extraction By Directional Long Borehole Hydraulic Fracturing In Coal Seams Of Medium Hardness And Low Permeability, Guo Chaoqi, Zhao Jizhan, Li Xiaojian, Zhang Jingfei, Wu Shengli, Chen Dongdong, Huang Xingli, Li Baojun Dec 2020

Technology And Application Of High Efficiency Gas Extraction By Directional Long Borehole Hydraulic Fracturing In Coal Seams Of Medium Hardness And Low Permeability, Guo Chaoqi, Zhao Jizhan, Li Xiaojian, Zhang Jingfei, Wu Shengli, Chen Dongdong, Huang Xingli, Li Baojun

Coal Geology & Exploration

Grouting quality test is the key technology for efficient development and utilization of waste land in the goaf of a coal mine, it is of great significance to evaluate the stability of the site and the safety of construction after goaf management. Based on many engineering practices, this paper summarizes the evaluation method of the qualified standards of the grouting quality and the errors existed in the testing work. The results proved that the quality inspection after grouting is a systematic work. The test method could be optimized according to the characteristics of the construction and grouting design requirements, following …

Go to article

Numerical Simulation Of Fractured Water-Conducting Zone By Considering Native Fractures In Overlying Rocks, Li Ruirui, Chen Luwang, Ou Qinghua, Chen Yifei, Wang Yingxin, Ge Rutao, Peng Zhihong Dec 2020

Numerical Simulation Of Fractured Water-Conducting Zone By Considering Native Fractures In Overlying Rocks, Li Ruirui, Chen Luwang, Ou Qinghua, Chen Yifei, Wang Yingxin, Ge Rutao, Peng Zhihong

Coal Geology & Exploration

The intelligent accurate coal mining needs to construct the high-precision and transparent 3D geological model, and the seismic data interpretation integrated into the dynamic roadway data provide data support for the model. The geological model of roadway is established and forward modeling is carried out to analyze the difference of seismic characteristics caused by a roadway. Based on curvature attribute principle, various seismic curvature attributes were applied to seismic data interpretation, guide the roadway recognition in the seismic data. The coal seam 2 of CJT coalfield was selected as the research object, and the high-quality seismic data and various attribute …

Go to article

Improvement And Optimization Of Permeability And Strength Properties Of Loess, Zhu Min, Ni Wankui, Yuan Kangze, Li Lan, Li Xiangning, Wang Haiman Dec 2020

Improvement And Optimization Of Permeability And Strength Properties Of Loess, Zhu Min, Ni Wankui, Yuan Kangze, Li Lan, Li Xiangning, Wang Haiman

Coal Geology & Exploration

In order to study the development of secondary faults and fracture, a boundary element method (BEM) combined with seismic interpretation of main faults and geo-mechanics is discussed. Firstly, with the Anderson's theory of faulting, the classification of secondary fault tectonic evolution events is improved under the combination of fault and stress; secondly, the stress tensor order reduction and linear superposition principle are applied to simplify the stress and displacement balance equation, and the Monte Carlo method is used to inverse the paleo-stress field. After all, the equilibrium equation of stress, strain and discontinuous displacement is solved to obtain the current …

Go to article

Penggunaan Neurodevelopmental Treatment Pada Kasus Dandy Walker Syndrome, Aditya Denny Dec 2020

Penggunaan Neurodevelopmental Treatment Pada Kasus Dandy Walker Syndrome, Aditya Denny

Jurnal Sosial Humaniora Terapan

Dandy Walker Syndrome (DWS) is a syndrome that occurs in a child due to a malformation that occurs during the development of the cerebellum and the fourth ventricle. One of the clinical manifestations of DWS is a balance disorder. The purpose of this case study was to determine the effectiveness of Neurodevelopmental Treatment (NDT) on standing balance in DWS cases with the Pediatric Balance Scale (PBS) parameter. The clinical question arises, how is the effectiveness of NDT to improve balance with the parameters of the pediatric balance scale in cases of dandy walker syndrome? To answer clinical problems, online literature …

Go to article

Vokhum Fest: A Specialized Integrated Marketing Communication Event Towards Small Medium Enterprises Brand Management And Youth Social Welfare Dec 2020

Vokhum Fest: A Specialized Integrated Marketing Communication Event Towards Small Medium Enterprises Brand Management And Youth Social Welfare

Jurnal Sosial Humaniora Terapan

Integrated Marketing Communication is an essential concept in marketing field. It is used worldwide to marketing and communicating in vary kind of business both in big enterprise or small enterprise. This article describes the implementation of IMC on an event marketing called Vokhum Fest as a community engagement program. The event is a collaboration between Vocational Education Program Universitas Indonesia lecturers, assistant lecturers, students and 12 Small Medium Enterprises (SMEs) in Jakarta Greater Area ranging from products to services also for the most part organized by youth. The purpose and benefits of this research are to see the impact of …

Go to article

Reception Test And Analysis Of Different Geophones In Coal Mining Districts Seismic Exploration, Zhang Libing, Dong Shouhua Dec 2020

Reception Test And Analysis Of Different Geophones In Coal Mining Districts Seismic Exploration, Zhang Libing, Dong Shouhua

Coal Geology & Exploration

During the development process of coalbed methane, the aggregation and sedimentation of coal fines can block the migration channel of coalbed methane and lead to accidents such as stuck pump and buried pump. In order to find out the aggregation and sedimentation characteristics of coal fines with different particle sizes, the aggregation and sedimentation experiments of coal fines with the particle size>140 mesh(<106 μm), 70 to 140 mesh(106-212 μm) and 50 to 70 mesh(212-300 μm) in deionized water were carried out. The aggregation and sedimentation characteristics of coal fines with different particle sizes in deionized water suspension were investigated from the suspension observation, the concentration characteristics of coal fines and the particle size distribution of coal fines in suspension. The results show that with the increase of the time, the color of coal fines suspension becomes lighter to different degrees, and the stratification of coal fines suspension gradually appears, and the suspension of coal fines with the particle size more than 140 mesh was the first to stratify among three suspensions. The smaller the particle sizes of coal fines, the more coal fines float on the top of the suspension, and the larger the particle sizes of coal fines, the more coal fines sink to the bottom of the suspension. The concentration of coal fines in the suspensions decreased to different degrees with the increase of the time. The concentration of coal fines decreased the fastest within 3 minutes after stopping the stirring. The concentration of coal fines with the particle sizes of 70 to 140 mesh in suspension was the largest among three suspensions. According to the particle size distribution curves, the process of aggregation and sedimentation of coal fines was divided into three stages: single peak to double peak(rapid floating and settlement of coal fines), double peak to single peak(rapid accumulation and settlement of coal fines) and single peak(slow sedimentation of coal fines). Coal fines with particle size more than 140 mesh in the suspension was the first to reach the stage of slow sedimentation, and coal fines with particle size of 70-140 mesh in the suspension reached the stage of slow sedimentation at the latest among three suspensions. The mechanism of aggregation and sedimentation of coal fines was discussed from the aspects of the force of coal fines, the extended DLVO theory, and the organic molecular structure of coal fines. The coal samples contain a large number of hydrophobic groups, such as aliphatic hydrocarbon and aromatic hydrocarbon, therefore, they have strong hydrophobicity and low wettability. With the decrease of particle sizes of coal fines, its specific surface area increases significantly, and a large amount of air is absorbed on the surface of coal fines, forming an air film. At the same time, particles of coal fines are adsorbed and aggregated with each other, and many micro pores are formed inside, resulting in that coal fines with small particle size is easy to aggregate and float on the suspension surface.

Go to article

Late Pleistocene Sedimentary Features And The Palaeoclimatic Background In Hongsibao Basin, Li Zhenhong, Cui Jiawei, Li Chaozhu, Jiang Boyu, Huang Ting Dec 2020

Late Pleistocene Sedimentary Features And The Palaeoclimatic Background In Hongsibao Basin, Li Zhenhong, Cui Jiawei, Li Chaozhu, Jiang Boyu, Huang Ting

Coal Geology & Exploration

The chuck is an important part of the coal mine tunnel drilling rig. The performance of the chuck directly affects the efficiency and quality of drilling. Aiming at the problems of the rubber cylinder hydraulic chuck. a new radial piston hydraulic chuck is studied. The objective of this paper is to devise a new radial piston hydraulic chuck instead of rubber-sleeve hydraulic chuck. Then, the motion mathematical model of radial piston hydraulic chuck was established based on the radial piston chuck clamping and loosening of system structure and working principle. At the same time, a dynamic co-simulation of chuck hydraulic …

Go to article

Development Of Collision Avoidance Algorithm Based On Consciousness Of Ship Operator, Eunkyu Lee, Young-Soo Park, Minjeong Park, Myoung-Ki Lee, Eunbi Park, In-Young Gong Dec 2020

Development Of Collision Avoidance Algorithm Based On Consciousness Of Ship Operator, Eunkyu Lee, Young-Soo Park, Minjeong Park, Myoung-Ki Lee, Eunbi Park, In-Young Gong

Journal of Marine Science and Technology–Taiwan

Several collision avoidance algorithms employing various methods have been developed to date. In this paper, a collision avoidance algorithm is proposed based on the potential assessment of risk (PARK) model, which is a maritime traffic risk assessment model based on the characteristics of the Korean coastal regions and the consciousness of a ship’s operator. The proposed collision avoidance algorithm is intended to be used in the transition period during which autonomous and human-operated ships sail simultaneously. The algorithm avoids collisions using the PARK model that reflects the International Regulations for Preventing Collisions at Sea. Situations such as head-on, crossing, overtaking, …

Go to article

First Prev Next Last