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 451 - 480 of 39127

Full-Text Articles in Entire DC Network

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 An Accurate Underwater Location Of Hybrid Underwater Gliders Using Machine Learning, Sang-Ki Jeong, Hyeung-Sik Choi, Dea-Hyung Ji, Mai The Vu, Joon-Young Kim, Sung Min Hong, Hyun Joon Cho Dec 2020

A Study On An Accurate Underwater Location Of Hybrid Underwater Gliders Using Machine Learning, Sang-Ki Jeong, Hyeung-Sik Choi, Dea-Hyung Ji, Mai The Vu, Joon-Young Kim, Sung Min Hong, Hyun Joon Cho

Journal of Marine Science and Technology–Taiwan

A hybrid underwater glider (HUG) is marine observation equipment that consumes a small amount of energy and offers greater range and navigation times. To achieve reduced energy consumption, however, the HUG uses imprecise navigation sensors, such as mems-type GPS and AHRS, resulting in inaccurate coordination. This study makes a new attempt on the application of machine learning algorithms in a way that complements sensor data errors to improve navigation performance. The proposed algorithm was used to a simulation of the HUG’s navigation and control system, after which the updated heading angle was decided by using the previous position data and …

Go to article

A New Complex Marine Unmanned Platform And Field Test, Jihyeong Lee, Han-Sol Jin, Hyunjoon Cho, Jiafeng Huang, Sang-Ki Jeong, Dae-Hyeong Ji, Hyeung-Sik Choi Dec 2020

A New Complex Marine Unmanned Platform And Field Test, Jihyeong Lee, Han-Sol Jin, Hyunjoon Cho, Jiafeng Huang, Sang-Ki Jeong, Dae-Hyeong Ji, Hyeung-Sik Choi

Journal of Marine Science and Technology–Taiwan

This paper presents the development of a new complex marine unmanned platform composed of an unmanned surface vehicle (USV) and a remotely operated vehicle (ROV), and the results of a sea test. The platform structure, control system, sensor system, and control algorithm were developed and are introduced. The complex platform collects information of the underwater structures, such as the wall, floor, and piers and harbors. Using a tether cable, the ROV is connected to the USV for power supply and to receive a large amount of underwater data obtained using a sonar scanner or a camera in real time. The …

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

Modeling Navigator Errors In Collisions Using Hidden Markov Models, Deuk-Jin Park, Jeong-Bin Yim, Chun-Ki Lee Dec 2020

Modeling Navigator Errors In Collisions Using Hidden Markov Models, Deuk-Jin Park, Jeong-Bin Yim, Chun-Ki Lee

Journal of Marine Science and Technology–Taiwan

Understanding navigator errors can be used as a basis for preventing collisions. Here, Hidden Markov Models (HMMs) are applied to navigator errors of fishing and merchant ships in collisions. Information on navigator errors providedin accident investigation reports issued by the Korean Maritime Safety Tribunal is surveyed. The surveyed information is converted into data using the framework of slips, lapses, and mistakes proposed in this study. The results of framework data states are inferred using the unsupervised learning of HMMs, with sequences of navigator errors contained in the error data. The expected errors learned using the navigator error models for fishing …

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

Short-Term Fatigue Damage Of Tethers Of Long-Span Floating Cable Supported Bridges Under Harsh Waves, Deokhee Won, Keesei Lee, Young-Jong Kang, Seungjun Kim Dec 2020

Short-Term Fatigue Damage Of Tethers Of Long-Span Floating Cable Supported Bridges Under Harsh Waves, Deokhee Won, Keesei Lee, Young-Jong Kang, Seungjun Kim

Journal of Marine Science and Technology–Taiwan

A floating bridge can be effectively used for sea-crossing in deep water. Because the superstructure of the bridge is supported by floating substructures with pontoons, the conventional fixed piers, towers, foundations, and piles are not required. Instead, a rational mooring system can be used to strictly maintain the target position of the floating substructures against environmental loads, including winds, waves, and currents. Recently, long-span cable-supported bridges with floating towers were investigated and found to overcome the limitations of conventional cable-supported bridges, when used as sea-crossing infrastructure. To design the moorings for very large floating structures, the structural safety should be …

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

Dynamic Modelling And Experimental Results Of A Ray-Type Hybrid Underwater Glider With A Dualbuoyancy Engine, Ngoc-Duc Nguyen, Hyeung-Sik Choi, Sung-Wook Lee, Wen-Hsiang Hsieh, Sang-Ki Jeong, Dae-Hyeong Ji Dec 2020

Dynamic Modelling And Experimental Results Of A Ray-Type Hybrid Underwater Glider With A Dualbuoyancy Engine, Ngoc-Duc Nguyen, Hyeung-Sik Choi, Sung-Wook Lee, Wen-Hsiang Hsieh, Sang-Ki Jeong, Dae-Hyeong Ji

Journal of Marine Science and Technology–Taiwan

For ocean observation and exploration, underwater gliders (UG) have shown their efficient long-range operation with buoyancy propulsion. The current Torpedo-shape UGs have small buoyancy capacity and insufficient space for batteries and sensors. In this paper, a Ray-type hybrid underwater glider (RHUG) is developed with new hull design, dual-buoyancy engine, and thrusters. The control system of the RHUG is constructed for gliding motion. To understand the characteristic of the RHUG, dynamic modelling of the dual-buoyancy engine was established. To verify the proposed dynamics model, a navigation experiment using the developed RHUG platform was carried out. Through comparison between experiment and simulation …

Go to article

Diffusing New Media As Know-How Digital Communication In Troubleshoot Maintenance Of Pico Hydro Technology In Bengkulu, Indonesia Dec 2020

Diffusing New Media As Know-How Digital Communication In Troubleshoot Maintenance Of Pico Hydro Technology In Bengkulu, Indonesia

Jurnal Sosial Humaniora Terapan

Communication has an important role for spreading messages and ideas through various mediums. This research explains the important role of new media in community engagement activities and the dissemination of new information, innovations and technologies that have been done in 2017, especially for the graphic design via the internet on Pico Hydros information technology in Batu Roto village, Bengkulu province, Indonesia. Community involvement itself is based on a special multidisciplinary perspective of communication and engineering. Pico Hydro is commonly used worldwide to generate electricity in rural areas, making it very useful for rural electrification. We conduct research to meet the …

Go to article

Perbandingan Empat Jalur Distribusi Pada Pemasukan Premi Asuransi Dec 2020

Perbandingan Empat Jalur Distribusi Pada Pemasukan Premi Asuransi

Jurnal Sosial Humaniora Terapan

This study aims to discuss the distribution of insurance sales. In addition, researchers will also calculate the contribution of each distribution channel to premium income in PT X. The data used are secondary data from 2017-2019. The data obtained is analyzed statistically as descriptive to provide information on the contribution to each lane. The best achievement is measured from the target presentation with the realization of sales results. PT X has 4 sales distribution channels, namely Agency, Bancassurance, Direct Marketing TeleMarketing (DMTM), and Corporate Solution. The results of the study explained that the highest achievement was DMTM and the lowest …

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

Identifying High-Collision Potential Vessel-Bridge Pairs In Vessel Traffic Service, Jeong-Bin Yim, Chun-Ki Lee Dec 2020

Identifying High-Collision Potential Vessel-Bridge Pairs In Vessel Traffic Service, Jeong-Bin Yim, Chun-Ki Lee

Journal of Marine Science and Technology–Taiwan

Collision risk assessment for maritime traffic monitoring in vessel traffic service (VTS) is a key technology for ensuring the safety of both vessels and bridges. This study proposes a risk assessment methodology using a single measure of collision risk ratio that could assist in reducing the cognitive load of VTS operators. To explain the proposed method, we first define the semantic and mathematical relationship of vessel– bridge pier collisions; then, we establish the risk assessment framework using the collision risk ratio by combining deviation angle and stopping distance probabilities. To validate the proposed method, we conducted an experiment in the …

Go to article

Experimental And Numerical Investigations On The Hydrodynamic Characteristics Of The Planar Motion Of An Open-Frame Remotely Operated Vehicle, Ying-Fei Zan, Rui-Nan Guo, Li-Hao Yuan, Shi-Peng Wang, Da-Zhong Zhang, Shi-Jing Xu, Zhao-Hui Wu Dec 2020

Experimental And Numerical Investigations On The Hydrodynamic Characteristics Of The Planar Motion Of An Open-Frame Remotely Operated Vehicle, Ying-Fei Zan, Rui-Nan Guo, Li-Hao Yuan, Shi-Peng Wang, Da-Zhong Zhang, Shi-Jing Xu, Zhao-Hui Wu

Journal of Marine Science and Technology–Taiwan

In this study, the longitudinal, sideways, vertical, and sideslip motions of an open-frame remotely operated vehicle (ROV) were experimentally and numerically investigated. The open-frame ROV was designed to be asymmetric in both the longitudinal and vertical directions to achieve special functionalities. A physical ROV model was tested in a towing tank with different velocities and sideslip angles in the horizontal and vertical planes. A numerical simulation was conducted with the same working conditions used in the scaled model tests by using a segregated flow solver based on Reynolds-averaged Navier–Stokes equations. This study investigated the effect of the hydrodynamic forces (moments) …

Go to article

An Enhanced Sliding Mode Control Method For Wave Compensation System Of Ship-Mounted Cranes With Roll Motions And Parametric Uncertainties, Hai-Yan Qiang, Si Xie, Zhi-Qiang Xu, You-Gang Sun Dec 2020

An Enhanced Sliding Mode Control Method For Wave Compensation System Of Ship-Mounted Cranes With Roll Motions And Parametric Uncertainties, Hai-Yan Qiang, Si Xie, Zhi-Qiang Xu, You-Gang Sun

Journal of Marine Science and Technology–Taiwan

Ship-mounted cranes are widely used in offshore constructions, resource exploitation and marine salvages, to transfer payloads. Due to serious sea conditions, unexpected motions of the ships caused by the wave will probably pose serious efficiency and security issues. Thus, the wave compensation system has become necessary equipment for the shipmounted crane. But wave-induced motions of the ship, parametric uncertainties and nonlinearities remain challenges for control of wave compensation systems, which needs to be solved urgently. In this paper, the mathematical model of the wave compensation system is established firstly. Then, a sliding mode controller is presented and the stability is …

Go to article

Study On Underwater Navigation For Underwater Track Vehicle, Dae-Hyeong Ji, Hyeung-Sik Choi, Sang-Ki Jeong, Hyun-Joon Cho, Ji-Hyeong Lee, Wen-Hsiang Hsieh Dec 2020

Study On Underwater Navigation For Underwater Track Vehicle, Dae-Hyeong Ji, Hyeung-Sik Choi, Sang-Ki Jeong, Hyun-Joon Cho, Ji-Hyeong Lee, Wen-Hsiang Hsieh

Journal of Marine Science and Technology–Taiwan

In this study, an underwater navigation algorithm was developed to apply a navigation system to an underwater track vehicle (UTV). Generally, a Doppler velocity log (DVL) is used to obtain the velocity information of underwater vehicles. However, a DVL cannot be used in a UTV owing to vehicle vibration and limited sensing distance. Hence, dead reckoning navigation is typically used, which results in severe errors in altitude and position values over long periods of operation. To address these problems, in this study, we developed a new underwater navigation system for a UTV using navigation sensors comprising an inertial navigation system, …

Go to article

A Study On The Analysis Of Minimum Speed Control Effect Using Queue Model Focused On Busan Port, Sangwon Park, Won-Sik Kang, Young-Soo Park Dec 2020

A Study On The Analysis Of Minimum Speed Control Effect Using Queue Model Focused On Busan Port, Sangwon Park, Won-Sik Kang, Young-Soo Park

Journal of Marine Science and Technology–Taiwan

VTS aims to increase the efficiency of maritime traffic in two ways. The first is a decrease in marine accidents, and the second is an increase in the utilization rate of infrastructure such as waterways and port facilities. This means that, if safety is guaranteed, efficiency must also be considered in the VTS. The purpose of this study is to quantitatively analyze the effects of speed regulation under safe conditions for an efficient use of waterways. A model was developed using a queue approach, and the effect of the waiting time according to the minimum speed proposal was analyzed through …

Go to article

Vision Based Target Recognition For Cage Aquaculture Detection, Chao-Xun Chen, Jih-Gau Juang Dec 2020

Vision Based Target Recognition For Cage Aquaculture Detection, Chao-Xun Chen, Jih-Gau Juang

Journal of Marine Science and Technology–Taiwan

This study applies Unmanned Aerial Vehicle (UAV) to netcage fish-farming. The UAV can fly thru cages along a predefined route. At each cage, the UAV can automatically drop sensors to collect the environment data around the cage. However, low cost commercial or assembled drone might not have precise Global Navigation Satellite System (GNSS). Also, there are many uncertain factors cause Global Positional System (GPS) instability, like weather, location…etc. The main idea of this study is using GPS to guide the drone to approximated location of each cage. Then, apply image recognition to obtain the net-cage and UAV relative position. After …

Go to article

Dynamic Behavior Of A Long-Span Cable-Stayed Bridge With Floating Towers After The Sudden Failure Of Tethers And Cables Under Irregular Waves, Minseo Jang, Yunwoo Lee, Seungjun Kim, Young-Jong Kang Dec 2020

Dynamic Behavior Of A Long-Span Cable-Stayed Bridge With Floating Towers After The Sudden Failure Of Tethers And Cables Under Irregular Waves, Minseo Jang, Yunwoo Lee, Seungjun Kim, Young-Jong Kang

Journal of Marine Science and Technology–Taiwan

Cable-supported bridges with floating towers do not require fixed piers at the seabed. Therefore, innovative conceptual models have been continuously developed to overcome the limitations of conventional bridges in deep waters. The main floating tower that supports superstructures using stay cables is balanced by the buoyancy of floaters moored by tethers. The applicability of floating bridges should be verified by evaluating the overall stability considering the tether design. Here, various cases of the sudden failure of tethers and stay cables under the environmental conditions of a 100-year return period are simulated in a time-domain. The floating cable-stayed bridges are subjected …

Go to article

Internal Force Evaluation Of A Submerged Floating Pipeline Under Irregular Waves, Deokhee Won, Jihye Seo, Jong Sup Park, Seungjun Kim Dec 2020

Internal Force Evaluation Of A Submerged Floating Pipeline Under Irregular Waves, Deokhee Won, Jihye Seo, Jong Sup Park, Seungjun Kim

Journal of Marine Science and Technology–Taiwan

Generally, submarine pipelines are laid on the seabed to transport water, oil, natural gas, and electricity to the land using submarine cables. However, they are not suitable for all seafloor conditions. There are environmental concerns such as deep seas, irregular seabed features, soft soils, transported materials and so on. To overcome these challenges, a submerged floating pipeline (SFP) concept was proposed. To stay in the middle of the water, the SFP has buoyant modules as floating devices. It is unrestricted under environments such as uneven seabeds, and deep waters, and is suspended to avoid interrupting passing vessels. This SFP model …

Go to article

The Continuous Intention To Use E-Learning, From Two Different Perspectives, Rana Saeed Al-Maroof, Khadija Alhumaid, Said Salloum Dec 2020

The Continuous Intention To Use E-Learning, From Two Different Perspectives, Rana Saeed Al-Maroof, Khadija Alhumaid, Said Salloum

All Works

During the recent vast growth of digitalization, e-learning methods have become the most influential phenomenon at higher educational institutions. E-learning adoption has proved able to shift educational circumstances from the traditional face-to-face teaching environment to a flexible and sharable type of education. An online survey was conducted, consisting of 30 teachers and 342 students in one of the universities in the United Arab Emirates. The results show that teachers’ and students’ perceived technology self-efficacy (TSE), ease of use (PEOU), and usefulness (PU) are the main factors directly affecting the continuous intention to use technology. Instructors’ technological pedagogical content knowledge (TPACK) …

Go to article

Biogas Production Of Lignite And Variation Characteristics Of Cations In Liquid Phase System, Zhao Han, He Huan, Wang Jiangze, Song Yanli, Niu Jianglu, Chen Linyong, Guo Xin, Liu Jian, Guan Jiadong, Yuan Xuefang Dec 2020

Biogas Production Of Lignite And Variation Characteristics Of Cations In Liquid Phase System, Zhao Han, He Huan, Wang Jiangze, Song Yanli, Niu Jianglu, Chen Linyong, Guo Xin, Liu Jian, Guan Jiadong, Yuan Xuefang

Coal Geology & Exploration

Liupan Shan lies between the Tibetan plateau and Ordos block and has been under the remote effect of the northeastward extension of the Tibetan plateau. The former research about the uplift of Liupan Shan mainly focused on the petrology, structural deformation or tectonic evolution study from the Cretaceous to early period of Cenozoic. However, the Late Pleistocene geological study closely connected with the human activities was rarely mentioned. In this study, we carried out systematic sedimentary research in the Qingshuihe basin adjacent to the Liupan Shan tectonic belt, re-determine the sedimentary sequence at first, then reverse the uplift history of …

Go to article

Pattern And Effect Of The High Density 3d Seismic Exploration In Coal Mining Districts, Jin Xueliang, Wang Qi Dec 2020

Pattern And Effect Of The High Density 3d Seismic Exploration In Coal Mining Districts, Jin Xueliang, Wang Qi

Coal Geology & Exploration

Graphene is an emerging carbon nanomaterial in the 21st century, has excellent properties and shows great application potential in many fields. Coal is the most abundant and the cheapest carbon source with unique structure and material composition. The application of coal in the development and the application of new carbonaceous materials such as graphene and their composites is a work worthy of further exploration. The development of coal-based graphene can both promote the clean utilization of coal and enhance the added value of coal resources. In this paper, the research developments in coal structure, the mechanism of coal graphitization, as …

Go to article

Analysis Of Channel Imaging Effect Of High Density And Conventional Observation System, Zhang Xianxu Dec 2020

Analysis Of Channel Imaging Effect Of High Density And Conventional Observation System, Zhang Xianxu

Coal Geology & Exploration

Aiming at the problems of uncontrollable trajectory, shallow borehole depth and poor gas extraction effect in gas treatment drilling of broken soft coal seam in Qinglong coal mine, the regional progressive gas extraction technology in broken soft coal seam based on compressed-air directional drilling was proposed, on the basis of analyzing the technical bottleneck of existing gas extraction borehole with rotary drilling. The principle and advantage of the technology was expounded, the technology of directional drilling by compressed-air, the technology of long distance in-seam drilling, and the technology of compound slag discharge by double power were integrated. The field test …

Go to article

First Prev Next Last