scholarly journals Innovative Method for Ship Navigation Safety Risk Response in Landslide-Induced Wave

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Peiyin Yuan ◽  
Pingyi Wang ◽  
Yu Zhao
Keyword(s):  
High Speed ◽  
Propagation Characteristics ◽  
Wave Direction ◽  
Safety Risk ◽  
Risk Response ◽  
Innovative Method ◽  
Mooring Cable ◽  
Ship Navigation ◽  
Motion Characteristics ◽  
Navigation Safety

When the bank of a reservoir slope slides along a weak structural plane at a high speed, “landslide slamming” will occur in the nearby water. The formation of landslide-induced waves is a serious threat to the safety of wharfs, shore marks, buildings in the water, and vessels navigating in reservoir areas. To ensure the safety of navigating ships, this study proposes a landslide-induced wave water ship navigation safety risk response technology. The propagation characteristics of landslide-induced waves are analysed based on a physical model experiment, and the characteristics of a ship's motion response and mooring cable tensions are studied under conditions of bow and stern mooring and multipoint mooring. The influences of the landslide-induced wave direction and ship navigation position on the ship rolling motion characteristics are discussed. The results of this study can further improve the navigation safety of ships in landslide-induced wave waters.

scholarly journals High speed magneto-optical imaging system to investigate motion characteristics of arc plasma in enclosed chamber

2018 ◽  
Vol 26 (18) ◽  
pp. 23156 ◽  
Author(s):  
Guogang Zhang ◽  
Zhiqiang Zhang ◽  
Youdang Xu ◽  
Jianhua Wang
Keyword(s):  
Optical Imaging ◽  
High Speed ◽  
Imaging System ◽  
Arc Plasma ◽  
Optical Imaging System ◽  
Enclosed Chamber ◽  
Motion Characteristics

scholarly journals Adjustment of Maintenance Approach for Improved Operability and Safety of Ship Navigation

2012 ◽  
Vol 22 (2) ◽  
pp. 95-103
Author(s):  
Ante Bukša ◽  
Ivica Šegulja ◽  
Vinko Tomas
Keyword(s):  
Risk Analysis ◽  
Lower Risk ◽  
Risk Index ◽  
Exhaust Valve ◽  
Maintenance Policy ◽  
Proposed Model ◽  
Risk Criterion ◽  
Ship Navigation ◽  
Definition Of ◽  
Navigation Safety

By adjusting the maintenance approach towards the significant components of ship’s engines and equipment, through the use of operational data from the ship machinery’s daily reports, higher operability and navigation safety can be achieved. The proposed maintenance adjustment model consists of an operation data analysis and risk analysis. The risk analysis comprises the definition of the upper and the lower risk criterion, as well as the definition of a risk index. If the risk index is higher than the lower risk criterion, the component is significant, while it is not significant and has an acceptable risk index if the risk index is lower than the lower risk criterion. For each significant component with a risk index found to be “unacceptable” or “undesirable”, an efficient maintenance policy needs to be adopted. The assessment of the proposed model is based on data regarding the power engine original operation throughout a 13-year period. The results of engine failure examinations reveal that the exhaust valve is the most vulnerable component with the highest rate of failure. For this reason the proposed model of adjusting the maintenance approach has been tested on the exhaust valve sample. It is suggested that the efforts to achieve higher ship operability and navigation safety should go in the direction of periodical adjustments of the maintenance approach i.e. choosing an efficient maintenance policy by reducing the risk indices of the significant engine components. KEY WORDS: maintenance adjustment approach, risk analysis, risk index, lower risk criterion, upper risk criterion, significant components, ship navigation

Integrated Optimal Design of Planar Mechanisms Using Fuzzy Theories

1989 ◽  
Author(s):  
A. K. Dhingra ◽  
S. S. Rao
Keyword(s):  
Nonlinear Programming ◽  
High Speed ◽  
Integrated Approach ◽  
Problem Formulation ◽  
Optimization Techniques ◽  
Motion Path ◽  
Programming Formulation ◽  
Planar Mechanisms ◽  
Dynamic Synthesis ◽  
Motion Characteristics

Abstract A new integrated approach to the design of high speed planar mechanisms is presented. The resulting nonlinear programming formulation combines both the kinematic and dynamic synthesis aspects of mechanism design. The multiobjective optimization techniques presented in this work facilitate the design of a linkage to meet several kinematic and dynamic design criteria. The method can be used for motion, path, and function generation problems. The nonlinear programming formulation also permits the imposition of constraints to eliminate solutions which possess undesirable kinematic and motion characteristics. To model the vague and imprecise information in the problem formulation, the tools of fuzzy set theory have been used. A method of solving the resulting fuzzy multiobjective problem using mathematical programming techniques is presented. The outlined procedure is expected to be useful in situations where doubt arises about the exactness of permissible values, degree of credibility, and correctness of statements and judgements.

Experimental Study on Cavitation Motion of Underwater Vehicle With Protrusions

2020 ◽  
Author(s):  
Zhaoyu Qu ◽  
Ning Gan ◽  
Yingyu Chen ◽  
Nana Yang
Keyword(s):  
High Speed ◽  
Underwater Vehicle ◽  
Test Method ◽  
Scale Model ◽  
Small Scale ◽  
Reduced Pressure ◽  
Local Flow ◽  
Bubble Generation ◽  
Scale Characteristics ◽  
Motion Characteristics

Abstract For underwater vehicles with protrusions (external structure), the geometric shape of the protrusions is bound to affect the local flow field of the vehicles during the moving process of the vehicles, thus affecting the generation, development and collapse of cavitation around the vehicles. The cavitation may break, fall off and collapse randomly, and other local movements may affect the motion attitude of the underwater vehicle. It is an effective method to study fluid dynamics to simulate prototype cases with small scale models. In this paper, we mainly use the small scale model test method to explore the cavitation motion characteristics of the vehicle in water with protrusions. Through the establishment of a set of vehicle motion test equipment under reduced pressure, a series of experiments were conducted on this basis to explore the motion characteristics of vehicle cavitation under different bump shapes. In this study, two high-speed cameras were used to simultaneously record cavitation generation, development, collapse and other characteristics, to analyze the bubble generation mechanism and scale characteristics caused by the bulge, and then to study the influence of cavitation induced by the bulge on the motion attitude of the vehicle.

scholarly journals Optimization and Experimental Study of the Semi-Closed Short-Gap Arc-Extinguishing Chamber Based on a Magnetohydrodynamics Model

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3335 ◽  
Author(s):  
Wenbin Jia ◽  
Wenxia Sima ◽  
Tao Yuan ◽  
Ming Yang ◽  
Potao Sun
Keyword(s):  
High Speed ◽  
Basic Structure ◽  
Optimization Method ◽  
Original Structure ◽  
Arc Plasma ◽  
Zero Crossing ◽  
In Series ◽  
Power Frequency ◽  
Motion Characteristics ◽  
Current Zero

The multi-chamber arc-extinguishing structure (MAS), which consists of a lot of semi-closed short-gap arc-extinguishing chambers (SSAC) in series, can be used in parallel gap lightning protection devices to improve the ability to extinguish power frequency follow current. The arc-extinguishing ability of single SSAC directly affects the arc-extinguishing performance of the whole MAS. Therefore, the arc-extinguishing performance of MAS can be improved by optimizing single SSACs. A two-dimensional model of the arc plasma in a SSAC is built based on the magneto-hydrodynamic (MHD) theory. The motion characteristics of an arc in the SSAC are simulated and analyzed. An optimization method of the SSAC structure is proposed. Finally, an impact test platform is built to verify the effectiveness of the optimized SSAC structure. Results show that the short-gap arc forms a high-speed airflow in the SSAC and the arc plasma sprays rapidly to the outlet until the arc is extinguished at its current zero-crossing point. The amplitude of airflow velocity in the optimized structure can be increased to about 8-fold the velocity in the basic structure. Experiments also show that the dissipation time of an arc in the optimized SSAC is 79.2 μs, which is much less than that in the original structure (422.4 μs).

scholarly journals An empirical analysis of the radio propagation characteristics in high-speed railway environment

2017 ◽  
Vol 231 ◽  
pp. 012077
Author(s):  
Guoqing Hu ◽  
Guangjin Ma ◽  
Chunlai Li ◽  
Yongchi Xu ◽  
Jin He ◽  
...  
Keyword(s):  
Empirical Analysis ◽  
High Speed ◽  
Radio Propagation ◽  
Propagation Characteristics ◽  
High Speed Railway

scholarly journals Propagation characteristics of wideband high-speed railway channel in viaduct scenario at 2.35 GHz

2012 ◽  
Vol 20 (4) ◽  
pp. 206-212 ◽  
Author(s):  
Yunling Guo ◽  
Jianhua Zhang ◽  
Cheng Tao ◽  
Liu Liu ◽  
Lei Tian
Keyword(s):  
High Speed ◽  
Propagation Characteristics ◽  
High Speed Railway

High-speed photographic analysis of microwave plasma torch source behaviour

2016 ◽  
Vol 31 (3) ◽  
pp. 759-766 ◽  
Author(s):  
Bingwen Yu ◽  
Wei Jin ◽  
Yangwei Ying ◽  
Haixiang Yu ◽  
Dan Zhu ◽  
...  
Keyword(s):  
Plasma Torch ◽  
High Speed ◽  
Microwave Plasma ◽  
High Speed Camera ◽  
Photographic Analysis ◽  
Microwave Plasma Torch ◽  
Motion Characteristics ◽  
First Time

Spatiotemporal motion characteristics of the microwave plasma torch (MPT) source were for the first time investigated with a high-speed camera.

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