scholarly journals A Study on the Minimum Safe Distance between Two Vessels in Confined Waters

2014 ◽  
Vol 38 (6) ◽  
pp. 561-565 ◽  
Author(s):  
Chun-Ki Lee ◽  
Serng-Bae Moon
Keyword(s):  
Safe Distance ◽  
Minimum Safe Distance

The Avoidance of Close Quarters in Clear Weather

1982 ◽  
Vol 35 (1) ◽  
pp. 151-159 ◽  
Author(s):  
R. A. Cahill
Keyword(s):  
Safe Distance ◽  
Minimum Safe Distance ◽  
Different Order ◽  
Clear Weather

What constitutes a minimum safe distance of approach in an overtaking or meeting situation is a problem that has engaged the interest of seamen since steam began to supplant sail. Prior to that time vessels were often obliged to steer zig-zag courses in tacking against the wind, and though they were probably no less concerned with avoiding a collision the problem was of a different order.

Minimum Safe Distance from Pool Fires

2000 ◽  
Vol 16 (4) ◽  
pp. 649-652 ◽  
Author(s):  
David G. Lilley
Keyword(s):  
Pool Fires ◽  
Safe Distance ◽  
Minimum Safe Distance

scholarly journals State movement for controlling trains operating under the virtual coupling system

2021 ◽  
pp. 095440972110437
Author(s):  
Naphat Ketphat ◽  
Anthony Whiteing ◽  
Ronghui Liu
Keyword(s):  
High Capacity ◽  
Operation Time ◽  
Separation Distance ◽  
Safe Distance ◽  
Signaling Systems ◽  
Time Period ◽  
Coupling System ◽  
Virtual Coupling ◽  
Braking Distance ◽  
Minimum Safe Distance

Train Virtual Coupling System (VCS) has been proposed as a new signalling system for controlling trains by building a group of trains as convoys in order to increase line’s capacity. This is achieved because the consecutive trains under the VCS is separated only by a relative braking distance; this is much shorter than the separation distance required in the Fixed Block Signaling (FBS) and Moving Block Signaling systems (MBS). In order to achieve the high capacity obtained from the VCS, the trains in a virtually coupled convoy should keep at a distance as close to the relative braking distance as possible and run at the same speed for maintaining the safe distance between them. In this paper, we propose a distance and velocity difference approach and introduce the multiple state movements for stimulating train’s movement under the VCS. The simulated results show that the capacity can be significantly increased and maximized in which the actual separation distance between trains when they are in convoy state is slightly longer than the minimum safe distance. It could be ensured that the train has proceeded safely in that the actual separation distance is surely longer than the minimum safe distance throughout the operation time period. In addition, we show that the trains can also proceed smoothly, in that a following train catches up with its leading train and joined in the convoy with a stable movement.

scholarly journals Modeling and Analysis on Minimum Safe Distance for Platooning Vehicles Based on Field Test of Communication Delay

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Mengyan Hu ◽  
Xiangmo Zhao ◽  
Fei Hui ◽  
Bin Tian ◽  
Zhigang Xu ◽  
...  
Keyword(s):  
Traffic Safety ◽  
Field Tests ◽  
Transportation Systems ◽  
Communication Delay ◽  
Ieee 802.11P ◽  
Safe Distance ◽  
Automated Driving ◽  
Emergency Braking ◽  
The Impact ◽  
Minimum Safe Distance

Vehicle platooning is a perspective technique for intelligent transportation systems (ITS). Connected and automated vehicles (CAVs) use dedicated short-range communication (DSRC) to form a convoy, in which the following vehicles can receive the information from their preceding vehicles to achieve safe automated driving and maintain a short headway. Consequently, a vehicle platoon can improve traffic safety and efficiency, further reducing fuel consumption. However, emergency braking inevitably occurs when the platoon meets an accident or a sudden mechanical failure. It is more critical when the wireless communication got delays. Therefore, “how to predefine a minimum safe distance (MSD) considering communication delay” is a challenging issue. To this end, a series of field tests were carried out to measure the communication delay of IEEE 802.11p that is the underlying protocol of DSRC. Subsequently, MSD is modeled and analyzed when the platoon travels at accelerating, cruising, and decelerating states. More importantly, the results of field tests are applied in the models to investigate the impact of communication delay on MSD in practice. The simulation results verify that the proposed model can effectively maintain the platooning vehicles’ safety even if emergency braking happens with certain communication delays.

scholarly journals Prediction of the Collapse Region Induced by a Concealed Karst Cave above a Deep Highway Tunnel

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Fu Huang ◽  
Di Wang ◽  
Yuan Feng ◽  
Min Zhang
Keyword(s):  
Rock Mass ◽  
Karst Cave ◽  
Favorable Result ◽  
Safe Distance ◽  
Upper Bound Theorem ◽  
Analytical Expression ◽  
Highway Tunnel ◽  
Concealed Karst Cave ◽  
Collapse Region ◽  
Minimum Safe Distance

The presence of a concealed karst cave above a deep highway tunnel may cause the collapse of the rock mass between the karst cave and tunnel during excavation. Rock mass collapse threatens the safety of tunnel construction personnel. A prediction method of the collapse region induced by a concealed karst cave above a deep highway tunnel is proposed on the basis of the upper bound theorem of limit analysis. An analytical expression of the collapse surface is derived from the variational principle. Using the analytical expression of the collapse surface, the shapes of the collapse surfaces are plotted for different rock mass parameters. Moreover, the minimum safe distance between the karst cave and tunnel is defined, and the computational equation of the minimum safe distance is derived. The proposed method is applied in a highway tunnel excavated in a karst terrain as a case study. Based on geological survey report parameters, the shape of the collapse surface and the minimum safe distance between the karst cave and tunnel are obtained. Finally, the collapse surface of the rock mass provided by the proposed approach is compared with that provided by numerical simulation, and the favorable result comparison shows that the proposed method is valid.

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