scholarly journals Estimating Critical Latency Affecting Ship’s Collision in Re-mote Maneuvering of Autonomous Ships

2021 ◽  
Vol 11 (22) ◽  
pp. 10987
Author(s):  
Jeong-Bin Yim ◽  
Deuk-Jin Park
Keyword(s):  
Simulation Experiment ◽  
Experimental Results ◽  
Ship Maneuvering ◽  
Time Ratio ◽  
Turning Maneuver

Estimation of the critical latency that can cause collision in remote maneuvering of autonomous ships can provide a clue to avoid collisions. The concept of estimating the critical latency was established using the turning circle formed by the turning maneuver of the own ship, and critical latency was estimated using the radius of the turning circle with the turning time ratio. The turning circle was observed using the turning trajectory of the give-way vessel measured in the ship maneuvering simulation experiment. Experimental results demonstrated that the proposed method is capable of identifying both the location and time of the collision due to critical latency. As a result, a clue to avoid possible collision in remote maneuvering caused by critical latency was deduced.

Effects of Hull and Control Surface Roughness on Ship Maneuvering

2020 ◽  
pp. 1-10
Author(s):  
John C. Daidola
Keyword(s):  
Surface Roughness ◽  
Equations Of Motion ◽  
Control Surface ◽  
Ship Maneuvering ◽  
Single Screw ◽  
Operation And Maintenance ◽  
Hydrodynamic Derivatives ◽  
Turning Maneuver ◽  
And Control ◽  
Surface Vessel

The effects of hull roughness on ship maneuvering characteristics are investigated. The hydrodynamic derivatives in the equations of motion for surface vessel maneuvering are modified to incorporate roughness of the hull and rudder. Vessel lifetime roughness profiles are postulated based on construction, coatings, operation, and maintenance for a vessel life of 25 years. These are then applied to the turning maneuver for single screw cargo ships with block coefficients from .60 to .80. The implications for naval missions are discussed.

Coupling Effects on Synchronizability of Two-Layer Network's Projective Outer Synchronization

2017 ◽  
Vol 873 ◽  
pp. 353-357
Author(s):  
Bo Yu Feng ◽  
Zhi Hao Zhang
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Complex Network ◽  
Simulation Experiment ◽  
Small World ◽  
Experimental Results ◽  
Coupling Effects ◽  
Network Synchronization ◽  
Numerical Examples ◽  
Outer Synchronization

Based on nonlinear dynamics theory and knowledge of complex network, this paper expanded the range of two-layer network synchronization to projective outers synchronization. A mathematical model was constructed and feasibility of synchronization was demonstrated. Then we improved the model in order to study the function of different couplings [1]. Numerical examples are examined to compare the synchronizability of projective outer synchronization with different couplings. A rule called "outer small-world effect" was found due to simulation experiment. Finally, some instances were used to explain experimental results.

scholarly journals A Smart Microcontroller Architecture for the Internet of Things

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1821 ◽  
Author(s):  
Zhenyu Wu ◽  
Kai Qiu ◽  
Jianguo Zhang
Keyword(s):  
Internet Of Things ◽  
Real World ◽  
Simulation Experiment ◽  
Cloud Model ◽  
Experimental Results ◽  
The Internet ◽  
Complex Problems ◽  
Logic Control ◽  
The Internet Of Things ◽  
Embedded Intelligence

The interoperations of endpoint devices are generally achieved by gateways in Internet of Things (IoT) systems. However, the gateways mainly focus on networking communication, which is lack of data logic control capabilities. The microcontrollers with embedded intelligence could work as an intermediate device to help the interconnections of the endpoint devices. Moreover, they could help control the endpoint devices. In this paper, a microcontroller architecture with intelligent and scalable characteristics is proposed. The intelligence means that the microcontroller could control the target endpoint devices by its logical circuits, and the scalability means that the microcontroller architecture could be easily extended to deal with more complex problems. Two real world industrial implementations of the proposed architecture are introduced. The implementations show that the microcontroller is important to provide the intelligent services to users in IoT systems. Furthermore, a simulation experiment based on the cloud model is designed to evaluate the proposed method. The experimental results demonstrate the effectiveness of the proposed architecture.

Numerical Study on Fish Tail Shaped Rudder for Improved Ship Maneuvering

2015 ◽  
Author(s):  
Mannam Naga Praveen Babu ◽  
P. Krishnankutty
Keyword(s):  
Surface Area ◽  
Numerical Study ◽  
Control Force ◽  
Ship Maneuvering ◽  
Safety Regulations ◽  
Open Sea ◽  
Stream Condition ◽  
Ship Maneuverability ◽  
Force Moment ◽  
Turning Maneuver

Maneuvering is an important safety aspect in ship operations so as to avoid accident of ships in seaways and more critically in the restricted area of waterways. IMO stipulates many safety regulations on ship maneuverability in open sea conditions and the local authorities may have additional regulations in harbor, canal and other restricted waterways. The effectiveness of rudder has substantial influence on the maneuverability of a ship. It is often difficult to increase the size of the rudder, to get higher control force/moment, due to the geometrical restrictions of the aft aperture of the ship. A hydrodynamically efficient rudder section addresses this problem to some extent. Most of the fishes maneuver efficiently using their tail. The fish tail functions almost similar to that of a rudder for its movements and navigation. In general, ship with flap rudders and fish tail shaped rudders perform maneuverability better compare to a ship fitted with a conventional rudder having the same underwater surface area. In fishtail shaped rudders, the shape and movements promote good flow patterns in a wider range of rudder angles. In a fish tail, the trailing edge accelerates the flow and recovers lift over the aft section of the rudder. This results in the generation of a higher lift and thus helps in reducing the turning diameter of the vessel. The studies carried out with two rudder types — conventional rudder and fish tail shaped rudder — are presented in this paper. Numerical simulations are performed on these two rudders, both having the same surface area, for different rudder angles in free stream condition. The lift force generated by the fish tail shaped rudder is found to be higher than the conventional rudder. The flow across and the hydrodynamic forces acting on the sections are determined using a commercial CFD code. The effectiveness of the fishtail rudder is also brought out from the numerically simulated turning maneuver of a chosen ship fitted with the same rudder.

Application and Study of Virtual Private Network Base on L2TP-IPSec

2014 ◽  
Vol 1044-1045 ◽  
pp. 1071-1074
Author(s):  
Tao Liu
Keyword(s):  
Data Transmission ◽  
Communication Channel ◽  
Simulation Experiment ◽  
Virtual Private Network ◽  
Experimental Results ◽  
Public Network ◽  
Key Technologies ◽  
Private Network ◽  
Ipsec Protocol

Using IPSec protocol and VPN technology can be in the open, insecure public network, build a safe and stable communication channel, ensure the safety of data transmission. The communicating peers should implement mutual ID authentication prior to the building up of IPSec channel. Traditional way of IPSec ID authentication is based on “Pre-shared keys”, it has lower security. It makes a detaied analysis on the key technologies in VPN based on IPSec. A design of the IPSec ID authentication building VPN based on certificate is proposed. Finally, in the VMWare simulation experiment has been carried out on the design, experimental results show the design is safe, steady operation and easy to implement.

An Interaction Effect Consideration in Cumulative Damage in Metals Due to Creep

1981 ◽  
Vol 23 (6) ◽  
pp. 281-288 ◽  
Author(s):  
T. Bui-Quoc ◽  
A. Biron
Keyword(s):  
Interaction Effect ◽  
Creep Damage ◽  
Cumulative Damage ◽  
Experimental Results ◽  
Creep Process ◽  
Time Ratio ◽  
Empirical Relations ◽  
The Difference

An interaction effect between stresses is considered in cumulative creep damage tests with two levels to explain the deviation of the summation of time ratios from unity. With the cumulative damage concept previously suggested for the creep process, empirical relations have been established in order to take this effect into account. The parameters considered are the difference between stresses and the damaging time ratio. Essentially, this approach gives a theoretical value of the sum of time ratios greater than unity for decreasing stresses, whereas this value is smaller than unity for increasing stresses. The correlation between predictions and some published experimental results is discussed.

What is New about the Internet Delay Space?

2014 ◽  
Vol 6 (4) ◽  
pp. 36-55
Author(s):  
Zhang Guomin ◽  
Wang Zhanfeng ◽  
Wang Rui ◽  
Wang Na ◽  
Xing Changyou
Keyword(s):  
Metric Space ◽  
Large Scale ◽  
Simulation Experiment ◽  
Comprehensive Analysis ◽  
Experimental Results ◽  
The Internet ◽  
Internet Topology ◽  
Routing Policies ◽  
The Relationship ◽  
Delay Space

The Internet delay space is a comprehensive result of the Internet topology, routing policies, and network traffic. In this paper, a large scale of measurement was carried out to measure the Internet delay space and reveal new characters of the Internet delay space today. A comprehensive analysis was made from three aspects: the relationship between delay and geodistance, TIV severity and its dimensionality. It's found that as the evolvement of the Internet, the Internet delay space is transforming from a non-metric space into a metric space. To validate our observation, a simulation experiment, complementary measurements and analysis on the former typical delay datasets were performed. The experimental results were consistent with our observation.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

Observation of Phase Contrast Images in STEM and CTEM Modes by Using 100 kV Field Emission Electron Gun

1974 ◽  
Vol 32 ◽  
pp. 390-391
Author(s):  
Y. Harada ◽  
T. Goto ◽  
H. Koike ◽  
T. Someya
Keyword(s):  
Field Emission ◽  
Phase Contrast ◽  
Image Formation ◽  
Fresnel Diffraction ◽  
Experimental Results ◽  
Electron Gun ◽  
Scanning Microscopy ◽  
Emission Electron ◽  
Lattice Images

Since phase contrasts of STEM images, that is, Fresnel diffraction fringes or lattice images, manifest themselves in field emission scanning microscopy, the mechanism for image formation in the STEM mode has been investigated and compared with that in CTEM mode, resulting in the theory of reciprocity. It reveals that contrast in STEM images exhibits the same properties as contrast in CTEM images. However, it appears that the validity of the reciprocity theory, especially on the details of phase contrast, has not yet been fully proven by the experiments. In this work, we shall investigate the phase contrast images obtained in both the STEM and CTEM modes of a field emission microscope (100kV), and evaluate the validity of the reciprocity theory by comparing the experimental results.

A new dissociation mode for dislocations in silicon

1978 ◽  
Vol 36 (1) ◽  
pp. 346-347
Author(s):  
A. Ourmazd ◽  
G.R. Booker ◽  
C.J. Humphreys
Keyword(s):  
Detailed Examination ◽  
Experimental Results ◽  
Dislocation Network ◽  
Weak Beam ◽  
Phosphorus Doped

A (111) phosphorus-doped Si specimen, thinned to give a TEM foil of thickness ∼ 150nm, contained a dislocation network lying on the (111) plane. The dislocation lines were along the three <211> directions and their total Burgers vectors,ḇt, were of the type , each dislocation being of edge character. TEM examination under proper weak-beam conditions seemed initially to show the standard contrast behaviour for such dislocations, indicating some dislocation segments were undissociated (contrast A), while other segments were dissociated to give two Shockley partials separated by approximately 6nm (contrast B) . A more detailed examination, however, revealed that some segments exhibited a third and anomalous contrast behaviour (contrast C), interpreted here as being due to a new dissociation not previously reported. Experimental results obtained for a dislocation along [211] with for the six <220> type reflections using (g,5g) weak-beam conditions are summarised in the table below, together with the relevant values.

Sign in / Sign up

Export Citation Format

Share Document