The Transient Capsize Diagram—A New Method of Quantifying Stability in Waves

1991 ◽  
Vol 35 (01) ◽  
pp. 58-62 ◽  
Author(s):  
R. C. T. Rainey ◽  
J. M. T. Thompson
Keyword(s):  
Computer Simulation ◽  
Dynamic Systems ◽  
Wave Steepness ◽  
Dynamic Systems Theory ◽  
Regular Waves ◽  
Desktop Computers ◽  
Strip Theory ◽  
Calm Water ◽  
Recent Developments ◽  
The Stability

It is argued that a plot of wave steepness against wave period, showing the combinations which cause capsize, is a well-defined measure of the stability of a ship or ocean vehicle in waves, provided the conditions are transient, that is, the vessel is initially in relatively calm water, and is suddenly hit by a train of regular waves. This conclusion is a consequence of recent developments in dynamic systems theory. Such Transient Capsize Diagrams can obviously be obtained by model testing; it is also argued that they could be obtained by computer simulation on contemporary desktop computers, taking advantage of recent developments in nonlinear strip theory.

A Nonlinear Mathematical Model for Ship Turning Circle Simulation in Waves

2005 ◽  
Vol 49 (02) ◽  
pp. 69-79 ◽  
Author(s):  
Ming-Chung Fang ◽  
Jhih-Hong Luo ◽  
Ming-Ling Lee
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Regular Waves ◽  
Nonlinear Mathematical Model ◽  
Ship Maneuvering ◽  
Sea Trial ◽  
Six Degrees Of Freedom ◽  
Strip Theory ◽  
Calm Water ◽  
Maneuvering Motion

In the paper, a simplified six degrees of freedom mathematical model encompassing calm water maneuvering and traditional seakeeping theories is developed to simulate the ship turning circle test in regular waves. A coordinate system called the horizontal body axes system is used to present equations of maneuvering motion in waves. All corresponding hydrodynamic forces and coefficients for seakeeping are time varying and calculated by strip theory. For simplification, the added mass and damping coefficients are calculated using the constant draft but vary with encounter frequency. The nonlinear mathematical model developed here is successful in simulating the turning circle of a containership in sea trial conditions and can be extended to make the further simulation for the ship maneuvering under control in waves. Manuscript received at SNAME headquarters February 19, 2003; revised manuscript received January 27, 2004.

Some Extensions of the Classical Approach to Strip Theory of Ship Motions, Including the Calculation of Mean Added Forces and Moments

1978 ◽  
Vol 22 (01) ◽  
pp. 1-19 ◽  
Author(s):  
Theodore A. Loukakis ◽  
Paul D. Scfavounos
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Dynamical Theory ◽  
Forced Oscillations ◽  
Ship Motions ◽  
Regular Waves ◽  
Strip Theory ◽  
Calm Water ◽  
Exciting Forces ◽  
New Formulation

The application of the dynamical theory to the problem of a ship moving with constant forward speed on a free surface has been extended to include the exciting forces in oblique regular waves. As a result, it has become possible to derive a new formulation for the equations of motion, for a ship moving with five degrees of freedom. The application of the same theory has yielded formulas for the calculation of the mean added resistance and drift force in oblique regular waves and the calculation of all mean forces and moments for the forced oscillations of a ship in calm water.

An Improved Body-Exact Method to Predict the Maneuvering of Ships in a Seaway

2019 ◽  
Author(s):  
Rahul Subramanian ◽  
Robert F. Beck
Keyword(s):  
Incident Wave ◽  
Body Position ◽  
Surface Boundary ◽  
Wave Surface ◽  
Computationally Efficient ◽  
Regular Waves ◽  
Viscous Effects ◽  
Surface Boundary Conditions ◽  
Strip Theory ◽  
Calm Water

Abstract Over the last decade, the importance of considering the effects of waves on the maneuvering characteristics of ships has been widely recognized. This paper presents the application of a recently developed nonlinear body-exact scheme (Subramanian, Rakesh, and Beck (2018)) to directly simulate the maneuvering characteristics of a container ship in calm water and in regular waves. In the present body-exact scheme, the perturbation free surface boundary conditions are transferred to a representative incident wave surface at each station at each time. The hydrodynamic forces are computed on the exact instantaneous wetted surface formed by the intersection of the incident wave surface with the exact body position at each time. It is proposed that this model will not only improve first order sea loads but also the higher order drift force predictions which are critical for determining the trajectory of a maneuvering vessel in a seaway. The strip theory formulation has been found to be numerically stable, robust and computationally efficient, which are all critical aspects when performing long time maneuvering simulations. The hull maneuvering, rudder and propeller forces are adopted from standard systems-based approaches that are used to predict calm water maneuvers. Care is taken to ensure that ideal fluid effects are separated from viscous effects and not double counted. Results are presented for turning circle maneuvers in calm water and regular waves incident at various headings and wavelengths. The numerical results are compared with available experiments.

scholarly journals Test Studies of the Resistance and Seakeeping Performance of a Trimaran Planing Hull

2015 ◽  
Vol 22 (1) ◽  
pp. 22-27 ◽  
Author(s):  
Weijia Ma ◽  
D. Hanbing Sun ◽  
D. Huawei Sun ◽  
D. Jin Zou ◽  
Jiayuan Zhuang
Keyword(s):  
Small Angle ◽  
Test Results ◽  
Regular Waves ◽  
Longitudinal Stability ◽  
Towing Tank ◽  
Centre Of Gravity ◽  
Air Jets ◽  
Seakeeping Performance ◽  
Calm Water ◽  
The Stability

Abstract Towing tank tests in calm water were performed on a trimaran planing hull to verify its navigational properties with different displacements and centres of gravity, as well as to assess the effects of air jets and bilge keels on the hull’s planing capabilities, and to increase the longitudinal stability of the hull. Hydrostatic roll tests, zero speed tests, and sea trials in the presence of regular waves were conducted to investigate the hull’s seakeeping ability. The test results indicate that the influence of the location of the centre of gravity on the hull resistance is similar to that of a normal trimaran planing hull; namely, moving the centre of gravity backward will reduce the resistance but lower the stability. Bilge keels improve the longitudinal stability but slightly affect the resistance, and the presence of air jets in the hull’s channels decreases the trim angle and increases heaving but has little effect on the resistance. Frequent small-angle rolling occurs in waves. The heaving and pitching motions peak at the encounter frequency of , and the peaks increase with velocity and move towards greater encounter frequencies. When the encounter frequency exceeds, the hull motion decreases, which leads to changes in the navigation speed and frequency.

Improving Feeding Outcomes in the NICU: Moving From Volume-Driven to Infant-Driven Feeding

2010 ◽  
Vol 19 (3) ◽  
pp. 68-74 ◽  
Author(s):  
Catherine S. Shaker
Keyword(s):  
Intensive Care Unit ◽  
Dynamic Systems ◽  
Neonatal Intensive Care ◽  
Well Being ◽  
Dynamic Systems Theory ◽  
Feeding Problems ◽  
Care Giving ◽  
Extremely Preterm ◽  
Extremely Preterm Infants

Current research on feeding outcomes after discharge from the neonatal intensive care unit (NICU) suggests a need to critically look at the early underpinnings of persistent feeding problems in extremely preterm infants. Concepts of dynamic systems theory and sensitive care-giving are used to describe the specialized needs of this fragile population related to the emergence of safe and successful feeding and swallowing. Focusing on the infant as a co-regulatory partner and embracing a framework of an infant-driven, versus volume-driven, feeding approach are highlighted as best supporting the preterm infant's developmental strivings and long-term well-being.

A Benchmarked Experiential System for Training (BEST) and dynamic systems theory

2006 ◽  
Author(s):  
Wayne Shebilske ◽  
Kevin Gildea ◽  
Jared Freeman ◽  
Georgiy Levchuk
Keyword(s):  
Systems Theory ◽  
Dynamic Systems ◽  
Dynamic Systems Theory ◽  
Experiential System

Investigation of the Stability of Continuous Dynamic Systems

1997 ◽  
Vol 29 (1) ◽  
pp. 44-54
Author(s):  
O. P. Gavril'chenko
Keyword(s):  
Dynamic Systems ◽  
Continuous Dynamic ◽  
The Stability

Novel Nanolipoidal Systems for the Management of Skin Cancer

2020 ◽  
Vol 14 (2) ◽  
pp. 108-125
Author(s):  
Apoorva Singh ◽  
Nimisha
Keyword(s):  
Skin Cancer ◽  
Survival Rates ◽  
Cancer Therapeutics ◽  
The Body ◽  
Surgical Removal ◽  
The Novel ◽  
Skin Cancers ◽  
Recent Developments ◽  
Abnormal Cells ◽  
The Stability

: Skin cancer, among the various kinds of cancers, is a type that emerges from skin due to the growth of abnormal cells. These cells are capable of spreading and invading the other parts of the body. The occurrence of non-melanoma and melanoma, which are the major types of skin cancers, has increased over the past decades. Exposure to ultraviolet radiations (UV) is the main associative cause of skin cancer. UV exposure can inactivate tumor suppressor genes while activating various oncogenes. The conventional techniques like surgical removal, chemotherapy and radiation therapy lack the potential for targeting cancer cells and harm the normal cells. However, the novel therapeutics show promising improvements in the effectiveness of treatment, survival rates and better quality of life for patients. Different methodologies are involved in the skin cancer therapeutics for delivering the active ingredients to the target sites. Nano carriers are very efficient as they have the ability to improve the stability of drugs and further enhance their penetration into the tumor cells. The recent developments and research in nanotechnology have entitled several targeting and therapeutic agents to be incorporated into nanoparticles for an enhancive treatment of skin cancer. To protect the research works in the field of nanolipoidal systems various patents have been introduced. Some of the patents acknowledge responsive liposomes for specific targeting, nanocarriers for the delivery or co-delivery of chemotherapeutics, nucleic acids as well as photosensitizers. Further recent patents on the novel delivery systems have also been included here.

Control Theory, Dynamics, and Continuous Interaction

2018 ◽  
Author(s):  
Roderick Murray-Smith
Keyword(s):  
Control Theory ◽  
Human Computer Interaction ◽  
Systems Theory ◽  
Dynamic Systems ◽  
Trajectory Generation ◽  
Interaction Techniques ◽  
Dynamic Systems Theory ◽  
Classical Work ◽  
Continuous Interaction

This chapter reviews the role of theory and dynamic systems theory for understanding common interaction techniques including: targetting, trajectory generation, panning, scrolling and zooming. It explains how can be seen to be at the foundations of Human–Computer Interaction and might be essential for making progress in novel forms of interface. It reinterprets Fitts’ classical work with theoretic tools. It also highlights the limitations of theory for design of human–computer loops.

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