Effects of Hull Geometry and Tightness of Turns on Ship Maneuverability: An OSIS-IHI Simulation

2021 ◽  
Author(s):  
Michael Lau
Keyword(s):  
Performance Assessment ◽  
Ship Maneuvering ◽  
Hull Form ◽  
Structure Interaction ◽  
The Poor ◽  
Ship Maneuverability ◽  
Modeling Software ◽  
Body Design ◽  
Ship Performance ◽  
Shed Light

Abstract OSIS-IHI (Ocean Structure Interaction Simulator – Ice-Hull Interaction) is a ship maneuvering in ice modeling software developed at OCRE for a marine simulator and ship performance assessment applications. A series of OSIS-IHI simulations is conducted to explain the maneuvering behavior observed of the USCGC Polar Icebreaker indicative design previously tested at the centre. The simulation is conducted with the original and a modified version of the USCGC Icebreaker Healy. The Icebreaker USCGC Healy was equipped with doublescrew conventional propellers. The hull geometry of the OSIS-Healy model is appropriately modified to mimic the hull form of two indicated design versions in question and its propulsion units replaced by twin pods prior to studying its maneuverability in order to shed light on the apparently poor maneuvering performance of the podded version of the indicative design. The modified version extends the mid-body leaving just 7.5 % of hull that constitutes the stern section. It is hypothesized that the extended mid-section cost large resisting moment against turning due to the increase of ice breaking at the aft shoulder and mid-body. This hypothesis is validated numerically to explain the poor maneuverability exhibited by the extended mid-body design, based on consideration of ice-hull interaction geometry and basic mechanics of ice breaking as well as existing anecdotal test evidences. This paper presents result of the simulation to explore effects of hull geometry and tightness of turns on ship maneuverability. Important insights gained are summarized and recommendation for further work given.

Abdullah Quilliam

2017 ◽  
Author(s):  
Mohammad Siddique Seddon
Keyword(s):  
Working Class ◽  
Political Activism ◽  
Working Classes ◽  
Political Influences ◽  
Union Movement ◽  
The Poor ◽  
Conversion To Islam ◽  
Class Struggles ◽  
Legal Advisor ◽  
Shed Light

This chapter explores the religious and political influences that shaped Abdullah Quilliam’s Muslim missionary activities, philanthropic work and scholarly writings in an attempt to shed light on his particular political convictions as manifest through his unique religiopolitical endeavors. It focuses especially on Quilliam’s Methodist upbringing in Liverpool and his support of the working classes. It argues that Quilliam’s religious and political activism, although primarily inspired by his conversion to Islam, was also shaped and influenced by the then newly emerging proletariat, revolutionary socialism. Quilliam’s continued commitment to the burgeoning working-class trades union movement, both as a leading member representative and legal advisor, coupled with his reputation as the "poor man’s lawyer" because of his frequent fee-free representations for the impoverished, demonstrates his empathetic proximity to working-class struggles.

scholarly journals Invisible inequality leads to punishing the poor and rewarding the rich

2019 ◽  
pp. 1-21 ◽  
Author(s):  
OLIVER P. HAUSER ◽  
GORDON T. KRAFT-TODD ◽  
DAVID G. RAND ◽  
MARTIN A. NOWAK ◽  
MICHAEL I. NORTON
Keyword(s):  
New York ◽  
Public Education ◽  
School Districts ◽  
New York School ◽  
Public Goods Game ◽  
Policy Makers ◽  
The Poor ◽  
The Us ◽  
The Rich ◽  
Shed Light

AbstractFour experiments examine how lack of awareness of inequality affect behaviour towards the rich and poor. In Experiment 1, participants who became aware that wealthy individuals donated a smaller percentage of their income switched from rewarding the wealthy to rewarding the poor. In Experiments 2 and 3, participants who played a public goods game – and were assigned incomes reflective of the US income distribution either at random or on merit – punished the poor (for small absolute contributions) and rewarded the rich (for large absolute contributions) when incomes were unknown; when incomes were revealed, participants punished the rich (for their low percentage of income contributed) and rewarded the poor (for their high percentage of income contributed). In Experiment 4, participants provided with public education contributions for five New York school districts levied additional taxes on mostly poorer school districts when incomes were unknown, but targeted wealthier districts when incomes were revealed. These results shed light on how income transparency shapes preferences for equity and redistribution. We discuss implications for policy-makers.

scholarly journals A Three-Dimensional Reconstructive Study of Pelvic Cavity in the New Zealand Rabbit (Oryctolagus cuniculus)

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sema Özkadif ◽  
Emrullah Eken ◽  
İbrahim Kalaycı
Keyword(s):  
New Zealand ◽  
3D Modeling ◽  
Three Dimensional ◽  
Pelvic Cavity ◽  
Zealand Rabbit ◽  
Pelvic Inclination ◽  
Modeling Techniques ◽  
Modeling Software ◽  
Shed Light ◽  
New Zealand Rabbits

The present study has been performed to reveal biometrical aspects and diameter-related differences in terms of sexes regarding pelvic cavity via three-dimensional (3D) reconstruction by using multidetector computed tomography (MDCT) images of pelvic cavity of the New Zealand rabbit. A total of 16 adult New Zealand rabbits, including 8 males and 8 females, were used in this study. Under anesthesia, the images obtained from MDCT were stacked and overlaid to reconstruct the 3D model of the pelvic cavity using 3D modeling software (Mimics 13.1). Measurements, such as the conjugate, transverse, and vertical diameters of the pelvic cavity, and the pelvic inclination were calculated and analyzed statistically. Biometrical differences of the pelvic diameters in New Zealand rabbits of both sexes were shown clearly. It was concluded that the pelvic diameters revealed by 3D modeling techniques can shed light on medical students who take both anatomy training and gynecological applications. The authors hope that the synchronization of medical approaches may give rise to novel diagnostic and therapeutic developments related to pelvic cavity.

Time Domain Analysis on Ship Maneuvering in Adverse Sea State

2016 ◽  
Author(s):  
Bingjie Guo ◽  
Ruth Eivind ◽  
Håvard Austefjord ◽  
Elzbieta M. Bitner-Gregersen ◽  
Olav Rognebakke
Keyword(s):  
Time Domain ◽  
Ghg Emissions ◽  
Weather Conditions ◽  
Time Domain Analysis ◽  
Equilibrium Analysis ◽  
Future Research ◽  
Ship Maneuvering ◽  
Ship Maneuverability ◽  
Adverse Weather ◽  
The Time Domain

Energy Efficiency Design Index (EEDI) introduced by the IMO Resolution MEPC.203 (62) has been the first initiative to regulate the greenhouse gas (GHG) emissions from ships. However, it has raised serious concerns that some ship designers might choose to lower the installed power to achieve EEDI requirements not accounting satisfactorily for ship safety. This has encouraged investigations addressing the ability of ship to maintain maneuverability in adverse sea states. The Interim Guidelines proposed in 2013, in IMO Res. MEPC.232 (65), recommend minimum propulsion power to maintain ship maneuvering ability in adverse weather conditions for bulk carriers and tankers. These guidelines are mainly based on statistical analysis and equilibrium analysis in a steady state. Today, most of the available tools and methods handle ship responses in waves by separating it into seakeeping and maneuvering. The present study investigates ship maneuverability by use of a recently developed time domain code which combines the sea-keeping and maneuvering equation to predict ship responses in waves. In this way, better insight into ship responses in adverse conditions is obtained. The numerical results presented in the study are validated by model tests. The limitations of the time-domain code are discussed and future research needs are pointed out.

scholarly journals Mandeville on charity schools: happiness, social order and the psychology of poverty

2016 ◽  
Vol 9 (1) ◽  
pp. 82
Author(s):  
Francesca Pongiglione ◽  
Mikko Tolonen
Keyword(s):  
Social Order ◽  
Working Poor ◽  
Poor People ◽  
Moral Thought ◽  
The Poor ◽  
Bernard Mandeville ◽  
Shed Light ◽  
School Movement

Bernard Mandeville was not alone in criticising the charity school movement that had developed in Britain starting in late 1600; yet his Essay on charity and charity-schools is extremely provocative, especially as it regards the conditions of the poor. He criticises the selfish intentions and motives of charity schools, and inquires whether such schools are socially advantageous. This essay aims, first, to shed light on Mandeville's views on charity and charity schools, and demonstrate that such views are consistent with his moral thought. Second, this essay addresses problems inherent in Mandeville's views on how the working poor should be "managed"; what he proposes does not appear to guarantee (but rather puts at further risk) societal peace or the happiness of poor people.

scholarly journals Numerical Estimation of Hull Hydrodynamic Derivatives in Ship Maneuvering Prediction

2021 ◽  
Vol 28 (2) ◽  
pp. 46-53
Author(s):  
Radosław Kołodziej ◽  
Paweł Hoffmann
Keyword(s):  
Model Tests ◽  
Circular Motion ◽  
Computational Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Ship Maneuvering ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Ship Maneuverability ◽  
Free Running

Abstract Prediction of the maneuvering characteristics of a ship at the design stage can be done by means of model tests, computational simulations or a combination of both. The model tests can be realized as a direct simulation of the standard maneuvers with the free running model, which gives the most accurate results but is also the least affordable, as it requires a very large tank or natural lake, as well as the complex equipment of the model. Alternatively, a captive model test can be used to identify the hydrodynamic characteristics of the hull, which can be used to simulate the standard maneuvers with the use of dedicated software. Two types of captive model tests are distinguished: circular motion tests (CMT) and planar motion mechanism tests (PMM). The paper presents an attempt to develop a computational method for ship maneuverability prediction in which the hydrodynamic characteristics of the hull are identified by means of computational fluid dynamics (CFD). The CFD analyses presented here directly simulate the circular motion test. The resulting hull characteristics are verified against the available literature data, and the results of the simulations are verified against the results of free running model tests. Reasonable agreement shows the large potential of the proposed method.

Learning Transfer Among Solid Modelers: An Analysis of Icon Recognition

2005 ◽  
Author(s):  
Raymond J. Rutkowski ◽  
Gu¨l E. Okudan
Keyword(s):  
Solid Modeling ◽  
Conceptual Learning ◽  
Review Of The Literature ◽  
Educational Materials ◽  
Decision Making Problem ◽  
Modeling Software ◽  
The Right ◽  
The Impact ◽  
Shed Light ◽  
Icon Recognition

Selecting the “right” solid modeling software is a complex, multi-criteria decision-making problem. Some of these criteria relate to ease of learning, educational materials built into the software, learning curve issues, performance of the software for different solid modeling functions, operations and utilities, and cost. Beyond selecting the right software, the decision-maker should also be concerned about (1) conceptual learning of the solid modeling topics while “the right software” is being used, and (2) transfer of conceptual learning between solid modelers. This is because a sound conceptual learning using one software might increase the probability of learning another in less time. Accordingly, this paper investigates the impact of icon recognition as an aid to transfer conceptual learning between solid modelers. The investigation includes a review of the literature on icon design and usage as it relates to solid modeling, in addition to an experiment in which the icon recognition correctness for over 20 operation icons were compared across two modelers. The results shed light into the impact of icon designs on the transfer of learning between solid modelers using the correct recognition counts as the transfer measure.

Hemodynamics and Growth of Intracranial Aneurysms

2010 ◽  
Author(s):  
Daniel Sforza ◽  
Christopher Putman ◽  
Satoshi Tateshima ◽  
Fernando Vinuela ◽  
Juan Cebral
Keyword(s):  
Cerebral Aneurysms ◽  
Vascular Wall ◽  
Relative Importance ◽  
Preventive Interventions ◽  
Challenging Problem ◽  
Non Invasive ◽  
The Poor ◽  
Main Factors ◽  
Underlying Mechanisms ◽  
Shed Light

Understanding the underlying mechanisms responsible for the progression and rupture of cerebral aneurysms is important for improving their evaluation and treatment. Previous studies have identified the main factors involved in these processes: hemodynamics, vascular wall biomechanics and mechano-biology, and contacts with peri-aneurysmal structures [1]. However, little is known about their relative importance and interactions. The goal of our study is to shed light into the mechanisms of aneurysm progression by studying cerebral aneurysms that are followed longitudinally in time. This is a challenging problem because due to the poor prognosis of aneurysm ruptures preventive interventions are considered for most aneurysms. This paper presents preliminary results and observations made on a series of aneurysms followed with non-invasive imaging.

Description of hull form and evaluation of ship performance (3rd Report)

1999 ◽  
Vol 1999 (185) ◽  
pp. 133-141
Author(s):  
Kayoko Arai ◽  
Yasunori Iwasaki ◽  
Ryusuke Hosoda
Keyword(s):  
Hull Form ◽  
Ship Performance

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.

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