Theoretical and Experimental Study of Ship-Roll Stabilization Tanks

1968 ◽  
Vol 12 (03) ◽  
pp. 165-180
Author(s):  
W. H. Chu ◽  
J. F. Dalzell ◽  
J. E. Modisette
Keyword(s):  
Experimental Studies ◽  
Theoretical Method ◽  
Linear Control ◽  
Mathematical Representation ◽  
Control Element ◽  
Design Technique ◽  
Ship Roll ◽  
Roll Stabilization ◽  
Gross Behavior ◽  
Experimental Findings

This paper summarizes development of a quasi-linear theory for rectangular-type anti-rolling tank and presents results of the ensuing experimental investigation. Theoretical and experimental studies are compared. It was found that the initial theoretical method, although it reflects gross behavior of fluid in the tank and moments exerted on the ship therefrom, should be regarded as the foundation for a better understanding rather than as a design technique. Experimental findings indicate that the antiroll tank is a non-linear control element over its practical range of operation. Development of a nonlinear mathematical representation incorporating empirical results, as necessary, is recommended.

scholarly journals The Influence of Alcohol Consumption on Fighting, Shoplifting and Vandalism in Young Adults

2021 ◽  
Vol 18 (7) ◽  
pp. 3509
Author(s):  
Ieuan Evans ◽  
Jon Heron ◽  
Joseph Murray ◽  
Matthew Hickman ◽  
Gemma Hammerton
Keyword(s):  
Young Adults ◽  
Longitudinal Study ◽  
Alcohol Consumption ◽  
Experimental Studies ◽  
Real Life ◽  
Self Report ◽  
Parents And Children ◽  
Experimental Findings ◽  
Avon Longitudinal Study ◽  
Causal Component

Experimental studies support the conventional belief that people behave more aggressively whilst under the influence of alcohol. To examine how these experimental findings manifest in real life situations, this study uses a method for estimating evidence for causality with observational data—‘situational decomposition’ to examine the association between alcohol consumption and crime in young adults from the Avon Longitudinal Study of Parents and Children. Self-report questionnaires were completed at age 24 years to assess typical alcohol consumption and frequency, participation in fighting, shoplifting and vandalism in the previous year, and whether these crimes were committed under the influence of alcohol. Situational decomposition compares the strength of two associations, (1) the total association between alcohol consumption and crime (sober or intoxicated) versus (2) the association between alcohol consumption and crime committed while sober. There was an association between typical alcohol consumption and total crime for fighting [OR (95% CI): 1.47 (1.29, 1.67)], shoplifting [OR (95% CI): 1.25 (1.12, 1.40)], and vandalism [OR (95% CI): 1.33 (1.12, 1.57)]. The associations for both fighting and shoplifting had a small causal component (with the association for sober crime slightly smaller than the association for total crime). However, the association for vandalism had a larger causal component.

scholarly journals Robust H∞ Control of STMDs Used in Structural Systems by Hardware in the Loop Simulation Method

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 55
Author(s):  
Huseyin Aggumus ◽  
Rahmi Guclu
Keyword(s):  
Natural Frequencies ◽  
Experimental Studies ◽  
Mr Damper ◽  
Simulation Method ◽  
Control Element ◽  
Structural Systems ◽  
Hardware In The Loop ◽  
Building Model ◽  
Mass Damper ◽  
Set Up

This paper investigated the performance of a semi-active tuned mass damper (STMD) on a multi-degree of freedom (MDOF) building model. A magnetorheological (MR) damper was used as a control element that provided semi-activity in the STMD. The Hardware in the Loop Simulation (HILS) method was applied to mitigate the difficulty and expense of experimental studies, as well as to obtain more realistic results from numerical simulations. In the implementation of this method for the STMD, the MR damper was set up experimentally, other parts of the system were modeled as computer simulations, and studies were carried out by operating these two parts simultaneously. System performance was investigated by excitation with two different acceleration inputs produced from the natural frequencies of the MDOF building. Additionally, a robust H ∞ controller was designed to determine the voltage transmitted to the MR damper. The results showed that the HILS method could be applied successfully to STMDs used in structural systems, and robust H ∞ controls improve system responses with semi-active control applications. Moreover, the control performance of the MR damper develops with an increase in the mass of the STMD.

Ship Roll Motion Damping Using Bilge Keels – A Detailed CFD Investigation

2015 ◽  
Author(s):  
Joshua Counsil ◽  
Kevin McTaggart ◽  
Dominic Groulx ◽  
Kiari Boulama
Keyword(s):  
Experimental Studies ◽  
The Body ◽  
Navier Stokes ◽  
Roll Motion ◽  
Empirical Methods ◽  
Viscous Effects ◽  
Vortex Interactions ◽  
Ship Roll ◽  
Semi Empirical ◽  
Bilge Keel

A study has been undertaken to test the value of unsteady Reynolds-averaged Navier-Stokes (URANS) and traditional semi-empirical methods in the face of complex ship roll phenomena, and provide insight into the selection of bilge keel span for varying roll amplitudes. The computational fluid dynamics (CFD) code STAR-CCM+ is employed and two-dimensional submerged bodies undergoing forced roll motion are analyzed. The spatial resolution and timestepping scheme are validated by comparison with published numerical and experimental studies. The model is then applied to a fully-submerged circular cylinder with bilge keels of varying span and undergoing roll motion at varying angular amplitudes. Extracted hydrodynamic coefficients indicate that in general, increasing displacement amplitude and bilge keel span yields increased added mass and increased damping. The relationship is complex and highly dependent upon vortex interactions with each other and the body. The semi-empirical methods used for comparison yield good predictions for simple vortex interactions but fail where viscous effects are strong. Hence, URANS methods are shown to be necessary for friction-dominated flows while semi-empirical methods remain useful for initial design considerations.

Effect of altered gas diffusivity on alveolar gas exchange-a theoretical study

1980 ◽  
Vol 48 (1) ◽  
pp. 147-153 ◽  
Author(s):  
W. Nixon ◽  
A. Pack
Keyword(s):  
Blood Flow ◽  
Gas Exchange ◽  
Theoretical Study ◽  
Experimental Studies ◽  
Flow Distribution ◽  
Molecular Diffusivity ◽  
Gas Diffusivity ◽  
Experimental Findings ◽  
Lung Airways ◽  
Alveolar Gas Exchange

Experimental studies have established that alveolar gas exchange is inversely relation to the molecular diffusivity of gas in the lung airways. The mechanism underlying this relationship is, however, unclear. To investigate this phenomenon, the conditions relevant to the experimental studies are simulated using a computational model of pulmonary gas transport. Results from these simulations suggest that the inverse relationship found experimentally can largely be explained on the basis of the intra-acinar stratification of blood flow and gas concentrations. Gas having a relatively low molecular diffusivity is not transported as far into the acinus as gas having a higher diffusivity. When these relative intra-acinar gas distributions interact with the blood flow distribution, which has been shown experimentally to be weighted towards the proximal alveoli, more gas exchange occurs in the low molecular diffusivity mixture. Consideration of the various other mechanisms that have been proposed to explain the experimental findings.he inverse dependence suggests that they are of little significance. In particular, our studies remove the need to invoke Taylor diffusion to explain the experimental findings.

scholarly journals Review of improvements on heat transfer using nanofluids via corrugated facing step

2018 ◽  
Vol 7 (4.13) ◽  
pp. 160 ◽  
Author(s):  
Ali Hilo ◽  
Abd Rahim Abu Talib ◽  
Sadeq R. Nfawa ◽  
Mohamed Thariq Hameed Sultan ◽  
Mohd Faisal Abdul Hamid
Keyword(s):  
Heat Transfer ◽  
Thermal Conduction ◽  
Experimental Studies ◽  
Conductivity Measurement ◽  
Measurement Methods ◽  
Laminar Flows ◽  
Transfer Enhancement ◽  
Innovative Design ◽  
Experimental Findings ◽  
The Ideal

Nanofluids are considered to offer significant advantages as thermodynamic fluids because of their admirable properties on thermal conduction, thermal convection, boiling heat transfer and stability. This paper presents numerous researches focusing on the improvement of heat transfer via facing step and corrugated channels using nanofluids and without it. Exploration on the convective heat transfer was done through numerical modeling. It was reported that experimental studies were carried out in corrugated and facing step channels through the application of nanofluids and conventional fluids for heat transfer enhancement. The turbulent and laminar flows along corrugated and facing step channels have been presented. The numerical and experimental findings in maximizing the heat transfer rate are in accord. Comparisons between thermal conductivity measurement methods were done. Innovative design of corrugated facing step channel is being proposed. The heat transfer enhancements reach 60% by using facing step channel under laminar flow with nanofluid. The dimensions of new channel such as height and width of the baffle, the height of the step, shape and height of corrugated are needed to compare that might to provide the ideal rate of heat transfer.  

Review of Stress Effects on Dopant Solubility in Silicon and Silicon-Germanium Layers

2009 ◽  
Vol 156-158 ◽  
pp. 173-180 ◽  
Author(s):  
Nicholas S. Bennett ◽  
Chihak Ahn ◽  
Nicholas E.B. Cowern ◽  
Peter Pichler
Keyword(s):  
Silicon Germanium ◽  
Experimental Studies ◽  
Close Correlation ◽  
Theoretical Treatment ◽  
Strained Si ◽  
Early Theory ◽  
Stress Effects ◽  
Experimental Findings ◽  
First Time ◽  
Strained Sige

We present a review of both theoretical and experimental studies of stress effects on the solubility of dopants in silicon and silicon-germanium materials. Critical errors and limitations in early theory are discussed, and a recent treatment incorporating charge carrier induced lattice strain and correct statistics is presented. Considering all contributing effects, the strain compensation energy is the primary contribution to solubility enhancement in both silicon and silicon-germanium for dopants of technological interest. An exception is the case of low-solubility dopants, where a Fermi level contribution is also found. Explicit calculations for a range of dopant impurities in Si are presented that agree closely with experimental findings for As, Sb and B in strained Si. The theoretical treatment is also applied to account for stress effects in strained SiGe structures, which also show close correlation with recently derived experimental results for B-doped strained SiGe which are presented here for the first time.

A Mathematical Representation of the ion Nitriding Process

1987 ◽  
Vol 98 ◽  
Author(s):  
J -L. Marchand ◽  
D. Ablitzer ◽  
J. Szekely ◽  
H. Michel ◽  
M. Gantois
Keyword(s):  
Electron Number Density ◽  
Mathematical Formulation ◽  
Temperature Fields ◽  
Nitriding Process ◽  
Mathematical Representation ◽  
Number Density ◽  
Ion Nitriding ◽  
Electron Number ◽  
Theoretical Predictions ◽  
Experimental Findings

ABSTRACTA mathematical formulation and computed results are presented to describe the velocity fields, temperature fields and concentration of the activated species in an ion nitriding process, operated at 1–5 torr pres-sure. The theoretical predictions, which are based on the two-dimensional trasnport equations and on a model for computing the electron number density, gave results in broad agreement with experimental findings reported by others for similar systems.

Neural network based fin control for ship roll stabilization with guaranteed robustness

2017 ◽  
Vol 230 ◽  
pp. 210-218 ◽  
Author(s):  
Weilin Luo ◽  
Bingbing Hu ◽  
Tieshan Li
Keyword(s):  
Neural Network ◽  
Ship Roll ◽  
Roll Stabilization
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