Added Moment of Inertia of Rolling Ship Sections

1982 ◽  
Vol 26 (02) ◽  
pp. 89-93
Author(s):  
P. P. Hsu ◽  
L. Landweber
Keyword(s):  
Free Surface ◽  
Infinite Series ◽  
Laurent Series ◽  
Low Frequency ◽  
Moment Of Inertia ◽  
Section Area ◽  
Family Of Curves ◽  
Section Rolling ◽  
The Given ◽  
Two Parameter

An expression for the added moment of inertia of a ship section rolling at low frequency at a free surface, in terms of the coefficients of the Laurent series of the function which maps the given section into a circle, has been derived. The method is applied to the two-parameter family of Lewis forms and the results are presented as a family of curves which gives the coefficient of the added moment of inertia as a function of the thickness ratio and the section-area coefficient of a form. A second application is to a square section, for which the Laurent expansion is an infinite series.

Added Moment of Inertia of a Rotating Ship Section

1979 ◽  
Vol 23 (03) ◽  
pp. 171-174
Author(s):  
L. Landweber
Keyword(s):  
Laurent Series ◽  
Parameter Family ◽  
Thickness Ratio ◽  
Moment Of Inertia ◽  
Section Area ◽  
Family Of Curves ◽  
The Given ◽  
Two Parameter

An expression for the added moment of inertia of a rotating ship section, in terms of the coefficients of the Laurent series of the function which maps the given section into a circle, has been derived. The method is applied to the two-parameter family of Lewis forms and the results are presented as a family of curves which gives the coefficient of the added moment of inertia as a function of the thickness ratio and the section-area coefficient of a form. A second application, to a square section, indicates that a sufficiently accurate value of the added moment of inertia can be obtained with little arithmetical work even in a case where the Laurent series is an infinite one.

Added Mass of a Three-Parameter Family of Two-Dimensional Forces Oscillating in a Free Surface

1959 ◽  
Vol 3 (01) ◽  
pp. 36-48
Author(s):  
L. Landweber ◽  
Matilde Macagno
Keyword(s):  
Free Surface ◽  
Added Mass ◽  
Small Error ◽  
Parameter Family ◽  
Radius Of Gyration ◽  
Two Dimensional ◽  
Transverse Axis ◽  
Section Area ◽  
Added Masses ◽  
The Given

The added-mass characteristics of shiplike forms, oscillating vertically or horizontally in a free surface, are derived for a three-parameter family of forms. The parameters varied are the draft-beam ratio, the section-area coefficient, and the ratio to the draft of the radius of gyration about the transverse axis in the free surface. The added-mass coefficients are presented as a series of curves for about 70 members of this family. It is suggested that the added masses of arbitrary shiplike sections may be obtained, with only small error, from these curves by interpolation at the parametric values of the given section.

scholarly journals On generation and propagation of tsunamis in a shallow running ocean

1978 ◽  
Vol 1 (3) ◽  
pp. 373-390
Author(s):  
Lokenath Debnath ◽  
Uma Basu
Keyword(s):  
Free Surface ◽  
Three Dimensional ◽  
Relative Magnitude ◽  
Ocean Floor ◽  
Surface Elevation ◽  
Free Surface Elevation ◽  
Surface Disturbance ◽  
Fourier And Laplace Transforms ◽  
The Given ◽  
Integral Solutions

A theory is presented of the generation and propagation of the two and the three dimensional tsunamis in a shallow running ocean due to the action of an arbitrary ocean floor or ocean surface disturbance. Integral solutions for both two and three dimensional problems are obtained by using the generalized Fourier and Laplace transforms. An asymptotic analysis is carried out for the investigation of the principal features of the free surface elevation. It is found that the propagation of the tsunamis depends on the relative magnitude of the given speed of the running ocean and the wave speed of the shallow ocean. When the speed of the running ocean is less than the speed of the shallow ocean wave, both the two and the three dimensional free surface elevation represent the generation and propagation of surface waves which decay asymptotically ast−12for the two dimensional case and ast−1for the three dimensional tsunamis. Several important features of the solution are discussed in some detail. As an application of the general theory, some physically realistic ocean floor disturbances are included in this paper.

scholarly journals Calculation of the maximum velocity of gravity flow in the pond-clarifier with higher aquatic plants

2020 ◽  
Vol 168 ◽  
pp. 00061
Author(s):  
Yevhen Semenenko ◽  
Tetіana Demchenko ◽  
Artyom Pavlichenko
Keyword(s):  
Free Surface ◽  
Aquatic Plants ◽  
Fluid Velocity ◽  
Maximum Velocity ◽  
Resistance Coefficient ◽  
Gravity Flow ◽  
Recycled Water ◽  
Higher Aquatic Plants ◽  
Two Parameters ◽  
The Given

The analysis of the possible maximum fluid flow rates when using higher aquatic plants for clarification of recycled water in the pondclarifier of the tailing pond has carried out. The study has been performed on the basis of a mathematical model of a plane slow stationary gravity flow of a viscous fluid in two parallel layers. The results of the study made it possible to determine the fluid velocity through a layer of higher aquatic plants floating on a free surface. The maximum possible velocity depending on the layer porosity has been determined. This value is necessary to determine the rational parameters of the process of clarifying technical recycled water from particles of the given hydraulic size, taking into account the pond-clarifier geometric dimensions. It is shown that the velocity in the layer with higher aquatic plants has been determined by the ratio of two parameters of this layer - porosity and dimensionless resistance coefficient. It has been shown that the maximum velocity value coefficient in the layer with plants floating on free surface depends only on porosity of this layer and does not depend on its resistance coefficient.

Hysteresis and nonlinear detuning in a spatial-resonance phenomenon

1973 ◽  
Vol 61 (2) ◽  
pp. 401-413
Author(s):  
Ian Huntley ◽  
Ronald Smith
Keyword(s):  
Free Surface ◽  
Experimental Work ◽  
Alternative Model ◽  
Pressure Field ◽  
Low Frequency ◽  
Theoretical Description ◽  
Resonance Phenomenon ◽  
Theoretical Problem ◽  
Frequency Wave ◽  
Spatial Resonance

The experimental work of Franklin, Price & Williams (1973) shows that for moderately large driving amplitudes there are features of spatial resonance that are not predicted by the model representation of Mahony & Smith (1972). We here derive an alternative model, which remains valid for moderately large driving amplitudes, and we are able to obtain a theoretical description of both hysteresis and nonlinear detuning of the low frequency wave response. An experiment in which surface waves were generated by a sinusoidal pressure field at the free surface (and which corresponds almost exactly to the theoretical problem) was conducted in order to test these predictions.

scholarly journals Testing donation menus: on charitable giving for cancer research – evidence from a natural field experiment

2019 ◽  
pp. 1-22
Author(s):  
MARIANNA BAGGIO ◽  
MATTEO MOTTERLINI
Keyword(s):  
Cancer Research ◽  
Field Experiment ◽  
Charitable Giving ◽  
Research Evidence ◽  
Low Frequency ◽  
Behavioral Responses ◽  
Average Amount ◽  
Charitable Behavior ◽  
Natural Field Experiment ◽  
The Given

AbstractBehavioral economics research has helped with understanding charitable behavior and has shown that charities can encourage donations by carefully designing their pledges. However, there is still scope to extend current research on who gives, what drives the decision to donate and at what levels, especially when behavioral insights are applied in context. In cooperation with a major Italian charity for cancer research, this study implements a natural direct mail field experiment, with over 150,000 letters sent to donors. By exploring the behavioral responses to different donation anchors, evidence was found that, within the given framework, including donation menus significantly increased the average amount donated without affecting the likelihood of donation. Furthermore, introducing additional explanations of how to make a payment significantly increased overall returns. Lastly, individual heterogeneity (high- and low-frequency donors, as well as senior and junior donors) had a direct effect on donations.

scholarly journals Wrapping the cube and other polyhedra

2012 ◽  
Vol 468 (2145) ◽  
pp. 2652-2666 ◽  
Author(s):  
T. Tarnai ◽  
F. Kovács ◽  
P. W. Fowler ◽  
S. D. Guest
Keyword(s):  
Regular Graph ◽  
Infinite Series ◽  
Complex Geometry ◽  
Convex Polyhedra ◽  
Octahedral Symmetry ◽  
Symmetry Constraint ◽  
Advanced Composite ◽  
Double Covers ◽  
Two Parameter

An infinite series of twofold, two-way weavings of the cube, corresponding to ‘wrappings’, or double covers of the cube, is described with the aid of the two-parameter Goldberg–Coxeter construction. The strands of all such wrappings correspond to the central circuits (CCs) of octahedrites (four-regular polyhedral graphs with square and triangular faces), which for the cube necessarily have octahedral symmetry. Removing the symmetry constraint leads to wrappings of other eight-vertex convex polyhedra. Moreover, wrappings of convex polyhedra with fewer vertices can be generated by generalizing from octahedrites to i -hedrites, which additionally include digonal faces. When the strands of a wrapping correspond to the CCs of a four-regular graph that includes faces of size greater than 4, non-convex ‘crinkled’ wrappings are generated. The various generalizations have implications for activities as diverse as the construction of woven-closed baskets and the manufacture of advanced composite components of complex geometry.

MATHEMATICAL ANALYSIS OF ELASTIC SURFACE WAVES IN TOPOGRAPHIC WAVEGUIDES

1999 ◽  
Vol 09 (05) ◽  
pp. 755-798 ◽  
Author(s):  
A. S. BONNET-BEN DHIA ◽  
J. DUTERTE ◽  
P. JOLY
Keyword(s):  
Free Surface ◽  
Half Space ◽  
Guided Waves ◽  
Transverse Energy ◽  
Eigenvalue Problems ◽  
Low Frequency ◽  
Elastic Half Space ◽  
High Frequencies ◽  
Guided Mode ◽  
Adjoint Operators

We present here a theoretical study of the guided waves in an isotropic homogeneous elastic half-space whose free surface has been deformed. The deformation is supposed to be invariant in the propagation direction and localized in the transverse ones. We show that finding guided waves amounts to solving a family of 2-D eigenvalue problems set in the cross-section of the propagation medium. Then using the min-max principle for non-compact self-adjoint operators, we prove the existence of guided waves for some particular geometries of the free surface. These waves have a smaller speed than that of the Rayleigh wave in the perfect half-space and a finite transverse energy. Moreover, we prove that the existence results are valid for arbitrary high frequencies in the presence of singularities of the free boundary. Finally, we prove that no guided mode can exist at low frequency, except maybe the fundamental one.

The Technology of Mig-Mag Welding with Low-Frequency Modulation of Arc Current

2014 ◽  
Vol 682 ◽  
pp. 426-430 ◽  
Author(s):  
S.A. Solodsky ◽  
N.Yu. Lugovtsova ◽  
I.S. Borisov
Keyword(s):  
Weld Pool ◽  
Theoretical Study ◽  
Low Frequency ◽  
Metal Structure ◽  
New Approach ◽  
Deposited Metal ◽  
Arc Current ◽  
Favorable Conditions ◽  
Pool Formation ◽  
The Given

The given paper suggests a new approach towards implementation of arc current low frequency modulating method in MAG, MIG-welding. The process facilitates controlling heat and crystallization processes, regulates the time of the weld pool formation and crystallization. Theoretical study allowed formulating the main criteria of receiving strong permanent joints to produce structures with advanced reliability as it creates favorable conditions for producing a more balanced deposited metal structure and reducing the heat-affected zone. Regulating the time of weld pool formation and crystallization improves weld formation and increases labor productivity when welding sheet metals.

scholarly journals The Scaling LInear Macroweather model (SLIM): using scaling to forecast global scale macroweather from months to decades

2015 ◽  
Vol 6 (1) ◽  
pp. 489-545 ◽  
Author(s):  
S. Lovejoy ◽  
L. del Rio Amador ◽  
R. Hébert
Keyword(s):  
Stochastic Models ◽  
High Frequency ◽  
Low Frequency ◽  
Global Scale ◽  
Forecast Skill ◽  
Previous Attempt ◽  
Frequency Noise ◽  
Forecast Errors ◽  
System Memory ◽  
Two Parameter

Abstract. At scales of ≈ 10 days (the lifetime of planetary scale structures), there is a drastic transition from high frequency weather to low frequency macroweather. This scale is close to the predictability limits of deterministic atmospheric models; so that in GCM macroweather forecasts, the weather is a high frequency noise. But neither the GCM noise nor the GCM climate is fully realistic. In this paper we show how simple stochastic models can be developped that use empirical data to force the statistics and climate to be realistic so that even a two parameter model can outperform GCM's for annual global temperature forecasts. The key is to exploit the scaling of the dynamics and the enormous stochastic memories that it implies. Since macroweather intermittency is low, we propose using the simplest model based on fractional Gaussian noise (fGn): the Scaling LInear Macroweather model (SLIM). SLIM is based on a stochastic ordinary differential equations, differing from usual linear stochastic models (such as the Linear Inverse Modelling, LIM) in that it is of fractional rather than integer order. Whereas LIM implicitly assumes there is no low frequency memory, SLIM has a huge memory that can be exploited. Although the basic mathematical forecast problem for fGn has been solved, we approach the problem in an original manner notably using the method of innovations to obtain simpler results on forecast skill and on the size of the effective system memory. A key to successful forecasts of natural macroweather variability is to first remove the low frequency anthropogenic component. A previous attempt to use fGn for forecasts had poor results because this was not done. We validate our theory using hindcasts of global and Northern Hemisphere temperatures at monthly and annual resolutions. Several nondimensional measures of forecast skill – with no adjustable parameters – show excellent agreement with hindcasts and these show some skill even at decadal scales. We also compare our forecast errors with those of several GCM experiments (with and without initialization), and with other stochastic forecasts showing that even this simplest two parameter SLIM model is somewhat superior. In future, using a space–time (regionalized) generalization of SLIM we expect to be able to exploiting the system memory more extensively and obtain even more realistic forecasts.

Sign in / Sign up

Export Citation Format

Share Document