in order to determine the stability of underwater robots, their governing differential equations of motion in vertical and horizontal planes should be investigated. for horizontal plane stability, using routh stability criterion, four hydrodynamic coefficients, including derivatives of the lateral force and vertical moment with respect to sway and angular velocity are required. these coefficien...

Shamos [1] recently showed that the diameter of a convex n-sided polygon could be computed in O(n) time using a very elegant and simple procedure which resembles rotating a set of calipers around the polygon once. In this paper we show that this simple idea can be generalized in two ways: several sets of calipers can be used simultaneously on one convex polygon, or one set of calipers can be us...

Rotating Shadowband Pyranometers (RSPs) have been deployed to measure global, beam, and diffuse irradiance because they do not require manual adjustment of trackers. However, a RSP requires the use of solar cell based pyranometers which underestimate diffuse irradiance by 20-30% under clear sky conditions. Algorithms were derived to address many of the systematic errors in solar cell based meas...

When density fluctuations of scalars such as CO2 are measured with openpath gas analyzers, the measured vertical turbulent flux must be adjusted to take into account fluctuations induced by ‘external effects’ such as temperature and water vapour. These adjustments are needed to separate the effects of surface fluxes responsible for ‘natural’ fluctuations in CO2 concentration from these external...

ion The technique of abstraction is based on making useful generalisations. The purpose of the generalisations is to understand and articulate the rules that apply to a specific domain of knowledge and even to discover rules that are shared between domains. Many people find it very difficult to think in terms of abstractions and are much more comfortable thinking in terms of specific instances....

The instability modes of the infinitesimally thin self-gravitating disk, which is composed of rotating and non-rotating parts, are investigated. By solving the dispersion relation numerically under various physical situations, two growing modes are found. They are the modified Jeans mode of rotating component or non-rotating one and the Landau mode by wave-particle (non-rotating component) inte...

In this study, two-dimensional electro-mechanical analysis of a composite rotating shaft subjected to non-axisymmetric internal pressure and applied voltage is investigated where hollow piezoelectric shaft reinforced by boron nitride nanotubes (BNNTs). Composite structure is modeled based on piezoelectric fiber reinforced composite (PFRC) theory and a representative volume element has been cons...

In this paper, a semi-analytical solution for magneto-thermo-elastic problem in an axisymmetric functionally graded (FG) hollow rotating disk with constant thickness placed in uniform magnetic and thermal fields with heat convection from disk’s surfaces is presented. Solution for stresses and perturbation of magnetic field vector in a thin FG rotating disk is determined using infinitesimal theo...