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Lecture

Stability: Critical Buckling Length and Palm Tree Stability

In course

CIVIL-123: Structures II

Le cours permet de comprendre le fonctionnement, déterminer les efforts et de dimensionner les structures en treillis, en poutre, en dalle et en cadre. Le cours se base sur la résolution des efforts par la statique graphique. ...

Description

This lecture covers the critical buckling length of a section, stability of a palm tree, comparison to Euler's stability, stability of a guyed palm tree at the head, and the use of laser pointers and highlighters for analysis.

Instructor

Olivier Burdet

Born 1960, Olivier Burdet has received his Diploma in Civil Engineering from EPFL in 1983. After a couple years in engineering practice, he went back to studying at the university of Texas at Austin, where he received his PhD in 1990. Returning to EPFL in 1990, he is now a senior researcher and a lecturer in the field of reinforced concrete structures. He is also actively involved in the development of internet-based course contents and MOOCs.

Official source

Related concepts (22)

Laser pointer

A laser pointer or laser pen is a small handheld device with a power source (usually a battery) and a laser diode emitting a very narrow coherent low-powered laser beam of visible light, intended to be used to highlight something of interest by illuminating it with a small bright spot of colored light. The small width of the beam and low power of typical laser pointers make the beam itself invisible in a clean atmosphere, only showing a point of light when striking an opaque surface.

Laser diode

A laser diode (LD, also injection laser diode or ILD, or diode laser) is a semiconductor device similar to a light-emitting diode in which a diode pumped directly with electrical current can create lasing conditions at the diode's junction. Driven by voltage, the doped p–n-transition allows for recombination of an electron with a hole. Due to the drop of the electron from a higher energy level to a lower one, radiation, in the form of an emitted photon is generated. This is spontaneous emission.

Laser safety

Laser radiation safety is the safe design, use and implementation of lasers to minimize the risk of laser accidents, especially those involving eye injuries. Since even relatively small amounts of laser light can lead to permanent eye injuries, the sale and usage of lasers is typically subject to government regulations. Moderate and high-power lasers are potentially hazardous because they can burn the retina, or even the skin.

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word laser is an anacronym that originated as an acronym for light amplification by stimulated emission of radiation. The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories, based on theoretical work by Charles H. Townes and Arthur Leonard Schawlow. A laser differs from other sources of light in that it emits light that is coherent.

Stability theory

In mathematics, stability theory addresses the stability of solutions of differential equations and of trajectories of dynamical systems under small perturbations of initial conditions. The heat equation, for example, is a stable partial differential equation because small perturbations of initial data lead to small variations in temperature at a later time as a result of the maximum principle. In partial differential equations one may measure the distances between functions using Lp norms or the sup norm, while in differential geometry one may measure the distance between spaces using the Gromov–Hausdorff distance.

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