linkstream2 microblog

https://www.evilmadscientist.com/2011/microwave-oven-diagnostics-with-indian-snack-food/
QT:{{”
As an area of the cracker cooks, it bubbles up in just a few seconds, leaving clear marks as to where there is microwave power and where there isn’t. For this particular microwave, Saturn-shaped objects will cook evenly.

Obviously what is happening is that there are two hotspots in this microwave: one in the center, and one offset from center which traces out a circle thanks to the rotating plate in the bottom.

We have access to four other microwave ovens. Are they all this bad?For each microwave, we spread out four appalams on a plate and cooked them for 30 seconds.
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can also observe w/ melted cheese

https://edisontechcenter.org/Microwaves.html

QT:{{”
The microwave oven uses a magnetron to generate microwave energy. The microwave energy travels through a waveguide and is distributed into a metal cavity where the food is cooked. The waves are absorbed by the food and excite water molecules in the food. This heat then transfers throughout the food cooking it.
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https://www.sbsun.com/2009/11/21/caltech-mathematics-professor-dies/
QT:{{”
Fuller came to Caltech as a research fellow in 1952 and stayed on as a professor. His work focused on “writhing numbers,” a way of
mathematically describing supercoiled double-stranded DNA helices. “}}

https://www.ncbi.nlm.nih.gov/pubmed/19995626

QT:{{”
From its first test scan on a mouse, in 1967, to current medical practice, the CT scanner has become a core imaging tool in thoracic diagnosis. Initially financed by money from Beatles’ record sales, the first patient scan was performed in 1971. Only 8 years later, a Nobel Prize in Physics and Medicine was awarded to Hounsfield and Cormack for their discovery.
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https://en.wikipedia.org/wiki/Allan_MacLeod_Cormack

QT:{{”
Allan MacLeod Cormack (February 23, 1924 – May 7, 1998) was a South African American physicist who won the 1979 Nobel Prize in Physiology or Medicine (along with Godfrey Hounsfield) for his work on X-ray computed tomography (CT).[1]
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https://en.wikipedia.org/wiki/Godfrey_Hounsfield

QT:{{”
Sir Godfrey Newbold Hounsfield CBE FRS[1] (28 August 1919 – 12 August 2004)[2][3][4][5][6] was an English electrical engineer who shared the 1979 Nobel Prize for Physiology or Medicine with Allan McLeod Cormack for his part in developing the diagnostic technique of X-ray computed tomography (CT).[7][8][9][10][11]
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https://en.wikipedia.org/wiki/Wave_equation

QT:{{”
Introduction
The wave equation is a partial differential equation that may constrain some scalar function u = u (x1, x2, …, xn; t) of a time variable t and one or more spatial variables x1, x2, … xn. The quantity u may be, for example, the pressure in a liquid or gas, or the displacement, along some specific direction, of the particles of a vibrating solid away from their resting positions. The equation is

{\displaystyle {\frac {\partial ^{2}u}{\partial
t^{2}}}\;=\;c^{2}\left({\frac {\partial ^{2}u}{\partial
x_{1}^{2}}}+{\frac {\partial ^{2}u}{\partial x_{2}^{2}}}+\cdots +{\frac {\partial ^{2}u}{\partial x_{n}^{2}}}\right)}{\displaystyle {\frac {\partial ^{2}u}{\partial t^{2}}}\;=\;c^{2}\left({\frac {\partial ^{2}u}{\partial x_{1}^{2}}}+{\frac {\partial ^{2}u}{\partial x_{2}^{2}}}+\cdots +{\frac {\partial ^{2}u}{\partial
x_{n}^{2}}}\right)}
where c is a fixed non-negative real coefficient.

Using the notations of Newtonian mechanics and vector calculus, the wave equation can be written more compactly as

{\displaystyle {\ddot {u}}=c^{2}\nabla ^{2}u}{\displaystyle {\ddot {u}}=c^{2}\nabla ^{2}u}
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https://en.wikipedia.org/wiki/Poincar%C3%A9_map

QT:{{”
In mathematics, particularly in dynamical systems, a first recurrence map or Poincaré map, named after Henri Poincaré, is the intersection of a periodic orbit in the state space of a continuous dynamical system with a certain lower-dimensional subspace, called the Poincaré section, transversal to the flow of the system. More precisely, one considers a periodic orbit with initial conditions within a section of the space, which leaves that section afterwards, and observes the point at which this orbit first returns to the section. One then creates a map to send the first point to the second, hence the name first recurrence map. The transversality of the Poincaré section means that periodic orbits starting on the subspace flow through it and not parallel to it.

A Poincaré map can be interpreted as a discrete dynamical system with a state space that is one dimension smaller than the original continuous dynamical system. Because it preserves many properties of periodic and quasiperiodic orbits of the original system and has a lower-dimensional state space, it is often used for analyzing the original system in a simpler way. In practice this is not always possible as there is no general method to construct a Poincaré map. “}}