Boring stuff

The previous equation is still too general, and a connection between stress and strain is still needed. Here we consider the case in which there is a linear relationship between both, which involves the coefficient of viscosity.

To begin with, let us consider a simple case in which a fluid is confined between two planes. One of them moves sideways with a certain speed , while the other is kept fixed. After a certain transient, some force is needed in order to keep this shearing. The simplest expression is

The force is proportional to the area and to the velocity difference between the planes. It is also inversely proportional to their separation, L (this fact being the least obvious). Finally, a constant of proportionality is given by , the viscosity coefficient, or

simply “the viscosity”. This constant may vary with temperature, density, pressure, but the point with Newtonian fluids is that it does not vary with the velocity field (or its derivatives).

Later, in section …, this flow will be solved as a solution of the Navier-Stokes equations, the Couette flow. There, it will be shown that the velocity is everywhere in the direction of the force exerted on the upper plane, let us call it $x$, and varies linearly between the planes, in the y direction. Therefore, the only components of the strain rate tensor are . We therefore have

With this in mind, let us look for a general relationship between and . This is much easier if we go to the principal strain axes. These are the coordinates on which the strain rate is diagonal. Such coordinate system always exist, since the strain rate tensor is symmetric. Notice that in these system strains are not due to shear, only to dilations.

Better with stock pictures

“A connection is needed”. Photo by Pixabay on Pexels.com

 

The previous equation is still too general, and a connection between stress and strain is still needed. Here we consider the case in which there is a linear relationship between both, which involves the coefficient of viscosity.

 

 

 

 

Holy cow, is honey viscous or what. Photo by Pixabay on Pexels.com

To begin with, let us consider a simple case in which a fluid is confined between two planes. One of them moves sideways with a certain speed , while the other is kept fixed. After a certain transient, some force is needed in order to keep this shearing. The simplest expression is

 

 

 

The force is proportional to the area and to the velocity difference between the planes. It is also inversely proportional to their separation, L (this fact being the least obvious). Finally, a constant of proportionality is given by , the viscosity coefficient, or

Newton’s craddle. Another of this guy’s creations. Photo by Pixabay on Pexels.com

simply  “the viscosity”. This constant may vary with temperature, density, pressure, but the point with Newtonian fluids is that it does not vary with the velocity field (or its derivatives).

 

 

 

 

 

 

 

What a wave. Its strain tensors must be on fire. Photo by Emiliano Arano on Pexels.com

Later, in section …, this flow will be solved as a solution of the Navier-Stokes equations, the Couette flow. There, it will be shown that the velocity is everywhere in the direction of the force exerted on the upper plane, let us call it $x$, and varies linearly between the planes, in the y direction. Therefore, the only components of the strain rate tensor are . We therefore have

 

 

With this in mind, let us look for a general relationship between and $latex

What a bunch of math. This is so hard. Photo by Lum3n.com on Pexels.com

\epsilon$. This is much easier if we go to the principal strain axes. These are the coordinates on which the strain rate is diagonal. Such coordinate system always exist, since the strain rate tensor is symmetric. Notice that in these system strains are not due to shear, only to dilations.

Play station 3 actualizando al 99%

The o-nigiri project. Películas para ver con niños.

Una lista de pelis que ver con los niños que se salgan de la línea Disney.

Friends, la isla de los monstruos. En el enlace la tenéis enterita. Subtítulos en inglés. Producción japonesa de animación computerizada 3D (la primera que se ha hecho que sea largometraje, por lo visto).

Enest et célestine. Francesa, nominada al óscar 2014. Con moraleja, pero parece que es muy bonita visualmente.

Panique au Village. Colección de cortos belgas de stop-motion. Muy locos. Aquí tenéis uno de ellos.

Del Estudio Ghibli:

• El Castillo en el Cielo
• Nausicaa
• Lupin III

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Las peores letras

Una colección de letras de canciones de llorar.

Escuela de Muñecos, Cantajuego 5.

Hay una escuela en algún lugar para muñecos
Es una escuela muy especial, es de muñecos
No me preguntes dónde está
Pues nadie nunca la pudo hallar
Porque esta escuela es solamente para muñecos

No Hay Marcha En Nueva York, Mecano

No hay marcha en Nueva York
Ni aunque lo jure Henry Ford
No hay marcha en Nueva York
Y los jamones son de York

The names of Studio Ghibli

Is there some Studio Ghibli’s  obsession with names that sound S-S-K?

Just consider the name of these main characters:

• Setsuko, Grave_of_the Fireflies
• Satsuki, My Neighbour Totoro
• Shizuku, Whisper of the Heart
• Sōsuke, Ponyo

And, to a lesser degree:

• Ashitaka, Princess Mononoke

 

The BrainFuck programming language

So, there’s a programming language with a name that cannot be spoken in public. A bit like the band The Butthole Surfers. I noticed it by a reference in the pygments site (pygments is a sort of super prettyprinter). The source code makes it clear why that name was chosen.

From the archive at esoteric.sange.fi/brainfuck

99 Bottles of Beer in Urban Mueller's BrainF*** (The actual
name is impolite)

by Ben Olmstead

ANSI C interpreter available on the internet; due to
constraints in comments the address below needs to have the
stuff in parenthesis replaced with the appropriate symbol:

http://www(dot)cats(dash)eye(dot)com/cet/soft/lang/bf/

Believe it or not this language is indeed Turing complete!
Combines the speed of BASIC with the ease of INTERCAL and
the readability of an IOCCC entry!

>+++++++++[<+++++++++++>-]<[>[-]>[-]<<[>+>+<<-]>>[<<+>>-]>>>
[-]<<<+++++++++<[>>>+<<[>+>[-]<<-]>[<+>-]>[<<++++++++++>>>+<
-]<<-<-]+++++++++>[<->-]>>+>[<[-]<<+>>>-]>[-]+<<[>+>-<<-]<<<
[>>+>+<<<-]>>>[<<<+>>>-]>[<+>-]<<-[>[-]<[-]]>>+<[>[-]<-]<+++
+++++[<++++++<++++++>>-]>>>[>+>+<<-]>>[<<+>>-]<[<<<<<.>>>>>-
]<<<<<<.>>[-]>[-]++++[<++++++++>-]<.>++++[<++++++++>-]<++.>+
++++[<+++++++++>-]<.><+++++..--------.-------.>>[>>+>+<<<-]>
>>[<<<+>>>-]<[<<<<++++++++++++++.>>>>-]<<<<[-]>++++[<+++++++
+>-]<.>+++++++++[<+++++++++>-]<--.---------.>+++++++[<------
---->-]<.>++++++[<+++++++++++>-]<.+++..+++++++++++++.>++++++
++[<---------->-]<--.>+++++++++[<+++++++++>-]<--.-.>++++++++
[<---------->-]<++.>++++++++[<++++++++++>-]<++++.-----------
-.---.>+++++++[<---------->-]<+.>++++++++[<+++++++++++>-]<-.
>++[<----------->-]<.+++++++++++..>+++++++++[<---------->-]<
-----.---.>>>[>+>+<<-]>>[<<+>>-]<[<<<<<.>>>>>-]<<<<<<.>>>+++
+[<++++++>-]<--.>++++[<++++++++>-]<++.>+++++[<+++++++++>-]<.
><+++++..--------.-------.>>[>>+>+<<<-]>>>[<<<+>>>-]<[<<<<++
++++++++++++.>>>>-]<<<<[-]>++++[<++++++++>-]<.>+++++++++[<++
+++++++>-]<--.---------.>+++++++[<---------->-]<.>++++++[<++
+++++++++>-]<.+++..+++++++++++++.>++++++++++[<---------->-]<
-.---.>+++++++[<++++++++++>-]<++++.+++++++++++++.++++++++++.
------.>+++++++[<---------->-]<+.>++++++++[<++++++++++>-]<-.
-.---------.>+++++++[<---------->-]<+.>+++++++[<++++++++++>-
]<--.+++++++++++.++++++++.---------.>++++++++[<---------->-]
<++.>+++++[<+++++++++++++>-]<.+++++++++++++.----------.>++++
+++[<---------->-]<++.>++++++++[<++++++++++>-]<.>+++[<----->
-]<.>+++[<++++++>-]<..>+++++++++[<--------->-]<--.>+++++++[<
++++++++++>-]<+++.+++++++++++.>++++++++[<----------->-]<++++
.>+++++[<+++++++++++++>-]<.>+++[<++++++>-]<-.---.++++++.----
---.----------.>++++++++[<----------->-]<+.---.[-]<<<->[-]>[
-]<<[>+>+<<-]>>[<<+>>-]>>>[-]<<<+++++++++<[>>>+<<[>+>[-]<<-]
>[<+>-]>[<<++++++++++>>>+<-]<<-<-]+++++++++>[<->-]>>+>[<[-]<
<+>>>-]>[-]+<<[>+>-<<-]<<<[>>+>+<<<-]>>>[<<<+>>>-]<>>[<+>-]<
<-[>[-]<[-]]>>+<[>[-]<-]<++++++++[<++++++<++++++>>-]>>>[>+>+
<<-]>>[<<+>>-]<[<<<<<.>>>>>-]<<<<<<.>>[-]>[-]++++[<++++++++>
-]<.>++++[<++++++++>-]<++.>+++++[<+++++++++>-]<.><+++++..---
-----.-------.>>[>>+>+<<<-]>>>[<<<+>>>-]<[<<<<++++++++++++++
.>>>>-]<<<<[-]>++++[<++++++++>-]<.>+++++++++[<+++++++++>-]<-
-.---------.>+++++++[<---------->-]<.>++++++[<+++++++++++>-]
<.+++..+++++++++++++.>++++++++[<---------->-]<--.>+++++++++[
<+++++++++>-]<--.-.>++++++++[<---------->-]<++.>++++++++[<++
++++++++>-]<++++.------------.---.>+++++++[<---------->-]<+.
>++++++++[<+++++++++++>-]<-.>++[<----------->-]<.+++++++++++
..>+++++++++[<---------->-]<-----.---.+++.---.[-]<<<]

Lista de expresiones inglesas sin traducción

Aquí recopilaré expresiones inglesas que me gustan y que carecen de una traducción buena al español.

Ciencia

• Bulk. ¿Volumen? ¿En bruto?
• Cluster. ¿Racimo?
• Core / heart / kernel (todas son “corazón” en castellano)
• Embedded. ¿Empotrado? ¿Embebido? ¿Incrustado?
• Scatter. ¿Dispersar? ¿Esparcir?

Informales

• Wishful thinking
• So much for (e.g. “… instilling them with a sense of awe“)
• You and what army. (La traducción literal ya se oye por ahí.)
• Yes we can
• Yes we want (es broma)
• As if
• Whatever
  
• Six feet under (¿muerto y enterrao? ¿criando malvas = pushing daisies?).

Miedito

• Doom. ¿Condenación? ¿Destino? ¿Mal rollo?
• Relacionado: impending doom. Como en esta gloriosa frase del manual Merck de medicina sobre infartos cardiacos: Sometimes the only symptom is a feeling of impending doom.
• Awe (¿temor reverencial?)
• Haunted
• Hallowed y Hallow (como en Harry Potter)

Genéricas

• Hardcore. Se dice tal cual (“jarcor”) en distintos contextos, esp. en música, pero en inglés es la misma palabra: “nucleo duro”, como en “linea dura” (hardline).

The Onion on Science

Just a list of The Onion articles about science that I find funny:

• Christian Right Lobbies To Overturn Second Law Of Thermodynamics. The second law of thermodynamics, a fundamental scientific principle stating that entropy increases over time as organized forms decay into greater states of randomness, has come under fire from conservative Christian groups, who are demanding that the law be repealed.
• Bush Finds Error In Fermilab Calculations. President Bush met with members of the Fermi National Accelerator Laboratory research team Monday to discuss a mathematical error he recently discovered in the famed laboratory’s “Improved Determination Of Tau Lepton Paths From Inclusive Semileptonic B-Meson Decays” report.
• National Science Foundation: Science Hard. The National Science Foundation’s annual symposium concluded Monday, with the 1,500 scientists in attendance reaching the consensus that science is hard.
• World’s Top Scientists Ponder: What If The Whole Universe Is, Like, One Huge Atom? Gathering for what members of the international science community are calling “potentially the most totally out-to-lunch freaky head trip since Einstein postulated that space and time were, like, curved and shit,” a consortium of the world’s top physicists descended upon Stanford University Monday to discuss some of the difficult questions facing the cutting edge of theoretical thinking.
• Raving Lunatic Obviously Took Some Advanced Physics… “Where’s my cheese? Don’t take my rowboat! Got no room!” the lunatic screamed from his regular spot near the Campus Drive bus stop. “I need space! Gimme space! Infinite dimensional separable Hilbert space!”.
• Evangelical Scientists Refute Gravity With New ‘Intelligent Falling’ Theory. As the debate over the teaching of evolution in public schools continues, a new controversy over the science curriculum arose Monday in this embattled Midwestern state. Scientists from the Evangelical Center For Faith-Based Reasoning are now asserting that the long-held “theory of gravity” is flawed, and they have responded to it with a new theory of Intelligent Falling.
• High-School Science Teacher Takes Fun And Excitement Out Of Science. Verona High School ninth-grade science teacher Mark Randalls has a unique talent for taking the fun and magic out of science, students of his comprehensive survey class reported Tuesday.

Addendum

Britney Spears .ac, including Britney Spears’ Guide to Semiconductor Physics, with articles such as Semiconductor Transport: The Einstein Relations.