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{{Other uses|Rotation operator (disambiguation){{!}}Rotation operator}}
It involves expertise and knowledge of various tools and technologies used for creating websites. Also, you may want to opt for a more professioanl theme if you are planning on showing your site off to a high volume of potential customers each day. Your parishioners and certainly interested audience can come in to you for further information from the group and sometimes even approaching happenings and systems with the church. In the recent years, there has been a notable rise in the number of companies hiring Indian Word - Press developers. You can easily customize the titles of the posts in Word - Press blog in a way that only title comes in the new post link and not the date or category of posts. <br><br>Creating a website from scratch can be such a pain. While direct advertising is limited to few spots in your site and tied to fixed monthly payment by the advertisers, affiliate marketing can give you unlimited income as long as you can convert your traffic to sales. Several claim that Wordpress just isn't an preferred tool to utilise when developing a professional site. They provide many such popular products which you can buy for your baby. For a Wordpress website, you don't need a powerful web hosting account to host your site. <br><br>Digital photography is a innovative effort, if you removethe stress to catch every position and viewpoint of a place, you free yourself up to be more innovative and your outcomes will be much better. Now if we talk about them one by one then -wordpress blog customization means customization of your blog such as installation of wordpress on your server by wordpress developer which will help you to acquire the SEO friendly blog application integrated with your site design as well as separate blog administration panel for starting up your own business blog,which demands a experienced wordpress designer. Are you considering getting your website redesigned. Storing write-ups in advance would have to be neccessary with the auto blogs. Purchase these from our site, or bring your own, it doesn't matter, we will still give you free installation and configuration. <br><br>The disadvantage is it requires a considerable amount of time to set every thing up. I didn't straight consider near it solon than one distance, I got the Popup Ascendancy plugin and it's up and lengthways, likely you make seen it today when you visited our blog, and I yet customize it to fit our Thesis Wound which gives it a rattling uncomparable visage and search than any different popup you know seen before on any added journal, I hump arrogated asset of one of it's quatern themes to make our own. When we talk about functional suitability, Word - Press proves itself as one of the strongest contestant among its other rivals. IVF ,fertility,infertility expert,surrogacy specialist in India at Rotundaivf. If your blog employs the permalink function, This gives your SEO efforts a boost, and your visitors will know firsthand what's in the post when seeing the URL. <br><br>Website security has become a major concern among individuals all over the world. Mahatma Gandhi is known as one of the most prominent personalities and symbols of peace, non-violence and freedomWhen you have almost any concerns regarding wherever as well as the way to use [http://www.tesla-games.com/profile/gimoffit backup plugin], it is possible to email us from our own site. However, you must also manually approve or reject comments so that your website does not promote parasitic behavior. Page speed is an important factor in ranking, especially with Google. Get started today so that people searching for your type of business will be directed to you.
 
This article derives the main properties of rotations in 3-dimensional space.
 
The three [[Euler angles|Euler rotations]] are one way to bring a [[rigid body]] to any desired orientation by sequentially making [[rotations]] about axis' fixed relative to the object.  However, this can also be achieved with one single rotation ([[Euler's rotation theorem]]). Using the concepts of [[linear algebra]] it is shown how this single
rotation can be performed.
 
==Mathematical formulation==
Let
:<math>\hat e_1\ ,\ \hat e_2\ ,\ \hat e_3</math>
 
be a [[coordinate system]] fixed in the body that through a change in orientation is brought to the new directions
:<math>\mathbf{A}\hat e_1\ ,\ \mathbf{A}\hat e_2\ ,\ \mathbf{A}\hat e_3.</math>
 
Any [[euclidean vector|vector]]
:<math>\bar x\ =x_1\hat e_1+x_2\hat e_2+x_3\hat e_3</math>
 
rotating with the body is then brought to the new direction
:<math>\mathbf{A}\bar x\ =x_1\mathbf{A}\hat e_1+x_2\mathbf{A}\hat e_2+x_3\mathbf{A}\hat e_3</math>
 
i.e. this is a [[linear operator]]
 
The [[Matrix (mathematics)|matrix]] of this [[Operator (mathematics)|operator]] relative to the coordinate system
:<math>\hat e_1\ ,\ \hat e_2\ ,\ \hat e_3</math>
 
is
:<math>
\begin{bmatrix}
  A_{11} & A_{12} & A_{13} \\
  A_{21} & A_{22} & A_{23} \\
  A_{31} & A_{32} & A_{33}
\end{bmatrix} =
\begin{bmatrix}
  \langle\hat e_1 | \mathbf{A}\hat e_1 \rangle & \langle\hat e_1 | \mathbf{A}\hat e_2 \rangle & \langle\hat e_1 | \mathbf{A}\hat e_3 \rangle \\
  \langle\hat e_2 | \mathbf{A}\hat e_1 \rangle & \langle\hat e_2 | \mathbf{A}\hat e_2 \rangle & \langle\hat e_2 | \mathbf{A}\hat e_3 \rangle \\
  \langle\hat e_3 | \mathbf{A}\hat e_1 \rangle & \langle\hat e_3 | \mathbf{A}\hat e_2 \rangle & \langle\hat e_3 | \mathbf{A}\hat e_3 \rangle
\end{bmatrix}
</math>
 
As
:<math> \sum_{k=1}^3 A_{ki}A_{kj}= \langle \mathbf{A}\hat e_i | \mathbf{A}\hat e_j \rangle
= \begin{cases}
0 & i\neq j, \\                                                                                1 & i = j,
\end{cases}
</math>
 
or equivalently in matrix notation
 
:<math>
\begin{bmatrix}
  A_{11} & A_{12} & A_{13} \\
  A_{21} & A_{22} & A_{23} \\
  A_{31} & A_{32} & A_{33}
\end{bmatrix}^T
\begin{bmatrix}
  A_{11} & A_{12} & A_{13} \\
  A_{21} & A_{22} & A_{23} \\
  A_{31} & A_{32} & A_{33}
\end{bmatrix} =
\begin{bmatrix}
  1 & 0 & 0 \\
  0 & 1 & 0 \\
  0 & 0 & 1
\end{bmatrix}
</math>
the matrix is [[Orthogonal matrix|orthogonal]] and as a "right hand" base vector system is re-orientated into another "right hand" system the [[determinant]] of this matrix has the value 1.
 
===Rotation around an axis===
Let
 
:<math>\hat e_1\ ,\ \hat e_2\ ,\ \hat e_3</math>
 
be an orthogonal positively oriented base vector system in <math>R^3</math>.
 
The linear operator
 
"Rotation with the angle <math>\theta</math> around the axis defined by <math>\hat e_3</math>"
 
has the matrix representation
 
:<math>
\begin{bmatrix}
  Y_1  \\
  Y_2  \\
  Y_3
\end{bmatrix}
=
\begin{bmatrix}
  \cos\theta & -\sin\theta & 0 \\
  \sin\theta &  \cos\theta & 0 \\
          0 &          0 & 1
\end{bmatrix}
\begin{bmatrix}
  X_1  \\
  X_2  \\
  X_3
\end{bmatrix}
</math>
 
relative to this basevector system.  
 
This then means that a vector
 
:<math>
\bar x=\begin{bmatrix}
  \hat e_1 & \hat e_2 & \hat e_3
\end{bmatrix}
\begin{bmatrix}
  X_1  \\
  X_2  \\
  X_3
\end{bmatrix}
</math>
 
is rotated to the vector
 
:<math>
\bar y=\begin{bmatrix}
  \hat e_1 & \hat e_2 & \hat e_3
\end{bmatrix}
\begin{bmatrix}
  Y_1  \\
  Y_2  \\
  Y_3
\end{bmatrix}
</math>
 
by the linear operator.  
 
The [[determinant]] of this matrix is
 
:<math>
\det
\begin{bmatrix}
  \cos\theta  & -\sin\theta & 0\\
  \sin\theta  &  \cos\theta & 0\\
          0  &          0 & 1
\end{bmatrix}=1
</math>
 
and the [[characteristic polynomial]] is
 
:<math>
\begin{align}
\det\begin{bmatrix}
  \cos\theta -\lambda  & -\sin\theta          & 0        \\
  \sin\theta          &  \cos\theta -\lambda & 0        \\
                    0 &                    0 & 1-\lambda
\end{bmatrix}
&=\big({(\cos\theta -\lambda)}^2 + {\sin\theta}^2 \big)(1-\lambda) \\
&=-\lambda^3+(2\ \cos\theta\ +\ 1)\ \lambda^2 - (2\ \cos\theta\ +\ 1)\ \lambda +1 \\
\end{align}
</math>
 
The matrix is symmetric if and only if <math>\sin\theta=0</math>, i.e. for <math>\theta=0</math>
and for <math>\theta=\pi</math>.
 
The case <math>\theta=0</math> is the trivial case of an identity operator.
 
For the case <math>\theta=\pi</math> the [[characteristic polynomial]] is
 
:<math>
-(\lambda-1){(\lambda +1)}^2
</math>
 
i.e. the rotation operator has the [[eigenvalue]]s
:<math>
\lambda=1 \quad \lambda=-1
</math>
 
The [[eigenspace]] corresponding to <math>\lambda=1</math> is all vectors on the rotation axis, i.e. all vectors
 
:<math>
\bar x  =\alpha \ \hat e_3 \quad -\infty <\alpha < \infty
</math>
 
The [[eigenspace]] corresponding to <math>\lambda=-1</math> consists of all vectors orthogonal to the rotation axis, i.e. all vectors
 
:<math>
\bar x  =\alpha \ \hat e_1 + \beta \ \hat e_2 \quad -\infty <\alpha < \infty \quad -\infty <\beta < \infty
</math>
 
For all other values of <math>\theta</math> the matrix is un-symmetric and as <math>{\sin\theta}^2 > 0</math> there is
only the eigenvalue <math>\lambda=1</math> with the one-dimensional [[eigenspace]] of the vectors on the rotation axis:
 
:<math>
\bar x  =\alpha \ \hat e_3 \quad -\infty <\alpha < \infty
</math>
 
The rotation matrix by angle <math>\theta</math> around a general axis of rotation
<math>
\mathbf{k} = \left[\begin{array}{ccc}
k_1  \\
k_2 \\
k_3
\end{array}\right]
</math>
is given by [[Rodrigues' rotation formula]].
: <math>
  R = I \cos\theta + [\mathbf{k}]_\times \sin\theta + (1 - \cos\theta) \mathbf{k} \mathbf{k}^\mathsf{T}
</math>,
 
where <math>I</math> is the [[identity matrix]] and <math>[\mathbf{k}]_\times</math> is the [[Hodge_star | dual 2-form]] of <math>\mathbf{k}</math> or
[[Cross_product | cross product matrix]],
 
: <math> [\mathbf{k}]_\times  =
\left[\begin{array}{ccc}
0 & -k_3 & k_2 \\
k_3 & 0 & -k_1 \\
-k_2 & k_1 & 0
\end{array}\right]
</math>.
 
Note that <math>[\mathbf{k}]_\times </math> satisfies <math>[\mathbf{k}]_\times \mathbf{v} = \mathbf{k}\times\mathbf{v} </math> for all  <math>\mathbf{v}</math>.
 
===The general case===
The operator
 
"Rotation with the angle <math>\theta</math> around a specified axis"
 
discussed above is an orthogonal mapping and its matrix relative to any base vector system is therefore an
[[orthogonal matrix]] . Furthermore its determinant  has the value 1.
A non-trivial fact is the opposite, i.e. that for any orthogonal linear mapping in <math>R^3</math> having
determinant = 1 there exist base vectors
 
:<math>\hat e_1\ ,\ \hat e_2\ ,\ \hat e_3</math>
 
such that the matrix takes the "canonical form"
 
:<math>
\begin{bmatrix}
\cos\theta & -\sin\theta & 0 \\
\sin\theta &  \cos\theta & 0 \\
          0 &          0 & 1\end{bmatrix}
</math>
 
for some value of <math>\theta</math>.  
 
In fact, if a linear operator has the [[orthogonal matrix]]
 
:<math>
\begin{bmatrix}
  A_{11} & A_{12} & A_{13} \\
  A_{21} & A_{22} & A_{23} \\
  A_{31} & A_{32} & A_{33}
\end{bmatrix}
</math>
relative some base vector system
:<math>\hat f_1\ ,\ \hat f_2\ ,\ \hat f_3</math>
 
and this matrix is symmetric, the "Symmetric operator theorem" valid in <math>R^n</math> (any dimension) applies saying
 
that it has ''n'' orthogonal eigenvectors.  This means for the 3-dimensional case that there exists a coordinate system
:<math>\hat e_1\ ,\ \hat e_2\ ,\ \hat e_3</math>
 
such that the matrix takes the form
:<math>
\begin{bmatrix}
  B_{11} &    0 &    0 \\
      0  & B_{22} &    0 \\
      0  &    0 & B_{33}
\end{bmatrix}
</math>
As it is an orthogonal matrix these diagonal elements <math>B_{ii}</math> are either 1 or &minus;1. As the determinant is 1 these elements
are either all 1 or one of the elements is 1 and the other two are &minus;1.
 
In the first case it is the trivial identity operator corresponding
to <math>\theta=0</math>.  
 
In the second case it has the form
 
:<math>
\begin{bmatrix}
    -1  &    0 &    0 \\
      0  &    -1 &    0 \\
      0  &    0 &    1
\end{bmatrix}
</math>
 
if the basevectors are numbered such that the one with eigenvalue 1 has index 3. This matrix is then of the desired form for <math>\theta=\pi</math>.
 
If the matrix is un-symmetric, the vector
:<math>
\bar E = \alpha_1\ \hat f_1 + \alpha_2\ \hat f_2 + \alpha_3\ \hat f_3
</math>
 
where
 
:<math>\alpha_1=\frac{A_{32}-A_{23} }{2} </math>
:<math>\alpha_2=\frac{A_{13}-A_{31}}{2}</math>
:<math>\alpha_3=\frac{A_{21}-A_{12}}{2}</math>
 
is non-zero. This vector is an eigenvector with eigenvalue
 
:<math>
\lambda=1
</math>
 
Setting
:<math>
\hat e_3=\frac{\bar E}{|\bar E|}
</math>
 
and selecting any two orthogonal unit vectors in the plane orthogonal to <math>\hat e_3</math>:
 
:<math>\hat e_1\ ,\ \hat e_2</math>
 
such that
 
:<math>\hat e_1\ ,\ \hat e_2,\ \hat e_3</math>
 
form a positively oriented triple, the operator takes the desired form with
:<math>\cos \theta=\frac{A_{11}+A_{22}+A_{33}-1}{2}</math>
:<math>\sin \theta=|\bar{E}|</math>
 
The expressions above are in fact valid also for the case of a symmetric
rotation operator corresponding to a rotation with <math>\theta = 0</math>
or <math>\theta = \pi</math>. But the difference is that for <math>\theta = \pi</math>
the vector
:<math>
\bar E = \alpha_1\ \hat f_1 + \alpha_2\ \hat f_2 + \alpha_3\ \hat f_3
</math>
 
is zero and of no use for finding the eigenspace of eigenvalue 1, i.e. the
rotation axis.
 
Defining <math>E_4</math> as <math>\cos \theta</math> the matrix for the
rotation operator is
 
:<math>
\frac{1-E_4}{{E_1}^2+{E_2}^2+{E_3}^2}
\begin{bmatrix}
E_1 E_1 & E_1 E_2 & E_1 E_3 \\
E_2 E_1 & E_2 E_2 & E_2 E_3 \\
E_3 E_1 & E_3 E_2 & E_3 E_3
\end{bmatrix}
+
\begin{bmatrix}
E_4 & -E_3 &  E_2 \\
E_3 &  E_4 & -E_1 \\
-E_2 &  E_1 &  E_4
\end{bmatrix}
</math>
 
provided that
 
:<math>
{E_1}^2+{E_2}^2+{E_3}^2 > 0
</math>
 
i.e. except for the cases <math>\theta=0</math> (the identity operator) and <math>\theta=\pi</math>
 
==Quaternions==
{{Main|Quaternions and spatial rotation}}
 
Quaternions are defined similar to <math>E_1\ ,\ E_2\ ,\ E_3\ ,\ E_4</math> with
the difference that the half angle  <math>\frac{\theta}{2}</math> is used
instead of the full angle <math>\theta</math>.
 
This means that the first 3 components <math>q_1\ ,\ q_2\ ,\ q_3\ </math> are components of a vector defined from
 
:<math>
q_1\ \hat{f_1}\ +\ q_2\ \hat{f_2}\ +\ \ q_3\ \hat{f_1}\ =\ \sin \frac{\theta}{2}\quad \hat{e_3}=\frac{\sin \frac{\theta}{2}}{\sin\theta}\quad \bar E
</math>
and that the fourth component is the scalar
:<math>
q_4=\cos \frac{\theta}{2}
</math>
 
As the angle <math>\theta</math> defined from the canonical form is in the interval
:<math>0 \le \theta \le \pi</math>
 
one would normally have that <math>q_4 \ge 0</math>. But a "dual" representation of a rotation with quaternions
is used, i.e.
:<math>q_1\ ,\ q_2\ ,\ q_3\ ,\ q_4\ </math>
 
and  
:<math>-q_1\ ,\ -q_2\ ,\ -q_3\ ,\ -q_4\ </math>
 
are two alternative representations of one and the same rotation.
 
The entities <math>E_k</math> are defined from the quaternions by
:<math> E_1=2 q_4 q_1</math>
:<math> E_2=2 q_4 q_2</math>
:<math> E_3=2 q_4 q_3</math>
:<math> E_4={q_4}^2 -({q_1}^2+{q_2}^2+{q_3}^2)</math>
 
Using quaternions the matrix of the rotation operator is
:<math>\begin{bmatrix}
2({q_1}^2+{q_4}^2)-1        &2({q_1}{q_2}-{q_3}{q_4})      &2({q_1}{q_3}+{q_2}{q_4}) \\
2({q_1}{q_2}+{q_3}{q_4})    &2({q_2}^2+{q_4}^2)-1          &2({q_2}{q_3}-{q_1}{q_4})  \\
2({q_1}{q_3}-{q_2}{q_4})    &2({q_2}{q_3}+{q_1}{q_4})      &2({q_3}^2+{q_4}^2)-1    \\
\end{bmatrix}</math>
 
==Numerical example==
 
Consider the reorientation corresponding to the [[Euler angle]]s
<math>
\alpha=10^\circ \quad \beta=20^\circ \quad \gamma=30^\circ \quad
</math>
relative a given base vector system
:<math>\hat f_1\ ,\ \hat f_2,\ \hat f_3</math>
 
Corresponding matrix relative to this base vector system is (see [[Euler angles#Matrix orientation]])
 
:<math>
\begin{bmatrix}
  0.771281 & -0.633718 &  0.059391 \\
  0.613092 &  0.714610 & -0.336824 \\
  0.171010 &  0.296198 &  0.939693
\end{bmatrix}
</math>
 
and the quaternion is
:<math>
(0.171010,\ -0.030154,\ 0.336824,\ 0.925417)
</math>
 
The canonical form of this operator
:<math>
\begin{bmatrix}
  \cos\theta  & -\sin\theta & 0\\
  \sin\theta  &  \cos\theta & 0\\
          0  &          0 & 1
\end{bmatrix}
</math>
with <math>\theta=44.537^\circ </math> is obtained with
:<math>\hat e_3=(0.451272,-0.079571,0.888832)</math>
 
The quaternion relative to this new system is then
:<math>
(0,\ 0,\ 0.378951,\ 0.925417) = (0,\ 0,\ \sin\frac{\theta}{2},\ \cos\frac{\theta}{2})
</math>
 
Instead of making the three Euler rotations
 
:<math>10^\circ,20^\circ,30^\circ</math>
 
the same orientation can be reached with one single rotation of size <math>44.537^\circ</math> around <math>\hat e_3</math>
 
==References==
* {{citation |title=An Introduction to the Theory of Linear Spaces|first=Georgi|last= Shilov|author-link =Georgii Evgen'evich Shilov|publisher= Prentice-Hall|year=1961|id=Library of Congress 61-13845}}.
 
[[Category:Linear algebra]]
[[Category:Kinematics]]

Latest revision as of 08:11, 17 December 2014

It involves expertise and knowledge of various tools and technologies used for creating websites. Also, you may want to opt for a more professioanl theme if you are planning on showing your site off to a high volume of potential customers each day. Your parishioners and certainly interested audience can come in to you for further information from the group and sometimes even approaching happenings and systems with the church. In the recent years, there has been a notable rise in the number of companies hiring Indian Word - Press developers. You can easily customize the titles of the posts in Word - Press blog in a way that only title comes in the new post link and not the date or category of posts.

Creating a website from scratch can be such a pain. While direct advertising is limited to few spots in your site and tied to fixed monthly payment by the advertisers, affiliate marketing can give you unlimited income as long as you can convert your traffic to sales. Several claim that Wordpress just isn't an preferred tool to utilise when developing a professional site. They provide many such popular products which you can buy for your baby. For a Wordpress website, you don't need a powerful web hosting account to host your site.

Digital photography is a innovative effort, if you removethe stress to catch every position and viewpoint of a place, you free yourself up to be more innovative and your outcomes will be much better. Now if we talk about them one by one then -wordpress blog customization means customization of your blog such as installation of wordpress on your server by wordpress developer which will help you to acquire the SEO friendly blog application integrated with your site design as well as separate blog administration panel for starting up your own business blog,which demands a experienced wordpress designer. Are you considering getting your website redesigned. Storing write-ups in advance would have to be neccessary with the auto blogs. Purchase these from our site, or bring your own, it doesn't matter, we will still give you free installation and configuration.

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