text:
User:Eml4500.f08.delta 6.castrillon/HW 4

= Connectivity & Location Matrix Master Arrays =

Consider the two-bar truss below:

and its respective bar element:

We can notice that there is a common global node, and its corresponding dofs, when comparing both bar element diagrams. Since the FEA method can be applied to a large system with multiple common nodes an elements, then it is important to organize these element notations so as to visualize which elements share which nodes and bounded by which dofs.

The Connectivity Array, "conn"
This array is set up as follows:

 * $$\begin{matrix}

1 & 2 \end{matrix}$$   <-- Local node numbers

 * conn = $$\left.\ \begin{vmatrix}

1 & 2\\ 2 & 3 \end{vmatrix} \right\}$$ <-- Global node numbers, each row for each element

In short-hand notation, we say that conn = (e,j): global node number of local node j of element e.

The Location Matrix Master Array, "lmm"
This array is set up as follows:

 * $$\begin{matrix}

1 & 2 & 3 & 4 \end{matrix}$$   <-- Local dofs numbers

 * lmm = $$\left.\ \begin{vmatrix}

1 & 2 & 3 & 4\\ 3 & 4 & 5 & 6 \end{vmatrix} \right\}$$ <-- Global dofs numbers, each row for each element

In short-hand notation, we say that lmm = (i,j): equation number (global dof number) for the element stiffness coefficient corresponding to the jth local dof number.


text:
User:Eml4500.f08.wiki1.schaet/hw3

Meeting 14 - 26 September 2008
Similarly, (same argument): $$ \begin{Bmatrix} P_1^{(e)} \\ P_2^{(e)} \end{Bmatrix} = I^{(e)} \begin{Bmatrix} f_1^{(e)} \\ f_2^{(e)} \\ f_3^{(e)} \\ f_4^{(e)}\end{Bmatrix} $$ b Where P is a 2x1 matrix, I is a 2x4 matrix, and f is a 4x1 matrix. This relationship is the same as saying $$ \underline{P}^{(e)}= I^{(e)} \underline{f}^{(e)} $$ Recall the axial Fd relationship: $$ \hat k^{(e)} q^{(e)} = P^{(e)} $$ where k is a 2x2 matrix, q is a 2x1 matrix, and P is a 2x1 matrix. $$ \hat k^{(e)} \underbrace{(\underline{T}^{(e)} \underline{d}^{(e)} )} = \underbrace{(\underline{T}^{(e)} \underline{f}^{(e)})} $$ $$ - \qquad \underline{q}^{(e)} \qquad \qquad \underline{P}^{(e)} $$ Goal: We want to have k (e) d (e)= f (e) so "move" T e from right side to the left side by pre multiplying equation by T (e)-1, the inverse of T (e). Unfortunately, T(e) is a rectangular matrix of the size 2x4 and cannot be inverted. Only square matricies can be inverted. To solve this issue, transpose T. Ans: $$ (\underline {T}^{(e)T} \underline {\hat k}^{(e)} \underline {T}^{(e)})\underline {d}^{(e)} = \underline {f}^{(e)} $$ $$ \underline{k}^{(e)} \underline{d}^{(e)} = \underline{f}^{(e)} $$ $$ \underline{k}^{(e)} = \underline{T}^{(e)T} \underline{\hat k}^{(e)} \underline{T}^{(e)} $$ where k is on p6.1, k hat is on 12-2, and T is on 12-5. Justification for (1): PVW see 10-1 for 1st applications of PVW, reduction of global FD relationship. $$ \underline {K}_{6x6} d_{6x1} = \underline{F}_{6x1} \rightarrow \underline{\bar K}_{2x2} \underline{\bar d}_{2x1} = \underline {\bar F}_{2x1} $$ Remember: Why not solve as follows? $$\underline {d} = \underline{K}^{-1} F$$ Used mathcad to try to solve K-1 and could not, due to singularity of K ., i.e. the determinant of K =0 and thus K is not invertible. Recall that you need to computer $$\begin{matrix} \frac{1}{detK} \end{matrix}$$ to find K -1. Why? For an unconstrained structure system, there are 3 possible rigid body mostion in 2-D (2 translational and 1 rotational). HW: Find the eigenvalues of K and make observations about the number of eigenvalues. Dyanmic eigenvalue problem K v = λ M  v  Where K is the stiffness matrix, M is the mass. Zero evaluation corresponds to zero stored elastic energy which means rigid body motion.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: User:Eml4500.f08.wiki1.schaet/hw3


text:
User talk:Lilia~enwikiversity

 Hello Lilia, and welcome to Wikiversity! If you need help, feel free to visit my talk page, or contact us and ask questions. After you leave a comment on a talk page, remember to sign and date; it helps everyone follow the threads of the discussion. The signature icon in the edit window makes it simple. To get started, you may

 * Take a guided tour and learn to edit.
 * Visit a (kind of) random random project.
 * Browse everything on Wikiversity, or visit a portal corresponding to your educational level: pre-school, primary, secondary, tertiary, non-formal education.
 * Find out about research activities on Wikiversity.

 * Read an introduction for teachers and find out how to write an educational resource for Wikiversity.
 * Give feedback about your initial observations
 * Discuss Wikiversity issues or ask questions at the colloquium.
 * Chat with other Wikiversitans on #wikiversity-en.

And don't forget to explore Wikiversity with the links to your left. Be bold to contribute and to experiment with the sandbox or your userpage, and see you around Wikiversity! --mikeu talk 16:10, 21 October 2008 (UTC)

Hi, the reason for not being able to upload yet is that you have just created a new account. It takes 4 days before that feature is available to you. Let us know if you have any problems after that, or if you have any questions about how to get started. --mikeu talk 16:10, 21 October 2008 (UTC)
 * Go to Special:upload after you have registered for 4 days, that is to say. Enjoy your time at wikiversity! --Hillgentleman | //\\ |Talk 12:50, 23 October 2008 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Lilia. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Lilia~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:36, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:14, 19 April 2015 (UTC)

title: User talk:Lilia~enwikiversity


text:
User:Eml4500.f08.wiki1.schaet/hw2

=Meeting 11 Lecture Notes (19 Sep 08)=

Element 1: k(e)d(e)=f(e)

\mathbf{k} ^{(1)} = \begin{bmatrix} (\frac{9}{16})        & (\frac{3\sqrt{3}}{16})    & (-\frac{9}{16})    & (-\frac{3\sqrt{3}}{16})  \\ (\frac{3\sqrt{3}}{16}) & (\frac{3}{16})   & (-\frac{3\sqrt{3}}{16})    & (-\frac{3}{16})  \\

(-\frac{9}{16})       & (-\frac{3\sqrt{3}}{16})    & (\frac{9}{16})    & (\frac{3\sqrt{3}}{16})  \\ (-\frac{3\sqrt{3}}{16})& (-\frac{3}{16})   & (\frac{3\sqrt{3}}{16})    & (\frac{3}{16}) \end{bmatrix} \begin{Bmatrix} 0 \\ 0 \\ 4.352 \\ 6.1271 \end{Bmatrix} = \begin{bmatrix} (-\frac{9}{16})   & (-\frac{3\sqrt{3}}{16})  \\ (-\frac{3\sqrt{3}}{16})   & (-\frac{3}{16})  \\ (\frac{9}{16})   & (\frac{3\sqrt{3}}{16})  \\ (\frac{3\sqrt{3}}{16})   & (\frac{3}{16}) \end{bmatrix}

\begin{Bmatrix} 4.352 \\ 6.1271 \end{Bmatrix} = \begin{Bmatrix} -4.4378 \\ -2.5622 \\ 4.4378 \\ 2.5622 \end{Bmatrix} = \begin{Bmatrix} f_1^{(1)} \\ f_2^{(1)} \\ f_3^{(1)} \\ f_4^{(1)} \end{Bmatrix} $$ where f1 and f2 are the reaction forces and f3 and f4 are the internal forces for element 1. Element 1 is in equilibrium so ΣFx=f1(1) + f3(1) = 0     (1) ΣFy=f2(1) + f4(1) = 0     (2)

Method 2: Statics for a 2-bar truss Use Euler Cut Method Back to FE solution. The question arises, how do you bring P back into the picture. Find the equilibrium at node 2. This is part of the homework.

P^{(1)} = [(f_1^{(1)})^2 + (f_2^{(1)})^2]^{\frac{1}{2}}$$

P^{(2)} = [(f_1^{(2)})^2 + (f_2^{(2)})^2]^{\frac{1}{2}}$$ Therefore,

P = [((f_1^{(1)})+ (f_1^{(2)}))^2 + ((f_2^{(1)}) + (f_2^{(2)}))^2]^{\frac{1}{2}} $$ Which equals our value for P. Therefore, node 2 is in equilibrium.

title: User:Eml4500.f08.wiki1.schaet/hw2


text:
User:Eml4500.f08.wiki1.schaet/hw1

=Matlab Tutorial Section 10-12=

Quick Summary
This section discusses the ease of editing commands using the arrow keys on the keyboard and recalling command lines in Matlab without having to write M-files (section 12).

Details
Editing commands is easy in Matlab. The cursor can be placed anywhere in the command line using the mouse, left/right arrow keys, and backspace. This simple method of editing does not exist in other programming languages such as Fortran. On the PC's that most of us use, the Home, End, and Delete keys can also be used to place the cursor to make revisions. Using the up/down arrow keys allows the user to scroll through past command lines. This allows the user to simply copy and paste a command they want to use again. Once pasted, the user can also alter the command line. This is very useful if you were using a long linear regression equation and only one constant or variable needed to be replaced.

Quick Summary
This section covers the use of colon notation for matricies. It also discusses subscripting by integral vectors. Both of these methods are used to easily manipulate complicated vectors and submatricies. Creative use of the colon notation discussed here can often eliminate the need for loops thus making the execution of MATLAB code faster.

Details
Vectors typically seen as [a b c d e f....n] can take on the notation of [a:n] in Matlab. Using this colon notation makes it easier and simpler to read and execute. One example of the use of this expression 1:5. This expands out to the row matrix [1 2 3 4 5]. When using this notation, the vector does not need to increment by just one either. Adding a middle term defines what level the vector should increment. For example, the expression 0.2:0.2:1.2 is the vector [0.2 0.4 0.6 0.8 1.0 1.2]. Another example is the expression 5:-1:1 gives [5 4 3 2 1].

The colon notation makes it easy to access submatricies as well as alter a given matrix. Below are some examples.

If A is a predefined matrix of arbitrary size n by n, the notation A(1:4,3) is the column vector consisting of the first four entries of the third column of A.

Using the colon by itself takes an entire row or column from a given matrix, in this case the matrix A. For example, the expression A(:,3) is the entire third column of A. The expression A(1:4,:) is the first four rows of A.

Creating new matricies using arbitrary integral vectors also proves useful in Matlab. The expression A(:,[2 4]) is a matrix whose two columns consist of column 2 and 4 of A. This method of manipulation can also be used in an assignment statement. One example of this is the expression A(:,[2 4 5]) = B(:,1:3) replaces columns 2, 4, and 5 of A with the first three columnds of B. Running this command prints and assigns the entire altered matrix A.

This notation also makes multiplying matricies easier. The expression A(:,[2,4]) = A(:,[2,4])*[1 2;3 4] multiplies the columns 2 and 4 in matrix A by the 2x2 matrix [1 2;3 4]. Running this command once again prints the entire altered matrix.

By comparison to other coding languages, using this notation makes adds to Matlab's usefulness when dealing with vectors and matricies.

Section 12 - M-files
M-files are MATLAB files with the ".m" file extension. These are usually created with a local editor, and contain a sequence of statements that can be executed. There are two types of M-files, script files and function files.

Script Files
A script file consists of a sequence of normal MATLAB statements. For example, if you create a script file called, then typing   into the command window will execute the statements that are in the script.

Note: Variables used in scripts are global and will interfere with any variables of the same name within the current MATLAB session.

Function Files
Function files allow you to create your own functions specific to what you are trying to do, and these will have the status as any other function within MATLAB. Function file variables are local by default, but can be set as global.

Example: function a = randint(m,n) %RANDINT Randomly generated integral matrix. %randint(m,n) returns an n-by-m matrix with integers between 0 and 9 a = floor(10*rand(m,n));

You would save this code as a diskfile with the name. Notice that the first line of code gives the name of the function, the input arguments, and output arguments; this line is the difference between a script file and a function file.

You would execute this function file by entering. This sends  and   to be sent as   and   respectively with the output result set as. Again, these variable are, by default, local variables.

The function are flexible in their use of inputs and outputs. The use of, ("number of input arguments") allows you to set a default value of an omitted input variable. A function may also have multiple output arguments.

To make comments, use '%' and the rest of the line is ignored by MATLAB. It is considered correct to include some beginning comment lines to describe the use of the function, and can displayed for example if  is entered. You should also try to write in efficient code, using vectorized operations and avoiding loops. If  loops must be used, you can make them faster by pre-allocating any vectors or matrices to which the output is stored.

Some MATLAB functions are built in while others are distributed as M-files. A listing of non-built-in functions can be seen with the MATLAB command  functionname.

title: User:Eml4500.f08.wiki1.schaet/hw1


text:
User:Stevenarntson/The Commons/Guerilla Art

Today in class, we'll look at public artworks by a variety of artists who don't ask permission. This doesn't necessarily mean the artwork is illegal. You don't have to ask anyone's permission, for instance, to walk to work while wearing a blue shirt, though that is undeniably public.

Busking

 * Joshua Bell
 * The Tuba Man

Politics

 * Reverend Billy
 * Damali Ayo
 * Clandestine Insurgent Rebel Clown Army (website)
 * Instant Grant Program

Repurposing

 * The Pixelator
 * The Splasher
 * Add Art

Pranks

 * Improv Everywhere
 * Biotic Baking Brigade gets Bill Gates

Graffiti

 * Fast Graffiti
 * Reverse Graffiti Project
 * Alexandre Orion
 * Graffiti.org
 * Seattle Street Art
 * Julian Beever
 * Arrested for chalk art.

Guerilla becomes Sanctioned

 * Park(ing) Spaces in Portland
 * The Monolith, placed in Seattle in 2001.
 * Ball and chain around the leg of SAM's Hammering Man

Other

 * Project for Public Spaces
 * mARK oWEns' "puddle poems"
 * Theo Janssen's Strandbeests
 * Seattle's Free Sheep Foundation.
 * A short excerpt of Seattle's legal code.
 * In class, we'll also watch this short movie: Thoth. Here is the performer's website.


text:
User:Tglaisyer

I live in Washington DC and I'm new to Wikiversity

title: User:Tglaisyer


text:
User:Bl4ckc4tz

I live in the UK and am new to Wikiversity

title: User:Bl4ckc4tz


text:
User talk:Bl4ckc4tz

Welcome to wiki versity. I'm new too but I'm going to pass your rinfor to User:Jtneill who might be able to introduce you to a striaghtforward project. Tglaisyer 16:45, 21 October 2008 (UTC)

 Hello Bl4ckc4tz, and welcome to Wikiversity! If you need help, feel free to visit my talk page, or contact us and ask questions. After you leave a comment on a talk page, remember to sign and date; it helps everyone follow the threads of the discussion. The signature icon in the edit window makes it simple. To get started, you may

 * Take a guided tour and learn to edit.
 * Visit a (kind of) random random project.
 * Browse everything on Wikiversity, or visit a portal corresponding to your educational level: pre-school, primary, secondary, tertiary, non-formal education.
 * Find out about research activities on Wikiversity.

 * Read an introduction for teachers and find out how to write an educational resource for Wikiversity.
 * Give feedback about your initial observations
 * Discuss Wikiversity issues or ask questions at the colloquium.
 * Chat with other Wikiversitans on #wikiversity-en.

And don't forget to explore Wikiversity with the links to your left. Be bold to contribute and to experiment with the sandbox or your userpage, and see you around Wikiversity! Jtneill - Talk - c 21:13, 21 October 2008 (UTC)

 Hi! My name is WikiversityJack. I am a pumpkin and a Wikiversity mascot. My aunt told me that fun + learning = Wikiversity. Let me know if I can help you out.

Hi, happy to help. What are your interests? -- Jtneill - Talk - c 21:13, 21 October 2008 (UTC)

title: User talk:Bl4ckc4tz


text:
User:Eas4200c.f08.aero.mcgilvray

Content to be added soon...

title: User:Eas4200c.f08.aero.mcgilvray


text: File:Cross Section View.jpg

title: File:Cross Section View.jpg


title: File:HW-4Picture1.jpg


title: File:HW-4Picture2.jpg


title: File:HW-4Picture3.jpg


title: File:HW-4Picture4.jpg


title: File:HW-4Picture5.jpg


title: File:HW-4Picture6.jpg


title: File:HW-4Picture7.jpg


text:
User:Jhinso35

Hey my name is Jennifer Hinson. My middle name is Samantha and that is what people call me. I am an Elem. Education major and concentrating in English and Communications. I am going to teach 3rd, 4th, or 5th grade. Hopefully, after some experience I will be able to go into adminsitration and ultimately become a principal one of these days. In my spare time I love to shop, eat, hang out with family, friends , and I love to sing. I am looking forward to doing this project because I think it will be interesting to see how people in other countries teach their students. I would like to know the similiarities and differences between our cultures when it comes to our topic of learning methods. If you have any other questions ask me ! I would love to talk!

title: User:Jhinso35


text: File:Euler Cut 2.JPG

title: File:Euler Cut 2.JPG


title: File:Diagram3HW4.jpg


title: File:Diagram4HW4.jpg


text:
User:Eas4200c.f08.wiki.b/HW4

=Mtg. 20 - Friday 10/10=

The engineering, or ad-hoc, derivation of the rate of twist of the following equation

 $$\displaystyle \theta = {1 \over 2G \bar A} \oint {q \over t} ds $$

applies to a uniform bar with a non-circular cross section.

The displacement of segment $$\displaystyle PP' $$ due to an angle $$\displaystyle \alpha $$ is defined as

 $$\displaystyle {PP' \over OP} = \tan \alpha $$

But for a small angle $$\displaystyle \alpha $$, the following approximation is appropriate:

 $$\displaystyle \tan \alpha \approx \alpha $$

Hence,

 $$\displaystyle {PP' \over OP} \approx \alpha $$

The projected displacement of $$\displaystyle PP' $$ in the direction perpendicular to $$\displaystyle OP' $$ can be written

 $$\displaystyle PP'' = PP' \cos \alpha $$

By substitution

 $$\displaystyle PP'' = (OP \tan \alpha) \cos \alpha $$

By the associative property of multiplication

 $$\displaystyle PP'' = (OP \cos \alpha) \tan \alpha $$

Recall that $$\displaystyle OP = r $$ and $$\displaystyle OP'' = \rho $$, thus we can express it as

 $$\displaystyle PP'' = (r \cos \alpha) \tan \alpha $$

Strain, $$\displaystyle \gamma $$ can be written as

 $$\displaystyle \gamma = {PP' \over dx} = {\rho \alpha \over dx} = \rho \theta $$

where, as previously stated, $$\displaystyle \theta $$ is the rate of twist.

title: User:Eas4200c.f08.wiki.b/HW4


text:
User talk:Tglaisyer

 Hello Tglaisyer, and welcome to Wikiversity! If you need help, feel free to visit my talk page, or contact us and ask questions. After you leave a comment on a talk page, remember to sign and date; it helps everyone follow the threads of the discussion. The signature icon in the edit window makes it simple. To get started, you may

 * Take a guided tour and learn to edit.
 * Visit a (kind of) random random project.
 * Browse everything on Wikiversity, or visit a portal corresponding to your educational level: pre-school, primary, secondary, tertiary, non-formal education.
 * Find out about research activities on Wikiversity.

 * Read an introduction for teachers and find out how to write an educational resource for Wikiversity.
 * Give feedback about your initial observations
 * Discuss Wikiversity issues or ask questions at the colloquium.
 * Chat with other Wikiversitans on #wikiversity-en.

And don't forget to explore Wikiversity with the links to your left. Be bold to contribute and to experiment with the sandbox or your userpage, and see you around Wikiversity! Jtneill - Talk - c 21:14, 21 October 2008 (UTC)

 Hi , I am Percy. Nice to meet you. I love the beach, swimming, fishing, and I am currently doing some research at Wikiversity on oceanography. I am also learning to play piano. What do you like? Can I be your mascot?

title: User talk:Tglaisyer


text:
User:Gaja

hu:User:Gaja

title: User:Gaja


text:
Electrical Engineering Fundamentals/Current Sources

An independent current source has a constant current that is completely independent of the voltage across the source. Like the independent voltage source the current source is at best a reasonable approximation for a physical element. It is a common mistake that students think the voltage across a current source is zero and that is false. There is a voltage across current sources. This voltage is, for an ideal current source, always equal to, the current output (amperes) times the load resistance (ohms).


text: File:FEA 19.1.jpg

title: File:FEA 19.1.jpg


text:
User:Jaredstein~enwikiversity

Jared M. Stein

Director of Instructional Design Services, Utah Valley University, USA

About Jared Stein

 * LinkedIn
 * Flexknowlogy - Jared Stein's blog on e-learning

title: User:Jaredstein~enwikiversity


text:
User:Eml4500.f08.team.guan/1013

10/13 Homework Assignment
Finding the Eigenvalues of a Three Bar Truss in a Square Configuration (Case A), and finding the eigenvalues of A Four Bar Truss in a Square Configuration with the Fourth Truss as a Diagonal Member (Case B). Plot the eigenvectors of Case A.

Matlab Code for Case A:

The below picture represents the plot produced by Matlab showing the Case A truss.

For this case, the code found the the global stiffness matrix resulted as follows. $$ K= \begin{bmatrix} 0 & 0 & 0 &  0 & 0 &  0 & 0 &  0\\ 0 &  6 & 0 &  -6 & 0 &  0 & 0 &  0\\ 0 &  0 & 6 &  0 & -6 &  0 & 0 &  0 \\ 0 &  -6 & 0 &  6 & 0 &  0 & 0 &  0\\ 0 &  0 & -6 &  0 & 6 &  0 & 0 &  0\\ 0 &  0 & 0 &  0 & 0 &  6 & 0 &  -6\\ 0 &  0 & 0 &  0 & 0 &  0 & 0 &  0\\ 0 &  0 & 0 &  0 & 0 &  -6 & 0 &  6\\ \end{bmatrix}

$$ This is a singular matrix meaning that the determinant is zero and thus it is not invertible. The eigenvalues are as follows. $$\lambda$$=[0,0,0,0,0,12,12,12].

Matlab Code for Case B:

The below picture represents the plot produced by Matlab showing the Case B truss.

For this case, the code found the the global stiffness matrix resulted as follows. $$ K= \begin{bmatrix} 2.1213  &    2.1213& 0&0 &     -2.1213&  -2.1213  &          0  &          0\\       2.1213 &      8.1213& 0     &      -6   &   -2.1213 & -2.1213   &         0   &         0\\ 0& 0      &    6&  0   &        -6    &     0   &         0 &           0\\ 0  &         -6&  0      &      6   &         0   &      0    &        0  &          0\\      -2.1213 &     -2.1213  &         -6  &          0    &   8.1213&    2.1213   &         0    &        0\\      -2.1213&      -2.1213    &        0  &          0   &    2.1213  &     8.1213  &          0  &         -6\\            0  &          0    &        0   &         0     &       0&         0   &         0    &        0\\            0   &         0     &       0     &       0      &      0    &       -6   &         0  &          6\\ \end{bmatrix}$$

This is also a singular matrix meaning that the determinant is zero and thus it is not invertible. The eigenvalues were as follows. $$\lambda $$=[0,0,0,0,3.8183,12,12,16.667].

title: User:Eml4500.f08.team.guan/1013


text: File:Caseajin.JPG

title: File:Caseajin.JPG


text: File:Casebjin.JPG

title: File:Casebjin.JPG


text:
User:Danieller~enwikiversity

My name is Danielle and I am currently a third year student at UNC-Charlotte. I enjoy shopping, sleeping, and going out with my friends. I decided to become a teacher because I believe that it is one of the most important jobs in the world. I love kids and I believe that great teachers influence their studnts long after they have left their classrooms and would love to become a positive influence to my students.

title: User:Danieller~enwikiversity


text:
Wikiversity talk:Respect people/Archive

What do you think?
What do you think of this proposal? Do you think it adequately addresses issues like attacking people and using people's names? --darklama 00:59, 20 September 2008 (UTC)

 * I like the wording. Very nice.  --mikeu talk 01:02, 20 September 2008 (UTC)
 * I thought so too. Emesee 01:05, 20 September 2008 (UTC)

 * I think there should be a more specific clause when discussing other wikimedia contributors, namely that if someone has not openly published their real name on the wikis, they should be referred to by their usernames. We've recently had problems with loopholing around that issue: quite a few wikimedians have had their names published off-site, but still do not want their names used on-site. It should be made clear that people should be addressed in the manner they choose to be addressed. --SB_Johnny talk 14:29, 20 September 2008 (UTC)

 * I'm a bit hesitant in this area. While I agree referring to people by their username is respectful when related to Wikiversity activities, I'm having trouble wrapping my head around what is disrespectful or wrong about using someone's real name in referring to activities elsewhere when they have openly made their real name available in a place where no reasonable expectation of privacy exists. I think when someone has disclosed their name someplace where no expectation of privacy exists, than it becomes fair to use in referring to their activities elsewhere. I think what is left than is using their real name responsibly and appropriately as it relates to Wikiversity's mission, mainly to discuss their activities or what they said, not for discussing what other people think of them as a human being. --dark[[Image:Yin yang.svg|12px]]lama 15:29, 20 September 2008 (UTC)
 * Or rather I mean when people have openly made the connections themselves in a place with no expectation of privacy, whether the connection is between there real name and username someplace, or some other connections. --dark[[Image:Yin yang.svg|12px]]lama 15:36, 20 September 2008 (UTC)
 * What exactly do you want to stop here? Are you suggesting that Wikiversity has an obligation to protect people's identities even when they have already disclosed this information themselves in a place with no expectation of privacy, or just people trying to expose other people's identities, when they have not done so in a place with no expectation of privacy? --dark[[Image:Yin yang.svg|12px]]lama 15:43, 20 September 2008 (UTC)

 * Its a great start. Perhaps have a section at the bottom for a list of specific things on what not to do? Ottava Rima (talk) 21:45, 20 September 2008 (UTC)

 * I'm glad this was started, so far it seems fine - if it becomes an official policy, guideline then that would be great. However I'm still concerned as to why this site haven't got a privacy policy yet since it was proposed in 2006 and it's now 2008. DarkMage  21:48, 20 September 2008 (UTC)

 * That is a good point, and we should probably get working on that at somepoint soon. Wikiversity actually does have an official privacy policy.  It applies to all wikimedia sites and can be found here.  The proposed Privacy policy would be in addition to the first one, not a replacement.  --mikeu talk 00:05, 22 September 2008 (UTC)

 * I believe telling people what not to do usually only encourages people to do them, possibly because no help was provided on what to do instead. I think if a list is necessary that it should try to focus on what to do instead. --dark[[Image:Yin yang.svg|12px]]lama 21:34, 21 September 2008 (UTC)
 * Haha, good point. There was an expression - "don't tell kids not to put marbles up their nose because they just will". Don't give ideas to people. :) Ottava Rima (talk) 23:24, 21 September 2008 (UTC)
 * Marbles? I thought it was beans. --mikeu talk 00:08, 22 September 2008 (UTC)

 * Actually, I think the current version is quite good. Kudos to darklama for his taciturn patience, understanding, and intuition. --SB_Johnny talk 21:46, 21 September 2008 (UTC)

My take
Well, that's my 2¢ for now. The Jade Knight (d'viser) 12:38, 22 September 2008 (UTC)
 * 1) I support Darklama's suggestions about information made public, with the proviso that personal requests concerning personal information will be respected, regardless of where it has been posted.
 * 2) When discussing individuals or people, discuss their accomplishments or things they have done, rather than what you think of them as human beings —I feel this needs context. Are we talking about public figures?  Contributors?  Are there any cases where it might be appropriate to discuss what you think of certain people as human beings (say, in Philosophy?)
 * 3) when legitimately published on Wikiversity by themselves —what is meant by "legitimately"?
 * 4) Be fair and responsible in your depictions of people —what is "fair and responsible"?
 * 5) allow other participants to reasonably balance your depictions with their own fair and responsible depictions of facts, opinions and theories —who is to determine what is fair and responsible, or when something is "reasonably balanced"? What should we do when a user wants to explore a project through a particular POV, and has disclosed said POV?
 * 6) be prepared to change your approach or what you've written if your sources update or retract information —(while certainly a good idea,) what does this have to do with respecting people? (And could there be circumstances where, given changing sources, a different approach may still not be necessary or appropriate?)
 * 7) Be careful to distinguish between what other people have said or done and your own interpretations —Yes, good, but something about the way it's worded bothers me.  "Be careful to distinguish fact from interpretation" would be more succinct, though it would almost certainly need explanation (not necessarily a bad thing, so long as explanation is provided)
 * 8) your peers may ask you to be civil, respectful and to change your approach —"peers" is too vague. I would use a more Wikiversity-relevant term.
 * 9) you might be disqualified from participating in any Wikiversity activities —eschew obfuscation. While this is terribly polite, a more terse expression may be in order ("you may get blocked")
 * 10) Finally, and relating to the last section, I think we need to include something about the concept of "consensus" here; a big part of respecting people is respecting consensus. However, I expect that initial drafts of consensus issues will be problematic in and of themselves.

 * I disagree with this mainly because it could be used to stop people from talking about things they've said or done, when it might be appropriate to do so.
 * Its talking about everyone, Wikiversity participants, public figures or anyone you write about. Everyone should be respected. Do you think that "This policy complements Wikiversity:Civility by addressing issues concerning respecting people (including both other Wikiversity participants and people you write about)" does not adequately put who is covered into context or did you miss that part? Using philosophy as an example, people could still write "John Doe's non-violent protest of X suggests his philosophy is ..." or "John Doe has said his philosophy is..."
 * When done by the person, and not someone impersonating them, pretending to be them, claiming to do it on their behalf, etc. I think this should be open to interpretation by the Wikiversity community.
 * What is fair and responsible should be up to community consensus or consensus of the people involved in a learning or research project.
 * The people working on the project determine what is fair and responsible, and reasonably balanced through consensus, or the Wikiversity community through consensus when or if its needed. This applies to disclosed POVs as well, which I think can still be reasonably balanced and people can still be fair and responsible in their depictions.
 * If you said "John Doe likes apple pie" based on a mistake source X made, which they than correct to say "John Doe likes pumpkin pie." or remove altogether because John Doe doesn't actually like pie, than an update might be needed on Wikiversity as well. This has to do with respecting what is said about people and getting facts straight, because even sources can make mistakes. Going back a little to your first issue, I think if people don't want personal information to be used that has already been made public than they need to get the sources that made the information public to retract it, than what's written on Wikiversity should follow suite. Changing approach might not be necessary if perhaps instead of saying "John Doe said...", "Gotham City Times quoted John Doe as saying..." and a way back machine link were used, though someone might feel compelled to mention this was later corrected or later discovered to be a mistake.
 * What bothers you about this? Not sure if a explanation would be necessary beyond that doing so respects people by clarifying what they actually did and what other people only think they did.
 * I've seen "peers" used in a Beta Wikiversity policy, I adopted the wording of the last sentence from a policy there.
 * Well it could say "or you may get blocked" too.
 * This proposal does intended to rely heavily on what consensus agrees it means. Would something like "When disagreements arises about what respecting people means, respect consensus. If you disrespect people, their privacy or consensus, your peers may ask you to be civil, respectful or to change your approach. If you continue to be disrespectful despite receiving sound advice from your peers to stop, you might be disqualified from participating in any Wikiversity activities or you may get blocked." satisfy you?
 * --dark[[Image:Yin yang.svg|12px]]lama 14:20, 22 September 2008 (UTC)

 * 1. But isn't that then failing to respect people?  Or is the policy "respect people, except for when they publish something"?
 * 2. What about Philosophy of Ethics, etc.?  Is it inappropriate to "judge" historical figures such as Hitler?
 * 3. I think it needs to be more explicit.
 * 4. Perhaps, but guidelines should be established here of what is generally considered "fair and reasonable"; people may have wildly differing opinions of what this means, and people will generally assume other people feel the way they do.
 * 5. If that is what is meant, then that is what the policy needs to say.  Be explicit.
 * 6. Wonderfully complicated in your approach, but I still fail to see how this is specific to respecting people.
 * 7. I find it awkwardly phrased and open to misunderstanding.  Thus I recommend a rephrase.
 * 8. I'm guessing the average user would find the use of "peers" more obfuscating than elucidating.
 * 9. I'm thinking policies should be written for the common denominator.
 * 10. If the policy is based on consensus, it needs to be particularly explicit about it.  Your example paragraph is an improvement, though it seems redundant to include both "disqualified from participating" and "get blocked".
 * The Jade Knight (d'viser) 14:01, 23 September 2008 (UTC)

 * I think respect is a two way street. Is it respectful to students trying to learn about a person and, what they've done or accomplished, when information that they are trying to learn and understand is removed? I think some sort of balance is needed between respecting the person whose being discussed and respecting people trying to learn from what's discussed. Maybe it is more like "respect people's wishes, except when doing so would disrespect people trying to learn from published information."
 * What do you mean? Isn't discussion about a person's ethics or philosophy done by studying or analyzing what a person has said or done? Aren't judgments like "Hitler was bad" unhelpful in learning or understanding why people think Hitler was bad, and what was right or wrong with Hitler's ethics or philosophy?
 * I think there are simply too many possibilities to cover to make it explicit. Can you think of a better way to say it that would be general and flexible enough, while also open to a consensus making process? IOW lets people judge on a case-by-case bases whether what was written can be used?
 * I think I'd rather the proposal was more explicit that fair and reasonable is going to depend on the consensus of the people working on a page.
 * I think we may agree here about making the proposal more explict on consensus drives what fair and reasonable means.
 * Part of respecting people is making sure that what you say about people is accurate and true to the best of your ability, so if the source of your information turn out to be wrong, it ought be corrected. I think it important to require people to fix their mistakes when they are aware of the mistakes. Sometimes correcting information requires a new approach if a lot depended on the inaccurate information.
 * How do you think it could be misunderstood? What do you think it could be understood to mean?
 * Would colleagues be any better?
 * An action other than a block might be possible, and some people seem to have problems with the word "block" and what it really means.
 * I have no problem with attempts to make this proposal more explicit about decisions being based on consensus.
 * --dark[[Image:Yin yang.svg|12px]]lama 21:39, 23 September 2008 (UTC)

 * That would be better… and for public figures, it's one thing, but for private private individuals (particularly those who contribute to Wikiversity), I think it's very important to show them respect when it comes to sensitive matters.
 * Not at all, actually, depending on the reason and method—it is quite common to discuss corruption and betrayal in terms of individuals in History, and in Philosophy in particular, it is not at all unreasonable to ask the question "Is this person ethical?" Granted, discussion will usually center around actions and beliefs, but the question, "Is this person ethical?" stands, and answering it directly (with explanation) would not likely be discouraged.
 * I think it is more likely to be misinterpreted or misapplied as stands. However, I think very few people in the community would hold someone liable for something they did not do; so it may be more effacacious to simply remove the word "legitimately" entirely from the sentence, and let it be assumed (as it almost certainly will be).
 * That would be great; it's more explicit, even if it is simply saying "accept consensus" instead of "be fair and reasonable"; there's lots of material on Wikimedia about what consensus is. There's nothing about what being "fair and reasonable" means.
 * Indeed.
 * Respecting people can include a great many elements, many of which can vary from individual to individual. Consider that much music is called "disrespectful" (for example).  Yes, according to some individuals, honesty is a very important part of respect.  According to other individuals, avoiding offense is a much more important part of respect than honesty—given, for example, that you are in a setting where your boss is wearing a new shirt recently purchased.  You think the thing is hideous, but when your boss asks you what you think of it, you may (dishonestly) say that it looks fine, etc., simply to be "respectful".  I think it's important to be honest and accurate, but that's simply a matter of good scholarship, and has nothing to do with being respectful.
 * I think the most likely misunderstanding to arise will be people who see it and interpret "what people have said or done" (emphasis added) to mean "other people's interpretations". In other words, someone might see the phrase, and think "okay, what I say and what they say is different.  Duh."  The matter is that, the phrase appears to be rhetorically emphasizing a distinction between "other people" and "your"self, when it wants to emphasize the distinction between fact and interpretation.
 * Colleagues would be somewhat better, but I think "other participants" would be better yet.
 * Oh? What ways, apart from a block, can one be disqualified from participating (I wasn't aware of them)?
 * The Jade Knight (d'viser) 13:04, 27 September 2008 (UTC)
 * Sounds like, with #4 proposed changes above, that you have to accept consensus even if it is unfair or irresponsible. Dzonatas 17:03, 27 September 2008 (UTC)
 * A logical impossibility, if consensus is the way what is fair and responsible is determined: Ie, if "what is fair and reasonable" is determined by consensus, then it is impossible for consensus to be "unfair or unreasonable".  Follow?  The Jade Knight (d'viser) 11:51, 28 September 2008 (UTC)
 * Then by consensus, my input is to say that, I not only disagree with that logic, I find it unfair and irresponsible because of the assumption that all paths of consensus is fair and responsible. A consensus does not substitute being fair and responsible in any way. A consensus can be fair, and it can be unfair. For example, it is quite easy for someone involved on content to get blocked right before a planned consensus is made, and that would be quite unfair. That is an obvious example, and it has happened. The logic you gave implies that it is ok to have different outcomes for every situation with similar factors. User A did X, Y, and Z, and user A gets blocked by consensus. User B did X, Y, and Z, and user B doesn't get blocked by consensus. That clearly demonstrates how it was an unequal outcome when a user does X, Y, and Z, and that can be seen as unfair or irresponsible by those who hold the consensus. Being fair and responsible is quite different from a consensus.
 * Sue Gardener mentions about being fair and responsible, and might help understand this better, "In general, the considerations for Wikinews reporters covering the Foundation are probably fairly similar for any journalist covering anybody: if they are responsible and fair, they'll earn the respect and cooperation of the people and organizations they cover, even if their work is challenging. If they behave irresponsibly, over time they will find that people refuse to cooperate with them." A little more about the back-story to that: there are some Wikinews members that apply journalism equally to any organization, even Wikinews itself. There were other Wikinews and WMF members that didn't like any criticism of Wikinews or WMF, and they edit warred or took admin action against those that journaled on Wikinews. At that point it was obvious there are members, Wikinews and WMF, that hold political agendas. This event also clearly reveals another point, and that is one can be completely honest in their political agenda, but that does not automatically qualify them to have acted in good-faith when they don't allow equality, like in journalistic coverage about themselves, their organization, or certain people. It was also made obvious that some tried to pass off WMF actions or admin actions as community consensus. When someone does not meet their obligations (i.e. wore the wrong hat), they did not act in good-faith.
 * What you want are these kind of obligations made explicit, not just replace "fair and responsible" with "consensus." There seemed to be an earlier attempt to list some of them: Colloquium. I believe it would be more wise to take the content as-is now on this proposed policy and separate each principle on its own page. That would avoid the implied concerns of an omnibus implementation and help prevent loopholes as noted in the earlier attempt, as it is noticed in this discussion (as noted in my comment). Dzonatas 16:41, 28 September 2008 (UTC)
 * I have no problem with trying to be more explicit or clearer in the intentions of this proposal. I think though there is only one principle being covered by this proposal and splitting it is not the answer. Like there are many aspects to civility, there are also many aspects to respecting people. --dark[[Image:Yin yang.svg|12px]]lama 16:55, 28 September 2008 (UTC)
 * There is one principal and several principles. Dzonatas 17:11, 28 September 2008 (UTC)
 * Sure, let's ignore consensus if it's not fair and responsible. But you force me to return to my first question, Dzonatas:  "4.  Be fair and responsible in your depictions of people —what is 'fair and responsible'?"  The Jade Knight (d'viser) 07:48, 29 September 2008 (UTC)

Some changes reflecting on "My take"
I've made some changes based on this discussion:
 * 1) I've revised the initial statement to say "Respect Wikiversity participants and anyone you write about, and their desire for dignity, autonomy and privacy" based on criticsm that it was not explicit enough, and some additions someone else had made.
 * 2) I've replaced uses of legitimately so that it now reads "Being respectful also means you must only divulge or disclose verifiable information after a notable, respected, responsible and sound public source has done so, or when verified publicly by themselves (such as on their Wikiversity user page)." I think this also makes it a bit more clearer what the context is.
 * 3) I've made "be prepared to change your approach..." more general so it now reads "Be prepared to adjust your approach when available information changes or when what the community considers acceptable changes". I think this makes it a bit clearer who decides.
 * 4) I've changed wording to say "being clear to distinguish between personal interpretations and facts". I hope this addresses your concerns about the wording
 * 5) I've replaced "peer" with Wikiversity participants.
 * 6) I've added how what "respect" and "fair, balanced and responsible" means is up to consensus when disagreements happen.
 * 7) I've gotten rid of the part about "what you think of them as human beings" instead saying "focusing mainly on what was said or done".

I am not sure if this settles all concerns, but I hope it least addresses most of them without adding new concerns. --darklama 17:56, 3 October 2008 (UTC)

 * Definitely seems like an improvement. I still think "blocked" should be thrown in there.  The Jade Knight (d'viser) 02:13, 4 October 2008 (UTC)

Is there consensus to make this an official Wikiversity policy?
'No consensus to make this an official policy at this time. Although there is general support (even from some who opposed) there are reservations that more time is needed to refine the wording of the policy. Lets have another round of discussion on the current revision, before opening another vote. --mikeu talk 17:34, 11 October 2008 (UTC)'

Is the [ current propose version] ready to become an officially enforceable policy? Please include agree, disagree or neutral before your response, and explain why you agree or disagree with the proposal, or why your neutral (such as specific wording that you want changed, how you think it should be phrased instead, and why you think the change is needed), so that the discussion part of building consensus can take place. Please also don't make any changes to the proposal beyond minor trivial changes while this consensus building discussion is going on. --darklama 13:08, 23 September 2008 (UTC)

If you have any specific suggestions for improvements please also comment in the section above. We'd like to get a dialogue going on what everyone would like to see. --mikeu talk 02:29, 22 September 2008 (UTC)

 * ✅ the current version looks good. --mikeu talk 00:10, 22 September 2008 (UTC)
 * I am in favour and support, and like what's developing, but I think this has been going too short a time without yet sufficiently wide consultation/contribution to be going to vote. In other words, even one more or two more weeks of further drafting will help to make it better and stronger. I would also like hear/see some devil's advocate points of view discussed - I daresay when this policy comes to actually be used, people will be looking hard then for its loopholes then; we may benefit from trying to find more of them now. -- Jtneill - Talk - c 00:15, 22 September 2008 (UTC)
 * Jtneill, I think the standing policy is quite good, and like any policy can and should be amended later when needed. It's also very low-key and "no-brainerish", so worth supporting in a "well, yeah! duh!" kind of way :-). --SB_Johnny talk 00:52, 22 September 2008 (UTC)
 * We're very interested in hearing suggestions on how to "make it better and stronger." The section above can be used to discuss improvements.  Everyone is encouraged to participate in that process.  --mikeu talk 12:41, 23 September 2008 (UTC)
 * -- a step in the right direction. --SB_Johnny talk 00:52, 22 September 2008 (UTC)
 * (disagree) - as per Jtneil. Emesee 01:03, 22 September 2008 (UTC)
 * . --HappyCamper 01:10, 22 September 2008 (UTC)
 * This page looks like a stopgap for the recent problems, and, rather than a policy, a guideline for applying existing policies on civility and privicy, NPOV and scholar ethics. It would be more beneficial for wikiversity in the long term to consider more deeply on these specific policies. If it is felt that such a stopgap is necessary, it is useful to cite the specific problems, and a time limit should be introduced for it, so that it will expire or it is subjected to review by the end of the year, for instance. Hillgentleman|Talk 01:19, 22 September 2008 (UTC)
 * I actually think it would be nice to reassess all policies and related guidelines once per year... I wonder if we couldn't divide them into 12 related groups to keep that organized. --SB_Johnny talk 13:26, 22 September 2008 (UTC)
 * Great idea. The Jade Knight (d'viser) 14:02, 23 September 2008 (UTC)
 * ✅ I've been called a "troll" and a "harassment enabler" and other bad stuff, but I have no problem with this proposed policy as written. Dtobias 02:41, 22 September 2008 (UTC)
 * I'm not sure, part of me is wanting to support or oppose due to reading the discussions above - so I'm at the moment staying neutral in the matter. DarkMage  10:07, 22 September 2008 (UTC)
 * , per Jtneil; I support the policy in concept, but I feel that it still needs to be hammered out; I have concerns… (will post above) The Jade Knight (d'viser) 12:24, 22 September 2008 (UTC)
 * after changes. The Jade Knight (d'viser) 02:25, 4 October 2008 (UTC)
 * : I presume from the above comments that the important issue is to avoid an omnibus implementation. Dzonatas 16:22, 22 September 2008 (UTC) Too many changes have been made since this vote was started (see diff). While it may be something boldly not well featured in this software to handle these kinds of votes and changes, with the current implementation the ability to change a voted on version lacks respect to those that have voted. It doesn't matter if the person still agrees or disagrees about changes made after their vote, as there is no acknowledgment from those previous voters to the others voters if their vote is still valid. The section started with a specific version, but it is obvious by some votes casted here they they reflect later changes. Perhaps, when a person casts their vote, they should acknowledge it with the version beside their signature. Dzonatas 19:27, 9 October 2008 (UTC)
 * - unenforceable and unnecessary stopgap measure. Countrymike 22:44, 22 September 2008 (UTC)
 * ✅ - Seems like a reasonable policy. MBisanz 13:23, 25 September 2008 (UTC)

Merge into Civility
Can't this be merged into Civility? The concept of respecting other users seems to fit perfectly into the scope of that policy. Instead of having multiple pages which cover similar areas, it would be better if this was all in one place rather than scattered around. Adambro 18:27, 22 September 2008 (UTC)
 * You're probably right. The Jade Knight (d'viser) 14:03, 23 September 2008 (UTC)
 * I would accept this as an important sub policy of Civility, and possibly given a section on the Civility page (if it isn't given its own page). Ottava Rima (talk) 19:21, 23 September 2008 (UTC)
 * I think Hillgentleman sort of got it right when he referred to this proposal as applying existing policies. I think though rather than applying existing policies, this proposal ties the concepts of civility, privacy, NPOV and ethics together, creating a new concept and applying them in new ways. Like how two or more concepts can be used together to make new concepts. I don't think this proposal is specifically about civility, even though civility and respect tend to go hand-in-hand and are related, there still separate concepts. --dark[[Image:Yin yang.svg|12px]]lama 20:43, 23 September 2008 (UTC)

Suggested changes
Please read and comment on these suggested changes. I have undone them for now, because of the template on the page that requests that "When editing this page, please ensure that your revision reflects consensus on the discussion page." Please refrain from making major changes to this while a vote is in progress. It is important that everyone be voting on the same revision of the proposed policy in order to gauge consensus. --mikeu talk 15:51, 3 October 2008 (UTC)

 * The Respect people page has been protected from editing by unconfirmed users for 3 days to prevent changes to the policy while there is an ongoing vote on the current revision. Please comment on the these suggested changes in  in this section of the talk page for consideration of inclusion in the main page after the vote.  --mikeu talk 16:29, 3 October 2008 (UTC)

 * Where's the ongoing vote? The Jade Knight (d'viser) 02:20, 4 October 2008 (UTC)

 * Oppose those changes; rhetoric like that isn't helpful here. The Jade Knight (d'viser) 02:18, 4 October 2008 (UTC)

 * Case in point. Strongly oppose changes for reasons mentioned.  The Jade Knight (d'viser) 03:48, 4 October 2008 (UTC)
 * It is if the individual in question has been deemed by their fellow scholars to have shown continued disrespect to the point where they are considered disruptive to the community—that would be, in fact, simply upholding the policy of showing respect. The Jade Knight (d'viser) 06:23, 4 October 2008 (UTC)

_____________
 * Here is a proposed revision that needs to be discussed...

Close vote?
Is it time to close this vote, and then perhaps free this policy up for some more editing? -- Jtneill - Talk - c 16:01, 11 October 2008 (UTC)
 * Hold a new consensus for version #350064 the new version? Dzonatas 16:54, 11 October 2008 (UTC)
 * I agree that we should close this round of voting, since there have been too many changes to consider the earlier votes to still be valid for the current revision. --mikeu talk 17:23, 11 October 2008 (UTC)
 * Agreed. The Jade Knight (d'viser) 02:50, 12 October 2008 (UTC)

title: Wikiversity talk:Respect people/Archive


text:
User:EAS4200c.f08.Blue.E

go to discussion

title: User:EAS4200c.f08.Blue.E


text:
User:Eml4500.f08.Lulz.Layton.Eric/Hw4

 Comment: This page is the updated version of Homework 4 for Team Lulz. The major changes from the on-time version submitted 20:59, 24 October 2008 were the additions of Sections 2 and 3 of the updated version and edits to Section 4. Changes in Section 4 include linking to Homework 2 for the 3 required MATLAB functions provided by the textbook, addition of the output from the ThreeBarTrussEx.m, and an updated MATLAB image of the Deformed and Undeformed Three-bar Truss.

The page comparing the on-time version and the updated version can be found here.

Eric Layton - Eml4500.f08.Lulz.Layton.Eric 08:13, 3 November 2008 (UTC)

Array Definitions
Consider the connectivity array "conn" for the two-bar truss system shown in Figure 1:

$$ \mathbf{conn} = \begin{bmatrix} 1 & 2\\ 2 & 3 \end{bmatrix} $$

The connectivity array describes the local nodes of a truss element in terms of the global node numbering convention. The rows correspond to individual truss elements, and the columns to local nodes 1 and 2 of those elements. In other words, conn(e,j) refers to the global node number of local node j for element e.

A related concept is the location master matrix lmm:

$$ \mathbf{lmm} = \begin{bmatrix} 1 & 2 & 3 & 4\\ 3 & 4 & 5 & 6 \end{bmatrix} $$

The location master matrix describes the local degrees of freedom for a truss element in terms of the global degrees of freedom. Like with the connectivity array, the rows correspond to individual truss elements, and the columns refer to local degrees of freedom 1-4 for those elements. In other words, lmm(i,j) refers to the global degree of freedom of local degree of freedom j of element i.

Transformation Matrix
A previous discussion centered on the inability to invert the transformation matrix $$\mathbf{T^{(e)}}$$ used in the axial displacement relationship $$\mathbf{q^{(e)}} = \mathbf{T^{(e)}}\cdot\mathbf{d^{(e)}}$$. Our goal is to convert the 2x4 transformation matrix into a 4x4 matrix $$\mathbf{\tilde{T}^{(e)}}$$ that can be easily inverted.

Figure 2 shows a general diagram of axial/transvere displacements $$\tilde{d}^{(e)}_{j}$$ on a truss element e. The relationship describing this case is $$\mathbf{\tilde{d}^{(e)}} = \mathbf{\tilde{T}^{(e)}}\cdot\mathbf{d^{(e)}}$$.

Through the same geometric process used to determine $$\mathbf{q^{(e)}}$$ in a previous homework, it can be shown that the two expressions below are true:

$$\tilde{d}^{(e)}_{1} = \begin{bmatrix} l^{(e)}&m^{(e)} \end{bmatrix}\begin{Bmatrix} d^{(e)}_{1}\\ d^{(e)}_{2} \end{Bmatrix}$$

$$\tilde{d}^{(e)}_{2} = \begin{bmatrix} -m^{(e)}&l^{(e)} \end{bmatrix}\begin{Bmatrix} d^{(e)}_{1}\\ d^{(e)}_{2} \end{Bmatrix}$$

Combining these two expressions yields the following relationship for the axial/transverse displacements at one local node:

$$\begin{Bmatrix} \tilde{d}^{(e)}_{1}\\\tilde{d}^{(e)}_{2}\end{Bmatrix} = \begin{bmatrix} l^{(e)}&m^{(e)}\\-m^{(e)}&l^{(e)}\end{bmatrix}\begin{Bmatrix} d^{(e)}_{1}\\ d^{(e)}_{2} \end{Bmatrix}$$

This describes a new displacement relationship given by $$\mathbf{\tilde{d}^{(e)}} = \mathbf{R^{(e)}}\cdot\mathbf{d^{(e)}}$$. Extending this to include both local nodes of a truss element yields:

$$\begin{Bmatrix} \tilde{d}^{(e)}_{1}\\\tilde{d}^{(e)}_{2}\\\tilde{d}^{(e)}_{3}\\\tilde{d}^{(e)}_{4}\end{Bmatrix} = \begin{bmatrix} l^{(e)}&m^{(e)}&0&0\\-m^{(e)}&l^{(e)}&0&0\\0&0&l^{(e)}&m^{(e)}\\0&0&-m^{(e)}&l^{(e)}\end{bmatrix}\begin{Bmatrix} d^{(e)}_{1}\\ d^{(e)}_{2}\\d^{(e)}_{3}\\ d^{(e)}_{4} \end{Bmatrix} = \begin{bmatrix} \mathbf{R^{(e)}}&\mathbf{0}\\\mathbf{0}&\mathbf{R^{(e)}}\end{bmatrix}\begin{Bmatrix} d^{(e)}_{1}\\ d^{(e)}_{2}\\d^{(e)}_{3}\\ d^{(e)}_{4} \end{Bmatrix}$$

Figure 3 shows the axial/transverse forces for a truss element. The axial/transverse force-displacement relationship is given by $$\mathbf{\tilde{f}^{(e)}} = \mathbf{\tilde{k}^{(e)}}\cdot\mathbf{\tilde{d^{(e)}}}$$. The modified element stiffness matrix $$\mathbf{\tilde{k}^{(e)}}$$is defined below:

$$\mathbf{\tilde{k}^{(e)}} = k^{(e)}\begin{bmatrix} 1&0&-1&0\\0&0&0&0\\-1&0&1&0\\0&0&0&0\end{bmatrix}$$

Consider the case where $$\tilde{d}^{(e)}_{1} = \tilde{d}^{(e)}_{2} = \tilde{d}^{(e)}_{3}= 0$$, but $$\tilde{d}^{(e)}_{4}\neq 0$$. Because the 4th column of matrix $$\mathbf{\tilde{k}^{(e)}}$$ (corresponding to transverse displacement $$\tilde{d}^{(e)}_{4}$$) is a vector of zeros, the following is true:

$$\mathbf{\tilde{f}^{(e)}} = 0$$.

This is the interpretation of transverse degrees of freedom.

Finally, we have determined that $$\mathbf{\tilde{d}^{(e)}} = \mathbf{\tilde{T}^{(e)}}\cdot\mathbf{d^{(e)}}$$ is valid. A corresponding relationship can be defined for the axial/transverse forces:

$$\mathbf{\tilde{f}^{(e)}} = \mathbf{\tilde{T}^{(e)}}\cdot\mathbf{f^{(e)}}$$

We also know that $$\mathbf{\tilde{f}^{(e)}} = \mathbf{\tilde{k}^{(e)}}\cdot\mathbf{\tilde{d^{(e)}}}$$ is valid, leading to the following logic:

$$\mathbf{\tilde{f}^{(e)}} = \mathbf{\tilde{k}^{(e)}}\cdot\mathbf{\tilde{d^{(e)}}}$$

$$\mathbf{\tilde{T}^{(e)}}\cdot \mathbf{f^{(e)}} = \mathbf{\tilde{k}^{(e)}}\cdot \mathbf{\tilde{T}^{(e)}}\cdot \mathbf{d^{(e)}}$$

Assuming that $$\mathbf{\tilde{T}^{(e)}}$$ is an invertible matrix, the following is true:

$$[\mathbf{\tilde{T}^{(e)^{-1}}}\cdot\mathbf{\tilde{k}^{(e)}}\cdot\mathbf{\tilde{T}^{(e)}}]\mathbf{d^{(e)}} = \mathbf{f^{(e)}}$$

Inversion of Diagonal Matrices
Consider a general $$n\;x\;n$$ block diagonal matrix $$\mathbf{A}$$:

In order to explore the inverse, first consider an example matrix $$\mathbf{B}$$:

This matrix can alternately be described using the following notation for diagonal matrices:

$$\mathbf{B} = Diag[d_{11},d_{22},...,d_{nn}]$$

If $$d_{ii} \neq 0$$ for $$i\,=\,1,...,n$$, the inverse of this matrix can be expressed as $$\mathbf{B^{-1}} = Diag[\frac{1}{d_{11}},\frac{1}{d_{22}},...,\frac{1}{d_{nn}}]$$. Applying this procedure to $$\mathbf{A}$$ yields the following:

$$\mathbf{A} = Diag[\mathbf{D_{1}},\mathbf{D_{2}},...,\mathbf{D_{n}}]$$

$$\mathbf{A^{-1}} = Diag[\mathbf{D_{1}^{-1}},\mathbf{D_{2}^{-1}},...,\mathbf{D_{n}^{-1}}]$$

Transformation Matrix Continued
Returning to the modified transformation matrix $$\mathbf{\tilde{T}^{(e)}}$$ and applying the inversion methods discussed above, the matrix $$\mathbf{\tilde{T}^{(e)^{-1}}}$$ can be written as follows:

$$\mathbf{\tilde{T}^{(e)^{-1}}} = Diag[\mathbf{R^{(e)^{-1}}},\mathbf{R^{(e)^{-1}}}]$$, where $$\mathbf{R^{(e)}} = \begin{bmatrix} l^{(e)}&-m^{(e)}\\m^{(e)}&l^{(e)}\end{bmatrix}$$

Additionally, the transpose of matrix $$\mathbf{R^{(e)}}$$ is $$\begin{bmatrix} l^{(e)}&m^{(e)}\\-m^{(e)}&l^{(e)}\end{bmatrix}$$, leading to the following relation:

$$\mathbf{R^{(e)^{T}}}\cdot\mathbf{R^{(e)}} = \begin{bmatrix} l^{(e)}&m^{(e)}\\-m^{(e)}&l^{(e)}\end{bmatrix}\cdot \begin{bmatrix} l^{(e)}&-m^{(e)}\\m^{(e)}&l^{(e)}\end{bmatrix} = \begin{bmatrix} l^{(e)^{2}}+ m^{(e)^{2}}&0\\0&m^{(e)^{2}}+l^{(e)^{2}}\end{bmatrix}$$

Recalling that $$l^{(e)} = \cos{\mathbf{\theta}^{(e)}}$$ and $$m^{(e)} = \sin{\mathbf{\theta}^{(e)}}$$, and the trigonometric identity $$\cos{^{2}\mathbf{\theta}} + \sin{^{2}\mathbf{\theta}} = 1$$, the following is true:

$$\mathbf{R^{(e)^{T}}}\cdot\mathbf{R^{(e)}} = \begin{bmatrix} 1&0\\0&1\end{bmatrix} = \mathbf{I}$$, where $$\mathbf{I}$$ is the 2 x 2 identity matrix.

Since it is a known property that the product of a matrix and it's inverse (e.g. $$\mathbf{M}\cdot\mathbf{M^{-1}} = \mathbf{I}$$), it is apparent that $$\mathbf{R^{(e)^{T}}} = \mathbf{R^{(e)^{-1}}}$$. Thus,

$$\mathbf{\tilde{T}^{(e)^{-1}}} = Diag[\mathbf{R^{(e)^{-1}}},\mathbf{R^{(e)^{-1}}}] = Diag[\mathbf{R^{(e)^{T}}},\mathbf{R^{(e)^{T}}}] = (Diag[\mathbf{R^{(e)}},\mathbf{R^{(e)}}])^{T} = \mathbf{\tilde{T}^{(e)^{T}}}$$

The expression for the modified force-displacement relationship derived earlier can now be rewritten as:

$$[\mathbf{\tilde{T}^{(e)^{T}}}\cdot\mathbf{\tilde{k}^{(e)}}\cdot\mathbf{\tilde{T}^{(e)}}]\mathbf{d^{(e)}} = \mathbf{f^{(e)}}$$

Not only is the expression inside the brackets easily determined, it also resembles the form of the general force-displacement relationship, and the following can be shown:

$$\mathbf{k^{(e)}} = [\mathbf{\tilde{T}^{(e)^{T}}}\cdot\mathbf{\tilde{k}^{(e)}}\cdot\mathbf{\tilde{T}^{(e)}}]$$

Discussion of Eigenvalues and Eigenvectors
Consider the eigenvalue problem $$\mathbf{kv} = \mathbf{\lambda v}$$. Let $$[\mathbf{u_{1}},\mathbf{u_{2}},\mathbf{u_{3}},\mathbf{u_{4}}]$$ be the eigenvectors for the 4 zero eigenvalues:

$$\mathbf{ku_{i}} = 0\cdot\mathbf{u_{i}} = \mathbf{0}$$, for i = [1,2,3,4].

A linear combination of {$$\mathbf{u_{i}}$$} can be defined as $$\sum_{i=1}^{4} \alpha_{i}\mathbf{u_{i}} = \mathbf{W}$$, where $$\alpha_{i}\;$$ refers to real number constants.

The vector $$\mathbf{W}$$ is also an eigenvector corresponding a zero eigenvalue, as shown below:

$$\mathbf{kW} = \mathbf{k}(\sum_{i=1}^{4} \alpha_{i}\mathbf{u_{i}}) = \sum_{i=1}^{4} \alpha_{i}\mathbf{ku_{i}} = \mathbf{0}$$

Justification of Assembly of Element Stiffness Matrices into Global Stiffness Matrix
Recalling the force displacement global relationship of $$ \mathbf{k_{4x4}^{(e)}} \mathbf{d_{4x1}^{(e)}} = \mathbf{f_{4x1}^{(e)}} $$, the equilibrium of global node 2 can be found. The equilibrium of global node 2 will found using the Euler Cut principle, using free body diagrams of element 1 and element 2, and identifying the global dofs to the element dofs for both element 1 and 2.

Figure 4 shows the generic two-bar truss system, with global node 2 isolated for analysis. Two equations are immediately evident from the diagram:

$$(1)\;\Sigma F_{x} = -f_{3}^{(1)} - f_{1}^{(2)} = 0$$

$$(2)\;\Sigma F_{y} = \mathbf{P} - f_{4}^{(1)} - f_{2}^{(2)} = 0$$

Equation 2 can also be written as $$\mathbf{P} = f_{4}^{(1)} + f_{2}^{(2)}$$ Using the general force-displacement relationship $$\mathbf{k^{(e)}}\cdot\mathbf{d^{(e)}}= \mathbf{f^{(e)}}$$, Equation 1 can be rewritten as follows:

$$0 = [k_{31}^{(1)}d_{1}^{(1)} + k_{32}^{(1)}d_{2}^{(1)} + k_{32}^{(1)}d_{3}^{(1)} + k_{34}^{(1)}d_{4}^{(1)}] + [k_{11}^{(2)}d_{1}^{(2)} + k_{12}^{(2)}d_{2}^{(2)} + k_{13}^{(2)}d_{3}^{(2)} + k_{14}^{(2)}d_{4}^{(2)}]$$

Replacing the local displacement degrees of freedom with the global degrees of freedom produces the following:

$$0 = [k_{31}^{(1)}d_{1} + k_{32}^{(1)}d_{2} + k_{32}^{(1)}d_{3} + k_{34}^{(1)}d_{4}] + [k_{11}^{(2)}d_{3} + k_{12}^{(2)}d_{4} + k_{13}^{(2)}d_{5} + k_{14}^{(2)}d_{6}]$$

Comparison of the above with the third row of $$\mathbf{K}$$ as described in Meeting 8 shows that the two are identical.

An expression for the assembly of $$ned\;x\;ned$$ element stiffness matrices $$\mathbf{k^{(e)}}$$ for $$e\;=\; 1,...,nel$$, where $$nel$$ refers to the number of elements, into the $$n\;x\;n$$ global stiffness matrix $$\mathbf{K}$$ can be expressed as follows:

$$ \mathbf{K} = \begin{matrix} nel\\A\\e=1\end{matrix}\mathbf{k^{(e)}}$$

$$n\;$$ is the number of global degrees of freedom before the application of boundary conditions. $$ned\;$$ is the number of element degrees of freedom. $$ned\;$$ must be less than $$n\;$$. $$A\;$$ is a symbol representing the operation of assembly.

Principle of Virtual Work (PVW)
PVW was previously used as the validation for elimination of rows in the global stiffness matrix that corresponded to zero-valued boundary conditions to produce $$\mathbf{\bar{k}}$$. It was also used to derive $$\mathbf{q^{(e)}} = \mathbf{T^{(e)}} \cdot \mathbf{d^{(e)}}$$, the axial displacement relationship, and also $$\mathbf{k^{(e)}} = \mathbf{T^{(e)^{T}}} \cdot \mathbf{\hat{k}^{(e)}} \cdot \mathbf{T^{(e)}}$$, the alternate expression for the element stiffness matrix based on the transformation matrix.

Deriving FEM for PDEs
The force-displacement relationship for a bar of spring is given by $$\mathbf{kd}=\mathbf{F}$$. This relationship implies the following:

$$(3)\;\mathbf{kd} - \mathbf{F} = 0$$

An equivalent expression to Equation 3 is also implied:

$$(4)\;\mathbf{W}(\mathbf{kd} - \mathbf{F}) = 0$$ for all $$\mathbf{W}$$.

Proof:

$$(3)\leftrightarrow(4)$$ -  trivial $$(4)\leftrightarrow(3)$$ -  NOT TRIVIAL

Since $$(4)\;$$ is valid for all $$\mathbf{W}$$ selecting $$\mathbf{W}\,=\,1$$ is an acceptable operation.

$$(4)\;$$ then becomes $$\mathbf{kd} - \mathbf{F} = 0$$, which is the same as $$(3)\;$$.

Prove $$\mathbf{\tilde{f}^{(e)}}=\mathbf{\tilde{T}^{(e)}{f}^{(e)}}$$
$$\mathbf{\tilde{f}^{(e)}}=\mathbf{\tilde{T}^{(e)}{f}^{(e)}}$$

$$\mathbf{\tilde{T}^{(e)}}=\begin{bmatrix} l^{(e)} & -m^{(e)} & 0 & 0\\ m^{(e)} & l^{(e)} & 0 & 0\\ 0 & 0 & l^{(e)} & -m^{(e)}\\ 0 & 0 & m^{(e)} & l^{(e)} \end{bmatrix}$$

Since we know that $$l^{(e)} = cos(\theta)^{(e)}$$, $$m^{(e)} = sin(\theta)^{(e)}$$, and that the angle is 30 degrees, we can substitute values and compare the transformed matrix output to the values previously calculated. Confirmation will prove the relation.

$$\mathbf{\tilde{T}^{(1)}}=\begin{bmatrix} \sqrt{3}/2 & -0.5 & 0 & 0\\ 0.5 & \sqrt{3}/2 & 0 & 0\\ 0 & 0 & \sqrt{3}/2 & -0.5\\ 0 & 0 & 0.5 & \sqrt{3}/2 \end{bmatrix}$$

$$\mathbf{\tilde{T}^{(1)}f^{(1)}}=\begin{bmatrix} \sqrt{3}/2 & -0.5 & 0 & 0\\ 0.5 & \sqrt{3}/2 & 0 & 0\\ 0 & 0 & \sqrt{3}/2 & -0.5\\ 0 & 0 & 0.5 & \sqrt{3}/2 \end{bmatrix}\begin{bmatrix} -4.378\\ -2.5622\\ 4.4378\\ 2.5622 \end{bmatrix}=\mathbf{\tilde{f}^{(1)}}$$

$$\mathbf{\tilde{f}^{(1)}}=\begin{bmatrix} -5.1243\\ 0\\ 5.1243\\ 0 \end{bmatrix}$$

This confirms as expected and thus the proof is confirmed.

Prove that $$ \mathbf k^{(e)} = \tilde \mathbf T^{(e)^{T}}\tilde \mathbf k^{(e)}\tilde \mathbf T^{(e)}$$
$$ \mathbf k^{(e)} = \tilde \mathbf T^{(e)^{T}}\tilde \mathbf k^{(e)}\tilde \mathbf T^{(e)}$$

We already know the values from previous work for $$\mathbf{k^{(e)}}$$, $$\mathbf{\tilde{k}^{(e)}}$$, $$\mathbf{\tilde{T}^{(e)}}$$, and $$\mathbf{\tilde{T}^{(e)^T}}$$ is trivial to find:

$$ \mathbf{\tilde{T}^{(e)^T}} = \begin{bmatrix} l^{(e)} & m^{(e)} & 0 & 0\\ -m^{(e)} & l^{(e)} & 0 & 0\\ 0 & 0 & l^{(e)} & m^{(e)}\\ 0 & 0 & -m^{(e)} & l^{(e)} \end{bmatrix}$$

$$\mathbf k^{(e)} = \tilde \mathbf T^{(e)^{T}}\tilde \mathbf k^{(e)}\tilde \mathbf T^{(e)}$$

$$\mathbf k^{(e)} = k^{(e)}\begin{bmatrix} l^{(e)} & -m^{(e)} & 0 & 0\\ m^{(e)} & l^{(e)} & 0 & 0\\ 0 & 0 & l^{(e)} & -m^{(e)}\\ 0 & 0 & m^{(e)} & l^{(e)} \end{bmatrix}\begin{bmatrix} 1 & 0 & -1 & 0\\ 0 & 0 & 0 & 0\\ -1 & 0 & 1 & 0\\ 0 & 0 & 0 & 0\end{bmatrix}\begin{bmatrix} l^{(e)} & m^{(e)} & 0 & 0\\ -m^{(e)} & l^{(e)} & 0 & 0\\ 0 & 0 & l^{(e)} & m^{(e)}\\ 0 & 0 & -m^{(e)} & l^{(e)}\end{bmatrix} = \begin{bmatrix} (l^{(e)})^{2} & l^{(e)}m^{(e)}  &  -(l^{(e)})^{2}  &  -l^{(e)}m^{(e)}   \\ l^{(e)}m^{(e)} &  (m^{(e)})^{2}  &  -l^{(e)}m^{(e)}  &  -(m^{(e)})^{2}   \\ -(l^{(e)})^{2} & -l^{(e)}m^{(e)}  &  (l^{(e)})^{2}  &  l^{(e)}m^{(e)} \\ -l^{(e)}m^{(e)} &  -(m^{(e)})^{2}  &  l^{(e)}m^{(e)}  &  (m^{(e)})^{2} \\ \end{bmatrix} = \mathbf k^{(e)}$$

MATLAB Code: Five-bar and Three-bar Trusses
The first part of the required MATLAB code constructs and loads a truss system composed of five bars. The code below represents Example 1.4 (FiveBarTrussEx.m) on page 25 of the textbook. The first part defines the specifications of each bar and node including modulus of elasticity (e), cross-sectional area (a), and loading values (P). The "nodes" matrix defines the absolute locations of the four nodes. The "conn" matrix defines the global node numbers at the ends of each bar or element. Each row represents an element and nodes are numbered by the lowest first. As shown in the code, there are 5 sets of 2 numbers for the 2 nodes corresponding to each element. The "lmm" matrix represents the global degrees of freedom (dof) for each element. Each node has 2 dof's; therefore, each element has 4 corresponding dof's. Degrees of freedom are numbered from 1 to 2*(number of nodes) where the first 2 correspond to Global Node 1, the second 2 correspond to the Global Node 2, etc. From all this data, the global stiffness matrix (K) is created. The displacement of the loaded node is calculated using the relevant parts of the global stiffness matrix, inverting them, and multiplying by the load array (R). Finally, the reactions (reactions) at each node are calculated by multiplying the displacement array (d) by the global stiffness matrix. The functions "PlaneTrussElement.m", "NodalSoln.m", and "PlaneTrussResults.m" are used again from Section 6 of Homework 2.

FiveBarTrussEx.m
% Five bar truss example e1=200*10^3; e2=70*10^3; a1=40*100; a2=30*100; a3=20*100; P = 150*10^3; nodes = 1000*[0, 0; 1.5, 3.5; 0, 5; 5, 5]; conn = [1,2; 2,4; 1,3; 3,4; 2,3]; lmm = [1,2,3,4; 3, 4, 7, 8; 1, 2, 5, 6; 5, 6, 7, 8; 3, 4, 5, 6]; K=zeros(8); % Generate stiffness matrix for each element and assemble it. for i=1:2 lm=lmm(i,:); con=conn(i,:); k=PlaneTrussElement(e1, a1, nodes(con,:)); K(lm, lm) = K(lm, lm) + k; end for i=3:4 lm=lmm(i,:); con=conn(i,:); k=PlaneTrussElement(e1, a2, nodes(con,:)); K(lm, lm) = K(lm, lm) + k; end

lm=lmm(5,:); con=conn(5,:); k=PlaneTrussElement(e2, a3, nodes(con,:)); K(lm, lm) = K(lm, lm) + k

% Define the load vector R = zeros(8,1); R(4)=-P

% Nodal solution and reactions [d, reactions] = NodalSoln(K, R, [1,2,7,8], zeros(4,1)) results=[]; for i=1:2 results = [results; PlaneTrussResults(e1, a1, ...           nodes(conn(i,:),:), d(lmm(i,:)))]; end for i=3:4 results = [results; PlaneTrussResults(e1, a2, ...           nodes(conn(i,:),:), d(lmm(i,:)))]; end format short g results = [results; PlaneTrussResults(e2, a3, ...       nodes(conn(5,:),:), d(lmm(5,:)))]

Output to the Command Window

>> FiveBarTrussEx

K =

32600       76067       -32600       -76067            0            0            0            0        76067  2.9749e+005       -76067 -1.7749e+005            0    -1.2e+005            0            0 -32600      -76067  2.4309e+005  1.1914e+005       -32998        32998 -1.7749e+005       -76067 -76067 -1.7749e+005 1.1914e+005  2.4309e+005        32998       -32998       -76067       -32600 0           0       -32998        32998    1.53e+005       -32998    -1.2e+005            0 0   -1.2e+005        32998       -32998       -32998    1.53e+005            0            0 0           0 -1.7749e+005       -76067    -1.2e+005            0  2.9749e+005        76067 0           0       -76067       -32600            0            0        76067        32600

R =

0          0           0     -150000           0           0           0           0

d =

0           0      0.53895     -0.95306       0.2647      -0.2647            0            0

reactions =

54927 1.5993e+005 -54927     -9926.7

results =

-0.0001743     -34.859 -1.3944e+005 -3.15e-005     -6.2999       -25200 -5.2941e-005     -10.588       -31764 -5.2941e-005     -10.588       -31764 0.00032087      22.461        44922

The results show the strain, stress, and axial force in each element corresponding to the three columns in the "results" matrix.

To visualize the loaded and unloaded system, the following code graphs the system in its loaded and unloaded state. In order to be able to realize the direction of node movement, the unfixed node displacements have been magnified by a factor of two (using the variable "m"). As shown, the original values from the displacement array (d3-d6) above were used below to get the right proportions of the nodal displacements.

FiveBarTrussDisplay.m
%Displaying the five bar truss clear; close;

m = 2;

d1 = 0;         %disp of node 1 in the x direction d2 = 0;         %disp of node 1 in the y direction d3 = 0.53895*m; %disp of node 2 in the x direction d4 = -0.95306*m; %disp of node 2 in the y direction d5 = 0.2647*m;  %disp of node 3 in the x direction d6 = -0.2647*m; %disp of node 3 in the y direction d7 = 0;         %disp of node 4 in the x direction d8 = 0;         %disp of node 4 in the y direction

%input nodal coordinates num_nodes = 4;              %total number of nodes num_elems = 5;              %total number of elements tot_dofs = 2 * num_nodes;   %total dofs of the system

%undeformed positions pos(1,:)=[0 1.5 0 5]; pos(2,:)=[0 3.5 5 5];

%undeformed nodal coordinate arrays for i=1:num_nodes x(i)=pos(1,i); y(i)=pos(2,i); end

%element connectivity array %follows: %node_conn(local node number, element number) = global node number

node_conn(1,1)=1;    %element 1 node_conn(2,1)=2;

node_conn(1,2)=2;    %element 2 node_conn(2,2)=4;

node_conn(1,3)=1;    %element 3 node_conn(2,3)=3;

node_conn(1,4)=3;    %element 4 node_conn(2,4)=4;

node_conn(1,5)=2;    %element 5 node_conn(2,5)=3;

%plot the undeformed 2-bar truss system for i=1:num_elems node_1=node_conn(1,i); node_2=node_conn(2,i); xx=[x(node_1),x(node_2)]; yy=[y(node_1),y(node_2)]; axis([-1 6 -1 6]) plot(xx,yy,'--rs') hold on end

n = -0.5; o = -0.25; text(0+n,0,'GN1','HorizontalAlignment','center') text(1.5+n,3.5,'GN2','HorizontalAlignment','center') text(0+n,5,'GN3','HorizontalAlignment','center') text(5+n,5,'GN4','HorizontalAlignment','center') text(0.75+o,1.75,'E1','HorizontalAlignment','center') text(3.25+o,4.25,'E2','HorizontalAlignment','center') text(0+o,2.5,'E3','HorizontalAlignment','center') text(2.5+o,5,'E4','HorizontalAlignment','center') text(0.75+o,4.25,'E5','HorizontalAlignment','center')

%deformed positions pos(1,:)=[0+d1 1.5+d3 0+d5 5+d7]; pos(2,:)=[0+d2 3.5+d4 5+d6 5+d8];

%deformed nodal coordinate arrays for i=1:num_nodes x(i)=pos(1,i); y(i)=pos(2,i); end

text(1.5+d3+n,3.5+d4,'GN2','HorizontalAlignment','center') text(0+d5+n,5+d6,'GN3','HorizontalAlignment','center') text(pos(1,1)+(pos(1,2)-pos(1,1))/2+o,pos(2,1)+(pos(2,2)-pos(2,1))/2,'E1','HorizontalAlignment','center') text(pos(1,2)+(pos(1,4)-pos(1,2))/2+o,pos(2,2)+(pos(2,4)-pos(2,2))/2,'E2','HorizontalAlignment','center') text(pos(1,1)+(pos(1,3)-pos(1,1))/2+o,pos(2,1)+(pos(2,3)-pos(2,1))/2,'E3','HorizontalAlignment','center') text(pos(1,3)+(pos(1,4)-pos(1,3))/2+o,pos(2,3)+(pos(2,4)-pos(2,3))/2,'E4','HorizontalAlignment','center') text(pos(1,2)+(pos(1,3)-pos(1,2))/2+o,pos(2,2)+(pos(2,3)-pos(2,2))/2,'E5','HorizontalAlignment','center')

%plot the deformed 2-bar truss system for i=1:num_elems hold on   node_1=node_conn(1,i); node_2=node_conn(2,i); xx=[x(node_1),x(node_2)]; yy=[y(node_1),y(node_2)]; plot(xx,yy,'-s') end

title('Deformed and Undeformed Five-bar Truss System') xlabel('X') ylabel('Y')

The dotted line represents the undeformed system shape. The solid line represents the deformed system shape. The abbreviation "GN" and "E" stand for Global Node and Element, respectively. Note only nodes 2 and 3 are displaced because they are unfixed.

For the three bar truss created in the class notes, the two bar truss system code (Two Bar Truss System.m) was modified from Section 6 of Homework 2. One node and element each were added to the system, and e, A, P, and L values were changed to coincide with the problem.

ThreeBarTrussEx.m
% Three bar truss example clear all; e = [2 4 3]; A = [3 1 2]; P = 30; L = [5 5 10]; alpha = pi/6; beta = -pi/6; gamma = -3*pi/4; nodes = [0, 0; L(1)*cos(alpha), L(1)*sin(alpha); L(1)*cos(alpha) + L(2)*cos(beta), L(1)*sin(alpha) + L(2)*sin(beta); L(1)*cos(alpha) + L(3)*cos(gamma), L(1)*sin(alpha) + L(3)*sin(gamma)]; dof = 2*length(nodes); conn = [1 2; 2 3; 2 4]; lmm = [1 2 3 4; 3 4 5 6; 3 4 7 8]; elems = size(lmm,1); K = zeros(dof); R = zeros(dof,1); debc = [1 2 5 6 7 8]; ebcVals = zeros(length(debc),1);

%load vector R = zeros(dof,1); R(4) = P;

% Assemble global stiffness matrix K = zeros(dof); for i = 1:elems lm = lmm(i,:); con = conn(i,:); k_local = e(i)*A(i)/L(i)*[1 -1; -1 1] k = PlaneTrussElement(e(i), A(i), nodes(con,:)) K(lm, lm) = K(lm, lm) + k; end K R % Nodal solution and reactions [d, reactions] = NodalSoln(K, R, debc, ebcVals) results = []; for i = 1:elems results = [results; PlaneTrussResults(e, A, nodes(conn(i,:),:), d(lmm(i,:)))]; end format short g results

Output to the Command Window

>> ThreeBarTrussEx

k_local =

1.2000  -1.2000   -1.2000    1.2000

k =

0.9000   0.5196   -0.9000   -0.5196    0.5196    0.3000   -0.5196   -0.3000   -0.9000   -0.5196    0.9000    0.5196   -0.5196   -0.3000    0.5196    0.3000

k_local =

0.8000  -0.8000   -0.8000    0.8000

k =

0.6000  -0.3464   -0.6000    0.3464   -0.3464    0.2000    0.3464   -0.2000   -0.6000    0.3464    0.6000   -0.3464    0.3464   -0.2000   -0.3464    0.2000

k_local =

0.6000  -0.6000   -0.6000    0.6000

k =

0.3000   0.3000   -0.3000   -0.3000    0.3000    0.3000   -0.3000   -0.3000   -0.3000   -0.3000    0.3000    0.3000   -0.3000   -0.3000    0.3000    0.3000

K =

0.9000   0.5196   -0.9000   -0.5196         0         0         0         0    0.5196    0.3000   -0.5196   -0.3000         0         0         0         0   -0.9000   -0.5196    1.8000    0.4732   -0.6000    0.3464   -0.3000   -0.3000   -0.5196   -0.3000    0.4732    0.8000    0.3464   -0.2000   -0.3000   -0.3000         0         0   -0.6000    0.3464    0.6000   -0.3464         0         0         0         0    0.3464   -0.2000   -0.3464    0.2000         0         0         0         0   -0.3000   -0.3000         0         0    0.3000    0.3000         0         0   -0.3000   -0.3000         0         0    0.3000    0.3000

R =

0    0     0    30     0     0     0     0

d =

0        0  -11.6737   44.4051         0         0         0         0

reactions =

-12.5672  -7.2557   22.3866  -12.9249   -9.8194   -9.8194

results =

2.4186      4.8371       9.6742       7.2557       14.511       9.6742       14.511       6.4625       12.925        25.85       19.387       38.775        25.85       38.775       2.3145       4.6289       9.2578       6.9434       13.887       9.2578       13.887

After running this code, the output produces displacement of node 2 to be -11.6737 in the x-direction and 44.4051 in the y-direction. On the other hand, the "results" matrix has 7 columns instead of 4. This is due to the fact that vectors for the modulus of elasticity (e), cross-sectional area (A), and element length (L) were passed as variables instead of the scalar values. The first column is the strain array for elements 1-3. This is followed by two 3x3 matrices created for stresses and axial forces of the elements instead of two arrays of length 3 each. The real values for stress and axial force lie along the diagonals of each of these matrices.

The code for displaying the three bar truss was similar to the code displaying the five bar truss. However, a displacement magnification factor (m) of 0.25 was used to ease visualization of the deformation.

ThreeBarTrussDisplay.m
%Displaying the three bar truss clear; close;

m = 0.25;

d1 = 0;         %disp of node 1 in the x direction d2 = 0;         %disp of node 1 in the y direction d3 = -11.6737*m; %disp of node 2 in the x direction d4 = 44.4051*m; %disp of node 2 in the y direction d5 = 0;         %disp of node 3 in the x direction d6 = 0;         %disp of node 3 in the y direction d7 = 0;         %disp of node 4 in the x direction d8 = 0;         %disp of node 4 in the y direction

%input nodal coordinates num_nodes = 4;              %total number of nodes num_elems = 3;              %total number of elements tot_dofs = 2 * num_nodes;   %total dofs of the system

%element 1 details L1 = 5; E1 = 2; A1 = 3; theta1 = 30; %deg thetar1 = (pi * theta1)/180;

%element 2 details L2 = 5; E2 = 4; A2 = 1; theta2 = -30; %deg thetar2 = (pi * theta2)/180;

%element 3 details L3 = 10; E3 = 3; A3 = 2; theta3 = -135; %deg thetar3 = (pi * theta3)/180;

%undeformed positions pos(1,:)=[0,L1*cos(thetar1),L1*cos(thetar1)+L2*cos(thetar2),L1*cos(thetar1)+L3*cos(thetar3)]; pos(2,:)=[0,L1*sin(thetar1),L1*sin(thetar1)+L2*sin(thetar2),L1*sin(thetar1)+L3*sin(thetar3)];

%undeformed nodal coordinate arrays for i=1:num_nodes x(i)=pos(1,i); y(i)=pos(2,i); end

%element connectivity array %follows: %node_conn(local node number, element number) = global node number

node_conn(1,1)=1;    %element 1 node_conn(2,1)=2;

node_conn(1,2)=2;    %element 2 node_conn(2,2)=3;

node_conn(1,3)=2;    %element 3 node_conn(2,3)=4;

%plot the undeformed 2-bar truss system for i=1:num_elems node_1=node_conn(1,i); node_2=node_conn(2,i); xx=[x(node_1),x(node_2)]; yy=[y(node_1),y(node_2)]; axis([-5 10 -10 20]) plot(xx,yy,'--rs') hold on end

n = -1; o = -0.5; text(x(node_conn(1,1))+n,y(node_conn(1,1)),'GN1','HorizontalAlignment','center') text(x(node_conn(2,1))+n,y(node_conn(2,1)),'GN2','HorizontalAlignment','center') text(x(node_conn(2,2))+n,y(node_conn(2,2)),'GN3','HorizontalAlignment','center') text(x(node_conn(2,3))+n,y(node_conn(2,3)),'GN4','HorizontalAlignment','center') text(x(node_conn(2,1))/2+o,y(node_conn(2,1))/2,'E1','HorizontalAlignment','center') text(x(node_conn(2,1))+(x(node_conn(2,2))-x(node_conn(2,1)))/2+o,y(node_conn(2,1))+(y(node_conn(2,2))-y(node_conn(2,1)))/2,... 'E2','HorizontalAlignment','center') text(x(node_conn(2,1))+(x(node_conn(2,3))-x(node_conn(2,1)))/2+o,y(node_conn(2,1))+(y(node_conn(2,3))-y(node_conn(2,1)))/2,... 'E3','HorizontalAlignment','center')

%deformed positions pos(1,:)=[0+d1,L1*cos(thetar1)+d3,L1*cos(thetar1)+L2*cos(thetar2)+d5,L1*cos(thetar1)+L3*cos(thetar3)+d7]; pos(2,:)=[0+d2,L1*sin(thetar1)+d4,L1*sin(thetar1)+L2*sin(thetar2)+d6,L1*sin(thetar1)+L3*sin(thetar3)+d8];

%deformed nodal coordinate arrays for i=1:num_nodes x(i)=pos(1,i); y(i)=pos(2,i); end

text(x(node_conn(2,1))+n,y(node_conn(2,1)),'GN2','HorizontalAlignment','center') text(x(node_conn(2,1))/2+o,y(node_conn(2,1))/2,'E1','HorizontalAlignment','center') text(x(node_conn(2,1))+(x(node_conn(2,2))-x(node_conn(2,1)))/2+o,y(node_conn(2,1))+(y(node_conn(2,2))-y(node_conn(2,1)))/2,... 'E2','HorizontalAlignment','center') text(x(node_conn(2,1))+(x(node_conn(2,3))-x(node_conn(2,1)))/2+o,y(node_conn(2,1))+(y(node_conn(2,3))-y(node_conn(2,1)))/2,... 'E3','HorizontalAlignment','center')

%plot the deformed 2-bar truss system for i=1:num_elems hold on   node_1=node_conn(1,i); node_2=node_conn(2,i); xx=[x(node_1),x(node_2)]; yy=[y(node_1),y(node_2)]; plot(xx,yy,'-s') end

title('Deformed and Undeformed Three-bar Truss System') xlabel('X') ylabel('Y')

The dotted line represents the undeformed system shape. The solid line represents the deformed system shape. The abbreviation "GN" and "E" stand for Global Node and Element, respectively. Note only node 2 is displaced because it is unfixed.

Derivation of d2
Knowing that $$l^e = cos(\theta)$$ and $$m^e = sin(\theta)$$

$$d_2^e = d_1^e\vec i + d_2^e\vec j$$

$$\tilde d_2^e = \tilde d_1^e\vec\tilde j$$

$$\tilde d_2^e = d_1^e(\vec i*\vec\tilde j) + d_2^e(\vec j*\vec\tilde j)$$

Knowing that $$(\vec i*\vec\tilde j)= -m^e$$ and $$(\vec j*\vec\tilde j)= l^e$$ the following simplification can be preformed.

$$\tilde d_2^e = -m^ed_1^e + l^ed_2^e$$

$$\tilde d_2^e = \begin{bmatrix} -m^e&l^e\end{bmatrix} \begin{bmatrix}d_1^e\\d_2^e\end{bmatrix}$$

Eigenvector Plotting
Now we want to plot the eigenvectors corresponding to the 0 eigenvalues of the 2-bar truss system that we have been looking at in class for the past few weeks. We want to assume no constraints on the 2-bar truss system so we will use the full 6x6 global stiffness matrix.

We know that the global stiffness matrix K is:

K = 0.5625   0.3248   -0.5625   -0.3248         0         0    0.3248    0.1875   -0.3248   -0.1875         0         0   -0.5625   -0.3248    3.0625   -2.1752   -2.5000    2.5000   -0.3248   -0.1875   -2.1752    2.6875    2.5000   -2.5000         0         0   -2.5000    2.5000    2.5000   -2.5000         0         0    2.5000   -2.5000   -2.5000    2.5000

If we use the eig function in Matlab we get that the eigenvalues are as follows:

Eval=eig(K) Eval= -0.0001        -0.0000         -0.0000          0.0000          1.4706         10.0294

Next we can use the function [V,D] = EIG(X)which gives us a diagonal matrix D of eigenvalues and a full matrix V whose columns contain the corresponding eigenvectors that corresponds to the equation:

$$\textbf{X}\times\textbf{V}=\textbf{D}\times\textbf{V}$$

For our particular case, we set X equivalent to K and the diagonal matrix D equivalent to $$\lambda$$ to get the following:

$$\textbf{K}\times\textbf{V}=\lambda\times\textbf{V}$$

Therefore, using Matlab we get:

[V,Lam]=eig(K) Lam = -0.0001        0         0         0         0         0         0   -0.0000         0         0         0         0         0         0   -0.0000         0         0         0         0         0         0    0.0000         0         0         0         0         0         0    1.4706         0         0         0         0         0         0   10.0294  V = -0.4494   0.3877    0.5158    0.0160    0.6174   -0.0139    0.6754   -0.4281    0.4825    0.0244    0.3565   -0.0080    0.1682    0.3877    0.5158    0.0160   -0.5409    0.5123   -0.3942   -0.4281    0.4825    0.0244   -0.4330   -0.4904    0.2812    0.4163   -0.0116    0.7023   -0.0765   -0.4984   -0.2812   -0.3995   -0.0449    0.7107    0.0765    0.4984

Where Lam contains the previously found eigenvalues and V contains the corresponding eigenvectors. It is important to note now that while Matlab calculated the eigenvalues to precise decimals, we can assume that the first four values in the diagonal Lam matrix are 0.

Now we would like to plot the eigenvectors that correspond to these four 0 eigenvalues so we may get a look at their mode shapes. Using the following Matlab function allows us to plot the four mode shapes at the same time.

for i=1:4 figure plot(V(:,i)); title(['Mode Shape ',num2str(i)]) end

Now let us consider the following three-bar truss system.

Assume that all three bars have the same material properties:

L=1    E=2      A=3

$$k=\frac{EA}L=\frac{(2)(3)}1=6$$

For element 1 and element 3:

$$l^{(1,3)}=0$$

$$m^{(1,3)}=1$$

For elemnt 2:

$$l^{(2)}=1$$

$$m^{(2)}=0$$

$$\textbf{k}^{(1)}=\textbf{k}^{(3)}= \left [\begin{array}{c c c c} 0 & 0 & 0 & 0\\ 0 & 36 & 0 & -36\\ 0 & 0 & 0 & 0\\ 0 & -36 & 0 &-36 \end{array}\right]$$

$$\textbf{k}^{(2)}= \left [\begin{array}{c c c c} 36 & 0 & -36 & 0\\ 0 & 0 & 0 & 0\\ -36 & 0 & 36 & 0\\ 0 & 0 & 0 & 0 \end{array} \right]$$

$$\textbf{K}= \left [\begin{array}{c c c c c c c c} 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ 0 & 36 & 0 & -36 & 0 & 0 & 0 & 0\\ 0 & 0 & 36 & 0 & -36 & 0 & 0 & 0\\ 0 & -36 & 0 & 36 & 0 & 0 & 0 & 0\\ 0 & 0 & -36 & 0 & 36 & 0 & 0 & 0\\ 0 & 0 & 0 & 0 & 0 & 36 & 0 & -36\\ 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0\\ 0 & 0 & 0 & 0 & 0 & -36 & 0 & 36 \end{array} \right] $$

In this example we are assuming that global nodes 1 and 4 are constrained so that they don't move. This means that $$d_1=d_2=d_7=d_8=0$$. Therefore we only have to consider the following modified global stiffness matrix.

$$\overline{\textbf{K}}= \left[ \begin{array} {c c c c} 36 & 0 & -36 & 0\\ 0 & 36 & 0 & 0\\ -36 & 0 & 36 & 0\\ 0 & 0 & 0 & 36 \end{array} \right]$$

If we follow the same steps as above we get:

Kbar = 36    0   -36     0     0    36     0     0   -36     0    36     0     0     0     0    36 Eval=eig(Kbar) Eval = 0   36    36    72 [V,Lam]=eig(Kbar) V = -0.7071        0         0   -0.7071         0    1.0000         0         0   -0.7071         0         0    0.7071         0         0    1.0000         0 Lam = 0    0     0     0     0    36     0     0     0     0    36     0     0     0     0    72

In this example we have only one zero eigenvalue and it's eigenvectors can be plotted as follows:

plot(V(:,1)); title(['Mode Shape',num2str(1)])

Derivation and Assembly of Row 4
Equation 2 is:

$$f_4^1+f_2^2=0$$

Which can also be written as:

$$\begin{bmatrix} k_{41}^1d_1^1+k_{42}^1d_2^1+k_{43}^1d_3^1+k_{44}^1d_4^1 \end{bmatrix}+\begin{bmatrix} k_{21}^2d_1^2+k_{22}^2d_2^2+k_{23}^2d_3^2+k_{24}^2d_4^2 \end{bmatrix}=0$$

The previous equation rewritten using global dof rather then local dof is:

$$\begin{bmatrix} k_{41}^1d_1^1+k_{42}^1d_2^1+k_{43}^1d_3^1+k_{44}^1d_4^1 \end{bmatrix}+\begin{bmatrix} k_{21}^2d_3^2+k_{22}^2d_4^2+k_{23}^2d_5^2+k_{24}^2d_6^2 \end{bmatrix}=0$$

Contributing Team Members
Aaron Fisher - Eml4500.f08.Lulz.fisher 00:37, 24 October 2008 (UTC)

Eric Layton - Eml4500.f08.Lulz.Layton.Eric 02:19, 22 October 2008 (UTC)

John Saxon - Eml4500.f08.Lulz.js 05:23, 24 October 2008 (UTC)

Andrew Strack - Eml4500.f08.lulz.strack 10:25, 24 October 2008 (UTC)

Benjamin Mitchell - Eml4500.f08.Lulz.mitchell.bm 20:09, 24 October 2008 (UTC)

Sam Miorelli - Eml4500.f08.lulz.abcd 21:01, 24 October 2008 (UTC)

title: User:Eml4500.f08.Lulz.Layton.Eric/Hw4


title: File:DSC00329.jpg


text:
User:Borko~enwikiversity

About Me
Hi. My name is Bobby and i'm from the University of Sofia "Kliment Ohridski".

title: User:Borko~enwikiversity


text:
User talk:Slott

 Hello Slott, and welcome to Wikiversity! If you need help, feel free to visit my talk page, or contact us and ask questions. After you leave a comment on a talk page, remember to sign and date; it helps everyone follow the threads of the discussion. The signature icon in the edit window makes it simple. To get started, you may

 * Take a guided tour and learn to edit.
 * Visit a (kind of) random random project.
 * Browse everything on Wikiversity, or visit a portal corresponding to your educational level: pre-school, primary, secondary, tertiary, non-formal education.
 * Find out about research activities on Wikiversity.

 * Read an introduction for teachers and find out how to write an educational resource for Wikiversity.
 * Give feedback about your initial observations
 * Discuss Wikiversity issues or ask questions at the colloquium.
 * Chat with other Wikiversitans on #wikiversity-en.

And don't forget to explore Wikiversity with the links to your left. Be bold to contribute and to experiment with the sandbox or your userpage, and see you around Wikiversity! --HappyCamper 03:02, 22 October 2008 (UTC)

title: User talk:Slott


text:
User talk:Borko~enwikiversity

 Hello Borko, and welcome to Wikiversity! If you need help, feel free to visit my talk page, or contact us and ask questions. After you leave a comment on a talk page, remember to sign and date; it helps everyone follow the threads of the discussion. The signature icon in the edit window makes it simple. To get started, you may

 * Take a guided tour and learn to edit.
 * Visit a (kind of) random random project.
 * Browse everything on Wikiversity, or visit a portal corresponding to your educational level: pre-school, primary, secondary, tertiary, non-formal education.
 * Find out about research activities on Wikiversity.

 * Read an introduction for teachers and find out how to write an educational resource for Wikiversity.
 * Give feedback about your initial observations
 * Discuss Wikiversity issues or ask questions at the colloquium.
 * Chat with other Wikiversitans on #wikiversity-en.

And don't forget to explore Wikiversity with the links to your left. Be bold to contribute and to experiment with the sandbox or your userpage, and see you around Wikiversity! --HappyCamper 03:02, 22 October 2008 (UTC)

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Borko. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Borko~enwikiversity that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:31, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 06:04, 19 April 2015 (UTC)

title: User talk:Borko~enwikiversity


text:
User talk:Arstcha

 Hello Arstcha, and welcome to Wikiversity! If you need help, feel free to visit my talk page, or contact us and ask questions. After you leave a comment on a talk page, remember to sign and date; it helps everyone follow the threads of the discussion. The signature icon in the edit window makes it simple. To get started, you may

 * Take a guided tour and learn to edit.
 * Visit a (kind of) random random project.
 * Browse everything on Wikiversity, or visit a portal corresponding to your educational level: pre-school, primary, secondary, tertiary, non-formal education.
 * Find out about research activities on Wikiversity.

 * Read an introduction for teachers and find out how to write an educational resource for Wikiversity.
 * Give feedback about your initial observations
 * Discuss Wikiversity issues or ask questions at the colloquium.
 * Chat with other Wikiversitans on #wikiversity-en.

And don't forget to explore Wikiversity with the links to your left. Be bold to contribute and to experiment with the sandbox or your userpage, and see you around Wikiversity! --HappyCamper 03:02, 22 October 2008 (UTC)

title: User talk:Arstcha


text:
User:La comadreja/Research

CURRENT RESEARCH  This page contains an overview of the specific research projects La comadreja has developed. There's more than enough room for you to join one, or to propose others. Just contact La comadreja by leaving a message on her Wikiversity User talk page.

Empirical and Theoretical Research

These projects are good for students to gain firsthand exposure to the scientific method. They provide unique opportunities for in-depth learning about various aspects of biology.

 * Echinoderm Nervous System Evolution Project - laboratory techniques
 * G-Protein Coupled Receptor Gene Duplication Project - computational analysis of databases

Essays Under Revision

 * An essay about self-organization and its role in the evolution of complexity, currently formulated as a course
 * How the theories of the Modern Evolutionary Synthesis should be reformulated for today's evolutionary biologists

Databases

 * Wikiversity Genomics Database

title: User:La comadreja/Research