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User:Eml4500.f08.bottle.loschak/HW3

HW 3 work matlab problem

% Matlab coding for HW 3 problem % For HW3, write a matlab code to plot the initial underformed % configuration of the two-bar truss system solved in class in % dotted line, and then superpose on the same figure the deformed % configuration in solid line. clear; close; % L(1) = 4 % theta(1) = 30 % k(1) = 3/4 % AC = 6.8324 % L(2) = 2 % theta(2) = -45 % k(2) = 5 % AB = 1.255 n_node = 8; n_elem = 6; P1_1 = 5.1243; P1_2 = 6.276; k_1 = .75; k_2 = 5; AC = P1_1/k_1; AB = P1_2/k_2; position(:,1) = [0; 0; 0]; position(:,2) = [4*cos(.5236); 4*sin(.5236); 0]; position(:,3) = [4*cos(.5236)+2*cos(.7854); 4*sin(.5236)-2*sin(.7854); 0]; position(:,4) = [4*cos(.5236)-1.255*cos(.7854); 4*sin(.5236)+1.255*sin(.7854); 0]; position(:,5) = [4*cos(.5236)+6.8324*cos(.5236); 4*sin(.5236)+6.8324*sin(.5236); 0]; position(:,6) = [4*cos(.5236)+6.8324*cos(.5236)-4*cos(1.047); 4*sin(.5236)+6.8324*sin(.5236)+4*sin(1.047); 0]; position(:,7) = [4*cos(.5236)-1.255*cos(.7854)+8*cos(.7854); 4*sin(.5236)+1.255*sin(.7854)+8*cos(.7854); 0]; position(:,8) = [7.8157; 8.1264; 0];   % intersection between AC and AB                                         % determined by zooming on graph % intersection for i = 1 : n_node; x(i) = position(1,i); y(i) = position(2,i); z(i) = position(3,i); end node_connect(1,1) = 1; node_connect(2,1) = 2; node_connect(1,2) = 2; node_connect(2,2) = 3; node_connect(1,3) = 2; node_connect(2,3) = 4; node_connect(1,4) = 2; node_connect(2,4) = 5; node_connect(1,5) = 4; node_connect(2,5) = 7; node_connect(1,6) = 5; node_connect(2,6) = 6; node_connect(1,7) = 1; node_connect(2,7) = 8; node_connect(1,8) = 3; node_connect(2,8) = 8; for i = 1 : n_elem; node_1 = node_connect(1,i); node_2 = node_connect(2,i); xx = [x(node_1),x(node_2)]; yy = [y(node_1),y(node_2)]; zz = [z(node_1),z(node_2)]; axis([-1 10 -1 10]) plot3(xx,yy,zz,':') hold on end for i = 7 : 8; node_1 = node_connect(1,i); node_2 = node_connect(2,i); xx = [x(node_1),x(node_2)]; yy = [y(node_1),y(node_2)]; zz = [z(node_1),z(node_2)]; plot3(xx,yy,zz,'-') hold on end title('Deformed and undeformed two-bar truss system') xlabel('x') ylabel('y') zlabel('z') view([0 0 1])     % xy plane view

title: User:Eml4500.f08.bottle.loschak/HW3


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User:Eml4500.f08.a-team.melvin/Lecture 17

Meeting 17: Friday, 26 September 2008, EML4500
ΣFx = 0, ΣFy = 0, ΣM A = 0 (sum of moments trivial)

Q: How about ΣM B ?

3D explanation

ΣM B  = BA X F

ΣM B  = BA' X F

for A' on linen of action of F

BA = BA + AA'

M B  = (BA + AA') X F

M B  = BA X F + AA' X F

where = AA' X F = 0

Back to 3-Bar Truss:

Node A is in equilibrium : ΣF i  = 0 from i=0 to i=3

Σ i M Bi  = Σ i BA' i  X F i

A' i = any point on the line of action of F i

Σ i M Bi  = Σ i BA' i  X F i

Σ i M Bi  = BA X Σ i F i  = 0 - meaning ΣM B is useless, still only 2 useful equations.

K 33 = K(1) 33 + K(2) 11 + K(3) 11

K 34 = K(1) 34 + K(2) 12 + K(3) 12

HW: Fill out the rest!

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


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Social psychology (psychology)/Lectures/Prosocial/Notes

View the slides

Introduction
This lecture introduced socio-psychological theory and research about prosocial behaviour and altruism. These are different concepts, with altruism being a subset of prosocial behaviour in which a prosocial behaviour is undertaken without any thought of personal reward. Prosocial behaviour refers to any behavioural act which further the interests of a group by improving its cohesion, quality of relationships, etc. What is deemed prosocial by one group may be considered by other groups to be antisocial. Antisocial behaviours are those judged to be destructive to group relationships.

An important psychological and philosophical issue for debate is whether there is any such thing as true altruism. The closer one looks at the possible explanations and motivations for prosocial behaviour, the more it seems that its possible to find non-altruistic explanations for prosocial behaviours. This is a rich topic for debate. A related issue is whether altruism is only evident (if at all) in humans or whether other animals are also altruistic e.g., what do you think about this video of a gorilla rescuing a kid at a zoo (1 min)?

Collectively, prosocial behaviour contributes to social capital, a concept which is explored in the Australian zeitgeist tutorial.

Prosocial behaviour can be contrasted with antisocial behaviour which are acts that undermine or otherwise negatively affect social relations within a community.

When would you help?

 * 1) A collapsed stranger in the street?...
 * 2) Some rubbish on a path?...
 * 3) Donate blood? organ? money? time?...
 * 4) Hitchiker?...
 * 5) Someone whose car is broken on the side of the road?...

What factors influence whether you help or not and why?

Prosocial behaviour is not just about helping
The Baumeister and Bauman (2008) textbook criticises many other social psychology textbook chapters on prosocial behaviour for being overly focused on "helping" and neglecting focus on the prosocial role of obedience and conformity (Note that we discussed obedience and conformity earlier in the lecture on social thinking and, more specifically, on social influence).

Reasons for prosocial behaviour
Reasons for prosocial behaviour include:
 * Self-interest
 * Improve social status
 * Reciprocity - direct or indirect
 * Conformity (e.g., to fairness - most people want a balance between underbenefitting and overbenefitting)
 * Rule of law (but also note that some acts of disobediance (e.g., civil disobediance) may ultimately prove to be prosocial rather than antisocial. In this respect, Kohlberg's stages of moral development help to give insight to "higher law")
 * Evolutionary (e.g., kin selection, which is stronger in more life-threatening situations)
 * Altruism (is it motivated by empathy for the other; or efforts to relieve one's own personal distress about the other person being distressed?)

Forgiveness
Given that often "bad" is stronger than "good", forgiveness of another for causing harm can be a particularly notable prosocial contribution. Forgiveness involves letting go of anger, resentment, and blaming of one's emotional distress as caused by another's antisocial behaviours.

Game theory
In the previous lecture on Groups and Relationships, the commons dilemma and the prisoners' dilemma were discussed as examples of iterative, experimental studies conducted to examine the sociodynamics of competition and cooperation. The collective results of our myriad relational games might be considered as a group's social capital. The net results of various interactions can be loosely understood as negative, neutral, or positive - see the helpful tables and diagrams here:. Also of relevance here is transactional analysis, Robert S. De Ropp's "The Master Game", Manning-Clark's straighteners and enlargers, etc. Essentially these and other such "game theory" schemes seek to describe and understand common sociodynamic relational patterns and their consequences.

Obedience and conformity
Without obedience and conformity to a rule of law, our social lives would be far more chaotic. Thus, obeying and conforming to social rules is vital for creating and maintaining a community. However, communities evolve and change, thus rules and norms often need to similarly evolve. And there is a danger in a group members becoming overly compliant and conforming, such as classically illustrated in Milgram's 1950's studies of obedience. Also, see Asch's conformity experiments. A more recent example of obedience is a TV show in which contestants were asked to torture. 80% of contestants went to the very end - i.e, administered the ultimate, potentially lethal shock ( BBC News, 2010; Telegraph.co.uk, 2010).

Motivations for helping
Batson (1994):
 * Egoism – helping benefits the helper – receive rewards or escape punishment.
 * Altruism – helping benefits others – no need for reciprocity.
 * Collectivism – helping benefits the in-group.
 * Principalism – help because of a moral imperative

Empathy-altruism hypothesis
Batson (1991) proposed that empathy motivates people to reduce other people’s distress by helping or comforting:
 * If low empathy, people can reduce their own distress by escaping the situation
 * If high empathy, emotional response corresponds to feelings of other person redue our distress by reducing other person's distress

Negative relief state theory is the proposition that people help others in order to relieve their own distress.

Personal determinants of helping

 * Personality - weak predictor, but consider "warmth"
 * Competence - more skilled you are in the area of need, the more likely you are to help
 * Attributions - recall from social thinking that we have a tendency to blame others' problems on their selves (as opposed to their circumstances, whereas we have a tendency to find external explanations for our own distress. We generally are more likely to help someone if we perceive that their circumstances were externally caused rather than caused by themselves (and thereby "deserved" - see the Just World Hypothesis)
 * Personal norms - personal norms for helping based on personal values (e.g., religious beliefs). If we have "helpfulness" as part of our self-concept, then we need to act in consistent ways otherwise we experience cognitive dissonance.

Emotion and helping
In general, positive mood increases likelihood of helping, whereas negative mood tends to decrease likelihood of helping. Note, however, that there are logical exceptions to this tendency (e.g., if it will be costsly to one's positive mood one may not help, or if it will relieve one's negative state, one may be more likely to help).

Interpersonal determinants of helping

 * 1) Females are more likely to receive help
 * 2) Attractiveness - more likely to help attractive others.
 * 3) Similarity - we are morely likely to help similar others (similarity increases attractiveness & empathy)
 * 4) Closeness - more likely to help those we know.
 * 5) Deservingness - help those we judge as deserving our help (e.g,. based on reciprocity and attribution).

Gender

 * 1) Males are more likely to help in "dramatic" circumstances, and broader societal spheres, and they are more likely to help women than men
 * 2) Females are more likely to help in "mundane" life, in the local sphere, and are more likely to receive help

Bystander effect
The larger the group, the less likely people are to help because of:
 * 1) Diffusion of responsibility: the reduction in feeling responsible that occurs when others are present.
 * 2) Pluralistic ignorance: looking to others for cues about how to behave, while they are looking to you; collective misinterpretation.

Five steps to helping
Five steps (or barriers) to helping have been proposed (Latane & Darley):
 * 1) Notice that something is happening
 * 2) Interpret meaning of event - Pluralistic ignorance
 * 3) Taking responsibility for providing help - # Diffusion of responsibility
 * 4) Know how to help
 * 5) Provide help

Good Samaritan study
Darley and Batson (1973)'s classic study found that time (in a rush or not in a rush) had the largest effect. Those in a rush were much less likely to help. Summary of the study.

Bystander-calculus model
Piliavin, Dovidio, Gaertner, and Clark (1981) offer a social exchange theory model for the bystander effect, according to which bystanders calculate the (perceived) costs & benefits of providing help in three stages:
 * 1) Physiological arousal - e.g., witnessing an emergency - the higher the physiological arousal, the  greater chance of helping.
 * 2) Labelling the arousal - type of label influences the kind of help offered; e.g., is arousal labelled as personal distress or empathic concern? - usually labelled as personal distress.
 * 3) Evaluating the consequences -  weigh up costs of helping, choose action that reduces personal distress at lowest cost.  Costs might include getting hurt, inconvenience, embarrassment etc.

How can we increase helping?

 * 1) Reduce ambiguity
 * 2) Reduce distractions (or make the need for help more obvious)
 * 3) Reduce pluralistic ignorance
 * 4) Increase personal responsibility (reduce diffusion of responsibility), e.g., reduce anonymity
 * 5) Reduce concerns about competence to help
 * 6) Reduce audience inhibitions
 * 7) Reduce uncertainties of obstacles
 * 8) Educate about bystander indifference
 * 9) Model helpfulness e.g., positive models in the media.
 * 10) Teach moral inclusion - perception of certain people as inside/outside our bounds of moral or ethical concern
 * 11) Guilt & concern for self-image - use of compliance tactics
 * 12) Learning about / socialising altruism

Summary and conclusion

 * 1) Prosocial behaviour includes conformity, obedience, and cooperating with others, but may also include disobedience.
 * 2) Human culture depends on people following rules.
 * 3) Following the rules of society and culture generally brings immense personal and social benefits.
 * 4) Is altruism unique to humans?
 * 5) Cultural and social variables and situational contingencies can significantly influence whether a person performs prosocial or antisocial behaviours


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User:Eml4500.f08.echo.lacroix/HW3

Monday Sept 22
Derivation of element FD with respect to global coordinate system:

$$\mathbf{k}_{4x4}^{(e)}\mathbf{d}_{4x1}^{(e)}=\mathbf{f}_{4x1}^{(e)}$$  (Equation 1)

This can equivalently be expressed in the following figure.

In matrix terms this is:

$$k^{(e)}\begin{bmatrix} 1 & -1 \\ -1 & 1 \end{bmatrix}\begin{Bmatrix} q_1^{(e)} \\ q_2^{(e)} \end{Bmatrix}=\begin{Bmatrix} P_1^{(e)} \\ P_2^{(e)} \end{Bmatrix}$$  (Equation 2)

In short:

$$\hat{\mathbf{k}}_{2x2}^{(e)}\mathbf{q}_{2x1}^{(e)}=\mathbf{P}_{2x1}^{(e)}$$

$$q_i^{(e)}=$$ axial displacement of element e at local node i

$$P_i^{(e)}=$$ axial force of element e at local node i

Goal: Derive Equation 1 from Equation 2. This can be done with the help of previous notes.

The k matrix can be found using the theta's.

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

Where: $$l_{ }^{(e)}=cos( \theta^{(e)})$$

$$m_{ }^{(e)}=sin( \theta^{(e)})$$

Next, the 4x1 distance matrix can be found using trigonometry.

$$\mathbf{d}_{4x1}^{(e)}=\begin{Bmatrix} d_1^{(e)} \\ d_2^{(e)} \\ d_3^{(e)} \\ d_4^{(e)} \end{Bmatrix}=\begin{Bmatrix} q_1^{(e)}\cdot cos\theta_1^{(e)} \\ q_1^{(e)}\cdot sin\theta_1^{(e)} \\ q_2^{(e)}\cdot cos\theta_1^{(e)} \\ q_2^{(e)}\cdot sin\theta_1^{(e)} \end{Bmatrix}$$

Similarly, the 4x1 force matrix can be derived.

$$\mathbf{f}_{4x1}^{(e)}=\begin{Bmatrix} f_1^{(e)} \\ f_2^{(e)} \\ f_3^{(e)} \\ f_4^{(e)} \end{Bmatrix}=\begin{Bmatrix} P_1^{(e)}\cdot cos\theta_1^{(e)} \\ P_1^{(e)}\cdot sin\theta_1^{(e)} \\ P_2^{(e)}\cdot cos\theta_1^{(e)} \\ P_2^{(e)}\cdot sin\theta_1^{(e)} \end{Bmatrix}$$

Therefore the result is:

$$k^{(e)}\begin{bmatrix} cos( \theta^{(e)})^2 & cos( \theta^{(e)})sin( \theta^{(e)}) & -cos( \theta^{(e)})^2 & -cos( \theta^{(e)})sin( \theta^{(e)}) \\cos( \theta^{(e)})sin( \theta^{(e)}) & sin( \theta^{(e)})^2 & -cos( \theta^{(e)})sin( \theta^{(e)}) & -sin( \theta^{(e)})^2 \\-cos( \theta^{(e)})^2 & -cos( \theta^{(e)})sin( \theta^{(e)}) & cos( \theta^{(e)})^2 & cos( \theta^{(e)})sin( \theta^{(e)}) \\-cos( \theta^{(e)})sin( \theta^{(e)}) & -sin( \theta^{(e)})^2 & cos( \theta^{(e)})sin( \theta^{(e)}) & sin( \theta^{(e)})^2\end{bmatrix}\begin{Bmatrix} q_1^{(e)}\cdot cos\theta_1^{(e)} \\ q_1^{(e)}\cdot sin\theta_1^{(e)} \\ q_2^{(e)}\cdot cos\theta_1^{(e)} \\ q_2^{(e)}\cdot sin\theta_1^{(e)} \end{Bmatrix}=\begin{Bmatrix} P_1^{(e)}\cdot cos\theta_1^{(e)} \\ P_1^{(e)}\cdot sin\theta_1^{(e)} \\ P_2^{(e)}\cdot cos\theta_1^{(e)} \\ P_2^{(e)}\cdot sin\theta_1^{(e)} \end{Bmatrix}$$

These relations can be expressed in the form:

$$\mathbf{q}_{2x1}^{(e)}=\mathbf{T}_{2x4}^{(e)}\mathbf{d}_{4x1}^{(e)}$$

Consider the displacement vector of local node 1, denoted by $$d_1^{(2)}$$:

$$\vec{d}_1^{(e)}=d_1^{(e)}\vec{i}+d_2^{(e)}\vec{j}$$

$$q_1^{(e)}=$$ axial displacement of node 1 is the orthogonal projection of the displacement

Vector $$\vec{d}_1^{(e)}$$ of node 1 on the axes $$\tilde{x}$$ of element e:

$$\Rightarrow q_1^{(e)}=\vec{d}_1^{(e)}\cdot\vec{i}=(d_1^{(e)}\vec{i}+d_2^{(e)}\vec{j})\cdot\vec{\tilde{i}}=d_1^{(e)}(\vec{i}\cdot\vec{\tilde{i}})+d_2^{(e)}(\vec{j}\cdot\vec{\tilde{i}})=d_1^{(e)}\cdot cos\theta^{(e)}+d_2^{(e)}\cdot sin\theta^{(e)}=d_1^{(e)}\cdot l^{(e)}+d_2^{(e)}\cdot m^{(e)}$$

$$\mathbf{q}_1^{(e)}=l^{(e)}\cdot d_1^{(e)}+m^{(e)}\cdot d_2^{(e)}=\begin{bmatrix} l^{(e)} & m^{(e)} \end{bmatrix}\begin{Bmatrix} d_1^{(e)} \\ d_2^{(e)} \end{Bmatrix}$$

Similarly for node 2:

$$\Rightarrow q_2^{(e)}=\vec{d}_3^{(e)}\cdot\vec{i}=(d_3^{(e)}\vec{i}+d_4^{(e)}\vec{j})\cdot\vec{\tilde{i}}=d_3^{(e)}(\vec{i}\cdot\vec{\tilde{i}})+d_4^{(e)}(\vec{j}\cdot\vec{\tilde{i}})=d_3^{(e)}\cdot cos\theta^{(e)}+d_4^{(e)}\cdot sin\theta^{(e)}=d_3^{(e)}\cdot l^{(e)}+d_4^{(e)}\cdot m^{(e)}$$

$$\mathbf{q}_2^{(e)}=l^{(e)}\cdot d_3^{(e)}+m^{(e)}\cdot d_4^{(e)}=\begin{bmatrix} l^{(e)} & m^{(e)} \end{bmatrix}\begin{Bmatrix} d_3^{(e)} \\ d_4^{(e)} \end{Bmatrix}$$

Combining:

$$\mathbf{q}_{2x1}^{(e)}=\mathbf{T}_{2x4}^{(e)}\mathbf{d}_{4x1}^{(e)}$$

$$\begin{Bmatrix} q_1^{(e)} \\ q_2^{(e)} \end{Bmatrix}=\begin{bmatrix} l^{(e)} & m^{(e)} & 0 & 0\\0 & 0 & l^{(e)} & m^{(e)}\end{bmatrix}\begin{Bmatrix} d_1^{(e)} \\ d_2^{(e)} \\ d_3^{(e)} \\ d_4^{(e)}\end{Bmatrix}$$

title: User:Eml4500.f08.echo.lacroix/HW3


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User:Eas4200c.f08.gator.edwards/Matlab Program

The following MATLAB function was created to plot the shape of a NACA 4-digit series airfoil. It also calculates the area and centroid of the cross section. Following the function is the implementation and output, copied out of the command window.

large

EDU>> airfoil(2415);

Cross Sectional Area A = 0.1013 Centroid Location C = (0.4203, 0.0157)


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User:Eml4500.f08.team.Bengtson/teamHW3

Meeting 12)
To find the derivation of element FD wrt global coordinate system please consult page 6-1 of the notes.

$$\boldsymbol{K}^{(e)}\boldsymbol{d}^{(e)}=\boldsymbol{f}^{(e)}$$

K (e)is a 4x4 matrix

d(e) is a 4x1 matrix

f(e) is both multiplied together to form a 4x1 matrix.

Reference from page 4-5 in the notes

$$ \boldsymbol{K}^{(e)} \begin{bmatrix} 1 & -1 \\ -1 & 1 \\ \end{bmatrix} $$$$\begin{Bmatrix} q_{1}^{(e)} \\ q_{1}^{(e)}\\ \end{Bmatrix} $$ =$$\begin{Bmatrix} P_{1}^{(e)}\\ P_{2}^{(e)} \end{Bmatrix}$$

$$ \boldsymbol{K}^{(e)}$$is a 2x2 matix $$ q_{i}^{(e)} $$ is an axial displacement of element e at local node i

$$P_{i}^{(e)}$$ is the axial force at local node i.

Goal: Derive eq(1) from eq(2)

Want to find relation (already done in meeting 4)

d(e) 2x1 and d(e) 4x1

p(e) 2x2 and f(e) 4x1

The relationship between q and d is $$ q^{(e)}=d^{e}_{i}\bullet \tilde{\imath }$$

The relationship between p and f is axis on which it works is different. One works on the normal x-y axis, the other works on the $$\tilde{x}$$ axis

$$\boldsymbol{K}^{(e)}*\boldsymbol{d}^{(e)}=\boldsymbol{f}^{(e)}$$

$$\boldsymbol{K}^{(e)}*\boldsymbol{q}^{(e)}=\boldsymbol{P}^{(e)}$$

So multiply by the inverse of K and you get the distance and axial distance. You can then find the relation by using the previous relationship between q and d.

These relationships can be expressed in for $$q^{(e)}=\boldsymbol{T}^{(e)}\boldsymbol{d}^{(e)}$$

Consider the displacement vector of the load mode [1], denoted by d[1](2)

$$d_{[1]}^{(e)}=d_{1}^{e}\imath +d_{2}^{e}\jmath $$

$$q_{1}^{(e)}$$= axial displacement of node [1] is the orthogonal projection of the displacement vector math>d_{[1]}^{(e)} of node 1 on the axis ~χ of element e

$$\Rightarrow q_{1}^{(e)}=\vec{d_{[1]}^{(e)}}\bullet \vec{\imath} $$

d(e) can be separated into a horizontal and vertical component

$$=\left(d_{1}^{(e)}\vec{\imath} +d_{2}^{(e)}\vec{\jmath} \right)\bullet \vec{\iota} $$

The dot product can be distributed and you get

$$=d_{1}^{(e)}\left(\vec{\imath} \bullet \vec{\iota} \right) + d_{2}^{(e)}\left(\vec{\jmath} \bullet \vec{\iota} \right)$$

The first part of the equation above is equal to $$\cos \theta ^{(e)}$$ or l(e)

The second part of the eqution above is equal to $$\sin \theta ^{(e)}$$ or M(e)

$$q^{(e)}_{1}= l^{(e)}d_{1}^{(e)}+ m^{(e)}d_{2}^{(e)}$$

$$q=\begin{bmatrix} l^{(e)} & M^{(e)} \end{bmatrix} \begin{Bmatrix} d_{1}^{(e)}\\ d_{2}^{(e)} \end{Bmatrix}$$

q is a 1x1 matrix (otherwise known as a scalar)

It is also the displacement along the $$\tilde{x}$$ axis.

Similarly for node [2]:

$$q_{2}^{(e)}=\begin{bmatrix} l^{(e)} & M^{(e)} \end{bmatrix} \begin{Bmatrix} d_{3}^{(e)}\\ d_{4}^{(e)} \end{Bmatrix}$$

$$\begin{Bmatrix} q_{1}^{(e)} \\ q_{2}^{(e)} \end{Bmatrix}= \begin{bmatrix} l^{(e)} & M^{(e)}& 0 & 0 \\ 0 & 0 & l^{(e)} & M^{(e)}\end{bmatrix} \begin{Bmatrix} d_{1}^{(e)}\\d_{2}^{(e)}\\d_{3}^{(e)}\\d_{4}^{(e)}\end{Bmatrix} $$

This equation shows how you can find the axial displacement of the two nodes by multiplying the displacements by the proper m(e) and l(e)

title: User:Eml4500.f08.team.Bengtson/teamHW3


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User:Eml4500.f08.bottle.brockmiller/hw3

Prove that $$\  \mathbf{k}^{(e)} = \mathbf{T}^{(e)T} \mathbf{\hat{k}}^{(e)} \mathbf{T}^{(e)}  $$  is true by multiplying right hand side of the equation.

$$\ \mathbf{T}^{(e)} $$ is defined in class as $$\ \begin{bmatrix} l^{(e)}&m^{(e)}&0&0\\0&0&l^{(e)}&m^{(e)} \end{bmatrix}_{2x4} $$

$$\ \mathbf{\hat{k}}^{(e)}$$ is defined in class as $$\ \begin{Bmatrix} k&-k\\-k&k\end{Bmatrix}_{2x2}$$

$$\ \mathbf{T}^{(e)T} $$ is the transpose of $$\ \mathbf{T}^{(e)}_, $$ where $$\ \mathbf{T}^{(e)T}_{ij} = \mathbf{T}^{(e)}_{ji} $$ from $$\ 1 \le i \le n_, \ 1 \le j \le m $$ for matrix $$\ \mathbf{T}^{(e)}$$  of dimensions $$\ n * m $$

Therefore, $$\ \mathbf{T}^{(e)T} = \begin{bmatrix} l^{(e)}&0\\m^{(e)}&0\\0&l^{(e)}\\0&m^{(e)} \end{bmatrix}_{4x2} $$

$$\ \mathbf{T}^{(e)T}*\mathbf{\hat{k}}^{(e)}= \begin{bmatrix} l^{(e)}*k^{(e)}&-l^{(e)}*k^{(e)}\\m^{(e)}*k^{(e)}&-m^{(e)}*k^{(e)}\\-l^{(e)}*k^{(e)}&l^{(e)}*k^{(e)}\\-m^{(e)}*k^{(e)}&m^{(e)}*k^{(e)} \end{bmatrix}_{4x2} $$

$$\ \mathbf{T}^{(e)T}*\mathbf{\hat{k}}^{(e)}*\mathbf{T}^{(e)}= \begin{bmatrix} l^{(e)}*l^{(e)}*k^{(e)}&l^{(e)}*m^{(e)}*k^{(e)}&-l^{(e)}*l^{(e)}*k^{(e)}&-l^{(e)}*m^{(e)}*k^{(e)}\\l^{(e)}*m^{(e)}*k^{(e)}&m^{(e)}*m^{(e)}*k^{(e)}&-l^{(e)}*m^{(e)}*k^{(e)}&-m^{(e)}*m^{(e)}*k^{(e)}\\-l^{(e)}*l^{(e)}*k^{(e)}&-l^{(e)}*m^{(e)}*k^{(e)}&l^{(e)}*l^{(e)}*k^{(e)}&l^{(e)}*m^{(e)}*k^{(e)}\\-l^{(e)}*m^{(e)}*k^{(e)}&-m^{(e)}*m^{(e)}*k^{(e)}&l^{(e)}*m^{(e)}*k^{(e)}&m^{(e)}*m^{(e)}*k^{(e)} \end{bmatrix}_{4x4} $$

Bringing out the $$\ k^{(e)} $$ and combining common terms gives $$\ \mathbf{T}^{(e)T}*\mathbf{\hat{k}}^{(e)}*\mathbf{T}^{(e)}= k^{(e)}\begin{bmatrix} (l^{(e)})^2&l^{(e)}*m^{(e)}&-(l^{(e)})^2&-l^{(e)}*m^{(e)}\\l^{(e)}*m^{(e)}&(m^{(e)})^2&-l^{(e)}*m^{(e)}&-(m^{(e)})^2\\-(l^{(e)})^2&-l^{(e)}*m^{(e)}&(l^{(e)})^2&l^{(e)}*m^{(e)}\\-l^{(e)}*m^{(e)}&-(m^{(e)})^2&l^{(e)}*m^{(e)}&(m^{(e)})^2 \end{bmatrix}_{4x4} $$

This is equivalent to the $$\ \mathbf{k}^{(e)} $$ given in class.

Therefore, $$\ \mathbf{f}^{(e)}=\mathbf{k}^{(e)}\mathbf{d}^{(e)} $$ can be written as

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

title: User:Eml4500.f08.bottle.brockmiller/hw3


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User:Eml4500.f08.bottle.brockmiller/hw1

Chapter 4 of the textbook Finite Element Analysis With Mathematica and Matlab Computations visits the Finite Element Method approach to understanding trusses, beams, and frame systems. Often, engineers and other problem solvers are faced with statically indeterminate systems. In other words, using standard knowledge of statics and mechanics of materials will not be able to understand these systems. The Finite Element Method is a different way of understanding these systems with the use of matrix algebra. Basically, the method rather than analyzing the system as a whole, parts of the system are analyzed separately. This chapter first treats plane truss systems. Unlike beams and frames, trusses are only subjected to axial loads. It is assumed that they are elastic bars that are deformable.

When faced with a problem dealing with truss systems, it is important to clearly understand the background of the problem and what is being asked. Diagrams are especially useful in visualizing the problem when they are properly labeled. Starting with the entire system itself, a clearly and properly marked global free body diagram (FBD) is necessary. Included in this diagram would be the global coordinate system, loads, reactions, degrees of freedom, and labels for each node and member of the system. Examples of degrees of freedom are the known, fixed degrees of freedom and constraints, or the unknown, often displacements. It is standard to label the global nodes using numbers with circles encircling the numbers. The members of the system should be labeled with numbers encircled by triangles. From this, one can determine whether or not the system is statically indeterminate.

Once the system has been determined statically indeterminate, one may proceed with Finite Element Analysis. Since the members of the system will be analyzed separately, element free body diagrams should be created for each of the members of the system. This process also has its own standard labeling method. Although the nodes should already have been labeled encircled by circles, labeling the local nodes encircled with a square helps clarify the diagram. The reactions, loads, and degrees of freedom should be written the same except for the global nodes that experience the loads, once should choose one member of the system that undergoes the load while the other member doesn't. The local coordinate system may be the same as the global coordinate system, or one may be chosen to further simplify the problem.

Recalling back to fundamental physics, the equation that describes the force (F) of a spring with a spring constant (k) where one end is fixed and the other goes through a displacement (x) is F=kx. However, this single equation can not describe the motion of a spring where both ends are not fixed. This is a statically indeterminate system, therefore the Finite Element Method must be used. The motion of this scenario can be described

$$\begin{Bmatrix} F_1 \\ F_2 \end{Bmatrix} = \begin{bmatrix} k & -k \\ -k & k \end{bmatrix}\begin{Bmatrix} d_1 \\ d_2 \end{Bmatrix}$$

where Fi is the force of node i=1,2, k is the stiffness matrix, and di is the displacement of node i=1,2. This can also be applied to truss systems in a similar manner. However many degrees of freedom determines the size of the matrix. In the spring scenario, there were two degrees of freedom creating a 2X1 force matrix, a 2X1 displacement matrix and a 2X2 stiffness matrix. In truss systems that are unconstrained the stiffness matrix will be of dimensions mXn, where m is the number of unknown displacement degrees of freedom and n is the number of both known and unknown degrees of freedom. Once the known degrees of freedom are eliminated the force and displacement matrix will be mX1, and the stiffness matrix will be mXm. For consistency purposes, the element stiffness and force matrices will be situated in the global coordinate system. Once the stiffness and displacement matrices are established, one may calculate the reactions (the unknown forces).

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User:Eas4200c.f08.vqcrew.d/hw3

Curved Panels
Figure 1 shows a curved panel with uniform thickness $$t$$ and constant shear stress $$\tau $$. This diagram will be analyzed in order to determine the forces acting on the panel in both the y and z directions. The shear flow $$q$$ is defined as: $$q=t \tau $$

In order to find the total forces acting in the y and z direction, the panel must be divided up into small sections with differential lengths and force vectors. A side view of the panel with dimensions and the differential components is shown in Figure 2. The differential force element, $$d\bar{F}$$, is equal to the shear flow multiplied by the differential length of the element, or: $$d\bar{F}=qd\bar{L}$$

A larger view of the differential length and force element are shown in Figure 3. Figure 3 also shows the components of the differential length element. The differential force vector and length vector can be broken into y and z components and simplified as follows:

$$d\bar{F}=qd\bar{L}$$ $$d\bar{F}=q(dL_{y} \hat{j} + dL_{z} \hat{k})$$ $$d\bar{F}=q(dL cos\theta \hat{j} + dL sin \theta  \hat{k})$$ $$d\bar{F}=q(dy \hat{j} + dz  \hat{k})$$

By integrating along the path from A to B, we can find the total force acting on the curved panel.

$$\bar{F}=\int_{A}^{B}{d \bar{F}}=q\left(\int_{A}^{B}{dy \hat{j}} + \int_{A}^{B}{dz \hat{k}}\right)$$ $$\bar{F}=q\left(a \hat{j} + b\hat{k}\right)$$

The force vector can be broken into y and z components and equated to the above solution to produce equations (1.4) and (1.5): $$\bar{F}=F_{y} \hat{j} + F_{z} \hat{k}$$ $$\Rightarrow F_{y} = qa = t \tau a$$ $$\Rightarrow F_{z} = qb = t \tau b$$

The relationship between the force components in a curved panel can be expressed as: $$\frac{F_y}{F_z}=\frac{a}{b}$$

The magnitude of the force, $$\left|\left| \bar{F} \right| \right|$$, can be expressed as follows: $$\left|\left| \bar{F} \right| \right|=\sqrt{(F_y)^2+(F_z)^2} = q\sqrt{a^2+ b^2}$$

However, $$\sqrt{a^2+ b^2}$$ is equal to the straight line distance, $$d$$, from point A to B. Therefore the force vector can also be expressed as: $$\bar{F}=qd$$

Torsion in a Closed, Thin-walled Beam
Figure XX depicts a generic, closed, thin-walled cross-section for a beam under torsion. The coordinate system may be defined from any arbitrary point in the plane of the section. The torque vector points in the positive x direction, or: $$\bar{T}=T \hat{i}$$ The differential unit of torque can be described as the cross product of the distance from the origin to the differential length segment with the differential force vector, or: $$d \bar{T}= \bar{r} \times d \bar{F}$$ The magnitude of this element is: $$dT=\rho dF$$ where $$\rho$$ is the perpendicular distance from the origin to the force vector and $$dF=qdL$$. To find the total torque, the differential torque element must be integrated about the closed path of the cross-section.

$$T=\oint{dT} = \oint{\rho dF}=q\oint{\rho dL}$$ However, $$\rho dL$$ is also equal to twice the area of the triangle swept out by the $$r$$ vector and $$dL$$. We can evaluate the integral over the average area, $$\bar{A}$$, to find the total torque as follows:

$$T=2q\int _{\bar{A}}{dA}=2q\bar{A}$$

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text: Advanced ANOVA/Admin

title: Advanced ANOVA/Admin


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Enterprise Resource Planning/Accounting

This is a course about enterprise resource planning (ERP) accounting, or ERP accounting.

Programme
This is a module part of the Open Source ERP/Executive Masters course conducted by a private university.

Subject
ERP Accounting - From Basics to Financial Management

Objectives
The objectives of this subject are:
 * To grasp the core Accounting Principles behind ERP processes
 * To appreciate the global different localisation on Accounting
 * To know the Accounting Consequences of the main Document Types
 * To understand the Financial Management needs and issues of ERP

Learning Outcomes
On completion of this subject the students shall be able to:
 * Demonstrate basic simple accounting equations
 * Perform GL Journal entries in the ERP application
 * Trace the Accounting Consequence of each document process in ERP
 * Troubleshoot and suggest modifications to the accounting model
 * Produce Financial Reports from the ERP System

Sypnosis
This subject handles just enough accounting and financial aspects of the ERP system. It covers the supply chain accounting consequences, where the ERP produces a complete balanced set of financial reports for periodic as well as regulatory purposes.

Basic Accounting
(15 hrs)
 * ^1 - Concept of ERP Accounting (Perpetual, and Default Accounts Posting)
 * ^2 - Accounting Equation and Its Transactions (Assets, Liabilities, Revenues, Costs)
 * ^3 - Basic trial balances, T-accounts and drawing up simple accounts

Accounting Setup
(20 hrs)
 * ^4 - Commitment and Accrual Accounting
 * ^5 - The Chart of Accounts
 * ^6 - Accounting Schemas
 * ^7 - Budgetary Planning

Accounting Consequence
(20 hrs)
 * ^9 - Accounting Types
 * ^10 - Document Type concept
 * ^11 - Integration of AR / AP in ERP
 * ^12 - Source Code Classes

Account Viewer
(15 hrs)
 * ^13 - Account Type
 * ^14 - Summary and Groupings
 * ^15 - Dimensions

Project Accounting
(20 hrs)
 * ^16 - Activity Based Accounting
 * ^17 - Project Code
 * ^18 - RFP and Tender Handling
 * ^19 - e-Bidding and e-Marketplace

GL Journal
(15 hrs)
 * ^20 - Double Entry via Journal Batches
 * ^21 - Processing Batches
 * ^22 - Journal Proof

Product Assets
(15 hrs)
 * ^23 - Type of Assets
 * ^24 - Fixed Assets Accounting
 * ^25 - Production Assets Accounting
 * ^26 - Assets Maintenance

title: Enterprise Resource Planning/Accounting


text:
User:EML4500.f08.FEABBQ.Hamdan/HW-3

Class Notes: September 26, 2008
Equation [2]

$$ \mathbf{k^{(e)}} \mathbf{q^{(e)}} = \mathbf{P^{(e)}} $$

Fallowing the same argument above we get the relation

$$ \begin{Bmatrix} p_1^{(e)} \\ p_2^{(e)} \end{Bmatrix} = \left[ \begin{matrix} l^{(e)} & m^{(e)} & 0 & 0 \\ 0 & 0 & l^{(e)} & m^{(e)} \end{matrix} \right] \begin{Bmatrix} f_1^{(e)} \\ f_2^{(e)} \\ f_3^{(e)} \\ f_4^{(e)} \end{Bmatrix} $$

Equation [3]

$$ \mathbf{p_{2x1}^{(e)}} = \mathbf{T_{2x4}^{(e)}} \mathbf{f_{4x1}^{(e)}} $$

recalling element axial FD relation

Equation [4]

$$ \mathbf {k_{2x4}^{(e)}} \mathbf{q_{4x1}^{(e)}} =\mathbf{p_{2x1}^{(e)}}  $$

and Equation [5]

$$ \mathbf{q_{2x1}^{(e)}} = \mathbf{T_{2x4}^{(e)}} \mathbf{d_{4x1}^{(e)}} $$

Substituting equations 3 and 5 into equation 4 yields to

$$ \mathbf {k_{2x4}^{(e)}} \mathbf{T_{2x4}^{(e)}} \mathbf{d_{4x1}^{(e)}} =\mathbf{T_{2x4}^{(e)}} \mathbf{f_{4x1}^{(e)}}  $$

The Goal is to have $$ \mathbf{k^{(e)}} \mathbf{d^{(e)}} = \mathbf{f^{(e)}} $$ so move $$ \mathbf{T^{(e)}} $$ from R.H.S. to L.H.S. by premultiplying the equation by $$ \mathbf{{(T^{(e)})}^{(-1)}} $$        ( inverse $$ \mathbf{T^{(e)}} $$)

But unfortunately $$ \mathbf{T^{(e)}} $$ is a rectangular matrix [2x4], can't inverse $$ \mathbf{T^{(e)}} $$

to solve this problem the transpose property was used as follows

$$ \mathbf{{T_{4x2}^{(e)}}^{T}} \mathbf {k_{2x4}^{(e)}} \mathbf{T_{2x4}^{(e)}} \mathbf{d_{4x1}^{(e)}} = \mathbf{f_{4x1}^{(e)}} $$

$$ \mathbf{{T_{4x2}^{(e)}}^{T}} \mathbf {k_{2x4}^{(e)}} \mathbf{T_{2x4}^{(e)}} \mathbf{d_{4x1}^{(e)}} = \mathbf{f_{4x1}^{(e)}} $$

$$ \mathbf {k_{2x4}^{(e)}} \mathbf{d_{4x1}^{(e)}} = \mathbf{f_{4x1}^{(e)}}  $$

Homework

Verify that

$$ \mathbf {I_{4x4}} = \mathbf{{T_{4x2}^{(e)}}^{T}} \mathbf{T_{2x4}^{(e)}}   $$

$$ \mathbf {I_{4x4}} =  \left[ \begin{matrix} l^{(e)} & 0 \\ m^{(e)} & 0 \\ 0 & l^{(e)} \\ 0 & m^{(e)}  \end{matrix} \right]  \left[ \begin{matrix} l^{(e)} & m^{(e)} & 0 & 0 \\ 0 & 0 & l^{(e)} & m^{(e)} \end{matrix} \right]   $$

Applying the principle of virtual work will result reduction of global FD relation:

$$ \mathbf {k_{2x4}^{(e)}} = \mathbf{{T_{4x2}^{(e)}}^{T}}  \mathbf{\tilde{k}_{4x1}^{(e)}} \mathbf{T_{2x4}^{(e)}}   $$

Remark

why not solve as follows $$ \mathbf{d_{4x1}^{(e)}} = \mathbf{{(T^{(e)})}^{(-1)}}  \mathbf{f_{4x1}^{(e)}}  $$  ?

The answer is that the used methods to compute $$ \mathbf{{(K^{(e)})}^{(-1)}} $$ could not be used since K is singular. this will result a determinants value of zero and thus K is not inverted.

Recall

for an unconstrained structure system there are three possible body motion in 2-D (plane) two translation and one rotation.

Homework

Compute the eigenvalues of K and make observation about the number of zero eigenvalues.

Matlab: Computing eigenvalues
The following is a matlab script and output for the two-bar K example.

K =

0.5625     0.32476      -0.5625     -0.32476            0            0      0.32476       0.1875     -0.32476      -0.1875            0            0      -0.5625     -0.32476       3.0625      -2.1752         -2.5          2.5     -0.32476      -0.1875      -2.1752       2.6875          2.5         -2.5            0            0         -2.5          2.5          2.5         -2.5            0            0          2.5         -2.5         -2.5          2.5

>> eig(K)

ans =

-0.0000  -0.0000    0.0000    0.0000    1.4706   10.0294

Zero Eigenvalues correspond to zero stored elastic energy, rigid body modes- (shape, eigenvictors)

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User:Eas4200c.f08.aero6.villalba

EAS4200C
Derivation of the second moment of area of a circle

Problem 1.3

Problem 1.4

Problem 1.5

title: User:Eas4200c.f08.aero6.villalba


text:
User:Eml4500.f08.jamama.justin/HW3

Similarly (same argument)

$$\begin{Bmatrix} P{_{1}}^{(e)}\\ P{_{2}}^{(e)}\\ \end{Bmatrix} = T^{(e)} \begin{Bmatrix} f{_{1}}^{(e)}\\ f{_{2}}^{(e)}\\ f{_{3}}^{(e)}\\ f{_{4}}^{(e)} \end{Bmatrix} $$

2X1 2X4 4X1

$$\Rightarrow P^{(e)}=T^{(e)}f^{(e)}$$

Recall element axial force displacement relationship

$$\hat{k}^{(e)}q^{(e)}=P^{(e)}$$

2X2 2X12X1

$$\Rightarrow \hat{k}^{(e)}\left(T^{(e)}d^{(e)} \right)=\left(T^{(e)}f^{(e)} \right)$$

\_________/\__________/

$$q^{(e)}$$$$p^{(e)}$$

Goal: Want to have $$k^{(e)}d^{(e)}=f^{(e)}$$ so "move" $$T^{(e)}$$ from right to left hand side by pre-multiplying equation by $$T^{(e)-1}$$ (inverse of $$T^{(e)}$$ ). Unfortunately, $$T^{(e)}$$ is a rectangular matrix (2X4) so it cannot be inverted.

So the actual answer is:  $$\begin{bmatrix} T{^{(e)T}}\bullet \hat{k}^{(e)}T^{(e)} \end{bmatrix} d^{(e)}=f^{(e)}$$

[4X22X22X4] 4X14X1

[ equal to a 4X4 ]

 $$k^{(e)}d^{(e)}=f^{(e)}$$

$$k^{(e)}=T{^{(e)T}} \hat{k}^{(e)}T^{(e)}$$

Justification for the above equation: Principle Virtual Work (PVW)

(See notes from the September1 17th for the first application of PVW. This is shown through Reduction of Global FD relationship.)

$$k d = F \Leftrightarrow  \bar{k} \bar{d} = \bar{F}$$

6X6 6X1 6X62X2 2X1 2X1

Question: Why would you not solve as follows? $$d = k^{-1} F$$ ?

It is because the matrix k is a singularity, and the det k=0. Therefore $$k^{-1}$$ is not invertible. This is because

to find $$k^{-1}$$ you need to compute $$\frac{1}{det k}$$

why? For an unconstrained structural system, there are three possible rigid body motions in 2-D. (2-translational and 1-rotational)

Dynamic eigenvalue problems: $$K v=\lambda Mv $$

K=Stiffness matrix

$$\lambda$$=Eigen value (related to the vibrational frequency)

M=Mass matrix

Zero eigenvalue corresponds to zero stored elastic energy, so rigid body modes. Modes, also called mode shapes, are used to describe the vibrations in an object. These correspond to the number of half wave vibrations in a body.

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English Language Reference Desk/Archives/2007

In, on and at.
First question ever!

I am learning English on my own and I have already come across many things I could not understand. However none as embarrassing as not being able to grasp the difference between on, in and at! Those are really common words that I have read millions of times. Yet, when it comes to writing something, I many times have to Google the phrase I want to write so I can learn whether should I use in, on or at. And I have even changed a lot of my sentences as to avoid the use of any of the three.

Is there any true difference between those prepositions or is its use somewhat arbitrary and you just have to get used to it? In Portuguese, my native language, we have only one preposition for this sort of thing and it doesn't seem like it causes ambiguity. So I can't see the reason for spliting it into three prepositions. I would like to know what is the difference. Why can't say I am at Brazil, at the world, in Wikiversity, on my college, etc?

Do children in English-speaking countries have a hard time learning it as well or do they actually get it easily? A.z. 14:24, 5 April 2007 (UTC)

 * "In" means "inside", for example, "I'm going in the store".

 * "On" means "on top of" as in "I put the steak on the table".

 * "At" means "at that location" as in "I left the car at the hospital".

 * There are some ambiguous cases, though, like leaving an answer "in" a web page, "on" a web page, or "at" a web page. This ambiguity is because we don't have a single physical way to think of a web page.  Is it like a physical object with volume so you can put things inside it ?  Is it like a flat object so you can stack things upon it ?  Is it like a location where you can visit and leave things ?  StuRat 12:53, 6 April 2007 (UTC)

 * StuRat, I VERY MUCH appreciated your explanation about web pages. I felt a little "outside" the language when I came across people saying "on Wikipedia" but "in the article" and both "at the reference desk" and "on the reference desk". I had imagined that it was sort of what you said: how each person applies the rules originally made for the "real world" to a web page, a concept open to interpretation. But I had never read this anywhere.

 * I'm going to see whether my problems with those prepositions are over. I'll be really happy if they are, but I'm already pleased to understand them a lot better. If I continue having some trouble, I'll ask here again a more specific question. Thank you so much! A.Z. 16:29, 6 April 2007 (UTC)

 * You're quite welcome ! StuRat 21:12, 6 April 2007 (UTC)

 * "In a web page" sounds wrong to me in the context of "leaving an answer" at a web page. You can talk about the code "in a web page", but you leave responses "on" or "at" web pages, not "in" them (in my mind).  But part of the difficulty in knowing what prepositions to use may be that native speakers may disagree as to what is acceptable!  The Jade Knight 04:57, 7 April 2007 (UTC)

 * That's good information as well. Thank you, Jade Knight! A.Z. 19:57, 7 April 2007 (UTC)

 * "I am going in the store" may be accepted in US English, but it would not usually be encountered in British English, Australian English, or many other varieties of English. If you were at home and you wanted to tell someone you were going to the store to do some shopping, you'd say "I'm going to the store".  If you were standing outside the store having a chat, and you wanted to tell them that the chat was over and you were now going to do your shopping, you'd say "I'm going into the store".  The only case where you might say "I'm going in the store" is where you're inside the store, busting for a pee, and it's now far too late to find the restroom.  JackofOz 00:34, 10 April 2007 (UTC)

 * US English speakers would also say "I'm going to the store", not "I'm going in the store", while at home. However, either "I'm going in the store" or "I'm going into the store" would work if you were standing outside the door.  Unlike Aussies, since people in the US don't urinate inside stores (except in the rest room), we don't need a different way to say that. :-) StuRat 00:42, 10 April 2007 (UTC)

 * In the usage of much of the United States, one would speak of being "in Brazil and not "at Brazil" because Brazil is large. If one were "at the Rodoviária, the precise center of the city of Brasília", "at" would be used because of the specificity of the location.  One could be "in Praça dos Três Poderes" in Brasília because a Praça has Dimensions; it is not a point.  We are all "on the Earth" because it has a surface; but we live "in the World" because "World" is a name for the planet Earth seen from the point of view of mankind.  You participate "in" "on" or "at" Wikiversity" at your option, because, your point of view as to the nature of your participation determines your choice here.  Chances are that you are "in" or "at" your college depending on whether you are "residing in some building there" or "you are at a place where learning takes place".  Native-born children in English-speaking countries pick up their usages with some difficulty, as do children everywhere with certain usages; but after a period of experimentation with their languages, children everywhere generally come to conform to the ways things are spoken and understood.  -- Dionysios (talk), Date: 2007-07-22 (July 22, 2007) Time: 2345 UTC

Going to / will
What is the difference between saying "I am going to" and "I will"? A.Z. 19:59, 7 April 2007 (UTC)

 * They both mean the same thing, but perhaps "going to" is a bit weaker, as in "I'm going to write a book someday", meaning that's a goal which may or may not actually be achieved, while "I will write a book" means I definitely will. StuRat 23:49, 7 April 2007 (UTC)

 * There's a definite connotative difference to me. If you say "I'm going to go to the store", you're sharing what you're planning on, or about to do.  If you say "I will go to the store", what it means depends on where the stress is placed, but I think the most natural sense places emphasis on "I" and carries the implicity connotation that someone needed to go the store, and you're volunteering to be that person.  If emphasis was on "will", then it is implicit that someone has implied or stated that you're not likely to go to the store, and you're contradicting them.  What do you think, StuRat?  The Jade Knight 11:43, 9 April 2007 (UTC)

 * I was thinking of the emphasis on "will", as in "Stop bitching at me, I will go to the store, OK !". StuRat 17:36, 9 April 2007 (UTC)

 * "going to" is the plan of a certain action. Where as "I will" is the commitment to executing a certain action.

--Wtxwevr 02:55, 26 October 2007 (UTC)

To can
How come we say "I can do that" and "I could do that" but we can't say "to can do something must be good" and "I will can do that one day"? A.Z. 20:01, 7 April 2007 (UTC)

 * I don't know the reason, but it's definitely not right. StuRat 23:51, 7 April 2007 (UTC)

 * Do you think one day you will can discover the reason? a.z. 05:02, 8 April 2007 (UTC)

 * Perhaps we should ask a toucan ? :-) StuRat 04:25, 9 April 2007 (UTC)

 * "could" and "can" are both modals in English, and in English, you cannot use the infinitive of modals. There is no "to should", "to would", "to might", etc.  The closest approximate you can make to "to can to" in English is "to be able to".  In proper English, you also cannot stack modals.  That being said, however, I know people around here who do stack modals!  "I will can do that one day" may be not so unacceptable for some, and I know people with college degrees who say things like "I might should give that a try some day."  This is non-standard usage, but it does happen.  BTW, the provided Wikipedia link may prove instructive.  The Jade Knight 11:50, 9 April 2007 (UTC)

 * The modal verbs "can", "must, "will", "shall" are also known as defective verbs because they have no infinitive form of their own.82.46.44.139 20:48, 4 July 2007 (UTC)

 * Good point. Wikipedia also has an article on defective verbs.  The Jade Knight 08:39, 5 July 2007 (UTC)

I am having problem with the usage of could. Which form of verb are we suppose to use with could

 * Can you give some examples of sentences which are giving you trouble ? Until we see those, I'm going to assume the problem you are having is the common one of confusing "can"/"could" with "will".  I like to substitute "is it possible for you to" in place of "can"/"could" and "are you going to" in place of "will".  So, is it correct to say "could you take the garbage out" ?  It is only correct if you mean to ask "is it possible for you to take the garbage out ?".  For example, if someone had a broken leg and you weren't sure if they could physically do it, then this would be the right form.  If, on the other hand, you know it is possible and just want to know if they are planning to do so, then you should say "are you going to take the garbage out ?" or "will you take the garbage out ?".  StuRat 18:34, 18 February 2008 (UTC)

Did and Have
Thank you all for all the answers above! I really learned from them. I'd like to learn more about the difference between saying "I have eaten it" and "I ate it". I most of the time choose between the two forms based on my "feeling" of which one is the most appropriate, and I'd like to know when it would be wrong to use one of them. a.z. 19:42, 14 April 2007 (UTC)

 * "I ate it" is less formal, that's the only diff I can think of. StuRat 01:56, 15 April 2007 (UTC)

 * That's interesting to know, but the eating thing was just the verb that I randomly chose to mean that I would like to know the difference beween saying "have" and "did", no matter which verb follows! a.z. 02:34, 15 April 2007 (UTC)

Actually,as far as I know,you have two instances:"I ate it"-The Past Simple Tense,and "I have eaten it"-The Present Perfect Tense.Now,if your mother tongue doesn't contain something such as 'a perfece tense'(I am referring to the whole group-The present perfect tense,the past perfect tense,the present perfect progressive tense and the past perfect progressive tense),like mine does(I am Bulgarian,and Bulgarian does not have these tenses),you will have a difficult time until you learn to grasp the difference between present perfect and past simple tense,which is often ver subtle.And very often there is no significant difference in meaning at all. Ok,basically,the main difference between the two is that(and now I'm quoting from a grammar book I have)"the present perfect tense indicates an action,which has begun at an unknown moment in the past and is still going on,when the act of speaking occurs.For example"I have been in Paris"-indicates that someone has once,at an unknown for us period of time visited Paris.We don't know exactly when that happened,that's why we use the present perfect. The past simple is used to refer to an action done at a specific period in the past(for example-"yesterday","last week/month/year",a year ago,etc").For example-"I ate a sandwitch an hour ago." So,when you try to make a difference between the two tenses,and which one of them is the more appropriate in a specific situation,there are several things you can do: 1.Look for words in the sentence,which indicate some specific moment in time,such as: yesterday,last week/month/year,2 years ago,an hour ago,a minute ago,etc.Any word that you feel might indicate the specific time in which the action takes place. 2.Words like"already","yet","still" very often suggest the use of the present perfect tense.Mostly because they don't stand for a specific moment in time.But it all depends on the context,don't take that rule literally,there are always exceptions. 3.If you don't find any of the above words,you must examine the context in order to decide which tense is more appropriate to be used. I know what I have written doesn't examine thoroughly the topic,because there's still a lot to be said on the matter.But I think I have given you the basics. In case you have any questions on the matter,or you want to ask me something else,feel free to write at:venera.hitova@gmail.com,and I'll do my best to help you. Melisandra 18:41, 23 April 2007 (UTC)Melisandra

Grammar question
In the sentence "Please stop running," what form is running? It doesn't look like a gerundive to me, and I have no idea what else it could be.

By the way, this page is being linked to from the top, where is says "Add your question to the list, at the bottom of the page." Are there supposed to be two pages for this?

Thanks much,

--Falconus 16:09, 8 July 2007 (UTC)

 * Ah hah! Thanks for pointing that out.  The link is in error.  I'll fix it anon.
 * As for your question, I would say that "running" would be the present participle. The Jade Knight 00:39, 9 July 2007 (UTC)

 * Alright, thanks --Falconus 02:01, 9 July 2007 (UTC)

How do you pronounce proper name "Geoffrey"?
Hello, I was just studying something about Geoffrey Chaucer and I was wondering how do you pronouce it. Seems to be a stupid question, but I've always been taught I should pronounce it this way: /gɒfri/ (or something like that) and absolutely not /ˈʤɛfri/ as everyone incorrectly does (told me my university professor). Then I found the latter version on it.wiki and was quite surprised, can some native speaker explain this to me? Maybe the pronunciation I was taught is the old English one? --Eyesglare 10:28, 9 July 2007 (UTC)

 * Yes, I believe that's correct, except that Middle English, not Old English, was the language of the time (Old English is almost completely unintelligible to speakers of modern English). Many pronunciations have drifted over time, with "talked" being an example.  At the time it was a two syllable word, pronounced like "talk Ed".  Now we pronounce it, and many other similar words, like "talk'd".  Of course, everyone can define their own pronunciation for their own name, so we can't be absolutely sure, but I would say your prof was most likely correct.  Note, however, that most modern speakers named "Geoffrey" tend to pronounce their names just like "Jeffrey".  I would pronounced Chaucer's name the way he most likely would have at the time, however, not in the modern way. StuRat 12:46, 9 July 2007 (UTC)
 * Evidently, Geoffrey was introduced into England by the Normans—I would be very surprised if a name spelled "Geoffrey" was pronounced /g/ and not /ʤ/. Wikipedia lists "Jeffrey" as a Medieval variant of "Geoffrey", further supporting a /ʤ/ pronunciation.  The name itself seems to have fallen entirely out of use among Norman speakers (name lists for both Jèrriais and Cotentinais lack a "Geoffrey" equivalent), so you can't appeal to modern Norman forms for help on this one.  The Jade Knight 03:23, 10 July 2007 (UTC)
 * It's possible that the /g/ pronunciation derives from the co-existance of the name "Godfrey". At any rate, while professors are generally smart, don't always trust everything they say—I've met both English and History professors who were unaware of the differences between French and Norman.  The Jade Knight 03:28, 10 July 2007 (UTC)

Another grammar question
In English, it is correct to say "runner," or "batter," or "seer," amongst others. Although people do it all the time, is it acceptable to tack 'er' (with necessary spelling changes) onto any verb which makes sense to do so?

Also, what is this concept called?

Thanks again,

--Falconus 14:23, 12 July 2007 (UTC)

 * I'm not sure if this counts as nominalization or not, but it is somewhat common. However, I'm not sure if there are limitations to its employment in English.  The Jade Knight 00:55, 13 July 2007 (UTC)

 * Note that "runner" (unless you consider a carpet runner) and "batter" (unless you consider battering your cake batter) mean just what you'd expect, but "seer" has a meaning beyond just "one who sees", it's more like "one who sees what others can not". StuRat 01:49, 13 July 2007 (UTC)

 * Cool, thanks --Falconus 15:13, 13 July 2007 (UTC)

 * Keep an eye out for things people do for a living. In fact, words that take this form provide a vast number of 'family' names in the language. 'Cooper' as a name descends from a job name for the guys who make barrels.  There are far fewer barrel-makers in the world now, but piles of people who would tell you they are called Cooper.  So a washer washes and a waiter waits, but how about an usher?  To know why in the world the guy at the theater who guides you to your seat is call this, we have to fall all the way back to a time period when this was the word for a door keeper.  A door keeper and an usher in modern usage are two very different things, but the formation is the same even after all this time.  Now just look at yourself and see what you do.  If you know how to surf, write, eat, clean, read, sing and play, the formation is correct.  There are exceptions, of course, and too many to list.  As an example, remember that if you know how to edit and have edited, then you are an editor... because editors are special. User: HBKurtzwilde, 19:02, 7 September 2007 (UTC)

Correct usage of the term "maiden name".
Mr. & Mrs. Smith have a daughter, Mary. Mary marries Tom Hanover. Which of the following is correct?

Mary Hanover's maiden name is Smith.

Mary Hanover's maiden name was Smith.

Thank you,

M

 * I'd go with "was", since she is no longer a "maiden". StuRat 13:04, 16 July 2007 (UTC)
 * But her maiden name still is Smith? It's not like her maiden name has changed. I would go for is. 213.48.15.234 13:26, 23 July 2007 (UTC)

 * This is another Attack of the Situation question. Say you are filling out a form right this minute and have to know right now.  Mary's maiden name is Smith.  Perhaps in conversation someone wonders what her family name used to be.  Mary's maiden name was Smith.  This is just a distinction of present and past, so the format of the question will determine the usage.  This gets tricky when the question is implied, but the flow of the conversation is the best place to get your usage cue.  “What was Mary's last name before she married?”  “Her maiden name was Smith.”  “What is Mary's maiden name?”  “Her maiden name is Smith.”  If you're being asked in English, your conversational partner might drop you a hint.User:HBKurtzwilde, 19:02, 7 September 2007 (UTC)

Future Tenses
Can someone help me with the names of the two tenses in bold? I know they are the future but not sure of the names!!!

a) I'm going to do the shopping; do you want anything?

b) Could you get some washing powder and cheese and bread?

a) Ok, I'll go to the grocery store.

 * They are both the Future tense in English. A friend of mine getting his PhD in Linguistics tells me that the difference is one of assumed/non-assumed language, but the short answer seems to be that they're both just the Future Tense. The Jade Knight 06:13, 22 July 2007 (UTC)
 * (But if I were to invent names for them, I'd call them the Progressive Future (not to be confused with the Future Progressive) and the Simple Future. However, to my knowledge, these are not real tense names in English).  The Jade Knight 06:15, 22 July 2007 (UTC)

Euroenglish
With respect to this, how can they remove the letter c from the keyboard even if they replace the soft c with s and hard c with k. I mean they would still need c to spell change. Am I right??

Another question: Will Euroenglish be easier than the british english for new learners learning the language. I am sure native speakers will face a multitude of problems.--122.162.143.20 17:57, 5 September 2007 (UTC)

 * I'm afraid you've fallen for a prank. That is just a retitled version of Mark Twain's satiric A plan for the improvement of spelling in the English language: .  But, if one were to seriously undertake such massive changes, I would propose "kh" to replace the "ch" sound, temporarily.  He did propose a long term plan of bringing back the "c" but now using it exclusively for the "ch" sound.  So, "change" would then be "canj". StuRat 20:37, 5 September 2007 (UTC)

Polite English Business Reply
I'm looking for a polite way to acknowledge an e-mail for a business template. Someone at my work changed it to say

"Dear Sir/Madame

We acknowledge your below cited e-mail

We trust that the issue has now been solved.

Kind Regards"

I find this very impolite. Surely "Thank you for your e-mail dated...." would be a better way of aknowledging a business e-mail or letter.

Any suggestions would be greatly appreciated

 * "Thank you" is definitely more polite, but sounds a bit ingenuous if in reply to a complaint (which this sounds like it might be). It's like saying "I so enjoyed you telling me how poorly I do my job".  It comes off as sarcasm.  So, I would only say "thank you" for things where you might genuinely be thankful, like when a purchase order is received.  I think "We acknowledge receipt" is the best you can do for complaints, without sounding sarcastic.

 * Also, "Madame" is for French married women, I believe; it should be "Madam" in English. Better yet, just put the customer name in place of "Sir/Madam", since this avoids the unpleasant implication that you can't tell if they are male or female. StuRat 15:37, 23 August 2007 (UTC)

Sindhi Hindus Worldwide
I wish to know how many Sindhi Hindus migrated from Pakistan when India was divided in 1947. I am writing a book on immigrants and the subject is: Sindhi Hindus worldwide. A directory is also in making to show the names, addresses [old address in Pakistan with new address anywhere in the world], contact telephone no., contact email id:, and few lines of family background. all views, suggestions, and comments are most welcome. Kindly contact: Sunder Thadani [75 years old and one man army with a base in Bombay since 1948]  Best Wishes!

 * 1) This page is for questions on the use of the English language. A better place for this type of general question is the Wikiversity Help Desk: Help_desk.

 * 2) As for your question, this Wikipedia article claims that 1.2 million of 1.4 million total Sindhi Hindus migrated to India: Partition_of_India.

 * 3) Good luck on your book ! StuRat 03:46, 19 September 2007 (UTC)

language
[[Media:Example.ogg]]

what do you mean by BTW?
 * BTW = by the way
 * What i sthe purpose of the ogg file ? I can hear: "test" and "test reading". Erkan Yilmaz ( Wikiversity:Chat, wiki blog ) 17:26, 17 December 2007 (UTC)