I try to understand how to input material properties using engineering constants for VTI material ( vertical transverse isotropic) with direction 3 being vertical direction. Does anyone has inp example showing how to input these material properties? For example, I don't know how to input nu12, n13? Thanks
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As for transversely isotropic materials you have to provide 5 different parameters (I don't know what the vertical means, I never read this before).
For the convention on the poissons number please see Abaqus online documentation - conventions.
For your example. You should usually have one "master" direction (englisch is not my first language). And you have a plane perpendicular to this which has rotational symmetry. If your 3-direction is this (maybe the direction in which fibers are oriented) then your E11 and E22 values should be identical. Furthermore two of your possion numbers in your case 31 and 32 (prependicular/parallel sometimes called). Also the same directions of shear modules have to be identical.
The last shear modulus can be obtain via
G = E/2(1+nu) where E must be prependicular E modulus (2,1) and the poisson number must be the prependicular one (21)
Your constants: E33, E22=E11, nu31=nu32, nu12, G31=G32 , calculate G21 from above equation
For clarification
from H. Schürmann - Konstruieren mit Faser-Kunststoff-Verbunden (construction with fiber reinforced materials)
NOTE: In this picture the 1 direction is the parallel direction where fibers are oriented, adjust it accordingly or follow what i wrote above.
Related
I am trying to solve with Comsol the problem of the figureTwo blue big electrodes with fixed potentials V1,V2. One red small electrode that moves above the others along x axis at constant distance and voltage V0. The charge in V0 depends on the electric field at each point 8(x). I have one small electrode with a potential V0 moving along x axis above two bigger electrodes with fixed potentials V1,V2.
I can easily compute with comsol the potential and field at each point in 3D and the resulting charge in V0 electrode. However i would like to simulate this charge along the x axis and eventually map it also for z and y direction so i have a V0 charge 2D map at a fixed distance.
How can i do this in COMSOL without changing the geometry coordinates manually and computing again the charge at each point?
Thank you for your answers,
Jorge
I'll describe how to setup the system so that you can move V0 around. Note that this requires changing the mesh throughout the simulation. For this reason, I don't think you want a "time dependent" study but instead you want to use the "parametric sweep" option.
First, go to your Global Parameters and create a parameter called block_x_pos or whatever you want.
Go to Component → Geometry and select V0 and in the appropriate field under the "Position" tab (in the Setting Panel), write block_x_pos in the X Position. This makes that position controllable by whatever value is in block_x_pos.
Right click on the appropriate Study and select "Parametric Sweep". The purpose (as far as I know) for the Parametric Sweep is that when the geometry is changing during computation, it updates the mesh accordingly, so you don't have to do it manually through some painful repetition. Select the "Parametric Sweep" node which has now appeared. Look in the Settings Panel and find the "Study Settings" tab. Below the empty table, you'll see some arrows and a "+" sign. Click the "+". This will add a new sweep parameter to the table. Click the dropdown menu on the table and select the "time" Global Parameter. In the "Parameter Value List" field, write the range of values you'd like to have it take.
i.e. if you want the block_x_pos parameter to vary from 0 to 10 in steps of 0.1, you would write range(0, 0.1, 10). Or you could write '-3 0 1 2 4 5 9 11' and it will take those values.
Now Compute using that same Study.
When you are making plots, be sure to use the correct Solution. It will be labeled something like "Study1/ParametricSolutions1". When you select this as your "Data Set", you will find (in your Settings Panel) a new dropdown menu below the "Data Set" field called "Parametric selection (time)". You can choose to show multiple values for the "time" parameter on most plot types.
SCENARIO
I am working on an application that keeps track of blood glucose levels into a graph. On the graph there are "markings" (ex: -200mg) going in vertical order along the y axis on the right side of the screen and "hours" (ex: -12:00 PM) will be along the x axis on the bottom of the graph. I have to plot out little 'dots' to display what the blood glucose level was throughout the way.
ISSUE
I am trying to calculate how to position the 'dots' in the correct time and mg level and I'm having difficulty calculating the positions. I can access the "markings" and retrieve it's marking.center.x to indicate which 'Time Slot' (x axis) and the marking.center.y to indicate which 'MG Level' the 'dot' needs to go into. Problem is it isn't always exactly 12:00 PM or 200mg where it will need to be placed. In fact that would be very rare.
WHAT I NEED
Based on the following variables:
dot.mgLevel
The dot will already know where it needs to go based on the information retrieved from the medical device. It will know the time and mgLevel to assign itself.
marking.mgLevel
The markings will each have evenly distributed values that such as -100mg, -200mg, -300mg ect...
timemarking.timeslot
Each time marking on the bottom will each have evenly distributed times allocated every 30 min. Such as -12:00PM, -12:30PM, -1:00PM ect...
If the dot has a mg Level of 330mg and the closest marking on the mg Level is 300mg, then I need to be able to calculate how much further up the dot needs to move from 300 going towards the 400mg marker.
SO...
If the distance between the markings are 100pt and the dot's mgLevel is 330mg, then I know that I need to move the dot from the 300mg marking toward the 400mg marking by exactly 30pt. That's because it's simple math because the distance between the markings is 100. But in real life it isn't 100, so I need to be able to calculate this.
MY ULTIMATE QUESTION
Say distance between markings is 241 and each marking represents multiples of a hundred. Say my dot has a mgLevel of 412. How do I calculate how far I need to move the dot so that it will be in the correct place?
I THINK?
I think I need to make 241 equal 100%. But I need help.
Distance between markings is 241pt
Markings are multiples of 100mg
1mg will occupy 2.41pt. So 412mg will occupy (2.41 * 412) pt. To know how much to move for the next dot, take the difference in mg and multiply by 2.41.
In general, if distance between 2 markings in points is d, markings are multiples of m, and desired accuracy is k decimal places, 1mg will occupy g:
let divisor = pow(10.0, Double(k))
let g = round((d/m)*divisor) / divisor
I have a slide with some hand-drawn circles on it. I'd like to get a list of the coordinates and radii (sizes) of them. Attached is an image and link. Anyone have an idea how?
I started looking into computer vision techniques, but it seems like there should be a much more direct way.
If you are familiar with openCV the method HoughCircles() will do the job:
http://docs.opencv.org/doc/tutorials/imgproc/imgtrans/hough_circle/hough_circle.html
Are you familiar with Matlab? imfindcircles() will do it:
http://www.mathworks.com/help/images/ref/imfindcircles.html
If this is a one time job you can post it as a job for someone else to do it for you for a small fee. Example: https://www.mturk.com/mturk/welcome
If you don't know any programming language and this is a one time job, you can do it manually. You can select each circle in photoshop, count the amount of pixels (and using the formulae of circumference = 2*pi*radius) find the radius. The center of mass of all the pixels will be the center of the circle.
It is a bit tricky to separate overlapping circles but you can do it by hand
I found a suitable method using vector graphics.
Select all the circles in powerpoint, right click and 'save as a picture'. Use .emf (windows metafile) format (this option was only available on my windows machine, not mac).
Open the emf file in inkscape, and save it to an 'svg' format, which is ascii and human readable.
Extract the information from the path commands.
E.g.: Each circle is represented as a path object, with a line:
d="m 36.527169,36.434607 c 0,-9.696733 9.075703,-17.551993 20.274845,-17.551993 11.194626,0 20.270329,7.85526 20.270329,17.551993 0,9.69264 -9.075703,17.552246 -20.270329,17.552246 -11.199142,0 -20.274845,-7.859606 -20.274845,-17.552246"
Here, the (x,y) following the 'm' character is the center of the circle, and the 12 (x,y) pairs following 'c' denote a 4-segment polybezier curve in which pairs 3,6,9,12 are the four compass points. Therefore in the above object, this is not a circle but an ellipse with axes ~ 20.27 and 17.55.
Has anyone been able to do spatial operations with #ApacheSpark? e.g. intersection of two sets that contain line segments?
I would like to intersect two sets of lines.
Here is a 1-dimensional example:
The two sets are:
A = {(1,4), (5,9), (10,17),(18,20)}
B = {(2,5), (6,9), (10,15),(16,20)}
The result intersection would be:
intersection(A,B) = {(1,1), (2,4), (5,5), (6,9), (10,15), (16,17), (18,20)}
A few more details:
- sets have ~3 million items
- the lines in a set cover the entire range
Thanks.
One approach to parallelize this would be to create a grid of some size, and group line segments by the grids they belong to.
So for a grid with sizes n, you could flatMap pairs of coordinates (segments of line segments), to create (gridId, ( (x,y), (x,y) )) key-value pairs.
The segment (1,3), (5,9) would be mapped to ( (1,1), ((1,3),(5,9) ) for a grid size 10 - that line segment only exists in grid "slot" 1,1 (the grid from 0-10,0-10). If you chose a smaller grid size, the line segment would be flatmapped to multiple key-value pairs, one for each grid-slot it belongs to.
Having done that, you can groupByKey, and for each group, calculation intersections as normal.
It wouldn't exactly be the most efficient way of doing things, especially if you've got long line segments spanning multiple grid "slots", but it's a simple way of splitting the problem into subproblems that'll fit in memory.
You could solve this with a full cartesian join of the two RDDs, but this would become incredibly slow at large scale. If your problem is smallish, sure, this is an easy and cheap approach. Just emit the overlap, if any, between every pair in the join.
To do better, I imagine that you can solve this by sorting the sets by start point, and then walking through both at the same time, matching one's current interval versus another and emitting overlaps. Details left to the reader.
You can almost solve this by first mapping each tuple (x,y) in A to something like ((x,y),'A') or something, and the same for B, and then taking the union and sortBy the x values. Then you can mapPartitions to encounter a stream of labeled segments and implement your algorithm.
This doesn't quite work though since you would miss overlaps between values at the ends of partitions. I can't think of a good simple way to take care of that off the top of my head.
I have a device that is taking TV screenshots at precise times (it doesn't take incomplete frames).
Still this screenshot is an interlace image made from two different original frames.
Now, the question is if/how is possible to identify which of the lines are newer/older.
I have to mention that I can take several sequential screenshots if needed.
Take two screenshots one after another, yielding a sequence of two images (1,2). Split each screenshot into two fields (odd and even) and treat each field as a separate image. If you assume that the images are interlaced consistently (pretty safe assumption, otherwise they would look horrible), then there are two possibilities: (1e, 1o, 2e, 2o) or (1o, 1e, 2o, 2e). So at the moment it's 50-50.
What you could then do is use optical flow to improve your chances. Say you go with the
first option: (1e, 1o, 2e, 2o). Calculate the optical flow f1 between (1e, 2e). Then calculate the flow f2 between (1e, 1o) and f3 between (1o,2e). If f1 is approximately the same as f2 + f3, then things are moving in the right direction and you've picked the right arrangement. Otherwise, try the other arrangement.
Optical flow is a pretty general approach and can be difficult to compute for the entire image. If you want to do things in a hurry, replace optical flow with video tracking.
EDIT
I've been playing around with some code that can do this cheaply. I've noticed that if 3 fields are consecutive and in the correct order, the absolute error due to smooth, constant motion will be minimized. On the contrary, if they are out of order (or not consecutive), this error will be greater. So one way to do this is two take groups of 3 fields and check the error for each of the two orderings described above, and go with the ordering that yielded the lower error.
I've only got a handful of interlaced videos here to test with but it seems to work. The only down-side is its not very effective unless there is substantial smooth motion or the number of used frames is low (less than 20-30).
Here's an interlaced frame:
Here's some sample output from my method (same frame):
The top image is the odd-numbered rows. The bottom image is the even-numbered rows. The number in the brackets is the number of times that image was picked as the most recent. The number to the right of that is the error. The odd rows are labeled as the most recent in this case because the error is lower than for the even-numbered rows. You can see that out of 100 frames, it (correctly) judged the odd-numbered rows to be the most recent 80 times.
You have several fields, F1, F2, F3, F4, etc. Weave F1-F2 for the hypothesis that F1 is an even field. Weave F2-F3 for the hypothesis that F2 is an even field. Now measure the amount of combing in each frame. Assuming that there is motion, there will be some combing with the correct interlacing but more combing with the wrong interlacing. You will have to do this at several times in order to find some fields when there is motion.