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1500 questions
7
votes
2 answers
Modelling splashing water in FEA
I'm running an FEA on a vessel that has a "splashing water" effect with vibrations. The problem I'm really coming up against is what kind of Young's Modulus and Poisson's ratio to use for the fluids? - air and water. I have been successful in…
Mark
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A clarifying question on Lasalle invariance principle
Given a nonlinear system \begin{equation}
\dot{x}=f(x),~x(0)=x_0 \tag{1}
\end{equation}
where $f\in{\mathcal{C}^{1}}:D\to\mathbb{R}^{n}$. The Lasalle invariance theorem statement goes as follows:
Let $\Omega\subset{D}$ be a compact set that is…
jbgujgu
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7
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What is "flow instability" in porous media?
Pressure drop across a porous medium can be described by the Forchheimer extension to Darcy’s law:
$$-\frac{dp}{dx} = \frac{\mu}{K_1}\cdot v + \frac{\rho}{K_2}\cdot v^2$$
where $K_1$ and $K_2$ are permeability coefficients that depends on medium…
Algo
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7
votes
1 answer
(Non)simultaneous prestressing anchorage slip losses
Post-tensioned prestressed concrete beams suffer from a multitude of losses. When jacked, they suffer friction losses and their tension diagram is, for example (to simplify the drawing, I'm using the linearized version of the friction loss equation…
Wasabi
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7
votes
1 answer
How should the welded corner of this bracket be detailed?
Consider the design of the bracket shown in the figure below (it is assumed that the anchors are sufficient and are not considered below).
My question concerns the detailing of the welded connection detail and the overall strength of the bracket.…
egg
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7
votes
1 answer
Settling of unevenly loaded storage tank
Suppose I have a concrete tank, round, vertical, diameter in the range 16m-24m. One half the floor is filled with gravel or concrete to a height of maybe 2 meters. When the tank is empty, that will mean I have about 5 tons per m² more weight on this…
mart
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7
votes
2 answers
What is the difference between using separate lathe and mill or a combination machine?
I'm interested in metalworking as a hobby, to make small parts for my numerous other hobbies. I'm looking at those cheap, typically Chinese import mini-lathes and mini-mills. I've read about their limitations as compared to larger machines; this…
Kevin Krumwiede
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7
votes
4 answers
What is the maximum angle of a shelf angled brace?
So suppose I want to make a single shelf protruding from a wall and to place a heavy object on it (Figure 1). A shelf like this would fail (assuming no internal mounting that penetrates into the wall).
As such, in an ideal scenario, I would want…
Davbog
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7
votes
1 answer
Calculating the ultimate achievable vacuum pressure of a diaphragm pump
I am looking to design a diaphragm pump for a device. I know that I would need to achieve a (negative) vacuum pressure of ~ 350-400 mmHg. I know from standard rotary pump design the pump rate should be dictated by stroke volume and speed, and…
daFireman
- 71
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7
votes
3 answers
Stiffening of Tesla turbine rotors
Recently I've begun thinking about experimenting with the construction of a Tesla turbine for steam use. The key issue I can find is that most of the examples out there of such turbines use either optical discs or HDD disks to make the actual…
ecfedele
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7
votes
2 answers
How can I calculate the force required to bend a 10 mm thick plate in a rolling machine?
We have a rolling machine with 3 rollers; the bottom has two rollers with diameters of 168 mm and one top roller with a diameter of 219 mm. I want to calculate the required force to bend a 10 mm thick plate which is 2,500 mm wide. The rolling…
Hardik Adroja
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7
votes
5 answers
How to identify low quality electronic components early?
Our component sourcing organization purchases large amount of electronic components from suppliers. I believe this is through a bid process. Engineering provides the sourcing organization specification, and they purchase these parts for the plant to…
user1586
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7
votes
2 answers
Calculation of the stored energy for a heat storage tank
There is a heat storage tank that is directly loaded from the top and the heat is also taken from the top.
The colder water from the heating circuit return flow enters the heat storage tank at the bottom. This creates a layered water temperature in…
Emma
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7
votes
3 answers
How are earthfills not eroded before they are overgrown with grass?
Almost every railroad and vehicle road landfill has its slopes overgrown with grass which is quite good at preventing erosion. However it takes some time (a year or more) for the grass to grow and emit enough roots to form a reliable mesh that would…
sharptooth
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7
votes
3 answers
What is the best way to control brightness of a LED?
LED brightness can be controlled using digitally controlled potentiometer such as a Microchip MCP413X or a PWM signal. In both cases the signal will be controlled/ generated from a micro-controller. Which method is better using a digitally…
Mahendra Gunawardena
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