The engineering tag has no wiki summary.
7
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1answer
2k views
How does a digital radio tuner work?
I believe I understand how tuning a radio with an analog tuner works: turning the dial physically changes the length of the antenna, which determines which broadcast wavelength will resonate in the ...
7
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4answers
774 views
Is the EmDrive, or “Relativity Drive” possible?
In 2006, New Scientist magazine published an article titled Relativity drive: The end of wings and wheels1 [1] about the EmDrive [Wikipedia] which stirred up a fair degree of controversy and some ...
6
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2answers
109 views
Would it be possible for geophysicists/geoengineers to develop an artificial way of trapping carbon in the ocean?
There's a mechanism by which the southern ocean sequesters carbon from the atmosphere. It happens when strong winds displace a large slab of surface water, accumulating in a specific region where the ...
5
votes
1answer
222 views
Water flushed down, water pumped up (in buildings)
I live in a tall building (20 floors) on a mountain. Because the water pressure from the water company is not enough, there is a water pump at the last floor which is activated each time someone is ...
5
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2answers
6k views
Hollow Tube Stronger than Solid bar of same Outside Diameter (O.D.)?
I was listening to some co-workers talking about problems meeting stiffness requirements. Someone said that even with a solid metal rod (instead of the existing tube) we could not meet stiffness ...
4
votes
1answer
111 views
Why do wind power plants have just 3 blades? [duplicate]
Why do wind power plants have just 3 blades? It seems that adding more blades would increase the area that interacts with the wind and gather more energy.
(Image from Wikipedia.)
4
votes
2answers
149 views
What properties would the ideal material for spacecraft construction possess?
Assuming we develop the capability to send a robot to study Gliese 518, or any of the Earth-like planets discovered in the neighbourhood; the spacecraft would need to travel through the Solar System ...
4
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4answers
963 views
Why do aircraft inner wings lose lift when turning?
first question here, so please be gentle!
I'm reading an entry-level engineering course book and am currently up to discussion of aircraft design.
There's one particular statement that is unclear to ...
4
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5answers
351 views
Tsunami dampening mechanisms
Encouraged by the zeitgeist let me ask the following:
Is it feasible (now or in the future) to build systems a certain distance of a vulnerable coastline which can serve to dampen a tsunami before it ...
4
votes
2answers
1k views
Shape of Fan Blades
How is the shape of the blades of an air fan determined? Trial and error, or is there a theory behind it? What are they trying to maximize, volume of air dislocated per rotation?
4
votes
3answers
243 views
Can anyone estimate what proportion of water remains after I flush a toilet?
Imagine I have a clean toilet with some amount of water in the bowl. When I flush the toilet much of that water will be displaced by the tank's water. I want to work out (or model really) what amount ...
4
votes
1answer
398 views
A conceptual problem with Euler-Bernoulli beam theory and Euler buckling
Euler-Bernoulli beam theory states that in static conditions the deflection $w(x)$ of a beam relative to its axis $x$ satisfies
$$EI\frac{\partial^4}{\partial x^4}w(x)=q(x)\ \ \ \ (1)$$
where $E$ is ...
4
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3answers
2k views
How do I calculate DC motor speed for a given load?
Suppose I have a robot of a given mass, and I'm choosing between 2 different wheels and 2 different motors to put on it. For each wheel I have the diameter, and for each motor I know the stall torque ...
4
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0answers
226 views
Why don't Turbojet engines use the De Laval Nozzle?
Why don't Turbojet engines use the De Laval Nozzle?
In fact, it seems that in a typical turbojet, the output nozzle contracts, not expands.
As the temperature of exhaust gases is high -- it should ...
3
votes
3answers
179 views
How to determine whether a large container is air-tight?
In constructing a kitchen-waste digester at home, I use a 50 Litre HDPE drum. The base of the drum is holed with a plug fitted to allow drainage when necessary.
The top has two openings - one for ...
3
votes
3answers
198 views
How does the shape (form; not cross-section) of a spring impact performance?
Cylindrical compression springs are everywhere and then some applications choose other forms like rectangular or unique polygonal form. What impact does the form of a compression spring have and how ...
3
votes
1answer
250 views
Tear drop shape
i heard that a tear drop shap is the most aerodynamic shape possible or the best is this true? If this isn't true what is since i need to make a fast ROV? Also since i need to have a propeller to ...
3
votes
1answer
166 views
How to estimate the Kolmogorov length scale
My understanding of Kolmogorov scales doesn't really go beyond this poem:
Big whirls have little whirls that feed on their velocity, and little whirls have lesser whirls and so on to viscosity. ...
3
votes
1answer
422 views
Air Turbulence and DIY laminar flow hoods
So for years on the mycology, plant tissue culture, and DIY laboratory websites there has been this ongoing debate on how to achieve laminar flow in a home built laminar flow hood.
Flow hood link!
...
3
votes
1answer
59 views
Amount of energy to separate Gases - relationship to concentration
I want to understand the efficiencies of separating mixed gases, and for that I want to understand the thermodynamic limit case. Looking at the wikipedia page for entropy of mixing, I find the ...
2
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4answers
748 views
Are quantum mechanics calculations useful for engineering?
I heard it's is pretty tough to get results for more than a few quantum particles. Are quantum mechanical calculations useful at all for any technology that is being sold?
Or do they use ...
2
votes
2answers
204 views
Piston movements in four stroke cycle?
I was reading about a four stroke cycle. Here's what I understood:
In the first stroke, the piston starts at the top and moves down.
In the second stroke, the piston moves upwards.
In the third ...
2
votes
3answers
142 views
Do processes $P\propto\frac{1}{V^2}$, $P\propto\frac{1}{V^3}$, $P\propto\frac{1}{V^4}$, etc., exist in the real world?
Is there any real process in which $PV^n=C$ where $P,V$ stands for pressure, volume respectively. $C$ is a constant and $n$ is a positive integer?
I am familiar with Boyle's law that states that ...
2
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2answers
109 views
How Safe Are Heat Ray Guns?
Could a little meddling with the frequencies of the Heat Ray Gun beam result in frying crowds rather than dispersing them?
2
votes
1answer
349 views
Equations instead of psychrometric charts
I want to create a program that will accurately simulate a condensor. I want to use the data in psychrometric charts. But I cannot and hence want to use equations that show similar data. Any idea ...
2
votes
1answer
314 views
How does holographic radar work?
I'm trying to figure out how the mechanics of holographic radar work.
AFAIK there is a continuous 3d transmission signal (a dome-shaped antenna?)
But because there isn't a direction or time-domain, ...
2
votes
3answers
505 views
Statics software for structural engineering
I'm attempting to expand my knowledge of engineering software. I've found comsol and ansys for acoustics and thermodynamics/fluid dynamics (not necessarily in that order), now I'd like to see if I can ...
2
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2answers
844 views
Angles on swing sets
I'm building a swing set for my children. All of the designs I've seen involve building two A-frames and connecting them at the top with a crossbar/beam from which hang the swings. The A-frames are ...
2
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0answers
89 views
Why did increasing the Ackermann geometry in my race car make it faster in corners?
Ackermann geometry is used to account for the different radius arcs that the front tires follow when the steering wheel is turned from center. It's often expressed as a percentage: e.g. 25% Ackermann, ...
2
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0answers
89 views
Internal moment in the hull of a pressure vessel
This question is related to the course structural analysis. As part of our exam grade every student has been given different multiple homework assignments which we have to solve.
One of the problems ...
2
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1answer
161 views
Compressible fluid flow through a branched pipe junctions
Backdrop: Designing a dust extraction system (LEV) with a branched junction.
What principles allow for the calculation of volume flow rate and pressure at the inlets if the volume flow rate and ...
1
vote
3answers
5k views
What is the difference between a moment and a couple?
In mechanical engineering, the torque due to a couple is given by $\tau = P\times d$, where $\tau$ is the resulting couple, $P~$ is one of the force vectors in the couple and $d$ is the arm of the ...
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3answers
367 views
Can I study Quantum Computing or Quantum Mechanics with an Engineering background?
Sir,
I am studying Electrical & Elctronics Engg. now. I wish to pursue Quantum Mechanics or Quantum Computing as my research subject. Is it possible for me to do my M.Tech. & then pursue ...
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3answers
2k views
Factors affecting torque and RPM of a motor
I'm not a physics guy, not even basic concept of a DC motor is easy for me. My question is, how these parts of a motor affects it's RPM and Torque? I had my research a while ago so I filled out some, ...
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3answers
1k views
Could a real-life X-Wing fly in Earth's atmosphere?
From an aerodynamic point of view, could a full-size aircraft of X-Wing design fly in Earth's atmosphere? Assuming you were free to add control surfaces here and there, could the wings in open ...
1
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2answers
259 views
History of the use of the concept of phase space in engineering
Engineering textbooks constantly use the concept of 'phase space' (see e.g. http://www.cs.cmu.edu/~baraff/sigcourse/notesc.pdf). That is, they think of the state of a mechanical system as a ...
1
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1answer
90 views
How to interpret a negative failure rate?
In statistical engineering the "hazard rate" of a distribution is defined as:
$$r(x)=\frac{f(x)}{1-F(x)}$$
where $f(x)$ and $F(x)$ are the PDF and CDF. Basically $r(x)$ is the odds that, having ...
1
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4answers
309 views
What is a strain gauge and how do I use one?
As the title says, I have no idea what these things are or how to get or use one. Can I receive a simple explanation or links to one? I'm a computer engineer so I have very little physics/mechanical ...
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2answers
558 views
Calculate the weight a simple plank can support
I'd like to build a simple desk; just a single plank of wood (or a few side-by-side) with solid supports on each end of the desk. What I'm trying to figure out is how thick a plank I want to use for ...
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2answers
161 views
Can someone explain the Hall effect thruster to me?
I am in high school, and am doing a major research project on Russia. Part of that is a section on the space race, and ion engines/hall effect engines have come up several times. Unfortunately, Google ...
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vote
2answers
2k views
The most efficient Fan Blade Design
What could be the most efficient fan blade design? There are three main factors for a good fan: one is speed at which air is circulated; second,the volume of air it can circulate; and the third is ...
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vote
2answers
1k views
How do I find the Gain of this Transfer Function
I found the transfer function for the spring mass damper system to be
$$G(s)=\frac{1}{ms^{2}+bs+k},$$
and now I need to find the gain of this transfer function. I know that the gain is ...
1
vote
1answer
83 views
How to find the value of the parameter $a$ in this transfer function?
I am given a transfer function of a second-order system as:
$$G(s)=\frac{a}{s^{2}+4s+a}$$
and I need to find the value of the parameter $a$ that will make the damping coefficient $\zeta=.7$. I am not ...
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2answers
182 views
Fluid flow through a diverging pipe
Relevant diagram loosely based on my real problem:
Description of problem: A fan creates a pressure sink that drives fluid flow through a gently diverging pipe (please note that the diagram is not ...
1
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2answers
140 views
Total Mechanical Advantage
How do you find the net Mechanical Advantage (MA) of two joint machines. Do you add or multiply the individual MA?
Suppose I have two sets of wheel and axle connected by a fixed pulley. Each of the ...
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0answers
294 views
propeller flying physics for the layman
I'm starting a (quad?)copter build, and i can find plenty of knowledge about stabilizing the craft and things related to gyroscopy.
but there's absolutely zero information on things that help me ...
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0answers
93 views
Can a the volume flow through a positive displacement pump be reliably measured by tracking revolutions of the drive shaft? [closed]
The question refers to non-compressible fluids.
I'm mostly thinking about monopumps (excentric screw pumps), but this also should apply to any type of gear pumps as well, possibly also to piston ...
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0answers
154 views
Centrifugal Compressor Flow Rate
For a centrifugal compressor, as found in most turbochargers on internal combustion engines, is there a noticeable change in flow rate versus a naturally aspirated flow rate? In other words, does the ...
1
vote
1answer
209 views
How to find the value of the parameter a in this transfer function? [duplicate]
Possible Duplicate:
How to find the value of the parameter $a$ in this transfer function?
I am given a transfer function of a second-order system as:
$$G(s)=\frac{a}{s^{2}+4s+a}$$
and I ...
1
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0answers
75 views
Simplifying a biquadratic filter equation [closed]
I am trying to calculate input impedance of a multiple feedback low pass filter. What I need is the symbolic expression as simple as possible so that later I fill in the values and get the impedance ...
