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2answers
881 views

Why oil is used as lubricant in hydro, wind power generators, while water is the most available, cheapest and accessible lubricant?

The lower viscosity of water, reduces the friction, besides the water can transfer heat way better than oils, so why not using the water as a lubricant in wind or hydro turbines, specially on those ...
0
votes
0answers
4 views

What object characteristics may cause significant distance measurement deviations in Sharp optical sensors?

Not sure if this is the right place to ask this question, but anyways. I'm not very fond of circuits and stuff, but I've got a test question I really need to answer. The question is in the title, ...
0
votes
1answer
74 views

Not solvable question civil engineering

They didn’t give me the radius of the wheel where external force F is acting . How can I calculate the reactions at A,B . When they didn’t give me the radius . Is this question “ Wrong “ ? Note ...
0
votes
0answers
6 views

Thermal radiation measurements: Looking for ~100 Hz BW, broadband (1-20 um) NIR/MIR detector

I am looking for a detector with about 100 Hz bandwidth, that has broad and ideally uniform absorbtance in the 1-20 um range. I need to be able to pickup signals in the 1 uW range with SNR >10, ...
0
votes
0answers
7 views

Name of this type of platform lift

There's a simple way to lift a platform a short distance: Identical discs are mounted on a frame at the four corners of a platform such that front pair of discs' axes of rotation are colinear, as are ...
0
votes
1answer
24 views

Where do I get basic mechanical components?

I'm looking for a few basic devices such as converting translational to rotational motion, 20:1 gearbox, etc. Found nothing at Home Depot. Could you suggest where does one buys/orders such components?
0
votes
1answer
35 views

installing swing hook before concrete is poured

I want to place a swing hooks in place before the concrete is poured so that , i dont have to drill a hole later. My contractor is not ready to make these bolts with TMT bars itself.. what kind of ...
2
votes
1answer
66 views

How to analyze a bent beam: Stress concentration?

I am analyzing a beam, that has a bend in it. Intuitively and inspecting FEA results using a linear solver, there is a stress concentration at the bend of this I-beam. When I was learning about ...
0
votes
1answer
38 views

Is there a standard for where treelines are drawn?

On surveys and site plans, I've often found treelines. These look like the below image, and serve to delineate in a very approximate way the areas full of trees and those that aren't: Is there a ...
1
vote
2answers
19 views

Turn rate of a jet vs. biplane

A friend and I were debating whether a biplane/propeller plane has a faster turning rate than jet aircraft. I argued that the propeller planes often do have better turning rates than jets, but I could ...
0
votes
0answers
16 views

What is the mathematical basis for the Ziegler-Nichols method for tuning a PID loop?

The Ziegler-Nichols method of tuning PID control loops has been around since the 1940's, and has been widely applied in many areas of engineering. I understand that it is really only a heuristic ...
0
votes
0answers
9 views

How can I model a hysteresis curve from data?

I have the task of modeling the current to torque mapping for a given motor. I have an experimental set up where I can retrieve current, torque pairs. Now my initial approach was to model the ...
0
votes
1answer
14 views

Using RC scale-down model to pre-test aircraft design

I'm a bit involved into building an actual airplane. And while the guys go conventional ways, I'm trying to look around to see other solutions. One of that is to try and use and RC scale-down model (...
1
vote
1answer
31 views

What is the mechanism of adsorption-desorption on biochar obtained from slow pyrolysis/ torrefaction?

Biochar is a major by-product from pyrolysis along with bio-oil and it is considered an important chemical feed-stock because of many light oxygenates. I have read some papers on using bio-char use ...
0
votes
1answer
40 views

Simple steel column buckling calc - where am I going wrong? (Eurocode)

I'm trying to follow an example of this, but I get a wildly different answer than expected and I can't see where I'm going wrong. The example I've got, is for a 2.8 m steel column (RHS 150 x 100 x ...
0
votes
1answer
27 views

how does this z-axis micro-adjust lead-screw design work

The picture (which I found on the web without any accompanying explanatory text) shows a home-made z-axis micro-adjust lead-screw add-on to the vertical milling attachment of a vintage hobbyist lathe. ...
1
vote
1answer
53 views

Can magnetic stripes be read wirelessly with lasers or other technologies?

I know that magnetic stripes used in credit cards and audio tapes are typically read by a magnetic reader head. But is it theoretically possible for the stripe to be read by a laser in a similar ...
0
votes
0answers
40 views

How fast could a Mini Cooper go in a vacuum?

Lord Evulz just stole the Earth's atmosphere. Our hero must race his trusty old Mini - which he had already prepared to be airtight, to ensure the tires do not explode, with pre-packaged oxygen to ...
0
votes
1answer
19 views

Transfer function for a quadcopter with linear velocity inputs

I found the control for a quadcopter using the angular velocities or thrust power as the input, but I need a model where I can set the initial and final position (for example, from (0,0,1) to (0,1,1))....
0
votes
0answers
13 views

What would be the surface area of a boiler that has a heat input of 850 MW from combustion? [on hold]

The rate at which heat is supplied the boiler is 850MW which is attained by burning 20Kg/s of natural gas. Heat losses by convection are to be calculated but the surface area is unknown. So how to ...
0
votes
0answers
43 views

Delta Robot: Torque and Motor Sizing

Question: Is 56 Nm enough torque for a delta robot with the below dimensions and specs? If not, what would be the minimum torque needed? Thank you in advance for your help. I am working on a rotary ...
0
votes
1answer
48 views

How to derive phase equillibrium criteria for more than 2 phases mathematically?

I know the derivation of phase equilibrium criteria derivation for 2 phases. I am not getting how to extend the derivation to more than 2 phases. Please help me out on that. Thank you
0
votes
2answers
22 views

Why torsional warping does not occur for shafts with circular symmetry?

When we twist a shaft/beam/rod, shearing stresses are produced. The angle by which the end of the shaft rotates can be found as: $${\displaystyle \theta ={\frac {TL}{GJ}}}$$ where $T$ is torque, $L$ ...
0
votes
1answer
39 views

Orthogonal to Orthoradial reinforcement

Most of finite element calculations are performed with an orthogonal mesh (Cartesian coordinate system). From this calculation, we get two values of required steel area per linear meter: $Ax, Ay$ ($cm^...
5
votes
1answer
217 views

How to make a conductive paint over PDMS?

Conductive paint by conventional technique using gum and graphite powder does not stick to the PDMS surface and comes off once the paint dries. How else can I make a conductive connection over the ...
0
votes
0answers
18 views

why do they put a ring on a planetary gear and why dont they turn it with a gear in the middle

why do they put a ring on a planetary gear why don't they just put a gear in the center I want to know if the ring adds torque thank you if anyone knows
2
votes
7answers
4k views

What is the opposite of “parallel” in engineering?

The two towers of the Verrazano Bridge are not parallel: they are [???] to account for the curvature of the earth. What is that word?
0
votes
1answer
29 views

Consequences of Inextensibility of an in-plane line in Euler-Bernoulli Beam Theory

The Euler-Bernoulli beam theory is based on the hypothesis that the beam deforms such that a straight line normal to the beam axis before deformation remains inextensible straight normal to the beam ...
0
votes
0answers
16 views

How to calculate how many solar panels can be connected to one inverter?

I am a bit confused about inverter specs, and most sources online seem to focus only on the power ratings. As far as I understand, if an inverter is rated at 100kW, and a solar panel is able to ...
3
votes
2answers
54 views

Why rectangular windows are so common?

Most of the windows in our rooms are mostly rectangular.Why don't we chose any other shape like circle,triangle or a trapezium.Does it affects airflow through room? Is the reason is that they look ...
0
votes
1answer
21 views

Normal Force distribution of Prism

On the image below there is a regular prism which is angled by $\alpha$. The (black) mass m1 applies a torque $M_k$. The mass m2, which is the rest of the Body applies the torque $M_s$ In the ...
7
votes
1answer
2k views

Calculate effort to raise hinged lever with distributed load

My father-in-law would like to install a hinged stair system in his garage that allows him comfortable access to his attic space. He wants the stairs to swing up flush with the ceiling when not in ...
0
votes
1answer
28 views

Arc subtended by stretching of a conical spiral spring

I'm trying to work out the angle subtended by the stretching of a conical spring and I have a solution but I'm not 100% sure about it so would appreciate some feedback. An Archimedes spiral spring is ...
1
vote
3answers
29 views

Huge gap between ceiling and floor above

I guess this question would belong on an architecture page if Stack had one. There is a 5 story building I was in recently that had fairly low ceilings (maybe about 8 feet) and a huge gap between ...
8
votes
7answers
7k views

Why is hydro-electric power still scarce in some places?

70% of the Earth's surface is covered in water, why can't a hydroelectric power plant be set up on each and every river? Is it that its too expensive? Why is electricity still a problem in countries ...
1
vote
1answer
33 views

Unit of Angular velocity of Precession [duplicate]

Since the Equation for the Angular velocity of Precession of a Spinning Disk is: $$\omega _{p}=\frac{m*g*r}{I*\omega _{spin}}$$ Where, m -> Mass of the spinning Disk. [$kg$] g -> ...
1
vote
1answer
17 views

what impact does drop height have on powder segregation?

In the pharmaceutical environment, the drop height from the hopper to the area where it collects must be minimized. Tubes can be used to minimise the height. I know that it affects powder segregation. ...
-1
votes
0answers
17 views

Solution of st venant equations using fortran

I tried to write code to solve st venant continuity and momentum equations in FORTRAN 90, with given slope and rainfall and find out the discharge. But I stuck in the procedure to find overland flow ...
0
votes
0answers
8 views

How does plant evapotranspiration reduce the required size of a chiller used to control the climate of an indoor farm?

When HVAC companies estimate the required size of a chiller unit for a greenhouse or an indoor farm, they reduce the estimated load by plant "transpiration cooling." I understand how transpiration ...
0
votes
0answers
28 views

Why is there no widely-used standardized unit for indentation hardness?

The last hundred years have seen a great degree of standardization of units, and the expression of units of measurement in standardized, instrument-agnostic, objective terms, often in the SI units. ...
2
votes
1answer
71 views

Buying Liquid Oxygen in Small Quantities

I am trying to work out costs and order parts for a small liquid fuelled rocket I have designed. My oxidiser is liquid oxygen but I can’t seem to find anywhere to purchase it on the internet. Does ...
0
votes
1answer
29 views

How to read the block diagram for the 2nd order integrator feedback system?

This is a prework for a lab, I haven't seen things in the picture before and have no idea on how to transfer this to an equation.
0
votes
1answer
37 views

Headlight auto-dimmer in newer cars

My RAM truck has a feature that intrigues me and I want to know how it works. In auto-dimmer mode, the truck will automatically put on low beams headlights when there is on-coming traffic at night, ...
0
votes
1answer
75 views

Installing satellite dish to point to local zenith

After receiving help on my previous post (Stopping/reducing wobbliness in threaded rod), I've decided to come back and ask another question: how can I actually hold the satellite dish into place? I ...
0
votes
1answer
24 views

Fluidic muscle in reverse, as a pump. Does this exist?

A fluidic muscle is a pneumatic or hydraulic actuator, consisting of a flexible tube. When the tube is filled with a working fluid (pressurized air or hydraulic oil), it balloons out and shortens. In ...
3
votes
2answers
63 views

Heat transfer coefficient of a cylindrical hot water storage tank depending on its size

I have a simulation model of a cylindrical hot water storage tank. The heat loss is determined by the surface area and the heat transfer coefficient. A configuration of the storage tank with 900 ...
0
votes
1answer
40 views

The elastic module for a paper bridge

I have build my own bridge from paper and i want to know the elastic module for the bridge, my bridge is flat all over the way and cylindrical from the sides.
3
votes
3answers
88 views

Determine surface area of arbitrary physical object

Assume a physical object with arbitrary shape whose dimensions are on the order of 1 meter. How would one measure the surface area of the object? There may be many reasons for determining the surface ...
0
votes
0answers
12 views

N2O/Kerosene Rocket Fuel

I am interested in building a small liquid fuel rocket and I have decided to use nitrous oxide and kerosene as the oxidiser and fuel respectively. I would like to know if anyone has any advice ...
0
votes
1answer
19 views

compute the maximum resisting torque that can be overcome by the system at the shaft axis

A 2Nm motor M is used to drive the system through a gear drive and a chain drive. the overall reduction ratio is to be between 16:1 and 18:1, and at an output speed of 6rpm.

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