All Questions

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0answers
5 views

Help me Solve this Steady State 2-D Heat equation

So I tried to solve this PDE by separation of variables which was not applicable because of non-homogeneous nature of this PDE. Then I assumed ( after reading from a book ) : $$ T(x,y)=v(x,y) + \phi(...
0
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0answers
16 views

What are the design principles for risers in sand casting?

Risers are added reservoirs used to feed liquid metal to solidifying casting. In the case of alloys that shrink during solidification (this is not the case of all alloys), one uses such reservoirs to ...
1
vote
1answer
35 views

How can batteries in electric cars charge at such a high rate?

If I were to look at "normal" batteries online, they often have charging C-rates of much less than 1. However, with an electric car that uses regenerative braking, obviously such a low charging rate ...
0
votes
2answers
23 views

Is a 1/8" AR400F steel plate strong enough, for 4,000 lbs?

I have a Ford F350 cab & chassis and a gooseneck trailer. For the gooseneck hitch I want to use a steel plate. The steel plate will be BOLTED to the frame, above the rear axle And the gooseneck ...
0
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0answers
21 views

How to design a coaxial 1:2 gear without reversing direction?

I am trying to design a gear that has a 1:2 speed ratio (input:output). This design is very limited in space and for simplicity and space savings requires the input and output shafts to be coaxial. ...
0
votes
1answer
13 views

What Is the Different Between Single Nipple, Double Nipple, and Pipe Nipple

I just work on the engineering company that specialize in water piping. I am confuse about the term of nipple. What is the different between Single Nipple, Double Nipple, and Pipe Nipple? Hope ...
0
votes
1answer
34 views

Is there a motor design where a rotor gradually moves into a stater?

I was wondering if there is a motor/generator design where the rotor moves gradually in and out of the stator along the axis of rotation, or the stator over the rotor. If so, I'd like some resource(s)...
0
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0answers
3 views

Is there a formula to relate the axial length of a nozzle expander with its radius?

I know the inlet, throat and outlet areas for a nozzle expander. Is there a formula to know its axial length? Something like L= f(A) = f(D).
0
votes
1answer
24 views

What height is needed to drop a 72 kg mass to impart a 5000g shock onto a test piece

I am trying to design a simple drop / shock testing machine. We want to rate our products to be shock rated to 5000g. In order to test our products to 5000g I plan on dropping a weight onto the ...
0
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2answers
33 views

What equation are we using to describe forces in FEA?

Engineers often use Finite Element Analysis software to solve for stresses inside complicated structures to generate pictures like the one above. I am familiar with FEA as a method to solve ...
0
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0answers
16 views

Using a rotational latch to restrain an object under a horizontal force

So hypothetically, I'd like a to build a latching system to prevent a steel block experiencing a horizontal force from moving until another upwards force releases a latch, at which point it would ...
0
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0answers
16 views

About method of work and Energy or Clapeyron theorem

I'm having some difficulty to understand the work and Energy method (aka Clapeyron theorem), especially with different loads. Could you please help me to fix this problem, because I found different ...
0
votes
1answer
15 views

the volume in hydraulic retention time is of reactor/container or liquid

I have a tiny reactor, and the volume I need is 425ml. If there is no/few other reactants, then the volume in hydraulic retention time is clear: reactor/container's ...
0
votes
1answer
14 views

Which mounting bracket to use with a geared box?

Which 90 degree bracket would you use for this one? Do you have any suggestions for what i should be looking for, I find it very hard to find something. It is 5cm between all the outer holes. Would ...
0
votes
2answers
62 views

Refute my assumption: Bearings Don't Improve Efficiency

If two surfaces rub together with a normal force between them, friction is generated. You could add lubrication between those two surfaces and reduce that friction. Bearings essentially consist of ...
1
vote
2answers
30 views

What kind of splines should be used when planning roads?

I would like to plan a small road network for an imaginary city, and I am looking for a way to create curved road segments. I am familiar with cubic Bezier curves, but I am not sure if it's the best ...
0
votes
1answer
19 views

How much power could a turbocharger generate?

I can find many figures online for the extra power generated when a turbo is fitted to an engine. However, I can't find any figures on how much energy the turbocharger turbine actually takes out of ...
0
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0answers
9 views

How to fix blocks with attribute tags in AutoCAD which were exploded?

Sometimes I get AutoCAD drawings with attributes outside blocks. Seems that people who don't know how to use attributes try to edit text and blocks but, as they don't know how, they explode those (...
0
votes
1answer
28 views

Simulating AC using DC

Is it possible to power an AC motor, using alternating positive and negative DC current? I would assume toggling between each at 60hz would work.
3
votes
3answers
78 views

What are the possible implications of the heating of the structural stonework of Notre-Dame cathedral during the fire?

Yesterday, Notre Dame cathedral caught fire. The roof and the central spire were destroyed and some of the stonework was subjected to high temperatures for an extended period. What are the likely ...
0
votes
1answer
13 views

Hover Stylus for capacitive touchscreen

Capacitive touchscreens do not rely on touch as the name suggests but rather measure the distortion of the electrostatic field. To my understanding a touchscreen might be able depending on the build ...
0
votes
0answers
27 views

Second Order OPAMP circuit

I was trying to understand the way this problem was solved and I got confused with the latter part of the solution. I encircled the part that confused me. They seem to contradict each other. If $\...
0
votes
1answer
25 views

Deflection of Rectangular Plate with 2 Simply Supported Edges

As shown in the figure provided, a Uniform load acts upon a rectangular plate with edges at Y = 0 and Y = b which are simply supported. Using this form of the Plate Equation: $\frac{\partial^4 \...
1
vote
1answer
27 views

How to compute core stress in honeycomb structure?

Assume I have a honecomb(sandwich) panel under distributed normal load. Each edge of this panel is simply supported(pinned) as on the picture below: The problem is how to find the core stresses σ-z (...
0
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0answers
7 views

which one is best certification course for WIFI? [on hold]

Is there any certification available for wifi courses, if there which one is best ?
1
vote
1answer
25 views

How to calculate divided irrigation discharge from a Parshall flume

How do I calculate the discharge from a Parshall flume that flow over a bulkhead (XY) into three partitions (A, B and C) divided 25%/50%/25%. There is no restriction of flow when the pipe gates are ...
0
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0answers
28 views

Why aren't artificial gills used together with oxygen tanks for diving?

Artificial gills aren't used for diving, not because they can't extract oxygen out of water, but because they won't provide enough oxygen for someone to breathe (only arround 1% oxygen in water ...
1
vote
1answer
30 views

Can a reinforced hose develop an internal restriction due to thermal expansion?

The type of hose involved is the thinnest one on the right in this picture. This hose contains an external rubber layer, a textile reinforcement layer, an inner rubber layer and a nylon lining. The ...
0
votes
0answers
14 views

abaqus simulatioon

USING ABAQUS SIMULIA 6.13 hysteresis low cycle fatigue of isotropic and kinematic hardening .I use combine parameters but no yielding occurs and hysteresis force disp loop area is zero .I also need ...
0
votes
1answer
21 views

Is there an easier way to calculate rocket engine Isp?

I am trying to calculate the $I_{sp}$ of a rocket with a thrust of 500 kN. I know that you can calculate $I_{sp}$ with $I_{sp} = \dfrac{v_e}{g_0}$. However, to calculate $v_e$, you need the $I_{...
0
votes
1answer
33 views

Comparing the precision work of plane surveying and geodetic surveying

In geodetic surveying, we consider the spherical geometry of the surface though the surface is not perfectly spherical. In-plane surveying, we consider a small surface area which is considered as a ...
6
votes
5answers
4k views

What happens to sewage if there is no river near by?

I know that in places where there are convenient rivers and streams the tendency is to dump the communities sewage into those waterways so that it is carried away. But what about places where there ...
0
votes
1answer
60 views

A naïve question about computer chips

Is it true that computer chips "float" inside of the computers ? Can someone give me references(books, articles, papers...) about that fact ?
0
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4answers
55 views

Unusual idea for fish tank design. Unsure if plausible or not

I looked through the stack exchange list of sites, hoping to find one more suitable for my question, but decided that this was the most likely place to get the answer I'm looking for. I'm not an ...
1
vote
0answers
23 views

Relation between burgers vector, slip plane, dislocation motion direction and dislocation line

I am really confused about the relation of this 4 entities. I know that the dislocation line is perpendicular to the burgers vector in an edge dislocation and parallel to the b vector in a screw ...
0
votes
1answer
30 views

Pump Characteristic Curve

I am bit confused about the curve: We could observe from the [Pump curve] that Total Head decreases with increase in flow rate, but for [System Curve], it is opposite, i.e, Total Head increases with ...
0
votes
0answers
23 views

Where/How do I source parts for a commercial product [on hold]

If I have a commercial project/product idea, where would I source the parts from? For example, if I would need to create a tablet - as part of the product (more like a portable computer with a touch ...
0
votes
2answers
20 views

Why does a lead-compensator type system decrease to a step response

For example, the step response of $\frac{s+1}{s+2}$ is decreasing although its gain is +1, and this system has higher gain at high frequencies than low frequencies based on its Bode plot. But if I ...
0
votes
0answers
23 views

Energy required to vacuum a cylinder

I'm trying to calculate the energy per unit length the vacuum pumps require to vacuum a cylinder with a diameter D. Which formulas should I use? I used a typical formula for compressors and the ...
3
votes
3answers
63 views

Why does concentrated shear force on a beam influence the whole beam?

This might be a silly question but can someone explain how this shear force on the right side of the beam causes Qy throught the whole beam? I understand it mathematically but not conceptually so I ...
1
vote
2answers
53 views

Influence of a diagonal fold on a web + double fold situation

I need to build a steel frame with a steel web in it, as illustrated below. Flanges of the frame will be welded, as well as the web, along its whole perimeter. Would adding a diagonal fold to the web ...
0
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0answers
4 views

Are the nearby airplanes cleared of the sky when launching Falcon Heavy? [migrated]

I was checking Flightradar24 when launch occurred and didn't see any difference. Also, 3 boosters landed back successfully. I assume the sky has to be clear of airplanes to avoid any potential ...
3
votes
2answers
97 views

Why do 2-stroke engines burn more oil?

Of course, most 2-stroke engines require oil to be mixed with the fuel (I appreciate there are 2-stroke engines that don't require this). Therefore, it makes sense to me that oil will be burnt during ...
0
votes
0answers
18 views

How to keep lighting “barn doors” open

I have two alum plates (45cm x 20cm x 1mm) that are hinged on the long side with two 30 x 80 hinges (30 x 40 each tang) in the middle, and "L" bracket / 20mm brace at the ends secured with a M4 loc ...
0
votes
2answers
24 views

How effective will a cooled mattress be for cooling down a baby?

I'm trying to make a cooling device to used in hot areas for cooling down newborns. I'm planning to cool down the mattress to a temperature of 37C, how effective will such a system be to keep the body ...
0
votes
0answers
9 views

why do errors occur in transmission of packets by network layer when transport layer protocols already make a virtual connection between hosts

As far as I know the duty of transport layer is to make a virtual connection between two hosts that want to share info after that the data is sent to network layer where data is divided into packets ...
1
vote
2answers
14 views

Gasturbine energy balance

I have a question regarding gasturbine energy balance, the total energy that flows into the gasturbine is given 12 MW and the power needed for the compressor is 4.4 MW and the turbine power is 9.3 MW....
1
vote
1answer
32 views

Magnetic treatment of hard water to prevent scale and corrosion? How does this work?

I ran across this company at their booth at a Tradeshow (2018). They claim to have a chemical free (and as far as I can tell - a power free) treatment method for hard water to minimize scale and ...
2
votes
1answer
22 views

Why do we increase the minimum beam/slab depth if we increase the grade of the reinforcement to control the deflection

I've just started to study reinforced concrete design and I came across this in the "Design of Concrete Structures" by Dr.Nilson. and I was wondering why do we increase the minimum thickness if we ...
0
votes
0answers
14 views

Which program should I use to find moment of inertia of complex sections?

It is an aluminium section for a mullion and transom and the autocad drawing I have is very complex and I tried using autocad mechanical but it does not work as I am not able to select the area as it ...

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