# All Questions

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### How small can you get a stream of molten steel to be at low pressure?

I'm designing a crucible / extruder, and right now it has a .6mm hole to extrude from. Will this work? A chart with various metals listed would be nice. Pictures: Click to expand
2k views

### Deriving the deflection force equation for a beam that is fixed on both ends

I want to calculate the force-displacement equation for a beam that is fixed at both ends. I think I should use the superposition principle but I am not very sure how to get started. I know that for,...
531 views

### Estimating Maximum Speed for a Pneumatic Cylinder

I am designing an machine that is going to use a pneumatic cylinder to accelerate a projectile. I have a tentative cylinder specified, and am working on the control and supply side. I have verified ...
364 views

### How to extract a building's heat isolation and thermal inertia based on temperature curves?

So imagine we have a house with some isolation and some thermal inertia. This house also has a heating system that turns on (starts heating) when the observed temperature curve goes below some ...
459 views

### 6082 Aluminium softened by brazing. How to harden?

I've started playing around with brazing pieces of extruded aluminium sections to join them together for strong joins as an alternative to bolting them. The pieces are made of 6082-T6 aluminium alloy....
12k views

### What does “beam end release” actually mean, and how it is modeled in mathematical terms?

I am reading a document about beam end release here: An end release will allow either or both ends of a beam element to rotate about or translate along one or more of the local axes of the beam....
7k views

### Steel Structure connection pin or fixed

For the connection above, I think that once the beam is loaded, their is no room for rotation of the beam. But as per British Standard this is a pinned connection. So I have been trying to determine ...
1k views

### Losses through holes drilled in a pipe

I asked a previous question about pipe t-junctions with pipes of varying diameters, and it got me wondering... How are losses handled and calculated in pipes with holes drilled directly into them? ...
354 views

### Fluid mechanics - how to calculate flow distribution in piping network?

I am trying to build flexible, visual tool to calculate flow distribution through the piping network (mobile hydraulics). I have root node of the network which has defined flow and pressure inputs. ...
675 views

### Minimum thicknesses of an elliptical cylinder pressure vessel

For pressure vessels in the shape of circular cylinders, we can use $\sigma_{hoop}=\frac{pr}{t}$ to find the minimum skin thickness by setting the hoop stress the maximum allowed value, and then ...
7k views

### Properties of an hexagonal shape vs round tube shape

In a bike frame build, are there any differences between hexagonal cross-section tube instead of the typical round tubes? Assuming that both are made from the same aluminium alloy and have the same ...
255 views

Suppose we have a horizontal rigid bar hinged at one end to the wall. An inclined straight link hinged at one end to the same wall, is pinned to the rigid bar at its center. A load P is acting at the ...
425 views

### Is there a theoretical bound to how tall a structure can be built?

Assuming that there are no constraints on cost, land to develop, or supply of materials, is there a theoretical limit on how tall a structure can be built? What are the main physical constraints that ...
538 views

### How to find angle of timing gears

I am trying to figure out how to calculate either the distance or angle of 2 Idler Gears in a Timing Gear Configuration like so: I have been able to eyeball things, so they are approximate. I would ...
518 views

### Gear coupling and clearance between pitch surfaces

I have a couple of spur gears (0.4 mm module, ISO8/AGMA9 precision, 24 and 120 teeth). I want to make their backlash as small as possible. But also I don't want them to jam. Where can I get the normal ...
723 views

### How can I attach a rotary encoder to a retractable dog lead?

I need to know how I can attach a rotary encoder to something string/wire that I can pull and it retracts automatically My idea was to take apart a retractable dog lead leash and affix it to it ...
443 views

### How to calculate the steering ratios on multiple axle vehicles?

I'm building a model of a long vehicle with 6 axles and I want to be able to steer it. How do I calculate the amount each axle should steer to minimise dragging of some wheels round sideways as it ...
77 views

### How can I make an uncalibrated flow meter for water flows of a few liters per hour

Or alternately what is the name of the device I'm looking for? My first thought is to make a narrow V shaped chamber by gluing 1/4" acrylic together with 2 face plates and a mid plate with a ...
28k views

### Difference between Saturated Liquid and Saturated Steam

I have a (maybe stupid) question which is making me crazy: what is the difference between a saturated steam and saturated liquid state? I mean the physical difference not the difference on a ...
108 views

### Why/how normal shear stress is zero in thin-walled beams?

Please explain how the normal shear stress (shear stress normal to the cuve, C, defining the cross-section of a thin-walled beam) is zero. I have attached a screenshot from a book which says that the ...
207 views

### what's the best shape for inducing condensation?

What would be the best ceiling shape for inducing condensation? I'm guessing it would a curve ︶ or V shape, but those are just guesses. (I don't have any background on thermal physics)
392 views

### Flow in a T-Junction with pipes of different diameters

I have been trying to model a complex pipe network recently and have come across something I can't find any information on. In my model, I have been assigning equivalent lengths of pipe to various ...
57 views

### Does the Hyperloop One suspension require constant current through copper windings?

As a follow-up to How does the pressurized suspension of the Hyperloop not affect the tube pressure?, I believe (though I can't find where I read it now) that the Virgin Hyperloop One implementation ...
70 views

### What does (a) the input of the activation function mean?

I am not very good at understanding the ANN theory, but please if anyone can explain me about what does (a) as input of the activation function mean? and how to get this value? Thank you
2k views

### Oldham coupling vs Universal joint

I've heard that both of these coupling types introduce a degree of kinematic error in the driven shaft. What does it actually mean in practice? Is it that the driven shaft doesn't turn uniformly even ...
196 views

### How to obtain strain and stress values by editing abaqus input file?

I am currently working on abaqus modeling, I am trying to find a quick way to get the strain and stress values shown in the output file. What do I need to put in the .inp file? Does anyone know how ...
797 views

### Can anyone verify this wall thickness of a pressure cooker?

I am working on designing a pressure cooker. I've have tried to find, using two different models, the wall thickness based on the following assumptions: Cylindrically shaped container Made of ...
97 views

### Is there a device like this? [closed]

I would like to get my hands on a mechanically-set timer (wind up is fine, so that it's self-powered) which sends a small electrical pulse to a mag-lock once the timer goes off, thus causing the mag-...
85 views

### What does this equation mean?

$$\propto \dfrac {\text {Cross-Sectional Area}}{\text {Volume}}$$ I've seen this equation on my textbook (physics). Let us imagine that there are two pen with $7$ and $3$ lenght. Which is harder ...
15 views

### Efficiency of a sterling engine

What is meant by thermodynamic efficiency of a sterling engine? and what are the factors that affect the thermodynamic efficiency of a sterling engine? Similair to other questions i know despite ...
50 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
1k views

### How would I find the Second Moment of Area of a Parallelogram?

How would I find the second moment of area of a parallelogram, as shown?
923 views

### What's the maximum water jet psi we can create?

Hy everyone, new here, I don't know much about how high pressure water pumping works - ( i'm just a programmer ) but i need to know if we can create water pressures ...
2k views

### How much force can a pole in ground take before falling?

Consider I have a pole stuck in the ground as illustrated below: When a force F1 is exerted on the pole, its bottom end will push against the ground it's stuck in; the ground then exerts a resistance ...
59 views

### how to avoid a clash of magnetic charge and electric charge

now I'm working on a project which involves a dc motor and high voltage. I'm developing a machine consists of a motor to rotate a platform disc and high voltage will be applied during the rotation. ...
62 views

### Find optimal configuration for Stirling Engine

I'm trying to figure out the theoretical calculations for a Stirling Engine system so I can determine optimal piston size, optimal piston displacement and number of pistons. I want to calculate which ...
1k views

This is the question, but with me 6 kN/m is 4 kN/m and 2 kN/m is 2.5 kN/m. And the length is not 4 but 9 metres. I am not yet at the chapter of equations of equilibrium, plus it says the couple ...
5k views

### How to prevent deposition of dust on ceiling fan blades

It is well known that dust gets deposited on a rotating ceiling fan because formation of a boundary layer over fan blades. The air layer next to blade surface is stagnant due to no-slip condition and ...
588 views

### Avoid snapping an electric cable from too much rotation

I recently built the basic construction for a crane out of lightweight material. Basically the head of the crane contains an electric servo motor which spins the head of the crane by pushing itself ...
382 views

### Does weathering steel corrode the same as carbon steel when it doesn't develop a protective patina?

Weathering steel is supposed to form a protective patina when exposed to wetting and drying cycles. This protective patina prevents more corrosion from occurring. This is what differentiates it from ...
1k views

### Is a permanent platform that is hanging and moving a dead load or a live load?

If a permanent room or platform is suspended from a larger structure (say, on a cable that is attached to a hook on a track in a ceiling) and designed to be in constant but not necessarily repetitive ...
2k views

### Could a gold/{second metal} crown be created that would pass the Archimedes test cost effectively?

Many people are familiar with the story of Archimedes submerging a crown in water to identify if the volume of the crown was consistent with the volume of the same amount of gold. The test was to see ...
514 views

I am having trouble to calculate the differential equations of a simplified loading bridge. The system is build as shown in the picture below (just a sketch): If I use the Newton approach, I am ...
1k views

### How do I keep my bit from wandering on a drill press?

I punch metals before I start a bit in them, but with small-diameter bits I am finding that they wander inside the material. E.g., drilling a 1/8" hole in 1/2" of aluminum the (titanium-coated HSS) ...
229 views

### Developing a stochastic differential equation model for concrete fibers

I am working on modeling concrete fibers (metallic fibers) as a mathematical model. My work is for my thesis. I am a PhD student of numerical analysis, but I am working on a real tunnel project. I ...
9k views

### Distance sensors with accuracy of 1 mm?

I am making a device for measurements. I would like to measure the distance within accuracy of 1 mm. Range could be 2 cm to 15 cm . I looked at Proximity Sensors but the readings displayed by these ...
277 views

### Sensors / processing algorithms to emulate a human's sense of smell

A lot of research has been devoted to creating electrical devices that emulate biological sensors, including: Visual: Cameras, color/light intensity sensors Auditory: Microphones, ultrasonic sensors ...
3k views

### How do I calculate the strength of a weld joining two crossed rods?

While considering this recent question, I started wondering how to determine the strength of the welds in the steel mesh. As AndyT points out in his comment: The welds at the connections are only ...