Engineering

Hello. Why are in general, water pumps outlet made smaller diameter than their inlet ? This is not asking why inlets are larger; but you can also elaborate on that if you want.

Hi, Does someone know how to derivate the formula of White-Colebrook? The professor said this will probably be a question on the exam, but I have no idea how to do it... I've searched on the internet for quite a while and I can't find the derivation . This is the formula: I would really appreciate any help!

Many of you have probably seen the news about the new Tesla Power Wall, which is basically a lithium-ion battery that's meant to be recharged with solar power (or other renewable source) and keeps you from using any electricity from the grid at all. For those who haven't seen the news, you can watch the presentation by Elon Musk, who is admittedly a great entrepreneur, but in my opinion might need to work a bit on his presentation skills. What do you reckon, is it worth getting one? I've been thinking of one and it seems barely worth it because: - average daily electricity consumption for our house is ~8 kWh (averaged over the last 4 months) - solar panels on the…

The last time I studied radio electronics we were still using tubes (valves for you Brits), though the ideas of amplitude modulation and frequency modulation remain the same. Moving to the crux of the matter, is it possible to transmit a radio signal that is simultaneously amplitude and frequency modulated?

Slider & Crank Mechanisms. How would you obtain power and efficiency from a slider & crank mechanism. Is there a relationship?

I remember Mr. Clarkson made a mention of this in Top Gear a couple seasons back, but anyway - how do you get out of a car with gull-wing doors if it's rolled over and ended on its roof? I haven't found information about it, but I can't really imagine that engineers have disregarded such a glaring safety hazard.

Hello, I am planning on building an electrostatic ion accelerator by having a tube with parallel plate capacitors to have a negatively charge plate facing one direction and an electrode to generate the ions for repulsion. now my question is if I have the wire from the negative side of my high voltage source split so as to branch between the capacitor and the electrode would this decrease the voltage to either source? and my second question is what are ways to increase the charge density created by the corona from the electrode aside from just increasing the voltage into the electrode.

Hello everybody, I'm looking for an electromechanical relay capable of high switching rate (make and break) up to 100 Hz. Relay is supposed to be for 24 V DC circuit and of small curent rating (100-200 mA). I know such a high switching rate is difficult demand for electromechanical relays, and manufacturers I contacted told me they don't have anything above 20 Hz. However, I researched myself and found in the book "Electromechanical systems in Microtechnology and Mechanotronics" the following table: Therefore, the relays I'm looking for certainly exist, but I don't know where they are used . Anybody here know something about such relays and where I can get the…

I was having discussion with my friend yesterday, and he says the jet fuel from the jet that crashed into the towers cannot melt steel...which I fully agreed with him. However, I argued (and I'm no engineer by any means) that the impact of the plane, the weight, and heat combined made the towers collapse. A 168 ton plane, flying at 400 mph, had to have severlely weakened the immediate area that the aircraft impacted. Also, the steel beams were not engineered to hold a 168 ton aircraft, along with the high temperatures inside the tower. All these factors combined lead me to believe this is what caused the first or few floors to buckle causing the towers to fall…

I am going to attempt to make my own circuit using a printed circuit board I was looking for soldering irons on-line and they have it classified as such -heavy duty soldering iron -medium duty soldering iron -light duty soldering iron and also they have different wattages which i do not understand its benefit or disadvantages (30w, 120w etc)

I have an electronics test tomorrow, and I got most the the theory down, but if we quickly consider a N type mosfet with a positive Vgs is applied, the positive holes in the P-type channel are repelled, thus the area becomes negatively charged (or is it more accurate to say electrons are attracted to the area??), but this does not necessarily mean there are free electrons to carry the current does it? Where do the charge carriers come from? I watch a youtube video that says electrons are attracted to the region, which doesn't make sense after the channel has been negatively charged, since it will repel electrons. Thanks in advance!

I know there are cloud seeding technologies already but for me that's sh*t. Will we one day we able to control every aspect of weather all over the planet? Like controlling what temperature we want to have, how much rain and when/where should it fall, how much UV we want etc. Coruscant from Star Wars (a gargantuan planet-sized multi-level megalopolis) had such a system. Personally I would like to see nice 20 degree Celsius weather in Sahara year round.

If we placed some conducting coils inside a magnetic field created by 2 permanent magnets, Ampere's law tells us that the current in those coil will be proportional to the flux flowing through the coils. This is fine if the coil is a super conductor, but as soon as you add a resistor to the coils, the current will create a potential across the resistor and thus the coils. Faraday's law tells us this will produce a changing flux, in this case the flux in the core will reduce. This seems to lead to an odd conclusion, either the permanent magnet strength must decrease to reduce the flux or the core must become extremely resistant to flux at steady state. My money is …

The resistance of the source and inductor are set to 0, this must be a mistake right? I was expecting current to stay constant after the source stops pulsing.

A problem with wind turbines is, of course, that their power is intermittent. I have seen talk of using compressed air or batteries to store the power but both these solutions have problems with efficiency, and batteries leak power even when not used. I was thinking, what about using a heavy weight to store power? Electric motors would lift a weight, then when power was needed, the weight would fall, running the motors backwards and generating power. I guess it would be very efficient, and there would be no leakage of power even if the stored energy was not used for months or even years. It is low-tech and very low maintenance. The heavier the weight, the less fa…

Anybody can tell you that if you wrap some wires around a something then pass a current though it, you will make an electromagnet, but did a single one of you stop to consider what was actually going on? Faraday's Law tells us that is we apply a voltage to this coil, the flux within the coil will increase with time. Consider a voltage being applied directly to a coil, well this should produce a ever increasing strength magnet right? But we know that DC electromagnets create a constant strength magnet. I sure as hell haven't heard of somebody creating some kind of magnetic singularity in their basement. So who can tell me why a DC electromagnet creates a c…

How I can declutch an electric actuator ?

How do you prevent eddy currents in a transformer? (I know the answer, just testing you guys).

Hi all, just registered to see what people thought of this idea. I believe the latest problem is that the containment pits have cracked, allowing contaminated water to leak into the sea. Why not use gelatine to turn the contaminated water to jelly and reduce how penetrating it is? It may also reduce evaporation If this seems reasonable, how can we get the message to tepco?

So I understand how the rotating magnetic field is created in the stator, so lets assume we have a uniform intensity rotating magnetic field and work from there. Lets start from a stationary position. The flux lines from the stator magnetic field cut the squirrel cage bars, inducing current and thus inducing a north and south pole in the rotor. This induced 'magnet' attempts to align with the rotating stator field, but as it approaches the stator magnetic field rotation speed (synchronous speed) flux line cut the bars less often, thus less current and a weaker magnetic field induced by the rotor. This is why the rotor speed never quite reaches the synchronous speed si…

To live in a flying city would be truly amazing, but how would we make it fly, power it, and control it?

Hi. What tough 'clear-to-heat' plastic film permanently exposed to sun, rain, wind (no snow) would you suggest ? Something similar to polyethylene. It is to cover a coil of black HDPE as for a solar water heater, shielding it from cooling winds and letting sun heat pass trough ? A life of 5+ year would be desirable. Greenhouse cover or there is something better ? A coil similar to this attachment, placed on top of a suitable heat insulating polyestyrene foam sheet, and covered by such film instead of glass or polycarbonate sheets.

I am teaching Bioprocess Engineering lecture but the lab of my school does not have many instruments and equipments. With basic equipment(without a bioreactor etc) bioprocess experiments for students that we can follow the process every week. I need some cool and interesting ideas..

Hi! I need an efficient power supply for my engineering activity. I have several variants but more keep to this isolated dc dc power supply. What supply will you recommend?

Those medieval castles with massive stone walls and in general, huge loads on soils, how were their foundations 'calculated', in ages with little tools, expertise, no reinforcing bars, portland cement, soils testing and engineering ? Many still standing, built with handcrafted and selected stones, erected with great efforts. Building sites mostly on solid grounds, but not all of them. Deterioration trough 4-5-6+ centuries show above ground, but, how good are their foundations after time elapsed ? How was that success achieved then ? The names and techniques of the engineers forgotten, the owners are the famous. ----> https://duckduckgo.com/?q=medieval+ca…