Engineering

Hello you all! Despite the unusual layout, you may recognize the common Sallen-Key biquadratic cell, here as a low-pass: s is j*2pi*F and A is the attenuation Vin/Vout or 1/H. The low-pass Sallen-Key worsens if the resistors differ, so the Q factor resides in the capacitor ratio only, but precise capacitors are often limited to the E3 series (10-22-47). The modification I used for >20 years improves that by adding one buffer: Now the resistors can usefully differ. Most often, a single capacitor value fits the biquad cell and even the complete filter. Big Q-factors can result from the combined resistor and capacitor ratios, the latter being si…

Can I connect an 12V alternator to my Electric cycle's rear wheel to recharge my battery simultaneously? I mean to recharge simultaneously while my bike is driven by a DC motor. The alternator would be connected to the other side of the rear wheel. The Electric bicycle runs on 250W motor/12V Lead acid battery system. Is it possible? Need experts' help!

I will be honest, I am new to doing this and I have alot of questions about engineering and physics. I have this question in my head about how engineering involves science. If anyone can explain this to me that will be very helpful. Thank You.

Hi guy, currently i doing research on SAM (scanning acoustic microscope technique) techniques to measure the internal micro-crack for material. But now the problem i facing is, most of the reviews i found are using SAM technique to measure internal crack for IC chips. May i ask is SAM technique suitable for larger material, such as metal rod( length = 400 mm, diameter= 30mm)? Next , i was researching on the suitable frequencies to measure the internal crack for the metal rod. The frequencies range is 10MHz to 2000MHZ. But i also found out when the frequency increase, the penetration ability will decrease. So may i ask, what is the suitable frequencies range to m…

I have a problem with this in working out getting it to watts/. I think I am doing it wrong. I can either work it out two ways. For an example, a circular solid disk with a diameter of 2 mtr and a weight of 7 kg or 70 newton this is rotating at 57rpm and I have this as 104 watts of power. Or I can do it with mass rotating around which would be .5 *7Kg = 3.5 * half the diameter V2 * Mtr/s at half radius =3 V2 and I come to an answer of 7.9 watts. Where am I going wrong !!!!. Hope that some pne can help me get some sleep. Many thanks

Hi, i'm a electrical student but recently i have been task to do a assignment which is material science related. I don't have any background for that, so i have quite a number of problem for it. My assignment is to measure crack length ( micro-crack length / very small crack length) for aluminum at HIGH TEMPERATURE. I have read up some methods example like using ultrasonic, DC potential, x -ray and so on. But the problem is i do not know which method is effective and simple. Is that any suggestion or information for me to read up. thanks

In a novel I've started, the Earth is slung out of solar orbit. But we are given several years' warning that we will be losing the sun as an energy source. Would it be possible for a scientific-minded individual to build a space suit to protect him for a few hours, at least, from temperatures down to say -150 degrees Celsius, when he ventures out from his underground bunker? At that point we would still have a decent atmosphere - although water vapor, carbon dioxide, and several other gases would have frozen out - so the issue wouldn't be atmospheric pressure, it would be protection from the cold plus oxygen supply. Thanks.

What do you think about building sealed long tunnels for trains, that after they are being built, there are pumps vacuuming it out of air, at high percentages of the atmospheric density. Suppose the train is sealed too and compressed like airplanes, and there are sealed passages in the stations connecting the train to to open world, to let people get in and out of the train. What do you think about reducing drag and fuel consumption in this model?

Hi guys, currently in second year engineering, found a part time job where I am an intern as a student in a business here who finds me things to calculate in an attempt to prepare me for the real world of engineering. Right now I'm on this project where I have to calculate whether the Equal Angled beam (L 6" x 6" x 5/8") (made of 44W steel or A36 in the US) can safely uptake the tension applied to the adjustable bending pully on mounted on the beam. Just to put you into perspective there is an engineer here, but I've been unable to get anything as much of an answer that makes much sense to me, I guess my understanding is limited and have the impression his time is…

What do you think?

i think there could be. i dont think there would be much mileage, or much room, but i think it could work. just have alot of springs, and the kind that are in wind up toys, just alot longer and bigger. it could rewind as it drives and as it sits still outside, just have like a windmill-like thing that rewinds the spring on top of or on the car some where. what do you guys think? has it beem tried?

Okay, so I'm trying to make this helmet, with LEDs in it. The total voltage for all the LEDs is 29.2 DC. Now, I cannot for the life of me figure out how to get enough power to these 10 LEDs to get them to work! I've looked at transformers, but none of them seem to provide what I need. (Read: Input: 9V Output: 30V Current: 20mA) Please help!

Hi actually I'm looking for a stepper motor and a driver for my Project. I have most of the specs needed but still left with an important factor which is torque. I have to use a stepper motor to turn a aluminum rod which is 320mm for Length and 28mm for diameter in one direction. I do not know the Formulae to calculate the torque with only the dimension. Please kindly advice the formulae needed for the calculation. Thanks

Hello guys Yesterday I was studying thermodynamics , now I've got this problem ! In the power plants we want to convert Q to W , in most cases at the end of cycle we uses some tools to reduce the amount of this Q , but why ? Why don't we use low amount of Q ? so that we don't need to reduce it at the end . And could you please let me know what books do you study in thermodynamics ? I'm studying Thermodynamics by Cengel . Best Regards

how do i make a ball mill the cheapest and most inexpensive way?

I'm trying to solve the following equation: using the following properties available in RefProp (specifically the derivatives of pure substance): Could anyone tell me how to modify the equation from being partial derivative with respect specific volume to partial derivative with respect to density (which can be easily obtained from RefProp). Thank you

Hello you all! A decade ago I suggested to mix a nano-powder of high index ceramic in plastic to produce thinner spectacle lens. If the powder is fine enough, the composite acts as a uniform material and doesn't diffuse light. Now I read that at light-emitting diodes (LED), laser diodes, photodetectors, photovoltaic cells... the high index of the semiconductor is said to create parasitic reflections at the chip's surface. I'm not quite convinced this is still the case: maybe books and Internet pages describe the situation several decades ago. Anyway, a solution would be to encapsulate the chip in a transparent plastic loaded with nano-powder of high-index cera…

Hi all, can any one explain what are the benefits of pharmaceutical packaging? How it is differ from general packaging methods?

I am in the research process of planning a single person private mission to mars and space. Money is an issue but Can be sacrificed to the mercy of working methods and science. I have little experience in the field and that is wear your ideas and thoughts come in. I am looking for a propulsion system that is the most Physically effective and compare the costs and output to other methods. The most important factor is actual amount of force that the system displays. The second most important is the amount of force comparable to the system or fuels own weight in earth. The third most important factor is the amount of force after weight of the system is subtracted a…

Hi fellows. What are the parameters of consideration to evaluate the suitability of a fluid used as a closed circuit circulating and pumped cooling media ? Thermal conductivity, specific heat, thermal transfer index, heat capacity, viscosity... what else? The circuit to be a machine that gets hot and a heat exchanger to cool the circulating fluid. To replace a coolant such as transformer oil with plain water, or diesel, or transmission fluid, or other suitable ones. Or reverse, as replacing plain water coolant with kerosene, or very thin oils with viscosity near water.

Gagged.

Hi, I've always been interested in humanoid robotics ever since seeing Ghost in the Shell wayyy back in the 90's and have decided to build a simple anthropomorphic robot arm that simulates the movement and speed of a human arm. Im also planning to make the arm react to its environment, but only once the arm itself is constructed and control software is written. This of course will just be a hobby, mainly to break into robotics and see where it takes me. If successful, I would like to construct a full size but limited humanoid robot. I've no plans to make this future bot capable of any type of self-supported locomotion like walking or running. At the most it would…

Hi, guys what you thing about new Innovations in Aerospace engineering. Like - Laser Propulsion Or Beamed Energy Propulsion Laser Propulsion Or Beamed Energy Propulsion Beam Energy Propulsion is a promising technology for near future aerospace propulsion. It offers high payload ratio and propulsion efficiency. But major problem with this Technology is Temperature Increase and thermal Damage (Melting). How can we solve these problems, any body have more knowledge about this technology please share. If you have any innovative idea like this any information regarding new technology in Aerospace Engineering plz share your ideas. Thanx..

except nuclear weapons.. also not >5mW lasers .. i'm writing an essay about present and future non lethal weapons..

To me, the main problems with hydrogen powered cars are where to get the hydrogen and how to store it on the car. Solar power would work for getting the energy, but how do we store it in reasonable amounts? I was thinking the fuel tank could contain a block of lithium, and water could be stored elsewhere. The lithium and water could be used to make hydrogen, which could in turn be combusted the usual way. Lithium hydroxide would be produced as a useful byproduct, it could be sold to the battery industry, or back to the "lithium station" for a discount on your next purchase. The lithium station could take the hydroxide to an electrolysis plant, where the lithium would be r…