CreationDate stringlengths 23 23 | Body stringlengths 57 10.9k | Tags stringlengths 5 114 | Answer stringlengths 39 16.3k | Id stringlengths 1 5 | Title stringlengths 15 149 |
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2015-05-10T20:28:06.510 | <p>I was always taught that electricity flows through the path of least resistance. </p>
<p>The problem that I'm having is that I've seen/done this:
Take 3 wires have one wire break off into the 2 other wire (like a fork in the road) and put electricity through the first single wire. </p>
<p>Now I take a multi-meter ... | |electrical-engineering| | <p>Ohm's law states that current through a resistor is voltage over resistance. Resistors in parallel will see an equal voltage. This means that each resistor will get some current through them. The one with lower resistance will get more. But they will both conduct current and the total current through the circuit wil... | 2766 | Path of least resistance misunderstanding |
2015-05-10T21:57:28.567 | <p>This may be a trivial problem, but I'm having a tough time with conceptualization. </p>
<p>I'm using a code for modeling flow out of a tank. I'm not experienced in fluid dynamics; I'm more experienced with chemical aspects of the problem. I want to use pressure boundary conditions (a constant pressure at the bot... | |fluid-mechanics| | <p>The reason you're dividing the pressure's by the density is that in the naiver stokes equations that describe fluid flow have three types of terms: inertia terms that are multiplied by the fluid density, pressure gradient terms, and viscous terms that are multiplied by the fluid viscosity. If you divide the whole eq... | 2768 | Conceptual problem: how to define pressure boundary conditions for stratified fluid in units of pressure/density? |
2015-05-11T07:32:39.047 | <p>I've recently discovered a very awesome software tool for the synthesis and analysis of mechanisms. The tool is called GIM, from Faculty of Engineering in Bilbao, Department of Mechanical Engineering, University of the Basque Country (UPV/EHU) "The software is intended for educational purposes, in particular desti... | |mechanical-engineering|software|linkage|kinematics| | <p>Okay, it took me way too long to figure this out. I'm thinking this is just not a very intuitive interface. Here's the fix for anybody else who makes it here. Click #1, Click #2 (carefully!), then check the box at #3.</p>
<p><img src="https://i.stack.imgur.com/sAwHL.jpg" alt="4 bar display output path"></p>
| 2771 | GIM Mechanism Software (Kinematics / Analysis / Synthesis) |
2015-05-11T20:59:23.277 | <p>I want to affix a cantilever to wall. I will support the other end of the cantilever with a strut made of wood, that attaches to some point on the wall below the cantilever, as shown in this sketch (click for full resolution):</p>
<p><a href="https://i.stack.imgur.com/z3Cj2.jpg" rel="nofollow noreferrer"><img src="... | |structures|statics|stresses|wood| | <p>I had a school assessment and decided to look into this. I believe you have calculated the angle that results in the least stiff strut - not the strongest. I would like to think that a higher moment of inertia (I) is better as it reduces the effect that force has on the rotation of the strut - this contradicts your ... | 2780 | What angle - for a strut - provides the greatest vertical strength/support for a cantilever? |
2015-05-12T06:54:03.450 | <p>If you look at the man-made objects around you, you will see that almost all of them are either rectangular, or parallel and perpendicular. There are a few circles here and there, but the overwhelming trend in basically everything humans make now is the rectangle. This is true from the computer user interface that y... | |mechanical-engineering|structural-engineering|design|engineering-history|geometry| | <h3>Buildings</h3>
<p>The primary reason is gravity. When humans first started building things structures that were perpendicular to the ground stayed up more. Stacking rocks for example, the straighter you could get it the more stable it would be, therefore the more 'square' the rocks you used, the easier it would be... | 2787 | Why are so many things around us rectilinear? |
2015-05-12T11:45:01.943 | <p>I'm trying to get my bearings (a somewhat heavy-handed expression) on pump design and I'm finding in the various books I've procured on the subject that there is very little consideration given to the output pressure developed by a pump.</p>
<p>If there isn't much detail to this question, I apologize; I'm still in ... | |mechanical-engineering|fluid-mechanics|pumps| | <p>Head and pressure are effectively the same thing.</p>
<p>It's impossible to look at a pump and say "this pump will provide 10 bar of pressure." One of my favorite aspects of fluids has always been how interconnected an entire fluid system is, and how it stabilizes itself on its own. So the pressure that's actually ... | 2792 | Output pressure of centrifugal pump |
2015-05-12T13:18:28.760 | <p>I am working with a very simple 3-DOF damped LTI spring-mass system. As an exercise I am altering two parameters simultaneously (stiffness and damping coefficients connecting mass 1 to mass 2) to see which combination minimizes:</p>
<ul>
<li>Settling time</li>
<li>Overshoot</li>
</ul>
<p>The objective is to determ... | |dynamics|springs|vibration|stiffness| | <h1>Equations of Motion</h1>
<p>From what I understand from the question and your comments, you can write the equations of motion of the 3-dof oscillator in the form:</p>
<p>$$M \frac{d^{2}x}{dt^{2}} + C \frac{dx}{dt} + K x = f$$</p>
<p>where the vector $x$ represents the displacements, $M$, $C$ and $K$ are the mass... | 2796 | Dominant parameters in the dynamical response of a linear oscillator |
2015-05-12T16:00:54.030 | <p>I want to fix a wire rope horizontally between two trees with a T-connector in the middle of the wire rope to hang a tire swing from.</p>
<p>Something like this:</p>
<pre><code>tree-------wire rope------???-----------------------tree
I I I
I ... | |mechanical-engineering| | <p>A guy on youtube does this professionally. <a href="https://www.youtube.com/watch?v=jWVL6EmBaZ4&ab_channel=PatrickBrandt" rel="nofollow noreferrer">https://www.youtube.com/watch?v=jWVL6EmBaZ4&ab_channel=PatrickBrandt</a> IMO rope breaks over time and I prefer extra strength for my kids. He uses EHS 5/16 guy... | 2798 | How can I make a tee connection on a wire rope? |
2015-05-12T19:30:03.300 | <p>I don't understand how to use the information in a stepper motor datasheet to understand how much torque it can generate. I was going to do a simple board and try to lift a small weight as an example but I realize I need to know how much torque the motor can generate. I'll probably have a little spool out there to ... | |mechanical-engineering|electrical-engineering|linear-motors| | <p>@StainlessSteelRat linked to a very good resource for <a href="http://www.allaboutcircuits.com/vol_2/chpt_13/5.html" rel="nofollow">stepper motors at All About Circuits</a>, but I fear he didn't address your questions. I'll go through your question line by line.</p>
<blockquote>
<p>I'll probably have a little sp... | 2802 | Reading stepper motor datasheets to get torque and speed |
2015-05-12T23:40:40.827 | <p>The term Systems Engineer has always interested me as it generally involves many different fields of engineering.</p>
<p><strong>Systems Engineer - Interdisciplinary</strong></p>
<p>The definition I'm familiar with is usually defined as an interdisciplinary profession of engineering, where the engineer has experie... | |engineering-history|terminology|systems-engineering| | <p>sys·tem /ˈsistəm/ </p>
<p>noun: a set of connected things or parts forming a complex whole, in particular.</p>
<p>a set of things working together as parts of a mechanism or an interconnecting network.</p>
<p>plural noun: systems
"the state railroad system"</p>
<p>synonyms: structure, organization, arr... | 2807 | Is systems engineer an IT profession or an interdisciplinary field of engineering? |
2015-05-13T04:59:24.827 | <p>I wish to calculate air leakage in a piston cylinder arrangement. One side is pressurized and the other is at atmospheric pressure. All steel construction. No piston rings or lubrication. The piston oscillates at about 50 to 80 times per sec, amplitude 5 mm, and is used as an indentation marking tool.</p>
<p>I know... | |mechanical-engineering|fluid-mechanics|pistons| | <p>If the piston is in (slight) clearance inside the cylinder, it's a bit like calculating the flow rate through a capillary, with the difference in diameter being the capillary diameter and the contact length between the piston and the cylinder the capillary length. There are various online calculators to help you wit... | 2812 | Calculating leakage in an all steel piston cylinder arrangement |
2015-05-13T08:59:46.440 | <p>I am trying to understand the difference in the definition of "fault tolerance" and "robustness" when it comes to system design.</p>
<p>For instance, what would be the main design considerations or what would be the definition of the terms when looking at engineering problems? In particular, how... | |mechanical-engineering|electrical-engineering|mechanical-failure| | <p><strong>Robustness</strong> (of a system):
The system keeps its expected performance (not failing) even when the real operation conditions (external to the system) are not the same as the ones assumed in the design. The broader is the range around the expected conditions more robust is the system. As a simple exampl... | 2814 | What is the difference between fault tolerance and robustness of a system? |
2015-05-13T14:33:36.993 | <p>Most modern aircraft engines, such as the one depicted below taken from <a href="http://en.wikipedia.org/wiki/Turbofan" rel="nofollow noreferrer">Wikipedia</a>, are composed of several compressor stages which are driven by a turbine (or several), and a combustion chamber in-between, in order to increase the temperat... | |mechanical-engineering|thermodynamics|aerospace-engineering|aircraft-design| | <p>Gas turbines are modeled using Brayton cycle which in the simplest case consits of:</p>
<ol>
<li>Isentropic compression (in a compressor) </li>
<li>Constant-pressure heat addition (combustion chamber) </li>
<li>Isentropic expansion (in a turbine)</li>
<li>Constant pressure heat rejection
<img src="https://i.stack.i... | 2821 | Efficiency in a gas turbine or aircraft engine |
2015-05-14T02:56:45.873 | <p>This is a continuation of me trying to understand torque and stepper motors in my other <a href="https://engineering.stackexchange.com/questions/2802/reading-stepper-motor-datasheets-to-get-torque-and-speed">question</a>. I'm trying to understand the torque a motor would be required to generate to lift a small weig... | |mechanical-engineering|motors|torque|stepper-motor| | <p>You have the right concept, but slipped a decimal point. 5 cm = 0.05 m. The gravitational force on your 450 g mass is 4.4 N as you say, so the torque just to keep up with gravity is (4.4 N)(0.05 m) = 0.22 Nm.</p>
<p>However, that is the absolute minimum torque just to keep the system in steady state. It leaves n... | 2826 | Understanding required torque for a motor lifting a weight |
2015-05-15T02:44:28.287 | <p>This is a follow up question to my question <a href="https://engineering.stackexchange.com/questions/2826/understanding-required-torque-for-a-motor-lifting-a-weight/2829#2829">here</a> about torque and stepper motors.</p>
<p>There Olin explains:</p>
<blockquote>
<p>Note also that torque isn't the only criterion ... | |mechanical-engineering|motors|stepper-motor| | <p>In the text you quoted, I was talking about mechanical power out of the motor. This is what the power rating of a motor, given no other qualifications, means. A "15 W motor" therefore can put out 15 W of mechanical power under the right conditions.</p>
<p>No motor is 100% efficient, so more electrical power than ... | 2836 | Power and motor current |
2015-05-16T00:42:28.253 | <p>I'm designing a solenoid valve for an automated irrigation project that I'm working on. After having looked at some designs, I have a question.</p>
<p><img src="https://i.ytimg.com/vi/SwqM8zpmAD8/0.jpg" alt="example design"></p>
<p>For most of the designs I've seen, the orifice is smaller than the pipe diameter. W... | |fluid-mechanics|pressure|valves| | <p>The total flow resistance is the sum of its parts. Pipes are long, valves are short. Making a pipe wider is relatively inexpensive, and making a valve wider is relatively expensive. As you make the opening wider, everything about the valve has to be beefed up, as the forces involved will scale along with the size of... | 2841 | Solenoid valve pressure drop |
2015-05-17T00:38:37.407 | <p><strong>tl;dr:</strong> After an extended conversation with an old-timer, I realized a few things:</p>
<ol>
<li>The single most valuable measurement for the majority of people will be water-depth-in-well.</li>
<li>The second most valuable will be water-flow-from-well.</li>
<li>The "bubbler" solution discus... | |civil-engineering|fluid-mechanics|sensors|pumps|water-resources| | <p>RE: for your well:</p>
<p>In geotech, piezometers measure water depth in monitoring boreholes.</p>
<p>Here's a professional sensor:
<a href="https://www.geokon.com/4500-Series" rel="nofollow noreferrer">https://www.geokon.com/4500-Series</a></p>
<p><a href="https://i.stack.imgur.com/3FCMK.png" rel="nofollow noreferr... | 2852 | Low cost, moderately accurate water depth measurement |
2015-05-18T03:38:48.707 | <p>I once meditated on the fact that a car, in downhill, would consume more fuel when in neutral to keep the engine on, rather than in gear. To keep the engine on when in gear, in fact, you mostly need <em>the gravity</em> and enough thrust to keep it rotating, and therefore no fuel (just motor oil).</p>
<p>This is wh... | |automotive-engineering|fuel-economy| | <p>The answer depends a great deal on the control system around the engine, and how fast you are going down the hill relative to the gear you are in.</p>
<p>For a basic engine system, like 1960s or earlier, at idle throttle setting the fuel usage would go up a bit with engine speed. The higher engine speed would make... | 2859 | While going downhill, does my car consume less fuel when in neutral or in gear? |
2015-05-19T01:51:04.870 | <p>If I take a large thin plate and I uniformly drill a very large number of holes (diameter "d") very close together (minimum spacing "s"), what will be the stiffness of this new plate? When I say "stiffness" I mean the derivative of average macroscopic displacement with respect to stress. With no holes it would be Yo... | |mechanical-engineering|stiffness|elastic-modulus| | <p>A simple first order approach would be to treat the plate like a composite material, with the holes acting as a medium with no modulus. The <a href="https://en.wikipedia.org/wiki/Rule_of_mixtures" rel="nofollow">rule of mixtures</a> , treating the "holes" as fibers with 0 modulus, would yield a modulus of 0. So, t... | 2865 | Elasticity of a drilled plate |
2015-05-19T12:02:10.323 | <p>If you have a look at the car's wheels, you'll notice that they have holes which can be of different forms (mostly circular or rectangular). </p>
<p>Why do they have such holes? Doesn't that reduce the stiffness of the wheels? </p>
<p><img src="https://i.stack.imgur.com/XjBCgm.jpg" alt="enter image description ... | |mechanical-engineering|automotive-engineering|wheels| | <p>Many of the answers so far have mentioned that part of the purpose of the holes is weight reduction, but most of them don't express why weight reduction in the wheels is important. There are two major reasons; the first (also mentioned by Steve Ives) is that the suspension systems in vehicles operate better if the ... | 2873 | Why do car wheels have holes? |
2015-05-20T04:58:27.930 | <p>In my engineering class we must make a machine that can sort 15 marbles with 3 different types in less than 2 minutes. I plan on having one marble go over/under a light sensor with a flashlight on the opposite side so it can read its reflection, then have a gear with three cups spin according to what the light senso... | |electrical-engineering|sensors|optics|robotics| | <p>A sensor's switching frequency will usually be in the order of milliseconds, so it definitely won't be a problem. However the highest delay you will have in the system is turning to the right cup to dispense the last marble that was sensed. Attach a two bit absolute encoder on the spinning gear to always find the sh... | 2884 | How fast can a VEX robotics light sensor operate? |
2015-05-21T09:03:46.213 | <p>A neat image <a href="http://en.wikipedia.org/wiki/British_Rail_Mark_3#/media/File:BR_Mk.IIIa_TSO_No.12604_%288074749189%29.jpg" rel="noreferrer">from Wikipedia</a>:</p>
<p><img src="https://i.stack.imgur.com/c8JHcl.jpg" alt="railway carriage side looks neat"></p>
<p>Here the railway carriage side looks like it is... | |materials|rail|metals| | <blockquote>
<p>Is it indeed possible</p>
</blockquote>
<p>Yes</p>
<blockquote>
<p>and reasonable to craft a carriage side of such large single sheet</p>
</blockquote>
<p>It can be reasonable, but typically isn't. To form an entire side of the carriage from one sheet of steel would require a forming press that ... | 2895 | Is this railway carriage side likely made of single metal sheet? |
2015-05-22T11:47:17.743 | <p>I have noticed when examining performance of various heating elements in different atmospheres that in a vacuum maximum temperatures are lower than the in air temperatures. Why is this?</p>
<p>(Typical heating element alloys are Nickel-Chromium and Iron-Chromium-Aluminum)</p>
<hr>
<p>As Olin Lathrop says below th... | |thermodynamics|temperature| | <p>One reason is because in vacuum there is no convection to help remove the heat. All heat loss from the element is either by radiation, or via conduction thru the supports and wires. Technically this only means lower maximum heater power, but that may be dumbed down to temperature.</p>
<p>Another reason is due to ... | 2904 | Why do heating elements have lower rated temperatures in vacuums? |
2015-05-22T12:54:26.960 | <p>I have just begun studying mechanics of materials and I am struggling to understand intuitively <strong>how to select the area</strong> in first moment of area calculations. I was hoping someone has a relatively easy explanation.</p>
<p>The problem arises when calculating the shear stress <span class="math-container... | |mechanical-engineering|materials|beam|stresses| | <p>You're looking for $\tau_{xz}$, which pertains to horizontal shear flow along the top flange. (Rather than the vertical shear flow considered in $\tau_{xy}$.) As Mark noted, the shear flow starts from the center of the flange and flows outward/down.</p>
<p><a href="https://i.stack.imgur.com/2HHJI.png" rel="nofollow... | 2905 | How do you select the correct area to consiser for first moment of area calculations? |
2015-05-23T14:01:24.447 | <p>System with compressed air seems more expensive and harder to build and integrate neither using simple electromagnetic drives to open public transport doors.</p>
| |transportation|motors|compressed-air| | <p>Do you mean, for example, a bus entry door? It may be as simple as the "service factor" for motors ("electromagnetic devices") as compared to pneumatics. Inexpensive motors with sintered bronze bushings wear out, and better ones with actual bearings must be routinely lubricated. Air-operated cylinders are cheap and ... | 2917 | Why does public transport uses compressed air to open doors instead of electromotors? |
2015-05-23T15:44:27.637 | <p><strong>Background</strong></p>
<p>For a washing process after a crystallization we want to know how much filter area we would need and if said area will work for our fixed volume flow. </p>
<p><strong>Calculation</strong></p>
<p>$\dot{V_F}$ has a given value</p>
<p>Velocity $u$ should be the superficial vel... | |fluid-mechanics|chemical-engineering|process-engineering|fluid-filtration| | <p>Your math seems to be sound. It looks like you calculated everything correctly up to where you calculated $L$. At that point you should have all of the variables solved for and there should be no need to refine your numbers. </p>
| 2920 | Filter Area for given flow rate |
2015-05-23T19:54:09.733 | <p><img src="https://i.stack.imgur.com/iUTmzm.jpg" alt="image from the measurement result"></p>
<p>I know the current should be higher than 0.67 mA, because I know phones use current in the order of 1A. Also the charger is able to support up to 1A, it doesn't make sense that the charger would have such a superior curr... | |electrical-engineering|measurements|rf-electronics| | <p>It seems like the Monsoon Power Monitor might be the right tool for the job of determining current draw. This would give you very accurate current readings in real time.</p>
| 2924 | How much current is this phone drawing? |
2015-05-26T00:51:54.240 | <p>I'm working on a project that uses a strong stepper motor to power a wheel that needs to be able to "coast" freely at times. The motor is too stiff when not engaged, and along with my gearing ratio, makes it impossible to get the free-spinning coast** that I want from the wheel when the motor is not powered. I only... | |gears|stepper-motor| | <p>You can use a SPRAG type clutch from Altramotion.com </p>
<p>or a backstop that would spin the opposite direction which could act like a engagement gear. </p>
<p>But i still believe you can get a all in one unit from them for a SPRAG clutch that will be useful for you. </p>
| 2934 | How can I get a stepper motor to engage with a freely spinning wheel? |
2015-05-26T06:40:26.810 | <p>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. </p>
<p>I have had issues with the distribution of fibers in the concrete. I am trying to find a way to develop a stochas... | |civil-engineering|materials|modeling|concrete| | <p><a href="https://engineering.stackexchange.com/questions/4182/how-do-i-calculate-an-estimate-for-the-properties-of-a-composite-material">Related - how do i calculate an estimate for the properties of a composite material</a></p>
<p>The reference to <a href="https://www.library.ucdavis.edu/wp-content/uploads/2017/03/... | 2935 | Developing a stochastic differential equation model for concrete fibers |
2015-05-26T15:40:08.587 | <p>I was trying to find the moment of area about point A on the following figure:</p>
<p><img src="https://i.stack.imgur.com/mN8FS.jpg" alt="enter image description here"></p>
<p>I prefer to use integration, since it can be extended to different shapes, and did this:</p>
<p>$\displaystyle Q_z=\int_{-25}^{25}\int_{-2... | |mechanical-engineering|geometry| | <blockquote>
<p>What is the meaning of the sign (if there is any)?</p>
</blockquote>
<p>There is no physical meaning associated with the negative sign in your result; it just means you got the math wrong.</p>
<p>The integral definition of the first moment of area is $\iint_A {r(y,z) \, dA}$, or the sum over the ent... | 2940 | First Moment of Area - Meaning of Sign/Sense |
2015-05-27T14:29:06.947 | <p>What is the minimum number of TET elements you need, in order to fully fill a cube(HEX element)?</p>
| |finite-element-method| | <p><img src="https://i.stack.imgur.com/BmlXi.png" alt="5 tet elements"></p>
<p><strong>Image 1</strong>: 5 tetrahedral elements can form a cube.</p>
<p><a href="https://www.youtube.com/watch?v=XAhgw2Z4T2M" rel="nofollow noreferrer">This video</a> shows how to decompose a cube into five tetrahedra. Not saying it can't... | 2949 | Minimum number of tetra elements required, to represent a cube? |
2015-05-27T16:11:54.837 | <p>Each power plant has a load gradient characteristic, describing to what extent it can change the output of its generators in a given timeframe. Reading the literature, I know that, for example, a gas turbine power plant has a vastly higher load gradient than a one that uses coal as its primary energy.</p>
<p>Howeve... | |electrical-engineering|thermodynamics|power-engineering| | <p>A gas turbine plant basically uses jet engines optimized for shaft power instead of exhaust push to drive the generators. These can be controlled quickly because there is little stored energy. You reduce the fuel flow rate, and the turbine pretty much has to slow down quickly, within a few seconds, taking tens of ... | 2953 | What limits a power plant's load gradient? |
2015-05-28T21:40:02.537 | <p>I am working on a compressed air energy storage system. The size and weight of the system are heavily constrained; nothing should (ideally) exceed a few pounds. For this reason, I would like to store the energy (compress the gas) and extract the energy (make the gas do work) with the same mechanism <strong>in a rota... | |mechanical-engineering|motors|compressed-air|energy-storage|compressed-gases| | <p>I'm not an expert on air compressors or motors, but from my limited knowledge I think as you say that the centrifugal compressor would be the best for compression and a Tesla Turbine would be ideal as the motor. I think it should be possible to mount them on the same shaft but in separate airtight chambers, with som... | 2966 | Air compressor that doubles as a pneumatic motor? |
2015-05-28T22:46:41.087 | <p>What would the adhesive strength of chewing gum be? Would it be enough to support a car bumper? I'm more interested in how much tensile strength chewing gum has. I'm working on a project regarding the used cars movie, and in the movie, the salesman repaired a bumper that was unconnected with chewing gum.</p>
<p>The... | |materials|automotive-engineering| | <h1>Short Answer</h1>
<p>Yes it can hold. Because there are 10 brackets on a '57 Chevy front bumper and some more on rear bumper but not all of them are always under load conditions. A broken bracket or lost screw can be compensated with chewing gum.</p>
<h1>Long Answer</h1>
<p>I haven't seen an actual '57 Chevy Sed... | 2967 | Adhesive strength of chewing gum |
2015-05-29T01:14:45.657 | <p>I'm working on designing a Cold Spray system that uses a convergent-divergent nozzle to achieve a 800 m/s exhaust velocity. I'm assuming 400 psi nitrogen at room temperature is provided at the inlet of the nozzle. The throat area is 0.0859 square inches (tiny, I know). </p>
<p>$$
\begin{align}
\dot{m} &= \... | |mechanical-engineering|aerospace-engineering| | <p>You're not that far off. In your analysis, you've just neglected the fact that the gas will accelerate as it passes through the converging nozzle. This is basically converting potential energy, in the form of pressure, into kinetic energy, velocity. As a result, the gas will no longer be at 400 psi when it reaches ... | 2968 | Convergent-Divergent Nozzle Design from Exhaust Velocity |
2015-05-28T23:54:37.397 | <p>I'm planning to build a laser shooting target. Something like this:</p>
<p><a href="https://i.stack.imgur.com/RXQlM.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RXQlMm.jpg" alt=""></a></p>
<p>In the long term I want to build something advanced like a professional grade target, in which the us... | |electrical-engineering|optics|photonics| | <p>Briefly:</p>
<p>The way to distinguish your signal from any others (and incidentally get a massive gain in signal to noise ratio) is to use modulation. The simplest modulation scheme just turns the laser on and off very quickly (a few MHz) and your detection circuit (synchronized with the switching of the laser) AD... | 2974 | Focusing light from a laser shot into one point |
2015-05-31T12:08:08.527 | <p>My question is "what is the need of using auxiliary carry?" I mean 'AC' flag is set when D3 generates a carry. Then why not different flags for D2 or D4? </p>
<p>Why suddenly we are treating D3 carry in a special way? </p>
| |electrical-engineering|embedded-systems| | <p>Auxillary carry flag is used in microprocessors to carry out BCD arithmetic operations.</p>
<p>As hexadecimal is used to carry out operations in microprocessor, we need to find a way to convert the answers in decimal( if we want decimal arithmetic). In 8085 microprocessor this process is carried out by commands like... | 2986 | What is the need of having a separate flag as Auxiliary carry in microprocessor 8085? |
2015-05-31T17:59:30.210 | <p>Some laser applications consist simply of concentrating light into a small spot. Two example applications are laser welding and cutting. In these cases a CO<sub>2</sub> laser is often used which needs a regulated power supply, a water cooling system, and a supply of CO<sub>2</sub> gas. </p>
<p>Why do these applica... | |optics|lasers| | <p>This is just an addition to the answer of Chris Mueller.</p>
<p>When you think about lasers, you always think about an aperture with lot of mirrors, lenses and optics in general. Lets say that you manage to create a focused (wide spectrum) beam at one point, now you want to bring it to the point of application. Wit... | 2991 | Why are lasers used for concentrated light applications instead of incoherent light sources? |
2015-05-31T19:05:56.117 | <p>Lasers have a wide range of applications, but can be very costly to produce at high power/intensity. Since light is nothing more than a narrow band of the electromagnetic spectrum, it makes me wonder if the same high power/intensity applications can be achieved at a lower cost by concentrating other wavelengths (e... | |electrical-engineering|lasers|photonics| | <p>I would just like to add, in addition to the other answers regarding the EM spectrum, that anything that follows the <a href="https://en.wikipedia.org/wiki/Wave_equation" rel="nofollow">wave equation</a> can be focused because all of the principles of constructive and deconstructive superposition apply. </p>
<p>Thi... | 2992 | Can all electromagnetic spectra be focused like a laser? |
2015-06-01T13:07:21.207 | <p>I'm interested in the usage of a self-Locking hex nut with a nylon insert (ISO 7040 or DIN 985).
How is it used correctly? Is there a prescribed usage, or a norm that describes how it should be used? </p>
| |civil-engineering|bolting| | <p>The biggest consideration is that the thread must fully engage the nylon ring. If your bolts are too short, the nylon won't do it's job by deforming to the shape of the threads. Depending on how critical your application is, in many industries they are considered single-use as the nylon gets less effective the more ... | 3000 | How is a self-locking hex nut (ISO 7040) used? |
2015-06-01T19:52:11.580 | <p>I'm using a 10/100/1000 BASE-T fiber transceiver. </p>
<p>What does this mean?</p>
| |lasers| | <p>The 10/100/1000 refers to the transmission rate in megabits per second<br>
= millions of bits per second.<br>
Also may be shown as Mbps or Mb/s.</p>
<p>1000 Mb/s is a data rate typically achieved by modern LAN interfaces.</p>
<p>10 and 100 mb/s are the maximum rates achieved by older standards.
A 10/100/1000 labe... | 3005 | What is the "10/100/1000 BASE-T" laser/transceiver rate unit signifying? |
2015-06-02T17:38:46.190 | <p>Lift produced by an airplane wing is related to airspeed - this much is clear; a plane moving too slowly will stall. But what is that relation? Linear? Quadratic? Exponential? I don't need the exact equation, which is surely quite complex, just the character of the relation.</p>
| |fluid-mechanics|aerospace-engineering| | <p>It's all based in air pressure. Lifting requires velocity because it needs to create pressure gradients between the wing profile, so the air that is lower in pressure in the bottom part of the wing tend to equalize with the pressure in the upper part. When you stall, that means that you are no longer creating pressu... | 3018 | How is lift related to airspeed? |
2015-06-02T23:21:04.027 | <h3>Summary</h3>
<p>A short way to phrase this question is:<br>
<em>Shear</em> describes the translation of one part of a body relative to another given an applied force.<br> What is the equivalent rotational term? That is,</p>
<p><strong><em>What</em> describes the rotation of one part of a body relative to another ... | |mechanical-engineering|statics|terminology| | <p>What you're describing is a subset of the general concept of rigidity (or stiffness). I think the measurement you're looking for is the inverse of rotational stiffness (<a href="http://en.wikipedia.org/wiki/Stiffness#Rotational_stiffness" rel="nofollow noreferrer">as defined by Wikipedia</a>):</p>
<blockquote>
<p... | 3024 | How to describe the rotation of opposite ends of a body due to an applied moment |
2015-06-03T09:26:54.690 | <p>I have the utilization rates of several machines for each week over a year. These differ per week because of the occurrence of machine failures and changes of orders. Meaning that one week a machine could be a bottleneck and the other week not. I want to rank these machines based on the utilization and so determine ... | |statistics|industrial-engineering| | <p>The problem is a multi-criteria decision analysis (MCDA), as I want to rank the machines based on several (available) criteria. With initially the following criteria: downtime costs and utilization. However with utilization there was the following problem: if the events are counted that surpasses a threshold or the ... | 3030 | How to compare utilization rates? |
2015-06-03T15:09:56.840 | <p>If you have a prestressed concrete beam or slab and are jacking a cable from both ends, does the order of operations alter the result?</p>
<p>For a symmetric curve, the tension diagram along the cable's span after friction losses is always shown as symmetric. </p>
<p><img src="https://i.stack.imgur.com/zmWaO.gif" ... | |civil-engineering|structural-engineering|beam|concrete|prestressed-concrete| | <p>After the discussion with @sanchises in the comments, the answer is that, yes, the order of operations in jacking does affect the final tension diagram of the cable. A symmetric cable simultaneously jacked will have a symmetric tension diagram, while the same cable jacked from one side and then the other will not. T... | 3038 | Is the order of operations in jacking a cable relevant? |
2015-06-03T19:08:43.163 | <p>I'm building a pizza oven and, to do so, I bought a whole load of engineering bricks (not <a href="http://www.travisperkins.co.uk/Ibstock-Brick-Class-B-Perforated-Engineering-Red/p/123759">these</a> but similar). They've got five holes vertically through them, each hole is 2x6x6.5 cm (80 ml) and the walls, both end ... | |mechanical-engineering|thermodynamics|pressure|mechanical-failure|masonry| | <p>Engineering bricks (solid) are fired at 1200 degrees in a kiln so don't worry about your complicated mathematics , your pizza oven will never get to that temp.if it did or even if it got much much higher the bricks would just melt together.(They call them clinkers)
I am a bricklayer with 47 years experience and a lo... | 3041 | Would engineering bricks explode if used to build an oven? |
2015-06-04T02:10:11.593 | <p>All these processes sound like structural change caused by heating.</p>
| |process-engineering|metallurgy| | <p><strong>Annealing</strong> is a heat-treatment process for stress-relief of a material. Annealing facilitates reduction of internal stresses and total elastic energy stored in inter-atomic bonds within a treated material. The term is used for appropriate heat-treatments of metals, ceramic glasses, and high-performan... | 3047 | What's the difference between annealing, curing and sintering? |
2015-06-04T21:27:52.493 | <p>There are multiple algorithms out there for generating synthetic EKG signals (for test and validation of heart rate estimation algorithms). All you plug in is the desired heart rate, and the algorithm outputs an EKG signal with the desired heart rate.</p>
<p>I need to create a similar algorithm - but for pulse oxim... | |biomedical-engineering| | <p>Short: </p>
<p>(1.) Mindless and without understanding method that would work well.</p>
<p>This is as quick and easy as is likely to be possible, should work 'well enough' and would be 'easy enough' to implement without any in depth understanding past ensuring that simulated sensor output characteristics (impedan... | 3058 | How to generate a synthetic infrared and red LED signal for SPO2 calculation |
2015-06-05T03:34:50.300 | <p>The obvious answer is a compass. I have an old (1952) transit that has a compass which seems to be accurate to 15'. However, that doesn't seem too incredibly accurate at all. Furthermore, most modern digital theodolites I see don't appear to have a compass (correct me if I'm wrong). I'm curious how a surveyor actual... | |measurements|surveying| | <p>You can use software like Stellarium to know at what exact time the sun will cross the meridian. At that time, you should cast a straight shadow on the terrain using a vertical pole. This line (the shadow) will go true North-South. In fact, you can know the angle with respect to true North of any straight pole shado... | 3061 | What instrument does a surveyor use to accurately find North? |
2015-06-05T15:35:15.687 | <p>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 turns?</p>
| |mechanical-engineering|automotive-engineering| | <p>What you are talking about is called <a href="http://en.wikipedia.org/wiki/Ackermann_steering_geometry">Ackerman steering</a> and is pretty easy to get approximately right, but requires non-linear proportional steering control to get fully right.</p>
<p>If you put an imaginary focus/center point of steering somewhe... | 3066 | How to calculate the steering ratios on multiple axle vehicles? |
2015-06-06T06:37:45.013 | <p>I've heard that the part of a tire which is towards the inner side of a vehicle has material which is more wear resistant than the part of a tire on the outer side of the vehicle. </p>
<p>In short, I have difficulty with identifying the inner side of a tire. Is there a difference in the material properties of tir... | |mechanical-engineering|materials|automotive-engineering| | <p>There are <a href="https://www.kaltire.com/whats-difference-directional-asymmetrical-symmetrical-tread-patterns/" rel="nofollow">Tread pattern differences</a>, which allows part of the tire to make good contact with the ground for performance (grip). Part of the tire with wide channels to evacuate water (typically c... | 3073 | Are tires symmetrical & are their material properties uniform? |
2015-06-06T23:35:28.910 | <p>My apologies for a likely very simple question. But what is this nut which I have on a micrometer head called, and what is the tool for removing it called?</p>
<p><img src="https://i.stack.imgur.com/PjMOA.jpg" alt="micrometerhead"></p>
| |mechanical-engineering|nomenclature| | <h1>Short Answer</h1>
<p>The nut on it is called a <strong>slotted lock nut</strong> or <strong>locking bearing nut</strong>. You can remove it with a <strong>hook spanner</strong>.</p>
<h1>Long Answer</h1>
<p>I guess your micrometer is Japanese and thus probably doesn't conform DIN standards but for slotted lock nu... | 3077 | What is this nut on a micrometer head and what is the tool for removing it called? |
2015-06-07T01:35:19.467 | <p>I have some university work to do based on a real world application with five or <a href="http://en.wikipedia.org/wiki/Six-bar_linkage" rel="nofollow">six bar mechanism</a>, but I am unable to find such a device. Are there real applications of such mechanisms? I've considered some, such as the trigger of a gun and a... | |mechanical-engineering|kinematics|linkage| | <p>To find a ready-made device that utilizes a six-bar mechanism, you can dig through some of the classical resources below. Instead of pointing out a few devices, I think it would be better to point you to these databases.</p>
<ol>
<li><strong>507 Mechanical Movements: Mechanisms & Devices</strong>. <a href="http... | 3078 | Applications of Five-Bar Mechanisms |
2015-06-07T03:00:57.307 | <p>I am affixing a servo motor with a machined enclosure to a base plate with drilled holes. The current design uses eight M-2.5 bolts in a figure U pattern (3-2-3) around the enclosure.</p>
<p>Tightening that many bolts/screws takes time, and the small gauge makes them finickier than larger-gauge bolts (missed nut th... | |bolting| | <p>In the machinery industry the holo-krome bolt selectors are used regularly to get tightening torque and resultant bolt tensions: the green one is for inch and blue is for metric: <a href="https://www.google.com/#q=holo-krome+screw+selector+cards" rel="nofollow">https://www.google.com/#q=holo-krome+screw+selector+car... | 3080 | Many small bolts, or few large bolts? |
2015-06-07T11:08:09.377 | <p>I want to create a solar powered kettle but first, I need to know how much power will be required. </p>
<p>This means, I think, I'll need to know how much water I want to bring up to a certain temperature. </p>
<p>I'm trying to understand how to work this out, and I'm frankly stumped.</p>
<p>Is it possible to wor... | |mechanical-engineering|electrical-engineering|thermodynamics|solar-panel| | <p>The amount of water and how much you want to heat it only tells you the <i>energy</i> required, not the power. Power is energy per time, so it matters how fast you want to get there.</p>
<p>You say you want to heat 500 ml of water by 60°C in 30 minutes. Do the math.</p>
<p>The specific heat of water is 4.18 ... | 3085 | Solar powered kettle - how much power for 1/2 litre |
2015-06-07T14:56:01.723 | <p>From what I understand, a control systems engineering job is almost always a senior level position. What kind of entry level jobs do most engineers have before they are qualified to actually design control systems? Is a PE license necessary for this kind of work?</p>
<p>I am currently working on a masters degree in... | |control-engineering|control-theory|employment| | <p>I recommend you to learn control theory while implementing what you learn directly.
a useful example to do so ,this course for mobile robots using control theory
<a href="https://www.coursera.org/learn/mobile-robot/home/info" rel="nofollow">https://www.coursera.org/learn/mobile-robot/home/info</a>
and in each lec... | 3087 | How does one become a control systems engineer? |
2015-06-08T23:54:06.047 | <p>So I got myself questioning what could be worse for the driver... a collision of two identical cars at equal speed (frontal crash) or the same car with the same speed crashing through a wall? The first case I see it would double the impact, but also it will absorb the energy into the other car structure, otherwise, ... | |automotive-engineering|safety| | <p>I'm guessing you haven't seen the <a href="https://www.youtube.com/watch?v=r8E5dUnLmh4" rel="nofollow">Mythbusters episode</a> on this.
Then, see <a href="http://www.wired.com/2010/05/mythbusters-energy-explanation/" rel="nofollow">this writeup</a> that explains why they are correct, since Mythbuster's explanation l... | 3099 | Which is Worse: Car vs. Car or Car vs. Wall? |
2015-06-09T01:44:08.630 | <p>The dimensions of the container for the water is 6.06m by 2.44m the depth of water is at 1m equating to 14.786m^3 or 14,786 ℓ of water.</p>
<p>The sytems is a closed system with a pump circulating the water 150 ℓ/min @ 1100 bar. How long would it take for the water to heat up from 20*C to 30*C?</p>
<p>How would th... | |thermodynamics| | <p>These two very simple to use formulas will probably allow easy order of magnitude scoping. </p>
<p><strong>Time to heat with given heating power</strong> </p>
<p>T = V x 1000 cc/l x 4.17 x K / W seconds
or T = 4170 V.K/W</p>
<p><strong>Power required to heat in time T</strong> </p>
<p>Power = W = = V x 1000 cc/l... | 3101 | Calculating time to heat up water at flow rate of 150 ℓ/min. @ 1100 bar |
2015-06-09T11:47:12.390 | <p>I would like to get a simple estimation of the parameters for a humidity chamber system. The humidity chamber has one constant inflow ($k_1$) and and outflow which depends on the humidity of a neighbor humidity chamber (diffusion, modeled as $k_2(RH_{ext} - RH)$. $RH$ is the humidity of the chamber, $RH_{ext}$ is th... | |measurements|modeling|control-theory|systems-engineering| | <p>It sounds like you have <a href="http://uk.mathworks.com/products/matlab/" rel="nofollow">MATLAB</a>, so it's a simple linear fit:</p>
<ul>
<li>From your vector $RH(t)$, compute $\frac{d RH}{dt}$ by numerical differentiation</li>
<li>Create a matrix $A$ with ones on the first column and the values of $RH_{ext}(t) -... | 3106 | Parameter Estimation for First Order System |
2015-06-09T14:31:28.457 | <p>When studying the strength of materials at the introductory level, we often make five simplifying assumptions.</p>
<ol>
<li>Material is homogeneous and isotropic. </li>
<li>Material obeys Hooke's law </li>
<li>Body is assumed to be prismatic </li>
<li>Effect of self-weight is neglected </li>
<li>Load is assumed... | |mechanical-engineering|materials| | <p>(Warning: this answer is skewed towards static applications - dynamic applications like the self-weight of a moving cable or a vehicle are much more complicated.) In actual applications, self weight is usually significant and it's fairly rare that you can neglect it for a real-world system. However, there are a numb... | 3110 | When can the effect of self-weight be neglected? |
2015-06-09T15:43:24.007 | <p>I have been <a href="http://www.lab-quip.co.uk/dynamic-cone-penetrometer-dcp" rel="nofollow">reading about DCP</a> and watched <a href="https://www.youtube.com/watch?v=UadgMNG-LWA" rel="nofollow">a video</a> of how it is done (the video is not in English). But there are some things that are still unclear and I would... | |geotechnical-engineering| | <h3>Standard</h3>
<p>The official description of the test can be found in one of the following depending on your location of interest:</p>
<ul>
<li><a href="http://shop.bsigroup.com/ProductDetail/?pid=000000000030087025" rel="nofollow noreferrer">BS 1377 Part 4</a></li>
<li><a href="http://www.astm.org/Standards/D6951.... | 3115 | Dynamic Cone Penetrometer (DCP) results and correlation |
2015-06-10T12:11:25.607 | <p>Yesterday, I tried to find constants $k_1$ and $k_2$ for the following system:</p>
<p>$$\frac{\mathrm d RH}{\mathrm dt}=k_1+k_2(RH_{ext}-RH).$$</p>
<p>Now, I have some first computations for $k_1$ and $k_2$ and would like to test how good a simulation with these parameters works. I think I could also write this as... | |measurements|modeling|simulation|systems-engineering| | <p>Yes, if you have values for <code>k1</code> and <code>k2</code>, data for <code>RH_ext</code> and <code>t</code>, your suggestion would work although I think you have your matrices wrong. You probably need to define <code>x</code> as <code>RH - k1/k2</code> to get rid of the constant term:</p>
<pre><code>A = -k2;
B... | 3122 | Simulation of First Order System (Matlab & Simulink) |
2015-06-10T18:10:07.387 | <p>I have this differential equation:</p>
<p>$\dot{\eta (t)}=\frac{-2\eta(t)}{C(\widehat{R}+\Delta R)}+\frac{K^2 L}{C E^2 (\widehat{R}+\Delta R)}+K$</p>
<p>which, my book says, correspond to a LTI system, asymptotically stable with a constant input:</p>
<p>$\frac{K^2 L}{C E^2 (\widehat{R}+\Delta R)}+K$</p>
<p>It sa... | |control-theory|mathematics| | <p>Think for a moment about what it means for $\eta(t)$ to have reached its <strong>steady</strong> state. It means precisely that $\dot{\eta}(t)=0$. If you plug that into your first equation and solve for $\eta(t)$ you get your solution as you've already observed. </p>
| 3130 | Steady state value, a possible shortcut? |
2015-06-10T19:32:53.503 | <p>One antonym word I can think of is "derating". If I say "derate motor for pump X", it can mean "select a motor with lower power output, since the pump doesn't need a more powerful motor".</p>
<p>But what about selecting a more powerful motor? How can I say "I want to ____ the motor for this pump" and mean "up" th... | |motors|sales|communication| | <p>Quite sure the word used is "oversized". When you say to an engineer that a motor is oversized for that application (for that pump) the engineer will not think the motor dimensions are too big (and will not fit) but he will understand as the motor rated values would exceed the minimum requirements by an unexpected h... | 3132 | Is there a universally accepted way to refer to choosing a more powerful motor for an application? |
2015-06-11T14:09:29.923 | <p>The four sides of the <em>Great Pyramid of Giza</em> are oriented to the four cardinal directions of the compass (north, west, east, south).</p>
<p><strong>Did I.M. Pei do the same with the <em>Louvre Pyramid</em>?</strong></p>
| |engineering-history|architecture| | <p>It doesn't appear so:</p>
<p><img src="https://i.stack.imgur.com/zGrdW.jpg" alt="enter image description here">
(screen shot <a href="https://www.google.be/maps/@48.860611,2.337644,745m/data=!3m1!1e3" rel="nofollow noreferrer">from google maps</a>.)</p>
| 3139 | Is the Louvre Pyramid oriented to the four cardinal points of the compass? |
2015-06-11T16:21:06.690 | <p>$\frac{0.25}{s^2+0.5s}$</p>
<p>Can I use formulas for 2nd order systems in <a href="http://www.ece.unm.edu/course/ece345/lectures/LectureNotes4.pdf" rel="nofollow">this pdf</a>?</p>
<p>If not, how can I understand if this sytem is underdamped, damped, etc?</p>
| |control-engineering| | <p>You can initially consider the system to be $$\frac{\frac{0.25}{\epsilon}\epsilon}{s^2+0.5s+\epsilon}$$ </p>
<p>This gives $\omega =\sqrt{\epsilon }$ and $\zeta =\frac{0.25}{\sqrt{\epsilon }}$.</p>
<p>In the limit $\epsilon \to 0$, $\omega \to 0$ and $\zeta \to \infty$. From the latter we conclude that it is dampe... | 3141 | How to calculate of Second-order system Frequency and Time domain values? |
2015-06-11T17:20:10.830 | <p>I was wondering how the values of thermodynamic properties as enthalpy, entropy, internal energy, specific heat, specific volumes ... etc, of gases and liquids are calculated using programming libraries such as <code>cantera</code> and <code>thermopy</code> as an example.</p>
<p>How are steam tables made for instan... | |mechanical-engineering|thermodynamics|numerical-methods| | <p>If you assume the gas you are dealing with is a semi-perfect gas (e.g. the heat capacity is not a function of pressure, and the gas follows ideal gas law), then you can calculate all properties (in the order of enthalpy, internal energy, entropy and gibbs free energy) if you can measure the specific heat capacity at... | 3143 | How are thermodynamics properties of gases and liquids calculated numerically? |
2015-06-12T03:28:32.003 | <p>I bought a germicidal UVC florescent lamp online and i would like to put it in a an 20 inch box for sanitation uses. After going to the hardware store I couldn't find any light that is compatible with the T8 light bulb other then this 15 Watt fixture:</p>
<p><a href="http://www.homedepot.com/p/Lithonia-Lighting-1-L... | |electrical-engineering|power-electronics| | <p>Well that's a lot of light (and heat) for fixture rated for a 15W lamp. And of course, UVC light is not good for skin and eyes. Here is some <a href="http://www.americanairandwater.com/lamps.htm" rel="nofollow">more info</a> about UVC lamps.</p>
<ol>
<li>Actually, no, the opposite. The lamp will attempt to draw mor... | 3149 | What will happen if I install a 46 watt fluorescent bulb on a 15 watt light fixture? |
2015-06-12T03:52:35.640 | <p>I'd like to know which stainless steels are good for heating on an induction stove. Wikipedia <a href="http://en.wikipedia.org/wiki/Induction_cooking#Cookware" rel="nofollow">notes</a> that the surface <s>resistance</s> resistivity is a good figure of merit. However, that article only lists the surface <s>resistance... | |materials|steel| | <blockquote>
<p>... that article only lists the surface resistance for 430 & 432 stainless steel -- the better being 432. However, I cannot find 432 from my favorite supplier, although they do have 430. Will 430 have a similar surface resistance?</p>
</blockquote>
<p>Yes.<br>
430 and 432 are listed as having alm... | 3150 | What stainless steels are good for induction heating? |
2015-06-12T04:54:03.063 | <p>What is safe and what is acceptable in the context of Engineering.</p>
<p>Specifically speaking we are in the process of designing a test rig which will pump water. What is a maximum safe temperature for the water to achieve without infringing employee safety. ie water at ${90}$ $^oC$ will burn so clearly that's no... | |safety| | <p>A common refrain in these kind of discussions is "there is no such thing as safe, only safer." Nothing we make is perfectly safe in an absolute manner - we don't design buildings to withstand asteroid impacts and we don't design cars to survive falling off a bridge. Instead, when we say safe, we usually mean "safe e... | 3152 | How does one define 'safe' in engineering? |
2015-06-12T19:51:41.537 | <p>I need to install an actuators to LABVIEW base test system because the old actuators are defective. We cannot purchase the old actuators because they are obsolete. The old actuators communicated using the COM ports 1 and 8. The COM port are hard coded in the LABVIEW program. The new actuators communicate via a USB i... | |software|labview| | <p>What you might need to do is to remove the "in use" port and then assign the respective COM port. Follow is a suggested set of steps.</p>
<ul>
<li>Open command prompt (Start > Run) and type: <strong>cmd</strong> </li>
<li>At the prompt type: <strong>set devmgr_show_nonpresent_devices=1</strong> </li>
<li><p>Followe... | 3163 | Unable to install Actuators to a LABVIEW based Engineering Test System |
2015-06-12T20:48:46.163 | <p>I have been learning the program embedded systems using Keil µVision 4.7 free version from Mentor graphic. So far all the learning has be using projects that have been already pre-defined. This has worked well so far. I would like to take the next step. Below are some of the several tutorial that I have tried with o... | |electrical-engineering|embedded-systems| | <p>Here are some steps for a ARM Cortex-M4</p>
<ol>
<li>Close your current project in keil µVision, menu: projects->close project</li>
<li>Select "New uVision Project..." from "Project" menu
<img src="https://i.stack.imgur.com/q7ilH.jpg" alt="enter image description here"></li>
<li>open an empty new one, menu: project... | 3165 | How to create Embedded System Program from Scratch using Keil µVision? |
2015-06-13T22:07:23.317 | <p>So i had this experience when driving in a cold night, where my windshield just got all blurry. I knew that on the drivers manual they say you should turn the hot air and soon it will go off, but my friend that was on the passenger seat said the cold air will work too. We turned the AC off and re-experienced the fac... | |thermodynamics| | <p>I just came from a heavy rain in a cold day, and wanted to know if any body had posted about this.
My facts are that using only the heater, is more delayed and besides that all other car windows get fogged,
There after I left the heater on, and turned on the AC, and the result is amazing, not only the windshield cle... | 3174 | Which is better: Defog a car windshield with cold or hot air? |
2015-06-14T23:45:36.407 | <p>I need to find the emission power of a WiFi mobile phone antenna. I have checked the IEEE 802.11 specifications but it says that the power transmission is variable and depends on the mobile phone fabricant and power saving options. </p>
<p>I also searched for information about some specific mobile phones but the da... | |electrical-engineering|power-electronics|wireless-communication| | <p>There is a list of some widely used devices and their transmit power (and many other properties) in an easily digestible table: <a href="https://clients.mikealbano.com/" rel="nofollow noreferrer">https://clients.mikealbano.com/</a>
The most smartphones seem to be just around 20 dBm and the maximum lies around 30 dBm... | 3183 | How can I find the emission power of a WiFi mobile phone antenna? |
2015-06-15T09:15:38.480 | <p>I have to put together a small solar system for a college project. </p>
<p>I have solar cells with an output of 3.65A and 0.6V. Now if I paralel two groups of two cells connected in series I will double the amps and volts. And the output power will be like 8W. </p>
<p>The question is, do a 1.2V panel really work? ... | |electrical-engineering|solar-panel|photovoltaics| | <p>If you want to charge a 12 V battery, you need a bit more than 12 V.</p>
<p>One way to achieve that is to put enough individual cells in series. Another way is to have the panel produce a lower voltage and use a electronic circuit called a <i>boost converter</i>. These convert low voltage at high current to high ... | 3184 | 8W Solar panel high amperage low voltage |
2015-06-15T10:35:18.380 | <p>I have <a href="http://www.allpumpsdirect.co.uk/files/1806869/uploaded/FLJ%20Duplex%202%20Tech%20Data.pdf" rel="nofollow">specifications for a positive displacement pump</a> where, in the data table on the last page, the given flow rate is referred to in the column header as 'Open Flow.'</p>
<p>Is this the maximum ... | |mechanical-engineering|fluid-mechanics|pumps| | <p>The open flow is the flow rate through the pump where no pressure is developed. That is, if you have fluid coming in and out horizontally, and the input and output hoses are open to the outside air (not a closed system developing pressure. This is the most flow the pump will ever create.</p>
<p>Usually though, we u... | 3187 | What does 'Open Flow' mean for a pump flow rate? |
2015-06-16T11:29:21.090 | <p>I have been assigned to build a ramp for a small car. I have only one A2 sheet of paper, scissors and a stapler. What would be the best slope profile, in order to move the car as far as possible after leaving the ramp, using only gravity? Any other ideas on construction? </p>
<p>The car is 1:43 size. The weight is ... | |applied-mechanics| | <p>So there's a number of concerns that you want to think about. Some of these you'll have to determine experimentally, others you'll be able to calculate and then iteratively improve based upon your observations.</p>
<p>It should be understood / obvious that the higher up you can get the car, then the faster it will... | 3206 | How to build a paper ramp for a small car? |
2015-06-16T11:58:58.760 | <p>I have the task to connect 6 input sources of fluid with 9 output (sinks) sources. Each input should be connected to each output. Each input should be able to distribute the fluid to only 1 output at a time. I have straight pipes, Y connections and valves, that I can use. I should use the MINIMUM amount of valves an... | |fluid-mechanics|pipelines| | <p>I recommend approaching problems like this by starting with a base case and working up from there until you see a pattern.</p>
<p>For piping, the base case is a straight case with one input flowing to one output. Depending on the exact specs of the problem, this requires either 0 or 1 valves; it does not require an... | 3207 | Distribute 6 inputs to 9 outputs with pipes |
2015-06-16T21:30:06.937 | <p>I work in consultancy and I am designing a product for a customer. The customer has requested a specific PSU. I have contacted this PSU manufacturer and they request 6 L/min of coolant flow and minimum 3 Bar. I now have to specify a suitable pump to deliver these fluid characteristics to the PSU.</p>
<p>I have conf... | |fluid-mechanics|pressure|power-electronics|cooling|computer-hardware| | <p>The pressure requirement could also be to raise the temperature at which the water boils. The boiling point of water depends on the pressure it's at; higher pressure raises the boiling point, as the following image shows.</p>
<p><img src="https://i.stack.imgur.com/ZPggh.png" alt="Image taken from www.engineeringto... | 3215 | Why is minimum pressure specified on a PSU water cooling circuit? |
2015-06-17T02:28:36.597 | <p>I have here a heating element that broke when it was used to ramp a furnace to 750 C, breaking at 740. The element had previously been used for higher temperatures and appears that it may have possibly shorted. The shape of the element is custom, as well as the furnace, and so we had a custom element machined with a... | |mechanical-engineering| | <p><strong>EDIT</strong> Just read the comments, #3 might be the best option, as #1 won't work, and #2 wont shape it, just hold it in place. </p>
<p>First thing I am assuming is that this stays in the ceramic as it is heated. </p>
<p>A couple things I would try:</p>
<ol>
<li>Fit the coil in the ceramic like the bo... | 3220 | How do I manually shape this heating element? |
2015-06-17T08:36:55.010 | <p>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 away from the tower (the rotor is fixed to the axis which is fixed to the tower. The axis isn't fixed to the head in an... | |electrical-engineering|motors| | <p>The device you are looking for is called a <a href="https://en.wikipedia.org/wiki/Slip_ring" rel="noreferrer">slip ring</a> such as the one shown below. These devices use internal components which maintain contact as they spin (old ones used brushes) allowing them to turn by an unlimited amount in either direction.... | 3221 | Avoid snapping an electric cable from too much rotation |
2015-06-17T14:34:06.153 | <p>How do we start a nuclear chain reaction? For example, if we wanted to do it this weekend, what would we need, and what are the basic steps? I'm not looking for a text book response or highly detailed information. I'm only curious about the most basic components. For example, we need to take A and B and submerge it ... | |nuclear-technology|nuclear-engineering| | <p>Nuclear fission is spontaneous. In fact, if you have a critical mass of fuel assembled, you need to take explicit steps to keep it from going into chain reaction, typically by adding neutron-absorbing material, AKA "control rods" to the assembly. When you remove the control rods, the reactor starts up by itself.</p>... | 3227 | How does a nuclear reactor initiate nuclear fission? |
2015-06-17T20:57:46.077 | <p>My North American facility is looking at a major shut down this fall. In the area, three other large facilities are also doing either shutdowns or expansions in the fall. </p>
<p>A last minute project that I have been assigned requires a couple of weeks of machining custom components. This is an issue as none of... | |machining|project-management| | <p>At very highly level the three areas that need to manage are scope, cost and time also known as the triple constraints. </p>
<p><strong>Scope:</strong><br>
Make sure the sponsor clearly defined the project. It is highly unlikely that the sponsor will document the scope. Therefore you need to document the scope and ... | 3234 | Going distant in sourcing machining |
2015-06-18T07:10:50.970 | <p>Trivially you can prevent rocking with many vehicle by eliminating the suspension. But is it possible to allow a floaty suspension that glides over potholes, without also having to rock back and forth, with some kind of stabilization? I know that it's possible in buildings, but having a fixed platform really helps.<... | |mechanical-engineering|applied-mechanics|automotive-engineering| | <p>The <a href="http://en.wikipedia.org/wiki/Citro%C3%ABn_Xantia" rel="nofollow noreferrer">Citroën Xantia Activa</a> was one of the earliest mass production active suspension vehicles I know of.</p>
<blockquote>
<p><strong>Activa active anti-roll bars</strong></p>
<p>In 1994, the Activa technology was introduced, whic... | 3238 | Is it possible to design a bus that doesn't rock? |
2015-06-19T00:54:54.150 | <p>My project team and I delivered the design of a 14ha urban infrastructure development in Sydney for a Client. The project was to hand over the development at a Tender level of design, which would be tendered upon by a number contractors. The succesful bidder would then take on the rest of the project as a Design and... | |civil-engineering|modeling|design|computer-aided-design| | <p>Before I start, let me disclose that I don't know a lot about the details of infrastructure projects or your file format, but I think the general considerations are fairly universal.</p>
<p>There are a number of considerations when providing your digital model to a contractor, and in my work I have decided to offer... | 3247 | Sending out a 12d Civil Design Model |
2015-06-19T13:35:22.110 | <p><a href="https://i.stack.imgur.com/Fieak.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Fieakm.jpg" alt="enter image description here" /></a></p>
<p>I have to solve the differential equation for radial disks, and therefore I need the shear force distribution. The disk is rotationally symmetric.</... | |mechanical-engineering|mathematics| | <p>When working with superposition method, any way of approaching the disc works - so long as you account for the reaction forces properly. In this context, it is important to ensure that the sum of the forces is always 0, so unknown reactions (like your simple support in the middle) can be factored in appropriately.<... | 3252 | Shear Force Distribution on disk |
2015-06-19T20:43:22.043 | <p>When testing a pressurized pipe with off-standard flanges, often times the materials available to fabricate a blind flange of the correct size are limited to what is around.</p>
<p>I've made it a habit of referring to Roark's formula's for stresses and strains, and going to the table for large deflection circular p... | |mechanical-engineering|piping|bolting| | <p>Given the clamping force of the bolts, I would think that Fixed and Held would be appropriate.</p>
<p>One way to test this is to calculate the edge tension (I don't recall if Roark's has formulations for this) and compare this to the clamping force of the bolts (i.e., the static frictional force between the flange... | 3257 | What boundary condition should I use for the edge of a blind flange? |
2015-06-20T08:23:30.653 | <p>I have machined parts that are made of aluminum and anodized black. The reason that I chose aluminum is because:</p>
<ol>
<li>It can easily be machined and is low cost and is common, so easy to buy</li>
<li>It is light weight compared to steel</li>
<li>It can take heat</li>
<li>It is easy to finish with oxidation<... | |mechanical-engineering|aluminum|cnc| | <p>I'm not sure how your part looks, but I can tell you about temperature and plastics.</p>
<p>I've blasted <a href="https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin" rel="nofollow">phenolic</a> composites with <strong>600 °F (310 °C)</strong> and haven't had a problem. There are high temperature epoxies and vi... | 3259 | Lightweight substitutes for machined aluminum parts |
2015-06-21T19:05:01.283 | <p>It is possible with a microphones array to isolate a sound coming from a direction. Is it possible with an array of photo diodes to isolate a light signal coming from one direction?</p>
<p>For example having 4 photo-diodes oriented at the same direction, spaced by 2 cm, and facing lamps at the ceiling, is it possib... | |electrical-engineering| | <p>This concept in general as it applies to microphones is known as <a href="https://en.wikipedia.org/wiki/Beamforming">beamforming</a>, and is most commonly applied to sound and radio waves. It is mostly aimed at wave forms that carry signals (ie change significantly over time,) but similar concepts could be used in y... | 3263 | Light signal isolation |
2015-06-22T12:26:39.303 | <p>Every scientific calculator I've come across has a DRG button that controls whether trigonometric functions use units of degrees, radians or grads yet I've never seen or heard of any system that actually uses grads. When is the grads setting useful?</p>
| |measurements| | <p>Grade is often used for inclination, such as looking at how steep a road is. The units are not as "crazy" as they seem, when you think of grade as a percentage. In other words, a hill can go down at anything from 0% (flat) to 100% (45 deg angle). (rise/run)
Based on some comments added below, it is not clear if t... | 3268 | What are grads used for on a scientific calculator? |
2015-06-22T17:37:19.177 | <p><a href="https://youtu.be/WOoUVeyaY_8?t=284" rel="nofollow noreferrer">In this video</a>, the video emphasises the very low recoil level of the AA-12 fully automatic shotgun. In particular, at <a href="https://youtu.be/WOoUVeyaY_8?t=300" rel="nofollow noreferrer"><strong>this point in the video</strong></a> the pres... | |mechanical-engineering|springs|firearms| | <p>There is a pervasive misconception that recoil can be "absorbed" by such things as springs and proprietary gas systems. This is not true; eventually all the recoil produced by launching the bullet must be absorbed by the shooter. The only thing that a spring/gas system can do is spread the recoil over a longer per... | 3273 | What is the simplest spring system that could produce recoil absorption comparable to that exhibited by the AA-12 assault shotgun? |
2015-06-23T22:02:27.137 | <p>We've had unusually dry weather and our well has run so low that we had to call in a water hauling company to refill it a few days ago.</p>
<p>The water man told me that even though he dumped in ~ 1000 gallons, a great part of it will seep out of the well to the surrounding (drier) aquifer, the same way groundwater... | |pressure|plastic|water-resources|waterproofing| | <p>Well liners are generally made to order. One of your issues will be to find a company that can make what you want. </p>
<p>You will need to ensure the liner is the correct size and that it does not tear when inserted into the well, while being filled with water, or when it is being removed from the well.</p>
<p>Yo... | 3300 | Can I seal the inside of a water well to use it as water reservoir when the well is dry? |
2015-06-23T23:38:25.450 | <p>I'm trying to do some processing of optical emission spectra from sputtering plasmas, and am confused by what NIST means by <a href="http://www.nist.gov/pml/data/handbook/index2.cfm">'easily reversed' in their notation</a>. Anyone have a clue?</p>
| |optics| | <p>This means that the line in question can be apparent or not depending on whether the spectrum has been absorbed for other reasons. Or as <a href="https://en.wikipedia.org/wiki/Spectral_line#Opacity_broadening" rel="nofollow">Wikipedia states</a>:</p>
<blockquote>
<p>...the reabsorption near the line center may be... | 3303 | What does 'easily reversed' mean in the NIST spectral database? |
2015-06-24T02:06:03.477 | <p>Is there a formula to calculate the grip generated by a tyre on a vehicle for a given surface?</p>
<p>I have a 13,000 kg machine pulling nearly 200 N of weight. I need to figure out if we need to put any more weight onto the machine so that it has enough traction to start the initial pull. It's going to use pneumat... | |mechanical-engineering|automotive-engineering| | <p>According to the <a href="http://www.engineeringtoolbox.com/friction-coefficients-d_778.html">engineering toolbox</a> the coefficient of static friction between a tire and pavement ranges between $\mu_{wet}=0.2$ for a wet surface and crappy tire and $\mu_{dry}=1$ for a dry surface and high quality tire. You can use... | 3306 | Calculating the grip of a tyre for a given surface |
2015-06-24T13:16:54.330 | <p>I've been working with SC magnet quench simulations. The conductor is made from NbTi in a Cu channel with a 5:1 ratio of Cu:NbTi. Opera3d has a quench program with an example that I began working from. In a quench scenario using a solenoid made from the conductor I described above heat propagates at different speeds... | |thermodynamics|magnets|superconduction| | <p>You are not too far off with parallel and series resistors method.</p>
<p>The <a href="https://en.wikipedia.org/wiki/Rule_of_mixtures" rel="nofollow">Rule of mixtures</a> for composite design works in the same fashion - by treating each of the <em>loads</em> as either springs in parallel (when loaded in the directi... | 3311 | Calculating Anisotropic Thermal Conductivity for two Materials |
2015-06-24T17:03:32.877 | <p>Our component sourcing organization purchases large amount of electronic components from suppliers. I believe this is through a bid process. Engineering provides the sourcing organization specification, and they purchase these parts for the plant to use in manufacturing. The issue is that recently the plant has been... | |electrical-engineering|statistics|quality-engineering| | <p>Looking for good and reliable suppliers might be one of best solutions. Vendors such as Digi-key, mouser, Newark always supply high quality electronic components. But understandably they come at a higher cost. If directly purchased from a manufacture it might be good idea to request for test data from suppliers to v... | 3315 | How to identify low quality electronic components early? |
2015-06-24T18:22:12.483 | <p>I'm doing a static analysis on a uniformly loaded cantilever beam in ANSYS APDL. I'm using BEAM188 with all the default options, so it uses linear form. for the element behaviour, which I think means the bending moments and tensions are linear within the element.</p>
<p>I want to plot the bending moments along the ... | |mechanical-engineering|finite-element-method| | <p>You might have got the answer if not,
come to your direct question for plotting actual bending moment. Just choose the element option key for "quadratic" instead of linear and re run the problem and plot the BMD.</p>
| 3317 | Results for Bending Moment using BEAM188 on ANSYS APDL |
2015-06-25T00:47:24.340 | <p>If I have an electric vehicle on an incline (m=17,300 kg) I want to figure out how much energy it would generate by regenerative braking. </p>
<p>I've used $a= g \cdot \sin({\theta}) $ and $f=m\cdot a$.</p>
<pre><code>at 05 deg incline, acceleration is 0.85 m/s/s; this creates a force of 11114.972 N
at 10 deg incl... | |electrical-engineering|automotive-engineering|regenerative-braking| | <p>The calculation perfectly right, bu the normal electric vehicle weights just 1/10th on the weight that you have considered. Hence the results are scaled in that ratio (10x more than what the real world EV could generate)... Hope that helps!</p>
| 3321 | How can I determine the power generated by a regenerative braking system? |
2015-06-25T09:02:53.780 | <p>I was reading about <a href="https://en.wikipedia.org/?title=CD-ROM">how CD-ROMs work</a> and I came to this: </p>
<blockquote>
<p>Although it might seem simplest to use a pit to record a 0 and a land
to record a 1, it is more reliable to use a pit/land or land/pit
transition for a 1 and its absence as a 0,so... | |optics|computer|computer-engineering| | <p>The explanation is incorrect. The laser is never more than half "in the pit". The reflection is land or 1/2 pit plus 1/2 non pit.</p>
| 3324 | Why is it more reliable to use the land/pit transition in a CD-ROM? |
2015-06-25T10:42:30.957 | <p>In lab we have Struers Tegrapol-21 grinding and polishing machine. I use it for sample preparation. Usually I put 6 samples at once and prepare them with sample holder. However today I need to prepare 3 samples. I checked <a href="http://www.struers.com/resources/elements/12/101288/TegraSystem%20brochure%20English.p... | |materials|metals|grinding| | <p>I personally have the tegrapol 11 and I use it with the tegraforce 1</p>
<p>Our units sample mover plate holds three specimens simultaneously (concept is the same though). Google tegrapol 11 and tegra force 1 for images if this is unclear.</p>
<p>Many times I run my sample mover plate both with only one and only t... | 3331 | How to use sample holder on Metallography specimen preparation machine Struers Tegrapol-21 |
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