# All Questions

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456 views

### How to verify results from a manometer/venturimeter?

I'm designing a system to determine pressure drops across thin samples while simultaneously measuring velocity (and through multiplying by area, volumetric flowrate). I need a way of determining how ...
475 views

### How are thermodynamics properties of gases and liquids calculated numerically?

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 ...
240 views

### How can I choose a motor for my project? [closed]

I'm working in a project that consists of something similar to a motorized skate. I know how to do it, but I don't know what motor to use. I need that the skate to be able to move 90 Kg to 20 Kph (12 ...
124 views

### How to calculate of Second-order system Frequency and Time domain values?

$\frac{0.25}{s^2+0.5s}$ Can I use formulas for 2nd order systems in this pdf? If not, how can I understand if this sytem is underdamped, damped, etc?
383 views

### Is the Louvre Pyramid oriented to the four cardinal points of the compass? [closed]

The four sides of the Great Pyramid of Giza are oriented to the four cardinal directions of the compass (north, west, east, south). Did I.M. Pei do the same with the Louvre Pyramid?
53 views

### Is there a universally accepted way to refer to choosing a more powerful motor for an application?

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". But what ...
65 views

### Steady state value, a possible shortcut?

I have this differential equation: $\dot{\eta (t)}=\frac{-2\eta(t)}{C(\widehat{R}+\Delta R)}+\frac{K^2 L}{C E^2 (\widehat{R}+\Delta R)}+K$ which, my book says, correspond to a LTI system, ...
275 views

### Plain bearings (plastic) in backlash free joints

I need to design some backlash free rotational joints for slow and intermittent movements (device for human-computer interaction) for my uni project. Possibly loaded in any direction; the loads won't ...
446 views

### Simulation of First Order System (Matlab & Simulink)

Yesterday, I tried to find constants $k_1$ and $k_2$ for the following system: $$\frac{\mathrm d RH}{\mathrm dt}=k_1+k_2(RH_{ext}-RH).$$ Now, I have some first computations for $k_1$ and $k_2$ and ...
177 views

### Dynamic Cone Penetrometer (DCP) results and correlation

I have been reading about DCP and watched a video of how it is done (the video is not in English). But there are some things that are still unclear and I would greatly appreciate some help and ...
839 views

### When can the effect of self-weight be neglected?

When studying the strength of materials at the introductory level, we often make five simplifying assumptions. Material is homogeneous and isotropic. Material obeys Hooke's law Body is assumed to ...
181 views

### Parameter Estimation for First Order System

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 ...
6k views

### Calculating time to heat up water at flow rate of 150 ℓ/min. @ 1100 bar

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. The sytems is a closed system with a pump circulating the water ...
11k views

### Which is Worse: Car vs. Car or Car vs. Wall?

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 ...
146 views

### What is the best method to model the input of an electro-mechanical system for control design and simulations?

In particular, say I have a dynamic model of the inverted pendulum / cart as described here. Instead of using the error difference in force to input into my controller, I want to take into ...
1k views

### How does one become a control systems engineer?

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 ...
368 views

### Solar powered kettle - how much power for 1/2 litre

I want to create a solar powered kettle but first, I need to know how much power will be required. This means, I think, I'll need to know how much water I want to bring up to a certain temperature. ...
34 views

### Corrosion of a galvanic couple made with silver and gold

If a bangle is made out of gold and silver, connected with each-other would there be a corrosion happening? If so can it be explained using the galvanic series? Also do those metals undergo oxidation ...
4k views

### Many small bolts, or few large bolts?

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. Tightening that ...
2k views

### Applications of Five-Bar Mechanisms

I have some university work to do based on a real world application with five or six bar mechanism, but I am unable to find such a device. Are there real applications of such mechanisms? I've ...
608 views

### What is this nut on a micrometer head and what is the tool for removing it called?

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?
3k views

### Why do we pave roads instead of making them from removable parts?

If roads were made of removable parts, we'd probably have fiber cable internet everywhere by now I'd say. It'd be so much easier to install e.g. new electricity and water infrastructure and to ...
99 views

### Are tires symmetrical & are their material properties uniform?

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. In short, I have ...
601 views

### Pressure drop across a damper vs rotor stator pressure increase

I am recalling from a turbo machinery course that a series of rotors and stators in a turbo machine operate like this. The air enters the machine and the rotors speed up the air so it slams into the ...
429 views

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

I'm building a model of a long vehicle with 6 axles and I want to be able to steer it. How do I calculate the amount each axle should steer to minimise dragging of some wheels round sideways as it ...
3k views

### What instrument does a surveyor use to accurately find North?

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 ...
2k views

### How to generate a synthetic infrared and red LED signal for SPO2 calculation

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 ...
85 views

### What procedure do steel plants use to recycle water vapor?

As you may know Steel plants and Tile Factories use a lot of water. I want to know how do these factories recycle water vapor which is mixed with flue gases to reuse it? Do they take advantage of Heat ...
164 views

### Thermal transfer function of an isotropic material

Consider a piece of material of infinite extent (i.e. no boundaries) with a point source of heat at its center which oscillates at frequency $\omega$ about the mean temperature $\langle T\rangle$. If ...
129 views

### What are the best materials to use for producing drinking water from the Air?

There are several companies producing equipment that produce drinking water from the air. They use dessicants, hygroscopic brine, or deliquescent salts, to adsorb water from atmospheric humidity. ...
4k views

### What's the difference between annealing, curing and sintering?

All these processes sound like structural change caused by heating.
1k views

### Biaxial flexure of steel I-beams

If an I-shaped section is loaded in two directions (in both weak and strong axes), how can I find the maximum load-carrying capacity of them beam? There is an interaction equation in AISC 360-10, ...
3k views

### Would engineering bricks explode if used to build an oven?

I'm building a pizza oven and, to do so, I bought a whole load of engineering bricks (not these but similar). They've got five holes vertically through them, each hole is 2x6x6.5 cm (80 ml) and the ...
140 views

### Is the order of operations in jacking a cable relevant?

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? For a symmetric curve, the tension diagram along the cable's ...
201 views

### Water pressure divider

Let's suppose I have a water jet as source, and this jet goes through a tube and is equally divided into 4 tubes. Is there a way to control the flow/pressure at each of those tubes separately by ...
353 views

### How to compare utilization rates?

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 ...
807 views

### FEM modal analysis computing displacements

I have an FEM model that I am doing a modal analysis of. I wanted to check that how I am computing the physical displacement is the correct way, as I've read a lot of about normalizing modes, ...
744 views

### How to describe the rotation of opposite ends of a body due to an applied moment

Summary A short way to phrase this question is: Shear describes the translation of one part of a body relative to another given an applied force. What is the equivalent rotational term? That is, ...
4k views

### How is lift related to airspeed?

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 ...
395 views

### What would be a practical way for removing thousands of padlocks from valuable bridge railings?

Inspired by this story about Paris authorities ordering removal of thousands of "love lock" padlocks from bridge railings. This is not a DIY SE question because it's not DIY scale in the first place. ...
3k views

### Why prefer any other pipes over plastic pipes for drainage and culverts?

Plastic pipes look superior - no corrosion, lightweight, easy to install, a bit flexible. Yet there're lots of cases when culverts and drainage pipes are made of steel (corrosive) and reinforced ...
122 views

### What is the “10/100/1000 BASE-T” laser/transceiver rate unit signifying?

I'm using a 10/100/1000 BASE-T fiber transceiver. What does this mean?
3k views

### What grade of Neodymium magnets are commonly used in hard drives?

I want to buy some magnets, but the ones that I have found on online shops are mostly grade N38. They are pretty cheap, but they need to be as strong as the ones found in a hard drives. I am afraid ...
541 views

### How is a self-locking hex nut (ISO 7040) used?

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?
263 views

### Is vortex tube reversible?

If you inject cold and hot air in outlets of a vortex tube, do you obtain a greater pressure at inlet?
1k views

### What is the name of this mechanism for raising and lowering the impression cylinder of a printing press?

It is like a cam that has an off-center hole, and it rotates in its fixture with a knob to lock it in place. The purpose is that you can loosen the knob and rotate the piece to slightly raise and ...
468 views

### Can all electromagnetic spectra be focused like a laser?

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 ...
513 views

### Why are lasers used for concentrated light applications instead of incoherent light sources?

Some laser applications consist simply of concentrating light into a small spot. Two example applications are laser welding and cutting. In these cases a CO2 laser is often used which needs a ...
I understand that the model for a first order system is $$G(s)=\frac{k_m*e^{-\tau s}}{T_ms+1}$$ In this case $\tau=3$ and the system gain $k_m=10$, correct? I need to calculate the transfer ...