Questions tagged [measurements]
Measurements, instrumentation, calibration and metrology.
199
questions
0
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2answers
31 views
Error propagation in reciprocal of a measurement
I have a measure of a quantity, x, and I know the standard deviation of the measure, STDx.
I want to compute the inverse of x, which is y= 1/x, but then what would happen to the standard deviation?
...
0
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0answers
21 views
Is there an instrument that can measure thickness of an object through strain?
So basically, I am doing a project to design a measurement tool for measuring the different layers of the quartz crucible used in the semiconductor industry. Since the crucibles undergo some ...
0
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2answers
31 views
Describe the magnitude of a force using real-life comparisons instead of numbers
I already asked this on physics.se, I got a suggestion to ask here, but the question became too old to migrate before I decided to do it. I did also receive an answer, and I am grateful for it but
...
1
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3answers
48 views
How to measure water output over time - any better solutions than tipping bucket gauge?
I'm trying to figure out how to get an automated measurement of a trickle of water over time. (Application is measuring the water output by a dehumidifier; overall output would be a few pints of water ...
1
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2answers
59 views
How are perfectly square blocks made from scratch?
So I'm looking into how stuff is made from scratch, starting with a surface plate which has been lapped flat using the three plate method. But almost everything I read on the subject on "the ...
0
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1answer
49 views
Are there any 'clever' mathematical techniques for testing a micrometer?
I've just inherited a vintage British 25 mm micrometer, and it's precious to me.
You can test a spirit level by reversing it, and similarly you can for an engineer's square. We can test a right angle ...
0
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0answers
26 views
Vibration measurement of rotating blade
In a vibration measurement of a rotating blade, I have the following information. The vibration signal is measured using an ICP accelerometer which has the following specification
Measurement range: ...
0
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1answer
21 views
Can you suggest a 0 to 10 Volts mesuring unit with an easy .NET (C#) API? [closed]
I am looking for a voltage input module that measures a voltage input in the range of 0 to 10 Volts (slowly changing during a 5 seconds period). It should be connected to a local Windows computer that ...
0
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1answer
26 views
Component for measuring push force
I would like to measure the force with which the bolt (dark blue) pushes on the break pad (grey) to stop the wheel (light blue). I am thinking that I could put some component between the bolt and the ...
1
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1answer
44 views
Fender Telecaster outer body measurements
I appreciate this may not be the best forum to pose this question but...
I've been attempting to model a copy of a Fender Telecaster electric guitar in SketchUp. I've been mainly working from a PDF ...
0
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0answers
26 views
How does the number of cycles for averaging in a lock-in amplifier relate to low-pass filtering and where do I set it?
Please forgive me if I ask too many questions at once or I am too much of a rookie. I want to understand the working-principle of lock-in amplifiers (LIAs).
I understood the calculation that yields ...
0
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1answer
42 views
Can I use loadcell for vibrating force measurement?
Is it possible to use a load cell to measure a force that is vibrating? The idea is to measure that force that is getting into the load cell in a sweep of frequencies and vibration is NOT a noise. ...
3
votes
3answers
221 views
Mechanism for controlling the clamping force
I am working on upgrading a research project on wind energy. They are trying to measure the performance of wind blade designs in a small wind tunnel (i.e. their models are relatively small).
What they ...
0
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1answer
32 views
Orientation of wire in linear position wire sensors
Talking about a wire potentiometer, I was wondering about the way it could be used after installation. as you know, wire sensors have a roll of wire inside them that come out of a hole, and it sounds ...
17
votes
7answers
4k views
How can I measure correctly with a ruler?
When measuring with a ruler divided into mm lines, should I include the lines by themselves or only in between them?
I illustrated the problem. (I took an example of measuring of 10 mm with two long ...
2
votes
2answers
45 views
Why are 0-10V signals de-facto standard in HVAC applications, when 4-20mA is more common in other applications?
I've been involved in a few projects with HVAC systems, where sensors etc. generally used 0-10 V signals, and looking at catalogues of Buderus and other suppliers this still appears to be the standard....
0
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1answer
69 views
How do engineers work with extremely small objects?
Please excuse me if my question is not well-worded. My background is pure mathematics and I am not familiar with engineering, but sometimes I feel fascinated by the things engineers have achieved.
...
1
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2answers
42 views
Accurate method or instrument to measure density of shaving cream foam or whipped cream foam?
I am currently filling a "standard" stainless steel cup of known volume with foam and then I weigh it. Then I calculate density. This method is pretty messy and I have to be careful about how I fill ...
0
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0answers
20 views
Estimating trunk rotation using frontal and sagittal views
I am doing an experiment regarding elbow flexion's effect on peak sprinting velocity and we want to measure trunk rotation and shoulder rotation during our trials. We don't have an overhead camera so ...
1
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2answers
56 views
Measuring a pattern size on a flat surface
I want to manually measure the dimension of a pattern printed on a flat surface, with an accuracy of about 0.1mm. For simplicity sake, let's say this is a black rectangle, printed on a white ...
0
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0answers
23 views
How to measure and create PVT diagram
We have all seen PVT diagrams. From my understanding one should measure pressure, volume and temperature on or near the outside of the system.
Volume: maybe by displacing water initially and then ...
0
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0answers
25 views
How to design a method to estimate vx=speed in direction of swimming
We have a body that goes underwater (let's say a whale) with magnetometer and accelerometer data. I also have GPS, date, depth, pressure and temperature data.
I want to know if there is any simple way ...
1
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1answer
61 views
How to measure the power output of a stirling engine
I'm doing a project for thermodynamics where I have to measure the power (work over time) of a Stirling engine for varying temperature differences. I don't necessarily need an exact answer (as in: ... ...
-1
votes
1answer
40 views
What are the simplest available methods for monitoring pressure and airflow in a 22mm diameter pipe?
In the emergency case that more than one person must share a mechanical ventilator, the medical professionals lose per-patient monitoring of pressure and airflow.
To that end, what are the simplest ...
1
vote
1answer
68 views
How to reduce oscillations (rapid changes of control signal) when controlling a real system, which occur due to noise in measurement from sensors?
I have a real mechanical system (ball & beam) which I want to control. The system is approximated by the second order transfer function:
$$ T(s) = \frac{b_0}{s^2+a_1s+a_2} $$
and in state-space ...
0
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0answers
33 views
What is dead beat reading?
I was reading about characteristic of a comparator.
It states
Comparator indicator device should be such that the readings are obtained in least possible time and for this magnification system should ...
-1
votes
1answer
34 views
Expression of uncertainty measurement
I have a problem with the expression of a measurement result.
I have a resistance decade box used as variable resistor in order to balance a Wheatstone Bridge. Let's call this resistance decade box $...
0
votes
1answer
16 views
Measuring EM radiation power over surface area
I didn't make it obvious enough below that I was interested mostly in infrared, as the current use case is measuring power radiated from warm objects and from the ground. As pointed out in comment by @...
1
vote
1answer
64 views
BJT Output Characteristics Question
Ok, so I am pretty confused at the moment with a question that I have been given to work out by my lecturer and was wondering if I could get some guidance with it. I will attach images of the question ...
1
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0answers
15 views
how do you calculate viscocity from torque arm load cell measurements?
I have a piece of company developed equipment that uses a pot mounted on a rotating base plate with a 0.15m torque arm and load cell, a mixing paddle is used to stir the mixture while the controller ...
2
votes
0answers
51 views
How can I calculate the smallest voltage a given adc can read?
I have a project where I'd need to measure small voltage (0.05 mV) output of a wheatstone bridge with an arduino mini pro.
Based on my previous question most probably it can't be done with its ...
0
votes
1answer
42 views
what is the range of the measurable relative elasticity with a commonly used strain gauge
I'm looking for a data that what is the typical application range for a common uni directional strain gauge like used in weight scales?
I've read about around 200 ppm in a research gate article, can ...
1
vote
1answer
50 views
what does 0.1% FS +/- 0.02 mean?
Let's assume a DMM is specified to have accuracy "0.1% FS +/-0.02" when used on the 50 V range.
I get that 0.1% FS means the true value will lie somewhere between measured value - 0.05 and measured ...
0
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1answer
163 views
Weight percentage and grams per liter
I was reading some documents that said
25 wt. %, 500 mlL-1
as well as
20 gL-1
I think 25 wt. %, 500 mlL-1 is referencing 25% weight of 500 ml of water so that would be 125 ml of water
20 g*L-1 would ...
2
votes
1answer
27 views
Calculate FTIR-system response functions from measurements of a calibrated black body
I need to find the response of my FTIR spectrometer. I do have a calibrated black-body source (area-emitter) which I measured at various temperatures.
The system operates in inverse cm, cm-1. My ...
0
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0answers
31 views
Why is there no widely-used standardized unit for indentation hardness?
The last hundred years have seen a great degree of standardization of units, and the expression of units of measurement in standardized, instrument-agnostic, objective terms, often in the SI units.
...
2
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4answers
97 views
Sylvac UL 4 - USB - (Send data) reports 'no.data'?
Using the sylvac UL 4
Each time I invoke the (send data) function the sylvac LED panel reports 'no.data'. To mention the obvious but nothing is received at the connected USB device.
My question ...
0
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1answer
85 views
Why does Bourdon tube measure relative pressure?
From Wikipedia:
Bourdon tubes measure gauge pressure, relative to ambient atmospheric pressure, as opposed to absolute pressure;
But looking at pictures such as the one above, it seems there is ...
-1
votes
1answer
36 views
Way to digitally measure volume of air inhaled by lungs?
I was interested in this as a fun project. To be able to get the volume of air inhaled by a person has some cool applications I can think of.
I was thinking of a modified anemometer of sorts fitted ...
0
votes
1answer
74 views
off-scale torque measured - what is my torque arm?
I have assembled a benchtop torque measurement stand for evaluating electric motor and controller efficiency.
The motor is 49kV , 5kW brushless outrunner.
Input power reading is taken from motor ...
3
votes
1answer
38 views
What's the most practical way to measure angular velocity for small rotations?
I'm looking to measure the angular velocity of an arm as it moves. It seems to be a difficult thing to research, since the term 'angular velocity/frequency' is usually reserved for other areas of ...
1
vote
2answers
45 views
Measuring viscosity with tools other than viscometer
I would like to measure viscosity, but do not have access to a viscometer. If possible, I would like to avoid having to purchase one. I have access to many other flow measuring devices, including ...
2
votes
3answers
99 views
Cutting a larger circle on center of a smaller circle
At work, we cut a 6" hole in the wall for a duct. Later we decided we now want a 10 inch duct in the same place. what tricks are there to center the larger hole over the center of the smaller hole if ...
1
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1answer
29 views
Bolt circle indication on angled ellipse
Ok so I am a machinist, not an engineer, but figured someone here might be able to provide some insight into my situation.
The part is 2.75" diameter and is on a 3.3* angle in the X axis on my mill. ...
1
vote
1answer
42 views
Whats a reliable way to measure the amount of rope going out of a coil?
I am an undergraduate researcher and I am working at enhancing a calibrating system for a hydrographic surveying system that my supervisor uses on his hydrography course. The rope is used to lower a ...
1
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0answers
110 views
Which imperial units of measurement use vulgar (simple) fraction numbers?
All values of metric units are expressed in decimal or scientific notation. Some imperial units, use fraction numbers as primary notation (3/4" for 0.75 inch).
As far as i know, only inch and foot ...
0
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1answer
23 views
Measuring wire damage using strain gauges
We need to determine the physical damage in some area of overhead lines that can't be inspected visually. The damage's in general caused by short circuit and air pollution (mostly sulphur compound).
...
1
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0answers
45 views
How much does loading a load cell in other directions than the direction it was designed for effect the readings?
I am looking into using this TAL230B miniature type load cell to measure forces in x and y direction. The normal sensor loading is displayed in image 1. What is the effect of loading them as in image ...
1
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0answers
33 views
Strange offset on oscilloscope channel
I've a Rigol DS2072A. It works great except for an offset problem that I noticed the past few days.
Channel 2 always shows a DC offset. This is independent of any settings such as channel coupling, ...
1
vote
5answers
1k views
Plumbing Imperial units confusion - 3/4" is supposed to be around 19mm, right?
I'm really confused. I've only ever used metric in my life. Recently I'm trying to build a IOT device and there is plumbing and water involved.
I was looking for a 19mm fitting, but on Amazon and ...
