Calculate torque required to rotate and hold a platform

I wish to rotate a rectangular platform about its length. It is attached to a shaft that runs through the length of the platform at width/2. How can I compute the torque of the motor required to rotate and hold this platform. The platform has uniformly distributed weight on it. I want to rotate it upto 45 degrees only. I am not entirely sure if I should go fo a high torque DC motor or a stepper motor.

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How to calculate server capacity?

I am trying to answer a question:

Do we need more worker machines to handle current load?

We have a variable number of jobs coming in and each job takes different time. Here is a snapshot of our system for a period 12 hours.

Jobs in 8 hours

But the number of jobs in system changes based on day and time.

How can I calculate throughput of our system and build monitoring around max load that our system can handle?

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Are there formulae to calculate capacitance and inductance of an antenna?

How to calculate internal impedance of a dipole antenna? Its resistance has two components ie wire resistance and radiation resistance, both these can be calculated using formula. Are there formula to calculate capacitance and inductance of an antenna? Or they are calculated empirically only?

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How to calculate exact angle to the moon?

I am building some device as a gift for my girlfriend.

For this device to work, I need to be able to calculate the angle to which I should look towards (3D angle), in order to see the moon.

This angle is affected by (and maybe not only):

  • The time of year.

  • The hour.

  • The location on earth from which I look.

I’m sure there’s some formula that approximates the angle.

I don’t need an exact value, I can live with +-1 degree.

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How to calculate water vapor budget for a selected region in GRADS or MAT Lab

I need to calculate water vapor budget for a selected region. Can anyone suggest a specific link or code for the above mentioned tools please. I have seen a link for NCL but i am not familiar with that tool.

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How do you calculate the number of days between two tasks in Microsoft Project?

I’ve created an event planning project that explains all of the relevant tasks before, during, and after a given event in MS Project 2003. I would like to calculate the number of days between a given task and a task I’ve created called “Host Event”. The best way I’ve been able to do it thus far is create a custom number column with a formula of:

Int([Project Finish]-8-[Start])

It essentially does the trick, as the “Host Event” task is 8 days away from the Project Finish date. However, this seems like bad coding because I hard-coded the 8 days and if I were to ever change any task durations after the “Host Event” task, it would completely throw off the formula.

Is there a better way that I can perform the following calculation?

Int([Project Finish]- ["Host Event" Start])

Link to Microsoft Project File

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RankOverflow: A website to calculate your Stack Overflow reputation rank in all leagues


website screenshot


Rank Overflow is a website to calculate your Stack Overflow reputation rank in all leagues easy and with one click.
I created this page because I wanted to know my percentage of my year league when the “top n%” badge is displaying the quarter. Also, if your reputation change is to low for this badge to display (e.g. top 10%, but you are top 12%), you can still find it out.
We use the Stack Exchange Authentication to get a the profile IDs on the sites you happen to have an account on.

You need at least 200 reputation on the site you want to check for this to work.

This is a limitation by SE, not by us, as the leagues site shows only data for 200+ rep users.

How it works

The website backend gets the rendered HTML from the Stack Exchange Leagues site for the community site you selected, and that for each period (week, month, quarter, year and all time) twice (first time to get your rank and the last page number, second time for the rank of the lowest ranked user). The required values get extracted and are shown as results.
The required data comes from the authentication and the leagues website.

If anyone has concerns about scraping to much/too often, this only happens, if the user presses the Calculate ranks button, never automatically.


This website is released under the MIT License.

How do I get to it?


Or clone the repository from GitHub


Rank Overflow works in the following browsers (and basically on each browser that supports the fetch() API):

  • Chrome 42+
  • Firefox 39+
  • Opera 29+
  • Mac OS Safari 10.1+
  • Edge 14+
  • Android Browser 56+
  • Chrome for Android 61+
  • Firefox for Android 56+
  • Opera Mobile 47+
  • Samsung Internet 4+
  • QQ Browser 1.2+
  • Baidu Browser 7.12+
  • Safari & Chrome for iOS 10.3+

The following browsers are NOT supported:

  • Internet Explorer & IE Mobile (all versions)
  • Edge 12 & 13
  • Opera Mini (all versions)
  • Blackberry Browser (all versions)
  • UC Browser for Android (all versions)


This website was created by me and I am the only key contributor at the moment.
Please submit an issue on GitHub if you run into errors.
For feedback, feel free to leave a comment under this question.


The page was built using Flask/Python and Bootstrap 4.
The static files are served over Apache, API and stuff like that is provided via WSGI

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Calculate accuracy order/rate

I was doing error analysis of numerical scheme and I get $L_1$ error for each grid size with $N$ element. I was searching reference to compute accuracy order/rate from that error data but doesn’t find any good reference. Anyone know?


$L_1$ error:
$L_1=1/N sum_{i=1}^{N} e_i$

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Procedural terrain: What’s the best approach to calculate noise in the GPU?

A few years ago I started creating a procedural planet engine/renderer for a game in Unity, which after a couple of years I had to stop developing due to lack of time. At the time i didn’t know too much about shaders so I did everything on the CPU. Now that I have plenty of time and am more aware of what shaders can do I’d like to resume development with the GPU in mind.

For the terrain mesh I’m using a cubed-sphere and chunked LODs. Since terrain never changes, heights for each chunk need to be calculated just once.The way I calculate heights is rather complex since it’s based on a noise tree, which is created from an artist/designer-provided XML for each main planet/asteroid. Leaf nodes in the tree would be noise generators like Simplex, Value, Sine, Voronoi, etc. while branch nodes would be filters and modifiers (FBM, abs, neg, sum, ridged, billow, blender, selectors, etc).

To calculate the heights for a mesh you’d call void CalcHeights( Vector3[] meshVertices, out float[] heights ) on the noise’s root node, somewhere in the game code.

This approach offers a lot of flexibility but also introduces a lot of load in the CPU. The first obvious thing to do would be (I guess) to move all generators to the GPU via compute shaders, then do the same for the rest of the filters. But, depending on the complexity of the noise tree, a single call to CalcHeights could potentially cause dozens of calls back and forth between the CPU and GPU, which I’m not sure it’s a good thing.

How should I go about this?

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How to calculate unsystematic risk?

We know that there are 2 types of risk which are systematic and unsystematic risk. Systematic risk can be estimate through the calculation of β in CAPM formula. But how can we estimate the unsystematic risk quantitatively? is there any formula or calculation that can be related to the measurement of unsystematic risk?

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