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  1. K

    I Help Understanding Luminance Calculation Process

    Hello all, I have a system that consists of: A projector with a known position, orientation, and brightness (luminous flux, I guess - units are lumens), A lens with known distortion characteristics (i.e. a known light ray vector for every point on the projector's image-generating panel) A...
  2. K

    Friction Measurement of Rotating Equipment

    Hello, I have two questions that I have been pondering for some time without arriving at an acceptable explanation. The questions require a little bit of background information: I work on rotating machinery that operate across a range of (relatively slow) speeds, and generally has a...
  3. K

    Harvesting Load Cell from Food Scale

    Hello, I've been toying with the idea of making a cheap dynomometer for small electric motors, but one of the obstacles I'm encountering is finding a cheap load cell. The best I've done so far is a $75 sensor from Omega, which still requires conditioning. Then it occurred to me that you can...
  4. K

    Can this be solved?

    Hello, I have an equation which I am trying to solve for t. Of course the problem I'm having is due to the combination of ts within the argument of the sin term and also outside of it. I think I could also manage without the constant D (using sin(x)/x=sinc(x)), but that's no help here (as...
  5. K

    Brushless AC Motor Windings

    Hello, I've recently read a couple of things about brushless motors that have spurred quite a few questions. Googling has solved some of them, but I'm hoping that you can help with the rest :smile: Apparently there are two types of permanent magnet brushless motors - DC and AC. This is...
  6. K

    Work done by rolling inverted pendulum system

    Hello, I am trying to derive the equations of motion for a system that is essentially an inverted pendulum on a wheel. The pendulum is connected to the wheel by a motor. I have a motor torque M and a disturbance torque D. The radius of the wheel is r. My generalized coordinates are the...
  7. K

    Pressure Drop Across Radiator And Air Flow

    Hello all, I have some performance data on a particular radiator, and I want to model the system and see if I can't get a simple analytical model to match the data. The problem I'm having is with the air flow rate through the radiator. The only relevant data made available to me is the...
  8. K

    Linkage analysis using intersection of three sphere

    Hello. I am creating an algorithm for finding the locations of nodes connected by rigid links. Some nodes in the system are constrained in place, and to one node (a *special* node), a displacement is applied. The algorithm should be able to determine the locations of the other nodes by...
  9. K

    Stack Overflow with Quicksort

    Hello. I've been reading up on sorting algorithms, and decided to try writing a quicksort algorithm. After a bit of debugging, I got it working, but when I increase the size of my data set, I get a stack overflow. To sort an array with 100 elements, I sometimes get a stack overflow, but with...
  10. K

    Electrical Power to Mechanical Power

    Hello! We (myself and the other folks at my company) have a couple of questions about the proper way to compare electrical energy to mechanical energy. Our application involves holding a load at zero speed, as well as moving it back and forth at varying speeds. Most of the time, our motor...
  11. K

    How to compute 'special' sum

    Hello! I am trying to find a way to compute the following in an Excel spreadsheet without the use of a macro: \frac{1}{n^{2}}+\frac{1}{\left(n-1\right)^{2}}+\frac{1}{\left(n-2\right)^{2}}+...+1 Can I manipulate this into some form that would make it easier to put in Excel? I'm pretty stuck...
  12. K

    Mechanical Advantage through series of links

    Hello, I'm trying to come up with a method for calculating the mechanical advantage of a vehicle's suspension (i.e. how much does the spring compress if I move the wheel center by some infinitesimally small amount?). I have a method that I thought was correct, but I recently compared my...
  13. K

    Field Weakening of a DC Motor

    Hello, I have a question regarding calculating the torque output of a DC motor. I can record current and field from a motor drive. I can also record commanded torque. I have time histories for a series of motor commands, and I'm comparing the torque command to a torque that I calculate...
  14. K

    Equations of Motion for Inverted Pendulum

    I'm working on a simple simulation for an inverted pendulum mounted on a cart. I derived the equations of motion using Lagrangian dynamics, but I want to go back and add viscous damping terms to the linear motion of the cart, as well as the angular motion of the pendulum. I also want to add a...
  15. K

    Amperage ratings on DC power supplies

    Hello, I'm hoping that by asking this question I can save myself a couple of bucks. I have a DC power supply for a router that is rated for 1.0 A. My router stopped working, and I traced the problem to the power supply. It's a 12 V supply putting out 0.1 V. I have other 12 V supplies, but...
  16. K

    Centrifuge Motion Equations

    Hello. A few of us at my company have been trying to solve this problem for a few weeks now, without success, and so now I turn to the brilliant minds of the people who frequent this forum for help :-) We operate a centrifuge that spins between 1.4 G and 9 G. The command that we send to our...
  17. K

    Valid Inertia Tensor

    Hello, Recently I was using multibody dynamics software at work and when I ran the simulation it warned me that the values that I specified for the inertia tensor of one of the bodies was physically impossible. It turned out that I had mistyped one of the values and it was an easy fix, but...
  18. K

    Numerical Integration and Energy Loss

    Hello. I've recently been using a few different numerical integration methods to solve a number of different problems, and as I looked into the integration algorithms, I realized that I don't understand them as well as I thought I did. I created a simple Excel workbook that calculates the...
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