A least squares fit gives L = 92 μH and RL = 2.8 Ω.
Yes I know, there are no error bars. I am lazy.
Saturday 09 July 2011
Inductor
I bought an inductor today at Pusterla and decided to measure its inductance. It brought back memories of the second year physics lab course. Having access to an oscilloscope again is awesome.
R = 988Ω and C = 102.5 nF as measured by a multimeter.
A least squares fit gives L = 92 μH and RL = 2.8 Ω.
Yes I know, there are no error bars. I am lazy.
A least squares fit gives L = 92 μH and RL = 2.8 Ω.
Yes I know, there are no error bars. I am lazy.
Tuesday 03 May 2011
Saturday 23 April 2011
Quick test of snappy compression
The snapshots from cosmological simulations can get quite large. It's easy to accumulate several terabytes with a 10243 simulation. It would be useful to compress the output if the running time is not significantly affected. This might be a good job for snappy compression.
In this case, snappy was 17 times faster than gzip but the result was 3.3 times larger. The snappy compression rate is 490 MB/s which is almost twice as large as the value claimed on their site (but of course this strongly depends on the hardware).
As a quick test, I compressed a single shard from a small simulation:
| Size | Time | |
| original | 98 MB | |
| snappy | 32MB | 0.2s |
| gzip | 9.6MB | 3.3s |
| bzip2 | 5.6MB | 28s |
In this case, snappy was 17 times faster than gzip but the result was 3.3 times larger. The snappy compression rate is 490 MB/s which is almost twice as large as the value claimed on their site (but of course this strongly depends on the hardware).
Saturday 01 January 2011
Saturday 04 December 2010
A New Corrective Scheme for SPH
Timothy Stranex and Spencer Wheaton, A New Corrective Scheme for SPH, Computer Methods in Applied Mechanics and Engineering 200 (2011) 392-402.
"A new corrective scheme for Smoothed Particle Hydrodynamics (SPH) is introduced which greatly improves its accuracy, particularly in regions of particle deficiency or when particles are irregularly distributed. The scheme is based on the Taylor expansion of the SPH kernel estimates. The corrective equations are derived up to the second derivative in an arbitrary number of dimensions. Test applications for the new scheme include the interpolation of functions and the numerical solution of the heat equation in one and two dimensions."
Friday 16 July 2010
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