Comment summary #53
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Comment 521 ... 530
| date | article | author | comment |
| 19 okt 2013 22:34:47 | Theory and Definitions | George Daglish | Dear Freddy, I am a retired Doctor of Applied Mathematics with a strong interest in Seismology. In view of recent disasters and together with some colleagues, I am interested in working to automate the process of Location of Earthquake Epi/Hypocentres from the receipt of seismograms to the release of possible Tsunami warnings. This response must be as rapid as possible. In this regard at least 300,000 lines of code have been designed, written and tested in prototype form. I have attended two World Congresses for Engineering [London] in 2010 and 2011 and the 33rd General Assembly of the European Seismological Commission in Moscow [2012] and am likely to attend the 34th in Istamboul in 2014 to present some more of this work. One of the many features that would appear to me to lend itself to purely hardware implementation is the pin-pointing of the initial onsets of the different forms of seismic energy [P-waves; S-waves; Love waves and Rayleigh waves, etc.] within the incoming seismogram at the point of receipt. There are several methods for this, of which I have programmed 3. One, in particular involves two parallel FFT's and two parallel resultant PSD's [Power Spectral Density] evaluations and their subsequent comparison by ratio. As stated, this would ideally act on an incoming seismogram in near real-time. Would you be prepared to consider a design? With Best Regards, George Daglish [BA PhD CMath FIMA] |
| 25 sep 2013 09:54:22 | Magnetic permeability | Zoltán Fuszenecker | The total permeability is exactly what I wanted to measure. So I am OK now. |
| 24 sep 2013 17:41:35 | Magnetic permeability | Freddy | The discribed methode measures the permeability of the total magnetic circuit. An airgap and other foreign materials has its own permeability. So if you introduce an interuption in the material to measure you create a series circuit with sections of different properties. When the material to measure has a μr of let say 2000, than the tiniest airgap with a μr=1 has already a big influence. See equ. 9 in meettechniek.info/compendium/magnetic-circuits.html how the magnetic resistance of a circuit is calculated. |
| 24 sep 2013 15:04:41 | Magnetic permeability | Zoltán Fuszenecker | Ah, okay, I have air gap and also non-magnetic (mu_rel=1) metal elements inside my solenoid. With core I meant the things inside the solenoid. Why is it a problem if I had air gap? Why does it distort my results? Thanks! |
| 20 sep 2013 14:26:44 | Magnetic permeability | Freddy | Cores like E-cores have an inner leg that has a twice as large cross sectional area as the two outer legs. This is because the flux of the inner leg will split before and each part follow both outer legs. Therefore the flux in the innerleg is twice as high as in the outer legs. The flux desity is at all places the same. Use therefore the larges cross sectional area in the calculations. If a core has an airgap it's impossible to measure the permeability with the discribed method. |
| 20 sep 2013 10:27:52 | Magnetic permeability | Zoltán Fuszenecker | Dear Writer! I used this guide to measure the magnetic permeability of a core. My problem is, that the core consists of more materials with variated cross sections. There is also an air gap. My question is, how I get the Ac and the lc of my magnetic circuit? I think lc is not really a problem, but regarding Ac, I have no clue. Thank you! |
| 19 jun 2013 01:28:06 | Fast Lux meter | Freddy | Direct sun light has a light intensity between 32 kLx and 130 kLx. The BPW21 isn't specified for this amount of light. You need another photodiode. |
| 18 jun 2013 06:49:49 | Fast Lux meter | Stella | How this suits when exposed sun ? |
| 03 apr 2013 01:02:18 | Accuracy, precision & resolution | Freddy | Making a PDF involves extra work. For instance two different resolutions for the images. You can also print websites if you want. And I hope that this article doesn't contain too much math. |
| 30 maa 2013 11:21:29 | Accuracy, precision & resolution | Jay Trivedi | Very good information. I request to keep maths minimum and where ever possible give example to understand it better. How about making a downloadable PDF file option. Thanks. |