Doppler Effect Animation

Adventures of Ibn Battuta: India

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Adventures of Ibn Battuta: Anatolia and Crimea

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Effect of Perfectly Matched Layers (PML) in FDTD Simulations

Although it is pretty straightforward for researchers in the field of modeling via FDTD or FEM, PML can puzzle those who do not have any modeling background. Therefore, here we try to simply show what happens with and without a PML in a free space propagation modeling.

Basically, we demonstrate the effects of the perfectly matched layers in finite-difference time-domain (FDTD) simulations. Here, a point source transmits a spherical wave and the simulation domain is truncated in two different ways. In the first case (left one) no PML region is utilized whereas in the second one (right) PML region is included. It is clearly observed that PML absorbs the incoming waves mimicking a infinite domain simulation whereas the simulation without PML, spurious reflections occur due to termination of the computational boundary.

A Tentative Map for Ibn Battuta's Travel in Black Africa and Andalusia

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This post is in draft version. It will hopefully be expanded later.


References:
1 - The Adventures of Ibn Battuta, Ross E. Dunn, University of California Press, Revised Edition, 2005, pp.277
2 - Ibn Battuta and his Saharan Travels

King's Mountain Hike (Oregon)

This was yet another hike with our hiking club during weekday after the job. Trail can be very steep at some points. But the view at the summit deserves that struggle. Definitely lovely view from the top. Descending is way more difficult than ascending. So caution should be practiced.  

Manually installing a Miktex package

If working behind a company firewall preventing you to download and install the Miktex packages automatically, here is a solution to achieve that.

http://tex.stackexchange.com/questions/2063/how-can-i-manually-install-a-package-on-miktex-windows

Including source code in Latex without using "verbatim"

It is a nice feature to have the exact (or close) code formats in the latex documents. The following “listings” package achieves that. Here is a link that illustrates this in a clear and concise manner.

http://texblog.wordpress.com/2008/04/02/include-source-code-in-latex-with-listings/

International Reply Coupon: Self Stamped International Shipment

Within US, we can use self-stamped envelopes when we want to pay for the incoming letters. However, I needed to do the same for an international letter. Since I was not able to get the stamps of another country, I had to find a different solution. I discovered the so-called “International Reply Coupon” by which you allow postage free shipment to the international senders.  I just sent several copies to Korea, Brazil and UK. I will share the experience when I can hopefully get the letters back.

Here is the USPS link where you can buy this coupon:
International Reply Coupon

Evanescent and Propagating Waves

Time domain simulation of a plane wave for different wavenumbers (k). At first the wavenumber is positive real number and keeps reducing down to 0. This constitutes the propagating region where the spatial wavelength (lambda) increases as the wavenumber (k) decreases. Then, wavenumber becomes negative imaginary and increases in magnitude. This region demonstrates the non-propagating or decaying properties of evanescent waves. In the evanescent region, the greater the magnitude of the wavenumber, the faster the wave decays.