Author: dmd

Hægt er að nota örbylgjur til að skynja hljóðbylgjur sem endurvarpast á vegg.
Það er talað um þetta í grein í new scientist

It is easy to defeat ordinary audio eavesdropping, just by sound-proofing a room. And simply drawing the curtains can defeat newer systems, which shine a laser beam onto a glass window and decode any modulation of the reflected beam caused by sound vibrations in the room.

So the new “through-the-wall audio surveillance system” uses a powerful beam of very high frequency radio waves instead of light. Radio can penetrate walls – if they didn’t, portable radios wouldn’t work inside a house.

The system uses a horn antenna to radiate a beam of microwave energy –between 30 and 100 gigahertz – through a building wall. If people are speaking inside the room, any flimsy surface, such as clothing, will be vibrating. This modulates the radio beam reflected from the surface.

Although the radio reflection that passes back through the wall is extremely faint, the kind of electronic extraction and signal cleaning tricks used by NASA to decode signals in space can be used to extract speech.

Sá þessa frétt á slashdot:

In a story at the new Open Source Energy Network site, Paul Noel says: “Energetically speaking, the vortex that forms in these storms is also a natural particle accelerator, and a massive capacitor bank. As the harmonic circuit develops, it resonates acoustically and functions as a capacitor, extracting the heat from the storm and transmitting it away. Without this electrical circuit, the storm would fail almost instantly due to the accumulation of heat from condensation of water.” He also asserts that understanding these phenomena better could help us harness the power of nature, seen and unseen.”

Þetta er dæmi um módel í veðurfræði sem er hliðstætt við módel í rafmagnsfræði.

Það má segja að það sé hitabylgja í Reykjavík þessa stundina. Í gær var 13 stiga hiti úti og heit gola, en fyrir tveimur dögum var 3 stiga frost. Hitamælirinn hérna inni hjá mér sýndi í nótt 25.5 stiga hita, sem er met held ég.

Var að rifja upp um daginn það að ég hélt alltaf að það væru menn sem væru undir gangstéttunum sem stýrðu umferðarljósunum og ljósastaurunum.

Núna rétt í þessu var fluga að fljúga upp í peruna í lampanum mínum og datt svo dauð niður í kaffið mitt.
Ég held að ég vaski kaffibollann upp á eftir.

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