Science desk
< July 21	<< Jun \| July \| Aug >>	July 23 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

July 22[edit]

Utility line detection[edit]

Have any technologies been researched for allowing backhoes, excavators and other dirt-digging machines to detect and identify utility lines in real time? An example I could think of would be a code of ridges and grooves engraved on the outside of a pipe (which could be a gas or water main, or a shield for power and telecom lines), a set of haptic sensors that would detect the bar code while scraping it, and a chip which would detect using error-correcting codes that it wasn't just reading the random texture of a rock. Neon Merlin 05:11, 23 July 2022 (UTC)[reply]

Often a plastic tape is buried above the cable. So hopefully the operator can see it. Perhaps there could be a detector for magnetic fields from cables. Graeme Bartlett (talk) 10:04, 23 July 2022 (UTC)[reply]

See several patents. Excavators for non-archeological digs typically do not carefully scrape away the surface carefully, layer by layer; they take big bites and may rip up a cable in the process. So proximity detection would seem required, well before physical contact is made. RFID is one possibility, for which there are also some patents. The cost of retrofitting a legacy system of underground pipes is prohibitive, though, and without standardization of the codes this does not offer promise for future systems either. --Lambiam 10:31, 23 July 2022 (UTC)[reply]

Recently buried utility lines are usually marked on maps, so diggers know what to expect. A coloured plastic warning strip is often buried slightly above sensitive lines. The problem are the old lines, and some are over a century old. They're not clearly marked and retrofitting markers in the ground would require digging up the entire line, with more risk than what can be avoided by adding the markers, on top of the disruption from breaking up the street. Electric power cables can be detected by their weak 50–60 Hz magnetic field, metal pipes can be detected by metal detectors, but a 50-year-old PVC water mains will be hard to detect. With a bit of luck, people are smart enough to put the dangerous lines (gas mains) deeper than the other lines, so the're less likely to get damaged when working on the other lines. PiusImpavidus (talk) 09:03, 26 July 2022 (UTC)[reply]

Swallow-tail Kite Flight "Rolling" Behavior[edit]

Hi WRD, Background... Near Indiantown, FL. Approx. 10 mi ESE inland from Lake Okeechobee. I'm very sorry I don't have video to share. I saw 4 or 5 Swallow-Tail Kites gliding. One tucked its head into its breast, then folded its wings close to its body. Rolled backwards and, as it came around, spread its wings and kept gliding. What are good references to describe and explain this behavior? And more broadly, what are the best books, articles, etc. I should read if I'm interested in these Kites? 2600:1702:2EA0:7AE0:6D09:ADF2:EA09:572A (talk) 03:39, 22 July 2022 (UTC)[reply]

Courtesy link: Swallow-tailed kite.

From here: "The kite’s aerial acrobatics while on the hunt are something to see. It continually flicks and rotates its tail, switching from a straight course to a tight turn in an instant as it scans for prey. Sometimes it rolls and dives backward to catch an insect behind it. Adults swallow their food while flying, rarely perching during the day."

{The poster formerly known as 87.81.230.195} 90.201.73.20 (talk) 08:36, 22 July 2022 (UTC)[reply]