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  • Infrastructure: steam heating?

    Sometimes, infrastructure might have interesting history. Radiators might be a case.

    The following is by my understanding.

    When I was a kid, we had radiators in houses and buildings. It was eastern Canada, so the weather was cold in the winter.

    The places I recall radiators from most clearly were in classrooms. The radiators were often about three to four feet tall, and resided under the windows. They were painted white or off-white. One soon took them for granted, yet one might be intrigued to see one today.

    I didn’t realize at the time that it’s possible those radiators held steam. Moreover, one did hear of a boiler room at the school.

    Somewhat interestingly, around eighty percent of large buildings in New York City use steam heating as of 2022.

    What pointed me in this direction was a this intriguing video on YouTube, from SdS construction (Mar 19, 2023), showing a homeowner’s steam heating setup using restored radiators.

    Source:

    Zhadanovsky, I. (Jun 21, 2022). “Steam Heating Conundrum of High-Rise Buildings.” https://www.intechopen.com/chapters/84666

    -js

  • Materials: polystyrene foam, part0

    Some materials that seem disposable might be worth holding on to.

    The following is by my understanding.

    The other day I was handling some polystyrene foam that arrived in a package. Like one would expect, it had been fitted around the package’s contents to protect them from damage. Said product had been unpacked, and the polystyrene remained.

    I noticed, as I handled it, how strong it was relative to its mass. I decided to look it up.

    It turns out that one-pound polystyrene foam has a shear strength of around 20PSI. It’s a pound per cubic foot.

    By way of comparison, Douglas fir has sheer strength of around 900PSI. However, it’s around 29 pounds per cubic foot.

    So, Douglas fir has greater shear strength by weight, perhaps by a factor of around 1.5. However, for temporary set-ups, such as forms to hold wood parts in place for fastening, polystyrene could be used effectively.

    Source:

    Foam Factory. (Oct 12, 2014). Polystyrene Foam (EPS) Physical Data Sheet. https://canada.foambymail.com/polystyrene-foam-sheet.html

    Hiziroglu, S. (Jul 2016). “Strength Properties of Wood for Practical Applications.” https://extension.okstate.edu/fact-sheets/strength-properties-of-wood-for-practical-applications

    -js

  • Energy: how 27000mAh might “become” 100Wh

    Researching specs of charging banks, one might at first be confused by capacity comparisons.

    The following is by my understanding.

    I was reading about charging banks that might be used to charge a laptop. There seems a common limit of the capacity of those: airlines don’t allow more than 100Wh of energy storage without special permission.

    Some places were saying 100Wh, while others, 27000mAh. In one place, it even said those are the same. Yet, from the point of view of physics, they can’t be, because a W (W) is not the same unit as a milliAmp (mA). Specifically, W measures power, while mA measures current. I knew more research was required.

    It turns out it’s because many power banks use lithium-ion cells, which produce energy, internally, at around 3.7V.

    So, since 1000mA=1A, and W=V*A, 27000mAh*3.7V=99.9Wh≈100Wh in the context of many power banks.

    Source:

    service.anker.com

    benzo energy (Aug 20, 2019). “What type of cells is used for power bank?” https://www.benzoenergy.com/blog/post/type-of-cells-used-for-power-bank.html

    “Guidelines for Batteries.” (Jun 10, 20206) Canadian Air Transport Security Authority. https://www.catsa-acsta.gc.ca/en/what-can-bring/guidelines-batteries

    -js

  • Hardware: charging Milwaukee RedLithium cell: flashing red/green

    Apparently I’m not the only one who’s tried to charge a Milwaukee RedLithium cell and had the charger flash red/green. Here’s what happened.

    The following is by my understanding.

    My wife got me a drill/impact wrench set from Milwaukee tools maybe a year ago. It revolutionized my handyman chores.

    I recall having to charge the cells before using the drill and the impact drill. When I slid one cell into the charger, the indicator went solid red, which means it’s charging. You want that.

    Then, when charging is finished, the indicator light on the charger turns solid green: you want that, too.

    Such happened with the first cell. However, with the second, the indicator light flashed red/green when I slid it in. You don’t want that; the manual seems to suggest that it means either the contact isn’t good, or there’s a hardware problem either with the cell, the charger, or both.

    Since the set was brand new, I didn’t want to think it was already defective. I played around a bit, slightly changing its geometry in the charger. After a couple of minutes of this, the indicator turned solid red: charging. I wanted that.

    Holding the cell in place in the charger, and my breath, I continued to watch the indicator light, wondering if it would start to flash. It did once, but by readjusting the position of the cell I was able to bring it back to solid red. Eventually, I could let go, and the indicator remained solid red. A few minutes later, I checked back: solid green. I wanted that:)

    Charging time doesn’t seem very long, anyway. I didn’t time it, but it seems maybe it took half an hour(?) from near-dead to full charge. That’s a very loose guess.

    Best of luck:)

    -js

  • JavaScript: defer

    Getting JavaScript to load when a webpage loads can be a consideration.

    The following is by my understanding.

    Lately I’ve been doing a lot of hands-on, physical tasks, as my posts have reflected. However, yesterday I had to incorporate some JavaScript into a web page. I’d done so many times in the past, but wondered if I’d done so the best way, if there’s a better way now, etc. I decided to look it up.

    I discovered that a way to load JavaScript after the web page loads seems to be to put defer in the script tag where the JavaScript source is given: something like this:

    <script src=”script.js” defer></script>

    It seemed to work great.

    Source:

    developer.mozilla.org

    -js

  • Autos: how much torque to turn healthy engine?

    The idea of how much torque is required for tasks in mechanics can be fascinating.

    The following is by my understanding.

    In my previous post I mention the idea of drive size, torque, etc. Ideas of aligning drive size with socket size, as well as torque requirements of certain tasks, naturally arise thence.

    The idea of turning over a car engine, by hand, is one I’ve been hearing about lately. One wonders what torque that might require.

    It turns out, apparently, that it might only take around 20 ft*lbs of torque to crank over a healthy engine by hand. Such can be done, at least in some cases, using a 1/2″ drive torque wrench.

    Source:

    YouTube: MotorCarNut: “How To Tell If Your Engine Is Seized”

    -js

  • Autos, hardware: drive size for sockets

    Most people might be familiar with a basic socket set. Yet, drive size might be less obvious.

    The following is by my understanding.

    I recall buying a socket one time to remove the anode of a hot water heater. It was, I think, one-and-one-sixteenth. I bought it from a discount bin, and it came on a straight bar. I was in a hurry, so didn’t think much of it.

    Later, I had to buy a 15/16″ socket to undo an oil filter casing. The clerk asked me what drive I was using. I didn’t know. The socket was 1/2″ drive. He assumed, correctly, that I would need an adapter from 3/8″ drive to 1/2″.

    Back then, I just had a standard socket set from Mastercraft. It had both 1/4″ and 3/8″ drives, and its largest socket was 3/4″. It hadn’t occurred to me that bigger drives – for instance, 1/2″, were called for sometimes. However, when I got home from buying the 15/16″ socket, I inspected the one-and-one-sixteenth socket, on its bar, that I’d bought years ago to remove the water heater anode. Indeed, that socket, too, was 1/2″ drive.

    When I thought about it, the reasoning was obvious why 1/2″ drive might be called for: a bigger fastener might well mean it’s under more strain, so needs to be tighter. In turn, a larger-diameter drive would be stronger, so less likely to break when removing such a fastener.

    It turns out that, for 3/8″ drive, the torque range tops out around 75 ft*lbs, then for 1/2″, around 250 ft*lbs.

    It’s hard to imagine me, personally, applying more than 250 ft*lbs of torque, but apparently that’s when 3/4″ drive becomes relevant.

    Source:

    eTork. (Sept 4, 2024). “Torque Wrench Sizes Explained.” https://etork.com/torque-wrench-sizes/

    -js

  • Web: nofollow links

    We hear about links being how some search engines decide the order of sites they present. What are “nofollow” links?

    The following is by my understanding.

    (Herein, the opposite of a nofollow link is referred to as an ordinary link.)

    Most people likely have heard it’s links to a site that determine where that site is presented in search. That’s probably an oversimplification, but substantially correct. For precision, some will argue that not all links are worth the same: links from an “authoritative” website (whatever that means) count for more than ones from a less regarded one. Moreover, “nofollow” links are meant not to count – meaning they don’t improve the site’s search position that they point to. Only ordinary links are meant to help a site in search. While the exact calculation, based on authority as well as ordinary vs nofollow, might be opague, most people seem to agree that if a lot of “famous” websites have links to a certain other one, then that certain other one will likely be near the top in relevant searches.

    A nofollow link is one that contains the parameter rel=”nofollow”. In theory, it tells a search engine that said link, while it leads to a given site, shouldn’t improve that site’s position in search. In a link-based system for deciding where a site ends up in search, the concept of a nofollow link might seem bizarre. Yet, there are reasons for it. Said reasons, to me, are somewhat questionable and ironic, so I’ll just say this: rel=”nofollow” is meant to be put on paid links and also on ones to “lower-quality” sites. Now, why someone would want to link to a site they think is lower-quality might seem an obvious question, and it’s left to the reader.

    One reason for the nofollow attribute is that some bulletin boards get spammed with comments filled with links completely unrelated to the topic being discussed. I’d suggest just not publishing those comments, rather than publishing them but changing the links to nofollow.

    The issue of one site being authoritative compared to another has always raised questions to me. Sometimes, the best advice is from an obscure individual; I’ve seen that happen.

    Anyway, the actual effect of nofollow seems dubious: nofollow links still appear to help the websites they point to. How much less that is compared to ordinary links is perhaps hard to fathom.

    Interesting, eh?

    Source:

    mailchip.com: “The Role of Nofollow Links in SEO”

    Kiran R. (May 11, 2016). “Nofollow Links: History, Benefits, and Rankings.” https://www.techwyse.com/blog/search-engine-optimization/nofollow-links-history-benefits-and-rankings#

    -js

  • Computer constructs: loops

    Loops probably aren’t new to most readers here. Yet, they are used in some less obvious scenarios.

    The following is by my understanding.

    Probably a lot of us have written a program that finds a number to a certain exponent. Therein, one might use a loop to continue multiplying the starting value by itself until it’s done so the exponent number of times. Then, the loop exits and the program tells the result.

    For me, learning programming, the loop idea like above was straightforward enough. It became obvious why some operations needed to be repeated until a certain condition was reached. I came to really like loops and what they could do.

    When I learned that input devices, such as a PC or smartphone, or even a calculator, typically use a loop to discover if the user has entered something, I was surprised. It seems a background loop is always running: during said cycle, the device checks every potential input, such as the keys and the ports, for activity. Detecting activity, it responds. Else, it “waits” by just continuing the loop.

    I wondered about the reason for the looping design, but it seems it’s because it simplifies the question of which key or port is being triggered that instant. The device discovers the key press, for instance, when it checks if that key is pressed as part of its routine loop. Finding it is pressed, it knows which key has been activated because of the position in the loop when the impulse was discovered.

    With the speed of computers, it’s easy to tell which key was pressed first, etc. Let’s imagine a “low” scan rate of 125Hz. That means 125 times per second the computer checks each key to see if it’s pressed.

    Interesting, eh?

    Source:

    akkogear.eu (Dec 26, 2025). “Keyboard Scan Rate Explained: What You Need to Know.”

    Eweadn.com (Apr 16, 2026). “What Are Polling Rate, Scan Rate, and Latency? Keyboard Performance Specs Explained.”

    -js

  • Household technology: adhesives, part0

    Which glue to use in a given context?

    The following is by my understanding.

    I usually buy glue at the dollar store: three I commonly buy are super glue (Krazy Glue and stuck being two kinds), Fix-All, and Rapid Grip. Each has worked very well in situations where the other two seemingly couldn’t have.

    Last night, I needed to salvage a board that seemed two pieces, but was actually milled as one. Yet, an end of it was compromised from water damage. (It had been in place for around 30 years.)

    I needed to cut off the rotten part, then glue on a replacement piece. I still needed, afterwards, to work with the finished piece: darkness was approaching in about three hours, and the reconstructed board needed to be installed by then.

    My go-to, with wood outside, is Fix-All. However, as I learned last night, it doesn’t necessarily bond strongly in an hour; it likely takes more like 12 to 24 hours. Rapid Grip seemed to turn out similarly: the repair came undone after letting the glue dry for an hour, but then working with the board.

    Having tried those two glues, I had less than an hour left to try the repair again; it needed to work this time.

    I know super glue works fast; the problem is that the kind I have is runny, so doesn’t work well with grainy surfaces, since it just penetrates the material so it’s not available on the surface. I sanded down the wood parts that needed to be glued together, hoping then they would be smooth enough to keep the super glue on the surface.

    I applied the super glue to both sanded sides, then pressed together and left the repair under some weight for about five minutes. I was very happy to discover it held. Moreover, the repair continued to hold as the board was re-installed.

    This was a case where, of the glues I had on hand, only super glue could work, because of its rapidity of bonding.

    -js