Archive for February, 2007

Going up?

Posted in Uncategorized on February 28th, 2007

I’ve been meaning to post this list somewhere for quite some time now.

Ever noticed what brand your local elevators are? I have, but then again, that’s because I’m a geek. I should really make up an identification guide for linking some characteristic hardware features to certain brands on those installations where the original branding is stripped…

Here is the great master list, in order of subjective, or is it objective, quality, by brand:

Otis - these like to last FOREVER - banks of the original ‘Autotronic’ series are still serving happily to this day in a couple of Miami locations! The newer Otis stuff is damned good too… even hydraulic, which is usually the cheap and nasty product line for other brands.
Old-school Montgomery - Unusual nowadays, but still going strong. Of particular note, these have all relay controls, and are immune to even the most severe power surges!

Dover - These often go unlabelled. If you get in an elevator and the buttons are white squares with rounded off corners, and the floor indicator’s a fake LED dot matrix arrangement (it’s really a set of square light/transparent mask assemblies), you’ve got a Dover. The build quality’s good on their stuff, and installation quality tends to be a cut above the rest for some reason.

Thyssen-Krupp: Same as Dover. They bought Dover.. why not? The only reason I’m putting them a cut below is that a few cost-cutting measures seem to have made themselves visible.

Now we start to get to the ones I’m a little iffy about …

Kone / Montgomery Kone: The hardware’s starting to get a bit flimsy as we go down the list here. Traction elevators in this line seem to be prone to freaking out and getting stuck more than usual. Interior panels don’t fit right. I think the best feature Kone’s got going for them is their optical door edge sensor, which can reliably tell if a very small object (like someone’s finger) is in the way. I’ve seen the Kone sensors installed on older Otis stuff a lot. Installation quality, at least in the Miami area, is usually terrible!

A rotten old wood packing crate hanging from a moldy frayed sisal rope over a squeaky pulley dangling down the open center of a staircase - This is vastly preferable to what comes next… trust me.

Schindler - Total, unadulterated crap. Schindler elevators can be expected to break down quite regularly, in very interesting ways.  Even on brand new installations, Schindler elevators will make scraping and grinding noises, randomly fail to level at floors and sit there with the doors closed for long periods of time, or even slap into the springs at the bottom of the shaft at full speed for no particular reason. When I used to go to MDC Kendall campus, one building’s classrooms were only accessible via a pair of Schindler hydraulics, and I got very used to prying the doors open after the elevator slammed into the bottom after failing to level. Newer Schindler door hardware features a frighteningly oversized hatch restrictor mechanism which makes rescue of trapped passengers extremely difficult if access can’t be gained to the top of the cab… and the failure of a single weak plastic part causes the door to jam as soon as it closes, requiring the same rescue procedure. I declare these completely unacceptable.

Yep. There’s the list.

Fight 802.11 Pollution!

Posted in Uncategorized on February 14th, 2007

If you’re in a public area right now with some sort of portable wireless device, take a quick look at the list of open wireless networks. Notice those ad-hoc (peer to peer) networks all over the place?

Connect to any of those, and you’ll find nothing other than someone else’s laptop. Perhaps some services will appear via Bonjour, Rendevous, or SMB announce thanks to ‘zero-configuration’ networking, but that’s all you’re going to find. Most likely, you will find one titled “Free Public WiFi”.
What is all this rubbish, and why is it there? The answer is pretty simple, really. The Windows operating system (which I do not use, for good reasons) remembers which wireless networks you were connected to permanently. This is probably a good thing, when you are connecting to ‘infrastructure’ networks with access points; it saves you from having to manually having to reselect the network each time you move from home to school, etc.

This behavior is at the very least stupid, and at the worst, disastrous, when applied to ad-hoc networks.

On an infrastructure network, the network is announced to and detected by the clients by the periodic transmission of a beacon frame. This beacon frame transmits some basic data, such as the network name. (If you’re curious as to exactly what’s in the beacon frame, there’s a nice article on that.)

On an ad-hoc network, every client transmits a beacon frame. Windows remembers to ‘connect’ to an unused ad-hoc network by beaconing… which essentially spams the airwaves with announcements of a network that goes nowhere.

This is, at the best, an inconvenient waste of power and source of interference to existing networks, and at the worst, a gaping security flaw.

Let me elaborate on the security concerns of this for a moment:

Remember the MS Blaster worm? The Blaster worm exploited a bug in the Windows networking stack to inject and execute its code, and to spread. An infected system with one of these wireless networks left on would immediately spread it to any other system that connected to it, probably because it too had been left on there.

Fortunately, the solution to this problem seems to be simple. Don’t connect to these junk networks, like ‘Free Public WiFi’, ‘hpsetup’, etc. Any business or home installation that offers free wireless Internet access will, almost without exception, have an access point. If you do connect to one of these, be sure to disconnect from it before moving to another location.

Mac users don’t have to worry about this; OS X won’t beacon an ad-hoc network unless you’ve chosen the “Create Network…” option. It’ll only connect to one it already sees beaconing.

You too can do your part to fight wireless LAN pollution! By making sure you’re not beaconing rubbish networks, you too can protect the world from the forces of evil!



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