Ear plugs

I recently purchased a new AGV helmet. I’m either a sucker for propaganda, or acutely aware of the diminishing performance a helmet gives with the passing of time. Back in my younger days, where riding the motorbike was a daily occurrence, I tended to replace my helmets every couple of years to avoid the problem of compressing the lining. These days, I am more of a “weekend warrior” and hence only feel the need to replace the helmet after about five years.

I don’t think I will ever be the sort of person who purchases a helmet on-line. I need to know that it will fit well and that things like the chin strap can be easily tucked away. Things you can only really tell by examining and wearing the helmet. The consequences of picking the wrong one on-line deter me from doing so!

Even though I prefer the “real life” selection process, the one question that always remains unanswered is: “Will this helmet be quiet?” I suspect I shouldn’t bother asking as the honest answer will always be “no”. It occurred to me as I was riding to the bike shop (to purchase “the new lid”) that when I first purchased my previous helmet, I found it disappointingly loud. However, on the trip I was taking to replace it, I didn’t think it was too bad. One could hope that as the helmet lining had compressed, it somehow improved its acoustic dampening, but I rather suspect years of ear abuse wearing the previous helmet has simply taken its toll on my hearing.

To over-simplify sound, its loudness is measured in decibels. db(A) This scale is logarithmic – as an example: an eighty decibel noise is ten times as loud as a seventy decibel noise. According to the dangerous decibels web-site once a sound reaches 85dB(A), permanent hearing damage can occur. The key thing then becomes how long you are exposed to the loud noise. For every 3dB(A) over 85, safe exposure times halve. (As a point of reference, eight hours is their suggested limit for 85dB(A) noise exposure.) Marcus, from headphones.com.au provide more generous figures, suggesting longer listening times are safe. He does work for a company that sell loud things you put on your ears, but I guess it is in his best interest to keep you hearing for as long as possible…

The Institute of Sound and Vibration Research, have recognised that noise levels whilst riding a motorcycle can be very high. Their research was carried out both in a wind tunnel and on the road. The provided measurements were hardly exhaustive, but they noted that different helmets and different motorcycles all affected the noise levels achieved. This included the revelation that particular helmets could be good or bad, depending on what model bike was being ridden. (This gives me hope, as my previous helmet started its active duty whilst I was riding my previous motorcycle!) :-)

A provided graph showed that if you discount illegal road use (i.e. over 110kph or around 70mph) the quietest scenario was in riding a BMW K1100LT with the adjustable screen up. Even it came in at around 88db(A) meaning it shouldn’t be ridden for more than around four hours. The simplest practical answer to reducing the volume of noise you are subjected to is by wearing ear-plugs.

If you have never considered wearing ear plugs before, I recommend you get several pairs of differing styles. There are different density foams as well as “putty” like materials that mould and shape in your ears. For my liking, I can’t go past simple foam plugs that are available in chemists. Even cheap foam ear plugs reduce the volume by around the 26 to 33 db(A) mark, It may take you some getting used to the feeling of foreign objects in your ears, but the long term benefits far outweigh this initial “unnatural” feel.

Some riders prefer to listen to music via an MP3 player fitted with ear-bud speakers. But, these in turn have to produce volume louder than the wind-noise generated by the helmet. Ear-bud speakers may look trendy in the Apple advertisements, but quite simply they are capable of loud volumes and therefore are dangerous to your long term hearing ability.

If you do want to listen to music on the motorbike, I’d suggest you look at spending some serious money and get a quality set of “canal-phones” that block outside noise allowing you to use lower volumes. Just remember that there are reports that ear-buds (and presumably “canal” style headphones) can be capable of producing in excess of 110db(A).

For my money, the 70 cents or so I spend on a set of ear plugs are the simplest way I can improve the quality of my ride whilst doing something good for my long term health and quality of life.

Digital Cameras: the new floppy disks.

The humble digital camera has replaced the even more humble floppy disk.  As a roving nerd, there’s seldom a holiday or a trip away where I’m not carrying a laptop computer.  As a result, eventually I’ll be asked to burn photos a friend or family member has taken onto a CD for them.  On more than one occasion, plugging in the camera has revealed a virus infection on the memory card. 

In this respect, the camera (or more correctly the memory card) is a perfect carrier – much like the floppy disk was throughout the early 90s.  The virus lies dormant, unable to fulfill whatever purpose its maker had intended for it.  I have seen criticisms that virus scanners are ineffective placebos and not to be trusted as a safe way of dealing with this threat. 

“The blacklist approach used by anti-virus vendors simply doesn’t scale to today’s threat environment. Blacklists are never particularly effective. But it’s getting to the point where the illusion of protection afforded by a traditional anti-virus solution is worse than no protection at all” 

The knockers have a fair point.  It’s true enough that “black-listing” means the vendors of such anti-virus software will always have to play “catch-up”.  It may also be true that this provides a greater feeling of security for the user than is scientifically justifiable. 

I’m going to pursue a line of logic that may well be flawed, but (for the most part) is fairly straight forward and can be thought of as “most likely”

  • I am using an up to date anti-virus product that has been labelled “ineffective”, but have found infections on people’s cameras.
  • The camera will most likely have become infected when they were connected to their home PC.
  • These people are unaware that they have a virus on their camera.
  • If they’re unaware that the virus is on the camera, they’ll most likely be unaware that their PC has a virus.

From this, I can only conclude that these people are most likely not to have an up to date virus scanner on their PC.  A lot of hardware vendors supply a one year subscription for some anti-virus software. – “Buy a computer, get 12 months free virus protection”.  I am not aware of the business model used by anti-virus vendors, but it seems likely that the software image provided on a new computer was purchased at a heavily subsidised (if not free) rate by the hardware supplier. 

To the anti-virus software vendors this must be equivalent to low-cost advertising:  It promotes their brand-name and due to the subscription nature of the software ensures a fairly good return on investment.  Figures on software piracy tend to be dubious.  However, personal experience tells me that there seems to be a trend in some home users that means they expect something for nothing.   They paid for the computer, they shouldn’t have to pay for the software.  As someone who earns their living by writing commercial software, it is not an attitude I can condone.  But alas, I digress. 

At the end of their “free anti-virus” subscription period, uninformed users are faced with seemingly two choices:

  1. Pay up.  They get to keep up to date, by parting with their hard earned money.
  2. Put up.  They’ve got anti-virus software that’s current at the time.  Surely that will be good enough?  Surely these pesky virus things aren’t created every day?

Here in-lies the problem.  The user feels safe as they have some anti-virus software, but their computer becomes an ever greater risk, as time goes by.  And time moves quickly in computing!

Of course there are other options to running out-of-date virus scannersFor home users there are free solutions.  Are they as good as ones that you pay for?  Various tests have been conducted and I would encourage you to read some for yourself.  One thing you are unlikely to see are comparisons between up-to date free virus scanners and out of date commercial scanners.  But, it seems a fairly logical step to assume that sooner or later an up-to date scanner is going to have a more comprehensive black-list than an out of date scanner does.  This means for the average home-user the free alternatives are a better option than an out of date scanner.  So, next time you spot a digital camera with a virus, pass the message on!

Biking 101: Accelerating

One of the amazing performance aspects of a sports motorbike is its ability to accelerate.  Standard 1/4 mile times and 0-100kph / 62mph times are staggering and leave all but the most exotic supercars lying in their wake.  Getting these sorts of figures is a test of courage as much as clutch / throttle control, but the potential is there if you possess the right qualities. 

Unlike turning corners, accelerating doesn’t require any seemingly counter-intuitive input from the rider.  Having said that, there are some interesting points to make about acceleration*.   Under hard acceleration, the rear suspension of a motorbike becomes less compliantNewtonian physics states that an object at rest is inclined to stay at rest until a force acts upon it.  This is quite observable in everyday life – you can feel a weight transference when a vehicle begins to move.  This is because initially, this weight is at rest and until the energy is transferred to it, it will continue to remain at rest.  On any vehicle with sufficiently compliant suspension, this will cause the vehicle to “squat” at the rear when accelerating.   However, after an initial compression of the rear suspension, the motorbike appears to “stiffen up”.  Even though there is more suspension travel to be had, it becomes harder for it to use.  Here’s my explanation of this:

A chain driven motorcycle has a small amount of slack in the chain.  This slack is necessary, as the distance between the two sprockets changes as the swingarm moves up and down.  – This is because the front (drive) sprocket is not located at the pivot point for the swing-arm.  At rest, gravity ensures that this slack is present on both sides of the chain.

Image showing the slack in a chain

When accelerating, the chain is pulled through by the drive sprocket.  Due to the tendency of the rear wheel to remain at rest, this pulls the top part of the chain taut. 

Tensioning of chain 

The harder you accelerate, the greater the difference in inertia of the two sprockets.  As a result, the distance between the top of the sprockets is minimised.  This is achieved with the aid of the weight transference and the suspension squats.  Once this shortest distance has been achieved, further suspension travel requires the distance between the tops of the sprockets to be extended again.  It’s not that this can’t occur, it is just an additional force that needs to be overcome.  Any let-up in this force will see the suspension return to the state where the tops of sprockets are minimally spaced.  As such, under hard acceleration, the rear suspension becomes distinctly non-compliant.

The second point to make about hard acceleration is the tendency for the bike to “wheelie”(or “wheel-stand” if you prefer to sound like a boffin).  In its simplest explanation, this is just a characteristic of a large weight transference to the rear of the bike.  Normally, the speed of the sprockets at their outer radius is the same.  If you can increase the speed of the front sprocket such that it exceeds the rear, then the front sprocket will “climb the chain”.  This can be demonstrated with two pens and a rubber band:

  1. Place the rubber band around the two pens to represent the chain and sprockets of the bike.  Keep the rubber band under enough tension, to ensure it grips the pens.
  2. Hold one pen in your right hand on the surface of a desk.
  3. Twist the pen in your left hand anti-clockwise (or counter-clockwise if you live in the US!)
  4. If you’re holding the right hand pen still, the left hand pen will “climb” in a clockwise direction around the right-hand pen.

This characteristic also holds true in shaft drive motorcycles, but the right-angle gearing makes it more difficult to demonstrate with mere office stationery.

Modern sports-bikes and drag bikes run longer swingarms than older bikes.  This helps prevent the bike from wheel-standing, for the same reason that a fat kid needs to sit closer to the middle of a see-saw to balance a light kid on the other end.  That is, the amount of torque required to lift the front of the motorbike becomes greater, the longer the swing-arm.  If you don’t have offspring of wildly differing weights (or a see-saw) you can try my second desktop experiment.  For this one, you will need a ruler and a smallish weight.
1. Place the ruler on the desk, such that one end extends 5cm (2 inches) past the edge of the desk.
2. Place your weight on the opposite end of the ruler.
3. Now push down gently, on the end of the ruler that sits over the edge of the desk.
4. Move the weight closer to the edge of the desk, and repeat step 3.

You will note that as the weight gets closer to the pivot point, it becomes easier to lift. (By now, I expect most of you are going “well duh!”).  It’s this same idea that makes the longer swingarm a less wheelie-prone bike.  Like every element of design, there is a compromise that must be reached – as swingarm length increases, suspension performance is reduced as is the turning ability of the bike.  But that’s a story for another day.
* Like my previous entry on cornering, what I state here is based on my observations and my understanding of physics.  Please feel free to leave a comment if you think my statements are not correct.

The problem with the Internet (Part 1)

One bad segue deserves anotherWelcome to my first post on the new site. What will happen to rolypolycat? It will still exist, but become the typical “family photo album” type web-site found everywhere on the Internet under obscure URLs. You don’t have to be terribly astute to note that all the old blog postings I made on the site, I’ve transferred over to nerdrider. But (and this is a terrible segue) what if I hadn’t? What if I’d simply abandoned the old web-site to gather virtual dust? The information I’d presented there, would be locked in time. – Both web-sites are hosted on a paid server. The domain names are paid for. So if I simply didn’t renew my account with the vendor, you could imagine that eventually, the hard-drive space would be reclaimed, the DNS entries removed and a small chapter (more like a “generic sentence summarising many aspiring bloggers”) of Internet history would come to a close. But sometimes it appears to be cheaper for a vendor to buy more hard drive space, than reclaim old disk space.

I value my time very highly. I don’t object to anyone who realises its real price. Time is one of those things you can’t buy and only have a limited supply of. IT staff only have a limited time to deal with every issue that comes their way. If they haven’t had the time to set up proper practices, they won’t be using their time effectively. If a hard drive fills, then you have the two choices of “empty it” or “replace it with a bigger one”. Economically, if you spend too long working out what can be removed from a drive, it would be cheaper to replace it. In a world where the global consciousness is finally realising that resources are limited, it’s almost criminal to suggest replacing working hardware is the right choice. But, in the real world, it happens. A classic example: Eighteen months ago, I changed ISP. As is fairly standard, both old and new ISPs offered “free web-space” for a personal web-site. On my old ISP’s website, I had a PHP page with phpInfo() and another page with pictures of strobe ants (that I thought may have been fire-ants). No – I’m not the sort of nerd that studies insects, rather I was concerned that we had fire-ants but the DPI web-site didn’t have the facility to upload photos for them. So, free web-space seemed like an easy solution. Some eighteen months later, my first foray into web-sites still exists.

The computer industry travels at an amazing pace. The technology used today wasn’t here ten years ago. Maybe some research boffin was developing the ideas / software / hardware, but for the most part, it simply didn’t exist. “Best practices” come and go as standards evolve. In our society, we increasingly turn to the Internet as a source of knowledge. We expect that we may have to be wary about the truthfulness of things stated, but we don’t often wonder if its factual basis is still matching any advancements in the field we are studying. Compare this with the Internet’s predecessor AKA a library… Take a book off the shelf, and you always get a feel for how old the information is. Dog-eared pages, faded text, a battered cover, all help convey a sense of age. If you take an engineering guideline off the shelf and see it was published in 1930, you may expect that what you read will be outdated. The cues of age can be far more subtle on a web-page. Without an actual date being displayed on a page, subtelties in fashion and trend (fonts / colours / images etc) will most likely be your only guide. Match that with the pace that the computer industry moves at, and you can see a problem utilising materials found on the Internet as the latest and greatest thinking in the computing field.

I guess my points are:

  • If you are a consumer of Internet material, always look for supporting evidence to indicate what you are reading is correct and up to date. It is relatively cheap to put together a web page. And, you don’t need credentials or a reputable publisher behind you. Without prior writing experience or credentials, try getting a book published in dead-tree form!
    If you are a provider of Internet material, always date your work. It’s current now, but it doesn’t mean it will be by the time someone reads it…

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Are you wearing a helmet?

If you live in a “western country” outside of the United States, you are probably required by law to wear a motorcycle helmet when riding a motorcycle. Australia is no exception to this rule. In Australia, this helmet must comply with Australian Standards AS 1698.

Let me state upfront: I have not read AS 1698. I am not a lazy person, but from my “Internet research” it appears reading standards is not a right of all, unless they wield a credit card… Besides, it wasn’t actually AS 1698 that interested me for the sake of this post.

From my understanding of AS 1698 and various reading I have done over time on the standards, it’s one of the better standards motorcycle helmets are tested against. It includes an element of destructive testing which (from memory) includes “batch testing”. In other words, it isn’t a “pass once and you are free to sell all you want” standard.

The standard covers all sorts of aspects – some fairly obvious, some less so. Things like:

  • How much energy the helmet is capable of absorbing. (In other words, making sure your head isn’t subjected to a 300G impact.)
  • Making sure a three kilogram spike does not penetrate the shell.
  • Testing that the strap adequately holds the helmet to your head.
  • Ensuring that the helmet permits a suitable range of peripheral vision.

In the eyes of the law, if your helmet does not have the official AS 1698 sticker, you are not wearing a helmet! So, if you feel the really cool graphics of your helmet clash with the sticker: “suck it up, buddy!”. But as I said earlier, AS 1698 is not what this post is all about.

I want to blog about AS 1609. This is the standard that covers motorcycle helmet visors (and other things like visors for race car drivers). Like AS 1698, if your visor does not feature the standard’s sticker, you are considered to not be wearing a helmet. This standard too, has its intentions on protecting the wearer. As such it features things such as protection against corrosive materials, stability of the material at adverse temperature ranges, strength of the material and optical clarity.

Put simply, it is the last point that I take issue with. It’s not like I ride around with my eyes shut – so optical clarity is important to me too. But currently, there are no tinted visor sold in Australia that pass this standard. But what aspect of the standard do they violate? If it’s the optical clarity – then I can live with that. I always carry a clear visor with me (complete with AS 1609 sticker!) Modern helmets make light work of changing visors, so the inconvenience of travelling with a bum-bag is something I can live with. I am not so sure I want to ride with a visor that may shatter if it is struck by a small stone. The standard is too encompassing. It is my opinion that it would be better for visors to pass two standards – one dealing with strength and another to do with optical clarity. It would be more informative to the wearer than this leaflet that came with a tinted visor I recently purchased:

Blanket disclaimer of unsuitability

So, when riding in sunny conditions, what are your choices? The way I see it, you have three:

  1. Wear sunglasses and use a clear visor. I used to do this a lot and don’t recommend it. Helmets don’t accommodate glasses particularly well. If you need to wear prescription glasses, make sure you test the helmet fit and comfort when wearing them, prior to purchase. The other reason I don’t recommend wearing sunglasses is that if they are not a well-fitting pair of wrap-around glasses, there is the chance for sunlight to get in behind the lenses. When this occurs, all you tend to see is your eyeball staring back at you! This is mildly disconcerting at the best of times and inappropriately distracting whilst travelling on a motorcycle.
  2. Squint. What would those optometrists know anyway? This raises another point. Sunglasses sold in Australia pass yet another Australian Standard: AS 1067. Maybe tinted visors should be subject to this standard conformance too?
  3. Break the law. Ride with a tinted visor… you rebel, you!

Technically, even though I carry a clear visor with me I am breaking the law by wearing a helmet fitted with a tinted visor. At times I have been booked or pulled over for random breath testing / licence checks whilst wearing a helmet fitted with a non-approved visor and I have yet to come across an officer who has even commented on it. Put simply, police officers are people too and are quite capable of applying common sense. If you are riding in conditions where “optical clarity” is unlikely to be an issue, I suspect it would take a fair degree of provocation on your part to provoke the officer into handing over a ticket for not wearing an approved helmet… But don’t count on it!

If you are riding at night or in dimly lit conditions, you can probably expect less favourable behaviour from a police officer, even if you are riding with the visor up, as Jeff Anderson found out:

…I was recently pulled over for wearing my tinted visor at night. The visor was up and not in use as it reduces vision. the officer said that it was illegal even though it wasn’t in use…

Jeff was writing on a forum which featured a section where you could ask an “an active serving motorcycle police officer. Interestingly enough in the response “Hubie” (the aforementioned police officer) mentions a rumour of an upcoming photochromic lens style visor, which is expected to pass the Australian standards testing. I can’t imagine that one will be cheap!
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How good is the black-box in your program?

I am a “big fan” of the television series “Air Crash Investigators“. I’m not what I consider “morbid” – the concept of making a TV series from actual plane crashes is slightly disturbing. It’s the methodical investigation that appeals to me. The thoroughness with which the investigations are conducted ensures that the airline industry is always striving to improve its safety record. That gives me comfort everytime I set foot on a plane. – However, I don’t recommend you watch one of the shows immediately before boarding an aircraft!

As you are no doubt aware, key to most aircraft crash investigations is the Black box. It contains vital details of the aircraft and along with the cockpit voice recordings help investigators unravel what happened during the final moments of the doomed flight.

Fortunately, the average software developer does not have to write software with the added pressure of it costing human life if it all goes pear-shaped. Of course, there are exceptions to this. Due to the lower cost of failure, most computer applications won’t be stringently controlled to protect against program failures. When a program fails, resources need to be devoted to resolve the problem for the customer. This costs your company money. “Resolving the problem” for the customer, is different to “fixing the bug that caused the error”. This may involve manipulating registry entries, files on disk or other methods. All’s fair in love and war… The more customers you need to fix this problem for, the more compelling finding the underlying problem becomes.

This is where decent error recording code comes into play. General exception handlers tend to include call-stacks these days. These are invaluable to locating the moment where something went wrong, but unfortunately, they don’t provide much context as to how the program came to this point. What do your support engineers ask for when investigating problems? A registry dump? A file listing? Configuration files? Why not package these up in an archive that can be sent through to your technical support people? Is your software capable of telling you the final moments before the crash? Can it report the features used that led to its demise? If it doesn’t, retrofitting this sort of code to your application can be considered a “long term investment”. It will cost your development now, it’s an unsellable feature for the customer, but you will reap the rewards for your effort down the track. Trust me, it will be worth it!
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