If you pitted your car’s engine against your car’s brakes, which would win?

As you’ve almost certainly heard, Toyota is under a tremendous amount of scrutiny at the moment due to reports of “unintended acceleration” in its cars.   My personal belief is that the problem is driver error attributable to mass delusion, since you’re no more likely to encounter such a situation in a Toyota than in any other brand.  One tends to find what one is seeking to find.   It hasn’t helped that Toyota’s initial handling of the situation will go down as a textbook case of what not to do.

Okay, but what about the reports where drivers claimed to be pressing the brake pedal to no effect?  Can the engine really overpower the brakes in a modern car?  Let’s do some back-of-the-envelope math to find out.

Assume that a car (a simplified model of the Lexus ES 350 in this case) and its passengers weighs 4000 lbs, has a 270 hp engine operating at the peak of its powerband, is going 70 mph, and can stop from 70 mph in 176 ft.   In metric units, that’s 1818 kg, 201 kW, 31 m/s, and 53.6 m.  Assuming constant deceleration, we see that the acceleration and time to decelerate is

v^2 = v_0 ^2 + 2 * a * (d-d_0)

0 = 31.3^2 + 2 * a * (53.6)

a = -9.13 m/s^2

t = (v – v_0) / a

t = 3.42 s

This means that the car is capable of decelerating at just under 1 g.

Now, let’s  look at how much power the brakes are dissipating during that stop.  First, we need to find the energy of the car at speed. Again assuming constant deceleration,

Ek = 0.5 * m * v^2

Ek = 0.5 * 1818 * 31.3^2

Ek = 890 kJ

Next, we solve for power:

P = E/t

P = 890 kJ / 3.42 s

P = 260 kW

Since the brakes are capable of dissipating more power than the engine is capable of producing, the brakes will win over the engine — though obviously the stopping distance and time will be increased.

Now, this margin might not appear to be much above the power output of the engine, but it ignores a few things:

• The engine produces peak power only in a limited rpm band, so the power output at any given time is likely to be less than the theoretical maximum
• There are significant drivetrain losses, so the actual power at the wheels is about 15% lower than that at the engine’s crankshaft
• Torque, and not power dissipation, is a strong factor when considering the actual stopping capabilities of a braking system

That last point is probably quite important, but I will leave exact calculation of its significance as an exercise for the reader.

There are some other caveats.  Brake effectiveness decreases with increased heat (a condition known as “brake fade”), so continued or repeated application of the brakes might severely hamper their ability to stop the vehicle.  The situation is further degraded by the loss of vacuum assist after repeated applications of the brake pedal while at speed.  Engine vacuum decreases with engine speed, so at full throttle, if the vacuum reserve has been depleted, the driver might find it very difficult to fully apply the brakes.

As a further aside: what about the parking/emergency brake?  Although it operates using an entirely separate system, it is very weak.  My BMW had no problem overpowering the parking brake from a standstill — something that was so easy and so common that it warranted an idiot light on the dash — so I am quite doubtful that it could stop the car in a reasonable distance from highway speeds even without the extra force from the engine.  (No numbers for analysis here, sorry.) Stick with the main brakes.

The idea that a car’s braking system can stop a car from highway speeds, even at full throttle, is supported by empirical evidence.  Car and Driver did a series of tests of the matter, in which they had no problems stopping various cars.  For example, the V6 Camry they tested stopped from 70 mph in 174 ft under normal conditions.  When the test was repeated with the throttle wide open, the same stop required 190 ft — an increase of less than 10%.

If anything, it seems like poor user interface design or poor user training is at fault here.  How many people know that power brakes offer less power assistance after being pumped?  Who besides techies familiar with ATX-style power supplies would guess that one must hold down the start/stop button on a modern car for about three seconds to force it to turn off?  How many drivers have practiced panic stops or evasive driving?

But I suppose new floormats are a good enough placebo.

I have several medium-sized cardboard boxes sitting around unopened from the last time I moved (about nine months ago).  They are nondescript and unlabeled.   Just strong, brown, plain boxes.  What they hold I do not remember.

If somebody put a gun to my head and said, “Tell me what’s in those boxes or you’ll die!” — well, I’d probably open them up and inform the inquisitive aggressor of the contents.  However, if the hypothetical gunman stopped me and insisted that I answer before looking, I would be without a clue:

“Books, perhaps?” I would stammer.  “Ok, which ones?” would be the response.  Again, I would draw a complete blank.

Clearly, I haven’t missed the utility of whatever lies in those cardboard caskets.

The only certainty is uncertainty; what they hold is — simultaneously — both valuable and worthless.  It will take observation to collapse it into a single truth.

I’m sure that the moment I open those boxes, I will be unable to live without whatever they contain.

In the beginning, god created the computer monitor.  The foreground glowed green; the background remained inky black.  And for a long while, that was the state of the world.  Then, in the mid 1990s, there was a great awakening. With the rise of the GUI, and particularly Windows 95, the world discovered and embraced full-screen, full-color, lush, vivid desktop backgrounds.

I change desktop wallpapers about as often as I change cell phones (i.e., rarely), so I have a reasonably clear recollection of my history, backgroundically speaking, for the past decade or so.

"Sierra by Moonlight" from Digital Blasphemy. My background circa 1999.

Our desktop backgrounds are windows into our soul.  They reflect our dreams for the future and our nostalgia for the past.  They show our desires and our triumphs.  They lurk as ever-present reminders of what we find appealing.

Porsche Carrera GT. My dream car and background circa 2003.

Some treat them as art.  Others use them to encourage relaxation or spur productivity.  A minority even recognize their potential for pranks, like the ol’ take-a-screenshot-and-remove-the-icons gag.

Solid black. It was a time of rudderless ennui, circa 2005.

What makes the perfect wallpaper?  After all, the image is seldom seen, as the efficient computer user will have every pixel of screen real estate covered by maximized windows.  I, for one, see my desktop background only while locking or unlocking my computer.  Should the image make it easy to see the desktop icons?  Should it look good stretched or cropped to the prevailing aspect ratio?  Should it exist at all?

Stanford from the air: a fairy-tale view via Microsoft Live Maps. My hopes, dreams, and identity during the period of use: March 2007 - June 2009.

I’ve taken a number of nature photos that I think would make good backgrounds, and yet… few of them evoke the emotional response that I find necessary for a compelling choice.  Notably, I can’t recall ever using a photo of people for a background.  Perhaps I don’t want to cover their faces with my windows?

Avalanche Lake in Glacier National Park. In use as background: June 2009 - present.

Our choices of desktop wallpapers are perhaps most closely related to our choices of profile photos on the various social networks.  The profile photos project how we wish the world to perceive us; the wallpapers project how we wish to see ourselves.  Proud fathers, adventurous rebels, stoic visionaries, drunken douches… all samples from the broad spectrum of possibilities.

So dream about that sports car, that island, that retirement.  Remind yourself about your spouse, your child, and your family.  Remember that trip, that dog, that crazy night.  Boost your concentration.   Be practical.  Be ridiculous. Be artistic.  Be rational.  There are no wrong answers.  Choose one and learn about yourself.

After a few more months of hard work, most of it outside of the public eye, I am happy to announce Blurity 0.2.  No, that’s not 2.0 — it’s 0.2, indicating that this is the much-improved second beta release.

Blurry photos, be gone!

Blurity has a new look, faster interaction, and — most importantly — a much-improved deblurring engine.

Is it perfect? No.  Not by a long shot.  But I do believe that Blurity now meets the inclusion criteria for the category of “somewhat useful.”

That said, there are some caveats.  A few ways to be disappointed:

• Submitting a huge image and expecting processing to be done nearly instantly.  It takes a while, as in five or more minutes, to process most images.
• Trying to use it from a non-Webkit smartphone.  If your phone runs Android, iPhone OS 3.0+, or WebOS (e.g., the Palm Pre), your experience should be quite decent.
• Expecting miracles.  If the blur in the image is extreme, if the noise in the image is crazy, if the image compression is incredibly aggressive, if the image is really small, if the photo is horribly overexposed… well, then, Blurity probably won’t work too well.  It works best on moderately blurry, not-too-noisy, not-too-compressed, reasonably large, reasonably well-exposed photographs.
• Selecting a bad focus point.  The focus point should be the part of the image that you most wish would have been sharp.  The deblurring is applied to the entire image, but the focus point is used to model the blur, so it’s important that you choose something reasonable.

I sincerely appreciate the feedback that you all sent my way after the initial release.  Many of the changes in the new version were driven by those comments, and many of the future changes will be linked to comments that I have yet to act upon.  Comments on this newer version are appreciated and needed.

With the site now at a point where it isn’t a complete embarrassment, I’m going to begin a marketing push that extends beyond my blogs.  Expect to see and hear more in the coming days as I actively promote it for the first time.

Give Blurity a try.  Make your blurry photos sharp.  Let me know what you think.

(Cross-posted on Northstartup)

A couple months ago, I tweeted about my disappointment over my new Moleskine notebook falling apart.   I loved everything about the design of that notebook, but the construction quality was quite poor.

I complained to the company and soon received this response:

“Dear Sir,

I’m very sorry for the trouble. All the notebooks are hand made and so they are not perfect as the ones made by machine.

We have a strict quality control but sometimes it’s very hard to find the defects.
We will send you a new Moleskine notebook and please, accept our apologise.

Kindest regards,
Vittoria Cleva”

That was in October.  Today, I went out to the mailbox and was pleasantly surprised to find a large letter postmarked from Milan.

I opened the package, and there it was: a brand new soft-cover extra-large plain-page Moleskine notebook.  Woohoo!

I just hope that this one holds up better than the last one…

Moleskine, you’re getting a second chance.