vireo's New Writeups

Saving Quicktime movies from a web page (idea)

2002-08-15T03:55:50Z

Using the Mozilla browser, click on the page containing the embedded object (may it be a Quicktime movie, Flash animation, or anything else) using the right mouse button. Select "View Page Info" from the context menu. Click on the "Media" tab. Select the embeded object in the list and click on the "Save as" button.

rocket placement (idea)

2002-02-18T01:33:45Z

First person shooters are now an established genre among video games, much like role-playing games or turn-based strategy games. The many games of the genre have all developed standard features that make sense, features that players expect to see in the game. Many people think that FPSes are all alike because of this, but avid gamers know that subtle but important differences lie elsewhere (for example, the ambiance, the physics model, the weapon balance, the general complexity of the gameplay, etc.). Over time, most FPSes have adopted a somewhat standard set of weapons that fills the space spanned by few parameters: the damage caused by the weapon, the speed of the projectile, the spread, the reload delay, etc. For example, Quake 3's rail gun has zero spread, is almost instantaneous, causes lots of damage but is extremely long to reload; whereas the machine gun has a moderate spread, is instantaneous, has a very high rate but only…

Hessian (thing)

2001-12-11T20:30:14Z

The hessian H of a n-variable function f is a n by n matrix whose (i,j)-th entry is the second order partial derivative:

            2
           d 
H(i,j) = ------ f(x ,x ,...,x )
         dx dx     1  2      n
           i  j

The hessian is symmetric only if the corresponding partial derivatives are continuous. If it is the case, one can gain insight into the behavior of f at a given point a=(a1,a2,...) by computing the determinant of its hessian. For example, if the determinant of the hessian is negative, then a is a saddle point of f. The hessian was introduced by german mathematician Ludwig Otto Hesse in 1842.

torque steer (thing)

2001-10-20T17:00:28Z

(nodeshell rescue)

When turning the steering wheel of a car, and then letting it go, the wheels turn back into a straight orientation. This is due to the way the front wheels are attached to the car: the kingpin and castor are inclined in such a way that when the front wheels are turned, the front of the car is slightly elevated. Thus, the weight of the car forces the wheels in a straight position when the steering wheel is free. However, the axis of rotation of the kingpin, when prolongated to the ground, does not in general intersect the point of contact of the wheel with the ground. This is what is called the steering offset.

In a front wheel drive car, when applying torque to the wheels, there is a force causing them to turn around the kingpin axis, which is proportional to the steering offset. Normally, this force is the same on both front wheels but on opposite directions, and since they are linked, it is cancelled out. However, if the friction is…

parallel dimension (idea)

2001-09-07T21:15:44Z

Interestingly, if other dimensions exist that are not the familiar three spatial dimensions nor the time, they are much more likely to be orthogonal, or in other words, perpendicular, and not parallel. In fact, if it's another dimension, they need not be orthogonal, but they can't be parallel.

Think about it.

Toyota Echo (thing)

2001-09-05T19:03:15Z

The Toyota Echo seems small because it is a little bit shorter and a little bit higher than most (sub-)compact cars. However, as for the frame, it is almost the same as most compact cars. The interior is surprisingly vast and very ergonomic, with lots of room for four adults. It has a 4 cylinders, 1.5-L DOHC VTT-i engine (the 1NZ-FE) that, at 108 hp of peak power and 105 lb-pi of peak torque, provides accelerations comparable to those of the Honda Civic or Mazda Protegé with basic engines. The Echo with manual transmission achieve 5.2 L/100 km on road, which beats every other car in North America except TDI Volks and hybrids. It's a low-cost car that is extremely well designed for its purpose.