I pride myself on being pretty knowledgeable in computer security and protecting my systems.
I do all the things they say you should do, protect systems with a firewall, run antivirus, don’t click on attachments in emails and install patches from Microsoft as soon as they come out.
I knew something was wrong soon after I started using the tab feature in IE 7 on Windows XP SP3. Everything was fine as long as I only opened one site in each IE window. Opening multiple sites with tabs would cause IE hangs that required me to kill iexplore.exe with task manager. [...] Continue Reading…
How much Vitamin C does a human being require?
First a shocking fact:
99% of all species on Earth do not require Vitamin C.
Why?
Most species continually synthesize ascorbate (vit c) in their liver from ordinary blood glucose. The enzyme in their liver which performs this action is called L-gulonolactone oxidase.
L-gulonolactone oxidase
Even Plants synthesize ascorbate in their cells, suggesting that Vitamin C is extremely important to the proper functioning of all life.
Several species including Guinea Pigs, Fruit Bats, higher apes and humans have a genetic defect that prevents the production of this enzyme. All of these species must take ascorbate since [...] Continue Reading…
Every language has its quirks and Java is no different.
I just spent a couple hours discovering Java’s string comparison quirk.
To illustrate the issue, take the following Pop quiz:
With the following code what statement gets printed?
String a = “hello”;
String b = “there”;
String c = a + b;
if (c == “hellothere” ) {
System.out.println(“c is hellothere”);
}
else {
System.out.println(“c is not hellothere”);
}
If you answered: c is hellothere
You just stumbled over Java’s string comparison quirk.
The correct answer is: c is not hellothere
Boolean operators (like ==) should not be used to compare strings in Java.
The above comparison would [...] Continue Reading…
Continuing my ongoing saga documenting my path to learning Java I discovered an annoying but probably very common problem building and running Java programs.
The application I’m developing will utilize Xalan to process some XML files.
That’s not important to this discussion except for the fact that I am planning to use XALAN predefined libaries contained in .jar files in my application.
Per the installation instructions I dutifully added the directory containing the libaries(as .jar files) to my exisitng CLASSPATH system variable in Windows XP as follows:
Right click My Computer -> Properties -> Advanced tab -> Environment
Variables button -> Under System Variables [...] Continue Reading…
I’ve started a small project where I’ll need a program that I can run on both Windows system and Linux. I had the choice of using either C++ or Java, and decided to jump into learning Java. This is a short log of my tribulations in getting Java and Netbeans working on my Windows XP system.
My first task was to figure out what to install. A quick search around the net makes it clear that Sun is THE authority on Java.
Sun’s Java Page is clear as mud about what I need to download.
After a little research (since [...] Continue Reading…
My now 8 year old son has always had an insatiable interest in Science especially DOING science. His favorite show is the Myth Busters on the Discovery Channel
He’s played around with Helium balloons, built his own rockets and many other things that I’ll try to write about. Anyway, I decided to look around on the net for ideas on experiments with stuff you might find in your Kitchen.
The first experiment we did was Vinegar and Baking Soda:
In the Kitchen sink fill a glass half full with Vinegar and then add a teaspoon of baking soda.
You’ll be amazed at the [...] Continue Reading…
What is the difference between operating a transistor as a switch and as an amplifier?
When a transistor is used as a switch it is fully turned ON and OFF by a control signal usually applied between the base and the emitter. This causes the collector to emitter resistance to drop to a low value.. much like a simple electrical switch. Common electrical components such as lamps can be connected in series with the power supply voltage and the collector and emitter of the transistor.
This allows a small control current applied to the base of the transistor to [...] Continue Reading…
A 0.11 kg ball is thrown straight up into the air with an initial velocity of 26 m/s
Find the momentum of the ball halfway to its maximum height on the way up.
V0 = 26 m/s
g=9.8 m/s^2
Max Height = V^2/2g
= 26^2 / 2*9.8
= 676 /19.6
= 34.489 meters
Halfway up is 1/2 this number or 17.2445 meters
Use the equation for height in terms of time
and solve for t
Height = Vt – 1/2 gt^2
17.2445 = 26t -1/2 (9.8)t^2
4.9t^2-26t+17.2445=0
Use the quadratic formula
( -b +- SQRT(b^2-4ac))/2a
to solve for roots
Roots are 0.777(ball on way up) and 4.52(ball on way down)
Calculate the velocity at [...] Continue Reading…
How do you measure voltage in a circuit?
Yes, you need to use a voltmeter or a multimeter with a voltage scale.
Voltage is always measured with respect to 2 points in an electrical circuit.
Most DC circuits use a common output of the power supply(usually the negative) for one of the points and call this ground (abbreviated GND). The black terminal of your meter should be attached to this point, while the red lead is used to measure voltages in the rest of the circuit with respect to this ground point.
AC circuits also use a common ground point but [...] Continue Reading…
If you have an Ultracapacitor with the below specs…
Boostcap® Ultracapacitor
3000.0 Farad ± 20%; 2.7V
How many would you need to store 1KWH of energy? ( 1,000 watts for an hour)
The energy in Joules stored in a capacitor can be calculated with the following formula
E=(1/2) C V^2
for C=3000F V=2.7 Volts
E=10935 Joules
1Kwh = 3,600,000 Joules
Therefore you would need
3600000/10935 = 329.2 or rounding up
330 capacitors to supply 1Kwh of energy
Modern ultracapacitors are now approaching the energy density of the best batteries and have the advantage of very rapid charge and discharge currents
The device shown at the following link is very similar to the [...] Continue Reading…