Archive for the ‘ Uncategorized ’ Category

MacBook Battery Swelling?

Last Tuesday, I took apart my 2nd-gen BlackBook to fix my squishy right palmrest (top was not flush against bottom case) when I was surprised by the heat and size of my battery. I don’t have a picture, but it looks like the one in this MacRumors thread.

The battery is thickest at the center. The heat melted the adhesive, so the rubbery back panel is separating from the metal part of the battery. The charge status button needs to be depressed further for the green LEDs to light up.

Summer’s coming on, and it’s pretty humid here in Kobe, so it might just have been the heat, but I feel that this has malfunctioned too easily. There was a battery update/replacement program, but that’s been discontinued since May 31 this year (zut!). Running GNU/Linux, I never got that battery firmware upgrade, and it won’t install from Mac OS installed on an external drive.

On the bright side, the battery still (just) fits, and the capacity doesn’t feel diminished. But I’ll get a new one next month, though, and keep this one as a backup.

And that squishy palmrest: apparently, the top case had been bent when I took it apart last year. I simply bent it back, and no more squish. :)

Advertisements

Supercritical Water Reactors (SCWRs)

My dad is a nuclear engineer, and he likes fluid dynamics. :) Last night he explained to me how the specific heat of a supercritical fluid sharply peaks at a certain pressure range (this relates, in some way too complicated for me, to the delta function). Okay, I didn’t understand all of it, but this is the idea behind supercritical water reactors (SCWRs) currently under investigation in 13 countries around the world. If the pressure of the coolant can be maintained within that range, we could get more efficient, simpler, and generally safer reactors because there would be no worry of such things as steam bubbles (different density = problems), pumps, or condensers.

In light water reactors (most reactors in the world are LWRs), water enters the reactor core at 290°C and exits at around 315°C—only a 35°C difference due to water’s high specific heat, but this could be improved by using supercritical fluids.

Wikipedia has better writers:

Advantages

  • Supercritical water-cooled reactors promise to have thermal efficiencies of approximately 45% versus the current 33% of light water reactors.
  • The supercritical coolant has a high specific enthalpy.
  • The SCWR design is far simpler than current designs, eliminating circulation pumps, pressurizers, steam generators, steam separators and dryers.

Disadvantages

  • Many of the materials needed for the SCWR are either expensive, rare, or do not exist.
  • Specific start-up procedures required to avoid instability.
  • Unknown chemistry.

Chemistry and LaTeX with mhchem

There is a LaTeX package called mhchem available that makes typesetting chemical equations a lot easier. Sure, you could be lazy and type it all out in math mode like this (sorry, I don’t know much chemistry yet):

[text{C}_6text{H}_{12}text{O}_6 + 6text{O}_2 xrightarrow{text{heat}} 6text{CO}_2 + 6text{H}_2text{O}]

or in text mode:

C$_6$H$_{12}$O$_6$ + 6O$_2 xrightarrow{text{heat}}$ 6CO$_2$ + 6H$_2$O

But that’s ridiculous. Writing it is a pain, and fonts become inconsistent (math vs. normal text). With the mhchem package, however, I can do this:

[ce{C6H12O6 + 6O2 ->[text{heat}] 6CO2 + 6H2O}]

Thank you Martin Hensel, who developed this!

LaTeX packages in home directory

I finally figured out how to get downloaded LaTeX packages working from my home directory:

Create ~/texmf!

I’d actually known that first step since long ago, but it didn’t work after a few tries, so I gave up. Anyhow, it works now, and (for example) I can put a custom bst file in ~/texmf/bibtex/bst without needing separate copies of it in each directory where I have a document in need of it. yay!

Happy New Year

Yeah. Now that I have this blog running, let’s see how long it survives.. Happy New Year!