Broken glasses

Whoops, broke my glasses today.


I was just cleaning them, felt a snap and heard the tinkling of a lens hitting the desk.

Had this pair for about 3 years, and was thinking it was probably time to replace them soon. These ones survived a remarkably long time relatively scratch free unlike my other glasses which have never lasted more than a couple years before they got so scratched up that it was like looking through a hazy window.

This pair was starting to lose the anti-reflection coating though, so it was about getting to the time for replacment.

Fortunately I still had the pair before this one that Connie made me stash away for just such an emergency. There wasn't a significant change in the prescription between the two, just needed replacing because of haziness due to scratches.

Off to the optometrist to get the eyes checked tomorrow for a new prescription.

Harry Potter binging

Connie's been after me to read the Harry Potter series for a while now. It's not one that's ever been on my radar to read but last month I started in on them after finishing off Asimov's Foundation series, Robot series, and derived books.

It's a pretty decent series, and I see the attraction of it to many people. The Wizarding world is quite the interesting universe to live in. Reading it was pretty easy, and most of the books I was able to get through in 2-3 days.

The series turned out to be an enjoyable read, and like many of the other books in our library, it will probably be read a few more times.

Now that we're finished with the books, we'll start binging on the Harry Potter movies.

This is the average x-ray output (μGy/mAs at 40") measured on ~40 radiographic units (fixed and portable units) over about 3 years for both large and small focal spots.


Textbooks say the radiation output should be proportional to kV2. Fitting a power law curve to the data gives the equation

Output (μGy/mAs) = 0.008373*kV1.983

which is pretty darn close to the expected square law.

There's not as much variation as might be expected. Armed with this data, I think I'd be comfortable calculating exposure estimates for patients or image receptors for any radiographic unit.

Half Value Layers

The many years of x-ray equipment testing I've done has generated a lot of potentially useful data on the performance of imaging equipment that I lay hands on.

In the past, I've just measured the half value layer (the thickness of material required to reduce the x-ray beam intensity by one half) of the x-ray beam at one point: 80 kVp. A couple years ago, I decided to add 60, 100 and 120 kVp to satisfy my curiosity. I knew from testing mammography machines that HVL was pretty linear between a narrow range of kV (24-32). Turns out over the much wider range of 60-120 kVp, HVL is still pretty linear. This is close to 3 years worth of HVL data from almost 40 radiographic units (fixed and portable).


Below is the mean HVL as a function of kV. Error bars represent the standard deviation at each kV. The linear fit equation is

HVL = -0.0254 + 0.03868*kV


The histograms below show the spread in HVLs measured at each kV.


There doesn't seem to be any significant trend over time (which is what I would expect). Here I'm using the ID assigned to each survey as a surrogate for time.


A moderately interesting finding I think. One thing that might be interesting to see is how HVL changes with the type of machine (fixed room vs portable). I'd have to go back to my spreadsheets and recollect the data to add in the type of machine though. Not sure I'm curious enough about it to go through all that again, but perhaps.

Digging more into this strange camera artifact problem I've been having, I decided to try uninstalling/reinstalling the Google Camera app. In this case, it means uninstalling any updates and and updating again from the Google Play store.

Uninstalling and reinstalling the update (2.5.052) didn't help things. The shifting is most visible with the red in the map on the book cover, but it's a global shift in the entire image.


Then I thought I'd just uninstall the updates and revert back to the built-in version of the camera app (2.4.018) to try that out. Much to my surprise, I got a perfect picture.


It's pretty reproducible too. With the latest update, the colour shift artifact is there. Back to the built-in version, it's gone. This is getting a little more interesting. Seems more a software issue now than hardware like I was starting to suspect earlier.

A few weeks ago the pictures coming out of my Nexus 5 started having this weird colour shifting artifact.


Note how the green is bleeding off to the right. Look a little closer and there's a strange colour shift across the entire image. Also on the left side of the image is a bar of digital artifact of some kind. Strangely enough, it only appears to happen when taking pictures in portrait orientation. It doesn't happen when I take pictures in landscape orientation.



Even more strangely, it also doesn't happen if I turn the N5 180 degrees (using the phone upside down).


Not entirely sure what's going on here, and so far my Google-fu has been unhelpful. I'm wondering if one of the tumbles my phone has taken recently might have messed something up.

Orlando mini-vacation

This past weekend we made a road trip down to Orlando to catch up with my sister and her family on their vacation. It also happened to be Field Day, so I put the HF rig back into Connie's car so we could play some radio over the weekend.

We drove down Friday and got to Orlando early enough to spend some time browsing around Skycraft Parts and Surplus, a big junk store filled with all manner of awesome stuff for DIY type people.


Part museum, part junk shop, lots of neat stuff. There were bins of electronic components, aisles of nuts, bolts, washers of all sizes, electronic equipment, some tools, wire, rope. Just like being in a candy store.


Don't forget to look up. Lots of stuff hanging from the ceiling in this place, some for sale, some just on display.


That evening we had dinner at Thani Thai which turned out to be quite excellent. Very tasty food, nicely decorated inside.

Saturday morning, we stopped at the Mary Queen of the Universe basilica for a visit and to check out their gift shop. Big church, very nice inside.



As you're walking toward the church from the parking lot, there's a pretty neat statue of Saint Michael


Off to the side of the church is a peaceful little rosary garden.


After the church, we still had a little bit of time to kill before meeting my sister. We found this neat little used book shop called The Book Worm on the way and explored it a bit.


They have a "Things found in books" bulletin board with some interesting items.


If you're looking for the politics section, it's in the bathroom.


Then it was off to meet my sister and her family at the Orlando Science Center. This turned out to be a pretty awesome place, and we ended up spending pretty much the entire afternoon here. There are 4 levels to explore, tons of interactive exhibits to play with and lots of things for kids (big and small) to learn about. Mummies of the World is their current headline exhibit and is pretty cool. Very expansive exhibit with actual mummified bodies and parts. You'll learn about how mummies are created both naturally and by people and get to see them up close and personal. No pictures allowed though.

The rest of OSC is a lot of fun to explore. Dinosaurs, weather, reptiles, several halls filled with hands on interactive exhibits to play with. It's definitely a place worth visiting and spending the day at.

Had a great time in Orlando, and was glad we were able to meet up with my sister and family.



SpaceX (CRS-7) launch

We were out in Orlando for the weekend (more about that later) and as luck would have it, were able to find a spot to watch the SpaceX Dragon launch (CRS-7) off US-528 a few miles from the launch site. This was the first rocket launch I've seen in person and "up close", so I was pretty excited. There were a fair number of people gathered at the same spot to see the launch too, but it wasn't super crowded fortunately. The mid-morning launch also meant the sun was hot, but not unbearably so. I even had a random eyeball QSO with another ham who spotted me tuning around on my HT listening for any launch related radio chatter.

Managed to get some pretty decent pictures of the launch and the rocket ascending with my SLR and 300mm lens. The images are cropped in from the original with some histogram enhancement applied.

Launch time!




About 20 seconds or so after the launch, the loud rumbling sound of the rocket firing reached us.

This was the last photo I took of the rocket before it disappeared behind the cloud. Not long after this shot, Connie told me the rocket had blown up.


The crowd starting to leave the observing site after the launch.


It was a very exciting first launch experience, although hearing about the rocket failure was very disappointing. I'm glad Connie found us a good spot to catch the launch from.

Bulgogi marinade

This is a recipe for a Korean bulgogi marinade that comes from Korean Cooking: Explore One of the Orient's Greatest Culinary Secrets by Hilaire Walden. It's a cookbook that's been on my shelf for quite a while now, and has several dishes that I've enjoyed making. Not sure how easy it is to get now, but you might get lucky and find one at your favourite used book store. It's got some great recipes that don't require special or hard to get ingredients.

  • 4 scallions coarsely chopped (I usually leave these out...not a big fan of onion-y things)
  • 3 garlic cloves, chopped (fresh is best, but the pre-chopped stuff in a jar will do in a pinch)
  • 1 tablespoon crushed toasted sesame seeds (mortar and pestle are great for the crushing part)
  • 3 tablespoons soy sauce (I usually use the low salt version...turns out fine)
  • 2 teaspoons rice wine/dry sherry (I never have any on hand so usually leave it out)
  • 1 tablespoon sesame oil (if you can find toasted sesame seed oil, go with that)
  • 2 tablespoons sugar (I like to use brown sugar)
  • freshly ground pepper (I always forget this)

This should make enough to marinate about a pound or so of your preferred meat/protein product.

After being a volunteer at the SC Aquarium for nearly 10 years and close to 700 hours, I decided it was time to retire and reclaim some of my weekends.

Being a volunteer there was a lot of fun and immensely rewarding. I got to get up close to a lot of cool birds, handled owls, hawks, an eagle, penguins, parrots and other birds there. The work I did was all behind the scenes stuff, nothing glamorous, but it was enjoyable.


I'll miss seeing the birds every other week, and seeing the other staff and volunteers there. Now I'll have some more time to work on other things that have been waiting on the sidelines.