Tuesday, December 14, 2010

PH253 final grades, mark 2

After going through the whole spreadsheet and looking at the final exams a third time, I decided to revise upward the partial credit on a couple of questions on the final. This will affect a lot (but not all) of you, depending on whether you chose to do those problems or not, and depending on what exactly you did. For some of you, the change was enough to affect your final grade.

I also went through everyone's final exam for a third time, and on a couple of exams I found that I had misunderstood the answer given, and you were owed more points.

Long story short, some grades needed to be revised.* Once I check my spreadsheet for what must be the 15th time, I am going to upload really final grades later this evening. I've been obsessing about this for three days now, but I think finally have gone over everything enough that I think it is consistent and fair.

*I didn't revise anyone's grade downward. If there was a grading error in your favor, it stayed.

Monday, December 13, 2010

PH253: preliminary grades on myBama

I've posted "final" grades on myBama, subject to the following qualifications:
  1. I have to check my spreadsheet thoroughly to be sure all my calculations are correct.
  2. I will have one more look at your final exams if you are on the borderline between two grades (I've graded them twice thusfar).
  3. Some of you might still sneak in an extra-credit assignment or late HW by the end of Monday.  (HINT)
So, I may have to make revisions after I review everything again, but as of right now everything seems to be in order. If you feel there is a mistake, contact me ASAP. Ditto if you want to know your grade breakdown.

Overall, I think most of you will not be surprised by your grade - not many of you moved up or down greatly based on your final exam score. (The class average was 0.76% higher after the final, the final exam average was 82%.) Notably, however, a couple of you managed to pull out a passing grade based on a very impressive showing on the final, which was nice to see.

Anyway, I hope you enjoyed the semester, I certainly did.

Thursday, December 9, 2010

PH253 Final exam pro tip

Pro tip: a problem might look on first sight just like one you've seen, but you still have to read it all the way through to make sure.

I say that since I'm seeing that same mistake again & again on HW9 ... the second problem was nearly like one from last year, but the second part was different in a crucial way. By "different" I mean "not even remotely close."

Let's recap: when you see a familiar-looking problem tomorrow, it might be a trap. Make sure I haven't changed anything key before you just go solving stuff all willy-nilly.

And, a bonus pro-tip: don't forget your calculator. There may actually be numbers other than pi and 2 on the exam. I think a 7 got in there while I wasn't looking.

PH253: server issues

UPDATE 2: with the server being down, Moodle is also down until further notice. Hopefully it will come back up some time today. Also, a draft of the formula sheet for the final.

UPDATE: HW and Exams mirrored here. The additional notes as well (well, most of them, until I hit my quota on bama.edu. Lame.)

For what I hope to be a short while, old HW/exams/etc are unavailable, owing to some script kiddie messing with the server I'm using:
I just got word that the machine that runs the faculty websites has been hax0red, so we have to take it offline till we can figure out what happened.
I will try to get a mirror up later this morning.

PH253: HW10 solutions

I have HW10 solutions ready. Given the end-of-semester craziness, I know quite a few of you will turn HW10 in late and take the hit on points. That's fine by me, it is your choice.

Because of that constraint, I had planned to not post the HW10 solutions publicly, but give them out by email to anyone who had already turned in HW10. The idea was that you wouldn't get to see the solutions until I saw your completed HW set.

Of course, that idea was hopelessly naive, and probably just punishes the people who need the most help. 

So, here are the HW10 solutions. I will still accept HW10 up through the final exam, minus the usual late penalty. Remember that I drop the lowest homework.

PH253: 8am exams suck and we can't do a thing about it

So our exam is 8am this Friday. That really sucks, and there is nothing we can do about it. Here are some thoughts about surviving the exam:
  1. Sleep the night before. All-night cramming may help you learn a few new things, but on a problem-based exam it is critical that you are able to think clearly and quickly. Zoning out because you're tired works against that very strongly.
  2. Use a buddy system if you're not a morning person. Seriously. Two different times I have actually called students on their cell phone to get them out of bed after the exam started. Call each other in the morning so you don't oversleep.
  3. Don't bother memorizing stuff. I want to see if you can think & solve problems, so you'll have all the formulas you need.
  4. Do ask questions during the exam. If it isn't 100% clear to you, ask for clarification. I may or may not be able to answer your question, but it can't hurt.
  5. Do be explicit about showing your work, and turn in anything you wrote on. Partial credit is key. If you are stuck on how to finish a problem, at least describe in words what you would like to do, that's worth something.
  6. Try not to get stuck on any one problem, since you will be somewhat pressed for time. (You will have more than enough time to finish if you work carefully and quickly, but if you get stuck for 15min on one problem, that may not be the case).
  7. Use your formula sheets for example problems, notes to yourself, or a guide to what various formulas are for (and what they are not for). You'll have a sufficient formula sheet, but that only helps if you recognize the formulas ...
  8. Remember that Wolfram Integrator will not be there to save the day on the exam, so remind yourself how to integrate the hard way ;-) Anything beyond basic polynomials will be on the formula sheet.
As I have more random work-avoiding thoughts, I will post them here ...

Wednesday, December 8, 2010

PH253: Exam 2 solutions

Just realized today after one of you emailed me that I never posted Exam 2 and its solution.

Here you are. Let me know if you find any errors or need further clarification on any problems.

Also, last semester's final with solutions.

PH253: final exam

I've decided to make it easier on you for the final, at least in terms of what you need to study.

The final exam questions will be drawn entirely from exam and homework problems from this and last semester, including last semester's final exam. (Just like I did for the last exam.) All I'm going to do is take old HW and exam problems, change some quantities or what I'm asking for, strip them down to an appropriate length if necessary, and recycle them. [Update: by exam problems, I mean the actual exam, not the sample problems.]

Some HW/exam problems are too long for the exam. Those problems will be shortened (perhaps only asking part a out of several parts). Some HW/exam problems involve too much time-consuming math for an exam, those problems will be modified to be less tedious.

So, there you go: all you need to do is understand how the old problems are worked (they will not be used verbatim, so copying them is of limited utility), and you are all set.

Again, you can bring in 2 formula sheets - either 2 sheets front & back, or 4 sheets with one side only. I'll provide all the basic formulas you need.

And, as a reminder, the final is this Friday at 8am in the usual room.

Thursday, December 2, 2010

Slides for 2 Dec 2010 lecture

UPDATE: the revised slides I actually used are at the same link below. Not many changes.

Here is an outline of tomorrow's lecture. My first draft of the slides are here, 15Mb PDF. Given that it is the second-to-last day of classes, I suppose you can check these out and decide whether to come or not ;-) For you EE-types, a lot of this stuff (like the truth tables and logic gates) is either the familiar subject of your recurring nightmares, or it will be soon.

The outline, as of now:
  • basic computer architecture
  • memory 
    • reminder: how transistors work
    • FLASH memory
    • S/D/MRAM basics 
    • memory architecture
  • logic & computation
    • how to implement logic & computation
    • logic gates 
    • building gates from transistors/switches
    • computation example: comparison, addition
  • information physics
    • energy requirements & thermal stability
    • mechanical, electrical, and magnetic storage
    • losses per cycle
    • the safety of Moore's "law" and fundamental limits
  • Time permitting (probably not): hard disks
    • overview of operation
    • media (analogous to CD/vinyl)
    • reading & writing
    • positioning & mechanical
    • why magnets?
    • history & recent boom times
    • fundamental limits approaching
 No, this is not on the final.