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2016 June 14

Things to do for book

Filed under: Circuits course — gasstationwithoutpumps @ 15:24
Tags: ,

I’ve finally finished my grading for the quarter, after a solid week of grading, and so I can now catch up on some of my administrative tasks (like checking the articulation framework documents, trying to find an undergraduate director for bioengineering for Fall quarter, checking the 30 or so senior exit portfolios, and so forth).

I can also start thinking about the tasks for me on revising my book, which will take up big chunks of summer and fall:

  • Move the book files into a source-code control system, probably mercurial, and use and off-site backup, probably BitBucket.  I should have had the files in a source-code control system from the beginning, but I never got around to setting it up.  This is a couple of years overdue, and I shouldn’t make any more updates to the book until I’ve done it.
  • Rearrange book to put labs in new order, moving all the audio labs into the second half, and moving the instrumentation amplifier and transimpedance amplifier into the first half.
  • Revise parts list for next year’s labs.
    • May want to use a different phototransistor (without the filter that makes it less sensitive to visible light).
    • Choose nFET with lower threshold voltage (maybe pFET also).
    • Find better resistor assortment.
  • Add hobbyist add-ons to the labs, for people who want to go beyond what we can do in class.  For example, I could add
    • designing a triangle-wave generator to the class-D amplifier, so that it can be self-contained,
    • sound input from a phone jack to class-D amplifier (with info about TRRS plugs)
    • logarithmic transimpedance amplifier for optical pulse monitor, to make it tolerant of different light levels and finger thicknesses
    • optical pulse monitor using reflected (actually back-scattered) light instead of transmitted light, so all the optics is on one side
    • motor controller based on H-bridge used in class D
    • temperature controller using thermistor, FET, and power resistor
    • galvanic skin response measurement?
    • oscillator design other than Schmitt trigger relaxation oscillator?  Maybe a Colpitts oscillator with the big inductor (though even with 10μF and 220μH, the frequency would be rather high for audio use)?
    • make Schmitt trigger out of comparator chip
    • EMG controller (either with analog envelope detection or with software envelope detection)
  • Insist on LaTeX for design reports.  I had too many reports with terrible math typesetting, incorrect figure numbering, and bad font substitutions with Microsoft Word or Google docs reports.  I’ll need to include a short tutorial in the book, with pointers to more complete ones.
  • Make it clear in the book that design reports build on each other, but each report needs to be self-contained—for example, the class-D amplifier report should contain circuits, results, and some discussion from the microphone, loudspeaker, and preamp labs; and the EKG lab report should include some information from the blood pressure and pulse monitor labs.
  • Add more background physics and math at the beginning of the book, to review (or introduce, for some students) topics we need.
  • Should I add a short lab characterizing the I-vs-V curve for an nFET and a pFET?  If so, where would I fit it in?  What about for a diode (could be LED)?
  • Bypass capacitor discussion should be moved to between the preamp lab and the class-D lab.  I need to talk more about power routing and location of bypass capacitors for the class D lab (it is important that the bypass capacitors be between the the noise-generating FETs and rest of the circuitry, which is noise-sensitive).  May need to introduce the concept of the power wiring not being a single node, so that “clean 5V” and “dirty 5V” are different nodes.
  • Class-D lab should have students measure and record the amount of current and power that their amplifier takes with no sound (removing the mic?) and with loud sound input, both with and without the LC filter.
  • Class-D lab should require students to show oscilloscope traces of the gate and drain of an nFET and of a pFET in the final H-bridge, both for turning on and for turning off.
  • EKG, blood pressure, and pulse monitor prelabs should have students compute the attenuation of 60Hz interference (relative to the signal in the passband) for low-pass filters that they design.

I should also review what students had to say about the course (look at discussion in previous post, for example).


2016 June 11

Teaching writing lab reports

Filed under: Circuits course — gasstationwithoutpumps @ 09:24
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Greg Jacobs, in his post Jacobs Physics: Report from the AP reading: Teach your class to write concise laboratory procedures. Please., asks high-school physics teachers to teach students how to write concisely:

Part (a) of our question asks for a description of a laboratory procedure. It could be answered in 20 words: “Use a meterstick to measure the height of a dropped ball before and after it bounces. Repeat for multiple heights.

“But oh, no … when America’s physics students are asked to describe a procedure, they go all Better Homes and Gardens Cookery Manual on us. Folks, it’s not necessary to tell me to gather the materials, nor to remind me to first obtain a ball and a wall to throw it against. Nor do you have to tell me that I’m going to record all data in a lab notebook, nor that I’m going to do anything carefully or exactly. Just get to the point—what should I measure, and how should I measure it.

Please don’t underestimate the emotional impact on the exam reader of being confronted with a wall of text. We have to grade over a hundred thousand exams. When we turn the page and see dense writing through which we have to wade to find the important bits that earn points, we figuratively—sometimes literally, especially near 5:00 PM—hit ourselves in the forehead. Now, we’re professionals, and I know that we all take pride in grading each exam appropriately to the rubric. Nevertheless, don’t you think it’s worth making things easy for us, when we be nearing brain fatigue? Just as good businesspeople make it easy for customers to give them money, a good physics student makes it easy for the grader to award points. 

Don’t think I’m making fun of or whining about students here. Writing a wall of text where a couple of sentences would suffice is a learned behavior. The students taking the AP exam are merely writing the same kinds of procedures that they’ve been writing in their own physics classes. It is thus our collective responsibility as physics teachers to teach conciseness.

As I’ve been spending far too much time this week grading an 11-cm-thick stack of design reports from my applied electronics course, I have considerable sympathy with Greg Jacobs’s view.

Technical writing is all about the 4 Cs: clear, correct, concise, and complete. Although there is always some tension between clarity and correctness, and between completeness and being concise, I generally find pretty high correlations between the four properties. Often, the very long reports are muddled, incomprehensible bundles of improperly applied factoids, while the essential information is missing entirely.

Part of the reason I have such a huge stack of papers to grade at the end of the quarter is that I have been giving “redo” grades for any errors in non-redundant representations (like schematic diagrams), putting a very high premium on correctness. For the class-D amplifier lab, 80% of the class had to redo the reports, mostly because they had not gotten the orientation of the FET transistors right in the schematics (a serious error that could lead to fires in the amplifier). I must have done a worse job at explaining the FET symbols—several times—than I thought, or maybe it is one of those things that people don’t learn unless they make a mistake and have it pointed out to them, repeatedly. I’ll be trying to fix the book and the lectures next year to reduce this problem.

I’ve also been down-grading students for lack of clarity (especially when the writing seems to indicate a lack of understanding, and not just inability to communicate) and for leaving out essential material (like not providing the schematics for their preamplifier as part of their amplifier lab report, not providing the parameters of the models they fit, or not providing the models they used at all). So clarity and completeness have had a fairly big impact on grades.

But I have not been giving bonus points for being concise, which I probably should start doing, as some students have started using a kitchen-sink approach, throwing in anything that might be tangentially related to the subject. Unfortunately, these are the students most likely to have unclear and incorrect reports, and they leave out the essential material in an attempt to throw in useless background, so their attempts at completeness generally backfire. I need to discourage this behavior, undoubtedly learned in middle school and high school, and get them to focus on the stuff that is unique to their design, rather than telling me Ohm’s Law or the voltage-divider formula over and over.

2016 March 19

Introduction of a technical paper

Filed under: Uncategorized — gasstationwithoutpumps @ 12:19
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I was recently pointed to a post The 5 pivotal paragraphs in a paper | Dynamic Ecologythat gives advice about how to structure a scientific paper.  Most of the advice is good, but I disagree with one statement:

First paragraph of the introduction—you should use this paragraph to embed and contextualize your work in the context of a large classic, timeless, eternal question. What drives species richness. Or controls abundance or distribution. Or gives the best management outcome. Or explains why species are invasive. Or controls carbon flux. You of course are not going to fully answer this question. Indeed no one person, and probably even no generation of scientists will fully answer this question, but ask a really big question. You can then use this big question setup to spend the rest of the introduction summarizing past attempts to answer this question, and show how they have all failed to address the key issue you are about to address.

The first paragraph of the introduction should be the specific point of the paper, not general BS. I read far too many papers (particularly student papers) where there is a huge wad of background dumped before the author gets around to telling me what they are writing about.  It irritates me—especially when I already know most of the background.

Don’t bury the specific goal of the paper at the end of the introduction—your readers may never get that far if you start out with general BS. Start with the specific goal of this paper—not the overall goal of a long-term research project or (even worse) the fundamental dogma of biology.

There is a term for this in journalism—it is known as “burying the lede”, which is considered a major flaw in news reporting.  It is a similarly large flaw in scientific writing.

I recommend that the first paragraph of a scientific article give the specific research question being answered in the article, and that the rest of the introduction then be used for the contextualizing that question—why is it important? how does this study answer it? For engineering reports, the first paragraph should give the main engineering design goal and constraints, again using the rest of the introduction to say why that was important.

If the conclusions of the paper do not answer the question raised in the first paragraph of the introduction, then the question is not specific enough.


2015 December 22

Small updates to book

Filed under: Circuits course — gasstationwithoutpumps @ 13:56
Tags: , ,

I released a couple more small updates to my book today:

  • revised Chapter 25 (Electrodes) and electrode lab
  • small additions to loudspeaker lab to remove several TODO comments
  • cleaned up many (but not all) overfull-box LaTeX errors

I’ll try to get Chapter 27 (EKGs) and the EKG lab redone by the end of 2015, completing the rewrite that I started in June 2015.  After finishing this pass, I’ll raise the minimum price on the book (probably to $3.99 from $2.99), though the book still won’t be “finished”—I’ll still have 46 TODO comments to resolve.

If anyone is waiting for me to finish the book before buying it, remember that as long as I’m publishing it with leanpub, buying a copy entitles you to all updates for free, so you might as well get it now, before I raise the price.

2015 December 14

Sabbatical leave application 2016

Filed under: Circuits course — gasstationwithoutpumps @ 14:33
Tags: , ,

I’ve got to write an application for sabbatical leave and submit it before 2016 March 11.   My plans are to take sabbatical leave for fall quarters at ⅔ or 5/9 pay for the next five years, to gradually drain the accumulated sabbatical leave credits, rather than spending them all at once getting two quarters off at full pay.  If I do that, I can retire after Winter 2021 with one unused sabbatical credit (which is a little left as you can get, as you have to return to the university for at least as long as the duration of your last sabbatical).

It is better for the department for me to take sabbatical at partial pay, as the savings in salary is returned to the department as Temporary Academic Staffing (TAS) funds, which can be used for hiring lecturers.  If I took salary at full pay, the department would get nothing, and if I took leave without pay, they’d get my full salary—at ⅔ salary they get  the remaining ⅓, which should be enough to hire 1.5 lecturers to replace me for that quarter (and cover the 1.4 courses that I’d not be teaching).

The sabbatical leave form is only for the Fall 2016 leave and asks a lot of questions, some of which are difficult to answer briefly.

The application form shall be accompanied by a statement providing in detail the following information:

a. A brief history of the project, from inception through progress to date and projection as to completion date. This history shall include a description of the applicant’s preparation and any significant contributions already made in the field of activity with which the project is concerned.

I’m planning to do two things in Summer and Fall 2016: work on my textbook and try to find a bioelectronics project to design, preferably in collaboration with a doctor at UCSF.  Unfortunately, I don’t know any one at UCSF who has a problem that would be interesting for me to work on, and I’m not very good at the networking needed to find such collaborators. I’m also more interested in open hardware than in proprietary development, and that could be a bad mismatch for the UC emphasis on making money off of research developments in the biomedical field.

Even if I’m vague in the request about starting a bioelectronics project, giving a brief history of the textbook development will take some thought—I can’t very well give them the 373 blog posts I’ve written about the course, as they probably want only one or two paragraphs.  I suppose I should mention the times I’ve taught the course, the evolution of the lab handouts into the current draft of the book, and the need for revision based on changing the level and pace of the course next year. The course will be moved from upper division (junior/senior) to lower division (freshman/sophomore), and split into two quarters (2 4-unit courses, replacing the current 5+2-unit course).  The move to lower division means reducing the prerequisites (I’ll still have differential calculus as a prereq, but not calculus-based physics), which in turns means beefing up the background in the text and in the class, to cover the physics that the students won’t have had.

The book may be publishable after the Fall 2016 leave, but I’ll probably want to try using it at the slower pace during Winter and Spring 2017, and revise it Summer and Fall 2017, based on that experience.  I’m still not sure when the project will be “completed”.  There are many milestones along the way: used in the course (done Spring 2015), released to the public (done in draft form starting August 2015), all the “to-do” notes in the text done (maybe never—I keep finding more that needs to be improved), adopted for teaching by someone other than me, available on paper (maybe never—the cost of printing is high relative to PDF distribution, but see Textbook should be on paper), available in EPUB and MOBI formats (maybe never—those formats are awful for math and for scientific graphics), freezing an edition and getting an ISBN, distributing through a professional publisher (maybe never—the textbook publishers take way too big a share of too high a price, providing little in return except their name).

b. Significance of the project as a contribution to knowledge, to art, to a particular profession; or as an expected contribution to the applicant’s increased effectiveness as a teacher and scholar.

I could find no intro electronics textbook that was suitable for bioengineering students at the level I wanted to teach.  Everything that had sufficient design content assumed that the students had already had at least a circuits course and often several low-level analog electronics courses. The books that assumed no prior electronics experience all ended up being “cookbooks”, which had students building things that others designed, or “physics” books, doing demos to illustrate concepts, with no design work in either case. There seems to be a real need for books that get students to design simple electronics without years of preliminary drudgery.

c. Name(s) of the location(s) or institution(s) where the project will be carried on, and the names of authorities, if any, with whom it will be conducted.

Textbook writing will happen at home.  Finding a project to collaborate on with someone else is less definite—I’ll probably try to find collaborators at UCSF, though that will not be easy to arrange, as I don’t want to move to San Francisco, but only visit for a few days at a time every couple of weeks. Stanford would be closer, but the doctors at the Stanford medical school have easy access to Stanford engineering faculty, so finding a fruitful collaboration is likely to be harder.

d. Assurances of cooperation, or authorization to conduct the project, received from individuals, institutions, or agencies.

No authorization is needed for the textbook project, and nothing has been set up yet for doing a collaboration.  It may be that I’ll spend much of the first sabbatical just finding people and setting up mechanisms for later collaborations.

e. Description of all financial support expected during the sabbatical leave, including any fellowship, grant, government-sponsored exchange lectureship, or payment for contract research. (See also APM-740-18 and 740-19.)

No external support expected. I may do small amounts of consulting (well less than the 1-day-a-week limit), if the opportunity arises.

f. Description of University service which will be provided if the applicant proposes to substitute significant University service for some or all of the teaching/instructional requirements of a sabbatical leave in residence (See APM 740-8-b & CAPM 900.700-G)

Not doing a leave in residence, but I may still do some service work at UCSC while on leave, like giving the “Speaking Loudly” workshop for Women in Science and Engineering or helping the advising office with new-student orientation.

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