Gas station without pumps

2015 June 4

Last lab of Spring 2015

Filed under: Circuits course — gasstationwithoutpumps @ 22:50
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I spent all day today in the lab for the electronics class, from around 9:30 a.m. until the last students packed up and left at 8:30 p.m.  This was the last lab of the quarter, and I had decided to stay until all the students had left.

Most of the students got their EKG boards soldered up and working today (there may be a few who left without demoing their working boards, and the last group at 8:30 p.m. had just had some more wiring errors pointed out to them).

I’m amazed sometimes at how basically competent designers can be very careless in their wiring, rushing through the placement and soldering without carefully checking each connection. The result is a 10-minute savings in wiring time, and a 4-hour or more cost in debugging and resoldering time.

Tomorrow in class I plan to go over a couple of 1-transistor amplifier designs, but that shouldn’t take the whole time.I’ll give them some pointers to companies that sell parts and kits that might be of use to them: Digikey, Mouser, Jameco, Sparkfun, Adafruit Industries, Itead Studio, Seeedstudio, Smart Prototyping, Elecrow, OSH Park, Makershed, … . And I’ll be sure to mention some local resources: Santa Cruz Electronics and Idea Fab Labs.

I also hope to remind the students of some of the goals of the course, and try to see whether the goals have been met.  I quote from the supplemental form for the course renaming that was approved this spring (effective next year).

The Program Learning outcomes for the bioengineering program are as follows:
A bioengineering student completing the program should

  • have a broad knowledge of science and engineering disciplines including biology, chemistry, physics, mathematics, statistics, and computer science; [Not relevant to this course]
  • be able to apply their broad knowledge to identify, formulate, and solve engineering design problems; [Students passing BME 101L will be able to design simple amplifiers and RC filters for a variety of sensor-interfacing applications.]
  • be able to find and use information from a variety of sources, including books, journal articles, online encyclopedias, and manufacturer data sheets; [Students passing BME 101L will be able to find and read data sheets for a number of analog electronics parts.]
  • be able to design and conduct experiments, as well as to analyze and interpret data; [Students passing BME 101L will be able to measure signals with multimeters, oscilloscopes, and data-acquisition devices,  plot the data, and fit non-linear models to the data.]
  • be able to communicate problems, experiments, and design solutions in writing, orally, and as posters; [Students passing BME 101L will be able to write coherent design reports for electronics designs with block diagrams, schematics, and descriptions of design choices made.] and
  • be able to apply ethical reasoning to make decisions about engineering methods and solutions in a global, economic, environmental, and societal context. [Not relevant to this course]

So tomorrow I plan to ask where the students feel that they are able to design simple amplifiers and RC filters, whether they can find and read data sheets for analog parts, whether they can measure signals with multimeters, oscilloscopes, and data acquisition devices, whether they can plot the data and fit non-linear models to it, and whether they can write coherent design reports.

I had some unofficial goals for the course also: to turn a few of the students into electronics hobbyists, to encourage a few to declare the bioelectronics concentration of bioengineering, to teach some tool-using, maker skills (calipers, micrometer, soldering iron, …), and to make all of them better at attacking problems by dividing into subproblems with clear interfaces between the subproblems.  I’ll ask about those things also.

I’ll also want some detailed suggestions for the course.  (So far I’ve gotten one: fume extractors for the lab for use when soldering.)  Some things I’m curious about include

  • Should the first amplifier lab (the low-power audio amp lab) be changed to use a single power supply and solder up the board, so that the board can be used as a preamp for the class-D power amp lab later?  We could then also do an emitter follower (common collector) class-A amplifier using the preamp board.  If they solder up a pre-amp, then we could eliminate soldering the instrumentation amp for the blood pressure lab.
  • Should I redesign the prototyping board to have more room for resistors and no instrumentation amp slot, making it more suitable for the preamp lab and the EKG lab?  A new custom board is still cheaper than something like the $4 perma-proto boards from Adafruit.
  • Should I switch from 18-turn trimmer pots to 3/4-turn trimmers with shafts?  The ones with shafts tend to be easier to turn, but not as precise and the multi-turn worm gear pots.  There are 3/4-turn trimmer pots that play nicely with a breadboard, though they take up a bit more space than the worm-gear trimmers we used this year.
  • Are there tools or parts that almost no one used?
  • Are there tools or parts that should be added to the lab kit? If so, at what price do they stop being attractive?
  • Should students buy oscilloscope and voltmeter probes, like they do at UCSB, rather than having to deal with broken probes or probes locked inconveniently to equipment?
  • Should there be more practice questions in the book? (currently I have very few, with almost all the questions being part of prelab assignments)
  • Does there need to be a “what you are already expected to know” section or chapter, to review material that students are supposed to know already?
  • Which labs took up too much time for the amount of learning achieved? How can they be streamlined?
  • How much time did the course really take total for the quarter?
  • What suggestions do students have for more fun labs?

2015 March 27

Bogus comparison of Word and LaTeX

Filed under: Uncategorized — gasstationwithoutpumps @ 09:36
Tags: , ,

An article was recently brought to my attention that claimed to compare LaTeX to Word for preparing manuscripts: PLOS ONE: An Efficiency Comparison of Document Preparation Systems Used in Academic Research and Development. The authors claim,

To assist the research community, we report a software usability study in which 40 researchers across different disciplines prepared scholarly texts with either Microsoft Word or LaTeX. The probe texts included simple continuous text, text with tables and subheadings, and complex text with several mathematical equations. We show that LaTeX users were slower than Word users, wrote less text in the same amount of time, and produced more typesetting, orthographical, grammatical, and formatting errors.

It turns out to be a completely bogus study—they compared typist or typesetting tasks, not authoring tasks. There was no inserting new figures or equations into the middle of a draft, no rearranging sections, no changing citations styles—not even any writing—just copying text from an existing typeset document. It is very misleading to say that the “LaTeX users … wrote less text”, as none of the subjects were writing, just copying, which uses a very different set of skills.

I don’t think that there is much question that for simply retyping an existing document, a WYSIWYG editor like Word is better than a document compiler like LaTeX, but that has very little to do with the tasks of an author. (And even they noted that the LaTeX users enjoyed the task more than the Word users.)

For those of us who use LaTeX on a regular basis, the benefits do not come from speeding up our typing—LaTeX is a bit slower to work with than a WYSIWYG editor.  The advantages come from things like automatic renumbering of figures and references to them, floating figures that don’t require manual placement (except when there are too many figures—then having to do manual placement with LaTeX is a pain), good math handling, automatic formatting of section and chapter headings, being able to define macros for commonly used actions, and the versatility of having a programming language available. For example, I have a macro that I like to use for proper formatting of conditional probability expressions, and another that I use for references to sections, so that I can switch between “Section 3.2″, “Sec. 3.2″, and “§3.2″ through an entire book with a change to just one line in the file.

LaTeX also has the advantage of having a much longer life span than Word—I can still run 30-year-old LaTeX files and print them, and I expect that the files I create now will still be usable in 30 years (if anyone still cares), while Word files become unusable in only 10-to-20 years.  LaTeX is also free and runs on almost any computer (the original TeX was written for machines that by modern standards were really tiny—64k bytes of RAM).

For those who want multiple-author simultaneous access (like Google Docs), there are web services like sharelatex.com that permit multiple authors to edit a LaTeX document simultaneously. I’ve used sharelatex.com with a co-author, and found it to be fairly effective, though the server behind the rendering is ridiculously slow—40 seconds for  a 10-page document on the web service, while I can compile my whole 217-page textbook three times in about 12 seconds on my 2009 MacBook Pro.

Like the emacs vs. vi wars, the LaTeX vs. Word camps are more about what people are used to and what culture they identify with than the actual advantages and disadvantages of the different tools. Bogus studies like the one in PLoS One don’t really serve any positive function (unless you happen to be a monopoly software seller like Microsoft).

 

2015 March 14

Not been blogging much

Those who have been following my blog for a while may have noticed that my blogging frequency has dropped quite a bit for the past few months.  I had planned to blog after every class meeting of the freshman design seminar, as I did last year, but I’ve simply been too busy. In addition to teach the freshman design seminar, I was also teaching the senior thesis writing course. Although both of these are 2-unit courses with small numbers of students (so the department gets essentially no additional resources as a result of my teaching them), they are both somewhat time-consuming, though the senior thesis writing much more so than the freshman design.

This weekend is the first weekend that I did not have a stack of thesis drafts to provide detailed feedback on (I’ve been averaging over 6 drafts a week to comment on all quarter).  In addition to the thesis drafts, I also arranged to have a 20-minute individual meeting weekly with each of the 19 seniors writing theses this year.  Because the meetings often ran over, I spent about 7 hours a week on those meetings.  I started each meeting with the student giving me a 2-minute elevator talk (after telling me what audience they were addressing the talk to and with what purpose). This served two purposes: to get the students to practice concise descriptions of their projects and to remind me which of the 19 projects we were talking about. (Several pairs of students were doing closely related projects in the same lab, so it was really easy for me to mix up the projects—and I have almost no memory for faces and names, so I needed the prompts!)

Next weekend I’ll pay for this weekend off—I’ll have all 19 theses to grade between Thursday night and Tuesday morning.  I won’t be doing as detailed feedback on this round—first, because there aren’t enough hours to do 2–3 hours a thesis; second, because I suspect that half the students won’t come by my office to pick up the graded theses (even those who still have a quarter to go before their theses are complete).

I hope to have the freshman design course all graded before the senior theses come in—they have their last lab on Monday and their design reports are due Tuesday.  The freshman reports are much shorter than the senior theses, so I can probably get them all graded on Wednesday.  If I get them done in a timely manner, I may take the time to try to do an end-of-quarter summary of the freshman design project course, which I think ran more smoothly this year, though not quite in the direction I had originally thought we would go.

This weekend, I’m getting back to work on my book, since I want to release a draft for the applied electronics course that starts in 2 weeks. I at least want the chapters and labs for the first two weeks to be finished, with no major overhauls planned for the remainder. I spent about 4 hours on the book today (after goofing around for a while with some phototransistor circuits that aren’t really relevant to the course—I’ll probably blog about that when I have more time, but it will take about 8 hours to do a good blog post on it, and I don’t have that much spare time this week). I hope to have the schedule for all the labs finished this weekend also—I made a good start on that in December, when I last had time to work on the book.

Next quarter will not give me much writing or blogging time—instead of the 12 contact hours (plus office hours and grading) that I had this quarter, I have 19 contact hours (3.5 hours of electronics lecture, 12 hours of electronics lab, 3.5 hours of banana slug genomics) plus grading 15 prelab assignments and 15 design reports a week for the electronics course. I’m hoping I can convince my co-instructor to do what grading we’ll need for the banana slug genomics, or that we won’t assign much that needs grading.

Also Spring quarter is when most students declare their majors, so I’ll probably have to increase my office hours from 2 hours a week to 3 or 4 to handle the advising load.  Two hours a week was just about right this quarter, especially since I allowed students to reserve a place in line by email.  I only had an empty office once or twice, and only ran an hour over once or twice.

On the administrative side, at least I’ve gotten the 20-page bioengineering self-study  and my 3-page contribution to the bioinformatics self-study done, so I won’t have too much to do on those next quarter.  The Curriculum Leave Plan is done for next year, and I hope it won’t need further modification. I’m reducing my teaching load next year to merely heavy (from insane this year), and some of the buyouts we had counted on for paying lecturers are not coming through, so the department has a structural deficit of about $30k, and only enough reserves to cover that for a couple of years (with no way to replenish the reserves).  I don’t know what we’re going to do long term, as we need to add more offerings of some of our more popular courses, at a cost of about $20k each.

2015 February 25

Freshman design seminar writing notes

Along with the senior-thesis writing course this quarter, I’m also teaching a freshman design seminar. Many of the problems in their first design reports are similar to the problems I see in senior theses (Senior thesis pet peeves, More senior thesis pet peeves, and Still more senior thesis pet peeves). I hope that by catching them early, I can squelch the problems.

Here are some things I saw in the first design report turned in by the freshmen:

  • Every design document should have a title, author, and date. If the document is more than one page log, it should have page numbers.
  • Passive voice should be used very sparingly—use it to turn sentences around to pull the object into the first position, when that is needed to get a smooth old-info-to-new-info flow.  Sometimes you can use it to hide the actor, when you really don’t know who did something, but that should be very rare.
  • Errors in schematics, programs, block diagrams, and other low-redundancy representations are very serious.  In the circuits class, any error in a schematic triggers an automatic REDO for the assignment.  I’m not as harsh in the freshman design class, but there is no notion of “just a little mistake” in a schematic.
  • The battery symbol is not the right way to show a voltage source that is not a battery.  Use the power-port symbol, to indicate connect to a power supply that is not included in the schematic, or include the Arduino board from which you are getting power as a component in the schematic.
  • Bar charts are not appropriate for all that many data representations in the physical and biological sciences.   If you have 2-D data, use a scatter diagram.  A bar should only be used when the area of the bar communicates the quantity of something that is labeled in discrete classes.  (And even then a single point is often clearer.)
  • Captions on figures should be about a paragraph long.  Remember that people generally flip through a paper looking at the pictures before deciding whether to read it.  If the figures and captions are mysterious, they’ll give up without ever reading the paper.  A lot of academic authors, when writing a paper for publication, start by choosing the figures and writing the captions.  Those figures and captions then form the backbone of the paper, which is written to explain and amplify that backbone.
  • In academic writing, figures are treated as floating insertions, not fixed with respect to the text.  Therefore, it is correct to refer to the figures by name, “Figure 1″, but not by location (“above” or “below”). Every figure in a paper should be referred to explicitly by name in the main body of the text, and the floating insertion put near where the first reference to the figure occurs.
  • Citations in modern scholarly works are not done as footnotes—those went out of style 50 or 60 years ago, and only high school teachers still use that style.  Modern papers put all the citations at the end (in any of several different styles, usually specific to a particular journal).  I have a slight preference for reference lists that are sorted by author, rather than by order cited in the paper, and I have a preference towards high-redundancy reference list formats rather than minimalist ones, but I don’t have a particular style that I recommend.
  • There is no point to saying “web” in a citation—if something comes from the web, then give me the URL (or DOI). For material that is only on the web (not citable as a journal article), you must give the URL or DOI.
  • When typing numbers, never start them with a decimal point—use a leading zero to prevent the easily missed leading decimal point. Even better is to follow the engineering convention of using numbers between 1 and 1000 with exponents of 10 that are multiples of three.  That is, instead of saying .01, or even 0.01, say 10E-3.  The advantage is that the powers of 1000 have prefix names, so that .01A becomes 10mA.  Don’t worry about significant figure meanings, because engineers express significance explicitly, not through imprecise sig-fig conventions.  That is, and engineer would say 10mA±2mA, not 1.E-2A (which a physicist would interpret as 10mA±5mA) or 1.0E-2A (which a physicist would interpret as 10mA±0.5mA).
  • In describing where components are in a schematic diagram, “before” and “after” don’t make much sense.  I have no idea what you mean if you say that a resistor is before an LED. When engineers use “before” or “after” it is generally in an information-flow sense.  For example, you may filter before amplifying or amplify before filtering, but if a resistor and capacitor are in series, neither is “before” the other.
  • Students use “would” in many different ways, but mostly incorrectly, as if it were some formal form of “was” or “will be”, while it is actually a past subjunctive form of the modal auxiliary “will”.  There are many correct uses of “would” in general English, but in technical writing, it is usually reserved for “contrary to fact” statements. When a student writes “I would grow bacteria for 2 days”, I immediately want to know why they don’t.
  • The pronoun “this” is very confusing, as the reader has to work out what antecedent is meant. A lot of effort can be saved if “this” and “these” are not used as pronouns but only as demonstrative adjectives modifying a noun. This usage is much easier for people to follow, as the noun helps enormously in figuring out the antecedent.  If you can’t figure out what noun to use, then your reader has no hope of understanding what you meant by “this”.
  • “First” is already an adverb and needs no -ly. The same is true of “second”, “third”, and “last”.  For some reason, no one makes the mistake with “next”, which follows the same pattern of being both an adjective and an adverb.  I wonder why that is?

2015 February 21

Long sentence

Filed under: Uncategorized — gasstationwithoutpumps @ 16:07
Tags: ,

Joseph Mitchell created a marvelous long sentence (found in A City of Many Pasts in The New Yorker):

And I should also say that when I say the past I mean a number of pasts, a hodgepodge of pasts, a spider’s web of pasts, a jungle of pasts: my own past; my father’s past; my mother’s past; the pasts of my brothers and sisters; the past of a small farming town geographically misnamed Fairmont down in the cypress swamps and black gum bottoms and wild magnolia bays of southeastern North Carolina, a town in which I grew up and from which I fled as soon as I could but which I go back to as often as I can and have for years and for which even at this late date I am now and then all of a sudden and for no conscious reason at all heart-wrenchingly homesick; the pasts of several furnished-room houses and side-street hotels in New York City in which I lived during the early years of the Depression, when I was first discovering the city, and that disappeared one by one without a trace a long time ago but that evidently made a deep impression on me, for every once in a while the parlor or the lobby of one of them or my old room in one of them turns up eerily recognizable in a dream; the pasts of a number of speakeasies, diners, greasy spoons, and drugstore lunch counters scattered all over the city that I knew very well in the same period and that also have disappeared and that also turn up in dreams; the pasts of a score or so of strange men and women—bohemians, visionaries, obsessives, impostors, fanatics, lost souls, gypsy kings and gypsy queens, and out-and-out freak-show freaks—whom I got to know and kept in touch with for years while working as a newspaper reporter and whom I thought of back then as being uniquely strange, only-one-of-a-kind-in-the-whole-world strange, but whom, since almost everybody has come to seem strange to me, including myself, I now think of, without taking a thing away from them, as being strange all right, no doubt about that, but also as being stereotypes—as being stereotypically strange, so to speak, or perhaps prototypically strange would be more exact or archetypically strange or even ur-strange or maybe old-fashioned pre-Freudian-insight strange would be about right, three good examples of whom are (1) a bearded lady who was billed as Lady Olga and who spent summers out on the road in circus sideshows and winters in a basement sideshow on Forty-second Street called Hubert’s Museum, and who used to be introduced to audiences by sideshow professors as having been born in a castle in Potsdam, Germany, and being the half sister of a French duke but who I learned to my astonishment when I first talked with her actually came from a farm in a county in North Carolina six counties west of the county I come from and who loved this farm and started longing to go back to it almost from the moment she left it at the age of twenty-one to work in a circus but who made her relatives uncomfortable when she went back for a visit (“ ‘How long are you going to stay’ was always the first question they asked me,” she once said) and who finally quit going back and from then on thought of herself as an exile and spoke of herself as an exile (“Some people are exiled by the government,” she would say, “and some are exiled by the po-lice or the F.B.I. or the head of some old labor union or the Mafia or the Black Hand or the K.K.K., but I was exiled by my own flesh and blood”), and who became a legend in the sideshow world because of her imaginatively sarcastic and sometimes imaginatively obscene and sometimes imaginatively brutal remarks about people in sideshow audiences delivered deadpan and sotto voce to her fellow-freaks grouped around her on the platform, and (2) a street preacher named James Jefferson Davis Hall, who also came up here from the South and who lived in what he called sackcloth-and-ashes poverty in a tenement off Ninth Avenue in the Forties and who believed that God had given him the ability to read between the lines in the Bible and who also believed that while doing so he had discovered that the end of the world was soon to take place and who also believed that he had been guided by God to make this discovery and who furthermore believed that God had chosen him to go forth and let the people of the world know what he had discovered or else supposing he kept this dreadful knowledge to himself God would turn his back on him and in time to come he would be judged as having committed the unforgivable sin and would burn in Hell forever and who consequently trudged up and down the principal streets and avenues of the city for a generation desperately crying out his message until he wore himself out and who is dead and gone now and long dead and gone but whose message remembered in the middle of the night (“It’s coming! Oh, it’s coming!” he would cry out. “The end of the world is coming! Oh, yes! Any day now! Any night now! Any hour now! Any minute now! Any second now!”) doesn’t seem as improbable as it used to, and (3) an old Serbian gypsy woman named Mary Miller—she called herself Madame Miller—whom I got to know with the help of an old-enemy-become-old-friend of hers, a retired detective in the Pickpocket and Confidence Squad, and whom I visited a number of times over a period of ten years in a succession of her ofisas, or fortune-telling parlors, and who was fascinating to me because she was always smiling and gentle and serene, an unusually sweet-natured old woman, a good mother, a good grandmother, a good great-grandmother, but who nevertheless had a reputation among detectives in con-game squads in police departments in big cities all over the country for the uncanny perceptiveness with which she could pick out women of a narrowly specific kind—middle-aged, depressed, unstable, and suggestible, and with access to a bank account, almost always a good-sized savings bank account—from the general run of those who came to her to have their fortunes told and for the mercilessness with which she could gradually get hold of their money by performing a cruel old gypsy swindle on them, the hokkano baro, or the big trick; and, finally, not to mention a good many other pasts, the past of New York City insofar as it is connected directly or indirectly with my own past, and particularly the past of the part of New York City that is known as lower Manhattan, the part that runs from the Battery to the Brooklyn Bridge and that encompasses the Fulton Fish Market and its environs, and which is part of the city that I look upon, if you will forgive me for sounding so high-flown, as my spiritual home.

Although this sort of long sentence may be amusing as a tour de force in literary writing, marvelous mainly for its ability to remain grammatical, despite the length, I hope never to see such a long sentence in technical writing.

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