CSC 200 Undergraduate Problem Seminar: Assignments

First, internalize the problem...

• The assignments will be posted here after the day's class, along with the due date. Assignments are due at the beginning of class on the due date. In general, no credit will be allowed for for late assignments. Turn what you have in in for partial credit.
  
  
• For any assignment, I expect a well organized report-style writeup that describes in detail what you did, why you did it, and what the results were. This includes negative results. Scratch work and computer code, if requested should be appended to the main writeup with appropriate pointers.
  
  
• Attribute ANY work that is not your own, including software off the web, text cribbed from other sources, etc. You are encouraged to look for resources, but not to the extent that it negates the point of the assignment. This is sometimes a fine line, especially in programming assignments. I will try to be specific as to what I expect you to write as a minimum. If in doubt, ask. In any case, use of UN-attributed material is plagiarism, and a violation of the University's academic honesty policy.
  Plagiarism is taken VERY seriously in this department. DON'T DO IT. If in doubt, reference.
  
  
• Specifically, text taken from web pages, even a single sentence, is plagiarism. Text paraphrased from web pages is plagiarism. Sentences from web pages cut up into phrases and re-arranged are plagiarism. If you want to avoid possible problems, my suggestion is never write while looking at text. Generate everything from your own understanding of the subject.
  
  
• Use of unattributed text in any written assignment will result in zero credit for that assignment. Text that comes from an outside source should appear in quotes. Too much use of quoted material will tend to reduce your credit for an assignment, as the point of written assignments is to convey your understanding of a subject.
  
  
• In general, you should consider written assignments for this course to be public documents - just as published research papers are public documents. As such I may place them in a forum where they may be scrutinized by your colleagues for accuracy, clarity, and for unattributed material.
  
  
• You are encouraged to discuss general techniques and specific approaches to general problems with your fellow students, or anyone else. Unless specifically directed in an assignment, however, you are not to share code you have written, or your written solutions to specific problems.
  
  

Wednesday, January 16, 2013

• Class activity: Danger, Will Robinson! Danger!
• Class activity: Introductory material, Survey forms, Tours.
• Assignment 1:
  Bring to class an item that is dangerous, but not intended as a weapon or destructive device (not permitted on campus in any case). Also nothing illegal. Prepare a writeup describing the dangerous potential of your item, and be ready to present it to the class. I'm looking for thoughtful observation here more than snarky cleverness. If I get pens (or pencils) that are mightier than the sword, and brains of the most dangerous game, I will be disappointed.
  
  Due: Wednesday, January 23, 2013.
  
• Assignment 2: First impossible project:
  
  With your team-mate, Design and build a simple electronic circuit that flashes an LED approximately once per second.
  
  Bring your device to class to demo it. Also a writeup referencing ALL your sources of information, including pointers you received from other students.
  
  Breadboards, wire, and some electronic components are available in the undergraduate lab in Hylan 301. Also a few tools. A flashing circuit can certainly be built from what is there. But you can use anything you can get your hands on.
  
  You are allowed (in fact expected and encouraged) to look for information and design ideas on or off the web, and even pass ideas around to your classmates. However, you or your team must build your device with your own hands. An app for your iphone does not count for this assignment
  
  Note that the exact components specified some web design may not be present in the lab, so you will have to understand enough about what is going on to make reasonable substitutions.
  
  Due: Wednesday, January 23, 2013.
  

Monday, January 21, 2013.

• Class activity: MLK day of service
  
  

Wednesday, January 23, 2013.

• Class activity: Observation of multiple flashing circuits.
• Class activity: Presentation of danger.
• Assignment: Construct a sturdy, physical dodecahedron at least 1 inch between parallel faces (bigger is fine). Structure should be strong enough to support a five pound load in any orientation. A single-layer paper structure for which templates can be found and printed on the internet will probably not suffice (I expect a little more effort than that). Artifacts that somehow semantically satisfy my attempt to specify the desired degree of strength, but have flimsy aspects (e.g. just a ball with paper extensions) are counter to the spirit of the assignment. This is not a class about legalisms. Shape should be accurate to 1/10 inch. Any material that does the job is OK. (Again, I am not interested in semantic tricks like virtual materials, or a bottle of water that could be argued to contain any shape...) You may work by yourself, or in teams of 2. The solids will be tested in class.
  
  Due: Monday, January 28, 2013.

Monday, January 28, 2013

• Class activity: Testing of Euclidean solids.
• Class activity: Intro discussion of Supersonic driver (SSD) project.
• Assignment: Write a short program in C that counts to 1 trillion (that is, 10^12), by ones. By definition, this means that your program must go through at least 10^12 states. There is one very small subtlety here, but your program should need to be be no more than a few lines long. Run and time your program. On a gigahertz processor, you should be able to run such a program in under an hour or so (you can check progress by writing a version that prints something every billion counts or so). If you are not running fast enough, go back and write something that will run faster.
  
  Now the fun part. Get hold of the .o file compiled version of your code. Map and count the bits that occur in non-zero bytes. (The reason for the non-zero byte condition is that .o files are generally padded with non-functional 0s to fill out some integral block condition on length) Figure out a way to flip an arbitrarily selected bit in the non-zero-byte portion of the .o file. Now experiment with flipping a single bit, and then try to re-link and re-run the program. Try this for every bit in your program. What percent of the time does the program
  A. Fail to link successfully.
  B. Crash or terminate prematurely in the first five seconds of running.
  C. Run for five seconds or more with no obvious problems.
  If the program fails to link in all cases find the parity check that the linker is using to identify a corrupt file and work around it.
  
  You might need to be a bit careful on a Windows system (though I hope not). Linux has been fairly well projected for a long time against programs getting out of their space, but early Windows systems would let you jump or write to vital system areas by mucking with a binary, and crash the OS. I really hope this is no longer true, but am basically a Windows ignoramus, and don't know for sure.
  
  Now the really fun part. Can you think of a way to write a program (doing the same counting) that is less susceptible to single bit flips? (other than increasing the length of the program with a lot of garbage code that is never executed). The idea is, given a certain probability that a stored bit will be corrupted over time, is there a way to make a stored program less susceptible to such damage. Increasing the length with no-ops doesn't help in this case, because the original program is still there and has the same probability of being whacked somewhere.
  
  Turn in a writeup of your results, including a printout of your program (Just so I can check that it actually counts to a trillion. Don't worry. I almost never will want to look a source code).
  
  Due: Wednesday, January 30, 2013.
  

Wednesday, January 30, 2013

• Class activity: Discussion of program damage results
• Class activity: Accidental discussion of interstellar civilization
• Assignment: Consider a simple circuit composed of the 25uF capacitor brought to class in series with a circular coil 1 cm in diameter made of 10 turns of #20 copper wire wound so that the thickness and length are negligible. Suppose that there is an initial potential of 2000V on the capacitor, and a switch is closed to complete the circuit at time t = 0;
  
  A. Model the current in the circuit as a function of time to sufficient accuracy to determine the following to 10% accuracy, assuming the coil does not burn up.
  1. The initial rate of current increase, dI/dt in the circuit.
  2. The peak current in the circuit (in amperes).
  3. The time t1 (after the switch is closed) at which the peak current occurs (in seconds, milliseconds, microseconds etc. as appropriate).
  4. The time t2 at which the first 0 crossing of the current occurs (if such a point exists).
  5. The ratio of the first current peak to the second current peak (if there is oscillation).
  6. The time constant tc associated with the asymptotic exponential decay
  B. Determine whether the coil is likely to melt due to resistive heating. If it does, determine the approximate time of failure. Note that if the temperature increase modeled using room temperature conductivity of copper exceeds a few hundred degrees Celcius, you would need to incorporate the decreasing conductivity with temperature into the model in order to get reasonably accurate results. This would probably involve a numerical simulation, which counts as above and beyond the call of duty for this assignment, but feel free if you want to.
  
  C. Plot the behavior of the current as a function of time to aid in understanding the circuit behavior.
  
  Note: You will need to calculate the inductance and resistance of your coil. Ignore inductance and resistance of the capacitor and the leads. You will probably need to do some research on the behavior of simple series RCL circuits. You will need information on the resistance of #20 copper wire, its dimensions, the specific heat, density, melting point etc. of copper, and quite likely other physical constants. You will need formulas for the inductance of your coil (these can be looked up, I don't expect you to do those integrals).
  
  You can assume that the wire is insulated sufficiently well that there is no arcing or shorting across the coil. You can assume the coil is sufficiently well constructed that it will not self-destruct due to magnetic forces. If you are feeling ambitious, you could compute the approximate magnitude and direction of these forces and decide if the copper wire has sufficient strength to withstand them, or if external support of the coil would be needed.
  
  Due: Monday, February 4, 2013.
  
  

Monday, February 4, 2013

• Class activity: Discussion of LRC circuit problem.
• Assignment: Use numerical optimization to solve the brachistochrone problem for the case of a sliding mass, initially at rest, moving down one meter (e.g. in y) and across one meter (e.g. in x) (in earth-normal gravity). Splitting x into 100 or so segments and doing piecewise linear integration of the motion along each segment to compute the sliding time will probably suffice for this problem, as the solution is a smooth curve. The trick is the search efficiently through the space of piecewise linear curves for the best. Graph your solution curve, and compare it to the theoretically optimal cycloid. Also compare your time to the theoretical minimum. Writeup as usual.
  Due: Monday, February 11 2013.

Wednesday, February 6, 2013

• Class activity: Introductory discussion of SSMD construction.
• Assignment: For Monday Feb. 11, write a brief memo outlining ideas for organizing the SSMD construction effort into components that can be addressed in parallel by teams of 4-5 people. Particular attention should be paid to the need for ultimate integration of components, and how to make sure that results fit cleanly together without the need for extensive retrofitting, reconstruction, or redesign.
• Reading: Short intro to coil drivers. This is fairly low-level, and clearly written by hobbyists rather than pros at this (who are mostly employed by military contractors and keep their mouths shut), but it provides a reasonable outline of some of the general issues involved. Note that we are planning what they refer to as an air-core inductive driver, rather than the conceptually simpler ferromagnet approach. The latter can't easily produce fields strong enough to go supersonic in a desktop space because of saturation of the iron cores.

Monday, February 11, 2013

• Class Activity: Discussion of project breakdown and team organization.
• Assignment: Discussed in class (propose ideas for determining the speed of a payload and producing a signal that coincides with the predicted arrival of the the payload at a particular point)

Wednesday, February 13, 2013

• Class activity: Teams. Initial discussions.
• Class activity: Critique of initial artifact design ideas.
• Assignment: Due next Monday (Feb 18 2013)
  Get together with your team and prepare an initial summary of the primary questions and issues you need to address, including interfaces with other teams. Prepare a (single) document describing these issues, and be prepared to present the outcome of your initial discussion to the class

Monday, February 18, 2013

• Class activity: Presentation and discussion of team issues

Wednesday, February 20, 2013

• Class activity: Presentation and discussion of team issues cont.
• Assignment: Each team should prepare a black-box description of their module, with physical and electrical interfaces to the other modules specified

Monday, February 25, 2013

• Class activity: Presentation and discussion of black-box modules
• Meeting of safety, integration, and shop groups.
• Assignment: For next Monday, Each team should produce a prototype design for their module at the component level, and a list of materials/components needed. Where possible detailed electronic specifications should be given including voltage and power ratings. The same is true for mechanical components. Where possible, specify exact materials. (For some components, this is not yet possible, specifically, we do not yet know the exact form factor and inductance of the coils we will be using. Assume the projectile will be made from 3/8 inch round aluminum rod. When values are not determinable yet, specify what information is needed to determine them. Produce as detailed a diagrame as possible of your module.

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