i hate school

[rmjjensen]

here's my first final exam of the week ............it's just gonna get worse

Problem Statement: You have been hired as the lead systems engineer by a start-up company that has just secured an SBIR-Phase 1 contract from the US Department of Homeland Security. The project is to design and build a Trace Contaminant Detector (TCD) to detect the presence of extremely small quantities of biological and/or chemical hazards in an airport security environment. The heart of the sensor system in a 16 channel Quartz Crystal Microbalance (QCM) array.
Each QCM consists of a quartz crystal coated with an adsorptive surface along with a pair of Au electrodes. The adsorptive surface is specific to a single analyte and allows a minute amount (a few nanograms) of the contaminant to adhere to it; thus changing the mass of the crystal structure. This change in mass causes a proportional shift in the resonant frequency of the quartz crystal. The mass of the adhering layer is calculated by using the Sauerbrey relation:
Äm = C Äf
Where C = 17.7 ng Hz-1cm-2 for a 5MHz quartz crystal. The QCM array consists of 16 separate QCM structures, each with a 14mm diameter quartz crystal, and each responding to a specific biological or chemical contaminant.
Perform a system-level design of the TCD device. Your device must output a digital bitstream that allows for:
1. The display of the detected quantity of each of the 16 contaminants; and,
2. A network interface to a remote host for data analysis and archival.
Other desired device specifications are:
Mass Resolution, ng: 3
Maximum Mass Load, ug: 90
Output Voltage Range, V: +- 4

Your system level design should not focus on individual components; rather, it should provide block diagrams of systems and subsystems, functionality and adherence to current communications standards.
(100 Points)

enjoy .....my guess is i got a D+, maybe C-

-Mike

[petesvx2]

Holy ****.

[Mr. Pockets]

If you don't enjoy it, why don't you change majors?

[rmjjensen]

Change majors ....no way...just one more year left!

It's just funny cuz the whole class was like, ........"ah what, we didn't do anything like this in class." he should be lenient with the grades though. I dont see how a test like that determines ur knowledge of the class as a whole.

[Noir]

that my friend looks fun

[LarryIII]

What's really sad is that I understand the problem.
You need a sniffer hooked up to a mass spectrometer that varies the voltage source +/- 4V. The teacher is arcane. He should have asked for an output of 4-20 ma, which is the standard industrial range.

[Ron Mummert]

Originally posted by LarryIII
What's really sad is that I understand the problem.
You need a sniffer hooked up to a mass spectrometer that varies the voltage source +/- 4V. The teacher is arcane. He should have asked for an output of 4-20 ma, which is the standard industrial range.

Solution to Mike's problem.

Larry does the math & submits the answer for Mike.
Mike gets an "A".

Mike washes & waxes three SVXes all summer.
Larry gets the hammock & Chivas.

Ron.

[immortal_suby]

I know some of those words.

[Sidewinder]

Originally posted by LarryIII
What's really sad is that I understand the problem.
You need a sniffer hooked up to a mass spectrometer that varies the voltage source +/- 4V. The teacher is arcane. He should have asked for an output of 4-20 ma, which is the standard industrial range.

Yeah, uh Larry, where exactly does your expertise end? Would thermodynamics be a familiar subject?

I just had my fourth thermo test today. I love engineering, I just have the courses like this. They give you four bits of information and expect eight different things to come of it. Just don't like it.

[rmjjensen]

Originally posted by LarryIII
What's really sad is that I understand the problem.
You need a sniffer hooked up to a mass spectrometer that varies the voltage source +/- 4V. The teacher is arcane. He should have asked for an output of 4-20 ma, which is the standard industrial range.

haha that's awesome ...I had to look up that word "arcane."

It was just a wild exam considering the class is electrical communication systems. We've covered just different COMM systems like AM, FM, PM, and dig. Nothing near "sniffers/mass spectrometers." I do see how the exam related to ECOMMS.

I wound up determining the surface area of each of the 16 crystals. Then using the delta(m) = C *Delta(f) to meet the 90ug mass requirement I can determine the maximum change in oscillation frequency that will occur for 1-16 crystals. ....did that and then made my block diagram with some filters, and old school frequency to voltage converters like those used in generic fm detector circuits. ...then took that output to a PCM circuit that samples, and quantizes the voltages levels into a digital bitstream using something like a Q-Mary / QPSK and feeding it through a DS-3,4,5 type data system.

........that was after staring at it for the first 45 minutes like, "wtf?!" ...I never did finish in the 2 hr time limit.

I'll wash some SVXs vs that. And Larry ........what is your occupation?

-Mike

[petesvx2]

Originally posted by immortal_suby
I know some of those words.

If we combine the ones you know, and the ones I know, we may be on to something here.

I hate school too.

lol.

[LarryIII]

Mike,

I am a consulting (insulting) mechanical engineer. The company that I work for builds bio-tech and pharmaceutical factories.
I 've been doing this kind of work for the chemical, plastics, petrochemical, mining & metals, and pharma industries for over 30 years now. Before that, I worked for Boeing Aircraft in the helicoptor division.


Since I'm an engineer, sometimes I even get to drive the locomotive, but usually they only let me blow the whistle....TOOOT TOOT !!

[rmjjensen]

Originally posted by LarryIII
Mike,

I am a consulting (insulting) mechanical engineer. The company that I work for builds bio-tech and pharmaceutical factories.
I 've been doing this kind of work for the chemical, plastics, petrochemical, mining & metals, and pharma industries for over 30 years now. Before that, I worked for Boeing Aircraft in the helicoptor division.


Since I'm an engineer, sometimes I even get to drive the locomotive, but usually they only let me blow the whistle....TOOOT TOOT !!

haha ...that's awesome! Well it seems like you are doing quite well. Hopefully I'll be doing good enough to bid against the next insane SVX memorabilia item at reading.

[GreenMarine]

God, that really made my head hurt... And I still have one more year till I get my Associates of Science... Then 2 years after that at NC State for Mechanical Engineering... Man, I'm gonna be a broken and torn person when I get outta school