Sensors - Recap

1. Sensors - Recap H. Scott Matthews March 23, 2004

2. Admin Issues • HW #3 - Mean 36/40 • A few not submitted yet

3. Recap of Last Lecture(s) • Finished discussion of ‘mgmt systems’ • Sensors interact with our environment and signal stimuli and changes • Sensor networks act as interfaces between sensors and our systems and practices • Historically, trend has been simple sensors connected to complex systems

4. Evolution of Systems • Increased data handling, analytic techniques (prob/stats, optimization, multi-obj analysis) • Computing power increased led to ability to look at larger scopes • In both problem area and application • Eventually went from mainframes to PCs - which sped up reporting time • “Sensor networks” / networks of sensors

5. Simple Sensor Example • Infrared Beam that reflects and sensor checks when beam broken • Used for ‘motion or passing through’ (mall) • Sensor connected to DC power source • Radio Shack $10, connect to alarm sys • Normally Open/Closed circuits • Watch multimeter as we make the sensor activate • What is happening? Why?

6. Implementation of Sensor • What kind of signal/system is this sensor generating (binary/boolean) • ‘Is it happening?’ - yes or no? • Could measure temperature? • Could measure temp cutoff (thermostat) • What other types of sensors/systems could/would work in a similar way? • Vehicle detector, occupancy, .. • How would we connect to a mgmt system?

7. More Complex ‘Sensor’ • Not really a ‘sensor’ but instead the communication method used by one • Simple radio antennas - transmit and receive • e.g. as used by wireless LAN on campus • Imagine this is ‘EZ-Pass’ • What is EZ-Pass - RFID tag system to uniquely identify cars and automate toll collection • Uses a transponder to send/receive radio signals • What else could you use it for?

8. Other Sensor Apps for IM • Asset condition / performance • Vehicle counting / tracking • Non-destructive testing/evaluation • Acoustic: use sound waves to detect flaws (pulses or continuous) in materials or structures • Thermal: similar to above - compression/tension cause hot/cold • Vibration: create signatures, compare

9. Connect with HW 3 - Value • Hip buzzwords of the day: “road value pricing” • Road pricing = pay for driving • Value pricing = it benefits you (reduced congestion, more maintenance, etc.) • Peak/demand pricing - Airlines do it, why not built infrastructure? • ‘Lexus lanes’ - HOT lanes (HOV + toll) • San Diego I-15: 8-miles, $0.50 -> $8 range! • Cordon tolls (e.g. central London)

10. London Congestion Tolls • Enacted to reduce traffic in central London, get fees from users • 5 pound fee / day ($8) - 70M per year ($150M) • After 6 months: • 50,000 fewer cars per day entering zone • But only 4,000 less net people (switch to metro) • Congestion in the zone down 30% • Vehicles entering zone during the day down 16% • Trip times decreased by an average 14% • Public transport is coping well with the increased number of ex-car users • 20% reduction in the number of accidents

11. Intermediate Use 1972-1997

12. For next time: • Read “Critical Infrastructure” Excerpt • Read Heller “Interdependencies”