Example: If Robinson Crusoe fishes by hand, he can catch 20 fish each week. If he takes a week off to make a net, he can then catch 25 fish a week with the net until it wears out in 10 weeks. In order to avoid starving during the week that he is weaving the net, he can borrow 10 fish from Friday, on the condition that he pays back the 10 fish plus an extra 5 fish. The cost of the net is the 20 fish that he gave up by not fishing for a week plus the 5 extra fish paid to Friday, or 25 fish. The gross marginal productivity of the net (the total addition to productivity that it contributes) is (5 fish per week)•(10 weeks) = 50 fish. The net marginal productivity of the net (the total addition to productivity that it contributes, less its cost) is (50 fish) – (25 fish) = 25 fish.
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NMAP Results Starting nmap 3.81 ( http://www.insecure.org/nmap ) at 2006-07-27 16:05 Central Daylight Time Interesting ports on MainRouter.cybersec.cs.uwp.edu (10.1.1.1): (The 1659 ports scanned but not shown below are in state: closed) PORT STATE SERVICE 22/tcp open ssh 23/tcp open telnet 80/tcp open http 443/tcp open https MAC Address: 00:14:69:3A:FE:F6 (Unknown) Interesting ports on MainSwitch.cybersec.cs.uwp.edu (10.1.1.2): (The 1661 ports scanned but not shown below are in state: closed) PORT STATE SERVICE 23/tcp open telnet 80/tcp open http MAC Address: 00:14:1C:CB:7E:40 (Unknown) Interesting ports on sholmes.cybersec.cs.uwp.edu (10.1.1.3): (The 1647 ports scanned but not shown below are in state: closed) PORT STATE SERVICE 22/tcp open ssh 53/tcp open domain 80/tcp open http 110/tcp open pop3 111/tcp open rpcbind 113/tcp open auth 139/tcp open netbios-ssn 143/tcp open imap 445/tcp open microsoft-ds 548/tcp open afpovertcp 631/tcp open ipp 644/tcp open unknown 668/tcp open unknown 993/tcp open imaps 2049/tcp open nfs 3128/tcp open squid-http MAC Address: 00:0E:A6:5C:E1:67 (Asustek Computer) Nmap finished: 3 IP addresses (3 hosts up) scanned in 2.360 seconds
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Maji Safi Jason Arble, Peter Balkam, Kaitlin Menzie, Minh Tran Faculty Advisor: Prof. Paul Siqueira Abstract System Overview Maji Safi is a remotely controlled device allowing users with a SMS-enabled cell phone to access measurements of physical water parameters where the device is deployed. Users text the device to issue commands to detect the presence of water, return turbidity, temperature, and pH measurements. The device then texts a web server (running Twilio’s web API) to report measurements. The server interprets the measurements and reports back to users via SMS. Our device targets countries experiencing economic water scarcity, where lack of information regarding the water quality of unimproved water resources leads to a poor water-delivery infrastructure. Admins ● Water Detector (yellow) ● Temperature Sensor (violet) ● Turbidity Sensor (green) ● pH Sensor (red) Data can be used to supplement chemical testing, allowing officials to monitor sanitation and correlate water conditions over time with growth of bacteria. People Scientists Device Control Request Block Diagram Application Control Signals Sensor Readings Sensor Readings Sensing The diagram (above left) are example use cases. We intend to have it be used as a scientific instrument, tool in the design and regulation of water distribution infrastructure, and a means by which locals learn about the water around them. Above right illustrates possible deployment sites: refined wells, unprotected wells, and small bodies of exposed surface water. Device Specifications Parameters Goal Actual/Dev. Device Volume 4400 ㎠ 4000 ㎠ Housing Water-Resistant, Buoyant Water-Resistant, Buoyant Server-User Response Time < 5 minutes < 1 minute Phone-User Response Time < 1 minute < 30 seconds Turbidity Sensor Accuracy ± 0.01-5 NTUs. ± 100 NTU pH Sensor Accuracy ± 0.5 ±1 Temperature Sensor Accuracy ± 3°C ± 3°C Power Consumption ≅ 1.4 W 1.35 W Battery Life 12 hours 18.5 hours Deployment Duration 1-3 Months 1-3 months SMS Text($)/Day $0.01-$0.03 (1 SMS/Day) $1.00-$5.00 (1 SMS/Day) Cost/Device <$100 $227.92 ● Solar panel extends the deployment time, allowing continuous measurements to be taken for weeks or months. ● Sensors are fairly accurate, power efficient, but could be improved upon or specialized for different applications Water Detector The water detector uses simple voltage divider (shown right) whose output voltage is read by the microcontroller. If this voltage is between a threshold between one and two volts and makes a binary decision on whether or not there is water. This threshold was determined from an experiment involving measuring the resistance of different states of water and calculating the output voltage. This data is shown in the table to the right. Substance Impedance (1 cm) Output Voltage Tap water 86 kΩ 1.50 V Sugar Water 99 kΩ 1.65 V Oatmeal Water 75 kΩ 1.36 V Garlic Salt Water Rice Water 65 kΩ 1.23 V 90 kΩ 1.55 V Mud 4 MΩ 4.76 V Acknowledgement Special thanks to our advisor Professor Paul Siqueira, our evaluators Sandip Kundu and Hossein Pishro-Nik, Kris Hollot, Francis Caron and Professor John E.Tobiason. Department of Electrical and Computer Engineering ECE 415/ECE 416 – SENIOR DESIGN PROJECT 2016 College of Engineering - University of Massachusetts Amherst SDP16
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Fish • Most fish reproduce by laying eggs, though some fish, such as great white sharks, give birth to live babies called pups • Fish use a variety of low-pitched sounds to convey messages to each other. They moan, grunt, croak, boom, hiss, whistle, creak, shriek, and wail. They rattle their bones and gnash their teeth. However, fish do not have vocal chords. They use other parts of their bodies to make noises, such as vibrating muscles against their swim bladder • Saltwater fish need to drink more water than freshwater fish. Since seawater is saltier than the liquids in a fish’s body, water inside the fish is constantly flowing out. If they didn’t drink to replace the lost water, saltwater fish would dry up like prunes.
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