Information Systems for you

Questions (Page 165)
	A	temperature sensor
	B	mercury tilt switch
	C	proximity sensor
	D	sound sensor
	E	temperature sensor
	F	pH sensor
	G	humidity sensor
	H	humidity sensor
	I	light sensor
	J	light sensor

Questions (Page 166)
	1	Can continually monitor patients. Nurses can only monitor patients at certain intervals. Frees up staff to deal with emergencies. Fewer nurses are needed and the money can be used elsewhere in the NHS.
	2	Patient's relatives may feel that the system is impersonal. If equipment malfunctions, then it can have serious consequences.

Questions (Page 168)
		If the window is open then close it
		Detect temperature
		If the temperature is greater than 28°C switch off the heater, buzz and open the window
		Detect temperature
		If the temperature is less than 24°C then switch on the heater, buzz and close the window
		Go back to the first detect temperature instruction to repeat

Questions (Page 169)
(a)		See chapter
(b)	(i) (ii)	More accurate than a human. You could easily miss a vehicle. Cheaper than employing people. Can note the times the readings are made so that graphs may be drawn. Less tedious. Data collected manually would still need to be entered into the computer. Any statistical graph (except a pie chart) could be drawn (e.g. cars per minute at different times).

Things To Do (page 169)
1(a)		The angle turned through could be the wrong way and it could be in the wrong direction. Commands could be in the wrong order or a command could be missing. The steps in the Forward or Back command could be wrong.
(b)		Needs a sensor which is able to sense and object blocking it's path and then produces a signal to tell it to stop.

2(a)		The sensor measures the temperature and if it is too cold the microprocessor turns on the heater. If it is too hot it turns the heater off. It only does this if the water covers the water sensor. If the water sensor is not covered than the valve opens to let the cold water in. The arrangement where data signals are fed back to the microprocessor which makes the decision about what to do, is called feedback.
(b)	(i) (ii)	Between the temperature sensor and the microprocessor. (n.b. the water sensor only detects whether the water is present or not and therefore produces a digital signal). Temperature is a continuous quantity with an infinite number of possible values and is therefore an analogue signal. The sensor also produces an analogue signal which needs to be converted to a digital one before the microprocessor can understand it.

3(a)		Closed-loop
(b)		Open-loop
(c)		A closed-loop traffic light system would keep the same timed sequence regardless of traffic conditions. An open-loop system uses sensors to detect the traffic and will alter the sequencing accordingly.

4(a)		Electrical activity of the heart, temperature, respiration etc.
(b)		Fewer nurses are needed. Computer is alert at all times. Only needs to alert the doctors if the quantities measured fall outside certain pre-described values.
(c)		Explaining medical treatment to patients. Giving news to relatives.

5(a)		Light sensors are used. When the light beam is broken, the microprocessor knows that the car is passing. When it detects the light again, it knows that the car has passed.
(b)		Wait until sensor activates Print tickets Wait until ticket sensor activates Open barrier Switch red off and green on Wait until second sensor shows the car has gone Switch red on and green off Close barrier
(c)		Date and time of entry
(d)		Punched holes and magnetic strip

6	(i) (ii)	Heat Daily 10 years Heat 5 minutes 1 hour

7		See answer to the questions (there is a similar question on page 166).

8(a)		Temperature
(b)		The sensor measures the temperature and relays a signal back to the chip which decides whether the temperature is low enough. This is called feedback. If the temperature is not low enough, the compressor is turned on. Once the temperature is low enough, the chip sends back a signal to switch the compressor off. The whole process is repeated.
(c)		Measure temperature. If the temperature is not low enough then turn compressor on. Measure temperature. If the temperature is too low, turn off the compressor. Go back to the first instruction.
(d)		Usually a switch, positioned near the hinge, closes when the door is opened.
(e)		If the fridge door is open for longer than a certain period such as 5 minutes, an alarm will sound.

Examination Questions (page 343)
1(a)		A robot is a device that can be programmed to do a particular task.
(b)		Any two from: Produces the same high quality work all the time; Doesn't take tea breaks or holidays; Cheaper than employing people; No problems with trade unions.
(c)		Handling the radioactive fuel rods inside a nuclear reactor. Obtaining rock samples from distant planets (not the Moon).

2(a)		Direct data capture
(b)	(i) (ii)	Heat sensor To measure the temperature automatically.
(c)	(i) (ii)	Every half hour (i.e. 48 readings) or every hour (24 readings). Need enough readings to see the fine detail of temperature change.
(d)		Best presented graphically in the form of a line graph (or bar chart).

3(a)		FILL MOVE FILL MOVE MOVE FILL MOVE
(b)		(i)The computer has no way of knowing whether there is a bottle under the hopper since there is no sensor to detect the hopper. (ii) A touch sensor detects that the bottle has moved into the correct position. (iii) It senses to see if there is a bottle present and when the bottle is in a suitable position a signal is sent back to the computer. If the bottle isn't in the correct position the computer instructs the conveyer belt to move so that it is.
(c)		Real time should be ticked.
(d)		Running costs will be lower (less wages); More likely to have the correct amount in each bottle. Leads to greater unemployment. The initial costs of the equipment are high.

4(a)		Any two from: To protect the computer or provide additional power; To convert the analogue signals to digital ones and vice versa. To enable the sensors to be connected to the computer.
(b)		Analogue signals vary continuously whereas digital signals may only be one value or another (e.g. 0 or 1).
(c)		The data from the spreadsheet is input into a spreadsheet and the spreadsheet graph/chart function is used to plot a graph.

5(a)		Sensors are used to take measurements of the conditions at set intervals (every half hour, every hour etc.) and these signals are sent to the computer where they stored and compared with the ideal conditions.
(b)		The signal from a particular sensor is compared with the ideal value stored by the computer. If it is not in the range of the ideal value then the computer will send a signal to turn a device on which will alter the conditions until the conditions lie in the range again. This process takes place continuously.
(c)		The data could be stored in a database or spreadsheet file and then the graphing/charting facilities of these packages could be used to produce graphs/charts to present the values.
(d)		Finding the mean values. Finding the number of readings taken that were outside the allowable range.

6		Measurements from the sensor are constantly taken and fed back to the computer where they are compared with a range of values. If the measurement lies outside the range then a signal will be sent to turn the pump on thus adding more air. Once the signal from the sensor lies inside the range the computer will send a signal to turn the pump off. This process of monitoring/feedback takes place continuously.

7		An infrared beam is emitted which bounces off objects in front of the buggy. When an obstacle is detected, the buggy can take another route.

8		Position/proximity sensors to sense an obstacle. Memory to remember the route. Some processing ability to know to erase those instructions of the route that were incorrect.