TU100-12B: EMA
1a)
A sensor network is the collective term for numerous, small, devices which are geographically spread, and have the ability to record specific details of the world around them. Each sensor may be able to detect, for example, temperature and gas levels. These sensors are interlinked, and reach a central aggregating controller, which can use their geographical spread to detect the start and growth of events.
Actuation refers to effecting real physical changes to the environment. A motor is a type of actuator which has the ability to move another object around; it makes the movement actual. Actuation is commonly the output stage of a system, because it can create an informational or productive response, such as lighting up, or changing the points of a rail system.
Smart dust, theoretically, is a type of sensor network which consists of many more, smaller, sensors than in a traditional network. Typically, these sensors would be around 1mm3 in volume and would coat the target area to provide a much finer resolution of input, by limiting the distance between nodes. This means that the controller can see changes propagate with greater precision.
Transceivers are small radio devices which can both transmit and receive signals, albeit not simultaneously. Such a device can be useful in sensor networks as it facilitates communication between the nodes and the controller. The sensors must report their current data, and in more advanced networks, the controller can transmit instructions to the sensors, and sometimes actuators.
The server is the central computer with the ability to communicate with many clients. It's role can include co-ordination, provision of instructions, and processing input from clients. In a sensor network, the many sensors are the clients, and the server will collect their results, and use the data in calculations which can inform a response to the readings.
1b)
We can assess the reliability of an academic paper in a number of ways. Something to identify early is whether the paper has verifiable claims; speculation which cannot be proven or disproven falls outside the realm of the scientific method and should not be relied upon. Contrastingly, the ideal is a paper which has seen rigorous, systematic peer review.
In the case of original research, the writer should lucidly be able to describe the way in which they have come to their conclusions, including their experimental methods and workings. Their empirical methods should be sound, and feature sufficiently large sample sizes which have been processed in a way which addresses bias appropriately.
Where an academic paper is derivative of one or more other works, it should clearly cite the sources of previous research. These references, when pursued, must transpire to be directly relevant to the statement which referenced them. A paper which makes unsupported claims is less deserving of trust, as is a paper which initially seems to be supported by a body of work but – in fact – has used dubiously related work in order to appear stronger. Additionally, the referenced works should themselves be analysed for their reliability.
The reputation of the author can be a helpful factor in determining reliability. However, credible first-time writers shouldn't be disadvantaged as a result. The presence of co-authors and others of good repute who will vouch for the work is useful here.
Lastly, one should investigate whether the writer has an ulterior motive, financial or otherwise. If the writer is invested in a technology which will be boosted by their research, then their work should be treated with extreme suspicion.
3a)
Program 1 is responsible for taking sensor readings, and posting them to an online RSS feed in a specific format. Every twenty seconds, it takes levels from Input A (designed for the light sensor), Input B (designed for the thermistor), and the SenseBoard microphone. Along with the time of the reading, these data are labelled, comma separated, and concatenated together. This combination of metrics allows RainforestTrackUK to monitor the passing of logging vehicles and the environmental disruption caused by logging. The consolidated readings are uploaded to the RSS feed.
Program 2 can read and process the RSS feed, in order to display easily readable information about the change in rainforest activity. Every twenty seconds, it downloads the most recent RSS feed item. It has a pseudo-function for pulling each datum out of the downloaded string, and does so for the time, tremor, volume, and temperature which were recorded. I decided to create a function-like piece of code for drawing variables out of the string, because it results in the code being more versatile and reusable.
With these isolated, it compares the tremor and volume to the last recorded instances, or to a pre-set baseline reading (if this is the first time). The program calculates whether there has been a change of 20% up or down in both of these metrics by querying whether the new level is greater than the previous reading multiplied by 1.2, or less than 0.8 times the previous. The “alert level” is commensurately increased or decreased, and this number is used to set the “costume” of the stage, defining its colour: green, amber, or red. If the alert level has changed since the last point, an arrow indicating up or down is also shown.
If the alert level remains in red for a further iteration, the MIDI synthesiser plays a 2-beat alarm pattern 20 times at 240 bpm (for a total running time of 10 seconds).
3b)
For sound levels:
Standard deviation: / 6.186014877Mean average: / 35.0827551
4ai)
60*60*0.05 = 180s
= 2 mins
4aii)
2705 mAh / 2.2 mA = 1229.545454
1229... × 60 × 60 = 4426363.63636364 s
= 4.43 ×106 s
4aii)
38ms = 0.038 s
435 bits = 54.375 bytes
= 0.054375 kilobytes
rate = data / time
= 0.054375 / 0.038
= 1.43 kbps
4b)
Energy harvesting refers to the use of readily available environmental sources to produce enough energy for low-consumption computers, such as sensors. This enables them to to operate without the constraints brought about by a limited power source, such as a battery[i]. The energy can be harvested from a diverse range of sources, and provides greater reliability and lower maintenance costs than fossil fuel cells. It may then be temporarily stored in a cell or capacitor[ii], so that a short lack of energy input does not result in downtime for the device. However, the fact that this cell does not need to be replaced in order to supply power is the main strength of energy harvesting sensors.
One example is the use of photovoltaic cells to convert incoming photon energy into electrical charge. Consequently, as long as the unit is receiving light energy, it remains powered. Sunlight is not in limited supply, so the longevity of the device is greatly extended. Modern PV cells work in a similar way to plants.
An alternative is the use of piezoelectric generation, which uses small movements to generate electrical current, for example the movement of the human body. This could be used to power Body Area Network devices[iii]. The piezoelectric effect depends on certain materials which generate current when expanded or contracted.
5)
Facebook allows an organisation to curate and maintain a “page”. This page has most of the features of a user, such as the ability to post textual, pictorial, and video statuses. These statuses are broadcast to all of the users who have “liked” your page. As a page, there is no way of reciprocating this contract. Users may comment on your statuses, and this discussion may require occasional moderation. In order to engage users, you should post news items which will interest them. Over-regular postings may annoy users. Users are able to break their “liking” contract.
On twitter, you may post 140 character “tweets” which can contain links to other media. Tweets are completely public by default, and anyone can “follow” your organisation and thereby receive everything you post. Tweets can be directed at one or more other users, and this will grant the tweet special attention in their twitter client, and can be used to respond to user queries posed to the organisation. You cannot stop people from creating tweets that mention the brand by its twitter tag, but you can reply in such a way that your reply appears alongside the original. Twitter can be used to post positive results from the organisation, and link to other topics of interest which your followers may enjoy.
A hosted forum requires committed moderators and administrators. It is the staff's responsibility to divide the forum into sensible sections and ensure that conversation remains civil. Forums require maintenance to keep discussion orderly, by consolidating similar topics and encouraging adherence to a set of rules. You have power to decide who becomes and who remains a member of the forum. Only admitted members may post. You can begin and maintain discussions about topics close to the aims of the organisation, and also poll members to find out their feelings on certain issues.
1/4TU100 EMAStephen Griffiths (sg9533)
[i]Energy Harvesting, [Online],
Available: [17/09/12]
[ii]Freeland R. (2011) Energy Harvesting: A practical reality for wireless sensing, [Online],
Available: [17/09/12]
[iii]Starner T. (1996) Human-powered wearable computing, [Online],
Available: [17/09/12]