RadMote - Mobile Framework for Radiation Monitoring

I don't know how many times I've watched the Simpsons and seen Homer Simpson sitting in front of his Safety Command Console at the Springfield nuclear power plant snoozing and eating donuts, only to scream and panic while pushing buttons at random when a meltdown seems inevitable. He is the safety inspector and is supposed to keep a close watch to ensure that no accidents occur. Yet, so often we see Homer doze off, leave his post unmanned, or even replace himself for the day with a chicken, a manatee, a homeless man or even a brick to cover for him. He is the lowest ranking person at the plant, yet is tasked with one of the most critical jobs. If only it were so simple...

Nuclear energy generates more energy when compared to other available forms such as thermal, kinetic, etc. It is a power source that is seen in many countries around the world, but its correct and safe operation is essential for its surrounding population. Although Homer Simpson's portrayal of nuclear safety at the plant appears trivial, the exact opposite rings true.  Most nations utilizing nuclear power have special institutions overseeing and regulating nuclear safety. Globally, the International Atomic Energy Agency works for the safe and peaceful use of nuclear science, and in the United States, the Nuclear Regulatory Commission ensures the safety of nuclear plants and materials. Due to the extremely serious repercussions that a nuclear accident could provoke, safety measures are especially important in these power plants.

Researchers at Malaga University in Spain have developed a prototype system using Motes to monitor the environmental conditions around and inside a nuclear power plant, with a specific focus on radiation levels. Sensor nodes equipped with radiation sensors are to be deployed in fixed positions throughout the plant. The staff at the plant is to be equipped with mobile devices with higher capabilities such as PDAs to monitor radiation levels and other conditions. The system enables communication between PDAs which form a mobile ad-hoc wireless network and allows workers to monitor remote conditions in the plant. The motes deployed in the environment communicate wirelessly to gather and report information about physical phenomena that can be used to improve safety measures.

To set up the prototype system, researchers used Crossbow's popular MICAz Mote platform along with the MDA300/100 data acquisition boards which would allow the addition of a radiation sensor to the network. The Stargate gateway was used as a sink node to interconnect the Motes using the 802.15.4/ZigBee compliant standard and PDAs using the Wi-Fi (802.11b) standard. The high level of communication was done with the HP iPAQ hw6500 Mobile Messenger which provides GSM connectivity. The sensor nodes were deployed in fixed positions. Environmental sensed data flows through the network to the sink nodes (Stargate gateways). The PDAs get connected to any of the reachable gateways in order to subscribe to the service of receiving gathered data. PDAs are also connected with each other in an ad-hoc manner, this way if it is far from the wireless sensor network; it can ask for the networks conditions from its neighbors. The data is then displayed in a datagrid component on the PDA as the front-end application. Using sophisticated routing algorithms and connection protocols, the system is able to interconnect the wireless sensor network and mobile ad-hoc wireless network to provide the information quickly and easily to the workers at the plant.

The system's basic features are to display data on the PDAs in real-time from environmental conditions, to display the relative position of the sensor nodes either via localization algorithms or noting their fixed position, alarm generation and propagation to detect risk situations, and to interact with the central server to provide data to the PDA and database. The increased safety measures that a wireless sensor network can provide to monitor the environmental conditions in situations where security, reliability and autonomy are paramount would not only aid in detecting accidents but prevent them from ever occurring. Wouldn't Homer be relieved? D'oh!

Intelligent Wireless Asset Tracking of Packaged Gases

Asset tracking is basically defined as a system that enables one to track an asset using several technologies. Asset tracking is an essential part of many industries, in particular, those concerned with logistics, purchasing and manufacturing.

Gas cylinders are used in many different situations, such as in research, in industry, in healthcare, and even in the home. They are tanks or pressure vessels used to store gases at high pressure. The transportation and storage of gas cylinders is regulated by most governments. Due to the demand  for monitoring and tracking in such a wide variety of circumstances, there is an inevitable ambition of gas suppliers to improve the efficiency of their business. A prototype system developed at Liverpool John Moores University addresses a new idea to use Motes to provide a tracking system that would improve efficiency while also integrating sensors in order to monitor gas cylinders from a safety perspective.

The aim of the prototype system was to discover whether or not communication between motes was possible and reasonably reliable despite signal attenuation which would be caused by the metallic surroundings. This simulated asset tracking environment contained caged gas cylinders which were stored outdoors. Each of the cyclers used during testing has a MICA2 Mote securely attached to its collar via a nylon cable tie with each mote arranged randomly to create non-line of sight (NLOS) conditions. The antennas were in various orientations and touching the metal gas cylinders. The situation was setup as a worst case scenario for RF communications in this application.

The base gateway received the data from the network and would communicate the information to the computer which had stored the network addresses or node IDs of the motes which were arbitrarily associated with a particular type of gas (e.g. Nitrogen, Oxygen, etc.). In order to ensure reliable communication between the base station and the motes attached to the gas cylinders outside, an intermediate relay node was used - it was placed outdoors with a brick walled building between. The prototype system was successful in collecting data within such an environment. Users were able to determine which tags were active at any one time, communicate with individual tags via their unique node ID in order to trigger an event such as sounding the buzzer on board. This two-way communication allowed tags to be identified and provide sensory data.

This idea for an automated gas storage facility is to monitor the gas cylinders when they are in motion. The facility could be unmanned and treated as a location where the gas cylinders were picked up and dropped off. When entering the facility, motes could be interrogated to identify themselves (i.e. their contents, from where they were being returned, etc.). Each mote would not need to rely on a specific reader to send its data, but could communicate the data over the multi-hop mesh network. This would allow data on what the cylinders needed to be filled with, when, or for who to be sent quickly and efficiently to the warehouse. This type of data would prove advantageous to the end users as well to automatically trigger an order of new stock of the particular gas that had been used, etc. Primarily, It also helps with safety issues if interfacing some type of pressure sensor to monitor the contents and prevent a dangerous or explosive situation. Accelerometers could be used to determine the orientation of the cylinder and worn the user if it is stored incorrectly. The flexibility of the mote platform to interface with various sensors is greatly useful for such an application.

This capability to monitor and track assets intelligently will enable a more reliable and safe environment especially for critical applications such as the storage and transportation of packaged gases!