Wireless sensor networks are hot. In any application in which wires used to cause problems, autonomous and wireless sensors can be positioned. An example of a project Van Hoesel is involved with, is monitoring the water quality in the fragile ecology of the Great Barrier Reef without the need of an ‘intrusive’ infrastructure. But also for climate control in buildings and for monitoring industrial processes, wireless sensor networks have been introduced. The sensors exchange information and form ‘multi hop’ connections. Because they sometimes stay in place for years, the use of battery power must be kept to a minimum.
The sensors don’t just constantly transmit their data to a central server; that would cost far too much energy. Communication is expensive in terms of energy consumption, therefore intelligence is added locally to each sensor node: the sensors know when to transmit their data and when to pass data through, coming from neighbouring sensors. For this, they have to be ‘on speaking terms’, as Van Hoesel calls it. In this way, the network itself can carry out complex tasks.
He therefore designed a so-called Medium Access (MAC) protocol, based on self organization of the network. The sensors keep an eye on their neighbours and autonomously decide whether to start transmitting or not. This also holds for the neighbours next-door to the closest neighbours: in this way, Van Hoesel avoids conflicts in the network and keeps energy use to a minimum.
This approach can be further improved by introducing passive sensors in the network: they provide data but they don’t actively participate in the multi hop communication. Passive sensors use less energy and thus extend the lifetime of the network as a whole. As wireless networks in general can be vulnerable to attacks from the outside, Van Hoesel presents adequate countermeasures.
Lodewijk van Hoesel, who defended his PhD thesis ‘Sensors on speaking terms’ on June 21 is also the cofounder –together with Paul Havinga and Stefan Dulman- of Ambient Systems, a company specialized in wireless sensor networks. The young company recently was awarded the Dutch ICTRegie Award and the Van den Kroonenberg Award, an award of the University of Twente for young entrepreneurs. Ambient Systems started cooperation with the Australian Institute of Marine Science for monitoring the water quality around the Great Barrier Reef using wireless sensor networks.
Wiebe van der Veen | alfa
The role of Sodium for the Enhancement of Solar Cells
17.07.2018 | Max-Planck-Institut für Eisenforschung GmbH
Behavior-influencing policies are critical for mass market success of low carbon vehicles
17.07.2018 | International Institute for Applied Systems Analysis (IIASA)
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
18.07.2018 | Materials Sciences
18.07.2018 | Life Sciences
18.07.2018 | Health and Medicine