(By: NWO)
In the week of 20–24 November 2017, 50 young physicists gathered at the Lorentz Center in Leiden to tackle a number of practical problems involving physics. They had been invited by two of NWO's domains: Science (ENW) and Applied and Engineering Sciences (TTW).

Image: PWI2017-group, photo by Anita van Stel

On the first day of the workshop, five companies each presented a practical problem. The PhD students and postdoctoral researchers then split up into five groups to work on those cases. On the final day of the workshop – after a week filled with discussing the case, reading the relevant literature, creating models and making calculations – each group of researchers presented their results in a plenary session. A jury of experts led by Rudolf Sprik (University of Amsterdam) evaluated those presentations in terms of their quality, the originality of the solution and the potential for a practical follow-up. In the end, it was the team that tackled the case from Boskalis who won the honours.

Problems in physics
The cases were provided by the Research & Development departments at the different companies. To qualify, each case had to meet two important criteria: 1) the problem had to be solvable (in part) by means of physics and 2) the space of one week had to be enough time to tackle the subject. Shell, Koppert Biological Systems, Boskalis, the National Data Warehouse for Traffic Information (NDW) and Sioux CCM presented the following cases:

Shell: carbon-based nanoparticles
As a dense energy carrier or fuel, hydrogen can play an important role in the transition to a carbon-free energy world. Methane pyrolysis yields hydrogen plus solid carbon, but carbon is often seen as an unwelcome by-product. Nevertheless, certain forms of carbon such as diamonds, graphene and carbon nanotubes are valuable and useful for a variety of applications. Current processes that produce solid carbon as a by-product yield a range of carbon particle sizes and morphologies. The question is: How can Shell separate a batch of carbonaceous nanoparticles on the basis of size, shape and morphology? Which physical properties of the various forms and sizes of particles will be useful? And how can the solution be scaled up?

Koppert: How can the temperature in moth cages be kept at 29ºC?
Koppert breeds insects and mites for biological pest control in horticulture and also bumble bees for pollination. Moths are reared on industrial scale at Koppert. The eggs of the moths are used as food for the 'useful' insects which are subsequently used for biocontrol in greenhouses. The larvae of the moths are kept on trays in a special cage. The optimal temperature in the unit is 29ºC. The moths themselves produce heat and CO₂, but if the temperature exceeds 35ºC, the system will "explode" and the larvae will start to leave the cages. To prevent this from happening, a climate-control system blasts air at 14ºC into the unit. The question is: How can the system be set up to ensure an optimally and uniform temperature controlled laminar flow over the plates? At the same time Koppert wants to achieve a reduction in energy consumption.

Boskalis: Detection instrument for divers
Boskalis is a global leader in the field of dredging and maritime services. One of Boskalis' activities concerns the salvaging of vessels and the removal of wrecks. That often involves removing oil from the bunkers of ships that have sunk. Such an operation is normally done by divers, who drill a hole into the hull in order to pump out the oil by means of a hose. The bunker often also contains water below the oil and air above it, with the differences in density between the substances keeping them separate. To ensure that all the oil can be pumped out, the hose must be connected at the level of the oil. That level is currently determined by consulting the vessel's design drawings, the current position and the geometry of the sunken vessel, as well as the estimated volume of oil in its bunkers. Boskalis has a strong need for an instrument that can determine which type of substance is located behind the hull of a ship without actually penetrating the hull. In short: a detection system that can be used by a diver at a depth of 100 metres.

National Data Warehouse for Traffic Information (NDW): Information about the reliability of travel time
The unreliability of traffic-information services that results from unpredictable variations in travel times leads to ineffective traffic situations, which in turn result in more pollution and unnecessary traffic-safety risks. The NDW would like to support their data providers and road authorities with detailed information about the unpredictable variations in travel time. What is needed is an effective and clear measure of travel time reliability per segment.

Sioux CCM: How can the loss of accuracy of laser illumination systems due to speckles be reduced?

Sioux CCM, is an innovation partner for the international high-tech industry. The company's core competences are mechanical construction principles, machine dynamics, motion control and optical design. One problem Sioux CCM faces is that the application of lasers in vision applications is often frustrated by speckles due to the coherent character of the source of laser light. What is more, in an application that creates a 3D-map of the teeth in a patient's mouth using structured light by means of a diffractive optical element (DOE), the speckles result in an inaccurate position measurement.

The participating researchers visited the companies concerned and made their own small-scale models in their respective rooms at the Lorentz Center. Each team approached their problem from different perspectives, using calculations and theories from physics. The solutions presented went down well with the representatives from the various companies.

Jeroen van Schelt from Koppert's Research & Development Entomology Department was enthusiastic about the researchers' results: "We were impressed by their smart, analytical approach to our problem. By means of an infrared camera and a smoke machine they came up with a good analysis of the strong and weak points in our rear system. In addition to presenting a whole bunch of creative ideas, such as the application of turbulence slits in the unit, they also recommended a less labour-intensive way of cleaning the trays."

Hans Kuppens, a system architect at Sioux CCM, was equally enthusiastic about the results of the team that had worked on the problem his company had provided: "In an extremely short period of time they managed to come up with two cost-effective solutions. Using a simple setup and a systematic approach, they managed to grasp the problem of the diffractive optical element and to come up with their own superluminescent diode (SLD). In one word: Tremendous! We can move forward with the solutions they presented."

Afbeelding: PWI Winnaars, foto Anita van Stel

The young researchers were practically unstoppable during the week at the Lorentz Center. Post-doc Adam Taylor and PhD student Sander Blok were part of the group that dealt with the problem that Sioux CCM presented. Blok didn't see it as an obstacle that he was one of the few in his group who lacked a background in optics: "I was able to give my knowledge of fundamental physics free rein. It was super fun to work as part of team on a clearly defined assignment. It also taught me something about how companies look at such problems. I might even decide to work in the industry once I've finished my PhD research."

The winning team, which tackled the problem presented by Boskalis, stood out from the others thanks to their original experiment: with candles and two bowls filled with liquid and gel, respectively, they tested for acoustic differences and viscosity. They studied echography and heat conduction, calculated the amplitude of lamb waves and microgravity, and had discussions with experts from Boskalis about the specifications and material properties of ships, such as thickness and surface of the steel from which ship hulls are made. They advised a concrete solution that can be used by divers. Roeland Neelissen from Boskalis congratulated the group with the results they achieved through an efficient combination of literature research and experiments.

At the end of this edition of Physics with Industry, the enthusiastic consensus among the participating researchers and companies was that NWO should hold such a week of workshops again in 2019. NWO expressed its gratitude to the Lorentz Center for its hospitality.