The detection of hydrogen in a fast, efficient and accurate way is vital for its safe handling in industrial processes and in its use as an energy carrier. Thin film metal hydrides are able to probe the hydrogen pressure, often relying on a change of the optical properties of a sensing layer comprised of palladium and alloys thereof. Apart from hysteresis, these palladium-based thin films suffer from a limited operating range. Here, we study the optical and structural properties of palladium capped hafnium and tantalum thin films. Both tantalum and hafnium thin films offer a stable and hysteresis-free optical response to hydrogen over a much larger pressure range than palladium-based films. Remarkably, the hydrogen content in both cases proves to be linear with the optical signal. In a wider perspective, these results illustrate that palladium-capped transition metals provide ample opportunities to design optical hydrogen sensors with desired properties.

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Vibrotactile wearable devices are a non-intrusive and inexpensive means to provide haptic feedback directly on the user’s skin. These devices utilize one or multiple vibrotactile actuators to generate vibrations across the skin and into the tissue. Combining these vibrations in amplitude can create the illusion of a funneled sensation on the skin at another location than at the actual sites of stimulation. This allows for the placement of virtual actuators on the skin, such that fewer actuators need to be deployed. However, the illusion does not take into account that the waves originating from the actuator attenuate and disperse due to the viscoelastic properties of the skin. We hypothesize that this diffusion of the elastic energy in the skin is affecting the perception of this illusion. Therefore, if we correct for the wave propagation speed, and temporally focus the stimulation, we hypothesized that the specificity of the stimulation on the skin could be drastically improved. In this paper, a novel technique, which is named the inverse filter technique, was introduced that enables to focus the amplitude, frequency and phase of vibrations to one location while cancelling them at the remaining nearby positions. We developed a wearable device for the volar surface of the forearm on which we could independently control arbitrary waveforms at any position between a set of four physical actuators. A human-subject study found that the performance in terms of localization confidence was improved significantly, whereas the precision and accuracy of the task did not improve compared to when we did not correct for the wave attenuation and dispersion. These results show that focusing waves towards a target location has a direct influence on our confidence of localizing vibrotactile stimuli on the arm. Therefore, we anticipate that our findings can benefit industries int Biorefineries are considered an integral part in the transition to sustainable bio-based economies as they can convert renewable biological resources into various bio-based products, while co-products are recycled and energy is produced out of the residuals. In this thesis, it is suggested to apply this biorefinery concept to revive the sugar industry of Jamaica, where currently only raw sugar is produced. For this, the development of a conceptual process design itself and the feasibility of the implementation is studied as the entire chain of utilizing biomass is influenced by both technical, environmental, social and economic aspects. With the Technological Innovation System (TIS) framework, the information obtained during the fieldwork about how (new) technologies function in the Jamaican agricultural industry are translated into context-specific design constraints. Those design constraints are used in the development of the context-specific conceptual process design for the Jamaican sugar industry. Three scenarios of the proposed design including the material balances and financial viability are discussed. The "status-quo" scenario predicts the bankruptcy of some of the sugar factories due to the reduced possibility to sell raw sugar, which will also leave the farmers without income. The "engineering-view" scenario was found to fail due to the unrealistic assumptions that all the products can be sold, that the farming yields can be improved, and that the Jamaican sugar sector can be seen as one. In the "most-realistic" scenario, it is considered that the energy generation from bagasse covers the energy demand for the processes and that the amount of plantation white sugar, anhydrous bio-ethanol and bio-pellets annually produced from 30,000 hectares of sugarcane land are considered to be 100,000 tonnes, 51 million liters, and 80,600 tonnes, respectively. It is suggested that this "most-realistic" scenario is able to revive the Jamaican sugar industry and to support the establishment of the sustainable bio-based economy, however the financial viability of the project and the inclusiveness of the various actors have to be taken into account.erested in including localized vibrotactile feedback on the human body surface.