Low-cost and Energy-efficient Solutions for Multicomponent Distillation

Distillation accounts for 90-95% of all the separations on a chemical plant, and for about 3% of the world energy consumption. Even modest improvements to the process of distillation can have tremendous impact on the chemical economy world over. The goal of a major part of this thesis is to use process intensification methods to present, thoroughly investigate and systematically synthesize new processes for multicomponent separations which can serve as attractive candidates for distillation technology of tomorrow

Near-field scanning and propagation of correlated low-frequency radiated emissions

Electromagnetic radiation from complex printed circuit boards can occur over a broad frequency bandwidth, ranging from hundreds of MHz to tens of GHz. This is becoming a critical issue for assessment of EMC and interoperability as electronic components become more and more integrated. We use emissions from an enclosure with a single-slot aperture and equipped with operating electronics to exemplify and model such sources. Spatial correlation functions obtained from two-probe measurements are used both to characterise the source and to propagate the emissions. We examine emissions in the submicrowave frequency range, where evanescent decay dominates the measured correlation function at the distances measured. We find that an approximate, diffusion-like propagator describes the measured emissions well. A phase-space approach based on Wigner functions is exploited to develop this approximation and to provide enhanced understanding of the emissions

Nearfield acoustical holography – a Wigner function approach

We propose to use Wigner transformation methods as a tool for propagating measured acoustic signals from and towards a source region. We demonstrate the usefulness of the approach both for source reconstruction purposes and as a stable numerical simulation tool with build-in filtering mechanisms. The starting point is a statistical description of the sound field in terms of spatial correlation functions. Using the concept of Wigner transformation – a half Fourier transform method, the correlation function can be associated with a phase space distribution, thus introducing direction or momentum information. A corresponding free-field propagator for Wigner function distributions is derived and the ray-limit of this propagator is discussed. Acoustic data are acquired in an experiment using an ‘acoustical camera’; the sound pressure emanating from a vibrating rectangular plate is measured on a 32 × 32 microphone array in coincidence, making it possible to get correlated data with relatively high resolution. Measurements and simulations are compared at different heights above the source plane. It is demonstrated that the Wigner function approach provides a stable tool to propagate correlation data. It is furthermore suitable for nearfield holography where the sound field is propagated back to the plate surface. The directional components encoded in the Wigner function can be used to read off the distance between the source and measurement plane on sub-wavelength scales