Coupled thermo-hydro-mechanical behaviour of a deep clay

An experimental study on Ypresian clays –one of the potential deep formations in Belgium for the geological disposal of heat-emitting radioactive waste– was undertaken to systematically study its thermal properties and coupled hydro-mechanical response during fast heating pulse tests. An accurate characterisation of the thermal properties is required for assessing the near-field perturbations around disposal galleries that the sedimentary host rock formation will undergo. A new experimental cell adapted to apply the high in situ stresses and with thermal flux sensors was used to directly measure the thermal conductivity at different sample orientations (heat flux orthogonal and parallel to bedding planes). A clear influence of the degree of saturation – despite being close to saturation – and anisotropic features on thermal conductivity have been detected. The study was complemented by performing fast heating pulse tests under constant volume on a new and fully-instrumented axisymmetric cell. The cell allowed recording the pore pressure build-up and dissipation along a heating pulse and under water-undrained conditions.Postprint (published version

Foldable all-textile cavity-backed slot antennas for personal UWB localization

An all-textile multimoded cavity-backed slot antenna has been designed and fabricated for body-worn impulse radio ultra-wideband (IR-UWB) operation in the 3,744-4,742.4 MHz frequency band, thereby covering Channels 2 and 3 of the IEEE 802.15.4a standard. Its light weight, mechanical flexibility, and small footprint of 35 mm x 56 mm facilitate integration into textile for radio communication equipment for first aid responders, personal locator beacons, and equipment for localization and medical monitoring of children or the elderly. The antenna features a stable radiation pattern and reflection coefficient in diverse operating conditions such as in free space, when subject to diverse bending radii and when deployed on the torso or upper right arm of a test person. The high isolation toward the wearer's body originates from the antenna's hemispherical radiation pattern with a -3 dB beamwidth of 120 degrees and a front-to-back ratio higher than 11 dB over the entire band. Moreover, the antenna exhibits a measured maximum gain higher than 6.3 dBi and a radiation efficiency over 75%. In addition, orientation-specific pulse distortion introduced by the antenna element is analyzed by means of the System Fidelity Factor (SFF). The SFF of the communication link between two instances of this antenna is higher than 94% for all directions within the antenna's -3 dB beamwidth. This easily wearable and deployable antenna is suitable to support IR-UWB localization with an accuracy in the order of 5 cm

Een ftanietrijke mesolithische vindplaats te Meeuwen Monnikswijer

Dit rapport werd ingediend bij het agentschap samen met een aantal afzonderlijke digitale bijlagen. Een aantal van deze bijlagen zijn niet inbegrepen in dit pdf document en zijn niet online beschikbaar. Sommige bijlagen (grondplannen, fotos, spoorbeschrijvingen, enz.) kunnen van belang zijn voor een betere lezing en interpretatie van dit rapport. Indien u deze bijlagen wenst te raadplegen kan u daarvoor contact opnemen met: [email protected]

Isopropyl alcohol recovery by heteroazeotropic batch distillation

Solvent recovery is becoming a major issue in the pharmaceutical and specialty chemical industries. Solvent recovery by conventional batch distillation is limited by the frequent presence of azeotropes in the used solvent mixtures. Most distillation processes for the separation of azeotropic or difficult zeotropic mixtures involve the addition of an entrainer (homogeneous and heterogeneous azeotropic distillation or extractive distillation). In this study the recovery of IPA (isopropyl alcohol) from an industrial waste stream (IPA/water mixture) was studied by conventional batch distillation and heteroazeotropic batch distillation, using cyclohexane as entrainer. First the ternary IPA/water/cyclohexane azeotrope (boiling temperature of 64.1 °C), then the binary IPA/cyclohexane azeotrope (boiling temperature of 69.3°C) and finally pure IPA was distilled. 99.96 mass% IPA could be obtained by heteroazeotropic distillation, using cyclohexane as entrainer. By using this procedure the IPA recovery is 97.6%, which is high compared to the conventional distillation techniques. The binary azeotrope could be reused in a subsequent heteroazeotropic batch distillation

Influence of the wind profile on the initiation of convection in mountainous terrain

A number of days with small precipitating convective cells were investigated using weather radars during the COPS (Convective and Orographically-induced Precipitation Study) field campaign in the region of the Vosges and the Rhine Valley in Central Europe. Depending on the weather situation, two distinct mechanisms could be identified for the initiation of convection.On some days, cells were initiated over the ridge of theVosges, whereas on other days cells were initiated in the lee of the Vosges. The initiation of convection appeared to be concentrated in a few favourable locations. Using the Froude number, it was possible to describe the two distinct mechanisms. When the Froude number was low, the flow was diverted around the Vosges and thermally driven convergence at the ridge initiated convection, whereas when the Froude number was high, the flow passed through mountain gaps and then converged on the lee side with the flow in the Rhine Valley. The convergence on the lee side was enhanced at locations where the outflows through valleys converged. Low Froude numbers were accompanied by weak winds varying with height,whereas high Froude numbers were observed during situations with stronger southwesterly winds increasing with height

Studying the thermal conductivity of a deep Eocene clay formation: direct measurements vs back-analysis results

An experimental study on Ypresian clays–one of the potential deep and sedimentary clay formations in Belgium for the geological disposal of heat-emitting radioactive waste–has been undertaken to systematically study its thermal conductivity using different experimental techniques. As a first step, a new experimental setup with heat flux measurement has been used and careful pre-conditioning protocols have been followed to directly measure this thermal property. The aim of these pre-conditioning tests has been ensuring a very high degree of saturation and the closure of fissures / gaps along bedding planes before the thermal tests are run under low stress conditions. Thermal tests have shown to be particularly sensitive when the thermal conductivity is determined along a direction orthogonal to these bedding planes. The study is then complemented by using a constant volume heating cell, in which heating pulse tests have been carried out under fully saturated conditions that have been ensured with a high water back-pressure. Numerical models have been used to interpret this pulse test, to exploit all the information provided by temperature measurements and to back-analyse the thermal conductivity. Direct thermal conductivity data with the improved pre-conditioning protocol allowed obtaining results consistent with the values reported when using back-analysis in the constant volume cell. The article discusses the importance of restoring full saturation conditions, particularly on retrieval of deep sedimentary clays, which may undergo opening of fissures along bedding planes that may affect the correct determination of the thermal conductivity.Peer ReviewedPostprint (author's final draft