Chapitre 3 • Acoustic logging

Approaches that are typically applied in deep exploration geophysics, combining different seismic and logging methods, can be technically adapted for certain geotechnical or hydrogeological surveys or some site characterizations in the framework of seismic hazard studies. Currently it is entirely feasible to implement this type of geophysical surveying if the situation requires. After reviewing the current state of knowledge regarding borehole measurements of subsurface shear velocities applied to the geotechnical field, this book illustrates the feasibility of carrying out vertical seismic profiles (VSPs) and logs in this field. This approach also illustrates the value of combining velocity measurements of formations provided by borehole seismic tools (VSP) and acoustic (sonic) tools. An innovative example of the application of borehole seismic and logging methods is then presented in the case study of a relatively near-surface (from 20 to 130 m) karst carbonate aquifer. It shows how a multi-scale description of the reservoir can be carried out by integrating the information provided by different 3D-THR surface seismic methods, full waveform acoustic logging, VSP with hydrophones, borehole optical televiewer and flow measurements. In this book the authors provide readers with guidelines to carry out these operations, in terms of acquisitions as well as processing and interpretation. Thus, users will be able to draw inspiration to continue transferring petroleum techniques and other innovative methods for use in near-surface studies

Chapitre 2 • Well seismic surveying

Approaches that are typically applied in deep exploration geophysics, combining different seismic and logging methods, can be technically adapted for certain geotechnical or hydrogeological surveys or some site characterizations in the framework of seismic hazard studies. Currently it is entirely feasible to implement this type of geophysical surveying if the situation requires. After reviewing the current state of knowledge regarding borehole measurements of subsurface shear velocities applied to the geotechnical field, this book illustrates the feasibility of carrying out vertical seismic profiles (VSPs) and logs in this field. This approach also illustrates the value of combining velocity measurements of formations provided by borehole seismic tools (VSP) and acoustic (sonic) tools. An innovative example of the application of borehole seismic and logging methods is then presented in the case study of a relatively near-surface (from 20 to 130 m) karst carbonate aquifer. It shows how a multi-scale description of the reservoir can be carried out by integrating the information provided by different 3D-THR surface seismic methods, full waveform acoustic logging, VSP with hydrophones, borehole optical televiewer and flow measurements. In this book the authors provide readers with guidelines to carry out these operations, in terms of acquisitions as well as processing and interpretation. Thus, users will be able to draw inspiration to continue transferring petroleum techniques and other innovative methods for use in near-surface studies

Transition from Knudsen to molecular diffusion in activity of absorbing irregular interfaces

We investigate through molecular dynamics the transition from Knudsen to molecular diffusion transport towards 2d absorbing interfaces with irregular geometry. Our results indicate that the length of the active zone decreases continuously with density from the Knudsen to the molecular diffusion regime. In the limit where molecular diffusion dominates, we find that this length approaches a constant value of the order of the system size, in agreement with theoretical predictions for Laplacian transport in irregular geometries. Finally, we show that all these features can be qualitatively described in terms of a simple random-walk model of the diffusion process.Comment: 4 pages, 4 figure

Economic impact of port activity : a disaggregate analysis. The case of Antwerp

The economic impact of the port sector is usually measured at an aggregate level by indicators such as value added, employment and investment. This paper tries to define the economic relevance for the regional as well as for the national economy at a disaggregate level. It attempts to identify, quantify and locate the mutual relationships between the various port players themselves and between them and other Belgian industries. Due to a lack of information foreign trade is only tackled very briefly but the method outlined in this paper can be used to measure the national effects of changes in port activity at a detailed level. A sector analysis is made by compiling a regional (regional as geographically opposed to national, not to be mistaken for the Belgian Regions Brussels, Flanders and Wallonia) input-output table, resorting to microeconomic data: a bottom-up approach. The main customers and suppliers of the port's key players or stakeholders are identified. A geographical analysis can also be carried out by using data at a disaggregate level. Each customer or supplier can be located by means of their postcode. In so doing, the economic impact of the port is quantified, both functionally and geographically. In the case of the port of Antwerp, the results show important links between freight forwarders and agents. The geographical analysis suggests the existence of major agglomerating effects in and around the port of Antwerp, referred to as a major transhipment location point. Key words: port economics, regional input-output table, sector analysis, geographical analysis.port economics, regional input-output table, sector analysis, geographical analysis

Hydrodynamics and Local Turbulent Mixing of Submerged, Parallel Liquid Jets: Experiments and CFD Simulations

The hydrodynamics and local turbulent mixing of parallel multiple liquid jets, submerged in liquid, were investigated by means of experiments and computational fluid dynamics (CFD). A renormalization group (RNG) k-ε turbulence model was used to simulate the flow field. The model was validated experimentally by particle image velocimetry (PIV) measurements. In the converging region adjacent to the nozzle exits, the recirculation region disappears, and there is only ambient fluid entrainment. Different jet arrays were compared to evaluate the effects of the jet spatial arrangement on the hydrodynamics and mixing performance. A shorter mixing length in the merging region suggests that mixing is more efficient in the triple-jet system than in other jet systems. Compared with the jet Reynolds number, the jet spacing plays a more significant role in determining the critical mixing regions, while the linear relationship between them is more sensitive than that for multiple parallel plane jets

Speech Characteristics and Intelligibility in Adults with Mild and Moderate Intellectual Disabilities

PURPOSE: Adults with intellectual disabilities (ID) often show reduced speech intelligibility, which affects their social interaction skills. This study aims to establish the main predictors of this reduced intelligibility in order to ultimately optimise management. METHOD: Spontaneous speech and picture naming tasks were recorded in 36 adults with mild or moderate ID. Twenty-five naïve listeners rated the intelligibility of the spontaneous speech samples. Performance on the picture-naming task was analysed by means of a phonological error analysis based on expert transcriptions. RESULTS: The transcription analyses showed that the phonemic and syllabic inventories of the speakers were complete. However, multiple errors at the phonemic and syllabic level were found. The frequencies of specific types of errors were related to intelligibility and quality ratings. CONCLUSIONS: The development of the phonemic and syllabic repertoire appears to be completed in adults with mild-to-moderate ID. The charted speech difficulties can be interpreted to indicate speech motor control and planning difficulties. These findings may aid the development of diagnostic tests and speech therapies aimed at improving speech intelligibility in this specific group

Precisely Engineered Supported Gold Clusters as a Stable Catalyst for Propylene Epoxidation

Designing a stable and selective catalyst with high H2 utilisation is of pivotal importance for the direct gas-phase epoxidation of propylene. This work describes a facile one-pot methodology to synthesise ligand-stabilised sub-nanometre gold clusters immobilised onto a zeolitic support (TS-1) to engineer a stable Au/TS-1 catalyst. A non-thermal O2 plasma technique is used for the quick removal of ligands with limited increase in particle size. Compared to untreated Au/TS-1 catalysts prepared using the deposition precipitation method, the synthesised catalyst exhibits improved catalytic performance, including 10 times longer lifetime (>20 days), increased PO selectivity and hydrogen efficiency in direct gas phase epoxidation. The structure-stability relationship of the catalyst is illustrated using multiple characterisation techniques, such as XPS, 31P MAS NMR, DR-UV/VIS, HRTEM and TGA. It is hypothesised that the ligands play a guardian role in stabilising the Au particle size, which is vital in this reaction. This strategy is a promising approach towards designing a more stable heterogeneous catalyst

Billiards in a general domain with random reflections

We study stochastic billiards on general tables: a particle moves according to its constant velocity inside some domain ${\mathcal D} \subset {\mathbb R}^d$ until it hits the boundary and bounces randomly inside according to some reflection law. We assume that the boundary of the domain is locally Lipschitz and almost everywhere continuously differentiable. The angle of the outgoing velocity with the inner normal vector has a specified, absolutely continuous density. We construct the discrete time and the continuous time processes recording the sequence of hitting points on the boundary and the pair location/velocity. We mainly focus on the case of bounded domains. Then, we prove exponential ergodicity of these two Markov processes, we study their invariant distribution and their normal (Gaussian) fluctuations. Of particular interest is the case of the cosine reflection law: the stationary distributions for the two processes are uniform in this case, the discrete time chain is reversible though the continuous time process is quasi-reversible. Also in this case, we give a natural construction of a chord "picked at random" in ${\mathcal D}$, and we study the angle of intersection of the process with a $(d-1)$-dimensional manifold contained in ${\mathcal D}$.Comment: 50 pages, 10 figures; To appear in: Archive for Rational Mechanics and Analysis; corrected Theorem 2.8 (induced chords in nonconvex subdomains

Gold nanoparticles with tailored size through ligand modification for catalytic applications

The active sites of catalysts can be tuned by using appropriate organic moieties. Here, we describe a facile approach to synthesise gold nanoparticles (AuNPs) using various Au(I) precursors. The core size of these AuNPs can be precisely tailored by varying the steric hindrance imposed by bound ligands. An interesting relationship is deduced that correlates the steric hindrance around the metal to the final size of the nanoparticles. The synthesised AuNPs are immobilised onto TS-1 zeolite (Au/TS-1) with minimal change in the final size of the AuNPs. The catalytic performance of Au/TS-1 catalyst is evaluated for the direct gas phase epoxidation of propylene with hydrogen and oxygen, an environmentally friendly route to produce propylene oxide. The results indicate that smaller AuNPs exhibit enhanced catalytic activity and selectivity. Furthermore, this synthetic approach is beneficial when tailored synthesis of gold nanoparticles of specific sizes is required