Simplified ultrasonic damage detection in fluid filled pipes

The location and extent of damage in a pipe can be remotely determined from weld and internal damage reflections using a single acoustic emitter/sensor pair. The use of normalised reflections yields single numbers enabling long distance data collection techniques such as wireless hopping. The attenuation is twice as high for opposite inner and outer fluids (whether air and water, or water and air) as compared to identical inner and outer fluids. The absolute recorded signals in the water-filled pipe are attenuated by a factor two compared to the empty pipe. The axial length of detection is reduced by a half. The reduction of &gt;90% in sensors and the longer axial detection (&gt;10× current state-of- the-art- technology) means that permanent fixed sensor pairs for whole pipelines are on the horizon of possibility. The greatest advantage is envisioned in submersed pipelines.</p

Simplified ultrasonic damage detection in fluid filled pipes

The location and extent of damage in a pipe can be remotely determined from weld and internal damage reflections using a single acoustic emitter/sensor pair. The use of normalised reflections yields single numbers enabling long distance data collection techniques such as wireless hopping. The attenuation is twice as high for opposite inner and outer fluids (whether air and water, or water and air) as compared to identical inner and outer fluids. The absolute recorded signals in the water-filled pipe are attenuated by a factor two compared to the empty pipe. The axial length of detection is reduced by a half. The reduction of &gt;90% in sensors and the longer axial detection (&gt;10× current state-of- the-art- technology) means that permanent fixed sensor pairs for whole pipelines are on the horizon of possibility. The greatest advantage is envisioned in submersed pipelines.</p

Emergence and public administration: A literature review for the project 'A new synthesis in public administration'

This literature review explores the concept of emergence in public governance, and the need for building anticipative capacity in public organisations. The purpose of this review is to explore how public organisations can deal with issues that emerge in their environment. Emerging issues are characterised by a great deal of complexity and uncertainty, and therefore create challenges for static public governance arrangements. Dealing with emerging issues requires that organisations and systems build anticipative capacities. The literature review summarises recent but also less recent organisation theory focusing on organisational improvisation and on complex governance arrangements. This literature presents an alternative way of both analysing organisations and of organising beyond static and highly proceduralised or systemised conceptions. New organisational arrangements to cope with emergence sometimes appear counterintuitive, and they sometimes appear to defy the rules of economy, efficiency, democracy and the rule of law. As is evident from Bourgon’s ‘New Synthesis’ framework, an organisation or system that facilitates emergence needs to make a trade-off with other objectives. While such arrangements are good at anticipating change and at detecting trends, they come with challenges to the performance, compliance, and the resilience of the public sector

The Fractal Dimension of Projected Clouds

The interstellar medium seems to have an underlying fractal structure which can be characterized through its fractal dimension. However, interstellar clouds are observed as projected two-dimensional images, and the projection of a tri-dimensional fractal distorts its measured properties. Here we use simulated fractal clouds to study the relationship between the tri-dimensional fractal dimension (D_f) of modeled clouds and the dimension resulting from their projected images. We analyze different fractal dimension estimators: the correlation and mass dimensions of the clouds, and the perimeter-based dimension of their boundaries (D_per). We find the functional forms relating D_f with the projected fractal dimensions, as well as the dependence on the image resolution, which allow to estimatethe "real" D_f value of a cloud from its projection. The application of these results to Orion A indicates in a self-consistent way that 2.5 < D_f < 2.7 for this molecular cloud, a value higher than the result D_per+1 = 2.3 some times assumed in literature for interstellar clouds.Comment: 27 pages, 13 figures, 1 table. Accepted for publication in ApJ. Minor change

Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?

Article / Letter to editorInstituut Psychologie;Instituut Psychologie;Instituut Psychologie;Instituut Psychologi

Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?

Article / Letter to editorInstituut Psychologie;Instituut Psychologie;Instituut Psychologie;Instituut Psychologi

Dynamic testing of gifted and average-ability children's analogy problem solving: Does executive functioning play a role?

status: publishe