Statistics for Spatial Data.

The Social Psychology of Organizations.

Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

/pdf/climate-change-2007-the-physical-science-basis-1x93ttz9jt.pdf

Climate Change 2007: The Physical Science Basis.

Social Psychology of Organizations

The boundary layer equations for plane, incompressible, and steady flow are 

$$\matrix{ {u{{\partial u} \over {\partial x}} + v{{\partial u} \over {\partial y}} = - {1 \over \varrho }{{\partial p} \over {\partial x}} + v{{{\partial ^2}u} \over {\partial {y^2}}},} \cr {0 = {{\partial p} \over {\partial y}},} \cr {{{\partial u} \over {\partial x}} + {{\partial v} \over {\partial y}} = 0.} \cr }$$

Boundary Layer Theory

Operational decision-making for sewer asset management has hardly been empirically analysed, hampering the current challenge for cost-effectiveness in the urban drainage sector. This paper analyses how decisions for sewer replacement are actually made and to what extent complexity of the decision-making environment is addressed. Decision argumentation of 150 sewer replacement projects in the Netherlands was obtained by interviews. The decision process was analysed by the rational and streams model. The decision argumentation is a relatively wide variety of information sources, of which the majority is case-specific. Yet, decision-making does not rely purely on data analysis; it also includes negotiations between involved infrastructure managers. Then, replacement planning of a sewer asset manager depends on other public works. Consequently, individual cost-effectiveness as an evaluation criterion should be expanded to include group utility.

RESEARCH ARTICLE Decision-making for sewer asset management: Theory and practice

Surrogate modelling for simplification of a complex urban drainage model.

Effect of biochemical attack on the mechanical performance of used concrete sewer pipes

Urban runoff (re)mobilises solids present on the street surface and transport them to urban drainage systems. The solids reduce the hydraulic capacity of the drainage system due to sedimentation and on the quality of receiving water bodies due to discharges via outfalls and combined sewer overflows (CSOs) of solids and associated pollutants. To reduce these impacts, gully pots, the entry points of the drainage system, are typically equipped with a sand trap, which acts as a small settling tank to remove suspended solids. This study presents data obtained using Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) measurements in a scale 1:1 gully to quantify the relation between parameters such as the gully pot geometry, discharge, sand trap depth, and sediment bed level on the flow field and subsequently the settling and erosion processes. The results show that the dynamics of the morphology of the sediment bed influences the flow pattern and the removal efficiency in a significant manner, prohibiting the conceptualization of a gully pot as a completely mixed reactor. Resuspension is initiated by the combination of both high turbulent fluctuations and high mean flow, which is present when a substantial bed level is present. In case of low bed levels, the overlaying water protects the sediment bed from erosion.

Sediment Morphology and the Flow Velocity Field in a Gully Pot: An Experimental Study

Decision-making for sewer asset management is partially based on intuition and often lacks explicit argumentation, hampering decision transparency and reproducibility. It is unknown to what extent each information source is appreciated by decision makers. Further insight into this relative importance and into implicit factors, improves understanding of decision-making of sewer system managers. As such, a digital questionnaire (response ratio 43%), containing pairwise comparisons between ten relevant information sources, was sent to every municipality in the Netherlands to analyse the relative importance and assess whether a shared frame of reasoning is present. Thurstone’s law of comparative judgment was used for analysis, combined with several consistency tests. Results show that camera inspections were valued highest, while pipe age was considered least important. The respondents were pretty consistent per individual and also showed consistency as a group. This indicated a common framework of reasoning among the group. The feedback of the group showed, however, the respondents found it difficult to make general comparisons without having a context. This indicates decision-making in practice is more likely to be steered by other mechanisms than purely combining information sources.

https://repository.tudelft.nl/islandora/object/uuid%3A56a2e0a9-3bd4-4c3d-a2c9-ad48aba6d39c/datastream/OBJ/download

Francois Clemens

Papers

RESEARCH ARTICLE Decision-making for sewer asset management: Theory and practice

Surrogate modelling for simplification of a complex urban drainage model.

Effect of biochemical attack on the mechanical performance of used concrete sewer pipes

Sediment Morphology and the Flow Velocity Field in a Gully Pot: An Experimental Study

Value of Information for Sewer Replacement Decisions