Experimental study of formwork tightness as a function of rheological properties of SCC

Several studies relating formwork pressure to rheology exist, however the relationship between rheology and leakage through formwork joints remains to be investigated. In practice, standard documents are used to define formwork tightness requirements, typically using a qualitative approach. To try bridge this gap in knowledge, we developed a test set-up to study tightness of formwork joints under pressure as a function of varying rheological properties. Coupled with standard rheology tests, this new test set-up provides means of linking flow rate, formwork pressure, flow area, and the rheological properties. The study seeks to provide insight on measurable governing parameters and thus inform formwork tightness requirements in a more quantifiable manner. This paper presents a test set-up designed to study the flow of fresh paste through small openings. It highlights a preliminary study on the pressure-driven flow of limestone paste through a bottom orifice in a cylindrical container. While this new device may not be directly representative of the actual conditions in formwork, it provides a good base for a fundamental study that can then be extrapolated to a more representative test operation. Preliminary results show a linear relationship between the flow rate and the applied pressure. The results also show that increasing the flow area by a factor of 2.33 had a higher impact than an increase in yield stress and viscosity by a factor of 2.54 and 3.80 respectively. However, more tests need to be carried out to obtain clear trends

Estimation of Large-Scale Multi-Rate Systems ⋆

model predictive control and estimation of large-scal

A rolling-horizon quadratic-programming approach to the signal control problem in large-scale congested urban road networks

The paper investigates the efficiency of a recently developed signal control methodology, which offers a computationally feasible technique for real-time network-wide signal control in large-scale urban traffic networks and is applicable also under congested traffic conditions. In this methodology, the traffic flow process is modeled by use of the store-and-forward modeling paradigm, and the problem of network-wide signal control (including all constraints) is formulated as a quadratic-programming problem that aims at minimizing and balancing the link queues so as to minimize the risk of queue spillback. For the application of the proposed methodology in real time, the corresponding optimization algorithm is embedded in a rolling-horizon (model-predictive) control scheme. The control strategy’s efficiency and real-time feasibility is demonstrated and compared with the Linear-Quadratic approach taken by the signal control strategy TUC (Traffic-responsive Urban Control) as well as with optimized fixed-control settings via their simulation-based application to the road network of the city centre of Chania, Greece, under a number of different demand scenarios. The comparative evaluation is based on various criteria and tools including the recently proposed fundamental diagram for urban network traffic

Formation of ultrathin Ni germanides : solid-phase reaction, morphology and texture

The solid-phase reaction of ultrathin (<= 10 nm) Ni films with different Ge substrates (single-crystalline (100), polycrystalline, and amorphous) was studied. As thickness goes down, thin film texture becomes a dominant factor in both the film's phase formation and morphological evolution. As a consequence, certain metastable microstructures are epitaxially stabilized on crystalline substrates, such as the epsilon-Ni5Ge3 phase or a strained NiGe crystal structure on the single-crystalline substrates. Similarly, the destabilizing effect of axiotaxial texture on the film's morphology becomes more pronounced as film thicknesses become smaller. These effects are contrasted by the evolution of germanide films on amorphous substrates, on which neither epitaxy nor axiotaxy can form, i.e. none of the (de) stabilizing effects of texture are observed. The crystallization of such amorphous substrates however, drives the film breakup

Nautical bottom sediment research: Sub report 11. Cohesive sediments dimensional analysis

The dimensional analysis technique was applied in order to determine possible relationships between the measured parameters in the STT and to identify possible inconsistencies in the measurements.The present dimensional analysis focuses only in the sedimentation and consolidation processes.Relationships between parameters could be used to identify inconsistencies for measured pore pressure, effective stresses and density values. Recommendations are suggested for sampling points and measuring methods

Wann werden Konflikte manifest? Politische Opportunitätsstrukturen für Proteste gegen Goldbergbau in Burkina Faso

Der aktuelle Bergbau-Boom geht weltweit mit Konflikten um ökologische Fragen, die Verteilung der Gewinne und Steuern, Menschenrechte, Landnutzungskonkurrenzen und territoriale Ansprüche, kollektive Identitäten entlang von Kategorien wie Indigenität, Ethnizität und Nationalität, kulturelle Repräsentation und Deutungshoheit in Entwicklungspolitik und diskursen einher. Der Artikel untersucht, unter welchen Bedingungen diese Konflikte, die dem Bergbau aufgrund seiner erheblichen sozialen und ökologischen Auswirkungen inhärent sind, manifest werden und eskalieren. Unter Rückgriff auf zwei Konzepte aus der contentious-politics-Forschung -politische Gelegenheitsstrukturen und Protestrepertoires- werden drei aktuelle Konflikte um den Goldbergbau in Burkina Faso analysiert, einem der Staaten in Subsahara-Afrika, in denen der extraktive Sektor gegenwärtig am schnellsten wächst. Ich stelle dar, welcher Protestrepertoires sich die jeweiligen Akteure bedienen und zeige, dass der Sturz des langjährigen Staatspräsidenten Blaise Compaoré Ende Oktober 2014 die zentrale Verschiebung in den politischen Gelegenheitsstrukturen darstellt, welche die Eskalation der Konflikte in allen drei Beispielen bedingte.All over the world, the recent boom in mining is accompanied by conflicts over the ecological impacts, distribution of rents and taxes, human rights, land use and territorial claims, collective identity related to indigeneity, ethnicity and citizenship, cultural representations, and the prerogative of interpretation regarding policies and discourses of development. This paper investigates under which conditions these conflicts, which are inherent to the mining sector because of its enormous social and ecological impacts, become manifest and escalate. Referring to two concepts from contentious politics research -political opportunity structures and repertoires of contention- three actual conflicts over gold mining in Burkina Faso are analysed. Burkina Faso is of the sub-Saharan countries where the extractive sector is quickly growing. The paper traces which repertoires of contention the respective actors use, and demonstrates that the overthrow of the long-standing President Blaise Compaoré in late October 2014 was the central political opportunity structure that, in all three cases, enabled the escalation of the local conflicts

Democratization in a passive dendritic tree : an analytical investigation

One way to achieve amplification of distal synaptic inputs on a dendritic tree is to scale the amplitude and/or duration of the synaptic conductance with its distance from the soma. This is an example of what is often referred to as “dendritic democracy”. Although well studied experimentally, to date this phenomenon has not been thoroughly explored from a mathematical perspective. In this paper we adopt a passive model of a dendritic tree with distributed excitatory synaptic conductances and analyze a number of key measures of democracy. In particular, via moment methods we derive laws for the transport, from synapse to soma, of strength, characteristic time, and dispersion. These laws lead immediately to synaptic scalings that overcome attenuation with distance. We follow this with a Neumann approximation of Green’s representation that readily produces the synaptic scaling that democratizes the peak somatic voltage response. Results are obtained for both idealized geometries and for the more realistic geometry of a rat CA1 pyramidal cell. For each measure of democratization we produce and contrast the synaptic scaling associated with treating the synapse as either a conductance change or a current injection. We find that our respective scalings agree up to a critical distance from the soma and we reveal how this critical distance decreases with decreasing branch radius