The hydraulics and resulting bed scour within the vicinity of Submerged Single Span Arch Bridges

As a consequence of climate change there is now a more frequent occurrence of extreme rainfall events where, with higher rates of urbanisation, the built environment has become increasingly affected by flooding.. This is of particular importance in relation to the stability of bridge structures that span rivers and canals etc. In November 2009, the UK and Ireland were subjected to extraordinarily severe weather conditions for several days. The rainfall was logged as the highest level of rainfall ever recorded within the UK, and as a direct consequence, unprecedented flooding occurred in Cumbria. This flooding led to the collapse of three road bridges which were generally 19th century masonry arch bridges, with relatively shallow foundations. In the UK, knowledge of the combined effect of bridge scouring and inundation has been not been particularly widely studied. Research carried out by Hamill et al [1] considered the hydraulic analysis of single arch bridges under flood conditions, but no consideration was given towards the likely damage to these structures due to scouring. Prior to this, Bierry and Delleur [2] produced a classic paper in predicting the discharge downstream of an inundated arch, focussing on predicting afflux as opposed to bridge scour. Further work on backwater effects was carried out by Martin-Vide & Prio [3] in semi-circular arch bridges. Both pressurized and free-surface flows at the bridge were investigated. Flows on a mobile bed in clear-water conditions were compared to those with a rigid bed, but no predictive equation for scour under pressurised conditions was considered. This paper will present initial findings from an experimental investigation into the effects of surcharged flow and subsequent scour within the vicinity of single span arch bridges. Velocities profiles will be shown within the vicinity of the arch, in addition to the depth of clear water scour, for a series of flows and model spans. The data will be presented, where results will be correlated to the most recent predictive equations that are proposed.

Field testing a full-scale tidal turbine Part 2: In-line Wake Effects

Recent research has shown that higher ambient turbulence leads to better wake recovery, so turbines could be installed in closer proximity in real tidal flows than might be assumed from typical towing tank tests that do not take into account turbulent inflow conditions. The standard tools to assess flow velocities in field conditions are Doppler based sonar devices, such as Acoustic Doppler Profilers (ADPs) or Acoustic Doppler Velocimeters (ADVs). The use of these devices poses some challenges when assessing the wake of a tidal turbine. While ADPs allow the three-dimensional measurement of a velocity profile over a distance, the data is calculated as a mean of three diverging beams and with low temporal resolution. ADVs can measure with higher sampling frequency but only at a single point in the flow. During the MaRINET testing of the SCHOTTELSIT turbine at the QUB tidal test site in Portaferry, Northern Ireland, ADP and ADV measurements were successfully tested.Two methods were employed for measuring the wake: firstly, with a rigidly mounted ADP and secondly, with a submerged ADV which was streamed behind the turbine. This paper presents the experimental set-up and results and discusses limitations and challenges of the two methods used.

The determination of optimal processing conditions for PLA and PLA/CaCO3 in twin screw extrusion using DoE and multivariate analysis

Biodegradable polymers, such as PLA (Polylactide), come from renewable resources like corn starch and if disposed of correctly, degrade and become harmless to the ecosystem making them attractive alternatives to petroleum based polymers. PLA in particular is used in a variety of applications including medical devices, food packaging and waste disposal packaging. However, the industry faces challenges in melt processing of PLA due to its poor thermal stability which is influenced by processing temperatures and shearing.
Identification and control of suitable processing conditions is extremely challenging, usually relying on trial and error, and often sensitive to batch to batch variations. Off-line assessment in a lab environment can result in high scrap rates, long lead times and lengthy and expensive process development. Scrap rates are typically in the region of 25-30% for medical grade PLA costing between €2000-€5000/kg.
Additives are used to enhance material properties such as mechanical properties and may also have a therapeutic role in the case of bioresorbable medical devices, for example the release of calcium from orthopaedic implants such as fixation screws promotes healing. Additives can also reduce the costs involved as less of the polymer resin is required.
This study investigates the scope for monitoring, modelling and optimising processing conditions for twin screw extrusion of PLA and PLA w/calcium carbonate to achieve desired material properties. A DAQ system has been constructed to gather data from a bespoke measurement die comprising melt temperature; pressure drop along the length of the die; and UV-Vis spectral data which is shown to correlate to filler dispersion. Trials were carried out under a range of processing conditions using a Design of Experiments approach and samples were tested for mechanical properties, degradation rate and the release rate of calcium. Relationships between recorded process data and material characterisation results are explored.

In the Shadows of the Old Town: Thomas Anna and 19th-century Glasgow

In 1858, a volume entitled Midnight Scenes and Social Photographs – being sketches of life in the streets, wynds and dens of the city of Glasgow was published under the pseudonym of ‘Shadow’ by Alexander Brown, a Glaswegian flâneur and reformer. Its frontispiece is an etching which depicts a theatre-like proscenium arch whose curtains have been withdrawn to reveal to the audience all the poverty, destitution and disorder that one was likely to find after dark in the insalubrious quarters of the city. At the extreme left-hand side, partly obscured by the curtain a silhouetted figure stands behind an unwieldy camera perched on a tripod. Distinctly unaffected by the mêlée, an arm is calmly raised and a finger precisely arched in the moment before the shutter is clicked and the scene committed to record. The volume, however, relies exclusively on textual descriptions to evoke the underside of the city and contains no photographs at all. Instead, the use of the word photograph in the title can be understood as a metaphor for detached scientific objectivity, a quality much celebrated by nineteenth-century reformers and investigators of social ills. As it happened, a decade after Shadow disappeared into the labyrinthine back-lands of Old Town Glasgow, he was followed there by a real photographer. In 1868, Thomas Annan was commissioned by the City Improvements Trust to take photographs of the Old Town in its last moments of existence before it was pulled down under a series of legislative acts. But perhaps paradoxically, given Shadow’s faith in the analytical properties of photography, Annan’s work seems to refute much of the material contained in Midnight Scenes and other similar tracts. Instead of the dens, shebeens, labyrinths and rowdy crowds described by Shadow, Annan’s depictions of the Old Town convey a static, calm environment, one which is often sparsely inhabited by a curious but apparently orderly population.

Taking account of the sensational tendencies of many reformists’ texts, this paper investigates the discrepancies between the two representations, focussing in particular on the constraints which operated on Annan during his commission. It argues that Annan’s compositions – which became very influential on other 19th century photographers of everyday life such as John Thomson or Jacob Riis – far from being dispassionate analytical works, emerged as a result of a matrix of factors which included: photographic and artistic precedents; Annan’s own predilections as a photographer; technological limitations; the nature of the commission from the City Improvements Trust and political climate in which it was given; the medieval urban fabric in which he had to operate; and, perhaps, most importantly, the identity of the Old Towns inhabitants themselves.

Does final demand for energy in Portugal exhibit long memory

In this paper, we measure the degree of fractional integration in final energy demand in Portugal using an ARFIMA model with and without adjustments for seasonality. We consider aggregate energy demand as well as final demand for petroleum, electricity, coal, and natural gas. Our findings suggest the presence of long memory in all of the energy demand variables, that the series are stationary, although the mean reversion process will be slower than in the typical short run processes. These results have important implications for the design of energy policies. The effects of temporary policy shocks on final energy demand will tend to disappear slowly. This means that even transitory shocks have long lasting effects. Given the temporary nature of these effects, however, permanent effects require permanent policies. This is unlike what would be suggested by the more standard but much more limited unit root approach, which would incorrectly indicate that even transitory policies would have permanent effects.

Vertebrate diversity in the Bussaco Mountain and surrounding areas

A biodiversidade é fundamental para o funcionamento dos ecossistemas e, além do seu valor intrínseco, fornece bens e serviços essenciais ao Homem. É consensual que as reservas naturais, por si só, não conseguirão preservar a biodiversidade de modo a que seja travada a perda de espécies que vem acontecendo a ritmos sem precedente. Assim, compreender os padrões de distribuição das espécies à escala regional ou sub-regional, ainda que em territórios não classificados, é crucial para o estabelecimento de políticas de gestão que visem a conservação da biodiversidade. O principal objectivo deste trabalho centrou-se na descrição e compreensão dos padrões de riqueza específica, distribuição e abundância de Vertebrados face aos diversos habitats que constituem a área de estudo. Constituíram, assim, objecto de estudo os anfíbios, aves, morcegos, micromamíferos e mamíferos de médio porte. A Serra do Bussaco e áreas envolventes encontram-se dominadas por vastas extensões de monocultura de Pinus pinaster e Eucalyptus globulus e por terrenos agrícolas. A Mata Nacional do Bussaco, bosque extremamente diverso, é outro importante elemento de paisagem. Pretendeu-se então analisar o efeito das práticas silvícolas actuais e da intensificação da agricultura sobre a biodiversidade, averiguando a importância de cada tipo de habitat para os Vertebrados em geral, e para algumas classes em particular. De entre os terrenos agrícolas, é bastante claro que a agricultura tradicional, com a sua típica complexidade e disponibilidade de água, constitui um habitat muito importante para a maioria dos Vertebrados, tendo também apresentado o maior valor conservacionista. No que respeita aos habitats florestais, o bosque misto apresentou consistentemente maior riqueza específica e diversidade, afirmando-se como o habitat preferido para a maioria das espécies e aquele com maior valor conservacionista. Do ponto de vista da conservação, as monoculturas, especialmente as da uma espécie exótica, revelaram-se habitats relativamente pobres. No entanto, estas conclusões referem-se às tendências gerais, sendo que taxa particulares respondem de forma diferente, atendendo aos seus requisitos específicos. A informação recolhida fornece bases essenciais para a construção de linhas de orientação que visem a integração das actividades humanas com a manutenção da biodiversidade e respectivos serviços, presumivelmente com aplicação a outras áreas geográficas.

Compósitos CNTs/biocerâmico para a estimulação elétrica óssea in situ

The present thesis aims to develop a biocompatible and electroconductor bone graft containing carbon nanotubes (CNTs) that allows the in situ regeneration of bone cells by applying pulsed external electrical stimuli. The CNTs were produced by chemical vapor deposition (CVD) by a semi-continuous method with a yield of ~500 mg/day. The deposition parameters were optimised to obtain high pure CNTs ~99.96% with controlled morphologies, fundamental requisites for the biomedical application under study. The chemical functionalisation of CNTs was also optimised to maximise their processability and biocompatibility. The CNTs were functionalised by the Diels-Alder cycloaddition of 1,3-butadiene. The biological behaviour of the functionalised CNTs was evaluated in vitro with the osteoblastic cells line MG63 and in vivo, by subcutaneous implantation in rats. The materials did not induce an expressed inflammatory response, but the functionalised CNTs showed a superior in vitro and in vivo biocompatibility than the non-functionalised ones. Composites of ceramic matrix, of bioglass (Glass) and hydroxyapatite (HA), reinforced with carbon nanotubes (CNT/Glass/HA) were processed by a wet approach. The incorporation of just 4.4 vol% of CNTs allowed the increase of 10 orders of magnitude of the electrical conductivity of the matrix. In vitro studies with MG63 cells show that the CNT/Glass/HA composites guarantee the adhesion and proliferation of bone cells, and stimulate their phenotype expression, namely the alkaline phosphate (ALP). The interactions between the composite materials and the culture medium (α-MEM), under an applied electrical external field, were studied by scanning vibrating electrode technique. An increase of the culture medium electrical conductivity and the electrical field confinement in the presence of the conductive samples submerged in the medium was demonstrated. The in vitro electrical stimulation of MG63 cells on the conductive composites promotes the increase of the cell metabolic activity and DNA content by 130% and 60%, relatively to the non-stimulated condition, after only 3 days of daily stimulation of 15 μA for 15 min. Moreover, the osteoblastic gene expression for Runx2, osteocalcin (OC) and ALP was enhanced by 80%, 50% and 25%, after 5 days of stimulation. Instead, for dielectric materials, the stimulus delivering was less efficient, giving an equal or lower cellular response than the non-stimulated condition. The proposed electroconductive bone grafts offer exciting possibilities in bone regeneration strategies by delivering in situ electrical stimulus to cells and consequent control of the new bone tissue formation rate. It is expected that conductive smart biomaterials might turn the selective bone electrotherapy of clinical relevance by decreasing the postoperative healing times.

NMR in the characterization of heavy residual procedural streams

The main objective of this work was to monitor a set of physical-chemical properties of heavy oil procedural streams through nuclear magnetic resonance spectroscopy, in order to propose an analysis procedure and online data processing for process control. Different statistical methods which allow to relate the results obtained by nuclear magnetic resonance spectroscopy with the results obtained by the conventional standard methods during the characterization of the different streams, have been implemented in order to develop models for predicting these same properties. The real-time knowledge of these physical-chemical properties of petroleum fractions is very important for enhancing refinery operations, ensuring technically, economically and environmentally proper refinery operations. The first part of this work involved the determination of many physical-chemical properties, at Matosinhos refinery, by following some standard methods important to evaluate and characterize light vacuum gas oil, heavy vacuum gas oil and fuel oil fractions. Kinematic viscosity, density, sulfur content, flash point, carbon residue, P-value and atmospheric and vacuum distillations were the properties analysed. Besides the analysis by using the standard methods, the same samples were analysed by nuclear magnetic resonance spectroscopy. The second part of this work was related to the application of multivariate statistical methods, which correlate the physical-chemical properties with the quantitative information acquired by nuclear magnetic resonance spectroscopy. Several methods were applied, including principal component analysis, principal component regression, partial least squares and artificial neural networks. Principal component analysis was used to reduce the number of predictive variables and to transform them into new variables, the principal components. These principal components were used as inputs of the principal component regression and artificial neural networks models. For the partial least squares model, the original data was used as input. Taking into account the performance of the develop models, by analysing selected statistical performance indexes, it was possible to conclude that principal component regression lead to worse performances. When applying the partial least squares and artificial neural networks models better results were achieved. However, it was with the artificial neural networks model that better predictions were obtained for almost of the properties analysed. With reference to the results obtained, it was possible to conclude that nuclear magnetic resonance spectroscopy combined with multivariate statistical methods can be used to predict physical-chemical properties of petroleum fractions. It has been shown that this technique can be considered a potential alternative to the conventional standard methods having obtained very promising results.

Validation of a method for the analysis of volatile organic compounds in water

Dissertação de mestrado, Qualidade em Análises, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

Using non-invasive techniques to examine black bear (Ursus americanus) abundance in the North Cascades Ecosystem, Washington State

Thesis (Master's)--University of Washington, 2013

Power Law Behavior and Self-similarity in Modern Industrial Accidents

Advances in technology have produced more and more intricate industrial systems, such as nuclear power plants, chemical centers and petroleum platforms. Such complex plants exhibit multiple interactions among smaller units and human operators, rising potentially disastrous failure, which can propagate across subsystem boundaries. This paper analyzes industrial accident data-series in the perspective of statistical physics and dynamical systems. Global data is collected from the Emergency Events Database (EM-DAT) during the time period from year 1903 up to 2012. The statistical distributions of the number of fatalities caused by industrial accidents reveal Power Law (PL) behavior. We analyze the evolution of the PL parameters over time and observe a remarkable increment in the PL exponent during the last years. PL behavior allows prediction by extrapolation over a wide range of scales. In a complementary line of thought, we compare the data using appropriate indices and use different visualization techniques to correlate and to extract relationships among industrial accident events. This study contributes to better understand the complexity of modern industrial accidents and their ruling principles.