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.

A continuous flow packed bed photocatalytic reactor for the destruction of 2-methylisoborneol and geosmin utilising pelletised TiO2

Taste and odour compounds, especially geosmin (GSM) and 2-methylisoborneol (2-MIB), cause major problems in both drinking water and aquaculture industries world-wide. Aquaculture in particular has experienced significant financial losses due to the accumulation of taint compounds prior to harvest resulting in consumer rejection. UV-TiO2 photocatalysis has been demonstrated to remove GSM and 2-MIB at laboratory scale but the development of a continuous flow reactor suitable for use in water treatment has not been investigated. In this study, a pilot packed bed photocatalytic reactor was developed and evaluated for water treatment with both laboratory and naturally tainted samples. A significant reduction of both 2-MIB and GSM was achieved in both trials using the packed bed reactor unit. With the laboratory spiked water (100ngL-1 of each compound added prior to treatment), detectable levels were reduced by up to 97% after a single pass through the unit. When the reactor was used to treat water in a fish farm where both compounds were being produced in situ (2-MIB: 19ngL-1 and GSM: 14ngL-1) a reduction of almost 90% in taint compounds was achieved. These very encouraging promising results demonstrate the potential of this UV-TiO2 photocatalytic reactor for water treatment in fish rearing systems and other applications.

ALEA: Fine-Grain Energy Profiling with Basic Block Sampling

Energy efficiency is an essential requirement for all contemporary computing systems. We thus need tools to measure the energy consumption of computing systems and to understand how workloads affect it. Significant recent research effort has targeted direct power measurements on production computing systems using on-board sensors or external instruments. These direct methods have in turn guided studies of software techniques to reduce energy consumption via workload allocation and scaling. Unfortunately, direct energy measurements are hampered by the low power sampling frequency of power sensors. The coarse granularity of power sensing limits our understanding of how power is allocated in systems and our ability to optimize energy efficiency via workload allocation.
We present ALEA, a tool to measure power and energy consumption at the granularity of basic blocks, using a probabilistic approach. ALEA provides fine-grained energy profiling via sta- tistical sampling, which overcomes the limitations of power sens- ing instruments. Compared to state-of-the-art energy measurement tools, ALEA provides finer granularity without sacrificing accuracy. ALEA achieves low overhead energy measurements with mean error rates between 1.4% and 3.5% in 14 sequential and paral- lel benchmarks tested on both Intel and ARM platforms. The sampling method caps execution time overhead at approximately 1%. ALEA is thus suitable for online energy monitoring and optimization. Finally, ALEA is a user-space tool with a portable, machine-independent sampling method. We demonstrate two use cases of ALEA, where we reduce the energy consumption of a k-means computational kernel by 37% and an ocean modelling code by 33%, compared to high-performance execution baselines, by varying the power optimization strategy between basic blocks.

Cybersecurity Test-Bed for IEC 61850 based Smart Substations

With the development and deployment of IEC 61850 based smart substations, cybersecurity vulnerabilities of supervisory control and data acquisition (SCADA) systems are increasingly emerging. In response to the emergence of cybersecurity vulnerabilities in smart substations, a test-bed is indispensable to enable cybersecurity experimentation. In this paper, a comprehensive and realistic cyber-physical test-bed has been built to investigate potential cybersecurity vulnerabilities and the impact of cyber-attacks on IEC 61850 based smart substations. This test-bed is close to a real production type environment, and has the ability to carry out end-to-end testing of cyber-attacks and physical consequences. A fuzz testing approach is proposed for detecting IEC 61850 based intelligent electronic devices (IEDs) and validated in the proposed test-bed.

The VINEYARD Approach: Versatile, Integrated, Accelerator-Based, Heterogeneous Data Centres.

Emerging web applications like cloud computing, Big Data and social networks have created the need for powerful centres hosting hundreds of thousands of servers. Currently, the data centres are based on general purpose processors that provide high flexibility buts lack the energy efficiency of customized accelerators. VINEYARD aims to develop an integrated platform for energy-efficient data centres based on new servers with novel, coarse-grain and fine-grain, programmable hardware accelerators. It will, also, build a high-level programming framework for allowing end-users to seamlessly utilize these accelerators in heterogeneous computing systems by employing typical data-centre programming frameworks (e.g. MapReduce, Storm, Spark, etc.). This programming framework will, further, allow the hardware accelerators to be swapped in and out of the heterogeneous infrastructure so as to offer high flexibility and energy efficiency. VINEYARD will foster the expansion of the soft-IP core industry, currently limited in the embedded systems, to the data-centre market. VINEYARD plans to demonstrate the advantages of its approach in three real use-cases (a) a bio-informatics application for high-accuracy brain modeling, (b) two critical financial applications, and (c) a big-data analysis application.

Evaluation of thermochemical biomass conversion in fluidized bed

Dado o aumento acelerado dos preços dos combustíveis fósseis e as incertezas quanto à sua disponibilidade futura, tem surgido um novo interesse nas tecnologias da biomassa aplicadas à produção de calor, eletricidade ou combustíveis sintéticos. Não obstante, para a conversão termoquímica de uma partícula de biomassa sólida concorrem fenómenos bastante complexos que levam, em primeiro lugar, à secagem do combustível, depois à pirólise e finalmente à combustão ou gasificação propriamente ditas. Uma descrição relativamente incompleta de alguns desses estágios de conversão constitui ainda um obstáculo ao desenvolvimento das tecnologias que importa ultrapassar. Em particular, a presença de elevados conteúdos de matéria volátil na biomassa põe em evidência o interesse prático do estudo da pirólise. A importância da pirólise durante a combustão de biomassa foi evidenciada neste trabalho através de ensaios realizados num reator piloto de leito fluidizado borbulhante. Verificou-se que o processo ocorre em grande parte à superfície do leito com chamas de difusão devido à libertação de voláteis, o que dificulta o controlo da temperatura do reator acima do leito. No caso da gasificação de biomassa a pirólise pode inclusivamente determinar a eficiência química do processo. Isso foi mostrado neste trabalho durante ensaios de gasificação num reator de leito fluidizado de 2MWth, onde um novo método de medição permitiu fechar o balanço de massa ao gasificador e monitorizar o grau de conversão da biomassa. A partir destes resultados tornou-se clara a necessidade de descrever adequadamente a pirólise de biomassa com vista ao projeto e controlo dos processos. Em aplicações de engenharia há particular interesse na estequiometria e propriedades dos principais produtos pirolíticos. Neste trabalho procurou-se responder a esta necessidade, inicialmente através da estruturação de dados bibliográficos sobre rendimentos de carbonizado, líquidos pirolíticos e gases, assim como composições elementares e poderes caloríficos. O resultado traduziu-se num conjunto de parâmetros empíricos de interesse prático que permitiram elucidar o comportamento geral da pirólise de biomassa numa gama ampla de condições operatórias. Para além disso, propôs-se um modelo empírico para a composição dos voláteis que pode ser integrado em modelos compreensivos de reatores desde que os parâmetros usados sejam adequados ao combustível ensaiado. Esta abordagem despoletou um conjunto de ensaios de pirólise com várias biomassas, lenhina e celulose, e temperaturas entre os 600 e 975ºC. Elevadas taxas de aquecimento do combustível foram alcançadas em reatores laboratoriais de leito fluidizado borbulhante e leito fixo, ao passo que um sistema termo-gravimétrico permitiu estudar o efeito de taxas de aquecimento mais baixas. Os resultados mostram que, em condições típicas de processos de combustão e gasificação, a quantidade de voláteis libertada da biomassa é pouco influenciada pela temperatura do reator mas varia bastante entre combustíveis. Uma análise mais aprofundada deste assunto permitiu mostrar que o rendimento de carbonizado está intimamente relacionado com o rácio O/C do combustível original, sendo proposto um modelo simples para descrever esta relação. Embora a quantidade total de voláteis libertada seja estabelecida pela composição da biomassa, a respetiva composição química depende bastante da temperatura do reator. Rendimentos de espécies condensáveis (água e espécies orgânicas), CO2 e hidrocarbonetos leves descrevem um máximo relativamente à temperatura para dar lugar a CO e H2 às temperaturas mais altas. Não obstante, em certas gamas de temperatura, os rendimentos de algumas das principais espécies gasosas (e.g. CO, H2, CH4) estão bem correlacionados entre si, o que permitiu desenvolver modelos empíricos que minimizam o efeito das condições operatórias e, ao mesmo tempo, realçam o efeito do combustível na composição do gás. Em suma, os ensaios de pirólise realizados neste trabalho permitiram constatar que a estequiometria da pirólise de biomassa se relaciona de várias formas com a composição elementar do combustível original o que levanta várias possibilidades para a avaliação e projeto de processos de combustão e gasificação de biomassa.

Valorization of solid wastes from cellulose and paper industry

This thesis reports in detail studies of industrial solid wastes valorization as alternative raw materials. All tested wastes are classified as non-hazardous and are generated in the pulp and paper process, including primary sludge, dregs, grits, lime mud and bottom ash (this generated in a process that occurs in parallel to the production of cellulose, whose aim is the production of energy to supply the plant through the combustion of forest biomass in fluidized bed). A detailed general characterization was performed at each waste and according to their characteristics, they were selected some applications in materials with potential use, specifically in Fibercement, Bituminous Mixture for regularization layer and industrial mortars (rendering mortars and cementitious-adhesive). After decided to application each waste was specifically tested to proceed the setting up of formulations containing different content of waste in replacement of the raw conventional material. As an isolated case, the bottom ash was tested not only as an alternative raw material for construction materials, but also it was tested for its use in fluidized bed in which the waste is generated as raw material. Both dregs and bottom ash had undergone special treatment to make possible to obtain a better quality of waste in order do not compromise the final product characteristics and process. The dregs were tested in bituminous mixtures as received and also washed (on the laboratory scale to remove soluble salts) and bottom ash were washed and screened in industrial scale (for removal of soluble salts, especially chlorides and coarse fraction particles elimination - particles larger than 1 mm size). The remaining residues form used in such as received avoiding additional costs. The results indicated potential and some limitations for each application to the use of these wastes as alternative raw material, but in some cases, the benefits in relation to valorization overlap with its limitations in both aspects, environmental and economic.

Seasonal and storm induced morphological variations at praia de Faro, península do Ancão, southern Portugal

Dissertação de Mestrado, Estudos Marinhos e Costeiros, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2009

Hydrodynamic and sediment fluxes through the inlets of the Ria Formosa

Tese de dout., Ciências do Mar, da Terra e do Ambiente (Ciências do Mar-Oceanografia Física), Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

Coastal storm snow event : November 20-22, 2006 open-file report

This report describes climatologically, the snow storm that occurred from November 20-22, 2006.

Feature Engineering in Fine-Grained Image Classification

Thesis (Ph.D.)--University of Washington, 2013

Quantifying Submerged Fluvial Topography Using Hyperspatial Resolution UAS Imagery and Structure From Motion Photogrammetry.

Quantifying the topography of rivers and their associated bedforms has been a fundamental concern of fluvial geomorphology for decades. Such data, acquired at high temporal and spatial resolutions, are increasingly in demand for process-oriented investigations of flow hydraulics, sediment dynamics and in-stream habitat. In these riverine environments, the most challenging region for topographic measurement is the wetted, submerged channel. Generally, dry bed topography and submerged bathymetry are measured using different methods and technology. This adds to the costs, logistical challenges and data processing requirements of comprehensive river surveys. However, some technologies are capable of measuring the submerged topography. Through-water photogrammetry and bathymetric LiDAR are capable of reasonably accurate measurements of channel beds in clear water. Whilst the cost of bathymetric LiDAR remains high and its resolution relatively coarse, the recent developments in photogrammetry using Structure from Motion (SfM) algorithms promise a fundamental shift in the accessibility of topographic data for a wide range of settings. Here we present results demonstrating the potential of so called SfM-photogrammetry for quantifying both exposed and submerged fluvial topography at the mesohabitat scale. We show that imagery acquired from a rotary-winged Unmanned Aerial System (UAS) can be processed in order to produce digital elevation models (DEMs) with hyperspatial resolutions (c. 0.02 m) for two different river systems over channel lengths of 50-100 m. Errors in submerged areas range from 0.016 m to 0.089 m, which can be reduced to between 0.008 m and 0.053 m with the application of a simple refraction correction. This work therefore demonstrates the potential of UAS platforms and SfM-photogrammetry as a single technique for surveying fluvial topography at the mesoscale (defined as lengths of channel from c.10 m to a few hundred metres). This article is protected by copyright. All rights reserved.

A Wireless Mesh Network NS-3 Simulation Model: Implementation and Performance Comparison With a Real Test-Bed

Wireless mesh networks present an attractive communication solution for various research and industrial projects. However, in many cases, the appropriate preliminary calculations which allow predicting the network behavior have to be made before the actual deployment. For such purposes, network simulation environments emulating the real network operation are often used. Within this paper, a behavior comparison of real wireless mesh network (based on 802.11s amendment) and the simulated one has been performed. The main objective of this work is to measure performance parameters of a real 802.11s wireless mesh network (average UDP throughput and average one-way delay) and compare the derived results with characteristics of a simulated wireless mesh network created with the NS-3 network simulation tool. Then, the results from both networks are compared and the corresponding conclusion is made. The corresponding results were derived from simulation model and real-worldtest-bed, showing that the behavior of both networks is similar. It confirms that the NS-3 simulation model is accurate and can be used in further research studies.

Development of remote monitoring process tools for biomass fired bubbling fluidized bed boilers

Remote monitoring of a power boiler allows the supplying company to make sure that equipment is used as supposed to and gives a good chance for process optimization. This improves co-operation between the supplier and the customer and creates an aura of trust that helps securing future contracts. Remote monitoring is already in use with recovery boilers but the goal is to expand especially to biomass-fired BFB-boilers. To make remote monitoring possible, data has to be measured reliably on site and the link between the power plant and supplying company’s server has to work reliably. Data can be gathered either with the supplier’s sensors or with measurements originally installed in the power plant if the plant in question is not originally built by the supplying company. Main goal in remote monitoring is process optimization and avoiding unnecessary accidents. This can be achieved for instance by following the efficiency curves and fouling in different parts of the process and comparing them to past values. The final amount of calculations depends on the amount of data gathered. Sudden changes in efficiency or fouling require further notice and in such a case it’s important that dialogue toward the power plant in question also works.