Reducing inconsistencies in point observations of maximum flood inundation level

Flood simulation models and hazard maps are only as good as the underlying data against which they are calibrated and tested. However, extreme flood events are by definition rare, so the observational data of flood inundation extent are limited in both quality and quantity. The relative importance of these observational uncertainties has increased now that computing power and accurate lidar scans make it possible to run high-resolution 2D models to simulate floods in urban areas. However, the value of these simulations is limited by the uncertainty in the true extent of the flood. This paper addresses that challenge by analyzing a point dataset of maximum water extent from a flood event on the River Eden at Carlisle, United Kingdom, in January 2005. The observation dataset is based on a collection of wrack and water marks from two postevent surveys. A smoothing algorithm for identifying, quantifying, and reducing localized inconsistencies in the dataset is proposed and evaluated showing positive results. The proposed smoothing algorithm can be applied in order to improve flood inundation modeling assessment and the determination of risk zones on the floodplain.

The consequences of the culture aspect and the power distance in the execution of global strategies in multinational companies in Brazil

One of the challenges presented by the current conjecture in Global Companies is to recognize and understand that the culture and levels in structure of the Power Distance in Organizations in different countries contribute, significantly, toward the failure or success of their strategies. The alignment between the implementation and execution of new strategies for projects intended for the success of the Organization as a whole, rather than as an individual part thereof, is an important step towards reducing the impacts of Power Distance (PDI) on the success of business strategies. A position at odds with this understanding by Companies creates boundaries that increase organizational chasms, also taking into consideration relevant aspects such as, FSAs (Firm-Specific Advantages) and CSAs (Country-Specific Advantages). It is also important that the Organizations based in countries or regions of low Power Distance (PDI) between its individuals be more flexible and prepared to ask and to hear the suggestions from Regional and Local Offices. Thus, the purpose of this study is to highlight the elements of effective strategy implementation considering the relevant aspects at all levels of global corporate culture that justify the influences of power distance when implementing new strategies and also to minimize the impacts of this internal business relationship. This study also recognizes that other corporate and cultural aspects are relevant for the success of business strategies so consider, for instance, the lack of alignment between global and regional/local organizations, the need for competent leadership resources, as well as the challenges that indicate the distance between the hierarchical levels ─ Headquarters and Regional Office ─ as some of the various causes that prevent the successful execution of global strategies. Finally, we show that the execution of the strategy cannot be treated as a construction solely created by the Headquarters or by only one Board and that it needs to be understood as a system aimed at interacting with the surroundings.

Real power losses reduction and loading margin improvement via continuation method

This letter presents an alternative approach for reducing the total real power losses by using a continuation method. Results for two simple test systems and for the IEEE 57-bus system show that this procedure results in larger voltage stability margin. Besides, the reduction of real power losses obtained with this procedure leads to significant money savings and, simultaneously, to voltage profile improvement. Comparison between the solution of an optimal power flow and the proposed method shows that the latter can provide near optimal results and so, it can be a reasonable alternative to power system voltage stability enhancement.

Comparison of the photodynamic fungicidal efficacy of methylene blue, toluidine blue, malachite green and low-power laser irradiation alone against Candida albicans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparison of Reactive Power Support in Distribution Networks Provided by Capacitor Banks and Distributed Generators

This paper presents a comparison of reactive power support in distribution networks provided by switched Capacitor Banks (CBs) and Distributed Generators (DGs). Regarding switched CBs, a Tabu Search metaheuristic algorithm is developed to determine their optimal operation with the objective of reducing the power losses in the lines on the system, while meeting network constraints. on the other hand, the optimal operation of DGs is analyzed through an evolutionary Multi-Objective (MO) programming approach. The objectives of such approach are the minimization of power losses and operation cost of the DGs. The comparison of the reactive power support provided by switched CBs and DGs is carried out using a modified IEEE 34 bus distribution test system.

The effect of power-ultrasound on the pretreatment of acidified aqueous solutions of banana flower-stalk: Structural, chemical and statistical analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reducing the spurious oscillations in the lumped parameters model using low-pass filter

Voltages and currents in the transmission line are described by differential equations that are difficult to solve due soil and skin effect that has to be considered for accurate results, but it increases their complexity. Therefore there are some models to study the voltages and currents along in transmission line. The distributed parameters model that transforms the equations in time domain to the frequency domain and once the solutions are obtained, they are converted to time domain using the Inverse Laplace Transform using numerical methods. Another model is named lumped parameters model and it considers the transmission line represented by a pi-circuit cascade and the currents and voltages are described by state equations. In the simulations using the lumped parameters model, it can be observed the presence of spurious oscillations that are independent of the quantity of pi-circuits used and do not represent the real value of the transient. In this work will be projected a passive low-pass filter directly inserted in the lumped parameters model to reduce the spurious oscillations in the simulations, making this model more accurate and reliable for studying the electromagnetic transients in power systems.

Managing server energy and reducing operational cost for online service providers

The past decade has seen the energy consumption in servers and Internet Data Centers (IDCs) skyrocket. A recent survey estimated that the worldwide spending on servers and cooling have risen to above $30 billion and is likely to exceed spending on the new server hardware . The rapid rise in energy consumption has posted a serious threat to both energy resources and the environment, which makes green computing not only worthwhile but also necessary. This dissertation intends to tackle the challenges of both reducing the energy consumption of server systems and by reducing the cost for Online Service Providers (OSPs). Two distinct subsystems account for most of IDC’s power: the server system, which accounts for 56% of the total power consumption of an IDC, and the cooling and humidifcation systems, which accounts for about 30% of the total power consumption. The server system dominates the energy consumption of an IDC, and its power draw can vary drastically with data center utilization. In this dissertation, we propose three models to achieve energy effciency in web server clusters: an energy proportional model, an optimal server allocation and frequency adjustment strategy, and a constrained Markov model. The proposed models have combined Dynamic Voltage/Frequency Scaling (DV/FS) and Vary-On, Vary-off (VOVF) mechanisms that work together for more energy savings. Meanwhile, corresponding strategies are proposed to deal with the transition overheads. We further extend server energy management to the IDC’s costs management, helping the OSPs to conserve, manage their own electricity cost, and lower the carbon emissions. We have developed an optimal energy-aware load dispatching strategy that periodically maps more requests to the locations with lower electricity prices. A carbon emission limit is placed, and the volatility of the carbon offset market is also considered. Two energy effcient strategies are applied to the server system and the cooling system respectively. With the rapid development of cloud services, we also carry out research to reduce the server energy in cloud computing environments. In this work, we propose a new live virtual machine (VM) placement scheme that can effectively map VMs to Physical Machines (PMs) with substantial energy savings in a heterogeneous server cluster. A VM/PM mapping probability matrix is constructed, in which each VM request is assigned with a probability running on PMs. The VM/PM mapping probability matrix takes into account resource limitations, VM operation overheads, server reliability as well as energy effciency. The evolution of Internet Data Centers and the increasing demands of web services raise great challenges to improve the energy effciency of IDCs. We also express several potential areas for future research in each chapter.

IMPROVING STARTABILITY AND REDUCING EMISSIONS IN FLEXFUEL SPARK IGNITION DIRECT INJECTION VARIABLE CAM TIMING ENGINE

Experimental work and analysis was done to investigate engine startup robustness and emissions of a flex-fuel spark ignition (SI) direct injection (DI) engine. The vaporization and other characteristics of ethanol fuel blends present a challenge at engine startup. Strategies to reduce the enrichment requirements for the first engine startup cycle and emissions for the second and third fired cycle at 25°C ± 1°C engine and intake air temperature were investigated. Research work was conducted on a single cylinder SIDI engine with gasoline and E85 fuels, to study the effect on first fired cycle of engine startup. Piston configurations that included a compression ratio change (11 vs 15.5) and piston geometry change (flattop vs bowl) were tested, along with changes in intake cam timing (95,110,125) and fuel pressure (0.4 MPa vs 3 MPa). The goal was to replicate the engine speed, manifold pressure, fuel pressure and testing temperature from an engine startup trace for investigating the first fired cycle for the engine. Results showed bowl piston was able to enable lower equivalence ratio engine starts with gasoline fuel, while also showing lower IMEP at the same equivalence ratio compared to flat top piston. With E85, bowl piston showed reduced IMEP as compression ratio increased at the same equivalence ratio. A preference for constant intake valve timing across fuels seemed to indicate that flattop piston might be a good flex-fuel piston. Significant improvements were seen with higher CR bowl piston with high fuel pressure starts, but showed no improvement with low fuel pressures. Simulation work was conducted to analyze initial three cycles of engine startup in GT-POWER for the same set of hardware used in the experimentations. A steady state validated model was modified for startup conditions. The results of which allowed an understanding of the relative residual levels and IMEP at the test points in the cam phasing space. This allowed selecting additional test points that enable use of higher residual levels, eliminating those with smaller trapped mass incapable of producing required IMEP for proper engine turnover. The second phase of experimental testing results for 2nd and 3rd startup cycle revealed both E10 and E85 prefer the same SOI of 240°bTDC at second and third startup cycle for the flat top piston and high injection pressures. E85 fuel optimal cam timing for startup showed that it tolerates more residuals compared to E10 fuel. Higher internal residuals drives down the Ø requirement for both fuels up to their combustion stability limit, this is thought to be direct benefit to vaporization due to increased cycle start temperature. Benefits are shown for an advance IMOP and retarded EMOP strategy at engine startup. Overall the amount of residuals preferred by an engine for E10 fuel at startup is thought to be constant across engine speed, thus could enable easier selection of optimized cam positions across the startup speeds.

Bursting Boilers and the Federal Power Redux: The Evolution of Safety on the Western Rivers

Using newly constructed data series on explosions, deaths, and steamboat traffic, we examine econometrically the causes of increased safety in steamboat boilers in the nineteenth century. Although the law of 1852 (but not that of 1838) did have a dramatic initial effect in reducing explosions, that reduction came against the background not of a system out of control but of a system that from the beginning was steadily increasing boiler safety per person- mile. The role of the federal government in conducting and disseminating basic research on boiler technology may have been more significant for increased safety than its explicit regulatory efforts.

A Precharge-Absorbed DPL Logic for Reducing Early Propagation Effects on FPGA Implementations

In this paper, a new countermeasure against power and electromagnetic (EM) Side Channel Attacks (SCA) on FPGA implemented cryptographic algorithms is proposed. This structure mainly focuses on a critical vulnerability, Early Evaluation, also known as Early Propagation Effect (EPE), which exists in most conventional SCA-hardened DPL (Dual-rail with Precharge Logic) solutions. The main merit of this proposal is that the EPE can be effectively prevented by using a synchronized non regular precharge network, which maintains identical routing between the original and mirror parts, where costs and design complexity compared with previous EPE-resistant countermeasures are reduced, while security level is not sacrificed. Another advantage for our Precharge Absorbed(PA) - DPL method is that its Dual-Core style (independent architecture for true and false parts) could be generated using partial reconfiguration. This helps to get a dynamic security protection with better energy planning. That means system only keeps the true part which fulfills the normal en/decryption task in low security level, and reconfigures the false parts once high security level is required. A relatively limited clock speed is a compromise, since signal propagation is restricted to a portion of the clock period. In this paper, we explain the principles of PA-DPL and provide the guidelines to design this structure. We experimentally validate our methods in a minimized AES co-processor on Xilinx Virtex-5 board using electromagnetic (EM) attacks.

Effectiveness of resilient wheels in reducing noise and vibrations

This study focuses on the effectiveness of resilient wheels in reducing railway noise and vibrations, and compares the effectiveness of three types of wheels. The finite elements method has been used to characterise the vibratory behaviour of these wheels. The model has been excited with a realistic spectrum of vertical track irregularities, and a spectral analysis has been carried out. Results have been post-processed in order to estimate the sound power emitted. These calculations have been used to assess the effectiveness of the resilient wheel designs in reducing noise emitted to the environment and in propagating structural vibrations.

An alternative for reducing the layers in the construction of three-phase planar transformers

A modified winding layout for three-phase transformers with PCB windings is proposed in this paper. This modified layout can be used in high current transformers with many PCB layers to simplify the fabrication process. One of the key factors that might increase the cost and complexity in the construction of planar transformers is the number of layers of each PCB winding. This issue becomes even more important in medium-high power three-phase transformers, where the number of PCB layers is higher. In addition to that, the proposed method allows the use of commercial core shapes that are commonly used to design single-phase transformers. This fact makes possible the reduction of cost and flexibility of the design solutions. The proposed solution has been validated and compared using the conventional and the proposed methodologies to design a high power (20 kW) transformer.

Towards cost reduction in concentrating solar power: innovative design for an efficient fresnel based solar field

Energía termosolar (de concentración) es uno de los nombres que hacen referencia en español al término inglés “concentrating solar power”. Se trata de una tecnología basada en la captura de la potencia térmica de la radiación solar, de forma que permita alcanzar temperaturas capaces de alimentar un ciclo termodinámico convencional (o avanzado); el futuro de esta tecnología depende principalmente de su capacidad para concentrar la radiación solar de manera eficiente y económica. La presente tesis está orientada hacia la resolución de ciertos problemas importantes relacionados con este objetivo. La mencionada necesidad de reducir costes en la concentración de radiación solar directa, asegurando el objetivo termodinámico de calentar un fluido hasta una determinada temperatura, es de vital importancia. Los colectores lineales Fresnel han sido identificados en la literatura científica como una tecnología con gran potencial para alcanzar esta reducción de costes. Dicha tecnología ha sido seleccionada por numerosas razones, entre las que destacan su gran libertad de diseño y su actual estado inmaduro. Con el objetivo de responder a este desafío se desarrollado un detallado estudio de las propiedades ópticas de los colectores lineales Fresnel, para lo cual se han utilizado métodos analíticos y numéricos de manera combinada. En primer lugar, se han usado unos modelos para la predicción de la localización y la irradiación normal directa del sol junto a unas relaciones analíticas desarrolladas para estudiar el efecto de múltiples variables de diseño en la energía incidente sobre los espejos. Del mismo modo, se han obtenido analíticamente los errores debidos al llamado “off-axis aberration”, a la apertura de los rayos reflejados en los espejos y a las sombras y bloqueos entre espejos. Esto ha permitido la comparación de diferentes formas de espejo –planos, circulares o parabólicos–, así como el diseño preliminar de la localización y anchura de los espejos y receptor sin necesidad de costosos métodos numéricos. En segundo lugar, se ha desarrollado un modelo de trazado de rayos de Monte Carlo con el objetivo de comprobar la validez del estudio analítico, pero sobre todo porque este no es preciso en el estudio de la reflexión en espejos. El código desarrollado está específicamente ideado para colectores lineales Fresnel, lo que ha permitido la reducción del tiempo de cálculo en varios órdenes de magnitud en comparación con un programa comercial más general. Esto justifica el desarrollo de un nuevo código en lugar de la compra de una licencia de otro programa. El modelo ha sido usado primeramente para comparar la intensidad de flujo térmico y rendimiento de colectores Fresnel, con y sin reflector secundario, con los colectores cilíndrico parabólicos. Finalmente, la conjunción de los resultados obtenidos en el estudio analítico con el programa numérico ha sido usada para optimizar el campo solar para diferentes orientaciones –Norte-Sur y Este-Oeste–, diferentes localizaciones –Almería y Aswan–, diferentes inclinaciones hacia el Trópico –desde 0 deg hasta 32 deg– y diferentes mínimos de intensidad del flujo en el centro del receptor –10 kW/m2 y 25 kW/m2–. La presente tesis ha conducido a importantes descubrimientos que deben ser considerados a la hora de diseñar un campo solar Fresnel. En primer lugar, los espejos utilizados no deben ser plano, sino cilíndricos o parabólicos, ya que los espejos curvos implican mayores concentraciones y rendimiento. Por otro lado, se ha llegado a la conclusión de que la orientación Este-Oeste es más propicia para localizaciones con altas latitudes, como Almería, mientras que en zonas más cercanas a los trópicos como Aswan los campos Norte-Sur conducen a mayores rendimientos. Es de destacar que la orientación Este-Oeste requiere aproximadamente la mitad de espejos que los campos Norte-Sur, puediendo estar inclinados hacia los Trópicos para mejorar el rendimiento, y que alcanzan parecidos valores de intensidad térmica en el receptor todos los días a mediodía. Sin embargo, los campos con orientación Norte-Sur permiten un flujo más constante a lo largo de un día. Por último, ha sido demostrado que el uso de diseños pre-optimizados analíticamente, con anchura de espejos y espaciado entre espejos variables a lo ancho del campo, pueden implicar aumentos de la energía generada por metro cuadrado de espejos de hasta el 6%. El rendimiento óptico anual de los colectores cilíndrico parabólicos es 23 % mayor que el rendimiento de los campos Fresnel en Almería, mientras que la diferencia es de solo 9 % en Aswan. Ello implica que, para alcanzar el mismo precio de electricidad que la tecnología de referencia, la reducción de costes de instalación por metro cuadrado de espejo debe estar entre el 10 % y el 25 %, y que los colectores lineales Fresnel tienen más posibilidades de ser desarrollados en zonas de bajas latitudes. Como consecuencia de los estudios desarrollados en esta tesis se ha patentado un sistema de almacenamiento que tiene en cuenta la variación del flujo térmico en el receptor a lo largo del día, especialmente para campos con orientación Este-Oeste. Este invento permitiría el aprovechamiento de la energía incidente durante más parte del año, aumentando de manera apreciable los rendimientos óptico y térmico. Abstract Concentrating solar power is the common name of a technology based on capturing the thermal power of solar radiation, in a suitable way to reach temperatures able to activate a conventional (or advanced) thermodynamic cycle to generate electricity; this quest mainly depends on our ability to concentrate solar radiation in a cheap and efficient way. The present thesis is focused to highlight and help solving some of the important issues related to this problem. The need of reducing costs in concentrating the direct solar radiation, but without jeopardizing the thermodynamic objective of heating a fluid up to the required temperature, is of prime importance. Linear Fresnel collectors have been identified in the scientific literature as a technology with high potential to reach this cost reduction. This technology has been selected because of a number of reasons, particularly the degrees of freedom of this type of concentrating configuration and its current immature state. In order to respond to this challenge, a very detailed exercise has been carried out on the optical properties of linear Fresnel collectors. This has been done combining analytic and numerical methods. First, the effect of the design variables on the ratio of energy impinging onto the reflecting surface has been studied using analytically developed equations, together with models that predict the location and direct normal irradiance of the sun at any moment. Similarly, errors due to off-axis aberration, to the aperture of the reflected energy beam and to shading and blocking effects have been obtained analytically. This has allowed the comparison of different shapes of mirrors –flat, cylindrical or parabolic–, as well as a preliminary optimization of the location and width of mirrors and receiver with no need of time-consuming numerical models. Second, in order to prove the validity of the analytic results, but also due to the fact that the study of the reflection process is not precise enough when using analytic equations, a Monte Carlo Ray Trace model has been developed. The developed code is designed specifically for linear Fresnel collectors, which has reduced the computing time by several orders of magnitude compared to a wider commercial software. This justifies the development of the new code. The model has been first used to compare radiation flux intensities and efficiencies of linear Fresnel collectors, both multitube receiver and secondary reflector receiver technologies, with parabolic trough collectors. Finally, the results obtained in the analytic study together with the numeric model have used in order to optimize the solar field for different orientations –North-South and East-West–, different locations –Almería and Aswan–, different tilts of the field towards the Tropic –from 0 deg to 32 deg– and different flux intensity minimum requirements –10 kW/m2 and 25 kW/m2. This thesis work has led to several important findings that should be considered in the design of Fresnel solar fields. First, flat mirrors should not be used in any case, as cylindrical and parabolic mirrors lead to higher flux intensities and efficiencies. Second, it has been concluded that, in locations relatively far from the Tropics such as Almería, East-West embodiments are more efficient, while in Aswan North- South orientation leads to a higher annual efficiency. It must be noted that East-West oriented solar fields require approximately half the number of mirrors than NS oriented fields, can be tilted towards the Equator in order to increase the efficiency and attain similar values of flux intensity at the receiver every day at midday. On the other hand, in NS embodiments the flux intensity is more even during each single day. Finally, it has been proved that the use of analytic designs with variable shift between mirrors and variable width of mirrors across the field can lead to improvements in the electricity generated per reflecting surface square meter up to 6%. The annual optical efficiency of parabolic troughs has been found to be 23% higher than the efficiency of Fresnel fields in Almería, but it is only around 9% higher in Aswan. This implies that, in order to attain the same levelized cost of electricity than parabolic troughs, the required reduction of installation costs per mirror square meter is in the range of 10-25%. Also, it is concluded that linear Fresnel collectors are more suitable for low latitude areas. As a consequence of the studies carried out in this thesis, an innovative storage system has been patented. This system takes into account the variation of the flux intensity along the day, especially for East-West oriented solar fields. As a result, the invention would allow to exploit the impinging radiation along longer time every day, increasing appreciably the optical and thermal efficiencies.

Reducing the impact of EV charging on the electric grid

One of the main objectives of European Commission related to climate and energy is the well-known 20-20-20 targets to be achieved in 2020: Europe has to reduce greenhouse gas emissions of at least 20% below 1990 levels, 20% of EU energy consumption has to come from renewable resources and, finally, a 20% reduction in primary energy use compared with projected levels, has to be achieved by improving energy efficiency. In order to reach these objectives, it is necessary to reduce the overall emissions, mainly in transport (reducing CO2, NOx and other pollutants), and to increase the penetration of the intermittent renewable energy. A high deployment of battery electric (BEVs) and plug-in hybrid electric vehicles (PHEVs), with a low-cost source of energy storage, could help to achieve both targets. Hybrid electric vehicles (HEVs) use a combination of a conventional internal combustion engine (ICE) with one (or more) electric motor. There are different grades of hybridation from micro-hybrids with start-stop capability, mild hybrids (with kinetic energy recovery), medium hybrids (mild hybrids plus energy assist) and full hybrids (medium hybrids plus electric launch capability). These last types of vehicles use a typical battery capacity around 1-2 kWh. Plug in hybrid electric vehicles (PHEVs) use larger battery capacities to achieve limited electric-only driving range. These vehicles are charged by on-board electricity generation or either plugging into electric outlets. Typical battery capacity is around 10 kWh. Battery Electric Vehicles (BEVs) are only driven by electric power and their typical battery capacity is around 15-20 kWh. One type of PHEV, the Extended Range Electric Vehicle (EREV), operates as a BEV until its plug-in battery capacity is depleted; at which point its gasoline engine powers an electric generator to extend the vehicle's range. The charging of PHEVs (including EREVs) and BEVs will have different impacts to the electric grid, depending on the number of vehicles and the start time for charging. Initially, the lecture will start analyzing the electrical power requirements for charging PHEVs-BEVs in Flanders region (Belgium) under different charging scenarios. Secondly and based on an activity-based microsimulation mobility model, an efficient method to reduce this impact will be presented.