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In the presented paper data collected from the field related to damage statistics of electrical and electronic apparatus in household are reported and investigated. These damages (total number approx. 74000 cases), registered by five German insurance companies in 2005 and 2006, were adviced by customers as caused by lightning overvoltages. With the use of stochastical methods it is possible, to reasses the collected data and to distinguish between cases, which are with high probability caused by lightning overvoltages, and those, which are not. If there was an indication for a direct strike, this case was excluded, so the focus was only on indirect lightning flashes, i.e. only flashes to ground near the structure and flashes to or nearby an incoming service line were investigated. The data from the field contain the location of damaged apparatus (residence of the policy holder) and the distances of the nearest cloud-to-ground stroke to the location of the damage registered by the German lightning location network BLIDS at the date of damage. The statistical data along with some complementary numerical simulations allow to verify the correspondence of the Standards rules used for IEC 62305-2 with the field data and to define some correction needs. The results could lead to a better understanding whether a damage reported to an insurance company is really caused by indirect lightning, or not.
[Paper of the X International Symposium on Lightning Protection 9th - 13th November, 2009 - Curitiba, Brazil. 6 pages] The international standard IEC 62305-3, published in 2006, requires as an integral part of the lightning protection system (LPS) the consideration of a separation distance between the conductors of the LPS and metal and electrical installations inside the structure to be protected. IEC 62305-3 gives two different methods for this calculation: a standard, simplified approach and a more detailed approach, which differ especially regarding the treatment of the current sharing effect on the LPS conductors. Hence, different results for the separation distance are possible, leading to some discrepancies in the use of the standard. The standard approach defined in the main part (Clause 6.3) and in Annex C of the standard in some cases may lead to a severe oversizing of the required separation distance. The detailed approach described in Annex E naturally gives more correct results. However, a calculation of the current sharing amongst all parts of the air-termination and downconductor network is necessary, in many cases requiring the use of network analysis programs. In this paper simplified methods for the assessment of the current sharing are presented, which are easy to use as well as sufficiently adequate.
The downsizing of spark ignition engines in conjunction with turbocharging is considered to be a promising method for reducing CO₂ emissions. Using this concept, FEV has developed a new, highly efficient drivetrain to demonstrate fuel consumption reduction and drivability in a vehicle based on the Ford Focus ST. The newly designed 1.8L turbocharged gasoline engine incorporates infinitely variable intake and outlet control timing and direct fuel injection utilizing piezo injectors centrally located. In addition, this engine uses a prototype FEV engine control system, with software that was developed and adapted entirely by FEV. The vehicle features a 160 kW engine with a maximum mean effective pressure of 22.4 bar and 34 % savings in simulated fuel consumption. During the first stage, a new electrohydraulically actuated hybrid transmission with seven forward gears and one reverse gear and a single dry starting clutch will be integrated. The electric motor of the hybrid is directly connected to the gear set of the transmission. Utilizing the special gear set layout, the electric motor can provide boost during a change of gears, so that there is no interruption in traction. Therefore, the transmission system combines the advantages of a double clutch controlled gear change (gear change without an interruption in traction) with the efficient, cost-effective design of an automated manual transmission system. Additionally, the transmission provides a purely electric drive system and the operation of an air-conditioning compressor during the engine stop phases. One other alternative is through the use of CAI (Controlled Auto Ignition), which incorporates a process developed by FEV for controlled compression ignition.
Das Ziel der vorliegenden Arbeit ist die Specklereduktion bei der Infrarotlaser-gestützten abbildenden Ferndetektion von TNT-Oberflächenkontaminationen. Für die Detektion wird die Probenoberfläche mit einem abstimmbaren Quantenkaskadenlaser bei verschiedenen Wellenzahlen im Spektralbereich von 1340cm-1 bis 1380cm-1 bestrahlt, während eine Infrarot-Kamera Bilder der bestrahlten Fläche aufzeichnet. Diese Bilder werden dann so verarbeitet, dass im Ausgabebild die chemisch spezifische TNT-Absorption durch eine Änderung der Helligkeit örtlich aufgelöst erkennbar werden. Da kohärente Strahlung, welche beispielsweise an optisch rauen Oberflächen reflektiert wird, aufgrund der stochastischen Verteilung der Oberflächenrautiefe mit der einfallenden Strahlung lateral unterschiedlich interferiert, entsteht ein „Rauschen“ in der aufgezeichneten Strahlungsleistungsverteilung, das sog. Speckle-Phänomen. Die Empfindlichkeit der oben skizzierten Lasergestützten Messtechnik wird im Wesentlichen durch diesen Effekt limitiert. Um die durch Laserspeckles verursachten Rauschanteile zu reduzieren, gibt es verschiedene Möglichkeiten. Durch Reduktion von zeitlicher und räumlicher Kohärenz der Strahlung wird deren Interferenzfähigkeit reduziert und durch Variieren des Specklemusters während einer Bildaufzeichnung führen Mittelungen unkorrelierter Rauschanteile zu einer Specklekontrastreduktion. Letztere Möglichkeit resultiert daraus, dass Laserspeckles statistisch durch die Familie der Gammaverteilungen beschrieben werden können. Demnach verbessert sich das Signal-zu-Rausch-Verhältnis mit der Anzahl gemittelter, unkorrelierter Rauschmuster proportional zur Wurzel dieser Anzahl. Ein im MIR-Spektralbereich umsetzbarer Ansatz, der all diese Möglichkeiten berücksichtigt, wurde bereits 1971 von Lowenthal und Joyeaux vorgeschlagen und im Rahmen der vorliegenden Arbeit für den infraroten Spektralbereich adaptiert. Dazu wird die Strahlung mit zwei CVD-Diamant-Wafern moduliert; ein Wafer ist dabei stationär und der andere rotiert mit ca. 70Hz. In der vorliegenden Arbeit konnte mit diesem Ansatz eine Verbesserung des Signal-zu-Rausch-Verhältnisses in der betrachteten Strahlungsleistungs¬verteilung von ursprünglich 3 auf etwa 45 erzielt werden. So konnten erstmals TNT-Kontaminationen von bis zu 10µg/cm² in einem Abstand von 5m abbildend nachgewiesen werden. Dies entspricht der Kontamination durch einen mit TNT leicht verunreinigten Fingerabdruck.
Unravelling the factors determining the allocation of carbon to various plant organs is one of the great challenges of modern plant biology. Studying allocation under close to natural conditions requires non-invasive methods, which are now becoming available for measuring plants on a par with those developed for humans. By combining magnetic resonance imaging (MRI) and positron emission tomography (PET), we investigated three contrasting root/shoot systems growing in sand or soil, with respect to their structures, transport routes and the translocation dynamics of recently fixed photoassimilates labelled with the short-lived radioactive carbon isotope 11C. Storage organs of sugar beet (Beta vulgaris) and radish plants (Raphanus sativus) were assessed using MRI, providing images of the internal structures of the organs with high spatial resolution, and while species-specific transport sectoralities, properties of assimilate allocation and unloading characteristics were measured using PET. Growth and carbon allocation within complex root systems were monitored in maize plants (Zea mays), and the results may be used to identify factors affecting root growth in natural substrates or in competition with roots of other plants. MRI–PET co-registration opens the door for non-invasive analysis of plant structures and transport processes that may change in response to genomic, developmental or environmental challenges. It is our aim to make the methods applicable for quantitative analyses of plant traits in phenotyping as well as in understanding the dynamics of key processes that are essential to plant performance.