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Event-based vision, as realized by bio-inspired Dynamic Vision Sensors (DVS), is gaining more and more popularity due to its advantages of high temporal resolution, wide dynamic range and power efficiency at the same time. Potential applications include surveillance, robotics, and autonomous navigation under uncontrolled environment conditions. In this paper, we deal with event-based vision for 3D reconstruction of dynamic scene content by using two stationary DVS in a stereo configuration. We focus on a cooperative stereo approach and suggest an improvement over a previously published algorithm that reduces the measured mean error by over 50 percent. An available ground truth data set for stereo event data is utilized to analyze the algorithm's sensitivity to parameter variation and for comparison with competing techniques.

The performance losses due to soiling occurring on any photovoltaic (PV) device are caused by a complex mechanism that involves numerous factors and their interactions. For this reason, the present work analyzes the outputs of reference PV cells installed in various locations, with the aim of contributing to the identification of the most important factors influencing the accumulation of dust on a PV surface. Parameters such as the air-quality indexes, the recurrence and the amount of rainfall and the climate zone are investigated and related to the soiling losses of the PV device.

In Smart Village Skarpnes in southern Norway, five detached houses are designed as zero energy homes. This work reports on the photovoltaic (PV) power production and energy consumption behavior of these homes and discusses whether an annual zero energy budget may be achieved. Results so far indicate that the extremely low annual energy consumption assumed for these types of homes may be difficult to achieve, and also point at a need for better matching between production and consumption power profiles. Performance results are based on monitoring data combined with estimated performances from PVsyst simulations. The work is part of a larger research project that investigates how the introduction of low-energy buildings equipped with PV systems is expected to change the power flow to and from the grid, which will require new models for efficient operation and investment in the future electric distribution grid.

The purpose of this paper is to propose a solution to an extremely pertinent problem, namely, that of identifying unreliable sensors (in a domain of reliable and unreliable ones) without any knowledge of the ground truth. This fascinating paradox can be formulated in simple terms as trying to identify stochastic liars without any additional information about the truth. Though apparently impossible, we will show that it is feasible to solve the problem, a claim that is counter-intuitive in and of itself. One aspect of our contribution is to show how redundancy can be introduced, and how it can be effectively utilized in resolving this paradox. Legacy work and the reported literature (for example, in the so-called weighted majority algorithm) have merely addressed assessing the reliability of a sensor by comparing its reading to the ground truth either in an online or an offline manner. Unfortunately, the fundamental assumption of revealing the ground truth cannot be always guaranteed (or even expected) in many real life scenarios. While some extensions of the Condorcet jury theorem [9] can lead to a probabilistic guarantee on the quality of the fused process, they do not provide a solution to the unreliable sensor identification problem. The essence of our approach involves studying the agreement of each sensor with the rest of the sensors, and not comparing the reading of the individual sensors with the ground truth-as advocated in the literature. Under some mild conditions on the reliability of the sensors, we can prove that we can, indeed, filter out the unreliable ones. Our approach leverages the power of the theory of learning automata (LA) so as to gradually learn the identity of the reliable and unreliable sensors. To achieve this, we resort to a team of LA, where a distinct automaton is associated with each sensor. The solution provided here has been subjected to rigorous experimental tests, and the results presented are, in our opinion, both novel and conclusive.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text K. Grujic, H. Mathisen, and S. Simonsen, "Optical Pyrometry in Harsh Environments: Measurement of Extreme Temperatures in a Pilot Scale Acheson Furnace," in Imaging and Applied Optics 2016, OSA Technical Digest (online) (Optica Publishing Group, 2016), paper AITh3A.4. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

SummarySimplified flow equations are developed for Herschel-Bulkley (HB) fluids in laminar Couette-Poiseuille (CP) flow. Such flow problems are encountered in drilling when the drillstring is moved longitudinally (surge and swab operations). The new equations give the frictional-pressure gradient explicitly as a function of the bulk-flow rate. This makes them very well-suited for applications in fast, robust dynamic models for real-time applications. Incorporating these equations in a dynamic model based on ordinary differential equations (ODEs) enables coupling with system identification and control-system theory. This is a great advantage in drilling applications where there are many uncertain parameters and few measurements. Thorough analysis of relevant analytical solutions is performed to replace the most complex (implicit) parts of the solution with simpler approximations. The accuracy of the new equations, in comparison with numerical simulations and available analytical solutions, is shown to be acceptable for most practical applications.

This paper presents performance results from one of the first grid-connected photovoltaic (PV) systems in Norway. The 45 kWp system is mounted on top of a flat roof at the headquarters of a local utility company, Agder Energi, in the coastal town of Kristiansand. The system consists mainly of multi-crystalline silicon modules, with one thin film array. The system has been in operation since May 2011 and is instrumented for research and monitoring purposes. Data recorded include global and diffuse horizontal irradiation, tilted irradiation and other weather parameters, PV module temperatures, DC and AC current and voltage for three arrays, in addition to inverter power data and voltage quality measurements. Similar performance data has not yet been published for Norway. The results so far indicate good conditions for solar utilization at this location with global horizontal irradiation around 1065 W/(m2yr) and around 50 % diffuse fraction. The system produces as expected from a design perspective, with specific yield reaching 950 kWh/kWp and PR approaching 0.8 in 2014. Improvement in PR is seen as operational experience increases and system downtime is reduced. PR loss can be attributed to part-shading of PV arrays from the surrounding building structures, snow coverage in winter and inverter outages.

Yield loss due to the breakage and production of nonprime or off-spec cells in industrially produced crystalline silicon-based solar cells is around 1-2%. Nonprime cells identified based on their electrical properties are rejected after quality inspection. The cells that are rejected can be classified as nonprime for many reasons, such as poor edge isolation, presence of conductive paths through p-n junctions formed by print paste stains, paste-filled microcracks, inclusions, nonuniform emitter, and nonuniform antireflective coatings. Development of efficient and economically feasible repair methods for the repowering of nonprime cells will increase the overall yield of the solar cell industry and reduce costs. To isolate severe shunts under front metallization, we developed a two-step chemical etching process to remove front metallization and emitter. Removal of front metallization and emitter yielded the best isolation of shunts. Shunt isolation and efficiency gain achieved by the chemical etching process has been demonstrated on both mono- and multicrystalline silicon solar cells.

Abstract In the exploration of global‐scale features of the Earth's aurora, little attention has been given to the radial component of the Interplanetary Magnetic Field (IMF). This study investigates the global auroral response in both hemispheres when the IMF is southward and lies in the xz plane. We present a statistical study of the average auroral response in the 12–24 magnetic local time (MLT) sector to an x component in the IMF. Maps of auroral intensity in both hemispheres for two IMF B x dominated conditions (± IMF B x ) are shown during periods of negative IMF B z , small IMF B y , and local winter. This is obtained by using global imaging from the Wideband Imaging Camera on the IMAGE satellite. The analysis indicates a significant asymmetry between the two IMF B x dominated conditions in both hemispheres. In the Northern Hemisphere the aurora is brighter in the 15–19 MLT region during negative IMF B x . In the Southern Hemisphere the aurora is brighter in the 16–20 MLT sector during positive IMF B x . We interpret the results in the context of a more efficient solar wind dynamo in one hemisphere. Both the intensity asymmetry and its location are consistent with this idea. This has earlier been suggested from case studies of simultaneous observations of the aurora in both hemispheres, but hitherto never been observed to have a general impact on global auroral brightness in both hemispheres from a statistical study. The observed asymmetries between the two IMF B x cases are not large; however, the difference is significant with a 95% confidence level. As the solar wind conditions examined in the study are rather common (37% of the time) the accumulative effect of this small influence may be important for the total energy budget.