How accurate is a commercial monitoring system for photovoltaic plant?

According to uncertainty calculations, the values recorded by means of commercial monitoring systems are expected to be less accurate than those recorded by a system optimized for the measurement of electrical parameters—the so‐called dedicated system (DS). This study aims to verify if a larger expected uncertainty for commercial system (CS) actually turns into a larger spread of the measurements around the true value. In the Airport Bolzano Dolomiti plant, CS and DS are installed on the same photovoltaic arrays. The comparison performed considers the detailed uncertainty budget for the two systems using three performance indicators—energy, yield and performance ratio. Results show that the uncertainty level of the CS is much larger; for example, on performance ratio, it is about four times larger with respect to the optimized one (respectively ±16% and ±4%). Three sources mainly contribute to the uncertainty: measurements of irradiance, current and voltage. The measured values of the electrical parameter are compared in order to verify if the results of the budget calculations turn into a real difference. Results show that the CS is accurate in measuring current and voltage, respectively, ~2% and ~5% of difference from the DS, but not for irradiance—here, the difference is higher than 10%. In particular, the irradiance measured by the CS is systematically smaller; therefore, the performance ratio calculated through the CS is always overestimated and often larger than 100%. Copyright © 2012 John Wiley & Sons, Ltd.     

Online Journalism and the War in Cyberspace: A Comparison Between U.S. and International Newspapers

The 2003 Iraq War was the first military conflict in which online media played a significant role. Traditional news organizations from around the world provided extensive coverage of the conflict on their websites, reaching global audiences and adding new dimensions to traditional war reporting. This study explores how the Internet disseminated news about the war by comparing 26 international newspaper sites (N = 791) and their use of Web‐specific features such as hyperlinks, animations, multimedia content, and interactive elements. By proposing a three‐stage model of online journalism and applying it to the online war coverage, the analysis suggests that online journalism has not yet reached the state of convergence. The differences in online news coverage between the United States and international websites and their implications are also discussed.     

Fundamentals of power spectra of extracellular potentials produced by a skeletal muscle fibre of finite length. Part I: Effect of fibre anatomy

To provide a thorough understanding of the changes in the power spectrum of electromyographic (EMG) signals, the formation of the power spectrum (PS) of extracellular potentials (EPs) produced by a skeletal muscle fibre of finite length was analysed. It was shown that, as in the case of an infinite fibre, the PS could be represented as the product of power spectra of the input signal (the first temporal derivative of the intracellular action potential, IAP) and of the impulse response (IR) of the fibre of finite length as a system of EP generation. The interrelations between the two multipliers determine the sensitivity of the EP power spectrum to alterations in parameters. The anatomical parameters of the fibre (length, depth, position of the end-plate in respect of the fibre ends) affect the EP power spectrum through IR power spectrum. Variations of the EP characteristic frequencies along the fibre length as well as oscillations in the PS are intrinsic properties of the fibre of finite length.     

Humoral and cellular immune response to elastin in patients with systemic sclerosis

Fifty-six patients (age range, 15-79 yr, average, 37.0+/-18.5 yr), with a clinical and/or radiological diagnosis of acute maxillary sinusitis, were prospectively studied with ultrasound (US) and computed tomography (CT). The imaging finding which supported the diagnosis of acute sinusitis with US was the identification of the hyperechoic posterior antral wall through the hypoechoic inflammation. The findings were compared to CT (3 mm axial sections). The sensitivity of US for maxillary sinus disease was found to be 66.7% and the specificity was 94.9%, which were similar to the plain film ones (65.2 and 96.8%, respectively). The results of the present study suggest US as the method of first choice for acute sinusitis of the maxillary antra, particularly for children and pregnant women.     

Subjective evaluation of terry fabrics handle

Based on a survey among specialists, the impact of criteria such as thickness, bulkiness, smoothness, stiffness, extensibility and elasticity on the handle of terry fabrics is evaluated and ranked. A methodology was developed to determine the weight coefficient of the factors involved in the evaluation. A relation was determined providing a connection between the examined factors and the handle rated on the Kawabata scale. A manual evaluation of terry fabric with different mass per unit area, structural features and finishing treatments was performed. Two methods were used – by ranking and by assigning a numerical score (from 0 to 5). The opinion of the evaluators has proven consistency, as the ranking of the samples, regardless of the method, was the same. The obtained results will be used to create a complex evaluation of terry fabrics handle.     

Study and design of a hybrid wind–diesel-compressed air energy storage system for remote areas

Remote areas around the world predominantly rely on diesel-powered generators for their electricity supply, a relatively expensive and inefficient technology that is responsible for the emission of 1.2 million tons of greenhouse gas (GHG) annually, only in Canada [1]. Wind–diesel hybrid systems (WDS) with various penetration rates have been experimented to reduce diesel consumption of the generators. After having experimented wind–diesel hybrid systems (WDS) that used various penetration rates, we turned our focus to that the re-engineering of existing diesel power plants can be achieved most efficiently, in terms of cost and diesel consumption, through the introduction of high penetration wind systems combined with compressed air energy storage (CAES). This article compares the available technical alternatives to supercharge the diesel that was used in this high penetration wind–diesel system with compressed air storage (WDCAS), in order to identify the one that optimizes its cost and performances. The technical characteristics and performances of the best candidate technology are subsequently assessed at different working regimes in order to evaluate the varying effects on the system. Finally, a specific WDCAS system with diesel engine downsizing is explored. This proposed design, that requires the repowering of existing facilities, leads to heightened diesel power output, increased engine lifetime and efficiency and to the reduction of fuel consumption and GHG emissions, in addition to savings on maintenance and replacement cost.     

Connected by media [vision and views]

Advertising campaigns and highly popular government programs have for many years trumpeted the need to get people connected to the Internet. That meant solving the technological and sociological issues involved in providing network access to the population and turning them into regular users. The message echoes today in a slightly muted form. Except in developing parts of the world, getting people connected is no longer a major challenge. The challenge today is to create and support experiences that users continue to value. The recent drop in the overheated valuations of networking-oriented businesses serves as a useful reminder that people don't really care about being connected to the Internet per se. They use the Internet to connect to other people or things. In the case of, connecting to people, a valuable question to ask might be, How can connected applications identify communities, support their activities, and evolve to meet their needs? With respect to things, let's consider the increasingly popular situation in which those things are multimedia content. In particular, let's think about how multimedia content might be the glue that connects, defines, and supports communities. Irrespective of views on intellectual property issues or business models, even a cursory reading of recent events makes it undeniable that the Web is becoming a remarkably effective-if not yet efficient-multimedia content distribution platform. While this may not have been a design goal earlier, it's now a significant driving force in the evolution of network technology, user services, and access devices. Given media content, people, and the Internet, there are three sorts of connectedness pairings to consider: people-to-people; people-to-media; and media-to-media