Simulating the dynamics of wind turbine blades: part II,model validation and uncertainty quantification

Verification and validation (V&V) offers the potential to play an indispensable role in the development of credible models for the simulation of wind turbines. This paper highlights the development of a three‐dimensional finite element model of the CX‐100 wind turbine blade. The scientific hypothesis that we wish to confirm by applying V&V activities is that it is possible to develop a fast‐running model capable of predicting the low‐order vibration dynamics with sufficient accuracy. A computationally efficient model is achieved by segmenting the geometry of the blade into six sections only. It is further assumed that each cross section can be homogenized with isotropic material properties. The main objectives of V&V activities deployed are to, first, assess the extent to which these assumptions are justified and, second, to quantify the resulting prediction uncertainty. Designs of computer experiments are analyzed to understand the effects of parameter uncertainty and identify the significant sensitivities. A calibration of model parameters to natural frequencies predicted by the simplified model is performed in two steps with the use of, first, a free–free configuration of the blade and, second, a fixed–free configuration. This two‐step approach is convenient to decouple the material properties from parameters of the model that describe the boundary condition. Here, calibration is not formulated as an optimization problem. Instead, it is viewed as a problem of inference uncertainty quantification where measurements are used to learn the uncertainty of model parameters. Gaussian process models, statistical tests and Markov chain Monte Carlo sampling are combined to explore the (true but unknown) joint probability distribution of parameters that, when sampled, produces bounds of prediction uncertainty that are consistent with the experimental variability. An independent validation assessment follows the calibration and is applied to mode shape vectors. Despite the identification of isolated issues with the simulation code and model developed, the overarching conclusion is that the modeling strategy is sound and leads to an accurate‐enough, fast‐running simulation of blade dynamics. This publication is Part II of a two‐part effort that highlights the V&V steps required to develop a robust model of a wind turbine blade, where Part I emphasizes code verification and the quantification of numerical uncertainty. Approved for unlimited public release on August 26, 2011, LA‐UR‐11‐4997. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and Preliminary Cancer Cell Line Results for the Product of Organotin Dihalides and Alpha-Cyano-4-Hydroxycinnamic Acid

High polymer poly(ester ethers) are rapidly synthesized in good yield employing the interfacial polycondensation reaction system. Infrared spectroscopy shows the formation of new bands derived from the Sn–O and Sn–O(CO) linkages. It also shows that the products exist as alternating Sn–O and Sn–O(CO) linkages. MALDI MS shows formation of ion fragment clusters several units in length. The products show reasonable inhibition of a variety of cancer cell lines including two pancreatic cancer cell lines.     

Outbacks: the popular construction of an emergent landscape

What is an 'outback'? Why is the term being applied to landscapes bearing little resemblance to the Australian interior? Based on a survey of the rising international use of this term, and a case study from Ohio, it is suggested that outbacks are discursively produced: (a) where post-industrial relationships between an urban place and its much larger, contiguous periphery have matured; (b) where economic shifts have resulted in patchy but recognizable re-naturalization of erstwhile fields or industrial badlands; (c) by rural groups, who recognize and promote the 'environmental power' of their changing landscapes; and (d) when proximate urbanites consume these landscapes as accessible, nostalgic, multi-use recreational getaways. The outback concept, then, offers a framework for exploring a new type of re-greened, post-industrial landscape through its discursive production by citizens, in a way that encompasses multiple forms of social, economic and ecological change. Where landscape scholars tend to explore these issues in isolation, simultaneous 'outbacking' of different landscapes around the world draws attention to popular articulation of commonalities in rural experience.     

Neural Networks and Principal Components Analysis for Strain-Based Vehicle Classification

A large database has been acquired and compiled of vehicles crossing over a simply supported bridge deck system. Over the course of 1.5?years, deck strains caused by traffic, along with time-synchronized video images have been archived (400,000 records). Herein, this dataset is presented and used to develop a strain-based vehicle classification approach, as a machine learning application. To achieve this goal, the principal components analysis technique is applied to extract essential features from the strain time histories. Using these features as input, a two-layered back-propagation neural network is built and trained to sort vehicles into five classes. In this regard, availability of the video images provides essential information for developing the needed labeled datasets. The trained network is tested, and satisfactory results are achieved, showing viability of the classification approach for this bridge deck system.     

Fasting increases risk for onset of binge eating and bulimic pathology: A 5-year prospective study.

Although adolescent girls with elevated dietary restraint scores are at increased risk for future binge eating and bulimic pathology, they do not eat less than those with lower restraint scores. The fact that only a small proportion of individuals with elevated dietary restraint scores develop bulimic pathology suggests that some extreme but rare form of dietary restriction may increase risk for this disturbance. The authors tested the hypothesis that fasting (going without eating for 24 hr for weight control) would be a more potent predictor of binge eating and bulimic pathology onset than dietary restraint scores using data from 496 adolescent girls followed over 5 years. Results confirmed that only 23% of participants with elevated dietary restraint scores reported fasting. Furthermore, fasting generally showed stronger and more consistent predictive relations to future onset of recurrent binge eating and threshold/subthreshold bulimia nervosa over 1- to 5-year follow-up relative to dietary restraint, though the former effects were only significantly stronger than the latter for some comparisons. Results provide preliminary support for the hypothesis that fasting is a stronger risk factor for bulimic pathology than is self-reported dieting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contact chemosensory cues in egg bundles elicit male-male agonistic conflicts in the squid Loligo pealeii

Male Loligo pealeii engage in frequent agonistic bouts to gain access to female mates while aggregated at communal egg beds. Male squids are attracted to eggs in the field and in the laboratory. It was recently demonstrated that visual detection followed by physical contact with egg capsules elicited male–male aggression. We tested specific physical and chemical features of the egg capsules that may cause this strong behavioral reaction. Male squids were presented with either natural or artificial egg stimuli and scored for four selected behaviors (egg touch, egg blowing, forward-lunge grab, and fin-beating), the last two of which are highly aggressive behaviors. First, squids were presented with natural eggs versus eggs sealed in agarose-coated tubes (ESACT), which eliminated both tactile and chemical stimuli. Second, males were presented with natural eggs versus eggs sealed in agarose coated tubes containing C₁₈ Sep-Pak-purified extracts (TCPE) from squid egg capsules, which provided chemical cues from natural eggs without the physical stimulus of the egg capsules. Third, natural eggs versus heat-denatured eggs were tested to determine whether the active factor in natural eggs is heat-labile. Squids responded aggressively when contacting natural eggs and TCPE, whereas squids did not respond after touching ESACT or denatured eggs. These results suggest that aggressive behavior is elicited by a heat-labile factor that is embedded within squid egg capsules. This chemosensory cue appears to be a contact pheromone that stimulates the agonistic interactions that characterize the mating behavior of migratory squids on inshore spawning grounds.     

Testing superabsorbent polymer (SAP) sorption properties prior to implementation in concrete: results of a RILEM Round-Robin Test

This article presents the results of a round-robin test performed by 13 international research groups in the framework of the activities of the RILEM Technical Committee 260 RSC “Recommendations for use of superabsorbent polymers in concrete construction”. Two commercially available superabsorbent polymers (SAP) with different chemical compositions and gradings were tested in terms of their kinetics of absorption in different media; demineralized water, cement filtrate solution with a particular cement distributed to every participant and a local cement chosen by the participant. Two absorption test methods were considered; the tea-bag method and the filtration method. The absorption capacity was evaluated as a function of time. The results showed correspondence in behaviour of the SAPs among all participants, but also between the two test methods, even though high scatter was observed at early minutes of testing after immersion. The tea-bag method proved to be more practical in terms of time dependent study, whereby the filtration method showed less variation in the absorption capacity after 24 h. However, absorption followed by intrinsic, ion-mediated desorption of a specific SAP sample in the course of time was not detected by the filtration method. This SAP-specific characteristic was only displayed by the tea-bag method. This demonstrates the practical applicability of both test methods, each one having their own strengths and weaknesses at distinct testing times.     

Computation of a face attractiveness index based on neoclassical canons, symmetry, and golden ratios

Analysis of attractiveness of faces has long been a topic of research. Literature has identified many different factors that can be related to attractiveness. In this research we analyze the role of symmetry, neoclassical canons, and golden ratio in the determination of attractiveness of a face. We focus on the geometry of a face and use actual faces for our analysis. We find there are some differences in the criteria used by males and females to determine attractiveness. The model we have developed to predict the attractiveness of a face using its geometry is accurate with low residual errors.     

Comparing laser diffraction and optical microscopy for characterizing superabsorbent polymer particle morphology,size, and swelling capacity

In this study, we determined the accuracy and practicality of using optical microscopy (OM) and laser diffraction (LD) to characterize hydrogel particle morphology, size, and swelling capacity (Q). Inverse‐suspension‐polymerized polyacrylamide particles were used as a model system. OM and LD showed that the average particle diameter varied with the mixing speed during synthesis for the dry (10–120 μm) and hydrated (34–240 μm) particles. The LD volume and number mean diameters showed that a few large particles were responsible for the majority of the water absorption. Excess water present in the gravimetric swelling measurements led to larger Qs (8.2 ± 0.37 g/g), whereas the volumetric measurements with OM and LD resulted in reduced capacities (6.5 ± 3.8 and 5.7 ± 3.9 g/g, respectively). Results from the individual particle swelling measurements with OM (5.2 ± 0.66 g/g) statistically confirmed that the volumetric methods resulted in a reduced and more accurate measurement of the Q than the gravimetric method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46055.