Augmented Adaptive Control of a Wind Turbine in the Presence of Structural Modes

Wind turbines operate in highly turbulent environments resulting in aerodynamic loads that can easily excite turbine structural modes, potentially causing component fatigue and failure. Two key technology drivers for turbine manufacturers are increasing turbine up time and reducing maintenance costs. Since the trend in wind turbine design is towards larger, more flexible turbines with lower frequency structural modes, manufacturers will want to develop methods to operate in the presence of these modes. Accurate models of the dynamic characteristics of new wind turbines are often not available due to the complexity and expense of the modeling task, making wind turbines ideally suited to adaptive control. In this paper, we develop theory for adaptive control with rejection of disturbances in the presence of modes that inhibit the controller. We use this method to design an adaptive collective pitch controller for a high-fidelity simulation of a utility-scale, variable-speed wind turbine operating in Region 3. The objective of the adaptive pitch controller is to regulate generator speed, accommodate wind gusts, and reduce the interference of certain structural modes in feedback. The control objective is accomplished by collectively pitching the turbine blades. The adaptive pitch controller for Region 3 is compared in simulations with a baseline classical Proportional Integrator (PI) collective pitch controller

A Comparative Assessment of knowledge management education across the United States department of defense Summer Bartczak (University of Central Arkansas)

The National Military Strategy (2004), the Capstone Concept for Joint Operations (2005), and the Quadrennial Defense Review (2006) specifically highlight a new focus by the Department of Defense (DoD) on knowledge in operations as opposed to traditional weapons platforms. As such, each of the military services have put into place KM programs to varying degrees. According to Stankosky’s (2005) four pillars of KM framework, managing an organization’s knowledge assets can be most effectively accomplished by addressing four key elements--leadership, organization, technology, and learning—the “learning” pillar including KM education. Given that research on KM education is sparse (Ruth et al, 2000) and that organizations that do not address KM education are more likely to fail with KM efforts (Koenig, 2004), this multiple-case study provides a first look at KM education across the DoD. The preliminary results indicate that nature and importance of programs vary across the services, and, despite some leadership support, the resources needed to execute them are not always available

Properties of isolated red pulp macrophages from mouse spleen

[No abstract available

Ligated complement receptors do not activate the arachidonic acid cascade in resident peritoneal macrophages

Receptors for IgG stimulate the release of approximately 20% of cellular arachidonic acid (20:4) from murine resident peritoneal macrophages. In contrast, C3 receptors do not trigger the secretion of any 20:4 in excess of that released constitutively from the cells. Since the ability of C3 receptors to promote phagocytosis is regulated, we compared resting macrophages, whose C3 receptors do not promote phagocytosis of C3-coated particles, and lymphokine-treated cells, whose receptors do promote ingestion. Despite their ability to promote phagocytosis, the C3 receptor of lymphokine-treated macrophages remain unable to initiate release of 20:4. We speculate that the intracellular signals that initiate phagocytosis are distinct from those that initiate release of 20:4

Intrinsic noise and discrete-time processes

A general formalism is developed to construct a Markov chain model that converges to a one-dimensional map in the infinite population limit. Stochastic fluctuations are therefore internal to the system and not externally specified. For finite populations an approximate Gaussian scheme is devised to describe the stochastic fluctuations in the non-chaotic regime. More generally, the stochastic dynamics can be captured using a stochastic difference equation, derived through an approximation to the Markov chain. The scheme is demonstrated using the logistic map as a case study.Comment: Modified version accepted for publication in Phys. Rev. E Rapid Communications. New figures adde

The influence of a full-time, immersive simulation-based clinical placement on physiotherapy student confidence during the transition to clinical practice

Background: Novice students may have limited learning opportunities during their early exposure to complex clinical environments, due to the priorities of patient care. Immersive, high-fidelity simulation provides an opportunity for physiotherapy students to be exposed to relatively complex scenarios in a safe learning environment before transitioning to the clinical setting. The present study evaluated the influence of immersive simulation on student confidence and competence. Methods: Sixty penultimate year physiotherapy students completed an 18-day full-time immersive simulation placement. The placement involved students spending 6 days working in each of three core practice areas (cardiopulmonary, musculoskeletal, neurological) in which they interacted with simulated patients portrayed by professional role-play actors. The patient scenarios were developed by groups of expert practitioners and incorporated full documentary and imaging information. Students completed a questionnaire to evaluate their confidence in the clinical environment at the start and completion of each 6-day rotation. Their clinical competence was evaluated at the end of each 6-day rotation using the Assessment of Physiotherapy Practice (APP) tool. In a secondary analysis, the clinical competence of this cohort was evaluated in comparison to a matched cohort of students from the same year group that had not completed an immersive simulation placement. Results: Student confidence improved significantly in each 6-day rotation (p < 0.001); however, it reduced again at the commencement of the next rotation, and there was no cumulative improvement in confidence over the 18-day placement (p = 0.22). Students who had completed the immersive simulation placement achieved higher APP (p < 0.001) scores in an evaluation of their competence to practice during their subsequent clinical placement. Conclusion: Immersive simulation provides a beneficial learning environment to enable physiotherapy students to transition from university-based education to working in the clinical environment

Experimental evidence that shear bands in metallic glasses nucleate like cracks

Highly time-resolved mechanical measurements, modeling, and simulations show that large shear bands in bulk metallic glasses nucleate in a manner similar to cracks. When small slips reach a nucleation size, the dynamics changes and the shear band rapidly grows to span the entire sample. Smaller nucleation sizes imply lower ductility. Ductility can be increased by increasing the nucleation size relative to the maximum (“cutoff”) shear band size at the upper edge of the power law scaling range of their size distribution. This can be achieved in three ways: (1) by increasing the nucleation size beyond this cutoff size of the shear bands, (2) by keeping all shear bands smaller than the nucleation size, or (3) by choosing a sample size smaller than the nucleation size. The discussed methods can also be used to rapidly order metallic glasses according to ductility

Ex-vivo HRMAS of adult brain tumours: metabolite quantification and assignment of tumour biomarkers

Background: High-resolution magic angle spinning (HRMAS) NMR spectroscopy allows detailed metabolic analysis of whole biopsy samples for investigating tumour biology and tumour classification. Accurate biochemical assignment of small molecule metabolites that are “NMR visible” will improve our interpretation of HRMAS data and the translation of NMR tumour biomarkers to in-vivo studies. Results: 1D and 2D 1H HRMAS NMR was used to determine that 29 small molecule metabolites, along with 8 macromolecule signals, account for the majority of the HRMAS spectrum of the main types of brain tumour(astrocytoma grade II, grade III gliomas, glioblastomas, metastases, meningiomas and also lymphomas). Differences in concentration of 20 of these metabolites were statistically significant between these brain tumour types. During the course of an extended 2D data acquisition the HRMAS technique itself affects sample analysis: glycine, glutathione and glycerophosphocholine all showed small concentration changes; analysis of the sample after HRMAS indicated structural damage that may affect subsequent histopathological analysis. Conclusions: A number of small molecule metabolites have been identified as potential biomarkers of tumour type that may enable development of more selective in-vivo 1H NMR acquisition methods for diagnosis and prognosis of brain tumours

Using mixed methods for analysing culture : The Cultural Capital and Social Exclusion project

This paper discusses the use of material generated in a mixed method investigation into cultural tastes and practices, conducted in Britain from 2003 to 2006, which employed a survey, focus groups and household interviews. The study analysed the patterning of cultural life across a number of fields, enhancing the empirical and methodological template provided by Bourdieu’s Distinction. Here we discuss criticisms of Bourdieu emerging from subsequent studies of class, culture and taste, outline the arguments related to the use of mixed methods and present illustrative results from the analysis of these different types of data. We discuss how the combination of quantitative and qualitative methods informed our analysis of cultural life in contemporary Britain. No single method was able to shed light on all aspects of our inquiry, lending support to the view that mixing methods is the most productive strategy for the investigation of complex social phenomena