Icing simulation: A survey of computer models and experimental facilities

A survey of the current methods for simulation of the response of an aircraft or aircraft subsystem to an icing encounter is presented. The topics discussed include a computer code modeling of aircraft icing and performance degradation, an evaluation of experimental facility simulation capabilities, and ice protection system evaluation tests in simulated icing conditions. Current research focussed on upgrading simulation fidelity of both experimental and computational methods is discussed. The need for increased understanding of the physical processes governing ice accretion, ice shedding, and iced airfoil aerodynamics is examined

Guiding center model to interpret neutral particle analyzer results

The theoretical model is discussed, which accounts for drift and cyclotron components of ion motion in a partially ionized plasma. Density and velocity distributions are systematically precribed. The flux into the neutral particle analyzer (NPA) from this plasma is determined by summing over all charge exchange neutrals in phase space which are directed into apertures. Especially detailed data, obtained by sweeping the line of sight of the apertures across the plasma of the NASA Lewis HIP-1 burnout device, are presented. Selection of randomized cyclotron velocity distributions about mean azimuthal drift yield energy distributions which compared well with experiment. Use of data obtained with a bending magnet on the NPA showed that separation between energy distribution curves of various mass species correlate well with a drift divided by mean cyclotron energy parameter of the theory. Use of the guiding center model in conjunction with NPA scans across the plasma aid in estimates of ion density and E field variation with plasma radius

Hot ion plasma heating experiments in SUMMA

Initial results are presented for the hot-ion plasma heating experiments conducted in the new SUMMA (superconducting magnetic mirror apparatus) at NASA Lewis Research Center. A discharge is formed by applying a radially inward dc electric field between cylindrical anodes and hallow cathodes located at the peak of the mirrors. Data were obtained at midplane magnetic field strengths from 1.0 to 3.5 tesla. Charge-exchange neutral particle energy analyzer data were reduced to ion temperatures using a plasma model that included a Maxwellian energy distribution superimposed on an azimuthal drift, finite ion orbits, and radial variations in density and electric field. The best ion temperatures in a helium plasma were 5 keV and in hydrogen the H2(+) and H(+) ions were 1.2 keV and 1 keV respectively. Optical spectroscopy line broadening measurements yielded ion temperatures about 50 percent higher than the charge-exchange neutral particle analyzer results. Spectroscopically obtained electron temperature ranged from 3 to 30 eV. Ion temperature was found to scale roughly linearly with the ratio of power input-to-magnetic field strength, P/B

Electric multipole plasmons in deformed sodium clusters

The random-phase-approximation (RPA) method with separable residual forces (SRPA) is proposed for the description of multipole electric oscillations of valence electrons in deformed alkali metal clusters. Both the deformed mean field and residual interaction are derived self-consistently from the Kohn-Sham functional. SRPA drastically simplifies the computational effort which is urgent if not decisive for deformed systems. The method is applied to the description of dipole, quadrupole and octupole plasmons in deformed sodium clusters of a moderate size. We demonstrate that, in clusters with the size N>50, Landau damping successfully competes with deformation splitting and even becomes decisive in forming the width and gross structure of the dipole plasmon. Besides, the plasmon is generated by excitations from both ground state and shape isomers. In such clusters familiar experimental estimates for deformation splitting of dipole plasmon are useless.Comment: 27 pages, 10 figure

The significance of trust in the political system and motivation for pupils' learning progress in politics lessons

Very little research has been conducted on the contribution of political education to learning progress in Germany. Hence, there is a need for intervention studies measuring performance against the theoretical background of a political competence model. This model comprises three constructs: subject knowledge, motivation and attitudes. According to this model, politics lessons should not only convey knowledge but also arouse subject interest, promote political attitudes and develop problem-solving skills. This study investigates how knowledge acquisition is influenced by intervention using theory-oriented teaching materials on the European Union, intervention using conventional textbooks on the European Union and politics lessons without any reference to the European Union. It further asks how the performance-related self-concept and subject interest in political issues impact political knowledge and whether civic virtue and trust in the system are related to it. The sample comprises 1071 pupils. Theory-oriented politics classes lead to greater growth of pupils’ knowledge than in the control group. As anticipated, this study proves that a positive subject-specific self-concept impacts knowledge. The examination of political attitudes reveals a positive correlation between civic virtue and knowledge. There is no connection between trust in the political system and knowledge

Konstruktivistische Ansätze in der Erwachsenenbildung und Weiterbildung

Theoretical approaches in the field of further education and advanced vocational training have to face multifaceted demands: the analysis of knowledge aquisition and knowledge transfer and its instructional support as well as the revealment of the mechanisms which influence further education on an organisational level in companies. This article describes, that herefore especially moderate constructivistic approaches are useful. After an introduction to the philosophical tradition of these approaches and important characteristics of adult learning, two examples of constructivistic models are being described particularly: The theory of situated learning environments and career counseling. Concluding it is shown, that a moderate constructive perspective fulfils important criteria for the theoretic modelling of further education processes.Theoretische Ansätze in der Erwachsenen- und insbesondere in der beruflichen Weiterbildung müssen sich vielfältigen Ansprüchen stellen: der Analyse des Wissenserwerbs und Wissenstransfers und seiner instruktionalen Unterstützung ebenso wie der Aufdeckung der Mechanismen, die in den Betrieben auf organisatorischer Ebene die Weiterbildung beeinflussen. In diesem Beitrag wird die Auffassung vertreten, daß dafür insbesondere liberalisierte konstruktivistische Ansätze gut geeignet sind. Nach einer Einführung in die philosophische Tradition dieser Ansätze und wichtiger Merkmale des Lernens im Erwachsenenalter werden zwei Beispiele konstruktivistischer Modelle genauer beschrieben: die Theorie situierter Lernumgebungen und das career counseling. Abschließend wird gezeigt, daß eine liberalisierte konstruktivistische Perspektive wichtige Kriterien für die theoretische Modellierung von Weiterbildungsprozessen erfüllt

Beyond arctic and alpine: the influence of winter climate on temperate ecosystems

Winter climate is expected to change under future climate scenarios, yet the majority of winter ecology research is focused in cold-climate ecosystems. In many temperate systems, it is unclear how winter climate relates to biotic responses during the growing season. The objective of this study was to examine how winter weather relates to plant and animal communities in a variety of terrestrial ecosystems ranging from warm deserts to alpine tundra. Specifically, we examined the association between winter weather and plant phenology, plant species richness, consumer abundance, and consumer richness in 11 terrestrial ecosystems associated with the U.S. Long-Term Ecological Research (LTER) Network. To varying degrees, winter precipitation and temperature were correlated with all biotic response variables. Bud break was tightly aligned with end of winter temperatures. For half the sites, winter weather was a better predictor of plant species richness than growing season weather. Warmer winters were correlated with lower consumer abundances in both temperate and alpine systems. Our findings suggest winter weather may have a strong influence on biotic activity during the growing season and should be considered in future studies investigating the effects of climate change on both alpine and temperate systems.This is the publisher’s final pdf. The published article is copyrighted by the Ecological Society of America and can be found at: http://esajournals.onlinelibrary.wiley.com/hub/journal/10.1002/%28ISSN%291939-9170/Keywords: ecosystem stability, temperate ecosystem, US LTER Network, global change, critical climate periods, winterKeywords: ecosystem stability, temperate ecosystem, US LTER Network, global change, critical climate periods, winte

Blended Learning in Higher Education: Theory and Praxis

Recent studies are showing that ‘blended learning’ is more than a mix between face-to-face and online education, or in other words: a mix of traditional and computer-based education. Blended learning seems to include mixtures between eLearning and other ways of learning, where the right choices have to be made in the distribution of learning content, didactical approaches, ways of communicating and characteristics of learning environments, in the perspective of the type of learning process and characteristics of students. This symposium provides evidence from qualitative studies of blended learning in practical situations, drawing on tutors’ and students’ perspectives, contrasted with theoretical ideas. Attention is focused on assessment in blended learning environments and the use of ePortfolios to align learning, teaching and assessment when new educational approaches are implemented. Also, research on the roles and effectiveness of the eTutor in blended learning will be presented, focussing on academic learning and social integration. Furthermore, attention is focussed on blended strategies in problem-based learning by presenting recent case study research on a postgraduate course for academic staff in ‘eLearning design’. Also, a redesign of the initial teacher training curriculum will be presented, offering different routes for groups of students according to their need of flexibility and support. Finally, a framework is offered for determining the quality of reflection reports in a blended learning environment. In sum, the concept of blended learning is studied from the main perspectives according to learning processes: designing a learning process, supporting a learning process and assessing a learning process. The discussant will go into issues like the design, deliverance, support and evaluation of the presented projects, the degree of internal locus of control for the learners, the assessment methods and tutor and student perceptions on interactions

Blended Learning in Higher Education: Theory and Praxis

Recent studies are showing that ‘blended learning’ is more than a mix between face-to-face and online education, or in other words: a mix of traditional and computer-based education. Blended learning seems to include mixtures between eLearning and other ways of learning, where the right choices have to be made in the distribution of learning content, didactical approaches, ways of communicating and characteristics of learning environments, in the perspective of the type of learning process and characteristics of students. This symposium provides evidence from qualitative studies of blended learning in practical situations, drawing on tutors’ and students’ perspectives, contrasted with theoretical ideas. Attention is focused on assessment in blended learning environments and the use of ePortfolios to align learning, teaching and assessment when new educational approaches are implemented. Also, research on the roles and effectiveness of the eTutor in blended learning will be presented, focussing on academic learning and social integration. Furthermore, attention is focussed on blended strategies in problem-based learning by presenting recent case study research on a postgraduate course for academic staff in ‘eLearning design’. Also, a redesign of the initial teacher training curriculum will be presented, offering different routes for groups of students according to their need of flexibility and support. Finally, a framework is offered for determining the quality of reflection reports in a blended learning environment. In sum, the concept of blended learning is studied from the main perspectives according to learning processes: designing a learning process, supporting a learning process and assessing a learning process. The discussant will go into issues like the design, deliverance, support and evaluation of the presented projects, the degree of internal locus of control for the learners, the assessment methods and tutor and student perceptions on interactions