Flow establishment in a generic scramjet combustor

The establishment of a quasi-steady flow in a generic scramjet combustor was studied for the case of a time varying inflow to the combustor. Such transient flow is characteristic of the reflected shock tunnel and expansion tube test facilities. Several numerical simulations of hypervelocity flow through a straight duct combustor with either a side wall step fuel injector or a centrally located strut injector are presented. Comparisons were made between impulsively started but otherwise constant flow conditions (typical of the expansion tube or tailored operations of the reflected shock tunnel) and the relaxing flow produced by the 'undertailored' operations of the reflected shock tunnel. Generally the inviscid flow features, such as the shock pattern and pressure distribution, were unaffected by the time varying inlet conditions and approached steady state in approx. the times indicated by experimental correlations. However, viscous features, such as heat transfer and skin friction, were altered by the relaxing inlet flow conditions

Low-rank approximations of nonseparable panel models

We provide estimation methods for nonseparable panel models based on low-rank factor structure approximations. The factor structures are estimated by matrix-completion methods to deal with the computational challenges of principal component analysis in the presence of missing data. We show that the resulting estimators are consistent in large panels, but suffer from approximation and shrinkage biases. We correct these biases using matching and difference-in-differences approaches. Numerical examples and an empirical application to the effect of election day registration on voter turnout in the US illustrate the properties and usefulness of our methods

Evaluating uniform manifold approximation and projection for dimension reduction and visualization of polinsar features

In this paper, the nonlinear dimension reduction algorithm Uniform Manifold Approximation and Projection (UMAP) is investigated to visualize information contained in high dimensional feature representations of Polarimetric Interferometric Synthetic Aperture Radar (PolInSAR) data. Based on polarimetric parameters, target decomposition methods and interferometric coherences a wide range of features is extracted that spans the high dimensional feature space. UMAP is applied to determine a representation of the data in 2D and 3D euclidean space, preserving local and global structures of the data and still suited for classification. The performance of UMAP in terms of generating expressive visualizations is evaluated on PolInSAR data acquired by the F-SAR sensor and compared to that of Principal Component Analysis (PCA), Laplacian Eigenmaps (LE) and t-distributed Stochastic Neighbor embedding (t-SNE). For this purpose, a visual analysis of 2D embeddings is performed. In addition, a quantitative analysis is provided for evaluating the preservation of information in low dimensional representations with respect to separability of different land cover classes. The results show that UMAP exceeds the capability of PCA and LE in these regards and is competitive with t-SNE

Intrinsisch ungeordnete Osteopontin-Fragmente ordnen sich während der interfazialen Calciumoxalat-Mineralisierung

Calcium oxalate (CaC(2)O(4)) is the major component of kidney stone. The acidic osteopontin (OPN) protein in human urine can effectively inhibit the growth of CaC(2)O(4) crystals, thereby acting as a potent stone preventer. Previous studies in bulk solution all attest to the importance of binding and recognition of OPN at the CaC(2)O(4) mineral surface, yet molecular level insights into the active interface during CaC(2)O(4) mineralization are still lacking. Here, we probe the structure of the central OPN fragment and its interaction with Ca(2+) and CaC(2)O(4) at the water–air interface using surface‐specific non‐linear vibrational spectroscopy. While OPN peptides remain largely disordered in solution, our results reveal that the bidentate binding of Ca(2+) ions refold the interfacial peptides into well‐ordered and assembled β‐turn motifs. One critical intermediate directs mineralization by releasing structural freedom of backbone and binding side chains. These insights into the mineral interface are crucial for understanding the pathological development of kidney stones and possibly relevant for calcium oxalate biomineralization in general

Arbeit und Ökologie: Ein neues Forschungsprogramm

Die Gewerkschaften haben im DGB-Grundsatzprogramm von 1996 die Gestaltung einer nachhaltigen Entwicklung zu einer wichtigen Aufgabe erklärt. lhre Suche nach einer sozial-ökologischen Reformstrategie steht unter der Prämisse, daß ökonomische, ökologische und soziale Nachhaltigkeitsziele gleichwertig verfolgt werden müssen, wobei erhebliche Defizite bei der Berücksichtigung der sozialen Dimension von Nachhaltigkeitskonzepten konstatiert werden. Vor diesem Hintergrund haben sich die drei Forschungsinstitute DIW, WI und WZB mit ihren jeweils spezifischen fachlichen Kompetenzbereichen zum Forschungsprojektverbund "Arbeit und Ökologie" zusammengetan. Dessen Hauptziel ist es, soziale und arbeitspolitische Aspekte in ihrer Wechselwirkung mit zentralen Elementen von unterschiedlich akzentuierten Nachhaltigkeitskonzepten zu untersuchen. Damit soll die Diskussion in Deutschland mit neuen Aspekten belebt und den Gewerkschaften eine fundierte Grundlage für ihren Strategiebildungsprozeß geboten werden. Dabei wird sich das Forschungsprojekt auf drei Leitfragestellungen konzentrieren: (1) das Verhältnis zwischen den sozialen Implikationen von Nachhaltigkeitsstrategien und gewerkschaftlichen Zielen, (2) die Bausteine einer sozial-ökologischen Reformstrategie und (3) die Rolle der deutschen Gewerkschaften in einem gesellschaftlichen Nachhaltigkeitsdiskurs. Das Projekt ist in die folgenden drei, zeitlich gestaffelten Phasen gegliedert: Querschnittsanalysen: Sie dienen der Erfassung und Klärung der vielfaltigen Wechselbeziehungen zwischen Nachhaltigkeit und Arbeit, die sich aus ökonomischer, sozialer und ökologischer Sicht ergeben. Hierbei wird es auf der Makroebene etwa um Fragen von Wirtschaftswachstum, Beschäftigungsentwicklung, sozialer Sicherheit und Ressourcenverbrauch gehen; auf der Mikroebene werden neue Arbeitsverhältnisse und Arbeitszeiten, das Verhältnis von formeller und informeller Arbeit, sowie sozialökologische Innovationspotentiale untersucht. Die Analyseergebnisse sollen Grundlagen für die Beurteilung von Szenarien schaffen und die Formulierung von Strategien unterstützen. Szenarioanalysen: Um dem Spektrum verschiedener Positionen in der Nachhaltigkeitsdiskussion gerecht zu werden, sollen zwei unterschiedliche Nachhaltigkeitsszenarien entwickelt und analysiert werden. Das sogenannte ökonomisch- soziale Szenario geht von der ökonomischen Kritik an der vorherrschenden Wirtschaftspolitik aus, während das sogenannte ökologisch-soziale Szenario auf der ökologischen Kritik vorherrschender umweltrelevanter Politikmuster basiert. Als Hintergrundfolie für die Beurteilung dieser beiden Nachhaltigkeitsszenarien dient ein sog. angebots orientiertes Kontrastszenario, das auf einer Fortschreibung bisher dominierender wirtschaftspolitischer Konzepte beruht. Erarbeitung von Strategieelementen: Die Bewertung der Szenarien nach (aus den Querschnittsanalysen gewonnenen) ökonomischen, ökologischen und sozialen Kriterien soll Zielkonflikte und - Synergien aufdecken und damit der Strategieformulierung dienen. Diese können - gemeinsam mit weiteren Strategieelementen, die aus der Analyse von Konfliktpotentialen und aus den Querschnittsanalysen gewonnen wurden - einen Beitrag für die Entwicklung einer gewerkschaftlichen sozial-ökologischen Reformstrategie liefern. -- In its Basic Programme published in 1996, the German trade union movement declared the shaping of a sustainable development to be an important task. The trade unions seek to pursue a social-ecological reform strategy that takes account of the need to strike a balance between economic, ecological and social sustainability objectives, while serious deficits in the consideration of social dimension of concepts of sustainable are being stated. Against this background, three research institutions (DIW, WI and WZB) with their complementary specialist qualifications and know-how in the relevant disciplines have joined to the Research Network Project "Work and Ecology". Their major objective is to analyse social and labour-related aspects in correlation with central elements of various sustainable development concepts in different perspectives. This aims at stimulating the German discussion with new arguments and establishing a solid base for strategybuilding-process ofthe trade unions. The research project will concentrate on three guiding questions: (I) The relationship between the social implications of sustainability strategies and trade union goals; (2) possible building blocks in a social-ecological reform strategy and (3) the role of German trade unions in a social discourse on sustainability. The project is planned to be accomplished in three main broadly successive working phases: Cross-sectional analyses: The aim of the cross-sectional analyses is to determine and specify the various linkages and interrelationships between sustainability and work seen from an economic, social and ecological perspective. This implies e. g. focussing on questions such as economic growth, the development of employment, social security and resource use on a macro-Ievel, and questions of new labour relations and working time, the relation between formal and informal work and social-ecologial innovation potentials on a micro-Ievel. The cross-sectional analyses are both to provide a basis for drawing up and evaluating the scenarios and to generate findings that can help directly in formulating social-ecological strategy elements. Scenario analyses: In order to take account of the spectrum of positions held in the debate on sustainable development concepts, the research project is to develop and analyse an economic-social and an ecological-social sustainability scenario. The so-called economic-social sustainable development scenario takes up the economic critique of the predominant one-sided orientation of economic policy to the supply side, while the socalled ecological-social sustainable development scenario is based on the critique of the prevailing policy approach regarding the environment. A supply-side scenario based on an extrapolation of the supply-side economic policy concepts, that have been predominant in German politics, will serve as the background evaluationpattern for the two sustainabilty scenarios.

Using virtual reality for science mission planning: A Mars Pathfinder case

NASA's Mars Pathfinder Project requires a Ground Data System (GDS) that supports both engineering and scientific payloads with reduced mission operations staffing, and short planning schedules. Also, successful surface operation of the lander camera requires efficient mission planning and accurate pointing of the camera. To meet these challenges, a new software strategy that integrates virtual reality technology with existing navigational ancillary information and image processing capabilities. The result is an interactive workstation based applications software that provides a high resolution, 3-dimensial, stereo display of Mars as if it were viewed through the lander camera. The design, implementation strategy and parametric specification phases for the development of this software were completed, and the prototype tested. When completed, the software will allow scientists and mission planners to access simulated and actual scenes of Mars' surface. The perspective from the lander camera will enable scientists to plan activities more accurately and completely. The application will also support the sequence and command generation process and will allow testing and verification of camera pointing commands via simulation