Expectation and variation with a virtual die

By the time students reach the middle years they have experienced many chance activities based on dice. Common among these are rolling one die to explore the relationship of frequency and theoretical probability, and rolling two dice and summing the outcomes to consider their probabilities. Although dice may be considered overused by some, the advantage they offer is a familiar context within which to explore much more complex concepts. If the basic chance mechanism of the device is understood, it is possible to enter quickly into an arena of more complex concepts. This is what happened with a two hour activity engaged in by four classes of Grade 6 students in the same school. The activity targeted the concepts of variation and expectation. The teachers held extended discussions with their classes on variation and expectation at the beginning of the activity, with students contributing examples of the two concepts from their own experience. These notions are quite sophisticated for Grade 6, but the underlying concepts describe phenomena that students encounter every day. For example, time varies continuously; sporting results vary from game to game; the maximum temperature varies from day to day. However, there is an expectation about tomorrow’s maximum temperature based on the expert advice from the weather bureau. There may also be an expectation about a sporting result based on the participants’ previous results. It is this juxtaposition that makes life interesting. Variation hence describes the differences we see in phenomena around us. In a scenario displaying variation, expectation describes the effort to characterise or summarise the variation and perhaps make a prediction about the message arising from the scenario. The explicit purpose of the activity described here was to use the familiar scenario of rolling a die to expose these two concepts. Because the students had previously experienced rolling physical dice they knew instinctively about the variation that occurs across many rolls and about the theoretical expectation that each side should “come up” one-sixth of the time. They had observed the instances of the concepts in action, but had not consolidated the underlying terminology to describe it. As the two concepts are so fundamental to understanding statistics, we felt it would be useful to begin building in the familiar environment of rolling a die. Because hand-held dice limit the explorations students can undertake, the classes used the soft-ware TinkerPlots (Konold & Miller, 2011) to simulate rolling a die multiple times.

Metadaten für Open Educational Resources (OER). Eine Handreichung für die öffentliche Hand, erstellt von der Technischen Informationsbibliothek (TIB)

"Im Zuge der weiteren Verbreitung der Social Media und der internetbasierten Lehre, gewinnen eLearning Inhalte immer mehr an Bedeutung. In den Kontext von eLearning und internetbasierter Lehre gehören auch Open Educational Resources (OER). OER sind digitale Lern- und Lehrmaterialien, die frei für Lehrende und Studierende zugänglich sind und auch frei verbreitet werden dürfen. [...] Um OER auszutauschen, zu finden, zu beschaffen und sie auf einer breiten Basis zugänglich zu machen, insbesondere auch über Suchmaschinen und dadurch verwenden zu können, werden für die jeweiligen Materialien Metadaten benötigt. [...] Um die Frage nach dem Handlungs- und Forschungsbedarf zum Thema Metadaten für Open Educational Resources zu untersuchen, wird zunächst ein Überblick über die momentan bestehenden nationalen und internationalen Metadatenstandards für eLearning Objekte gegeben. [...] Hieraus ergeben sich Empfehlungen, welche Metadaten-Standards für die weitere Nutzung und Förderung geeignet sein könnten. Es werden außerdem die Möglichkeiten der Erstellung eines neuen Metadaten-Standards sowie eines gemeinsamen Portals für OER erörtert. Hierbei wird vor allem auf die zu erwartenden Probleme und die damit verbundenen Anforderungen eingegangen." (DIPF/Orig.)

Determination of the heat transfer coefficient at the metal–die interface for high pressure die cast AlSi9Cu3Fe

When simulating the High Pressure Die Casting ‘HPDC’ process, the heat transfer coefficient ‘HTC’ between the casting and the die is critical to accurately predict the quality of the casting. To determine the HTC at the metal–die interface a production die for an automotive engine bearing beam, Die 1, was instrumented with type K thermocouples. A Magmasoft® simulation model was generated with virtual thermocouple points placed in the same location as the production die. The temperature traces from the simulation model were compared to the instrumentation results. Using the default simulation HTC for the metal–die interface, a poor correlation was seen, with the temperature response being much less for the simulation model. Because of this, the HTC at the metal–die interface was modified in order to get a better fit. After many simulation iterations, a good fit was established using a peak HTC of 42,000 W/m2 K, this modified HTC was further validated by a second instrumented production die, proving that the modified HTC gives good correlation to the instrumentation trials. The updated HTC properties for the simulation model will improve the predictive capabilities of the casting simulation software and better predict casting defects.

A virtual inspection framework for precision manufacturing of aerofoil components

The finite element method plays an extremely important role in forging process design as it provides a valid means to quantify forging errors and thereby govern die shape modification to improve the dimensional accuracy of the component. However, this dependency on process simulation could raise significant problems and present a major drawback if the finite element simulation results were inaccurate. This paper presents a novel approach to assess the dimensional accuracy and shape quality of aeroengine blades formed from finite element hot-forging simulation. The proposed virtual inspection system uses conventional algorithms adopted by modern coordinate measurement processes as well as the latest free-form surface evaluation techniques to provide a robust framework for virtual forging error assessment. Established techniques for the physical registration of real components have been adapted to localise virtual models in relation to a nominal Design Coordinate System. Blades are then automatically analysed using a series of intelligent routines to generate measurement data and compute dimensional errors. The results of a comparison study indicate that the virtual inspection results and actual coordinate measurement data are highly comparable, validating the approach as an effective and accurate means to quantify forging error in a virtual environment. Consequently, this provides adequate justification for the implementation of the virtual inspection system in the virtual process design, modelling and validation of forged aeroengine blades in industry.

Nutzbarkeit virtueller sozialer Netzwerke für die Personalauswahl

Virtuelle soziale Netzwerke gewinnen im Bereich des Human Resource Managements zunehmend an Bedeutung. In der vorliegenden Arbeit wird die Nutzbarkeit von virtuellen sozialen Netzwerken für die Personalauswahl untersucht. Beginnend mit einer Einführung in die virtuellen sozialen Netzwerke liegt der Schwerpunkt dieser Arbeit in der Prüfung verschiedener virtueller sozialer Netzwerke auf die Nutzbarkeit für die Personalauswahl. Hierbei wird das Hauptaugenmerk auf StudiVZ, ein virtuelles soziales Netzwerk mit der Zielgruppe Studenten, gelegt. Abschließend erfolgen eine Detailanalyse eines StudiVZProfils und eine Analyse der Aussagekraft über die Persönlichkeit des Nutzers.

Digital unterwegs ohne das virtuelle soziale Netzwerk – qualitative Studie über Facebook-Verweigerung und Virtual Identity Suicide

Das virtuelle soziale Netzwerk Facebook feiert seinen zehnten Geburtstag. Mit über einer Milliarde aktiver Nutzer ist es seit seiner Entstehung zur weltweit größten Internetplattform zur Kommunikation avanciert. Dennoch gibt es in Deutschland eine große Anzahl an Menschen, die sich zwar täglich im Internet bewegt, aber auf eine Mitgliedschaft bei Facebook verzichtet. In dieser Arbeit werden die Gründe untersucht, warum manche Personen Facebook nicht nutzen. Die Leitfrage der Arbeit lautet: „Warum nutzen ausgewählte deutsche Internetnutzer Facebook nicht?“. Es wird zwischen zwei unterschiedlichen Personenkreisen, den Nicht- und den Ex-Nutzern, unterschieden. Basierend auf Leitfadeninterviews mit 25 Befragten, die mittels einer qualitativen Inhaltsanalyse ausgewertet werden, werden elf verschiedene Gründe für eine Verweigerung von Facebook identifiziert. Für die Nicht-Nutzer stellt die Art der Kommunikation den zentralen Grund dar, Facebook nicht zu verwenden. Die Ex-Nutzer wiederum sehen den fehlenden Nutzen der Anwendung als wichtigstes Argument gegen Facebook.

O ambiente virtual na formação inicial de professores de alemão como apoio para o ensino e a aprendizagem da língua e a reflexão sobre ações docentes

Estudiosos dos campos da Educação, da Linguística Aplicada e da Formação de Professores de Línguas insistem hoje na grande importância da inclusão de Tecnologias de Informação e Comunicação (TICs) na formação inicial, bem como na necessidade de promover o desenvolvimento do pensamento crítico-reflexivo dos futuros professores. Tomando como pressupostos teóricos estudos acerca das características da sociedade de informação, dos ambientes virtuais e da formação de professores, este trabalho tem como objetivo discutir possibilidades oferecidas pela plataforma Moodle de aprendizagem na formação inicial de professores de alemão. Para tanto, apresentaremos diferentes formas de uso de ambientes virtuais e de ferramentas neles disponíveis, que demonstraram ser de grande valor no processo de formação de licenciandos, tanto em língua alemã, quanto durante suas práticas iniciais. As experiências apontam para um valor inestimável de ambientes virtuais no acompanhamento de licenciandos no processo de aprendizagem da língua e nas primeiras experiências com a docência.

Polarization observables in virtual compton scattering

Virtual Compton Scattering (VCS) is an important reaction for understanding nucleon structure at low energies. By studying this process, the generalized polarizabilities of the nucleon can be measured. These observables are a generalization of the already known polarizabilities and will permit theoretical models to be challenged on a new level. More specifically, there exist six generalized polarizabilities and in order to disentangle them all, a double polarization experiment must be performed. Within this work, the VCS reaction p(e,e p)gamma was measured at MAMI using the A1 Collaboration three spectrometer setup with Q2=0.33 (GeV/c)2. Using the highly polarized MAMI beam and a recoil proton polarimeter, it was possible to measure both the VCS cross section and the double polarization observables. Already in 2000, the unpolarized VCS cross section was measured at MAMI. In this new experiment, we could confirm the old data and furthermore the double polarization observables were measured for the first time. The data were taken in five periods between 2005 and 2006. In this work, the data were analyzed to extract the cross section and the proton polarization. For the analysis, a maximum likelihood algorithm was developed together with the full simulation of all the analysis steps. The experiment is limited by the low statistics due mainly to the focal plane proton polarimeter efficiency. To overcome this problem, a new determination and parameterization of the carbon analyzing power was performed. The main result of the experiment is the extraction of a new combination of the generalized polarizabilities using the double polarization observables.

Deeply virtual Compton scattering in a relativistic quark model

This thesis is mainly concerned with a model calculation for generalized parton distributions (GPDs). We calculate vectorial- and axial GPDs for the N N and N Delta transition in the framework of a light front quark model. This requires the elaboration of a connection between transition amplitudes and GPDs. We provide the first quark model calculations for N Delta GPDs. The examination of transition amplitudes leads to various model independent consistency relations. These relations are not exactly obeyed by our model calculation since the use of the impulse approximation in the light front quark model leads to a violation of Poincare covariance. We explore the impact of this covariance breaking on the GPDs and form factors which we determine in our model calculation and find large effects. The reference frame dependence of our results which originates from the breaking of Poincare covariance can be eliminated by introducing spurious covariants. We extend this formalism in order to obtain frame independent results from our transition amplitudes.

Virtual Compton scattering in baryon chiral perturbation theory

This thesis is concerned with the calculation of virtual Compton scattering (VCS) in manifestly Lorentz-invariant baryon chiral perturbation theory to fourth order in the momentum and quark-mass expansion. In the one-photon-exchange approximation, the VCS process is experimentally accessible in photon electro-production and has been measured at the MAMI facility in Mainz, at MIT-Bates, and at Jefferson Lab. Through VCS one gains new information on the nucleon structure beyond its static properties, such as charge, magnetic moments, or form factors. The nucleon response to an incident electromagnetic field is parameterized in terms of 2 spin-independent (scalar) and 4 spin-dependent (vector) generalized polarizabilities (GP). In analogy to classical electrodynamics the two scalar GPs represent the induced electric and magnetic dipole polarizability of a medium. For the vector GPs, a classical interpretation is less straightforward. They are derived from a multipole expansion of the VCS amplitude. This thesis describes the first calculation of all GPs within the framework of manifestly Lorentz-invariant baryon chiral perturbation theory. Because of the comparatively large number of diagrams - 100 one-loop diagrams need to be calculated - several computer programs were developed dealing with different aspects of Feynman diagram calculations. One can distinguish between two areas of development, the first concerning the algebraic manipulations of large expressions, and the second dealing with numerical instabilities in the calculation of one-loop integrals. In this thesis we describe our approach using Mathematica and FORM for algebraic tasks, and C for the numerical evaluations. We use our results for real Compton scattering to fix the two unknown low-energy constants emerging at fourth order. Furthermore, we present the results for the differential cross sections and the generalized polarizabilities of VCS off the proton.

Das Internet als Forschungsinstrument für die Afrikanistik

L’internet est reconnue de manière générale comme un instrument de recherche valable. Bien que les langues africaines ne soient pas bien représentées sur internet il y a assez d’informations qui peuvent être découvertes dans la recherche sur terrain virtuel. Des petits vocabulaires et des descriptions de plusieurs langues africaines sont écrits par des auteurs individuels, des départements d’universités et des agences de voyages. Des textes en langues africaines sont en majorité publiés par des missionaries ou des ONGs. Ces données tendent à refléter les variantes standards des langues utilisées. Ce sont des contributions dans des forums qui sont témoins d’un langage proche de la langue parlée. On recherche les données linguistiques en utilisant les noms des langues respectives combinés avec des termes tels que “langue”, “grammaire”, “cours” ou le nom d’un auteur comme terme de recherche. Des chaînes de mots (en guillemets) qui sont très courantes dans le langage parlé et/ou écrit peuvent constituer de bons termes de recherche pour trouver des textes ou des contributions dans des forums.

Modelle und Prototypen für die Medizin

Der Anwendungsbereich für Modelle und Prototypen hat sich mittlerweile auch auf unterschiedlichste medizinische Fragestellungen ausgedehnt. Der vorliegende Beitrag zeigt an verschiedenen Praxisbeispielen und Verfahren Möglichkeiten eines in der Technik etablierten Verfahrens für eine erweiterte Anwendung auf.

Rechtliche Grundlagen für die Ernährungssicherheit in der Schweiz

The Right to Food, as enshrined in international law, has found its way into national constitutions and practices. What matters from a national and international legal point of view is how this policy objective is implemented. In Switzerland, a number of policies and their instruments are relevant here, namely agricultural, supply/stockpile, trade and development policies. This paper (in German) asks whether the policy instruments are coherent and how implementation conflicts and negative spill-over effects could be minimised. It finds that the four policy objectives enshrined in the Federal Constitution are not in themselves incoherent. However, certain Swiss agricultural policy instruments, even where they are compatible with relevant rules of the World Trade Organization (WTO), do have an avoidable negative impact on the Right to Food of developing country producers, because Swiss Food Security is overwhelmingly and increasingly defined by agricultural (self-reliance) policies (“Food Sovereignty”). This implies higher domestic food prices, commercial displacement and food dumping. The conclusions suggest a number of optimisations as a contribution to the presently on-going reform process for 1983 National Economic Supply Act 1983 (NESA), such as virtual stockpiles and taxpayer-financed stockpile costs.