Friendly Virtual Machine: Leveraging a Feedback-Control Model for Application Adaptation

With the increased use of "Virtual Machines" (VMs) as vehicles that isolate applications running on the same host, it is necessary to devise techniques that enable multiple VMs to share underlying resources both fairly and efficiently. To that end, one common approach is to deploy complex resource management techniques in the hosting infrastructure. Alternately, in this paper, we advocate the use of self-adaptation in the VMs themselves based on feedback about resource usage and availability. Consequently, we define a "Friendly" VM (FVM) to be a virtual machine that adjusts its demand for system resources, so that they are both efficiently and fairly allocated to competing FVMs. Such properties are ensured using one of many provably convergent control rules, such as AIMD. By adopting this distributed application-based approach to resource management, it is not necessary to make assumptions about the underlying resources nor about the requirements of FVMs competing for these resources. To demonstrate the elegance and simplicity of our approach, we present a prototype implementation of our FVM framework in User-Mode Linux (UML)-an implementation that consists of less than 500 lines of code changes to UML. We present an analytic, control-theoretic model of FVM adaptation, which establishes convergence and fairness properties. These properties are also backed up with experimental results using our prototype FVM implementation.

Lightweight Modeling of Java Virtual Machine Security Constraints using Alloy

The Java programming language has been widely described as secure by design. Nevertheless, a number of serious security vulnerabilities have been discovered in Java, particularly in the component known as the Bytecode Verifier. This paper describes a method for representing Java security constraints using the Alloy modeling language. It further describes a system for performing a security analysis on any block of Java bytecodes by converting the bytes into relation initializers in Alloy. Any counterexamples found by the Alloy analyzer correspond directly to insecure code. Analysis of a real-world malicious applet is given to demonstrate the efficacy of the approach.

An investigation of innovation and knowledge creation in virtual worlds

The Internet and World Wide Web have had, and continue to have, an incredible impact on our civilization. These technologies have radically influenced the way that society is organised and the manner in which people around the world communicate and interact. The structure and function of individual, social, organisational, economic and political life begin to resemble the digital network architectures upon which they are increasingly reliant. It is increasingly difficult to imagine how our ‘offline’ world would look or function without the ‘online’ world; it is becoming less meaningful to distinguish between the ‘actual’ and the ‘virtual’. Thus, the major architectural project of the twenty-first century is to “imagine, build, and enhance an interactive and ever changing cyberspace” (Lévy, 1997, p. 10). Virtual worlds are at the forefront of this evolving digital landscape. Virtual worlds have “critical implications for business, education, social sciences, and our society at large” (Messinger et al., 2009, p. 204). This study focuses on the possibilities of virtual worlds in terms of communication, collaboration, innovation and creativity. The concept of knowledge creation is at the core of this research. The study shows that scholars increasingly recognise that knowledge creation, as a socially enacted process, goes to the very heart of innovation. However, efforts to build upon these insights have struggled to escape the influence of the information processing paradigm of old and have failed to move beyond the persistent but problematic conceptualisation of knowledge creation in terms of tacit and explicit knowledge. Based on these insights, the study leverages extant research to develop the conceptual apparatus necessary to carry out an investigation of innovation and knowledge creation in virtual worlds. The study derives and articulates a set of definitions (of virtual worlds, innovation, knowledge and knowledge creation) to guide research. The study also leverages a number of extant theories in order to develop a preliminary framework to model knowledge creation in virtual worlds. Using a combination of participant observation and six case studies of innovative educational projects in Second Life, the study yields a range of insights into the process of knowledge creation in virtual worlds and into the factors that affect it. The study’s contributions to theory are expressed as a series of propositions and findings and are represented as a revised and empirically grounded theoretical framework of knowledge creation in virtual worlds. These findings highlight the importance of prior related knowledge and intrinsic motivation in terms of shaping and stimulating knowledge creation in virtual worlds. At the same time, they highlight the importance of meta-knowledge (knowledge about knowledge) in terms of guiding the knowledge creation process whilst revealing the diversity of behavioural approaches actually used to create knowledge in virtual worlds and. This theoretical framework is itself one of the chief contributions of the study and the analysis explores how it can be used to guide further research in virtual worlds and on knowledge creation. The study’s contributions to practice are presented as actionable guide to simulate knowledge creation in virtual worlds. This guide utilises a theoretically based classification of four knowledge-creator archetypes (the sage, the lore master, the artisan, and the apprentice) and derives an actionable set of behavioural prescriptions for each archetype. The study concludes with a discussion of the study’s implications in terms of future research.

Reasoning about trust, entrepreneurial services, and the virtual team

This Portfolio of Exploration (PoE) tracks a transformative learning developmental journey that is directed at changing meaning making structures and mental models within an innovation practice. The explicit purpose of the Portfolio is to develop new and different perspectives that enable the handling of new and more complex phenomena through self transformation and increased emotional intelligence development. The Portfolio provides a response to the question: ‘What are the key determinants that enable a Virtual Team (VT) to flourish where flourishing means developing and delivering on the firm’s innovative imperatives?’ Furthermore, the PoE is structured as an investigation into how higher order meaning making promotes ‘entrepreneurial services’ within an intra-firm virtual team, with a secondary aim to identify how reasoning about trust influence KGPs to exchange knowledge. I have developed a framework which specifically focuses on the effectiveness of any firms’ Virtual Team (VT) through transforming the meaning making of the VT participants. I hypothesized it is the way KGPs make meaning (reasoning about trust) which differentiates the firm as a growing firm in the sense of Penrosean resources: ‘inducement to expand and a limit of expansion’ (1959). Reasoning about trust is used as a higher order meaning-making concept in line with Kegan’s (1994) conception of complex meaning making, which is the combining of ideas and data in ways that transform meaning and implicates participants to find new ways of knowledge generation. Simply, it is the VT participants who develop higher order meaning making that hold the capabilities to transform the firm from within, providing a unique competitive advantage that enables the firm to grow.

Exploring the effects of image persistence in low frame rate virtual environments

© 2015 IEEE.In virtual reality applications, there is an aim to provide real time graphics which run at high refresh rates. However, there are many situations in which this is not possible due to simulation or rendering issues. When running at low frame rates, several aspects of the user experience are affected. For example, each frame is displayed for an extended period of time, causing a high persistence image artifact. The effect of this artifact is that movement may lose continuity, and the image jumps from one frame to another. In this paper, we discuss our initial exploration of the effects of high persistence frames caused by low refresh rates and compare it to high frame rates and to a technique we developed to mitigate the effects of low frame rates. In this technique, the low frame rate simulation images are displayed with low persistence by blanking out the display during the extra time such image would be displayed. In order to isolate the visual effects, we constructed a simulator for low and high persistence displays that does not affect input latency. A controlled user study comparing the three conditions for the tasks of 3D selection and navigation was conducted. Results indicate that the low persistence display technique may not negatively impact user experience or performance as compared to the high persistence case. Directions for future work on the use of low persistence displays for low frame rate situations are discussed.

Validation of the Food-Linked Virtual Response task.

This research validates a computerized dietary selection task (Food-Linked Virtual Response or FLVR) for use in studies of food consumption. In two studies, FLVR task responses were compared with measures of health consciousness, mood, body mass index, personality, cognitive restraint toward food, and actual food selections from a buffet table. The FLVR task was associated with variables which typically predict healthy decision-making and was unrelated to mood or body mass index. Furthermore, the FLVR task predicted participants' unhealthy selections from the buffet, but not overall amount of food. The FLVR task is an inexpensive, valid, and easily administered option for assessing momentary dietary decisions.

Mi escuela virtual de Educación Matemática

esde el año 2004 la Licenciatura en Matemáticas, consecuente con el principio de pertinencia de la Investigación en la Universidad de Cundinamarca, emprendió acciones inmediatas orientadas a generar procesos de innovación modernizadora en la formación de docentes investigadores en Educación Matemática que contribuyeran con la construcción gradual de bases sólidas para la línea de investigación del programa10, eje articulador del proyecto curricular.

Comunidad virtual de discurso profasional geométrico: contribuciones de un proceso interactivo docente por internet

La naturaleza del pensamiento de los profesores es una área de considerable interés y la atención hacia la relevancia de la geometría como un importante componente formativo es un hecho en los planteamientos interesados en la formación inicial y continuada del profesorado. En el ámbito de la investigación cualitativa, presentaremos las contribuciones de un entorno virtual para el desarrollo crítico del contenido del conocimiento profesional del profesor de matemática. Específicamente, analizar un proceso teleinteractivo docente a partir de situaciones de enseñanza-aprendizaje en geometría (para alumnos con 11-14 años). La importancia del proceso teleinteractivo para el desarrollo de habilidades metacognitivas en los profesores es un hecho destacable en las conclusiones de la investigación.

Modelación concreta en álgebra: balanza virtual, ecuaciones y sistemas matemáticos de signos

Se analizan resultados de un estudio con alumnos de secundaria, en el que se utiliza un modelo virtual de la balanza para la enseñanza de la resolución de ecuaciones de primer grado. A diferencia del modelo concreto o diagramático, el modelo virtual es dinámico e interactivo y en su versión ampliada (balanza con poleas) incluye la representación y resolución de ecuaciones con sustracción de términos. Los resultados indican que al final del estudio, los alumnos logran extender el método algebraico de resolución a una variedad amplia de modalidades de ecuaciones y que de manera espontánea infieren el método de transposición de términos. Con el fin de investigar los procesos de producción de sentido y de construcción de significado, se adopta una perspectiva semiótica que incorpora al análisis las producciones sígnicas de los estudiantes, como parte de la interacción entre los sistemas de signos algebraico, aritmético y el sistema de signos del modelo.

Torre de Hanói virtual e a constucâo do conceito de funcâo exponencial no ensino médio: um processo que parte da intuicâo a caminho da formalizacâo

Este trabalho tem como objetivo apresentar uma reflexão sobre o processo de aprendizagem do conceito de Função Exponencial no Ensino Médio, a partir da utilização do jogo Torre de Hanói virtual, através do uso de laptops educacionais. Os dados foram coletados por meio de um questionário inicial, para identificação das ideias prévias dos estudantes e por meio de registros em um diário de campo. Em seguida, os dados foram analisados conforme a metodologia Análise Textual Discursiva. A partir da análise, emergiram duas categorias: a primeira indica que a ideia inicial apresentada pelos alunos em relação à Função Exponencial está associada a uma caracterização da linguagem ligada à Função Quadrática. Já, a segunda categoria aponta uma transformação da linguagem natural do entendimento da função exponencial para a linguagem formal, isto é, a formalização escolarizada do conceito de Função Exponencial.

Transferencia del aprendizaje situado de la sintaxis algebraica: ecuaciones lineales y balanza virtual

El estudio tiene como propósito investigar los procesos de transferencia del aprendizaje situado de la sintaxis algebraica para la resolución de ecuaciones lineales, cuando se utiliza un modelo de enseñanza concreto, virtual y dinámico con estudiantes de nivel secundaria. Al final del estudio, los alumnos muestran un avance significativo en la resolución de ecuaciones y se puede decir que en su mayoría logran realizar la transferencia de las acciones efectuadas con el sistema de signos del modelo concreto (balanza virtual) a acciones que se ejecutan con el sistema de signos del álgebra. A su vez, se observó que los procesos de transferencia pasan por diferentes etapas, dependiendo del sistema de signos hacia el cual se logra la transferencia de acciones.

Aprendiendo a reconocer evidencias del proceso de generalización de los estudiantes a través de un debate virtual

Este estudio tiene como objetivo examinar cómo los futuros profesores de secundaria (EPS) reconocen evidencias de la comprensión del proceso de generalización en estudiantes de secundaria. Los EPS realizaron dos tareas: (1) describir las respuestas dadas por estudiantes de secundaria a dos problemas de generalización lineal y agrupar las que reflejaban características comunes de la comprensión del proceso de generalización; (2) participar en un debate virtual sobre las características de la comprensión del proceso de generalización. Los resultados indican que la participación en el debate virtual permitió a los EPS centrar su mirada en las ideas que subyacen en el proceso de generalización (generalización cercana y lejana e intento de expresar la regla general, pasando de una estrategia aditiva a una funcional) más que en el procedimiento realizado.

Laboratorio virtual de matemáticas (ALME2005)

Concebimos que la modelación de fenómenos es una práctica que está ligada a la construcción de conocimientos matemáticos y en este sentido se han realizado investigaciones entorno a su incorporación al contexto escolar. Sin embargo, el incorporar la experimentación en el aula de matemáticas conlleva dificultades, una de ellas es la carencia de material de laboratorio. El laboratorio virtual es un proyecto que intenta suplir la ausencia de un laboratorio físicamente, sin embargo, esta sustitución desencadena diferentes relaciones entre los actores. En este trabajo se pretende mostrar como es que un laboratorio simulado, podría contribuir a la incorporación a sistemas escolares concretos de diseños de aprendizaje basados en las prácticas sociales de modelación. Se da evidencia de cómo se desarrollan acciones e interacciones colaborativas alrededor del laboratorio virtual.

Virtual manufacturing and design in the real world - implementation and scalability on HPPC systems

Virtual manufacturing and design assessment increasingly involve the simulation of interacting phenomena, sic. multi-physics, an activity which is very computationally intensive. This chapter describes an attempt to address the parallel issues associated with a multi-physics simulation approach based upon a range of compatible procedures operating on one mesh using a single database - the distinct physics solvers can operate separately or coupled on sub-domains of the whole geometric space. Moreover, the finite volume unstructured mesh solvers use different discretization schemes (and, particularly, different ‘nodal’ locations and control volumes). A two-level approach to the parallelization of this simulation software is described: the code is restructured into parallel form on the basis of the mesh partitioning alone, that is, without regard to the physics. However, at run time, the mesh is partitioned to achieve a load balance, by considering the load per node/element across the whole domain. The latter of course is determined by the problem specific physics at a particular location.

The specification and design of an interactive virtual environment for use in teacher training

The original concept was to create a 'simulation' which would provide trainee teachers, specializing in Information and Communications Technology (ICT) with the opportunity to explore a primary school environment. Within the simulation, factors affecting the development and implementation of ICT would be modelled so that trainees would be able to develop the skills, knowledge and understanding necessary to identify appropriate strategies to overcome the limitations. To this end, we have developed Allsorts Primary - the prototype of a simulated interactive environment, representing a typical primary school