lLTZVisor: a lightweight TrustZone-assisted hypervisor for low-end ARM devices

Dissertação de mestrado em Engenharia Eletrónica Industrial e ComputadoresVirtualization is a well-established technology in the server and desktop space and has recently been spreading across different embedded industries. Facing multiple challenges derived by the advent of the Internet of Things (IoT) era, these industries are driven by an upgrowing interest in consolidating and isolating multiple environments with mixed-criticality features, to address the complex IoT application landscape. Even though this is true for majority mid- to high-end embedded applications, low-end systems still present little to no solutions proposed so far. TrustZone technology, designed by ARM to improve security on its processors, was adopted really well in the embedded market. As such, the research community became active in exploring other TrustZone’s capacities for isolation, like an alternative form of system virtualization. The lightweight TrustZone-assisted hypervisor (LTZVisor), that mainly targets the consolidation of mixed-criticality systems on the same hardware platform, is one design example that takes advantage of TrustZone technology for ARM application processors. With the recent introduction of this technology to the new generation of ARM microcontrollers, an opportunity to expand this breakthrough form of virtualization to low-end devices arose. This work proposes the development of the lLTZVisor hypervisor, a refactored LTZVisor version that aims to provide strong isolation on resource-constrained devices, while achieving a low-memory footprint, determinism and high efficiency. The key for this is to implement a minimal, reliable, secure and predictable virtualization layer, supported by the TrustZone technology present on the newest generation of ARM microcontrollers (Cortex-M23/33).Virtualização é uma tecnologia já bem estabelecida no âmbito de servidores e computadores pessoais que recentemente tem vindo a espalhar-se através de várias indústrias de sistemas embebidos. Face aos desafios provenientes do surgimento da era Internet of Things (IoT), estas indústrias são guiadas pelo crescimento do interesse em consolidar e isolar múltiplos sistemas com diferentes níveis de criticidade, para atender ao atual e complexo cenário aplicativo IoT. Apesar de isto se aplicar à maioria de aplicações embebidas de média e alta gama, sistemas de baixa gama apresentam-se ainda com poucas soluções propostas. A tecnologia TrustZone, desenvolvida pela ARM de forma a melhorar a segurança nos seus processadores, foi adoptada muito bem pelo mercado dos sistemas embebidos. Como tal, a comunidade científica começou a explorar outras aplicações da tecnologia TrustZone para isolamento, como uma forma alternativa de virtualização de sistemas. O "lightweight TrustZone-assisted hypervisor (LTZVisor)", que tem sobretudo como fim a consolidação de sistemas de criticidade mista na mesma plataforma de hardware, é um exemplo que tira vantagem da tecnologia TrustZone para os processadores ARM de alta gama. Com a recente introdução desta tecnologia para a nova geração de microcontroladores ARM, surgiu uma oportunidade para expandir esta forma inovadora de virtualização para dispositivos de baixa gama. Este trabalho propõe o desenvolvimento do hipervisor lLTZVisor, uma versão reestruturada do LTZVisor que visa em proporcionar um forte isolamento em dispositivos com recursos restritos, simultâneamente atingindo um baixo footprint de memória, determinismo e alta eficiência. A chave para isto está na implementação de uma camada de virtualização mínima, fiável, segura e previsível, potencializada pela tecnologia TrustZone presente na mais recente geração de microcontroladores ARM (Cortex-M23/33)

Supporting virtuosity and flow in computer music

As we begin to realise the sonic and expressive potential of the computer, HCI researchers face the challenge of designing rewarding and accessible user experiences that enable individuals to explore complex creative domains such as music. In performance-based music systems such as sequencers, a disjunction exists between the musician’s specialist skill with performance hardware and the generic usability techniques applied in the design of the software. The creative process is not only fragmented across multiple physical (and virtual) devices, but divided across creativity and productivity phases separated by the act of recording. Integrating psychologies of expertise and intrinsic motivation, this thesis proposes a design shift from usability to virtuosity, using theories of “flow” (Csikszentmihalyi, 1996) and feedback “liveness” (Tanimoto, 1990) to identify factors that facilitate learning and creativity in digital notations and interfaces, leading to a set of design heuristics to support virtuosity in notation use. Using the cognitive dimensions of notations framework (Green, 1996), models of the creative user experience are developed, working towards a theoretical framework for HCI in music systems, and specifically computer-aided composition. Extensive analytical methods are used to look at corollaries of virtuosity and flow in real-world computer music interaction, notably in soundtracking, a software-based composing environment offering a rapid edit-audition feedback cycle, enabled by the user’s skill in manipulating the text-based notation (and program) through the computer keyboard. The interaction and development of more than 1,000 sequencer and tracker users was recorded over a period of 2 years, to investigate the nature and development of skill and technique, look for evidence of flow experiences, and establish the use and role of both visual and musical feedback in music software. Quantitative analyses of interaction data are supplemented with a detailed video study of a professional tracker composer, and a user survey that draws on psychometric methods to evaluate flow experiences in the use of digital music notations, such as sequencers and trackers. Empirical findings broadly support the proposed design heuristics, and enable the development of further models of liveness and flow in notation use. Implications for UI design are discussed in the context of existing music systems, and supporting digitally-mediated creativity in other domains based on notation use

INERTIAL MOTION CAPTURE SYSTEM FOR BIOMECHANICAL ANALYSIS IN PRESSURE SUITS

A non-invasive system has been developed at the University of Maryland Space System Laboratory with the goal of providing a new capability for quantifying the motion of the human inside a space suit. Based on an array of six microprocessors and eighteen microelectromechanical (MEMS) inertial measurement units (IMUs), the Body Pose Measurement System (BPMS) allows the monitoring of the kinematics of the suit occupant in an unobtrusive, self-contained, lightweight and compact fashion, without requiring any external equipment such as those necessary with modern optical motion capture systems. BPMS measures and stores the accelerations, angular rates and magnetic fields acting upon each IMU, which are mounted on the head, torso, and each segment of each limb. In order to convert the raw data into a more useful form, such as a set of body segment angles quantifying pose and motion, a series of geometrical models and a non-linear complimentary filter were implemented. The first portion of this works focuses on assessing system performance, which was measured by comparing the BPMS filtered data against rigid body angles measured through an external VICON optical motion capture system. This type of system is the industry standard, and is used here for independent measurement of body pose angles. By comparing the two sets of data, performance metrics such as BPMS system operational conditions, accuracy, and drift were evaluated and correlated against VICON data. After the system and models were verified and their capabilities and limitations assessed, a series of pressure suit evaluations were conducted. Three different pressure suits were used to identify the relationship between usable range of motion and internal suit pressure. In addition to addressing range of motion, a series of exploration tasks were also performed, recorded, and analysed in order to identify different motion patterns and trajectories as suit pressure is increased and overall suit mobility is reduced. The focus of these evaluations was to quantify the reduction in mobility when operating in any of the evaluated pressure suits. This data should be of value in defining new low cost alternatives for pressure suit performance verification and evaluation. This work demonstrates that the BPMS technology is a viable alternative or companion to optical motion capture; while BPMS is the first motion capture system that has been designed specifically to measure the kinematics of a human in a pressure suit, its capabilities are not constrained to just being a measurement tool. The last section of the manuscript is devoted to future possible uses for the system, with a specific focus on pressure suit applications such in the use of BPMS as a master control interface for robot teleoperation, as well as an input interface for future robotically augmented pressure suits

Proceedings of the 1993 Conference on Intelligent Computer-Aided Training and Virtual Environment Technology, Volume 1

These proceedings are organized in the same manner as the conference's contributed sessions, with the papers grouped by topic area. These areas are as follows: VE (virtual environment) training for Space Flight, Virtual Environment Hardware, Knowledge Aquisition for ICAT (Intelligent Computer-Aided Training) & VE, Multimedia in ICAT Systems, VE in Training & Education (1 & 2), Virtual Environment Software (1 & 2), Models in ICAT systems, ICAT Commercial Applications, ICAT Architectures & Authoring Systems, ICAT Education & Medical Applications, Assessing VE for Training, VE & Human Systems (1 & 2), ICAT Theory & Natural Language, ICAT Applications in the Military, VE Applications in Engineering, Knowledge Acquisition for ICAT, and ICAT Applications in Aerospace

COSPO/CENDI Industry Day Conference

The conference's objective was to provide a forum where government information managers and industry information technology experts could have an open exchange and discuss their respective needs and compare them to the available, or soon to be available, solutions. Technical summaries and points of contact are provided for the following sessions: secure products, protocols, and encryption; information providers; electronic document management and publishing; information indexing, discovery, and retrieval (IIDR); automated language translators; IIDR - natural language capabilities; IIDR - advanced technologies; IIDR - distributed heterogeneous and large database support; and communications - speed, bandwidth, and wireless

Parallelizing the ALSA Modular Audio Synthesizer

Digital audio synthesizers are frameworks for generating digital audio, and are the backbone for creating synthesized digital music. Some of the existing audio synthesizer engines are quite popular due to the following reasons: economy, flexibility and convenience for the user in synthesizing music/audio, compatibility with commodity hardware and software platforms. One such audio synthesis engine is the ALSA (Advanced Linux Sound Architecture) Modular Synthesizer, which is an emulation of an analogue modular synthesizer. Until recently, audio programming software has been inherently sequential. There have been some attempts to parallelize a few of these engines with mixed results. The goal of parallelization is not only to obtain speedup but also to increase throughput so that more complex synthesizers can be built to enhance quality and/or complexity of the sound generated. By design, audio synthesizers have soft real-time requirements. This can mean that many of the techniques that are normally used to parallelize a program can in certain situations be too expensive to offer any real performance gain. As a consequence, a naïve parallelization technique for an audio synthesizer can in fact be too expensive due to added overheads, and hence is of no benefit. This paper discusses our methodologies and experiences on parallelizing the ALSA Modular Synthesizer on a multicore environment, and elaborates the experimental results highlighting the advantages of parallelization

Exploring Processor and Memory Architectures for Multimedia

Multimedia has become one of the cornerstones of our 21st century society and, when combined with mobility, has enabled a tremendous evolution of our society. However, joining these two concepts introduces many technical challenges. These range from having sufficient performance for handling multimedia content to having the battery stamina for acceptable mobile usage. When taking a projection of where we are heading, we see these issues becoming ever more challenging by increased mobility as well as advancements in multimedia content, such as introduction of stereoscopic 3D and augmented reality. The increased performance needs for handling multimedia come not only from an ongoing step-up in resolution going from QVGA (320x240) to Full HD (1920x1080) a 27x increase in less than half a decade. On top of this, there is also codec evolution (MPEG-2 to H.264 AVC) that adds to the computational load increase. To meet these performance challenges there has been processing and memory architecture advances (SIMD, out-of-order superscalarity, multicore processing and heterogeneous multilevel memories) in the mobile domain, in conjunction with ever increasing operating frequencies (200MHz to 2GHz) and on-chip memory sizes (128KB to 2-3MB). At the same time there is an increase in requirements for mobility, placing higher demands on battery-powered systems despite the steady increase in battery capacity (500 to 2000mAh). This leaves negative net result in-terms of battery capacity versus performance advances. In order to make optimal use of these architectural advances and to meet the power limitations in mobile systems, there is a need for taking an overall approach on how to best utilize these systems. The right trade-off between performance and power is crucial. On top of these constraints, the flexibility aspects of the system need to be addressed. All this makes it very important to reach the right architectural balance in the system. The first goal for this thesis is to examine multimedia applications and propose a flexible solution that can meet the architectural requirements in a mobile system. Secondly, propose an automated methodology of optimally mapping multimedia data and instructions to a heterogeneous multilevel memory subsystem. The proposed methodology uses constraint programming for solving a multidimensional optimization problem. Results from this work indicate that using today’s most advanced mobile processor technology together with a multi-level heterogeneous on-chip memory subsystem can meet the performance requirements for handling multimedia. By utilizing the automated optimal memory mapping method presented in this thesis lower total power consumption can be achieved, whilst performance for multimedia applications is improved, by employing enhanced memory management. This is achieved through reduced external accesses and better reuse of memory objects. This automatic method shows high accuracy, up to 90%, for predicting multimedia memory accesses for a given architecture

Cooperative framework for open real-time systems

Actualmente, os sistemas embebidos estão presentes em toda a parte. Embora grande parte da população que os utiliza não tenha a noção da sua presença, na realidade, se repentinamente estes sistemas deixassem de existir, a sociedade iria sentir a sua falta. A sua utilização massiva deve-se ao facto de estarem practicamente incorporados em quase os todos dispositivos electrónicos de consumo, telecomunicações, automação industrial e automóvel. Influenciada por este crescimento, a comunidade científica foi confrontada com novos problemas distribuídos por vários domínios científicos, dos quais são destacados a gestão da qualidade de serviço e gestão de recursos - domínio encarregue de resolver problemas relacionados com a alocação óptima de recursos físicos, tais como rede, memória e CPU. Existe na literatura um vasto conjunto de modelos que propõem soluções para vários problemas apresentados no contexto destes domínios científicos. No entanto, não é possível encontrar modelos que lidem com a gestão de recursos em ambientes de execução cooperativos e abertos com restrições temporais utilizando coligações entre diferentes nós, de forma a satisfazer os requisitos não funcionais das aplicações. Devido ao facto de estes sistemas serem dinâmicos por natureza, apresentam a característica de não ser possível conhecer, a priori, a quantidade de recursos necessários que uma aplicação irá requerer do sistema no qual irá ser executada. Este conhecimento só é adquirido aquando da execução da aplicação. De modo a garantir uma gestão eficiente dos recursos disponíveis, em sistemas que apresentam um grande dinamismo na execução de tarefas com e sem restrições temporais, é necessário garantir dois aspectos fundamentais. O primeiro está relacionado com a obtenção de garantias na execução de tarefas de tempo-real. Estas devem sempre ser executadas dentro da janela temporal requirida. O segundo aspecto refere a necessidade de garantir que todos os recursos necessários à execução das tarefas são fornecidos, com o objectivo de manter os níveis de performance quer das aplicações, quer do próprio sistema. Tendo em conta os dois aspectos acima mencionados, o projecto CooperatES foi especificado com o objectivo de permitir a dispositivos com poucos recursos uma execução colectiva de serviços com os seus vizinhos, de modo a cumprir com as complexas restrições de qualidade de serviço impostas pelos utilizadores ou pelas aplicações. Decorrendo no contexto do projecto CooperatES, o trabalho resultante desta tese tem como principal objectivo avaliar a practicabilidade dos conceitos principais propostos no âmbito do projecto. O trabalho em causa implicou a escolha e análise de uma plataforma, a análise de requisitos, a implementação e avaliação de uma framework que permite a execução cooperativa de aplicações e serviços que apresentem requisitos de qualidade de serviço. Do trabalho desenvolvido resultaram as seguintes contribuições: Análise das plataformas de código aberto que possam ser utilizadas na implementação dos conceitos relacionados com o projecto CooperatES; Critérios que influenciaram a escolha da plataforma Android e um estudo focado na análise da plataforma sob uma perspectiva de sistemas de tempo-real; Experiências na implementação dos conceitos do projecto na plataforma Android; Avaliação da practicabilidade dos conceitos propostos no projecto CooperatES; Proposta de extensões que permitam incorporar características de sistemas de tempo real abertos na plataforma Android.Embedded devices are reaching a point where society does not notice its presence; however, if suddenly taken away, everyone would notice their absence. The new, small, embedded devices used in consumer electronics, telecommunication, industrial automation, or automotive systems are the reason for their massive spread. Influenced by this growth and pervasiveness, the scientific community is faced with new challenges in several domains. Of these, important ones are the management of the quality of the provided services and the management of the underlying resources - both interconnected to solve the problem of optimal allocation of physical resources (namely CPU, memory and network as examples), whilst providing the best possible quality to users. Although several models have been presented in literature, a recent proposal handles resource management by using coalitions of nodes in open real-time cooperative environments, as a solution to guarantee that the application’s non-functional requirements are met, and to provide the best possible quality of service to users. This proposal, the CooperatES framework, provides better models and mechanisms to handle resource management in open real-time systems, allowing resource constrained devices to collectively execute services with their neighbours, in order to fulfil the complex Quality of Service constraints imposed by users and applications. Within the context of the CooperatES framework, the work presented in this thesis evaluates the feasibility of the implementation of the framework’s Quality of Service concept within current embedded Java platforms, and proposes a solution and architecture for a specific platform: the Android operating system. To this purpose, the work provides an evaluation of the suitability of Java solutions for real-time and embedded systems, an evaluation of the Android platform for open real-time systems, as well as discusses the required extensions to Android allowing it to be used within real-time system. Furthermore, this thesis presents a prototype implementation of the CooperatES framework within the Android platform, which allows determining the suitability of the proposed platform extensions for open real-time systems applications

A basic web-based distance education model

Thesis (Master)--Izmir Institute of Technology, Computer Engineering, Izmir, 2005Includes bibliographical references (leaves: 147)Text in English; Abstract: Turkish and Englishxv, 201 leavesDuring the recent years, the rapid growth of the Web and multimedia technologies urged a shift of Computer-Based Educational Technology towards the Web. In the leading universities of the developed countries, studies on Web-Based Education have started and in an increasing manner are going strong. In the last few years, the leading universities of Turkey are also greatly interested in Web-Based Education and have started their re-structuring accordingly.The goal of this study is to design a basic model to be utilized by a university aiming to offer web-based distance education. In achieving this; by the use of system approach, a model comprising of three subsystems, namely system analysis, system design and evaluation&control, working in coordination with each other, has been tried to be proposed. There may be only one missing point of this study, that is; since preparing a lesson or program according to this model was not foreseen in this thesis, the effectiveness evaluations suggested in the evaluation&control subsystem could not be realized. It is recommended to realize such an evaluation in a further study to make it possible to reveal the effectiveness of web-based education by preparing a lesson or program according to this model.On the other hand, a survey has been conducted in Turkey in some of the universities either offering web-based education or are interested in studies in this field.The aim of this survey is to analyze from system design point of view the studies carried out in our universities on this matter and to get a picture of the existing situation.The directed questions aiming this were prepared by taking into consideration of the three stages of system design subsystem, i.e. administrative design, educational design, and technological design. It is intended for the result of this survey to shed light to the new-coming institutions in this field. As a matter of fact, each stage of this subsystem is a survey item itself and should be researched one by one in other studies.Furthermore, for individuals interested in distance education and web-based distance education and for people newly involved in this matter, this thesis is intended to be a reference material and to serve this purpose the sections are prepared containing the basic information accordingly. Nevertheless, since most of the information regarding system design are prepared without taking into consideration the disabled people, the relevant information are not complete. In another study, the offering of the web-based education to the disabled people, especially for deaf, hard of hearing or speech impaired, and blind students, has to be investigated.Finally, in this thesis the proposed model for the Web-Based Distance Education, as being a basic and conceptual model, has a flexible structure; i.e., suitable for all the institutions and establishments intending to offer the web-based education.What is important here, is to exploit the potential sources within the institution that will display the required systematic approach