Designs for increasing reliability while reducing energy and increasing lifetime

In the last decades, the computing technology experienced tremendous developments. For instance, transistors' feature size shrank to half at every two years as consistently from the first time Moore stated his law. Consequently, number of transistors and core count per chip doubles at each generation. Similarly, petascale systems that have the capability of processing more than one billion calculation per second have been developed. As a matter of fact, exascale systems are predicted to be available at year 2020. However, these developments in computer systems face a reliability wall. For instance, transistor feature sizes are getting so small that it becomes easier for high-energy particles to temporarily flip the state of a memory cell from 1-to-0 or 0-to-1. Also, even if we assume that fault-rate per transistor stays constant with scaling, the increase in total transistor and core count per chip will significantly increase the number of faults for future desktop and exascale systems. Moreover, circuit ageing is exacerbated due to increased manufacturing variability and thermal stresses, therefore, lifetime of processor structures are becoming shorter. On the other side, due to the limited power budget of the computer systems such that mobile devices, it is attractive to scale down the voltage. However, when the voltage level scales to beyond the safe margin especially to the ultra-low level, the error rate increases drastically. Nevertheless, new memory technologies such as NAND flashes present only limited amount of nominal lifetime, and when they exceed this lifetime, they can not guarantee storing of the data correctly leading to data retention problems. Due to these issues, reliability became a first-class design constraint for contemporary computing in addition to power and performance. Moreover, reliability even plays increasingly important role when computer systems process sensitive and life-critical information such as health records, financial information, power regulation, transportation, etc. In this thesis, we present several different reliability designs for detecting and correcting errors occurring in processor pipelines, L1 caches and non-volatile NAND flash memories due to various reasons. We design reliability solutions in order to serve three main purposes. Our first goal is to improve the reliability of computer systems by detecting and correcting random and non-predictable errors such as bit flips or ageing errors. Second, we aim to reduce the energy consumption of the computer systems by allowing them to operate reliably at ultra-low voltage level. Third, we target to increase the lifetime of new memory technologies by implementing efficient and low-cost reliability schemes

Neurophysiological mechanisms of sensorimotor recovery from stroke

Ischemic stroke often results in the devastating loss of nervous tissue in the cerebral cortex, leading to profound motor deficits when motor territory is lost, and ultimately resulting in a substantial reduction in quality of life for the stroke survivor. The International Classification of Functioning, Disability and Health (ICF) was developed in 2002 by the World Health Organization (WHO) and provides a framework for clinically defining impairment after stroke. While the reduction of burdens due to neurological disease is stated as a mission objective of the National Institute of Neurological Disorders and Stroke (NINDS), recent clinical trials have been unsuccessful in translating preclinical research breakthroughs into actionable therapeutic treatment strategies with meaningful progress towards this goal. This means that research expanding another NINDS mission is now more important than ever: improving fundamental knowledge about the brain and nervous system in order to illuminate the way forward. Past work in the monkey model of ischemic stroke has suggested there may be a relationship between motor improvements after injury and the ability of the animal to reintegrate sensory and motor information during behavior. This relationship may be subserved by sprouting cortical axonal processes that originate in the spared premotor cortex after motor cortical injury in squirrel monkeys. The axons were observed to grow for relatively long distances (millimeters), significantly changing direction so that it appears that they specifically navigate around the injury site and reorient toward the spared sensory cortex. Critically, it remains unknown whether such processes ever form functional synapses, and if they do, whether such synapses perform meaningful calculations or other functions during behavior. The intent of this dissertation was to study this phenomenon in both intact rats and rats with a focal ischemia in primary motor cortex (M1) contralateral to the preferred forelimb during a pellet retrieval task. As this proved to be a challenging and resource-intensive endeavor, a primary objective of the dissertation became to provide the tools to facilitate such a project to begin with. This includes the creation of software, hardware, and novel training and behavioral paradigms for the rat model. At the same time, analysis of previous experimental data suggested that plasticity in the neural activity of the bilateral motor cortices of rats performing pellet retrievals after focal M1 ischemia may exhibit its most salient changes with respect to functional changes in behavior via mechanisms that were different than initially hypothesized. Specifically, a major finding of this dissertation is the finding that evidence of plasticity in the unit activity of bilateral motor cortical areas of the reaching rat is much stronger at the level of population features. These features exhibit changes in dynamics that suggest a shift in network fixed points, which may relate to the stability of filtering performed during behavior. It is therefore predicted that in order to define recovery by comparison to restitution, a specific type of fixed point dynamics must be present in the cortical population state. A final suggestion is that the stability or presence of these dynamics is related to the reintegration of sensory information to the cortex, which may relate to the positive impact of physical therapy during rehabilitation in the postacute window. Although many more rats will be needed to state any of these findings as a definitive fact, this line of inquiry appears to be productive for identifying targets related to sensorimotor integration which may enhance the efficacy of future therapeutic strategies

A computer-aided design for digital filter implementation

Imperial Users onl

Micro-, Meso- and Macro-Dynamics of the Brain

Neurosciences, Neurology, Psychiatr

System-level design of energy-efficient sensor-based human activity recognition systems: a model-based approach

This thesis contributes an evaluation of state-of-the-art dataflow models of computation regarding their suitability for a model-based design and analysis of human activity recognition systems, in terms of expressiveness and analyzability, as well as model accuracy. Different aspects of state-of-the-art human activity recognition systems have been modeled and analyzed. Based on existing methods, novel analysis approaches have been developed to acquire extra-functional properties like processor utilization, data communication rates, and finally energy consumption of the system

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Encoding of Object Presence and Manipulation Affordances in the Frontoparietal Grasp Network

The ability to grasp and manipulate objects is a fundamental human capacity. Loss of this function due to injury or disease can result in the inability to independently perform tasks of daily living. Brain computer interfaces (BCIs), which decode neural activity to control assistive devices, represent a new class of potential therapies to restore arm and hand function. Recent efforts to implement BCI control of a robotic hand for grasping have been hindered by unexpected neural modulations in primary motor cortex (M1) related to the contextual factor of whether movements were made with or without an object present. We designed and carried out three experiments in healthy rhesus macaque monkeys to characterize the influence of various object-related contextual factors on movement features (MFs — kinematics and muscle activity of the arm and hand) and on neural activity in three grasp-related brain areas: M1, ventral premotor cortex (PMV) and anterior intraparietal area (AIP). A novel method was devised to implant intracortical microelectrode arrays in PMV and AIP for these experiments. In Experiment 1, monkeys performed similar reaching movements with or without an object present. In Experiment 2, monkeys performed similar grasps on a set of objects with different grip affordances (objects could be grasped in multiple ways). In Experiment 3, monkeys performed similar grasps on two objects with different use affordances (one was stationary and one could be lifted). All object-related contextual factors were found to evoke small but significant differences in MFs despite task requirements remaining constant across contexts. These context-dependent behavioral differences were accompanied by proportionately larger neural differences in all three brain areas. The presence or absence of an object resulted in changes in neuronal firing rates that could not be accounted for by linear encoding of MFs. This object presence signal was found to interact with MF encoding in M1 in a way that was detrimental for BCI-style MF decoding. Object grip affordance differences resulted in similar but smaller neural modulations that did not impact MF decoding. Neural modulations related to object use affordance were prominent only in PMV

CIRA annual report FY 2016/2017

Reporting period April 1, 2016-March 31, 2017

Cruiser and PhoTable: Exploring Tabletop User Interface Software for Digital Photograph Sharing and Story Capture

Digital photography has not only changed the nature of photography and the photographic process, but also the manner in which we share photographs and tell stories about them. Some traditional methods, such as the family photo album or passing around piles of recently developed snapshots, are lost to us without requiring the digital photos to be printed. The current, purely digital, methods of sharing do not provide the same experience as printed photographs, and they do not provide effective face-to-face social interaction around photographs, as experienced during storytelling. Research has found that people are often dissatisfied with sharing photographs in digital form. The recent emergence of the tabletop interface as a viable multi-user direct-touch interactive large horizontal display has provided the hardware that has the potential to improve our collocated activities such as digital photograph sharing. However, while some software to communicate with various tabletop hardware technologies exists, software aspects of tabletop user interfaces are still at an early stage and require careful consideration in order to provide an effective, multi-user immersive interface that arbitrates the social interaction between users, without the necessary computer-human interaction interfering with the social dialogue. This thesis presents PhoTable, a social interface allowing people to effectively share, and tell stories about, recently taken, unsorted digital photographs around an interactive tabletop. In addition, the computer-arbitrated digital interaction allows PhoTable to capture the stories told, and associate them as audio metadata to the appropriate photographs. By leveraging the tabletop interface and providing a highly usable and natural interaction we can enable users to become immersed in their social interaction, telling stories about their photographs, and allow the computer interaction to occur as a side-effect of the social interaction. Correlating the computer interaction with the corresponding audio allows PhoTable to annotate an automatically created digital photo album with audible stories, which may then be archived. These stories remain useful for future sharing -- both collocated sharing and remote (e.g. via the Internet) -- and also provide a personal memento both of the event depicted in the photograph (e.g. as a reminder) and of the enjoyable photo sharing experience at the tabletop. To provide the necessary software to realise an interface such as PhoTable, this thesis explored the development of Cruiser: an efficient, extensible and reusable software framework for developing tabletop applications. Cruiser contributes a set of programming libraries and the necessary application framework to facilitate the rapid and highly flexible development of new tabletop applications. It uses a plugin architecture that encourages code reuse, stability and easy experimentation, and leverages the dedicated computer graphics hardware and multi-core processors of modern consumer-level systems to provide a responsive and immersive interactive tabletop user interface that is agnostic to the tabletop hardware and operating platform, using efficient, native cross-platform code. Cruiser's flexibility has allowed a variety of novel interactive tabletop applications to be explored by other researchers using the framework, in addition to PhoTable. To evaluate Cruiser and PhoTable, this thesis follows recommended practices for systems evaluation. The design rationale is framed within the above scenario and vision which we explore further, and the resulting design is critically analysed based on user studies, heuristic evaluation and a reflection on how it evolved over time. The effectiveness of Cruiser was evaluated in terms of its ability to realise PhoTable, use of it by others to explore many new tabletop applications, and an analysis of performance and resource usage. Usability, learnability and effectiveness of PhoTable was assessed on three levels: careful usability evaluations of elements of the interface; informal observations of usability when Cruiser was available to the public in several exhibitions and demonstrations; and a final evaluation of PhoTable in use for storytelling, where this had the side effect of creating a digital photo album, consisting of the photographs users interacted with on the table and associated audio annotations which PhoTable automatically extracted from the interaction. We conclude that our approach to design has resulted in an effective framework for creating new tabletop interfaces. The parallel goal of exploring the potential for tabletop interaction as a new way to share digital photographs was realised in PhoTable. It is able to support the envisaged goal of an effective interface for telling stories about one's photos. As a serendipitous side-effect, PhoTable was effective in the automatic capture of the stories about individual photographs for future reminiscence and sharing. This work provides foundations for future work in creating new ways to interact at a tabletop and to the ways to capture personal stories around digital photographs for sharing and long-term preservation

Proceedings of the EAA Joint Symposium on Auralization and Ambisonics 2014

In consideration of the remarkable intensity of research in the field of Virtual Acoustics, including different areas such as sound field analysis and synthesis, spatial audio technologies, and room acoustical modeling and auralization, it seemed about time to organize a second international symposium following the model of the first EAA Auralization Symposium initiated in 2009 by the acoustics group of the former Helsinki University of Technology (now Aalto University). Additionally, research communities which are focused on different approaches to sound field synthesis such as Ambisonics or Wave Field Synthesis have, in the meantime, moved closer together by using increasingly consistent theoretical frameworks. Finally, the quality of virtual acoustic environments is often considered as a result of all processing stages mentioned above, increasing the need for discussions on consistent strategies for evaluation. Thus, it seemed appropriate to integrate two of the most relevant communities, i.e. to combine the 2nd International Auralization Symposium with the 5th International Symposium on Ambisonics and Spherical Acoustics. The Symposia on Ambisonics, initiated in 2009 by the Institute of Electronic Music and Acoustics of the University of Music and Performing Arts in Graz, were traditionally dedicated to problems of spherical sound field analysis and re-synthesis, strategies for the exchange of ambisonics-encoded audio material, and – more than other conferences in this area – the artistic application of spatial audio systems. This publication contains the official conference proceedings. It includes 29 manuscripts which have passed a 3-stage peer-review with a board of about 70 international reviewers involved in the process. Each contribution has already been published individually with a unique DOI on the DepositOnce digital repository of TU Berlin. Some conference contributions have been recommended for resubmission to Acta Acustica united with Acustica, to possibly appear in a Special Issue on Virtual Acoustics in late 2014. These are not published in this collection.European Acoustics Associatio