Partition and propagate: an error derivation algorithm for the design of approximate circuits

Inexact hardware design techniques have become popular in error-tolerant systems, where energy efficiency is a primary concern. Several techniques aim to identify circuit portions that can be discarded under an error constraint, but research on systematic methods to determine such error is still at an early stage. We herein illustrate a generic, scalable algorithm that determines the influence of each circuit gate on the final output. The algorithm first partitions the graph representing the circuit, then determines the error propagation model of the resulting subgraphs. When applied to existing approximate design frameworks, our solution improves their efficiency and result quality

Controlling Concurrent Change - A Multiview Approach Toward Updatable Vehicle Automation Systems

The development of SAE Level 3+ vehicles [{SAE}, 2014] poses new challenges not only for the functional development, but also for design and development processes. Such systems consist of a growing number of interconnected functional, as well as hardware and software components, making safety design increasingly difficult. In order to cope with emergent behavior at the vehicle level, thorough systems engineering becomes a key requirement, which enables traceability between different design viewpoints. Ensuring traceability is a key factor towards an efficient validation and verification of such systems. Formal models can in turn assist in keeping track of how the different viewpoints relate to each other and how the interplay of components affects the overall system behavior. Based on experience from the project Controlling Concurrent Change, this paper presents an approach towards model-based integration and verification of a cause effect chain for a component-based vehicle automation system. It reasons on a cross-layer model of the resulting system, which covers necessary aspects of a design in individual architectural views, e.g. safety and timing. In the synthesis stage of integration, our approach is capable of inserting enforcement mechanisms into the design to ensure adherence to the model. We present a use case description for an environment perception system, starting with a functional architecture, which is the basis for componentization of the cause effect chain. By tying the vehicle architecture to the cross-layer integration model, we are able to map the reasoning done during verification to vehicle behavior

JPEG2000-Based Semantic Image Compression using CNN

Some of the computer vision applications such as understanding, recognition as well as image processing are some areas where AI techniques like convolutional neural network (CNN) have attained great success. AI techniques are not very frequently used in applications like image compression which are a part of low-level vision applications. Intensifying the visual quality of the lossy video/image compression has been a huge obstacle for a very long time. Image processing tasks and image recognition can be addressed with the application of deep learning CNNs as a result of the availability of large training datasets and the recent advances in computing power. This paper consists of a CNN-based novel compression framework comprising of Compact CNN (ComCNN) and Reconstruction CNN (RecCNN) where they are trained concurrently and ideally consolidated into a compression framework, along with MS-ROI (Multi Structure-Region of Interest) mapping which highlights the semiotically notable portions of the image. The framework attains a mean PSNR value of 32.9dB, achieving a gain of 3.52dB and attains mean SSIM value of 0.9262, achieving a gain of 0.0723dB over the other methods when compared using the 6 main test images. Experimental results in the proposed study validate that the architecture substantially surpasses image compression frameworks, that utilized deblocking or denoising post- processing techniques, classified utilizing Peak Signal to Noise Ratio (PSNR) and Structural Similarity Index Measures (SSIM) with a mean PSNR, SSIM and Compression Ratio of 38.45, 0.9602 and 1.75x respectively for the 50 test images, thus obtaining state-of-art performance for Quality Factor (QF)=5

Demonstrating Controlled Change for Autonomous Space Vehicles

Recent research discusses concepts of infield changes to overcome the drawbacks of conventional lab-based system design processes. In this paper, we evaluate the concept of controlled change by applying it to a demonstration of a potential future space exploration scenario with mobile robots. The robots are capable of executing several image computations for exploration, object detection and pose estimation, which can be allocated to both FPGA-and processor resources of a System-on-Chip. The demonstrator addresses three scenarios which cover application-, environment-, and platform change. The system adapts itself to any of the named changes. This capability can increase the autonomy of future space missions. Exemplary, the demonstrator executes adaption of applications during operation to fulfill the mission goals, adaption of reliability under changing environment conditions, and adaption to sensor failure

Self-Aware Scheduling for Mixed-Criticality Component-Based Systems

A basic mixed-criticality requirement in real-time systems is temporal isolation, which ensures that applications receive a guaranteed (CPU) service and impose a bounded interference on other applications. Providing operating system support for temporal isolation is often inefficient, in terms of utilisation and achieved latencies, or complex and hard to implement or model correctly. Correct models are, however, a prerequisite when response times are bounded by formal analyses. We provide a novel approach to this challenge by applying self-aware computing methodologies that involve run-time monitoring to detect (and correct) model deviations of a budget-based scheduler

Context and communication profiling for IoT security and privacy: techniques and applications

During the last decade, two major technological changes have profoundly changed the way in which users consume and interact with on-line services and applications. The first of these has been the success of mobile computing, in particular that of smartphones, the primary end device used by many users for access to the Internet and various applications. The other change is the emergence of the so-called Internet-of-Things (IoT), denoting a technological transition in which everyday objects like household appliances that traditionally have been seen as stand-alone devices, are given network connectivity by introducing digital communication capabilities to those devices. The topic of this dissertation is related to a core challenge that the emergence of these technologies is introducing: how to effectively manage the security and privacy settings of users and devices in a user-friendly manner in an environment in which an ever-growing number of heterogeneous devices live and co-exist with each other? In particular we study approaches for utilising profiling of contextual parameters and device communications in order to make autonomous security decisions with the goal of striking a better balance between a system's security on one hand, and, its usability on the other. We introduce four distinct novel approaches utilising profiling for this end. First, we introduce ConXsense, a system demonstrating the use of user-specific longitudinal profiling of contextual information for modelling the usage context of mobile computing devices. Based on this ConXsense can probabilistically automate security policy decisions affecting security settings of the device. Further we develop an approach utilising the similarity of contextual parameters observed with on-board sensors of co-located devices to construct proofs of presence that are resilient to context-guessing attacks by adversaries that seek to fool a device into believing the adversary is co-located with it, even though it is in reality not. We then extend this approach to a context-based key evolution approach that allows IoT devices that are co-present in the same physical environment like the same room to use passively observed context measurements to iteratively authenticate their co-presence and thus gradually establish confidence in the other device being part of the same trust domain, e.g., the set of IoT devices in a user's home. We further analyse the relevant constraints that need to be taken into account to ensure security and usability of context-based authentication. In the final part of this dissertation we extend the profiling approach to network communications of IoT devices and utilise it to realise the design of the IoTSentinel system for autonomous security policy adaptation in IoT device networks. We show that by monitoring the inherent network traffic of IoT devices during their initial set-up, we can automatically identify the type of device newly added to the network. The device-type information is then used by IoTSentinel to adapt traffic filtering rules automatically to provide isolation of devices that are potentially vulnerable to known attacks, thereby protecting the device itself and the rest of the network from threats arising from possible compromise of vulnerable devices

Scalable Task Schedulers for Many-Core Architectures

This thesis develops schedulers for many-cores with different optimization objectives. The proposed schedulers are designed to be scale up as the number of cores in many-cores increase while continuing to provide guarantees on the quality of the schedule

Optimization-Based Methodology for the Exploration of Cyber-Physical System Architectures

In this thesis, we address the design space exploration of cyber-physical system architectures to select correct-by-construction configuration and interconnection of system components taken from pre-defined libraries. We formulate the exploration problem as a mapping problem and use optimization to solve it by searching for a minimum cost architecture that meets system requirements. Using a graph-based representation of a system architecture, we define a set of generic mixed integer linear constraints over graph vertices, edges and paths, and use these constraints to instantiate a variety of design requirements (e.g., interconnection, flow, workload, timing, reliability, routing). We implement a comprehensive toolbox that supports all steps of the proposed methodology. It provides a pattern-based formal language to facilitate requirements specification and a set of scalable algorithms for encoding and solving exploration problems. We prove our concepts on a set of case studies for different cyber-physical system domains, such as electrical power distribution networks, reconfigurable industrial production lines and wireless sensor networks