482 research outputs found

    Design and Real-World Evaluation of Dependable Wireless Cyber-Physical Systems

    Get PDF
    The ongoing effort for an efficient, sustainable, and automated interaction between humans, machines, and our environment will make cyber-physical systems (CPS) an integral part of the industry and our daily lives. At their core, CPS integrate computing elements, communication networks, and physical processes that are monitored and controlled through sensors and actuators. New and innovative applications become possible by extending or replacing static and expensive cable-based communication infrastructures with wireless technology. The flexibility of wireless CPS is a key enabler for many envisioned scenarios, such as intelligent factories, smart farming, personalized healthcare systems, autonomous search and rescue, and smart cities. High dependability, efficiency, and adaptivity requirements complement the demand for wireless and low-cost solutions in such applications. For instance, industrial and medical systems should work reliably and predictably with performance guarantees, even if parts of the system fail. Because emerging CPS will feature mobile and battery-driven devices that can execute various tasks, the systems must also quickly adapt to frequently changing conditions. Moreover, as applications become ever more sophisticated, featuring compact embedded devices that are deployed densely and at scale, efficient designs are indispensable to achieve desired operational lifetimes and satisfy high bandwidth demands. Meeting these partly conflicting requirements, however, is challenging due to imperfections of wireless communication and resource constraints along several dimensions, for example, computing, memory, and power constraints of the devices. More precisely, frequent and correlated message losses paired with very limited bandwidth and varying delays for the message exchange significantly complicate the control design. In addition, since communication ranges are limited, messages must be relayed over multiple hops to cover larger distances, such as an entire factory. Although the resulting mesh networks are more robust against interference, efficient communication is a major challenge as wireless imperfections get amplified, and significant coordination effort is needed, especially if the networks are dynamic. CPS combine various research disciplines, which are often investigated in isolation, ignoring their complex interaction. However, to address this interaction and build trust in the proposed solutions, evaluating CPS using real physical systems and wireless networks paired with formal guarantees of a system’s end-to-end behavior is necessary. Existing works that take this step can only satisfy a few of the abovementioned requirements. Most notably, multi-hop communication has only been used to control slow physical processes while providing no guarantees. One of the reasons is that the current communication protocols are not suited for dynamic multi-hop networks. This thesis closes the gap between existing works and the diverse needs of emerging wireless CPS. The contributions address different research directions and are split into two parts. In the first part, we specifically address the shortcomings of existing communication protocols and make the following contributions to provide a solid networking foundation: • We present Mixer, a communication primitive for the reliable many-to-all message exchange in dynamic wireless multi-hop networks. Mixer runs on resource-constrained low-power embedded devices and combines synchronous transmissions and network coding for a highly scalable and topology-agnostic message exchange. As a result, it supports mobile nodes and can serve any possible traffic patterns, for example, to efficiently realize distributed control, as required by emerging CPS applications. • We present Butler, a lightweight and distributed synchronization mechanism with formally guaranteed correctness properties to improve the dependability of synchronous transmissions-based protocols. These protocols require precise time synchronization provided by a specific node. Upon failure of this node, the entire network cannot communicate. Butler removes this single point of failure by quickly synchronizing all nodes in the network without affecting the protocols’ performance. In the second part, we focus on the challenges of integrating communication and various control concepts using classical time-triggered and modern event-based approaches. Based on the design, implementation, and evaluation of the proposed solutions using real systems and networks, we make the following contributions, which in many ways push the boundaries of previous approaches: • We are the first to demonstrate and evaluate fast feedback control over low-power wireless multi-hop networks. Essential for this achievement is a novel co-design and integration of communication and control. Our wireless embedded platform tames the imperfections impairing control, for example, message loss and varying delays, and considers the resulting key properties in the control design. Furthermore, the careful orchestration of control and communication tasks enables real-time operation and makes our system amenable to an end-to-end analysis. Due to this, we can provably guarantee closed-loop stability for physical processes with linear time-invariant dynamics. • We propose control-guided communication, a novel co-design for distributed self-triggered control over wireless multi-hop networks. Self-triggered control can save energy by transmitting data only when needed. However, there are no solutions that bring those savings to multi-hop networks and that can reallocate freed-up resources, for example, to other agents. Our control system informs the communication system of its transmission demands ahead of time so that communication resources can be allocated accordingly. Thus, we can transfer the energy savings from the control to the communication side and achieve an end-to-end benefit. • We present a novel co-design of distributed control and wireless communication that resolves overload situations in which the communication demand exceeds the available bandwidth. As systems scale up, featuring more agents and higher bandwidth demands, the available bandwidth will be quickly exceeded, resulting in overload. While event-triggered control and self-triggered control approaches reduce the communication demand on average, they cannot prevent that potentially all agents want to communicate simultaneously. We address this limitation by dynamically allocating the available bandwidth to the agents with the highest need. Thus, we can formally prove that our co-design guarantees closed-loop stability for physical systems with stochastic linear time-invariant dynamics.:Abstract Acknowledgements List of Abbreviations List of Figures List of Tables 1 Introduction 1.1 Motivation 1.2 Application Requirements 1.3 Challenges 1.4 State of the Art 1.5 Contributions and Road Map 2 Mixer: Efficient Many-to-All Broadcast in Dynamic Wireless Mesh Networks 2.1 Introduction 2.2 Overview 2.3 Design 2.4 Implementation 2.5 Evaluation 2.6 Discussion 2.7 Related Work 3 Butler: Increasing the Availability of Low-Power Wireless Communication Protocols 3.1 Introduction 3.2 Motivation and Background 3.3 Design 3.4 Analysis 3.5 Implementation 3.6 Evaluation 3.7 Related Work 4 Feedback Control Goes Wireless: Guaranteed Stability over Low-Power Multi-Hop Networks 4.1 Introduction 4.2 Related Work 4.3 Problem Setting and Approach 4.4 Wireless Embedded System Design 4.5 Control Design and Analysis 4.6 Experimental Evaluation 4.A Control Details 5 Control-Guided Communication: Efficient Resource Arbitration and Allocation in Multi-Hop Wireless Control Systems 5.1 Introduction 5.2 Problem Setting 5.3 Co-Design Approach 5.4 Wireless Communication System Design 5.5 Self-Triggered Control Design 5.6 Experimental Evaluation 6 Scaling Beyond Bandwidth Limitations: Wireless Control With Stability Guarantees Under Overload 6.1 Introduction 6.2 Problem and Related Work 6.3 Overview of Co-Design Approach 6.4 Predictive Triggering and Control System 6.5 Adaptive Communication System 6.6 Integration and Stability Analysis 6.7 Testbed Experiments 6.A Proof of Theorem 4 6.B Usage of the Network Bandwidth for Control 7 Conclusion and Outlook 7.1 Contributions 7.2 Future Directions Bibliography List of Publication

    Alternative Water Supply Systems

    Get PDF
    This is the final version. Available on open access from IWA Publishing via the DOI in this recordOwing to climate change related uncertainties and anticipated population growth, different parts of the developing and the developed world (particularly urban areas) are experiencing water shortages or flooding and security of fit-for-purpose supplies is becoming a major issue. The emphasis on decentralized alternative water supply systems has increased considerably. Most of the information on such systems is either scattered or focuses on large scale reuse with little consideration given to decentralized small to medium scale systems. Alternative Water Supply Systems brings together recent research into the available and innovative options and additionally shares experiences from a wide range of contexts from both developed and developing countries. Alternative Water Supply Systems covers technical, social, financial and institutional aspects associated with decentralized alternative water supply systems. These include systems for greywater recycling, rainwater harvesting, recovery of water through condensation and sewer mining. A number of case studies from the UK, the USA, Australia and the developing world are presented to discuss associated environmental and health implications. The book provides insights into a range of aspects associated with alternative water supply systems and an evidence base (through case studies) on potential water savings and trade-offs. The information organized in the book is aimed at facilitating wider uptake of context specific alternatives at a decentralized scale mainly in urban areas. This book is a key reference for postgraduate level students and researchers interested in environmental engineering, water resources management, urban planning and resource efficiency, water demand management, building service engineering and sustainable architecture. It provides practical insights for water professionals such as systems designers, operators, and decision makers responsible for planning and delivering sustainable water management in urban areas through the implementation of decentralized water recycling

    Measurement of Triple-Differential Z+Jet Cross Sections with the CMS Detector at 13 TeV and Modelling of Large-Scale Distributed Computing Systems

    Get PDF
    The achievable precision in the calculations of predictions for observables measured at the LHC experiments depends on the amount of invested computing power and the precision of input parameters that go into the calculation. Currently, no theory exists that can derive the input parameter values for perturbative calculations from first principles. Instead, they have to be derived from measurements in dedicated analyses that measure observables sensitive to the input parameters with high precision. Such an analysis that measures the production cross section of oppositely charged muon pairs with an invariant mass close to the mass of the Z\mathrm{Z} boson in association with jets in a phase space divided into bins of the transverse momentum of the dimuon system pTZp_T^\text{Z}, and two observables yy^* and yby_b created from the rapidities of the dimuon system and the jet with the highest momentum is presented. To achieve the highest statistical precision in this triple-differential measurement the full data recorded by the CMS experiment at a center-of-mass energy of s=13TeV\sqrt{s}=13\,\mathrm{TeV} in the years 2016 to 2018 is combined. The measured cross sections are compared to theoretical predictions approximating full NNLO accuracy in perturbative QCD. Deviations from these predictions are observed rendering further studies at full NNLO accuracy necessary. To obtain the measured results large amounts of data are processed and analysed on distributed computing infrastructures. Theoretical calculations pose similar computing demands. Consequently, substantial amounts of storage and processing resources are required by the LHC collaborations. These requirements are met in large parts by the resources of the WLCG, a complex federation of globally distributed computer centres. With the upgrade of the LHC and the experiments, in the HL-LHC era, the computing demands are expected to increase substantially. Therefore, the prevailing computing models need to be updated to cope with the unprecedented demands. For the design of future adaptions of the HEP workflow executions on infrastructures a simulation model is developed, and an implementation tested on infrastructure design candidates inspired by a proposal of the German HEP computing community. The presented study of these infrastructure candidates showcases the applicability of the simulation tool in the strategical development of a future computing infrastructure for HEP in the HL-LHC context

    D4.2 Intelligent D-Band wireless systems and networks initial designs

    Get PDF
    This deliverable gives the results of the ARIADNE project's Task 4.2: Machine Learning based network intelligence. It presents the work conducted on various aspects of network management to deliver system level, qualitative solutions that leverage diverse machine learning techniques. The different chapters present system level, simulation and algorithmic models based on multi-agent reinforcement learning, deep reinforcement learning, learning automata for complex event forecasting, system level model for proactive handovers and resource allocation, model-driven deep learning-based channel estimation and feedbacks as well as strategies for deployment of machine learning based solutions. In short, the D4.2 provides results on promising AI and ML based methods along with their limitations and potentials that have been investigated in the ARIADNE project

    Applications

    Get PDF
    Volume 3 describes how resource-aware machine learning methods and techniques are used to successfully solve real-world problems. The book provides numerous specific application examples: in health and medicine for risk modelling, diagnosis, and treatment selection for diseases in electronics, steel production and milling for quality control during manufacturing processes in traffic, logistics for smart cities and for mobile communications

    DDoS Capability and Readiness - Evidence from Australian Organisations

    Get PDF
    A common perception of cyber defence is that it should protect systems and data from malicious attacks, ideally keeping attackers outside of secure perimeters and preventing entry. Much of the effort in traditional cyber security defence is focused on removing gaps in security design and preventing those with legitimate permissions from becoming a gateway or resource for those seeking illegitimate access. By contrast, Distributed Denial of Service (DDoS) attacks do not use application backdoors or software vulnerabilities to create their impact. They instead utilise legitimate entry points and knowledge of system processes for illegitimate purposes. DDoS seeks to overwhelm system and infrastructure resources so that legitimate requests are prevented from reaching their intended destination. For this thesis, a literature review was performed using sources from two perspectives. Reviews of both industry literature and academic literature were combined to build a balanced view of knowledge of this area. Industry and academic literature revealed that DDoS is outpacing internet growth, with vandalism, criminal and ideological motivations rising to prominence. From a defence perspective, the human factor remains a weak link in cyber security due to proneness for mistakes, oversights and the variance in approach and methods expressed by differing cultures. How cyber security is perceived, approached, and applied can have a critical effect on the overall outcome achieved, even when similar technologies are implemented. In addition, variance in the technical capabilities of those responsible for the implementation may create further gaps and vulnerabilities. While discussing technical challenges and theoretical concepts, existing literature failed to cover the experiences held by the victim organisations, or the thoughts and feelings of their personnel. This thesis addresses these identified gaps through exploratory research, which used a mix of descriptive and qualitative analysis to develop results and conclusions. The websites of 60 Australian organisations were analysed to uncover the level and quality of cyber security information they were willing to share and the methods and processes they used to engage with their audience. In addition, semi-structured interviews were conducted with 30 employees from around half of those websites analysed. These were analysed using NVivo12 qualitative analysis software. The difficulty experienced with attracting willing participants reflected the comfort that organisations showed with sharing cyber security information and experiences. However, themes found within the results show that, while DDoS is considered a valid threat, without encouragement to collaborate and standardise minimum security levels, firms may be missing out on valuable strategies to improve their cyber security postures. Further, this reluctance to share leads organisations to rely on their own internal skill and expertise, thus failing to realise the benefits of established frameworks and increased diversity in the workforce. Along with the size of the participant pool, other limitations included the diversity of participants and the impact of COVID-19 which may have influenced participants' thoughts and reflections. These limitations however, present opportunity for future studies using greater participant numbers or a narrower target focus. Either option would be beneficial to the recommendations of this study which were made from a practical, social, theoretical and policy perspective. On a practical and social level, organisational capabilities suffer due to the lack of information sharing and this extends to the community when similar restrictions prevent collaboration. Sharing of knowledge and experiences while protecting sensitive information is a worthy goal and this is something that can lead to improved defence. However, while improved understanding is one way to reduce the impact of cyber-attacks, the introduction of minimum cyber security standards for products, could reduce the ease at which devices can be used to facilitate attacks, but only if policy and effective governance ensures product compliance with legislation. One positive side to COVID-19's push to remote working, was an increase in digital literacy. As more roles were temporarily removed from their traditional physical workplace, many employees needed to rapidly accelerate their digital competency to continue their employment. To assist this transition, organisations acted to implement technology solutions that eased the ability for these roles to be undertaken remotely and as a consequence, they opened up these roles to a greater pool of available candidates. Many of these roles are no longer limited to the geographical location of potential employees or traditional hours of availability. Many of these roles could be accessed from almost anywhere, at any time, which had a positive effect on organisational capability and digital sustainability

    Signalling Design in Sensor-Assisted mmWave Communications for Cooperative Driving

    Get PDF
    Millimeter-Wave (mmWave) Vehicle-To-Vehicle (V2V) communications are a key enabler for connected and automated vehicles, as they support the low-latency exchange of control signals and high-resolution imaging data for maneuvering coordination. The employment of mmWave V2V communications calls for Beam Alignment and Tracking (BAT) procedures to ensure that the antenna beams are properly steered during motion. The conventional beam sweeping approach is known to be unsuited for the high vehicular mobility and its large overhead reduces transmission efficiency. A promising solution to reduce BAT signalling foresees the integration of V2V communication systems with on-board vehicle sensors. We focus on a cooperative sensor-assisted architecture for mmWave V2V communications in line of sight, where vehicles exchange the estimate of antenna position and its uncertainty to compute the optimal beam direction and dimension. We analyze and compare different signalling strategies for sharing the information on antenna estimate, evaluating the tradeoff between signalling overhead and performance loss for different position and uncertainty encoding strategies. Main attention is given to differential quantization on both the antenna position and uncertainty. Analyses over realistic urban mobility trajectories suggest that differential approaches introduce a negligible performance loss while significantly reducing the BAT signalling communication overhead
    corecore