637 research outputs found

    A Survey of Recent Developments in Testability, Safety and Security of RISC-V Processors

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    With the continued success of the open RISC-V architecture, practical deployment of RISC-V processors necessitates an in-depth consideration of their testability, safety and security aspects. This survey provides an overview of recent developments in this quickly-evolving field. We start with discussing the application of state-of-the-art functional and system-level test solutions to RISC-V processors. Then, we discuss the use of RISC-V processors for safety-related applications; to this end, we outline the essential techniques necessary to obtain safety both in the functional and in the timing domain and review recent processor designs with safety features. Finally, we survey the different aspects of security with respect to RISC-V implementations and discuss the relationship between cryptographic protocols and primitives on the one hand and the RISC-V processor architecture and hardware implementation on the other. We also comment on the role of a RISC-V processor for system security and its resilience against side-channel attacks

    Towards trustworthy computing on untrustworthy hardware

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    Historically, hardware was thought to be inherently secure and trusted due to its obscurity and the isolated nature of its design and manufacturing. In the last two decades, however, hardware trust and security have emerged as pressing issues. Modern day hardware is surrounded by threats manifested mainly in undesired modifications by untrusted parties in its supply chain, unauthorized and pirated selling, injected faults, and system and microarchitectural level attacks. These threats, if realized, are expected to push hardware to abnormal and unexpected behaviour causing real-life damage and significantly undermining our trust in the electronic and computing systems we use in our daily lives and in safety critical applications. A large number of detective and preventive countermeasures have been proposed in literature. It is a fact, however, that our knowledge of potential consequences to real-life threats to hardware trust is lacking given the limited number of real-life reports and the plethora of ways in which hardware trust could be undermined. With this in mind, run-time monitoring of hardware combined with active mitigation of attacks, referred to as trustworthy computing on untrustworthy hardware, is proposed as the last line of defence. This last line of defence allows us to face the issue of live hardware mistrust rather than turning a blind eye to it or being helpless once it occurs. This thesis proposes three different frameworks towards trustworthy computing on untrustworthy hardware. The presented frameworks are adaptable to different applications, independent of the design of the monitored elements, based on autonomous security elements, and are computationally lightweight. The first framework is concerned with explicit violations and breaches of trust at run-time, with an untrustworthy on-chip communication interconnect presented as a potential offender. The framework is based on the guiding principles of component guarding, data tagging, and event verification. The second framework targets hardware elements with inherently variable and unpredictable operational latency and proposes a machine-learning based characterization of these latencies to infer undesired latency extensions or denial of service attacks. The framework is implemented on a DDR3 DRAM after showing its vulnerability to obscured latency extension attacks. The third framework studies the possibility of the deployment of untrustworthy hardware elements in the analog front end, and the consequent integrity issues that might arise at the analog-digital boundary of system on chips. The framework uses machine learning methods and the unique temporal and arithmetic features of signals at this boundary to monitor their integrity and assess their trust level

    GPU devices for safety-critical systems: a survey

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    Graphics Processing Unit (GPU) devices and their associated software programming languages and frameworks can deliver the computing performance required to facilitate the development of next-generation high-performance safety-critical systems such as autonomous driving systems. However, the integration of complex, parallel, and computationally demanding software functions with different safety-criticality levels on GPU devices with shared hardware resources contributes to several safety certification challenges. This survey categorizes and provides an overview of research contributions that address GPU devices’ random hardware failures, systematic failures, and independence of execution.This work has been partially supported by the European Research Council with Horizon 2020 (grant agreements No. 772773 and 871465), the Spanish Ministry of Science and Innovation under grant PID2019-107255GB, the HiPEAC Network of Excellence and the Basque Government under grant KK-2019-00035. The Spanish Ministry of Economy and Competitiveness has also partially supported Leonidas Kosmidis with a Juan de la Cierva Incorporación postdoctoral fellowship (FJCI-2020- 045931-I).Peer ReviewedPostprint (author's final draft

    'Extenuating circumstances' in the South African law of murder

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    The concept of statutory "extenuating circumstances" was' introduced into the South African criminal law of murder. 1935 in _tile use of those two words alone. It was left to the course, without any further legislative aid, to provide the definition, structure, and development of the concept. Over the· period of more than forty years there has been), ·no -written attempt to survey or deal at any length this development. Beside legal textbooks which give some brief rough grouping of certain of the cases . I (E.M PM A Hunt, South African Criminal law and procedure, Volume II allo6ates ten pages - the most detailed textbook handling of the matter so far there have been two , -c ' articles 1.n law journals ( one by ,the present writer in 195·5 and Loubser in 1977) which have attempted a form· 9f analysis or development of the subject. This thesis is in the nature of, pilot study along a certain line approach in an attempt to order the appropriate material. No entry has been made into the discussion of the substantive legal concepts in the law of murder or any ease of contention there, even though these may have been referred to in passing. Rather have the generally accepted '/ statements of the substantive law been accepted. What i's sough to be dealt with is the limited area of the relevance application of certain considerations appropriate only to the :sentencing function in cases where an accused is found guilty: if murder in South Africa. But even this limited·· .ficid of study has a dynamic broadness about it which ass6ciates with other disciplines such as ethics, anthropology, psychiatry and other psycho-social sciences

    Sizing and control of a Hybrid hydro-battery-flywheel storage system for frequency regulation services

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    Energy security and environmental challenges are some of the drivers for increasing the electricity generation from non-programmable Renewable Energy Source (RES), adding pressure to the grid, especially if located in weakly connected (or isolated) islands, like Sardinia. Variable-speed Pumped Storage Hydro Power (PSHP) can offer a high degree of flex ibility in providing ancillary services (namely primary and secondary regulations), but due to the hydromechanical nature of the equipment, sudden variations in the power output cause wear and tear. Other energy storage devices can not compete with PSHP in terms of energy and power availability. This work aims to assess the potential benefits derived from the hybridization of a PSHP with Battery Energy Storage System (BESS) and Flywheel Energy Storage System (FESS) in providing frequency regulation services to the grid of the Sardinia Island (Italy). The focus of the study tries to cross both the plant owner point of view, whose aim is to have a smooth PSHP operation and the economic incentive to hybridize the plant, and the Transmission System Operator’s, whose aim is to have a fast reacting plant that better stabilizes the grid frequency. This is done by simulations of a detailed dynamic model of the PSHP, whose hydraulic machine has been characterized from real experimental data, the BESS and the FESS. Moreover, two power management strategies are presented, based on different criteria, to effectively coordinate the devices making up the Hybrid Energy Storage System (HESS). First the simulations are performed open-loop, to assess the impact of various combinations of installed BESS and FESS powers over the wear and tear of the equipment. Later the model is used in an optimization procedure to find the combination of installed BESS and FESS powers and the respective controlparameters that would guarantee the maximum economic return at the end of the investment life. Last, the model is included into a Sardinian power system model and simulated in a future scenario with high RES penetration, assessing the plant capabilities to effectively contain and restore the frequency. Results show that there is not a catch-all solution in terms of hybridization and that a trade-off must be made between the plant owner’s urge to smoothly operate the plant in order to reduce the equipment degradation, and the TSO’s objective to have fast responsive plants providing high quality frequency regulation services. If on one hand open-loop simulations show that the hybridization reduce the main wear and tear indicators, on the other the optimal hybrid system limits the plant ability to contain the frequency excursions in closed-loop simulations, as the optimization problem was formulated over the plant owner’s interests. The results show that there much potential for frequency stabilization and wear and tear reduction, but more techno-economic data is required to fully investigate the benefits of this configuration.Energy security and environmental challenges are some of the drivers for increasing the electricity generation from non-programmable Renewable Energy Source (RES), adding pressure to the grid, especially if located in weakly connected (or isolated) islands, like Sardinia. Variable-speed Pumped Storage Hydro Power (PSHP) can offer a high degree of flex ibility in providing ancillary services (namely primary and secondary regulations), but due to the hydromechanical nature of the equipment, sudden variations in the power output cause wear and tear. Other energy storage devices can not compete with PSHP in terms of energy and power availability. This work aims to assess the potential benefits derived from the hybridization of a PSHP with Battery Energy Storage System (BESS) and Flywheel Energy Storage System (FESS) in providing frequency regulation services to the grid of the Sardinia Island (Italy). The focus of the study tries to cross both the plant owner point of view, whose aim is to have a smooth PSHP operation and the economic incentive to hybridize the plant, and the Transmission System Operator’s, whose aim is to have a fast reacting plant that better stabilizes the grid frequency. This is done by simulations of a detailed dynamic model of the PSHP, whose hydraulic machine has been characterized from real experimental data, the BESS and the FESS. Moreover, two power management strategies are presented, based on different criteria, to effectively coordinate the devices making up the Hybrid Energy Storage System (HESS). First the simulations are performed open-loop, to assess the impact of various combinations of installed BESS and FESS powers over the wear and tear of the equipment. Later the model is used in an optimization procedure to find the combination of installed BESS and FESS powers and the respective controlparameters that would guarantee the maximum economic return at the end of the investment life. Last, the model is included into a Sardinian power system model and simulated in a future scenario with high RES penetration, assessing the plant capabilities to effectively contain and restore the frequency. Results show that there is not a catch-all solution in terms of hybridization and that a trade-off must be made between the plant owner’s urge to smoothly operate the plant in order to reduce the equipment degradation, and the TSO’s objective to have fast responsive plants providing high quality frequency regulation services. If on one hand open-loop simulations show that the hybridization reduce the main wear and tear indicators, on the other the optimal hybrid system limits the plant ability to contain the frequency excursions in closed-loop simulations, as the optimization problem was formulated over the plant owner’s interests. The results show that there much potential for frequency stabilization and wear and tear reduction, but more techno-economic data is required to fully investigate the benefits of this configuration

    Global Chinese Initiatives and the emerging place of China in the international legal order

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    peer reviewedChina plays an increasingly significant role in global affairs, rebalancing the international political and economic order and promoting a shift in global power to the East. At the same time, along with its development reorientation, China has been attempting to establish itself as an active shaper of global legal governance. This paper presents the results of a non-doctrinal study on the legal dimension of the four global Chinese initiatives (namely, the Belt and Road Initiative, the Global Development Initiative, the Global Security Initiative, and the Global Civilization Initiative, plus the concept of “Community of Shared Future for Mankind”) within a broader framework of China’s changing role in the international legal order. The paper concludes with the place of the four initiatives in transforming Chinese approaches to law in foreign policy and claims that the new initiatives enhance China’s potential to promote its legal vision in the developing world

    Impact of peer-to-peer trading and flexibility on local energy systems

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    To meet the 2050 net zero emission targets, energy systems around the globe are being revisited to achieve multi-vector decarbonisation in terms of electricity, transport, heating and cooling. As energy systems become more decentralised and digitised, local energy systems will have greater potential to self-sustain and hence, decrease reliance on fossil-fuelled central generation. While the uptake of electric vehicles, heat pumps, solar and battery systems offer a solution, the increase in electricity demand poses challenges in terms of higher peak demand, imbalance and overloading. Additionally, the current energy market structure prevents these assets in the distribution network from reaching their true techno-economic potential in flexibility services and energy trading. Peer-to-peer energy trading and community-level control algorithms achieve better matching of local demand and supply through the use of transactive energy markets, load shifting and peak shaving techniques. Existing research addresses the challenges of local energy markets and others investigate the effect of increased distributed assets on the network. However, the combined techno-economic effect requires the co-simulation of both market and network levels, coupled with simultaneous system balance, cost and carbon intensity considerations. Using bottom-up coordination and user-centric optimisation, this project investigated the potential of network-aware peer-to-peer trading and community-level control to increase self-sufficiency and self-consumption in energy communities. The techno-economic effects of these strategies are modelled while maintaining user comfort levels and healthy operation of the network and assets. The proposed strategies are evaluated according to their economic benefit, environmental impact and network stress. A case study in Scotland was employed to demonstrate the benefits of peer-to-peer trading and community self-consumption using future projections of demand, generation and storage. Additionally, the concept of energy smart contracts, embedded in blockchains, are proposed and demonstrated to overcome the major challenges of monitoring and contracting. The results indicate benefits for various energy systems stakeholders. Distribution system end-users benefit from lower energy costs while system operators obtain better visibility of the local-level flexibility along with the associated technical challenges in terms of losses, imbalance and loading. From a commercial perspective, community energy companies may utilise this study to inform investment decisions regarding storage, distributed generation and transactive market solutions. Additionally, the insights about the energy smart contracts allow blockchain and relevant technology sectors to recognise the opportunities and challenges of smart contracts and distributed ledger technologies that are specific to the energy sector. On the broader scale, energy system operators, regulators and high-level decision-makers can compare the simulated impact of community-led energy transition on the net zero goals with large-scale top-down initiatives
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