8,819 research outputs found

    ERASMUS: Efficient Remote Attestation via Self- Measurement for Unattended Settings

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    Remote attestation (RA) is a popular means of detecting malware in embedded and IoT devices. RA is usually realized as an interactive protocol, whereby a trusted party -- verifier -- measures integrity of a potentially compromised remote device -- prover. Early work focused on purely software-based and fully hardware-based techniques, neither of which is ideal for low-end devices. More recent results have yielded hybrid (SW/HW) security architectures comprised of a minimal set of features to support efficient and secure RA on low-end devices. All prior RA techniques require on-demand operation, i.e, RA is performed in real time. We identify some drawbacks of this general approach in the context of unattended devices: First, it fails to detect mobile malware that enters and leaves the prover between successive RA instances. Second, it requires the prover to engage in a potentially expensive (in terms of time and energy) computation, which can be harmful for critical or real-time devices. To address these drawbacks, we introduce the concept of self-measurement where a prover device periodically (and securely) measures and records its own software state, based on a pre-established schedule. A possibly untrusted verifier occasionally collects and verifies these measurements. We present the design of a concrete technique called ERASMUS : Efficient Remote Attestation via Self-Measurement for Unattended Settings, justify its features and evaluate its performance. In the process, we also define a new metric -- Quality of Attestation (QoA). We argue that ERASMUS is well-suited for time-sensitive and/or safety-critical applications that are not served well by on-demand RA. Finally, we show that ERASMUS is a promising stepping stone towards handling attestation of multiple devices (i.e., a group or swarm) with high mobility

    Tribological investigations of the piston assembly and liner of a gasoline engine

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    The automotive industry is being forced towards greater efficiency, increased engine power from smaller engines and lower environmental impact by both governmental legislation and public opinion. Oil drain intervals are increasing whilst emissions legislation limit the use of current wear protection and antioxidant additives containing elements such as phosphorus and sulphur. To address these demands and challenges an increased understanding of the link between lubricant degradation, its transport and residence time, and the effect on piston assembly tribology is required. The aim of the work reported in this paper was to further develop the understanding of the effect degraded lubricants have on piston assembly tribology. The small oil volumes and environmental conditions in the piston assembly make the affective lubrication and protection of components in this region one of the most challenging areas of tribology. This was carried out through an extensive experimental programme using a research engine, tribometer testing and chemical and rheological analysis of lubricant samples

    Extraction and tribological investigation of top piston ring zone oil from a gasoline engine

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    With tightening emission regulations, increased expected fuel economy, and longer drain intervals impacting on lubricant formulation, greater understanding of how oil degrades in an automotive engine is becoming ever more important. Equally significant is the effect that this degraded lubricant has on the tribological operation of the engine, particularly its overall internal friction and component wear. In a previous paper, four tests to degrade oil in a single cylinder engine were reported [1]. These tests were set up such that the lubricating oil was degraded in the ring pack before returning to the sump, where it was sampled and chemical and rheological analysis undertaken. This paper reports the extension of this work using the same Hydra engine and describes how oil has additionally been extracted from the rear of the top piston ring during engine operation. This extracted oil has then been subjected to similar analysis as the sump oil samples in the previous tests, along with additional analysis to look at the tribological properties of the oil using tribometers. The results clearly show significant differences in the rheological, tribological, and chemical properties of the fresh oil and used sump oil samples when compared with the top ring zone (TRZ) oil samples, particularly the effect of load on the levels of volatiles present in the TRZ samples and their effect on traction and friction coefficient values during tribological testing

    Adding Salt to Pepper: A Structured Security Assessment over a Humanoid Robot

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    The rise of connectivity, digitalization, robotics, and artificial intelligence (AI) is rapidly changing our society and shaping its future development. During this technological and societal revolution, security has been persistently neglected, yet a hacked robot can act as an insider threat in organizations, industries, public spaces, and private homes. In this paper, we perform a structured security assessment of Pepper, a commercial humanoid robot. Our analysis, composed by an automated and a manual part, points out a relevant number of security flaws that can be used to take over and command the robot. Furthermore, we suggest how these issues could be fixed, thus, avoided in the future. The very final aim of this work is to push the rise of the security level of IoT products before they are sold on the public market.Comment: 8 pages, 3 figures, 4 table

    HYDRA: Macroscopic modeling of hybrid ablative thermal protection system

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    In the framework of HYDRA, an European funded program, technological solutions of hybrid Thermal Protection System (TPS) are developed. This advanced shielding relies on the hybridization of upper lightweight porous ablative material and inner Ceramic Matrix Composite (CMC) bonded together with a novel high temperature adhesive. The aerial mass optimization of the full TPS requires a controlled reduction in the ablative material thickness to reach high operating temperature configuration of the CMC. Therefore, radiative heat transfer takes place in a thin layer of ablator and becomes a major contributor to the elevation of the interface temperature. In this paper we develop an high fidelity radiative transfer in porous carbon fibers charring and ablative material. Specific elementary characterization, plasma test campaign and numerical simulation are scheduled to feed this radiative heat transfer model

    Influence of gasoline engine lubricant on tribological performance, fuel economy and emissions

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    The requirement for increased performance, improved fuel economy and reduced emissions is constantly sustaining the demand for research into combustion, fuels and lubricants. Due to the nature of the operation of an engine and the current market climate the lubricant not only has to respond to these requirements, but also to changes in engine design, fuelling methods and fuel types, increased power densities and developments in emissions formation and after-treatment. This paper will describe advances made at the authors’ institution to elucidate the influence of gasoline engine lubricant on tribological performance, fuel economy and emissions, giving examples of work undertaken and then look to future possible lubricant demands

    An overview of the Amoeba distributed operating system

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    As hardware prices continue to drop rapidly, building large computer systems by interconnecting substantial numbers of microcomputers becomes increasingly attractive. Many techniques for interconnecting the hardware, such as Ethernet [Metcalfe and Boggs, 1976], ring nets [Farber and Larson, 1972], packet switching, and shared memory are well understood, but the corresponding software techniques are poorly understood. The design of general purpose distributed operating systems is one of the key research issues for the 1980s

    A new method of utilising stability study results in applying out-of-step protection to allow observability of rotor angle unstable conditions

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    Power system rotor-angle unstable conditions may cause undesired operation of distance relays, resulting in the unnecessary switching of lines. To prevent the possible undesired operation of distance relays, a protection type known as out-of-step blocking is used. This protection type is complemented by another type of protection, known as out-of-step tripping protection. The tripping protection's main functions are to detect total loss of synchronism and send tripping signals to selected locations in the system to initiate islanding. In this research the application of out-of-step blocking and tripping protection was investigated. The motivation for the research was provided by system unstable incidents that occurred in Eskom, the electricity utility of South Africa. Detailed out-of-step protection investigations indicated that the out-of-step blocking and tripping protection applied according to a method which is based on an existing approach failed to detect the unstable conditions. In summary, the detailed investigations showed that the existing approach of applying out-of-step blocking and tripping protection is not adequate as it does not allow the necessary observability1 and correct detection of rotor-angle unstable conditions
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