1,823 research outputs found

    A Mobile Secure Bluetooth-Enabled Cryptographic Provider

    Get PDF
    The use of digital X509v3 public key certificates, together with different standards for secure digital signatures are commonly adopted to establish authentication proofs between principals, applications and services. One of the robustness characteristics commonly associated with such mechanisms is the need of hardware-sealed cryptographic devices, such as Hardware-Security Modules (or HSMs), smart cards or hardware-enabled tokens or dongles. These devices support internal functions for management and storage of cryptographic keys, allowing the isolated execution of cryptographic operations, with the keys or related sensitive parameters never exposed. The portable devices most widely used are USB-tokens (or security dongles) and internal ships of smart cards (as it is also the case of citizen cards, banking cards or ticketing cards). More recently, a new generation of Bluetooth-enabled smart USB dongles appeared, also suitable to protect cryptographic operations and digital signatures for secure identity and payment applications. The common characteristic of such devices is to offer the required support to be used as secure cryptographic providers. Among the advantages of those portable cryptographic devices is also their portability and ubiquitous use, but, in consequence, they are also frequently forgotten or even lost. USB-enabled devices imply the need of readers, not always and not commonly available for generic smartphones or users working with computing devices. Also, wireless-devices can be specialized or require a development effort to be used as standard cryptographic providers. An alternative to mitigate such problems is the possible adoption of conventional Bluetooth-enabled smartphones, as ubiquitous cryptographic providers to be used, remotely, by client-side applications running in users’ devices, such as desktop or laptop computers. However, the use of smartphones for safe storage and management of private keys and sensitive parameters requires a careful analysis on the adversary model assumptions. The design options to implement a practical and secure smartphone-enabled cryptographic solution as a product, also requires the approach and the better use of the more interesting facilities provided by frameworks, programming environments and mobile operating systems services. In this dissertation we addressed the design, development and experimental evaluation of a secure mobile cryptographic provider, designed as a mobile service provided in a smartphone. The proposed solution is designed for Android-Based smartphones and supports on-demand Bluetooth-enabled cryptographic operations, including standard digital signatures. The addressed mobile cryptographic provider can be used by applications running on Windows-enabled computing devices, requesting digital signatures. The solution relies on the secure storage of private keys related to X509v3 public certificates and Android-based secure elements (SEs). With the materialized solution, an application running in a Windows computing device can request standard digital signatures of documents, transparently executed remotely by the smartphone regarded as a standard cryptographic provider

    Leading Alternatives to Fossil Fuels for Powering Vehicles

    Get PDF
    With respect to environmental stewardship, the research question in this project was: which alternative fuel/ power source best supplants fossil fuels as a primary mode of powering vehicles? It details five of today’s leading alternatives: compressed natural gas, biodiesel/biofuels, hydrogen fuel cells, all-electric vehicles, and solar-powered vehicles. The project presents appreciable research on each fuel/power source focused on defining each option, explaining how it works, and its advantages and disadvantages as compared to vehicles propelled by traditional petroleum products. Electric and solar vehicles (or a combination thereof) are most compelling as likely successors to fossil fuels into the future due to their resource renewability and minimal negative environmental impact. A narrowed, tangential focus was directed toward fueling or powering fire service apparatus

    Understanding Household Preferences For Alternative-Fuel Vehicle Technologies

    Get PDF
    This report explores consumer preferences among four different alternative-fuel vehicles (AFVs): hybrid electric vehicles (HEVs), compressed natural gas (CNG) vehicles, hydrogen fuel cell (HFC) vehicles, and electric vehicles (EVs). Although researchers have been interested in understanding consumer preferences for AFVs for more than three decades, it is important to update our estimates of the trade-offs people are willing to make between cost, environmental performance, vehicle range, and refuel¬ing convenience. We conducted a nationwide, Internet-based survey to assess consumer preferences for AFVs. Respondents participated in a stated-preference ranking exercise in which they ranked a series of five vehicles (four AFVs and a traditional gasoline-fueled vehicle) that differ primarily in fuel type, price, environmental performance, vehicle range, and refueling conve¬nience. Our findings indicate that, in general, gasoline-fueled vehicles are still preferred over AFVs, however there is a strong interest in AFVs. No AFV type is overwhelmingly preferred, although HEVs seem to have an edge. Using a panel rank-ordered mixed logit model, we assessed the trade-offs people make between key AFV characteristics. We found that, in order to leave a person’s utility unchanged, a 1,000increaseinAFVcostneedstobecompensatedbyeither:(1)a1,000 increase in AFV cost needs to be compensated by either: (1) a 300 savings in driving cost over 12,000 miles; (2) a 17.5 mile increase in vehicle range; or (3) a 7.8-minute decrease in total refueling time (e.g. finding a gas station and refueling)

    The design and analysis of novel integrated phase-change photonic memory and computing devices

    Get PDF
    The current massive growth in data generation and communication challenges traditional computing and storage paradigms. The integrated silicon photonic platform may alleviate the physical limitations resulting from the use of electrical interconnects and the conventional von Neuman computing architecture, due to its intrinsic energy and bandwidth advantages. This work focuses on the development of the phase-change all-photonic memory (PPCM), a device potentially enabling the transition from the electrical to the optical domain by providing the (previously unavailable) non-volatile all-photonic storage functionality. PPCM devices allow for all-optical encoding of the information on the crystal fraction of a waveguide-implemented phase-change material layer, here Ge2Sb2Te5, which in turn modulates the transmitted signal amplitude. This thesis reports novel developments of the numerical methods necessary to emulate the physics of PPCM device operation and performance characteristics, illustrating solutions enabling the realization of a simulation framework modelling the inherently three-dimensional and self-influencing optical, thermal and phase-switching behaviour of PPCM devices. This thesis also depicts an innovative, fast and cost-effective method to characterise the key optical properties of phase-change materials (upon which the performance of PPCM devices depend), exploiting the reflection pattern of a purposely built layer stack, combined with a smart fit algorithm adapting potential solutions drawn from the scientific literature. The simulation framework developed in the thesis is used to analyse reported PPCM experimental results. Numerous sources of uncertainty are underlined, whose systematic analysis reduced to the peculiar non-linear optical properties of Ge2Sb2Te5. Yet, the data fit process validates both the simulation tool and the remaining physical assumptions, as the model captures the key aspects of the PPCM at high optical intensity, and reliably and accurately predicts its behaviour at low intensity, enabling to investigate its underpinning physical mechanisms. Finally, a novel PPCM memory architecture, exploiting the interaction of a much-reduced Ge2Sb2Te5 volume with a plasmonic resonant nanoantenna, is proposed and numerically investigated. The architecture concept is described and the memory functionality is demonstrated, underlining its potential energy and speed improvement on the conventional device by up to two orders of magnitude.Engineering and Physical Sciences Research Council (EPSRC

    System design of a hydrogen induction system as a retrofit item compatible with existing internal combustion engines

    Get PDF
    As the current method of delivering the world’s transportation energy demand via fossil fuels becomes increasingly unsustainable, vehicle manufactures and organisations are looking to alternative energy sources for vehicle propulsion such as hydrogen fuel. This project has been undertaken to establish the feasibility of the System Design of a Hydrogen Induction System as a Retrofit Item Compatible with Existing Internal Combustion Engines, by examining the conversion of a Holden 5.0L V8 to accommodate hydrogen combustion. The for the purpose of analysis, a Holden HX GTS sedan has been chosen as a case study vehicle, commonly optioned with the first generation Holden 5.0L V8. Analysis of urban and extra-urban drive cycles provided theoretical power requirements for the operation of the vehicle for the duration of the cycles. Outputs from the drive cycle analysis were used in an engine simulation model that was modified to accommodate simulation of hydrogen combustion. Input values for average power and engine speed required to maintain velocity along the drive cycles are supplied to the engine simulation model. The engine simulation model returns a hydrogen fuel consumption of 4.18 kg/100km and 5.34 kg/100km for the extra- urban and urban driving cycles respectively, a gasoline gallon equivalent of 15.4 L/100km and 20.27 L/100km. This provides a theoretical endurance of 133.62 km and 104.14 km from vehicles proposed 5.6 kg of useable hydrogen storage for the cycles respectively. An extensive literature review is used to identify design modifications that are required to accommodate hydrogen combustion in internal combustion engines. A trade study is used to identify the measures specifically required to adapt the Holden 5.0L case study engine to dual hydrogen/petrol operation modes. The modifications and additional components required were costed where possible, resulting in an estimated minimum cost of AUD $12,664 in parts for the conversion

    A finite element approach for the implementation of magnetostrictive material terfenol-D in automotive CNG fuel injection actuation

    Get PDF
    Magnetostriction is the deformation that spontaneously occurs in ferromagnetic materials when an external magnetic field is applied. In applications broadly defined for actuation, magnetostrictive material Terfenol-D possesses intrinsic rapid response times while providing small and accurate displacements and high-energy efficiency, which are some of the essential parameters required for fast control of fuel injector valves for decreased engine emissions and lower fuel consumption compared with the traditional solenoid fuel injection system. A prototype CNG fuel injector assembly was designed, which primarily included magnetostrictive material Terfenol-D as the actuator material, 1020 Steel having soft magnetic properties as the injector housing material, AWG copper wire as the coil material and 316 Stainless Steel having non-magnetic properties as the plunger material. A 2D cross-sectional geometry including the injector housing, coil, Terfenol-D shaft, and plunger, was modeled in both Finite Element Method Magnetics (FEMM) and ANSYS for 2D axisymmetric magnetic simulation. The magnetic simulations were performed in order to determine the coil-circuit parameters and the magnetic field strength to achieve the required magnetostrictive strain, and consequently, the injector needle lift. The FEMM magnetic simulations were carried out with four different types of AWG coil wires and four different injector coil thicknesses in order to evaluate the relationship between the different coil types and thicknesses against the achieved strain or injector lift. Eventually, the optimized parameter obtained from FEMM results analysis was verified against ANSYS electromagnetic simulation. Subsequently, a three dimensional replica of the CNG flow conduit was modelled in GAMBIT with the resultant injector lift. The meshed conduit was then simulated in FLUENT using the 3D time independent segregated solver with standard k-Δ, realizable k-Δ and RSM turbulent models to predict the mass flow rate of CNG to be injected. Eventually, the simulated flow rates were verified against mathematically derived static flow rate required for a standard automotive fuel injector considering standard horsepower, BSFC and injector duty cycle
    • 

    corecore