73,662 research outputs found

    Bootstrap tomography of high-precision pulses for quantum control

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    Long-time dynamical decoupling and quantum control of qubits require high-precision control pulses. Full characterization (quantum tomography) of imperfect pulses presents a bootstrap problem: tomography requires initial states of a qubit which can not be prepared without imperfect pulses. We present a protocol for pulse error analysis, specifically tailored for a wide range of the single solid-state electron spins. Using a single electron spin of a nitrogen-vacancy (NV) center in diamond, we experimentally verify the correctness of the protocol, and demonstrate its usefulness for quantum control tasks

    Bootstrapping opportunistic networks using social roles

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    Opportunistic routing protocols can enable message delivery in disconnected networks of mobile devices. To conserve energy in mobile environments, such routing protocols must minimise unnecessary message-forwarding. This paper presents an opportunistic routing protocol that leverages social role information. We compute node roles from a social network graph to identify nodes with similar contact relationships, and use these roles to determine routing decisions. By using pre-existing social network information, such as online social network friends, to determine roles, we show that our protocol can bootstrap a new opportunistic network without the delay incurred by encounter-history-based routing protocols such as SimbetTS. Simulations with four real-world datasets show improved performance over SimbetTS, with performance approaching Epidemic routing in some scenarios.Postprin

    Does the Kyoto Protocol Agreement matters? An environmental efficiency analysis

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    This paper uses both conditional and unconditional Data Envelopment Analysis (DEA) models in order to determine different environmental efficiency levels for a sample of 110 countries in 2007. In order to capture the effect of countries compliance with the Kyoto Protocol Agreement (KPA), we condition the years since a country has signed the agreement until 2007. Particularly, various DEA models have been applied alongside with bootstrap techniques in order to determine the effect of Kyoto protocol agreement on countries’ environmental efficiencies. The study illustrates how the recent developments in efficiency analysis and statistical inference can be applied when evaluating environmental performance issues. The results indicate that the first six years after countries signed the Kyoto protocol agreement have a positive effect on their environmental efficiencies. However after that period it appears that countries avoid complying with the actions imposed by the agreement which in turn has an immediate negative effect on their environmental efficiencies.Environmental efficiency; Kyoto protocol agreement; Conditional full frontiers; Statistical inference; DEA

    KALwEN: a new practical and interoperable key management scheme for body sensor networks

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    Key management is the pillar of a security architecture. Body sensor networks (BSNs) pose several challenges–some inherited from wireless sensor networks (WSNs), some unique to themselves–that require a new key management scheme to be tailor-made. The challenge is taken on, and the result is KALwEN, a new parameterized key management scheme that combines the best-suited cryptographic techniques in a seamless framework. KALwEN is user-friendly in the sense that it requires no expert knowledge of a user, and instead only requires a user to follow a simple set of instructions when bootstrapping or extending a network. One of KALwEN's key features is that it allows sensor devices from different manufacturers, which expectedly do not have any pre-shared secret, to establish secure communications with each other. KALwEN is decentralized, such that it does not rely on the availability of a local processing unit (LPU). KALwEN supports secure global broadcast, local broadcast, and local (neighbor-to-neighbor) unicast, while preserving past key secrecy and future key secrecy (FKS). The fact that the cryptographic protocols of KALwEN have been formally verified also makes a convincing case. With both formal verification and experimental evaluation, our results should appeal to theorists and practitioners alike

    KALwEN: A New Practical and Interoperable Key Management Scheme for Body Sensor Networks

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    Key management is the pillar of a security architecture. Body sensor networks(BSNs) pose several challenges -- some inherited from wireless sensor networks(WSNs), some unique to themselves -- that require a new key management scheme to be tailor-made. The challenge is taken on, and the result is KALwEN, a new lightweight scheme that combines the best-suited cryptographic techniques in a seamless framework. KALwEN is user-friendly in the sense that it requires no expert knowledge of a user, and instead only requires a user to follow a simple set of instructions when bootstrapping or extending a network. One of KALwEN's key features is that it allows sensor devices from different manufacturers, which expectedly do not have any pre-shared secret, to establish secure communications with each other. KALwEN is decentralized, such that it does not rely on the availability of a local processing unit (LPU). KALwEN supports global broadcast, local broadcast and neighbor-to-neighbor unicast, while preserving past key secrecry and future key secrecy. The fact that the cryptographic protocols of KALwEN have been formally verified also makes a convincing case

    Realizing the potential of fluvial archives using robust OSL chronologies

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    Optically Stimulated Luminescence (OSL) dating has enormous potential for interpreting fluvial sediments, because the mineral grains used for OSL dating are abundant in fluvial deposits. However, the limited light exposure of mineral grains during fluvial transport and deposition often leads to scatter and inaccuracy in OSL dating results. Here we present a statistical protocol which aims to overcome these difficulties. Rather than estimating a single burial age for a sample, we present ages as likelihood functions created by bootstrap re-sampling of the equivalent-dose data. The bootstrap likelihoods incorporate uncertainty from age-model parameters and plausible variation in the input data. This approach has the considerable advantage that it permits Bayesian methods to be used to interpret sequences containing multiple samples, including partially bleached OSL data. We apply the statistical protocol to both single-grain and small-aliquot OSL data from samples of recent fluvial sediment. The combination of bootstrap likelihoods and Bayesian processing may greatly improve OSL chronologies for fluvial sediment, and allow OSL ages from partially bleached samples to be combined with other age information

    A new security architecture for SIP based P2P computer networks

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    Many applications are transferred from C/S (Client/Server) mode to P2P (Peer-to-Peer) mode such as VoIP (Voice over IP). This paper presents a new security architecture, i.e. a trustworthy authentication algorithm of peers, for Session Initialize Protocol (SIP) based P2P computer networks. A mechanism for node authentication using a cryptographic primitive called one-way accumulator is proposed to secure the P2P SIP computer networks. It leverages the distributed nature of P2P to allow for distributed resource discovery and rendezvous in a SIP network, thus eliminating (or at least reducing) the need for centralized servers. The distributed node authentication algorithm is established for the P2P SIP computer networks. The corresponding protocol has been implemented in our P2P SIP experiment platform successfully. The performance study has verified the proposed distributed node authentication algorithm for SIP based P2P computer networks

    SAFE: Secure-Roaming Agents for E-commerce

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    The development of the Internet has made a powerful impact on the concept of commerce. E-commerce, a new way to conduct business, is gaining more and more popularity. Despite its rapid growth, there are limitations that hinder the expansion of e-commerce. The primary concern for most people when talking about on-line shopping is security. Due to the open nature of the Internet, personal financial details necessary for on-line shopping can be stolen if sufficient security mechanism is not put in place. How to provide the necessary assurance of security to consumers remains a question mark despite various past efforts. Another concern is the lack of intelligence. The Internet is an ocean of information depository. It is rich in content but lacks the necessary intelligent tools to help one locate the correct piece of information. Intelligent agent, a piece of software that can act on behalf of its owner intelligently, is designed to fill this gap. However, no matter how intelligent an agent is, if it remains on its owner’s machine and does not have any roaming capability, its functionality is limited. With the roaming capability, more security concerns arise. In response to these concerns, SAFE, Secure roaming Agent For E-commerce, is designed to provide secure roaming capability to intelligent agents
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