Sources of Polycyclic Aromatic Hydrocarbons in Street Dust from the Chang-Zhu-Tan Region, Hunan, China

Street dusts collected from 20 sites as well as three special dust samples collected from chimney of coal-fired plant, smelter and refinery of nonferrous metals and automobile exhaust, respectively, in the Chang-Zhu-Tan (Changsha, Zhuzhou and Xiangtan) urban region, Hunan, China, in May to August 2009, were investigated for sources of polycylic aromatic hydrocarbons (PAHs). The ΣPAHs16 levels were in the range of 3515 - 24488 ng/g, with a mean of 8760 ng/g. The sources of PAH inputs to street dusts were determined by isomer ratios, principal components analysis and REE geochemical analysis. The isomer ratios suggested a rather uniform mixture of coal combustion and petroleum PAH sources. Factor analysis indicated that the main sources of 16 PAHs were coal combustion/vehicle exhaust and coking/ petroleum. Rare earth elements (REE) and Factor score analysis further indicated the possible dust sources were from background soil, coal or coking combustion, nonferrous metal factories, traffic exhaust.

tsrCert:Traceable Self-Randomization Certificate and Its Application to Blockchain Supervision

Traditional public key infrastructure(PKI)only provides authentication for network communication,and the standard X.509 certificate used in this architecture reveals the user’s identity.This lack of privacy protection no longer satisfies the increasing demands for personal privacy.Though an optimized anonymous PKI certificate realizes anonymity,it has the potential to be abused due to the lack of identity tracking.Therefore,maintaining a balance between user anonymity and traceability has become an increasing requirement for current PKI.This paper introduces a novel traceable self-randomization certificate authentication scheme based on PKI architecture that achieves both anonymity and traceability.We propose a traceable self-randomization certificate authentication scheme based on the short randomizable signature.Specifically,certificate users can randomize the initial certificate and public key into multiple anonymous certificates and public keys by themselves under the premise of traceability,which possesses lower computational complexity and fewer interactive operations.Users can exhibit different attributes of themselves in different scenarios,randomizing the attributes that do not necessarily need to be displayed.Through security and performance analysis,we demonstrate the suitability of the improved PKI architecture for practical applications.Additionally,we provide an application of the proposed scheme to the permissioned blockchain for supervision.

Reaching consensus for membership dynamic in secret sharing and its application to cross-chain

The communication efficiency optimization,censorship resilience,and generation of shared randomness are inseparable from the threshold cryptography in the existing Byzantine Fault Tolerant(BFT)consensus.The membership in consensus in a blockchain scenario supports dynamic changes,which effectively prevents the corruption of consensus participants.Especially in cross-chain protocols,the dynamic access to different blockchains will inevitably bring about the demand for member dynamic.Most existing threshold cryptography schemes rely on redefined key shares,leading to a static set of secret sharing participants.In this paper,we propose a general approach to coupling blockchain consensus and dynamic secret sharing.The committee performs consensus confirmation of both dynamic secret sharing and transaction proposals.Our scheme facilitates threshold cryptography membership dynamic,thus underlying support for membership dynamic of threshold cryptographybased BFT consensus schemes.We instantiate a dynamic HotStuff consensus to demonstrate the effectiveness of the scheme.After the correctness and security proof,our scheme achieves the secrecy and integrity of the threshold key shares while ensuring consensus liveness and safety.Experimental results prove that our scheme obtains dynamic membership with negligible overhead.

Lightweight and Manageable Digital Evidence Preservation System on Bitcoin

An effective and secure system used for evidence preservation is essential to possess the properties of anti- loss, anti-forgery, anti-tamper and perfect verifiability. Traditional architecture which relies on centralized cloud storage is depressingly beset by the security problems such as incomplete confidence and unreliable regulation. Moreover, an expensive, inefficient and incompatible design impedes the effort of evidence preservation. In contrast, the decentralized blockchain network is qualified as a perfect replacement for its secure anonymity, irrevocable commitment, and transparent traceability. Combining with subliminal channels in blockchain, we have weaved the transaction network with newly designed evidence audit network. In this paper, we have presented and implemented a lightweight digital evidence-preservation architecture which possesses the features of privacy-anonymity, audit-transparency, function-scalability and operation-lightweight. The anonymity is naturally formed from the cryptographic design, since the cipher evidence under encrypted cryptosystem and hash-based functions leakages nothing to the public. Covert channels are efficiently excavated to optimize the cost, connectivity and security of the framework, transforming the great computation power of Bitcoin network to the value of credit. The transparency used for audit, which relates to the proof of existence, comes from instant timestamps and irreversible hash functions in mature blockchain network. The scalability is represented by the evidence chain interacted with the original blockchain, and the extended chains on top of mainchain will cover the most of auditors in different institutions. And the lightweight, which is equal to low-cost, is derived from our fine-grained hierarchical services. At last, analyses of efficiency, security, and availability have shown the complete accomplishment of our system.

华夏板块发现冥古宙捕掳锆石

由于缺少冥古宙岩石的证据,对地球冥古宙地壳演化模式仍缺乏深入认识.锆石作为火成岩中常见的副矿物,由于其独特的物理化学稳定性,在研究岩石成因以及地壳演化等方面发挥着重要作用.因此,本文对华夏板块汤湖岩体中新发现的冥古宙捕掳锆石开展了一系列U-Pb年代学和Lu-Hf同位素地球化学研究.结果表明,该锆石具有明显的核幔结构,核部年龄为4102±12 Ma且具有较高的Th/U比(0.48)和ε_(Hf)(t)值(0.07),证实了该捕掳锆石属岩浆成因且形成于冥古宙.本文提出了两种假说且均可解释该锆石的成因:(1)其由4200Ma的亏损地幔派生出的岩石在4100 Ma经历再造;和(2)其由原始地幔在4100 Ma派生出.但是不管是哪种模式都指示了地球在冥古宙存在新生地壳的生长事件.

Graph Computing and Its Application in Power Grid Analysis

Approaches to apply graph computing to power grid analysis are systematically explained using real-world application examples.Through exploring the nature of the power grid and the characteristics of power grid analysis,the guidelines for selecting appropriate graph computing techniques for the application to power grid analysis are outlined.A custom graph model for representing the power grid for the analysis and simulation purpose and an in-memory computing(IMC)based graph-centric approach with a shared-everything architecture are introduced.Graph algorithms,including network topology processing and subgraph processing,and graph computing application scenarios,including in-memory computing,contingency analysis,and Common Information Model(CIM)model merge,are presented.

Revocable Hierarchical Identity-Based Broadcast Encryption

Hierarchical Identity-Based Broadcast Encryption （HIBBE） organizes users into a tree-like structure, and it allows users to delegate their decryption ability to subordinates and enable encryption to any subset of users while only intended users can decrypt. However, current HIBBE schemes do not support efficient revocation of private keys. Here, a new primitive called Revocable Hierarchical Identity-Based Broadcast Encryption （RHIBBE） is formalized that allows revocation of the HIBBE. Ciphertext indistinguishability is defined against the selectively Bounded Revocable Identity-Vector-Set and Chosen-Plaintext Attack （IND-sBRIVS-CPA）. An IND-sBRIVS-CPA secure RHIBBE scheme is constructed with efficient revocation on prime-order bilinear groups. The unbounded version of the scheme is also shown to be secure but a little weaker than the former under the decisional n-Weak Bilinear Diffie-Hellman inversion assumption.

Flexible radio-frequency micro electro-mechanical switch towards the applications of satellite communications

This paper presents a flexible radio-frequency microelectromechanical system(RF MEMS)switch integrated on cyclo-olefin polymer(COP)substrate using a modified surface MEMS processing technology,which could be used in the 17-19 GHz frequency band of satellite communication.Through systematic simulation analysis,it is found that flexible RF MEMS switch can achieve certain bending radius by miniaturizing the electronic dimension,without degrading the RF performance.It is demonstrated that the RF characteristics of flexible RF MEMS switch with special anchor structural design,fabricated by modified surface MEMS processing,are not sensitive to bending deformation under the curvature of 0 mm^(-1),0.05 mm^(-1),0.10 mm^(-1).Furthermore,the range of bending curvature which will affect the RF characteristics is given through systematic simulation.The flexible RF MEMS switch with high process compatibility and stable RF performance is believed to be promising candidates for future microwave communications and other consumer electronics.