6,464 research outputs found

    A framework for proving the correctness of cryptographic protocol properties by linear temporal logic

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    In this paper, a framework for cryptographic protocol analysis using linear temporal logic is proposed. The framework can be used to specify and analyse security protocols. It aims to investigate and analyse the security protocols properties that are secure or have any flaws. The framework extends the linear temporal logic by including the knowledge of participants in each status that may change over the time. It includes two main parts, the Language of Temporal Logic (LTL) and the domain knowledge. The ability of the framework is demonstrated by analysing the Needham-Schroeder public key protocol and the Andrew Secure RPC protocol as examples

    Towards green energy for smart cities: particle swarm optimization based MPPT approach

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    This paper proposes an improved one-power-point (OPP) maximum power point tracking (MPPT) algorithm for wind energy conversion system (WECS) to overcome the problems of the conventional OPP MPPT algorithm, namely, the difficulty in getting a precise value of the optimum coefficient, requiring pre-knowledge of system parameters, and non-uniqueness of the optimum curve. The solution is based on combining the particle swarm optimization (PSO) and optimum-relation-based (ORB) MPPT algorithms. The PSO MPPT algorithm is used to search for the optimum coefficient. Once the optimum coefficient is obtained, the proposed algorithm switches to the ORB MPPT mode of operation. The proposed algorithm neither requires knowledge of system parameters nor mechanical sensors. In addition, it improves the efficiency of the WECS. The proposed algorithm is studied for two different wind speed profiles, and its tracking performance is compared with conventional optimum torque control (OTC) and conventional ORB MPPT algorithms under identical conditions. The improved performance of the algorithm in terms of tracking efficiency is validated through simulation using MATLAB/Simulink. The simulation results confirm that the proposed algorithm has a better performance in terms of tracking efficiency and energy extracted. The tracking efficiency of the PSO-ORB MPPT algorithm could reach up to 99.4% with 1.9% more harvested electrical energy than the conventional OTC and ORB MPPT algorithms. Experiments have been carried out to demonstrate the validity of the proposed MPPT algorithm. The experimental results compare well with system simulation results, and the proposed algorithm performs well, as expected

    Local majority dynamics on preferential attachment graphs

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    Suppose in a graph GG vertices can be either red or blue. Let kk be odd. At each time step, each vertex vv in GG polls kk random neighbours and takes the majority colour. If it doesn't have kk neighbours, it simply polls all of them, or all less one if the degree of vv is even. We study this protocol on the preferential attachment model of Albert and Barab\'asi, which gives rise to a degree distribution that has roughly power-law P(x)1x3P(x) \sim \frac{1}{x^{3}}, as well as generalisations which give exponents larger than 33. The setting is as follows: Initially each vertex of GG is red independently with probability α<12\alpha < \frac{1}{2}, and is otherwise blue. We show that if α\alpha is sufficiently biased away from 12\frac{1}{2}, then with high probability, consensus is reached on the initial global majority within O(logdlogdt)O(\log_d \log_d t) steps. Here tt is the number of vertices and d5d \geq 5 is the minimum of kk and mm (or m1m-1 if mm is even), mm being the number of edges each new vertex adds in the preferential attachment generative process. Additionally, our analysis reduces the required bias of α\alpha for graphs of a given degree sequence studied by the first author (which includes, e.g., random regular graphs)

    Kesiapan Guru Terhadap Penerapan Kurikulum 2013 Pada Mata Pelajaran PAI (Bahasa Arab) Di SMK PPMI Assalaam Surakarta Kelas XI Tahun Pelajaran 2014/2015

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    Perubahan dan pembaharuan kurikulum harus difahami sebagai hal yang lazim, karena kurikulum memang harus selalu beradaptasi dengan zaman dan kebutuhan, dan kurikulum 2013 memang disusun untuk mengantisipasi perkembangan zaman tersebut. Lalu yang menjadi masalah sekarang adalah bagaimanakah kesiapan guru dalam menerapkan kurikulum 2013 itu untuk tahun ini. Apabila guru memiliki kesiapan yang memadai, siap dalam segi kualifikasi dan kompetensi serta siap dalam hal kesamaan pemahaman paradigma yang dijabarkan dalam kurikulum 2013 maka tidak akan bermasalah. Penulis tertarik meneliti tentang: kesiapan guru terhadap penerapan kurikulum 2013 pada mata pelajaran PAI (bahasa Arab). Dalam penelitian ini masalah yang penulis bahas adalah kesiapan guru terhadap penerapan kurikulum 2013 pada mata pelajaran PAI (bahasa Arab) di SMK PPMI Assalaam Surakarta. Serta apa yang menjadi faktor pendukung dan penghambat dalam penerapan Kurikulum 2013 pada mata pelajaran PAI (bahasa Arab) di SMK PPMI Assalaam Surakarta. Tujuan penelitan ini adalah untuk mendeskripsikan kesiapan guru terhadap penerapan kurikulum 2013 pada mata pelajaran PAI (bahasa Arab). Serta mendeskripsikan apa yang menjadi faktor pendukung dan penghambat dalam penerapan kurikulum 2013 pada mata pelajaran PAI (bahasa Arab) di SMK PPMI Assalaam Surakarta kelas XI tahun pelajaran 2014/2015. Manfaat penelitian diharapkan dapat menambah wawasan dan pengetahuan dalam meningkatkan kesiapan guru dalam menerapkan kurikulum 2013. Penelitian ini merupakan penelitian kualitatif yang mengambil objek di SMK PPMI Assalaam Surakarta dengan subjek guru PAI dan siswa kelas XI. Metode pengumpulan data yang digunakan adalah dokumentasi, observasi, dan wawancara. Sedangkan metode analisis data yang digunakan adalah teknik analisis deskriptif kualitatif dengan cara deduktif yaitu pengumpulan data, penyajian data, dan penarikan kesimpulan. Berdasarkan hasil penelitian dan analisis data, maka dapat disimpulkan bahwa: Guru belum sepenuhnya siap dalam menerapkan kurikulum 2013 dalam mata pelajaran PAI (bahasa Arab). Hal ini dapat dilihat dari ketidak sesuian rumusan kurikulum 2013 dan penerapan mata pelajaran bahasa Arab di SMK PPMI Assalaaam, yaitu: SKL belum dirumuskan sesuai dengan kurikulum 2013, standar isi belum diadaptasi dengan kurikulum pemerintah. Dalam standar proses KI 1, KI 2, KI 3, dan KI 4 belum diterapkan dalam KBM. Dan standar penilaian pada sikap sesama teman dan portofolio belum dilakukan. Faktor pendukung: Siswa diajak aktif mengkonstruk pemahamannya dalam mengikuti setiap pembelajaran. Pembelajaran tidak hanya dilakukan di ruang kelas. Siswa dibebaskan memanfaatkan media pembelajaran seperti laptop. Faktor penghambatnya: Buku PAI disusun menggunakan bahasa Arab sehingga kurang efektif jika diajarkan dengan menerapkan kurikulum 2013. Metode yang kurang variatif sehingga menimbulkan kebosanan pada siswa

    Spin-crossover, mesomorphic and thermoelectrical properties of cobalt(II) complexes with alkylated N3-Schiff bases

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    Three new cobalt(ii) complexes, [Co(L12)2](BF4)2 (1), [Co(L14)2](BF4)2·H2O (2) and [Co(L16)2](BF4)2·H2O (3), where L12-16 are N3-Schiff bases appended with linear C12-16 carbon chains at the nitrogen atoms, were obtained in good yields by facile one-pot reactions. The single crystal X-ray structure of complex 1 shows a tetragonally compressed CoN6 coordination geometry. The melting temperatures of 1-3 were lower than 373 K, while their decomposition temperatures were above 473 K. All complexes have high-spin Co(ii) centres at 300 K and exhibit a columnar mesophase above 383 K. Complexes 1 and 3 showed normal thermal spin-crossover behaviour with weak hysteresis loops at about 320 K. Hence, these complexes showed uncoupled phase transitions (class iiia). The values for the Seebeck coefficient (Se) of the cobalt redox couples formed from 1 and 2 were 1.89 ± 0.02 mV K-1 and 1.92 ± 0.08 mV K-1, respectively, identifying them as potential thermoelectrochemical materials

    CP violation in a multi-Higgs doublet model with flavor changing neutral current

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    We study CP violation in a multi-Higgs doublet model based on a S3×Z3S_3 \times Z_3 horizontal symmetry where CKM phase is not the principal source of CP violation. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalar-pseudoscalar Higgs boson mixings. Both mechanisms can explain the observed CP violation in the neutral Kaon system. ϵ/ϵ\epsilon'/\epsilon due to neutral Higgs boson exchange is small in both mechanisms, but charged Higgs boson con- tributions can be as large as 10310^{-3} for a), and 10410^{-4} for b). CP violation in the neutral B system is, however, quite different from the Minimal Standard Model. The neutron Electric Dipole Moment can be as large as the present ex- perimental bound, and can be used to constrain charged Higgs boson masses. The electron EDM is one order of magnitude below the experimental bound in case b) and smaller in case a).Comment: 22 pages, Revtex, OITS-52

    CP Violation in a Multi-Higgs Doublet Model

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    We study CP violation in a multi-Higgs doublet model based on a S3×Z3S_3 \times Z_3 horizontal symmetry. We consider two mechanisms for CP violation in this model: a) CP violation due to complex Yukawa couplings; and b) CP violation due to scalar-pseudoscalar mixings. We find that the predictions for ϵ/ϵ\epsilon'/\epsilon, CP violation in B decays and the electric dipole moments of neutron and electron are different between these two mechanisms. These predictions are also dramatically different from the minimal Standard Model predictions.Comment: 17 pages + one figure, Revtex. Talk presented by Deshpande at the Conference WHEPP-3, December 199

    Secondhand smoke exposure assessment and counseling in the Chinese pediatric setting: a qualitative study

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    Background: Assisting smoking parents to quit smoking and eliminating the secondhand smoke (SHS) exposure of their children is a global health priority. Engaging healthcare workers in developing countries to address this priority has been a challenge. This study intends to explore issues around current practice related to SHS exposure assessment and counseling and identify barriers to SHS exposure reduction counseling in the Chinese pediatric setting. Methods: We conducted qualitative interviews (11 focus groups discussions (FGDs) with pediatricians, 6 FGDs with pediatric nurses and 11 in-depth interviews (IDIs) with hospital administrators) among 101 health-care professionals (HCP) from 5 hospitals in four major cities of Guangxi Province, China. All FGDs/ IDIs were audio recorded and analysed thematically. Results: The findings suggest that few Chinese pediatricians routinely address the SHS exposure of children in their usual practice. All HCPs felt the need for clinical interventions to promote SHS exposure reduction for children. Primary barriers to SHS exposure reduction counseling in the Chinese pediatric setting included: lack of skills and training in tobacco use reduction and cessation counseling; time constraints and heavy workloads, uncertainty about the usefulness of smoking cessation interventions and lack of hospital-wide systems requiring pediatricians to record tobacco use or SHS exposure information. Ideas for overcoming these barriers were building capacity of pediatricians, collaboration with international organization to initiate training, engaging top level leaders in the effort and ensuring financial resources to support the program. Conclusions: This study among hospital administrators and service providers in China demonstrated a high level of interest in delivering SHS exposure reduction interventions in the pediatric setting. The findings can inform the creation and delivery of clinical interventions in China to promote SHS exposure reduction to children in the pediatric setting. Electronic supplementary material The online version of this article (doi:10.1186/1471-2431-14-266) contains supplementary material, which is available to authorized users

    On Convergence and Threshold Properties of Discrete Lotka-Volterra Population Protocols

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    In this work we focus on a natural class of population protocols whose dynamics are modelled by the discrete version of Lotka-Volterra equations. In such protocols, when an agent aa of type (species) ii interacts with an agent bb of type (species) jj with aa as the initiator, then bb's type becomes ii with probability P_ijP\_{ij}. In such an interaction, we think of aa as the predator, bb as the prey, and the type of the prey is either converted to that of the predator or stays as is. Such protocols capture the dynamics of some opinion spreading models and generalize the well-known Rock-Paper-Scissors discrete dynamics. We consider the pairwise interactions among agents that are scheduled uniformly at random. We start by considering the convergence time and show that any Lotka-Volterra-type protocol on an nn-agent population converges to some absorbing state in time polynomial in nn, w.h.p., when any pair of agents is allowed to interact. By contrast, when the interaction graph is a star, even the Rock-Paper-Scissors protocol requires exponential time to converge. We then study threshold effects exhibited by Lotka-Volterra-type protocols with 3 and more species under interactions between any pair of agents. We start by presenting a simple 4-type protocol in which the probability difference of reaching the two possible absorbing states is strongly amplified by the ratio of the initial populations of the two other types, which are transient, but "control" convergence. We then prove that the Rock-Paper-Scissors protocol reaches each of its three possible absorbing states with almost equal probability, starting from any configuration satisfying some sub-linear lower bound on the initial size of each species. That is, Rock-Paper-Scissors is a realization of a "coin-flip consensus" in a distributed system. Some of our techniques may be of independent value
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