470 research outputs found

    Three-Dimensional Security Barrier Impact Response Modeling

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    The occurrence of terrorist vehicular bomb attacks has been frequently reported. Perimeter security barriers are designed and guilt to defeat vehicle penetration. Due to the complexity of designing a security barrier, the current practice is to physically crash test the barrier head-on with a threat vehicle, at a certain velocity as a validation of the design. As full-scale vehicular crash tests are costly, facility designers are often forced to use existing barriers without the benefit of designing new, innovative and cost-effective systems for a specific threat. With the present-day computing capability, conducting three-dimensional simulations of vehicular crash dynamics on a personal computer has become very feasible. Vehicular crash simulations are traditionally conducted using finite element (FE) programs, which require extensive computer runtime. A first-principle approach based on the physics of crash dynamics has been developed to reduce computer runtime. Nonlinear structural responses due to the inelastic material effect and large deformation during the vehicular impact are taken into account. An explicit, step-by-step solution scheme is used for solving the transient dynamic problem. No inversions of large matrices are necessary at each time step in this algorithm. Validation examples using crash test data and data from the literature are presented to demonstrate the accuracy and efficiency of the developed algorithm

    Steganography and steganalysis for digital image enhanced Forensic analysis and recommendations

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    Image steganography and steganalysis, which involve concealing and uncovering hidden data within images, have gained significant attention in recent years, finding applications in various fields like military, medicine, e-government, and social media. Despite their importance in real-world applications, some practical aspects remain unaddressed. To bridge this gap, the current study compares image steganography and steganalysis tools and techniques for Digital Forensic Investigators (DFIs) to uncover concealed information in images. We perform a thorough review of Artificial Intelligence, statistical, and signature steganalysis methods, assesses both free and paid versions, and experiments with various image features like size, colour, mean square error (MSE), root mean square error (RMSE), and peak signal-to-noise ratio (PSNR) using a JPEG/PNG dataset. The research provides valuable insights for professionals in cybersecurity. The originality of this research resides in the fact that, although previous studies have been conducted in this area, none have explicitly examined the analysis of the selected tools—F5, Steghide, Outguess for image steganography, and Aletheia, StegExpose for image steganalysis—and their application to JPEG image analysis

    ZZ polarization at an e+e−e^+e^- collider and properties of decay-lepton angular asymmetries

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    ZZ production at an e+e−e^+e^- collider, associated with production of other particles, can be an accurate source of information of details of electroweak interactions, including possible interactions beyond the standard model. We discuss from a general physical point of view the properties of the density matrix as well as lepton angular asymmetries. While most considerations will be applicable to processes of ZZ production associated with any other particle or particles, for some discussions, we specialize to a HZHZ final state. While many of the results can be found in earlier literature, especially for the process e+e−→HZe^+e^- \to HZ, we give details of the reasoning, which are not always found. We discuss the properties of the spin density matrix under C, P and T transformations, and combinations thereof, as also the predictions of these for the corresponding leptonic asymmetries. The specific transformations P, CP, T and CPT are of special importance and we discuss the consequences of these symmetries or their absence for the leptonic asymmetries. A specific issue which has been given attention to is the role of beam polarization, and how one can infer on general grounds which asymmetries get enhanced by the use of beam polarization. Similarly, we also discuss which asymmetries would be sensitive to the measurement of tau polarization in ZZ decay in to τ+τ−\tau^+\tau^-.Comment: 29 page

    Fokker-Planck Kinetic description of small-scale fluid turbulence for classical incompressible fluids

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    Extending the statistical approach proposed in a parallel paper \cite% {Tessarotto2008-aa}, purpose of this work is to propose a stochastic inverse kinetic theory for small-scale hydrodynamic turbulence based on the introduction of a suitable \textit{local phase-space probability density function} (pdf). In particular, we pose the problem of the construction of Fokker-Planck kinetic models of hydrodynamic turbulence. The approach here adopted is based on the so-called IKT approach (inverse kinetic theory), developed by Ellero et al. (2004-2008) which permits an exact phase-space description of incompressible fluids based on the adoption of a local pdf. We intend to show that for prescribed models of stochasticity the present approach permits to determine uniquely the time evolution of the stochastic fluid fields. The stochastic-averaged local pdf is shown to obey a kinetic equation which, although generally non-Markovian, locally in velocity-space can be approximated by means of a suitable Fokker-planck kinetic equation. As a side result, the same pdf is proven to have generally a non-Gaussian behavior.Comment: Contributed paper at RGD26 (Kyoto, Japan, July 2008

    Seroprevalence of canine dirofilariosis, granulocytic anaplasmosis and lyme borreliosis of public health importance in dogs from India’s North East

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    Aim: Vector-borne infections namely dirofilariosis, ehrlichiosis, anaplasmosis and lyme borreliosis are being recognized as emerging and/or re-emerging problems in dogs and man due to rapid extension of zoogeographical ranges of many causative agents through international tourism and increase mobility of dogs at national and international level towards meeting the demand for companion animals in the present day society. Anticipating such situation, a serological study was conducted in dogs from North East India to estimate the prevalence of zoonotically important Dirofilaria immitis, Anaplasma phagocytophilum and Borrelia burgdorferi along with Ehrlichia canis. Materials and Methods: Serological study was carried out using enzyme immunoassay in commercial SNAP 4DX® test kit (Idexx Laboratories, USA). The study was conducted in 191 dogs comprising 82 pets, 57 stray and 52 working dogs owned by defence organizations. Results: The study revealed seroprevalence of mosquito-borne D. immitis (17.80%), tick-borne E. canis (22.51%) and A. phagocytophilum (4.71%) with an overall 41.88% prevalence of pathogens in single or co-infection. Serological evidence of tick-borne lyme borreliosis due to B. burgdorferi could not be established in dogs in the present study. Of the zoonotic species, highest prevalence of D. immitis was found in the stray dogs (22.80%) and that of A. phagocytophilum in pet dogs (6.09%). Conclusion: The results of the present serological study serve as baseline information on the prevalence of A. phagocytophilum in dogs reported for the first time in India and reaffirmation on the high prevalence of D. immitis and E. canis in the North East India

    Non-linear charge reduction effect in strongly-coupled plasmas

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    The charge reduction effect, produced by the nonlinear Debye screening of high-Z charges occuring in strongly-coupled plasmas, is investigated. An analytic asymptotic expression is obtained for the charge reduction factor which determines the Debye-Hueckel potential generated by a charged test particle. Its relevant parametric dependencies are analyzed and shown to predict a strong charge reduction effect in strongly-coupled plasmas.Comment: 4 figure
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