53 research outputs found

    Detecting Cloud-Based Phishing Attacks by Combining Deep Learning Models

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    Web-based phishing attacks nowadays exploit popular cloud web hosting services and apps such as Google Sites and Typeform for hosting their attacks. Since these attacks originate from reputable domains and IP addresses of the cloud services, traditional phishing detection methods such as IP reputation monitoring and blacklisting are not very effective. Here we investigate the effectiveness of deep learning models in detecting this class of cloud-based phishing attacks. Specifically, we evaluate deep learning models for three phishing detection methods--LSTM model for URL analysis, YOLOv2 model for logo analysis, and triplet network model for visual similarity analysis. We train the models using well-known datasets and test their performance on phishing attacks in the wild. Our results qualitatively explain why the models succeed or fail. Furthermore, our results highlight how combining results from the individual models can improve the effectiveness of detecting cloud-based phishing attacks

    Oxidative Stress in the Poultry Gut: Potential Challenges and Interventions

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    The gastrointestinal tract (GIT) provides the biological environment for nutrient digestion and absorption, and protection from pathogens and toxins. Broilers are fast growing because of the great potential of intestinal epithelia for nutrient absorption, and efficient conversion of nutrient to muscle. Physiologically, reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated by GIT epithelial cells either from oxygen metabolism or by enteric commensal bacteria and regulate gut health. However, increased production of ROS elevates free radical production and antioxidant insults resulting in oxidative stress. Oxidative stress in poultry GIT is derived from nutritional, environmental heat stress, and pathological factors, which alters overall performance as well as meat and egg quality. Supplementation of exogenous vitamins, antioxidants, and plant extract having antioxidant properties scavenge ROS and are beneficial in mitigating oxidative stress in the GIT. This review highlights the involvement of oxidative stress in the gastrointestinal functionality of poultry and potential intervention strategies to maintain redox balance in the GIT

    Numerical simulation of mixing in viscous-fingering displacements

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    Thesis (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 97-100).Mixing of two fluids in viscously unstable displacements is far from being fully understood. It is not known how mixing efficiency depends on the viscosity contrast between the fluids, especially for advection-dominated flows (Peclet number Pe > 103). It is well known that when a less viscous fluid displaces a more viscous fluid, the displacement front is unstable and leads to the formation of a pattern known as viscous fingering. However, current simulation technology is unable to cope with large viscosity contrasts (M > 30). We develop a high-resolution simulation approach that is stable for arbitrary viscosity ratios, and we study mixing under different canonical configurations with viscosity contrasts up to M = 400. We explain the observed evolution in degree of mixing through numerical simulation and dimensional analysis. We compute degree of mixing from decay in concentration variance and relate it to the stretching of material interface between the fluids due to fingering. Our analysis predicts the optimum range of viscosity contrast and Peclet number that maximize fluid-fluid interfacial area by balancing the number of fingers with their length before diffusive mixing across the sharp interface takes over. Interesting fingering patterns such as channeling and tip-splitting play an important role in this balancing act which makes degree of mixing a non-monotonic function of viscosity contrast and Peclet number.by Birendra Jha.S.M.in Transportatio

    Effect of lyophilization on infectivity and viral load of Adenovirus

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    Freeze drying (Lyophilization) performed at temperature and pressure below the triple point is being practiced for the preservation of virus stocks for longer periods. The present study is aimed to lyophilize adenovirus strain to study its effects on infectivity and viral load. In-house adenovirus reference strain (stock virus) was propagated in Hep-2 cell line in 25cm2 cell culture flasks. In 24-well plates the serial dilutions of stock virus from 10-1 to 10-7 (100μl inoculum) was inoculated in each well with Hep-2 cells for TCID50 titer and viral DNA was extracted separately to determine viral load by Taqman Real Time PCR. Stock virus was lyophilized in 3 lots and stored at RT (25±2°C) and 4°C separately for 1, 4 and 6 months and subjected to TCID50 (for viral infectivity) and viral load assay (for total viral genome copies). Following lyophilisation and storage of adenoviral strains at RT and 4°C separately did not affect significantly on the viral stability, infectivity as well as viral copy number till 4 months. However, storage at RT for 6 months resulted in 1 log reduction in viral copy number. Thus, storage of even lyophilized virus stock would necessitate a temperature of at least 4°C for prolonged periods. The present study could successfully lyophilize adenovirus and retain its infectivity over a period of 6 months when stored at RT and 4°C. No significant difference in the infectivity or TCID50 titer was observed in the lyophilized virus as compared to the stock virus. However, the viral load was observed to increase with lyophilization of the virus over 6 months when stored at 4°C which possibly is due to the concentration of the virus on freeze-drying.Nepal Journal of Biotechnology. Dec. 2015 Vol. 3, No. 1: 15-2

    Reservoir characterization in an underground gas storage field using joint inversion of flow and geodetic data

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    Characterization of reservoir properties like porosity and permeability in reservoir models typically relies on history matching of production data, well pressure data, and possibly other fluid-dynamical data. Calibrated (history-matched) reservoir models are then used for forecasting production and designing effective strategies for improved oil and gas recovery. Here, we perform assimilation of both flow and deformation data for joint inversion of reservoir properties. Given the coupled nature of subsurface flow and deformation processes, joint inversion requires efficient simulation tools of coupled reservoir flow and mechanical deformation. We apply our coupled simulation tool to a real underground gas storage field in Italy. We simulate the initial gas production period and several decades of seasonal natural gas storage and production. We perform a probabilistic estimation of rock properties by joint inversion of ground deformation data from geodetic measurements and fluid flow data from wells. Using an efficient implementation of the ensemble smoother as the estimator and our coupled multiphase flow and geomechanics simulator as the forward model, we show that incorporating deformation data leads to a significant reduction of uncertainty in the prior distributions of rock properties such as porosity, permeability, and pore compressibility.Eni S.p.A. (Firm

    SOME CONTRIBUTIONS TO CYCLOTOMIC DIFFERENCE SETS AND ABELIAN DIFFERENCE SETS

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    The modern theory of sets has been originated by the German Mathematician George Cantor. He published so many papers showing various properties of abstract sets. George Cantor’s work was well received by a famous Mathematician Richard Dedekind and another German Mathematician Gottlob Frege presented the set theory as principles of logic. It was the famous English philosopher Bertrand Russel showed in with the intention of the continuation of a set of all sets lead to a inconsistency and is known as Russell’s paradox. Later on many paradoxes were introduced by several mathematicians as well as logicians. several existence and non-existence results on abelian difference sets were, found in research papers of Arasu, Pott , Jungnicked and Schuildt, and Davis and Jedwab. Difference sets play a extremely significant function in combinational design theory and in communicational engineering. Hall Introduction of the useful concept of multipliers and can be used to investigate the existence question. Also difference sets in subjective cluster were formally introduced by Bruck and a new types of sets were developed known as cyclotomic difference sets, twin prime power difference sets and also spence difference sets

    Some Contributions to Cyclotomic Difference Sets and Abelian Difference Sets

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    The modern theory of sets has been originated by the German Mathematician George Cantor. He published so many papers showing various properties of abstract sets. George Cantor's work was well received by a famous Mathematician Richard Dedekind and another German Mathematician Gottlob Frege presented the set theory as principles of logic. It was the famous English philosopher Bertrand Russel showed in with the intention of the continuation of a set of all sets lead to a inconsistency and is known as Russell's paradox. Later on many paradoxes were introduced by several mathematicians as well as logicians. several existence and non-existence results on abelian difference sets were, found in research papers of Arasu, Pott , Jungnicked and Schuildt, and Davis and Jedwab. Difference sets play a extremely significant function in combinational design theory and in communicational engineering. Hall Introduction of the useful concept of multipliers and can be used to investigate the existence question. Also difference sets in subjective cluster were formally introduced by Bruck and a new types of sets were developed known as cyclotomic difference sets, twin prime power difference sets and also spence difference sets

    Geomechanical characterization of gondwana shale across nano-micro-meso scales

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    We study multiphase and multiscale mechanical properties of the Gondwana shale samples obtained from the Raniganj Formation of central and eastern India. The mechanical properties of black and gray shale samples cored perpendicular to the bedding plane direction are analyzed across nano-to-micro scales using the nanoindentation method. We characterize the multiphase structure of the two shales in terms of three mechanical phases–quartz/feldspar/pyrite, organic matter, and kaolinite–and use that to explain the heterogeneous elastoplastic behavior observed during nanoindentation. We quantify the fracture toughness of black and gray shales at microscale using our modified energy method, which relates the energy released during a pop-in event to a radial fracture model. We extend the deconvolution approach over multiple properties to estimate the uncertainty in multiphase structure and phase volume fractions. We used the viscosity-toughness scaling analysis to study the difference in hydraulic fracturing behavior of the black and gray shales. We show the influence of nano- and micro-scale multiphase mineralogical properties on characteristic length, time and pressure scales of fracture propagation at mesoscale

    Coupled multiphase flow and poromechanics: A computational model of pore pressure effects on fault slip and earthquake triggering

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    The coupling between subsurface flow and geomechanical deformation is critical in the assessment of the environmental impacts of groundwater use, underground liquid waste disposal, geologic storage of carbon dioxide, and exploitation of shale gas reserves. In particular, seismicity induced by fluid injection and withdrawal has emerged as a central element of the scientific discussion around subsurface technologies that tap into water and energy resources. Here we present a new computational approach to model coupled multiphase flow and geomechanics of faulted reservoirs. We represent faults as surfaces embedded in a three-dimensional medium by using zero-thickness interface elements to accurately model fault slip under dynamically evolving fluid pressure and fault strength. We incorporate the effect of fluid pressures from multiphase flow in the mechanical stability of faults and employ a rigorous formulation of nonlinear multiphase geomechanics that is capable of handling strong capillary effects. We develop a numerical simulation tool by coupling a multiphase flow simulator with a mechanics simulator, using the unconditionally stable fixed-stress scheme for the sequential solution of two-way coupling between flow and geomechanics. We validate our modeling approach using several synthetic, but realistic, test cases that illustrate the onset and evolution of earthquakes from fluid injection and withdrawal.Eni S.p.A. (Firm) (Multiscale Reservoir Science Project

    Coupled Modeling of Multiphase Flow and Fault Poromechanics During Geologic CO[subscript 2] Storage

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    Coupling between fluid flow and mechanical deformation in porous media plays a critical role in geologic storage of CO[subscript 2] One of the key issues in simulation of CO[subscript 2] sequestration is the ability to describe the mechanical and hydraulic behavior of faults, and the influence of the stress tensor and change in pressure on fault slip. Here, we present a new computational approach to model coupled multiphase flow and geomechanics of faulted reservoirs. We represent faults as surfaces embedded in a three-dimensional medium by using zero-thickness interface elements to accurately model fault slip under dynamically evolving fluid pressure and fault strength. We incorporate the effect of fluid pressures from multiphase flow in the mechanical stability of faults by defining a fault pressure. We employ a rigorous formulation of nonlinear multiphase geomechanics based on the increment in mass of fluid phases, instead of the change in porosity. Our nonlinear formulation is required to properly model systems with high compressibility or strong capillarity, as can be the case for geologic CO[subscript 2] sequestration. To account for the effect of surface stresses along fluid-fluid interfaces, we use the equivalent pore pressure in the definition of multiphase effective stress. We develop a numerical simulation tool by coupling a multiphase flow simulator with a mechanics simulator, using the unconditionally stable fixed-stress scheme for a computationally efficient sequential solution of two-way coupling between flow and geomechanics. We validate our modeling approach using several synthetic test cases that illustrate the onset and evolution of earthquakes from fluid injection
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