WorldWideScience

Sample records for angle of attack

  1. Effect of attack angle on flow characteristic of centrifugal fan

    Science.gov (United States)

    Wu, Y.; Dou, H. S.; Wei, Y. K.; Chen, X. P.; Chen, Y. N.; Cao, W. B.

    2016-05-01

    In this paper, numerical simulation is performed for the performance and internal flow of a centrifugal fan with different operating conditions using steady three-dimensional incompressible Navier-Stokes equations coupled with the RNG k-e turbulent model. The performance curves, the contours of static pressure, total pressure, radial velocity, relative streamlines and turbulence intensity at different attack angles are obtained. The distributions of static pressure and velocity on suction surface and pressure surface in the same impeller channel are compared for various attack angles. The research shows that the efficiency of the centrifugal fan is the highest when the attack angle is 8 degree. The main reason is that the vortex flow in the impeller is reduced, and the jet-wake pattern is weakened at the impeller outlet. The pressure difference between pressure side and suction side is smooth and the amplitude of the total pressure fluctuation is low along the circumferential direction. These phenomena may cause the loss reduced for the attack angle of about 8 degree.

  2. Non-linear Flight Dynamics at High Angles of Attack

    DEFF Research Database (Denmark)

    Granasy, P.; Sørensen, C.B.; Mosekilde, Erik;

    1998-01-01

    The methods of nonlinear dynamics are applied to the longitudinal motion of a vectored thrust aircraft, in particular the behavior at high angles of attack. Our model contains analytic nonlinear aerodynamical coefficients based on NASA windtunnel experiments on the F-18 high-alpha research vehicl...

  3. High angle of attack aerodynamics subsonic, transonic, and supersonic flows

    CERN Document Server

    Rom, Josef

    1992-01-01

    The aerodynamics of aircraft at high angles of attack is a subject which is being pursued diligently, because the modern agile fighter aircraft and many of the current generation of missiles must perform well at very high incidence, near and beyond stall. However, a comprehensive presentation of the methods and results applicable to the studies of the complex aerodynamics at high angle of attack has not been covered in monographs or textbooks. This book is not the usual textbook in that it goes beyond just presenting the basic theoretical and experimental know-how, since it contains reference material to practical calculation methods and technical and experimental results which can be useful to the practicing aerospace engineers and scientists. It can certainly be used as a text and reference book for graduate courses on subjects related to high angles of attack aerodynamics and for topics related to three-dimensional separation in viscous flow courses. In addition, the book is addressed to the aerodynamicist...

  4. Potential flow past axisymmetric bodies at angle of attack

    Science.gov (United States)

    Kuhlman, J. M.; Shu, J.-Y.

    1984-01-01

    The Karamcheti (1966) suggestion concerning the use of higher order singularity techniques has been developed for the calculation of incompressible flow past an axisymmetric body at angle of attack. Attention is given to the results of a convergence study using this axial singularity method, where solution accuracy has been investigated for ellipsoids of slenderness ratio in the 1-10 range for both axial and inclined flow. Effects of singularity type, element number and size distribution, and singularity line inset distance, are noted, and a paneling scheme is developed which yields accurate results for the class of axisymmetric bodies having continuous body slopes with discontinuous curvature jumps.

  5. Determination of the angle of attack on rotor blades

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Hansen, Martin Otto Laver; Sørensen, Jens Nørkær

    2009-01-01

    Two simple methods for determining the angle of attack (AOA) on a section of a rotor blade are proposed. Both techniques consist of employing the Biot-Savart integral to determine the influence of the bound vorticity on the velocity field. In the first technique, the force distribution along...... the blade and the velocity at a monitor point in the vicinity of the blade are assumed to be known from experiments or CFD computations. The AOA is determined by subtracting the velocity induced by the bound circulation, determined from the loading, from the velocity at the monitor point. In the second...... to be located closer to the blade, and thus to determine the AOA with higher accuracy. Data from CFD computations for flows past the Tellus 95 kW wind turbine at different wind speeds are used to test both techniques. Comparisons show that the proposed methods are in good agreement with existing techniques...

  6. Effect of attack angle change on hydrodynamic character of supercavitating bodies

    Institute of Scientific and Technical Information of China (English)

    JIANG Zeng-hui; YU Kai-ping; WANG Cong; ZHANG Jia-zhong; HUANG Wen-hu

    2009-01-01

    A series of experiments has been done in a moderate-velocity cavitation tunnel to investigate the effects of attack angle change on hydrodynamic characters of supercavitation. Hydrodynamic characters of the aft section at various attack angles were compared. The investigation shows that hydrodynamic forces of the aft section are dependent of supercavity shapes at different attack angles, and the magnitude of hydrodynamic forces of the aft section varies with the change of attack angle. When the aft section is in the fully wetted case, the drag coefficient changes little. Lift and moment coefficients both increase with the increased attack angle, and the increase magnitude is not large. When the aft body planing is on the cavity boundary, the drag coefficient of nonzero attack angle is larger than that of zero attack angle, and the maximal lift and moment coefficients both vary obviously with the increased attack angle. In the case that the body is fully enveloped by cavity, the drag coefficient, lift coefficient and moment coefficient are nearly constant with the change of attack angles.

  7. Aerodynamic characteristics of general aviation at high angle of attack with the propeller slipstream

    Science.gov (United States)

    Matsuo, N.; Hirano, S.

    1986-01-01

    The aerodynamic characteristics of the FA-300 business aircraft at high angle of attack with the propeller stream are described. The FA-300 offers two types, FA-300-700 for 340 HP, and -710 for 450 Hp of the engine. The effects of the propeller slipstream on the high angle of the attack are discussed.

  8. Footprint Problem with Angle of Attack Optimization for High Lifting Reentry Vehicle

    Institute of Scientific and Technical Information of China (English)

    LI Huifeng; ZHANG Ran; LI Zhaoying; ZHANG Rui

    2012-01-01

    A formal analysis to footprint problem with effects of angle of attack (AOA) is presented.First a flexible and rapid standardized method for footprint generation is developed.Zero bank angle control strategy and the maximum crossrange method are used to obtain virtual target set; afterward,closed-loop bank angle guidance law is used to find footprint by solving closest approach problem for each element in virtual target set.Then based on quasi-equilibrium glide condition,the typical inequality reentry trajectory constraints are converted to angle of attack lower boundary constraint.Constrained by the lower boundary,an original and practical angle of attack parametric method is proposed.By using parametric angle of attack profile,optimization algorithm for angle of attack is designed and the impact of angle of attack to footprint is discussed.Simulations with different angle of attack profiles are presented to demonstrate the performance of the proposed footprint solution method and validity of optimal algorithm.

  9. EFFECT OF SWEEP ANGLE ON THE VORTICAL FLOW OVER DELTA WINGS AT AN ANGLE OF ATTACK OF 10°

    Directory of Open Access Journals (Sweden)

    JAMES BRETT

    2014-12-01

    Full Text Available CFD simulations have been used to analyse the vortical flows over sharp edged delta wings with differing sweep angles under subsonic conditions at an angle of attack of 10°. RANS simulations were validated against experimental data for a 65° sweep wing, with a flat cross-section, and the steadiness of the flow field was assessed by comparing the results against unsteady URANS and DES simulations. To assess the effect of sweep angle on the flow field, a range of sweep angles from 65° to 43° were simulated. For moderate sweep wings the primary vortex was observed to detach from the leading edge, undergoing vortex breakdown, and a weaker, replacement, "shadow" vortex was formed. The shadow vortex was observed for sweep angles of 50° and less, and resulted in reduced lift production near the wing tips loss of the stronger primary vortex.

  10. Delayed detached eddy simulations of fighter aircraft at high angle of attack

    Science.gov (United States)

    Xu, Guoliang; Jiang, Xiong; Liu, Gang

    2016-08-01

    The massively separated flows over a realistic aircraft configuration at 40°, 50°, and 60° angles of attack are studied using the delayed detached eddy simulation (DDES). The calculations are carried out at experimental conditions corresponding to a mean aerodynamic chord-based Reynolds number of 8.93× 105 and Mach number of 0.088. The influence of the grid size is investigated using two grids, 20.0× 106 cells and 31.0× 106 cells. At the selected conditions, the lift, drag, and pitching moment from DDES predictions agree with the experimental data better than that from the Reynolds-averaged Navier-Stokes. The effect of angle of attack on the flow structure over the general aircraft is also studied, and it is found that the dominated frequency associated with the vortex shedding process decreases with increasing angle of attack.

  11. Delayed detached eddy simulations of fighter aircraft at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    Guoliang Xu; Xiong Jiang; Gang Liu

    2016-01-01

    The massively separated flows over a realistic air-craft configuration at 40◦, 50◦, and 60◦angles of attack are studied using the delayed detached eddy simulation (DDES). The calculations are carried out at experimental conditions corresponding to a mean aerodynamic chord-based Reynolds number of 8.93 × 105 and Mach number of 0.088. The influ-ence of the grid size is investigated using two grids, 20.0×106 cells and 31.0 × 106 cells. At the selected conditions, the lift, drag, and pitching moment from DDES predictions agree with the experimental data better than that from the Reynolds-averaged Navier–Stokes. The effect of angle of attack on the flow structure over the general aircraft is also studied, and it is found that the dominated frequency associated with the vortex shedding process decreases with increasing angle of attack.

  12. COMPUTATION OF FIELD STRUCTURE AND AERODYNAMIC CHARACTERISTICS OF DELTA WINGS AT HIGH ANGLES OF ATTACK

    Institute of Scientific and Technical Information of China (English)

    YANG Li-zhi; GAO Zheng-hong

    2005-01-01

    A numerical investigation of the structure of the vortical flowfield over delta wings at high angles of attack in longitudinal and with small sideslip angle is presented.Three-dimensional Navier-Stokes numerical simulations were carried out to predict the complex leeward-side flowfield characteristics that are dominated by the effect of the breakdown of the leading-edge vortices. The methods that analyze the flowfield structure quantitatively were given by using flowfield data from the computational results. In the region before the vortex breakdown, the vortex axes are approximated as being straight line. As the angle of attack increases, the vortex axes are closer to the root chord, and farther away from the wing surface. Along the vortex axes, as the adverse pressure gradients occur, the axial velocity decreases, that is, λ is negative, so the vortex is unstable, and it is possible to breakdown. The occurrence of the breakdown results in the instability of lateral motion for a delta wing, and the lateral moment diverges after a small perturbation occurs at high angles of attack. However,after a critical angle of attack is reached, the vortices breakdown completely at the wing apex, and the instability resulting from the vortex breakdown disappears.

  13. Heat transfer characteristics of staggered wing-shaped tubes bundle at different angles of attack

    Science.gov (United States)

    Sayed Ahmed, Sayed Ahmed E.; Ibrahiem, Emad Z.; Mesalhy, Osama M.; Abdelatief, Mohamed A.

    2014-08-01

    An experimental and numerical study has been conducted to clarify heat transfer characteristics and effectiveness of a cross-flow heat exchanger employing staggered wing-shaped tubes at different angels of attack. The water-side Rew and the air-side Rea were at 5 × 102 and at from 1.8 × 103 to 9.7 × 103, respectively. The tubes arrangements were employed with various angles of attack θ1,2,3 from 0° to 330° at the considered Rea range. Correlation of Nu, St, as well as the heat transfer per unit pumping power (ɛ) in terms of Rea and design parameters for the studied bundle were presented. The temperature fields around the staggered wing-shaped tubes bundle were predicted by using commercial CFD FLUENT 6.3.26 software package. Results indicated that the heat transfer increased with the angle of attack in the range from 0° to 45°, while the opposite was true for angles of attack from 135° to 180°. The best thermal performance and hence the efficiency η of studied bundle occurred at the lowest Rea and/or zero angle of attack. Comparisons between the experimental and numerical results of the present study and those, previously, obtained for similar available studies showed good agreements.

  14. NUMERICAL STUDY OF FLOW PAST AN AXISYMMETRIC BODY WITH A RING WING AT VARIOUS ATTACK ANGLES

    Institute of Scientific and Technical Information of China (English)

    Ren An-lu; Zou Jian-feng; Dai Zhi-qian

    2003-01-01

    The laminar and turbulent flows past an axisymmetric body with a ring wing were investigated numerically at various attack angles (0°-20°) for the Reynolds numbers ranging from 103 to 107. The DDM (Domain Decomposition Method) with the Schwarz iterative method based on finite difference approximation was applied to simulate this problem. The primitive variable formulation was used for the solution of the incompressible Navier-Stoke equations. The velocity field was calculated from the unsteady momentum equation by marching in time. The continuity equation was replaced by a Poisson-type equation for the pressure with the Neumann boundary conditions. The Baldwin-Lomax model was adopted to simulate turbulence effect. The leap frog implicit iterative method was used for the time difference approximations. The computed pressure at the front stagnation point is found to have a small deviation, less than 10%, from the theoretical value. The outlet flux has a loss about 5%. The lift coefficients increase linearly with the attack angle, but for attack angles greater than 15° the lift coefficients show mild decrease. The friction drag coefficients are insensitive to the attack angles, but the pressure drag coefficients increase markedly with the attack angles. In addition, complex flow patterns are revealed within the vicinity of the ring wing.

  15. Surface pressure model for simple delta wings at high angles of attack

    Indian Academy of Sciences (India)

    A A Pashilkar

    2001-12-01

    A new aerodynamic modelling approach is proposed for the longitudinal static characteristics of a simple delta wing. It captures the static variation of normal force and pitching moment characteristics throughout the angle of attack range. The pressure model is based on parametrizing the surface pressure distribution on a simple delta wing. The model is then extended to a wing/body combination where body-alone data are also available. The model is shown to be simple and consistent with experimental data. The pressure model can be used as a first approximation for the load estimation on the delta wing at high angles of attack.

  16. Lattice Boltzmann Method used for the aircraft characteristics computation at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Traditional Finite Volume Method(FVM)and Lattice Boltzmann Method(LBM)are both used to compute the high angle attack aerodynamic characteristics of the benchmark aircraft model named CT-1.Even though the software requires flow on the order of Ma<0.4,simulation at Ma=0.5 is run in PowerFLOW after theoretical analysis.The consistency with the wind tunnel testing is satisfied,especially for the LBM which can produce perfect results at high angle attack.PowerFLOW can accurately capture the detail of flows because it is inherently time-dependent and parallel and suits large-scale computation very well.

  17. Bifurcation analysis of polynomial models for longitudinal motion at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    Shi Zhongke; Fan Li

    2013-01-01

    To investigate the longitudinal motion stability of aircraft maneuvers conveniently,a new stability analysis approach is presented in this paper.Based on describing longitudinal aerodynamics at high angle-of-attack (α < 50°) motion by polynomials,a union structure of two-order differential equation is suggested.By means of nonlinear theory and method,analytical and global bifurcation analyses of the polynomial differential systems are provided for the study of the nonlinear phenomena of high angle-of-attack flight.Applying the theories of bifurcations,many kinds of bifurcations,such as equilibrium,Hopf,homoclinic (heteroclinic) orbit and double limit cycle bifurcations are discussed and the existence conditions for these bifurcations as well as formulas for calculating bifurcation curves are derived.The bifurcation curves divide the parameter plane into several regions; moreover,the complete bifurcation diagrams and phase portraits in different regions are obtained.Finally,our conclusions are applied to analyzing the stability and bifurcations of a practical example of a high angle-of-attack flight as well as the effects of elevator deflection on the asymptotic stability regions of equilibrium.The model and analytical methods presented in this paper can be used to study the nonlinear flight dynamic of longitudinal stall at high angle of attack.

  18. Prediction of Unsteady Aerodynamic Coefficients at High Angles of Attack

    Science.gov (United States)

    Pamadi, Bandu N.; Murphy, Patrick C.; Klein, Vladislav; Brandon, Jay M.

    2001-01-01

    The nonlinear indicial response method is used to model the unsteady aerodynamic coefficients in the low speed longitudinal oscillatory wind tunnel test data of the 0.1 scale model of the F-16XL aircraft. Exponential functions are used to approximate the deficiency function in the indicial response. Using one set of oscillatory wind tunnel data and parameter identification method, the unknown parameters in the exponential functions are estimated. The genetic algorithm is used as a least square minimizing algorithm. The assumed model structures and parameter estimates are validated by comparing the predictions with other sets of available oscillatory wind tunnel test data.

  19. Numerical investigation on properties of attack angle for an opposing jet thermal protection system

    Institute of Scientific and Technical Information of China (English)

    Lu Hai-Bo; Liu Wei-Qiang

    2012-01-01

    The three-dimensional Navier Stokes equation and the k- ε viscous model are used to simulate the attack angle characteristics of a hemisphere nose-tip with an opposing jet thermal protection system in supersonic flow conditions.The numerical method is validated by the relevant experiment.The flow field parameters,aerodynamic forces,and surface heat flux distributions for attack angles of 0°,2°,5°,7°,and 10° are obtained.The detailed numerical results show that the cruise attack angle has a great inflnence on the flow field parameters,aerodynamic force,and surface heat flux distribution of the supersonic vehicle nose-tip with an opposing jet thermal protection system.When the attack angle reaches 10°,the heat flux on the windward generatrix is close to the maximal heat flux on the wall surface of the nose-tip without thermal protection system,thus the thermal protection has failed.

  20. Qualitative evaluation of a flush air data system at transonic speeds and high angles of attack

    Science.gov (United States)

    Larson, Terry J.; Whitmore, Stephen A.; Ehernberger, L. J.; Johnson, J. Blair; Siemers, Paul M., III

    1987-01-01

    Flight tests were performed on an F-14 aircraft to evaluate the use of flush pressure orifices on the nose section for obtaining air data at transonic speeds over a large range of flow angles. This program was part of a flight test and wind tunnel program to assess the accuracies of such systems for general use on aircraft. It also provided data to validate algorithms developed for the shuttle entry air data system designed at NASA Langley. Data were obtained for Mach numbers between 0.60 and 1.60, for angles of attack up to 26.0 deg, and for sideslip angles up to 11.0 deg. With careful calibration, a flush air data system with all flush orifices can provide accurate air data information over a large range of flow angles. Several orificies on the nose cap were found to be suitable for determination of stagnation pressure. Other orifices on the nose section aft of the nose cap were shown to be suitable for determination of static pressure. Pairs of orifices on the nose cap provided the most sensitive measurements for determining angles of attack and sideslip, although orifices located farther aft on the nose section could also be used.

  1. Evaluation of electrolytic tilt sensors for measuring model angle of attack in wind tunnel tests

    Science.gov (United States)

    Wong, Douglas T.

    1992-01-01

    The results of a laboratory evaluation of electrolytic tilt sensors as potential candidates for measuring model attitude or angle of attack in wind tunnel tests are presented. The performance of eight electrolytic tilt sensors was compared with that of typical servo accelerometers used for angle-of-attack measurements. The areas evaluated included linearity, hysteresis, repeatability, temperature characteristics, roll-on-pitch interaction, sensitivity to lead-wire resistance, step response time, and rectification. Among the sensors being evaluated, the Spectron model RG-37 electrolytic tilt sensors have the highest overall accuracy in terms of linearity, hysteresis, repeatability, temperature sensitivity, and roll sensitivity. A comparison of the sensors with the servo accelerometers revealed that the accuracy of the RG-37 sensors was on the average about one order of magnitude worse. Even though a comparison indicates that the cost of each tilt sensor is about one-third the cost of each servo accelerometer, the sensors are considered unsuitable for angle-of-attack measurements. However, the potential exists for other applications such as wind tunnel wall-attitude measurements where the errors resulting from roll interaction, vibration, and response time are less and sensor temperature can be controlled.

  2. Influence of Angle of Attack and Lateral Force between Wheel and Rail on Wear of Rail--a Laboratory Study

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Angle of attack and lateral force are two important parameters influencing wheel-rail wear. This paper deals with the question of influences of the angle of attack and the lateral force on the wear of rail. A series of experiments are conducted on 1/4 JD-1 Wheel/Rail Tribology Simulation Facility. The angles of attack selected in the tests are 0°16′30″, 0°37′40″ and 1°0′0″ respectively. The lateral forces selected in the tests are 0.694 kN, 1.250 kN and 2.083 kN, respectively corresponding to the lateral forces of 25 kN, 45 kN and 75 kN measured in the field, with the aim of keeping the same ratio of L/V between laboratory and field conditions. It is found that the larger the angle of attack is, the more serious the wear of rail is. The relation of rail wear rate versus angle of attack is non-linear, and the relation of rail wear rate versus lateral force is approximately linear. The influence of angle of attack is more serious than that of lateral force. For the tractive wheelset, the wear index involving linear and quadratic function terms of angle of attack has good agreement with the limited experimental data. Some conclusions are given.

  3. Study on flow behavior and structure over chined fuselage at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A study of leeward vortex structure over chined fuselage and the effects of micro tip perturbation on its vortex flow have been carried out in wind tunnel experiments at Reynolds numbers from 1.26×105 to 5.04×105 with PIV and pressure measurement techniques.Firstly,the experiment results have proved that micro tip perturbation has no effects on the vortex flow and its aerodynamic characteristics over chined fuselage at high angle of attack,in which there are not any non-deterministic flow behaviors.Secondly,the evolution of leeward vortex structure over chined fuselage along the axis of model can be divided into four flow regimes:linear conical developed regime,decay regime of leeward vortex intensity,asymmetric leeward vortex break down regime and completely break down regime.And a correlation between leeward vortex structure and sectional aerodynamic force was also revealed in the present paper.Thirdly,the experiment results show the behavior of leeward vortex core trajectories and zonal characteristics of leeward vortex structure with angles of attack.Finally,the experiment results of Reynolds number effect on the leeward vortex flow have further confirmed research conclusions from previous studies:the flows over chined fuselage at high angles of attack are insensitive to variation of Reynolds number,and there is a little effect on the secondary boundary layer separation and the suction peak induced by leeward vortex.

  4. Penetration and impact resistance of PDC cutters inclined at different attack angles

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to develop a rotary-percussive bit with diamond-enhanced cutters assisted by high pressure water jets,it is necessary to study the damage mechanism and the penetration properties of PDC cutters subject to different impactload level and rock types. Therefore the impact experiments of the single PDC cutters with different attack angles in fourrocks: black basalt, Missouri red granite, Halston limestone, and a very soft (Roubidoux) sandstone were carried out,and the effects of rake angles of PDC cutters on both the penetration and impact resistance of PDC cutters have been discussed in detail. Test results show that a PDC insert can withstand a very strong impact in compression but is easily damaged by impact shearing, the PDC cutters are more easily damaged by shearing if the attack angles are relatively small, the45 PDC cutters have the least penetration resistance among the cutters tested. Thus it is suggested that the attack anglesof PDC cutters should be larger than 30 for bits which must withstand impact from a hammer

  5. Hydrodynamic performance of a vertical-axis tidal-current turbine with different preset angles of attack

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guang; YANG Ran-sheng; LIU Yan; ZHAO Peng-fei

    2013-01-01

    The instantaneous angle of attack on the blade has a significant effect on the hydrodynamic performance of a vertical-axis tidal-current turbine with straight blades.This paper investigates the influence of different preset angles of attack on the hydrodynamic performance of a three-bladed,vertical-axis,tidal-current turbine both experimentally and numerically.Experiments are carried out in a towing tank.This tested turbine's solidity is 0.1146.The preset angles of attack on the blade are-3°,0°,3°,and 5°,in the experiments.Experimental results show that with the increase of the preset angle of attack from-3°,to 5°,the hydrodynamic performance of the turbine is improved significantly with the power coefficients being increased from 15.3% to 34.8%,respectively.Compared to the result of a 0° preset angle of attack,the performance of the turbine with positive preset angles of attack is experimentally demonstrated to be beneficial.This performance improvement is also shown by numerical simulations based on the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations.In addition,the numerical results show that the optimal positive preset angle of attack is 7° for the turbine studied.The corresponding power coefficient is 38%.Beyond this optimal preset angle of attack,the hydrodynamic performance of the turbine decreases.Therefore,due to the dynamic stall phenomenon,an optimal preset angle of attack exists for any vertical-axis turbine.This value should be considered in the design of a vertical-axis tidal-current turbine.

  6. An evaluation of several methods of determining the local angle of attack on wind turbine blades

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Sørensen, Niels N.

    2014-01-01

    Several methods of determining the angles of attack (AOAs) on wind turbine blades are discussed in this paper. A brief survey of the methods that have been used in the past are presented, and the advantages of each method are discussed relative to their application in the BEM theory. Data from...... existing as well as new full rotor CFD computations of the MEXICO rotor are used in this analysis. A more accurate estimation of the AOA is possible from 3D full rotor CFD computations, but when working with experimental data, pressure measurements and sectional forces are often the only data available...

  7. Mechanism of transition in a hypersonic sharp cone boundary layer with zero angle of attack

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Firstly, the steady laminar flow field of a hypersonic sharp cone boundary layer with zero angle of attack was computed. Then, two groups of finite amplitude T-S wave disturbances were introduced at the entrance of the computational field, and the spatial mode transition process was studied by direct numerical simulation (DNS) method.The mechanism of the transition process was analyzed. It was found that the change of the stability characteristics of the mean flow profile was the key issue. Furthermore, the characteristics of evolution for the disturbances of different modes in the hypersonic sharp cone boundary layer were discussed.

  8. Effects of Sudden Changes in Inflow Conditions on the Angle of Attack on HAWT Blades

    CERN Document Server

    Stoevesandt, Bernhard

    2010-01-01

    In this paper changes in wind speed and wind direction from a measured wind field are being analyzed at high frequencies. This is used to estimate changes in the angle of attack (AOA) on a blade segment over short time periods for different estimated turbine concepts. Here a statistical approach is chosen to grasp the characteristics of the probability distributions to give an over all view of the magnitude and rate of the changes. The main interest is the generation of basic distributions for the calculation of dynamic stall effects and stall flutter due to wind fluctuations.

  9. Study of optical techniques for the Ames unitary wind tunnels. Part 3: Angle of attack

    Science.gov (United States)

    Lee, George

    1992-01-01

    A review of optical sensors that are capable of accurate angle of attack measurements in wind tunnels was conducted. These include sensors being used or being developed at NASA Ames and Langley Research Centers, Boeing Airplane Company, McDonald Aircraft Company, Arnold Engineering Development Center, National Aerospace Laboratory of the Netherlands, National Research Council of Canada, and the Royal Aircraft Establishment of England. Some commercial sensors that may be applicable to accurate angle measurements were also reviewed. It was found that the optical sensor systems were based on interferometers, polarized light detector, linear or area photodiode cameras, position sensing photodetectors, and laser scanners. Several of the optical sensors can meet the requirements of the Ames Unitary Plan Wind Tunnel. Two of these, the Boeing interferometer and the Complere lateral effect photodiode sensors are being developed for the Ames Unitary Plan Wind Tunnel.

  10. Method for estimating the aerodynamic coefficients of wind turbine blades at high angles of attack

    Science.gov (United States)

    Beans, E. W.; Jakubowski, G. S.

    1983-12-01

    The method is based on the hypothesis that at high angles of attack the force on an airfoil is produced by the deflection of the fluid across the lower surface. It is also hypothesized that all airfoils behave the same regardless of shape and that the effects of circulation and skin friction are small. It is pointed out that the expression for the force N normal to the airfoil due to momentum exchange can be written in terms of the component parallel to the flow (drag) and the component perpendicular to the flow (lift). A comparison of estimated values with measured values and generally accepted data indicates that the method given here estimates coefficients which are low. It is thought that the difference may derive from the persistence of circulation at high angles of attack. Low estimates are not seen as a serious limitation to the designer of wind turbines. Owing to the fifth power diameter relation, the effect of a low estimate of performance on the inner portion of the blade is minimized.

  11. Low-frequency unsteadiness of vortex wakes over slender bodies at high angle of attack

    Directory of Open Access Journals (Sweden)

    Ma Baofeng

    2014-08-01

    Full Text Available A type of flow unsteadiness with low frequencies and large amplitude was investigated experimentally for vortex wakes around an ogive-tangent cylinder. The experiments were carried out at angles of attack of 60–80° and subcritical Reynolds numbers of 0.6–1.8 × 105. The reduced frequencies of the unsteadiness are between 0.038 and 0.072, much less than the frequency of Karman vortex shedding. The unsteady flow induces large fluctuations of sectional side forces. The results of pressure measurements and particle image velocimetry indicate that the flow unsteadiness comes from periodic oscillation of the vortex wakes over the slender body. The time-averaged vortex patterns over the slender body are asymmetric, whose orientation is dependent on azimuthal locations of tip perturbations. Therefore, the vortex oscillation is a type of unsteady oscillation around a time-averaged asymmetric vortex structure.

  12. Evaluation of electrolytic tilt sensors for wind tunnel model angle-of-attack (AOA) measurements

    Science.gov (United States)

    Wong, Douglas T.

    1991-01-01

    The results of a laboratory evaluation of three types of electrolytic tilt sensors as potential candidates for model attitude or angle of attack (AOA) measurements in wind tunnel tests are presented. Their performance was also compared with that from typical servo accelerometers used for AOA measurements. Model RG-37 electrolytic tilt sensors were found to have the highest overall accuracy among the three types. Compared with the servo accelerometer, their accuracies are about one order of magnitude worse and each of them cost about two-thirds less. Therefore, the sensors are unsuitable for AOA measurements although they are less expensive. However, the potential for other applications exists where the errors resulting from roll interaction, vibration, and response time are less, and sensor temperature can be controlled.

  13. Investigation of Load Prediction on the Mexico Rotor Using the Technique of Determination of the Angle of Attack

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær;

    2012-01-01

    ). The extracted airfoil data are put into a BEM code, and the calculated axial and tangential forces are compared to both computations using BEM with Glauert's and SHEN's tip loss correction models and experimental data. The comparisons show that the present method of determination of angle of attack is correct......Blade element moment (BEM) is a widely used technique for prediction of wind turbine aerodynamics performance, the reliability of airfoil data is an important factor to improve the prediction accuracy of aerodynamic loads and power using a BEM code. The method of determination of angle of attack...

  14. Parametric approximation of airfoil aerodynamic coefficients at high angles of attack

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Zahle, Frederik; Bak, Christian

    2014-01-01

    Three methods for estimating the lift and drag curves in the 360° angle of attack (α) range with harmonic approximation functions were analyzed in the present work. The first method assumes aerodynamic response of a flat plate, the second utilizes even sine and even cosine approximation functions......-dimensional Computational Fluid Dynamics (CFD) computations. This was done by a comparison of the results obtained with 2D steady CFD with 3D unsteady CFD. In the present work, reference aerodynamic coefficients were used directly in this α region. Reference aerodynamic coefficients were also used directly in the α region...... between -30° and 30° as in this region the data is either available of may be computed with 2D CFD. In between the aforementioned α regions, the present approximation method produced lift, drag, and moment coefficient curves satisfactorily close to the reference by using several data points to tune...

  15. Identification of variations of angle of attack and lift coefficient for a large horizontal-axis wind turbine

    DEFF Research Database (Denmark)

    Rezaeiha, Abdolrahim; Arjomandi, Maziar; Kotsonis, Marios;

    2015-01-01

    The current paper investigates the effects of various elements including turbulence, wind shear, yawed inflow, tower shadow, gravity, mass and aerodynamic imbalances on variations of angle of attack and lift coefficient for a large horizontal-axis wind turbine. It will identify the individual...... and the aggregate effect of elements on variations of mean value and standard deviation of the angle of attack and lift coefficient in order to distinguish the major contributing factors. The results of the current study is of paramount importance in the design of active load control systems for wind turbine....

  16. High angle of attack position sensing for the Southampton University magnetic suspension and balance system

    Science.gov (United States)

    Parker, David H.

    1987-01-01

    An all digital five channel position detection system is to be installed in the Southampton University Magnetic Suspension and Balance System (SUMSBS). The system is intended to monitor a much larger range of model pitch attitudes than has been possible hitherto, up to a maximum of a 90 degree angle of attack. It is based on the use of self-scanning photodiode arrays and illuminating laser light beams, together with purpose built processing electronics. The principles behind the design of the system are discussed, together with the results of testing one channel of the system which was used to control the axial position of a magnetically suspended model in SUMSBS. The removal of optically coupled heave position information from the axial position sensing channel is described.

  17. ASYMMETRIC VORTICES FLOW OVER SLENDER BODY AND ITS ACTIVE CONTROL AT HIGH ANGLE OF ATTACK

    Institute of Scientific and Technical Information of China (English)

    DENG Xueying; WANG Yankui

    2004-01-01

    The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant importance for both academic field and engineering area. This paper attempts to provide an update state of art to the investigations on the fields of forebody asymmetric vortices. This review emphasizes the correlation between micro-perturbation on the model nose and its response and evolution behaviors of the asymmetric vortices. The critical issues are discussed,which include the formation and evolution mechanism of asymmetric multi-vortices; main behaviors of asymmetric vortices flow including its deterministic feature and vortices flow structure; the evolution and development of asymmetric vortices under the perturbation on the model nose; forebody vortex active control especially discussed micro-perturbation active control concept and technique in more detail. However present understanding in this area is still very limited and this paper tries to identify the key unknown problems in the concluding remarks.

  18. Design of a Normal Acceleration and Angle of Attack Control System for a Missile Having Front and Rear Control Surfaces

    Science.gov (United States)

    Ochi, Yoshimasa

    Precise normal acceleration control is essential for missile guidance. Missiles with both front and rear control surfaces have a higher ability to control normal acceleration than missiles with front or rear control surfaces only. From the viewpoint of control, however, the control problem becomes a two-input-one-output problem, where generally control input cannot be determined uniquely. This paper proposes controlling angle of attack as well as normal acceleration, which makes the problem a two-input-two-output one and determines the controls uniquely. Normal acceleration command is given by a guidance system, but angle of attack command must be generated in accordance to the acceleration command without affecting the normal acceleration control. This paper also proposes such a command generator for angle of attack. Computer simulation is conducted using a nonlinear missile model to investigate the effectiveness of the control system along with control systems designed using three other methods.

  19. Effect of Varying the Angle of Attack of the Scales on a Biomimetic Shark Skin Model on Embedded Vortex Formation

    Science.gov (United States)

    Wheelus, Jennifer; Lang, Amy; Bradshaw, Michael; Jones, Emily; Afroz, Farhana; Motta, Philip; Habegger, Maria

    2012-11-01

    The skin of fast-swimming sharks is proposed to have mechanisms to reduce drag and delay flow separation. The skin of fast-swimming and agile sharks is covered with small teeth-like denticles on the order of 0.2 mm. The shortfin mako is one of the fastest and most agile ocean predators creating the need to minimize its pressure drag by controlling flow separation. Biological studies of the shortfin mako skin have shown the passive bristling angle of their denticles to exceed 50 degrees in areas on the flank corresponding to the locations likely to experience separation first. It has been shown that for an angle of attack of 90 degrees, vortices form within these cavities and impose a partial slip condition at the surface of the cavity. This experiment focuses on smaller angles of attack for denticle bristling, closer to the range thought to be achieved on real shark skin. A 3-D bristled shark skin model with varying angle of attack, embedded below a boundary layer, was used to study the formation of cavity vortices through fluorescent dye visualization and Digital Particle Image Velocimetry (DPIV). The effect of varying angle of attack on vortex formation will be discussed.

  20. Flow Control and Mechanism for Slender Body at High Angle of Attack

    Science.gov (United States)

    Ming, Xiao; Gu, Yunsong

    The wind tunnel experiments for high angle of attack aerodynamics were designed from the inspiration of understanding the mechanism and development of an innovative flow control technique. The side force, varying with the different rolling angle, is featured by bi-stable situation, and can be easily switched by a tiny disturbance. A miniature strake is attached to the nose tip of the model. When the strake is stationary, the direction of the side force can be controlled. When the nose tip strake, as an unsteady control means, is swung the flow pattern could be controlled. The results obtained from dynamic measurements of section side force indicate that when the strake swing at lower frequency the side force can follow the cadence of the swinging strake. With increasing frequency, the magnitude of the side force decreases. At still high frequency, the side force diminishes to zero. The side forces could be also changed proportionally. Based on the experimental factors, the mechanism of the asymmetry is discussed.

  1. A hybrid system approach to airspeed, angle of attack and sideslip estimation in Unmanned Aerial Vehicles

    KAUST Repository

    Shaqura, Mohammad

    2015-06-01

    Fixed wing Unmanned Aerial Vehicles (UAVs) are an increasingly common sensing platform, owing to their key advantages: speed, endurance and ability to explore remote areas. While these platforms are highly efficient, they cannot easily be equipped with air data sensors commonly found on their larger scale manned counterparts. Indeed, such sensors are bulky, expensive and severely reduce the payload capability of the UAVs. In consequence, UAV controllers (humans or autopilots) have little information on the actual mode of operation of the wing (normal, stalled, spin) which can cause catastrophic losses of control when flying in turbulent weather conditions. In this article, we propose a real-time air parameter estimation scheme that can run on commercial, low power autopilots in real-time. The computational method is based on a hybrid decomposition of the modes of operation of the UAV. A Bayesian approach is considered for estimation, in which the estimated airspeed, angle of attack and sideslip are described statistically. An implementation on a UAV is presented, and the performance and computational efficiency of this method are validated using hardware in the loop (HIL) simulation and experimental flight data and compared with classical Extended Kalman Filter estimation. Our benchmark tests shows that this method is faster than EKF by up to two orders of magnitude. © 2015 IEEE.

  2. A Tail Buffet Loads Prediction Method for Aircraft at High Angles of Attack

    Science.gov (United States)

    Pototzky, Anthony S.; Moses, Robert W.

    2005-01-01

    Aircraft designers commit significant resources to the design of aircraft in meeting performance goals. Despite fulfilling traditional design requirements, many fighter aircraft have encountered buffet loads when demonstrating their high angle-of-attack maneuver capabilities. As a result, during test or initial production phases of fighter development programs, many new designs are impacted, usually in a detrimental way, by resulting in reassessing designs or limiting full mission capability. These troublesome experiences usually stem from overlooking or completely ignoring the effects of buffet during the design phase of aircraft. Perhaps additional requirements are necessary that addresses effects of buffet in achieving best aircraft performance in fulfilling mission goals. This paper describes a reliable, fairly simple, but quite general buffet loads analysis method to use in the initial design phases of fighter-aircraft development. The method is very similar to the random gust load analysis that is now commonly available in a commercial code, which this analysis capability is based, with some key modifications. The paper describes the theory and the implementation of the methodology. The method is demonstrated on a JSF prototype example problem. The demonstration also serves as a validation of the method, since, in the paper, the analysis is shown to nearly match the flight data. In addition, the paper demonstrates how the analysis method can be used to assess candidate design concepts in determining a satisfactory final aircraft configuration.

  3. High angle of attack: Forebody flow physics and design emphasizing directional stability

    Science.gov (United States)

    Ravi, R.

    A framework for understanding the fundamental physics of flowfields over forebody type shapes at low speed, high angle of attack conditions with special emphasis on sideslip has been established. Computational Fluid Dynamics (CFD) has been used to study flowfieids over experimentally investigated forebodies: the Lamont tangent-ogive forebody, the F-5A forebody and the Erickson chine forebody. A modified version of a current advanced code, CFL3D, was used to solve the Euler and thin-layer Navier-Stokes equations. The Navier-Stokes equations used a form of the Baldwin-Lomax turbulence model modified to account for massive crossflow separation. Using the insight provided by the solutions obtained using CFD, together with comparison with limited available data, the aerodynamics of forebodies with positive directional stability has been revealed. An unconventional way of presenting the results is used to illustrate how a positive contribution to directional stability arises. Based on this new understanding, a parametric study was then conducted to determine which shapes promote a positive contribution to directional stability. The effect of cross-sectional shape on directional stability was found to be very significant. Broad chine-shaped cross-sections were found to promote directional stability. Also, directional stability is improved if the chine is placed closer to the top of the cross-section. Planform shapes also played an important role in determining the forebody directional stability characteristics. This initial parametric study has been used to propose some guidelines for aerodynamic design to promote positive directional stability.

  4. Bifurcation analysis and stability design for aircraft longitudinal motion with high angle of attack

    Institute of Scientific and Technical Information of China (English)

    Xin Qi; Shi Zhongke

    2015-01-01

    Bifurcation analysis and stability design for aircraft longitudinal motion are investigated when the nonlinearity in flight dynamics takes place severely at high angle of attack regime. To pre-dict the special nonlinear flight phenomena, bifurcation theory and continuation method are employed to systematically analyze the nonlinear motions. With the refinement of the flight dynam-ics for F-8 Crusader longitudinal motion, a framework is derived to identify the stationary bifurca-tion and dynamic bifurcation for high-dimensional system. Case study shows that the F-8 longitudinal motion undergoes saddle node bifurcation, Hopf bifurcation, Zero-Hopf bifurcation and branch point bifurcation under certain conditions. Moreover, the Hopf bifurcation renders ser-ies of multiple frequency pitch oscillation phenomena, which deteriorate the flight control stability severely. To relieve the adverse effects of these phenomena, a stabilization control based on gain scheduling and polynomial fitting for F-8 longitudinal motion is presented to enlarge the flight envelope. Simulation results validate the effectiveness of the proposed scheme.

  5. Experimental investigation of separated shear layer from a leading edge subjected to various angles of attack with tail flap deflections

    Indian Academy of Sciences (India)

    K Anand; S Sarkar

    2015-05-01

    Shear layer development over a thick flat plate with a semi-circular leading edge is investigated for a range of angles of attack under different pressure gradients for a Reynolds number of 2.44×105 (based on chord and free-stream velocity). The characteristics of the separated shear layer are very well documented through a combination of surface pressure measurement and smoke flow visualization. The instability of the separated layer occurs because of enhanced receptivity of perturbations leading to the development of significant unsteadiness and three-dimensional motions in the second-half of the bubble. The onset of separation, transition and the point of reattachment are identified for varying angles of attack and pressure gradients imposed by tail flap deflections. The data concerning bubble length, laminar portion and reattachment points agree well with the literature.

  6. Comparison of high-angle-of-attack slender-body theory and exact solutions for potential flow over an ellipsoid

    Science.gov (United States)

    Hemsch, Michael J.

    1990-01-01

    The accuracy of high-alpha slender-body theory (HASBT) for bodies with elliptical cross-sections is presently demonstrated by means of a comparison with exact solutions for incompressible potential flow over a wide range of ellipsoid geometries and angles of attack and sideslip. The addition of the appropriate trigonometric coefficients to the classical slender-body theory decomposition yields the formally correct HASBT, and results in accuracies previously considered unattainable.

  7. Operating characteristics of an inlet model tested with a 0.5m powered fan at high angles of attack

    Science.gov (United States)

    Koncsek, J. L.; Shaw, R. J.

    1977-01-01

    An inlet model designed for high angle of attack capability, coupled to a .508 m tip diameter turbofan simulator, was tested in the NASA-Lewis Research Center's 9-by 15-ft low speed wind tunnel. The test variables were: tunnel velocity, 0 to 75 m/s; inlet angle of attack, 0 to 120 deg; and fan face corrected airflow per unit area, 75 to 200 kg/s sqm. The inlet flow separation boundaries, the fan face total pressure recovery and distortion characteristics, and the fan blade vibratory stresses were determined. The recovery, distortion, and stress levels showed no abrupt changes at the onset of separation, but became gradually more unfavorable as the size and intensity of the separation increased as induced by increasingly severe operating conditions. Performance characteristics for a large scale model of the inlet were estimated from these test results.

  8. Survey of needs and capabilities for wind tunnel testing of dynamic stability of aircraft at high angles of attack

    Science.gov (United States)

    Orlik-Ruckemann, K. J.

    1973-01-01

    A survey was conducted relative to future requirements for dynamic stability information for such aerospace vehicles as the space shuttle and advanced high performance military aircraft. High-angle-of-attack and high-Reynolds number conditions were emphasized. A review was made of the wind-tunnel capabilities in North America for measuring dynamic stability derivatives, revealing an almost total lack of capabilities that could satisfy these requirements. Recommendations are made regarding equipment that should be constructed to remedy this situation. A description is given of some of the more advanced existing capabilities, which can be used to at least partly satisfy immediate demands.

  9. An Experimental Study on Aerodynamic Sound Generated from Wake Interaction of Circular Cylinder and Airfoil with Attack Angle in Tandem

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In our previous study, the effects of the interval between the cylinder and the airfoil on the aerodynamic sound were investigated and compared with the cases of single circular and single airfoil. In this study, the effects of the attack angle of the airfoil located downstream on the characteristics of aerodynamic sound and the wake structure are investigated at a given interval between the cylinder and the airfoil. It is found that the sound pressure level of DFN and the peak frequency decrease with increasing attack angle of airfoil because of the diffusive wake structure due to the increased back pressure of circular cylinder, which is caused by the blocking effect of airfoil. It is shown that the sound sources are corresponded to the attack points of shedding vortex form the upstream circular cylinder to the downstream airfoil. We conclude that the pressure fluctuation at the airfoil surface effects on the sound pressure level, from the flow visualizations and the exploration test of sound source.

  10. The Effect of Aspect Ratio and Angle of Attack on the Transition Regions of the Inverted Flag Instability

    Science.gov (United States)

    Cosse, Julia; Sader, John; Fan, Boyu; Kim, Daegyoum; Gharib, Mory

    2014-11-01

    The inverted flag instability occurs when a pliable plate is held parallel to a free-stream, with the leading edge free to move and the trailing edge clamped. Large-amplitude flapping is observed across a slim band of non-dimensional wind speeds. This specific boundaries of this flapping band vary greatly, depending on both the aspect ratio and the angle of attack of the plate with respect to the incoming flow. In addition, both periodic and aperiodic flapping modes exist. The frequency of the plate motion was analyzed and was found to be consistent with vortex-induced vibration. This research is supported by the Gordon and Betty Moore Foundation.

  11. Development of microprocessor-based laser velocimeter and its application to measurement of jet exhausts and flows over missiles at high angles of attack

    Science.gov (United States)

    Harwell, K. E.; Farmer, W. M.; Hornkohl, J. O.; Stallings, E.

    1981-03-01

    During the past three years, personnel have developed a unique three-component laser velocimeter for the in situ measurement of particle and/or gas velocities in flow fields produced behind bodies at high angles of attack and in jet exhaust plumes. This report describes the development of the laser velocimeter and its subsequent application of the measurement of the velocity distribution and vortex structure in free jets and in flows over missiles at high angles of attack.

  12. Convective heat transfer over a wall mounted cube at different angle of attack using large eddy simulation

    Directory of Open Access Journals (Sweden)

    Heidarzadeh Habibollah

    2014-01-01

    Full Text Available Turbulent fluid flow and convective heat transfer over the wall mounted cube in different flow angle of attack have been studied numerically using Large Eddy Simulation. Cube faces and plate have a constant heat flux. Dynamic Smagorinsky (DS subgrid scale model were used in this study. Angles were in the range 0≤θ≤45 and Reynolds number based on the cube height and free stream velocity was 4200. The numerical simulation results were compared with the experimental data of Nakamura et al [6, 7]. Characteristics of fluid flow field and heat transfer compared for four angles of attack. Flow around the cube was classified to four regimes. Results was represented in the form of time averaged normalized streamwise velocity and Reynolds stress in different positions, temperature contours, local and average Nusselt number over the faces of cube. Local convective heat transfer on cube faces was affected by flow pattern around the cube. The local convective heat transfer from the faces of the cube and plate are directly related to the complex phenomena such as horse shoe vortex, arch vortexes in behind the cube, separation and reattachment. Results show that overall convective heat transfer of cube and mean drag coefficient have maximum and minimum value at θ=0 deg and θ=25 deg respectively.

  13. Turbofan blade stresses induced by the flow distortion of a VTOL inlet at high angles of attack

    Science.gov (United States)

    Williams, R. C.; Diedrich, J. H.; Shaw, R. J.

    1983-01-01

    A 51-cm-diameter turbofan with a tilt-nacelle VTOL inlet was tested in the Lewis Research Center's 9- by 15-Ft Low Speed Wind Tunnel at velocities up to 72 m/s and angles of attack up to 120 deg. Fan-blade vibratory stress levels were investigated over a full aircraft operating range. These stresses were due to inlet air flow distortion resulting from (1) internal flow separation in the inlet, and (2) ingestion of the exterior nacelle wake. Stress levels are presented, along with an estimated safe operating envelope, based on infinite blade fatigue life.

  14. Numerical simulation by TVD schemes of complex shock reflections from airfoils at high angle of attack. [Total Variation Diminishing

    Science.gov (United States)

    Moon, Young J.; Yee, H. C.

    1987-01-01

    The shock-capturing capability of total variation diminishing (TVD) schemes is demonstrated for a more realistic complex shock-diffraction problem for which the experimental data are available. Second-order explicit upwind and symmetric TVD schemes are used to solve the time-dependent Euler equations of gas dynamics for the interaction of a blast wave with an airfoil at high angle-of-attack. The test cases considered are a time-dependent moving curved-shock wave and a contant moving planar-shock wave impinging at an angle-of-attack 30 deg on a NACA 0018 airfoil. Good agreement is obtained between isopycnic contours computed by the TVD schemes and those from experimental interferograms. No drastic difference in flow-field structure is found between the curved- and planar-shock wave cases, except for a difference in density level near the lower surface of the airfoil. Computation for cases with higher shock Mach numbers is also possible. Numerical experiments show that the symmetric TVD scheme is less sensitive to the boundary conditions treatment than the upwind scheme.

  15. 1.5 μm lidar anemometer for true air speed, angle of sideslip, and angle of attack measurements on-board Piaggio P180 aircraft

    Science.gov (United States)

    Augere, B.; Besson, B.; Fleury, D.; Goular, D.; Planchat, C.; Valla, M.

    2016-05-01

    Lidar (light detection and ranging) is a well-established measurement method for the prediction of atmospheric motions through velocity measurements. Recent advances in 1.5 μm Lidars show that the technology is mature, offers great ease of use, and is reliable and compact. A 1.5 μm airborne Lidar appears to be a good candidate for airborne in-flight measurement systems. It allows measurements remotely, outside aircraft aerodynamic disturbance, and absolute air speed (no need for calibration) with great precision in all aircraft flight domains. In the framework of the EU AIM2 project, the ONERA task has consisted of developing and testing a 1.5 μm anemometer sensor for in-flight airspeed measurements. The objective of this work is to demonstrate that the 1.5 μm Lidar sensor can increase the quality of the data acquisition procedure for aircraft flight test certification. This article presents the 1.5 μm anemometer sensor dedicated to in-flight airspeed measurements and describes the flight tests performed successfully on-board the Piaggio P180 aircraft. Lidar air data have been graphically compared to the air data provided by the aircraft flight test instrumentation (FTI) in the reference frame of the Lidar sensor head. Very good agreement of true air speed (TAS) by a fraction of ms‑1, angle of sideslip (AOS), and angle of attack (AOA) by a fraction of degree were observed.

  16. Vortex-induced vibrations of a DU96-W-180 airfoil at 90° angle of attack

    DEFF Research Database (Denmark)

    Skrzypinski, Witold Robert; Gaunaa, Mac; Sørensen, Niels N.;

    2014-01-01

    This work presents an analysis of vortex-induced vibrations of a DU96-W-180 airfoil in deep stall at a 90 degrees angle of attack, based on 2D and 3D Reynolds Averaged Navier Stokes and 3D Detached Eddy Simulation unsteady Computational Fluid Dynamics computations with non-moving, prescribed motion...... and elastically mounted airfoil suspensions. Stationary vortex-shedding frequencies computed in 2D and 3D Computational Fluid Dynamics differed. In the prescribed motion computations, the airfoil oscillated in the direction of the chord line. Negative aerodynamic damping, found in both 2D and 3D Computational...... Fluid Dynamics computations with moving airfoil, showed in the vicinity of the stationary vortex-shedding frequency computed by 2D Computational Fluid Dynamics. A shorter time series was sufficient to verify the sign of the aerodynamic damping in the case of the elastic computations than the prescribed...

  17. Vortex flow structures and interactions for the optimum thrust efficiency of a heaving airfoil at different mean angles of attack

    Energy Technology Data Exchange (ETDEWEB)

    Martín-Alcántara, A.; Fernandez-Feria, R. [Universidad de Málaga, Andalucía Tech, E. T. S. Ingeniería Industrial, Dr Ortiz Ramos s/n, 29071 Málaga (Spain); Sanmiguel-Rojas, E. [Área de Mecánica de Fluidos, Universidad de Jaén, Campus de las Lagunillas, 23071 Jaén (Spain)

    2015-07-15

    The thrust efficiency of a two-dimensional heaving airfoil is studied computationally for a low Reynolds number using a vortex force decomposition. The auxiliary potentials that separate the total vortex force into lift and drag (or thrust) are obtained analytically by using an elliptic airfoil. With these auxiliary potentials, the added-mass components of the lift and drag (or thrust) coefficients are also obtained analytically for any heaving motion of the airfoil and for any value of the mean angle of attack α. The contributions of the leading- and trailing-edge vortices to the thrust during their down- and up-stroke evolutions are computed quantitatively with this formulation for different dimensionless frequencies and heave amplitudes (St{sub c} and St{sub a}) and for several values of α. Very different types of flows, periodic, quasi-periodic, and chaotic described as St{sub c}, St{sub a}, and α, are varied. The optimum values of these parameters for maximum thrust efficiency are obtained and explained in terms of the interactions between the vortices and the forces exerted by them on the airfoil. As in previous numerical and experimental studies on flapping flight at low Reynolds numbers, the optimum thrust efficiency is reached for intermediate frequencies (St{sub c} slightly smaller than one) and a heave amplitude corresponding to an advance ratio close to unity. The optimal mean angle of attack found is zero. The corresponding flow is periodic, but it becomes chaotic and with smaller average thrust efficiency as |α| becomes slightly different from zero.

  18. A New Acute Attack of Angle Closure Glaucoma Animal Model with Healon 5

    Directory of Open Access Journals (Sweden)

    Silvania Y. F. Lau

    2011-05-01

    Full Text Available Acute angle closure glaucoma (AACG is an ocular emergency and sight -threatening disease in which the intraocular ocular pressure (IOP rises suddenly due to blockage of aqueous humor outflow. It can cause permanent loss in visual acuity and visual field. In animal study, the well-established model to study AACG is by fluid infusion and by adjusting the bottle level, a high IOP can be induced in a few seconds. However, there is no blockage of aqueous outflow and the pressure rise is unrealistically fast. To mimic human AACG, we suggest to use Healon 5, an ophthalmic viscosurgical device, which is injected intracamerally to block the aqueous outflow. The IOP is allowed to build up naturally. We found that, with this technique, the IOP elevated at a rate of 0.57 mmHg/min before it hit 40 mmHg, which is considered as AACG in human. The maximum IOP registered was above 70 mmHg. Thinning of retinal nerve fiber layer (RNFL and neural cells lost were seen. Visual function evaluated by ERG showed reduction in a-wave, b-wave, photopic negative response (PhNR and oscillatory potentials (OPs activities. In conclusion, Healon 5 is effective in inducing acute transient rise in IOP which mimics human AACG.

  19. 1.5 μm lidar anemometer for true air speed, angle of sideslip, and angle of attack measurements on-board Piaggio P180 aircraft

    International Nuclear Information System (INIS)

    Lidar (light detection and ranging) is a well-established measurement method for the prediction of atmospheric motions through velocity measurements. Recent advances in 1.5 μm Lidars show that the technology is mature, offers great ease of use, and is reliable and compact. A 1.5 μm airborne Lidar appears to be a good candidate for airborne in-flight measurement systems. It allows measurements remotely, outside aircraft aerodynamic disturbance, and absolute air speed (no need for calibration) with great precision in all aircraft flight domains. In the framework of the EU AIM2 project, the ONERA task has consisted of developing and testing a 1.5 μm anemometer sensor for in-flight airspeed measurements. The objective of this work is to demonstrate that the 1.5 μm Lidar sensor can increase the quality of the data acquisition procedure for aircraft flight test certification. This article presents the 1.5 μm anemometer sensor dedicated to in-flight airspeed measurements and describes the flight tests performed successfully on-board the Piaggio P180 aircraft. Lidar air data have been graphically compared to the air data provided by the aircraft flight test instrumentation (FTI) in the reference frame of the Lidar sensor head. Very good agreement of true air speed (TAS) by a fraction of ms−1, angle of sideslip (AOS), and angle of attack (AOA) by a fraction of degree were observed. (special issue article)

  20. Experimental study of heat transfer enhancement in solar air heater with different angle of attack of V-down continuous ribs

    Science.gov (United States)

    Istanto, Tri; Danardono, Dominicus; Yaningsih, Indri; Wijayanta, Agung Tri

    2016-06-01

    In this paper, an experimental study on the effect of angle attack in V-down continuous ribs on heat transfer and friction factor in an artificially roughened air heater duct is presented. The electric heater with a constant heat flux as a simulation of the indoor testing solar air heater is used to heat the roughened part of rectangular duct while other parts were insulated. The system and operating conditions were used to decide the range of parameters for the study. The ratio of the width to height of the duct (W/H) was 12, the relative roughness pitch (p/e) was 10, the relative roughness height (e/Dh) was 0.033 and the angle of attack of flow (α) was 30-80°. The air flow rate corresponded to Reynolds number between 3500 -10,000. The result of heat transfer and friction factor had been compared to those for smooth duct under similar flow and thermal boundary condition. The thermo-hydraulic performance also had been considered. As a result, the maximum enhancement of Nusselt number (Nu) and friction factor(f) were 2.34 and 2.45 times, respectively. For each variation of angle attack of flow, the thermo-hydraulic performance has been compared and the result shows that a V-down continuous rib with the angle of attack of flow as 60° gave the best thermo-hydraulic performance.

  1. A physical model of asymmetric vortices flow structure in regular state over slender body at high angle of attack

    Institute of Scientific and Technical Information of China (English)

    邓学蓥; 王刚; 陈学锐; 王延奎; 刘沛清; 郗忠祥

    2003-01-01

    In subcritical Reyolds number flow region, the repeatable and determinate asymmetric vortices flow at regular state can be obtained by manually setting mini-perturbation on the nose of a pointed ogive-cylinder model at high angle of attack and zero side slip. Test results of this study involve surface pressure distributions, sectional-side-force distributions and flow visualizations. The analyses of these results revealed a complicated multi-vortices system at regular state in which asymmetric twin vortices with inception region and fully developed region, asymmetric triple vortices, four vortices region, five vortices region and Karman-vortex-street-like flow region are developed along the slender body. The correlation between multi-vortices system structures and corresponding sectional-side-force distribution is given. The behaviors of multi-vortices flow structure at the peculiar points of sectional-side-force distributions and characteristics of corresponding pressure distribution are analysed. Finally, a physical model of asymmetric multi-vortices flow structure in regular state over slender body is developed.

  2. Validation of aerodynamic parameters at high angles of attack for RAE high incidence research models

    Science.gov (United States)

    Ross, A. Jean; Edwards, Geraldine F.; Klein, Vladislav; Batterson, James G.

    1987-01-01

    Two series of free-flight tests have been conducted for combat aircraft configuration research models in order to investigate flight behavior near departure conditions as well as to obtain response data from which aerodynamic characteristics can be derived. The structure of the mathematical model and values for the mathematical derivatives have been obtained through an analysis of the first series, using stepwise regression. The results thus obtained are the bases of the design of active control laws. Flight test results for a novel configuration are compared with predicted responses.

  3. Aerodynamic coefficients of plain and helically filleted twin circular cylinders for varying wind angles of attack

    DEFF Research Database (Denmark)

    Acampora, Antonio; Georgakis, Christos T.

    2013-01-01

    Moderate vibrations continue to be recorded on the Øresund Bridge twin-stay cables. System identification techniques have been applied to investigate the aerodynamic characteristics of the cables based on ambient vibration measurements. As might be expected, the measured aerodynamic damping ratios...... vary from those estimated through use of aerodynamic coefficients of single circular cylinders, as reported in literature. To address this issue, wind tunnel tests were performed on a 1:2.3 scale section model of the Øresund Bridge cables, with and without the presence of helical fillets. In this paper...

  4. A Study of 2D Separated Cascade Flow at Large Angles of Attack Using Euler Equations

    Institute of Scientific and Technical Information of China (English)

    YeDajun; LiuWeidong; 等

    1992-01-01

    This paper presents a numerical simulation method developed for separated flow in cascades using Euler equations and demonstrates the Feasibility of this method MacCOrmack's two-steps explicit finite difference scheme is used to discretize the equations in conservation form,and the artificial viscosity is added to the discretized inviscid equations by means of the self-adapted filter technique.The initial separation boundary is given according to simple experimental results.The numerical simulation results including subsonic and transonic turbine cascades flow with of without separation show that the fundamental idea of this numerical method is reasonable and simple.The present stude indicates that for solving certain engineering problems it is a simple and effective tool for adding some viscosity corrections to inviscld flow model,especially the current when the Navier-Stokes equations have not been solved very effectively for verious complicated flows in turbonachinery.

  5. Drag prediction for blades at high angle of attack using CFD

    DEFF Research Database (Denmark)

    Sørensen, Niels N.; Michelsen, J.A.

    2004-01-01

    In the present paper it is first demonstrated that state of the art 3D CFD codes are. capable of predicting the correct dependency of the integrated drag of a flat plate placed perpendicular to the flow. This is in strong contrast to previous 2D investigations of infinite plates, where computations...... are known to severely overpredict drag. We then demonstrate that the computed drag distribution along the plate span deviate from the general expectation of 2D behavior at the central part of the plate, an important finding in connection with the theoretical estimation of drag behavior on wind turbine...... blades. The computations additionally indicate that a tip effect is present that produces increased drag near the end of the plate, which is opposite of the assumptions generally used in drag estimation for blades. Following this several wind turbine blades are analyzed, ranging from older blades...

  6. Influences of attack angle and mach number on aerodynamic characters of typical sections of extra-long blade in a steam turbine

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On super-sonic or trans-sonic planar cascade wind tunnel of free jet intermittent type, wind blowing experiments were performed on the typical sections of stator and rotor blades in the last stage of ultra-ultra-critical steam turbine with extra-long blade of 1200mm. The influences of attack angle and Mach number on the aerodynamic performances of these sections of the blade profiles were verified, and their operating ranges were also specified.

  7. BiGlobal linear stability analysis on low-Re flow past an airfoil at high angle of attack

    KAUST Repository

    Zhang, Wei

    2016-04-04

    We perform BiGlobal linear stability analysis on flow past a NACA0012 airfoil at 16° angle of attack and Reynolds number ranging from 400 to 1000. The steady-state two-dimensional base flows are computed using a well-tested finite difference code in combination with the selective frequency damping method. The base flow is characterized by two asymmetric recirculation bubbles downstream of the airfoil whose streamwise extent and the maximum reverse flow velocity increase with the Reynolds number. The stability analysis of the flow past the airfoil is carried out under very small spanwise wavenumber β = 10−4 to approximate the two-dimensional perturbation, and medium and large spanwise wavenumbers (β = 1–8) to account for the three-dimensional perturbation. Numerical results reveal that under small spanwise wavenumber, there are at most two oscillatory unstable modes corresponding to the near wake and far wake instabilities; the growth rate and frequency of the perturbation agree well with the two-dimensional direct numerical simulation results under all Reynolds numbers. For a larger spanwise wavenumber β = 1, there is only one oscillatory unstable mode associated with the wake instability at Re = 400 and 600, while at Re = 800 and 1000 there are two oscillatory unstable modes for the near wake and far wake instabilities, and one stationary unstable mode for the monotonically growing perturbation within the recirculation bubble via the centrifugal instability mechanism. All the unstable modes are weakened or even suppressed as the spanwise wavenumber further increases, among which the stationary mode persists until β = 4.

  8. Experimental investigation of effect of flow attack angle on thermohydraulic performance of air flow in a rectangular channel with discrete V-pattern baffle on the heated plate

    Directory of Open Access Journals (Sweden)

    Raj Kumar

    2016-05-01

    Full Text Available In this work, the effect of angle of attack ( α a of the discrete V-pattern baffle on thermohydraulic performance of rectangular channel has been studied experimentally. The baffle wall was constantly heated and the other three walls of the channel were kept insulated. The experimentations were conducted to collect the data on Nusselt number ( N u b and friction factor ( f b by varying the Reynolds number (Re = 3000–21,000 and angle of attack ( α a from 30° to 70°, for the kept values of relative baffle height ( H b / H = 0 . 50 , relative pitch ratio ( P b / H = 1 . 0 , relative discrete width ( g w / H b = 1 . 5 and relative discrete distance ( D d / L v = 0 . 67 . As compared to the smooth wall, the V-pattern baffle roughened channel enhances the Nusselt number ( N u b and friction factor ( f b by 4.2 and 5.9 times, respectively. The present discrete V-pattern baffle shapes with angle of attack ( α a of 60° equivalent to flow Reynolds number of 3000 yields the greatest thermohydraulic performance. Discrete V-pattern baffle has improved thermal performance as compared to other baffle shapes’ rectangular channel.

  9. Methods for root effects, tip effects and extending the angle of attack range to {+-} 180 deg., with application to aerodynamics for blades on wind turbines and propellers

    Energy Technology Data Exchange (ETDEWEB)

    Montgomerie, Bjoern

    2004-06-01

    For wind turbine and propeller performance calculations aerodynamic data, valid for several radial stations along the blade, are used. For wind turbines the data must be valid for the 360 degree angle of attack range. The reason is that all kinds of abnormal conditions must be analysed especially during the design of the turbine. Frequently aerodynamic data are available from wind tunnel tests where the angle of attack range is from say -5 to +20 degrees. This report describes a method to extend such data to be valid for {+-} 180 degrees. Previously the extension of data has been very approximate following the whim of the moment with the analyst. Furthermore, the Himmelskamp effect at the root and tip effects are treated in the complete method.

  10. 鱼雷纯方位攻击提前角优化分析%Optimization of Torpedo Bearing-only Attack Angle in Advance

    Institute of Scientific and Technical Information of China (English)

    董严红; 卫翔; 孙春生

    2014-01-01

    The bearing-only torpedo attack is a method that submarine attack only based on the change of target bearing. The hitting probability of torpedo is an important content of weapon research and operational use,and it is also a necessary basis of the torpedo operational effectiveness. Through the analysis of process of bearing-only torpedo attack,the mathematical simulation model is built up, performing the large sample simulation,the optimal solutions of torpedo attack angle in advance in different conditions could be taken out.%鱼雷纯方位攻击是潜艇因无法解算目标运动要素时,依靠方位变化对目标实施快速鱼雷攻击的一种方法。鱼雷命中概率是武器装备研究和作战使用研究的重要内容,也是鱼雷武器作战效能评估的主要依据。通过分析自导鱼雷纯方位攻击的使用过程,建立了相应的数学和仿真模型,并采用大样本仿真的方法,得出不同情况下鱼雷攻击提前角的最优解。

  11. A modification to linearized theory for prediction of pressure loadings on lifting surfaces at high supersonic Mach numbers and large angles of attack

    Science.gov (United States)

    Carlson, H. W.

    1979-01-01

    A new linearized-theory pressure-coefficient formulation was studied. The new formulation is intended to provide more accurate estimates of detailed pressure loadings for improved stability analysis and for analysis of critical structural design conditions. The approach is based on the use of oblique-shock and Prandtl-Meyer expansion relationships for accurate representation of the variation of pressures with surface slopes in two-dimensional flow and linearized-theory perturbation velocities for evaluation of local three-dimensional aerodynamic interference effects. The applicability and limitations of the modification to linearized theory are illustrated through comparisons with experimental pressure distributions for delta wings covering a Mach number range from 1.45 to 4.60 and angles of attack from 0 to 25 degrees.

  12. An experimental investigation of thrust vectoring two-dimensional convergent-divergent nozzles installed in a twin-engine fighter model at high angles of attack

    Science.gov (United States)

    Capone, Francis J.; Mason, Mary L.; Leavitt, Laurence D.

    1990-01-01

    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine thrust vectoring capability of subscale 2-D convergent-divergent exhaust nozzles installed on a twin engine general research fighter model. Pitch thrust vectoring was accomplished by downward rotation of nozzle upper and lower flaps. The effects of nozzle sidewall cutback were studied for both unvectored and pitch vectored nozzles. A single cutback sidewall was employed for yaw thrust vectoring. This investigation was conducted at Mach numbers ranging from 0 to 1.20 and at angles of attack from -2 to 35 deg. High pressure air was used to simulate jet exhaust and provide values of nozzle pressure ratio up to 9.

  13. Experimental Evaluation of the Effect of Angle-of-attack on the External Aerodynamics and Mass Capture of a Symmetric Three-engine Air-breathing Launch Vehicle Configuration at Supersonic Speeds

    Science.gov (United States)

    Kim, Hyun D.; Frate, Franco C.

    2001-01-01

    A subscale aerodynamic model of the GTX air-breathing launch vehicle was tested at NASA Glenn Research Center's 10- by 10-Foot Supersonic Wind Tunnel from Mach 2.0 to 3.5 at various angles-of-attack. The objective of the test was to investigate the effect of angle-of-attack on inlet mass capture, inlet diverter effectiveness, and the flowfield at the cowl lip plane. The flow-through inlets were tested with and without boundary-layer diverters. Quantitative measurements such as inlet mass flow rates and pitot-pressure distributions in the cowl lip plane are presented. At a 3deg angle-of-attack, the flow rates for the top and side inlets were within 8 percent of the zero angle-of-attack value, and little distortion was evident at the cowl lip plane. Surface oil flow patterns showing the shock/boundary-layer interaction caused by the inlet spikes are shown. In addition to inlet data, vehicle forebody static pressure distributions, boundary-layer profiles, and temperature-sensitive paint images to evaluate the boundary-layer transition are presented. Three-dimensional parabolized Navier-Stokes computational fluid dynamics calculations of the forebody flowfield are presented and show good agreement with the experimental static pressure distributions and boundary-layer profiles. With the boundary-layer diverters installed, no adverse aerodynamic phenomena were found that would prevent the inlets from operating at the required angles-of-attack. We recommend that phase 2 of the test program be initiated, where inlet contraction ratio and diverter geometry variations will be tested.

  14. Nomogram for correcting drag and angle of attack of an airfoil model in an air stream of finite diameter

    Science.gov (United States)

    1924-01-01

    In experimenting with airfoil models in a wind tunnel, the magnitude of the forces acting on the model is affected by the fact that the air stream in which the model is suspended, has a restricted cross-section. In order to utilize the results for an airplane in an unlimited quantity of air, a correction must be made. The magnitude of this correction was determined by Prandtl by the application of his wing theory.

  15. Influence of wind angle of attack and isotropic turbulence on wind-induced vibrations of ice-accreted bridge cables

    OpenAIRE

    Pospíšil, S.; Trush, A. (Arsenii); Kuznetsov, S. (Sergeii); Kozmar, H.; Náprstek, J. (Jiří)

    2016-01-01

    Bridge-supporting cables and mast guys with high flexibility and low damping often experience vibrations with large amplitudes that may have consequently destructive effects on supported structures. Surface roughness and ice accretion are important issues, as they can considerably alter aerodynamic characteristics of bridge cables. This study describes wind-tunnel experiments on vortex-induced vibration of cylindrical section models with the deliberately adjusted natural frequency f = 5 Hz. T...

  16. Investigation of normal force and moment coefficients for an AUV at nonlinear angle of attack and sideslip range

    Digital Repository Service at National Institute of Oceanography (India)

    Barros, E.A. de; Dantas, J.L.D.; Pascoal, A.M.; Desa, E.S.

    and calculate the pressure distribu- tion acting upon a submerged vehicle, from which the resulting forces and moments of interest acting on it can be calculated. Manuscript received December 21, 2007; revised June 09, 2008; accepted August 11, 2008. Current... chosen for calculations and experimental validation. This geometry was adopted for vehicles such as Remus [18] and the MAYA AUV. This paper is organized as follows. Section II presents the adopted methodology for CFD simulation, and the estimated pressure...

  17. Signs of a Heart Attack

    Science.gov (United States)

    ... attack Heart Health and Stroke Signs of a heart attack Related information Make the Call. Don't Miss ... to top More information on Signs of a heart attack Read more from womenshealth.gov Make the Call, ...

  18. 攻角对一种深水炸弹入水散布特性的影响%Analysis on Attack Angle Impacted Dispersion Characteristic of Depth Charge Water Entry

    Institute of Scientific and Technical Information of China (English)

    张世林; 阮晓亮

    2014-01-01

    研究攻角对深水炸弹入水后的散布特性影响,针对一种新型深水炸弹总体外形,通过试验分析了不同攻角下入水时的弹着点散布状态,试验结果表明:随着攻角的增加,落点散布有增大的趋势,随着水深的增加,落点散布增加,而增加的趋势逐渐减小;深水炸弹的质量偏心对落点的分布有着很大影响。%To research how attack angle impacted dispersion characteristic of depth charge after water en-try,the depth charge with a new general shape has been taken into experiment to research and record its points of impact when water entry with different attack angle. Research results show that:impact disper-sion increases as the increasing of attack angle;when water depth increases impact dispersion also increa-ses,but the trend is decreasing gradually;mass eccentricity of depth charge has great influence on impact dispersion.

  19. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    OpenAIRE

    Yi-Hsun Wang; Ching-Hao Mao; Hahn-Ming Lee

    2010-01-01

    Web applications suffer from cross-site scripting (XSS) attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of...

  20. 无尾布局嵌入式舵面的大迎角纵向操纵能力研究%Longitudinal Control Ability Investigation of Lower Surface Spoiler for Blended Wing Body Tailless Configuration at High Angles of Attack

    Institute of Scientific and Technical Information of China (English)

    孙静; 张彬乾; 杨广珺

    2012-01-01

    Based on the platform of blended wing body tailless configuration, to solve the problem of decreasing pitching control efficiency at high angles of attack for basic longitudinal control surfaces including canard elevator and tail elevator, the new concept of lower surface spoiler is put forward and the effectiveness and auxiliary function for pitching control at high angles of attack is analyzed with numerical simulation method. The influences of the parameters such as lower surface spoiler's height, deflection angle, and relative position when combined with tail elevator are studied. The design law, flow mechanism and action principle to afford nose-down pitching moment increment are put forward. The results show that lower surface spoiler can support tailless configuration as a high-efficiency longitudinal control effecter. With the single use of lower surface spoiler, the maximal nose down pitching moment can be obtained to balance 10° angle of attack with little effect on lift and drag characteristics. When combined with the tail elevator, nose down moment increment ofangle of attack can be obtained with the angles of attack smaller than 32' and favorable effect on lift-drag performance is produced. The longitudinal control ability at high angles of attack is improved. The design developed in this paper can provide a reference for control surface design for blended wing body tailless configuration.%针对某前掠翼翼身融合无尾布局由鸭面与尾舵组成的纵向基本控制舵面在大迎角状态操纵效率降低的问题,采用数值模拟方法研究一种机身下表面嵌入式新概念纵向操纵舵面实施大迎角纵向操纵补充的可行性.提出了嵌入式舵面的设计思想,研究了嵌入式舵面高度、偏度及其与尾舵组合时的相对位置等参数影响,提出了嵌入式舵面的设计原则、流动机理以及提供低头力矩增量的作用原理.研究结果表明:嵌入式舵面是无尾布局飞机大

  1. Virtual Test for the Effect of Rear Wing Attack Angle on the Performance of Formula SAE Car%尾翼攻角变化对方程式赛车性能影响的虚拟试验

    Institute of Scientific and Technical Information of China (English)

    倪俊; 吴志成; 陈思忠

    2012-01-01

    In order to compare the performance of Formula SAE car with different rear wing attack angles, the virtual prototype model of a certain Formula SAE car was built by ADAMS with considering the nonlinear factors and aerodynamics characteristics. By comparison with actual test data, the correctness of the virtual prototype model was verified. Based on these, a feasible method was proposed which can take the aerodynamics characteristics of the rear wing into simulation. The comparison among different rear wing attack angles was performed according to the lift and drag characteristics of the rear wing. The results show that the increase of the attack angle has a little effect on acceleration performance. Besides, the transient performance and the crosswind stability are improved with the increase of attack angle, but the tendency to understeer is aggravated.%为对比方程式赛车尾翼攻角不同时的性能.应用ADAMS建立了某方程式赛车的虚拟样机模型,并考虑了非线性因素及空气动力特性.通过与实车试验结果的对比,验证了虚拟样机模型的准确性.在此基础上,提出了一种切实可行的方法在仿真中计入了尾翼的空气动力特性.并根据不同攻角时的尾翼升阻特性,对尾翼攻角不同时的各项性能进行了对比.对比结果表明,攻角的增大对赛车的直线加速性能影响很小,提高了赛车的瞬态响应性能和侧风稳定性,但加重了赛车的不足转向特性.

  2. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    Directory of Open Access Journals (Sweden)

    Yi-Hsun Wang

    2010-09-01

    Full Text Available Web applications suffer from cross-site scripting (XSS attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of generating mutated XSS attacks in a fully automatic way. Mutated XSS attack generation depends on the analysis of attack vectors and the structural learning mechanism. For the kernel of the learning mechanism, we use a Hidden Markov model (HMM as the structure of the attack vector model to capture the implicit manner of the attack vector, and this manner is benefited from the syntax meanings that are labeled by the proposed tokenizing mechanism. Bayes theorem is used to determine the number of hidden states in the model for generalizing the structure model. The paper has the contributions as following: (1 automatically learn the structure of attack vectors from practical data analysis to modeling a structure model of attack vectors, (2 mimic the manners and the elements of attack vectors to extend the ability of testing tool for identifying XSS vulnerabilities, (3 be helpful to verify the flaws of blacklist sanitization procedures of Web applications. We evaluated the proposed mechanism by Burp Intruder with a dataset collected from public XSS archives. The results show that mutated XSS attack generation can identify potential vulnerabilities.

  3. Structural Learning of Attack Vectors for Generating Mutated XSS Attacks

    CERN Document Server

    Wang, Yi-Hsun; Lee, Hahn-Ming; 10.4204/EPTCS.35.2

    2010-01-01

    Web applications suffer from cross-site scripting (XSS) attacks that resulting from incomplete or incorrect input sanitization. Learning the structure of attack vectors could enrich the variety of manifestations in generated XSS attacks. In this study, we focus on generating more threatening XSS attacks for the state-of-the-art detection approaches that can find potential XSS vulnerabilities in Web applications, and propose a mechanism for structural learning of attack vectors with the aim of generating mutated XSS attacks in a fully automatic way. Mutated XSS attack generation depends on the analysis of attack vectors and the structural learning mechanism. For the kernel of the learning mechanism, we use a Hidden Markov model (HMM) as the structure of the attack vector model to capture the implicit manner of the attack vector, and this manner is benefited from the syntax meanings that are labeled by the proposed tokenizing mechanism. Bayes theorem is used to determine the number of hidden states in the model...

  4. The Timing of Terrorist Attacks

    DEFF Research Database (Denmark)

    Jensen, Thomas

    2016-01-01

    I use a simple optimal stopping model to derive policy relevant insights on the timing of one-shot attacks by small autonomous terrorist units or “lone wolf” individuals. A main insight is that an increase in proactive counterterrorism measures can lead to a short term increase in the number...... of attempted terrorist attacks because it makes it more risky for existing terrorist units to pursue further development of capabilities. This is consistent with the events in London in 2005 where a terrorist attack on 7 July was followed by a similar but unsuccessful attack two weeks later....

  5. Energy harvesting performance of an oscillatory foil with elliptic sine attack angle%基于椭圆正弦攻角运动振动翼的能量采集性能分析

    Institute of Scientific and Technical Information of China (English)

    徐文华; 许国冬; 张庆力

    2015-01-01

    振动翼作为一种有效的潮流能、风能换能装置,可将潮流或风的动能转化为机械动能推动电机发电。该文通过调整机翼的周期性垂向运动与旋转运动实现机翼与来流的有效攻角控制,来流对机翼的流体动升力可推动机械装置往复运动并转换为电机的转动。假定机翼表面的边界层极薄,黏性仅在边界层内部作用,泻出涡仅从机翼的尾缘处泻出,引入势流理论,采用边界元法与泻出涡模型模拟机翼边界层的外部流场。主要分析了机翼以椭圆正弦为有效攻角运动的振动运动的能量采集性能,计算NACA0012机翼在不同运动频率、振动幅值与有效攻角时的能量采集效率,并分析了椭圆正弦K 参数对能量采集的影响,研究实现高效率能量采集的机理。%Oscillatory foil is an effective energy harvesting device to extract energy from incoming flow, including current and wind. By adjusting the periodical vertical and rotational motion, the effective attack angle can be controlled;and the fluid loads can be utilized to drive the reciprocating motion of mechanical device. Assuming that the boundary layer is thin and the viscosity only has effects within the layer, the velocity potential is introduced to simulate the outer fluid flow through boundary element method and vortex shedding scheme. The energy harvesting performance of NACA0012 foil in oscillatory motion, where the effective attack angle is elliptic sine function, is analyzed. The energy extraction efficiency at various heave amplitude, the effective attack angle and Strouhal number is calculated, the effects of K parameter on the energy efficiency have been analyzed;the mechanics to achieve high efficiency is investigated.

  6. Decoupling Design for High Angle-of-Attack Missile Based on Neural Network and Dynamic Inversion%基于神经网络动态逆的大攻角导弹解耦设计

    Institute of Scientific and Technical Information of China (English)

    罗绪涛; 梁晓庚; 杨军; 贾杰

    2011-01-01

    The strong coupling between channels and non-linear characteristics is lead by asymmetric vortex and vortex breakdown phenomenon under the hign angle of the air to air missile. In order to decoupling the nonlinear of the system, decoupling design for high angle - of-attack missile based on neural network and dynamic inversion is presented, the nonlinear dynamic inverse system is designed, and the RBF neural network approximation inversion error is developed. At last, the simulation experimental results show that the performance of decoupling and command tracking by this designed control system is quite good.%空空导弹大攻角飞行时,由于出现非对称涡及涡破裂现象,导致强烈的通道间耦合并呈现非线性特性;为提高系统控制品质,实现通道间解耦,文中基于非线性动态逆系统原理,利用了RBF神经网络逼近逆误差,构造了基于神经网络动态逆的大攻角导弹解耦控制器;最后,对控制系统进行了仿真分析,实验结果表明了该方法的可行性.

  7. Perception of perspective angles

    NARCIS (Netherlands)

    Erkelens, C.J.

    2015-01-01

    We perceive perspective angles, that is, angles that have an orientation in depth, differently from what they are in physical space. Extreme examples are angles between rails of a railway line or between lane dividers of a long and straight road. In this study, subjects judged perspective angles bet

  8. The numerical simulation of separated flow at large attack angles for a wind turbine airfoil%风力机翼型大攻角分离流的数值模拟

    Institute of Scientific and Technical Information of China (English)

    王文龙; 何斌; 傅洁; 范钦珊

    2012-01-01

    为了准确预测风力机翼型在大攻角下分离流动的气动性能,并且为风力机的设计与安全运行提供一种可靠的数值模拟手段,针对某风力机专用翼型,分别采用基于非定常不可压缩Navier-Stokes方程的大涡模拟(LES)模型、RNG κ-ε模型和Standard κ-ε模型对其气动性能进行数值模拟,并计算出翼型攻角为35 ~90°,雷诺数为2×106时的气动力参数.将不同湍流模型的计算结果与风洞试验数据进行比较,并分析流场结构.分析结果表明,LES模型能够准确地模拟出翼型表面的分离流动,计算结果与试验数据取得了很好的一致性,并且优于RNG κ-ε模型和Standard κ-ε模型的模拟结果.%In order to accurately predict the aerodynamic performance of the separated flows of a wind turbine airfoil at large attack angles and provide a reliable numerical simulation method for the design and safe operation of the wind turbine, aiming at a certain type of wind turbine airfoil, an aerodynamic performance was numerically simulated by using LES model, RNG k-e model and Standard k-e model based on unsteady incompressible Navier-Stokes equations respectively, and the aerodynamic parameters at various attack angles ranging from 35 ° to 90 ° was calculated when the Reynolds number is 2×l06. By comparing the calculation results of the different turbulence models with wind tunnel test data and analyzing the flow field, it is shown that LES model can accurately simulate the separation of the airfoil surface flows, and its calculated results, which are better than RNG k -s model's and Standard k -e model's, agree well with the experimental data.

  9. 不同攻角下AUV回收过程中的水动力规律%Research on the Law of the Hydrodynamic During AUV Recovery under Different Angle of Attack

    Institute of Scientific and Technical Information of China (English)

    潘光; 王培; 杜晓旭

    2012-01-01

    通过对AUV(Autonomous Underwater Vehicle)回收过程中运动规律的研究和对纳维—斯托克斯方程(Navier-Stokes equations)及其求解方法的分析,基于CFD(Computational Fluid Dynamics)理论建立了AUV回收运动的三维计算模型,并使用CFD软件完成其物理模型的建立、网格的划分及求解设置.在此基础上对AUV回收过程中的阻力、升力干扰进行分析计算,得到不同攻角下AUV所受到的水动力干扰与AUV和回收平台之间距离的相互联系.%By studying the law of motion of AUV recovery process and analyzing Navier-Stokes equations (Navier-Stokes equations) and its solution.the three-dimensional model of the AUV recovery movement is established based on CFD Theory,and then CFD software is used to finish the build of the physical model,the partition of the mesh and solution set. On this basis, drag and lift interference have been calculated in the process of the AUV recovery. The relationship between AUV hydrodynamic interference suffered by different angle of attack and the distance between recovery platform and AUV is obtained.

  10. Some Aspects of the Modified Newtonian and Prandtl-Meyer-Expansion Method for Axisymmetric Blunt Bodies at Zero Angle of Attack

    Science.gov (United States)

    Wagner, Richard D., Jr.

    1959-01-01

    In a recent article on hypersonic flow, Lees and Kubota suggested a modification of the local-expansion method to predict the surface pressures in the region of a nose-cylinder junction where Newtonian theory fails. The modification consists of matching the Newtonian pressure distribution and the Prandtl-Meyer relation at the point on the nose surface where both the pressure and the pressure gradient, predicted by these two solution, are equal. With this approximation, the pressure distribution can be predicted quite accurately up to the nose-cylinder junction for blunt-nosed bodies of continuous curvature, provided centrifugal-force effects are negligible. The purpose of this note is to facilitate the application of Lees' suggestion and to draw attention to some of its consequences.

  11. Analytical Characterization of Internet Security Attacks

    Science.gov (United States)

    Sellke, Sarah H.

    2010-01-01

    Internet security attacks have drawn significant attention due to their enormously adverse impact. These attacks includes Malware (Viruses, Worms, Trojan Horse), Denial of Service, Packet Sniffer, and Password Attacks. There is an increasing need to provide adequate defense mechanisms against these attacks. My thesis proposal deals with analytical…

  12. Wind tunnel research concerning lateral control devices, particularly at high angles of attack VII : Handley Page tip and full-span slots with ailerons and spoilers

    Science.gov (United States)

    Weick, Fred E; Wenzinger, Carl J

    1933-01-01

    Tests were made with ordinary ailerons and different sizes of spoilers on rectangular Clark Y wing models with Handley Page tip and full span slots. The tests showed the effect of the control devices on the general performance of the wings as well as on the lateral control and lateral stability characteristics.

  13. [Polygraphy of a panic attack].

    Science.gov (United States)

    Noffke, H U; Roser, M

    2001-09-01

    We studied a 24-year old female patient with Type 1 diabetes mellitus suffering for 4 weeks from a major depressive episode combined with panic disorder without agoraphobia. A spontaneous panic attack was serendipitously recorded by polygraph while the subject was at rest. Electrocardiogram, finger blood-flow, respiratory rhythm and muscle tone (forearm, forehead) were recorded. A triphasic course consisting of a "dynamic phase" (appr. 80 s) preceded by a discrete "initial phase" (appr. 140 s) and a "declining phase" (appr. 180 s) was observed. The dynamic phase is characterized by an acute increase of fingertip vasoconstriction and heart rate. The patient was not aware of the panic attack before the dynamic phase. The recognisable central regulation confirms previously published findings indicating a sympathetic-norepinephrine activation at the beginning of the panic attack without activating the musculoskeletal system. Furthermore, a paradoxical phenomenon involving heart and respiratory rate was observed before the onset of anxiety, i.e. an increase of the heart rate and a simultaneous decline of the respiratory rate, suggesting a non-antagonistic regulation of the ergotropic-trophotropic system. The autonomic state of the patient points to a lability in homeostasis from which panic attacks as a form of CNS response could develop. PMID:11572106

  14. Automated Generation of Attack Trees

    DEFF Research Database (Denmark)

    Vigo, Roberto; Nielson, Flemming; Nielson, Hanne Riis

    2014-01-01

    are automatically inferred from a process algebraic specification in a syntax-directed fashion, encompassing a great many application domains and avoiding incurring systematically an exponential explosion. Moreover, we show how the standard propositional denotation of an attack tree can be used to phrase...

  15. Detection of complex cyber attacks

    Science.gov (United States)

    Gregorio-de Souza, Ian; Berk, Vincent H.; Giani, Annarita; Bakos, George; Bates, Marion; Cybenko, George; Madory, Doug

    2006-05-01

    One significant drawback to currently available security products is their inabilty to correlate diverse sensor input. For instance, by only using network intrusion detection data, a root kit installed through a weak username-password combination may go unnoticed. Similarly, an administrator may never make the link between deteriorating response times from the database server and an attacker exfiltrating trusted data, if these facts aren't presented together. Current Security Information Management Systems (SIMS) can collect and represent diverse data but lack sufficient correlation algorithms. By using a Process Query System, we were able to quickly bring together data flowing from many sources, including NIDS, HIDS, server logs, CPU load and memory usage, etc. We constructed PQS models that describe dynamic behavior of complicated attacks and failures, allowing us to detect and differentiate simultaneous sophisticated attacks on a target network. In this paper, we discuss the benefits of implementing such a multistage cyber attack detection system using PQS. We focus on how data from multiple sources can be combined and used to detect and track comprehensive network security events that go unnoticed using conventional tools.

  16. Performance of attack strategies on modular networks

    CERN Document Server

    da Cunha, Bruno Requião

    2016-01-01

    Vulnerabilities of complex networks have became a trend topic in complex systems recently due to its real world applications. Most real networks tend to be very fragile to high betweenness adaptive attacks. However, recent contributions have shown the importance of interconnected nodes in the integrity of networks and module-based attacks have appeared promising when compared to traditional malicious non-adaptive attacks. In the present work we deeply explore the trade-off associated with attack procedures, introducing a generalized robustness measure and presenting an attack performance index that takes into account both robustness of the network against the attack and the run-time needed to obtained the list of targeted nodes for the attack. Besides, we introduce the concept of deactivation point aimed to mark the point at which the network stops to function properly. We then show empirically that non-adaptive module-based attacks perform better than high degree and betweenness adaptive attacks in networks ...

  17. Perfection of Recent Attacks using IP

    Directory of Open Access Journals (Sweden)

    A. RENGARAJAN

    2012-02-01

    Full Text Available The Internet threat monitoring (ITM systems have been deployed to detect widespread attacks on the Internet in recent years. However, the effectiveness of ITM systems critically depends on the confidentiality of the location of their monitors. If adversaries learn the monitor locations of an ITM system, they can bypass the monitors and focus on the uncovered IP address space without being detected. In this paper, we study a new class of attacks, the invisible LOCalization (iLOC attack. The iLOC attack can accurately and invisibly localize monitors of ITM systems. In the iLOC attack, the attacker launches low-rate port-scan traffic, encoded with a selected pseudo noise code (PN-code, to targeted networks. While the secret PN-code is invisible to others, the attacker can accurately determine the existence of monitors in the targeted networks based on whether the PN-code is embedded in the report data queried from the data center of the ITM system. We formally analyze the impact of various parameters on attack effectiveness. We implement the iLOC attack and conduct the performance evaluation on a real-world ITM system to demonstrate the possibility of such attacks. We also conduct extensive simulations on the iLOC attack using real-world traces. Our data show that the iLOC attack can accurately identify monitors while being invisible to ITM systems. Finally, we present a set of guidelines to counteract the iLOC attack.

  18. Biomechanics of knife stab attacks.

    Science.gov (United States)

    Chadwick, E K; Nicol, A C; Lane, J V; Gray, T G

    1999-10-25

    Equipment, materials and methods for the measurement of the biomechanical parameters governing knife stab attacks have been developed and data have been presented that are relevant to the improvement of standards for the testing of stab-resistant materials. A six-camera Vicon motion analysis system was used to measure velocity, and derive energy and momentum during the approach phase of the attack and a specially developed force-measuring knife was used to measure three-dimensional forces and torque during the impact phase. The body segments associated with the knife were modelled as a series of rigid segments: trunk, upper arm, forearm and hand. The velocities of these segments, together with knowledge of the mass distribution from biomechanical tables, allowed the calculation of the individual segment energy and momentum values. The instrumented knife measured four components of load: axial force (along the length of the blade), cutting force (parallel to the breadth of the blade), lateral force (across the blade) and torque (twisting action) using foil strain gauges. Twenty volunteers were asked to stab a target with near maximal effort. Three styles of stab were used: a short thrust forward, a horizontal style sweep around the body and an overhand stab. These styles were chosen based on reported incidents, providing more realistic data than had previously existed. The 95th percentile values for axial force and energy were 1885 N and 69 J, respectively. The ability of current test methods to reproduce the mechanical parameters measured in human stab attacks has been assessed. It was found that current test methods could reproduce the range of energy and force values measured in the human stab attacks, although the simulation was not accurate in some respects. Non-axial force and torque values were also found to be significant in the human tests, but these are not reproduced in the standard mechanical tests.

  19. Stochastic Model of TCP SYN Attacks

    Directory of Open Access Journals (Sweden)

    Simona Ramanauskaitė

    2011-08-01

    Full Text Available A great proportion of essential services are moving into internet space making the threat of DoS attacks even more actual. To estimate the real risk of some kind of denial of service (DoS attack in real world is difficult, but mathematical and software models make this task easier. In this paper we overview the ways of implementing DoS attack models and offer a stochastic model of SYN flooding attack. It allows evaluating the potential threat of SYN flooding attacks, taking into account both the legitimate system flow as well as the possible attack power. At the same time we can assess the effect of such parameters as buffer capacity, open connection storage in the buffer or filte­ring efficiency on the success of different SYN flooding attacks. This model can be used for other type of memory depletion denial of service attacks.Article in Lithuanian

  20. Diabetes Ups Risk of Heart Attack Death

    Science.gov (United States)

    ... 159557.html Diabetes Ups Risk of Heart Attack Death Study points to need for better coordinated care, ... people with diabetes have a higher risk of death after a heart attack. "We knew that following ...

  1. On Mitigating Distributed Denial of Service Attacks

    Science.gov (United States)

    Gao, Zhiqiang

    2006-01-01

    Denial of service (DoS) attacks and distributed denial of service (DDoS) attacks are probably the most ferocious threats in the Internet, resulting in tremendous economic and social implications/impacts on our daily lives that are increasingly depending on the well-being of the Internet. How to mitigate these attacks effectively and efficiently…

  2. Influence of Wind Attacking Angle on Aerodynamic Characteristic of Rectangular Girder with Aspect Ratio 5%风攻角对宽高比为5的矩形断面梁气动力特性的影响

    Institute of Scientific and Technical Information of China (English)

    杨群; 刘小兵

    2015-01-01

    针对宽高比为5的矩形断面梁进行了节段模型测压风洞试验,研究了矩形断面梁的气动力特性随风攻角的变化规律。研究结果表明:在0°~6°的风攻角范围内,风攻角对斯托罗哈数的影响很小;不同风攻角下的驰振力系数均大于0;与上表面中间位置的测点相比,上表面边缘位置测点的压力与升力和扭矩的相关性更强;上表面边缘位置测点的压力与升力和扭矩的相关性对风攻角的变化不敏感;随着风攻角的增大,上表面中间位置测点的压力与升力和扭矩的相关性显著增强。%A pressure-measured sectional model wind tunnel test of rectangular girder with aspect ratio 5 was performed.The changing rule of aerodynamic characteristic of rectangular girder versus wind attacking angle was studied.The study results show that when wind attacking angle is in range of 0°~6°, the change of wind attac-king angle has little effect on Strouhal number.The galloping force coefficients under different wind attacking an-gles are greater than zero.Compared with point-pressure in center of upper surface, point-pressure in the edge of upper surface is more correlated with lift force and torque.With the increase of the wind attacking angle, the correlation of point-pressure in edge of upper surface with lift force and torque changes little, while correlation of point-pressure in center of upper surface with lift force and torque increases dramatically.

  3. Detection of Denial-of-service Attacks

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Denial-of-service (DOS) is a type of computer attack, which can essentially disable computers and networks.Resource consumption type of DOS attack could not be detected by the traditional misuse detection technique. This paper presents a new method of support vector mchine (SVM) to detect these attacks. We find that a DOS attack to a host is related to the activities within an impact data set of the host. The SVM method is used to classify the subsets of an impact data set to estimate its anomalism. The experiment result shows that this method can detect resource consumption type of DOS attacks, such as SYNflood, Smurf and UDP-storm. A receiver operating characteristic curve is plotted to determine performance for any possible operating point of the DOS attacks detection.

  4. What Are the Symptoms of a Heart Attack?

    Science.gov (United States)

    ... on Twitter. What Are the Symptoms of a Heart Attack? Not all heart attacks begin with the sudden, ... This Content: NEXT >> Featured Video What is a heart attack? 05/22/2014 Describes how a heart attack ...

  5. Percolation of localized attack on complex networks

    CERN Document Server

    Shao, Shuai; Stanley, H Eugene; Havlin, Shlomo

    2014-01-01

    The robustness of complex networks against node failure and malicious attack has been of interest for decades, while most of the research has focused on random attack or hub-targeted attack. In many real-world scenarios, however, attacks are neither random nor hub-targeted, but localized, where a group of neighboring nodes in a network are attacked and fail. In this paper we develop a percolation framework to analytically and numerically study the robustness of complex networks against such localized attack. In particular, we investigate this robustness in Erd\\H{o}s-R\\'{e}nyi networks, random-regular networks, and scale-free networks. Our results provide insight into how to better protect networks, enhance cybersecurity, and facilitate the design of more robust infrastructures.

  6. Evaluation of Hypervisor Stability towards Insider Attacks

    Institute of Scientific and Technical Information of China (English)

    Roman Kulikov; Svetlana Kolesnikova

    2016-01-01

    Virtualization technology plays a key role in cloud computing. Thus, the security issues of virtualization tools (hypervisors, emulators, etc.) should be under precise consideration. However, threats of insider attacks are underestimated. The virtualization tools and hypervisors have been poorly protected from this type of attacks. Furthermore, hypervisor is one of the most critical elements in cloud computing infrastructure. Firstly, hypervisor vulnerabilities analysis is provided. Secondly, a formal model of insider attack on hypervisor is developed. Consequently, on the basis of the formal attack model, we propose a new methodology of hypervisor stability evaluation. In this paper, certain security countermeasures are considered that should be integrated in hypervisor software architecture.

  7. Use of Attack Graphs in Security Systems

    Directory of Open Access Journals (Sweden)

    Vivek Shandilya

    2014-01-01

    Full Text Available Attack graphs have been used to model the vulnerabilities of the systems and their potential exploits. The successful exploits leading to the partial/total failure of the systems are subject of keen security interest. Considerable effort has been expended in exhaustive modeling, analyses, detection, and mitigation of attacks. One prominent methodology involves constructing attack graphs of the pertinent system for analysis and response strategies. This not only gives the simplified representation of the system, but also allows prioritizing the security properties whose violations are of greater concern, for both detection and repair. We present a survey and critical study of state-of-the-art technologies in attack graph generation and use in security system. Based on our research, we identify the potential, challenges, and direction of the current research in using attack graphs.

  8. Evaluating Deterioration of Concrete by Sulfate Attack

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Effects of factors such as water to cement ratio, fly ash and silica fume on the resistance of concrete to sulfate attack were investigated by dry-wet cycles and immersion method. The index of the resistance to sulfate attack was used to evaluate the deterioration degree of concrete damaged by sulfate. The relationship between the resistance of concrete to sulfate attack and its permeability/porosity were analyzed as well as its responding mechanism. Results show that the depth of sulfate crystal attack from surface to inner of concrete can be reduced by decreasing w/c and addition of combining fly ash with silica fume. The variation of relative elastic modulus ratio and relative flexural strength ratio of various specimens before and after being subjected to sulfate attack was compared.

  9. Spatially localized attacks on interdependent networks: the existence of a finite critical attack size

    CERN Document Server

    Berezin, Yehiel; Danziger, Michael M; Li, Daqing; Havlin, Shlomo

    2013-01-01

    Many real world complex systems such as infrastructure, communication and transportation networks are embedded in space, where entities of one system may depend on entities of other systems. These systems are subject to geographically localized failures due to malicious attacks or natural disasters. Here we study the resilience of a system composed of two interdependent spatially embedded networks to localized geographical attacks. We find that if an attack is larger than a finite (zero fraction of the system) critical size, it will spread through the entire system and lead to its complete collapse. If the attack is below the critical size, it will remain localized. In contrast, under random attack a finite fraction of the system needs to be removed to initiate system collapse. We present both numerical simulations and a theoretical approach to analyze and predict the effect of local attacks and the critical attack size. Our results demonstrate the high risk of local attacks on interdependent spatially embedd...

  10. Automatic Classification of Attacks on IP Telephony

    Directory of Open Access Journals (Sweden)

    Jakub Safarik

    2013-01-01

    Full Text Available This article proposes an algorithm for automatic analysis of attack data in IP telephony network with a neural network. Data for the analysis is gathered from variable monitoring application running in the network. These monitoring systems are a typical part of nowadays network. Information from them is usually used after attack. It is possible to use an automatic classification of IP telephony attacks for nearly real-time classification and counter attack or mitigation of potential attacks. The classification use proposed neural network, and the article covers design of a neural network and its practical implementation. It contains also methods for neural network learning and data gathering functions from honeypot application.

  11. SURVEY OF PACKET DROPPING ATTACK IN MANET

    Directory of Open Access Journals (Sweden)

    A.Janani

    2014-03-01

    Full Text Available Mobile Ad-hoc NETwork (MANET is an application of wireless network with self-configuring mobile nodes. MANET does not require any fixed infrastructure. Its development never has any threshold range. Nodes in MANET can communicate with each other if and only if all the nodes are in the same range. This wide distribution of nodes makes MANET vulnerable to various attacks, packet dropping attack or black hole attack is one of the possible attack. It is very hard to detect and prevent. To prevent from packet dropping attack, detection of misbehavior links and selfish nodes plays a vital role in MANETs. In this paper, a omprehensive investigation on detection of misbehavior links and malicious nodes is carried out.

  12. Situational awareness of a coordinated cyber attack

    Science.gov (United States)

    Sudit, Moises; Stotz, Adam; Holender, Michael

    2005-03-01

    As technology continues to advance, services and capabilities become computerized, and an ever increasing amount of business is conducted electronically the threat of cyber attacks gets compounded by the complexity of such attacks and the criticality of the information which must be secured. A new age of virtual warfare has dawned in which seconds can differentiate between the protection of vital information and/or services and a malicious attacker attaining their goal. In this paper we present a novel approach in the real-time detection of multistage coordinated cyber attacks and the promising initial testing results we have obtained. We introduce INFERD (INformation Fusion Engine for Real-time Decision-making), an adaptable information fusion engine which performs fusion at levels zero, one, and two to provide real-time situational assessment and its application to the cyber domain in the ECCARS (Event Correlation for Cyber Attack Recognition System) system. The advantages to our approach are fourfold: (1) The complexity of the attacks which we consider, (2) the level of abstraction in which the analyst interacts with the attack scenarios, (3) the speed at which the information fusion is presented and performed, and (4) our disregard for ad-hoc rules or a priori parameters.

  13. Forensics Investigation of Web Application Security Attacks

    Directory of Open Access Journals (Sweden)

    Amor Lazzez

    2015-02-01

    Full Text Available Nowadays, web applications are popular targets for security attackers. Using specific security mechanisms, we can prevent or detect a security attack on a web application, but we cannot find out the criminal who has carried out the security attack. Being unable to trace back an attack, encourages hackers to launch new attacks on the same system. Web application forensics aims to trace back and attribute a web application security attack to its originator. This may significantly reduce the security attacks targeting a web application every day, and hence improve its security. The aim of this paper is to carry out a detailed overview about the web application forensics. First, we define the web applications forensics, and we present a taxonomic structure of the digital forensics. Then, we present the methodology of a web application forensics investigation. After that, we illustrate the forensics supportive tools for a web application forensics investigation. After that, we present a detailed presentation of a set of the main considered web application forensics tools. Finally, we provide a comparison of the main considered web application forensics tools.

  14. Research on First Attack Probability Model of an Attacker Level Bombing Anti-air Radars

    Institute of Scientific and Technical Information of China (English)

    LUO Peng-cheng; MU Fu-ling; ZHOU Jing-lun

    2007-01-01

    The paper mainly studies the first attack probability (FAP) of an attacker level bombing anti-air radars through analyzing the radiant point orientation and attack (RPOA) process of attackers. Firstly, the searching target process is analyzed, and a corresponding target finding model is brought forward. Secondly, the target approaching process is concretely analyzed when the attacker levelly bombs the anti-air radar, and a corresponding target approaching model is presented. Finally, a demonstration is given to analyze the major factors in the model and prove its validity.

  15. Logical Modes of Attack in Argumentation Networks

    OpenAIRE

    Gabbay, Dov M.; Garcez, A. S. D. Avila

    2009-01-01

    This paper studies methodologically robust options for giving logical contents to nodes in abstract argumentation networks. It defines a variety of notions of attack in terms of the logical contents of the nodes in a network. General properties of logics are refined both in the object level and in the meta level to suit the needs of the application. The network-based system improves upon some of the attempts in the literature to define attacks in terms of defeasible proofs, the...

  16. AN APPROACH OF DEFENDING AGAINST DDOS ATTACK

    Institute of Scientific and Technical Information of China (English)

    Wu Zhijun; Duan Haixin; Li Xing

    2006-01-01

    An approach of defending against Distributed Denial of Service (DDoS) attack based on flow model and flow detection is presented. The proposed approach can protect targets from DDoS attacking, and allow targets to provide good service to legitimate traffic under DDoS attacking, with fast reaction. This approach adopts the technique of dynamic comb filter, yields a low level of false positives of less than 1.5%,drops similar percentage of good traffic, about 1%, and passes neglectable percentage of attack bandwidth to the victim, less than 1.5%. The prototype of commercial product, D-fighter, is developed by implementing this proposed approach on Intel network processor platform IXP 1200.

  17. The role of sleep in migraine attacks

    Directory of Open Access Journals (Sweden)

    Elaine Inamorato

    1993-11-01

    Full Text Available Migraine attacks may be precipitated by sleep deprivation or excessive sleep and sleep is also associated with relief of migraine attacks. In view of this variable relationship we studied the records of 159 consecutive outpatients of our Headache Unit. In 121 records there was reference to sleep involvement, in 55% by a single form and in 45% by more than one form. When only one form was related, relief was most common (70%. 30% of that group of patients had the migraine attack precipitated by sleep, 24% by deprivation and 6% by sleep excess. When the effects of sleep were multiple, these effects were as expected logically in 65%: «in accordance» group (e.g attack precipitated by sleep deprivation and relieved by sleep onset. In a second group, («conflicting» where the involvement was not logical, there were three different combinations of sleep involvement, possibly due to more than one pathophysiological mechanism.

  18. Recovery of infrastructure networks after localised attacks

    Science.gov (United States)

    Hu, Fuyu; Yeung, Chi Ho; Yang, Saini; Wang, Weiping; Zeng, An

    2016-04-01

    The stability of infrastructure network is always a critical issue studied by researchers in different fields. A lot of works have been devoted to reveal the robustness of the infrastructure networks against random and malicious attacks. However, real attack scenarios such as earthquakes and typhoons are instead localised attacks which are investigated only recently. Unlike previous studies, we examine in this paper the resilience of infrastructure networks by focusing on the recovery process from localised attacks. We introduce various preferential repair strategies and found that they facilitate and improve network recovery compared to that of random repairs, especially when population size is uneven at different locations. Moreover, our strategic repair methods show similar effectiveness as the greedy repair. The validations are conducted on simulated networks, and on real networks with real disasters. Our method is meaningful in practice as it can largely enhance network resilience and contribute to network risk reduction.

  19. Prevention of Routing Attacks In Manet

    Directory of Open Access Journals (Sweden)

    N.Rajesh

    2013-01-01

    Full Text Available Mobile Ad hoc Networks (MANET are easily prone to attacks due to its network infrastructure. In previous routing attacks the malicious node is isolated using naive fuzzy response decisions. In this paper a new technology of broadcasting the awareness information about attacker node to all the existing nodes in the network is discussed. The awareness approach is based on an extended Dempster-Shafer mathematical theory(D-S Theory. Dempster-Shafer mathematical theory is used to collect the evidence notion of importance factors. The adaptiveness of the mechanism allows to systematically cope with the identified MANET routing attacks. The intrusion response action in MANET was addressed by isolating uncooperative nodes based on the node reputation derived from their behaviors. Here the effectiveness of the approach with the consideration of the packet delivery ratio and routing cost were demonstrated using java swing concepts

  20. CASE STUDY OF SQL INJECTION ATTACKS

    OpenAIRE

    Sonakshi*, Rakesh Kumar, Girdhar Gopal

    2016-01-01

    Today, most of the web applications are associated with database at back-end so there are possibilities of SQL injection attacks (SQLIA) on it. A number of preventive measures have also been discovered by various researchers to overcome this attack, but which measure is more convenient and provides fast access to application without compromising the security is also a major concern nowadays. This paper provides a clear distinction among different types of SQLIAs and how these can be performed...

  1. Pathologic features of fatal shark attacks.

    Science.gov (United States)

    Byard, R W; Gilbert, J D; Brown, K

    2000-09-01

    To examine the pattern of injuries in cases of fatal shark attack in South Australian waters, the authors examined the files of their institution for all cases of shark attack in which full autopsies had been performed over the past 25 years, from 1974 to 1998. Of the seven deaths attributed to shark attack during this period, full autopsies were performed in only two cases. In the remaining five cases, bodies either had not been found or were incomplete. Case 1 was a 27-year-old male surfer who had been attacked by a shark. At autopsy, the main areas of injury involved the right thigh, which displayed characteristic teeth marks, extensive soft tissue damage, and incision of the femoral artery. There were also incised wounds of the right wrist. Bony injury was minimal, and no shark teeth were recovered. Case 2 was a 26-year-old male diver who had been attacked by a shark. At autopsy, the main areas of injury involved the left thigh and lower leg, which displayed characteristic teeth marks, extensive soft tissue damage, and incised wounds of the femoral artery and vein. There was also soft tissue trauma to the left wrist, with transection of the radial artery and vein. Bony injury was minimal, and no shark teeth were recovered. In both cases, death resulted from exsanguination following a similar pattern of soft tissue and vascular damage to a leg and arm. This type of injury is in keeping with predator attack from underneath or behind, with the most severe injuries involving one leg. Less severe injuries to the arms may have occurred during the ensuing struggle. Reconstruction of the damaged limb in case 2 by sewing together skin, soft tissue, and muscle bundles not only revealed that no soft tissue was missing but also gave a clearer picture of the pattern of teeth marks, direction of the attack, and species of predator.

  2. Modeling attacking of high skills volleyball players

    Directory of Open Access Journals (Sweden)

    Vladimir Gamaliy

    2014-12-01

    Full Text Available Purpose: to determine the model indicators of technical and tactical actions in the attack highly skilled volleyball players. Material and Methods: the study used statistical data of major international competitions: Olympic Games – 2012 World Championships – 2010, World League – 2010–2014 European Championship – 2010–2014. A total of 130 analyzed games. Methods were used: analysis and generalization of scientific and methodological literature, analysis of competitive activity highly skilled volleyball players, teacher observation, modeling technical and tactical actions in attacking highly skilled volleyball players. Results: it was found that the largest volume application of technical and tactical actions in the attack belongs to the group tactics «supple movement», whose indicator is 21,3%. The smallest amount of application belongs to the group tactics «flight level» model whose indicators is 5,4%, the efficiency of 3,4%, respectively. It is found that the power service in the jump from model parameters used in 51,6% of cases, the planning targets – 21,7% and 4,4% planning to reduce. Attacks performed with the back line, on model parameters used in the amount of 20,8% efficiency –13,7%. Conclusions: we prove that the performance of technical and tactical actions in the attack can be used as model in the control system of training and competitive process highly skilled volleyball players

  3. Performance Evaluation of AODV with Blackhole Attack

    Science.gov (United States)

    Dara, Karuna

    2010-11-01

    A Mobile Ad Hoc Network (MANET) is a temporary network set up by a wireless mobile computers moving arbitrary in the places that have no network infrastructure. These nodes maintain connectivity in a decentralized manner. Since the nodes communicate with each other, they cooperate by forwarding data packets to other nodes in the network. Thus the nodes find a path to the destination node using routing protocols. However, due to security vulnerabilities of the routing protocols, mobile ad-hoc networks are unprotected to attacks of the malicious nodes. One of these attacks is the Black Hole Attack against network integrity absorbing all data packets in the network. Since the data packets do not reach the destination node on account of this attack, data loss will occur. In this paper, we simulated the black hole attack in various mobile ad-hoc network scenarios using AODV routing protocol of MANET and have tried to find a effect if number of nodes are increased with increase in malicious nodes.

  4. Power analysis attacks revealing the secrets of smart cards

    CERN Document Server

    Mangard, Stefan; Popp, Thomas

    2008-01-01

    A comprehensive treatment of power analysis attacks and countermeasures. Based on the principle that the only way to defend against power analysis attacks is to understand them, this book explains how power analysis attacks work. It discusses simple and differential power analysis as well as advanced techniques like template attacks.

  5. Early Detection of SQL Injection Attacks

    Directory of Open Access Journals (Sweden)

    Hossain Shahriar

    2013-07-01

    Full Text Available SQL Injection (SQLI is a common vulnerability found in web applications.The starting point of SQLIattack is the client-side (browser. If attack inputs can be detected early at the browse side, then it could bethwarted early by not forwarding the malicious inputs to the server-side for further processing.This paperpresents a client-side approach to detect SQLI attacks1. The client-side accepts shadow SQL queries fromthe server-side and checks any deviation betweenshadow queries with dynamic queries generated withuser supplied inputs. We measure the deviation of shadow query and dynamic query based on conditionalentropy metrics and propose four metrics in this direction. We evaluate the approach with three PHPapplications containing SQLI vulnerabilities. The evaluation results indicate that our approach can detectwell-known SQLI attacks early at the client-side and impose negligible overhead.

  6. Panic Attack or Heart Attack?

    Science.gov (United States)

    Panic Attack or Heart Attack? Diagnosing heart disease in women A Healthy Hearts Guide ® Heart disease in women is often mistaken for panic attack with shortness of breath, anxiety, palpitations and indigestion. ...

  7. The diagnosis of transient ischemic attacks

    NARCIS (Netherlands)

    P.J. Koudstaal (Peter Jan)

    1989-01-01

    textabstractThe diagnosis of transient ischemic attack (TIA) is fraught with difficulty, since the diagnosis rests entirely upon the history of the patient's symptoms and the neurologist's skill in questioning the patient. The aim of this thesis is to investigate various measures to improve the reli

  8. Chemical Attack of Malaysian Pozzolans Concrete

    Directory of Open Access Journals (Sweden)

    Mohd Hilton Ahmad

    2011-09-01

    Full Text Available Malaysia produces more than 10 million tonne of by-product from industrial sector per year. As the environmental impact concerns, more than half of the by-product can be recycled to be used as construction materials. One of them is pozzolan, a cement replacing material that can be used to enhance the properties of the concrete. This paper studies the chemical attack to local prozzolans concrete. The parameters studied include weight loss, length change, and residual strength of local pozzolans concrete after been exposed to severe environment. The specimen were tested under normal room temperature, exposed to magnesium sulfate, MgSO4. 2H2O where both sulfate attack and acid attack take place. Two series of pozzolans< which is Pulverized fly ash (PFA and Palm oil fuel ash (POFA were identified. Another series of admixture, Quarry Dust (QD from quarry waste that contain high amount of silica content also been carried out. Each series will study the effect of cement replacement percentage of 5%, 10% and 15%. The parameters were compared to conventional ordinary Portland cement (OPC concrete as control mix. Accelerated testing was conducted at 3, 7, 28, 56 and 90 days. The result shows that the local pozzolans concrete were found to be in good resistance against sulfate attack compared to conventional concrete. Compared to all series conducted, series of PFA replacement gave the best resistance followed by POFA and QD replacement series.

  9. Recovery of human remains after shark attack.

    Science.gov (United States)

    Byard, Roger W; James, Ross A; Heath, Karen J

    2006-09-01

    Two cases of fatal shark attack are reported where the only tissues recovered were fragments of lung. Case 1: An 18-year-old male who was in the sea behind a boat was observed by friends to be taken by a great white shark (Carcharodon carcharias). The shark dragged him under the water and then, with a second shark, dismembered the body. Witnesses noted a large amount of blood and unrecognizable body parts coming to the surface. The only tissues recovered despite an intensive beach and sea search were 2 fragments of lung. Case 2: A 19-year-old male was attacked by a great white shark while diving. A witness saw the shark swim away with the victim's body in its mouth. Again, despite intensive beach and sea searches, the only tissue recovered was a single piece of lung, along with pieces of wetsuit and diving equipment. These cases indicate that the only tissue to escape being consumed or lost in fatal shark attacks, where there is a significant attack with dismemberment and disruption of the integrity of the body, may be lung. The buoyancy of aerated pulmonary tissue ensures that it rises quickly to the surface, where it may be recovered by searchers soon after the attack. Aeration of the lung would be in keeping with death from trauma rather than from drowning and may be a useful marker in unwitnessed deaths to separate ante- from postmortem injury, using only relatively small amounts of tissues. Early organ recovery enhances the identification of human tissues as the extent of morphologic alterations by putrefactive processes and sea scavengers will have been minimized. DNA testing is also possible on such recovered fragments, enabling confirmation of the identity of the victim. PMID:16936505

  10. Recovery of human remains after shark attack.

    Science.gov (United States)

    Byard, Roger W; James, Ross A; Heath, Karen J

    2006-09-01

    Two cases of fatal shark attack are reported where the only tissues recovered were fragments of lung. Case 1: An 18-year-old male who was in the sea behind a boat was observed by friends to be taken by a great white shark (Carcharodon carcharias). The shark dragged him under the water and then, with a second shark, dismembered the body. Witnesses noted a large amount of blood and unrecognizable body parts coming to the surface. The only tissues recovered despite an intensive beach and sea search were 2 fragments of lung. Case 2: A 19-year-old male was attacked by a great white shark while diving. A witness saw the shark swim away with the victim's body in its mouth. Again, despite intensive beach and sea searches, the only tissue recovered was a single piece of lung, along with pieces of wetsuit and diving equipment. These cases indicate that the only tissue to escape being consumed or lost in fatal shark attacks, where there is a significant attack with dismemberment and disruption of the integrity of the body, may be lung. The buoyancy of aerated pulmonary tissue ensures that it rises quickly to the surface, where it may be recovered by searchers soon after the attack. Aeration of the lung would be in keeping with death from trauma rather than from drowning and may be a useful marker in unwitnessed deaths to separate ante- from postmortem injury, using only relatively small amounts of tissues. Early organ recovery enhances the identification of human tissues as the extent of morphologic alterations by putrefactive processes and sea scavengers will have been minimized. DNA testing is also possible on such recovered fragments, enabling confirmation of the identity of the victim.

  11. Activity Modelling and Comparative Evaluation of WSN MAC Security Attacks

    DEFF Research Database (Denmark)

    Pawar, Pranav M.; Nielsen, Rasmus Hjorth; Prasad, Neeli R.;

    2012-01-01

    and initiate security attacks that disturb the normal functioning of the network in a severe manner. Such attacks affect the performance of the network by increasing the energy consumption, by reducing throughput and by inducing long delays. Of all existing WSN attacks, MAC layer attacks are considered...... the most harmful as they directly affect the available resources and thus the nodes’ energy consumption. The first endeavour of this paper is to model the activities of MAC layer security attacks to understand the flow of activities taking place when mounting the attack and when actually executing it....... The second aim of the paper is to simulate these attacks on hybrid MAC mechanisms, which shows the performance degradation of aWSN under the considered attacks. The modelling and implementation of the security attacks give an actual view of the network which can be useful in further investigating secure...

  12. Quantitative Verification and Synthesis of Attack-Defence Scenarios

    DEFF Research Database (Denmark)

    Aslanyan, Zaruhi; Nielson, Flemming; Parker, David

    2016-01-01

    Attack-defence trees are a powerful technique for formally evaluating attack-defence scenarios. They represent in an intuitive, graphical way the interaction between an attacker and a defender who compete in order to achieve conflicting objectives. We propose a novel framework for the formal...... analysis of quantitative properties of complex attack-defence scenarios, using an extension of attack-defence trees which models temporal ordering of actions and allows explicit dependencies in the strategies adopted by attackers and defenders. We adopt a game-theoretic approach, translating attack......-defence trees to two-player stochastic games, and then employ probabilistic model checking techniques to formally analyse these models. This provides a means to both verify formally specified security properties of the attack-defence scenarios and, dually, to synthesise strategies for attackers or defenders...

  13. Managing burn victims of suicide bombing attacks: outcomes, lessons learnt, and changes made from three attacks in Indonesia

    OpenAIRE

    Chim, Harvey; Yew, Woon Si; Song, Colin

    2007-01-01

    Introduction Terror attacks in Southeast Asia were almost nonexistent until the 2002 Bali bomb blast, considered the deadliest attack in Indonesian history. Further attacks in 2003 (Jakarta), 2004 (Jakarta), and 2005 (Bali) have turned terrorist attacks into an ever-present reality. Methods The authors reviewed medical charts of victims evacuated to the Singapore General Hospital (SGH) Burns Centre during three suicide attacks involving Bali (2002 and 2005) and the Jakarta Marriott hotel (200...

  14. Analysis of the SYN Flood DoS Attack

    Directory of Open Access Journals (Sweden)

    Mitko Bogdanoski

    2013-06-01

    Full Text Available The paper analyzes systems vulnerability targeted by TCP (Transmission Control Protocol segments when SYN flag is ON, which gives space for a DoS (Denial of Service attack called SYN flooding attack or more often referred as a SYN flood attack. The effects of this type of attack are analyzed and presented in OPNET simulation environment. Furthermore, the paper presents two anomaly detection algorithms as an effective mechanism against this type of attack. Finally, practical approaches against SYN flood attack for Linux and Windows environment which are followed by are shown.

  15. A Survey of Mobile Ad Hoc Network Attacks

    Directory of Open Access Journals (Sweden)

    PRADIP M. JAWANDHIYA,

    2010-09-01

    Full Text Available Security is an essential requirement in mobile ad hoc network (MANETs. Compared to wired networks, MANETs are more vulnerable to security attacks due to the lack of a trusted centralized authority and limited resources. Attacks on ad hoc networks can be classified as passive and active attacks, depending on whether the normal operation of the network is disrupted or not. In this paper, we are describing the all prominent attacks described in literature in a consistent manner to provide a concise comparison on attack types. To the best of our knowledge, this is the first paper that studies all the existing attacks on MANETs.

  16. Incidence of Fungal attack on Aircraft Fuselage

    Directory of Open Access Journals (Sweden)

    H. M. Dayal

    1968-10-01

    Full Text Available Incidence of fungal attack on the fuselage of a few Vampire aircraft has been observed. The fungus isolated from the infected regions has been tentatively indentified as TorulaSp. Laboratory experiments have revealed that within four weeks this fungus causes about 44 percent loss in the tensile strength of the brich plywood used in the manufacture of the fuselage of the aircraft.

  17. An Analysis of Various Attacks in MANET

    OpenAIRE

    M.Udhayamoorthi; C. Senthilkumar; Dr S. Karthik; Dr. T.Kalaikumaran

    2014-01-01

    An Ad-hoc network is a self-organized network, without a central coordinator, and which frequently changes its topology. According to the perspective of our paper, we try to connect the current status of computers era to adhoc networking. As adhoc networks has been unleashing several updated technologies, it is the most growing area in the field of networks in information and communication Engineering has ever seen .we start with area introduction, deeply reviewed about the various attacks es...

  18. Denial of Service Attack Techniques: Analysis, Implementation and Comparison

    Directory of Open Access Journals (Sweden)

    Khaled Elleithy

    2005-02-01

    Full Text Available A denial of service attack (DOS is any type of attack on a networking structure to disable a server from servicing its clients. Attacks range from sending millions of requests to a server in an attempt to slow it down, flooding a server with large packets of invalid data, to sending requests with an invalid or spoofed IP address. In this paper we show the implementation and analysis of three main types of attack: Ping of Death, TCP SYN Flood, and Distributed DOS. The Ping of Death attack will be simulated against a Microsoft Windows 95 computer. The TCP SYN Flood attack will be simulated against a Microsoft Windows 2000 IIS FTP Server. Distributed DOS will be demonstrated by simulating a distribution zombie program that will carry the Ping of Death attack. This paper will demonstrate the potential damage from DOS attacks and analyze the ramifications of the damage.

  19. Mitigation of Malicious Attacks on Networks

    CERN Document Server

    Schneider, Christian M; Andrade, Jose S; Havlin, Shlomo; Herrmann, Hans J; 10.1073/pnas.1009440108

    2011-01-01

    Terrorist attacks on transportation networks have traumatized modern societies. With a single blast, it has become possible to paralyze airline traffic, electric power supply, ground transportation or Internet communication. How and at which cost can one restructure the network such that it will become more robust against a malicious attack? We introduce a unique measure for robustness and use it to devise a method to mitigate economically and efficiently this risk. We demonstrate its efficiency on the European electricity system and on the Internet as well as on complex networks models. We show that with small changes in the network structure (low cost) the robustness of diverse networks can be improved dramatically while their functionality remains unchanged. Our results are useful not only for improving significantly with low cost the robustness of existing infrastructures but also for designing economically robust network systems.

  20. Robustness of Complex Networks against Attacks Guided by Damage

    CERN Document Server

    Wang, Hui; Xu, Xiaomin; Xiao, Yanghua; Wang, Wei

    2011-01-01

    Extensive researches have been dedicated to investigating the performance of real networks and synthetic networks against random failures or intentional attack guided by degree (degree attack). Degree is one of straightforward measures to characterize the vitality of a vertex in maintaining the integrity of the network but not the only one. Damage, the decrease of the largest component size that was caused by the removal of a vertex, intuitively is a more destructive guide for intentional attack on networks since the network functionality is usually measured by the largest component size. However, it is surprising to find that little is known about behaviors of real networks or synthetic networks against intentional attack guided by damage (damage attack), in which adversaries always choose the vertex with the largest damage to attack. In this article, we dedicate our efforts to understanding damage attack and behaviors of real networks as well as synthetic networks against this attack. To this end, existing ...

  1. Concrete Deterioration under Alternate Action of Carbonation and Sulfate Attack

    Directory of Open Access Journals (Sweden)

    Fenglan Li

    2013-11-01

    Full Text Available By micro- and macro-observations, the study reveals the deterioration mechanisms of concrete under alternate action of carbonation and sodium sulfate solution attack (C-SA comparied with the single sodium sulfate solution attack (SA. The studies indicate that in both cases, the main attack product is ettringite, some gypsum is checked only in the first layer of case SA, the thaumasite form of sulfate attack is not initiated in case C-SA. Compared with the single sodium sulfate solution attack, although the carbonation layer mitigates the extent of sulfate attack in limited exposure period, the alternate action of carbonation and sulfate attack still leads to strength degradation to some extent. The effect of carbonation on sulfate attack for longer exposure period deserves further research.

  2. Tests of Aerodynamically Heated Multiweb Wing Structures in a Free Jet at Mach Number 2: Five Aluminum-Alloy Models of 20-Inch Chord with 0.064-Inch-Thick Skin, 0.025-Inch-Thick Webs, and Various Chordwise Stiffening at 2 deg Angle of Attack

    Science.gov (United States)

    Trussell, Donald H.; Thomson, Robert G.

    1960-01-01

    An experimental study was made on five 2024-T3 aluminum-alloy multiweb wing structures (MW-2-(4), MW-4-(3), mw-16, MW-17, and MW-18), at a Mach number of 2 and an angle of attack of 2 deg under simulated supersonic flight conditions. These models, of 20-inch chord and semi-span and 5-percent-thick circular-arc airfoil section, were identical except for the type and amount of chordwise stiffening. One model with no chordwise ribs between root and tip bulkhead fluttered and failed dynamically partway through its test. Another model with no chordwise ribs (and a thinner tip bulkhead) experienced a static bending type of failure while undergoing flutter. The three remaining models with one, two, or three chordwise ribs survived their tests. The test results indicate that the chordwise shear rigidity imparted to the models by the addition of even one chordwise rib precludes flutter and subsequent failure under the imposed test conditions. This paper presents temperature and strain data obtained from the tests and discusses the behavior of the models.

  3. Comparative Analysis of Routing Attacks in Ad Hoc Network

    Directory of Open Access Journals (Sweden)

    Bipul Syam Purkayastha

    2012-03-01

    Full Text Available In the mobile ad hoc networks the major role is played by the routing protocols in order to route the data from one mobile node to another mobile node. But in such mobile networks, routing protocols are vulnerable to various kinds of security attacks such as blackhole node attacks. The routing protocols of MANET are unprotected and hence resulted into the network with the malicious mobile nodes in the network. These malicious nodes in the network are basically acts as attacks in the network. In this paper, we modify the existing DSR protocol with the functionality of attacks detection without affecting overall performance of the network. Also, we are considering the various attacks on mobile ad hoc network called blackhole attack, flooding attack and show the comparative analysis of these attacks using network simulator ns-2.

  4. A Review of Man-in-the-Middle Attacks

    OpenAIRE

    Gangan, Subodh

    2015-01-01

    This paper presents a survey of man-in-the-middle (MIM) attacks in communication networks and methods of protection against them. In real time communication, the attack can in many situations be discovered by the use of timing information. The most common attacks occur due to Address Resolution Protocol (ARP) cache poisoning, DNS spoofing, session hijacking, and SSL hijacking.

  5. A Formal Classification of Internet Banking Attacks and Vulnerabilities

    Directory of Open Access Journals (Sweden)

    Laerte Peotta

    2011-02-01

    Full Text Available A formal classification of attacks and vulnerabilities that affect current internet banking systems is presented along with two attacks which demonstrate the insecurity of such systems. Based ona thoroughanalysis of current security models, we propose a guidelines for designing secure internet banking systems which are not affected by the presented attacks and vulnerabilities.

  6. Understand Your Risk of Heart Attack

    Science.gov (United States)

    ... Stroke More Understand Your Risks to Prevent a Heart Attack Updated:Aug 2,2016 Knowledge is power, so ... medication. This content was last reviewed June 2016. Heart Attack • Home • About Heart Attacks Acute Coronary Syndrome (ACS) • ...

  7. Methods of Identifying and Preventing SQL Attacks

    Directory of Open Access Journals (Sweden)

    Bojken Shehu

    2012-11-01

    Full Text Available The paper begins by identifying the organizations which are vulnerable to the SQL attack referred to as an SQL injection attack. The term SQL injection attack is defined and a diagram is used to illustrate the way that attack occurs. In another section, the paper identifies the methods used to detect an attack to SQL, whereby the techniques are discussed extensively using relevant diagrams for illustration. The other sections cover the preventive methods, where the methods are also discussed with an illustration using diagrams.

  8. The Semiotic and Conceptual Genesis of Angle

    Science.gov (United States)

    Tanguay, Denis; Venant, Fabienne

    2016-01-01

    In the present study, we try to understand how students at the end of primary school conceive of angle: Is an angle a magnitude for them or a geometric figure, and how do they manage to coordinate the two aspects in their understanding of the concepts of angle and of angle measurement? With the aim of better grasping the way "angle" is…

  9. On the security of gyrator transform-based image encryption by chosen-plaintext attack

    Science.gov (United States)

    Sang, Jun; Alam, Mohammad S.; Cai, Bin

    2016-04-01

    For the gyrator transform-based image encryption, besides the random operations, the rotation angles used in the gyrator transforms are also taken as the secret keys, which makes such cryptosystems to be more secure. To analyze the security of such cryptosystems, one may start from analyzing the security of a single gyrator transform. In this paper, the security of the gyrator transform-based image encryption by chosen-plaintext attack was discussed in theory. By using the impulse functions as the chosen-plaintext, it was concluded that: (1) For a single gyrator transform, by choosing a plaintext, the rotation angle can be obtained very easily and efficiently; (2) For image encryption with a single random phase encoding and a single gyrator transform, it is hard to find the rotation angle directly with a chosen-plaintext attack. However, assuming the value of one of the elements in the random phase mask is known, the rotation angle can be obtained very easily with a chosen-plaintext attack, and the random phase mask can also be recovered. Furthermore, by exhaustively searching the value of one of the elements in the random phase mask, the rotation angle as well as the random phase mask may be recovered. By obtaining the relationship between the rotation angle and the random phase mask for image encryption with a single random phase encoding and a single gyrator transform, it may be useful for further study on the security of the iterative random operations in the gyrator transform domains.

  10. Frequency characteristics of breakdown vortices over delta wings with small amplitude oscillation at the high angle of attack%大迎角下小振幅振荡三角翼破裂涡的频率特性

    Institute of Scientific and Technical Information of China (English)

    张明禄; 刘绍辉; 吕志咏

    2009-01-01

    Experiments of dynamic unsteady pressure measurement and hot film velocity measurement with the small amplitude oscillation delta wings were carried out in a water channel and a wind tunnel respec-tively in order to investigate the influence of the nondimensional oscillation frequency n on the frequency char-acteristics of leading-edge vortices over delta wings. Power spectral analysis of pressure signal measured in the wind tunnel shows that at n =0.018~0.036, which is close to the oscillation frequency of vortex breakdown point, resonant phenomenon will happen and oscillatory energy will be largely enhanced. Power spectral analy-sis of velocity signal measured in the water channel shows that at n =0. 8~1. 38, which is close to the propa-gation frequency of spiral wave, the vortex breakdown point moves towards trailing edge, and therefore break-down of vortices will be delayed and the dominant frequency will be increased.%在风洞和水洞中分别进行了小振幅振荡三角翼的动态测压和热膜测速实验,目的是研究振荡的无量纲频率n对于三角翼前缘涡的频率特性的影响.对风洞中测得的压力数据进行频谱分析,发现n值在0.018~0.036时,即与三角翼翼面上涡破裂点的振荡频率接近时,会发生耦合现象,使振动能量明显加强;对水洞中测得的速度数据进行频谱分析,则发现n在0.8~1.4的范围内,即与螺旋波的传播频率接近时,三角翼的振荡会使涡破裂点向后缘移动,延缓了涡的破裂,使螺旋波频率增大.

  11. Unified communications forensics anatomy of common UC attacks

    CERN Document Server

    Grant, Nicholas Mr

    2013-01-01

    Unified Communications Forensics: Anatomy of Common UC Attacks is the first book to explain the issues and vulnerabilities and demonstrate the attacks, forensic artifacts, and countermeasures required to establish a secure (UC) environment. This book is written by leading UC experts Nicholas Grant and Joseph W. Shaw II and provides material never before found on the market, including: analysis of forensic artifacts in common UC attacks an in-depth look at established UC technologies and attack exploits hands-on understanding of UC attack vectors and associated countermeasures

  12. Survey of Protections from Buffer-Overflow Attacks

    OpenAIRE

    Krerk Piromsopa; Richard J Enbody

    2011-01-01

    Buffer-overflow attacks began two decades ago and persist today. Over that time, many solutions to provide protection from buffer-overflow attacks have been proposed by a number of researchers. They all aim to either prevent or protect against buffer-overflow attacks. As defenses improved, attacks adapted and became more sophisticated. Given the maturity of field and the fact that some solutions now exist that can prevent most buffer-overflow attacks, we believe it is time to survey these sch...

  13. PERFORMANCE EVALUATION OF WIRELESS SENSOR NETWORK UNDER HELLO FLOOD ATTACK

    Directory of Open Access Journals (Sweden)

    Mohammad Abdus Salam

    2016-03-01

    Full Text Available Wireless sensor network (WSN is highly used in many fields. The network consists of tiny lightweight sensor nodes and is largely used to scan or detect or monitor environments. Since these sensor nodes are tiny and lightweight, they put some limitations on resources such as usage of power, processing given task, radio frequency range. These limitations allow network vulnerable to many different types of attacks such as hello flood attack, black hole, Sybil attack, sinkhole, and many more. Among these attacks, hello flood is one of the most important attacks. In this paper,we have analyzed the performance of hello flood attack and compared the network performance as number of attackers increases. Network performance is evaluated by modifying the ad-hoc on demand distance vector (AODV routing protocol by using NS2 simulator. It has been tested under different scenarios like no attacker, single attacker, and multiple attackers to know how the network performance changes. The simulation results show that as the number of attackers increases the performance in terms of throughput and delay changes.

  14. 原发性闭角型青光眼单侧急性发作对侧眼激光虹膜周边切除术后随访研究%Follow-up of laser peripheral iridotomy in fellow eyes with unilateral acute attack of primary angle closure glaucoma

    Institute of Scientific and Technical Information of China (English)

    张海涛; 杨华; 徐英英

    2011-01-01

    Background Laser peripheral iridotomy(LPI) is used as the primary therapy for the eyes at risk of angle closure.But there are still 28% eyes with primary angle closure suspect occur angle closure within 2 years after LPI.It is necessary to explore the associated factors of the efficacy of LPI.Objective The aim of this study was to explore the changes of intraocular pressure(IOP) and anterior chamber angle in the fellow eyes of patients with unilateral acute attack of primary angle closure glaucoma (PACG) and analyze the relevant factors influencing the successful rate of LPI.Methods Eighty-seven fellow eyes received LPI from 87 patients with unilateral acute attack of PACG were included in this study and retrospectively analyzed.The IOP and gonioscopy were performed before and 1 week,3,6,9,12 months after LPI.Successful signs of LPI were defined as an IOP 6-21mmHg without any anti-glaucoma medication,none of glaucomatous neuropathy and the coincident visual field loss,and no need of additional glaucomatous medication or surgery.This study was approved by Ethic Committee of the First Hospital of Xinxiang Medical College,and written informed consent was obtained from each patient.Results Seventy-nine eyes of 79 cases finished the medical visit throughout the follow-up duration with the age 61.4±0.4 years and 33(41.8%) males and 46(58.2%) females.The mean IOP was lowed in various time points after LPI in comparison with before operation with the general difference among different time visiting groups(F=4.056,P<0.01).Shaffer grade was increased in superior,temporal and nasal quadrants and significant differences were found between 1 week group,3 months group or 6 months group and before operation group (P<0.05).LPI lessened the range of appositional angle closure (AAC) in postoperative 1 week group and 3 months group compared with pre-operative group (P<0.05),but no statistically significant reduce was seen in range of AAC from 6 months through 12 months after

  15. Variability of clinical features in attacks of migraine with aura

    DEFF Research Database (Denmark)

    Hansen, Jakob M; Goadsby, Peter J; Charles, Andrew C

    2016-01-01

    BACKGROUND: There is significant variability in the clinical presentation of migraine, both among patients, and between attacks in an individual patient. We examined clinical features of migraine with aura in a large group of patients enrolled in a clinical trial, and compared retrospective...... migraine attack characteristics reported upon enrollment in the trial with those recorded prospectively in the trial. METHODS: Patients with migraine (n = 267) with typical visual aura in more than 30% of their attacks were enrolled from 16 centers for a clinical trial. Upon enrollment, patients provided...... a detailed retrospective description of the clinical features of their attacks of migraine. During the trial, clinical symptoms in migraine attacks starting with aura were recorded prospectively in 861 attacks. RESULTS: Retrospectively reported visual aura symptoms were variable and often overlapping...

  16. REVIEW CLUSTERING MECHANISMS OF DISTRIBUTED DENIAL OF SERVICE ATTACKS

    Directory of Open Access Journals (Sweden)

    Wesam Bhaya

    2014-01-01

    Full Text Available Distributed Denial of Service attacks (DDoS overwhelm network resources with useless or harmful packets and prevent normal users from accessing these network resources. These attacks jeopardize the confidentiality, privacy and integrity of information on the internet. Since it is very difficult to set any predefined rules to correctly identify genuine network traffic, an anomaly-based Intrusion Detection System (IDS for network security is commonly used to detect and prevent new DDoS attacks. Data mining methods can be used in intrusion detection systems, such as clustering k-means, artificial neural network. Since the clustering methods can be used to aggregate similar objects, they can detect DDoS attacks to reduce false-positive rates. In this study, a review of DDoS attacks using clustering data mining techniques is presented. A review illustrates the most recent, state-of-the art science for clustering techniques to detect DDoS attacks.

  17. Public knowledge of heart attack symptoms in Beijing residents

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-tan; HU Da-yi; YANG Jin-gang; ZHANG Shou-yan; ZHANG Xin-quan; LIU Shu-shan

    2007-01-01

    Background Definitive treatment for heart attack is early reperfusion with either angioplasty or thrombolytic therapy,and the benefit is strictly time-dependent. Patient outcomes are improved with either therapy when initiated as soon as possible. Recognition of heart attack symptoms is logically tied to taking action to receive prompt emergency care.Inadequate knowledge of heart attack symptoms may prolong delay. The purpose of this study was to document knowledge about heart attack symptoms in Beijing residents and to identify the characteristics associated with increased knowledge of heart attack.Methods A structured survey was conducted in 18 communities in Beijing from March 1 through June 10 in 2006.Addresses and participants were selected randomly following a stratification. The survey was designed to collect knowledge of heart attack symptoms from sampled adults in each community.Results A total of 4627 respondents completed the questionnaires correctly, and 50.29% of them were female. Totally 64.15% of the respondents reported chest pain or discomfort (common symptoms) as a symptom of heart attack; 75.38% reported at least one of the following eight symptoms as a symptom of heart attack: back pain, shortness of breath, arm pain or numbness, nausea or vomiting, neck, jaw or shoulder pain, epigastric pain, sweating, weakness (less common symptoms); 20.36% correctly reported four or more heart attack symptoms, only 7.4% knew all the correct heart attack symptoms, and 28.94% knew about reperfusion therapy for heart attack; 31.7% reported to call 120 or 999 while having a heart attack themselves; however 89.6% reported to call 120 or 999 when someone else is suffering from a heart attack. Very old persons and those with health insurance coverage, high education level, high household income, longer living in Beijing and previous experience with heart disease had greater knowledge of heart attack symptoms.Conclusions Public knowledge of common heart attack

  18. An Attack Investigation, Characterization and Simulation of Various Attacks in MANET

    Directory of Open Access Journals (Sweden)

    Pratik Gite

    2015-01-01

    Full Text Available Mobile Ad-hoc Network is one of the most popular network technology in the field of research and development community. Due to their dynamic and ad-hoc nature, the network suffers from the various performance and security issues. The main objective of this paper is to evaluate the performance of Ad-hoc On Demand Distance Vector (AODV routing protocol under normal condition and attacks conditions on the basis of different performance metrics. This paper is also concerned about the different kinds of attacks formation viz. Black Hole, Worm Hole, Gray Hole and Denial of Service attacks on MANET environment. In addition of that different kinds of approaches available for detection and prevention of such attacks are also investigated. Finally using different experimentation and simulations through NS-2, the effort is made to identify the effective network characteristics. After concluding the effects and simulation the need of a new Intrusion Detection System (IDS model is presented for future implementation.

  19. Performance Analysis of Manet Before and After Black Hole Attack

    Directory of Open Access Journals (Sweden)

    Ms.Heena Bhalla

    2012-01-01

    Full Text Available A Mobile ad-hoc network is a temporary network set up by wireless mobile computers (or nodes moving arbitrary in the places that have no network infrastructure. Due to security vulnerabilities of the routing protocols, wireless ad-hoc networks are unprotected to attacks of the malicious nodes. One of the prominent attacks is the Black Hole Attack which absorbs all data packets in the network. Since the data packets do not reach the destination node on account of this attack, data loss will occur. In this paper we simulated MANETs with and without Black Hole to study the effects of Black hole attack on network performance. Because of Black Hole Attack the average packet drop increased form 0.25% to 90.69% . The throughput of the network decreased 93.56% due to Black Hole effect.

  20. The Impact of Black-Hole Attack on ZRP Protocol

    Directory of Open Access Journals (Sweden)

    CHAHIDI Badr

    2016-07-01

    Full Text Available lack of infrastructure in ad hoc networks makes their deployment easier. Each node in an ad hoc network can route data using a routing protocol, which decreases the level of security. Ad hoc networks are exposed to several attacks such as the blackhole attack. In this article, a study has been made on the impact of the attack on the hybrid routing protocol ZRP (Zone Routing Protocol. In this attack a malicious node is placed between two or more nodes in order to drop data. The trick of the attack is simple, the malicious node declares to have the most reliable way to the destination so that the wife destination chooses this path. In this study, NS2 is used to assess the impact of the attack on ZRP. Two metrics measure, namely the packet delivered ratio and end to end delay.

  1. Agoraphobic behavior and panic attack: a study of male twins.

    Science.gov (United States)

    Tsuang, Ming; Domschke, Katharina; Jerskey, Beth A; Lyons, Michael J

    2004-01-01

    We used data from 3372 pairs of male twins from the Vietnam Era Twin Registry to examine comorbidity and familial influences on the frequently observed association between agoraphobic behavior and panic. Due to low prevalence of DSM-III-R-defined panic disorder, we also examined subjects who had experienced at least one panic attack during their lives. Agoraphobic behavior among individuals with a history of panic attacks showed familial aggregation (odds ratio = 5.7; P = .018 ). Probands with panic attacks and agoraphobic behavior and their co-twins had higher risk of major depression than probands without agoraphobic avoidance and their co-twins (P = .01). Groups did not differ for alcohol dependence or antisocial personality. Agoraphobic behavior associated with panic attack is familial and associated with comorbid major depression. Agoraphobia following panic attack does not seem to reflect severity as agoraphobic behavior in the proband was unrelated to risk of panic attacks in the co-twin. PMID:15474853

  2. Efficient Detection of Sybil Attack Based on Cryptography in Vanet

    CERN Document Server

    Rahbari, Mina

    2011-01-01

    Vehicular communications play a substantial role in providing safety transportation by means of safety message exchange. Researchers have proposed several solutions for securing safety messages. Protocols based on a fixed key infrastructure are more efficient in implementation and maintain stronger security in comparison with dynamic structures. The purpose of this paper present a method based on a fixed key infrastructure for detection impersonation attack, in other words, Sybil attack, in the vehicular ad hoc network. This attack, puts a great impact on performance of the network. The proposed method, using an cryptography mechanism to detection Sybil attack. Finally, using Mat lab simulator the results of this approach are reviewed, This method it has low delay for detection Sybil attack, because most operations are done in Certification Authority, so this proposed schema is a efficient method for detection Sybil attack.

  3. Breakdown of an Inhomogeneous Scale- Free Network Under Intentional Attack

    Institute of Scientific and Technical Information of China (English)

    LIN Guo-Ji; CHENG Xiang; OU-YANG Qi

    2003-01-01

    Using a recently introduced network model with node and connection diversity, we study the breakdown of different scale-free networks under intentional attacks. Our simulation results show that inhomogeneous networks are more sensitive to intentional attack than the homogeneous ones and that the centralization of the networks is an important variable, reflecting the characteristics of the network under intentional attack. Using a recently introduced method we can theoretically develop the critical point of the inhomogeneous networks.

  4. HProxy: Client-side detection of SSL stripping attacks

    OpenAIRE

    Nikiforakis, Nick; Younan, Yves; Joosen, Wouter

    2010-01-01

    In today's world wide web hundreds of thousands of companies use SSL to protect their customers' transactions from potential eavesdroppers. Recently,a new attack against the common usage of SSL surfaced, SSL stripping. The attack is based on the fact that users almost never request secure pages explicitly but rather rely on the servers, to redirect them to the appropriate secure version of a particular website. An attacker, after becoming man-in-the-middle can suppress such messages and p...

  5. Use of the Panic Attack Questionnaire-IV to assess non-clinical panic attacks and limited symptom panic attacks in student and community samples.

    Science.gov (United States)

    Norton, Peter J; Zvolensky, Michael J; Bonn-Miller, Marcel O; Cox, Brian J; Norton, G Ron

    2008-10-01

    Since its development in the mid-1980s, the Panic Attack Questionnaire (PAQ) has been one of the more, if not the most, commonly used self-report tools for assessing panic attacks. The usage of the instrument, however, has come amid potential concerns that instructions and descriptions may lead to an over-estimate of the prevalence of panic attacks. Furthermore, the instrument has not been revised since 1992, despite changes in DSM-IV criteria and more recent developments in the understanding of panic attacks. As a result, this paper describes a revision of the PAQ to improve the instruction and descriptive set, and to fully assess features of panic derived from recent conceptualizations. Students meeting DSM-IV panic attack criteria and those endorsing panic attacks, but not meeting criteria, showed few differences with the exception that those not meeting DSM-IV criteria typically reported a longer onset-to-peak intensity time than did Panickers. Results were cross-validated and extended using an independent Community Sample. A full descriptive phenomenology of panic attacks is described, and future directions for studying panic attacks using the PAQ are presented. PMID:18243647

  6. Impact Analysis of Recent DDoS Attacks

    Directory of Open Access Journals (Sweden)

    Ketki Arora

    2011-02-01

    Full Text Available In the present era Internet has changed the way of traditional essential services such as banking, transportation, power, health, and defence being operated. These operations are being replacedby cheaper, more efficient Internet-based applications. It is all because of rapid growth and success of Internet in every sector. Unfortunately with the growth of Internet, count of attacks on Internet has also increased incredibly fast. Denial-of-service attack is one of them, which poses immense threat on the availability. Since, the World is highly dependent on the Internet, availability of the Internet is very critical for the socio-economic growth of the society. Denial-of-service attacks occur almost every day,and the frequency and the volume of these attacks are increasing day by day. One of the biggest challenges before researchers is to find the details of such attacks because due to damaging reputationissues, most of the commercial sites do not even disclose that they were blitzed by such attacks. Details of attacks can guide very well in the formulation of comprehensive defensive solution for such attacks. In this paper, an overview on DDoS problem, major factors causing DDoS attacks are demonstrated, brief detail of most recent DDoS incidents on online organizations is outlined and finally, the need for a comprehensive distributed solution is highlighted.

  7. PERFORMANCE EVALUATION OF WIRELESS SENSOR NETWORK UNDER HELLO FLOOD ATTACK

    OpenAIRE

    Mohammad Abdus Salam; Nayana Halemani

    2016-01-01

    Wireless sensor network (WSN) is highly used in many fields. The network consists of tiny lightweight sensor nodes and is largely used to scan or detect or monitor environments. Since these sensor nodes are tiny and lightweight, they put some limitations on resources such as usage of power, processing given task, radio frequency range. These limitations allow network vulnerable to many different types of attacks such as hello flood attack, black hole, Sybil attack, sinkhole, and m...

  8. Different Types of Attacks on Integrated MANET-Internet Communication

    OpenAIRE

    Abhay Kumar Rai, Rajiv Ranjan Tewari & Saurabh Kant Upadhyay

    2010-01-01

    Security is an important issue in the integrated MANET-Internet environment because inthis environment we have to consider the attacks on Internet connectivity and also onthe ad hoc routing protocols. The focus of this work is on different types of attacks onintegrated MANET-Internet communication. We consider most common types of attackson mobile ad hoc networks and on access point through which MANET is connected tothe Internet. Specifically, we study how different attacks affect the perfor...

  9. An Indistinguishability Model for Evaluating Diverse Classes of Phishing Attacks and Quantifying Attack Efficacy

    Directory of Open Access Journals (Sweden)

    Narasimha Shashidhar

    2015-07-01

    Full Text Available Phishing is a growing threat to Internet users and causes billions of dollars in damage every year. While there are a number of research articles that study the tactics, techniques and procedures employed by phishers in the literature, in this paper, we present a theoretical yet practical model to study this menacing threat in a formal manner. While it is common folklore knowledge that a successful phishing attack entails creating messages that are indistinguishable from the natural, expected messages by the intended victim, this concept has not been formalized. Our model attempts to capture a phishing attack in terms of this indistinguishability between the natural and phishing message probability distributions. We view the actions performed by a phisher as an attempt to create messages that are indistinguishable to the victim from that of “normal” messages. To the best of our knowledge, this is the first study that places phishing on a concrete theoretical framework and offers a new perspective to analyze this threat. We propose metrics to analyze the success probability of a phishing attack taking into account the input used by a phisher and the work involved in creating deceptive email messages. Finally, we study and apply our model to a new class of phishing attacks called collaborative spear phishing that is gaining momentum. Recent examples include Operation Woolen-Goldfish in 2015, Rocket Kitten in 2014 and Epsilon email breach in 2011. We point out fundamental flaws in the current email-based marketing business model which enables such targeted spear phishing collaborative attacks. In this sense, our study is very timely and presents new and emerging trends in phishing.

  10. Non-harmful insertion of data mimicking computer network attacks

    Science.gov (United States)

    Neil, Joshua Charles; Kent, Alexander; Hash, Jr, Curtis Lee

    2016-06-21

    Non-harmful data mimicking computer network attacks may be inserted in a computer network. Anomalous real network connections may be generated between a plurality of computing systems in the network. Data mimicking an attack may also be generated. The generated data may be transmitted between the plurality of computing systems using the real network connections and measured to determine whether an attack is detected.

  11. The Angle of Attack Control for Air-breathing Hypersonic Cruise Vehicle Based on the Adaptive Sliding Mode with Reference Model%吸气式高超声速巡航飞行器飞行攻角的模型参考自适应滑模控制

    Institute of Scientific and Technical Information of China (English)

    熊柯; 夏智勋; 郭振云

    2011-01-01

    An angle of attack control law for air-breathing hypersonic cruise vehicle is presented.Due to the various dynamics and modeling uncertainties among engine cowl closing, engine cowl opening and engine working, an adaptive parameter adjuster control rule is introduced into the sliding mode control.The adaptive law is used to approximate the model perturbation and external disturbances.This method can effectively improve the performance of dynamics and stable characteristics in the pitch channel, and it also has strong adaptability to the changes of aerodynamic parameters and elevator trimming.The simulation results show that the control method has the excellent tracking-point performance and the strong robustness against the disturbances and the uncertainties.%针对吸气式高超声速巡航飞行器发动机进气道关闭、进气道打开、发动机点火工作3个状态下俯仰通道气动系数和配平舵偏角变化大的特点,设计了一种基于参考模型的自适应滑模攻角控制律.在滑模控制中引入了自适应参数调节律来逼近不确定的模型参数变化和外界干扰,有效地改善了飞行器俯仰通道的动态和稳态性能,同时对于气动系数和配平舵偏角的变化具有自适应性.数学仿真结果表明,所设计的控制律具有良好的指令跟踪性能和抗干扰能力.

  12. Flooding Distributed Denial of Service Attacks-A Review

    Directory of Open Access Journals (Sweden)

    Khadijah W.M. Ghazali

    2011-01-01

    Full Text Available Problem statement: Flaws either in users’ implementation of a network or in the standard specification of protocols has resulted in gaps that allow various kinds of network attack to be launched. Of the kinds of network attacks, denial-of-service flood attacks have caused the most severe impact. Approach: This study reviews recent researches on flood attacks and their mitigation, classifying such attacks as either high-rate flood or low-rate flood. Finally, the attacks are compared against criteria related to their characteristics, methods and impacts. Results: Denial-of-service flood attacks vary in their rates, traffic, targets, goals and impacts. However, they have general similarities that are the methods used are flooding and the main purpose is to achieve denial of service to the target. Conclusion/Recommendations: Mitigation of the denial-of-service flood attacks must correspond to the attack rates, traffic, targets, goals and impacts in order to achieve effective solution.

  13. Fake BTS Attacks of GSM System on Software Radio Platform

    OpenAIRE

    Yubo Song; Kan Zhou; Xi Chen

    2012-01-01

    The 2G GSM communication system only provides one-way authentication mechanism which just authenticate the identities of mobile users. As we know, this is not resistant to fake BTS attack. But for the huge cost for building a fake BTS before, this kind of attack were not really implemented before. This paper presents an implement of fake BTS based on software radio technologies. Furthermore, this paper discusses two types of fake BTS attacks on our software radio platform. The first attack is...

  14. Fake BTS Attacks of GSM System on Software Radio Platform

    Directory of Open Access Journals (Sweden)

    Yubo Song

    2012-02-01

    Full Text Available The 2G GSM communication system only provides one-way authentication mechanism which just authenticate the identities of mobile users. As we know, this is not resistant to fake BTS attack. But for the huge cost for building a fake BTS before, this kind of attack were not really implemented before. This paper presents an implement of fake BTS based on software radio technologies. Furthermore, this paper discusses two types of fake BTS attacks on our software radio platform. The first attack is IMSI/IMEI catch attack, which can get the mobile phone’s IMSI and IMEI. With this information, attacker can got the track of the man with this phone. The second attack is selective jamming attack. After get the IMSI and IMEI of the mobile phone, the attackers can decide whether the mobile phone is blocked or not. We will analyze the GSM protocol which is relevant to the interception system and later present the performance of such a system by real tests and demonstrate its feasibility.

  15. Optimal counterterrorism and the recruitment effect of large terrorist attacks

    DEFF Research Database (Denmark)

    Jensen, Thomas

    2011-01-01

    We analyze a simple dynamic model of the interaction between terrorists and authorities. Our primary aim is to study optimal counterterrorism and its consequences when large terrorist attacks lead to a temporary increase in terrorist recruitment. First, we show that an increase in counterterrorism...... makes it more likely that terrorist cells plan small rather than large attacks and therefore may increase the probability of a successful attack. Analyzing optimal counterterrorism we see that the recruitment effect makes authorities increase the level of counterterrorism after large attacks. Therefore...

  16. An Improved Model of Attack Probability Prediction System

    Institute of Scientific and Technical Information of China (English)

    WANG Hui; LIU Shufen; ZHANG Xinjia

    2006-01-01

    This paper presents a novel probability generation algorithm to predict attacks from an insider who exploits known system vulnerabilities through executing authorized operations. It is different from most intrusion detection systems (IDSs) because these IDSs are inefficient to resolve threat from authorized insiders. To deter cracker activities, this paper introduces an improved structure of augmented attack tree and a notion of "minimal attack tree", and proposes a new generation algorithm of minimal attack tree. We can provide a quantitative approach to help system administrators make sound decision.

  17. Induction of panic attack by stimulation of the ventromedial hypothalamus.

    Science.gov (United States)

    Wilent, W Bryan; Oh, Michael Y; Buetefisch, Cathrin M; Bailes, Julian E; Cantella, Diane; Angle, Cindy; Whiting, Donald M

    2010-06-01

    Panic attacks are sudden debilitating attacks of intense distress often accompanied by physical symptoms such as shortness of breath and heart palpitations. Numerous brain regions, hormones, and neurotransmitter systems are putatively involved, but the etiology and neurocircuitry of panic attacks is far from established. One particular brain region of interest is the ventromedial hypothalamus (VMH). In cats and rats, electrical stimulation delivered to the VMH has been shown to evoke an emotional "panic attack-like" escape behavior, and in humans, stimulation targeting nuclei just posterior or anterior to the VMH has reportedly induced panic attacks. The authors report findings obtained in an awake patient undergoing bilateral implantation of deep brain stimulation electrodes into the hypothalamus that strongly implicates the VMH as being critically involved in the genesis of panic attacks. First, as the stimulating electrode progressed deeper into the VMH, the intensity of stimulation required to evoke an attack systematically decreased; second, while stimulation of the VMH in either hemisphere evoked panic, stimulation that appeared to be in the center of the VMH was more potent. Thus, this evidence supports the role of the VMH in the induction of panic attacks purported by animal studies. PMID:19852539

  18. Prevention Of WormholeAttacks In Geographic Routing Protocol

    Directory of Open Access Journals (Sweden)

    E.Poornima,

    2011-01-01

    Full Text Available As mobile ad hoc network applications are deployed, security emerges as a central requirement..Position aided routing protocols can offer a significant performance increase over traditional ad hoc routing protocols. Boundary State Routing (BSR is a geographic routing protocol which routes the data using the location of the nodes. Geographic routing protocols are known to be particularly susceptible to attacks.. In this paper we present the possible attacks on BSR protocol. One of the most popular and serious attacks in ad hoc networks is wormhole attack in which two or more colluding attackers record packets at one location, and tunnel them to another location for a replay at that remote location. A wormhole attack is very powerful, and preventing the attack has proven to be very difficult. In this paper, we devise efficient methods to detect and avoid wormhole attacks in the BSR protocol. The first method namely Reverse Routing Scheme (RRS attempts to detect the intrusion action .The second technique namely Authentication of Nodes Scheme (ANS uses cryptographic concepts to detect and prevent wormhole attacks. It not only detects the fake route but also adopts preventive measures against action wormhole nodes from reappearing during routing. The proposed system is designed in Boundary state routing (BSRprotocol and analysis and simulations are performed in network simulator (NS-2.

  19. Study of Various Attacks in MANET and Elaborative Discussion Of Rushing Attack on DSR with clustering scheme

    Directory of Open Access Journals (Sweden)

    Rusha Nandy

    2011-07-01

    Full Text Available An ad hoc network is a collection of mobile nodes that dynamically form a temporary network and are capable of communicating with each other without the use of a network infrastructure or any centralized administration. Due to open medium, dynamic topology, distributed cooperation, constrained capabilities ad hoc networks are vulnerable to many types of security attacks; one such attack is rushing attack. It is a malicious attack that is directed against on demand routing protocols that uses duplicate suppression at each node.

  20. Pattern association--a key to recognition of shark attacks.

    Science.gov (United States)

    Cirillo, G; James, H

    2004-12-01

    Investigation of a number of shark attacks in South Australian waters has lead to recognition of pattern similarities on equipment recovered from the scene of such attacks. Six cases are presented in which a common pattern of striations has been noted.

  1. Is There Anybody There? A Psychodynamic View of Panic Attack.

    Science.gov (United States)

    Rizq, Rosemary

    2002-01-01

    Presents a process analysis of a psychodynamic intervention for a client with panic attacks. Discusses how a psychodynamic understanding of the complex etiology of the client's panic attacks that ultimately produced improved coping skills and a subjective sense of improvement for her. Process analysis is used to illustrate the theoretical base,…

  2. Prodromes and predictors of migraine attack.

    Science.gov (United States)

    Rossi, Paolo; Ambrosini, Anna; Buzzi, M Gabriella

    2005-01-01

    Premonitory symptoms of migraine include a wide and heterogeneous collection of cognitive, psychic and physical changes preceding and forewarning of an attack by a few hours to 2-3 days. To date, premonitory symptoms have received little attention in the literature, being treated more as a curiosity than as a primary feature of migraine. This paper provides an extensive critical review of this neglected area of migraine research in the light of the recent advances in our understanding of the pathogenetic mechanisms of migraine. Epidemiological and clinical studies that have investigated the premonitory symptoms of migraine lack scientific rigour, producing conflicting results, whilst genetic and pathophysiological investigations are still in their very early stages. There is evidence supporting the idea that premonitory symptoms could be used as a phenotypical marker to identify subgroups of migraineurs which could show correlations with specific clinical expressions of the disease, genotypes, or responses to treatments. Future studies are needed to clarify the clinical, pathophysiological and therapeutic significance of premonitory symptoms. PMID:16483459

  3. Assessment and treatment of nocturnal panic attacks.

    Science.gov (United States)

    Craske, Michelle G; Tsao, Jennie C I

    2005-06-01

    Nocturnal panic (NP), waking from sleep in a state of panic, is a common occurrence among patients with panic disorder, with 44-71% reporting at least one such attack. NP is a non-REM event that is distinct from sleep terrors, sleep apnea, nightmares or dream-induced arousals. This review outlines recent advances in the characterization of NP, as well as current approaches to the assessment and treatment of NP. In contrast to earlier work, more recent studies suggest that patients with NP do not differ from patients without NP on sleep architecture, sleep physiology, self-reported sleep quality and severity of panic disorder. However, more precise measurement of physiological precipitants and features is warranted. Assessment of NP focuses on ruling out other explanations for NP, with differential diagnosis based on interviews, sleep polysomnography and ambulatory recording of sleep. Psychological treatment (cognitive-behavioral therapy) targets misappraisals of anxiety sensations, hyperventilatory response, and conditioned reactions to internal, physical cues. Recent evidence supports the efficacy of this approach, however, controlled studies on pharmacological agents in the treatment of NP are lacking. Research is needed to examine the effects of combined cognitive-behavioral therapy and medications, compared to medication alone in the treatment of NP. PMID:15893248

  4. Performance evaluation of DSR Protocol under DoS attack

    Directory of Open Access Journals (Sweden)

    Ms. Trupti Patel

    2012-03-01

    Full Text Available A mobile ad-hoc network (MANET consists of mobile hosts equipped with wireless communication devices. A Mobile Ad hoc Network is a self-organizing, infrastructure less, multi-hop network. The transmission of a mobile host is received by all hosts within its transmission range due to the broadcast nature of wireless communication and unidirectional antenna. If two wireless hosts are out of their transmission ranges in the ad hoc networks, other mobile hosts located between them can forward their message, which effectively builds connected networks among the mobile hosts in the deployed area. One main challenge in design of these networks is their vulnerable nature to security attack. These attacks can be deployed by insider or outsider attacker. Sometime, the node from network can be attacker. This is happen because of mobility of nodes and changing network topology. There are different kind of attacks available in literature and can be implemented on MANET. One of these attacks is Grey Hole attack that has dangerous effect on Mobile Ad-Hoc Network. In this paper, we study the effect of Grey Hole attack on Dynamic Source Routing (DSR protocol in Mobile Ad-Hoc Network.

  5. Robustness of Complex Networks under Attack and Repair

    Institute of Scientific and Technical Information of China (English)

    HU Bin; LI Fang; ZHOU Hou-Shun

    2009-01-01

    To study the robustness of complex networks under attack and repair,we introduce a repair model of complex networks.Based on the model,we introduce two new quantities,i.e.attack fraction f_a and the maximum degree of the nodes that have never been attacked K_a,to study analytically the critical attack fraction and the relati ve size of the giant component of complex networks under attack and repair,using the method of generating function.We show analytically and numerically that the repair strategy significantly enhances the robustness of the scale-free network and the effect of robustness improvement is better for the scale-free networks with a smaller degree exponent.We discuss the application of our theory in relation to the understanding of robustness of complex networks with reparability.

  6. Effectiveness of the Call in Beach Volleyball Attacking Play

    Directory of Open Access Journals (Sweden)

    Künzell Stefan

    2014-12-01

    Full Text Available In beach volleyball the setter has the opportunity to give her or his hitter a “call”. The call intends that the setter suggests to her or his partner where to place the attack in the opponent’s court. The effectiveness of a call is still unknown. We investigated the women’s and men’s Swiss National Beach Volleyball Championships in 2011 and analyzed 2185 attacks. We found large differences between female and male players. While men called in only 38.4% of attacks, women used calls in 85.5% of attacks. If the male players followed a given call, 63% of the attacks were successful. The success rate of attacks without any call was 55.8% and 47.6% when the call was ignored. These differences were not significant (χ2(2 = 4.55, p = 0.103. In women’s beach volleyball, the rate of successful attacks was 61.5% when a call was followed, 35% for attacks without a call, and 42.6% when a call was ignored. The differences were highly significant (χ2(2 = 23.42, p < 0.0005. Taking into account the findings of the present study, we suggested that the call was effective in women’s beach volleyball, while its effect in men’s game was unclear. Considering the quality of calls we indicate that there is a significant potential to increase the effectiveness of a call.

  7. Treatment of HAE Attacks in the Icatibant Outcome Survey

    DEFF Research Database (Denmark)

    Hernández Fernandez de Rojas, Dolores; Ibañez, Ethel; Longhurst, Hilary;

    2015-01-01

    BACKGROUND: Icatibant, a selective bradykinin B2 receptor antagonist for the treatment of acute hereditary angio-oedema (HAE) attacks in adults, can be administered by health care professionals (HCPs) or self-administered. This analysis compared characteristics and outcomes of acute HAE attacks t...

  8. Strategies and scenarios of CSRF attacks against the CAPTCHA forms

    Directory of Open Access Journals (Sweden)

    Hossein Moradi

    2015-01-01

    Full Text Available In this article, we’ve tried to examine the hypothesis of the robustness of a form by using CAPTCHA against CSRF and login CSRF attacks. Our investigations showed that unlike public opinion, common attacks to bypass CAPTCHAs such as Optical Character Recognition (OCR and 3rd party human attacks are not applicable in the CSRF case and instead, Clickjacking is the most important scenario of CSRF and login CSRF attacks against a secure session-dependent CAPTCHA form. Remember that the Clickjacking is also applicable to bypass the well-known CSRF protections, such as the secret token and the Referer header. Therefore, although the frequent application of CAPTCHA on every page of a website negatively impacts the user experience, but the robustness of a robust session-dependent CAPTCHA against the CSRF and login CSRF attacks is almost the same as the session-dependent security token. Moreover, when a website is using a session-independent or week pattern of CAPTCHA, attackers can bypass the CAPTCHAs and launch the CSRF or login CSRF attacks by using XSS, session hijacking, replay attacks or submitting a random response.

  9. Optimal attack strategy of complex networks based on tabu search

    Science.gov (United States)

    Deng, Ye; Wu, Jun; Tan, Yue-jin

    2016-01-01

    The problem of network disintegration has broad applications and recently has received growing attention, such as network confrontation and disintegration of harmful networks. This paper presents an optimized attack strategy model for complex networks and introduces the tabu search into the network disintegration problem to identify the optimal attack strategy, which is a heuristic optimization algorithm and rarely applied to the study of network robustness. The efficiency of the proposed solution was verified by comparing it with other attack strategies used in various model networks and real-world network. Numerical experiments suggest that our solution can improve the effect of network disintegration and that the "best" choice for node failure attacks can be identified through global searches. Our understanding of the optimal attack strategy may also shed light on a new property of the nodes within network disintegration and deserves additional study.

  10. Survey of Attacks on Mobile AdhocWireless Networks

    Directory of Open Access Journals (Sweden)

    Vikas Solomon Abel

    2011-02-01

    Full Text Available Security has always been a key issue with wireless networks since there are no physical boundaries. Experience has shown numerous vulnerabilities to a variety of attacks even when security measures are in place. In the combined Internet-MANET environment also security is an important issue keeping in view the Internet connectivity and attack on the MANET protocols.

  11. Randomized, controlled trial of telcagepant over four migraine attacks

    DEFF Research Database (Denmark)

    Ho, Andrew P; Dahlöf, Carl Gh; Silberstein, Stephen D;

    2010-01-01

    This study evaluated the calcitonin gene-related peptide (CGRP) receptor antagonist telcagepant (tablet formulation) for treatment of a migraine attack and across four attacks. Adults with migraine were randomized, double-blind, to telcagepant 140 mg, telcagepant 280 mg, or control treatment sequ...

  12. A Survey of Man in the Middle Attacks

    DEFF Research Database (Denmark)

    Conti, Mauro; Dragoni, Nicola; Lesyk, Viktor

    2016-01-01

    The Man-In-The-Middle (MITM) attack is one of the most well known attacks in computer security, representing one of the biggest concerns for security professionals. MITM targets the actual data that flows between endpoints, and the confidentiality and integrity of the data itself. In this paper, we...... extensively review the literature on MITM to analyse and categorize the scope of MITM attacks, considering both a reference model, such as the open systems interconnection (OSI) model, as well as two specific widely used network technologies, i.e., GSM and UMTS. In particular, we classify MITM attacks based...... on several parameters, like location of an attacker in the network, nature of a communication channel, and impersonation techniques. Based on an impersonation techniques classification, we then provide execution steps for each MITM class. We survey existing countermeasures and discuss the comparison among...

  13. Opening Angles of Collapsar Jets

    OpenAIRE

    Mizuta, Akira; Ioka, Kunihito

    2013-01-01

    We investigate the jet propagation and breakout from the stellar progenitor for gamma-ray burst (GRB) collapsars by performing two-dimensional relativistic hydrodynamic simulations and analytical modeling. We find that the jet opening angle is given by $\\theta_j \\sim 1/5 \\Gamma_{0}$, and infer the initial Lorentz factor of the jet at the central engine, $\\Gamma_0$, is a few for existing observations of $\\theta_j$. The jet keeps the Lorentz factor low inside the star by converging cylindricall...

  14. The research of DPA attacks against AES implementations

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This article examines vulnerabilities to power analysis attacks between software and hardware implementations of cryptographic algorithms. Representative platforms including an Atmel 89S8252 8-bit processor and a 0.25 μm 1.8 v standard cell circuit are proposed to implement the advance encryption standard (AES). A simulation-based experimental environment is built to acquire power data, and single-bit differential power analysis (DPA), and multi-bit DPA and correlation power analysis (CPA) attacks are conducted on two implementations respectively. The experimental results show that the hardware implementation has less data-dependent power leakages to resist power attacks. Furthermore, an improved DPA approach is proposed. It adopts hamming distance of intermediate results as power model and arranges plaintext inputs to differentiate power traces to the maximal probability. Compared with the original power attacks, our improved DPA performs a successful attack on AES hardware implementations with acceptable power measurements and fewer computations.

  15. Metrics for Assessment of Smart Grid Data Integrity Attacks

    Energy Technology Data Exchange (ETDEWEB)

    Annarita Giani; Miles McQueen; Russell Bent; Kameshwar Poolla; Mark Hinrichs

    2012-07-01

    There is an emerging consensus that the nation’s electricity grid is vulnerable to cyber attacks. This vulnerability arises from the increasing reliance on using remote measurements, transmitting them over legacy data networks to system operators who make critical decisions based on available data. Data integrity attacks are a class of cyber attacks that involve a compromise of information that is processed by the grid operator. This information can include meter readings of injected power at remote generators, power flows on transmission lines, and relay states. These data integrity attacks have consequences only when the system operator responds to compromised data by redispatching generation under normal or contingency protocols. These consequences include (a) financial losses from sub-optimal economic dispatch to service loads, (b) robustness/resiliency losses from placing the grid at operating points that are at greater risk from contingencies, and (c) systemic losses resulting from cascading failures induced by poor operational choices. This paper is focused on understanding the connections between grid operational procedures and cyber attacks. We first offer two examples to illustrate how data integrity attacks can cause economic and physical damage by misleading operators into taking inappropriate decisions. We then focus on unobservable data integrity attacks involving power meter data. These are coordinated attacks where the compromised data are consistent with the physics of power flow, and are therefore passed by any bad data detection algorithm. We develop metrics to assess the economic impact of these attacks under re-dispatch decisions using optimal power flow methods. These metrics can be use to prioritize the adoption of appropriate countermeasures including PMU placement, encryption, hardware upgrades, and advance attack detection algorithms.

  16. Serial analysis of gene expression predicts structural differences in hippocampus of long attack latency and short attack latency mice

    NARCIS (Netherlands)

    Feldker, DEM; Datson, NA; Veenema, AH; Meulmeester, E; de Kloet, ER; Vreugdenhil, E

    2003-01-01

    The genetically selected long attack latency (LAL) and short attack latency (SAL) mice differ in a wide variety of behavioural traits and display differences in the serotonergic system and the hypothalamus-pituitary-adrenocortical (HPA)-axis. Serial analysis of gene expression (SAGE) was used to gen

  17. Cross-correlation Based Synchronization Mechanism of LDDoS Attacks

    Directory of Open Access Journals (Sweden)

    Zhijun WU

    2014-03-01

    Full Text Available A success Low-rate Distributed Denial of Service (LDDoS attack is composed of many single sources of Low-rate Denial of Service (LDoS attacks, which are well-organized in time synchronization to aggregate the attack flow at the end of target router. This paper addresses time synchronization and flow aggregation in LDDoS attacks for the purpose of exploring the attack performance. A cross-correlation algorithm is proposed to guarantee all network-wide distributed attack pulses aggregate at the victim end with a strict time limitation to form a powerful attack pulse. Experiments on the attack performance of LDoS and LDDoS attack are performed in NS-2 simulation platform. Experiment results show that the LDDoS attack effects can be improved significantly by using cross-correlation algorithm to coordinate attack pulses, which obtain better attack performance than many single dependent attack pulses. 

  18. The qualitative criterion of transient angle stability

    OpenAIRE

    Lyu, R; Xue, Y.; Xue, F; Wu, Qiuwei; Yang, Guangya; Zhou, H; Ju, P.

    2015-01-01

    In almost all the literatures, the qualitative assessment of transient angle stability extracts the angle information of generators based on the swing curve. As the angle (or angle difference) of concern and the threshold value rely strongly on the engineering experience, the validity and robust of these criterions are weak. Based on the stability mechanism from the extended equal area criterion (EEAC) theory and combining with abundant simulations of real system, this paper analyzes the crit...

  19. Personality characteristics of victims of illegal attacks on the Internet

    Directory of Open Access Journals (Sweden)

    Safuanov F.S.

    2016-01-01

    Full Text Available The article examines the personality characteristics of victims of illegal attacks on the Internet. We used methods as follow: 16 factors Cattell personality questionnaire, subjective control level, life-style index, Buss-Perry questionnaire, Spielberger State-Trait Anxiety Inventory, a COPE inventory. 78 internet users were divided into two groups of 38 persons: the main group included people falling victim to illegal attacks on the Internet, the control group participants were not attacked on the internet. We identified specific aggregated symptoms of individual psychological characteristics of internet attack victims and show that victims of "non-forced" and "forced" offenses have different levels of situational and personal anxiety, aggression and locus of control.

  20. Visual Simulation of Missile Attacking Battleplane Based on Vega

    Directory of Open Access Journals (Sweden)

    Zhang Huibing

    2013-07-01

    Full Text Available A visual simulation system of fragment warhead missile attacking F-16C ''Falcon'' battleplane based on simulation and virtual reality technology is put forward. Firstly, the overall design of visual simulation of missile attacking F16 battleplane is implemented, and all functions of each module are demonstrated in detailed. Then 3D models in virtual battle field are optimized by level of detail, texture mapping, billboard and instance technology. Finally, Vega scene driving program is developed, and the implementation of special effect, view transform, preview and collision detect are emphasized. The result of simulation provides reference for damage assessment of missile attacking F16 battleplane.

  1. AMC Model for Denial of Sleep Attack Detection

    CERN Document Server

    Bhattasali, Tapalina

    2012-01-01

    Due to deployment in hostile environment, wireless sensor network is vulnerable to various attacks. Exhausted sensor nodes in sensor network become a challenging issue because it disrupts the normal connectivity of the network. Affected nodes give rise to denial of service that resists to get the objective of sensor network in real life. A mathematical model based on Absorbing Markov Chain (AMC)is proposed for Denial of Sleep attack detection in sensor network. In this mechanism, whether sensor network is affected by denial of sleep attack or not can be decided by considering expected death time of sensor network under normal scenario.

  2. Distributed denial of service attacks : Protection, Mitigation, and Economic Consequences

    OpenAIRE

    Eklund, Martin; Ståhlberg, Patrik

    2015-01-01

    Distributed Denial of Service attacks is a problem that constantly threatens companies that rely on the internet for major parts of their business. A successful DDoS attack that manages to penetrate a company’s network can lead to devastating damages in the form of lost income, reduced productivity, increase in costs, and damage to the company’s image and reputation. The different DDoS attacks are many and of different character and often Offer different parts of the network, which makes it v...

  3. The LOCAL attack: Cryptanalysis of the authenticated encryption scheme ALE

    DEFF Research Database (Denmark)

    Khovratovich, Dmitry; Rechberger, Christian

    2014-01-01

    We show how to produce a forged (ciphertext, tag) pair for the scheme ALE with data and time complexity of 2102 ALE encryptions of short messages and the same number of authentication attempts. We use a differential attack based on a local collision, which exploits the availability of extracted...... state bytes to the adversary. Our approach allows for a time-data complexity tradeoff, with an extreme case of a forgery produced after 2119 attempts and based on a single authenticated message. Our attack is further turned into a state recovery and a universal forgery attack with a time complexity...

  4. Recurrence of Panic Attacks after Influenza Vaccination: Two Case Reports

    Science.gov (United States)

    Kim, Han-Joon; Jeon, Sang-Won; Yoon, Ho-Kyoung

    2016-01-01

    Human influenza is a contagious respiratory illness caused by the influenza virus. The influenza vaccination is recommended annually, but several adverse effects related to allergic reactions have been reported. Panic attacks are also known to occur, but no case of a panic attack adverse effect has been reported in South Korea. We present two cases of panic disorder patients whose symptoms were aggravated by the influenza vaccination. We assumed that dysregulation of T-lymphocytes in panic disorder patients could have a role in activating various kinds of cytokines and chemokines, which then can lead to panic attack aggravation. PMID:27776395

  5. Blind Recognition of Touched Keys: Attack and Countermeasures

    OpenAIRE

    Yue, Qinggang; Ling, Zhen; Liu, Benyuan; Fu, Xinwen; Zhao, Wei

    2014-01-01

    In this paper, we introduce a novel computer vision based attack that discloses inputs on a touch enabled device, while the attacker cannot see any text or popups from a video of the victim tapping on the touch screen. In the attack, we use the optical flow algorithm to identify touching frames where the finger touches the screen surface. We innovatively use intersections of detected edges of the touch screen to derive the homography matrix mapping the touch screen surface in video frames to ...

  6. The Attack and Defense of Weakest-Link Networks

    OpenAIRE

    Kovenock, Dan; Roberson, Brian; Sheremeta, Roman M.

    2010-01-01

    This paper experimentally examines behavior in a two-player game of attack and defense of a weakest-link network of targets, in which the attacker’s objective is to successfully attack at least one target and the defender’s objective is diametrically opposed. We apply two benchmark contest success functions (CSFs): the auction CSF and the lottery CSF. Consistent with the theoretical prediction, under the auction CSF, attackers utilize a stochastic “guerilla warfare” strategy — in which a sing...

  7. Effect of Black Hole Attack on MANET Routing Protocols

    Directory of Open Access Journals (Sweden)

    Jaspal Kumar

    2013-04-01

    Full Text Available Due to the massive existing vulnerabilities in mobile ad-hoc networks, they may be insecure against attacks by the malicious nodes. In this paper we have analyzed the effects of Black hole attack on mobile ad hoc routing protocols. Mainly two protocols AODV and Improved AODV have been considered. Simulation has been performed on the basis of performance parameters and effect has been analyzed after adding Black-hole nodes in the network. Finally the results have been computed and compared to stumble on which protocol is least affected by these attacks.

  8. Analysis of the Fault Attack ECDLP over Prime Field

    Directory of Open Access Journals (Sweden)

    Mingqiang Wang

    2011-01-01

    Full Text Available In 2000, Biehl et al. proposed a fault-based attack on elliptic curve cryptography. In this paper, we refined the fault attack method. An elliptic curve E is defined over prime field p with base point P∈E(p. Applying the fault attack on these curves, the discrete logarithm on the curve can be computed in subexponential time of Lp(1/2,1+o(1. The runtime bound relies on heuristics conjecture about smooth numbers similar to the ones used by Lenstra, 1987.

  9. Enhancement of scale-free network attack tolerance

    Institute of Scientific and Technical Information of China (English)

    Qu Ze-Hui; Wang Pu; Song Chao-Ming; Qin Zhi-Guang

    2010-01-01

    Despite the large size of most communication and transportation systems, there are short paths between nodes in these networks which guarantee the efficient information, data and passenger delivery; furthermore these networks have a surprising tolerance under random errors thanks to their inherent scale-free topology. However, their scale-free topology also makes them fragile under intentional attacks, leaving us a challenge on how to improve the network robustness against intentional attacks without losing their strong tolerance under random errors and high message and passenger delivering capacity. Here we propose two methods (SL method and SH method) to enhance scale-free network's tolerance under attack in different conditions.

  10. An Improvement of GNY Logic for the Reflection Attacks

    Institute of Scientific and Technical Information of China (English)

    DING Yiqiang

    1999-01-01

    In this paper, the limitation of the GNY logic about its inability to detect the reflection attacks againstsome authentication protocols is given. An improvement is proposed whichtakes into account the possible multiple instances (principals) of thesame identity in the model.

  11. Attack surfaces

    DEFF Research Database (Denmark)

    Gruschka, Nils; Jensen, Meiko

    2010-01-01

    The new paradigm of cloud computing poses severe security risks to its adopters. In order to cope with these risks, appropriate taxonomies and classification criteria for attacks on cloud computing are required. In this work-in-progress paper we present one such taxonomy based on the notion...... of attack surfaces of the cloud computing scenario participants. © 2010 IEEE....

  12. Assessing the effects of honeypots on cyber-attackers

    OpenAIRE

    Lim, Sze Li Harry

    2006-01-01

    A honeypot is a non-production system, design to interact with cyber-attackers to collect intelligence on attack techniques and behaviors. While the security community is reaping fruits of this collection tool, the hacker community is increasingly aware of this technology. In response, they develop anti-honeypot technology to detect and avoid honeypots. Prior to the discovery of newer intelligence collection tools, we need to maintain the relevancy of honeypot. Since the development of a...

  13. Heart Attack

    Science.gov (United States)

    ... a million people in the U.S. have a heart attack. About half of them die. Many people have permanent heart damage or die because they don't get ... It's important to know the symptoms of a heart attack and call 9-1-1 if someone ...

  14. Evaluation of Security Attacks on UMTS Authentication Mechanism

    Directory of Open Access Journals (Sweden)

    Mojtaba Ayoubi Mobarhan

    2012-08-01

    Full Text Available In this study security of internet access over the Third Generation (3G telecommunication systems is considered and Universal Mobile Telecommunications System (UMTS is selected as the most popular system among 3G systems. The study then focuses on network access security mechanism of UMTS, called Authentication and Key Agreement (AKA. In addition, twenty types of important attacks and threats in UMTS system are presented and classified based on three major security factors; authentication, confidentiality, and data integrity. The evaluations finally show that the authentication factor is more interesting than other factors for hackers. Then, we describe four attacks named; man-inthe-middle, denial of service, identity catching, and redirection as the most significant attacks against authentication mechanism. Furthermore, we provide some solutions and methods to improve AKA mechanism and prevent these attacks in UMTS system.

  15. Analysis and mitigation of new network attack types

    OpenAIRE

    Hribar, Klemen

    2014-01-01

    Network security is an area that needs to be constantly monitored. New forms of network attacks are being discovered and can be divided into several categories. New forms of computer vulnerability can be monitored in various ways. It is important to rapidly discover ways to eliminate vulnerabilities and prevent their abuse. In the thesis, we have set ourselves the aim to conduct a review of recent network attacks and seek measures to prevent them. For this purpose, we have produced a short ov...

  16. A Comparative Study of Power Consumption Models for CPA Attack

    OpenAIRE

    Hassen Mestiri; Noura Benhadjyoussef; Mohsen Machhout; Rached Tourki

    2013-01-01

    Power analysis attacks are types of side channel attacks that are based on analyzing the power consumption of the cryptographic devices. Correlation power analysis is a powerful and efficient cryptanalytic technique. It exploits the linear relation between the predicted power consumption and the real power consumption of cryptographic devices in order to recover the correct key. The predicted power consumption is determined by using the appropriate consumption model. Until now, only a few mod...

  17. Analysis of Topology Poisoning Attacks in Software-Defined Networking

    OpenAIRE

    Thanh Bui, Tien

    2015-01-01

    Software-defined networking (SDN) is an emerging architecture with a great potential to foster the development of modern networks. By separating the control plane from the network devices and centralizing it at a software-based controller, SDN provides network-wide visibility and flexible programmability to network administrators. However, the security aspects of SDN are not yet fully understood. For example, while SDN is resistant to some topology poisoning attacks in which the attacker misl...

  18. Vulnerability of water supply systems to cyber-physical attacks

    Science.gov (United States)

    Galelli, Stefano; Taormina, Riccardo; Tippenhauer, Nils; Salomons, Elad; Ostfeld, Avi

    2016-04-01

    The adoption of smart meters, distributed sensor networks and industrial control systems has largely improved the level of service provided by modern water supply systems. Yet, the progressive computerization exposes these critical infrastructures to cyber-physical attacks, which are generally aimed at stealing critical information (cyber-espionage) or causing service disruption (denial-of-service). Recent statistics show that water and power utilities are undergoing frequent attacks - such as the December power outage in Ukraine - , attracting the interest of operators and security agencies. Taking the security of Water Distribution Networks (WDNs) as domain of study, our work seeks to characterize the vulnerability of WDNs to cyber-physical attacks, so as to conceive adequate defense mechanisms. We extend the functionality of EPANET, which models hydraulic and water quality processes in pressurized pipe networks, to include a cyber layer vulnerable to repeated attacks. Simulation results on a medium-scale network show that several hydraulic actuators (valves and pumps, for example) can be easily attacked, causing both service disruption - i.e., water spillage and loss of pressure - and structural damages - e.g., pipes burst. Our work highlights the need for adequate countermeasures, such as attacks detection and reactive control systems.

  19. Impact modeling and prediction of attacks on cyber targets

    Science.gov (United States)

    Khalili, Aram; Michalk, Brian; Alford, Lee; Henney, Chris; Gilbert, Logan

    2010-04-01

    In most organizations, IT (information technology) infrastructure exists to support the organization's mission. The threat of cyber attacks poses risks to this mission. Current network security research focuses on the threat of cyber attacks to the organization's IT infrastructure; however, the risks to the overall mission are rarely analyzed or formalized. This connection of IT infrastructure to the organization's mission is often neglected or carried out ad-hoc. Our work bridges this gap and introduces analyses and formalisms to help organizations understand the mission risks they face from cyber attacks. Modeling an organization's mission vulnerability to cyber attacks requires a description of the IT infrastructure (network model), the organization mission (business model), and how the mission relies on IT resources (correlation model). With this information, proper analysis can show which cyber resources are of tactical importance in a cyber attack, i.e., controlling them enables a large range of cyber attacks. Such analysis also reveals which IT resources contribute most to the organization's mission, i.e., lack of control over them gravely affects the mission. These results can then be used to formulate IT security strategies and explore their trade-offs, which leads to better incident response. This paper presents our methodology for encoding IT infrastructure, organization mission and correlations, our analysis framework, as well as initial experimental results and conclusions.

  20. ROPocop - Dynamic Mitigation of Code-Reuse Attacks

    OpenAIRE

    Follner, Andreas; Bodden, Eric

    2015-01-01

    Control-flow attacks, usually achieved by exploiting a buffer-overflow vulnerability, have been a serious threat to system security for over fifteen years. Researchers have answered the threat with various mitigation techniques, but nevertheless, new exploits that successfully bypass these technologies still appear on a regular basis. In this paper, we propose ROPocop, a novel approach for detecting and preventing the execution of injected code and for mitigating code-reuse attacks such as re...

  1. Modeling Partial Attacks with Alloy (Transcript of Discussion)

    Science.gov (United States)

    Lin, Amerson

    The reason we went into this research, was that we found that partial attacks were extremely hard to model in terms of a language that could be used by an automated tool. Now there are three reasons why this is so. The first is that it is hard to identify these attacks even by hand, because you have to be really creative in thinking, what constitutes a reduction in entropy of the secret, that is significant, because a partial attack is really anything that reduces entropy, it's just that it does not reduce the entropy to zero, which would be a case of a complete attack. Next, it's hard to describe that in a formal language, part of that problem comes from the definition, you have to define what you want to be the goal, if the secret is the entire password, then getting one letter is pretty much a partial attack, but if the secret is that one letter, then getting that one letter is a complete attack. And lastly, applying that logic, how do you measure entropy, how do you measure information leakage, that's also very difficult.

  2. Impact of Degree Heterogeneity on Attack Vulnerability of Interdependent Networks.

    Science.gov (United States)

    Sun, Shiwen; Wu, Yafang; Ma, Yilin; Wang, Li; Gao, Zhongke; Xia, Chengyi

    2016-01-01

    The study of interdependent networks has become a new research focus in recent years. We focus on one fundamental property of interdependent networks: vulnerability. Previous studies mainly focused on the impact of topological properties upon interdependent networks under random attacks, the effect of degree heterogeneity on structural vulnerability of interdependent networks under intentional attacks, however, is still unexplored. In order to deeply understand the role of degree distribution and in particular degree heterogeneity, we construct an interdependent system model which consists of two networks whose extent of degree heterogeneity can be controlled simultaneously by a tuning parameter. Meanwhile, a new quantity, which can better measure the performance of interdependent networks after attack, is proposed. Numerical simulation results demonstrate that degree heterogeneity can significantly increase the vulnerability of both single and interdependent networks. Moreover, it is found that interdependent links between two networks make the entire system much more fragile to attacks. Enhancing coupling strength between networks can greatly increase the fragility of both networks against targeted attacks, which is most evident under the case of max-max assortative coupling. Current results can help to deepen the understanding of structural complexity of complex real-world systems. PMID:27609483

  3. Impact of Degree Heterogeneity on Attack Vulnerability of Interdependent Networks

    Science.gov (United States)

    Sun, Shiwen; Wu, Yafang; Ma, Yilin; Wang, Li; Gao, Zhongke; Xia, Chengyi

    2016-09-01

    The study of interdependent networks has become a new research focus in recent years. We focus on one fundamental property of interdependent networks: vulnerability. Previous studies mainly focused on the impact of topological properties upon interdependent networks under random attacks, the effect of degree heterogeneity on structural vulnerability of interdependent networks under intentional attacks, however, is still unexplored. In order to deeply understand the role of degree distribution and in particular degree heterogeneity, we construct an interdependent system model which consists of two networks whose extent of degree heterogeneity can be controlled simultaneously by a tuning parameter. Meanwhile, a new quantity, which can better measure the performance of interdependent networks after attack, is proposed. Numerical simulation results demonstrate that degree heterogeneity can significantly increase the vulnerability of both single and interdependent networks. Moreover, it is found that interdependent links between two networks make the entire system much more fragile to attacks. Enhancing coupling strength between networks can greatly increase the fragility of both networks against targeted attacks, which is most evident under the case of max-max assortative coupling. Current results can help to deepen the understanding of structural complexity of complex real-world systems.

  4. Robustness of network of networks under targeted attack

    Science.gov (United States)

    Dong, Gaogao; Gao, Jianxi; Du, Ruijin; Tian, Lixin; Stanley, H. Eugene; Havlin, Shlomo

    2013-05-01

    The robustness of a network of networks (NON) under random attack has been studied recently [Gao , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.195701 107, 195701 (2011)]. Understanding how robust a NON is to targeted attacks is a major challenge when designing resilient infrastructures. We address here the question how the robustness of a NON is affected by targeted attack on high- or low-degree nodes. We introduce a targeted attack probability function that is dependent upon node degree and study the robustness of two types of NON under targeted attack: (i) a tree of n fully interdependent Erdős-Rényi or scale-free networks and (ii) a starlike network of n partially interdependent Erdős-Rényi networks. For any tree of n fully interdependent Erdős-Rényi networks and scale-free networks under targeted attack, we find that the network becomes significantly more vulnerable when nodes of higher degree have higher probability to fail. When the probability that a node will fail is proportional to its degree, for a NON composed of Erdős-Rényi networks we find analytical solutions for the mutual giant component P∞ as a function of p, where 1-p is the initial fraction of failed nodes in each network. We also find analytical solutions for the critical fraction pc, which causes the fragmentation of the n interdependent networks, and for the minimum average degree k¯min below which the NON will collapse even if only a single node fails. For a starlike NON of n partially interdependent Erdős-Rényi networks under targeted attack, we find the critical coupling strength qc for different n. When q>qc, the attacked system undergoes an abrupt first order type transition. When q≤qc, the system displays a smooth second order percolation transition. We also evaluate how the central network becomes more vulnerable as the number of networks with the same coupling strength q increases. The limit of q=0 represents no dependency, and the results are consistent with

  5. Generating IDS Attack Pattern Automatically Based on Attack Tree

    Institute of Scientific and Technical Information of China (English)

    向尕; 曹元大

    2003-01-01

    Generating attack pattern automatically based on attack tree is studied. The extending definition of attack tree is proposed. And the algorithm of generating attack tree is presented. The method of generating attack pattern automatically based on attack tree is shown, which is tested by concrete attack instances. The results show that the algorithm is effective and efficient. In doing so, the efficiency of generating attack pattern is improved and the attack trees can be reused.

  6. A Strategic Analysis of Information Sharing Among Cyber Attackers

    Directory of Open Access Journals (Sweden)

    Kjell Hausken

    2015-10-01

    Full Text Available We build a game theory model where the market design is such that one firm invests in security to defend against cyber attacks by two hackers. The firm has an asset, which is allocated between the three market participants dependent on their contest success. Each hacker chooses an optimal attack, and they share information with each other about the firm’s vulnerabilities. Each hacker prefers to receive information, but delivering information gives competitive advantage to the other hacker. We find that each hacker’s attack and information sharing are strategic complements while one hacker’s attack and the other hacker’s information sharing are strategic substitutes. As the firm’s unit defense cost increases, the attack is inverse U-shaped and reaches zero, while the firm’s defense and profit decrease, and the hackers’ information sharing and profit increase. The firm’s profit increases in the hackers’ unit cost of attack, while the hackers’ information sharing and profit decrease. Our analysis also reveals the interesting result that the cumulative attack level of the hackers is not affected by the effectiveness of information sharing between them and moreover, is also unaffected by the intensity of joint information sharing. We also find that as the effectiveness of information sharing between hackers increases relative to the investment in attack, the firm’s investment in cyber security defense and profit are constant, the hackers’ investments in attacks decrease, and information sharing levels and hacker profits increase. In contrast, as the intensity of joint information sharing increases, while the firm’s investment in cyber security defense and profit remain constant, the hackers’ investments in attacks increase, and the hackers’ information sharing levels and profits decrease. Increasing the firm’s asset causes all the variables to increase linearly, except information sharing which is constant. We extend

  7. The qualitative criterion of transient angle stability

    DEFF Research Database (Denmark)

    Lyu, R.; Xue, Y.; Xue, F.;

    2015-01-01

    In almost all the literatures, the qualitative assessment of transient angle stability extracts the angle information of generators based on the swing curve. As the angle (or angle difference) of concern and the threshold value rely strongly on the engineering experience, the validity and robust of...... these criterions are weak. Based on the stability mechanism from the extended equal area criterion (EEAC) theory and combining with abundant simulations of real system, this paper analyzes the criterions in most literatures and finds that the results could be too conservative or too optimistic. It is...

  8. Panic disorder, panic attacks and panic attack symptoms across race-ethnic groups: results of the collaborative psychiatric epidemiology studies.

    Science.gov (United States)

    Asnaani, Anu; Gutner, Cassidy A; Hinton, Devon E; Hofmann, Stefan G

    2009-01-01

    The current study investigates race-ethnic differences in rates of panic disorder, panic attacks and certain panic attack symptoms by jointly combining three major national epidemiological databases. The compared groups were White, African American, Latino and Asian. The White group had significantly higher rates of panic disorder, and of many panic symptoms, including palpitations, as compared to the African American, Asian and Latino groups. Several expected race-ethnic differences were not found. An explanation for these findings are adduced, and suggestions are given for future studies so that possible ethnic-racial differences in panic disorder, panic attacks and panic attack symptoms can be investigated in a more rigorous manner. PMID:19691544

  9. Value of ABCD2-F in Predicting Cerebral Ischemic Attacks: Three Months Follow-Up after the Primary Attack.

    Science.gov (United States)

    Chardoli, Mojtaba; Firoozabadi, Nader H; Nouri, Mohsen; Rahimi-Movaghar, Vafa

    2016-06-01

    Cerebrovascular attack (CVA) and transient ischemic attack (TIA) are major causes of emergency department visits around the globe. A significant number of these patients may experience repeat attacks if left untreated. Several risk stratifying scoring systems have been developed in recent years to point out the high risk patients. ABCD2 is based on age, blood pressure, clinical status, diabetes mellitus, and duration of symptoms and is used commonly for this purpose. In this study, we were to enhance its sensitivity and specificity with the addition of another criterion namely atrial fibrillation and making ABCD2-F. A prospective study in two hospitals was performed and 138 patients diagnosed with TIA/CVA were enrolled. Demographic, clinical, and paraclinical data of all patients were registered. All patients were followed for three months for any sign or symptom of a recurrent ischemic attack. Recurrent ischemic attacks happened in 9.4% of the patients. None of the criteria of ABCD2-F was associated with higher chance of ischemic attacks. Similarly, ABCD2-F was not different between patients with or without repeat cerebral ischemia. The addition of atrial fibrillation to ABCD2 did not enhance the accuracy of this scoring system to detect patients high risk for repeat cerebral ischemia. More studies in the future to improve sensitivity and specificity of this test are warranted. PMID:27306346

  10. Behavior of Tilted Angle Shear Connectors.

    Directory of Open Access Journals (Sweden)

    Koosha Khorramian

    Full Text Available According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type.

  11. Formalized Description of Distributed Denial of Service Attack

    Institute of Scientific and Technical Information of China (English)

    杜彦辉; 马锐; 刘玉树

    2004-01-01

    The distributed denial of service (DDoS) attack is one of the dangers in intrusion modes. It's difficult to defense and can cause serious damage to the system. Based on a careful study of the attack principles and characteristics, an object-oriented formalized description is presented, which contains a three-level framework and offers full specifications of all kinds of DDoS modes and their features and the relations between one another. Its greatest merit lies in that it contributes to analyzing, checking and judging DDoS. Now this formalized description has been used in a special IDS and it works very effectively.

  12. Performance Comparison of Routing Attacks in Manet and WSN

    Directory of Open Access Journals (Sweden)

    Shyamala Ramachandran

    2012-08-01

    Full Text Available Routing is a basic step for data exchange. In wirel ess ad-hoc networks each node acts as a router and executes a routing protocol. Wireless ad-hoc networ ks are highly resource constrained in terms of network topology, memory and computation power. The reliable data transfer is a difficult task in wireless ad-hoc networks because of resource constr aints. A mobile ad-hoc network (MANET is a kind of wireless ad-hoc network, and is a self-configuri ng network of mobile routers connected by wireless links. A wireless sensor network (WSN is a highly constrained wireless ad-hoc network. In these network, multicast is the efficient routing service for data broadcasting. Denial of service (DOS att ack, sinkhole, wormhole, sybil, black hole and rushing a ttacks are some routing attacks. So, it is necessar y to study the impact of routing attacks on existing mul ticast routing protocols to suggest a suitable secu re multicast routing protocol. The objective of this p aper is to study the effects of black hole and rush ing attack on MANET and WSN. The NS-2 based simulation is used in analyzing the black hole and rushing attacks. From performance metrics such as packet de livery ratio (PDR, packet drop ratio (PDrR, network throughput (NTh and energy consumption it is observed that the routing attacks have severe impact on MANET than WSN.

  13. Heart Attack Recovery FAQs

    Science.gov (United States)

    ... Pressure High Blood Pressure Tools & Resources Stroke More Heart Attack Recovery FAQs Updated:Aug 24,2016 Most people ... recovery. View an animation of a heart attack . Heart Attack Recovery Questions and Answers What treatments will I ...

  14. Myocardial perfusion imaging study of CO(2)-induced panic attack.

    Science.gov (United States)

    Soares-Filho, Gastão L F; Machado, Sergio; Arias-Carrión, Oscar; Santulli, Gaetano; Mesquita, Claudio T; Cosci, Fiammetta; Silva, Adriana C; Nardi, Antonio E

    2014-01-15

    Chest pain is often seen alongside with panic attacks. Moreover, panic disorder has been suggested as a risk factor for cardiovascular disease and even a trigger for acute coronary syndrome. Patients with coronary artery disease may have myocardial ischemia in response to mental stress, in which panic attack is a strong component, by an increase in coronary vasomotor tone or sympathetic hyperactivity setting off an increase in myocardial oxygen consumption. Indeed, coronary artery spasm was presumed to be present in cases of cardiac ischemia linked to panic disorder. These findings correlating panic disorder with coronary artery disease lead us to raise questions about the favorable prognosis of chest pain in panic attack. To investigate whether myocardial ischemia is the genesis of chest pain in panic attacks, we developed a myocardial perfusion study through research by myocardial scintigraphy in patients with panic attacks induced in the laboratory by inhalation of 35% carbon dioxide. In conclusion, from the data obtained, some hypotheses are discussed from the viewpoint of endothelial dysfunction and microvascular disease present in mental stress response. PMID:24188891

  15. Vulnerability of complex networks under three-level-tree attacks

    Science.gov (United States)

    Hao, Yao-hui; Han, Ji-hong; Lin, Yi; Liu, Lin

    2016-11-01

    We investigate vulnerability of complex networks including model networks and real world networks subject to three-level-tree attack. Specifically, we remove three different three-level-tree structures: RRN (Random Root Node), MaxDRN (Max Degree Root Node) and MinDRN (Min Degree Root Node) from a network iteratively until there is no three-level-tree left. Results demonstrate that random network is more robust than scale-free network against three tree attacks, and the robustness of random network decreases as the increases. And scale-free network shows different characteristics in different tree attack modes. The robustness of scale-free is not affected by the parameters for RRN, but increases as the increases for MinDRN. The important thing is that MaxDRN is the most effective in the three tree attack modes, especially for scale-free network. These findings supplement and extend the previous attack results on nodes and edges, and can thus help us better explain the vulnerability of different networks, and provide an insight into more tolerant real complex systems design.

  16. INTRA-SNAIL LIDOCAIN FOR TREATMENT OF MIGRAINE ATTACK

    Institute of Scientific and Technical Information of China (English)

    Qu Songbin; Wang Xiaofeng

    2000-01-01

    OBJECTIVE To explore a mcthod of trcating migraine attack. BACKROUND Migraine is the most common disorder which causcs .severe headache, nausea and vomiting in attack continuing several hours. There is little method to cease migraine attack quickly. METHOD The patients lied down and kept the head backward. Lidocain 2% 1 to 2 ml was slowly instilled into the nostril ipsilatcral to thc headache. RESULTS Pain relief was achievcd in minutes. The headache disappeared in 19 cases and slight headache rcmained in 2 cases mong 21 cascs. TCD (transcranial dopple ) was tested in 6 cases before thc treatment and 5 minutes after thc treatment. The results showed that CBF (cerebral blood flow) velocity diminished before thc treatment and increased to normal value after the treatment in 5 cases, and it increased beforc thc treatment in another case and diminished after the treatment. DISSCUSION Thc migraine attacks are associated with dysfunction of the vascular constriction and vasodilatation. It was reported that Lidocain had diplex effect that induce the vascular constriction and also induce vasodilatation on the bases of regulation of the autonomic nerves. Medications to abort the attack dramatically by the transnasal route.. CONCLUSION This method is casy to use, painless and effective.

  17. Detection of Attacks on MAODV Association Rule Mining Optimization

    Directory of Open Access Journals (Sweden)

    A. Fidalcastro

    2015-02-01

    Full Text Available Current mining algorithms can generate large number of rules and very slow to generate rules or generate few results, omitting interesting and valuable information. To address this problem, we propose an algorithm Optimized Featured Top Association Rules (OFTAR algorithm, where every attack have many features and some of the features are more important. The Features are selected by genetic algorithm and processed by the OFTAR algorithm to find the optimized rules. The algorithm utilizes Genetic Algorithm feature selection approach to find optimized features. OFTAR incorporate association rules with several rule optimization techniques and expansion techniques to improve efficiency. Increasing popularity of Mobile ad hoc network users of wireless networks lead to threats and attacks on MANET, due to its features. The main challenge in designing a MANET is protecting from various attacks in the network. Intrusion Detection System is required to monitor the network and to detect the malicious node in the network in multi casting mobility environment. The node features are processed in Association Analysis to generate rules, the generated rules are applied to nodes to detect the attacks. Experimental results show that the algorithm has higher scalability and good performance that is an advantageous to several association rule mining algorithms when the rule generation is controlled and optimized to detect the attacks.

  18. Distributed Denial of Service (DDoS) Attacks Detection Mechanism

    CERN Document Server

    Kumarasamy, Saravanan

    2012-01-01

    Pushback is a mechanism for defending against Distributed Denial-of-Service (DDoS) attacks. DDoS attacks are treated as a congestion-control problem, but because most such congestion is caused by malicious hosts not obeying traditional end-to-end congestion control, the problem must be handled by the routers. Functionality is added to each router to detect and preferentially drop packets that probably belong to an attack. Upstream routers are also notified to drop such packets in order that the router's resources be used to route legitimate traffic hence term pushback. Client puzzles have been advocated as a promising countermeasure to DoS attacks in the recent years. In order to identify the attackers, the victim server issues a puzzle to the client that sent the traffic. When the client is able to solve the puzzle, it is assumed to be authentic and the traffic from it is allowed into the server. If the victim suspects that the puzzles are solved by most of the clients, it increases the complexity of the puz...

  19. Why do chimpanzee males attack the females of neighboring communities?

    Science.gov (United States)

    Pradhan, Gauri R; Pandit, Sagar A; Van schaik, Carel P

    2014-11-01

    Our closest nonhuman primate relatives, chimpanzees, engage in potentially lethal between-group conflict; this collective aggressive behavior shows parallels with human warfare. In some communities, chimpanzee males also severely attack and even kill females of the neighboring groups. This is surprising given their system of resource defense polygyny, where males are expected to acquire potential mates. We develop a simple mathematical model based on reproductive skew among primate males to solve this puzzle. The model predicts that it is advantageous for high-ranking males but not for low-ranking males to attack females. It also predicts that more males gain a benefit from attacking females as the community's reproductive skew decreases, i.e., as mating success is more evenly distributed. Thus, fatal attacks on females should be concentrated in communities with low reproductive skew. These attacks should also concur with between-community infanticide. A review of the chimpanzee literature provides enough preliminary support for this prediction to warrant more detailed testing. PMID:25100507

  20. Panic Attack

    OpenAIRE

    Scantamburlo, Gabrielle; Ansseau, Marc

    2004-01-01

    Panic attacks can occur unexpectedly and in almost any situation. The present article discusses the main features of anxiety states, the approach, the management and the practice guidelines for the treatment of panic disorder. Peer reviewed

  1. [Panic attack].

    Science.gov (United States)

    Scantamburlo, G; Ansseau, M

    2004-05-01

    Panic attacks can occur unexpectedly and in almost any situation. The present article discusses the main features of anxiety states, the approach, the management and the practice guidelines for the treatment of panic disorder. PMID:15264579

  2. A Case Of Transient Ischemic Attack Presenting As Hemichroea

    Directory of Open Access Journals (Sweden)

    Hasan Hüseyin Özdemir

    2013-12-01

    Full Text Available Chorea is defined as; involuntary movements of the distal parts of limbs which have arrhythmic, rapid, bouncing or smooth, simple or complex properties. Choreiform movements occur when putamen, globus pallidus and subthalamic nucleus are affected. Chorea can be observed during the course of metabolic and vascular diseases, neurodegenerative or hereditary diseases. Chorea may be a rare symptom of cerebral hypoperfusion. Transient ischemic attack is an event that occurs in short term characterized by a temporary ischemia of brain. A wide variety of symptoms can be seen depending on the localization of cerebral hypoperfusion. Hemichorea is a very rare finding observed during transient ischemic attacks. In this article hemichorea in a case of symptomatic transient ischemic attack is discussed with relevant literature.

  3. Matrix metalloproteinases during and outside of migraine attacks without aura

    DEFF Research Database (Denmark)

    Ashina, M.; Tvedskov, J.F.; Thiesen, Kerstin Lipka;

    2010-01-01

    Ashina M, Tvedskov JF, Lipka K, Bilello J, Penkowa M & Olesen J. Matrix metalloproteinases during and outside of migraine attacks without aura. Cephalalgia 2009. London. ISSN 0333-1024To test the hypothesis that permeability of the blood-brain barrier (BBB) is altered during migraine attack due...... to enhanced activation of matrix metalloproteinases (MMPs), we investigated MMP-3, MMP-9 and tissue inhibitor of metalloproteases (TIMP)-1 in the external jugular vein during and outside of migraine attacks in 21 patients with migraine without aura. In addition, we measured plasma levels of several other...... and interictal plasma levels of MMP-7, -8, -10 and TIMP-2 (P > 0.05). Our data suggest that plasma MMP-9 cannot be used as a biomarker of BBB disruption in migraine without aura. Decreased MMP-3 levels are an interesting and unexpected finding warranting further investigation....

  4. Hydrogen attack evaluation of boiler tube using ultrasonic wave

    International Nuclear Information System (INIS)

    The presence of hydrogen in industrial plants is a source of damage. Hydrogen attack is one such form of degradation and often causing large tube ruptures that necessitate an immediate shutdown. Hydrogen attack may reduce the fracture toughness as well as the strength of steels. This reduction is caused partially by the presence of cavities and microcracks at the grain boundaries. In the past several techniques have been used with limited results. This paper describes the application of an ultrasonic velocity, attenuation and backscatter techniques for detecting the presence of hydrogen damage in utility boiler tubes. Ultrasonic tests showed a decrease in wave velocity and an increase in attenuation. Such results demonstrate the potential for ultrasonic nondestructive testing to quantify damage. Based on this study, recommendations are that both velocity and attenuation be used to detect hydrogen attack in steels.

  5. PREVENTION OF WORMHOLE ATTACK IN WIRELESS SENSOR NETWORK

    Directory of Open Access Journals (Sweden)

    Dhara Buch

    2011-10-01

    Full Text Available Ubiquitous and pervasive applications, where the Wireless Sensor Networks are typically deployed, leadto the susceptibility to many kinds of security attacks. Sensors used for real time response capability alsomake it difficult to devise the resource intensive security protocols because of their limited battery, power,memory and processing capabilities. One of potent form of Denial of Service attacks is Wormhole attackthat affects on the network layer. In this paper, the techniques dealing with wormhole attack areinvestigated and an approach for wormhole prevention is proposed. Our approach is based on theanalysis of the two-hop neighbors forwarding Route Reply packet. To check the validity of the sender, aunique key between the individual sensor node and the base station is required to be generated bysuitable scheme.

  6. Method of Preventing Buffer Overflow Attacks by Intercepting DLL Functions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The way of intercepting Windows DLL functions against buffer overflow attacks is evaluated. It's produced at the expense of hooking vulnerable DLL functions by addition of check code. If the return address in the stack belongs to a heap or stack page, the call is from illicit code and the program is terminated. The signature of malicious code is recorded, so it is possible for the next attack to be filtered out. The return-into-libc attacks are detected by comparing the entry address of DLL functions with the overwritten return address in the stack. The presented method interrupts the execution of malicious code and prevents the system from being hijacked when these intercepted DLL functions are invoked in the context of buffer overflow.

  7. Identifying optimal targets of network attack by belief propagation

    CERN Document Server

    Mugisha, Salomon

    2016-01-01

    For a network formed by nodes and undirected links between pairs of nodes, the network optimal attack problem aims at deleting a minimum number of target nodes to break the network down into many small components. This problem is intrinsically related to the feedback vertex set problem that was successfully tackled by spin glass theory and an associated belief propagation-guided decimation (BPD) algorithm [H.-J. Zhou, Eur.~Phys.~J.~B 86 (2013), 455]. In the present work we apply a slightly adjusted version of the BPD algorithm to the network optimal attack problem, and demonstrate that it has much better performance than a recently proposed Collective Information algorithm [F. Morone and H. A. Makse, Nature 524 (2015), 63--68] for different types of random networks and real-world network instances. The BPD-guided attack scheme often induces an abrupt collapse of the whole network, which may make it very difficult to defend.

  8. Identification Method of Attack Path Based on Immune Intrusion Detection

    Directory of Open Access Journals (Sweden)

    Wenhua Huang

    2014-04-01

    Full Text Available This thesis takes researches on the immune intrusion detection and IP trace back technology. To find out the network data features of the real-time analyses, the distributed immune intrusion detection system and the packet marking theory are used; to guide the dynamically processing of path signs technology, the immune intrusion detection system is used; what’s more, to dynamically adaptive different methods of characteristics of network data, the path signs technology is adopted. After that, the attack paths can be quickly identified to provide path information for feature detector on attack path in the immune intrusion detection system. Experiment results show that this scheme can quickly reconstruct the attack path information, and the performance on the aspects of the convergence is with efficiency rate and false positive rate, which is superior to the current probabilistic packet marking algorithm and can provide characteristic path information for immune intrusion detection system

  9. Heart Attack

    Science.gov (United States)

    ... having another heart attack. These medicines include: aspirin, beta blockers, statins, ACE inhibitors and fish oil. Your doctor ... have had a stent placed in your heart. Beta blockers are a group of drugs that lower the ...

  10. Computing Preferred Extensions for Argumentation Systems with Sets of Attacking

    DEFF Research Database (Denmark)

    Nielsen, Søren Holbech; Parsons, Simon

    2006-01-01

    The hitherto most abstract, and hence general, argumentation system, is the one described by Dung in a paper from 1995. This framework does not allow for joint attacks on arguments, but in a recent paper we adapted it to support such attacks, and proved that this adapted framework enjoyed the same...... formal properties as that of Dung. One problem posed by Dung's original framework, which was neglected for some time, is how to compute preferred extensions of the argumentation systems. However, in 2001, in a paper by Doutre and Mengin, a procedure was given for enumerating preferred extensions...... for these systems. In this paper we propose a method for enumerating preferred extensions of the potentially more complex systems, where joint attacks are allowed. The method is inspired by the one given by Doutre and Mengin....

  11. An Assessment of Worm Hole attack over Mobile Ad-Hoc Network as serious threats

    Directory of Open Access Journals (Sweden)

    Vikas Kumar Upadhyay

    2013-07-01

    Full Text Available Now these day Mobile Ad hoc networks vulnerable from number of security threats like black hole attack, DOS attack, Byzantine attack and wormhole attack. Wormhole attack is one of most important attack and having great attention in recent year. Wormhole attack, demonstrate a illusion over the network that show two far away node to be an neighbor node and attracted all traffic by presenting an greediness of shortest path over the network. This paper presents a bird eye over different existing wormhole deduction mechanism and their problem.

  12. A Model of Biological Attacks on a Realistic Population

    Science.gov (United States)

    Carley, Kathleen M.; Fridsma, Douglas; Casman, Elizabeth; Altman, Neal; Chen, Li-Chiou; Kaminsky, Boris; Nave, Demian; Yahja, Alex

    The capability to assess the impacts of large-scale biological attacks and the efficacy of containment policies is critical and requires knowledge-intensive reasoning about social response and disease transmission within a complex social system. There is a close linkage among social networks, transportation networks, disease spread, and early detection. Spatial dimensions related to public gathering places such as hospitals, nursing homes, and restaurants, can play a major role in epidemics [Klovdahl et. al. 2001]. Like natural epidemics, bioterrorist attacks unfold within spatially defined, complex social systems, and the societal and networked response can have profound effects on their outcome. This paper focuses on bioterrorist attacks, but the model has been applied to emergent and familiar diseases as well.

  13. A Review of Techniques to Mitigate Sybil Attacks

    Directory of Open Access Journals (Sweden)

    Nitish Balachandran

    2012-07-01

    Full Text Available Any decentralised distributed network is particularly vulnerable to the Sybil attack wherein a malicious node masquerades as several different nodes, called Sybil nodes, simultaneously in an attempt to disrupt the proper functioning of the network. Such attacks may cause damage on a fairly large scale especially since they are difficult to detect and there has been no universally accepted scheme to counter them as yet. In this paper, we discuss the different kinds of Sybil attacks including those occurring in peer-to-peer reputation systems, selforganising networks and even social network systems. In addition, various methods that have been suggested over time to decrease or eliminate their risk completely are also analysed along with their modus operandi.

  14. An ensemble approach for feature selection of Cyber Attack Dataset

    CERN Document Server

    Singh, Shailendra

    2009-01-01

    Feature selection is an indispensable preprocessing step when mining huge datasets that can significantly improve the overall system performance. Therefore in this paper we focus on a hybrid approach of feature selection. This method falls into two phases. The filter phase select the features with highest information gain and guides the initialization of search process for wrapper phase whose output the final feature subset. The final feature subsets are passed through the Knearest neighbor classifier for classification of attacks. The effectiveness of this algorithm is demonstrated on DARPA KDDCUP99 cyber attack dataset.

  15. Attack on a classical analogue of the Dunjko, Wallden, Kent and Andersson quantum digital signature protocol

    OpenAIRE

    Newton, Derrick

    2015-01-01

    A quantum digital signature (QDS) protocol is investigated in respect of an attacker who can impersonate other communicating principals in the style of Lowe's attack on the Needham-Schroeder public-key authentication protocol. A man-in-the-middle attack is identified in respect of a classical variant of the protocol and it is suggested that a similar attack would be effective against the QDS protocol. The attack has been confirmed through initial protocol modelling using a automated theorem p...

  16. Simulation Analysis of DoS, MITM and CDP Security Attacks and Countermeasures

    OpenAIRE

    Tanceska, Biljana; Bogdanoski, Mitko; Risteski, Aleksandar

    2015-01-01

    In this paper, an analysis of security attacks on network elements along with the appropriate countermeasures is presented. The network topology that has been attacked is designed in GNS3 software tool installed on Windows operating system, while the attacks are performed in Kali Linux operating system. Three groups of security attacks (Denial of Service, Man in the Middle, and Control Plane attacks) are observed in simulation scenarios with a detailed analysis on each of them, followed by a ...

  17. A 3-Subset Meet-in-the-Middle Attack: Cryptanalysis of the Lightweight Block Cipher KTANTAN

    DEFF Research Database (Denmark)

    Bogdanov, Andrey; Rechberger, Christian

    2011-01-01

    In this paper we describe a variant of existing meet-in-the-middle attacks on block ciphers. As an application, we propose meet-in-the-middle attacks that are applicable to the KTANTAN family of block ciphers accepting a key of 80 bits. The attacks are due to sonic weaknesses in its bitwise key s...... requirements, these attacks are valid even in RFID-like environments where only a very limited amount of text material may be available to an attacker....

  18. Modification of Slenderness Coefficient of Angle Steels

    Institute of Scientific and Technical Information of China (English)

    刘红燕; 李志业

    2004-01-01

    To provide information for amendment to Technical Specifications for Power Transmission Towers (SDGJ94-90), the critical loads of typical compressed angle steels was calculated. The correlation of buckling loads and slenderness of compressed angle steels was obtained with regression. A new slenderness coefficient equation was proposed based on the result of the correlation. A practical measure to ensure good result in nonlinear solution using Arch-length method is put forward.

  19. Enhancing the security of quantum secret sharing against multiphoton attack

    Institute of Scientific and Technical Information of China (English)

    Zhang Bin-Bin; Wang Da-Qing; Huang Shan-Shan; Liu Yu

    2009-01-01

    It is generally believed that nonorthogonal operations which can realize the state transformation between two nonorthogonal bases may ensure the security of many quantum communication protocols. However, in this paper, we present a powerful attack against quantum secret sharing protocols of these kinds. Applying entangled photons as fake signals, Eve can successfully steal the exact information without being revealed. We also give our effective modification to improve it. Under the suggested checking strategy, even to Eve's most general attack, it is robust and secure.

  20. Analysis of factors affecting angle ANB.

    Science.gov (United States)

    Hussels, W; Nanda, R S

    1984-05-01

    Cephalometric analyses based on angular and linear measurements have obvious fallacies, which have been discussed in detail by Moyers and Bookstein. However, the clinical application of such an analysis by the orthodontic profession in treatment planning is widely accepted. Variations of angle ANB are commonly used to determine relative jaw relationships in most of the cephalometric evaluations. Several authors, including points A and B influences angle ANB, as does rotational growth of the upper and lower jaws. In addition, the authors point out that growth in a vertical direction (distance N to B) and an increase of the dental height (distance A to B) may contribute to changes in angle ANB. For a Class I relation (Wits = 0 mm), a mathematical formula has been developed which enables the authors to study the geometric influence of angle ANB caused by the following four effects: (1) rotation of the jaws and/or occlusal plane relative to the anterior cranial base; (2) anteroposterior position of N relative to point B, (3) vertical growth (distance N to B); (4) increase in dental height (distance A to B). It was observed that, contrary to the common belief that an ANB angle of 2 +/- 3.0 degrees is considered normal for a skeletal Class I relation, the calculated values of angle ANB will vary widely with changes in these four controlling factors under the same skeletal Class I conditions (Wits = 0 mm). Therefore, in a case under consideration, angle ANB must be corrected for these geometric effects in order to get a proper perspective of the skeletal discrepancy. This is facilitated by comparing the measured ANB angle with the corresponding ANB angle calculated by a formula for a Class I relationship. The corresponding calculated angle ANB can be taken from the tables which are based upon the formula using the same values for SNB, omega (angle between occlusal plane and anterior cranial base), b (which is distance N to B) and a (dental height measured as perpendicular

  1. ATTACK ON WATER BY CARBON OF SOLID FUEL

    OpenAIRE

    N. S. Nazarov; A. I. Оlevanov

    2008-01-01

    The paper considers a continuous method for attack of high temperature water steam by carbon of solid fuel (coke). Design of water-coal gas generator and experimental stand, methodology for  measurements of parameters of water-coal gasification are described in the paper.

  2. ATTACK ON WATER BY CARBON OF SOLID FUEL

    Directory of Open Access Journals (Sweden)

    N. S. Nazarov

    2008-01-01

    Full Text Available The paper considers a continuous method for attack of high temperature water steam by carbon of solid fuel (coke. Design of water-coal gas generator and experimental stand, methodology for  measurements of parameters of water-coal gasification are described in the paper.

  3. A lattice determination of gA and left angle x right angle from overlap fermions

    International Nuclear Information System (INIS)

    We present results for the nucleon's axial charge gA and the first moment left angle x right angle of the unpolarized parton distribution function from a simulation of quenched overlap fermions. (orig.)

  4. Extracranial arterial aneurysms: a cause of crescendo transient ischaemic attacks.

    Science.gov (United States)

    Paterson, H M; Holdsworth, R J

    2000-12-01

    Crescendo transient ischaemic attacks (TIAs) should be regarded as a medical emergency. Patients require hospitalisation with urgent assessment and symptom control with anticoagulant therapy. We report on three patients, all of whom had atherosclerotic aneurysmal disease of the extracranial arterial circulation who presented with crescendo TIAs. The possibility of extracranial aneurysmal disease should always be considered and excluded.

  5. Vulnerabilities in GSM technology and feasibility of selected attacks

    Science.gov (United States)

    Voznak, M.; Prokes, M.; Sevcik, L.; Frnda, J.; Toral-Cruz, Homer; Jakovlev, Sergej; Fazio, Peppino; Mehic, M.; Mikulec, M.

    2015-05-01

    Global System for Mobile communication (GSM) is the most widespread technology for mobile communications in the world and serving over 7 billion users. Since first publication of system documentation there has been notified a potential safety problem's occurrence. Selected types of attacks, based on the analysis of the technical feasibility and the degree of risk of these weaknesses, were implemented and demonstrated in laboratory of the VSB-Technical University of Ostrava, Czech Republic. These vulnerabilities were analyzed and afterwards possible attacks were described. These attacks were implemented using open-source tools, software programmable radio USRP (Universal Software RadioPeripheral) and DVB-T (Digital Video Broadcasting - Terrestrial) receiver. GSM security architecture is being scrutinized since first public releases of its specification mainly pointing out weaknesses in authentication and ciphering mechanisms. This contribution also summarizes practically proofed and used scenarios that are performed using opensource software tools and variety of scripts mostly written in Python. Main goal of this paper is in analyzing security issues in GSM network and practical demonstration of selected attacks.

  6. Modelling Based Approach for Reconstructing Evidence of VOIP Malicious Attacks

    Directory of Open Access Journals (Sweden)

    Mohammed Ibrahim

    2015-05-01

    Full Text Available Voice over Internet Protocol (VoIP is a new communication technology that uses internet protocol in providing phone services. VoIP provides various forms of benefits such as low monthly fee and cheaper rate in terms of long distance and international calls. However, VoIP is accompanied with novel security threats. Criminals often take advantages of such security threats and commit illicit activities. These activities require digital forensic experts to acquire, analyses, reconstruct and provide digital evidence. Meanwhile, there are various methodologies and models proposed in detecting, analysing and providing digital evidence in VoIP forensic. However, at the time of writing this paper, there is no model formalized for the reconstruction of VoIP malicious attacks. Reconstruction of attack scenario is an important technique in exposing the unknown criminal acts. Hence, this paper will strive in addressing that gap. We propose a model for reconstructing VoIP malicious attacks. To achieve that, a formal logic approach called Secure Temporal Logic of Action(S-TLA+ was adopted in rebuilding the attack scenario. The expected result of this model is to generate additional related evidences and their consistency with the existing evidences can be determined by means of S-TLA+ model checker.

  7. Impact of migraine attacks on the blood-brain barrier

    Institute of Scientific and Technical Information of China (English)

    GAO Hong-mei; LI Le; ZHANG Ke-ling; CHEN Xu-hui; TIAN Shu-qing; ZHANG Zhong-ling

    2010-01-01

    Background Cortical spreading depression can cause migraine attack, and up-regulate matrix metalloproteinase-9 (MMP-9) expression in animal. This study aimed to determine the impact on the structure and function of the blood-brain barrier by measuring plasma MMP-9 levels in patients at the acute and late stages of migraine attacks in order to elucidate the pathological mechanisms involved.Methods We recruited a case-control cohort of 38 adult migraine patients and 20 age- and gender-matched healthy control subjects. Five milliliter blood samples were collected at the acute and late stages of migraine (days 1-7), and also from the control subjects. Solid phase double antibody sandwich enzyme-linked immunosorbent assay was used to determine plasma MMP-9 levels. Statistical analysis was performed using the SAS version 9.1.Results Initial plasma MMP-9 levels of migraine patients were significantly higher than those of controls ((12.612±0.016)μg/L vs. (6.069±0.023) μg/L, respectively, P 0.05); in addition, levels were not correlated with degree of headache pain (P >0.05).Conclusions We hypothesize that migraine could lead to increased plasma MMP-9 levels resulting in blood-brain barrier damage. MMP-9 levels increase during days 1-6 of migraine attacks, peaking on day 3. Therefore, MMP-9 could be used as a biological marker to guide treatment of migraine attacks.

  8. Parent-Reported Predictors of Adolescent Panic Attacks.

    Science.gov (United States)

    Hayward, Chris; Wilson, Kimberly A.; Lagle, Kristy; Killen, Joel D.; Taylor, C. Barr

    2004-01-01

    Objective: To identify parent-reported risk factors for adolescent panic attacks. Method: Structured diagnostic interviews were obtained from 770 parents of participants in a school-based risk factor study for adolescent panic. Parent-reported risk factors assessed included characteristics of the child (negative affect, separation anxiety disorder…

  9. A video-polygraphic analysis of the cataplectic attack

    DEFF Research Database (Denmark)

    Rubboli, G; d'Orsi, G; Zaniboni, A;

    2000-01-01

    OBJECTIVES AND METHODS: To perform a video-polygraphic analysis of 11 cataplectic attacks in a 39-year-old narcoleptic patient, correlating clinical manifestations with polygraphic findings. Polygraphic recordings monitored EEG, EMG activity from several cranial, trunk, upper and lower limbs musc...... of REM sleep and neural structures subserving postural control....

  10. Plasma Exchange in Severe Attacks of Neuromyelitis Optica

    Directory of Open Access Journals (Sweden)

    Mickael Bonnan

    2012-01-01

    Full Text Available Background. Neuromyelitis optica (NMO attacks are poorly controlled by steroids and evolve in stepwise neurological impairments. Assuming the strong humoral response underlying NMO attacks, plasma exchange (PLEX is an appropriate technique in severe NMO attacks. Objective. Presenting an up-to-date review of the literature of PLEX in NMO. Methods. We summarize the rationale of PLEX in relation with the physiology of NMO, the main technical aspects, and the available studies. Results. PLEX in severe attacks from myelitis or optic neuritis are associated with a better outcome, depending on PLEX delay (“time is cord and eyes”. NMO-IgG status has no influence. Finally, we build up an original concept linking the inner dynamic of the lesion, the timing of PLEX onset and the expected clinical results. Conclusion. PLEX is a safe and efficient add-on therapy in NMO, in synergy with steroids. Large therapeutic trials are required to definitely assess the procedure and define the time opportunity window.

  11. Evaluation of corrosion attack of chimney liners

    OpenAIRE

    Blahetová M.; Horák J.; Kubesa P.; Lasek S.; Ochodek T.

    2016-01-01

    The case study of chimney liner corrosion addresses three specific cases of damage of chimney systems from of stainless steels. These systems were used for flue of gas arising from the combustion of brown coal in small automatic boilers, which are used for heating. Detailed analyzes implied that the cause of devastating corrosion of the steel AISI 316 and 304 steel (CSN 17349, 17241) was particularly high content of halides (chlorides and fluorides), which caused a severe pitting corrosion, w...

  12. Nonadiabatic Hannay's Angle of Spin One Half in Grassmannian Version and Invariant Angle Coherent States

    OpenAIRE

    Cherbal, Omar; Maamache, Mustapha; Drir, Mahrez

    2003-01-01

    We propose to determinate the nonadiabatic Hannay’s angle of spin one half in a varying external magnetic field, by using an averaged version of the variational principal. We also show how the evolution and this nonadiabatic Hannay’s angle is associated with the evolution of Grassmannian invariant-angle coherent states.

  13. The anatomy of a shark attack: a case report and review of the literature.

    Science.gov (United States)

    Caldicott, D G; Mahajani, R; Kuhn, M

    2001-07-01

    Shark attacks are rare but are associated with a high morbidity and significant mortality. We report the case of a patient's survival from a shark attack and their subsequent emergency medical and surgical management. Using data from the International Shark Attack File, we review the worldwide distribution and incidence of shark attack. A review of the world literature examines the features which make shark attacks unique pathological processes. We offer suggestions for strategies of management of shark attack, and techniques for avoiding adverse outcomes in human encounters with these endangered creatures.

  14. Evaluation of corrosion attack of chimney liners

    Directory of Open Access Journals (Sweden)

    Blahetová M.

    2016-06-01

    Full Text Available The case study of chimney liner corrosion addresses three specific cases of damage of chimney systems from of stainless steels. These systems were used for flue of gas arising from the combustion of brown coal in small automatic boilers, which are used for heating. Detailed analyzes implied that the cause of devastating corrosion of the steel AISI 316 and 304 steel (CSN 17349, 17241 was particularly high content of halides (chlorides and fluorides, which caused a severe pitting corrosion, which led up to the perforation of the liner material. Simultaneous reduction of the thickness of the used sheets was due to by the general corrosion, which was caused by the sulfur in the solid fuel. The condensation then led to acid environment and therefore the corrosion below the dew point of the sulfuric acid has occurred. All is documented by metallographic analysis and microanalysis of the corrosion products.

  15. Prevalence of eating disorders and eating attacks in narcolepsy

    Directory of Open Access Journals (Sweden)

    Norbert Dahmen

    2008-03-01

    Full Text Available Norbert Dahmen, Julia Becht, Alice Engel, Monika Thommes, Peter TonnPsychiatry Department, University of Mainz, GermanyAbstract: Narcoleptic patients suffer frequently from obesity and type II diabetes. Most patients show a deficit in the energy balance regulating orexinergic system. Nevertheless, it is not known, why narcoleptic patients tend to be obese. We examined 116 narcoleptic patients and 80 controls with the structured interview for anorectic and bulimic eating disorders (SIAB to test the hypothesis that typical or atypical eating attacks or eating disorders may be more frequent in narcoleptic patients. No difference in the current prevalence of eating disorders bulimia nervosa, binge eating disorder, or anorexia nervosa was found, nor was the frequency of eating attacks higher in the narcolepsy group. We conclude that present eating disorders and eating attacks as defined in DSM IV are not the reason for the observed differences in body composition. Additional factors, such as basal metabolic rates and lifestyle factors need to be considered.Keywords: narcolepsy, eating disorder, SIAB, bulimia, anorexia, eating attack

  16. Low Serum Concentrations of Vitamin B6 and Iron Are Related to Panic Attack and Hyperventilation Attack

    OpenAIRE

    Mikawa, Yasuhito; Mizobuchi, Satoshi; Egi, Moritoki; Morita, Kiyoshi

    2013-01-01

    Patients undergoing a panic attack (PA) or a hyperventilation attack (HVA) are sometimes admitted to emergency departments (EDs). Reduced serotonin level is known as one of the causes of PA and HVA. Serotonin is synthesized from tryptophan. For the synthesis of serotonin, vitamin B6 (Vit B6) and iron play important roles as cofactors. To clarify the pathophysiology of PA and HVA, we investigated the serum levels of vitamins B2, B6, and B12 and iron in patients with PA or HVA attending an ED. ...

  17. EMERGENCE ANGLE OF FLOW OVER AN AERATOR

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aerator is an important device for release works of hydraulic structures with high-speed flow in order to protect them from cavitation damage. This kind of protecting effect is related closely to cavity length below the aerator, while the cavity length is dominated by the emergence angle over the aerator. Therefore it is crucial to determine this angle accurately. In the present paper the affecting intensities of flow depth and the fluctuating velocity on this angle were analyzed through two introduced parameters. Furthermore, the improved expressions of emergence angle estimation, for both ramp-type and step-type aerators, were presented by means of 68 sets of experimental data from 6 projects based on error theory. The results showed that the present method has higher accuracy than the previously reported methods.

  18. Detection techniques of selective forwarding attacks in wireless sensor networks: a survey

    CERN Document Server

    Sharma, Preeti; Saluja, Krishan Kumar

    2012-01-01

    The wireless sensor network has become a hot research area due its wide range of application in military and civilian domain, but as it uses wireless media for communication these are easily prone to security attacks. There are number of attacks on wireless sensor networks like black hole attack, sink hole attack, Sybil attack, selective forwarding attacks etc. in this paper we will concentrate on selective forwarding attacks In selective forwarding attacks, malicious nodes behave like normal nodes and selectively drop packets. The selection of dropping nodes may be random. Identifying such attacks is very difficult and sometimes impossible. In this paper we have listed up some detection techniques, which have been proposed by different researcher in recent years, there we also have tabular representation of qualitative analysis of detection techniques

  19. Winding angles of long lattice walks

    Science.gov (United States)

    Hammer, Yosi; Kantor, Yacov

    2016-07-01

    We study the winding angles of random and self-avoiding walks (SAWs) on square and cubic lattices with number of steps N ranging up to 107. We show that the mean square winding angle of random walks converges to the theoretical form when N → ∞. For self-avoiding walks on the square lattice, we show that the ratio /2 converges slowly to the Gaussian value 3. For self-avoiding walks on the cubic lattice, we find that the ratio /2 exhibits non-monotonic dependence on N and reaches a maximum of 3.73(1) for N ≈ 104. We show that to a good approximation, the square winding angle of a self-avoiding walk on the cubic lattice can be obtained from the summation of the square change in the winding angles of lnN independent segments of the walk, where the ith segment contains 2i steps. We find that the square winding angle of the ith segment increases approximately as i0.5, which leads to an increase of the total square winding angle proportional to (lnN)1.5.

  20. Generation of plasmin during acute attacks of hereditary angioedema.

    Science.gov (United States)

    Cugno, M; Hack, C E; de Boer, J P; Eerenberg, A J; Agostoni, A; Cicardi, M

    1993-01-01

    Hereditary angioedema is caused by a genetic deficiency of C1-inhibitor, a serine protease inhibitor that regulates activation of complement, contact, and fibrinolytic systems. Symptoms (bouts of subcutaneous and mucous swelling) depend on the release of a vasoactive mediator, probably through activation of these three systems. We studied the interrelationship among complement, contact, and fibrinolytic activation in 23 patients with hereditary angiodema, 18 during remission and five during an attack, by measuring plasma levels of C1-C1 inhibitor, factor XIIa-C1 inhibitor, kallikrein-C1 inhibitor, and plasmin-alpha 2-antiplasmin complexes, tissue plasminogen activator, and urokinase plasminogen activator. In addition, cleavage of high-molecular weight kininogen was detected by sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis and quantified by densitometry. During remission, plasma levels of C1-C1 inhibitor complexes were elevated (p = 0.0002), whereas the other parameters were within the normal range. During acute attacks, not only plasma levels of C1-C1 inhibitor complexes but also those of plasmin-alpha 2-antiplasmin complexes (P = 0.0009) and cleaved high-molecular weight kininogen were elevated. A positive correlation between plasmin-alpha 2-antiplasmin complexes and cleaved high-molecular weight kininogen was observed (r = 0.75, p attacks is associated with the activation of the fibrinolytic system.

  1. Resistance of the double random phase encryption against various attacks.

    Science.gov (United States)

    Frauel, Yann; Castro, Albertina; Naughton, Thomas J; Javidi, Bahram

    2007-08-01

    Several attacks are proposed against the double random phase encryption scheme. These attacks are demonstrated on computer-generated ciphered images. The scheme is shown to be resistant against brute force attacks but susceptible to chosen and known plaintext attacks. In particular, we describe a technique to recover the exact keys with only two known plain images. We compare this technique to other attacks proposed in the literature.

  2. Traits of Masson Pine Affecting Attack of Pine Wood Nematode

    Institute of Scientific and Technical Information of China (English)

    Juan Shi; You-Qing Luo; Ji-Ying Song; Hai-Wei Wu; Lei Wang; Gary Z. Wang

    2007-01-01

    Masson pine characteristics were analyzed in five sample plots in Zhejiang Province, China.Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle (pine wood nematode, PWN) carried by Monochamus alternatus predominately attacked Masson pines in the lower diameter classes.Among the 10 tree characteristics examined, mean crown width, percentage of bole with crown, 5-year cumulative diameter growth, and resin amount showed significant variation between successfully attacked and unattacked trees.The attacked trees had a lower percentage of the bole covered with tree crown, lower crown width, lower radial growth in the last 5 years, and produced less induced resinosis than unattacked trees.Results allowed for effective ranking of the pine forest based on individual tree resistance to PWN.This Index of resistance should be considered throughout the development of an "Evaluation Criterion and Indicator System".The preceding ranking can be used to evaluate the resistance and resiliency of the pine forest ecosystem to PWN's invasion, which is similar to Pest Risk Analysis (PRA).

  3. A Method of Detecting Sql Injection Attack to Secure Web Applications

    Directory of Open Access Journals (Sweden)

    Manesh T

    2012-12-01

    Full Text Available Web applications are becoming an important part of our daily life. So attacks against them also increasesrapidly. Of these attacks, a major role is held by SQL injection attacks (SQLIA. This paper proposes anew method for preventing SQL injection attacks in JSP web applications. The basic idea is to checkbefore execution, the intended structure of the SQL query. For this we use semantic comparison. Ourfocus is on stored procedure attack in which query will be formed within the database itself and sodifficult to extract that query structure for validation. Also this attack is less considered in the literature.

  4. Intrusion Detection of NSM Based DoS Attacks Using Data Mining in Smart Grid

    OpenAIRE

    JungChan Na; Kijoon Chae; Mihui Kim; Shi Li; Xinyi Chen; Kyung Choi

    2012-01-01

    In this paper, we analyze the Network and System Management (NSM) requirements and NSM data objects for the intrusion detection of power systems; NSM is an IEC 62351-7 standard. We analyze a SYN flood attack and a buffer overflow attack to cause the Denial of Service (DoS) attack described in NSM. After mounting the attack in our attack testbed, we collect a data set, which is based on attributes for the attack. We then run several data mining methods with the data set using the Waikato Envir...

  5. Prevention of Spoofing Attacks in the Infrastructure Wireless Networks

    Directory of Open Access Journals (Sweden)

    Samraa A. AlAsady

    2012-01-01

    Full Text Available Problem statement: Spoofing Attack is one of the vulnerabilities in the wireless networks, which is a situation in which the intruder successfully masquerades as legal one. Spoofing Attacks will decrease the performance of the network and violate many security issues. In the networks that use MAC address based filtering approach to authenticate the clients, the spoofer just needs to get a valid MAC address that belong to some authorized client in the network in order to gain an illegitimate advantage. Approach: In this article, it has proposed an algorithm that uses an additional authentication process beside MAC address filtering and periodically re-authenticates the client after sending every specific number of Data frames. The proposed additional authentication process is based on two parts. First: Using unique information that belongs to every client in the network such as computer name, CPU ID and the current time as inputs to a hash function (one-way function, then insert the hash value in the slack fields of the header of the frame (Steganography. Second: Make a modification to the access point access control list by adding that unique information belong to each client in addition to its MAC address in the access control list. Thus, when the AP receives an Authentication frame from a client, it will first check the MAC address, if it is legal; the AP will re-compute the Hash value depending on the corresponding identifiers stored in the access control list and the time of creating the frame, then compare the resulted hash value with the received one and decide whether to reject or accept the access. Results: The results has been found is that even the attacker is spoofed the MAC address; he/she cannot communicate with the network because the attacker will fail in computing the hash value that depends on the Computer name and CPU ID. Also the attacker will be prevented even if he/she enters the network after the legal client finished the

  6. Extensive Design for Attack's Recognition and Resistance of Survivable Network

    Directory of Open Access Journals (Sweden)

    Hui Xu

    2012-02-01

    Full Text Available Extentics is a new discipline that studies the methods for dealing with contradictory problems. This paper gives a solution of attack defense of survivable network based on this theory. The basic knowledge of extension theory is introduced and the inspiration from it to our problem is illustrated. The contradictory characteristic of survivability of borderless network is explained. The extension model and algorithms of recognition and resistance of attacks is presented. The definitions of element, including message matter-element, defense affair-element, node relation-element and inform mixture-element, are given. The dependent function based on lateral distance with the most advantage point occurs in the left common endpoint, is constructed to solve the problem and its properties are discussed. Finally, an application of worm’s warning by this method is illustrated.

  7. STUDY OF PRIVILEGE ESCALATION ATTACK ON ANDROID AND ITS COUNTERMEASURES

    Directory of Open Access Journals (Sweden)

    REJO MATHEW

    2012-09-01

    Full Text Available Android is most commonly used platform for smartphones today which boasts of an advanced security model having MAC and sandboxing. These features allow developers and users to restrict the execution of anapplication to the privileges assigned. The exploitation of vulnerabilities of the program is confined within the privilege boundaries of an applications sandbox. Privilege escalation attacks have grown manifold as the use of android systems have increased. Different kinds of mechanisms have provided some sort of respite to the developers but the security feature handling by the developers has not helped much. In this paper we discuss the basics of the privilege escalation attack and the various techniques used to counter and prevent this problem.

  8. Distributed Detection of Wormhole Attacks in Wireless Sensor Networks

    Science.gov (United States)

    de Graaf, Rennie; Hegazy, Islam; Horton, Jeffrey; Safavi-Naini, Reihaneh

    Sensors in a wireless sensor network depend on their neighbours to route their messages. Yet, routing protocols in wireless sensor network are vulnerable to different types of attacks. In this paper, we consider the wormhole attack in which the adversary diverts traffic from one part of the network to another part by introducing a low cost tunnel between the two parts. We introduce a distributed intrusion detection system that monitors the communication in the network and propose a criterion for the placement of intrusion detection nodes. The intrusion detection system searches for violations of that criterion to detect wormholes of length above a certain minimum value. We evaluate the effectiveness of our system in a simulated environment. The experiments show that our system can detect 100% of the wormholes that are beyond the communication range of the intrusion detection nodes. Finally, we discuss our results and show directions for future work.

  9. A serious cause of panic attack.

    Science.gov (United States)

    O'Connell, Michael; Bernard, Aaron

    2012-01-01

    We report on a case of a patient with atrial fibrillation in the setting of Wolff-Parkinson-White syndrome. The patient underwent synchronized electrical cardioversion, typically considered safe and effective, which resulted in a dangerous complication for the patient (degeneration into ventricular fibrillation). Discussion of common rhythm disturbances in WPW and management strategies are reviewed. PMID:23326712

  10. A Serious Cause of Panic Attack

    OpenAIRE

    Michael O'Connell; Aaron Bernard

    2012-01-01

    We report on a case of a patient with atrial fibrillation in the setting of Wolff-Parkinson-White syndrome. The patient underwent synchronized electrical cardioversion, typically considered safe and effective, which resulted in a dangerous complication for the patient (degeneration into ventricular fibrillation). Discussion of common rhythm disturbances in WPW and management strategies are reviewed.

  11. A Serious Cause of Panic Attack

    Directory of Open Access Journals (Sweden)

    Michael O'Connell

    2012-01-01

    Full Text Available We report on a case of a patient with atrial fibrillation in the setting of Wolff-Parkinson-White syndrome. The patient underwent synchronized electrical cardioversion, typically considered safe and effective, which resulted in a dangerous complication for the patient (degeneration into ventricular fibrillation. Discussion of common rhythm disturbances in WPW and management strategies are reviewed.

  12. Analysis of signature wrapping attacks and countermeasures

    DEFF Research Database (Denmark)

    Gajek, Sebastian; Jensen, Meiko; Liao, Lijun;

    2009-01-01

    In recent research it turned out that Boolean verification, of digital signatures in the context of WSSecurity, is likely to fail: If parts of a SOAP message, are signed and the signature verification applied to, the whole document returns true, then nevertheless the, document may have been...

  13. Study of attack in college volleyball

    Directory of Open Access Journals (Sweden)

    Yordan Portela Pozo

    2014-03-01

    Full Text Available AbstractThis work is done in order to analyze the positive and negative aspects that affected the performance of the auction action in volleyball players performing this action (in this case male in the Provincial University Games in 2012 in Havana , for which I take as a case study to the players of the University of Information Sciences and its opponents in those games, completing a total of 268 shares auctions in 7 games with a total of 15 September analyzed taking account of changes in the sport of Volleyball university in Cuba, data recorded by an observation sheet previously completed by the authors. The main results in this paper show that the greatest amount of shots that were done in these games were diagonal and a good percentage of positive linear auctions however were few and with very poor results. The primary role of the auction for the game's success is fully confirmed in this work because this action is achieved through many points in the game of volleyball and thus leads to a better result.

  14. Attacks to cryptography protocols of wireless industrial communication systems

    OpenAIRE

    Ondrašina, Tomáš; Franeková, Mária

    2010-01-01

    The paper deals with problems of safety and security principles within wireless industrial communication systems. First safety requirements to wireless industrial communication system, summarisation of attack methods and the available measures for risks elimination are described with orientation to safety critical applications. The mainly part is oriented to identification of risks and summarisation of defensive methods of wireless communication based on cryptographic techniques. Practical pa...

  15. Performance analyses of wormhole attack in Cognitive Radio Network (CRN

    Directory of Open Access Journals (Sweden)

    Prabhjot

    2015-06-01

    Full Text Available Mobile wirelesses networks are generally open to various attacks like information and physical security attacks than fixed wired networks. Securing wireless ad hoc networks is particularly more difficult for many of the reasons for example vulnerability of channels and nodes, absence of infrastructure, dynamically changing topology etc. After that we initialize the number of nodes. Then implement protocol for the communication of nodes. Due to these protocols communication start. And this will be then implemented in CRNs which stand for cognitive radio network in which channel sensing is done. By the use of CRN security will be improved and performance will be enhanced. Find the malicious nodes occur in the network. One malicious node uses routing protocol to claim itself of being shortest path to last node but drops routing packets and doesn’t send packets to its neighbors. In last evaluate the parameters.

  16. Applying the Principles of Homicide by Heart Attack.

    Science.gov (United States)

    Hlavaty, Leigh; Sung, LokMan

    2016-06-01

    Homicide by heart attack is a well-established model in forensic pathology that describes death elicited during or immediately after a criminal act where a threat or fear of physical injury is present. After its introduction nearly 4 decades ago, the principle has undergone a handful of modifications but still maintains its core concepts. All cases of this nature during a 20-year period at the Wayne County Medical Examiner's Office were compared and contrasted for demographics, circumstances and scene investigation, and autopsy and toxicology findings. Of the cases fulfilling the previously established criteria for homicide by heart attack, more than 80% displayed significant changes because of hypertension. This finding coincides with the high prevalence of hypertension in our urban population and highlights the significance of this disease. Also present were minor external and internal injuries in select cases, which reinforce the understanding that physical contact between the decedent and assailant does not preclude this diagnosis. PMID:27049661

  17. Applying the Principles of Homicide by Heart Attack.

    Science.gov (United States)

    Hlavaty, Leigh; Sung, LokMan

    2016-06-01

    Homicide by heart attack is a well-established model in forensic pathology that describes death elicited during or immediately after a criminal act where a threat or fear of physical injury is present. After its introduction nearly 4 decades ago, the principle has undergone a handful of modifications but still maintains its core concepts. All cases of this nature during a 20-year period at the Wayne County Medical Examiner's Office were compared and contrasted for demographics, circumstances and scene investigation, and autopsy and toxicology findings. Of the cases fulfilling the previously established criteria for homicide by heart attack, more than 80% displayed significant changes because of hypertension. This finding coincides with the high prevalence of hypertension in our urban population and highlights the significance of this disease. Also present were minor external and internal injuries in select cases, which reinforce the understanding that physical contact between the decedent and assailant does not preclude this diagnosis.

  18. Use of forensic analysis to better understand shark attack behaviour.

    Science.gov (United States)

    Ritter, E; Levine, M

    2004-12-01

    Shark attacks have primarily been analyzed from wound patterns, with little knowledge of a shark's approach, behaviour and intention leading to such wounds. For the first time, during a shark-human interaction project in South Africa, a white shark, Carcharodon carcharias, was filmed biting a vertically positioned person at the water surface, and exhibiting distinct approach patterns leading to the bite. This bite was compared to ten white shark attacks that occurred (i) in the same geographical area of South Africa, and (ii) where the same body parts were bitten. Close similarity of some of these wound patterns to the bite imprint of the videotaped case indicate that the observed behaviour of the white shark may represent a common pattern of approaching and biting humans.

  19. Under attack: a way of life

    Directory of Open Access Journals (Sweden)

    David Eubank

    2008-04-01

    Full Text Available Much of what is happening in the conflict zones ofeastern Burma is difficult to capture with photos, videoand reports. It is a slow and insidious strangulation of thepopulation rather than an all-out effort to crush them.

  20. Case studies of attacks on communication networks

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Sin Bok; Han, Eon Suk [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1996-06-15

    Recently, as the computer hardware and communications are developed, the data exchange through inter-networking has been highlighted and the data is being recognized as a great asset. Most of the organizations, businesses and enterprises are open to the external world-computer communication networks, attention must be focused on the securities of the information infrastructure. A government organization has been developing 'Circuits Analyzers', and 'Hacker-Tracking Program' and is struggling to track down sneakers. In this report, we analyze the contents of the cases where the communication network has been invaded, from the past up until now in Korea. This report also contains the result of a study on E-mail security, for the protection of KAERI Integrated Management Information System under which utilizes the CALS concepts and web services. (Author)

  1. DEF: As a form of sulfate attack

    Directory of Open Access Journals (Sweden)

    Skalny, J.

    1996-12-01

    Full Text Available Delayed ettringite formation (DEF is the term used to describe expansion of some heat cured portland cement concretes. Although meaningful progress has been made, the exact mechanism of the expansion itself is not entirely understood. The ettringite reformation is enabled, primarily, by thermal decomposition of ettringite formed prior to or during the cement paste setting as a result of excessive/improper heat curing. Observance in mature concrete of crystalline ettringite in air voids, cracks, and gaps around the aggregate is not in itself an evidence for DEF, but is the consequence of natural recrystallization of ettringite into available larger spaces. Occurance of DEF is dependent on materials, curing, and environmental conditions, and can easily be distinguished from ASR and other deterioration mechanisms by optical and electron-optical methods.

    DEF es el término habitualmente usado para describir la expansión que sufren algunos hormigones de cemento Portland que han sido curados con la ayuda de un tratamiento térmico. DEF es la abreviatura de la expresión inglesa "Delayed Ettringite Formation" que en español se podría traducir como "Formación de Etringita Retrasada". Aunque en los últimos tiempos se ha progresado significativamente, aún hoy día no se entiende completamente el mecanismo exacto de la expansión en sí misma. La formación de una etringita tardía es, en principio, consecuencia de la descomposición térmica de la etringita formada con anterioridad o durante el fraguado de la pasta de cemento, por un exceso de calor o inadecuado proceso de curado térmico. La observación, en el hormigón maduro, de etringita cristalina en poros, fisuras y en las interfases pasta-áridos no es en sí una evidencia de la DEF, pero sí es una consecuencia de la natural recristalización de la etringita en espacios disponibles. El fenómeno de la DEF depende de los materiales, del curado y de las condiciones ambientales, y puede

  2. Possible mechanisms of panic attack and schizophrenia via APUD system.

    Science.gov (United States)

    Fukuda, K

    2002-02-01

    Psilocybin poisoning produces biphasic reactions composed of a schizophrenic phase and a panic attack-like phase. There is a time lag of several hours between phases, which may be considered an accumulation time in certain sites between the gut and the brain. So far as 5-hydroxytryptamine (5-HT) congeners are concerned, no sites are to be found except the amine precursor uptake and decarboxylation (APUD) system. It is postulated that argyrophil cells (AC) in the foregut, neuroepithelial bodies (NEB) in the lung, and raphe nuclei (RN) in the brainstem axis are relevant to mental disorders. Schizophrenia might be due to the massive destruction of APUD cells, and the paroxysmal release of 5-HT with peptides and panneuroendocrine markers from NEB might be the cause of panic attack. PMID:11812187

  3. Classification of artificial intelligence ids for smurf attack

    CERN Document Server

    Ugtakhbayar, N; Sodbileg, Sh

    2012-01-01

    Many methods have been developed to secure the network infrastructure and communication over the Internet. Intrusion detection is a relatively new addition to such techniques. Intrusion detection systems (IDS) are used to find out if someone has intrusion into or is trying to get it the network. One big problem is amount of Intrusion which is increasing day by day. We need to know about network attack information using IDS, then analysing the effect. Due to the nature of IDSs which are solely signature based, every new intrusion cannot be detected; so it is important to introduce artificial intelligence (AI) methods / techniques in IDS. Introduction of AI necessitates the importance of normalization in intrusions. This work is focused on classification of AI based IDS techniques which will help better design intrusion detection systems in the future. We have also proposed a support vector machine for IDS to detect Smurf attack with much reliable accuracy.

  4. Resilience of LTE networks against smart jamming attacks

    KAUST Repository

    Aziz, Farhan M.

    2014-12-08

    Commercial LTE networks are being studied for mission-critical applications, such as public safety and smart grid communications. In this paper, LTE networks are shown vulnerable to Denial-of-Service (DOS) and loss of service attacks from smart jammers, who may employ simple narrowband jamming techniques to attack without any need to hack the network or its users. We modeled the utilities of jamming and anti-jamming actions played by the jammer and the network under the framework of single-shot and repeated Bayesian games. In a single-shot game formulation the only Nash Equilibria (NE) are pure strategy equilibria at which network utility is severely compromised. We propose a repeated-game learning and strategy algorithm for the network that outperforms single-shot games by a significant margin. Furthermore, all of our proposed actions and algorithms can be implemented with current technology.

  5. Detection Techniques of DOS/DDOS/DRDOS Attacks in Networks of Mass Service

    Directory of Open Access Journals (Sweden)

    G. Shangytbayeva

    2015-08-01

    Full Text Available The study describes the basic network attacks such as "denial of service", algorithm of operation of malefactors with attacks of this type, techniques of detection of DOS/DDOS/DRDOS attacks in networks of mass service. For detection of DDoS-attacks is offered the valuation method of probability of loss of arbitrary request in case of its passing on networks of mass service. Developed the architecture and constructed program implementation of system of detection of DDoS-attacks. The developed technique allows to receive an adequate assessment of frequency of loss of requests on a network if the network of mass service is in the stationary mode.

  6. The Rebound Attack: Cryptanalysis of Reduced Whirlpool and Grøstl

    DEFF Research Database (Denmark)

    Mendel, Florian; Rechberger, Christian; Schläffer, Martin;

    2009-01-01

    In this work, we propose the rebound attack, a new tool for the cryptanalysis of hash functions. The idea of the rebound attack is to use the available degrees of freedom in a collision attack to efficiently bypass the low probability parts of a differential trail. The rebound attack consists...... of an inbound phase with a match-in-the-middle part to exploit the available degrees of freedom, and a subsequent probabilistic outbound phase. Especially on AES based hash functions, the rebound attack leads to new attacks for a surprisingly high number of rounds. We use the rebound attack to construct...... collisions for 4.5 rounds of the 512-bit hash function Whirlpool with a complexity of 2^120 compression function evaluations and negligible memory requirements. The attack can be extended to a near-collision on 7.5 rounds of the compression function of Whirlpool and 8.5 rounds of the similar hash function...

  7. Web Application Scanning and Identification of Vulnerabilities for Different Attacks

    Directory of Open Access Journals (Sweden)

    Haridas V.Kanure,

    2014-05-01

    Full Text Available Now days there are lots of websites present in internet. And providing different services to the client is not only important task for website owner but also protecting their website from different attacks. Now days Identification of vulnerabilities in web application is becoming serious issue. Protecting website by identifying vulnerabilities and taking important attack prevention steps is very much important task.Different vulnerabilities identification is based on different test cases which we have and which we are going to build by use of this tool. Those test cases come from combination of some effective code. SQL injection test case can work with effective database query. And Cross site scripting can works with some java script code or other scripting language code etc.

  8. Robustness of onion-like correlated networks against targeted attacks

    CERN Document Server

    Tanizawa, Toshihiro; Stanley, H Eugene

    2011-01-01

    Recently, it was found by Schneider et al. [Proc. Natl. Acad. Sci. USA, 108, 3838 (2011)], using simulations, that scale-free networks with "onion structure" are very robust against targeted high degree attacks. The onion structure is a network where nodes with almost the same degree are connected. Motivated by this work, we propose and analyze, based on analytical considerations, an onion-like candidate for a nearly optimal structure against simultaneous random and targeted high degree node attacks. The nearly optimal structure can be viewed as a hierarchically interconnected random regular graphs, the degrees and populations of which are specified by the degree distribution. This network structure exhibits an extremely assortative degree-degree correlation and has a close relationship to the "onion structure." After deriving a set of exact expressions that enable us to calculate the critical percolation threshold and the giant component of a correlated network for an arbitrary type of node removal, we apply...

  9. Attacks of Asthma due to Chlorinized Water: Case Report

    OpenAIRE

    Murat Eyup Berdan; Ercan Gocgeldi; Sami Ozturk; Ali Kutlu

    2008-01-01

    The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been reported. But, attacks of asthma which is related to chlorinized water is rare. Chlorine, a strong oxidizing agent, is an important toxic gas that the swimmer can breath during swimming and a worker can exposed to chlorine while he or she was using water with chlorine at home. We describe a persistent increase in nonspecific bronchial hyperresponsiveness following chronic exposure ...

  10. Robustness of networks against propagating attacks under vaccination strategies

    CERN Document Server

    Hasegawa, Takehisa

    2011-01-01

    We study the effect of vaccination on robustness of networks against propagating attacks that obey the susceptible-infected-removed model. By extending the generating function formalism developed by Newman (2005), we analytically determine the robustness of networks that depends on the vaccination parameters. We consider the random defense where nodes are vaccinated randomly and the degree-based defense where hubs are preferentially vaccinated. We apply the obtained results to the random graph and scale-free networks.

  11. Evaluation of Popcorn Germplasm for Resistance to Sesamia nonagrioides Attack

    OpenAIRE

    Revilla Temiño, Pedro; Butrón Gómez, Ana María; Sandoya Miranda, Germán; Malvar Pintos, Rosa Ana; Ordás Pérez, Amando

    2005-01-01

    Popcorn adapted to Spanish conditions could be an interesting and profitable alternative to field corn. However, little is known about breeding popcorn germplasm for adaptation to Spain. Sesamia nonagrioides Lefèvbre is the main insect pest affecting popcorn quality and yield under Spanish growing conditions. The objectives of the study were the search for sources of resistance to S. nonagrioides among popcorn germplasm and to study the genetics of the resistance to S. nonagrioides attack. Ei...

  12. A Review of Virtual Machine Attack Based on Xen

    Directory of Open Access Journals (Sweden)

    Ren xun-yi

    2016-01-01

    Full Text Available Virtualization technology as the foundation of cloud computing gets more and more attention because the cloud computing has been widely used. Analyzing the threat with the security of virtual machine and summarizing attack about virtual machine based on XEN to predict visible security hidden recently. Base on this paper can provide a reference for the further research on the security of virtual machine.

  13. Robustness of networks against propagating attacks under vaccination strategies

    International Nuclear Information System (INIS)

    We study the effect of vaccination on the robustness of networks against propagating attacks that obey the susceptible–infected–removed model. By extending the generating function formalism developed by Newman (2005 Phys. Rev. Lett. 95 108701), we analytically determine the robustness of networks that depends on the vaccination parameters. We consider the random defense where nodes are vaccinated randomly and the degree-based defense where hubs are preferentially vaccinated. We show that, when vaccines are inefficient, the random graph is more robust against propagating attacks than the scale-free network. When vaccines are relatively efficient, the scale-free network with the degree-based defense is more robust than the random graph with the random defense and the scale-free network with the random defense

  14. Animal attack: an unusual case of multiple trauma in childhood.

    LENUS (Irish Health Repository)

    O'Grady, E

    2014-11-01

    A 2½ year old girl attended our facility following attack by a tapir at a city zoo. She sustained multiple injuries including a forearm laceration and multiple perforating wounds to her abdominal wall. She had several procedures, including bowel resection, performed under the care of the General Paediatric Surgery and Plastic Surgery teams and was treated with a course of IV antibiotics. She recovered well and to date has suffered no long-term adverse outcome.

  15. [Hereditary angioedema. Treatment of acute attacks in Argentina].

    Science.gov (United States)

    Malbrán, Alejandro; Malbrán, Eloisa; Menéndez, Alejandra; Fernández Romero, Diego S

    2014-01-01

    In the world, hereditary angioedema (HAE) affects 1 every 50000 persons. It is characterized by highly disabling and recurrent episodes of cutaneous, abdominal and laryngeal episodes of angioedema. Asphyxia related mortality ranges from 15 to 50%. In Argentina a plasma derived C1 inhibitor concentrate (pdC1INH) has been available for the treatment of acute attacks for many decades, however, only15 (26%) out of 58 patients had received pdC1INH at least once until 2008, and only2 (3.4%) had used it regularly. After worldwide approval of the new drugs for the treatment of acute HAE attacks, adding icatibant to pdC1INH in Argentina, and after publication of the therapeutic guide for the country, 42 (82%) out of 51 patients from the original group has pdC1INH available to treat their next attack. However, 16 (18%) patients continue without access to medication and other 15 (35.7%) obtain their therapy spuriously through some other affected relative in their environment. Only 12 (28.6%) patients of the group self-treated at home. Access to treatment has greatly improved, but needs to be extended to all patients and self-treatment at home should be encouraged.

  16. High Doses of Fish Oil Might Help Healing After Heart Attack

    Science.gov (United States)

    ... Doses of Fish Oil Might Help Healing After Heart Attack Study found improved heart function, less scarring To ... 2, 2016 MONDAY, Aug. 1, 2016 (HealthDay News) -- Heart attack patients who took high doses of fish oil ...

  17. 3 CFR - Continuation of the National Emergency With Respect to Certain Terrorist Attacks

    Science.gov (United States)

    2010-01-01

    ... to Certain Terrorist Attacks Presidential Documents Other Presidential Documents Notice of September 10, 2009 Continuation of the National Emergency With Respect to Certain Terrorist Attacks Consistent... national emergency declared on September 14, 2001, in Proclamation 7463, with respect to the...

  18. Threat Assessment of Potential Terrorist Attacks to the Transport Infrastructure

    Directory of Open Access Journals (Sweden)

    Gabriel Nowacki

    2014-06-01

    Full Text Available The paper presents threat assessment of potential terrorist attacks to the transport infrastructure. The range of transportation infrastructure has spread and includes railway, inland waterways, road, maritime, air, intermodal transport infrastructure and intelligent transport systems (ITS. ITS service is the provision of an ITS application through a well-defined organisational and operational framework with the aim of contributing to the user safety, efficiency, comfort and/or to facilitate or support transport and travel operations. Terrorism means acts of violence committed by groups that view themselves as victimized by some notable historical wrong. Although these groups have no formal connection with governments, they usually have the financial and moral backing of sympathetic governments. Typically, they stage unexpected attacks on civilian targets, including transport infrastructure, with the aim of sowing fear and confusion. Based on the analyses, transportation infrastructure is potentially threatened with terrorism attacks, especially road and rail infrastructure (about 23 %, and to a smaller degree the maritime and air transport infrastructure (about 2 %. There were 90,3% of incidents involve land transport (74,5% – vehicles, 9,5% – buses, 6,3% - rail covered the 41-year period 1967-2007 in the USA. Legal steps to fight terrorism have been taken on the international level, furthermore, some institutions have been established for this purpose.

  19. Mass Change Prediction Model of Concrete Subjected to Sulfate Attack

    Directory of Open Access Journals (Sweden)

    Kwang-Myong Lee

    2015-01-01

    Full Text Available The present study suggested a mass change prediction model for sulfate attack of concrete containing mineral admixtures through an immersion test in sulfate solutions. For this, 100% OPC as well as binary and ternary blended cement concrete specimens were manufactured by changing the types and amount of mineral admixture. The concrete specimens were immersed in fresh water, 10% sodium sulfate solution, and 10% magnesium sulfate solution, respectively, and mass change of the specimens was measured at 28, 56, 91, 182, and 365 days. The experimental results indicated that resistance of concrete containing mineral admixture against sodium sulfate attack was far greater than that of 100% OPC concrete. However, in terms of resistance against magnesium sulfate attack, concrete containing mineral admixture was lower than 100% OPC concrete due to the formation of magnesium silicate hydrate (M-S-H, the noncementitious material. Ultimately, based on the experimental results, a mass change prediction model was suggested and it was found that the prediction values using the model corresponded relatively well with the experimental results.

  20. Comparison of artificial intelligence classifiers for SIP attack data

    Science.gov (United States)

    Safarik, Jakub; Slachta, Jiri

    2016-05-01

    Honeypot application is a source of valuable data about attacks on the network. We run several SIP honeypots in various computer networks, which are separated geographically and logically. Each honeypot runs on public IP address and uses standard SIP PBX ports. All information gathered via honeypot is periodically sent to the centralized server. This server classifies all attack data by neural network algorithm. The paper describes optimizations of a neural network classifier, which lower the classification error. The article contains the comparison of two neural network algorithm used for the classification of validation data. The first is the original implementation of the neural network described in recent work; the second neural network uses further optimizations like input normalization or cross-entropy cost function. We also use other implementations of neural networks and machine learning classification algorithms. The comparison test their capabilities on validation data to find the optimal classifier. The article result shows promise for further development of an accurate SIP attack classification engine.

  1. Flocking and invariance of velocity angles.

    Science.gov (United States)

    Liu, Le; Huang, Lihong; Wu, Jianhong

    2016-04-01

    Motsch and Tadmor considered an extended Cucker-Smale model to investigate the flocking behavior of self-organized systems of interacting species. In this extended model, a cone of the vision was introduced so that outside the cone the influence of one agent on the other is lost and hence the corresponding influence function takes the value zero. This creates a problem to apply the Motsch-Tadmor and Cucker-Smale method to prove the flocking property of the system. Here, we examine the variation of the velocity angles between two arbitrary agents, and obtain a monotonicity property for the maximum cone of velocity angles. This monotonicity permits us to utilize existing arguments to show the flocking property of the system under consideration, when the initial velocity angles satisfy some minor technical constraints. PMID:27105986

  2. Packet track and traceback mechanism against denial of service attacks

    Institute of Scientific and Technical Information of China (English)

    LI Li; SHEN Su-bin

    2008-01-01

    The denial of service attack is a main type of threat on the Internet today. On the basis of path identification (Pi) and Internet control message protocol (ICMP) traceback (iTrace) methods, a packet track and traceback mechanism is proposed, which features rapid response and high accuracy. In this scheme, routers apply packet marking scheme and send traceback messages, which enables the victim to design the path tree in peace time. During attack times the victim can trace attackers back within the path tree and perform rapid packet filtering using the marking in each packet. Traceback messages overcome Pi's limitation, wherein too much path information is lost in path identifiers; whereas path identifiers can be used to expedite the design of the path-tree, which reduces the high overhead in iTrace. Therefore, our scheme not only synthesizes the advantages but also compromises the disadvantages of the above two methods. Simulation results with NS-2 show the validity of our scheme.

  3. Precision measurements of the CKM angle gamma

    CERN Document Server

    CERN. Geneva

    2016-01-01

    The level of CP-violation permitted within the Standard Model cannot account for the matter dominated universe in which we live. Within the Standard Model the CKM matrix, which describes the quark couplings, is expected to be unitary. By making precise measurements of the CKM matrix parameters new physics models can be constrained, or with sufficient precision the effects of physics beyond the standard model might become apparent. The CKM angle gamma is the least well known angle of the unitarity triangle. It is the only angle easily accessible at tree-level, and furthermore has almost no theoretical uncertainties. Therefore it provides an invaluable Standard Model benchmark against which other new physics sensitive tests of the CP-violation can be made. I will discuss recent measurements of gamma using the the Run 1 LHCb dataset, which improve our knowledge of this key parameter.

  4. The Principles of Modern Attacks Analysis for Penetration Tester

    Directory of Open Access Journals (Sweden)

    Adam Ali.Zare Hudaib

    2015-03-01

    Full Text Available Modern cyber defense requires a realistic and thorough understanding of web application security issues. Anyone can learn to sling a few web hacks, but web application penetration testing requires something deeper. Major web application flaws and their exploitation, a field-tested and repeatable process to consistently finding these flaws and convey them will be discussed in this article. Modern attacks principles will be analyzed on purpose to create the most sufficient penetration tests.

  5. FPGA Implementation of a Statistical Saturation Attack against PRESENT

    OpenAIRE

    Kerckhof, Stéphanie; Collard, Baudoin; Standaert, François-Xavier; AFRICACRYPT 2011

    2011-01-01

    Statistical attacks against block ciphers usually exploit “characteristics”. A characteristic essentially defines a relation between (parts of) the block cipher’s inputs, outputs and intermediate values. Intuitively, a good characteristic is one for which the relation between the cipher’s inputs and outputs exhibit a significant deviation from the uniform distribution. Due to its intensive computational complexity, the search for good characteristics generally relies on heuristics, e.g. based...

  6. EFFICACY AND TOLERABILITY OF STOPAIN FOR A MIGRAINE ATTACK

    Directory of Open Access Journals (Sweden)

    Andrea eSt. Cyr

    2015-02-01

    Full Text Available ObjectiveTo determine whether topical menthol 6% gel will relieve a migraine attack.Materials and MethodsA single-center, open-label pilot trial of 25 patients with at least one year of diagnosed episodic migraine and < 15 headache days per month. Patients treated one migraine attack with STOPAIN topical menthol 6% gel to skull base within 2 hours of headache onset. Headache pain severity was assessed prior to and after gel application. ResultsThirty-two patients enrolled and 25 completed the study. Prior to treatment, seven patients had mild pain, 13 moderate pain, and five severe pain. Two hours following gel application, 7 patients had no pain, 7 mild pain, 6 moderate pain and 5 severe pain. The majority of patients had similar pain intensity (8; 32 % or improvement (13; 52%. At 24-hour, only 2 non-rescued patients still had mild headache. Of the 25 completers, two patients took rescue medication prior to the 2-hour period, and an additional 10 patients rescued between 2 and 24 hours. ConclusionStudy results showed a significant improvement in headache intensity by 2 hours after gel application. This pilot study shows STOPAIN gel may be effective in treating an acute migraine attack.

  7. Radon - an angle of view

    International Nuclear Information System (INIS)

    Apart from its radiation effects on living organism, radon induces the formation of atmospheric ions which are beneficial to man: some asthmatics can breathe more easily in an environment with elevated ion levels, the blood pH increases, the fraction of albumins is higher while the serotonin level is lower, sedimentation decreases and the leukocyte counts in peripherals diminish. The blood pressure, particularly in people suffering from hypertension, drops appreciably. The production of pituitary hormones as well as the overall sexual activity is stimulated by ions in air. Exposure to negative ions affects circulation through the skin, reduces skin temperature and improves overall resistance of the organism to infection. Negative ions also have a stimulating effect on mental activity and help against insomnia. Sites where radon is present in not too high concentrations are often famous as climatic spas. So, antiradon provisions, if exercised too thoroughly, may have adverse rather than positive consequences. All pros and cons should always be taken into account when deciding on antiradon steps. (P.A.)

  8. Scaling of misorientation angle distributions

    DEFF Research Database (Denmark)

    Hughes, D.A.; Chrzan, D.C.; Liu, Q.;

    1998-01-01

    for the small to large strain regimes for aluminum, 304L stainless steel, nickel, and copper (taken from the literature )appear to be identical. Hence the distributions may be "universal." These results have significant implications for the development of dislocation based deformation models. [S0031...

  9. Identifying optimal targets of network attack by belief propagation

    Science.gov (United States)

    Mugisha, Salomon; Zhou, Hai-Jun

    2016-07-01

    For a network formed by nodes and undirected links between pairs of nodes, the network optimal attack problem aims at deleting a minimum number of target nodes to break the network down into many small components. This problem is intrinsically related to the feedback vertex set problem that was successfully tackled by spin-glass theory and an associated belief propagation-guided decimation (BPD) algorithm [Zhou, Eur. Phys. J. B 86, 455 (2013), 10.1140/epjb/e2013-40690-1]. In the present work we apply the BPD algorithm (which has approximately linear time complexity) to the network optimal attack problem and demonstrate that it has much better performance than a recently proposed collective information algorithm [Morone and Makse, Nature 524, 65 (2015), 10.1038/nature14604] for different types of random networks and real-world network instances. The BPD-guided attack scheme often induces an abrupt collapse of the whole network, which may make it very difficult to defend.

  10. Prevention of Buffer overflow Attack Blocker Using IDS

    Directory of Open Access Journals (Sweden)

    Pankaj B. Pawar

    2012-10-01

    Full Text Available Now a day internet threat takes a blended attack form, targetingindividual users to gain control over networks and data. BufferOverflow which is one of the most occurring securityvulnerabilities in a Computer’s world. Buffer Overflow occurswhile writing data to a buffer and it overruns the buffer'sboundary and overwrites it to a adjacent memory. The techniquesto exploit buffer overflow vulnerability vary per architecture,Operating system and memory region. There are variousexploitation which causes to buffer overflow attack as stackbased exploitation, heap based exploitation and choice ofprogramming language and many more. Which may result inerratic program behavior, including memory access errors,incorrect results, a crash or a breach of system security. C andC++ are the two programming languages which do not check thatdata has overwritten to an array that results to an buffer overflow.There are many more techniques which has been used forprotecting the Computer from buffer overflow attack We areproposing a novel techniques for preventing data loss duringthe transmission of images of different formats. In this paper wehave discuss and compare certain tools and techniques whichprevent buffer overflows. We have also discuss some moderntools and techniques with their pros and cons.

  11. A taxonomy and discussion of software attack technologies

    Science.gov (United States)

    Banks, Sheila B.; Stytz, Martin R.

    2005-03-01

    Software is a complex thing. It is not an engineering artifact that springs forth from a design by simply following software coding rules; creativity and the human element are at the heart of the process. Software development is part science, part art, and part craft. Design, architecture, and coding are equally important activities and in each of these activities, errors may be introduced that lead to security vulnerabilities. Therefore, inevitably, errors enter into the code. Some of these errors are discovered during testing; however, some are not. The best way to find security errors, whether they are introduced as part of the architecture development effort or coding effort, is to automate the security testing process to the maximum extent possible and add this class of tools to the tools available, which aids in the compilation process, testing, test analysis, and software distribution. Recent technological advances, improvements in computer-generated forces (CGFs), and results in research in information assurance and software protection indicate that we can build a semi-intelligent software security testing tool. However, before we can undertake the security testing automation effort, we must understand the scope of the required testing, the security failures that need to be uncovered during testing, and the characteristics of the failures. Therefore, we undertook the research reported in the paper, which is the development of a taxonomy and a discussion of software attacks generated from the point of view of the security tester with the goal of using the taxonomy to guide the development of the knowledge base for the automated security testing tool. The representation for attacks and threat cases yielded by this research captures the strategies, tactics, and other considerations that come into play during the planning and execution of attacks upon application software. The paper is organized as follows. Section one contains an introduction to our research

  12. Analysis and visualization of large complex attack graphs for networks security

    Science.gov (United States)

    Chen, Hongda; Chen, Genshe; Blasch, Erik; Kruger, Martin; Sityar, Irma

    2007-04-01

    In this paper, we have proposed a comprehensive and innovative approach for analysis and visualization of large complex multi-step cyber attack graphs. As an automated tool for cyber attack detection, prediction, and visualization, the newly proposed method transforms large quantities of network security data into real-time actionable intelligence, which can be used to (1) provide guidance on network hardening to prevent attacks, (2) perform real-time attack event correlation during active attacks, and (3) formulate post-attack responses. We show that it is possible to visualize the complex graphs, including all possible network attack paths while still keeping complexity manageable. The proposed analysis and visualization tool provides an efficient and effective solution for predicting potential attacks upon observed intrusion evidence, as well as interactive multi-resolution views such that an analyst can first obtain high-level overviews quickly, and then drill down to specific details.

  13. Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects

    Science.gov (United States)

    Jiang, Yuzhen; Chang, Dolly S.; Zhu, Haogang; Khawaja, Anthony P.; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M.

    2015-01-01

    Objective To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Design Longitudinal cohort study. Participants Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Methods Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Main Outcome Measures Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. Results No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1

  14. 29 CFR 18.806 - Attacking and supporting credibility of declarant.

    Science.gov (United States)

    2010-07-01

    ... HEARINGS BEFORE THE OFFICE OF ADMINISTRATIVE LAW JUDGES Rules of Evidence Hearsay § 18.806 Attacking and...), (iv), or (v), has been admitted in evidence, the credibility of the declarant may be attacked, and if attacked may be supported, by any evidence which would be admissible for those purposes if declarant...

  15. COMPARING THE IMPACT OF BLACK HOLE AND GRAY HOLE ATTACKS IN MOBILE ADHOC NETWORKS

    Directory of Open Access Journals (Sweden)

    Bose

    2012-01-01

    Full Text Available Mobile Adhoc Networks (MANETs are dynamic in nature. Any nodes can join and leave the network at any time. Hence any type of intruders can attack the communication at any time, especially the routing mechanism between the nodes. In this study, we study and understand two types of attacks which cause more damage to the routing performance of MANET; the attacks are Black Hole attacks and Gray Hole attacks and compare the impact of these attacks on MANET. “Send Fake Route Reply to the nodes” type of attack is used to understand the behavior of these two types of attacks. Existing AODV protocol is modified in order to study these types of attacks in MANET. Performance evaluation of the proposed method is carried out using NS-2. In the presence of these attacks the network performance degrades for various network attributes. The performance of MANET under attack is thoroughly investigated, by applying it on various network parameters with various node densities. Not only had that which attack causes more damage to the environment also studied.

  16. Robustness of two-way quantum communication protocols against Trojan horse attack

    CERN Document Server

    Deng, F G; Li, X H; Zhou, H Y; Zhou, P

    2005-01-01

    We discuss the robustness of two-way quantum communication protocols against Trojan horse attack and introduce a novel attack, delay-photon Trojan horse attack. Moreover, we present a practical way for two-way quantum communication protocols to prevent the eavesdropper from stealing the information transmitted with Trojan horse attacks. It means that two-way quantum communication protocols is also secure in a practical application.

  17. Shark attack.

    Science.gov (United States)

    Guidera, K J; Ogden, J A; Highhouse, K; Pugh, L; Beatty, E

    1991-01-01

    Shark attacks are rare but devastating. This case had major injuries that included an open femoral fracture, massive hemorrhage, sciatic nerve laceration, and significant skin and muscle damage. The patient required 15 operative procedures, extensive physical therapy, and orthotic assistance. A review of the literature pertaining to shark bites is included.

  18. Symptom Induction and De-escalation in the Treatment of Panic Attacks.

    Science.gov (United States)

    Dattilio, Frank M.

    1990-01-01

    Describes technique known as symptom induction and de-escalation for panic attacks in which goal is to reproduce the type of situation that may precipitate an attack and then to show the client how the attacks can be "turned on" as well as "turned off." (ABL)

  19. Status of the CDF small angle spectrometer

    International Nuclear Information System (INIS)

    During the 1987 Tevatron collider period the CDF small angle spectrometer system was partially installed and elastic scattering events were recorded in a special high-β run. The design and physics goals of this system are described and results from an analysis of the elastic scattering data are discussed

  20. The attack navigator

    DEFF Research Database (Denmark)

    Probst, Christian W.; Willemson, Jan; Pieters, Wolter

    2016-01-01

    that are caused by the strategic behaviour of adversaries. Therefore, technology-supported methods are needed to help us identify and manage these risks. In this paper, we describe the attack navigator: a graph-based approach to security risk assessment inspired by navigation systems. Based on maps of a socio......-technical system, the attack navigator identifies routes to an attacker goal. Specific attacker properties such as skill or resources can be included through attacker profiles. This enables defenders to explore attack scenarios and the effectiveness of defense alternatives under different threat conditions....

  1. Research on Coordinated Antisumarine Attack Effeciency of Two Helicopters Under Countermeasures

    Institute of Scientific and Technical Information of China (English)

    丁红岩; 董晓明; 蹇明裕

    2012-01-01

    The organization of coordinated attack and the selection of aiming point which affect hit probability were analyzed for the countermeasures taken by the hostile submarines at two helicopters' coordinated attack.A computational model of coordinated attack parameters,a model of submarine maneuver,and a model of noise jammer were established.Compared to single helicopter' torpedo attack,the coordinated attack of two helicopters can effectively increase the hit probability of torpedo and achieve the higher target detecting probability under counterwork condition.

  2. The accountability problem of flooding attacks in service-oriented architectures

    DEFF Research Database (Denmark)

    Jensen, Meiko; Schwenk, Jörg

    2009-01-01

    The threat of Denial of Service attacks poses a serious problem to the security of network-based services in general. For flooding attacks against service-oriented applications, this threat is dramatically amplified with potentially much higher impact and very little effort on the attacker's side....... Additionally, due to the high distribution of a SOA application's components, fending such attacks becomes a far more complex task. In this paper, we present the problem of accountability, referring to the issue of resolving the attacker in a highly distributed service-oriented application. Using a general...

  3. Experimental Validation of the Invariance of Electrowetting Contact Angle Saturation

    NARCIS (Netherlands)

    Chevalliot, S.; Dhindsa, M.; Kuiper, S.; Heikenfeld, J.

    2011-01-01

    Basic electrowetting theory predicts that a continued increase in applied voltage will allow contact angle modulation to zero degrees. In practice, the effect of contact angle saturation has always been observed to limit the contact angle modulation, often only down to a contact angle of 60 to 70°.

  4. A fringe shadow method for measuring flapping angle and torsional angle of a dragonfly wing

    Science.gov (United States)

    Zeng, Lijiang; Matsumoto, Hirokazu; Kawachi, Keiji

    1996-05-01

    A fringe shadow (FS) method was developed for measuring the flapping angle and torsional angle of a dragonfly wing during beating motion. This new method involves two sets of fringe patterns projected onto the wing from orthogonal directions. The torsional angle is determined using the length of the shadow of the wing chord that is cast by the two sets of fringe patterns. The flapping angle is determined using the shadowgraph of the wing projected by a laser. The advantages of the FS method are its capability (i) to measure the flapping angle and torsional angle of a dragonfly wing simultaneously using only one high-speed camera and (ii) to recognize the spanwise position of a section from the number of fringes, without having to use diffuse marks that are common in current methods. The resolution of the FS method can be changed easily by adjusting the fringe spacing. The measurement results for the torsional angle and flapping angle of a dragonfly wing prove the effectiveness of the FS method in studying the flight performance of dragonflies.

  5. Behavioral Modeling of WSN MAC Layer Security Attacks: A Sequential UML Approach

    DEFF Research Database (Denmark)

    Pawar, Pranav M.; Nielsen, Rasmus Hjorth; Prasad, Neeli R.;

    2012-01-01

    of medium access control (MAC) security attacks in WSNs. The MAC layer is responsible for energy consumption, delay and channel utilization of the network and attacks on this layer can introduce significant degradation of the individual sensor nodes due to energy drain and in performance due to delays....... The behavioral modeling of attacks will be beneficial for designing efficient and secure MAC layer protocols. The security attacks are modeled using a sequential diagram approach of Unified Modeling Language (UML). Further, a new attack definition, specific to hybrid MAC mechanisms, is proposed....

  6. Mathematical Attacks on RSA Cryptosystem

    Directory of Open Access Journals (Sweden)

    Imad K. Salah

    2006-01-01

    Full Text Available In this paper some of the most common attacks against Rivest, Shamir, and Adleman (RSA cryptosystem are presented. We describe the integer factoring attacks, attacks on the underlying mathematical function, as well as attacks that exploit details in implementations of the algorithm. Algorithms for each type of attacks are developed and analyzed by their complexity, memory requirements and area of usage.

  7. Risk factors of transient ischemic attack: An overview

    Directory of Open Access Journals (Sweden)

    Supreet Khare

    2016-01-01

    Full Text Available Transient ischemic attack (TIA is a transient episode of neurologic dysfunction caused due to loss of blood flow to the brain or spinal cord without acute infarction. Depending on the area of the brain involved, symptoms of TIA vary widely from patient to patient. Since the blockage period in TIA is very short-lived, there is no permanent damage. Risk factors for TIA include family history of stroke or TIA, age above 55 years or older, higher risk of TIA in males than females, high blood pressure, diabetes mellitus, and tobacco smoking. Genetics, race, and imbalance in lipid profile are other risk factors of TIA. TIA is usually diagnosed after taking a thorough history and a physical examination. Several radiological tests such as computed tomography and magnetic resonance imaging are useful in the evaluation of patients who have had a TIA. Ultrasound of the neck and an echocardiogram of the heart are other tests useful in the diagnosis and evaluation of the attack. The treatment following acute recovery from a TIA depends on the underlying cause. Patients who have more than 70% stenosis of the carotid artery, removal of atherosclerotic plaque is usually done by carotid endarterectomy surgery. One-third of the people with TIA can later have recurrent TIAs and one-third can have a stroke because of permanent nerve cell loss. Having a TIA is a risk factor for eventually having a stroke. Educating the patients and inculcating lifestyle modifications in them are initial steps to minimize the prevalence of transient ischemic attack.

  8. Risk factors of transient ischemic attack: An overview.

    Science.gov (United States)

    Khare, Supreet

    2016-01-01

    Transient ischemic attack (TIA) is a transient episode of neurologic dysfunction caused due to loss of blood flow to the brain or spinal cord without acute infarction. Depending on the area of the brain involved, symptoms of TIA vary widely from patient to patient. Since the blockage period in TIA is very short-lived, there is no permanent damage. Risk factors for TIA include family history of stroke or TIA, age above 55 years or older, higher risk of TIA in males than females, high blood pressure, diabetes mellitus, and tobacco smoking. Genetics, race, and imbalance in lipid profile are other risk factors of TIA. TIA is usually diagnosed after taking a thorough history and a physical examination. Several radiological tests such as computed tomography and magnetic resonance imaging are useful in the evaluation of patients who have had a TIA. Ultrasound of the neck and an echocardiogram of the heart are other tests useful in the diagnosis and evaluation of the attack. The treatment following acute recovery from a TIA depends on the underlying cause. Patients who have more than 70% stenosis of the carotid artery, removal of atherosclerotic plaque is usually done by carotid endarterectomy surgery. One-third of the people with TIA can later have recurrent TIAs and one-third can have a stroke because of permanent nerve cell loss. Having a TIA is a risk factor for eventually having a stroke. Educating the patients and inculcating lifestyle modifications in them are initial steps to minimize the prevalence of transient ischemic attack.

  9. The resilience of interdependent transportation networks under targeted attack

    CERN Document Server

    Zhang, Peng; Zhao, Zhuang; Li, Daqing; Lu, Guangquan; Wang, Yunpeng; Xiao, Jinghua

    2013-01-01

    Modern world builds on the resilience of interdependent infrastructures characterized as complex networks. Recently, a framework for analysis of interdependent networks has been developed to explain the mechanism of resilience in interdependent networks. Here we extend this interdependent network model by considering flows in the networks and study the system's resilience under different attack strategies. In our model, nodes may fail due to either overload or loss of interdependency. Under the interaction between these two failure mechanisms, it is shown that interdependent scale-free networks show extreme vulnerability. The resilience of interdependent SF networks is found in our simulation much smaller than single SF network or interdependent SF networks without flows.

  10. Design and Analysis of an Attack Resilient and Adaptive Medium access Control Protocol for Computer Networks

    CERN Document Server

    Shukla, Piyush Kumar; Bhadoria, Dr Sarita Singh

    2009-01-01

    The challenge of designing an efficient Medium Access Control (MAC) protocol and analyzing it has been an important research topic for over 30 years. This paper focuses on the performance analysis (through simulation) and modification of a well known MAC protocol CSMA/CD. The existing protocol does not consider the wastage of bandwidth due to unutilized periods of the channel. By considering this fact, performance of MAC protocol can be enhanced. The purpose of this work is to modify the existing protocol by enabling it to adapt according to state of the network. The modified protocol takes appropriate action whenever unutilized periods detected. In this way, to increase the effective bandwidth utilization and determine how it behaves under increasing load, and varying packet sizes. It will also include effects of attacks i.e. Denial of service attacks, Replay Attack, Continuous Channel Access or Exhaustion attack, Flooding attack, Jamming (Radio interference) attack, Selective forwarding attack which degrade...

  11. WLAN Security-Active Attack of WLAN Secure Network

    Directory of Open Access Journals (Sweden)

    Anil Kumar Singh

    2011-05-01

    Full Text Available In Wireless Local Area Network data transfer from one node to another node via air in the form of radio waves. There is no physical medium for transferring the data like traditional LAN. Because of its susceptible nature WLAN can open the door for the intruders and attackers that can come from any direction. Security is the most important element in WLAN. MAC address filtering is one of the security methods for securing the WLAN. But it is also vulnerable. In this paper we will demonstrate how hackers exploit the WLAN vulnerability (Identity theft of legitimate user to access the Wireless Local Area Network.

  12. Attack Coverage in High-Level Men's Volleyball: Organization on the Edge of Chaos?

    Science.gov (United States)

    Laporta, Lorenzo; Nikolaidis, Pantelis; Thomas, Luke; Afonso, José

    2015-09-29

    Change is pervasive, but emerging patterns are occasionally detectable through analysis of systemic behaviors. Match analysis uses these patterns in order to reduce the degree of improvisation and to optimize the training process. However, it is possible that certain game phases elude systematic patterning. In this vein, our aim was to analyze the case of attack coverage in men's volleyball, as we suspected it would elude systematic patterning and has received negligible attention in scientific research. We analyzed the occurrence of attack coverage in 4544 plays of the 2011 Volleyball World League. A Chi-square test with residual adjusted values was applied to explore significant associations between variables. A Monte Carlo correction was applied, as some cells had n<5. Effect sizes were determined using Cramer's V. Overall, attack coverage occurred in 3.89% of ball possessions, and 23 distinct structures emerged. These structures lacked significant associations with the game complex, setting zone, and effect of attack coverage. Conversely, attack coverage structures showed significant associations with the attack zone and tempo, with very strong effect sizes (V=0.472 and V=0.521, respectively). As certain attack zones are deeply associated with attack tempo, it is apparent that quicker attack plays affect attack coverage structuring, promoting the formation of less complex structures. Ultimately, attack coverage structures seem to depend on momentary constraints, thereby rendering rigid systematization impracticable. Still, we contended that a principle-based approach might be suitable. This invites researchers to rethink how to interpret game regularities. PMID:26557208

  13. Cultural Memory of Sorrow in Advertising after the Terrorist Attacks

    OpenAIRE

    Esther Martínez Pastor; Clara Simón

    2015-01-01

    The general objective of this research study is to do a comparative research to investigate the perception of sorrow in the advertising in the press after the terrorist attacks: 11/09/2001 (U.S.) and 11/04/2004 (Spain). The general hypothesis considers that there are similar perceptions of the sorrow towards the ads although there are cultural differences. On a computer program the subject was shown these images about announcement advertisement published in the press after the 09/11 and 11/04...

  14. Cultural Memory of Sorrow in Advertising after the Terrorist Attacks

    Directory of Open Access Journals (Sweden)

    Esther Martínez Pastor

    2015-09-01

    Full Text Available The general objective of this research study is to do a comparative research to investigate the perception of sorrow in the advertising in the press after the terrorist attacks: 11/09/2001 (U.S. and 11/04/2004 (Spain. The general hypothesis considers that there are similar perceptions of the sorrow towards the ads although there are cultural differences. On a computer program the subject was shown these images about announcement advertisement published in the press after the 09/11 and 11/04 in a random order and was asked different questions that explored their perception and attitudes with regard to these advertisements

  15. Simulating effectiveness of helicopter evasive manoeuvres to RPG attack

    Science.gov (United States)

    Anderson, D.; Thomson, D. G.

    2010-04-01

    The survivability of helicopters under attack by ground troops using rocket propelled grenades has been amply illustrated over the past decade. Given that an RPG is unguided and it is infeasible to cover helicopters in thick armour, existing optical countermeasures are ineffective - the solution is to compute an evasive manoeuvre. In this paper, an RPG/helicopter engagement model is presented. Manoeuvre profiles are defined in the missile approach warning sensor camera image plane using a local maximum acceleration vector. Required control inputs are then computed using inverse simulation techniques. Assessments of platform survivability to several engagement scenarios are presented.

  16. Mars attacks.

    Science.gov (United States)

    Cohain, Judy Slome

    2008-01-01

    "Mars Attacks" is a new term coined to describe unjustified violation of women by care providers at the time of birth, as well as the purposeful abandonment of the peer review system by major obstetric journals and the abandonment of the use of research evidence by ACOG in their latest protocols, in order to justify continued use of this form of violence against women. PMID:19244777

  17. Cognitive models for the concept of angle

    OpenAIRE

    Matos, José Manuel Leonardo de

    1999-01-01

    The instructional models taught in class were similar to the students' models. The teachers addressed angle as a basic-level category, discussed its submodels, clarified the boundaries, and established cognitive reference points. They gradually increased the use of complex metaphors and of several models. The study enriched the characterization of the first two levels of van Hiele theory and demonstrated the value of categorization theory in understanding how our comprehension ...

  18. Magnetic resonance colonography in severe attacks of ulcerative colitis

    Energy Technology Data Exchange (ETDEWEB)

    Savoye-Collet, C.; Roset, J.B.; Koning, E.; Dacher, J.N. [Rouen University Hospital Charles Nicolle, Radiology Department - QUANTIF - LITIS EA 4108, Rouen (France); Charpentier, C.; Hommel, S.; Lerebours, E.; Savoye, G. [Rouen University Hospital Charles Nicolle, Gastroenterology Department - ADEN U 1073, Rouen (France)

    2012-09-15

    To evaluate the ability of MR colonography (MRC) to detect lesions in severe attacks of ulcerative colitis (UC) and to assess its concordance with rectosigmoidoscopy. Eighteen patients underwent MRC and rectosigmoidoscopy. MRC consisted of a water-filled colonic procedure followed by T1/T2w images. Image quality was recorded. Inflammatory lesions and the existence of signs of severity were analysed. We calculated MR accuracy in the diagnosis of inflammatory lesions, as well as per segment and per patient concordance depending on the presence or absence of severe lesions. The MR image quality of the 108 segments was satisfactory. Endoscopy was used to study 36 segments (rectum and sigmoid). MRC had a positive predictive value of 100% and a sensitivity of 64% in the diagnosis of inflammatory lesions. Concordance for the diagnosis of severe lesions was excellent for the rectum (k = 0.85) and good for the sigmoid (k = 0.64). MRC diagnosed signs of severity in all patients affected at endoscopy. MRC also disclosed signs of severity located higher in the colon in four patients with nonsevere lesions at rectosigmoidoscopy. MRC can accurately diagnose inflammatory lesions in severe attacks of UC and significantly correlates with rectosigmoidoscopy in the diagnosis of severe lesions. (orig.)

  19. Detection of malicious attacks by Meta classification algorithms

    Directory of Open Access Journals (Sweden)

    G.Michael

    2015-03-01

    Full Text Available We address the problem of malicious node detection in a network based on the characteristics in the behavior of the network. This issue brings out a challenging set of research papers in the recent contributing a critical component to secure the network. This type of work evolves with many changes in the solution strategies. In this work, we propose carefully the learning models with cautious selection of attributes, selection of parameter thresholds and number of iterations. In this research, appropriate approach to evaluate the performance of a set of meta classifier algorithms (Ad Boost, Attribute selected classifier, Bagging, Classification via Regression, Filtered classifier, logit Boost, multiclass classifier. The ratio between training and testing data is made such way that compatibility of data patterns in both the sets are same. Hence we consider a set of supervised machine learning schemes with meta classifiers were applied on the selected dataset to predict the attack risk of the network environment . The trained models were then used for predicting the risk of the attacks in a web server environment or by any network administrator or any Security Experts. The Prediction Accuracy of the Classifiers was evaluated using 10-fold Cross Validation and the results have been compared to obtain the accuracy.

  20. Pericarditis - after heart attack

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000166.htm Pericarditis - after heart attack To use the sharing features on this page, ... occur in the days or weeks following a heart attack. Causes Two types of pericarditis can occur after ...

  1. Measurements of Neutrino Oscillation Angle theta_13

    CERN Document Server

    Kuze, Masahiro

    2013-01-01

    Neutrinos exhibit an interesting phenomenon called 'neutrino oscillation', in which a neutrino changes its flavor after traveling some flight length. Many experiments measured the mixing angles and mass differences, but the angle $\\theta_{13}$ had been unmeasured due to its smallness compared to others. During 2011 and 2012, series of new-generation neutrino experiments reported positive results in $\\theta_{13}$ search, and its value has been determined to be just below the previous upper limit. The non-zero result of $\\theta_{13}$ is a very good news for future of neutrino physics, since it opens a possibility of measuring the CP violation phase in the lepton sector. An introduction to neutrino oscillation and latest experimental results are presented. A detail is put on Double Chooz reactor experiment, in which the author is involved.

  2. Perceptions of tilt angles of an agricultural tractor.

    Science.gov (United States)

    Görücü, Serap; Cavallo, Eugenio; Murphy, Dennis

    2014-01-01

    A tractor stability simulator has been developed to help study tractor operators' perceptions of angles when the simulator is tilted to the side. The simulator is a trailer-mounted tractor cab equipped with hydraulic lift that can tilt the tractor cabin up to 30 degrees. This paper summarizes data from 82 participants who sat in the simulator while it was tilted. Demographic variables, estimates of tilt angles, and measured tilt angles were collected. The effects of age, gender, tractor driving experience, and frequency of operation on the estimated and measured tilt angles were analyzed. The results showed that about 50% of the participants reported estimations of side tilt angles within ±5 degrees of the actual angles, and nearly the same percentage overestimated the actual side tilt angles. Only a small percentage underestimated the angles. Older, more experienced, and male participants set higher limits on the actual angle at which they felt uncomfortable and would not drive. PMID:24417527

  3. The triggers or precipitants of the acute migraine attack.

    Science.gov (United States)

    Kelman, L

    2007-05-01

    The aim of this study was to evaluate and define the triggers of the acute migraine attack. Patients rated triggers on a 0-3 scale for the average headache. Demographics, prodrome, aura, headache characteristics, postdrome, medication responsiveness, acute and chronic disability, sleep characteristics and social and personal characteristics were also recorded. One thousand two hundred and seven International Classification of Headache Disorders-2 (1.1-1.2, and 1.5.1) patients were evaluated, of whom 75.9% reported triggers (40.4% infrequently, 26.7% frequently and 8.8% very frequently). The trigger frequencies were stress (79.7%), hormones in women (65.1%), not eating (57.3%), weather (53.2%), sleep disturbance (49.8%), perfume or odour (43.7%), neck pain (38.4%), light(s) (38.1%), alcohol (37.8%), smoke (35.7%), sleeping late (32.0%), heat (30.3%), food (26.9%), exercise (22.1%) and sexual activity (5.2%). Triggers were more likely to be associated with a more florid acute migraine attack. Differences were seen between women and men, aura and no aura, episodic and chronic migraine, and between migraine and probable migraine.

  4. Multi-Level Parsing Based Approach Against Phishing Attacks With the Help of Knowledge Bases

    Directory of Open Access Journals (Sweden)

    Gaurav Kumar Tak

    2013-11-01

    Full Text Available The increasing use of internet all over the world,be it in households or in corporate firms, has ledto anunprecedented rise in cyber-crimes. Amongst these the major chunk consists of Internet attacks which arethe most popular and common attacks are carried over the internet. Generally phishing attacks, SSLattacks and some other hacking attacks are kept into this category. Security against these attacks isthemajor issue of internet security in today’s scenario where internet has very deep penetration. Internet hasno doubt made our lives very convenient. It has provided many facilities to us at penny’s cost. For instanceit has made communication lightning fast and that too at a very cheap cost. But internet can pose addedthreats for those users who are not well versed inthe ways of internet and unaware of the security risksattached with it. Phishing Attacks, Nigerian Scam,Spam attacks, SSL attacks and other hacking attacksaresome of the most common and recent attacks to compromise the privacy of the internet users. Many a timesif the user isn’t careful, then these attacks are able to steal the confidential information of user (orunauthorized access. Generally these attacks are carried out with the help of social networking sites,popular mail server sites, online chatting sites etc. Nowadays, Facebook.com, gmail.com, orkut.com andmany other social networking sites are facing thesesecurity attack problems.This paper discusses a Knowledge Base Compound approach which is based on query operations andparsing techniques to counter these internet attacks using the web browser itself. In this approach wepropose to analyze the web URLs before visiting theactual site, so as to provide security against webattacks mentioned above. This approach employs various parsing operations and query processing whichuse many techniques to detect the phishing attacksas well as other web attacks. The aforementionedapproach is completely based on operation through the

  5. Practising of radiological emergency caused by a terrorist attack

    International Nuclear Information System (INIS)

    After the events of September 11, 2001 terrorist working has become an important factor in the forecasts to adopt in the face of the possibility of confronting different radiological emergencies. The not wanted events of exposure to ionizing radiations can take place by flaws of systems or accidents, or also by criminal voluntary actions. These malevolent actions can include attacks or sabotages in nuclear plants, detonation of manufactured nuclear devices or acquired under ground, robbery of radioactive sources to manufacture the calls dirty bombs or to cause damage, panic or threats. In the scenarios in that the radiological emergency is voluntarily provoked the moment and place of the attack are chosen by the aggressors, therefore the ionizing radiations will be in not prepared atmospheres neither equipped to the effect. This increases the confusion, the panic and the damage not only caused by the radiation effects but also by the uncertainty and consequent reactions. To diminish the effects of this type of threats it is necessary to make forecasts and to train the personnel that it can be direct or indirectly involved. During 2005, an exercise in which it was outlined the robbery by part of a group command of a source of Co 60 of 5000 Ci that it was transported to make a decanting in a medical center of The Pampa county, Argentina. It was about a cabinet exercise, planned and executed jointly among the Nuclear Regulatory Authority and the Secretary of Interior Safety, in which participated the professionals of the nuclear area that by law are the responsible ones of coordinating the actions in the event of an emergency of this type, and the safety forces that depend of the Secretary of Interior Safety, Federal and Provincial Policemen, Naval Prefecture and National Gendarmerie. The exercise last one day during which 9 main situations were approached that were unchained after having produced the attack and initial robbery. For each situation it was checked the

  6. Strategies of detecting Profile-injection attacks in E-Commerce Recommender System: A survey Partha

    Directory of Open Access Journals (Sweden)

    Sarathi Chakraborty,

    2015-12-01

    Full Text Available E-commerce recommender systems are vulnerable to different types of shilling attack where the attacker influences the recommendation procedure in favor of him by inserting fake user-profiles into the system. From one point of view, the attacks can be of type push or nuke-either to promote or to demote a product. On the other hand, attacks can be classified as high-knowledge or low-knowledge attack depending on the amount of system knowledge required for making the attack successful. Several research works have been done in the last two decades for defending attacks on recommender systems. In this paper, we have surveyed the major works done in this area by different researchers. After a brief explanation of different attack types and attack models, we discussed the attack detection strategies proposed by the researchers mainly under five categories- Generic and model specific attribute based, rating distribution based, outlier analysis based, statistical approach based and clustering based.

  7. Importance of Video-EEG Monitoring in the Diagnosis of Refractory Panic Attacks

    Directory of Open Access Journals (Sweden)

    Batool F. Kirmani

    2013-01-01

    Full Text Available Partial seizures can be misdiagnosed as panic attacks. There is considerable overlap of symptoms between temporal lobe seizures and panic attacks making the diagnosis extremely challenging. Temporal lobe seizures can present with intense fear and autonomic symptoms which are also seen in panic disorders. This results in delay in diagnosis and management. We report an interesting case of a young woman who was diagnosed with right temporal lobe seizures with symptoms suggestive of a panic attack.

  8. Importance of Video-EEG Monitoring in the Diagnosis of Refractory Panic Attacks

    OpenAIRE

    Kirmani, Batool F.; Diana Mungall

    2013-01-01

    Partial seizures can be misdiagnosed as panic attacks. There is considerable overlap of symptoms between temporal lobe seizures and panic attacks making the diagnosis extremely challenging. Temporal lobe seizures can present with intense fear and autonomic symptoms which are also seen in panic disorders. This results in delay in diagnosis and management. We report an interesting case of a young woman who was diagnosed with right temporal lobe seizures with symptoms suggestive of a panic attack.

  9. Characteristic features of injuries due to shark attacks: a review of 12 cases.

    Science.gov (United States)

    Ihama, Yoko; Ninomiya, Kenji; Noguchi, Masamichi; Fuke, Chiaki; Miyazaki, Tetsuji

    2009-09-01

    Shark attacks on humans might not occur as often as is believed and the characteristic features of shark injuries on corpses have not been extensively reviewed. We describe the characteristic features of shark injuries on 12 corpses. The analysis of these injuries might reveal the motivation behind the attacks and/or the shark species involved in the attack. Gouge marks on the bones are evidence of a shark attack, even if the corpse is decomposed. Severance of the body part at the joints without a fracture was found to be a characteristic feature of shark injuries.

  10. Cooperating attackers in neural cryptography.

    Science.gov (United States)

    Shacham, Lanir N; Klein, Einat; Mislovaty, Rachel; Kanter, Ido; Kinzel, Wolfgang

    2004-06-01

    A successful attack strategy in neural cryptography is presented. The neural cryptosystem, based on synchronization of neural networks by mutual learning, has been recently shown to be secure under different attack strategies. The success of the advanced attacker presented here, called the "majority-flipping attacker," does not decay with the parameters of the model. This attacker's outstanding success is due to its using a group of attackers which cooperate throughout the synchronization process, unlike any other attack strategy known. An analytical description of this attack is also presented, and fits the results of simulations.

  11. AN ANALYSIS OF CURRENT COMPUTER NETWORK ATTACK PROCEDURES, THEIR MITIGATION MEASURES AND THE DEVELOPMENT OF AN IMPROVED DENIAL OF SERVICE (DoS ATTACK MODEL

    Directory of Open Access Journals (Sweden)

    IHEKWEABA OGECHI

    2013-04-01

    Full Text Available This paper presents the major network attack profiles, taxonomies, classification and identification frameworks. Further, current approaches for intrusion detection on networks were x-rayed though, with emphasis on Denial of Service (DoS attacks only. The concept of intelligent agents and subsequently adaptive systems was elucidated, the properties derived were used as a proof of concept, and then applied in the development of a model for an adaptive intelligent multi-agent for network protection, against denial of service attacks.

  12. Performance Analysis of AODV under Black Hole Attack through Use of OPNET Simulator

    CERN Document Server

    Esmaili, H A; gharaee, Hossein

    2011-01-01

    Mobile ad hoc networks (MANETs) are dynamic wireless networks without any infrastructure. These networks are weak against many types of attacks. One of these attacks is the black hole. In this attack, a malicious node advertises itself as having freshest or shortest path to specific node to absorb packets to itself. The effect of black hole attack on ad hoc network using AODV as a routing protocol will be examined in this research. Furthermore, we investigate solution for increasing security in these networks. Simulation results using OPNET simulator depict that packet delivery ratio in the presence of malicious nodes, reduces notably.

  13. The Oracle a New Intelligent Cooperative Strategy of Attacks on Trust and Reputation Systems

    Directory of Open Access Journals (Sweden)

    Janiszewski Marek

    2014-06-01

    Full Text Available The paper presents a new concept of attack on trust and reputation systems. The oracle attack could violate the security provided by some of the existing reputation systems. The formal model of the attack is presented in the article on the base of the reference trust model, provided by the author. The author has proved that this type of attack could be eficient. On the other hand, a sort of measures is provided in the paper which could be implemented in the reputation systems to overcome identified vulnerabilities, unfortunately at the cost of increase of system complication. The paper also provides a definition of intelligent strategies of attacks on trust and reputation systems based on cooperation of many malicious nodes and justifies why this type of attacks is a serious threat

  14. Analysis, classification and detection methods of attacks via wireless sensor networks in SCADA systems

    OpenAIRE

    Botvinkin, Pavel Viktorovich; Kamaev, Valery Anatolevich; Nefedova, Irina Sergeevna; Finogeev, Aleksey Germanovich; Finogeev, Egor Alekseevich

    2014-01-01

    Effectiveness of information security of automated process control systems, as well as of SCADA, depends on data transmissions protection technologies applied on transport environments components. This article investigates the problem of detecting attacks on WSN (wireless sensor networks) of SCADA systems. As the result of analytical studies the authors developed the detailed classification of external attacks on sensor networks and brought the detailed description of attacking impacts on com...

  15. Detection and Modeling of Cyber Attacks with Petri Nets

    Directory of Open Access Journals (Sweden)

    Bartosz Jasiul

    2014-12-01

    Full Text Available The aim of this article is to present an approach to develop and verify a method of formal modeling of cyber threats directed at computer systems. Moreover, the goal is to prove that the method enables one to create models resembling the behavior of malware that support the detection process of selected cyber attacks and facilitate the application of countermeasures. The most common cyber threats targeting end users and terminals are caused by malicious software, called malware. The malware detection process can be performed either by matching their digital signatures or analyzing their behavioral models. As the obfuscation techniques make the malware almost undetectable, the classic signature-based anti-virus tools must be supported with behavioral analysis. The proposed approach to modeling of malware behavior is based on colored Petri nets. This article is addressed to cyber defense researchers, security architects and developers solving up-to-date problems regarding the detection and prevention of advanced persistent threats.

  16. Impact of Rushing attack on Multicast in Mobile Ad Hoc Network

    CERN Document Server

    Palanisamy, V

    2009-01-01

    A mobile ad hoc network (MANETs) is a self-organizing system of mobile nodes that communicate with each other via wireless links with no fixed infrastructure or centralized administration such as base station or access points. Nodes in a MANETs operate both as host as well as routers to forward packets for each other in a multihop fashion. For many applications in wireless networks, multicasting is an important and frequent communication service. By multicasting, since a single message can be delivered to multiple receivers simultaneously. It greatly reduces the transmission cost when sending the same packet to multiple recipients. The security issue of MANETs in group communications is even more challenging because of involvement of multiple senders and multiple receivers. At that time of multicasting, mobile ad hoc network are unprotected by the attacks of malicious nodes because of vulnerabilities of routing protocols. Some of the attacks are Rushing attack, Blackhole attack, Sybil attack, Neighbor attack ...

  17. A Comparison of Link Layer Attacks on Wireless Sensor Networks

    CERN Document Server

    Mohammadi, Shahriar; 10.5121/jgraphhoc.2011.3103

    2011-01-01

    Wireless sensor networks (WSNs) have many potential applications [1, 5] and unique challenges. They usually consist of hundreds or thousands small sensor nodes such as MICA2, which operate autonomously; conditions such as cost, invisible deployment and many application domains, lead to small size and limited resources sensors [2]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional networks security techniques are unusable on WSNs [2]; due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. So, security is a vital requirement for these networks; but we have to design a proper security mechanism that attends to WSN's constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs' link layer a...

  18. On the Measurement of Privacy as an Attacker's Estimation Error

    CERN Document Server

    Rebollo-Monedero, David; Diaz, Claudia; Forné, Jordi

    2011-01-01

    A wide variety of privacy metrics have been proposed in the literature to evaluate the level of protection offered by privacy enhancing-technologies. Most of these metrics are specific to concrete systems and adversarial models, and are difficult to generalize or translate to other contexts. Furthermore, a better understanding of the relationships between the different privacy metrics is needed to enable more grounded and systematic approach to measuring privacy, as well as to assist systems designers in selecting the most appropriate metric for a given application. In this work we propose a theoretical framework for privacy-preserving systems, endowed with a general definition of privacy in terms of the estimation error incurred by an attacker who aims to disclose the private information that the system is designed to conceal. We show that our framework permits interpreting and comparing a number of well-known metrics under a common perspective. The arguments behind these interpretations are based on fundame...

  19. Composite Dos Attack Model

    Directory of Open Access Journals (Sweden)

    Simona Ramanauskaitė

    2012-04-01

    Full Text Available Preparation for potential threats is one of the most important phases ensuring system security. It allows evaluating possible losses, changes in the attack process, the effectiveness of used countermeasures, optimal system settings, etc. In cyber-attack cases, executing real experiments can be difficult for many reasons. However, mathematical or programming models can be used instead of conducting experiments in a real environment. This work proposes a composite denial of service attack model that combines bandwidth exhaustion, filtering and memory depletion models for a more real representation of similar cyber-attacks. On the basis of the introduced model, different experiments were done. They showed the main dependencies of the influence of attacker and victim’s properties on the success probability of denial of service attack. In the future, this model can be used for the denial of service attack or countermeasure optimization.

  20. Research on recognition of ramp angle based on transducer

    Directory of Open Access Journals (Sweden)

    Wenhao GU

    2015-12-01

    Full Text Available Focusing on the recognition of ramp angle, the relationship between the signal of vehicle transducer and real ramp angle is studied. The force change of vehicle on the ramp, and the relationship between the body tilt angle and front and rear suspension scale is discussed. According to the suspension and tire deformation, error angle of the ramp angle is deduced. A mathematical model is established with Matlab/Simulink and used for simulation to generate error curve of ramp angle. The results show that the error angle increases with the increasing of the ramp angle, and the limit value can reach 6.5%, while the identification method can effectively eliminate this error, and enhance the accuracy of ramp angle recognition.

  1. On Attack-Relevant Ranking of Network Features

    Directory of Open Access Journals (Sweden)

    Adel Ammar

    2015-11-01

    Full Text Available An Intrusion Detection System (IDS is an important component of the defense-in-depth security mechanism in any computer network system. For assuring timely detection of intrusions from millions of connection records, it is important to reduce the number of connection features examined by the IDS, using feature selection or feature reduction techniques. In this scope, this paper presents the first application of a distinctive feature selection method based on neural networks to the problem of intrusion detection, in order to determine the most relevant network features, which is an important step towards constructing a lightweight anomaly-based intrusion detection system. The same procedure is used for feature selection and for attack detection, which gives more consistency to the method. We apply this method to a case study, on KDD dataset and show its advantages compared to some existing feature selection approaches. We then measure its dependence to the network architecture and the learning database.

  2. Attacks of Asthma due to Chlorinized Water: Case Report

    Directory of Open Access Journals (Sweden)

    Murat Eyup Berdan

    2008-02-01

    Full Text Available The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been reported. But, attacks of asthma which is related to chlorinized water is rare. Chlorine, a strong oxidizing agent, is an important toxic gas that the swimmer can breath during swimming and a worker can exposed to chlorine while he or she was using water with chlorine at home. We describe a persistent increase in nonspecific bronchial hyperresponsiveness following chronic exposure to strong respiratory irritant with chlorinized water in two subjects with no past history of asthma or atopy. We conclude that airway hyperresponsiveness can develop or increase after chronic inhalation of high concentrations of irritants such as chlorinized water an indoor irritant factor and that these changes may be prolonged. [TAF Prev Med Bull. 2008; 7(1: 87-90

  3. Attacks of Asthma due to Chlorinized Water: Case Report

    Directory of Open Access Journals (Sweden)

    Murat Eyup Berdan

    2008-02-01

    Full Text Available The presence of a high prevalence of bronchial hyperresponsiveness and asthma-like symptoms in swimmers has been reported. But, attacks of asthma which is related to chlorinized water is rare. Chlorine, a strong oxidizing agent, is an important toxic gas that the swimmer can breath during swimming and a worker can exposed to chlorine while he or she was using water with chlorine at home. We describe a persistent increase in nonspecific bronchial hyperresponsiveness following chronic exposure to strong respiratory irritant with chlorinized water in two subjects with no past history of asthma or atopy. We conclude that airway hyperresponsiveness can develop or increase after chronic inhalation of high concentrations of irritants such as chlorinized water an indoor irritant factor and that these changes may be prolonged. [TAF Prev Med Bull 2008; 7(1.000: 87-90

  4. Advances in the Management of Transient Ischaemic Attack and Stroke

    Directory of Open Access Journals (Sweden)

    Mayra J Montalvo

    2016-07-01

    Full Text Available Among many important advances in the management of transient ischaemic attack (TIA and stroke are: the updated definition of TIA; risk stratification scores for TIA; the urgent diagnostic and treatment process for TIA; thrombectomy treatment for large vessel occlusive ischaemic stroke; cryptogenic stroke evaluation and treatment, including long-term monitoring for paroxysmal atrial fibrillation; and strategies to improve outcomes for patients including mirror therapy for neglect and timing of mobilisation after stroke. Future research will focus on: antiplatelet strategies after TIA; selecting patients for treatment with recanalisation therapies in an extended time window; uncovering the cause of strokes previously defined as cryptogenic; and better defining the optimal timing and dose of mobilisation after stroke.

  5. A Study and Detection of TCP SYN Flood Attacks with IP spoofing and its Mitigations

    Directory of Open Access Journals (Sweden)

    Deepak Singh Rana

    2012-07-01

    Full Text Available Flooding attacks are major threats on TCP/IP protocol suite these days; Maximum attacks are launched through TCP and exploit the resources and bandwidth of the machine. Flooding attacks are DDOS (Distributed denial of service attacks and utilize the weakness of the network protocols. SYN flood exploits the 3-way handshaking of the TCP by sending many SYN request with IP spoofing technique to victim host and exhaust the backlog queue resource of the TCP and deny legitimate user to connect. Capturing the packet flow is very important to detecting the DOS attack. This paper present how the TCP SYN flood takes place and show the number of packets received by the victim server under the attack.

  6. Cerebral blood flow velocities are reduced during attacks of unilateral migraine without aura

    DEFF Research Database (Denmark)

    Thomsen, L L; Iversen, Helle Klingenberg; Olesen, J

    1995-01-01

    aura in 25 patients. Blood velocity in the middle cerebral artery was lower on the headache side (59 cm/s) than on the non-headache side (65 cm/s) during the migraine attack. No such difference was found outside of attack (65 cm/s both sides). The difference (headache side minus non-headache side......) was on average -6.1 cm/s during attack compared to -0.4 cm/s outside of attack (p = 0.01). Assuming that rCBF is unchanged during attacks of migraine without aura, our results suggest a 9% increase in middle cerebral artery lumen (cross-sectional area) on the affected side during unilateral attacks of migraine...... without aura. The findings, however, do not necessarily mean that arterial dilatation is the only or even the most significant cause of pain....

  7. Evaluation of Seizure Attacks in Patients with Cerebrovascular Accident

    Directory of Open Access Journals (Sweden)

    Ebrahim Koochaki

    2013-04-01

    Full Text Available Background: The most common reason for seizure in elderly duration is the stroke. This study was conducted aiming to assess the frequency of seizure attack occurrence in those patients. Materials and Methods: This investigation was carried out through a cross-sectional method for one year on 330 patients admitted to the neurology ward as diagnosed with stroke. The required data was collected through the researcher-made questionnaire from the patients suffering from stoke which was diagnosed based on clinical findings, CT-Scan and MRI as required. Results: Among 330 patient suffering from stroke (162 men and 168 women, 48 cases (14.5% were suffering from seizure. Six percent of the patients had early seizure and another 8.5% had late seizure. Among 162 men suffering from the stroke, 32 ones were without seizures and 30 men were suffering the seizure. A number of 150 women out of total 168 ones suffering from the stroke, had no seizure and 18 others had seizures; frequency of seizure occurrence was more in male samples (p=0.044. In the people under 60 year, there were mostly early types of seizure (45% and in the age range above 60 year, it was mostly late type (89.3%. A 68.5% of the patients suffering from the seizure had experienced ischemic stroke. However, the frequency of seizure occurrence in the patients with hemorrhagic stroke was statistically greater (p=0.003. Conclusion: This examination showed that occurrence of seizure attacks in the people with stroke is 14.5% and it is seen more in the hemorrhagic strokes than ischemic ones. The frontoparietal area is the most common location involved and tonic clonic was the most common seizure in the patients suffering from it who have experienced the stroke

  8. Relation of EEG and computerized tomography in transient ischaemic attacks

    International Nuclear Information System (INIS)

    80 patients with transient ischaemic attack (TIA) were examined via computer tomogram (CT) and electronencephalogram (EEG). 53 patients were found to have a normal CT and 32 a normal EEG. In the patients with pathological CT findings (27) a significantly lower number of normal EEG's (22) was seen. Further subdivision of the 27 pathological CT findings revealed 12 patients with hypodense areas (infarctions) and 15 patients with an atrophy only. A normal EEG was significantly rarer in patients with a hypodense lesion (2) and in those with atrophy (3), focal EEG changes being significantly more frequent. Hence EEG findings facilitate the aetiological linking of an atrophy to an ischaemic stroke, especially when EEG follow-up examinations are included in the diagnostic procedure. (orig.)

  9. Influence of self-compacting concrete composition on sulfuric acid attack

    OpenAIRE

    Feys, Dimitri; Liu, Zanqun; Heirman, Gert; De Schutter, Geert; Boel, Veerle; Desmet, Bram; Vantomme, John; Cizer, Özlem; Vandewalle, Lucie; Gemert, Dionys van

    2009-01-01

    Sulfuric acid attack on concrete has been reported for over a century. Many scientific papers deal with the issue of concrete damage due to sulfate and sulfuric attack. The introduction of self-compacting concrete introduces new questions related to the behaviour of powder-rich mixtures in a sulfate environment. This paper describes a simple testing method to investigate the influence of the concrete composition on the sulfuric acid attack. Concrete samples have been submerged in a sulfate...

  10. Calibration of 5-hole Probe for Flow Angles from Advanced Technologies Testing Aircraft System Flight Data

    Directory of Open Access Journals (Sweden)

    Y. Parameswaran

    2004-04-01

    Full Text Available This paper describes the investigations carried out to calibrate the 5-hole probe for flow angles from advanced technologies testing aircraft system flight data. The flight tests were carriedout with gear up and at nominal mid-centre of gravity location for two landing flap positions, Of= IN and 14°. Dynamic manoeuvres were executed to excite the short period and Dutch roll mode of the aircraft. In addition, pull up, push down and steady sideslip manoeuvres were also carried out. The data compatibility check on the recorded flight data has been carried out using maximum likelihood output error algorithm to estimate the bias, scale factor, and time delay in the pressure measurements from the 5-hole probe mounted on a noseboom in front of aircraft nose . Through a way of kinematic consistency checking, flight-validated scale factors, biases, and time delays are determined for the differential pressure measurements for both angle of attack and angle of sideslip. Also, the dynamic pressure measurement is found to have time delays. Based on the earlier investigations, it is once again confirmed that the measurements of attitude angles, obtained from the inertial platform, clearly indicate time delays referred to the other signals like linear accelerations and angular rates which are measured with the dedicated flight instrumentation package.The identified time delays in attitude angles agreed well with the inertial platform specifications. The estimates of sensitivity coefficients and scale factors from the flight data analysis correlates reasonably well with the manufacturer Rosemount calibration curves for the tested Mach range 0.23-0.53 . The flight data analysis at Mach number of about 0.59 indicateMach dependency for the angle of attack.

  11. Low serum concentrations of vitamin B6 and iron are related to panic attack and hyperventilation attack.

    Science.gov (United States)

    Mikawa, Yasuhito; Mizobuchi, Satoshi; Egi, Moritoki; Morita, Kiyoshi

    2013-01-01

    Patients undergoing a panic attack (PA) or a hyperventilation attack (HVA) are sometimes admitted to emergency departments (EDs). Reduced serotonin level is known as one of the causes of PA and HVA. Serotonin is synthesized from tryptophan. For the synthesis of serotonin, vitamin B6 (Vit B6) and iron play important roles as cofactors. To clarify the pathophysiology of PA and HVA, we investigated the serum levels of vitamins B2, B6, and B12 and iron in patients with PA or HVA attending an ED. We measured each parameter in 21 PA or HVA patients and compared the values with those from 20 volunteers. We found that both Vit B6 and iron levels were significantly lower in the PA/HVA group than in the volunteer group. There was no significant difference in the serum levels of vitamins B2 or B12. These results suggest that low serum concentrations of Vit B6 and iron are involved in PA and HVA. Further studies are needed to clarify the mechanisms involved in such differences. PMID:23603926

  12. Low Serum Concentrations of Vitamin B6 and Iron Are Related to Panic Attack and Hyperventilation Attack

    Directory of Open Access Journals (Sweden)

    Morita,Kiyoshi

    2013-04-01

    Full Text Available Patients undergoing a panic attack (PA or a hyperventilation attack (HVA are sometimes admitted to emergency departments (EDs. Reduced serotonin level is known as one of the causes of PA and HVA. Serotonin is synthesized from tryptophan. For the synthesis of serotonin, vitamin B6 (Vit B6 and iron play important roles as cofactors. To clarify the pathophysiology of PA and HVA, we investigated the serum levels of vitamins B2, B6, and B12 and iron in patients with PA or HVA attending an ED. We measured each parameter in 21 PA or HVA patients and compared the values with those from 20 volunteers. We found that both Vit B6 and iron levels were significantly lower in the PA/HVA group than in the volunteer group. There was no significant difference in the serum levels of vitamins B2 or B12. These results suggest that low serum concentrations of Vit B6 and iron are involved in PA and HVA. Further studies are needed to clarify the mechanisms involved in such differences.

  13. Development of mental health first aid guidelines for panic attacks: a Delphi study

    OpenAIRE

    Jorm Anthony F; Kelly Claire M; Kitchener Betty A

    2009-01-01

    Abstract Background Panic attacks are common, and while they are not life-threatening events, they can lead to the development of panic disorder and agoraphobia. Appropriate help at the time that a panic attack occurs may decrease the fear associated with the attack and reduce the risk of developing an anxiety disorder. However, few people have the knowledge and skills required to assist. Simple first aid guidelines may help members of the public to offer help to people who experience panic a...

  14. Contact angles of liquid metals on quasicrystals

    International Nuclear Information System (INIS)

    Wetting with μm-sized Pb droplets on thin polycrystalline films of decagonal Al13Co4 is reported. The films were prepared under high vacuum conditions in order to have Pb droplets lying on a clean surface. The method used is sequential deposition and annealing of specific stackings of Al and Co layers of nanometric thicknesses. A 300 nm thick Pb slab was then deposited on top of the films and dewetting experiments were followed in situ in a scanning Auger microprobe. The contact angle between the Pb droplet and the surface of the film is measured to be 49 deg. ± 7 deg. Further investigation performed by cross section transmission electron microscopy allows us to better characterize the interface. Taking into account the rugosity of the film, it is concluded that there is partial wetting of the film, which corresponds to a smaller contact angle. The comparison with other results obtained either with pure metals or with a cubic AlCo compound leads to the conclusion that the wetting behaviour of Pb on the surface of a decagonal compound is close to that of a metal with a high melting point and not significantly different from that of a crystalline compound with a small unit cell

  15. Incidence and impact of dog attacks on guide dogs in the UK: an update.

    Science.gov (United States)

    Moxon, R; Whiteside, H; England, G C W

    2016-04-01

    Data on dog attacks on Guide Dogs' stock were reviewed to investigate the characteristics of the attacks. An average of 11.2 attacks occurred each month. Nearly all of the attacks occurred in public areas, 68.4 per cent of victim dogs were qualified guide dogs and 55.5 per cent of victim dogs were working in harness when they were attacked. Guide Dogs' stock were injured in 43.2 per cent of attacks and veterinary costs for attacks were estimated at £34,514.30. Over 40 per cent of qualified guide dogs' working ability was affected and >20 per cent of qualified guide dogs required some time off from working after a dog attack. Twenty dogs were permanently withdrawn from the Guide Dogs' programme as a result of dog attacks, 13 of which were qualified and working with guide dog owners at the time of the withdrawal; this resulted in a financial cost of >£600,000 to the charity. More importantly perhaps, temporary and permanent withdrawals have a significant impact upon the mobility and independence of guide dog owners and in many cases significantly impacted their emotional well-being. PMID:26924739

  16. Incidence and impact of dog attacks on guide dogs in the UK: an update.

    Science.gov (United States)

    Moxon, R; Whiteside, H; England, G C W

    2016-04-01

    Data on dog attacks on Guide Dogs' stock were reviewed to investigate the characteristics of the attacks. An average of 11.2 attacks occurred each month. Nearly all of the attacks occurred in public areas, 68.4 per cent of victim dogs were qualified guide dogs and 55.5 per cent of victim dogs were working in harness when they were attacked. Guide Dogs' stock were injured in 43.2 per cent of attacks and veterinary costs for attacks were estimated at £34,514.30. Over 40 per cent of qualified guide dogs' working ability was affected and >20 per cent of qualified guide dogs required some time off from working after a dog attack. Twenty dogs were permanently withdrawn from the Guide Dogs' programme as a result of dog attacks, 13 of which were qualified and working with guide dog owners at the time of the withdrawal; this resulted in a financial cost of >£600,000 to the charity. More importantly perhaps, temporary and permanent withdrawals have a significant impact upon the mobility and independence of guide dog owners and in many cases significantly impacted their emotional well-being.

  17. Adaptive Consensus of Distributed Varying Scale Wireless Sensor Networks under Tolerable Jamming Attacks

    Directory of Open Access Journals (Sweden)

    Jinping Mou

    2013-01-01

    Full Text Available Consensus problem is investigated for a varying scale wireless sensor network (VSWSN under tolerable jamming attacks, where the scale of the network is increasing or decreasing due to the newly joined nodes or the removed nodes, respectively; the tolerable jamming attack means that the attack strength is limited. It supposes that during the communications, all nodes may encounter with the tolerable jamming attacks; when the attack power is larger than the given value, the attacked nodes fall asleep, or otherwise the nodes are awakened. Under the sleep method, based on the Lyapunov method, it shows that if the communicating graph is the global limited intersectional connection (GLI connection and the system has the enough dwell time in the intersectional topology, then under the designed consensus protocol, all nodes achieve the global average consensus.

  18. Seven Deadliest Network Attacks

    Energy Technology Data Exchange (ETDEWEB)

    Prowell, Stacy J [ORNL; Borkin, Michael [None; Kraus, Robert [Solutionary, Inc.

    2010-05-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting networks? Then you need "Seven Deadliest Network Attacks". This book pinpoints the most dangerous hacks and exploits specific to networks, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: Denial of Service; War Dialing; Penetration 'Testing'; Protocol Tunneling; Spanning Tree Attacks; Man-in-the-Middle; and, Password Replay. Knowledge is power, find out about the most dominant attacks currently waging war on computers and networks globally. Discover the best ways to defend against these vicious attacks; step-by-step instruction shows you how. Institute countermeasures, don't be caught defenseless again, learn techniques to make your computer and network impenetrable.

  19. A simple coherent attack and practical security of differential phase shift quantum cryptography

    Science.gov (United States)

    Kronberg, D. A.

    2014-02-01

    The differential phase shift quantum key distribution protocol reveals good security against such powerful attacks as unambiguous state discrimination and beam splitting attacks. Its complete security analysis is complex due to high dimensions of the supposed spaces and density operators. In this paper, we consider a particular and conceptually simple coherent attack, available in practical implementations. The main condition for this attack is the length of used coherent state tuples of order 8-12. We show that under this condition, no high level of practical distance between legitimate users can be achieved.

  20. Multidimensional zero-correlation attacks on lightweight block cipher HIGHT: Improved cryptanalysis of an ISO standard

    DEFF Research Database (Denmark)

    Wen, Long; Wang, Meiqin; Bogdanov, Andrey;

    2014-01-01

    results on HIGHT, its security evaluation against the recent zero-correlation linear attacks is still lacking. At the same time, the Feistel-type structure of HIGHT suggests that it might be susceptible to this type of cryptanalysis. In this paper, we aim to bridge this gap. We identify zero......-correlation linear approximations over 16 rounds of HIGHT. Based upon those, we attack 27-round HIGHT (round 4 to round 30) with improved time complexity and practical memory requirements. This attack of ours is the best result on HIGHT to date in the classical single-key setting. We also provide the first attack...

  1. Multi-Layer Approach for the Detection of Selective Forwarding Attacks.

    Science.gov (United States)

    Alajmi, Naser; Elleithy, Khaled

    2015-01-01

    Security breaches are a major threat in wireless sensor networks (WSNs). WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD). The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable. PMID:26610499

  2. Multi-Layer Approach for the Detection of Selective Forwarding Attacks

    Directory of Open Access Journals (Sweden)

    Naser Alajmi

    2015-11-01

    Full Text Available Security breaches are a major threat in wireless sensor networks (WSNs. WSNs are increasingly used due to their broad range of important applications in both military and civilian domains. WSNs are prone to several types of security attacks. Sensor nodes have limited capacities and are often deployed in dangerous locations; therefore, they are vulnerable to different types of attacks, including wormhole, sinkhole, and selective forwarding attacks. Security attacks are classified as data traffic and routing attacks. These security attacks could affect the most significant applications of WSNs, namely, military surveillance, traffic monitoring, and healthcare. Therefore, there are different approaches to detecting security attacks on the network layer in WSNs. Reliability, energy efficiency, and scalability are strong constraints on sensor nodes that affect the security of WSNs. Because sensor nodes have limited capabilities in most of these areas, selective forwarding attacks cannot be easily detected in networks. In this paper, we propose an approach to selective forwarding detection (SFD. The approach has three layers: MAC pool IDs, rule-based processing, and anomaly detection. It maintains the safety of data transmission between a source node and base station while detecting selective forwarding attacks. Furthermore, the approach is reliable, energy efficient, and scalable.

  3. Stress-related changes in toddlers and their mothers following the attack of September 11.

    Science.gov (United States)

    Conway, Anne; McDonough, Susan C; MacKenzie, Michael J; Follett, Chantal; Sameroff, Arnold

    2013-10-01

    Unlike other forms of disaster, terrorism is not confined to a particular place or time, and recent evidence indicates that the 9/11 terrorist attack was a significant macrolevel stressor affecting the health and mental health of United States citizens. No studies, however, have reported symptoms in toddlers and their mothers both before and after the attacks. To address this gap, we examined the effects of the 9/11 terrorist attacks on mothers and their 33-month-old toddlers. The attacks occurred during data collection at 33 months of a longitudinal study. Thirty-three-month-old toddlers and mothers who were assessed after the attacks were compared with those assessed before the attacks. When changes were examined from a previous wave of data collected at 15 months, those in the after-attack group showed poorer health, lower child acceptance, and marginally more anxiety, and their toddlers cried more and slept less, whereas the before-attack group showed no changes. Our findings contribute to research documenting widespread effects of the 9/11 terrorist attack on stress-related symptoms and suggest that greater attention must be placed on the needs of our youngest citizens and their caregivers. PMID:24164525

  4. On resilience studies of system detection and recovery techniques against stealthy insider attacks

    Science.gov (United States)

    Wei, Sixiao; Zhang, Hanlin; Chen, Genshe; Shen, Dan; Yu, Wei; Pham, Khanh D.; Blasch, Erik P.; Cruz, Jose B.

    2016-05-01

    With the explosive growth of network technologies, insider attacks have become a major concern to business operations that largely rely on computer networks. To better detect insider attacks that marginally manipulate network traffic over time, and to recover the system from attacks, in this paper we implement a temporal-based detection scheme using the sequential hypothesis testing technique. Two hypothetical states are considered: the null hypothesis that the collected information is from benign historical traffic and the alternative hypothesis that the network is under attack. The objective of such a detection scheme is to recognize the change within the shortest time by comparing the two defined hypotheses. In addition, once the attack is detected, a server migration-based system recovery scheme can be triggered to recover the system to the state prior to the attack. To understand mitigation of insider attacks, a multi-functional web display of the detection analysis was developed for real-time analytic. Experiments using real-world traffic traces evaluate the effectiveness of Detection System and Recovery (DeSyAR) scheme. The evaluation data validates the detection scheme based on sequential hypothesis testing and the server migration-based system recovery scheme can perform well in effectively detecting insider attacks and recovering the system under attack.

  5. Therapeutic attack of hypoxic cells of solid tumors: presidential address.

    Science.gov (United States)

    Sartorelli, A C

    1988-02-15

    Hypoxic cells of solid tumors are relatively resistant to therapeutic assault. Studies have demonstrated that oxygen-deficient tumor cells exist in an environment conducive to reductive reactions making hypoxic cells particularly sensitive to bioreductive alkylating agents. Mitomycin C, the prototype bioreductive alkylating agent available for clinical use, is capable of preferentially killing oxygen-deficient cells both in vitro and in vivo. This phenomenon is at least in part the result of differences in the uptake and metabolism of mitomycin C by hypoxic and oxygenated tumor cells, with the ultimate critical lesion being the cross-linking of DNA by the mitomycin antibiotic. The combination of mitomycin C with X-irradiation, to attack hypoxic and oxygenated tumor cell populations, respectively, has led to enhanced antitumor effects in mice bearing solid tumor implants and in patients with cancer of the head and neck. More efficacious kill of hypoxic tumor cells may be possible by the use of dicoumarol in combination with mitomycin or by the use of the related antibiotic porfiromycin. The findings support the use of an agent with specificity for hypoxic tumor cells in potentially curative regimens for solid tumors. PMID:3123053

  6. Effective Authentication Technique for Distributed Denial of Service Attacks in Wireless Local Area Networks

    Directory of Open Access Journals (Sweden)

    S. Sathiyabama

    2012-01-01

    Full Text Available Problem statement: In 802.11-based Wireless LAN (WLAN, there is an mproved risk of security attacks. To defeat concealed attacks, there is a necessity to authenticate both access points and wireless stations. Approach: We propose a defensive technique for DDoS attack in WLAN. This authentication technique includes an Authentication Server (AS in addition to the Wireless Station (WS and Access Point (AP. Results: The authentication server holds both normal and attacker databases. The attacker database can be constructed from the outcome of fuzzy decision making. After WS and AP registers itself with AS, WS sends authentication request message to AS through the nearest AP. Before granting the session key for the WS, the AS checks the occurrence of WS in the attacker database. If it is found to be an attacker, AS denies the session key for the WS, there by isolating the WS from further communications. In order to prevent the authentication request flooding attacks, traffic pattern filtering rule is implemented. Conclusion/Recommendations: By simulation results, we show that the proposed technique is more efficient defensive mechanism against DDoS attack.

  7. Resilience of gated avalanche photodiodes against bright illumination attacks in quantum cryptography

    CERN Document Server

    Yuan, Z L; Shields, A J; 10.1063/1.3597221

    2011-01-01

    Semiconductor avalanche photodiodes (APDs) are commonly used for single photon detection in quantum key distribution. Recently, many attacks using bright illumination have been proposed to manipulate gated InGaAs APDs. In order to devise effective counter-measures, careful analysis of these attacks must be carried out to distinguish between incorrect operation and genuine loopholes. Here, we show that correctly-operated, gated APDs are immune to continuous-wave illumination attacks, while monitoring the photocurrent for anomalously high values is a straightforward counter-measure against attacks using temporally tailored light.

  8. Mechanism of hypothalamic paraventricular nucleus in regulating asthmatic attack

    Institute of Scientific and Technical Information of China (English)

    Jia Liu; Rong Dong; Jian Xiao; Nina Liu

    2006-01-01

    BACKGROUD: It has been confirmed that c-fos expession increased markedly in hypothalamic paraventricular nucleus(PVN)during asthmatic attack in rats,and PVN has extensive physiological functions,involving in the regulation of respiratory system,etc.OBJECTIVE: To observe the alteration of electroencephalogram(EEG)and power spectra in PVN during the asthmatic attack,and the alteraiton of lung function and diaphragmatic muscle discharge after bilateral PVN lesion in asthmatic rats.DESIGN:A randomized control study.SETTING: Laboratory of Physiology and Pharmacology,School of Basic Medical Sciences,Southeast University.MATERIALS: Forty-eight male adult SD rats of 260-300g were used.The rats were randomly divided into 6 groups(n=8):control group,asthma group,electrolytic lesion of PVN group,KA-induced lesion of PVN group,sham electrolytic lesion of PVN group and sham kainic acid(KA)-induced lesion of PVN group.KA,chicken ovalbumin and aluminum hydroxide were purchased from American Sigma Company.Bordetella pertrssis vaccine (Institute of Biological Products of Shanghai);stereotaxic apparartus (Jianwan Ⅱ,China);Iesion-producing device (YC-2 programmable stimulato,Chengdu Iustrument Company);MD2000 signal processing system(Nanjing Medical School); data acquisition system (RM6240B,Chengdu Instrument Company).METHODS:The experiments were carried out in the Laboratory of Physiology and Pharmacology,School of Basic Medical Sciences,Southeast University from January to August in 2006.①Rats except for control group were sensitized with an intraperitoneal injection of 100 mg chicken ovalbumin and 100 mg aluminum hydroxide and Bordetella pertussis vaccine containing 5×109 heat-killed in 1 mL of sterile saline.From the fifteenth to seventeenth days rats received three times aerosolized ovalbumin challenge. In rats of the control group and asthma group three steel electrodes were placed into the left PVN(AP-1.8 mm,LR 0.4 mm,OH-7.9 mm).parietal cortex and subcutaneous tissue in

  9. An Assessment of User Response to Phishing Attacks: The Effects of Fear and Self-Confidence

    Science.gov (United States)

    House, Deanna

    2013-01-01

    Phishing attacks have threatened the security of both home users and organizations in recent years. Individuals of varying levels of computer proficiency are potential targets for a phishing attack; all that is needed is an email address and Internet access. Phishing uses social engineering to fraudulently obtain information that is confidential…

  10. Characterization of collective Gaussian attacks and security of coherent-state quantum cryptography.

    Science.gov (United States)

    Pirandola, Stefano; Braunstein, Samuel L; Lloyd, Seth

    2008-11-14

    We provide a simple description of the most general collective Gaussian attack in continuous-variable quantum cryptography. In the scenario of such general attacks, we analyze the asymptotic secret-key rates which are achievable with coherent states, joint measurements of the quadratures and one-way classical communication.

  11. Help-Seeking Behaviours of Adolescents in Relation to Terrorist Attacks: The Perceptions of Israeli Parents

    Science.gov (United States)

    Tatar, Moshe; Amram, Sima; Kelman, Talia

    2011-01-01

    Exposure to terrorism poses a challenge for children and adolescents as well as parents. For many years, Israeli citizens have been exposed to ongoing terrorist attacks. The present article is aimed at revealing the reactions of Israeli parents when facing terrorist attacks and their perceptions regarding the help-seeking behaviours of their…

  12. Distribution of angles in hyperbolic lattices

    DEFF Research Database (Denmark)

    Risager, Morten Skarsholm; Truelsen, Jimi Lee

    2010-01-01

    We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result from the study by Boca.......We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result from the study by Boca....

  13. Distribution of Angles in Hyperbolic Lattices

    DEFF Research Database (Denmark)

    S. Risager, Morten; L. Truelsen, Jimi

    2008-01-01

    We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result due to F. P. Boca.......We prove an effective equidistribution result about angles in a hyperbolic lattice. We use this to generalize a result due to F. P. Boca....

  14. Effect of hydrogen attack on acoustic emission behavior of low carbon steel

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to investigate the effect of hydrogen attack degree on acoustic emission (AE) behavior of low carbon steel during tensiling, specimens made of low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and 500℃ for 240, 480 and 720 h respectively. Experimental results show that with increase of the hydrogen attack degree, the totally AE activity decreases during tensiling. In addition, the count of AE signals with high amplitude for the specimens with hydrogen attack keeps a constant which is less than that without hydrogen attack. It is concluded that AE signals originate in the specimens with hydrogen attack from intergranular fracture induced by methane blisterings or/and microcracks on grain boundaries.

  15. Analysis of AODV and DSR in Presence of Wormhole Attack in Mobile Ad-hoc Network

    Directory of Open Access Journals (Sweden)

    VIVEK SHARMA,

    2010-11-01

    Full Text Available An ad hoc network is a collection of mobile nodes that dynamically form a temporary network. It operates without the use of existing infrastructure. As mobile ad hoc network applications are deployed, security emerges as a central requirement. In this paper, we introduce the wormhole attack, a severe security attack in ad hocnetworks that is particularly challenging to defend against. The wormhole attack is possible even if the attacker has not compromised any hosts and even if all communication provides authenticity and confidentiality. In the wormhole attack, an attacker records packets (or bits at one location in the network, tunnels them (possiblyselectively to another location, and retransmits them there into the network. The wormhole attack can form a serious threat in wireless networks, especially against many ad hoc network routing protocols and locationbased wireless security systems. This paper analyses the performance of AODV and DSR routing protocols with and without wormhole attack. This would be a great help for the people conducting research on real world problems in MANET security.

  16. Prediction of first episode of panic attack among white-collar workers.

    Science.gov (United States)

    Watanabe, Akira; Nakao, Kazuhisa; Tokuyama, Madoka; Takeda, Masatoshi

    2005-04-01

    The purpose of the present study was to elucidate a longitudinal matrix of the etiology for first-episode panic attack among white-collar workers. A path model was designed for this purpose. A 5-year, open-cohort study was carried out in a Japanese company. To evaluate the risk factors associated with the onset of a first episode of panic attack, the odds ratios of a new episode of panic attack were calculated by logistic regression. The path model contained five predictor variables: gender difference, overprotection, neuroticism, lifetime history of major depression, and recent stressful life events. The logistic regression analysis indicated that a person with a lifetime history of major depression and recent stressful life events had a fivefold and a threefold higher risk of panic attacks at follow up, respectively. The path model for the prediction of a first episode of panic attack fitted the data well. However, this model presented low accountability for the variance in the ultimate dependent variables, the first episode of panic attack. Three predictors (neuroticism, lifetime history of major depression, and recent stressful life events) had a direct effect on the risk for a first episode of panic attack, whereas gender difference and overprotection had no direct effect. The present model could not fully predict first episodes of panic attack in white-collar workers. To make a path model for the prediction of the first episode of panic attack, other strong predictor variables, which were not surveyed in the present study, are needed. It is suggested that genetic variables are among the other strong predictor variables. A new path model containing genetic variables (e.g. family history etc.) will be needed to predict the first episode of panic attack. PMID:15823155

  17. High Order Differential Attack and Trace Attack to Block Ciphers

    Institute of Scientific and Technical Information of China (English)

    HU Yupu; CHEN Kai; Xiao Guozhen

    2001-01-01

    In this paper, we prove a high or-der differential property of power function, then giverespectively high order differential attack and traceattack to block ciphers. These attacks depend onlyon block cipher's algebraic shape on GF(2n) and haveno relation with its designing structure. The condi-tions are given for both effective attacks and strengthagainst attacks.

  18. The Role of Initial Attack and Performer Expertise on Instrument Identification

    Science.gov (United States)

    Cassidy, Jane W.; Schlegel, Amanda L.

    2016-01-01

    The purpose of this study was to examine the role initial attack and expertise play in the identification of instrumental tones. A stimulus CD was made of 32 excerpts of instrumental tones. Sixteen possible combinations of the variables of initial attack (present or absent), expertise (beginner versus professional), and timbre (flute, clarinet,…

  19. Attack Coverage in High-Level Men’s Volleyball: Organization on the Edge of Chaos?

    Directory of Open Access Journals (Sweden)

    Laporta Lorenzo

    2015-09-01

    Full Text Available Change is pervasive, but emerging patterns are occasionally detectable through analysis of systemic behaviors. Match analysis uses these patterns in order to reduce the degree of improvisation and to optimize the training process. However, it is possible that certain game phases elude systematic patterning. In this vein, our aim was to analyze the case of attack coverage in men’s volleyball, as we suspected it would elude systematic patterning and has received negligible attention in scientific research. We analyzed the occurrence of attack coverage in 4544 plays of the 2011 Volleyball World League. A Chi-square test with residual adjusted values was applied to explore significant associations between variables. A Monte Carlo correction was applied, as some cells had n<5. Effect sizes were determined using Cramer’s V. Overall, attack coverage occurred in 3.89% of ball possessions, and 23 distinct structures emerged. These structures lacked significant associations with the game complex, setting zone, and effect of attack coverage. Conversely, attack coverage structures showed significant associations with the attack zone and tempo, with very strong effect sizes (V=0.472 and V=0.521, respectively. As certain attack zones are deeply associated with attack tempo, it is apparent that quicker attack plays affect attack coverage structuring, promoting the formation of less complex structures. Ultimately, attack coverage structures seem to depend on momentary constraints, thereby rendering rigid systematization impracticable. Still, we contended that a principle-based approach might be suitable. This invites researchers to rethink how to interpret game regularities.

  20. Computer simulation of dislocation core structure of metastable left angle 111 right angle dislocations in NiAl

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Z.Y. (Dept. of Materials Science and Engineering, Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)); Vailhe, C. (Dept. of Materials Science and Engineering, Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)); Farkas, D. (Dept. of Materials Science and Engineering, Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1993-10-01

    The atomistic structure of dislocation cores of left angle 111 right angle dislocations in NiAl was simulated using embedded atom method potentials and molecular statics computer simulation. In agreement with previous simulation work and experimental observations, the complete left angle 111 right angle dislocation is stable with respect to the two superpartials of 1/2 left angle 111 right angle separated by an antiphase boundary. The structure of the latter configuration, though metastable, is of interest in the search for ways of improving ductility in this material. The structure of the complete dislocation and that of the metastable superpartials was studied using atomistic computer simulation. An improved visualization method was used for the representation of the resulting structures. The structure of the partials is different from that typical of 1/2 left angle 111 right angle dislocations in b.c.c. materials and that reported previously for the B2 structure using model pair potentials. (orig.)

  1. Booters - an analysis of DDoS-as-a-Service attacks

    NARCIS (Netherlands)

    Santanna, José Jair; Rijswijk-Deij, van Roland; Sperotto, Anna; Wierbosch, Mark; Zambenedetti Granville, Lisandro; Pras, Aiko; Badonnel, Remi; Xiao, Jin; Ata, Shingo; De Turck, Filip; Groza, Voicy; Santos, dos Carlos Raniery P.

    2015-01-01

    In 2012, the Dutch National Research and Education Network, SURFnet, observed a multitude of Distributed Denial of Service (DDoS) attacks against educational institutions. These attacks were effective enough to cause the online exams of hundreds of students to be cancelled. Surprisingly, these attac

  2. Liquid Missile Fuels as Means of Chemical Terrorist Attack

    International Nuclear Information System (INIS)

    Modern world is faced with numerous terrorist attacks whose goals, methods and means of the conduct are various. It seems that we have entered the era when terrorism, one's own little terrorism, is the easiest and the most painless way of achieving a goal. That is why that such a situation has contributed to the necessity for strengthening individual and collective protection and safety, import and export control, control of the production and illegal sale of the potential means for delivering terrorist act. It has also contributed to the necessity for devising means of the delivery. For more than 10 years, a series of congresses on CB MTS Industry has pointed at chemicals and chemical industry as potential means and targets of terrorism. The specialization and experience of different authors in the field of the missile technology and missile fuels, especially those of Eastern origin, and the threat that was the reality of the war conflicts in 1990s was the reason for making a scientific and expert analysis of the liquid missile fuels as means of terrorism. There are not many experts in the field of NBC protection who are familiar with the toxicity and reaction of liquid missile fuels still lying discarded and unprotected in abandoned barracks all over Europe and Asia. The purpose of this paper is to draw public attention to possible different abuses of liquid missile fuels for a terrorist purpose, as well as to possible consequences and prevention measures against such abuses. (author)

  3. A Review of Malicious Attack in Mobile Ad-Hoc Network Based On Power Constraints

    Directory of Open Access Journals (Sweden)

    Sanjay Yadav

    2016-06-01

    Full Text Available The minimization of power in wireless sensor network is big issue. If the process of energy constraints is optimized increase the reliability and security of mobile ADHOC network. The management of ADHOC network is great challenge due to dynamic infrastructure and mobility of node. Due to mobility of node routing path of network and security of communication suffered. In the process of node mobility and path discovery of routing protocol take huge amount of power and decrease the life of network. For the improvement of power and secured communication various protocol are designed but all are limitation in terms of group communication in ADHOC network. A security constraint in mobile ADHOC network is very critical task. Some critical security issue such as black hole attack, wormhole attack, sinkhole attack, prevention and detection of attack is major challenge. For the detection of wormhole attack various authors used various technique such as clock synchronization, threshold based technique, nearest neighbor node selection method.

  4. Assassination in the United States: an operational study of recent assassins, attackers, and near-lethal approachers.

    Science.gov (United States)

    Fein, R A; Vossekuil, B

    1999-03-01

    This study is the first operational exploration of the thinking and behavior of all 83 persons known to have attacked, or approached to attack, a prominent public official or public figure in the United States since 1949. In addition to data about each attack or near-attack and each subject's demographic and background characteristics, information was gathered about each subject's ideas and actions in the days and weeks before their attacks or near-lethal approaches. Questions were examined about each subject's movement from the idea of attack to actual attack, motives, selection of targets, planning, communication of threat and intent, symptoms of mental illness, and significant life experiences. In every case, the attack or near-attack was the end result of an understandable, and often discernible, process of thinking and action. Implications for protectors, investigators, and researchers are discussed.

  5. Attack or attacked: The sensory and fluid mechanical constraints of copepods’ predator–prey interactions

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2013-01-01

    Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding, and mechani......Many animals are predator and prey at the same time. This dual position represents a fundamental dilemma because gathering food often leads to increased exposure to predators. The optimization of the tradeoff between eating and not being eaten depends strongly on the sensing, feeding...

  6. Major depressive disorder following terrorist attacks: A systematic review of prevalence, course and correlates

    Directory of Open Access Journals (Sweden)

    Cano-Vindel Antonio

    2011-06-01

    Full Text Available Abstract Background Terrorist attacks are traumatic events that may result in a wide range of psychological disorders for people exposed. This review aimed to systematically assess the current evidence on major depressive disorder (MDD after terrorist attacks. Methods A systematic review was performed. Studies included assessed the impact of human-made, intentional, terrorist attacks in direct victims and/or persons in general population and evaluated MDD based on diagnostic criteria. Results A total of 567 reports were identified, 11 of which were eligible for this review: 6 carried out with direct victims, 4 with persons in general population, and 1 with victims and general population. The reviewed literature suggests that the risk of MDD ranges between 20 and 30% in direct victims and between 4 and 10% in the general population in the first few months after terrorist attacks. Characteristics that tend to increase risk of MDD after a terrorist attack are female gender, having experienced more stressful situations before or after the attack, peritraumatic reactions during the attack, loss of psychosocial resources, and low social support. The course of MDD after terrorist attacks is less clear due to the scarcity of longitudinal studies. Conclusions Methodological limitations in the literature of this field are considered and potentially important areas for future research such as the assessment of the course of MDD, the study of correlates of MDD or the comorbidity between MDD and other mental health problems are discussed.

  7. Detection and Discrimination of DDoS Attacks from Flash Crowd Using Entropy Variations

    Directory of Open Access Journals (Sweden)

    Pragya Katiyar

    2013-08-01

    Full Text Available Internet is a worldwide network that combines millions local to global scope, private public, academics, business, optical network technologies, government networks. It carries an expandable rangeof information resources and services which lead to bulk exchange of traffic over the Internet every day. This excessive popularity creates some troubles in the networks. Among them, Flash Crowd andDistributed Denial of Service (DDoS attacks are the two major events. Web services needs stability and security from these two concerns. There are some methods that can discriminate DDoS attack from flash crowd and trace the sources of the attack in huge volume of network traffic. However, it is difficult to detect the exact sources of DDoS attacks in network traffic when Flash crowd event is also present. Due to the alikeness of these two anomalies, attacker can easily mimic the malicious flow into legitimate traffic patterns and defence system cannot detect real sources of attack on time. In this paper, entropy variation, a theoretic parameter, is used to discriminate DDoS attack from Flash Crowd and trace the sources of theDDoS attack. Entropy variation is a theoretic concept which is a measure of changes in concentration of distribution of flows at a router for a given time duration. The proposed strategy is effective and efficiently scalable that has several advantages like memory non intensive, minimum overhead in terms of resources and time, and independent of traffic pattern.

  8. 77 FR 56515 - Continuation of the National Emergency With Respect to Certain Terrorist Attacks

    Science.gov (United States)

    2012-09-12

    ..., 2012. [FR Doc. 2012-22708 Filed 9-11-12; 2:15 pm] Billing code 3295-F2-P ... With Respect to Certain Terrorist Attacks Notice of September 11, 2012--Continuation of the National... the National Emergency With Respect to Certain Terrorist Attacks Consistent with section 202(d) of...

  9. Evolution of Swarming Behavior Is Shaped by How Predators Attack.

    Science.gov (United States)

    Olson, Randal S; Knoester, David B; Adami, Christoph

    2016-01-01

    Animal grouping behaviors have been widely studied due to their implications for understanding social intelligence, collective cognition, and potential applications in engineering, artificial intelligence, and robotics. An important biological aspect of these studies is discerning which selection pressures favor the evolution of grouping behavior. In the past decade, researchers have begun using evolutionary computation to study the evolutionary effects of these selection pressures in predator-prey models. The selfish herd hypothesis states that concentrated groups arise because prey selfishly attempt to place their conspecifics between themselves and the predator, thus causing an endless cycle of movement toward the center of the group. Using an evolutionary model of a predator-prey system, we show that how predators attack is critical to the evolution of the selfish herd. Following this discovery, we show that density-dependent predation provides an abstraction of Hamilton's original formulation of domains of danger. Finally, we verify that density-dependent predation provides a sufficient selective advantage for prey to evolve the selfish herd in response to predation by coevolving predators. Thus, our work corroborates Hamilton's selfish herd hypothesis in a digital evolutionary model, refines the assumptions of the selfish herd hypothesis, and generalizes the domain of danger concept to density-dependent predation. PMID:27139941

  10. Investigation of digestion Kinetics in commercial starches using in-situ small-angle neutron scattering

    International Nuclear Information System (INIS)

    Full text: The digestion of starch has been the subject of many investigations, mostly involving in vitro measurement of the susceptibility of starches to attack by different enzymes, rather than measuring actual digestibility in vivo. The rate and extent of amylolytic hydrolysis of granular starches is known to vary according to botanical origin. Granule characteristics considered to influence susceptibility to attack by alpha-amylase include crystallinity, granule size and available specific surface, amylose content, porosity, structural inhomogeneities and degree of integrity. Most in-vitro studies of granular starch digestion have been limited to samples for which aliquots have been removed from the reaction mixture at various time intervals and freeze-dried to be subsequently characterized using a range of techniques. It remains unclear whether sample preparation creates artefacts in the samples. In this study, we have studied the kinetics of starch digestion of several commercial granular starches by time-resolved small-angle neutron scattering using an in-situ digestion chamber allowing, for the first time, to follow structural changes of starch in the course of digestion directly in the digestion mixture. Additionally, samples before and after digestion were studied by x-ray diffraction, small-angle x-ray scattering, differential scanning calorimetry and microscopy. Microscopy revealed that studied starches, which varied in their amylose content and digestion kinetics, followed different modes of attack The multidisciplinary approach allowed the nanostructural changes detected by small-angle scattering in the course of enzymic breakdown to be correlated with changes in crystallinity and functional properties.

  11. Seven Deadliest Wireless Technologies Attacks

    CERN Document Server

    Haines, Brad

    2010-01-01

    How can an information security professional keep up with all of the hacks, attacks, and exploits? One way to find out what the worst of the worst are is to read the seven books in our Seven Deadliest Attacks Series. Not only do we let you in on the anatomy of these attacks but we also tell you how to get rid of them and how to defend against them in the future. Countermeasures are detailed so that you can fight against similar attacks as they evolve. Attacks featured in this book include:Bluetooth AttacksCredit Card, Access Card, and Passport AttacksBad Encryption

  12. Formal reconstruction of attack scenarios in mobile ad hoc and sensor networks

    Directory of Open Access Journals (Sweden)

    Rekhis Slim

    2011-01-01

    Full Text Available Abstract Several techniques of theoretical digital investigation are presented in the literature but most of them are unsuitable to cope with attacks in wireless networks, especially in Mobile Ad hoc and Sensor Networks (MASNets. In this article, we propose a formal approach for digital investigation of security attacks in wireless networks. We provide a model for describing attack scenarios in a wireless environment, and system and network evidence generated consequently. The use of formal approaches is motivated by the need to avoid ad hoc generation of results that impedes the accuracy of analysis and integrity of investigation. We develop an inference system that integrates the two types of evidence, handles incompleteness and duplication of information in them, and allows possible and provable actions and attack scenarios to be generated. To illustrate the proposal, we consider a case study dealing with the investigation of a remote buffer overflow attack.

  13. Review of syn-flooding attack detection mechanism

    CERN Document Server

    Manna, Mehdi Ebady

    2012-01-01

    Denial of Service (DoS) is a security threat which compromises the confidentiality of information stored in Local Area Networks (LANs) due to unauthorized access by spoofed IP addresses. SYN Flooding is a type of DoS which is harmful to network as the flooding of packets may delay other users from accessing the server and in severe cases, the server may need to be shut down, wasting valuable resources, especially in critical real-time services such as in e-commerce and the medical field. The objective of this paper is to review the state-of-the art of detection mechanisms for SYN flooding. The detection schemes for SYN Flooding attacks have been classified broadly into three categories - detection schemes based on the router data structure, detection schemes based on statistical analysis of the packet flow and detection schemes based on artificial intelligence. The advantages and disadvantages for various detection schemes under each category have been critically examined. The performance measures of the cate...

  14. Usefulness of chest radiographs in first asthma attacks

    International Nuclear Information System (INIS)

    To assess the value of routine chest radiography during acute first attacks of asthma, we studied 371 consecutive children over one year of age who presented with an initial episode of wheezing. Three hundred fifty children (94.3%) had radiographic findings that were compatible with uncomplicated asthma and were considered negative. Twenty-one (5.7%) had positive findings: atelectasis and pneumonia were noted in seven, segmental atelectasis in six, pneumonia in five, multiple areas of subsegmental atelectasis in two, and pneumomediastinum in one. The patients with positive films were more likely to have a respiratory rate above 60 or a pulse rate above 160 (P < 0.001), localized rales or localized decreased breath sounds before treatment (P < 0.01), and localized rales (P < 0.005) and localized wheezing (P < 0.02) after treatment; also, these patients were admitted to the hospital more often (P < 0.001). Ninety-five percent (20 of 21) of the children with positive films could be identified before treatment on the basis of a combination of tachypnea, tachycardia, fever, and localized rales or localized decreased breath sounds. Most first-time wheezers will not have positive radiographs; careful clinical evaluation should reveal which patients will have abnormal radiographs and will therefore benefit from the procedure. 20 references, 3 tables

  15. Development of an accelerated test for Internal Sulfate Attack study

    Directory of Open Access Journals (Sweden)

    Khelil Nacim

    2014-04-01

    Full Text Available Internal Sulfate Attack (ISA is a pathology that occurs under certain conditions in concrete having undergone heating above 70 °C at early age (through heating in pre-casting industry or due to hydration in large concrete parts. This reaction deemed very slow, numerous methods to speed up reactions leading to delayed ettringite formation have been developed. These methods are all based on the material damage. Another type of test is currently under development. It is based on rehabilitation techniques such as electrochemical chloride extraction (ECE in order to accelerate the leaching of alkalis that could be one of the triggers of the pathology. The study presented in this paper focused on concrete specimens prepared from cement (CEM I 52.5 N enriched with Na2SO4. These concretes have undergone a heat treatment typical of those used in precast plants (up to 24 hours with a maximum temperature of 80 °C. Various paths were explored for the development of the accelerated test. The first results showed that it was necessary to use a removable titanium anode ruthenium anode instead of stainless steel embedded in the concrete. Then tests with de-ionized water as the solute to the cathode did not accelerate the onset of expansions. The experiment has been modified and potassium carbonate was added to the solution. This modification didn’t show any significant improvement, and other experiments are being carried out to explain this result.

  16. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models.

    Science.gov (United States)

    Rao, Nageswara S V; Poole, Stephen W; Ma, Chris Y T; He, Fei; Zhuang, Jun; Yau, David K Y

    2016-04-01

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities, expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical subinfrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures, are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. The analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures. PMID:25847370

  17. Defense of Cyber Infrastructures Against Cyber-Physical Attacks Using Game-Theoretic Models.

    Science.gov (United States)

    Rao, Nageswara S V; Poole, Stephen W; Ma, Chris Y T; He, Fei; Zhuang, Jun; Yau, David K Y

    2016-04-01

    The operation of cyber infrastructures relies on both cyber and physical components, which are subject to incidental and intentional degradations of different kinds. Within the context of network and computing infrastructures, we study the strategic interactions between an attacker and a defender using game-theoretic models that take into account both cyber and physical components. The attacker and defender optimize their individual utilities, expressed as sums of cost and system terms. First, we consider a Boolean attack-defense model, wherein the cyber and physical subinfrastructures may be attacked and reinforced as individual units. Second, we consider a component attack-defense model wherein their components may be attacked and defended, and the infrastructure requires minimum numbers of both to function. We show that the Nash equilibrium under uniform costs in both cases is computable in polynomial time, and it provides high-level deterministic conditions for the infrastructure survival. When probabilities of successful attack and defense, and of incidental failures, are incorporated into the models, the results favor the attacker but otherwise remain qualitatively similar. This approach has been motivated and validated by our experiences with UltraScience Net infrastructure, which was built to support high-performance network experiments. The analytical results, however, are more general, and we apply them to simplified models of cloud and high-performance computing infrastructures.

  18. Denial-of-Service Security Attack in the Continuous-Time World

    DEFF Research Database (Denmark)

    Wang, Shuling; Nielson, Flemming; Nielson, Hanne Riis

    2014-01-01

    -of-service security attack, the expected information from the controllers is not received and as a consequence the physical systems may fail to behave as expected. This paper proposes a formal framework for expressing denial-of-service security attack in hybrid systems. As a virtue, a physical system is able to plan...

  19. Development of an Attack-Resistant and Secure SCADA System using WSN, MANET, and Internet

    Directory of Open Access Journals (Sweden)

    N. Rajesh kumar

    2014-06-01

    Full Text Available Industrial Control Systems (ICS are open to security attacks when they are integrated with IT systems and wireless technologies for enhanced processing and remote control. These Critical Infrastructures (CIs are highly important as they provide service for an entire nation and causes serious danger even when interrupted for a while. Some of the common SCADA (Supervisory Control and Data Acquisition systems involve energy and water distribution systems. In this paper, the energy distribution SCADA system comprising several substations is considered. A secure framework is proposed that combines the energy control system with Wireless Sensor Networks (WSNs, Mobile Ad hoc Networks (MANETs, and the Internet, providing anomaly prevention and status management. SCADA attacks occur at the state estimators of the power systems which are used to route power flows and detect faulty devices. These estimators are located in the SCADA control center which is a sensitive area and measurements must be transmitted over a secure communication channel. The attack-resistance of the SCADA system is enhanced by increasing the hardness and complexity of the attack problem. The Attack-Resistant and Secure (ARS SCADA system is evaluated against existing techniques like NAMDIA (Network-Aware Mitigation of Data Integrity Attacks, Retrofit IDS (Intrusion Detection System, and CSBF (Critical State-Based Filtering for enhancing the attack-resistance and security of SCADA systems. It is found that the performance of ARS SCADA system is good compared to the existing methods in terms of maximum normalized attack impact and latency.

  20. Structural basis of complement membrane attack complex formation

    Science.gov (United States)

    Serna, Marina; Giles, Joanna L.; Morgan, B. Paul; Bubeck, Doryen

    2016-02-01

    In response to complement activation, the membrane attack complex (MAC) assembles from fluid-phase proteins to form pores in lipid bilayers. MAC directly lyses pathogens by a `multi-hit' mechanism; however, sublytic MAC pores on host cells activate signalling pathways. Previous studies have described the structures of individual MAC components and subcomplexes; however, the molecular details of its assembly and mechanism of action remain unresolved. Here we report the electron cryo-microscopy structure of human MAC at subnanometre resolution. Structural analyses define the stoichiometry of the complete pore and identify a network of interaction interfaces that determine its assembly mechanism. MAC adopts a `split-washer' configuration, in contrast to the predicted closed ring observed for perforin and cholesterol-dependent cytolysins. Assembly precursors partially penetrate the lipid bilayer, resulting in an irregular β-barrel pore. Our results demonstrate how differences in symmetric and asymmetric components of the MAC underpin a molecular basis for pore formation and suggest a mechanism of action that extends beyond membrane penetration.

  1. Evolution of serum amylase, lipase and immunoreactive trypsin during pancreatitis attacks.

    Science.gov (United States)

    Courtois, P; Art, G; Vertongen, F; Franckson, J R

    1985-01-01

    The characteristics of the blood curves of alpha-amylase (SA), pancreatic lipase (SL) and immunoreactive trypsin (SIT) have been analyzed in a series of patients daily explored throughout the evolution of pancreatitis attacks; urines were also collected to estimate the amylase-creatinine clearance ratio (ACCR). The following results were obtained. a). The 3 enzymes profiles ran roughly parallel during an acute attack. b). SL rose far higher than SA at the onset of the attack but its decay displayed a shorter half-life than the latter; these features resulted in an absence of systematic difference between their times of return to normal levels at the end of the attack. c). SIT more closely correlated with SL than with SA. d). In common hospital practice, simultaneous SA and SL determinations were proving a more reliable help to diagnose pancreatitis attack than ACCR. PMID:3878108

  2. Temperature Influence on Divergence Angles of Quartz Crystal Wollaston Prism

    International Nuclear Information System (INIS)

    We propose a structural angle and main refractive indices as two key factors to understand the temperature influence on the divergence angles of the Wollaston prism. The temperature influence on the divergence angles of quartz crystal Wollaston prism is studied theoretically The results show that divergence angles decrease with increasing temperature, while the divergence angle of e-light decrease more quickly than that of o-light. The testing system is established to verify the above results, and the experimental results are in agreement well with the theoretical analysis. (fundamental areas of phenomenology (including applications))

  3. Epidemics of panic during a bioterrorist attack--a mathematical model.

    Science.gov (United States)

    Radosavljevic, Vladan; Radunovic, Desanka; Belojevic, Goran

    2009-09-01

    A bioterrorist attacks usually cause epidemics of panic in a targeted population. We have presented epidemiologic aspect of this phenomenon as a three-component model--host, information on an attack and social network. We have proposed a mathematical model of panic and counter-measures as the function of time in a population exposed to a bioterrorist attack. The model comprises ordinary differential equations and graphically presented combinations of the equations parameters. Clinically, we have presented a model through a sequence of psychic conditions and disorders initiated by an act of bioterrorism. This model might be helpful for an attacked community to timely and properly apply counter-measures and to minimize human mental suffering during a bioterrorist attack. PMID:19423234

  4. Characteristics of acute pain attacks in patients with irritable bowel syndrome meeting Rome III criteria

    DEFF Research Database (Denmark)

    Hellström, P.M.; Saito, Y.A.; Bytzer, P.;

    2011-01-01

    Objectives: An international multicenter, prospective, non-interventional, 2-month study characterized acute pain attacks in patients with irritable bowel syndrome (IBS). Methods: Adult patients meeting the Rome III IBS diagnostic criteria with a history of 3 pain attacks per month participated...

  5. Numerical simulation of wave attack on sea dike with asphalt concrete revetment

    NARCIS (Netherlands)

    Jassim, I.; Tan, S.; Vermeer, P.A.; Hicks, M.A.

    2012-01-01

    The numerical simulation of wave attack on a sea dike with an asphalt concrete revetment during a severe storm is carried out using the dynamic Finite Element Method. When wave loads attack the revetment during such a storm, both the revetment and the underlying soil may be damaged. The two-phase fl

  6. 76 FR 56631 - Continuation of the National Emergency With Respect to Certain Terrorist Attacks

    Science.gov (United States)

    2011-09-13

    .... (Presidential Sig.) THE WHITE HOUSE, September 9, 2011. [FR Doc. 2011-23609 Filed 9-12-11; 11:15 am] Billing... With Respect to Certain Terrorist Attacks #0; #0; #0; Presidential Documents #0; #0; #0;#0;Federal... Certain Terrorist Attacks Consistent with section 202(d) of the National Emergencies Act, 50 U.S.C....

  7. 78 FR 56579 - Continuation of the National Emergency With Respect to Certain Terrorist Attacks

    Science.gov (United States)

    2013-09-12

    ... the Congress. (Presidential Sig.) THE WHITE HOUSE, September 10, 2013. [FR Doc. 2013-22406 Filed 9-11... Emergency With Respect to Certain Terrorist Attacks #0; #0; #0; Presidential Documents #0; #0; #0;#0;Federal... to Certain Terrorist Attacks Consistent with section 202(d) of the National Emergencies Act, 50...

  8. Study of DSR and AODV under Sinkhole Attack and Its Proposed Prevention Technique

    Directory of Open Access Journals (Sweden)

    Winnie Main

    2014-03-01

    Full Text Available Mobile Ad-hoc Networks (MANET are wireless mobile nodes that communicate without any predefined infrastructure. This allows MANETs to be easily setup in geographical and terrestrial constraints. To achieve this kind of communication MANET routing protocols play an important role. Two routing protocols, DSR and AODV are studied in detail. This basic trait of a MANET makes its routing protocols very vulnerable to security attacks. One such attack is the ‘Sinkhole’ attack which lures packets towards the sinkhole node. A malicious Sinkhole node severely degrades the network once the attack is in progress. This paper describes two of the popular MANET routing protocols, DSR and AODV and the sinkhole attack on these protocols. Prior research carried out to prevent the sinkhole attack is analyzed. Multiple procedures are documented to prevent and mitigate the problem of Sinkhole in MANETs. The proposed solution relies on tackling the sequence number discontinuity to contain Sinkhole attacks. A prevention technique is proposed that relies on the fact that the sequence number discontinuity if tackled can go a long way in containing Sinkhole attacks.

  9. Frenzied attacks. A micro-sociological analysis of the emotional dynamics of extreme youth violence.

    Science.gov (United States)

    Weenink, Don

    2014-09-01

    Inspired by phenomenological and interactionist studies of youth violence, this article offers an empirical evaluation of Collins's micro-sociological theory of violence. The main question is whether situations of extreme violence have distinct situational dynamics. Based on analyses of 159 interactions taken from judicial case files, situations of extreme youth violence, here called frenzied attacks, were identified on the basis of the state of encapsulation of the attackers (absorbed in the violence, their sole focus is the destruction of the victim) and the disproportionateness of the violence (the attackers continue to hurt the victims even though they do not pose a threat or a challenge to them). Qualitative and statistical analyses revealed that this emotional state results from a social figuration in which the emotional balance shifts toward complete dominance of the attackers. Thus, the occurrence of frenzied attacks is associated with the moment victims hit the ground, paralyse and start to apologize, with the numerical dominance of the attackers' supportive group and with feelings of group membership, in the form of solidarity excitement and family ties in the attackers' group. Alcohol intoxication is of influence as well, but contrary to the expectation, this effect was independent from solidarity excitement. The article concludes that Collins's theory on the emotional dynamics of violence adds a new dimension to the phenomenological and interactionist traditions of research.

  10. PERFORMANCE ANALYSIS OF ADHOC ON DEMAND DISTANCE VECTOR PROTOCOL WITH BLACKHOLE ATTACK IN WSN

    Directory of Open Access Journals (Sweden)

    Adnan Ahmed

    2014-01-01

    Full Text Available The security is major challenging issue in wireless sensor network applications because they are operated in public and unrestrained areas which also makes difficult to protect against tampering or captured by an adversary force that can launch insider attacks to make a node compromised. One type of such attack is black hole attack. Existing AODV routing protocol does not have mechanism to defend against such attacks. In this study, we comprehensively investigates the performance of AODV protocol by simulating it on the various network parameters with various number of blackhole nodes. The metrics for evaluation has been considered as packet delivery ratio, end to end delay, normalized routing overhead and total number of packets drop. The simulation results show that blackhole attack severely degrades the performance of WSN.

  11. On Linear Hulls, Statistical Saturation Attacks, PRESENT and a Cryptanalysis of PUFFIN

    DEFF Research Database (Denmark)

    Leander, Gregor

    2011-01-01

    We discuss complexities of advanced linear attacks. In particular, we argue why it is often more appropriate to examine the median of the complexity than the average value. Moreover, we apply our methods to the block ciphers PUFFIN and PRESENT. For PUFFIN, a 128 bit key cipher, we present an attack...... which breaks the cipher for at least a quarter of the keys with a complexity less than 258. In the case of PRESENT we show that the design is sound. The design criteria are sufficient to ensure the resistance against linear attacks, taking into account the notion of linear hulls. Finally, we show...... that statistical saturation attacks and multi dimensional linear attacks are almost identical....

  12. Building Computer Network Attacks

    CERN Document Server

    Futoransky, Ariel; Richarte, Gerardo; Sarraute, Carlos

    2010-01-01

    In this work we start walking the path to a new perspective for viewing cyberwarfare scenarios, by introducing conceptual tools (a formal model) to evaluate the costs of an attack, to describe the theater of operations, targets, missions, actions, plans and assets involved in cyberwarfare attacks. We also describe two applications of this model: autonomous planning leading to automated penetration tests, and attack simulations, allowing a system administrator to evaluate the vulnerabilities of his network.

  13. Abnormal brain processing of cutaneous pain in migraine patients during the attack.

    Science.gov (United States)

    de Tommaso, Marina; Guido, Marco; Libro, Giuseppe; Losito, Luciana; Sciruicchio, Vittorio; Monetti, Carlo; Puca, Francomichele

    2002-11-15

    We examined cutaneous pain thresholds using CO(2) laser stimuli during migraine attacks, and defined the evoked cortical potential characteristics. Ten patients without aura were studied during attacks and for at least 72 h subsequently. Pain stimuli were generated on the dorsum of both hands and the right and left supraorbital zones, using pulses from a CO(2) laser. Absolute latencies of scalp potentials were measured at the highest peak of each response component, and the peak-to-peak amplitudes of N2a-P2 components were recorded. Cutaneous pain thresholds were significantly reduced on both the symptomatic and non-symptomatic sides during the attack, in comparison with the headache-free phase. The N2a-P2 complexes also increased in amplitude during attacks in comparison with the pain-free side. Thus, cutaneous hyperalgesia occurs during migraine attack, and is subtended by central sensitization phenomena, probably involving the cortex.

  14. Impacts of tropical cyclone inflow angle on ocean surface waves

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei; HONG Xin

    2011-01-01

    The inflow angle of tropical cyclones (TC) is generally neglected in numerical studies of ocean surface waves induced by TC. In this study, the impacts of TC inflow angle on ocean surface waves were investigated using a high-resolution wave model. Six numerical experiments were conducted to examine, in detail, the effects of inflow angle on mean wave parameters and the spectrum of wave directions. A comparison of the waves simulated in these experiments shows that inflow angle significantly modifies TC-induced ocean surface waves. As the inflow angle increases, the asymmetric axis of the significant wave height (SWH) field shifts 30° clockwise, and the maximum SWH moves from the front-right to the rear-right quadrant. Inflow angle also affects other mean wave parameters, especially in the rear-left quadrant, such as the mean wave direction, the mean wavelength, and the peak direction. Inflow angle is a key factor in wave models for the reproduction of double-peak or multi-peak patterns in the spectrum of wave directions. Sensitivity experiments also show that the simulation with a 40° inflow angle is the closest to that of the NOAA statistical SLOSH inflow angle. This suggests that 40° can be used as the inflow angle in future TC-induced ocean surface wave simulations when SLOSH or observed inflow angles are not available.

  15. Identification and Ranking of Critical Assets within an Electrical Grid under Threat of Cyber Attack

    Science.gov (United States)

    Boyer, Blake R.

    This paper examines the ranking of critical assets within an electrical grid under threat of cyber attack.1 Critical to this analysis is the assumption of zero hour exploits namely, the threat of an immediate attack as soon as a vulnerability is discovered. Modeling shows that over time load fluctuations as well as other system variations will change the importance of each asset in the delivery of bulk power. As opposed to classic stability studies where risk can be shown to be greatest during high load periods, the zero hour exploit-cyber-risk assumes that vulnerabilities will be attacked as soon as they are discovered. The probability of attacks is made uniform over time to include any and all possible attacks. Examining the impact of an attack and how the grid reacts immediately following an attack will identify and determine the criticality of each asset. This work endeavors to fulfill the NERC Critical Infrastructure Protection Requirements CIP-001-1 through CIP-009-2, cyber security requirements for the reliable supply of bulk power to customers throughout North America. 1Critical assets will here refer to facilities, systems, and equipment, which, if destroyed, degraded, or otherwise rendered unavailable, would affect the reliability or operability of the Bulk Electric System, NERC Glossary of Terms Used in Reliability Standards, 2009

  16. Effect of Helicobacter Pylori Treatment on the Number and Intensity of Migraine Attacks

    Directory of Open Access Journals (Sweden)

    Alireza Bakhshipour

    2012-06-01

    Full Text Available Background: Migraine is a common headache with an unknown cause. Migraine is about three times more common in women (18.2% than in men (6.2%. The recent studies have posed the possible relationship between the Helicobacter pylori infection and migraine headache. This study tries to analyze the effect of treating H. pylori infection on number and severity of migraine attacks.Materials and Methods: In this clinical pilot study, a number of 60 patients with migraine were examined in terms of infecting with H. pylori. Patients with the infections were treated by H. pylori eradication treatment standard triple regimen and the frequency and severity of their migraine attacks were measured for three months and finally the average of frequency and severity of attacks before and after treatment were compared. Results: The average frequency of the migraine attacks in patients with the H.pylori infection who have been treated was 7.1 before treatment and 2.7 after treatment (p=0.001. Likewise, the severity rate of such attacks in such patients was 9 which decreased to 4.5 after treatment (p=0.002. Conclusion: According to our study, patients with migraine attacks are preferred to be examined tested in terms of infecting with H. pylori. Thus, and eradication of this infection can be effective in decreasing of the migraine attacks.

  17. A Review of Current Routing Attacks in Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Rashid Hafeez Khokhar

    2008-11-01

    Full Text Available A mobile ad hoc network (MANET is a dynamic wireless network that can be formed without any pre-existing infrastructure in which each node can act as a router. MANET has no clear line of defense, so, it is accessible to both legitimate network users and malicious attackers. In the presence of malicious nodes, one of the main challenges in MANET is to design the robust security solution that can protect MANET from various routing attacks. Different mechanisms have been proposed using various cryptographic techniques to countermeasure the routing attacks against MANET. However, these mechanisms are not suitable for MANET resource constraints, i.e., limited bandwidth and battery power, because they introduce heavy traffic load to exchange and verifying keys. In this paper, the current security issues in MANET are investigated. Particularly, we have examined different routing attacks, such as flooding, blackhole, link spoofing, wormhole, and colluding misrelay attacks, as well as existing solutions to protect MANET protocols.

  18. Building Computer Network Attacks

    OpenAIRE

    Futoransky, Ariel; Notarfrancesco, Luciano; Richarte, Gerardo; Sarraute, Carlos

    2010-01-01

    In this work we start walking the path to a new perspective for viewing cyberwarfare scenarios, by introducing conceptual tools (a formal model) to evaluate the costs of an attack, to describe the theater of operations, targets, missions, actions, plans and assets involved in cyberwarfare attacks. We also describe two applications of this model: autonomous planning leading to automated penetration tests, and attack simulations, allowing a system administrator to evaluate the vulnerabilities o...

  19. Superwide-angle acoustic propagations above the critical angles of the Snell law in liquid—solid superlattice

    Science.gov (United States)

    Zhang, Sai; Zhang, Yu; Gao, Xiao-Wei

    2014-12-01

    In this paper, superwide-angle acoustic propagations above the critical angles of the Snell law in liquid—solid superlattice are investigated. Incident waves above the critical angles of the Snell law usually inevitably induce total reflection. However, incident waves with big oblique angles through the liquid—solid superlattice will produce a superwide angle transmission in a certain frequency range so that total reflection does not occur. Together with the simulation by finite element analysis, theoretical analysis by using transfer matrix method suggests the Bragg scattering of the Lamb waves as the physical mechanism of acoustic wave super-propagation far beyond the critical angle. Incident angle, filling fraction, and material thickness have significant influences on propagation. Superwide-angle propagation phenomenon may have potential applications in nondestructive evaluation of layered structures and controlling of energy flux.

  20. Design Estimation of Aerodynamic Angles of High Speed Cars

    Directory of Open Access Journals (Sweden)

    Debojyoti Mitra

    2010-05-01

    Full Text Available The study of aerodynamic design of high-speed cars is mainly based on the wind-tunnel experiments and computational methods till date. In this particular study three car models of 100,200,300 pitch angles and 500,600,700 yaw angles are employed, and by wind-tunnel experiments we obtain pressure distributions over them. Now the correlations between drag-coefficient, lift-coefficient, pitch-angle and yaw-angle with Reynolds number are obtained by regression analysis of experimental data using MATLAB software. After plotting graphs it can be concluded that for minimum aerodynamic drag the optimized value of pitch and yaw angle should be 300 and 500. This type of study is expected to give a fair idea of aerodynamic angle design of high-speed cars.

  1. Note: A gel based imaging technique of the iridocorneal angle for evaluation of angle-closure glaucoma

    Science.gov (United States)

    Shinoj, V. K.; Murukeshan, V. M.; Baskaran, M.; Aung, T.

    2014-06-01

    Noninvasive medical imaging techniques have high potential in the field of ocular imaging research. Angle closure glaucoma is a major disease causing blindness and a possible way of detection is the examination of the anterior chamber angle in eyes. Here, a simple optical method for the evaluation of angle-closure glaucoma is proposed and illustrated. The light propagation from the region associated with the iridocorneal angle to the exterior of eye is considered analytically. The design of the gel assisted probe prototype is carried out and the imaging of iridocorneal angle is performed on an eye model.

  2. Clinical analysis on neuroprotection of transient ischemic attacks

    Institute of Scientific and Technical Information of China (English)

    Dimitar Maslarov; Desislava Drenska

    2011-01-01

    Transient ischemic attack (TIA) is an acute cerebrovascular incident, and is generally considered the best opportunity for early neuroprotective treatment against cerebral ischemia. This study retrospectively analyzed 80 patients with TIA (38 males and 42 females). Among 61 patients who received neuroprotective cerebrolysin treatment within 24 hours after TIA onset, 13 (21.31%)patients suffered subsequent strokes. Among 19 patients who received neuroprotective

  3. The correlation of multi-angle thermal infrared data and the choice of optimal view angles

    Institute of Scientific and Technical Information of China (English)

    FAN; Wenjie; XU; Xiru

    2004-01-01

    Based on the matrix formula of thermal infrared radiant system, the components temperature can be retrieved by the inversive matrix. Around the stability problem of retrieved result, the research work we did was focused on (i) the correlation of (wk,j) which is the key to affect the retrieval accuracy, (ii) a general method which can help us find the number of retrievable parameters and evaluate the retrieval error before its performance, (iii) the choice of "optimal viewing angle group" based on the formula of absolute error propagation. The row winter wheat field was chosen as an example. The results can provide a theoretical basis for multi-angle thermal infrared remote sensing and components temperature retrieval.

  4. A Review of Network Forensics Techniques for the Analysis of Web Based Attack

    Directory of Open Access Journals (Sweden)

    Mr. Sudhakar Parate, Ms. S. M. Nirkhi

    2012-12-01

    Full Text Available Network forensics has been the most prevalenttechnology to investigate different attack. It used fortroubleshooting connection issues and helping tosolve various network security problems, such assystem log, router log, and access control. NetworkForensic help to identify the evidences of datasource as intermediate side and the end sides. Thispaper gives comprehensive review on varioustechniques that helps to improve the system,analysis of different attack, detection of attack. Itfocuses on the critical stages of preservation andacquisition of digital evidence from the differentsource to be used as evidence for aidinginvestigation.

  5. Seven Deadliest Network Attacks

    CERN Document Server

    Prowell, Stacy; Borkin, Mike

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting networks? Then you need Seven Deadliest Network Attacks. This book pinpoints the most dangerous hacks and exploits specific to networks, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: Denial of Service War Dialing Penetration "Testing" Protocol Tunneling Spanning Tree At

  6. Terror attacks increases the risk of vascular injuries

    Directory of Open Access Journals (Sweden)

    Eitan eHeldenberg

    2014-05-01

    Full Text Available Objectives: Extensive literature exists about military trauma as opposed to the very limited literature regarding terror-related civilian trauma. However, terror-related vascular trauma (VT, as a unique type of injury, is yet to be addressed.Methods: A retrospective analysis of the Israeli National Trauma Registry was performed. All patients in the registry from 09/2000 to 12/2005 were included. The subgroup of patients with documented vascular trauma (VT (N=1,545 was analyzedand further subdivided into those suffering from Terror-related Vascular Trauma (TVT and Non-Terror related Vascular Trauma (NTVT. Both groups were analyzed according to mechanism of trauma, type and severity of injury and treatment.Results: Out of 2,446 terror related trauma admissions 243 sustained TVT (9.9% compared to 1302 VT patients from Non Terror trauma (1.1%. TVT injuries tend to be more complex and most patients were operated on. ICU admissions and hospitallength of stay was higher in the TVT group. Penetrating trauma was the prominent cause of injury among the TVT group. TVT group had a higher proportion of patients with severe injuries (ISS>16 and mortality. Thorax injuries were more frequent in the TVT group. Extremity injuries were the most prevalent vascular injuries in both groups; however NTVT group had more upper extremity injuries, while the TVT group had significantly more lower extremity injuries.Conclusion: Vascular injuries are remarkably more common among terror attack victims than among non-terror trauma victims and the injuries of terror casualties tend to be more complex. The presence of a vascular surgeon will ensure a comprehensive clinical care.

  7. Seven deadliest USB attacks

    CERN Document Server

    Anderson, Brian

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting USB technology? Then you need Seven Deadliest USB Attacks. This book pinpoints the most dangerous hacks and exploits specific to USB, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Attacks detailed in this book include: USB Hacksaw USB Switchblade USB Based Virus/Malicous Code Launch USB Device Overflow RAMdum

  8. Seven Deadliest Microsoft Attacks

    CERN Document Server

    Kraus, Rob; Borkin, Mike; Alpern, Naomi

    2010-01-01

    Do you need to keep up with the latest hacks, attacks, and exploits effecting Microsoft products? Then you need Seven Deadliest Microsoft Attacks. This book pinpoints the most dangerous hacks and exploits specific to Microsoft applications, laying out the anatomy of these attacks including how to make your system more secure. You will discover the best ways to defend against these vicious hacks with step-by-step instruction and learn techniques to make your computer and network impenetrable. Windows Operating System-Password AttacksActive Directory-Escalat

  9. Grounded running in quails: simulations indicate benefits of observed fixed aperture angle between legs before touch-down.

    Science.gov (United States)

    Andrada, Emanuel; Rode, Christian; Blickhan, Reinhard

    2013-10-21

    Many birds use grounded running (running without aerial phases) in a wide range of speeds. Contrary to walking and running, numerical investigations of this gait based on the BSLIP (bipedal spring loaded inverted pendulum) template are rare. To obtain template related parameters of quails (e.g. leg stiffness) we used x-ray cinematography combined with ground reaction force measurements of quail grounded running. Interestingly, with speed the quails did not adjust the swing leg's angle of attack with respect to the ground but adapted the angle between legs (which we termed aperture angle), and fixed it about 30ms before touchdown. In simulations with the BSLIP we compared this swing leg alignment policy with the fixed angle of attack with respect to the ground typically used in the literature. We found symmetric periodic grounded running in a simply connected subset comprising one third of the investigated parameter space. The fixed aperture angle strategy revealed improved local stability and surprising tolerance with respect to large perturbations. Starting with the periodic solutions, after step-down step-up or step-up step-down perturbations of 10% leg rest length, in the vast majority of cases the bipedal SLIP could accomplish at least 50 steps to fall. The fixed angle of attack strategy was not feasible. We propose that, in small animals in particular, grounded running may be a common gait that allows highly compliant systems to exploit energy storage without the necessity of quick changes in the locomotor program when facing perturbations. PMID:23831138

  10. Efficiency of actions in attack of diagonal players in female volleyball

    OpenAIRE

    Yevgeniya Strelnykova; Tamara Liakhova

    2016-01-01

    Strelnikova Ye., Lyakhova T.  Purpose: to define efficiency of technical and tactical actions of the diagonal player in the attacking actions of a team depending on schemes of a defensive play of the rival. Material & Methods: the competitive process with participation of 10 players of the role –the diagonal forward of qualification and the adult category was investigated in the pedagogical supervision. The efficiency of actions in attack of diagonal players of women's teams of Student's ...

  11. Impact Angle Control of Interplanetary Shock Geoeffectiveness

    CERN Document Server

    Oliveira, D M

    2015-01-01

    We use OpenGGCM global MHD simulations to study the nightside magnetospheric, magnetotail, and ionospheric responses to interplanetary (IP) fa st forward shocks. Three cases are presented in this study: two inclined oblique shocks, here after IOS-1 and IOS-2, where the latter has a Mach number twice stronger than the former. Both shocks have impact angles of 30$^o$ in relation to the Sun-Earth line. Lastly, we choose a frontal perpendicular shock, FPS, whose shock normal is along the Sun-Earth line, with the same Mach number as IOS-1. We find that, in the IOS-1 case, due to the north-south asymmetry, the magnetotail is deflected southward, leading to a mild compression. The geomagnetic activity observed in the nightside ionosphere is then weak. On the other hand, in the head-on case, the FPS compresses the magnetotail from both sides symmetrically. This compression triggers a substorm allowing a larger amount of stored energy in the magnetotail to be released to the nightside ionosphere, resulting in stronger...

  12. Mapping of low flip angles in magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Balezeau, Fabien; Saint-Jalmes, Herve [LTSI, INSERM U642, Universite Rennes 1 (France); Eliat, Pierre-Antoine [PRISM, IFR 140, Universite Rennes 1 (France); Cayamo, Alejandro Bordelois, E-mail: fabien.balezeau@gmail.com [Centro De BiofIsika Medica, Universidad de Oriente, Santiago de Cuba (Cuba)

    2011-10-21

    Errors in the flip angle have to be corrected in many magnetic resonance imaging applications, especially for T1 quantification. However, the existing methods of B1 mapping fail to measure lower values of the flip angle despite the fact that these are extensively used in dynamic acquisition and 3D imaging. In this study, the nonlinearity of the radiofrequency (RF) transmit chain, especially for very low flip angles, is investigated and a simple method is proposed to accurately determine both the gain of the RF transmitter and the B1 field map for low flip angles. The method makes use of the spoiled gradient echo sequence with long repetition time (TR), such as applied in the double-angle method. It uses an image acquired with a flip angle of 90{sup 0} as a reference image that is robust to B1 inhomogeneity. The ratio of the image at flip angle alpha to the image at a flip angle of 90{sup 0} enables us to calculate the actual value of alpha. This study was carried out at 1.5 and 4.7 T, showing that the linearity of the RF supply system is highly dependent on the hardware. The method proposed here allows us to measure the flip angle from 1{sup 0} to 60{sup 0} with a maximal uncertainty of 10% and to correct T1 maps based on the variable flip angle method.

  13. Prevention of Co-operative Black Hole attack in Manet on DSR protocol using Cryptographic Algorithm

    Directory of Open Access Journals (Sweden)

    G.Vennila

    2014-10-01

    Full Text Available The Mobile ad-hoc network (MANET is a collection of wireless mobile node in which each node can communicate with other node without use of predefined infrastructure. Currently, a lot of efficient protocols have been proposed for MANET. All of these efficient Routing protocols are depends only conviction and supportive environment. Conversely, the networks are more vulnerable to various kinds of routing attacks with the presence of malicious nodes. Black hole attack is one of network layer attack. In this attack, A malicious node make use of routing protocol to advertise itself that has a shortest path to reach destination, drops at the cost of original routing packets. In our work, the proposed algorithm is used to secure the DSR protocol. This will help to improve the performance of Mobile Ad hoc network due to the attack. There are several prevention mechanisms to eliminate the Black Hole attack in MANET. The aim of the paper is to provide better prevention of Co-operative Black hole attack in MANET and how it affects the performance metrics in terms of throughput and delay of the network by comparing the network performance with and without black hole nodes.

  14. Before Using Aspirin to Lower Your Risk of Heart Attack or Stroke, Here Is What You Should Know

    Science.gov (United States)

    ... Medicines Safe Daily Use of Aspirin Before Using Aspirin to Lower Your Risk of Heart Attack or ... care provider can determine whether regular use of aspirin will help to prevent a heart attack or ...

  15. [Risk perception and psychological reactions in public crisis situations using the example of terror attacks].

    Science.gov (United States)

    Grimm, A; Hulse, L; Schmidt, S

    2009-12-01

    The reactions to the 9/11 terror attacks were immense in the western population. In the current review, the impact of terror attacks is presented with surveys, clinical interviews, and scientific polls, which were identified in a comprehensive literature search. Results show that the fear of further terror attacks is comparatively overestimated in the population and is associated with numerous psychological consequences and reactions. The overestimation of the probability of further terror attacks is related among other reasons to its unique features and its strong representation in the media. Several independent studies proved that the number of stress symptoms and psychiatric diagnoses is associated with a high risk perception in relation to terror attacks. This was not only the case for victims of terror attacks, but also for people indirectly exposed to the terror attacks. In addition, there is evidence that the number of the stress symptoms correlate with the duration of TV consumption of new findings about terror attempts. Methodologically, there is a critical lack of more in-depth analyses to explain the development of risk perceptions and its influence on mental and physical health. Because of the international importance and cross-cultural differences, an international standardization of research is desirable. PMID:19862488

  16. [Risk perception and psychological reactions in public crisis situations using the example of terror attacks].

    Science.gov (United States)

    Grimm, A; Hulse, L; Schmidt, S

    2009-12-01

    The reactions to the 9/11 terror attacks were immense in the western population. In the current review, the impact of terror attacks is presented with surveys, clinical interviews, and scientific polls, which were identified in a comprehensive literature search. Results show that the fear of further terror attacks is comparatively overestimated in the population and is associated with numerous psychological consequences and reactions. The overestimation of the probability of further terror attacks is related among other reasons to its unique features and its strong representation in the media. Several independent studies proved that the number of stress symptoms and psychiatric diagnoses is associated with a high risk perception in relation to terror attacks. This was not only the case for victims of terror attacks, but also for people indirectly exposed to the terror attacks. In addition, there is evidence that the number of the stress symptoms correlate with the duration of TV consumption of new findings about terror attempts. Methodologically, there is a critical lack of more in-depth analyses to explain the development of risk perceptions and its influence on mental and physical health. Because of the international importance and cross-cultural differences, an international standardization of research is desirable.

  17. The robustness of multiplex networks under layer node-based attack

    Science.gov (United States)

    Zhao, Da-Wei; Wang, Lian-Hai; Zhi, Yong-Feng; Zhang, Jun; Wang, Zhen

    2016-04-01

    From transportation networks to complex infrastructures, and to social and economic networks, a large variety of systems can be described in terms of multiplex networks formed by a set of nodes interacting through different network layers. Network robustness, as one of the most successful application areas of complex networks, has attracted great interest in a myriad of research realms. In this regard, how multiplex networks respond to potential attack is still an open issue. Here we study the robustness of multiplex networks under layer node-based random or targeted attack, which means that nodes just suffer attacks in a given layer yet no additional influence to their connections beyond this layer. A theoretical analysis framework is proposed to calculate the critical threshold and the size of giant component of multiplex networks when nodes are removed randomly or intentionally. Via numerous simulations, it is unveiled that the theoretical method can accurately predict the threshold and the size of giant component, irrespective of attack strategies. Moreover, we also compare the robustness of multiplex networks under multiplex node-based attack and layer node-based attack, and find that layer node-based attack makes multiplex networks more vulnerable, regardless of average degree and underlying topology.

  18. Efficiency of actions in attack of diagonal players in female volleyball

    Directory of Open Access Journals (Sweden)

    Yevgeniya Strelnykova

    2016-04-01

    Full Text Available Purpose: to define efficiency of technical and tactical actions of the diagonal player in the attacking actions of a team depending on schemes of a defensive play of the rival. Material & Methods: the competitive process with participation of 10 players of the role –the diagonal forward of qualification and the adult category was investigated in the pedagogical supervision. The efficiency of actions in attack of diagonal players of women's teams of Student's volleyball league of Kharkov was defined by mathematical processing of the obtained data. Results: we carried out the analysis of references on a condition of a problem of training of the diagonal player, defined tactical combinations in attack in which the diagonal player and efficiency of game actions of the diagonal player take part in the attacking actions of women's teams of Student's volleyball league of Kharkov defining indicators of efficiency of technical and tactical actions of the diagonal player in the attacking actions of women's teams of Student's league of Kharkov against various schemes of a defensive play of teams of the rival. Conclusions: the offered methodical approach based on a quantitative assessment of the competitive activity will allow to rationalize the structure and distribution of means of trainings and to increase the efficiency of the whole educational and training process of training of diagonal players for a game in attack against teams which build a defensive play according to various schemes.

  19. An Efficient Algorithm for the Detection of Exposed and Hidden Wormhole Attack

    Directory of Open Access Journals (Sweden)

    ZUBAIR AHMED KHAN

    2016-07-01

    Full Text Available MANETs (Mobile Ad Hoc Networks are slowly integrating into our everyday lives, their most prominent uses are visible in the disaster and war struck areas where physical infrastructure is almost impossible or very hard to build. MANETs like other networks are facing the threat of malicious users and their activities. A number of attacks have been identified but the most severe of them is the wormhole attack which has the ability to succeed even in case of encrypted traffic and secure networks. Once wormhole is launched successfully, the severity increases by the fact that attackers can launch other attacks too. This paper presents a comprehensive algorithm for the detection of exposed as well as hidden wormhole attack while keeping the detection rate to maximum and at the same reducing false alarms. The algorithm does not require any extra hardware, time synchronization or any special type of nodes. The architecture consists of the combination of Routing Table, RTT (Round Trip Time and RSSI (Received Signal Strength Indicator for comprehensive detection of wormhole attack. The proposed technique is robust, light weight, has low resource requirements and provides real-time detection against the wormhole attack. Simulation results show that the algorithm is able to provide a higher detection rate, packet delivery ratio, negligible false alarms and is also better in terms of Ease of Implementation, Detection Accuracy/ Speed and processing overhead.

  20. Numerical aperture characteristics of angle-ended plastic optical fiber

    Science.gov (United States)

    Gao, Cheng; Farrell, Gerard

    2003-03-01

    With the increasing information rates demanded in consumer, automotive and aeronautical applications, a low cost and high performance physical transmission medium is required. Compared with Silica Optical Fiber, Plastic Optical Fiber (POF) offers an economic solution for a range of high-capacity, short-haul applications in industrial and military environments. Recently, a new type of POF, the perfluorinated graded-index plastic optical fiber (PF GI-POF), has been introduced that has low losses and high bandwidth at the communication wavelengths 850 nm and 1300nm. POF is normally terminated perpendicular to the fiber axis. We propose an angle-ended POF, which is terminated at non-perpendicular angles to the fiber axis. The aim of the research is to investigate the numerical aperture (NA) characteristics of angle-ended POF along the major axis of the elliptical endface. A theoretical model indicates that the NA of the angle-ended POF will increase nonlinearly with tilt-angle and the acceptance cone will be deflected with the angle of the deflection increasing nonlinearly with tilt-angle. We present results for the measured NA and the measured deflection angle using the far-field radiation method. Results are presented for 13 angle-ended SI-POF tilt-angles. We also present results for theoretical value of NA and deflection angle as a function of tilt-angle. The agreement between the measured and theoretical value is good up to tilt-angles of about 15 degrees, beyond which deviation occurs.

  1. Rhynchophorus ferrugineus attack affects a group of compounds rather than rearranging Phoenix canariensis metabolic pathways

    Institute of Scientific and Technical Information of China (English)

    Antonio Giovino; Federico Martinelli; Sergio Saia

    2016-01-01

    The red palm weevil (RPW; Rhynchophorus ferrugi-neus) is spreading worldwide and severely harming many palm species. However, most studies on RPW focused on insect biology, and little information is available about the plant response to the attack. In the present experiment, we used metabolomics to study the alteration of the leaf metabolome of Phoenix canariensis at initial (1st stage) or advanced (2nd stage) attack by RPW compared with healthy (unattacked) plants. The leaf metabolome significantly varied among treatments. At the 1st stage of attack, plants showed a reprogramming of carbohydrate and organic acid metabolism;in contrast, peptides and lipid metabolic pathways underwent more changes during the 2nd than 1st stage of attack. Enrichment metabolomics analysis indicated that RPW attack mostly affected a particular group of compounds rather than rearranging plant metabolic pathways. Some compounds selectively affected during the 1st rather than 2nd stage (e.g. phenylalanine;tryptophan;cel obiose;xylose;quinate;xylonite;idonate;and iso-threonate;cel obiotol and arbutine) are upstream events in the phenylpropanoid, terpenoid and alkaloid biosynthesis. These compounds could be designated as potential markers of initial RPW attack. However, further investigation is needed to determine efficient early screening methods of RPW attack based on the concentrations of these molecules.

  2. Denial of Service Attack: Analysis of Network Traffic Anormaly using Queuing Theory

    CERN Document Server

    Singh, Neetu; Chaudhuri, Pranay

    2010-01-01

    Denial-of-service (DOS) attacks increasingly gained reputation over the past few years. As the Internet becomes more ubiquitous, the threat of the denial-of-service attacks becomes more realistic and important for individuals, businesses, governmental organizations, and even countries. There is intensive need to detect an attack in progress as soon as possible. The efficiency of diagnosing the DOS attack using concepts of queuing theory and performance parameter of the system has been investigated in the present work, as the servers definitely have some mechanisms to store and process the requests. Utilizing this concept of queuing theory, the collection of data patterns were generated. With the performance parameter of the system, the analysis of the data pattern had been made to diagnose the network anomaly. Performance analysis and results show the accuracy of the proposed scheme in detecting anomalies.

  3. Modelling the attack success of planktonic predators: patterns and mechanisms of prey size selectivity

    DEFF Research Database (Denmark)

    Caparroy, P.; Thygesen, Uffe Høgsbro; Visser, Andre

    2000-01-01

    A mathematical model of the attack success of planktonic predators (fish larvae and carnivorous copepods) is proposed. Based on a geometric representation of attack events, the model considers how the escape reaction characteristics (speed and direction) of copepod prey affect their probability...... of being captured. By combining the attack success model with previously published hydrodynamic models of predator and prey perception, we examine how predator foraging behaviour and prey perceptive ability affect the size spectra of encountered and captured copepod prey. We examine food size spectra of (i......) a rheotactic cruising predator, (ii) a suspension-feeding hovering copepod and (iii) a larval fish. For rheotactic predators such as carnivorous copepods, a central assumption of the model is that attack is triggered by prey escape reaction, which in turn depends on the deformation rate of the fluid created...

  4. A Survey On Various Defense Mechanisms Against Application Layer Distributed Denial Of Service Attack

    Directory of Open Access Journals (Sweden)

    Ms. Anuja R. Zade

    2011-11-01

    Full Text Available The severity of application layer Distributed Denial of Service attack has become a major threat to network operators nowadays. Application layer Distributed Denial of Service attack causes unavailability of resources, revenue loss, and customer churns etc and is one of the most difficult problems to defend against in the internet. The goal of paper is to understand various techniquesproposed recently to defend against specifically application layer Distributed Denial of Service attack. The next step in the path would be to come up with a better solution to solve this problem. Undoubtedly the following discussed techniques are extremely good. A collaborative approach using few of them can be a better solution.

  5. The framework for simulation of bioinspired security mechanisms against network infrastructure attacks.

    Science.gov (United States)

    Shorov, Andrey; Kotenko, Igor

    2014-01-01

    The paper outlines a bioinspired approach named "network nervous system" and methods of simulation of infrastructure attacks and protection mechanisms based on this approach. The protection mechanisms based on this approach consist of distributed procedures of information collection and processing, which coordinate the activities of the main devices of a computer network, identify attacks, and determine necessary countermeasures. Attacks and protection mechanisms are specified as structural models using a set-theoretic approach. An environment for simulation of protection mechanisms based on the biological metaphor is considered; the experiments demonstrating the effectiveness of the protection mechanisms are described.

  6. Heavy-tailed distribution of the SSH Brute-force attack duration in a multi-user environment

    Science.gov (United States)

    Lee, Jae-Kook; Kim, Sung-Jun; Park, Chan Yeol; Hong, Taeyoung; Chae, Huiseung

    2016-07-01

    Quite a number of cyber-attacks to be place against supercomputers that provide highperformance computing (HPC) services to public researcher. Particularly, although the secure shell protocol (SSH) brute-force attack is one of the traditional attack methods, it is still being used. Because stealth attacks that feign regular access may occur, they are even harder to detect. In this paper, we introduce methods to detect SSH brute-force attacks by analyzing the server's unsuccessful access logs and the firewall's drop events in a multi-user environment. Then, we analyze the durations of the SSH brute-force attacks that are detected by applying these methods. The results of an analysis of about 10 thousands attack source IP addresses show that the behaviors of abnormal users using SSH brute-force attacks are based on human dynamic characteristics of a typical heavy-tailed distribution.

  7. Determination of the angle of attack on the mexico rotor using experimental data

    DEFF Research Database (Denmark)

    Yang, Hua; Shen, Wen Zhong; Sørensen, Jens Nørkær;

    2010-01-01

    characteristics from experimental data on the MEXICO (Model Experiments in controlled Conditions) rotor. Detailed surface pressure and Particle Image Velocimetry (PIV) flow field at different rotor azimuth positions were examined for determining the sectional airfoil data. It is worthwhile noting that the present...

  8. On the effectiveness of XML schema validation for countering XML signature wrapping attacks

    DEFF Research Database (Denmark)

    Jensen, Meiko; Meyer, Christopher; Somorovsky, Juraj;

    2011-01-01

    In the context of security of Web Services, the XML Signature Wrapping attack technique has lately received increasing attention. Following a broad range of real-world exploits, general interest in applicable countermeasures rises. However, few approaches for countering these attacks have been...... investigated closely enough to make any claims about their effectiveness. In this paper, we analyze the effectiveness of the specific countermeasure of XML Schema validation in terms of fending Signature Wrapping attacks. We investigate the problems of XML Schema validation for Web Services messages...

  9. Handbook of biometric anti-spoofing trusted biometrics under spoofing attacks

    CERN Document Server

    Marcel, Sébastien; Li, Stan Z

    2014-01-01

    As the plethora of approaches to biometrics and their deployment continues to grow, so too does the need to combat the techniques used to subvert the aim of such biometric systems. Presenting the first definitive study of the subject, this Handbook of Biometric Anti-Spoofing reviews the state of the art in covert attacks against biometric systems, and in deriving countermeasures to these attacks. Across a range of common biometrics, including face, iris, fingerprint, speaker and gait, the book describes spoofing methods and examines the vulnerabilities of biometric systems to these attacks.

  10. Childhood Internalizing and Externalizing Problems Predict the Onset of Clinical Panic Attacks over Adolescence: The TRAILS Study

    OpenAIRE

    Mathyssek, Christina M.; Olino, Thomas M.; Verhulst, Frank C.; Oort, Floor V. A.

    2012-01-01

    textabstractBackground: Panic attacks are a source of individual suffering and are an independent risk factor for later psychopathology. However, much less is known about risk factors for the development of panic attacks, particularly during adolescence when the incidence of panic attacks increases dramatically. We examined whether internalizing and externalizing problems in childhood predict the onset of panic attacks in adolescence. Method: This study is part of the TRacking Adolescents' In...

  11. Detection and Avoidance of SQL Injection Attack In Multi-Tier Web Based Application

    Directory of Open Access Journals (Sweden)

    Ms. S.Raichal

    2013-06-01

    Full Text Available The aim of this paper is to prevent sql injection attack using stored procedure. In SQL injection attack,an attacker might deliver malicious SQL query segments as user input which could effect in a different database request. Using SQL injection attacks, an attacker might thus obtain and modify confidential information. An attacker could even use a SQL injection vulnerability as a basic IP or Port scanner of the internal corporate network. The stored procedure does not permit conditional statement there by the hacker cannot identify the IDs. The stored procedure is the new approach that is executed. Stored procedure avoids the attack which is more secured one where the conditional statements are not permitted. In sql injection input is set as conditional statements and the user can able to login into the website. But in this paper every condition are checked in the procedural language of stored procedure.Once it notices the condition statement the user will be blocked to log into the website. Only the correct form of passwords is acceptable.

  12. EVALUATION OF NECK SHAFT ANGLE OF FEMUR ON DRY BONES

    OpenAIRE

    Radha; Ravi Shankar; Naveen; Roopa

    2015-01-01

    BACKGROUND: Evaluation of the neck shaft angle of femur helps to understand clinical relevance in bio mechanics of the hip joint. It helps for the better treatment of different pathological conditions of hip and femur and also to design prosthesis. Femoral neck shaft angle is important to convey the information regarding the race to ...

  13. DETECTION AND LOCALIZATION OF MULTIPLE SPOOFING ATTACKERS FOR MOBILE WIRELESS NETWORKS

    Directory of Open Access Journals (Sweden)

    R. Maivizhi

    2015-06-01

    Full Text Available The openness nature of wireless networks allows adversaries to easily launch variety of spoofing attacks and causes havoc in network performance. Recent approaches used Received Signal Strength (RSS traces, which only detect spoofing attacks in mobile wireless networks. However, it is not always desirable to use these methods as RSS values fluctuate significantly over time due to distance, noise and interference. In this paper, we discusses a novel approach, Mobile spOofing attack DEtection and Localization in WIireless Networks (MODELWIN system, which exploits location information about nodes to detect identity-based spoofing attacks in mobile wireless networks. Also, this approach determines the number of attackers who used the same node identity to masquerade as legitimate device. Moreover, multiple adversaries can be localized accurately. By eliminating attackers the proposed system enhances network performance. We have evaluated our technique through simulation using an 802.11 (WiFi network and an 802.15.4 (Zigbee networks. The results prove that MODELWIN can detect spoofing attacks with a very high detection rate and localize adversaries accurately.

  14. EVALUATION OF NECK SHAFT ANGLE OF FEMUR ON DRY BONES

    Directory of Open Access Journals (Sweden)

    Radha

    2015-04-01

    Full Text Available BACKGROUND: Evaluation of the neck shaft angle of femur helps to understand clinical relevance in bio mechanics of the hip joint. It helps for the better treatment of different pathological conditions of hip and femur and also to design prosthesis. Femoral neck shaft angle is important to convey the information regarding the race to which they belong. Hence the present study was under taken to determine the neck shaft angle of femur in humans. OBJECTIVE: 1. To correct the different types of deformity and to have a normal good walking Mechanism. 2. To know the recent methodology and attempt to evaluate the range of normal Angles of femora and their sex differences. METHODS: ANTHROPOMETRIC: 100 Adult dry bones were studied and analyzed . The neck shaft angle of femur was measured by tracing outlines of contours of all femora. RESULTS: The neck shaft angle of the femur have revealed that there is no much difference in between males and females. There was slightly higher 0.2° in females. INTERPRETATION & CONCLUSION: There was no significant gender difference in neck shaft angle. The Knowledge of knowing the neck shaft angle helps to understand the Biomechanics of the hip joint and also for better treatment of pathological condition of hip and femur.

  15. A study of images of Projective Angles of pulmonary veins

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jue [Beijing Anzhen Hospital, Beijing (China); Zhaoqi, Zhang [Beijing Anzhen Hospital, Beijing (China)], E-mail: zhaoqi5000@vip.sohu.com; Yu Wei; Miao Cuilian; Yan Zixu; Zhao Yike [Beijing Anzhen Hospital, Beijing (China)

    2009-09-15

    Aims: In images of magnetic resonance and computed tomography (CT) there are visible angles between pulmonary veins and the coronary, transversal or sagittal section of body. In this study these angles are measured and defined as Projective Angles of pulmonary veins. Several possible influential factors and characters of distribution are studied and analyzed for a better understanding of this imaging anatomic character of pulmonary veins. And it could be the anatomic base of adjusting correctly the angle of the central X-ray of the angiography of pulmonary veins undergoing the catheter ablation of atrial fibrillation (AF). Method: Images of contrast enhanced magnetic resonance angiography (CEMRA) and contrast enhanced computer tomography (CECT) of the left atrium and pulmonary veins of 137 health objects and patients with atrial fibrillation (AF) are processed with the technique of post-processing, and Projective Angles to the coronary and transversal sections are measured and analyzed statistically. Result: Project Angles of pulmonary veins are one of real and steady imaging anatomic characteristics of pulmonary veins. The statistical distribution of variables is relatively concentrated, with a fairly good representation of average value. It is possible to improve the angle of the central X-ray according to the average value in the selective angiography of pulmonary veins undergoing the catheter ablation of AF.

  16. Contact pressure distribution and support angle optimization of kiln tyre

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    According to the shearing force character and the deformation coordination condition of shell at the station of supports, the mathematical models to calculate contact angle and contact pressure distribution between tyre and shell were set up, the formulae of bending moment and bending stress of tyre were obtained. Taking the maximum of tyre fatigue life as the optimal objective, the optimization model of tyre support angle was built. The computational results show that when tyre support angle is 30°, tyre life is far less than that when tyre support angle is optimal, which is 35.6°, and it is unsuitable to stipulate tyre support angle to be 30° in traditional design. The larger the load, the less the nominal stress amplitude increment of tyre, the more favorable the tyre fatigue life when tyre support angle is optimal.

  17. Mechanism and Etiology of Primary Chronic Angle Closure Glaucoma

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    The ocular anatomic features, pupil-blocking force, status of angle synechiae closure and positivity of provocative tests were compared between the primary chronic angle closure glaucoma (PCACG) and primary a-cute angle closure glaucoma (PAACG) by using ultrasonic biometry, computerized anterior ocular segment image processing technique, gonioscopy and provocative tests. The studies showed that the anterior chamber depth of PAACG was shallower than that of PCACG; the pupil-blocking force of PAACG was st...

  18. Comparative study of Attacks on AODV-based Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    Ipsa De

    2011-01-01

    Full Text Available In recent years, the use of mobile ad hoc networks (MANETs has been widespread in many applications, The lack of infrastructures in MANETs makes the detection and control of security hazards allthe more difficult. The security issue is becoming a major concern and bottle neck in the application of MANET. In this paper, an attempt has been made to thoroughly study the blackhole attack which is one ofthe possible attacks in ad hoc networks in routing protocol AODV with possible solution to blackhole attack detection.

  19. The dynamic correlation between degree and betweenness of complex network under attack

    Science.gov (United States)

    Nie, Tingyuan; Guo, Zheng; Zhao, Kun; Lu, Zhe-Ming

    2016-09-01

    Complex networks are often subjected to failure and attack. Recent work has addressed the resilience of complex networks to either random or intentional deletion of nodes or links. Here we simulate the breakdown of the small-world network and the scale-free network under node failure or attacks. We analyze and discuss the dynamic correlation between degree and betweenness in the process of attack. The simulation results show that the correlation for scale-free network obeys a power law distribution until the network collapses, while it represents irregularly for small-world network.

  20. Perturbative estimates of lepton mixing angles in unified models

    Energy Technology Data Exchange (ETDEWEB)

    Antusch, Stefan [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Muenchen (Germany)], E-mail: antusch@mppmu.mpg.de; King, Stephen F. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Malinsky, Michal [Department of Theoretical Physics, School of Engineering Sciences, Royal Institute of Technology (KTH) - AlbaNova University Center, Roslagstullsbacken 21, SE-106 91 Stockholm (Sweden)

    2009-10-11

    Many unified models predict two large neutrino mixing angles, with the charged lepton mixing angles being small and quark-like, and the neutrino masses being hierarchical. Assuming this, we present simple approximate analytic formulae giving the lepton mixing angles in terms of the underlying high energy neutrino mixing angles together with small perturbations due to both charged lepton corrections and renormalisation group (RG) effects, including also the effects of third family canonical normalization (CN). We apply the perturbative formulae to the ubiquitous case of tri-bimaximal neutrino mixing at the unification scale, in order to predict the theoretical corrections to mixing angle predictions and sum rule relations, and give a general discussion of all limiting cases. We also discuss the implications for the sum rule relations of the measurement of a non-zero reactor angle, as hinted at by recent experimental measurements.