16,827 research outputs found

    REDIR: Automated Static Detection of Obfuscated Anti-Debugging Techniques

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    Reverse Code Engineering (RCE) to detect anti-debugging techniques in software is a very difficult task. Code obfuscation is an anti-debugging technique makes detection even more challenging. The Rule Engine Detection by Intermediate Representation (REDIR) system for automated static detection of obfuscated anti-debugging techniques is a prototype designed to help the RCE analyst improve performance through this tedious task. Three tenets form the REDIR foundation. First, Intermediate Representation (IR) improves the analyzability of binary programs by reducing a large instruction set down to a handful of semantically equivalent statements. Next, an Expert System (ES) rule-engine searches the IR and initiates a sensemaking process for anti-debugging technique detection. Finally, an IR analysis process confirms the presence of an anti-debug technique. The REDIR system is implemented as a debugger plug-in. Within the debugger, REDIR interacts with a program in the disassembly view. Debugger users can instantly highlight anti-debugging techniques and determine if the presence of a debugger will cause a program to take a conditional jump or fall through to the next instruction

    Vorticity-transport and unstructured RANS investigation of rotor-fuselage interactions

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    The prediction capabilities of unstructured primitive-variable and vorticity-transport-based Navier-Stokes solvers have been compared for rotorcraft-fuselage interaction. Their accuracies have been assessed using the NASA Langley ROBIN series of experiments. Correlation of steady pressure on the isolated fuselage delineates the differences between the viscous and inviscid solvers. The influence of the individual blade passage, model supports, and viscous effects on the unsteady pressure loading has been studied. Smoke visualization from the ROBIN experiment has been used to determine the ability of the codes to predict the wake geometry. The two computational methods are observed to provide similar results within the context of their physical assumptions and simplifications in the test configuration

    Development of a Variable Extensometer Method for Measuring Ductility Scaling Parameters

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    Ductility is the measure of how much a material can stretch before separation. It is usually measured in percent elongation, which is the amount a material stretches divided by its original length before stretching. This is an important property to understand for both the design for performance and safety. A materialā€™s ductility can be influenced by several factors including heat treatment, machining, temperature, and radiation dose. Materials used in nuclear energy facilities are often exposed to all these factors, and it is important to be able to understand ductility at each possible combination. Ductility is usually characterized through tension tests where a material is stretched until separation and the percent elongation is measured. However, ductility measured this way is dependent on the specimen geometry, meaning specimens of different lengths and thicknesses of the same material produce different percent elongation values. To account for this, ductility scaling laws have been developed that scale percent elongation to specimens of different sizes. Traditionally, these laws require testing multiple different specimen geometries to empirically extract the scaling parameters. This can be cost-prohibitive for many materials used for nuclear energy. This work develops a technique for extracting scaling parameters from a single specimen with the use of Digital Image Correlationā€”a camera-based measurement that extracts displacements from the pixel data across the entirety of the specimen. Improvements to the current scaling laws have been proposed, and the technique is validated by testing specimens of multiple different geometries

    Anarchy, Groups, and Conflict: An Experiment on the Emergence of Protective Associations

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    In this paper, we investigate the implications of the philosophical considerations presented in Nozickā€™s Anarchy, State, and Utopia, by examining group formation in a laboratory setting where subjects engage in both cooperative and conflictual interactions. We endow participants with a commodity used to generate earnings, plunder others, or protect against plunder. In our primary treatment, we allow participants to form groups to pool their resources. We conduct a baseline comparison treatment that does not allow group formation. We find that allowing subjects to organize themselves into groups does not lead to more cooperation and may in fact exacerbate tendencies for conflict.Nozickian protective associations, Conflict, Anarchy, Experimental economics

    Coagulation and fragmentation processes with evolving size and shape profiles : a semigroup approach

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    We investigate a class of bivariate coagulation-fragmentation equations. These equations describe the evolution of a system of particles that are characterised not only by a discrete size variable but also by a shape variable which can be either discrete or continuous. Existence and uniqueness of strong solutions to the associated abstract Cauchy problems are established by using the theory of substochastic semigroups of operators
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