The security development lifecycle (SDL) is becoming an industry standard. Dynamic symbolic execution (DSE) has enormous amount of applications in computer security (fuzzing, vulnerability discovery, reverse-engineeri...
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ISBN:
(数字)9781665412919
ISBN:
(纸本)9781665448215
The security development lifecycle (SDL) is becoming an industry standard. Dynamic symbolic execution (DSE) has enormous amount of applications in computer security (fuzzing, vulnerability discovery, reverse-engineering, etc.). We propose several performance and accuracy improvements for dynamic symbolic execution. Skipping non-symbolic instructions allows to build a path predicate 1.2-3.5 times faster. Symbolic engine simplifies formulas during symbolic execution. Path predicate slicing eliminates irrelevant conjuncts from solver queries. We handle each jump table (switch statement) as multiple branches and describe the method for symbolic execution of multi-threaded programs. The proposed solutions were implemented in Sydr tool. Sydr performs inversion of branches in path predicate. Sydr combines DynamoRIO dynamic binary instrumentation tool with Triton symbolic engine. We evaluated Sydr features on 64-bit Linux executables.
A substantial data volume growth will appear with the start of the HL-LHC era. It is not well covered by the current LHC computing model, even taking into account the hardware evolution. The WLCG DOMA project was esta...
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In this work, we develop software based on porousMultiphaseFoam library in OpenFOAM package to study enhanced oil recovery methods, and to study the influence of these methods on the oil recovery factor. New models of...
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In this work, we develop software based on porousMultiphaseFoam library in OpenFOAM package to study enhanced oil recovery methods, and to study the influence of these methods on the oil recovery factor. New models of relative phase permeability and capillary pressure were implemented, and their comparative analysis was performed. The code was verified using the analytical approach. A new solver for simulating compressible flow was developed.
A novel algorithm of the Lagrangian vortex method is considered for incompressible flow simulation. The boundary condition on the body surface is satisfied by vortex sheet introduction, which intensity is determined f...
A novel algorithm of the Lagrangian vortex method is considered for incompressible flow simulation. The boundary condition on the body surface is satisfied by vortex sheet introduction, which intensity is determined from the equality between the tangential components of flow velocity limit value and the body surface velocity. High accuracy of velocity field reconstruction in the neighbourhood of the body surface permits to estimate unsteady aerodynamic loads for the complex-shaped bodies, including added masses tensor components with rather low computational cost.
In recent years, the research on deep-sea mining has become more and more popular, especially in the interaction between the harvesting system and seabed to estimate and minimize seabed disturbance. In this paper, an ...
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ISBN:
(数字)9781665412919
ISBN:
(纸本)9781665448215
In recent years, the research on deep-sea mining has become more and more popular, especially in the interaction between the harvesting system and seabed to estimate and minimize seabed disturbance. In this paper, an inclined plane is adopted to simplify the front of the nodule harvester, and a solver for simulating turbulent sediment transport and fluid-structure interaction is developed based on the drift-flux model in the OpenFOAM. The volume of fluid (VOF) algorithm is used to simulate the diffusion and sedimentation process of sediment in the water, and the kOmegaSST model is used to calculate the turbulent diffusion coefficient of the mixed solution. Two different dynamic mesh strategies, overset and arbitrarily coupled mesh interface (ACMI) methods, are used to simulate the movement of the tilting push plate. This paper compares the simulation results of two different strategies. The results show that under the same simulation accuracy, ACMI method is more reliable and efficient than overset method.
The numerical method based on the discontinuous Galerkin (DG) approach for perfect inviscid compressible gas dynamics modelling is developed. The approximate Riemann solvers in combination with gas dynamics equations ...
The numerical method based on the discontinuous Galerkin (DG) approach for perfect inviscid compressible gas dynamics modelling is developed. The approximate Riemann solvers in combination with gas dynamics equations system characteristic properties are used to calculate the numerical fluxes on the cells interfaces and inside the cells. A number of approximate Riemann solvers are considered. The solution characteristic decomposition is used in the similar to PPML way. The developed algorithm is tested using problems with smooth and discontinuous solutions. Both one-dimensional and two-dimensional test problems are considered. The method provides accurate discontinuity resolution and ability to compute gas-dynamic instabilities with minimal artificial distortion.
Industrial static analyzers are able to detect only several narrow classes of algorithmic errors, for example actual arguments order swapped with formal parameters, forgotten renaming of variable after copy-paste. How...
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Industrial static analyzers are able to detect only several narrow classes of algorithmic errors, for example actual arguments order swapped with formal parameters, forgotten renaming of variable after copy-paste. However, even for these categories essential part of errors is lost because of heuristical design of a checker. We propose the generalization of specified errors in the form of variable misuse problem and deal with it using machine learning. The proposed method uses message propagation through the program model represented as a graph, combining data from multiple analysis levels, including AST, dataflow. We introduce several error criteria, which were evaluated on the set of open source projects with millions of LoC. Testing in close to industrial conditions shows good false positive and missed errors ratio comparable with remaining detectors and allows to include developed checker (after a minor rework) into a general purpose production static analyzer for error detection.
These days, real-time analytics is one of the most often used notions in the world of databases. Broadly, this term means very fast analytics over very fresh data. Usually the term comes together with other popular te...
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ISBN:
(数字)9781665412919
ISBN:
(纸本)9781665448215
These days, real-time analytics is one of the most often used notions in the world of databases. Broadly, this term means very fast analytics over very fresh data. Usually the term comes together with other popular terms, hybrid transactional/analytical processing (HTAP) and in-memory data processing. The reason is that the simplest way to provide fresh operational data for analysis is to combine in one system both transactional and analytical processing. The most effective way to provide fast transactional and analytical processing is to store an entire database in memory. So on the one hand, these three terms are related but on the other hand, each of them has its own right to life. In this paper, we provide an overview of several in-memory data management systems that are not HTAP systems. Some of them are purely transactional, some are purely analytical, and some support real-time analytics. Then we overview nine in-memory HTAP DBMSs, some of which don't support real-time analytics. Existing real-time in-memory HTAP DBMSs have very diverse and interesting architectures although they use a number of common approaches: multiversion concurrency control, multicore parallelization, advanced query optimization, just in time compilation, etc. Additionally, we are interested whether these systems use non-volatile memory, and, if yes, in what manner. We conclude that an emergence of new generation of NVM will greatly stimulate its use in in-memory HTAP systems.
In this paper, we describe various data caching scenarios test implementation and lessons learned. In particular, we show how local data caches may be configured, deployed, and tested. In our studies, we are using xCa...
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In this paper, we consider the synchronous composition of Finite State Machines (FSMs) that corresponds to instantaneous communication of hardware components. Such FSMs can be deterministic or nondeterministic, partia...
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ISBN:
(纸本)9781728160627
In this paper, we consider the synchronous composition of Finite State Machines (FSMs) that corresponds to instantaneous communication of hardware components. Such FSMs can be deterministic or nondeterministic, partial or complete. We first extend the existing synchronous composition operator from a pair of components to a collection of components with multiple input and output ports, and provide a procedure to compute the composition working directly on the collection of transition tables of the component FSMs. Then, based on the notion of input-output Moore pair (the output is not sensitive to the input), we prove the following sufficient condition: if the composition has the property that every cycle of ports has a component with a Moore pair, then the class of quasi-complete and quasi-deterministic FSMs is closed under the proposed synchronous composition.
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