3,617 research outputs found
Tailored Source Code Transformations to Synthesize Computationally Diverse Program Variants
The predictability of program execution provides attackers a rich source of
knowledge who can exploit it to spy or remotely control the program. Moving
target defense addresses this issue by constantly switching between many
diverse variants of a program, which reduces the certainty that an attacker can
have about the program execution. The effectiveness of this approach relies on
the availability of a large number of software variants that exhibit different
executions. However, current approaches rely on the natural diversity provided
by off-the-shelf components, which is very limited. In this paper, we explore
the automatic synthesis of large sets of program variants, called sosies.
Sosies provide the same expected functionality as the original program, while
exhibiting different executions. They are said to be computationally diverse.
This work addresses two objectives: comparing different transformations for
increasing the likelihood of sosie synthesis (densifying the search space for
sosies); demonstrating computation diversity in synthesized sosies. We
synthesized 30184 sosies in total, for 9 large, real-world, open source
applications. For all these programs we identified one type of program analysis
that systematically increases the density of sosies; we measured computation
diversity for sosies of 3 programs and found diversity in method calls or data
in more than 40% of sosies. This is a step towards controlled massive
unpredictability of software
DSpot: Test Amplification for Automatic Assessment of Computational Diversity
Context: Computational diversity, i.e., the presence of a set of programs
that all perform compatible services but that exhibit behavioral differences
under certain conditions, is essential for fault tolerance and security.
Objective: We aim at proposing an approach for automatically assessing the
presence of computational diversity. In this work, computationally diverse
variants are defined as (i) sharing the same API, (ii) behaving the same
according to an input-output based specification (a test-suite) and (iii)
exhibiting observable differences when they run outside the specified input
space. Method: Our technique relies on test amplification. We propose source
code transformations on test cases to explore the input domain and
systematically sense the observation domain. We quantify computational
diversity as the dissimilarity between observations on inputs that are outside
the specified domain. Results: We run our experiments on 472 variants of 7
classes from open-source, large and thoroughly tested Java classes. Our test
amplification multiplies by ten the number of input points in the test suite
and is effective at detecting software diversity. Conclusion: The key insights
of this study are: the systematic exploration of the observable output space of
a class provides new insights about its degree of encapsulation; the behavioral
diversity that we observe originates from areas of the code that are
characterized by their flexibility (caching, checking, formatting, etc.).Comment: 12 page
Alignment and IT Project Value Maximization
This paper presents a case study of successful ERP implementation in two phases. The second phase included significant efforts to align the business strategy and organizational structure along with the information system components. These efforts enabled the organization to complete its alignment cycle by integrating its IT infrastructure and processes with the organizational infrastructure and processes, as well as fitting business strategy with the new infrastructure and processes and to reap the maximum value
Full-sky CMB lensing reconstruction in presence of sky-cuts
We consider the reconstruction of the CMB lensing potential and its power
spectrum of the full sphere in presence of sky-cuts due to point sources and
Galactic contaminations. Those two effects are treated separately. Small
regions contaminated by point sources are filled in using Gaussian constrained
realizations. The Galactic plane is simply masked using an apodized mask before
lensing reconstruction. This algorithm recovers the power spectrum of the
lensing potential with no significant bias.Comment: Submitted to A&
Innovation Intensity: From IT Use and Innovative Culture to Organizational Performance
Drawing from past research on information technology (IT) use, organizational culture, and innovation, the present study tests a model exploring the effects of collaborative and experiential culture as well as internally and externally-focused use of IT on innovation intensity and organizational performance. As the innovation process is complex and uncertain, we try to open the black box of innovation intensity by exploring the roles played by the use of IT and the innovation culture. The research model was tested via a structural equation model using PLS with data collected from 395 top executives. Results indicate that intense use of internally and externally- focused IT positively affect innovation intensity. The results also show that collaborative culture increases innovation intensity. In turn, innovation intensity increases both operational and financial performance
Using a crop model to account for the effects of local factors on the LCA of sugar beet ethanol in Picardy region, France
CT1 ; CT3 ; EnjS1 ; EnjS4 ; Base de données AgroclimInternational audienceThe results of published Life Cycle Assessments (LCAs) of biofuels are characterized by a large variability, arising from the diversity of both biofuel chains and the methodologies used to estimate inventory data. Here, we suggest that the best option to maximize the accuracy of biofuel LCA is to produce local results taking into account the local soil, climatic and agricultural management factors. Methods We focused on a case study involving the production of first-generation ethanol from sugar beet in the Picardy region in Northern France. To account for local factors, we first defined three climatic patterns according to rainfall from a 20-year series of weather data. We subsequently defined two crop rotations with sugar beet as a break crop, corresponding to current practice and an optimized management scenario, respectively. The six combinations of climate types and rotations were run with the process-based model CERES-EGC to estimate crop yields and environmental emissions. We completed the data inventory and compiled the impact assessments using Simapro v.7.1 and Ecoinvent database v2.0. Results Overall, sugar beet ethanol had lower impacts than gasoline for the abiotic depletion, global warming, ozone layer depletion and photochemical oxidation categories. In particular, it emitted between 28 % and 42 % less greenhouse gases than gasoline. Conversely, sugar beet ethanol had higher impacts than gasoline for acidification and eutrophication due to losses of reactive nitrogen in the arable field. Thus, LCA results were highly sensitive to changes in local conditions and management factors. As a result, an average impact figures for a given biofuel chain at regional or national scales may only be indicative within a large uncertainty band. Conclusions Although the crop model made it possible to take local factors into account in the life-cycle inventory, best management practices that achieved high yields while reducing environmental impacts could not be identified. Further modelling developments are necessary to better account for the effects of management practices, in particular regarding the benefits of fertiliser incorporation into the topsoil in terms of nitrogen losses abatement. Supplementary data and modelling developments also are needed to better estimate the emissions of pesticides and heavy metals in the field
Toward a better understanding of the placement of shotcrete: Nozzles and velocities
A lot of developments and improvements seen in the shotcrete industry over the last few decades have mostly arisen through the improvement of mixture designs and admixture efficiency. Unfortunately, limited efforts have been put into the modelling and optimization of one of the most important portions: the acceleration of the material through the nozzle and its subsequent travelling toward the surface. The paper first presents a clear explanation and demonstration, based on spray patterns analysis, of the differences between dry-mix and wet-mix shotcrete. It then follows with practical examples of ways to improve the technology behind the nozzle (for both processes) along with unique experimental results. The paper offers a discussion on where our efforts should be put to further reduce losses due to rebound and increase in-place shotcrete homogeneity to promote strength and durability
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