pinecone/core-2020-05-10-deduplication huggingface dataset:
Roaring Bitmaps: Implementation of an Optimized Software Library

Compressed bitmap indexes are used in systems such as Git or Oracle to
accelerate queries. They represent sets and often support operations such as
unions, intersections, differences, and symmetric differences. Several
important systems such as Elasticsearch, Apache Spark, Netflix's Atlas,
LinkedIn's Pivot, Metamarkets' Druid, Pilosa, Apache Hive, Apache Tez,
Microsoft Visual Studio Team Services and Apache Kylin rely on a specific type
of compressed bitmap index called Roaring. We present an optimized software
library written in C implementing Roaring bitmaps: CRoaring. It benefits from
several algorithms designed for the single-instruction-multiple-data (SIMD)
instructions available on commodity processors. In particular, we present
vectorized algorithms to compute the intersection, union, difference and
symmetric difference between arrays. We benchmark the library against a wide
range of competitive alternatives, identifying weaknesses and strengths in our
software. Our work is available under a liberal open-source license
Towards Linux Kernel Memory Safety

The security of billions of devices worldwide depends on the security and
robustness of the mainline Linux kernel. However, the increasing number of
kernel-specific vulnerabilities, especially memory safety vulnerabilities,
shows that the kernel is a popular and practically exploitable target. Two
major causes of memory safety vulnerabilities are reference counter overflows
(temporal memory errors) and lack of pointer bounds checking (spatial memory
errors).
  To succeed in practice, security mechanisms for critical systems like the
Linux kernel must also consider performance and deployability as critical
design objectives. We present and systematically analyze two such mechanisms
for improving memory safety in the Linux kernel: (a) an overflow-resistant
reference counter data structure designed to accommodate typical reference
counter usage in kernel source code, and (b) runtime pointer bounds checking
using Intel MPX in the kernel
JAC: An Aspect-Based Distributed Dynamic Framework

International audienceIn this paper, we present the Java Aspect Components (JAC) framework for building aspect-oriented distributed applications in Java. This paper describes the aspect-oriented programming model and the architectural details of the framework implementation. The framework enables extension of application semantics for handling well-separated concerns. This is achieved with a software entity called an aspect component (AC). ACs provide distributed pointcuts, dynamic wrappers and metamodel annotations. Distributed pointcuts are a key feature of our framework. They enable the definition of crosscutting structures that do not need to be located on a single host. ACs are dynamic. They can be added, removed, and controlled at runtime. This enables our framework to be used in highly dynamic environments where adaptable software is needed
An illustrative example of refactoring object-oriented source code with aspect-oriented mechanisms

This paper describes a refactoring process that transforms a Java source code base into a functionally equivalent AspectJ source code base. The process illustrates the use of a collection of refactorings for aspect-oriented source code, covering the extraction of scattered implementation elements to aspects, the internal reorganization of the extracted aspects and the extraction of commonalities to super-aspects.Fundo Europeu de Desenvolvimento Regional (FEDER) - POSC/EIA/60189/2004Fundação para a Ciência e a Tecnologia (FCT
AQuoSA-adaptive quality of service architecture

This paper presents an architecture for Quality of Service (QoS) control of time- sensitive applications in multi-programmed embedded systems. In such systems, tasks must receive appropriate timeliness guarantees from the Operating System independently from one another, otherwise the QoS experienced by users may decrease. Moreover, fluctuations in time of the workloads make a static partitioning of the CPU not appropriate nor convenient, whereas an adaptive allocation based on an on-line monitoring of the application behaviour leads to an optimum design. By combining a resource reservation scheduler and a feedback based mechanism, we allow applications to meet their QoS requirements with the minimum possible impact on CPU occupation. We implemented the framework in AQuoSA [8], a software architecture that runs on top of the Linux kernel.We provide extensive experimental validation of our results and offer evaluation of the introduced overhead, which is perfectly sustainable in the class of addressed applications
AQuoSA - adaptive quality of service architecture

This paper presents an architecture for quality of service (QoS) control of time-sensitive applications in multi-programmed embedded systems. In such systems, tasks must receive appropriate timeliness guarantees from the operating system independently from one another; otherwise, the QoS experienced by the users may decrease. Moreover, fluctuations in time of the workloads make a static partitioning of the central processing unit (CPU) that is neither appropriate nor convenient, whereas an adaptive allocation based on an on-line monitoring of the application behaviour leads to an optimum design. By combining a resource reservation scheduler and a feedback-based mechanism, we allow applications to meet their QoS requirements with the minimum possible impact on CPU occupation. We implemented the framework in AQuoSA (Adaptive Quality of Service Architecture (AQuoSA). http://aquosa.sourceforge.net), a software architecture that runs on top of the Linux kernel. We provide extensive experimental validation of our results and offer an evaluation of the introduced overhead, which is perfectly sustainable in the class of addressed applications
ISO/IEC 15504 - Evolution to an International Standard

This article describes the work currently being undertaken to help ISO/IEC TR 15504 progress to the status of a full International Standard, and outlines the changes in design that are to be incorporated in the revision. It describes the inputs for the design decisions that were taken; identifies the fundamental changes in the architecture of the Standard; and briefly describes the current status of the development of the Standard.Griffith Sciences, School of Information and Communication TechnologyFull Tex
Agent-based simulation of open source evolution

We present an agent-based simulation model developed to study how size, complexity and effort relate to each other in the development of open source software (OSS). In the model, many developer agents generate, extend, and re-factor code modules independently and in parallel. This accords with empirical observations of OSS development. To our knowledge, this is the first model of OSS evolution that includes the complexity of software modules as a limiting factor in productivity, the fitness of the software to its requirements, and the motivation of developers. \ud
Validation of the model was done by comparing the simulated results against four measures of software evolution (system size, proportion of highly complex modules, level of complexity control work, and distribution of changes) for four large OSS systems. The simulated results resembled the observed data, except for system size: three of the OSS systems showed alternating patterns of super-linear and sub-linear growth, while the simulations produced only super-linear growth. However, the fidelity of the model for the other measures suggests that developer motivation and the limiting effect of complexity on productivity have a significant effect on the development of OSS systems and should be considered in any model of OSS development
Improving Performance and Fostering Accountability in the Public Sector through System Dynamics Modelling From an ‘external’ to an ‘internal’ perspective

This paper aims to outline the benefits justifying a tailored approach to System Dynamics (SD) modelling in the public sector, to improve performance and foster decision makers' accountability. The need of combining an internal with an external perspective (in respect to decision makers) in developing SD models is claimed. Different levels of intervention (i.e. macro, micro and meso) are discussed. Two case studies are analysed. The first one demonstrates how a dynamic resource-based view (DRBV) can support an analysis of the impact of back and front office units on a public sector organization's performance drivers. The second case shows how SD modelling based on a DRBV can also be applied to improve performance on a political leve
Towards a Methodology of Wicked Problem Exploration through Concept Shifting and Tension Point Analysis

Synthesis is a creative and mysterious process in which a chaotic array of concepts, what might be called a mess, is cognitively 'engaged' with a problem domain to produce as many interpretations as can validly be derived for effective decision-making purposes.   The bene?ts of engaging concepts into a mess are that it allows the problem to be viewed through multiple lenses simultaneously, which affords a holistic vantage point for richer problem interpretation. By deliberately shifting the underlying concept held by actors and provoking the movement of concepts, better interpretations might lead to more useful decision making. Although research has discussed the possibility of using synthesis through case studies, we argue that there is a need to formally develop methodologies in this area for the purpose of fostering and solving complex problems. To demonstrate this, we provide a speculative case study to illustrate how this approach may be usefully applied.Griffith Business School, Department of International Business and Asian StudiesFull Tex
Critical mass and discontinued use of social media

Using simulation, this study compares a critical mass of adopters with a critical mass of those who discontinue their adoption of social media. A network of reflex agents is simulated where each agent has an unchanging threshold and will adopt social media if the number of their friends who have adopted is greater than it. In the first study, the size of the critical mass that adopts is varied, and in the second, the size of the critical mass that discontinues use is varied. The studies show that a critical mass of leavers can cause a community to fail and that this mass can potentially be as small as that needed to influence a community to succeed; although given a certain critical mass, their leaving is less likely to cause failure than their adoption is success. This influence of the critical mass is facilitated by network structure
Modelling the emergence of shared attitudes from group dynamics using an agent-based model of social comparison theory

We propose a novel agent-based implementation of Festinger’s social comparison theory (SCT). The social comparison model (SCM) consists of connectionist networks that simu- late agent-level social comparison processes. Agent networks are combined into an adap- tive network structure that is shaped by social comparisons between individual agents. Simulations show how the SCM produces behavior consistent with the empirical litera- ture on group dynamics. In addition, experimental results are reported that show how the SCM can simulate how critical and conformist norms affect interpersonal processes and emergent attitudes. We conclude that the coupling of simulations and experiments, and the use of psychologically plausible agent models within adaptive network struc- tures, can provide new impetus to the development of models of individual and social cognition. An integrated framework such as the SCM allows investigating key theoretical predictions around the origin and maintenance of socially shared information through so- cial comparisons in fundamentally novel ways
Temporal Events and Problem Structuring

Problems come with a history and sometimes an assumed future. Our understanding of the past and our assumptions of the future shape the way we structure problems. In this paper, we explore how the past and the future might influence temporality in problem structuring and identify the utility of linkage theory in providing temporal understanding. Data for this paper are derived from trade treaty negotiations conducted by the USA and Singapore (2000–2003), Australia and Singapore (2000–2003) and Australia and the USA (2003–2004). These three negotiations, occurring concurrently or consecutively in time, allow us to examine a temporal quality to problem-structuring through linkage theory. This study enriches our understanding of the problem-structuring methods literature by focusing on how temporal issues play a role in how problems are structured. The negotiation context described earlier is used as an exemplar of how temporal issues affect problem structuring. Our aim is to begin a discussion on how and if a temporal perspective can be handled methodologically.Griffith Business School, Department of International Business and Asian StudiesFull Tex
A Trusting Constructivist Approach to Systemic Inquiry: Exploring Accountability

This paper offers an outline of, and justification for, what I call a ‘trusting constructivist’
approach to systemic inquiry. I work with the constructivist view that, as Banathy puts it:
‘what we know about the world becomes projected onto the world’. That is, our
theoretical constructions and ways of thinking in relation to the world cannot be
considered separately from the impacts that they might have on the unfolding of
possibilities. Recognizing our involvement in the development of systems means that we
can reconsider—with others—the status of our own constructions as potentially
generating self-fulfilling effects. A trusting constructivist view suggests that people
cannot desist from offering their own constructions (that embody particular concerns)
in processes of inquiry (professional or otherwise). But they need to recognize the
choices that they are making as they create constructions, so that they can account for
these in relation to alternatives in social discourse, in an endeavor to earn others’ trust.ABET and Youth Developmen
Adaptive networks as second order governance systems

We connect the idea of 'levers for change' with 'governance capacity' and propose 'adaptive networks' as an ideal type embedded in, and leveraging change in, governance systems. Discourses connect practices of citizens and companies with that governance system. Aware of interdependencies, individuals may act in the interest of the whole system and self-organize into adaptive networks, and influence discourses to a common end. Their effectiveness depends on second-orderedness: adaptive networks in niches outside the governance system may influence it through levers. The motivation and competence to build creative tension helps adaptive networks emerge and coevolve with power networks, improving governance capacity
Finite element analysis of glass fiber-reinforced polyamide engine oil pan subjected to localized low velocity impact from flying projectiles

This paper investigates low velocity impact involving a glass fiber-reinforced polyamide engine oil pan as part of a complete new development of thermoplastic components. The assessment of the impact resistance has driven the need to employ LS DYNA for finite element modeling in order to benchmark and predict the strength and fracture behavior of stressed plastic parts. In order to develop a reliable predictive capability and to validate simulations, complete components were manufactured by injection molding techniques for the experimental samples. Low velocity impact investigations were carried out using a gas gun and a falling weight tester in order to simulate impact events to which the oil pan is subjected whilst in operational service. This was intended to point out damage tolerance and failure mechanisms likely to occur in the structure. The study results show the significant contribution of the design in terms of shock absorption. Specific oil pan design with protective ribbing combined with a superior material considerably improves the impact resistance. The paper provides results and discussions on experimental and finite element analysis investigations before concluding with some remarks
Digital microstructures matching statistical distributions of features in real materials - Example of forgings

International audienceVarious analytical rules of mixture are commonly used to take into account heterogeneous features of a material and to derive global properties. But, with such models, one may not be able to fulfil the requirements for separating appropriately the different lengthscales. This might be the case for some issues such as strain localisation, surface effect, or topological distributions. At an intermediate lengthscale, which we refer to as the mesoscopic scale, one can still apply continuum mechanics. So why not perform calculations using the finite element method on volumes of material to obtain the response of Representative Elementary Volumes (R.E.V.). The construction of digital microstructures for such calculations is performed in two steps. First, a series of R.E.V.s with statistics of features of real materials should be defined. Then, finite element meshes should be produced for these R.E.V.s and updated when calculations involve large strains. Powerful automatic three-dimensional mesh generators and remeshing techniques prove necessary for this latter task. This strategy is applied to create digital R.E.V.s which match statistical features of forgings. Measurements provide micromechanical parameters of each subvolume. As an example of calculations, numerical simulations provide the anisotropic fatigue properties of forgings
Effect of microstructural and morphological parameters on the formability of BCC metal sheets

The determination of forming limit strains in sheet metal forming industry is a useful way for quantifying metals in terms of formability. However, such forming limit diagrams (FLDs) remain very difficult to obtain experimentally. Therefore, the numerical prediction of forming limit strains represents a convenient alternative to replace this time consuming and expensive experimental process. Moreover, a combined theoretical-numerical model allows investigating the impact of essential microstructural aspects (e.g., initial and induced textures, dislocation density evolution, softening mechanisms, ...) and deformation mechanisms on the ductility of polycrystalline aggregates. In this paper, the impact of microstructural and morphological parameters, particularly the mean grain size, on the formability limit of BCC materials is investigated. To this end, an elastic-plastic self-consistent (EPSC) polycrystalline model, coupled with a bifurcation-based localization criterion, is adopted to numerically simulate FLDs. The FLDs thus determined using the Bifurcation-EPSC model for an IF-Ti single-phase steel are compared to the FLDs given by ArcelorMittal, demonstrating the predictive capability of the proposed approach in investigations of sheet metal formability. The role of the averaging scheme is also shown to be significant by comparing the critical limit strains predicted with the self-consistent scale-transition scheme to those obtained with the more classical full-constraint Taylor model. Finally, numerical simulations for different values of mean grain size are provided in order to analyze the impact of mean grain size on the formability of BCC metal sheets. In this study, an elastic-plastic self-consistent (EPSC) polycrystalline model is coupled with a bifurcation-based localization criterion to investigate relationships between microstructural and morphological properties and formability of single-phase BCC steels. The interest in such a combined theoretical-numerical prediction tool is to classify materials in terms of ductility and to optimize material properties or to design new grades of steel with enhanced in-use mechanical properties
Numerical Modeling of Dehydrogenation and Denitrogenation in Industrial Vacuum Tank Degassers

Hydrogen and nitrogen are inescapable elements in all commercial steel products and the presence of dissolved hydrogen and nitrogen in liquid steel can cause various problems in most of the final products. In general, the reduction of these elements in liquid steel is required in most steelmaking companies, where vacuum treatment is typically applied to remove these impurities.
The main focus of this thesis work has been put on investigating the dehydrogenation and/or denitrogenation behavior in a number of operational vacuum tank degassers (VTD) from different industrial plants. A literature review on various investigations and modeling techniques in the related field was firstly presented in this report. Based on the developed theories and methods that are relatively separate in the open literature, an integrated computational fluid dynamics (CFD) model was built to better understand the degassing process on an industrial scale and more importantly, for accurate predictions that are of considerable importance to industrial process operators.
The CFD model consists of two sub-routines for calculating multiphase flows and species transportations, respectively. The commercial CFD package of ANSYS FLUENT was adopted and augmented by various user-defined functions. As for the multiphase sub-model, the standard k-epsilon equations were extended by adding extra source terms to consider the impact of gas injections on turbulence quantities. The sub-model was validated by using literature data for an aqueous system whose similarity represented one of the industrial VTDs studied in this work. With the extended k-epsilon equations, deviations from measured data of axial liquid velocity and turbulent kinetic energy were lower than 13 % and 18 % respectively, whereas the deviations were about 30 % and 85 % with the standard equations. For mass transfer calculations, two fundamental expressions that have been commonly employed to compute mass transfer coefficient in gas-liquid systems were assessed. Comparisons with process data showed that the eddy-cell correlation provides a better prediction under the studied conditions. The versatility of the CFD model was further demonstrated by performing extensive simulations to cover the effect of gas flow rate, initial element (i.e., hydrogen and nitrogen) content and steel compositions on final element content and degassing rate. For hydrogen removal, deviations from measured data in different industrial plants were ranged between 6 % and 14 % and for nitrogen removal, the deviations were generally lower than 13 %
Usefulness of Non-Uniform Heating and Quenching Method for Residual Stress of Bimetallic Roll: FEM Simulation Considering Creep Behavior

Bimetallic rolls are widely used in steel rolling industries because of the excellent hardness, wear resistance and high temperature properties. Controlling the residual stress distribution is important to improve the roll fatigue life due to the compressive residual stress at the roll surface. Recently, to reduce the tensile residual stress appearing at the roll center, quenching heat treatment is performed just after heating the roll non-uniformly instead of heating the roll uniformly with enough time. In this paper, therefore, the residual stresses are compared after between the uniform heating quenching and the non-uniform heating quenching on the basis of the FEM simulation. The results show that tensile stresses at the roll center for non-uniform heating are smaller than that for uniform heating by 400MPa although the same compressive stresses appear at the surface. The effect of creep on stress relaxation is also considered in this study. By considering creep, the maximum tensile residual stress decreases by 8% for uniform heating and by 15% for non-uniform heating