Synchronization Algorithms for Multi-cores and Multiprocessors

A distributed system is a group of processors that do not allocate memory. As an alternative, each processor has its own local memory, and the processors communicate with one another through communication lines such as local-area or wide-area networks. The processors in a distributed system vary in size and function. Such systems may include small handheld or real-time devices, personal computers, workstations, and large mainframe computer systems. Distributed systems, will have their own set of unique challenges, including synchronizing data and creating sense of conflicts. Effective synchronization algorithms performance depends on runtime factors that are rigid to predict. The designers have protocols to employ the synchronization operation and waiting mechanisms to wait for synchronization delays. In this paper an effort is made to investigate synchronization algorithm that vigorously select waiting mechanisms and protocols in response to runtime factors so as to attain enhanced performance. DOI: 10.17762/ijritcc2321-8169.150615

A software architecture for consensus based replication

Orientador: Luiz Eduardo BuzatoTese (doutorado) - Universidade Estadual de Campinas, Instituto de ComputaçãoResumo: Esta tese explora uma das ferramentas fundamentais para construção de sistemas distribuídos: a replicação de componentes de software. Especificamente, procuramos resolver o problema de como simplificar a construção de aplicações replicadas que combinem alto grau de disponibilidade e desempenho. Como ferramenta principal para alcançar o objetivo deste trabalho de pesquisa desenvolvemos Treplica, uma biblioteca de replicação voltada para construção de aplicações distribuídas, porém com semântica de aplicações centralizadas. Treplica apresenta ao programador uma interface simples baseada em uma especificação orientada a objetos de replicação ativa. A conclusão que defendemos nesta tese é que é possível desenvolver um suporte modular e de uso simples para replicação que exibe alto desempenho, baixa latência e que permite recuperação eficiente em caso de falhas. Acreditamos que a arquitetura de software proposta tem aplicabilidade em qualquer sistema distribuído, mas é de especial interesse para sistemas que não são distribuídos pela ausência de uma forma simples, eficiente e confiável de replicá-losAbstract: This thesis explores one of the fundamental tools for the construction of distributed systems: the replication of software components. Specifically, we attempted to solve the problem of simplifying the construction of high-performance and high-availability replicated applications. We have developed Treplica, a replication library, as the main tool to reach this research objective. Treplica allows the construction of distributed applications that behave as centralized applications, presenting the programmer a simple interface based on an object-oriented specification for active replication. The conclusion we reach in this thesis is that it is possible to create a modular and simple to use support for replication, providing high performance, low latency and fast recovery in the presence of failures. We believe our proposed software architecture is applicable to any distributed system, but it is particularly interesting to systems that remain centralized due to the lack of a simple, efficient and reliable replication mechanismDoutoradoSistemas de ComputaçãoDoutor em Ciência da Computaçã

Proceedings of the 22nd Conference on Formal Methods in Computer-Aided Design – FMCAD 2022

The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing

Proceedings of the 22nd Conference on Formal Methods in Computer-Aided Design – FMCAD 2022

The Conference on Formal Methods in Computer-Aided Design (FMCAD) is an annual conference on the theory and applications of formal methods in hardware and system verification. FMCAD provides a leading forum to researchers in academia and industry for presenting and discussing groundbreaking methods, technologies, theoretical results, and tools for reasoning formally about computing systems. FMCAD covers formal aspects of computer-aided system design including verification, specification, synthesis, and testing

Proceedings of the 1st International Conference on Live Coding

Open Access peer reviewed papers on live coding published at the 1st International Conference on Live Coding (ICLC) in Leeds

Anonymous Stabilizing Leader Election using a Network Sequencer ∗

In this paper, we present an anonymous, stable, communication efficient, stabilizing leader election algorithm that works using anonymous communication primitives. The algorithm offers properties similar to that of the Ω failure detector, with the added property of totally ordering the sequence of proposed leaders. The algorithm does not need to know beforehand the identity or the number of processes in the system, and operates using a constant amount of memory. We present the algorithm, discuss performance issues and optimizations and present experimental results of a prototype implementation

Electric field imaging

Thesis (Ph.D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts & Sciences, 1999.Includes bibliographical references (p. 213-216).The physical user interface is an increasingly significant factor limiting the effectiveness of our interactions with and through technology. This thesis introduces Electric Field Imaging, a new physical channel and inference framework for machine perception of human action. Though electric field sensing is an important sensory modality for several species of fish, it has not been seriously explored as a channel for machine perception. Technological applications of field sensing, from the Theremin to the capacitive elevator button, have been limited to simple proximity detection tasks. This thesis presents a solution to the inverse problem of inferring geometrical information about the configuration and motion of the human body from electric field measurements. It also presents simple, inexpensive hardware and signal processing techniques for making the field measurements, and several new applications of electric field sensing. The signal processing contribution includes synchronous undersampling, a narrowband, phase sensitive detection technique that is well matched to the capabilities of contemporary microcontrollers. In hardware, the primary contributions are the School of Fish, a scalable network of microcontroller-based transceive electrodes, and the LazyFish, a small footprint integrated sensing board. Connecting n School of Fish electrodes results in an array capable of making heterodyne measurements of any or all n(n - 1) off-diagonal entries in the capacitance matrix. The LazyFish uses synchronous undersampling to provide up to 8 high signal-to-noise homodyne measurements in a very small package. The inverse electrostatics portion of the thesis presents a fast, general method for extracting geometrical information about the configuration and motion of the human body from field measurements. The method is based on the Sphere Expansion, a novel fast method for generating approximate solutions to the Laplace equation. Finally, the thesis describes a variety of applications of electric field sensing, many enabled by the small footprint of the LazyFish. To demonstrate the School of Fish hardware and the Sphere Expansion inversion method, the thesis presents 3 dimensional position and orientation tracking of two hands.by Joshua Reynolds Smith.Ph.D

LIPIcs, Volume 251, ITCS 2023, Complete Volume

LIPIcs, Volume 251, ITCS 2023, Complete Volum

Computer Aided Verification

This open access two-volume set LNCS 10980 and 10981 constitutes the refereed proceedings of the 30th International Conference on Computer Aided Verification, CAV 2018, held in Oxford, UK, in July 2018. The 52 full and 13 tool papers presented together with 3 invited papers and 2 tutorials were carefully reviewed and selected from 215 submissions. The papers cover a wide range of topics and techniques, from algorithmic and logical foundations of verification to practical applications in distributed, networked, cyber-physical, and autonomous systems. They are organized in topical sections on model checking, program analysis using polyhedra, synthesis, learning, runtime verification, hybrid and timed systems, tools, probabilistic systems, static analysis, theory and security, SAT, SMT and decisions procedures, concurrency, and CPS, hardware, industrial applications

"Hispano-Lusophone" community media : identity, cultural politics and difference

In recent years, the issue of identity has been the subject of an intensive analysis across different fields and disciplines. Indeed, in an era of accelerated social and technological changes under the phenomenon of globalization, with the rapid internationalization and expansion of urban centres across the world, this is of little surprise. According to Lyotard (2006), these sweeping changes have set a crucial moment in a much longer process of displacement, through which dominant narratives, traditions and structures have progressively lost their historic power. As a part of this social reconfiguration, institutions have dematerialized, while beliefs, traditions and cultural practices have gained flexibility through rapid and frequent changes. In such a context, we witness the advent of a new subject, whose identity is no longer fixed, as well as the development of new forms of inequality, as it all converges to modify the contemporary social and political landscape. In these terms, Arjun Appadurai (1996) uses the expression "global cultural economy" to describe the myriad of cultural meeting points and flows underpinning this new modern, globalized world. As the author explains, "the new global cultural economy has to be seen as a complex, overlapping, disjunctive order that cannot any longer be understood in terms of existing centre-periphery models" (Appadurai, 1996:32). Indeed, the ongoing renegotiation and traversal of traditional borders point towards a multiplicity of new, non-monolithic membership forms: collectivities in which the local and the global, as experiential entities, are intimately intertwined (Featherstone & Lash, 2002). With this in mind, we have operationalized the concept of 'multi-territoriality' as a guide for this book. Such an expression, initially proposed by Haesbaert (1994) but further developed by Augé (1995), Albagli and Maciel (2010), refers to the intensification of multiple territorial re-imaginings and repossessions. In this context, displacement does not mean the abandonment of already established territorial references, but rather the addition of new references, which come together to form a complex matrix of feelings of belonging and ownership, towards a multiplicity of places and spaces. The intense flow of people and information appears pivotal to this panorama. Hence, the proliferation of 'differences' establishes a strategic space for intervention, which goes beyond and onto a broader, non-universalizing understanding of culture. In this process, the differences and experiences are taken into consideration, creating the basic conditions for societies to be transformed and improved. One of the most notable consequences of these shifts is the current social reconfiguration, with the consequent surfacing of groups that were previously marginalized. Indeed, these groups find themselves now able to capitalize on new flows of information, communication and expertise. Consequently, novel social categories and relations of belonging are forged, extending both within and across national boundaries (Santos & Rodríguez, 2003). Inspired by the idea of 'territory' as a cultural construct, created, contested and transformed in various ways by media technologies (Canclini, 2001; Appadurai, 2001; Haesbaert, 1994), the works collected in this edition span and explore several of the community media projects, parts of a 'space'1 named the 'Hispano-Lusophone' sphere. By mapping and exploring the creative and intellectual production in the context of the Hispano-Lusophone imaginary, this project consciously endeavours to disarm and overturn certain cultural and raced hierarchies within the global knowledge production. Its authors come from a large array of professional backgrounds: they have worked intensively to overcome the significant linguistic and geographical barriers to intellectual collaboration. In this respect, the authors draw into critical examination the established frontiers of knowledge production, as well as the main agents and processes that create and legitimate those borders