9,517 research outputs found

    Approximate Computing Survey, Part I: Terminology and Software & Hardware Approximation Techniques

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    The rapid growth of demanding applications in domains applying multimedia processing and machine learning has marked a new era for edge and cloud computing. These applications involve massive data and compute-intensive tasks, and thus, typical computing paradigms in embedded systems and data centers are stressed to meet the worldwide demand for high performance. Concurrently, the landscape of the semiconductor field in the last 15 years has constituted power as a first-class design concern. As a result, the community of computing systems is forced to find alternative design approaches to facilitate high-performance and/or power-efficient computing. Among the examined solutions, Approximate Computing has attracted an ever-increasing interest, with research works applying approximations across the entire traditional computing stack, i.e., at software, hardware, and architectural levels. Over the last decade, there is a plethora of approximation techniques in software (programs, frameworks, compilers, runtimes, languages), hardware (circuits, accelerators), and architectures (processors, memories). The current article is Part I of our comprehensive survey on Approximate Computing, and it reviews its motivation, terminology and principles, as well it classifies and presents the technical details of the state-of-the-art software and hardware approximation techniques.Comment: Under Review at ACM Computing Survey

    Beam scanning by liquid-crystal biasing in a modified SIW structure

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    A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium

    AN EMPIRICAL STUDY OF CONCURRENT FEATURE USAGE IN GO

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    The Go language includes support for running functions or methods concurrently as goroutines, which are lightweight threads managed directly by the Go language runtime. Go is probably best known for the use of a channel-based, message-passing concurrency mechanism, based on Hoare's Communicating Sequential Processes (CSP), for inter-thread communication. However, Go also includes support for traditional concurrency features, such as mutexes and condition variables, that are commonly used in other languages. In this paper, we analyze the use of these traditional concurrency features, using a corpus of Go programs used in earlier work to study the use of message-passing concurrency features in Go. The goal of this work is to better support developers in using traditional concurrency features, or a combination of traditional and message-passing features, in Go

    Modelling, Monitoring, Control and Optimization for Complex Industrial Processes

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    This reprint includes 22 research papers and an editorial, collected from the Special Issue "Modelling, Monitoring, Control and Optimization for Complex Industrial Processes", highlighting recent research advances and emerging research directions in complex industrial processes. This reprint aims to promote the research field and benefit the readers from both academic communities and industrial sectors

    Multi-scale computer models of lymphatic pumping

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    The lymphatic system maintains fluid homeostasis by returning interstitial fluid to the veins. Lymphatics pump fluid locally with contracting segments of the vessel (lymphangions) bounded by valves. Contractions are generated by specialized muscle exhibiting phasic and tonic contractions. Deficient pumping can result in accumulation of interstitial fluid, called lymphoedema. Lymphoedema treatments have limited effectiveness, partially attributable to a lack of understanding of contractions. A lumped parameter computational model of lymphangion pumping has previously been developed in the group. In this thesis I detail development of two multiscale models of lymphatic pumping to facilitate improved treatments for lymphoedema. The first model captures subcellular mechanisms of lymphatic muscle contraction. This model is based on the sliding filament model and its smooth muscle adaptation. Contractile elements are combined with passive viscoelastic elements to model a cell. Many arrangements were trialled but only one behaved physiologically. The muscle model was then combined with the lymphangion model for comparison with experiments. This model captures mechanical and energetic aspects of both contraction types. I show that the model provides results similar to published experiments from rat mesenteric lymphatics. The model predicted a peak efficiency of 35%, in the upper range from other muscle types. In the range of frequencies and amplitudes simulated, the direct effect of calcium oscillations can increase lymphangion outflow by up to 40% of the flow in their absence. The second model aims to improve our understanding of lymphangion interaction in large networks through computational homogenisation. In this model we do not directly simulate all lymphangions but sample lymphangions at evenly spaced intervals to reduce the computational intensity. We show through this model that increased external pressure at the network inlet collapses lymphangions and that this disruption of pumping for a few lymphangions reduces the outflow from the entire network.Open Acces

    CITIES: Energetic Efficiency, Sustainability; Infrastructures, Energy and the Environment; Mobility and IoT; Governance and Citizenship

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    This book collects important contributions on smart cities. This book was created in collaboration with the ICSC-CITIES2020, held in San José (Costa Rica) in 2020. This book collects articles on: energetic efficiency and sustainability; infrastructures, energy and the environment; mobility and IoT; governance and citizenship

    Cellular Senescence in Health, Disease and Aging: Blessing or Curse?

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    Dear Colleagues, When Hayflick and Moorhead coined the term “cellular senescence” (CS) almost 60 years ago, this phenomenon was understood as a mechanism, usually induced by activation of the DNA-repair machinery, to prevent uncontrolled proliferation. Meanwhile, additional beneficial roles for CS have been identified, such as embryonic development and wound healing. The senescence associated secretory phenotype (SASP) activated in most senescent cells (SC) signals to the immune system “come here and remove me”. In organisms with young and functional immune systems, occurring SC are usually detected and removed. If SC remain in the tissue expressing the SASP, this will cause not just a damaging local inflammation but can also induce remodeling and regeneration of the surrounding tissue as well as spreading of senescence. Old organisms show reduced regenerative potential and immune function which leads to accumulation of SC. Accordingly, accumulation of SC was observed in tissues of aged individuals, but importantly also in the context of age-related disorders, neurodegenerative, or cardiovascular diseases and others. Because of its detrimental effect of the surrounding tissue, accumulation of SC is not just a consequence, but can rather been understood as a major driver of aging. In line with this, recent studies described that removal of SC showed beneficial effects on healthspan and lifespan. This exciting research led to the discovery of “senolytics”, drugs which can kill SC. Given the heterogeneity of cell types that show senescence-like phenotypes, including heart muscle and post-mitotic neuronal cells, further research is required to unravel the molecular background that renders a cell type vulnerable to senesce. Additionally, it will be important to understand how senescence is cell type-specifically induced and which molecules serve as drug targets to prevent senescence and its spreading, or actively kill SC. This special issue will shed light on the molecular pathways of CS and inflammaging and on possible strategies to interfere with these processes. Dr. Markus Riessland Guest Edito
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