1,720,975 research outputs found
Efficient control-oriented modelling of heterogeneous large-scale computer cooling systems
No full textThe power of modern computing equipment, from small devices such as laptops through a variety of cases up to entire data centres, makes cooling vital. Especially in large-scale systems, delivering the right cooling to the right place at the right time is crucial for both computing performance and energy efficiency. As such, modern cooling systems require a lot of controls. Given the many cases to face, designing and assessing such controls requires tools to rapidly and modularly build and manage computationally efficient simulation models, sometimes concentrating on the thermal policies aboard on a chip, sometimes on the cooling of a rack, sometimes on an entire date centre with its fluid conditioning and transport machinery, and so forth. Though technology exist to address many such cases individually, a holistic approach to embrace them all within a unified modelling methodology and workflow is still the subject of research. In this paper we distil our experience over the last years, and discuss how a solution based on joining purpose-specific chip modelling (using the 3D-ICE simulator) and Equation-Based Object-Oriented Modelling (employing the Modelica language) can help the joint design of a computing system and its cooling
Wireless synchronisation as a control problem embedded in new-generation networked automation systems
Full text linkIn the present and rapidly evolving industrial scenario, wireless networked controls are gaining importance. This brings about new problems concerning the use of the radio channel, as well as the energy efficiency of the involved devices (often running on battery). We argue that such problems, among which a fundamental one is clock synchronisation, should be addressed by dedicated control structures embedded in the used hardware/software architecture, and that the construction of the said controls should follow strictly system-theoretical principles to the maximum extent. In this paper, building on previous experience, we present such a synchronisation solution together with a formal model for its operation, also accounting for non-idealities in the reference time base. Some experimental results are reported to support the statements made
A Multitransmission Event-Based Architecture for Energy-Efficient Autotuning Wireless Controls
No full textWe propose a periodic event-based control scheme in which, when the sensor triggers an event, also past and subsequent values of the controlled variable are transmitted. We employ this idea to obtain a stability condition independent of the used event-triggering mechanism. In turn, we exploit this independence to devise a methodology for extending existing controller (auto)tuning rules to the event-based setting and provide an example with the internal model control PID (IMC-PID) rule. We then abstract the functionalities that a wireless sensor node has to offer for implementing our scheme and finally present such a node, physically realized in a completely hardware-based form to the advantage of both energy efficiency and security. Simulations results and experiments with the so-obtained control architecture (wireless sensor node plus event-based IMC-PID) are reported
Odierne possibilità cliniche di valutazione dell'indice di rischio per il danno radioterapico tardivo
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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