1,721,116 research outputs found
An object oriented approach in building an environment for simulation and analysis based on timed Petri nets with multiple execution policies
No full textThe paper describes a programming environment based on the timed Petri net paradigm with generally distributed transition firing times and with several execution policies. The user interaction is supported by a X Window-based graphical interface. The graphical editor, which allows both bottom-up and top-down modeling, is based on a hierarchy (toolkit) of graphical objects (widgets). A discrete-event simulator is provided: it is composed by a set of basic simulation objects assembled from the model description. A simulator prototype has been developed using the C++ programming language
Automatic Verification for a class of distributed systems
No full textThe paper presents a new analysis method for a class of concurrent systems which are formed of several interacting components with the same structure. The model for these systems is composed of a control process and a set of homogeneous user processes. The control and user processes are modeled by finite labeled state transition systems which interact by means of enabling functions and triggering mechanisms. Based on this structure, an analysis method is presented which allows system properties, derived by reachability analysis for a finite number of user processes, to be generalized to an arbitrary number of user processes. A procedure for the automatic verification of properties such as mutual exclusion and absence of deadlocks is presented and is then used to provide for the first time a fully automated verification of the Lamport's fast mutual exclusion algorithm
Virtualization of accelerators in embedded systems for mixed-criticality: RPU exploitation for fusion diagnostics and control
No full textThe need for computing systems featuring high performance, safety, security, and predictability requirements, has become essential for fusion diagnostics and control. In this scenario, the next-generation Multiprocessors System-On-Chip (MPSoCs) characterized by modern processors and hardware accelerators can expand the potential of control infrastructure. To enhance the usability, performance, and dependability of these new technologies and to reduce the deployment cost, the concept of virtualization sees its first application in embedded systems. This work aims to propose three high-level architectural solutions that leverage virtualization to exploit accelerators and Real-Time Processing Units (RPUs) present on MPSoCs to realize Mixed-Criticality Systems (MCSs). That is, systems capable to manage on a single chip real-time tasks for critical automatic control together with other value-added services on the same hardware. The problems to be solved to implement these proposals will be explained in detail to guide future works. To highlight the potential of virtualization for real-time embedded systems in fusion science scenarios we explore some use cases regarding Vertical Stabilization (VS) algorithms for plasma magnetic control that can benefit from the proposed solutions
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
Virtualization of accelerators in embedded systems for mixed-criticality: RPU exploitation for fusion diagnostics and control
No full textThe need for computing systems featuring high performance, safety, security, and predictability requirements, has become essential for fusion diagnostics and control. In this scenario, the next-generation Multiprocessors System-On-Chip (MPSoCs) characterized by modern processors and hardware accelerators can expand the potential of control infrastructure. To enhance the usability, performance, and dependability of these new technologies and to reduce the deployment cost, the concept of virtualization sees its first application in embedded systems. This work aims to propose three high-level architectural solutions that leverage virtualization to exploit accelerators and Real-Time Processing Units (RPUs) present on MPSoCs to realize Mixed-Criticality Systems (MCSs). That is, systems capable to manage on a single chip real-time tasks for critical automatic control together with other value-added services on the same hardware. The problems to be solved to implement these proposals will be explained in detail to guide future works. To highlight the potential of virtualization for real-time embedded systems in fusion science scenarios we explore some use cases regarding Vertical Stabilization (VS) algorithms for plasma magnetic control that can benefit from the proposed solutions
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
Distributed Continuous Event-Based Data Acquisition Using the IEEE 1588 Synchronization and FlexRIO FPGA
No full textHigh-speed event driven acquisition is normally performed by analog-to-digital converter (ADC) boards with a given number of pretrigger sample and posttrigger sample that are recorded upon the occurrence of a hardware trigger. A direct physical connection is, therefore, required between the source of event (trigger) and the ADC, because any other software-based communication method would introduce a delay in triggering that would turn out to be not acceptable in many cases. This paper proposes a solution for the relaxation of the event communication time that can be, in this case, carried out by software messaging (e.g., via an LAN), provided that the system components are synchronized in time using the IEEE 1588 synchronization mechanism. The information about the exact event occurrence time is contained in the software packet that is sent to communicate the event and is used by the ADC FPGA to identify the exact sample in the ADC sample queue. The length of the ADC sample queue will depend on the maximum delay in software event message communication time. A prototype implementation using a National FlexRIO FPGA board connected with an ADC device is presented as the proof of concept
Big data requirements in current and next fusion research experiments
No full textThe present and future data management requirements for fusion experiments are presented along with the currently adopted solutions. Even if the presented solution fulfil the requirements of the current experiments, the next generation fusion devices are likely to produce/require an unpreceded amount of data. For this reason, the solutions adopted nowadays, and also foreseen for the experiments under construction, might prove not enough scalable. Information Technology already provides efficient solutions for big data management, successfully employed for large cloud applications and social media. In particular, MongoDB, Cassandra and Hadoop represent promising candidates for the next generation experiments because their combined usage covers the specific data requirements for fusion research
- …
