Search results for "Asynchronous communication"
showing 10 items of 65 documents
A Web-Based Coordination Infrastructure for Grid Collective Services
2004
Virtual Organizations (VO) consisting of heterogeneous institutions and individuals that share resources dynamically and in a coordinated way to support collaborative problem-solving are emerging in many fields. Consequently, new types of distributed infrastructures known as Grids have been proposed to cope with these new sharing requirements. Grids offer sets of collective services to support collaborative tasks which are distributed in nature and need asynchronous communication. Existing approaches to this problem lack of flexibility, adaptability and are tightly bound to the collective service that is provided. We present here a generic event model to build collective services that requi…
3D Map Computation from Historical Stereo Photographs of Florence
2018
The analysis of early photographic sources is fundamental for documenting and understanding the evolution of a city so rich in history and art as Florence. Indeed, by the 1860s several photographers used to work in town, and their images (often obtained through stereoscopic set-ups) can help us to reconstruct Florence in 3D as it was by the time of the Italian unification. The first and most delicate part of such reconstruction process is the computation of disparity maps from the historical stereo pairs. This is a very challenging task for fully-automatic computer vision algorithms, since XIX century photographs are affected by several problems—ranging from superficial damages to asynchron…
Asynchronously switched control of discrete impulsive switched systems with time delays
2013
This paper is concerned with the stabilization problem for a class of uncertain discrete impulsive switched delay systems under asynchronous switching. The so-called asynchronous switching means that the switches between the candidate controllers and system modes are asynchronous. By using the average dwell time (ADT) approach, sufficient conditions for the existence of an asynchronously switched controller is derived such that the resulting closed-loop system is exponentially stable. The desired controller gains and the admissible switching signals are obtained in terms of a set of matrix inequalities. A numerical example is given to illustrate the effectiveness of the proposed method.
A simple timestamping data acquisition system for ToF-ERDA
2015
A new data acquisition system, ToF-DAQ, has been developed for a ToF-ERDA telescope and other ToF-E and ToF-ToF measurement systems. ToF-DAQ combines an analogue electronics front-end to asynchronous time stamped data acquisition by means of a FPGA device. Coincidences are sought solely in software based on the timestamps. Timestamping offers more options for data analysis as coincidence events can be built also in offline analysis. The system utilises a National Instruments R-series FPGA device and a Windows PC as a host computer. Both the FPGA code and the host software were developed using the National Instruments LabVIEW graphical programming environment. Up to eight NIM ADCs can be han…
Visual spike-based convolution processing with a Cellular Automata architecture
2010
this paper presents a first approach for implementations which fuse the Address-Event-Representation (AER) processing with the Cellular Automata using FPGA and AER-tools. This new strategy applies spike-based convolution filters inspired by Cellular Automata for AER vision processing. Spike-based systems are neuro-inspired circuits implementations traditionally used for sensory systems or sensor signal processing. AER is a neuromorphic communication protocol for transferring asynchronous events between VLSI spike-based chips. These neuro-inspired implementations allow developing complex, multilayer, multichip neuromorphic systems and have been used to design sensor chips, such as retinas an…
AER Filtering Using GLIDER: VHDL Cellular Automata Description
2008
Cellular Automata (CA) is a bio-inspired processing model for problem solving, initially proposed by Von Neumann. This approach modularizes the processing by dividing the solution into synchronous cells that change their states at the same time in order to get the solution. The communication between them is crucial to achieve the correct solution. On the other hand, the Address-Event-Representation (AER) is a neuromorphic communication protocol for transferring asynchronous events between VLSI chips. These neuro-inspired implementations have been used to design sensor chips (retina, cochleas), processing chips (convolutions, filters) and learning chips, which makes it possible to develop co…
Link scheduling in sensor networks for asymmetric average consensus
2012
Wireless Sensor Networks constitute a recent technology where the nodes cooperate to obtain, in a totally distributed way, certain function of the sensed data. One example is the average consensus algorithm, which allows every node to converge to the global average. However, this algorithm presents two major drawbacks in practice. The first one is that instantaneous symmetric links are required, which are hard to ensure in practice because of the presence of wireless interferences. The second one is that all the nodes are required to communicate with all of their local neighbors in every iteration, which can lead to an unbounded delay. In order to solve these issues, we propose a novel link…
“Nice to get to know you”
2020
Virtual exchange comprises online collaborative activities in facilitated, educational contexts across borders. This paper offers a multimodal approach to the study of social presence in students’ asynchronous online discourse in the context of virtual exchange. It draws on the Community of Inquiry model of online learning (Garrison 2017) and interprets social presence as the dynamic discursive process of social interaction and self-presentation. The data consists of screenshots collected in a closed Facebook group during the first assignment of a Czech-Finnish virtual exchange project in 2017. The study aims to explore how the method of multimodal discourse analysis can be used to describe…
Role Scripting as a Tool to Foster Transactivity of Asynchronous Student Discussions
2021
Transactivity of student discussions is crucial in computer-supported collaborative learning (CSCL). However, CSCL learners often lack well-developed argumentation and negotiation skills, which makes it challenging for them to engage in and maintain a transactive discussion. Collaboration scripts have been implemented in CSCL contexts and have demonstrated positive effects on students' collaboration and argumentation skills. Yet, the degree of transactivity of student interactions is rarely addressed directly in CSCL research. Employing a qualitative content analysis approach, this study seeks to understand how a role script affects the transactivity of students' argumentative knowledge co-…
Diferencias de sexo en estrategias de aprendizaje de estudiantes online.
2018
Analizamos aquí las estrategias de aprendizaje empleadas por estudiantes universitarios, de modalidad online, en función del género. En primer lugar, se realiza una exhaustiva revisión de publicaciones que comparten el objeto de estudio, la mayoría de ellas difundidas en la última década y señalando los principales hallazgos de estas investigaciones. El objetivo del estudio es analizar tanto las estrategias empleadas como desvelar semejanzas y diferencias con respecto a modalidades presenciales. Metodológicamente optamos por realizar un diseño multimétodo, en el que el análisis cualitativo tiene como finalidad contribuir a la evaluación e interpretación de los resultados de tipo cuantitativ…