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[en] Internet is often used for transaction based applications such as online banking, stock trading and shopping, where the service interruption or outages are unacceptable. Therefore, it is important for designers of such applications to analyze how hardware, software and performance related failures affect the quality of service delivered to the users. This paper presents analytical models for evaluating the service availability of web cluster architectures. A composite performance and availability modeling approach is defined considering various causes of service unavailability. In particular, web cluster systems are modeled taking into account: two error recovery strategies (client transparent and non-client-transparent) as well as two traffic models (Poisson and modulated Poisson). Sensitivity analysis results are presented to show their impact on the web service availability. The obtained results provide useful guidelines to web designers
[en] At Belle II, detector signals are digitized inside or near the detector and collected via high-speed optical serial links. Each frontend digitization board equips an FPGA for a unified data link and timing system interface to receive the system clock, the level-1 trigger, other fast timing signals and to return status signals. Timing signals are serialized and delivered via a commodity category-7 LAN cable, through a tree-structure distribution network made from cascaded 1-to-20 distribution modules. We report the performance of this timing distribution system.
[en] The Industrial Internet of Things (IIoT) is the industrial subset of the Internet of Things (IoT). IIoT incorporates big data technology, harnessing the instrumentation data, machine to machine communication and automation technologies that have existed in industrial settings for years. As industry in general trends towards the IIoT and as the screw compressor packages developed by Howden Compressors are designed with a minimum design life of 25 years, it is imperative this technology is embedded immediately. This paper provides the reader with a description on the Industrial Internet of Things before moving onto describing the scope of the problem for an organisation like Howden Compressors who deploy multiple compressor technologies across multiple locations and focuses on the critical measurements particular to high specification screw compressor packages. A brief analysis of how this differs from high volume package manufacturers deploying similar systems is offered. Then follows a description on how the measured information gets from the tip of the instrument in the process pipework or drive train through the different layers, with a description of each layer, into the final presentation layer. The functions available within the presentation layer are taken in turn and the benefits analysed with specific focus on efficiency and availability. The paper concludes with how packagers adopting the IIoT can not only optimise their package but by utilising the machine learning technology and pattern detection applications can adopt completely new business models. (paper)
[en] The wireless local area networks represent an alternative to custom sensors and dedicated surveillance systems for target indoor detection. The availability of the channel state information has opened the exploitation of the spatial and frequency diversity given by the orthogonal frequency division multiplexing. Such a fine-grained information can be used to solve the detection problem as an inverse scattering problem. The goal of the detection is to reconstruct the properties of the investigation domain, namely to estimate if the domain is empty or occupied by targets, starting from the measurement of the electromagnetic perturbation of the wireless channel. An innovative inversion strategy exploiting both the frequency and the spatial diversity of the channel state information is proposed. The target-dependent features are identified combining the Kruskal-Wallis test and the principal component analysis. The experimental validation points out the detection performance of the proposed method when applied to an existing wireless link of a WiFi architecture deployed in a real indoor scenario. False detection rates lower than 2 [%] have been obtained. (paper)
[en] This paper presents the research developed at Universidad Nacional de Colombia about the e-Manufacturing platform that is being developed and implemented at LabFabEx (acronym in Spanish as "Laboratorio Fabrica Experimental"). This platform besides has an approach to virtual-remote labs that have been tested by several students and engineers of different industrial fields. At this paper it is shown the physical and communication experimental platform, the general scope and characteristics of this e-Manufacturing platform and the virtual lab approach. This research project is funded by COLCIENCIAS (Administrative Department of science, technology and innovation in Colombia) and the enterprise IMOCOM S.A
[en] A review of the state of the Internet in terms of traffic and services trends covering both the Research and Education and the Commercial Internet will first be given. The problematic behind the IPv4 to IPv6 migration will be explained shortly, a short review of the ongoing efforts to re-design the Internet in a clean-slate approach will then be made.
[en] The speed of light is an essential topic in the teaching of physics at school and at university, either with respect to the type of experiment or of course with respect to its genuine inherent importance. In reality, the various available experiments are hardly ever performed in class for many reasons. Therefore, we offer this experiment as a remotely controlled laboratory (RCL). An RCL is a real experiment setup at location A which can be controlled via the Internet by a user at a distant location B. It allows several actions like in the hands-on experiment and delivers convincing results. Finally, we present experiences of the use of the RCL, describe the added value of this experiment as an RCL and give hints for implementing the RCL in teaching.