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The widespread use of computing and communications technologies has enabled the popularity of social networks oriented to learn. In this work, we study the nature and strength of associations between students using an online social network embedded in a learning management system. With datasets from two offerings of the same course, we mined the sequences of questions and answers posted by the students...
Distributed Electronic Systems used for executing concurrently intensive data acquisition (sensing) and control tasks (actuating) are spread thorough several applications. Health-care, automotive, communications, space and other industries are developing and including these systems because of their competitiveness in terms of cost, performance and reliability. Robustness of distributed electronic...
The main body of the literature states that Artificial Neural Networks must be regarded as a "black box" without further interpretation due to the inherent difficulties for analyze the weights and bias terms. Some authors claim that ANN trained as a regression device tend to organize itself by specializing some neurons to learn the main relationships embedded in the training set, while other...
This paper proposes a fuzzy logic based algorithm which decides the best telescope, within a heterogeneous network, taking into account user constraints, weather forecast, visibility and statistical information from every telescope. The main objective of this algorithm is to serve the maximum number of observations as soon as possible, minimizing the reallocation process and improving the selection...
It is commonly accepted that contemporary cohorts of students witness and experience the benefits of information technologies in their learning processes. The so-called “digital natives” acquire, as a consequence of their early exposure to these technologies, different patterns of work, distinct attention conducts, new learning preferences and, generally, better skills for learning and working within...
An indirect proxy is the name of a special kind of component wrapper that is defined within the framework of a hybrid (hardware and software) object-oriented middleware for Systems-on-Chips (SoCs). Which makes indirect proxies so attractive for networked embedded designs is that they do not need to know the physical address of the destination in advance. Regardless the actual place the required functionality...
Single Event Transients (SETs) are soft errors that occur in CMOS circuits as the result of radiation effects. An SET consists in the generation of a short current pulse in the active area of a transistor. In a digital circuit, these events provoke a transient voltage pulse while in analog circuits the effect depends on the kind of affected component. Assuring the fault tolerance behavior under SETs...
Software-Defined Networking (SDN) has gained momentum in recent years, in a bid to transform networking ecosystems. It has already been applied to data center networks and wide area networks, such as Google's WAN. A software-defined approach is thus a reasonable candidate architecture for other highly dynamic environments such as future 5G mobile networks. This paper presents a two-level software-defined...
This study attempted to develop valid, reliable, and good fit model game design scales. The first draft of instrument with fifty items was subjected to statistical analyses. Exploratory factor analysis with factor loadings of at least 0.50 was utilized to determine the dimensions and the validity of constructs. Reliability of items was ensured through Cronbach's alpha analysis. Items with alpha values...
. Permanent faults (e.g., due to electronic components aging) represent a real problem in nowadays digital systems working in automotive vehicles. Mandatory tests should be done at the vehicle key-on in order to detect damaged elements. Generation and validation of these tests can be improved in a great manner considering the characteristics of the target distributed subsystems. In this work, an approach...
. True-random number generators (TRNGs) are being recently defined, designed and prototyped on digital electronic circuits, like part of encryption and decryption algorithms. They provide very interesting results in terms of security and cost. In harsh environments, like aerospace applications, Single Event Upsets (SEUs) are a main concern. TRNGs are currently used in satellite communications to enhance...
It is a known fact that when an AC motor operates below its rated load, its efficiency can be improved by reducing the supply voltage to an appropriate level. This paper proposes an automatic voltage controller that optimizes the efficiency of fractional-horsepower motors when operating under variable load conditions. The scheme is based on perturbing the supply voltage (by controlling the firing...
Digital electronic systems in automotive applications are in charge of different tasks, ranging from very critical control functions (e.g., airbag, ABS, ESP) to comfort services (e.g., handling of mirrors, seats, windows, wipers). Hardening these systems involves suitably trading off cost and reliability. Due to standards and regulations in the area, the reliability of subsystems involved even in...
The growth of Internet traffic and the many different traffic classes that exist make network performance control extremely difficult for operators. The methods available rely on complex or costly hardware. However, recent research on bandwidth sharing has introduced methods that require only basic statistics of aggregated link utilization, such as mean and variance. This data can be easily obtained...
Partial Reconfiguration is one of the most attractive features of FPGAs. This feature provides new computing possibilities, for instance we can change a part of the initial functionality after its deployment, where a complete configuration is not needed, and the total area required is reduced. However, the design of partially reconfigurable systems has been a complex task yet. This work try to facilitate...
Single Event Transients (SETs) are a concern in digital circuits using nanometric technologies. Proposed solutions include the insertion of pulse filtering cells in the circuit, like some C-Element based cells. These filters are usually introduced at flip-flop inputs. In general, protecting every flip-flop with SET filters is a very costly solution in terms of area. Selective hardening of critical...
The design of a decentralized discrete-time block control scheme, for a multi-agent system with a fixed topology, to achieve formation and trajectory tracking is proposed in this work. Each agent dynamics is represented either by a first-order or second-order discrete-time system, only the position of each agent's neighbors is measured and their velocity and acceleration are unknown, and exclusively...
In this paper, the optimal reactive power planning considering uncertainty is presented. The classical deterministic mixed-integer nonlinear model is expanded into two-stage stochastic model with chance-constraint. This new model considers uncertainty on the demand and the equivalent availability of the reactive power sources. The concepts of expected value of perfect information (EVPI) and the value...
Metamaterials are a new kind of artificial media, exhibiting electromagnetic properties not found in nature. In fact, the word “meta” comes from the Greek word meaning “beyond”. Among them, the class of “Left Handed” (LH), also known as “Double Negative” (DNG) metamaterials shows unusual characteristics such as backward waves, negative refraction or reverse Doppler effect. In this paper we will present...
In this paper, the optimal reactive power planning problem under risk is presented. The classical mixed-integer nonlinear model for reactive power planning is expanded into two stage stochastic model considering risk. This new model considers uncertainty on the demand load. The risk is quantified by a factor introduced into the objective function and is identified as the variance of the random variables...
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